text: /*
   * Copyright (c) 2015 Cryptonomex, Inc., and contributors.
   *
   * The MIT License
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  #include <sstream>
  #include <iomanip>
  #include <deque>
  #include <unordered_set>
  #include <list>
  #include <forward_list>
  #include <iostream>
  #include <algorithm>
  #include <tuple>
  #include <boost/tuple/tuple.hpp>
  #include <boost/circular_buffer.hpp>
  
  #include <boost/multi_index_container.hpp>
  #include <boost/multi_index/ordered_index.hpp>
  #include <boost/multi_index/mem_fun.hpp>
  #include <boost/multi_index/member.hpp>
  #include <boost/multi_index/random_access_index.hpp>
  #include <boost/multi_index/tag.hpp>
  #include <boost/multi_index/sequenced_index.hpp>
  #include <boost/multi_index/hashed_index.hpp>
  #include <boost/logic/tribool.hpp>
  #include <boost/range/algorithm_ext/push_back.hpp>
  #include <boost/range/algorithm/find.hpp>
  #include <boost/range/numeric.hpp>
  
  #include <boost/accumulators/accumulators.hpp>
  #include <boost/accumulators/statistics/stats.hpp>
  #include <boost/accumulators/statistics/rolling_mean.hpp>
  #include <boost/accumulators/statistics/min.hpp>
  #include <boost/accumulators/statistics/max.hpp>
  #include <boost/accumulators/statistics/sum.hpp>
  #include <boost/accumulators/statistics/count.hpp>
  
  #include <boost/preprocessor/seq/for_each.hpp>
  #include <boost/preprocessor/cat.hpp>
  #include <boost/preprocessor/stringize.hpp>
  
  #include <fc/thread/thread.hpp>
  #include <fc/thread/future.hpp>
  #include <fc/thread/non_preemptable_scope_check.hpp>
  #include <fc/thread/mutex.hpp>
  #include <fc/thread/scoped_lock.hpp>
  #include <fc/log/logger.hpp>
  #include <fc/io/json.hpp>
  #include <fc/io/enum_type.hpp>
  #include <fc/crypto/rand.hpp>
  #include <fc/network/rate_limiting.hpp>
  #include <fc/network/ip.hpp>
  #include <fc/smart_ref_impl.hpp>
  
  #include <graphene/net/node.hpp>
  #include <graphene/net/peer_database.hpp>
  #include <graphene/net/peer_connection.hpp>
  #include <graphene/net/stcp_socket.hpp>
  #include <graphene/net/config.hpp>
  #include <graphene/net/exceptions.hpp>
  
  #include <graphene/chain/config.hpp>
  #include <graphene/chain/protocol/fee_schedule.hpp>
  
  #include <fc/git_revision.hpp>
  
  //#define ENABLE_DEBUG_ULOGS
  
  #ifdef DEFAULT_LOGGER
  # undef DEFAULT_LOGGER
  #endif
  #define DEFAULT_LOGGER "p2p"
  
  #define P2P_IN_DEDICATED_THREAD 1
  
  #define INVOCATION_COUNTER(name) \
      static unsigned total_ ## name ## _counter = 0; \
      static unsigned active_ ## name ## _counter = 0; \
      struct name ## _invocation_logger { \
        unsigned *total; \
        unsigned *active; \
        name ## _invocation_logger(unsigned *total, unsigned *active) : \
          total(total), active(active) \
        { \
          ++*total; \
          ++*active; \
          dlog("NEWDEBUG: Entering " #name ", now ${total} total calls, ${active} active calls", ("total", *total)("active", *active)); \
        } \
        ~name ## _invocation_logger() \
        { \
          --*active; \
          dlog("NEWDEBUG: Leaving " #name ", now ${total} total calls, ${active} active calls", ("total", *total)("active", *active)); \
        } \
      } invocation_logger(&total_ ## name ## _counter, &active_ ## name ## _counter)
  
  //log these messages even at warn level when operating on the test network
  #ifdef GRAPHENE_TEST_NETWORK
  #define testnetlog wlog
  #else
  #define testnetlog(...) do {} while (0)
  #endif
  
  namespace graphene { namespace net {
  
    namespace detail
    {
      namespace bmi = boost::multi_index;
      class blockchain_tied_message_cache
      {
      private:
        static const uint32_t cache_duration_in_blocks = GRAPHENE_NET_MESSAGE_CACHE_DURATION_IN_BLOCKS;
  
        struct message_hash_index{};
        struct message_contents_hash_index{};
        struct block_clock_index{};
        struct message_info
        {
          message_hash_type message_hash;
          message           message_body;
          uint32_t          block_clock_when_received;
  
          // for network performance stats
          message_propagation_data propagation_data;
          fc::uint160_t     message_contents_hash; // hash of whatever the message contains (if it's a transaction, this is the transaction id, if it's a block, it's the block_id)
  
          message_info( const message_hash_type& message_hash,
                        const message&           message_body,
                        uint32_t                 block_clock_when_received,
                        const message_propagation_data& propagation_data,
                        fc::uint160_t            message_contents_hash ) :
            message_hash( message_hash ),
            message_body( message_body ),
            block_clock_when_received( block_clock_when_received ),
            propagation_data( propagation_data ),
            message_contents_hash( message_contents_hash )
          {}
        };
        typedef boost::multi_index_container
          < message_info,
              bmi::indexed_by< bmi::ordered_unique< bmi::tag<message_hash_index>,
                                                    bmi::member<message_info, message_hash_type, &message_info::message_hash> >,
                               bmi::ordered_non_unique< bmi::tag<message_contents_hash_index>,
                                                        bmi::member<message_info, fc::uint160_t, &message_info::message_contents_hash> >,
                               bmi::ordered_non_unique< bmi::tag<block_clock_index>,
                                                        bmi::member<message_info, uint32_t, &message_info::block_clock_when_received> > >
          > message_cache_container;
  
        message_cache_container _message_cache;
  
        uint32_t block_clock;
  
      public:
        blockchain_tied_message_cache() :
          block_clock( 0 )
        {}
        void block_accepted();
        void cache_message( const message& message_to_cache, const message_hash_type& hash_of_message_to_cache,
                          const message_propagation_data& propagation_data, const fc::uint160_t& message_content_hash );
        message get_message( const message_hash_type& hash_of_message_to_lookup );
        message_propagation_data get_message_propagation_data( const fc::uint160_t& hash_of_message_contents_to_lookup ) const;
        size_t size() const { return _message_cache.size(); }
      };
  
      void blockchain_tied_message_cache::block_accepted()
      {
        ++block_clock;
        if( block_clock > cache_duration_in_blocks )
          _message_cache.get<block_clock_index>().erase(_message_cache.get<block_clock_index>().begin(),
                                                        _message_cache.get<block_clock_index>().lower_bound(block_clock - cache_duration_in_blocks ) );
      }
  
      void blockchain_tied_message_cache::cache_message( const message& message_to_cache,
                                                       const message_hash_type& hash_of_message_to_cache,
                                                       const message_propagation_data& propagation_data,
                                                       const fc::uint160_t& message_content_hash )
      {
        _message_cache.insert( message_info(hash_of_message_to_cache,
                                           message_to_cache,
                                           block_clock,
                                           propagation_data,
                                           message_content_hash ) );
      }
  
      message blockchain_tied_message_cache::get_message( const message_hash_type& hash_of_message_to_lookup )
      {
        message_cache_container::index<message_hash_index>::type::const_iterator iter =
           _message_cache.get<message_hash_index>().find(hash_of_message_to_lookup );
        if( iter != _message_cache.get<message_hash_index>().end() )
          return iter->message_body;
        FC_THROW_EXCEPTION(  fc::key_not_found_exception, "Requested message not in cache" );
      }
  
      message_propagation_data blockchain_tied_message_cache::get_message_propagation_data( const fc::uint160_t& hash_of_message_contents_to_lookup ) const
      {
        if( hash_of_message_contents_to_lookup != fc::uint160_t() )
        {
          message_cache_container::index<message_contents_hash_index>::type::const_iterator iter =
             _message_cache.get<message_contents_hash_index>().find(hash_of_message_contents_to_lookup );
          if( iter != _message_cache.get<message_contents_hash_index>().end() )
            return iter->propagation_data;
        }
        FC_THROW_EXCEPTION(  fc::key_not_found_exception, "Requested message not in cache" );
      }
  
  /////////////////////////////////////////////////////////////////////////////////////////////////////////
  
      // This specifies configuration info for the local node.  It's stored as JSON
      // in the configuration directory (application data directory)
      struct node_configuration
      {
        node_configuration() : accept_incoming_connections(true), wait_if_endpoint_is_busy(true) {}
  
        fc::ip::endpoint listen_endpoint;
        bool accept_incoming_connections;
        bool wait_if_endpoint_is_busy;
        /**
         * Originally, our p2p code just had a 'node-id' that was a random number identifying this node
         * on the network.  This is now a private key/public key pair, where the public key is used
         * in place of the old random node-id.  The private part is unused, but might be used in
         * the future to support some notion of trusted peers.
         */
        fc::ecc::private_key private_key;
      };
  
  
  } } } // end namespace graphene::net::detail
  FC_REFLECT(graphene::net::detail::node_configuration, (listen_endpoint)
                                                   (accept_incoming_connections)
                                                   (wait_if_endpoint_is_busy)
                                                   (private_key));
  
  namespace graphene { namespace net { namespace detail {
  
      // when requesting items from peers, we want to prioritize any blocks before
      // transactions, but otherwise request items in the order we heard about them
      struct prioritized_item_id
      {
        item_id  item;
        unsigned sequence_number;
        fc::time_point timestamp; // the time we last heard about this item in an inventory message
  
        prioritized_item_id(const item_id& item, unsigned sequence_number) :
          item(item),
          sequence_number(sequence_number),
          timestamp(fc::time_point::now())
        {}
        bool operator<(const prioritized_item_id& rhs) const
        {
          static_assert(graphene::net::block_message_type > graphene::net::trx_message_type,
                        "block_message_type must be greater than trx_message_type for prioritized_item_ids to sort correctly");
          if (item.item_type != rhs.item.item_type)
            return item.item_type > rhs.item.item_type;
          return (signed)(rhs.sequence_number - sequence_number) > 0;
        }
      };
  
  /////////////////////////////////////////////////////////////////////////////////////////////////////////
      class statistics_gathering_node_delegate_wrapper : public node_delegate
      {
      private:
        node_delegate *_node_delegate;
        fc::thread *_thread;
  
        typedef boost::accumulators::accumulator_set<int64_t, boost::accumulators::stats<boost::accumulators::tag::min,
                                                                                         boost::accumulators::tag::rolling_mean,
                                                                                         boost::accumulators::tag::max,
                                                                                         boost::accumulators::tag::sum,
                                                                                         boost::accumulators::tag::count> > call_stats_accumulator;
  #define NODE_DELEGATE_METHOD_NAMES (has_item) \
                                     (handle_message) \
                                     (handle_block) \
                                     (handle_transaction) \
                                     (get_block_ids) \
                                     (get_item) \
                                     (get_chain_id) \
                                     (get_blockchain_synopsis) \
                                     (sync_status) \
                                     (connection_count_changed) \
                                     (get_block_number) \
                                     (get_block_time) \
                                     (get_head_block_id) \
                                     (estimate_last_known_fork_from_git_revision_timestamp) \
                                     (error_encountered) \
                                     (get_current_block_interval_in_seconds)
  
  
  #define DECLARE_ACCUMULATOR(r, data, method_name) \
        mutable call_stats_accumulator BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _execution_accumulator)); \
        mutable call_stats_accumulator BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _delay_before_accumulator)); \
        mutable call_stats_accumulator BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _delay_after_accumulator));
        BOOST_PP_SEQ_FOR_EACH(DECLARE_ACCUMULATOR, unused, NODE_DELEGATE_METHOD_NAMES)
  #undef DECLARE_ACCUMULATOR
  
        class call_statistics_collector
        {
        private:
          fc::time_point _call_requested_time;
          fc::time_point _begin_execution_time;
          fc::time_point _execution_completed_time;
          const char* _method_name;
          call_stats_accumulator* _execution_accumulator;
          call_stats_accumulator* _delay_before_accumulator;
          call_stats_accumulator* _delay_after_accumulator;
        public:
          class actual_execution_measurement_helper
          {
            call_statistics_collector &_collector;
          public:
            actual_execution_measurement_helper(call_statistics_collector& collector) :
              _collector(collector)
            {
              _collector.starting_execution();
            }
            ~actual_execution_measurement_helper()
            {
              _collector.execution_completed();
            }
          };
          call_statistics_collector(const char* method_name,
                                    call_stats_accumulator* execution_accumulator,
                                    call_stats_accumulator* delay_before_accumulator,
                                    call_stats_accumulator* delay_after_accumulator) :
            _call_requested_time(fc::time_point::now()),
            _method_name(method_name),
            _execution_accumulator(execution_accumulator),
            _delay_before_accumulator(delay_before_accumulator),
            _delay_after_accumulator(delay_after_accumulator)
          {}
          ~call_statistics_collector()
          {
            fc::time_point end_time(fc::time_point::now());
            fc::microseconds actual_execution_time(_execution_completed_time - _begin_execution_time);
            fc::microseconds delay_before(_begin_execution_time - _call_requested_time);
            fc::microseconds delay_after(end_time - _execution_completed_time);
            fc::microseconds total_duration(actual_execution_time + delay_before + delay_after);
            (*_execution_accumulator)(actual_execution_time.count());
            (*_delay_before_accumulator)(delay_before.count());
            (*_delay_after_accumulator)(delay_after.count());
            if (total_duration > fc::milliseconds(500))
            {
              ilog("Call to method node_delegate::${method} took ${total_duration}us, longer than our target maximum of 500ms",
                   ("method", _method_name)
                   ("total_duration", total_duration.count()));
              ilog("Actual execution took ${execution_duration}us, with a ${delegate_delay}us delay before the delegate thread started "
                   "executing the method, and a ${p2p_delay}us delay after it finished before the p2p thread started processing the response",
                   ("execution_duration", actual_execution_time)
                   ("delegate_delay", delay_before)
                   ("p2p_delay", delay_after));
            }
          }
          void starting_execution()
          {
            _begin_execution_time = fc::time_point::now();
          }
          void execution_completed()
          {
            _execution_completed_time = fc::time_point::now();
          }
        };
      public:
        statistics_gathering_node_delegate_wrapper(node_delegate* delegate, fc::thread* thread_for_delegate_calls);
  
        fc::variant_object get_call_statistics();
  
        bool has_item( const net::item_id& id ) override;
        void handle_message( const message& ) override;
        bool handle_block( const graphene::net::block_message& block_message, bool sync_mode, std::vector<fc::uint160_t>& contained_transaction_message_ids ,bool stoppable=false) override;
        void handle_transaction( const graphene::net::trx_message& transaction_message ) override;
        std::vector<item_hash_t> get_block_ids(const std::vector<item_hash_t>& blockchain_synopsis,
                                               uint32_t& remaining_item_count,
                                               uint32_t limit = 2000) override;
        message get_item( const item_id& id ) override;
        chain_id_type get_chain_id() const override;
        std::vector<item_hash_t> get_blockchain_synopsis(const item_hash_t& reference_point, 
                                                         uint32_t number_of_blocks_after_reference_point) override;
        void     sync_status( uint32_t item_type, uint32_t item_count ) override;
        void     connection_count_changed( uint32_t c ) override;
        uint32_t get_block_number(const item_hash_t& block_id) override;
        fc::time_point_sec get_block_time(const item_hash_t& block_id) override;
        item_hash_t get_head_block_id() const override;
        uint32_t estimate_last_known_fork_from_git_revision_timestamp(uint32_t unix_timestamp) const override;
        void error_encountered(const std::string& message, const fc::oexception& error) override;
        uint8_t get_current_block_interval_in_seconds() const override;
      };
  
  /////////////////////////////////////////////////////////////////////////////////////////////////////////
  
      class node_impl : public peer_connection_delegate
      {
      public:
  #ifdef P2P_IN_DEDICATED_THREAD
        std::shared_ptr<fc::thread> _thread;
  #endif // P2P_IN_DEDICATED_THREAD
        std::unique_ptr<statistics_gathering_node_delegate_wrapper> _delegate;
        fc::sha256           _chain_id;
  
  #define NODE_CONFIGURATION_FILENAME      "node_config.json"
  #define POTENTIAL_PEER_DATABASE_FILENAME "peers.json"
        fc::path             _node_configuration_directory;
        node_configuration   _node_configuration;
  
        /// stores the endpoint we're listening on.  This will be the same as
        // _node_configuration.listen_endpoint, unless that endpoint was already
        // in use.
        fc::ip::endpoint     _actual_listening_endpoint;
  
        /// we determine whether we're firewalled by asking other nodes.  Store the result here:
        firewalled_state     _is_firewalled;
        /// if we're behind NAT, our listening endpoint address will appear different to the rest of the world.  store it here.
        fc::optional<fc::ip::endpoint> _publicly_visible_listening_endpoint;
        fc::time_point       _last_firewall_check_message_sent;
  
        /// used by the task that manages connecting to peers
        // @{
        std::list<potential_peer_record> _add_once_node_list; /// list of peers we want to connect to as soon as possible
  
        peer_database             _potential_peer_db;
        fc::promise<void>::ptr    _retrigger_connect_loop_promise;
        bool                      _potential_peer_database_updated;
        fc::future<void>          _p2p_network_connect_loop_done;
        // @}
  
        /// used by the task that fetches sync items during synchronization
        // @{
        fc::promise<void>::ptr    _retrigger_fetch_sync_items_loop_promise;
        bool                      _sync_items_to_fetch_updated;
        fc::future<void>          _fetch_sync_items_loop_done;
  
        typedef std::unordered_map<graphene::net::block_id_type, fc::time_point> active_sync_requests_map;
  
        active_sync_requests_map              _active_sync_requests; /// list of sync blocks we've asked for from peers but have not yet received
        std::list<graphene::net::block_message> _new_received_sync_items; /// list of sync blocks we've just received but haven't yet tried to process
        std::list<graphene::net::block_message> _received_sync_items; /// list of sync blocks we've received, but can't yet process because we are still missing blocks that come earlier in the chain
        // @}
  
        fc::future<void> _process_backlog_of_sync_blocks_done;
        bool _suspend_fetching_sync_blocks;
  
        /// used by the task that fetches items during normal operation
        // @{
        fc::promise<void>::ptr _retrigger_fetch_item_loop_promise;
        bool                   _items_to_fetch_updated;
        fc::future<void>       _fetch_item_loop_done;
  
        struct item_id_index{};
        typedef boost::multi_index_container<prioritized_item_id,
                                             boost::multi_index::indexed_by<boost::multi_index::ordered_unique<boost::multi_index::identity<prioritized_item_id> >,
                                                                            boost::multi_index::hashed_unique<boost::multi_index::tag<item_id_index>, 
                                                                                                              boost::multi_index::member<prioritized_item_id, item_id, &prioritized_item_id::item>,
                                                                                                              std::hash<item_id> > >
                                             > items_to_fetch_set_type;
        unsigned _items_to_fetch_sequence_counter;
        items_to_fetch_set_type _items_to_fetch; /// list of items we know another peer has and we want
        peer_connection::timestamped_items_set_type _recently_failed_items; /// list of transactions we've recently pushed and had rejected by the delegate
        // @}
  
        /// used by the task that advertises inventory during normal operation
        // @{
        fc::promise<void>::ptr        _retrigger_advertise_inventory_loop_promise;
        fc::future<void>              _advertise_inventory_loop_done;
        std::unordered_set<item_id>   _new_inventory; /// list of items we have received but not yet advertised to our peers
        // @}
  
        fc::future<void>     _terminate_inactive_connections_loop_done;
        uint8_t _recent_block_interval_in_seconds; // a cached copy of the block interval, to avoid a thread hop to the blockchain to get the current value
  
        std::string          _user_agent_string;
        /** _node_public_key is a key automatically generated when the client is first run, stored in
         * node_config.json.  It doesn't really have much of a purpose yet, there was just some thought
         * that we might someday have a use for nodes having a private key (sent in hello messages)
         */
        node_id_t            _node_public_key;
        /**
         * _node_id is a random number generated each time the client is launched, used to prevent us
         * from connecting to the same client multiple times (sent in hello messages).
         * Since this was introduced after the hello_message was finalized, this is sent in the
         * user_data field.
         * While this shares the same underlying type as a public key, it is really just a random
         * number.
         */
        node_id_t            _node_id;
  
        /** if we have less than `_desired_number_of_connections`, we will try to connect with more nodes */
        uint32_t             _desired_number_of_connections;
        /** if we have _maximum_number_of_connections or more, we will refuse any inbound connections */
        uint32_t             _maximum_number_of_connections;
        /** retry connections to peers that have failed or rejected us this often, in seconds */
        uint32_t              _peer_connection_retry_timeout;
        /** how many seconds of inactivity are permitted before disconnecting a peer */
        uint32_t              _peer_inactivity_timeout;
  
        fc::tcp_server       _tcp_server;
        fc::future<void>     _accept_loop_complete;
  
        /** Stores all connections which have not yet finished key exchange or are still sending initial handshaking messages
         * back and forth (not yet ready to initiate syncing) */
        std::unordered_set<peer_connection_ptr>                     _handshaking_connections;
        /** stores fully established connections we're either syncing with or in normal operation with */
        std::unordered_set<peer_connection_ptr>                     _active_connections;
        /** stores connections we've closed (sent closing message, not actually closed), but are still waiting for the remote end to close before we delete them */
        std::unordered_set<peer_connection_ptr>                     _closing_connections;
        /** stores connections we've closed, but are still waiting for the OS to notify us that the socket is really closed */
        std::unordered_set<peer_connection_ptr>                     _terminating_connections;
  
        boost::circular_buffer<item_hash_t> _most_recent_blocks_accepted; // the /n/ most recent blocks we've accepted (currently tuned to the max number of connections)
  
        uint32_t _sync_item_type;
        uint32_t _total_number_of_unfetched_items; /// the number of items we still need to fetch while syncing
        std::vector<uint32_t> _hard_fork_block_numbers; /// list of all block numbers where there are hard forks
  
        blockchain_tied_message_cache _message_cache; /// cache message we have received and might be required to provide to other peers via inventory requests
  
        fc::rate_limiting_group _rate_limiter;
  
        uint32_t _last_reported_number_of_connections; // number of connections last reported to the client (to avoid sending duplicate messages)
  
        bool _peer_advertising_disabled;
  
        fc::future<void> _fetch_updated_peer_lists_loop_done;
  
        boost::circular_buffer<uint32_t> _average_network_read_speed_seconds;
        boost::circular_buffer<uint32_t> _average_network_write_speed_seconds;
        boost::circular_buffer<uint32_t> _average_network_read_speed_minutes;
        boost::circular_buffer<uint32_t> _average_network_write_speed_minutes;
        boost::circular_buffer<uint32_t> _average_network_read_speed_hours;
        boost::circular_buffer<uint32_t> _average_network_write_speed_hours;
        unsigned _average_network_usage_second_counter;
        unsigned _average_network_usage_minute_counter;
  
        fc::time_point_sec _bandwidth_monitor_last_update_time;
        fc::future<void> _bandwidth_monitor_loop_done;
  
        fc::future<void> _dump_node_status_task_done;
  
        /* We have two alternate paths through the schedule_peer_for_deletion code -- one that
         * uses a mutex to prevent one fiber from adding items to the queue while another is deleting
         * items from it, and one that doesn't.  The one that doesn't is simpler and more efficient
         * code, but we're keeping around the version that uses the mutex because it crashes, and
         * this crash probably indicates a bug in our underlying threading code that needs
         * fixing.  To produce the bug, define USE_PEERS_TO_DELETE_MUTEX and then connect up
         * to the network and set your desired/max connection counts high
         */
  //#define USE_PEERS_TO_DELETE_MUTEX 1
  #ifdef USE_PEERS_TO_DELETE_MUTEX
        fc::mutex _peers_to_delete_mutex;
  #endif
        std::list<peer_connection_ptr> _peers_to_delete;
        fc::future<void> _delayed_peer_deletion_task_done;
  
  #ifdef ENABLE_P2P_DEBUGGING_API
        std::set<node_id_t> _allowed_peers;
  #endif // ENABLE_P2P_DEBUGGING_API
  
        bool _node_is_shutting_down; // set to true when we begin our destructor, used to prevent us from starting new tasks while we're shutting down
  
        unsigned _maximum_number_of_blocks_to_handle_at_one_time;
        unsigned _maximum_number_of_sync_blocks_to_prefetch;
        unsigned _maximum_blocks_per_peer_during_syncing;
  
        std::list<fc::future<void> > _handle_message_calls_in_progress;
  
        node_impl(const std::string& user_agent);
        virtual ~node_impl();
  
        void save_node_configuration();
  
        void p2p_network_connect_loop();
        void trigger_p2p_network_connect_loop();
  
        bool have_already_received_sync_item( const item_hash_t& item_hash );
        void request_sync_item_from_peer( const peer_connection_ptr& peer, const item_hash_t& item_to_request );
        void request_sync_items_from_peer( const peer_connection_ptr& peer, const std::vector<item_hash_t>& items_to_request );
        void fetch_sync_items_loop();
        void trigger_fetch_sync_items_loop();
  
        bool is_item_in_any_peers_inventory(const item_id& item) const;
        void fetch_items_loop();
        void trigger_fetch_items_loop();
  
        void advertise_inventory_loop();
        void trigger_advertise_inventory_loop();
  
        void terminate_inactive_connections_loop();
  
        void fetch_updated_peer_lists_loop();
        void update_bandwidth_data(uint32_t bytes_read_this_second, uint32_t bytes_written_this_second);
        void bandwidth_monitor_loop();
        void dump_node_status_task();
  
        bool is_accepting_new_connections();
        bool is_wanting_new_connections();
        uint32_t get_number_of_connections();
        peer_connection_ptr get_peer_by_node_id(const node_id_t& id);
  
        bool is_already_connected_to_id(const node_id_t& node_id);
        bool merge_address_info_with_potential_peer_database( const std::vector<address_info> addresses );
        void display_current_connections();
        uint32_t calculate_unsynced_block_count_from_all_peers();
        std::vector<item_hash_t> create_blockchain_synopsis_for_peer( const peer_connection* peer );
        void fetch_next_batch_of_item_ids_from_peer( peer_connection* peer, bool reset_fork_tracking_data_for_peer = false );
  
        fc::variant_object generate_hello_user_data();
        void parse_hello_user_data_for_peer( peer_connection* originating_peer, const fc::variant_object& user_data );
  
        void on_message( peer_connection* originating_peer,
                         const message& received_message ) override;
  
        void on_hello_message( peer_connection* originating_peer,
                               const hello_message& hello_message_received );
  
        void on_connection_accepted_message( peer_connection* originating_peer,
                                             const connection_accepted_message& connection_accepted_message_received );
  
        void on_connection_rejected_message( peer_connection* originating_peer,
                                             const connection_rejected_message& connection_rejected_message_received );
  
        void on_address_request_message( peer_connection* originating_peer,
                                         const address_request_message& address_request_message_received );
  
        void on_address_message( peer_connection* originating_peer,
                                 const address_message& address_message_received );
  
        void on_fetch_blockchain_item_ids_message( peer_connection* originating_peer,
                                                   const fetch_blockchain_item_ids_message& fetch_blockchain_item_ids_message_received );
  
        void on_blockchain_item_ids_inventory_message( peer_connection* originating_peer,
                                                       const blockchain_item_ids_inventory_message& blockchain_item_ids_inventory_message_received );
  
        void on_fetch_items_message( peer_connection* originating_peer,
                                     const fetch_items_message& fetch_items_message_received );
  
        void on_item_not_available_message( peer_connection* originating_peer,
                                            const item_not_available_message& item_not_available_message_received );
  
        void on_item_ids_inventory_message( peer_connection* originating_peer,
                                            const item_ids_inventory_message& item_ids_inventory_message_received );
  
        void on_closing_connection_message( peer_connection* originating_peer,
                                            const closing_connection_message& closing_connection_message_received );
  
        void on_current_time_request_message( peer_connection* originating_peer,
                                              const current_time_request_message& current_time_request_message_received );
  
        void on_current_time_reply_message( peer_connection* originating_peer,
                                            const current_time_reply_message& current_time_reply_message_received );
  
        void forward_firewall_check_to_next_available_peer(firewall_check_state_data* firewall_check_state);
  
        void on_check_firewall_message(peer_connection* originating_peer,
                                       const check_firewall_message& check_firewall_message_received);
  
        void on_check_firewall_reply_message(peer_connection* originating_peer,
                                             const check_firewall_reply_message& check_firewall_reply_message_received);
  
        void on_get_current_connections_request_message(peer_connection* originating_peer,
                                                        const get_current_connections_request_message& get_current_connections_request_message_received);
  
        void on_get_current_connections_reply_message(peer_connection* originating_peer,
                                                      const get_current_connections_reply_message& get_current_connections_reply_message_received);
  
        void on_connection_closed(peer_connection* originating_peer) override;
  
        void send_sync_block_to_node_delegate(const graphene::net::block_message& block_message_to_send);
        void process_backlog_of_sync_blocks();
        void trigger_process_backlog_of_sync_blocks();
        void process_block_during_sync(peer_connection* originating_peer, const graphene::net::block_message& block_message, const message_hash_type& message_hash);
        void process_block_during_normal_operation(peer_connection* originating_peer, const graphene::net::block_message& block_message, const message_hash_type& message_hash);
        void process_block_message(peer_connection* originating_peer, const message& message_to_process, const message_hash_type& message_hash);
  
        void process_ordinary_message(peer_connection* originating_peer, const message& message_to_process, const message_hash_type& message_hash);
  
        void start_synchronizing();
        void start_synchronizing_with_peer(const peer_connection_ptr& peer);
  
        void new_peer_just_added(const peer_connection_ptr& peer); /// called after a peer finishes handshaking, kicks off syncing
  
        void close();
  
        void accept_connection_task(peer_connection_ptr new_peer);
        void accept_loop();
        void send_hello_message(const peer_connection_ptr& peer);
        void connect_to_task(peer_connection_ptr new_peer, const fc::ip::endpoint& remote_endpoint);
        bool is_connection_to_endpoint_in_progress(const fc::ip::endpoint& remote_endpoint);
  
        void move_peer_to_active_list(const peer_connection_ptr& peer);
        void move_peer_to_closing_list(const peer_connection_ptr& peer);
        void move_peer_to_terminating_list(const peer_connection_ptr& peer);
  
        peer_connection_ptr get_connection_to_endpoint( const fc::ip::endpoint& remote_endpoint );
  
        void dump_node_status();
  
        void delayed_peer_deletion_task();
        void schedule_peer_for_deletion(const peer_connection_ptr& peer_to_delete);
  
        void disconnect_from_peer( peer_connection* originating_peer,
                                 const std::string& reason_for_disconnect,
                                  bool caused_by_error = false,
                                 const fc::oexception& additional_data = fc::oexception() );
  
        // methods implementing node's public interface
        void set_node_delegate(node_delegate* del, fc::thread* thread_for_delegate_calls);
        void load_configuration( const fc::path& configuration_directory );
        void listen_to_p2p_network();
        void connect_to_p2p_network();
        void add_node( const fc::ip::endpoint& ep );
        void initiate_connect_to(const peer_connection_ptr& peer);
        void connect_to_endpoint(const fc::ip::endpoint& ep);
        void listen_on_endpoint(const fc::ip::endpoint& ep , bool wait_if_not_available);
        void accept_incoming_connections(bool accept);
        void listen_on_port( uint16_t port, bool wait_if_not_available );
  
        fc::ip::endpoint         get_actual_listening_endpoint() const;
        std::vector<peer_status> get_connected_peers() const;
        uint32_t                 get_connection_count() const;
  
        void broadcast(const message& item_to_broadcast, const message_propagation_data& propagation_data);
        void broadcast(const message& item_to_broadcast);
        void sync_from(const item_id& current_head_block, const std::vector<uint32_t>& hard_fork_block_numbers);
        bool is_connected() const;
        std::vector<potential_peer_record> get_potential_peers() const;
        void set_advanced_node_parameters( const fc::variant_object& params );
  
        fc::variant_object         get_advanced_node_parameters();
        message_propagation_data   get_transaction_propagation_data( const graphene::net::transaction_id_type& transaction_id );
        message_propagation_data   get_block_propagation_data( const graphene::net::block_id_type& block_id );
  
        node_id_t                  get_node_id() const;
        void                       set_allowed_peers( const std::vector<node_id_t>& allowed_peers );
        void                       clear_peer_database();
        void                       set_total_bandwidth_limit( uint32_t upload_bytes_per_second, uint32_t download_bytes_per_second );
        void                       disable_peer_advertising();
        fc::variant_object         get_call_statistics() const;
        message                    get_message_for_item(const item_id& item) override;
  
        fc::variant_object         network_get_info() const;
        fc::variant_object         network_get_usage_stats() const;
  
        bool is_hard_fork_block(uint32_t block_number) const;
        uint32_t get_next_known_hard_fork_block_number(uint32_t block_number) const;
      }; // end class node_impl
  
      ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
      ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  
      void node_impl_deleter::operator()(node_impl* impl_to_delete)
      {
  #ifdef P2P_IN_DEDICATED_THREAD
        std::weak_ptr<fc::thread> weak_thread;
        if (impl_to_delete)
        {
          std::shared_ptr<fc::thread> impl_thread(impl_to_delete->_thread);
          weak_thread = impl_thread;
          impl_thread->async([impl_to_delete](){ delete impl_to_delete; }, "delete node_impl").wait();
          dlog("deleting the p2p thread");
        }
        if (weak_thread.expired())
          dlog("done deleting the p2p thread");
        else
          dlog("failed to delete the p2p thread, we must be leaking a smart pointer somewhere");
  #else // P2P_IN_DEDICATED_THREAD
        delete impl_to_delete;
  #endif // P2P_IN_DEDICATED_THREAD
      }
  
  #ifdef P2P_IN_DEDICATED_THREAD
  # define VERIFY_CORRECT_THREAD() assert(_thread->is_current())
  #else
  # define VERIFY_CORRECT_THREAD() do {} while (0)
  #endif
  
  #define MAXIMUM_NUMBER_OF_BLOCKS_TO_HANDLE_AT_ONE_TIME 200
  #define MAXIMUM_NUMBER_OF_BLOCKS_TO_PREFETCH (10 * MAXIMUM_NUMBER_OF_BLOCKS_TO_HANDLE_AT_ONE_TIME)
  
      node_impl::node_impl(const std::string& user_agent) :
  #ifdef P2P_IN_DEDICATED_THREAD
        _thread(std::make_shared<fc::thread>("p2p")),
  #endif // P2P_IN_DEDICATED_THREAD
        _delegate(nullptr),
        _is_firewalled(firewalled_state::unknown),
        _potential_peer_database_updated(false),
        _sync_items_to_fetch_updated(false),
        _suspend_fetching_sync_blocks(false),
        _items_to_fetch_updated(false),
        _items_to_fetch_sequence_counter(0),
        _recent_block_interval_in_seconds(GRAPHENE_MAX_BLOCK_INTERVAL),
        _user_agent_string(user_agent),
        _desired_number_of_connections(GRAPHENE_NET_DEFAULT_DESIRED_CONNECTIONS),
        _maximum_number_of_connections(GRAPHENE_NET_DEFAULT_MAX_CONNECTIONS),
        _peer_connection_retry_timeout(GRAPHENE_NET_DEFAULT_PEER_CONNECTION_RETRY_TIME),
        _peer_inactivity_timeout(GRAPHENE_NET_PEER_HANDSHAKE_INACTIVITY_TIMEOUT),
        _most_recent_blocks_accepted(_maximum_number_of_connections),
        _total_number_of_unfetched_items(0),
        _rate_limiter(0, 0),
        _last_reported_number_of_connections(0),
        _peer_advertising_disabled(false),
        _average_network_read_speed_seconds(60),
        _average_network_write_speed_seconds(60),
        _average_network_read_speed_minutes(60),
        _average_network_write_speed_minutes(60),
        _average_network_read_speed_hours(72),
        _average_network_write_speed_hours(72),
        _average_network_usage_second_counter(0),
        _average_network_usage_minute_counter(0),
        _node_is_shutting_down(false),
        _maximum_number_of_blocks_to_handle_at_one_time(MAXIMUM_NUMBER_OF_BLOCKS_TO_HANDLE_AT_ONE_TIME),
        _maximum_number_of_sync_blocks_to_prefetch(MAXIMUM_NUMBER_OF_BLOCKS_TO_PREFETCH),
        _maximum_blocks_per_peer_during_syncing(GRAPHENE_NET_MAX_BLOCKS_PER_PEER_DURING_SYNCING)
      {
        _rate_limiter.set_actual_rate_time_constant(fc::seconds(2));
        fc::rand_pseudo_bytes(&_node_id.data[0], (int)_node_id.size());
      }
  
      node_impl::~node_impl()
      {
        VERIFY_CORRECT_THREAD();
        ilog( "cleaning up node" );
        _node_is_shutting_down = true;
  
        for (const peer_connection_ptr& active_peer : _active_connections)
        {
          fc::optional<fc::ip::endpoint> inbound_endpoint = active_peer->get_endpoint_for_connecting();
          if (inbound_endpoint)
          {
            fc::optional<potential_peer_record> updated_peer_record = _potential_peer_db.lookup_entry_for_endpoint(*inbound_endpoint);
            if (updated_peer_record)
            {
              updated_peer_record->last_seen_time = fc::time_point::now();
              _potential_peer_db.update_entry(*updated_peer_record);
            }
          }
        }
  
        try
        {
          ilog( "close" );
          close();
        }
        catch ( const fc::exception& e )
        {
          wlog( "unexpected exception on close ${e}", ("e", e) );
        }
        ilog( "done" );
      }
  
      void node_impl::save_node_configuration()
      {
        VERIFY_CORRECT_THREAD();
        if( fc::exists(_node_configuration_directory ) )
        {
          fc::path configuration_file_name( _node_configuration_directory / NODE_CONFIGURATION_FILENAME );
          try
          {
            fc::json::save_to_file( _node_configuration, configuration_file_name );
          }
          catch (const fc::canceled_exception&)
          {
            throw;
          }
          catch ( const fc::exception& except )
          {
            elog( "error writing node configuration to file ${filename}: ${error}",
                 ( "filename", configuration_file_name )("error", except.to_detail_string() ) );
          }
        }
      }
  
      void node_impl::p2p_network_connect_loop()
      {
        VERIFY_CORRECT_THREAD();
        while (!_p2p_network_connect_loop_done.canceled())
        {
          try
          {
            dlog("Starting an iteration of p2p_network_connect_loop().");
            display_current_connections();
  
            // add-once peers bypass our checks on the maximum/desired number of connections (but they will still be counted against the totals once they're connected)
            if (!_add_once_node_list.empty())
            {
              std::list<potential_peer_record> add_once_node_list;
              add_once_node_list.swap(_add_once_node_list);
              dlog("Processing \"add once\" node list containing ${count} peers:", ("count", add_once_node_list.size()));
              for (const potential_peer_record& add_once_peer : add_once_node_list)
              {
                dlog("    ${peer}", ("peer", add_once_peer.endpoint));
              }
              for (const potential_peer_record& add_once_peer : add_once_node_list)
              {
                // see if we have an existing connection to that peer.  If we do, disconnect them and
                // then try to connect the next time through the loop
                peer_connection_ptr existing_connection_ptr = get_connection_to_endpoint( add_once_peer.endpoint );
                if(!existing_connection_ptr)
                  connect_to_endpoint(add_once_peer.endpoint);
              }
              dlog("Done processing \"add once\" node list");
            }
  
            while (is_wanting_new_connections())
            {
              bool initiated_connection_this_pass = false;
              _potential_peer_database_updated = false;
  
              for (peer_database::iterator iter = _potential_peer_db.begin();
                   iter != _potential_peer_db.end() && is_wanting_new_connections();
                   ++iter)
              {
                fc::microseconds delay_until_retry = fc::seconds((iter->number_of_failed_connection_attempts + 1) * _peer_connection_retry_timeout);
  
                if (!is_connection_to_endpoint_in_progress(iter->endpoint) &&
                    ((iter->last_connection_disposition != last_connection_failed &&
                      iter->last_connection_disposition != last_connection_rejected &&
                      iter->last_connection_disposition != last_connection_handshaking_failed) ||
                     (fc::time_point::now() - iter->last_connection_attempt_time) > delay_until_retry))
                {
                  connect_to_endpoint(iter->endpoint);
                  initiated_connection_this_pass = true;
                }
              }
  
              if (!initiated_connection_this_pass && !_potential_peer_database_updated)
                break;
            }
  
            display_current_connections();
  
            // if we broke out of the while loop, that means either we have connected to enough nodes, or
            // we don't have any good candidates to connect to right now.
  #if 0
            try
            {
              _retrigger_connect_loop_promise = fc::promise<void>::ptr( new fc::promise<void>("graphene::net::retrigger_connect_loop") );
              if( is_wanting_new_connections() || !_add_once_node_list.empty() )
              {
                if( is_wanting_new_connections() )
                  dlog( "Still want to connect to more nodes, but I don't have any good candidates.  Trying again in 15 seconds" );
                else
                  dlog( "I still have some \"add once\" nodes to connect to.  Trying again in 15 seconds" );
                _retrigger_connect_loop_promise->wait_until( fc::time_point::now() + fc::seconds(GRAPHENE_PEER_DATABASE_RETRY_DELAY ) );
              }
              else
              {
                dlog( "I don't need any more connections, waiting forever until something changes" );
                _retrigger_connect_loop_promise->wait();
              }
            }
            catch ( fc::timeout_exception& ) //intentionally not logged
            {
            }  // catch
  #else
            fc::usleep(fc::seconds(10));
  #endif
          }
          catch (const fc::canceled_exception&)
          {
            throw;
          }
          FC_CAPTURE_AND_LOG( (0) )
        }// while(!canceled)
      }
  
      void node_impl::trigger_p2p_network_connect_loop()
      {
        VERIFY_CORRECT_THREAD();
        dlog( "Triggering connect loop now" );
        _potential_peer_database_updated = true;
        //if( _retrigger_connect_loop_promise )
        //  _retrigger_connect_loop_promise->set_value();
      }
  
      bool node_impl::have_already_received_sync_item( const item_hash_t& item_hash )
      {
        VERIFY_CORRECT_THREAD();
        return std::find_if(_received_sync_items.begin(), _received_sync_items.end(),
                            [&item_hash]( const graphene::net::block_message& message ) { return message.block_id == item_hash; } ) != _received_sync_items.end() ||
               std::find_if(_new_received_sync_items.begin(), _new_received_sync_items.end(),
                            [&item_hash]( const graphene::net::block_message& message ) { return message.block_id == item_hash; } ) != _new_received_sync_items.end();                          ;
      }
  
      void node_impl::request_sync_item_from_peer( const peer_connection_ptr& peer, const item_hash_t& item_to_request )
      {
        VERIFY_CORRECT_THREAD();
        dlog( "requesting item ${item_hash} from peer ${endpoint}", ("item_hash", item_to_request )("endpoint", peer->get_remote_endpoint() ) );
        item_id item_id_to_request( graphene::net::block_message_type, item_to_request );
        _active_sync_requests.insert( active_sync_requests_map::value_type(item_to_request, fc::time_point::now() ) );
        peer->sync_items_requested_from_peer.insert( peer_connection::item_to_time_map_type::value_type(item_id_to_request, fc::time_point::now() ) );
        std::vector<item_hash_t> items_to_fetch;
        peer->send_message( fetch_items_message(item_id_to_request.item_type, std::vector<item_hash_t>{item_id_to_request.item_hash} ) );
      }
  
      void node_impl::request_sync_items_from_peer( const peer_connection_ptr& peer, const std::vector<item_hash_t>& items_to_request )
      {
        VERIFY_CORRECT_THREAD();
        dlog( "requesting ${item_count} item(s) ${items_to_request} from peer ${endpoint}",
              ("item_count", items_to_request.size())("items_to_request", items_to_request)("endpoint", peer->get_remote_endpoint()) );
        for (const item_hash_t& item_to_request : items_to_request)
        {
          _active_sync_requests.insert( active_sync_requests_map::value_type(item_to_request, fc::time_point::now() ) );
          item_id item_id_to_request( graphene::net::block_message_type, item_to_request );
          peer->sync_items_requested_from_peer.insert( peer_connection::item_to_time_map_type::value_type(item_id_to_request, fc::time_point::now() ) );
        }
        peer->send_message(fetch_items_message(graphene::net::block_message_type, items_to_request));
      }
  
      void node_impl::fetch_sync_items_loop()
      {
        VERIFY_CORRECT_THREAD();
        while( !_fetch_sync_items_loop_done.canceled() )
        {
          _sync_items_to_fetch_updated = false;
          dlog( "beginning another iteration of the sync items loop" );
  
          if (!_suspend_fetching_sync_blocks)
          {
            std::map<peer_connection_ptr, std::vector<item_hash_t> > sync_item_requests_to_send;
  
            {
              ASSERT_TASK_NOT_PREEMPTED();
              std::set<item_hash_t> sync_items_to_request;
  
              // for each idle peer that we're syncing with
              for( const peer_connection_ptr& peer : _active_connections )
              {
                if( peer->we_need_sync_items_from_peer &&
                    sync_item_requests_to_send.find(peer) == sync_item_requests_to_send.end() && // if we've already scheduled a request for this peer, don't consider scheduling another
                    peer->idle() )
                {
                  if (!peer->inhibit_fetching_sync_blocks)
                  {
                    // loop through the items it has that we don't yet have on our blockchain
                    for( unsigned i = 0; i < peer->ids_of_items_to_get.size(); ++i )
                    {
                      item_hash_t item_to_potentially_request = peer->ids_of_items_to_get[i];
                      // if we don't already have this item in our temporary storage and we haven't requested from another syncing peer
                      if( !have_already_received_sync_item(item_to_potentially_request) && // already got it, but for some reson it's still in our list of items to fetch
                          sync_items_to_request.find(item_to_potentially_request) == sync_items_to_request.end() &&  // we have already decided to request it from another peer during this iteration
                          _active_sync_requests.find(item_to_potentially_request) == _active_sync_requests.end() ) // we've requested it in a previous iteration and we're still waiting for it to arrive
                      {
                        // then schedule a request from this peer
                        sync_item_requests_to_send[peer].push_back(item_to_potentially_request);
                        sync_items_to_request.insert( item_to_potentially_request );
                        if (sync_item_requests_to_send[peer].size() >= _maximum_blocks_per_peer_during_syncing)
                          break;
                      }
                    }
                  }
                }
              }
            } // end non-preemptable section
  
            // make all the requests we scheduled in the loop above
            for( auto sync_item_request : sync_item_requests_to_send )
              request_sync_items_from_peer( sync_item_request.first, sync_item_request.second );
            sync_item_requests_to_send.clear();
          }
          else
            dlog("fetch_sync_items_loop is suspended pending backlog processing");
  
          if( !_sync_items_to_fetch_updated )
          {
            dlog( "no sync items to fetch right now, going to sleep" );
            _retrigger_fetch_sync_items_loop_promise = fc::promise<void>::ptr( new fc::promise<void>("graphene::net::retrigger_fetch_sync_items_loop") );
            _retrigger_fetch_sync_items_loop_promise->wait();
            _retrigger_fetch_sync_items_loop_promise.reset();
          }
        } // while( !canceled )
      }
  
      void node_impl::trigger_fetch_sync_items_loop()
      {
        VERIFY_CORRECT_THREAD();
        dlog( "Triggering fetch sync items loop now" );
        _sync_items_to_fetch_updated = true;
        if( _retrigger_fetch_sync_items_loop_promise )
          _retrigger_fetch_sync_items_loop_promise->set_value();
      }
  
      bool node_impl::is_item_in_any_peers_inventory(const item_id& item) const
      {
        for( const peer_connection_ptr& peer : _active_connections )
        {
          if (peer->inventory_peer_advertised_to_us.find(item) != peer->inventory_peer_advertised_to_us.end() )
            return true;
        }
        return false;
      }
  
      void node_impl::fetch_items_loop()
      {
        VERIFY_CORRECT_THREAD();
        while (!_fetch_item_loop_done.canceled())
        {
          _items_to_fetch_updated = false;
          dlog("beginning an iteration of fetch items (${count} items to fetch)",
               ("count", _items_to_fetch.size()));
  
          fc::time_point oldest_timestamp_to_fetch = fc::time_point::now() - fc::seconds(_recent_block_interval_in_seconds * GRAPHENE_NET_MESSAGE_CACHE_DURATION_IN_BLOCKS);
          fc::time_point next_peer_unblocked_time = fc::time_point::maximum();
  
          // we need to construct a list of items to request from each peer first,
          // then send the messages (in two steps, to avoid yielding while iterating)
          // we want to evenly distribute our requests among our peers.
          struct requested_item_count_index {};
          struct peer_and_items_to_fetch
          {
            peer_connection_ptr peer;
            std::vector<item_id> item_ids;
            peer_and_items_to_fetch(const peer_connection_ptr& peer) : peer(peer) {}
            bool operator<(const peer_and_items_to_fetch& rhs) const { return peer < rhs.peer; }
            size_t number_of_items() const { return item_ids.size(); }
          };
          typedef boost::multi_index_container<peer_and_items_to_fetch,
                                               boost::multi_index::indexed_by<boost::multi_index::ordered_unique<boost::multi_index::member<peer_and_items_to_fetch, peer_connection_ptr, &peer_and_items_to_fetch::peer> >,
                                                                              boost::multi_index::ordered_non_unique<boost::multi_index::tag<requested_item_count_index>,
                                                                                                                     boost::multi_index::const_mem_fun<peer_and_items_to_fetch, size_t, &peer_and_items_to_fetch::number_of_items> > > > fetch_messages_to_send_set;
          fetch_messages_to_send_set items_by_peer;
  
          // initialize the fetch_messages_to_send with an empty set of items for all idle peers
          for (const peer_connection_ptr& peer : _active_connections)
            if (peer->idle())
              items_by_peer.insert(peer_and_items_to_fetch(peer));
  
          // now loop over all items we want to fetch
          for (auto item_iter = _items_to_fetch.begin(); item_iter != _items_to_fetch.end();)
          {
            if (item_iter->timestamp < oldest_timestamp_to_fetch)
            {
              // this item has probably already fallen out of our peers' caches, we'll just ignore it.
              // this can happen during flooding, and the _items_to_fetch could otherwise get clogged
              // with a bunch of items that we'll never be able to request from any peer
              wlog("Unable to fetch item ${item} before its likely expiration time, removing it from our list of items to fetch", ("item", item_iter->item));
              item_iter = _items_to_fetch.erase(item_iter);
            }
            else
            {
              // find a peer that has it, we'll use the one who has the least requests going to it to load balance
              bool item_fetched = false;
              for (auto peer_iter = items_by_peer.get<requested_item_count_index>().begin(); peer_iter != items_by_peer.get<requested_item_count_index>().end(); ++peer_iter)
              {
                const peer_connection_ptr& peer = peer_iter->peer;
                // if they have the item and we haven't already decided to ask them for too many other items
                if (peer_iter->item_ids.size() < GRAPHENE_NET_MAX_ITEMS_PER_PEER_DURING_NORMAL_OPERATION &&
                    peer->inventory_peer_advertised_to_us.find(item_iter->item) != peer->inventory_peer_advertised_to_us.end())
                {
                  if (item_iter->item.item_type == graphene::net::trx_message_type && peer->is_transaction_fetching_inhibited())
                    next_peer_unblocked_time = std::min(peer->transaction_fetching_inhibited_until, next_peer_unblocked_time);
                  else
                  {
                    //dlog("requesting item ${hash} from peer ${endpoint}",
                    //     ("hash", iter->item.item_hash)("endpoint", peer->get_remote_endpoint()));
                    item_id item_id_to_fetch = item_iter->item;
                    peer->items_requested_from_peer.insert(peer_connection::item_to_time_map_type::value_type(item_id_to_fetch, fc::time_point::now()));
                    item_iter = _items_to_fetch.erase(item_iter);
                    item_fetched = true;
                    items_by_peer.get<requested_item_count_index>().modify(peer_iter, [&item_id_to_fetch](peer_and_items_to_fetch& peer_and_items) {
                      peer_and_items.item_ids.push_back(item_id_to_fetch);
                    });
                    break;
                  }
                }  
              }
              if (!item_fetched)
                ++item_iter;
            }
          }
  
          // we've figured out which peer will be providing each item, now send the messages.
          for (const peer_and_items_to_fetch& peer_and_items : items_by_peer)
          {
            // the item lists are heterogenous and
            // the fetch_items_message can only deal with one item type at a time.  
            std::map<uint32_t, std::vector<item_hash_t> > items_to_fetch_by_type;
            for (const item_id& item : peer_and_items.item_ids)
              items_to_fetch_by_type[item.item_type].push_back(item.item_hash);
            for (auto& items_by_type : items_to_fetch_by_type)
            {
              dlog("requesting ${count} items of type ${type} from peer ${endpoint}: ${hashes}",
                   ("count", items_by_type.second.size())("type", (uint32_t)items_by_type.first)
                   ("endpoint", peer_and_items.peer->get_remote_endpoint())
                   ("hashes", items_by_type.second));
              peer_and_items.peer->send_message(fetch_items_message(items_by_type.first,
                                                                    items_by_type.second));
            }
          }
          items_by_peer.clear();
  
          if (!_items_to_fetch_updated)
          {
            _retrigger_fetch_item_loop_promise = fc::promise<void>::ptr(new fc::promise<void>("graphene::net::retrigger_fetch_item_loop"));
            fc::microseconds time_until_retrigger = fc::microseconds::maximum();
            if (next_peer_unblocked_time != fc::time_point::maximum())
              time_until_retrigger = next_peer_unblocked_time - fc::time_point::now();
            try
            {
              if (time_until_retrigger > fc::microseconds(0))
                _retrigger_fetch_item_loop_promise->wait(time_until_retrigger);
            }
            catch (const fc::timeout_exception&)
            {
              dlog("Resuming fetch_items_loop due to timeout -- one of our peers should no longer be throttled");
            }
            _retrigger_fetch_item_loop_promise.reset();
          }
        } // while (!canceled)
      }
  
      void node_impl::trigger_fetch_items_loop()
      {
        VERIFY_CORRECT_THREAD();
        _items_to_fetch_updated = true;
        if( _retrigger_fetch_item_loop_promise )
          _retrigger_fetch_item_loop_promise->set_value();
      }
  
      void node_impl::advertise_inventory_loop()
      {
        VERIFY_CORRECT_THREAD();
        while (!_advertise_inventory_loop_done.canceled())
        {
          dlog("beginning an iteration of advertise inventory");
          // swap inventory into local variable, clearing the node's copy
          std::unordered_set<item_id> inventory_to_advertise;
          inventory_to_advertise.swap(_new_inventory);
  
          // process all inventory to advertise and construct the inventory messages we'll send
          // first, then send them all in a batch (to avoid any fiber interruption points while
          // we're computing the messages)
          std::list<std::pair<peer_connection_ptr, item_ids_inventory_message> > inventory_messages_to_send;
  
          for (const peer_connection_ptr& peer : _active_connections)
          {
            // only advertise to peers who are in sync with us
             wdump((peer->peer_needs_sync_items_from_us));
            if( !peer->peer_needs_sync_items_from_us )
            {
              std::map<uint32_t, std::vector<item_hash_t> > items_to_advertise_by_type;
              // don't send the peer anything we've already advertised to it
              // or anything it has advertised to us
              // group the items we need to send by type, because we'll need to send one inventory message per type
              unsigned total_items_to_send_to_this_peer = 0;
              wdump((inventory_to_advertise));
              for (const item_id& item_to_advertise : inventory_to_advertise)
              {
                if (peer->inventory_advertised_to_peer.find(item_to_advertise) != peer->inventory_advertised_to_peer.end() )
                   wdump((*peer->inventory_advertised_to_peer.find(item_to_advertise)));
                if (peer->inventory_peer_advertised_to_us.find(item_to_advertise) != peer->inventory_peer_advertised_to_us.end() )
                   wdump((*peer->inventory_peer_advertised_to_us.find(item_to_advertise)));
  
                if (peer->inventory_advertised_to_peer.find(item_to_advertise) == peer->inventory_advertised_to_peer.end() &&
                    peer->inventory_peer_advertised_to_us.find(item_to_advertise) == peer->inventory_peer_advertised_to_us.end())
                {
                  items_to_advertise_by_type[item_to_advertise.item_type].push_back(item_to_advertise.item_hash);
                  peer->inventory_advertised_to_peer.insert(peer_connection::timestamped_item_id(item_to_advertise, fc::time_point::now()));
                  ++total_items_to_send_to_this_peer;
                  if (item_to_advertise.item_type == trx_message_type)
                    testnetlog("advertising transaction ${id} to peer ${endpoint}", ("id", item_to_advertise.item_hash)("endpoint", peer->get_remote_endpoint()));
                  dlog("advertising item ${id} to peer ${endpoint}", ("id", item_to_advertise.item_hash)("endpoint", peer->get_remote_endpoint()));
                }
              }
                dlog("advertising ${count} new item(s) of ${types} type(s) to peer ${endpoint}",
                     ("count", total_items_to_send_to_this_peer)
                     ("types", items_to_advertise_by_type.size())
                     ("endpoint", peer->get_remote_endpoint()));
              for (auto items_group : items_to_advertise_by_type)
                inventory_messages_to_send.push_back(std::make_pair(peer, item_ids_inventory_message(items_group.first, items_group.second)));
            }
            peer->clear_old_inventory();
          }
  
          for (auto iter = inventory_messages_to_send.begin(); iter != inventory_messages_to_send.end(); ++iter)
            iter->first->send_message(iter->second);
          inventory_messages_to_send.clear();
  
          if (_new_inventory.empty())
          {
            _retrigger_advertise_inventory_loop_promise = fc::promise<void>::ptr(new fc::promise<void>("graphene::net::retrigger_advertise_inventory_loop"));
            _retrigger_advertise_inventory_loop_promise->wait();
            _retrigger_advertise_inventory_loop_promise.reset();
          }
        } // while(!canceled)
      }
  
      void node_impl::trigger_advertise_inventory_loop()
      {
        VERIFY_CORRECT_THREAD();
        if( _retrigger_advertise_inventory_loop_promise )
          _retrigger_advertise_inventory_loop_promise->set_value();
      }
  
      void node_impl::terminate_inactive_connections_loop()
      {
        VERIFY_CORRECT_THREAD();
        std::list<peer_connection_ptr> peers_to_disconnect_gently;
        std::list<peer_connection_ptr> peers_to_disconnect_forcibly;
        std::list<peer_connection_ptr> peers_to_send_keep_alive;
        std::list<peer_connection_ptr> peers_to_terminate;
  
        _recent_block_interval_in_seconds = _delegate->get_current_block_interval_in_seconds();
  
        // Disconnect peers that haven't sent us any data recently
        // These numbers are just guesses and we need to think through how this works better.
        // If we and our peers get disconnected from the rest of the network, we will not
        // receive any blocks or transactions from the rest of the world, and that will
        // probably make us disconnect from our peers even though we have working connections to
        // them (but they won't have sent us anything since they aren't getting blocks either).
        // This might not be so bad because it could make us initiate more connections and
        // reconnect with the rest of the network, or it might just futher isolate us.
        {
          // As usual, the first step is to walk through all our peers and figure out which
          // peers need action (disconneting, sending keepalives, etc), then we walk through 
          // those lists yielding at our leisure later.
          ASSERT_TASK_NOT_PREEMPTED();
  
          uint32_t handshaking_timeout = _peer_inactivity_timeout;
          fc::time_point handshaking_disconnect_threshold = fc::time_point::now() - fc::seconds(handshaking_timeout);
          for( const peer_connection_ptr handshaking_peer : _handshaking_connections )
            if( handshaking_peer->connection_initiation_time < handshaking_disconnect_threshold &&
                handshaking_peer->get_last_message_received_time() < handshaking_disconnect_threshold &&
                handshaking_peer->get_last_message_sent_time() < handshaking_disconnect_threshold )
            {
              wlog( "Forcibly disconnecting from handshaking peer ${peer} due to inactivity of at least ${timeout} seconds",
                    ( "peer", handshaking_peer->get_remote_endpoint() )("timeout", handshaking_timeout ) );
              wlog("Peer's negotiating status: ${status}, bytes sent: ${sent}, bytes received: ${received}",
                    ("status", handshaking_peer->negotiation_status)
                    ("sent", handshaking_peer->get_total_bytes_sent())
                    ("received", handshaking_peer->get_total_bytes_received()));
              handshaking_peer->connection_closed_error = fc::exception(FC_LOG_MESSAGE(warn, "Terminating handshaking connection due to inactivity of ${timeout} seconds.  Negotiating status: ${status}, bytes sent: ${sent}, bytes received: ${received}",
                                                                                        ("peer", handshaking_peer->get_remote_endpoint())
                                                                                        ("timeout", handshaking_timeout)
                                                                                        ("status", handshaking_peer->negotiation_status)
                                                                                        ("sent", handshaking_peer->get_total_bytes_sent())
                                                                                        ("received", handshaking_peer->get_total_bytes_received())));
              peers_to_disconnect_forcibly.push_back( handshaking_peer );
            }
  
          // timeout for any active peers is two block intervals
          uint32_t active_disconnect_timeout = 10 * _recent_block_interval_in_seconds;
          uint32_t active_send_keepalive_timeout = active_disconnect_timeout / 2;
          
          // set the ignored request time out to 1 second.  When we request a block
          // or transaction from a peer, this timeout determines how long we wait for them
          // to reply before we give up and ask another peer for the item.
          // Ideally this should be significantly shorter than the block interval, because
          // we'd like to realize the block isn't coming and fetch it from a different 
          // peer before the next block comes in.  At the current target of 3 second blocks,
          // 1 second seems reasonable.  When we get closer to our eventual target of 1 second 
          // blocks, this will need to be re-evaluated (i.e., can we set the timeout to 500ms
          // and still handle normal network & processing delays without excessive disconnects)
          fc::microseconds active_ignored_request_timeout = fc::seconds(1);
  
          fc::time_point active_disconnect_threshold = fc::time_point::now() - fc::seconds(active_disconnect_timeout);
          fc::time_point active_send_keepalive_threshold = fc::time_point::now() - fc::seconds(active_send_keepalive_timeout);
          fc::time_point active_ignored_request_threshold = fc::time_point::now() - active_ignored_request_timeout;
          for( const peer_connection_ptr& active_peer : _active_connections )
          {
            if( active_peer->connection_initiation_time < active_disconnect_threshold &&
                active_peer->get_last_message_received_time() < active_disconnect_threshold )
            {
              wlog( "Closing connection with peer ${peer} due to inactivity of at least ${timeout} seconds",
                    ( "peer", active_peer->get_remote_endpoint() )("timeout", active_disconnect_timeout ) );
              peers_to_disconnect_gently.push_back( active_peer );
            }
            else
            {
              bool disconnect_due_to_request_timeout = false;
              for (const peer_connection::item_to_time_map_type::value_type& item_and_time : active_peer->sync_items_requested_from_peer)
                if (item_and_time.second < active_ignored_request_threshold)
                {
                  wlog("Disconnecting peer ${peer} because they didn't respond to my request for sync item ${id}",
                        ("peer", active_peer->get_remote_endpoint())("id", item_and_time.first.item_hash));
                  disconnect_due_to_request_timeout = true;
                  break;
                }
              if (!disconnect_due_to_request_timeout &&
                  active_peer->item_ids_requested_from_peer &&
                  active_peer->item_ids_requested_from_peer->get<1>() < active_ignored_request_threshold)
                {
                  wlog("Disconnecting peer ${peer} because they didn't respond to my request for sync item ids after ${synopsis}",
                        ("peer", active_peer->get_remote_endpoint())
                        ("synopsis", active_peer->item_ids_requested_from_peer->get<0>()));
                  disconnect_due_to_request_timeout = true;
                }
              if (!disconnect_due_to_request_timeout)
                for (const peer_connection::item_to_time_map_type::value_type& item_and_time : active_peer->items_requested_from_peer)
                  if (item_and_time.second < active_ignored_request_threshold)
                  {
                    wlog("Disconnecting peer ${peer} because they didn't respond to my request for item ${id}",
                          ("peer", active_peer->get_remote_endpoint())("id", item_and_time.first.item_hash));
                    disconnect_due_to_request_timeout = true;
                    break;
                  }
              if (disconnect_due_to_request_timeout)
              {
                // we should probably disconnect nicely and give them a reason, but right now the logic
                // for rescheduling the requests only executes when the connection is fully closed,
                // and we want to get those requests rescheduled as soon as possible
                peers_to_disconnect_forcibly.push_back(active_peer);
              }
              else if (active_peer->connection_initiation_time < active_send_keepalive_threshold &&
                       active_peer->get_last_message_received_time() < active_send_keepalive_threshold)
              {
                wlog( "Sending a keepalive message to peer ${peer} who hasn't sent us any messages in the last ${timeout} seconds",
                      ( "peer", active_peer->get_remote_endpoint() )("timeout", active_send_keepalive_timeout ) );
                peers_to_send_keep_alive.push_back(active_peer);
              }
            }
          }
  
          fc::time_point closing_disconnect_threshold = fc::time_point::now() - fc::seconds(GRAPHENE_NET_PEER_DISCONNECT_TIMEOUT);
          for( const peer_connection_ptr& closing_peer : _closing_connections )
            if( closing_peer->connection_closed_time < closing_disconnect_threshold )
            {
              // we asked this peer to close their connectoin to us at least GRAPHENE_NET_PEER_DISCONNECT_TIMEOUT
              // seconds ago, but they haven't done it yet.  Terminate the connection now
              wlog( "Forcibly disconnecting peer ${peer} who failed to close their connection in a timely manner",
                    ( "peer", closing_peer->get_remote_endpoint() ) );
              peers_to_disconnect_forcibly.push_back( closing_peer );
            }
  
          uint32_t failed_terminate_timeout_seconds = 120;
          fc::time_point failed_terminate_threshold = fc::time_point::now() - fc::seconds(failed_terminate_timeout_seconds);
          for (const peer_connection_ptr& peer : _terminating_connections )
            if (peer->get_connection_terminated_time() != fc::time_point::min() &&
                peer->get_connection_terminated_time() < failed_terminate_threshold)
            {
              wlog("Terminating connection with peer ${peer}, closing the connection didn't work", ("peer", peer->get_remote_endpoint()));
              peers_to_terminate.push_back(peer);
            }
  
          // That's the end of the sorting step; now all peers that require further processing are now in one of the
          // lists peers_to_disconnect_gently,  peers_to_disconnect_forcibly, peers_to_send_keep_alive, or peers_to_terminate
  
          // if we've decided to delete any peers, do it now; in its current implementation this doesn't yield,
          // and once we start yielding, we may find that we've moved that peer to another list (closed or active)
          // and that triggers assertions, maybe even errors
          for (const peer_connection_ptr& peer : peers_to_terminate )
          {
            assert(_terminating_connections.find(peer) != _terminating_connections.end());
            _terminating_connections.erase(peer);
            schedule_peer_for_deletion(peer);
          }
          peers_to_terminate.clear();
  
          // if we're going to abruptly disconnect anyone, do it here 
          // (it doesn't yield).  I don't think there would be any harm if this were 
          // moved to the yielding section
          for( const peer_connection_ptr& peer : peers_to_disconnect_forcibly )
          {
            move_peer_to_terminating_list(peer);
            peer->close_connection();
          }
          peers_to_disconnect_forcibly.clear();
        } // end ASSERT_TASK_NOT_PREEMPTED()
  
        // Now process the peers that we need to do yielding functions with (disconnect sends a message with the
        // disconnect reason, so it may yield)
        for( const peer_connection_ptr& peer : peers_to_disconnect_gently )
        {
          fc::exception detailed_error( FC_LOG_MESSAGE(warn, "Disconnecting due to inactivity",
                                                        ( "last_message_received_seconds_ago", (peer->get_last_message_received_time() - fc::time_point::now() ).count() / fc::seconds(1 ).count() )
                                                        ( "last_message_sent_seconds_ago", (peer->get_last_message_sent_time() - fc::time_point::now() ).count() / fc::seconds(1 ).count() )
                                                        ( "inactivity_timeout", _active_connections.find(peer ) != _active_connections.end() ? _peer_inactivity_timeout * 10 : _peer_inactivity_timeout ) ) );
          disconnect_from_peer( peer.get(), "Disconnecting due to inactivity", false, detailed_error );
        }
        peers_to_disconnect_gently.clear();
  
        for( const peer_connection_ptr& peer : peers_to_send_keep_alive )
          peer->send_message(current_time_request_message(),
                             offsetof(current_time_request_message, request_sent_time));
        peers_to_send_keep_alive.clear();
  
        if (!_node_is_shutting_down && !_terminate_inactive_connections_loop_done.canceled())
           _terminate_inactive_connections_loop_done = fc::schedule( [this](){ terminate_inactive_connections_loop(); },
                                                                     fc::time_point::now() + fc::seconds(GRAPHENE_NET_PEER_HANDSHAKE_INACTIVITY_TIMEOUT / 2),
                                                                     "terminate_inactive_connections_loop" );
      }
  
      void node_impl::fetch_updated_peer_lists_loop()
      {
        VERIFY_CORRECT_THREAD();
  
        std::list<peer_connection_ptr> original_active_peers(_active_connections.begin(), _active_connections.end());
        for( const peer_connection_ptr& active_peer : original_active_peers )
        {
          try
          {
            active_peer->send_message(address_request_message());
          }
          catch ( const fc::canceled_exception& )
          {
            throw;
          }
          catch (const fc::exception& e)
          {
            dlog("Caught exception while sending address request message to peer ${peer} : ${e}",
                 ("peer", active_peer->get_remote_endpoint())("e", e));
          }
        }
  
        // this has nothing to do with updating the peer list, but we need to prune this list 
        // at regular intervals, this is a fine place to do it.
        fc::time_point_sec oldest_failed_ids_to_keep(fc::time_point::now() - fc::minutes(15));
        auto oldest_failed_ids_to_keep_iter = _recently_failed_items.get<peer_connection::timestamp_index>().lower_bound(oldest_failed_ids_to_keep);
        auto begin_iter = _recently_failed_items.get<peer_connection::timestamp_index>().begin();
        _recently_failed_items.get<peer_connection::timestamp_index>().erase(begin_iter, oldest_failed_ids_to_keep_iter);
  
        if (!_node_is_shutting_down && !_fetch_updated_peer_lists_loop_done.canceled() )
           _fetch_updated_peer_lists_loop_done = fc::schedule( [this](){ fetch_updated_peer_lists_loop(); },
                                                               fc::time_point::now() + fc::minutes(15),
                                                               "fetch_updated_peer_lists_loop" );
      }
      void node_impl::update_bandwidth_data(uint32_t bytes_read_this_second, uint32_t bytes_written_this_second)
      {
        VERIFY_CORRECT_THREAD();
        _average_network_read_speed_seconds.push_back(bytes_read_this_second);
        _average_network_write_speed_seconds.push_back(bytes_written_this_second);
        ++_average_network_usage_second_counter;
        if (_average_network_usage_second_counter >= 60)
        {
          _average_network_usage_second_counter = 0;
          ++_average_network_usage_minute_counter;
          uint32_t average_read_this_minute = (uint32_t)boost::accumulate(_average_network_read_speed_seconds, uint64_t(0)) / (uint32_t)_average_network_read_speed_seconds.size();
          _average_network_read_speed_minutes.push_back(average_read_this_minute);
          uint32_t average_written_this_minute = (uint32_t)boost::accumulate(_average_network_write_speed_seconds, uint64_t(0)) / (uint32_t)_average_network_write_speed_seconds.size();
          _average_network_write_speed_minutes.push_back(average_written_this_minute);
          if (_average_network_usage_minute_counter >= 60)
          {
            _average_network_usage_minute_counter = 0;
            uint32_t average_read_this_hour = (uint32_t)boost::accumulate(_average_network_read_speed_minutes, uint64_t(0)) / (uint32_t)_average_network_read_speed_minutes.size();
            _average_network_read_speed_hours.push_back(average_read_this_hour);
            uint32_t average_written_this_hour = (uint32_t)boost::accumulate(_average_network_write_speed_minutes, uint64_t(0)) / (uint32_t)_average_network_write_speed_minutes.size();
            _average_network_write_speed_hours.push_back(average_written_this_hour);
          }
        }
      }
      void node_impl::bandwidth_monitor_loop()
      {
        VERIFY_CORRECT_THREAD();
        fc::time_point_sec current_time = fc::time_point::now();
  
        if (_bandwidth_monitor_last_update_time == fc::time_point_sec::min())
          _bandwidth_monitor_last_update_time = current_time;
  
        uint32_t seconds_since_last_update = current_time.sec_since_epoch() - _bandwidth_monitor_last_update_time.sec_since_epoch();
        seconds_since_last_update = std::max(UINT32_C(1), seconds_since_last_update);
        uint32_t bytes_read_this_second = _rate_limiter.get_actual_download_rate();
        uint32_t bytes_written_this_second = _rate_limiter.get_actual_upload_rate();
        for (uint32_t i = 0; i < seconds_since_last_update - 1; ++i)
          update_bandwidth_data(0, 0);
        update_bandwidth_data(bytes_read_this_second, bytes_written_this_second);
        _bandwidth_monitor_last_update_time = current_time;
  
        if (!_node_is_shutting_down && !_bandwidth_monitor_loop_done.canceled())
          _bandwidth_monitor_loop_done = fc::schedule( [=](){ bandwidth_monitor_loop(); },
                                                       fc::time_point::now() + fc::seconds(1),
                                                       "bandwidth_monitor_loop" );
      }
  
      void node_impl::dump_node_status_task()
      {
        VERIFY_CORRECT_THREAD();
        dump_node_status();
        if (!_node_is_shutting_down && !_dump_node_status_task_done.canceled())
          _dump_node_status_task_done = fc::schedule([=](){ dump_node_status_task(); },
                                                     fc::time_point::now() + fc::minutes(1),
                                                     "dump_node_status_task");
      }
  
      void node_impl::delayed_peer_deletion_task()
      {
        VERIFY_CORRECT_THREAD();
  #ifdef USE_PEERS_TO_DELETE_MUTEX
        fc::scoped_lock<fc::mutex> lock(_peers_to_delete_mutex);
        dlog("in delayed_peer_deletion_task with ${count} in queue", ("count", _peers_to_delete.size()));
        _peers_to_delete.clear();
        dlog("_peers_to_delete cleared");
  #else
        while (!_peers_to_delete.empty())
        {
          std::list<peer_connection_ptr> peers_to_delete_copy;
          dlog("beginning an iteration of delayed_peer_deletion_task with ${count} in queue", ("count", _peers_to_delete.size()));
          peers_to_delete_copy.swap(_peers_to_delete);
        }
        dlog("leaving delayed_peer_deletion_task");
  #endif
      }
  
      void node_impl::schedule_peer_for_deletion(const peer_connection_ptr& peer_to_delete)
      {
        VERIFY_CORRECT_THREAD();
  
        assert(_handshaking_connections.find(peer_to_delete) == _handshaking_connections.end());
        assert(_active_connections.find(peer_to_delete) == _active_connections.end());
        assert(_closing_connections.find(peer_to_delete) == _closing_connections.end());
        assert(_terminating_connections.find(peer_to_delete) == _terminating_connections.end());
  
  #ifdef USE_PEERS_TO_DELETE_MUTEX
        dlog("scheduling peer for deletion: ${peer} (may block on a mutex here)", ("peer", peer_to_delete->get_remote_endpoint()));
  
        unsigned number_of_peers_to_delete;
        {
          fc::scoped_lock<fc::mutex> lock(_peers_to_delete_mutex);
          _peers_to_delete.emplace_back(peer_to_delete);
          number_of_peers_to_delete = _peers_to_delete.size();
        }
        dlog("peer scheduled for deletion: ${peer}", ("peer", peer_to_delete->get_remote_endpoint()));
  
        if (!_node_is_shutting_down &&
            (!_delayed_peer_deletion_task_done.valid() || _delayed_peer_deletion_task_done.ready()))
        {
          dlog("asyncing delayed_peer_deletion_task to delete ${size} peers", ("size", number_of_peers_to_delete));
          _delayed_peer_deletion_task_done = fc::async([this](){ delayed_peer_deletion_task(); }, "delayed_peer_deletion_task" );
      }
        else
          dlog("delayed_peer_deletion_task is already scheduled (current size of _peers_to_delete is ${size})", ("size", number_of_peers_to_delete));
  #else
        dlog("scheduling peer for deletion: ${peer} (this will not block)", ("peer", peer_to_delete->get_remote_endpoint()));
        _peers_to_delete.push_back(peer_to_delete);
        if (!_node_is_shutting_down &&
            (!_delayed_peer_deletion_task_done.valid() || _delayed_peer_deletion_task_done.ready()))
        {
          dlog("asyncing delayed_peer_deletion_task to delete ${size} peers", ("size", _peers_to_delete.size()));
          _delayed_peer_deletion_task_done = fc::async([this](){ delayed_peer_deletion_task(); }, "delayed_peer_deletion_task" );
        }
        else
          dlog("delayed_peer_deletion_task is already scheduled (current size of _peers_to_delete is ${size})", ("size", _peers_to_delete.size()));
  
  #endif
      }
  
      bool node_impl::is_accepting_new_connections()
      {
        VERIFY_CORRECT_THREAD();
        return !_p2p_network_connect_loop_done.canceled() && get_number_of_connections() <= _maximum_number_of_connections;
      }
  
      bool node_impl::is_wanting_new_connections()
      {
        VERIFY_CORRECT_THREAD();
        return !_p2p_network_connect_loop_done.canceled() && get_number_of_connections() < _desired_number_of_connections;
      }
  
      uint32_t node_impl::get_number_of_connections()
      {
        VERIFY_CORRECT_THREAD();
        return (uint32_t)(_handshaking_connections.size() + _active_connections.size());
      }
  
      peer_connection_ptr node_impl::get_peer_by_node_id(const node_id_t& node_id)
      {
        for (const peer_connection_ptr& active_peer : _active_connections)
          if (node_id == active_peer->node_id)
            return active_peer;
        for (const peer_connection_ptr& handshaking_peer : _handshaking_connections)
          if (node_id == handshaking_peer->node_id)
            return handshaking_peer;
        return peer_connection_ptr();
      }
  
      bool node_impl::is_already_connected_to_id(const node_id_t& node_id)
      {
        VERIFY_CORRECT_THREAD();
        if (node_id == _node_id)
        {
          dlog("is_already_connected_to_id returning true because the peer is us");
          return true;
        }
        for (const peer_connection_ptr active_peer : _active_connections)
          if (node_id == active_peer->node_id)
          {
            dlog("is_already_connected_to_id returning true because the peer is already in our active list");
            return true;
          }
        for (const peer_connection_ptr handshaking_peer : _handshaking_connections)
          if (node_id == handshaking_peer->node_id)
          {
            dlog("is_already_connected_to_id returning true because the peer is already in our handshaking list");
            return true;
          }
        return false;
      }
  
      // merge addresses received from a peer into our database
      bool node_impl::merge_address_info_with_potential_peer_database(const std::vector<address_info> addresses)
      {
        VERIFY_CORRECT_THREAD();
        bool new_information_received = false;
        for (const address_info& address : addresses)
        {
          if (address.firewalled == graphene::net::firewalled_state::not_firewalled)
          {
            potential_peer_record updated_peer_record = _potential_peer_db.lookup_or_create_entry_for_endpoint(address.remote_endpoint);
            if (address.last_seen_time > updated_peer_record.last_seen_time)
              new_information_received = true;
            updated_peer_record.last_seen_time = std::max(address.last_seen_time, updated_peer_record.last_seen_time);
            _potential_peer_db.update_entry(updated_peer_record);
          }
        }
        return new_information_received;
      }
  
      void node_impl::display_current_connections()
      {
        VERIFY_CORRECT_THREAD();
        dlog("Currently have ${current} of [${desired}/${max}] connections",
             ("current", get_number_of_connections())
             ("desired", _desired_number_of_connections)
             ("max", _maximum_number_of_connections));
        dlog("   my id is ${id}", ("id", _node_id));
  
        for (const peer_connection_ptr& active_connection : _active_connections)
        {
          dlog("        active: ${endpoint} with ${id}   [${direction}]",
               ("endpoint", active_connection->get_remote_endpoint())
               ("id", active_connection->node_id)
               ("direction", active_connection->direction));
        }
        for (const peer_connection_ptr& handshaking_connection : _handshaking_connections)
        {
          dlog("   handshaking: ${endpoint} with ${id}  [${direction}]",
               ("endpoint", handshaking_connection->get_remote_endpoint())
               ("id", handshaking_connection->node_id)
               ("direction", handshaking_connection->direction));
        }
      }
  
      void node_impl::on_message( peer_connection* originating_peer, const message& received_message )
      {
        VERIFY_CORRECT_THREAD();
        message_hash_type message_hash = received_message.id();
        dlog("handling message ${type} ${hash} size ${size} from peer ${endpoint}",
             ("type", graphene::net::core_message_type_enum(received_message.msg_type))("hash", message_hash)
             ("size", received_message.size)
             ("endpoint", originating_peer->get_remote_endpoint()));
        switch ( received_message.msg_type )
        {
        case core_message_type_enum::hello_message_type:
          on_hello_message(originating_peer, received_message.as<hello_message>());
          break;
        case core_message_type_enum::connection_accepted_message_type:
          on_connection_accepted_message(originating_peer, received_message.as<connection_accepted_message>());
          break;
        case core_message_type_enum::connection_rejected_message_type:
          on_connection_rejected_message(originating_peer, received_message.as<connection_rejected_message>());
          break;
        case core_message_type_enum::address_request_message_type:
          on_address_request_message(originating_peer, received_message.as<address_request_message>());
          break;
        case core_message_type_enum::address_message_type:
          on_address_message(originating_peer, received_message.as<address_message>());
          break;
        case core_message_type_enum::fetch_blockchain_item_ids_message_type:
          on_fetch_blockchain_item_ids_message(originating_peer, received_message.as<fetch_blockchain_item_ids_message>());
          break;
        case core_message_type_enum::blockchain_item_ids_inventory_message_type:
          on_blockchain_item_ids_inventory_message(originating_peer, received_message.as<blockchain_item_ids_inventory_message>());
          break;
        case core_message_type_enum::fetch_items_message_type:
          on_fetch_items_message(originating_peer, received_message.as<fetch_items_message>());
          break;
        case core_message_type_enum::item_not_available_message_type:
          on_item_not_available_message(originating_peer, received_message.as<item_not_available_message>());
          break;
        case core_message_type_enum::item_ids_inventory_message_type:
          on_item_ids_inventory_message(originating_peer, received_message.as<item_ids_inventory_message>());
          break;
        case core_message_type_enum::closing_connection_message_type:
          on_closing_connection_message(originating_peer, received_message.as<closing_connection_message>());
          break;
        case core_message_type_enum::block_message_type:
          process_block_message(originating_peer, received_message, message_hash);
          break;
        case core_message_type_enum::current_time_request_message_type:
          on_current_time_request_message(originating_peer, received_message.as<current_time_request_message>());
          break;
        case core_message_type_enum::current_time_reply_message_type:
          on_current_time_reply_message(originating_peer, received_message.as<current_time_reply_message>());
          break;
        case core_message_type_enum::check_firewall_message_type:
          on_check_firewall_message(originating_peer, received_message.as<check_firewall_message>());
          break;
        case core_message_type_enum::check_firewall_reply_message_type:
          on_check_firewall_reply_message(originating_peer, received_message.as<check_firewall_reply_message>());
          break;
        case core_message_type_enum::get_current_connections_request_message_type:
          on_get_current_connections_request_message(originating_peer, received_message.as<get_current_connections_request_message>());
          break;
        case core_message_type_enum::get_current_connections_reply_message_type:
          on_get_current_connections_reply_message(originating_peer, received_message.as<get_current_connections_reply_message>());
          break;
  
        default:
          // ignore any message in between core_message_type_first and _last that we don't handle above
          // to allow us to add messages in the future
          if (received_message.msg_type < core_message_type_enum::core_message_type_first ||
              received_message.msg_type > core_message_type_enum::core_message_type_last)
            process_ordinary_message(originating_peer, received_message, message_hash);
          break;
        }
      }
  
  
      fc::variant_object node_impl::generate_hello_user_data()
      {
        VERIFY_CORRECT_THREAD();
        // for the time being, shoehorn a bunch of properties into the user_data variant object,
        // which lets us add and remove fields without changing the protocol.  Once we
        // settle on what we really want in there, we'll likely promote them to first
        // class fields in the hello message
        fc::mutable_variant_object user_data;
        user_data["fc_git_revision_sha"] = fc::git_revision_sha;
        user_data["fc_git_revision_unix_timestamp"] = fc::git_revision_unix_timestamp;
  #if defined( __APPLE__ )
        user_data["platform"] = "osx";
  #elif defined( __linux__ )
        user_data["platform"] = "linux";
  #elif defined( _MSC_VER )
        user_data["platform"] = "win32";
  #else
        user_data["platform"] = "other";
  #endif
        user_data["bitness"] = sizeof(void*) * 8;
  
        user_data["node_id"] = _node_id;
  
        item_hash_t head_block_id = _delegate->get_head_block_id();
        user_data["last_known_block_hash"] = head_block_id;
        user_data["last_known_block_number"] = _delegate->get_block_number(head_block_id);
        user_data["last_known_block_time"] = _delegate->get_block_time(head_block_id);
  
        if (!_hard_fork_block_numbers.empty())
          user_data["last_known_fork_block_number"] = _hard_fork_block_numbers.back();
  
        return user_data;
      }
      void node_impl::parse_hello_user_data_for_peer(peer_connection* originating_peer, const fc::variant_object& user_data)
      {
        VERIFY_CORRECT_THREAD();
        // try to parse data out of the user_agent string
        if (user_data.contains("graphene_git_revision_sha"))
          originating_peer->graphene_git_revision_sha = user_data["graphene_git_revision_sha"].as_string();
        if (user_data.contains("graphene_git_revision_unix_timestamp"))
          originating_peer->graphene_git_revision_unix_timestamp = fc::time_point_sec(user_data["graphene_git_revision_unix_timestamp"].as<uint32_t>());
        if (user_data.contains("fc_git_revision_sha"))
          originating_peer->fc_git_revision_sha = user_data["fc_git_revision_sha"].as_string();
        if (user_data.contains("fc_git_revision_unix_timestamp"))
          originating_peer->fc_git_revision_unix_timestamp = fc::time_point_sec(user_data["fc_git_revision_unix_timestamp"].as<uint32_t>());
        if (user_data.contains("platform"))
          originating_peer->platform = user_data["platform"].as_string();
        if (user_data.contains("bitness"))
          originating_peer->bitness = user_data["bitness"].as<uint32_t>();
        if (user_data.contains("node_id"))
          originating_peer->node_id = user_data["node_id"].as<node_id_t>();
        if (user_data.contains("last_known_fork_block_number"))
          originating_peer->last_known_fork_block_number = user_data["last_known_fork_block_number"].as<uint32_t>();
      }
  
      void node_impl::on_hello_message( peer_connection* originating_peer, const hello_message& hello_message_received )
      {
        VERIFY_CORRECT_THREAD();
        // this already_connected check must come before we fill in peer data below
        node_id_t peer_node_id = hello_message_received.node_public_key;
        try
        {
          peer_node_id = hello_message_received.user_data["node_id"].as<node_id_t>();
        }
        catch (const fc::exception&)
        {
          // either it's not there or it's not a valid session id.  either way, ignore.
        }
        bool already_connected_to_this_peer = is_already_connected_to_id(peer_node_id);
  
        // validate the node id
        fc::sha256::encoder shared_secret_encoder;
        fc::sha512 shared_secret = originating_peer->get_shared_secret();
        shared_secret_encoder.write(shared_secret.data(), sizeof(shared_secret));
        fc::ecc::public_key expected_node_public_key(hello_message_received.signed_shared_secret, shared_secret_encoder.result(), false);
  
        // store off the data provided in the hello message
        originating_peer->user_agent = hello_message_received.user_agent;
        originating_peer->node_public_key = hello_message_received.node_public_key;
        originating_peer->node_id = hello_message_received.node_public_key; // will probably be overwritten in parse_hello_user_data_for_peer()
        originating_peer->core_protocol_version = hello_message_received.core_protocol_version;
        originating_peer->inbound_address = hello_message_received.inbound_address;
        originating_peer->inbound_port = hello_message_received.inbound_port;
        originating_peer->outbound_port = hello_message_received.outbound_port;
  
        parse_hello_user_data_for_peer(originating_peer, hello_message_received.user_data);
  
        // if they didn't provide a last known fork, try to guess it
        if (originating_peer->last_known_fork_block_number == 0 &&
            originating_peer->graphene_git_revision_unix_timestamp)
        {
          uint32_t unix_timestamp = originating_peer->graphene_git_revision_unix_timestamp->sec_since_epoch();
          originating_peer->last_known_fork_block_number = _delegate->estimate_last_known_fork_from_git_revision_timestamp(unix_timestamp);
        }
  
        // now decide what to do with it
        if (originating_peer->their_state == peer_connection::their_connection_state::just_connected)
        {
          if (hello_message_received.node_public_key != expected_node_public_key.serialize())
          {
            wlog("Invalid signature in hello message from peer ${peer}", ("peer", originating_peer->get_remote_endpoint()));
            std::string rejection_message("Invalid signature in hello message");
            connection_rejected_message connection_rejected(_user_agent_string, core_protocol_version,
                                                            originating_peer->get_socket().remote_endpoint(),
                                                            rejection_reason_code::invalid_hello_message,
                                                            rejection_message);
  
            originating_peer->their_state = peer_connection::their_connection_state::connection_rejected;
            originating_peer->send_message( message(connection_rejected ) );
            // for this type of message, we're immediately disconnecting this peer
            disconnect_from_peer( originating_peer, "Invalid signature in hello message" );
            return;
          }
          if (hello_message_received.chain_id != _chain_id)
          {
            wlog("Received hello message from peer on a different chain: ${message}", ("message", hello_message_received));
            std::ostringstream rejection_message;
            rejection_message << "You're on a different chain than I am.  I'm on " << _chain_id.str() <<
                                " and you're on " << hello_message_received.chain_id.str();
            connection_rejected_message connection_rejected(_user_agent_string, core_protocol_version,
                                                            originating_peer->get_socket().remote_endpoint(),
                                                            rejection_reason_code::different_chain,
                                                            rejection_message.str());
  
            originating_peer->their_state = peer_connection::their_connection_state::connection_rejected;
            originating_peer->send_message(message(connection_rejected));
            // for this type of message, we're immediately disconnecting this peer, instead of trying to
            // allowing her to ask us for peers (any of our peers will be on the same chain as us, so there's no
            // benefit of sharing them)
            disconnect_from_peer(originating_peer, "You are on a different chain from me");
            return;
          }
          if (originating_peer->last_known_fork_block_number != 0)
          {
            uint32_t next_fork_block_number = get_next_known_hard_fork_block_number(originating_peer->last_known_fork_block_number);
            if (next_fork_block_number != 0)
            {
              // we know about a fork they don't.  See if we've already passed that block.  If we have, don't let them
              // connect because we won't be able to give them anything useful
              uint32_t head_block_num = _delegate->get_block_number(_delegate->get_head_block_id());
              if (next_fork_block_number < head_block_num)
              {
  #ifdef ENABLE_DEBUG_ULOGS
                ulog("Rejecting connection from peer because their version is too old.  Their version date: ${date}", ("date", originating_peer->graphene_git_revision_unix_timestamp));
  #endif
                wlog("Received hello message from peer running a version of that can only understand blocks up to #${their_hard_fork}, but I'm at head block number #${my_block_number}",
                     ("their_hard_fork", next_fork_block_number)("my_block_number", head_block_num));
                std::ostringstream rejection_message;
                rejection_message << "Your client is outdated -- you can only understand blocks up to #" << next_fork_block_number << ", but I'm already on block #" << head_block_num;
                connection_rejected_message connection_rejected(_user_agent_string, core_protocol_version,
                                                                originating_peer->get_socket().remote_endpoint(),
                                                                rejection_reason_code::unspecified,
                                                                rejection_message.str() );
  
                originating_peer->their_state = peer_connection::their_connection_state::connection_rejected;
                originating_peer->send_message(message(connection_rejected));
                // for this type of message, we're immediately disconnecting this peer, instead of trying to
                // allowing her to ask us for peers (any of our peers will be on the same chain as us, so there's no
                // benefit of sharing them)
                disconnect_from_peer(originating_peer, "Your client is too old, please upgrade");
                return;
              }
            }
          }
          if (already_connected_to_this_peer)
          {
  
            connection_rejected_message connection_rejected;
            if (_node_id == originating_peer->node_id)
              connection_rejected = connection_rejected_message(_user_agent_string, core_protocol_version,
                                                                originating_peer->get_socket().remote_endpoint(),
                                                                rejection_reason_code::connected_to_self,
                                                                "I'm connecting to myself");
            else
              connection_rejected = connection_rejected_message(_user_agent_string, core_protocol_version,
                                                                originating_peer->get_socket().remote_endpoint(),
                                                                rejection_reason_code::already_connected,
                                                                "I'm already connected to you");
            originating_peer->their_state = peer_connection::their_connection_state::connection_rejected;
            originating_peer->send_message(message(connection_rejected));
            dlog("Received a hello_message from peer ${peer} that I'm already connected to (with id ${id}), rejection",
                 ("peer", originating_peer->get_remote_endpoint())
                 ("id", originating_peer->node_id));
          }
  #ifdef ENABLE_P2P_DEBUGGING_API
          else if(!_allowed_peers.empty() &&
                  _allowed_peers.find(originating_peer->node_id) == _allowed_peers.end())
          {
            connection_rejected_message connection_rejected(_user_agent_string, core_protocol_version,
                                                            originating_peer->get_socket().remote_endpoint(),
                                                            rejection_reason_code::blocked,
                                                            "you are not in my allowed_peers list");
            originating_peer->their_state = peer_connection::their_connection_state::connection_rejected;
            originating_peer->send_message( message(connection_rejected ) );
            dlog( "Received a hello_message from peer ${peer} who isn't in my allowed_peers list, rejection", ("peer", originating_peer->get_remote_endpoint() ) );
          }
  #endif // ENABLE_P2P_DEBUGGING_API
          else
          {
            // whether we're planning on accepting them as a peer or not, they seem to be a valid node,
            // so add them to our database if they're not firewalled
  
            // in the hello message, the peer sent us the IP address and port it thought it was connecting from.
            // If they match the IP and port we see, we assume that they're actually on the internet and they're not
            // firewalled.
            fc::ip::endpoint peers_actual_outbound_endpoint = originating_peer->get_socket().remote_endpoint();
            if( peers_actual_outbound_endpoint.get_address() == originating_peer->inbound_address &&
                peers_actual_outbound_endpoint.port() == originating_peer->outbound_port )
            {
              if( originating_peer->inbound_port == 0 )
              {
                dlog( "peer does not appear to be firewalled, but they did not give an inbound port so I'm treating them as if they are." );
                originating_peer->is_firewalled = firewalled_state::firewalled;
              }
              else
              {
                // peer is not firewalled, add it to our database
                fc::ip::endpoint peers_inbound_endpoint(originating_peer->inbound_address, originating_peer->inbound_port);
                potential_peer_record updated_peer_record = _potential_peer_db.lookup_or_create_entry_for_endpoint(peers_inbound_endpoint);
                _potential_peer_db.update_entry(updated_peer_record);
                originating_peer->is_firewalled = firewalled_state::not_firewalled;
              }
            }
            else
            {
              dlog("peer is firewalled: they think their outbound endpoint is ${reported_endpoint}, but I see it as ${actual_endpoint}",
                   ("reported_endpoint", fc::ip::endpoint(originating_peer->inbound_address, originating_peer->outbound_port))
                   ("actual_endpoint", peers_actual_outbound_endpoint));
              originating_peer->is_firewalled = firewalled_state::firewalled;
            }
  
            if (!is_accepting_new_connections())
            {
              connection_rejected_message connection_rejected(_user_agent_string, core_protocol_version,
                                                              originating_peer->get_socket().remote_endpoint(),
                                                              rejection_reason_code::not_accepting_connections,
                                                              "not accepting any more incoming connections");
              originating_peer->their_state = peer_connection::their_connection_state::connection_rejected;
              originating_peer->send_message(message(connection_rejected));
              dlog("Received a hello_message from peer ${peer}, but I'm not accepting any more connections, rejection",
                   ("peer", originating_peer->get_remote_endpoint()));
            }
            else
            {
              originating_peer->their_state = peer_connection::their_connection_state::connection_accepted;
              originating_peer->send_message(message(connection_accepted_message()));
              dlog("Received a hello_message from peer ${peer}, sending reply to accept connection",
                   ("peer", originating_peer->get_remote_endpoint()));
            }
          }
        }
        else
        {
          // we can wind up here if we've connected to ourself, and the source and
          // destination endpoints are the same, causing messages we send out
          // to arrive back on the initiating socket instead of the receiving
          // socket.  If we did a complete job of enumerating local addresses,
          // we could avoid directly connecting to ourselves, or at least detect
          // immediately when we did it and disconnect.
  
          // The only way I know of that we'd get an unexpected hello that we
          //  can't really guard against is if we do a simulatenous open, we
          // probably need to think through that case.  We're not attempting that
          // yet, though, so it's ok to just disconnect here.
          wlog("unexpected hello_message from peer, disconnecting");
          disconnect_from_peer(originating_peer, "Received a unexpected hello_message");
        }
      }
  
      void node_impl::on_connection_accepted_message(peer_connection* originating_peer, const connection_accepted_message& connection_accepted_message_received)
      {
        VERIFY_CORRECT_THREAD();
        dlog("Received a connection_accepted in response to my \"hello\" from ${peer}", ("peer", originating_peer->get_remote_endpoint()));
        originating_peer->negotiation_status = peer_connection::connection_negotiation_status::peer_connection_accepted;
        originating_peer->our_state = peer_connection::our_connection_state::connection_accepted;
        originating_peer->send_message(address_request_message());
        fc::time_point now = fc::time_point::now();
        if (_is_firewalled == firewalled_state::unknown &&
            _last_firewall_check_message_sent < now - fc::minutes(5) &&
            originating_peer->core_protocol_version >= 106)
        {
          wlog("I don't know if I'm firewalled.  Sending a firewall check message to peer ${peer}",
               ("peer", originating_peer->get_remote_endpoint()));
          originating_peer->firewall_check_state = new firewall_check_state_data;
  
          originating_peer->send_message(check_firewall_message());
          _last_firewall_check_message_sent = now;
        }
      }
  
      void node_impl::on_connection_rejected_message(peer_connection* originating_peer, const connection_rejected_message& connection_rejected_message_received)
      {
        VERIFY_CORRECT_THREAD();
        if (originating_peer->our_state == peer_connection::our_connection_state::just_connected)
        {
          ilog("Received a rejection from ${peer} in response to my \"hello\", reason: \"${reason}\"",
               ("peer", originating_peer->get_remote_endpoint())
               ("reason", connection_rejected_message_received.reason_string));
  
          if (connection_rejected_message_received.reason_code == rejection_reason_code::connected_to_self)
          {
            _potential_peer_db.erase(originating_peer->get_socket().remote_endpoint());
            move_peer_to_closing_list(originating_peer->shared_from_this());
            originating_peer->close_connection();
          }
          else
          {
            // update our database to record that we were rejected so we won't try to connect again for a while
            // this only happens on connections we originate, so we should already know that peer is not firewalled
            fc::optional<potential_peer_record> updated_peer_record = _potential_peer_db.lookup_entry_for_endpoint(originating_peer->get_socket().remote_endpoint());
            if (updated_peer_record)
            {
              updated_peer_record->last_connection_disposition = last_connection_rejected;
              updated_peer_record->last_connection_attempt_time = fc::time_point::now();
              _potential_peer_db.update_entry(*updated_peer_record);
            }
          }
  
          originating_peer->negotiation_status = peer_connection::connection_negotiation_status::peer_connection_rejected;
          originating_peer->our_state = peer_connection::our_connection_state::connection_rejected;
          originating_peer->send_message(address_request_message());
        }
        else
          FC_THROW( "unexpected connection_rejected_message from peer" );
      }
  
      void node_impl::on_address_request_message(peer_connection* originating_peer, const address_request_message& address_request_message_received)
      {
        VERIFY_CORRECT_THREAD();
        dlog("Received an address request message");
  
        address_message reply;
        if (!_peer_advertising_disabled)
        {
          reply.addresses.reserve(_active_connections.size());
          for (const peer_connection_ptr& active_peer : _active_connections)
          {
            fc::optional<potential_peer_record> updated_peer_record = _potential_peer_db.lookup_entry_for_endpoint(*active_peer->get_remote_endpoint());
            if (updated_peer_record)
            {
              updated_peer_record->last_seen_time = fc::time_point::now();
              _potential_peer_db.update_entry(*updated_peer_record);
            }
  
            reply.addresses.emplace_back(address_info(*active_peer->get_remote_endpoint(),
                                                      fc::time_point::now(),
                                                      active_peer->round_trip_delay,
                                                      active_peer->node_id,
                                                      active_peer->direction,
                                                      active_peer->is_firewalled));
          }
        }
        originating_peer->send_message(reply);
      }
  
      void node_impl::on_address_message(peer_connection* originating_peer, const address_message& address_message_received)
      {
        VERIFY_CORRECT_THREAD();
        dlog("Received an address message containing ${size} addresses", ("size", address_message_received.addresses.size()));
        for (const address_info& address : address_message_received.addresses)
        {
          dlog("    ${endpoint} last seen ${time}", ("endpoint", address.remote_endpoint)("time", address.last_seen_time));
        }
        std::vector<graphene::net::address_info> updated_addresses = address_message_received.addresses;
        for (address_info& address : updated_addresses)
          address.last_seen_time = fc::time_point_sec(fc::time_point::now());
        bool new_information_received = merge_address_info_with_potential_peer_database(updated_addresses);
        if (new_information_received)
          trigger_p2p_network_connect_loop();
  
        if (_handshaking_connections.find(originating_peer->shared_from_this()) != _handshaking_connections.end())
        {
          // if we were handshaking, we need to continue with the next step in handshaking (which is either
          // ending handshaking and starting synchronization or disconnecting)
          if( originating_peer->our_state == peer_connection::our_connection_state::connection_rejected)
            disconnect_from_peer(originating_peer, "You rejected my connection request (hello message) so I'm disconnecting");
          else if (originating_peer->their_state == peer_connection::their_connection_state::connection_rejected)
            disconnect_from_peer(originating_peer, "I rejected your connection request (hello message) so I'm disconnecting");
          else
          {
            fc::optional<fc::ip::endpoint> inbound_endpoint = originating_peer->get_endpoint_for_connecting();
            if (inbound_endpoint)
            {
              // mark the connection as successful in the database
              fc::optional<potential_peer_record> updated_peer_record = _potential_peer_db.lookup_entry_for_endpoint(*inbound_endpoint);
              if (updated_peer_record)
              {
                updated_peer_record->last_connection_disposition = last_connection_succeeded;
                _potential_peer_db.update_entry(*updated_peer_record);
              }
            }
  
            originating_peer->negotiation_status = peer_connection::connection_negotiation_status::negotiation_complete;
            move_peer_to_active_list(originating_peer->shared_from_this());
            new_peer_just_added(originating_peer->shared_from_this());
          }
        }
        // else if this was an active connection, then this was just a reply to our periodic address requests.
        // we've processed it, there's nothing else to do
      }
  
      void node_impl::on_fetch_blockchain_item_ids_message(peer_connection* originating_peer,
                                                           const fetch_blockchain_item_ids_message& fetch_blockchain_item_ids_message_received)
      {
        VERIFY_CORRECT_THREAD();
        item_id peers_last_item_seen = item_id(fetch_blockchain_item_ids_message_received.item_type, item_hash_t());
        if (fetch_blockchain_item_ids_message_received.blockchain_synopsis.empty())
        {
          dlog("sync: received a request for item ids starting at the beginning of the chain from peer ${peer_endpoint} (full request: ${synopsis})",
               ("peer_endpoint", originating_peer->get_remote_endpoint())
               ("synopsis", fetch_blockchain_item_ids_message_received.blockchain_synopsis));
        }
        else
        {
          item_hash_t peers_last_item_hash_seen = fetch_blockchain_item_ids_message_received.blockchain_synopsis.back();
          dlog("sync: received a request for item ids after ${last_item_seen} from peer ${peer_endpoint} (full request: ${synopsis})",
               ("last_item_seen", peers_last_item_hash_seen)
               ("peer_endpoint", originating_peer->get_remote_endpoint())
               ("synopsis", fetch_blockchain_item_ids_message_received.blockchain_synopsis));
          peers_last_item_seen.item_hash = peers_last_item_hash_seen;
        }
  
        blockchain_item_ids_inventory_message reply_message;
        reply_message.item_type = fetch_blockchain_item_ids_message_received.item_type;
        reply_message.total_remaining_item_count = 0;
        try
        {
          reply_message.item_hashes_available = _delegate->get_block_ids(fetch_blockchain_item_ids_message_received.blockchain_synopsis,
                                                                         reply_message.total_remaining_item_count);
        }
        catch (const peer_is_on_an_unreachable_fork&)
        {
          dlog("Peer is on a fork and there's no set of blocks we can provide to switch them to our fork");
          // we reply with an empty list as if we had an empty blockchain; 
          // we don't want to disconnect because they may be able to provide
          // us with blocks on their chain
        }
  
        bool disconnect_from_inhibited_peer = false;
        // if our client doesn't have any items after the item the peer requested, it will send back
        // a list containing the last item the peer requested
        wdump((reply_message)(fetch_blockchain_item_ids_message_received.blockchain_synopsis));
        if( reply_message.item_hashes_available.empty() )
          originating_peer->peer_needs_sync_items_from_us = false; /* I have no items in my blockchain */
        else if( !fetch_blockchain_item_ids_message_received.blockchain_synopsis.empty() &&
                 reply_message.item_hashes_available.size() == 1 &&
                 std::find(fetch_blockchain_item_ids_message_received.blockchain_synopsis.begin(),
                           fetch_blockchain_item_ids_message_received.blockchain_synopsis.end(),
                           reply_message.item_hashes_available.back() ) != fetch_blockchain_item_ids_message_received.blockchain_synopsis.end() )
        {
          /* the last item in the peer's list matches the last item in our list */
          originating_peer->peer_needs_sync_items_from_us = false;
          if (originating_peer->inhibit_fetching_sync_blocks)
            disconnect_from_inhibited_peer = true; // delay disconnecting until after we send our reply to this fetch_blockchain_item_ids_message
        }
        else
          originating_peer->peer_needs_sync_items_from_us = true;
  
        if (!originating_peer->peer_needs_sync_items_from_us)
        {
          dlog("sync: peer is already in sync with us");
          // if we thought we had all the items this peer had, but now it turns out that we don't
          // have the last item it requested to send from,
          // we need to kick off another round of synchronization
          if (!originating_peer->we_need_sync_items_from_peer &&
              !fetch_blockchain_item_ids_message_received.blockchain_synopsis.empty() &&
              !_delegate->has_item(peers_last_item_seen))
          {
            dlog("sync: restarting sync with peer ${peer}", ("peer", originating_peer->get_remote_endpoint()));
            start_synchronizing_with_peer(originating_peer->shared_from_this());
          }
        }
        else
        {
          dlog("sync: peer is out of sync, sending peer ${count} items ids: first: ${first_item_id}, last: ${last_item_id}",
               ("count", reply_message.item_hashes_available.size())
               ("first_item_id", reply_message.item_hashes_available.front())
               ("last_item_id", reply_message.item_hashes_available.back()));
          if (!originating_peer->we_need_sync_items_from_peer &&
              !fetch_blockchain_item_ids_message_received.blockchain_synopsis.empty() &&
              !_delegate->has_item(peers_last_item_seen))
          {
            dlog("sync: restarting sync with peer ${peer}", ("peer", originating_peer->get_remote_endpoint()));
            start_synchronizing_with_peer(originating_peer->shared_from_this());
          }
        }
        originating_peer->send_message(reply_message);
  
        if (disconnect_from_inhibited_peer)
          {
          // the peer has all of our blocks, and we don't want any of theirs, so disconnect them
          disconnect_from_peer(originating_peer, "you are on a fork that I'm unable to switch to");
          return;
          }
  
        if (originating_peer->direction == peer_connection_direction::inbound &&
            _handshaking_connections.find(originating_peer->shared_from_this()) != _handshaking_connections.end())
        {
          // handshaking is done, move the connection to fully active status and start synchronizing
          dlog("peer ${endpoint} which was handshaking with us has started synchronizing with us, start syncing with it",
               ("endpoint", originating_peer->get_remote_endpoint()));
          fc::optional<fc::ip::endpoint> inbound_endpoint = originating_peer->get_endpoint_for_connecting();
          if (inbound_endpoint)
          {
            // mark the connection as successful in the database
            potential_peer_record updated_peer_record = _potential_peer_db.lookup_or_create_entry_for_endpoint(*inbound_endpoint);
            updated_peer_record.last_connection_disposition = last_connection_succeeded;
            _potential_peer_db.update_entry(updated_peer_record);
          }
  
          // transition it to our active list
          move_peer_to_active_list(originating_peer->shared_from_this());
          new_peer_just_added(originating_peer->shared_from_this());
        }
      }
  
      uint32_t node_impl::calculate_unsynced_block_count_from_all_peers()
      {
        VERIFY_CORRECT_THREAD();
        uint32_t max_number_of_unfetched_items = 0;
        for( const peer_connection_ptr& peer : _active_connections )
        {
          uint32_t this_peer_number_of_unfetched_items = (uint32_t)peer->ids_of_items_to_get.size() + peer->number_of_unfetched_item_ids;
          max_number_of_unfetched_items = std::max(max_number_of_unfetched_items,
                                                   this_peer_number_of_unfetched_items);
        }
        return max_number_of_unfetched_items;
      }
  
      // get a blockchain synopsis that makes sense to send to the given peer.
      // If the peer isn't yet syncing with us, this is just a synopsis of our active blockchain
      // If the peer is syncing with us, it is a synopsis of our active blockchain plus the
      //    blocks the peer has already told us it has
      std::vector<item_hash_t> node_impl::create_blockchain_synopsis_for_peer( const peer_connection* peer )
      {
        VERIFY_CORRECT_THREAD();
        item_hash_t reference_point = peer->last_block_delegate_has_seen;
        uint32_t reference_point_block_num = _delegate->get_block_number(peer->last_block_delegate_has_seen);
  
        // when we call _delegate->get_blockchain_synopsis(), we may yield and there's a
        // chance this peer's state will change before we get control back.  Save off
        // the stuff necessary for generating the synopsis.
        // This is pretty expensive, we should find a better way to do this
        std::vector<item_hash_t> original_ids_of_items_to_get(peer->ids_of_items_to_get.begin(), peer->ids_of_items_to_get.end());
        uint32_t number_of_blocks_after_reference_point = original_ids_of_items_to_get.size();
  
        std::vector<item_hash_t> synopsis = _delegate->get_blockchain_synopsis(reference_point, number_of_blocks_after_reference_point);
  
  #if 0
        // just for debugging, enable this and set a breakpoint to step through
        if (synopsis.empty())
          synopsis = _delegate->get_blockchain_synopsis(reference_point, number_of_blocks_after_reference_point);
  
        // TODO: it's possible that the returned synopsis is empty if the blockchain is empty (that's fine)
        // or if the reference point is now past our undo history (that's not). 
        // in the second case, we should mark this peer as one we're unable to sync with and
        // disconnect them.
        if (reference_point != item_hash_t() && synopsis.empty())
          FC_THROW_EXCEPTION(block_older_than_undo_history, "You are on a fork I'm unable to switch to");
  #endif
  
        if( number_of_blocks_after_reference_point )
        {
          // then the synopsis is incomplete, add the missing elements from ids_of_items_to_get
          uint32_t first_block_num_in_ids_to_get = _delegate->get_block_number(original_ids_of_items_to_get.front());
          uint32_t true_high_block_num = first_block_num_in_ids_to_get + original_ids_of_items_to_get.size() - 1;
  
          // in order to generate a seamless synopsis, we need to be using the same low_block_num as the 
          // backend code; the first block in the synopsis will be the low block number it used
          uint32_t low_block_num = synopsis.empty() ? 1 : _delegate->get_block_number(synopsis.front());
          
          do
          {
            if( low_block_num >= first_block_num_in_ids_to_get )
              synopsis.push_back(original_ids_of_items_to_get[low_block_num - first_block_num_in_ids_to_get]);
            low_block_num += (true_high_block_num - low_block_num + 2 ) / 2;
          }
          while ( low_block_num <= true_high_block_num );
          assert(synopsis.back() == original_ids_of_items_to_get.back());
        }
        return synopsis;
      }
  
      void node_impl::fetch_next_batch_of_item_ids_from_peer( peer_connection* peer, bool reset_fork_tracking_data_for_peer /* = false */ )
      {
        VERIFY_CORRECT_THREAD();
        if( reset_fork_tracking_data_for_peer )
        {
          peer->last_block_delegate_has_seen = item_hash_t();
          peer->last_block_time_delegate_has_seen = _delegate->get_block_time(item_hash_t());
        }
  
        fc::oexception synopsis_exception;
        try
        {
          std::vector<item_hash_t> blockchain_synopsis = create_blockchain_synopsis_for_peer( peer );
        
          item_hash_t last_item_seen = blockchain_synopsis.empty() ? item_hash_t() : blockchain_synopsis.back();
          dlog( "sync: sending a request for the next items after ${last_item_seen} to peer ${peer}, (full request is ${blockchain_synopsis})",
               ( "last_item_seen", last_item_seen )
               ( "peer", peer->get_remote_endpoint() )
               ( "blockchain_synopsis", blockchain_synopsis ) );
          peer->item_ids_requested_from_peer = boost::make_tuple( blockchain_synopsis, fc::time_point::now() );
          peer->send_message( fetch_blockchain_item_ids_message(_sync_item_type, blockchain_synopsis ) );
        }
        catch (const block_older_than_undo_history& e)
        {
          synopsis_exception = e;
        }
        if (synopsis_exception)
          disconnect_from_peer(peer, "You are on a fork I'm unable to switch to");
      }
  
      void node_impl::on_blockchain_item_ids_inventory_message(peer_connection* originating_peer,
                                                               const blockchain_item_ids_inventory_message& blockchain_item_ids_inventory_message_received )
      {
        VERIFY_CORRECT_THREAD();
        // ignore unless we asked for the data
        if( originating_peer->item_ids_requested_from_peer )
        {
          // verify that the peer's the block ids the peer sent is a valid response to our request;
          // It should either be an empty list of blocks, or a list of blocks that builds off of one of 
          // the blocks in the synopsis we sent
          if (!blockchain_item_ids_inventory_message_received.item_hashes_available.empty())
          {
            // what's more, it should be a sequential list of blocks, verify that first
            uint32_t first_block_number_in_reponse = _delegate->get_block_number(blockchain_item_ids_inventory_message_received.item_hashes_available.front());
            for (unsigned i = 1; i < blockchain_item_ids_inventory_message_received.item_hashes_available.size(); ++i)
            {
              uint32_t actual_num = _delegate->get_block_number(blockchain_item_ids_inventory_message_received.item_hashes_available[i]);
              uint32_t expected_num = first_block_number_in_reponse + i;
              if (actual_num != expected_num)
              {
              wlog("Invalid response from peer ${peer_endpoint}.  The list of blocks they provided is not sequential, "
                   "the ${position}th block in their reply was block number ${actual_num}, "
                   "but it should have been number ${expected_num}",
                   ("peer_endpoint", originating_peer->get_remote_endpoint())
                   ("position", i)
                   ("actual_num", actual_num)
                   ("expected_num", expected_num));
              fc::exception error_for_peer(FC_LOG_MESSAGE(error, 
                                                          "You gave an invalid response to my request for sync blocks.  The list of blocks you provided is not sequential, "
                                                          "the ${position}th block in their reply was block number ${actual_num}, "
                                                          "but it should have been number ${expected_num}",
                                                          ("position", i)
                                                          ("actual_num", actual_num)
                                                          ("expected_num", expected_num)));
              disconnect_from_peer(originating_peer,
                                   "You gave an invalid response to my request for sync blocks",
                                   true, error_for_peer);
              return;
              }
            }
  
            const std::vector<item_hash_t>& synopsis_sent_in_request = originating_peer->item_ids_requested_from_peer->get<0>();
            const item_hash_t& first_item_hash = blockchain_item_ids_inventory_message_received.item_hashes_available.front();
  
            if (synopsis_sent_in_request.empty())
            {
              // if we sent an empty synopsis, we were asking for all blocks, so the first block should be block 1
              if (_delegate->get_block_number(first_item_hash) != 1)
              {
                wlog("Invalid response from peer ${peer_endpoint}.  We requested a list of sync blocks starting from the beginning of the chain, "
                     "but they provided a list of blocks starting with ${first_block}",
                     ("peer_endpoint", originating_peer->get_remote_endpoint())
                     ("first_block", first_item_hash));
                fc::exception error_for_peer(FC_LOG_MESSAGE(error, "You gave an invalid response for my request for sync blocks.  I asked for blocks starting from the beginning of the chain, "
                                                            "but you returned a list of blocks starting with ${first_block}",  
                                                            ("first_block", first_item_hash)));
                disconnect_from_peer(originating_peer,
                                     "You gave an invalid response to my request for sync blocks",
                                     true, error_for_peer);
                return;
              }
            }
            else // synopsis was not empty, we expect a response building off one of the blocks we sent
            {
              if (boost::range::find(synopsis_sent_in_request, first_item_hash) == synopsis_sent_in_request.end())
              {
                wlog("Invalid response from peer ${peer_endpoint}.  We requested a list of sync blocks based on the synopsis ${synopsis}, but they "
                     "provided a list of blocks starting with ${first_block}",
                     ("peer_endpoint", originating_peer->get_remote_endpoint())
                     ("synopsis", synopsis_sent_in_request)
                     ("first_block", first_item_hash));
                fc::exception error_for_peer(FC_LOG_MESSAGE(error, "You gave an invalid response for my request for sync blocks.  I asked for blocks following something in "
                                                            "${synopsis}, but you returned a list of blocks starting with ${first_block} which wasn't one of your choices",  
                                                            ("synopsis", synopsis_sent_in_request)
                                                            ("first_block", first_item_hash)));
                disconnect_from_peer(originating_peer,
                                     "You gave an invalid response to my request for sync blocks",
                                     true, error_for_peer);
                return;
              }
            }
          }
          originating_peer->item_ids_requested_from_peer.reset();
  
          dlog( "sync: received a list of ${count} available items from ${peer_endpoint}",
               ( "count", blockchain_item_ids_inventory_message_received.item_hashes_available.size() )
               ( "peer_endpoint", originating_peer->get_remote_endpoint() ) );
          //for( const item_hash_t& item_hash : blockchain_item_ids_inventory_message_received.item_hashes_available )
          //{
          //  dlog( "sync:     ${hash}", ("hash", item_hash ) );
          //}
  
          // if the peer doesn't have any items after the one we asked for
          if( blockchain_item_ids_inventory_message_received.total_remaining_item_count == 0 &&
              ( blockchain_item_ids_inventory_message_received.item_hashes_available.empty() || // there are no items in the peer's blockchain.  this should only happen if our blockchain was empty when we requested, might want to verify that.
               ( blockchain_item_ids_inventory_message_received.item_hashes_available.size() == 1 &&
                _delegate->has_item( item_id(blockchain_item_ids_inventory_message_received.item_type,
                                            blockchain_item_ids_inventory_message_received.item_hashes_available.front() ) ) ) ) && // we've already seen the last item in the peer's blockchain
              originating_peer->ids_of_items_to_get.empty() &&
              originating_peer->number_of_unfetched_item_ids == 0 ) // <-- is the last check necessary?
          {
            dlog( "sync: peer said we're up-to-date, entering normal operation with this peer" );
            originating_peer->we_need_sync_items_from_peer = false;
  
            uint32_t new_number_of_unfetched_items = calculate_unsynced_block_count_from_all_peers();
            _total_number_of_unfetched_items = new_number_of_unfetched_items;
            if( new_number_of_unfetched_items == 0 )
              _delegate->sync_status( blockchain_item_ids_inventory_message_received.item_type, 0 );
  
            return;
          }
  
          std::deque<item_hash_t> item_hashes_received( blockchain_item_ids_inventory_message_received.item_hashes_available.begin(),
                                                       blockchain_item_ids_inventory_message_received.item_hashes_available.end() );
          originating_peer->number_of_unfetched_item_ids = blockchain_item_ids_inventory_message_received.total_remaining_item_count;
          // flush any items this peer sent us that we've already received and processed from another peer
          if (!item_hashes_received.empty() &&
              originating_peer->ids_of_items_to_get.empty())
          {
            bool is_first_item_for_other_peer = false;
            for (const peer_connection_ptr& peer : _active_connections)
              if (peer != originating_peer->shared_from_this() &&
                  !peer->ids_of_items_to_get.empty() &&
                  peer->ids_of_items_to_get.front() == blockchain_item_ids_inventory_message_received.item_hashes_available.front())
              {
                dlog("The item ${newitem} is the first item for peer ${peer}",
                     ("newitem", blockchain_item_ids_inventory_message_received.item_hashes_available.front())
                     ("peer", peer->get_remote_endpoint()));
                is_first_item_for_other_peer = true;
                break;
              }
            dlog("is_first_item_for_other_peer: ${is_first}.  item_hashes_received.size() = ${size}",
                 ("is_first", is_first_item_for_other_peer)("size", item_hashes_received.size()));
            if (!is_first_item_for_other_peer)
            {
              while (!item_hashes_received.empty() &&
                     _delegate->has_item(item_id(blockchain_item_ids_inventory_message_received.item_type,
                                                 item_hashes_received.front())))
              {
                assert(item_hashes_received.front() != item_hash_t());
                originating_peer->last_block_delegate_has_seen = item_hashes_received.front();
                originating_peer->last_block_time_delegate_has_seen = _delegate->get_block_time(item_hashes_received.front());
                dlog("popping item because delegate has already seen it.  peer ${peer}'s last block the delegate has seen is now ${block_id} (actual block #${actual_block_num})",
                     ("peer", originating_peer->get_remote_endpoint())
                     ("block_id", originating_peer->last_block_delegate_has_seen)
                     ("actual_block_num", _delegate->get_block_number(item_hashes_received.front())));
  
                item_hashes_received.pop_front();
              }
              dlog("after removing all items we have already seen, item_hashes_received.size() = ${size}", ("size", item_hashes_received.size()));
            }
          }
          else if (!item_hashes_received.empty())
          {
            // we received a list of items and we already have a list of items to fetch from this peer.
            // In the normal case, this list will immediately follow the existing list, meaning the
            // last hash of our existing list will match the first hash of the new list.
  
            // In the much less likely case, we've received a partial list of items from the peer, then
            // the peer switched forks before sending us the remaining list.  In this case, the first
            // hash in the new list may not be the last hash in the existing list (it may be earlier, or
            // it may not exist at all.
  
            // In either case, pop items off the back of our existing list until we find our first
            // item, then append our list.
            while (!originating_peer->ids_of_items_to_get.empty())
            {
              if (item_hashes_received.front() != originating_peer->ids_of_items_to_get.back())
                originating_peer->ids_of_items_to_get.pop_back();
              else
                break;
            }
            if (originating_peer->ids_of_items_to_get.empty())
            {
              // this happens when the peer has switched forks between the last inventory message and
              // this one, and there weren't any unfetched items in common
              // We don't know where in the blockchain the new front() actually falls, all we can
              // expect is that it is a block that we knew about because it should be one of the
              // blocks we sent in the initial synopsis.
              assert(_delegate->has_item(item_id(_sync_item_type, item_hashes_received.front())));
              originating_peer->last_block_delegate_has_seen = item_hashes_received.front();
              originating_peer->last_block_time_delegate_has_seen = _delegate->get_block_time(item_hashes_received.front());
              item_hashes_received.pop_front();
            }
            else
            {
              // the common simple case: the new list extends the old.  pop off the duplicate element
              originating_peer->ids_of_items_to_get.pop_back();
            }
          }
  
          if (!item_hashes_received.empty() && !originating_peer->ids_of_items_to_get.empty())
            assert(item_hashes_received.front() != originating_peer->ids_of_items_to_get.back());
  
          // append the remaining items to the peer's list
          boost::push_back(originating_peer->ids_of_items_to_get, item_hashes_received);
  
          originating_peer->number_of_unfetched_item_ids = blockchain_item_ids_inventory_message_received.total_remaining_item_count;
  
          // at any given time, there's a maximum number of blocks that can possibly be out there
          // [(now - genesis time) / block interval].  If they offer us more blocks than that,
          // they must be an attacker or have a buggy client.
          fc::time_point_sec minimum_time_of_last_offered_block =
              originating_peer->last_block_time_delegate_has_seen + // timestamp of the block immediately before the first unfetched block
              originating_peer->number_of_unfetched_item_ids * GRAPHENE_MIN_BLOCK_INTERVAL;
          fc::time_point_sec now = fc::time_point::now();
          if (minimum_time_of_last_offered_block > now + GRAPHENE_NET_FUTURE_SYNC_BLOCKS_GRACE_PERIOD_SEC)
          {
            wlog("Disconnecting from peer ${peer} who offered us an implausible number of blocks, their last block would be in the future (${timestamp})",
                 ("peer", originating_peer->get_remote_endpoint())
                 ("timestamp", minimum_time_of_last_offered_block));
            fc::exception error_for_peer(FC_LOG_MESSAGE(error, "You offered me a list of more sync blocks than could possibly exist.  Total blocks offered: ${blocks}, Minimum time of the last block you offered: ${minimum_time_of_last_offered_block}, Now: ${now}",
                                                        ("blocks", originating_peer->number_of_unfetched_item_ids)
                                                        ("minimum_time_of_last_offered_block", minimum_time_of_last_offered_block)
                                                        ("now", now)));
            disconnect_from_peer(originating_peer,
                                 "You offered me a list of more sync blocks than could possibly exist",
                                 true, error_for_peer);
            return;
          }
  
          uint32_t new_number_of_unfetched_items = calculate_unsynced_block_count_from_all_peers();
          if (new_number_of_unfetched_items != _total_number_of_unfetched_items)
            _delegate->sync_status(blockchain_item_ids_inventory_message_received.item_type,
                                   new_number_of_unfetched_items);
          _total_number_of_unfetched_items = new_number_of_unfetched_items;
  
          if (blockchain_item_ids_inventory_message_received.total_remaining_item_count != 0)
          {
            // the peer hasn't sent us all the items it knows about.
            if (originating_peer->ids_of_items_to_get.size() > GRAPHENE_NET_MIN_BLOCK_IDS_TO_PREFETCH)
            {
              // we have a good number of item ids from this peer, start fetching blocks from it;
              // we'll switch back later to finish the job.
              trigger_fetch_sync_items_loop();
            }
            else
            {
              // keep fetching the peer's list of sync items until we get enough to switch into block-
              // fetchimg mode
              fetch_next_batch_of_item_ids_from_peer(originating_peer);
            }
          }
          else
          {
            // the peer has told us about all of the items it knows
            if (!originating_peer->ids_of_items_to_get.empty())
            {
              // we now know about all of the items the peer knows about, and there are some items on the list
              // that we should try to fetch.  Kick off the fetch loop.
              trigger_fetch_sync_items_loop();
            }
            else
            {
              // If we get here, the peer has sent us a non-empty list of items, but we have already
              // received all of the items from other peers.  Send a new request to the peer to
              // see if we're really in sync
              fetch_next_batch_of_item_ids_from_peer(originating_peer);
            }
          }
        }
        else
        {
          wlog("sync: received a list of sync items available, but I didn't ask for any!");
        }
      }
  
      message node_impl::get_message_for_item(const item_id& item)
      {
        try
        {
          return _message_cache.get_message(item.item_hash);
        }
        catch (fc::key_not_found_exception&)
        {}
        try
        {
          return _delegate->get_item(item);
        }
        catch (fc::key_not_found_exception&)
        {}
        return item_not_available_message(item);
      }
  
      void node_impl::on_fetch_items_message(peer_connection* originating_peer, const fetch_items_message& fetch_items_message_received)
      {
        VERIFY_CORRECT_THREAD();
        dlog("received items request for ids ${ids} of type ${type} from peer ${endpoint}",
             ("ids", fetch_items_message_received.items_to_fetch)
             ("type", fetch_items_message_received.item_type)
             ("endpoint", originating_peer->get_remote_endpoint()));
  
        fc::optional<message> last_block_message_sent;
  
        std::list<message> reply_messages;
        for (const item_hash_t& item_hash : fetch_items_message_received.items_to_fetch)
        {
          try
          {
            message requested_message = _message_cache.get_message(item_hash);
            dlog("received item request for item ${id} from peer ${endpoint}, returning the item from my message cache",
                 ("endpoint", originating_peer->get_remote_endpoint())
                 ("id", requested_message.id()));
            reply_messages.push_back(requested_message);
            if (fetch_items_message_received.item_type == block_message_type)
              last_block_message_sent = requested_message;
            continue;
          }
          catch (fc::key_not_found_exception&)
          {
             // it wasn't in our local cache, that's ok ask the client
          }
  
          item_id item_to_fetch(fetch_items_message_received.item_type, item_hash);
          try
          {
            message requested_message = _delegate->get_item(item_to_fetch);
            dlog("received item request from peer ${endpoint}, returning the item from delegate with id ${id} size ${size}",
                 ("id", requested_message.id())
                 ("size", requested_message.size)
                 ("endpoint", originating_peer->get_remote_endpoint()));
            reply_messages.push_back(requested_message);
            if (fetch_items_message_received.item_type == block_message_type)
              last_block_message_sent = requested_message;
            continue;
          }
          catch (fc::key_not_found_exception&)
          {
            reply_messages.push_back(item_not_available_message(item_to_fetch));
            dlog("received item request from peer ${endpoint} but we don't have it",
                 ("endpoint", originating_peer->get_remote_endpoint()));
          }
        }
  
        // if we sent them a block, update our record of the last block they've seen accordingly
        if (last_block_message_sent)
        {
          graphene::net::block_message block = last_block_message_sent->as<graphene::net::block_message>();
          originating_peer->last_block_delegate_has_seen = block.block_id;
          originating_peer->last_block_time_delegate_has_seen = _delegate->get_block_time(block.block_id);
        }
  
        for (const message& reply : reply_messages)
        {
          if (reply.msg_type == block_message_type)
            originating_peer->send_item(item_id(block_message_type, reply.as<graphene::net::block_message>().block_id));
          else
            originating_peer->send_message(reply);
        }
      }
  
      void node_impl::on_item_not_available_message( peer_connection* originating_peer, const item_not_available_message& item_not_available_message_received )
      {
        VERIFY_CORRECT_THREAD();
        const item_id& requested_item = item_not_available_message_received.requested_item;
        auto regular_item_iter = originating_peer->items_requested_from_peer.find(requested_item);
        if (regular_item_iter != originating_peer->items_requested_from_peer.end())
        {
          originating_peer->items_requested_from_peer.erase( regular_item_iter );
          originating_peer->inventory_peer_advertised_to_us.erase( requested_item );
          if (is_item_in_any_peers_inventory(requested_item))
            _items_to_fetch.insert(prioritized_item_id(requested_item, _items_to_fetch_sequence_counter++));
          wlog("Peer doesn't have the requested item.");
          trigger_fetch_items_loop();
          return;
        }
  
        auto sync_item_iter = originating_peer->sync_items_requested_from_peer.find(requested_item);
        if (sync_item_iter != originating_peer->sync_items_requested_from_peer.end())
        {
          originating_peer->sync_items_requested_from_peer.erase(sync_item_iter);
  
          if (originating_peer->peer_needs_sync_items_from_us)
            originating_peer->inhibit_fetching_sync_blocks = true;
          else
            disconnect_from_peer(originating_peer, "You are missing a sync item you claim to have, your database is probably corrupted. Try --rebuild-index.",true,
                                 fc::exception(FC_LOG_MESSAGE(error,"You are missing a sync item you claim to have, your database is probably corrupted. Try --rebuild-index.",
                                 ("item_id",requested_item))));
          wlog("Peer doesn't have the requested sync item.  This really shouldn't happen");
          trigger_fetch_sync_items_loop();
          return;
        }
  
        dlog("Peer doesn't have an item we're looking for, which is fine because we weren't looking for it");
      }
  
      void node_impl::on_item_ids_inventory_message(peer_connection* originating_peer, const item_ids_inventory_message& item_ids_inventory_message_received)
      {
        VERIFY_CORRECT_THREAD();
  
        // expire old inventory so we'll be making decisions our about whether to fetch blocks below based only on recent inventory
        originating_peer->clear_old_inventory();
  
        dlog( "received inventory of ${count} items from peer ${endpoint}",
             ( "count", item_ids_inventory_message_received.item_hashes_available.size() )("endpoint", originating_peer->get_remote_endpoint() ) );
        for( const item_hash_t& item_hash : item_ids_inventory_message_received.item_hashes_available )
        {
          item_id advertised_item_id(item_ids_inventory_message_received.item_type, item_hash);
          bool we_advertised_this_item_to_a_peer = false;
          bool we_requested_this_item_from_a_peer = false;
          for (const peer_connection_ptr peer : _active_connections)
          {
            if (peer->inventory_advertised_to_peer.find(advertised_item_id) != peer->inventory_advertised_to_peer.end())
            {
              we_advertised_this_item_to_a_peer = true;
              break;
            }
            if (peer->items_requested_from_peer.find(advertised_item_id) != peer->items_requested_from_peer.end())
              we_requested_this_item_from_a_peer = true;
          }
  
          // if we have already advertised it to a peer, we must have it, no need to do anything else
          if (!we_advertised_this_item_to_a_peer)
          {
            // if the peer has flooded us with transactions, don't add these to the inventory to prevent our
            // inventory list from growing without bound.  We try to allow fetching blocks even when
            // we've stopped fetching transactions.
            if ((item_ids_inventory_message_received.item_type == graphene::net::trx_message_type &&
                 originating_peer->is_inventory_advertised_to_us_list_full_for_transactions()) ||
                originating_peer->is_inventory_advertised_to_us_list_full())
              break;
            originating_peer->inventory_peer_advertised_to_us.insert(peer_connection::timestamped_item_id(advertised_item_id, fc::time_point::now()));
            if (!we_requested_this_item_from_a_peer)
            {
              if (_recently_failed_items.find(item_id(item_ids_inventory_message_received.item_type, item_hash)) != _recently_failed_items.end())
              {
                dlog("not adding ${item_hash} to our list of items to fetch because we've recently fetched a copy and it failed to push",
                     ("item_hash", item_hash));
              }
              else
              {
                auto items_to_fetch_iter = _items_to_fetch.get<item_id_index>().find(advertised_item_id);
                if (items_to_fetch_iter == _items_to_fetch.get<item_id_index>().end())
                {
                  // it's new to us
                  _items_to_fetch.insert(prioritized_item_id(advertised_item_id, _items_to_fetch_sequence_counter++));
                  dlog("adding item ${item_hash} from inventory message to our list of items to fetch",
                       ("item_hash", item_hash));
                  trigger_fetch_items_loop();
                }
                else
                {
                  // another peer has told us about this item already, but this peer just told us it has the item
                  // too, we can expect it to be around in this peer's cache for longer, so update its timestamp
                  _items_to_fetch.get<item_id_index>().modify(items_to_fetch_iter,
                                                              [](prioritized_item_id& item) { item.timestamp = fc::time_point::now(); });
                } 
              }
            }
          }
        }
  
      }
  
      void node_impl::on_closing_connection_message( peer_connection* originating_peer, const closing_connection_message& closing_connection_message_received )
      {
        VERIFY_CORRECT_THREAD();
        originating_peer->they_have_requested_close = true;
  
        if( closing_connection_message_received.closing_due_to_error )
        {
          elog( "Peer ${peer} is disconnecting us because of an error: ${msg}, exception: ${error}",
               ( "peer", originating_peer->get_remote_endpoint() )
               ( "msg", closing_connection_message_received.reason_for_closing )
               ( "error", closing_connection_message_received.error ) );
          std::ostringstream message;
          message << "Peer " << fc::variant( originating_peer->get_remote_endpoint() ).as_string() <<
                    " disconnected us: " << closing_connection_message_received.reason_for_closing;
          fc::exception detailed_error(FC_LOG_MESSAGE(warn, "Peer ${peer} is disconnecting us because of an error: ${msg}, exception: ${error}",
                                                      ( "peer", originating_peer->get_remote_endpoint() )
                                                      ( "msg", closing_connection_message_received.reason_for_closing )
                                                      ( "error", closing_connection_message_received.error ) ));
          _delegate->error_encountered( message.str(),
                                        detailed_error );
        }
        else
        {
          wlog( "Peer ${peer} is disconnecting us because: ${msg}",
               ( "peer", originating_peer->get_remote_endpoint() )
               ( "msg", closing_connection_message_received.reason_for_closing ) );
        }
        if( originating_peer->we_have_requested_close )
          originating_peer->close_connection();
        }
  
      void node_impl::on_connection_closed(peer_connection* originating_peer)
      {
        VERIFY_CORRECT_THREAD();
        peer_connection_ptr originating_peer_ptr = originating_peer->shared_from_this();
        _rate_limiter.remove_tcp_socket( &originating_peer->get_socket() );
  
        // if we closed the connection (due to timeout or handshake failure), we should have recorded an
        // error message to store in the peer database when we closed the connection
        fc::optional<fc::ip::endpoint> inbound_endpoint = originating_peer->get_endpoint_for_connecting();
        if (originating_peer->connection_closed_error && inbound_endpoint)
        {
          fc::optional<potential_peer_record> updated_peer_record = _potential_peer_db.lookup_entry_for_endpoint(*inbound_endpoint);
          if (updated_peer_record)
          {
            updated_peer_record->last_error = *originating_peer->connection_closed_error;
            _potential_peer_db.update_entry(*updated_peer_record);
          }
        }
  
        _closing_connections.erase(originating_peer_ptr);
        _handshaking_connections.erase(originating_peer_ptr);
        _terminating_connections.erase(originating_peer_ptr);
        if (_active_connections.find(originating_peer_ptr) != _active_connections.end())
        {
          _active_connections.erase(originating_peer_ptr);
  
          if (inbound_endpoint && originating_peer_ptr->get_remote_endpoint())
          {
            fc::optional<potential_peer_record> updated_peer_record = _potential_peer_db.lookup_entry_for_endpoint(*inbound_endpoint);
            if (updated_peer_record)
            {
              updated_peer_record->last_seen_time = fc::time_point::now();
              _potential_peer_db.update_entry(*updated_peer_record);
            }
          }
        }
  
        ilog("Remote peer ${endpoint} closed their connection to us", ("endpoint", originating_peer->get_remote_endpoint()));
        display_current_connections();
        trigger_p2p_network_connect_loop();
  
        // notify the node delegate so it can update the display
        if( _active_connections.size() != _last_reported_number_of_connections )
        {
          _last_reported_number_of_connections = (uint32_t)_active_connections.size();
          _delegate->connection_count_changed( _last_reported_number_of_connections );
        }
  
        // if we had delegated a firewall check to this peer, send it to another peer
        if (originating_peer->firewall_check_state)
        {
          if (originating_peer->firewall_check_state->requesting_peer != node_id_t())
          {
            // it's a check we're doing for another node
            firewall_check_state_data* firewall_check_state = originating_peer->firewall_check_state;
            originating_peer->firewall_check_state = nullptr;
            forward_firewall_check_to_next_available_peer(firewall_check_state);
          }
          else
          {
            // we were asking them to check whether we're firewalled.  we'll just let it
            // go for now
            delete originating_peer->firewall_check_state;
          }
        }
  
        // if we had requested any sync or regular items from this peer that we haven't
        // received yet, reschedule them to be fetched from another peer
        if (!originating_peer->sync_items_requested_from_peer.empty())
        {
          for (auto sync_item_and_time : originating_peer->sync_items_requested_from_peer)
            _active_sync_requests.erase(sync_item_and_time.first.item_hash);
          trigger_fetch_sync_items_loop();
        }
  
        if (!originating_peer->items_requested_from_peer.empty())
        {
          for (auto item_and_time : originating_peer->items_requested_from_peer)
          {
            if (is_item_in_any_peers_inventory(item_and_time.first))
              _items_to_fetch.insert(prioritized_item_id(item_and_time.first, _items_to_fetch_sequence_counter++));
          }
          trigger_fetch_items_loop();
        }
  
        schedule_peer_for_deletion(originating_peer_ptr);
      }
  
      void node_impl::send_sync_block_to_node_delegate(const graphene::net::block_message& block_message_to_send)
      {
        dlog("in send_sync_block_to_node_delegate()");
        bool client_accepted_block = false;
        bool discontinue_fetching_blocks_from_peer = false;
  
        fc::oexception handle_message_exception;
  
        try
        {
          std::vector<fc::uint160_t> contained_transaction_message_ids;
          _delegate->handle_block(block_message_to_send, true, contained_transaction_message_ids,true);
          ilog("Successfully pushed sync block ${num} (id:${id})",
               ("num", block_message_to_send.block.block_num())
               ("id", block_message_to_send.block_id));
          _most_recent_blocks_accepted.push_back(block_message_to_send.block_id);
  
          client_accepted_block = true;
        }
        catch (const block_older_than_undo_history& e)
        {
          wlog("Failed to push sync block ${num} (id:${id}): block is on a fork older than our undo history would "
               "allow us to switch to: ${e}",
               ("num", block_message_to_send.block.block_num())
               ("id", block_message_to_send.block_id)
               ("e", (fc::exception)e));
          handle_message_exception = e;
          discontinue_fetching_blocks_from_peer = true;
        }
        catch (const fc::canceled_exception&)
        {
          throw;
        }
        catch (const fc::exception& e)
        {
          wlog("Failed to push sync block ${num} (id:${id}): client rejected sync block sent by peer: ${e}",
               ("num", block_message_to_send.block.block_num())
               ("id", block_message_to_send.block_id)
               ("e", e));
          handle_message_exception = e;
        }
  
        // build up lists for any potentially-blocking operations we need to do, then do them
        // at the end of this function
        std::set<peer_connection_ptr> peers_with_newly_empty_item_lists;
        std::set<peer_connection_ptr> peers_we_need_to_sync_to;
        std::map<peer_connection_ptr, std::pair<std::string, fc::oexception> > peers_to_disconnect; // map peer -> pair<reason_string, exception>
  
        if( client_accepted_block )
        {
          --_total_number_of_unfetched_items;
          dlog("sync: client accpted the block, we now have only ${count} items left to fetch before we're in sync",
                ("count", _total_number_of_unfetched_items));
          bool is_fork_block = is_hard_fork_block(block_message_to_send.block.block_num());
          for (const peer_connection_ptr& peer : _active_connections)
          {
            ASSERT_TASK_NOT_PREEMPTED(); // don't yield while iterating over _active_connections
            bool disconnecting_this_peer = false;
            if (is_fork_block)
            {
              // we just pushed a hard fork block.  Find out if this peer is running a client
              // that will be unable to process future blocks
              if (peer->last_known_fork_block_number != 0)
              {
                uint32_t next_fork_block_number = get_next_known_hard_fork_block_number(peer->last_known_fork_block_number);
                if (next_fork_block_number != 0 &&
                    next_fork_block_number <= block_message_to_send.block.block_num())
                {
                  std::ostringstream disconnect_reason_stream;
                  disconnect_reason_stream << "You need to upgrade your client due to hard fork at block " << block_message_to_send.block.block_num();
                  peers_to_disconnect[peer] = std::make_pair(disconnect_reason_stream.str(),
                                                             fc::oexception(fc::exception(FC_LOG_MESSAGE(error, "You need to upgrade your client due to hard fork at block ${block_number}",
                                                                                                         ("block_number", block_message_to_send.block.block_num())))));
  #ifdef ENABLE_DEBUG_ULOGS
                  ulog("Disconnecting from peer during sync because their version is too old.  Their version date: ${date}", ("date", peer->graphene_git_revision_unix_timestamp));
  #endif
                  disconnecting_this_peer = true;
                }
              }
            }
            if (!disconnecting_this_peer &&
                peer->ids_of_items_to_get.empty() && peer->ids_of_items_being_processed.empty())
            {
              dlog( "Cannot pop first element off peer ${peer}'s list, its list is empty", ("peer", peer->get_remote_endpoint() ) );
              // we don't know for sure that this peer has the item we just received.
              // If peer is still syncing to us, we know they will ask us for
              // sync item ids at least one more time and we'll notify them about
              // the item then, so there's no need to do anything.  If we still need items
              // from them, we'll be asking them for more items at some point, and
              // that will clue them in that they are out of sync.  If we're fully in sync
              // we need to kick off another round of synchronization with them so they can
              // find out about the new item.
              if (!peer->peer_needs_sync_items_from_us && !peer->we_need_sync_items_from_peer)
              {
                dlog("We will be restarting synchronization with peer ${peer}", ("peer", peer->get_remote_endpoint()));
                peers_we_need_to_sync_to.insert(peer);
              }
            }
            else if (!disconnecting_this_peer)
            {
              auto items_being_processed_iter = peer->ids_of_items_being_processed.find(block_message_to_send.block_id);
              if (items_being_processed_iter != peer->ids_of_items_being_processed.end())
              {
                peer->last_block_delegate_has_seen = block_message_to_send.block_id;
                peer->last_block_time_delegate_has_seen = block_message_to_send.block.timestamp;
  
                peer->ids_of_items_being_processed.erase(items_being_processed_iter);
                dlog("Removed item from ${endpoint}'s list of items being processed, still processing ${len} blocks",
                     ("endpoint", peer->get_remote_endpoint())("len", peer->ids_of_items_being_processed.size()));
  
                // if we just received the last item in our list from this peer, we will want to
                // send another request to find out if we are in sync, but we can't do this yet
                // (we don't want to allow a fiber swap in the middle of popping items off the list)
                if (peer->ids_of_items_to_get.empty() &&
                    peer->number_of_unfetched_item_ids == 0 &&
                    peer->ids_of_items_being_processed.empty())
                  peers_with_newly_empty_item_lists.insert(peer);
  
                // in this case, we know the peer was offering us this exact item, no need to
                // try to inform them of its existence
              }
            }
          }
        }
        else
        {
          // invalid message received
          for (const peer_connection_ptr& peer : _active_connections)
          {
            ASSERT_TASK_NOT_PREEMPTED(); // don't yield while iterating over _active_connections
  
            if (peer->ids_of_items_being_processed.find(block_message_to_send.block_id) != peer->ids_of_items_being_processed.end())
            {
              if (discontinue_fetching_blocks_from_peer)
              {
                wlog("inhibiting fetching sync blocks from peer ${endpoint} because it is on a fork that's too old",
                     ("endpoint", peer->get_remote_endpoint()));
                peer->inhibit_fetching_sync_blocks = true;
              }
              else
                peers_to_disconnect[peer] = std::make_pair(std::string("You offered us a block that we reject as invalid"), fc::oexception(handle_message_exception));
            }
          }
        }
  
        for (auto& peer_to_disconnect : peers_to_disconnect)
        {
          const peer_connection_ptr& peer = peer_to_disconnect.first;
          std::string reason_string;
          fc::oexception reason_exception;
          std::tie(reason_string, reason_exception) = peer_to_disconnect.second;
          wlog("disconnecting client ${endpoint} because it offered us the rejected block",
               ("endpoint", peer->get_remote_endpoint()));
          disconnect_from_peer(peer.get(), reason_string, true, reason_exception);
        }
        for (const peer_connection_ptr& peer : peers_with_newly_empty_item_lists)
          fetch_next_batch_of_item_ids_from_peer(peer.get());
  
        for (const peer_connection_ptr& peer : peers_we_need_to_sync_to)
          start_synchronizing_with_peer(peer);
  
        dlog("Leaving send_sync_block_to_node_delegate");
  
        if (// _suspend_fetching_sync_blocks && <-- you can use this if "maximum_number_of_blocks_to_handle_at_one_time" == "maximum_number_of_sync_blocks_to_prefetch"
            !_node_is_shutting_down &&
            (!_process_backlog_of_sync_blocks_done.valid() || _process_backlog_of_sync_blocks_done.ready()))
          _process_backlog_of_sync_blocks_done = fc::async([=](){ process_backlog_of_sync_blocks(); },
                                                           "process_backlog_of_sync_blocks");
      }
  
      void node_impl::process_backlog_of_sync_blocks()
      {
        VERIFY_CORRECT_THREAD();
        // garbage-collect the list of async tasks here for lack of a better place
        for (auto calls_iter = _handle_message_calls_in_progress.begin();
              calls_iter != _handle_message_calls_in_progress.end();)
        {
          if (calls_iter->ready())
            calls_iter = _handle_message_calls_in_progress.erase(calls_iter);
          else
            ++calls_iter;
        }
  
        dlog("in process_backlog_of_sync_blocks");
        if (_handle_message_calls_in_progress.size() >= _maximum_number_of_blocks_to_handle_at_one_time)
        {
          dlog("leaving process_backlog_of_sync_blocks because we're already processing too many blocks");
          return; // we will be rescheduled when the next block finishes its processing
        }
        dlog("currently ${count} blocks in the process of being handled", ("count", _handle_message_calls_in_progress.size()));
  
  
        if (_suspend_fetching_sync_blocks)
        {
          dlog("resuming processing sync block backlog because we only ${count} blocks in progress",
               ("count", _handle_message_calls_in_progress.size()));
          _suspend_fetching_sync_blocks = false;
        }
  
  
        // when syncing with multiple peers, it's possible that we'll have hundreds of blocks ready to push
        // to the client at once.  This can be slow, and we need to limit the number we push at any given
        // time to allow network traffic to continue so we don't end up disconnecting from peers
        //fc::time_point start_time = fc::time_point::now();
        //fc::time_point when_we_should_yield = start_time + fc::seconds(1);
  
        bool block_processed_this_iteration;
        unsigned blocks_processed = 0;
  
        std::set<peer_connection_ptr> peers_with_newly_empty_item_lists;
        std::set<peer_connection_ptr> peers_we_need_to_sync_to;
        std::map<peer_connection_ptr, fc::oexception> peers_with_rejected_block;
  
        do
        {
          std::copy(std::make_move_iterator(_new_received_sync_items.begin()),
                    std::make_move_iterator(_new_received_sync_items.end()),
                    std::front_inserter(_received_sync_items));
          _new_received_sync_items.clear();
          dlog("currently ${count} sync items to consider", ("count", _received_sync_items.size()));
  
          block_processed_this_iteration = false;
          for (auto received_block_iter = _received_sync_items.begin();
               received_block_iter != _received_sync_items.end();
               ++received_block_iter)
          {
  
            // find out if this block is the next block on the active chain or one of the forks
            bool potential_first_block = false;
            for (const peer_connection_ptr& peer : _active_connections)
            {
              ASSERT_TASK_NOT_PREEMPTED(); // don't yield while iterating over _active_connections
              if (!peer->ids_of_items_to_get.empty() &&
                  peer->ids_of_items_to_get.front() == received_block_iter->block_id)
              {
                potential_first_block = true;
                peer->ids_of_items_to_get.pop_front();
                peer->ids_of_items_being_processed.insert(received_block_iter->block_id);
              }
            }
  
            // if it is, process it, remove it from all sync peers lists
            if (potential_first_block)
            {
              // we can get into an interesting situation near the end of synchronization.  We can be in
              // sync with one peer who is sending us the last block on the chain via a regular inventory
              // message, while at the same time still be synchronizing with a peer who is sending us the
              // block through the sync mechanism.  Further, we must request both blocks because
              // we don't know they're the same (for the peer in normal operation, it has only told us the
              // message id, for the peer in the sync case we only known the block_id).
              if (std::find(_most_recent_blocks_accepted.begin(), _most_recent_blocks_accepted.end(),
                            received_block_iter->block_id) == _most_recent_blocks_accepted.end())
              {
                graphene::net::block_message block_message_to_process = *received_block_iter;
                _received_sync_items.erase(received_block_iter);
                _handle_message_calls_in_progress.emplace_back(fc::async([this, block_message_to_process](){
                  send_sync_block_to_node_delegate(block_message_to_process);
                }, "send_sync_block_to_node_delegate"));
                ++blocks_processed;
                block_processed_this_iteration = true;
              }
              else
                dlog("Already received and accepted this block (presumably through normal inventory mechanism), treating it as accepted");
  
              break; // start iterating _received_sync_items from the beginning
            } // end if potential_first_block
          } // end for each block in _received_sync_items
  
          if (_handle_message_calls_in_progress.size() >= _maximum_number_of_blocks_to_handle_at_one_time)
          {
            dlog("stopping processing sync block backlog because we have ${count} blocks in progress",
                 ("count", _handle_message_calls_in_progress.size()));
            //ulog("stopping processing sync block backlog because we have ${count} blocks in progress, total on hand: ${received}",
            //     ("count", _handle_message_calls_in_progress.size())("received", _received_sync_items.size()));
            if (_received_sync_items.size() >= _maximum_number_of_sync_blocks_to_prefetch)
              _suspend_fetching_sync_blocks = true;
            break;
          }
        } while (block_processed_this_iteration);
  
        dlog("leaving process_backlog_of_sync_blocks, ${count} processed", ("count", blocks_processed));
  
        if (!_suspend_fetching_sync_blocks)
          trigger_fetch_sync_items_loop();
      }
  
      void node_impl::trigger_process_backlog_of_sync_blocks()
      {
        if (!_node_is_shutting_down &&
            (!_process_backlog_of_sync_blocks_done.valid() || _process_backlog_of_sync_blocks_done.ready()))
          _process_backlog_of_sync_blocks_done = fc::async([=](){ process_backlog_of_sync_blocks(); }, "process_backlog_of_sync_blocks");
      }
  
      void node_impl::process_block_during_sync( peer_connection* originating_peer,
                                                 const graphene::net::block_message& block_message_to_process, const message_hash_type& message_hash )
      {
        VERIFY_CORRECT_THREAD();
        dlog( "received a sync block from peer ${endpoint}", ("endpoint", originating_peer->get_remote_endpoint() ) );
  
        // add it to the front of _received_sync_items, then process _received_sync_items to try to
        // pass as many messages as possible to the client.
        _new_received_sync_items.push_front( block_message_to_process );
        trigger_process_backlog_of_sync_blocks();
      }
  
      void node_impl::process_block_during_normal_operation( peer_connection* originating_peer,
                                                             const graphene::net::block_message& block_message_to_process,
                                                             const message_hash_type& message_hash )
      {
        fc::time_point message_receive_time = fc::time_point::now();
  
        dlog( "received a block from peer ${endpoint}, passing it to client", ("endpoint", originating_peer->get_remote_endpoint() ) );
        std::set<peer_connection_ptr> peers_to_disconnect;
        std::string disconnect_reason;
        fc::oexception disconnect_exception;
        fc::oexception restart_sync_exception;
        try
        {
          // we can get into an intersting situation near the end of synchronization.  We can be in
          // sync with one peer who is sending us the last block on the chain via a regular inventory
          // message, while at the same time still be synchronizing with a peer who is sending us the
          // block through the sync mechanism.  Further, we must request both blocks because
          // we don't know they're the same (for the peer in normal operation, it has only told us the
          // message id, for the peer in the sync case we only known the block_id).
          fc::time_point message_validated_time;
          if (std::find(_most_recent_blocks_accepted.begin(), _most_recent_blocks_accepted.end(),
                        block_message_to_process.block_id) == _most_recent_blocks_accepted.end())
          {
            std::vector<fc::uint160_t> contained_transaction_message_ids;
            _delegate->handle_block(block_message_to_process, false, contained_transaction_message_ids,true);
            message_validated_time = fc::time_point::now();
            ilog("Successfully pushed block ${num} (id:${id})",
                  ("num", block_message_to_process.block.block_num())
                  ("id", block_message_to_process.block_id));
            _most_recent_blocks_accepted.push_back(block_message_to_process.block_id);
  
            bool new_transaction_discovered = false;
            for (const item_hash_t& transaction_message_hash : contained_transaction_message_ids)
            {
              size_t items_erased = _items_to_fetch.get<item_id_index>().erase(item_id(trx_message_type, transaction_message_hash));
              // there are two ways we could behave here: we could either act as if we received
              // the transaction outside the block and offer it to our peers, or we could just
              // forget about it (we would still advertise this block to our peers so they should
              // get the transaction through that mechanism).
              // We take the second approach, bring in the next if block to try the first approach
              //if (items_erased)
              //{
              //  new_transaction_discovered = true;
              //  _new_inventory.insert(item_id(trx_message_type, transaction_message_hash));
              //}
            }
            if (new_transaction_discovered)
              trigger_advertise_inventory_loop();
          }
          else
            dlog( "Already received and accepted this block (presumably through sync mechanism), treating it as accepted" );
  
          dlog( "client validated the block, advertising it to other peers" );
  
          item_id block_message_item_id(core_message_type_enum::block_message_type, message_hash);
          uint32_t block_number = block_message_to_process.block.block_num();
          fc::time_point_sec block_time = block_message_to_process.block.timestamp;
  
          for (const peer_connection_ptr& peer : _active_connections)
          {
            ASSERT_TASK_NOT_PREEMPTED(); // don't yield while iterating over _active_connections
  
            auto iter = peer->inventory_peer_advertised_to_us.find(block_message_item_id);
            if (iter != peer->inventory_peer_advertised_to_us.end())
            {
              // this peer offered us the item.  It will eventually expire from the peer's
              // inventory_peer_advertised_to_us list after some time has passed (currently 2 minutes).
              // For now, it will remain there, which will prevent us from offering the peer this
              // block back when we rebroadcast the block below
              peer->last_block_delegate_has_seen = block_message_to_process.block_id;
              peer->last_block_time_delegate_has_seen = block_time;
            }
            peer->clear_old_inventory();
          }
          message_propagation_data propagation_data{message_receive_time, message_validated_time, originating_peer->node_id};
          broadcast( block_message_to_process, propagation_data );
          _message_cache.block_accepted();
  
          if (is_hard_fork_block(block_number))
          {
            // we just pushed a hard fork block.  Find out if any of our peers are running clients
            // that will be unable to process future blocks
            for (const peer_connection_ptr& peer : _active_connections)
            {
              if (peer->last_known_fork_block_number != 0)
              {
                uint32_t next_fork_block_number = get_next_known_hard_fork_block_number(peer->last_known_fork_block_number);
                if (next_fork_block_number != 0 &&
                    next_fork_block_number <= block_number)
                {
                  peers_to_disconnect.insert(peer);
  #ifdef ENABLE_DEBUG_ULOGS
                  ulog("Disconnecting from peer because their version is too old.  Their version date: ${date}", ("date", peer->graphene_git_revision_unix_timestamp));
  #endif
                }
              }
            }
            if (!peers_to_disconnect.empty())
            {
              std::ostringstream disconnect_reason_stream;
              disconnect_reason_stream << "You need to upgrade your client due to hard fork at block " << block_number;
              disconnect_reason = disconnect_reason_stream.str();
              disconnect_exception = fc::exception(FC_LOG_MESSAGE(error, "You need to upgrade your client due to hard fork at block ${block_number}",
                                                                  ("block_number", block_number)));
            }
          }
        }
        catch (const fc::canceled_exception&)
        {
          throw;
        }
  	  catch (const block_process_stopped&)
  	  {
  		  return;
  	  }
        catch (const unlinkable_block_exception& e) 
        {
          restart_sync_exception = e;
        }
        catch (const fc::exception& e)
        {
          // client rejected the block.  Disconnect the client and any other clients that offered us this block
          wlog("Failed to push block ${num} (id:${id}), client rejected block sent by peer",
                ("num", block_message_to_process.block.block_num())
                ("id", block_message_to_process.block_id));
  
          disconnect_exception = e;
          disconnect_reason = "You offered me a block that I have deemed to be invalid";
  
          peers_to_disconnect.insert( originating_peer->shared_from_this() );
          for (const peer_connection_ptr& peer : _active_connections)
            if (!peer->ids_of_items_to_get.empty() && peer->ids_of_items_to_get.front() == block_message_to_process.block_id)
              peers_to_disconnect.insert(peer);
        }
  
        if (restart_sync_exception)
        {
          wlog("Peer ${peer} sent me a block that didn't link to our blockchain.  Restarting sync mode with them to get the missing block. "
               "Error pushing block was: ${e}",
               ("peer", originating_peer->get_remote_endpoint())
               ("e", *restart_sync_exception));
          start_synchronizing_with_peer(originating_peer->shared_from_this());
        }
  
        for (const peer_connection_ptr& peer : peers_to_disconnect)
        {
          wlog("disconnecting client ${endpoint} because it offered us the rejected block", ("endpoint", peer->get_remote_endpoint()));
          disconnect_from_peer(peer.get(), disconnect_reason, true, *disconnect_exception);
        }
      }
      void node_impl::process_block_message(peer_connection* originating_peer,
                                            const message& message_to_process,
                                            const message_hash_type& message_hash)
      {
        VERIFY_CORRECT_THREAD();
        // find out whether we requested this item while we were synchronizing or during normal operation
        // (it's possible that we request an item during normal operation and then get kicked into sync
        // mode before we receive and process the item.  In that case, we should process the item as a normal
        // item to avoid confusing the sync code)
        graphene::net::block_message block_message_to_process(message_to_process.as<graphene::net::block_message>());
        auto item_iter = originating_peer->items_requested_from_peer.find(item_id(graphene::net::block_message_type, message_hash));
        if (item_iter != originating_peer->items_requested_from_peer.end())
        {
          originating_peer->items_requested_from_peer.erase(item_iter);
          process_block_during_normal_operation(originating_peer, block_message_to_process, message_hash);
          if (originating_peer->idle())
            trigger_fetch_items_loop();
          return;
        }
        else
        {
          // not during normal operation.  see if we requested it during sync
          auto sync_item_iter = originating_peer->sync_items_requested_from_peer.find(item_id(graphene::net::block_message_type,
                                                                                              block_message_to_process.block_id));
          if (sync_item_iter != originating_peer->sync_items_requested_from_peer.end())
          {
            originating_peer->sync_items_requested_from_peer.erase(sync_item_iter);
            _active_sync_requests.erase(block_message_to_process.block_id);
            process_block_during_sync(originating_peer, block_message_to_process, message_hash);
            if (originating_peer->idle())
            {
              // we have finished fetching a batch of items, so we either need to grab another batch of items
              // or we need to get another list of item ids.
              if (originating_peer->number_of_unfetched_item_ids > 0 &&
                  originating_peer->ids_of_items_to_get.size() < GRAPHENE_NET_MIN_BLOCK_IDS_TO_PREFETCH)
                fetch_next_batch_of_item_ids_from_peer(originating_peer);
              else
                trigger_fetch_sync_items_loop();
            }
            return;
          }
        }
  
        // if we get here, we didn't request the message, we must have a misbehaving peer
        wlog("received a block ${block_id} I didn't ask for from peer ${endpoint}, disconnecting from peer",
             ("endpoint", originating_peer->get_remote_endpoint())
             ("block_id", block_message_to_process.block_id));
        fc::exception detailed_error(FC_LOG_MESSAGE(error, "You sent me a block that I didn't ask for, block_id: ${block_id}",
                                                    ("block_id", block_message_to_process.block_id)
                                                    ("graphene_git_revision_sha", originating_peer->graphene_git_revision_sha)
                                                    ("graphene_git_revision_unix_timestamp", originating_peer->graphene_git_revision_unix_timestamp)
                                                    ("fc_git_revision_sha", originating_peer->fc_git_revision_sha)
                                                    ("fc_git_revision_unix_timestamp", originating_peer->fc_git_revision_unix_timestamp)));
        disconnect_from_peer(originating_peer, "You sent me a block that I didn't ask for", true, detailed_error);
      }
  
      void node_impl::on_current_time_request_message(peer_connection* originating_peer,
                                                      const current_time_request_message& current_time_request_message_received)
      {
        VERIFY_CORRECT_THREAD();
        fc::time_point request_received_time(fc::time_point::now());
        current_time_reply_message reply(current_time_request_message_received.request_sent_time,
                                         request_received_time);
        originating_peer->send_message(reply, offsetof(current_time_reply_message, reply_transmitted_time));
      }
  
      void node_impl::on_current_time_reply_message(peer_connection* originating_peer,
                                                    const current_time_reply_message& current_time_reply_message_received)
      {
        VERIFY_CORRECT_THREAD();
        fc::time_point reply_received_time = fc::time_point::now();
        originating_peer->clock_offset = fc::microseconds(((current_time_reply_message_received.request_received_time - current_time_reply_message_received.request_sent_time) +
                                                           (current_time_reply_message_received.reply_transmitted_time - reply_received_time)).count() / 2);
        originating_peer->round_trip_delay = (reply_received_time - current_time_reply_message_received.request_sent_time) -
                                             (current_time_reply_message_received.reply_transmitted_time - current_time_reply_message_received.request_received_time);
      }
  
      void node_impl::forward_firewall_check_to_next_available_peer(firewall_check_state_data* firewall_check_state)
      {
        for (const peer_connection_ptr& peer : _active_connections)
        {
          if (firewall_check_state->expected_node_id != peer->node_id && // it's not the node who is asking us to test
              !peer->firewall_check_state && // the peer isn't already performing a check for another node
              firewall_check_state->nodes_already_tested.find(peer->node_id) == firewall_check_state->nodes_already_tested.end() &&
              peer->core_protocol_version >= 106)
          {
            wlog("forwarding firewall check for node ${to_check} to peer ${checker}",
                 ("to_check", firewall_check_state->endpoint_to_test)
                 ("checker", peer->get_remote_endpoint()));
            firewall_check_state->nodes_already_tested.insert(peer->node_id);
            peer->firewall_check_state = firewall_check_state;
            check_firewall_message check_request;
            check_request.endpoint_to_check = firewall_check_state->endpoint_to_test;
            check_request.node_id = firewall_check_state->expected_node_id;
            peer->send_message(check_request);
            return;
          }
        }
        wlog("Unable to forward firewall check for node ${to_check} to any other peers, returning 'unable'",
             ("to_check", firewall_check_state->endpoint_to_test));
  
        peer_connection_ptr originating_peer = get_peer_by_node_id(firewall_check_state->expected_node_id);
        if (originating_peer)
        {
          check_firewall_reply_message reply;
          reply.node_id = firewall_check_state->expected_node_id;
          reply.endpoint_checked = firewall_check_state->endpoint_to_test;
          reply.result = firewall_check_result::unable_to_check;
          originating_peer->send_message(reply);
        }
        delete firewall_check_state;
      }
  
      void node_impl::on_check_firewall_message(peer_connection* originating_peer,
                                                const check_firewall_message& check_firewall_message_received)
      {
        VERIFY_CORRECT_THREAD();
  
        if (check_firewall_message_received.node_id == node_id_t() &&
            check_firewall_message_received.endpoint_to_check == fc::ip::endpoint())
        {
          // originating_peer is asking us to test whether it is firewalled
          // we're not going to try to connect back to the originating peer directly,
          // instead, we're going to coordinate requests by asking some of our peers
          // to try to connect to the originating peer, and relay the results back
          wlog("Peer ${peer} wants us to check whether it is firewalled", ("peer", originating_peer->get_remote_endpoint()));
          firewall_check_state_data* firewall_check_state = new firewall_check_state_data;
          // if they are using the same inbound and outbound port, try connecting to their outbound endpoint.
          // if they are using a different inbound port, use their outbound address but the inbound port they reported
          fc::ip::endpoint endpoint_to_check = originating_peer->get_socket().remote_endpoint();
          if (originating_peer->inbound_port != originating_peer->outbound_port)
            endpoint_to_check = fc::ip::endpoint(endpoint_to_check.get_address(), originating_peer->inbound_port);
          firewall_check_state->endpoint_to_test = endpoint_to_check;
          firewall_check_state->expected_node_id = originating_peer->node_id;
          firewall_check_state->requesting_peer = originating_peer->node_id;
  
          forward_firewall_check_to_next_available_peer(firewall_check_state);
        }
        else
        {
          // we're being asked to check another node
          // first, find out if we're currently connected to that node.  If we are, we
          // can't perform the test
          if (is_already_connected_to_id(check_firewall_message_received.node_id) ||
              is_connection_to_endpoint_in_progress(check_firewall_message_received.endpoint_to_check))
          {
            check_firewall_reply_message reply;
            reply.node_id = check_firewall_message_received.node_id;
            reply.endpoint_checked = check_firewall_message_received.endpoint_to_check;
            reply.result = firewall_check_result::unable_to_check;
          }
          else
          {
            // we're not connected to them, so we need to set up a connection to them
            // to test.
            peer_connection_ptr peer_for_testing(peer_connection::make_shared(this));
            peer_for_testing->firewall_check_state = new firewall_check_state_data;
            peer_for_testing->firewall_check_state->endpoint_to_test = check_firewall_message_received.endpoint_to_check;
            peer_for_testing->firewall_check_state->expected_node_id = check_firewall_message_received.node_id;
            peer_for_testing->firewall_check_state->requesting_peer = originating_peer->node_id;
            peer_for_testing->set_remote_endpoint(check_firewall_message_received.endpoint_to_check);
            initiate_connect_to(peer_for_testing);
          }
        }
      }
  
      void node_impl::on_check_firewall_reply_message(peer_connection* originating_peer,
                                                      const check_firewall_reply_message& check_firewall_reply_message_received)
      {
        VERIFY_CORRECT_THREAD();
  
        if (originating_peer->firewall_check_state &&
            originating_peer->firewall_check_state->requesting_peer != node_id_t())
        {
          // then this is a peer that is helping us check the firewalled state of one of our other peers
          // and they're reporting back
          // if they got a result, return it to the original peer.  if they were unable to check,
          // we'll try another peer.
          wlog("Peer ${reporter} reports firewall check status ${status} for ${peer}",
               ("reporter", originating_peer->get_remote_endpoint())
               ("status", check_firewall_reply_message_received.result)
               ("peer", check_firewall_reply_message_received.endpoint_checked));
  
          if (check_firewall_reply_message_received.result == firewall_check_result::unable_to_connect ||
              check_firewall_reply_message_received.result == firewall_check_result::connection_successful)
          {
            peer_connection_ptr original_peer = get_peer_by_node_id(originating_peer->firewall_check_state->requesting_peer);
            if (original_peer)
            {
              if (check_firewall_reply_message_received.result == firewall_check_result::connection_successful)
              {
                // if we previously thought this peer was firewalled, mark them as not firewalled
                if (original_peer->is_firewalled != firewalled_state::not_firewalled)
                {
  
                  original_peer->is_firewalled = firewalled_state::not_firewalled;
                  // there should be no old entry if we thought they were firewalled, so just create a new one
                  fc::optional<fc::ip::endpoint> inbound_endpoint = originating_peer->get_endpoint_for_connecting();
                  if (inbound_endpoint)
                  {
                    potential_peer_record updated_peer_record = _potential_peer_db.lookup_or_create_entry_for_endpoint(*inbound_endpoint);
                    updated_peer_record.last_seen_time = fc::time_point::now();
                    _potential_peer_db.update_entry(updated_peer_record);
                  }
                }
              }
              original_peer->send_message(check_firewall_reply_message_received);
            }
            delete originating_peer->firewall_check_state;
            originating_peer->firewall_check_state = nullptr;
          }
          else
          {
            // they were unable to check for us, ask another peer
            firewall_check_state_data* firewall_check_state = originating_peer->firewall_check_state;
            originating_peer->firewall_check_state = nullptr;
            forward_firewall_check_to_next_available_peer(firewall_check_state);
          }
        }
        else if (originating_peer->firewall_check_state)
        {
          // this is a reply to a firewall check we initiated.
          wlog("Firewall check we initiated has returned with result: ${result}, endpoint = ${endpoint}",
               ("result", check_firewall_reply_message_received.result)
               ("endpoint", check_firewall_reply_message_received.endpoint_checked));
          if (check_firewall_reply_message_received.result == firewall_check_result::connection_successful)
          {
            _is_firewalled = firewalled_state::not_firewalled;
            _publicly_visible_listening_endpoint = check_firewall_reply_message_received.endpoint_checked;
          }
          else if (check_firewall_reply_message_received.result == firewall_check_result::unable_to_connect)
          {
            _is_firewalled = firewalled_state::firewalled;
            _publicly_visible_listening_endpoint = fc::optional<fc::ip::endpoint>();
          }
          delete originating_peer->firewall_check_state;
          originating_peer->firewall_check_state = nullptr;
        }
        else
        {
          wlog("Received a firewall check reply to a request I never sent");
        }
  
      }
  
      void node_impl::on_get_current_connections_request_message(peer_connection* originating_peer,
                                                                 const get_current_connections_request_message& get_current_connections_request_message_received)
      {
        VERIFY_CORRECT_THREAD();
        get_current_connections_reply_message reply;
  
        if (!_average_network_read_speed_minutes.empty())
        {
          reply.upload_rate_one_minute = _average_network_write_speed_minutes.back();
          reply.download_rate_one_minute = _average_network_read_speed_minutes.back();
  
          size_t minutes_to_average = std::min(_average_network_write_speed_minutes.size(), (size_t)15);
          boost::circular_buffer<uint32_t>::iterator start_iter = _average_network_write_speed_minutes.end() - minutes_to_average;
          reply.upload_rate_fifteen_minutes = std::accumulate(start_iter, _average_network_write_speed_minutes.end(), 0) / (uint32_t)minutes_to_average;
          start_iter = _average_network_read_speed_minutes.end() - minutes_to_average;
          reply.download_rate_fifteen_minutes = std::accumulate(start_iter, _average_network_read_speed_minutes.end(), 0) / (uint32_t)minutes_to_average;
  
          minutes_to_average = std::min(_average_network_write_speed_minutes.size(), (size_t)60);
          start_iter = _average_network_write_speed_minutes.end() - minutes_to_average;
          reply.upload_rate_one_hour = std::accumulate(start_iter, _average_network_write_speed_minutes.end(), 0) / (uint32_t)minutes_to_average;
          start_iter = _average_network_read_speed_minutes.end() - minutes_to_average;
          reply.download_rate_one_hour = std::accumulate(start_iter, _average_network_read_speed_minutes.end(), 0) / (uint32_t)minutes_to_average;
        }
  
        fc::time_point now = fc::time_point::now();
        for (const peer_connection_ptr& peer : _active_connections)
        {
          ASSERT_TASK_NOT_PREEMPTED(); // don't yield while iterating over _active_connections
  
          current_connection_data data_for_this_peer;
          data_for_this_peer.connection_duration = now.sec_since_epoch() - peer->connection_initiation_time.sec_since_epoch();
          if (peer->get_remote_endpoint()) // should always be set for anyone we're actively connected to
            data_for_this_peer.remote_endpoint = *peer->get_remote_endpoint();
          data_for_this_peer.clock_offset = peer->clock_offset;
          data_for_this_peer.round_trip_delay = peer->round_trip_delay;
          data_for_this_peer.node_id = peer->node_id;
          data_for_this_peer.connection_direction = peer->direction;
          data_for_this_peer.firewalled = peer->is_firewalled;
          fc::mutable_variant_object user_data;
          if (peer->graphene_git_revision_sha)
            user_data["graphene_git_revision_sha"] = *peer->graphene_git_revision_sha;
          if (peer->graphene_git_revision_unix_timestamp)
            user_data["graphene_git_revision_unix_timestamp"] = *peer->graphene_git_revision_unix_timestamp;
          if (peer->fc_git_revision_sha)
            user_data["fc_git_revision_sha"] = *peer->fc_git_revision_sha;
          if (peer->fc_git_revision_unix_timestamp)
            user_data["fc_git_revision_unix_timestamp"] = *peer->fc_git_revision_unix_timestamp;
          if (peer->platform)
            user_data["platform"] = *peer->platform;
          if (peer->bitness)
            user_data["bitness"] = *peer->bitness;
          user_data["user_agent"] = peer->user_agent;
  
          user_data["last_known_block_hash"] = peer->last_block_delegate_has_seen;
          user_data["last_known_block_number"] = _delegate->get_block_number(peer->last_block_delegate_has_seen);
          user_data["last_known_block_time"] = peer->last_block_time_delegate_has_seen;
  
          data_for_this_peer.user_data = user_data;
          reply.current_connections.emplace_back(data_for_this_peer);
        }
        originating_peer->send_message(reply);
      }
  
      void node_impl::on_get_current_connections_reply_message(peer_connection* originating_peer,
                                                               const get_current_connections_reply_message& get_current_connections_reply_message_received)
      {
        VERIFY_CORRECT_THREAD();
      }
  
  
      // this handles any message we get that doesn't require any special processing.
      // currently, this is any message other than block messages and p2p-specific
      // messages.  (transaction messages would be handled here, for example)
      // this just passes the message to the client, and does the bookkeeping
      // related to requesting and rebroadcasting the message.
      void node_impl::process_ordinary_message( peer_connection* originating_peer,
                                                const message& message_to_process, const message_hash_type& message_hash )
      {
        VERIFY_CORRECT_THREAD();
        fc::time_point message_receive_time = fc::time_point::now();
  
        // only process it if we asked for it
        auto iter = originating_peer->items_requested_from_peer.find( item_id(message_to_process.msg_type, message_hash) );
        if( iter == originating_peer->items_requested_from_peer.end() )
        {
          wlog( "received a message I didn't ask for from peer ${endpoint}, disconnecting from peer",
               ( "endpoint", originating_peer->get_remote_endpoint() ) );
          fc::exception detailed_error( FC_LOG_MESSAGE(error, "You sent me a message that I didn't ask for, message_hash: ${message_hash}",
                                                      ( "message_hash", message_hash ) ) );
          disconnect_from_peer( originating_peer, "You sent me a message that I didn't request", true, detailed_error );
          return;
        }
        else
        {
          originating_peer->items_requested_from_peer.erase( iter );
          if (originating_peer->idle())
            trigger_fetch_items_loop();
  
          // Next: have the delegate process the message
          fc::time_point message_validated_time;
          try
          {
            if (message_to_process.msg_type == trx_message_type)
            {
              trx_message transaction_message_to_process = message_to_process.as<trx_message>();
              dlog("passing message containing transaction ${trx} to client", ("trx", transaction_message_to_process.trx.id()));
              _delegate->handle_transaction(transaction_message_to_process);
            }
            else
              _delegate->handle_message( message_to_process );
            message_validated_time = fc::time_point::now();
          }
          catch ( const fc::canceled_exception& )
          {
            throw;
          }
          catch ( const fc::exception& e )
          {
            wlog( "client rejected message sent by peer ${peer}, ${e}", ("peer", originating_peer->get_remote_endpoint() )("e", e) );
            // record it so we don't try to fetch this item again
            _recently_failed_items.insert(peer_connection::timestamped_item_id(item_id(message_to_process.msg_type, message_hash ), fc::time_point::now()));
            return;
          }
  
          // finally, if the delegate validated the message, broadcast it to our other peers
          message_propagation_data propagation_data{message_receive_time, message_validated_time, originating_peer->node_id};
          broadcast( message_to_process, propagation_data );
        }
      }
  
      void node_impl::start_synchronizing_with_peer( const peer_connection_ptr& peer )
      {
        VERIFY_CORRECT_THREAD();
        peer->ids_of_items_to_get.clear();
        peer->number_of_unfetched_item_ids = 0;
        peer->we_need_sync_items_from_peer = true;
        peer->last_block_delegate_has_seen = item_hash_t();
        peer->last_block_time_delegate_has_seen = _delegate->get_block_time(item_hash_t());
        peer->inhibit_fetching_sync_blocks = false;
        fetch_next_batch_of_item_ids_from_peer( peer.get() );
      }
  
      void node_impl::start_synchronizing()
      {
        for( const peer_connection_ptr& peer : _active_connections )
          start_synchronizing_with_peer( peer );
      }
  
      void node_impl::new_peer_just_added( const peer_connection_ptr& peer )
      {
        VERIFY_CORRECT_THREAD();
        peer->send_message(current_time_request_message(),
                           offsetof(current_time_request_message, request_sent_time));
        start_synchronizing_with_peer( peer );
        if( _active_connections.size() != _last_reported_number_of_connections )
        {
          _last_reported_number_of_connections = (uint32_t)_active_connections.size();
          _delegate->connection_count_changed( _last_reported_number_of_connections );
        }
      }
  
      void node_impl::close()
      {
        VERIFY_CORRECT_THREAD();
  
        try
        {
          _potential_peer_db.close();
        }
        catch ( const fc::exception& e )
        {
          wlog( "Exception thrown while closing P2P peer database, ignoring: ${e}", ("e", e) );
        }
        catch (...)
        {
          wlog( "Exception thrown while closing P2P peer database, ignoring" );
        }
  
        // First, stop accepting incoming network connections
        try
        {
          _tcp_server.close();
          dlog("P2P TCP server closed");
        }
        catch ( const fc::exception& e )
        {
          wlog( "Exception thrown while closing P2P TCP server, ignoring: ${e}", ("e", e) );
        }
        catch (...)
        {
          wlog( "Exception thrown while closing P2P TCP server, ignoring" );
        }
  
        try
        {
          _accept_loop_complete.cancel_and_wait("node_impl::close()");
          dlog("P2P accept loop terminated");
        }
        catch ( const fc::exception& e )
        {
          wlog( "Exception thrown while terminating P2P accept loop, ignoring: ${e}", ("e", e) );
        }
        catch (...)
        {
          wlog( "Exception thrown while terminating P2P accept loop, ignoring" );
        }
  
        // terminate all of our long-running loops (these run continuously instead of rescheduling themselves)
        try
        {
          _p2p_network_connect_loop_done.cancel("node_impl::close()");
          // cancel() is currently broken, so we need to wake up the task to allow it to finish
          trigger_p2p_network_connect_loop();
          _p2p_network_connect_loop_done.wait();
          dlog("P2P connect loop terminated");
        }
        catch ( const fc::canceled_exception& )
        {
          dlog("P2P connect loop terminated");
        }
        catch ( const fc::exception& e )
        {
          wlog( "Exception thrown while terminating P2P connect loop, ignoring: ${e}", ("e", e) );
        }
        catch (...)
        {
          wlog( "Exception thrown while terminating P2P connect loop, ignoring" );
        }
  
        try
        {
          _process_backlog_of_sync_blocks_done.cancel_and_wait("node_impl::close()");
          dlog("Process backlog of sync items task terminated");
        }
        catch ( const fc::canceled_exception& )
        {
          dlog("Process backlog of sync items task terminated");
        }
        catch ( const fc::exception& e )
        {
          wlog( "Exception thrown while terminating Process backlog of sync items task, ignoring: ${e}", ("e", e) );
        }
        catch (...)
        {
          wlog( "Exception thrown while terminating Process backlog of sync items task, ignoring" );
        }
  
        unsigned handle_message_call_count = 0;
        while( true )
        {
          auto it = _handle_message_calls_in_progress.begin();
          if( it == _handle_message_calls_in_progress.end() )
             break;
          if( it->ready() || it->error() || it->canceled() )
          {
             _handle_message_calls_in_progress.erase( it );
             continue;
          }
          ++handle_message_call_count;
          try
          {
            it->cancel_and_wait("node_impl::close()");
            dlog("handle_message call #${count} task terminated", ("count", handle_message_call_count));
          }
          catch ( const fc::canceled_exception& )
          {
            dlog("handle_message call #${count} task terminated", ("count", handle_message_call_count));
          }
          catch ( const fc::exception& e )
          {
            wlog("Exception thrown while terminating handle_message call #${count} task, ignoring: ${e}", ("e", e)("count", handle_message_call_count));
          }
          catch (...)
          {
            wlog("Exception thrown while terminating handle_message call #${count} task, ignoring",("count", handle_message_call_count));
          }
        }
  
        try
        {
          _fetch_sync_items_loop_done.cancel("node_impl::close()");
          // cancel() is currently broken, so we need to wake up the task to allow it to finish
          trigger_fetch_sync_items_loop();
          _fetch_sync_items_loop_done.wait();
          dlog("Fetch sync items loop terminated");
        }
        catch ( const fc::canceled_exception& )
        {
          dlog("Fetch sync items loop terminated");
        }
        catch ( const fc::exception& e )
        {
          wlog( "Exception thrown while terminating Fetch sync items loop, ignoring: ${e}", ("e", e) );
        }
        catch (...)
        {
          wlog( "Exception thrown while terminating Fetch sync items loop, ignoring" );
        }
  
        try
        {
          _fetch_item_loop_done.cancel("node_impl::close()");
          // cancel() is currently broken, so we need to wake up the task to allow it to finish
          trigger_fetch_items_loop();
          _fetch_item_loop_done.wait();
          dlog("Fetch items loop terminated");
        }
        catch ( const fc::canceled_exception& )
        {
          dlog("Fetch items loop terminated");
        }
        catch ( const fc::exception& e )
        {
          wlog( "Exception thrown while terminating Fetch items loop, ignoring: ${e}", ("e", e) );
        }
        catch (...)
        {
          wlog( "Exception thrown while terminating Fetch items loop, ignoring" );
        }
  
        try
        {
          _advertise_inventory_loop_done.cancel("node_impl::close()");
          // cancel() is currently broken, so we need to wake up the task to allow it to finish
          trigger_advertise_inventory_loop();
          _advertise_inventory_loop_done.wait();
          dlog("Advertise inventory loop terminated");
        }
        catch ( const fc::canceled_exception& )
        {
          dlog("Advertise inventory loop terminated");
        }
        catch ( const fc::exception& e )
        {
          wlog( "Exception thrown while terminating Advertise inventory loop, ignoring: ${e}", ("e", e) );
        }
        catch (...)
        {
          wlog( "Exception thrown while terminating Advertise inventory loop, ignoring" );
        }
  
  
        // Next, terminate our existing connections.  First, close all of the connections nicely.
        // This will close the sockets and may result in calls to our "on_connection_closing"
        // method to inform us that the connection really closed (or may not if we manage to cancel
        // the read loop before it gets an EOF).
        // operate off copies of the lists in case they change during iteration
        std::list<peer_connection_ptr> all_peers;
        boost::push_back(all_peers, _active_connections);
        boost::push_back(all_peers, _handshaking_connections);
        boost::push_back(all_peers, _closing_connections);
  
        for (const peer_connection_ptr& peer : all_peers)
        {
          try
          {
            peer->destroy_connection();
          }
          catch ( const fc::exception& e )
          {
            wlog( "Exception thrown while closing peer connection, ignoring: ${e}", ("e", e) );
          }
          catch (...)
          {
            wlog( "Exception thrown while closing peer connection, ignoring" );
          }
        }
  
        // and delete all of the peer_connection objects
        _active_connections.clear();
        _handshaking_connections.clear();
        _closing_connections.clear();
        all_peers.clear();
  
        {
  #ifdef USE_PEERS_TO_DELETE_MUTEX
          fc::scoped_lock<fc::mutex> lock(_peers_to_delete_mutex);
  #endif
          try
          {
            _delayed_peer_deletion_task_done.cancel_and_wait("node_impl::close()");
            dlog("Delayed peer deletion task terminated");
          }
          catch ( const fc::exception& e )
          {
            wlog( "Exception thrown while terminating Delayed peer deletion task, ignoring: ${e}", ("e", e) );
          }
          catch (...)
          {
            wlog( "Exception thrown while terminating Delayed peer deletion task, ignoring" );
          }
          _peers_to_delete.clear();
        }
  
        // Now that there are no more peers that can call methods on us, there should be no
        // chance for one of our loops to be rescheduled, so we can safely terminate all of
        // our loops now
        try
        {
          _terminate_inactive_connections_loop_done.cancel_and_wait("node_impl::close()");
          dlog("Terminate inactive connections loop terminated");
        }
        catch ( const fc::exception& e )
        {
          wlog( "Exception thrown while terminating Terminate inactive connections loop, ignoring: ${e}", ("e", e) );
        }
        catch (...)
        {
          wlog( "Exception thrown while terminating Terminate inactive connections loop, ignoring" );
        }
  
        try
        {
          _fetch_updated_peer_lists_loop_done.cancel_and_wait("node_impl::close()");
          dlog("Fetch updated peer lists loop terminated");
        }
        catch ( const fc::exception& e )
        {
          wlog( "Exception thrown while terminating Fetch updated peer lists loop, ignoring: ${e}", ("e", e) );
        }
        catch (...)
        {
          wlog( "Exception thrown while terminating Fetch updated peer lists loop, ignoring" );
        }
  
        try
        {
          _bandwidth_monitor_loop_done.cancel_and_wait("node_impl::close()");
          dlog("Bandwidth monitor loop terminated");
        }
        catch ( const fc::exception& e )
        {
          wlog( "Exception thrown while terminating Bandwidth monitor loop, ignoring: ${e}", ("e", e) );
        }
        catch (...)
        {
          wlog( "Exception thrown while terminating Bandwidth monitor loop, ignoring" );
        }
  
        try
        {
          _dump_node_status_task_done.cancel_and_wait("node_impl::close()");
          dlog("Dump node status task terminated");
        }
        catch ( const fc::exception& e )
        {
          wlog( "Exception thrown while terminating Dump node status task, ignoring: ${e}", ("e", e) );
        }
        catch (...)
        {
          wlog( "Exception thrown while terminating Dump node status task, ignoring" );
        }
      } // node_impl::close()
  
      void node_impl::accept_connection_task( peer_connection_ptr new_peer )
      {
        VERIFY_CORRECT_THREAD();
        new_peer->accept_connection(); // this blocks until the secure connection is fully negotiated
        send_hello_message(new_peer);
      }
  
      void node_impl::accept_loop()
      {
        VERIFY_CORRECT_THREAD();
        while ( !_accept_loop_complete.canceled() )
        {
          peer_connection_ptr new_peer(peer_connection::make_shared(this));
  
          try
          {
            _tcp_server.accept( new_peer->get_socket() );
            ilog( "accepted inbound connection from ${remote_endpoint}", ("remote_endpoint", new_peer->get_socket().remote_endpoint() ) );
            if (_node_is_shutting_down)
              return;
            new_peer->connection_initiation_time = fc::time_point::now();
            _handshaking_connections.insert( new_peer );
            _rate_limiter.add_tcp_socket( &new_peer->get_socket() );
            std::weak_ptr<peer_connection> new_weak_peer(new_peer);
            new_peer->accept_or_connect_task_done = fc::async( [this, new_weak_peer]() {
              peer_connection_ptr new_peer(new_weak_peer.lock());
              assert(new_peer);
              if (!new_peer)
                return;
              accept_connection_task(new_peer);
            }, "accept_connection_task" );
  
            // limit the rate at which we accept connections to mitigate DOS attacks
            fc::usleep( fc::milliseconds(10) );
          } FC_CAPTURE_AND_LOG( (0) )
        }
      } // accept_loop()
  
      void node_impl::send_hello_message(const peer_connection_ptr& peer)
      {
        VERIFY_CORRECT_THREAD();
        peer->negotiation_status = peer_connection::connection_negotiation_status::hello_sent;
  
        fc::sha256::encoder shared_secret_encoder;
        fc::sha512 shared_secret = peer->get_shared_secret();
        shared_secret_encoder.write(shared_secret.data(), sizeof(shared_secret));
        fc::ecc::compact_signature signature = _node_configuration.private_key.sign_compact(shared_secret_encoder.result());
  
        // in the hello messsage, we send three things:
        //  ip address
        //  outbound port
        //  inbound port
        // The peer we're connecting to will assume we're firewalled if the
        // ip address and outbound port we send don't match the values it sees on its remote endpoint
        //
        // if we know that we're behind a NAT that will allow incoming connections because our firewall
        // detection figured it out, send those values instead.
  
        fc::ip::endpoint local_endpoint(peer->get_socket().local_endpoint());
        uint16_t listening_port = _node_configuration.accept_incoming_connections ? _actual_listening_endpoint.port() : 0;
  
        if (_is_firewalled == firewalled_state::not_firewalled &&
            _publicly_visible_listening_endpoint)
        {
          local_endpoint = *_publicly_visible_listening_endpoint;
          listening_port = _publicly_visible_listening_endpoint->port();
        }
  
        hello_message hello(_user_agent_string,
                            core_protocol_version,
                            local_endpoint.get_address(),
                            listening_port,
                            local_endpoint.port(),
                            _node_public_key,
                            signature,
                            _chain_id,
                            generate_hello_user_data());
  
        peer->send_message(message(hello));
      }
  
      void node_impl::connect_to_task(peer_connection_ptr new_peer,
                                      const fc::ip::endpoint& remote_endpoint)
      {
        VERIFY_CORRECT_THREAD();
  
        if (!new_peer->performing_firewall_check())
        {
          // create or find the database entry for the new peer
          // if we're connecting to them, we believe they're not firewalled
          potential_peer_record updated_peer_record = _potential_peer_db.lookup_or_create_entry_for_endpoint(remote_endpoint);
          updated_peer_record.last_connection_disposition = last_connection_failed;
          updated_peer_record.last_connection_attempt_time = fc::time_point::now();;
          _potential_peer_db.update_entry(updated_peer_record);
        }
        else
        {
          wlog("connecting to peer ${peer} for firewall check", ("peer", new_peer->get_remote_endpoint()));
        }
  
        fc::oexception connect_failed_exception;
  
        try
        {
          new_peer->connect_to(remote_endpoint, _actual_listening_endpoint);  // blocks until the connection is established and secure connection is negotiated
  
          // we connected to the peer.  guess they're not firewalled....
          new_peer->is_firewalled = firewalled_state::not_firewalled;
  
          // connection succeeded, we've started handshaking.  record that in our database
          potential_peer_record updated_peer_record = _potential_peer_db.lookup_or_create_entry_for_endpoint(remote_endpoint);
          updated_peer_record.last_connection_disposition = last_connection_handshaking_failed;
          updated_peer_record.number_of_successful_connection_attempts++;
          updated_peer_record.last_seen_time = fc::time_point::now();
          _potential_peer_db.update_entry(updated_peer_record);
        }
        catch (const fc::exception& except)
        {
          connect_failed_exception = except;
        }
  
        if (connect_failed_exception && !new_peer->performing_firewall_check())
        {
          // connection failed.  record that in our database
          potential_peer_record updated_peer_record = _potential_peer_db.lookup_or_create_entry_for_endpoint(remote_endpoint);
          updated_peer_record.last_connection_disposition = last_connection_failed;
          updated_peer_record.number_of_failed_connection_attempts++;
          if (new_peer->connection_closed_error)
            updated_peer_record.last_error = *new_peer->connection_closed_error;
          else
            updated_peer_record.last_error = *connect_failed_exception;
          _potential_peer_db.update_entry(updated_peer_record);
        }
  
        if (new_peer->performing_firewall_check())
        {
          // we were connecting to test whether the node is firewalled, and we now know the result.
          // send a message back to the requester
          peer_connection_ptr requesting_peer = get_peer_by_node_id(new_peer->firewall_check_state->requesting_peer);
          if (requesting_peer)
          {
            check_firewall_reply_message reply;
            reply.endpoint_checked = new_peer->firewall_check_state->endpoint_to_test;
            reply.node_id = new_peer->firewall_check_state->expected_node_id;
            reply.result = connect_failed_exception ?
                             firewall_check_result::unable_to_connect :
                             firewall_check_result::connection_successful;
            wlog("firewall check of ${peer_checked} ${success_or_failure}, sending reply to ${requester}",
                  ("peer_checked", new_peer->get_remote_endpoint())
                  ("success_or_failure", connect_failed_exception ? "failed" : "succeeded" )
                  ("requester", requesting_peer->get_remote_endpoint()));
  
            requesting_peer->send_message(reply);
          }
        }
  
        if (connect_failed_exception || new_peer->performing_firewall_check())
        {
          // if the connection failed or if this connection was just intended to check
          // whether the peer is firewalled, we want to disconnect now.
          _handshaking_connections.erase(new_peer);
          _terminating_connections.erase(new_peer);
          assert(_active_connections.find(new_peer) == _active_connections.end());
          _active_connections.erase(new_peer);
          assert(_closing_connections.find(new_peer) == _closing_connections.end());
          _closing_connections.erase(new_peer);
  
          display_current_connections();
          trigger_p2p_network_connect_loop();
          schedule_peer_for_deletion(new_peer);
  
          if (connect_failed_exception)
            throw *connect_failed_exception;
        }
        else
        {
          // connection was successful and we want to stay connected
          fc::ip::endpoint local_endpoint = new_peer->get_local_endpoint();
          new_peer->inbound_address = local_endpoint.get_address();
          new_peer->inbound_port = _node_configuration.accept_incoming_connections ? _actual_listening_endpoint.port() : 0;
          new_peer->outbound_port = local_endpoint.port();
  
          new_peer->our_state = peer_connection::our_connection_state::just_connected;
          new_peer->their_state = peer_connection::their_connection_state::just_connected;
          send_hello_message(new_peer);
          dlog("Sent \"hello\" to peer ${peer}", ("peer", new_peer->get_remote_endpoint()));
        }
      }
  
      // methods implementing node's public interface
      void node_impl::set_node_delegate(node_delegate* del, fc::thread* thread_for_delegate_calls)
      {
        VERIFY_CORRECT_THREAD();
        _delegate.reset();
        if (del)
          _delegate.reset(new statistics_gathering_node_delegate_wrapper(del, thread_for_delegate_calls));
        if( _delegate )
          _chain_id = del->get_chain_id();
      }
  
      void node_impl::load_configuration( const fc::path& configuration_directory )
      {
        VERIFY_CORRECT_THREAD();
        _node_configuration_directory = configuration_directory;
        fc::path configuration_file_name( _node_configuration_directory / NODE_CONFIGURATION_FILENAME );
        bool node_configuration_loaded = false;
        if( fc::exists(configuration_file_name ) )
        {
          try
          {
            _node_configuration = fc::json::from_file( configuration_file_name ).as<detail::node_configuration>();
            ilog( "Loaded configuration from file ${filename}", ("filename", configuration_file_name ) );
  
            if( _node_configuration.private_key == fc::ecc::private_key() )
              _node_configuration.private_key = fc::ecc::private_key::generate();
  
            node_configuration_loaded = true;
          }
          catch ( fc::parse_error_exception& parse_error )
          {
            elog( "malformed node configuration file ${filename}: ${error}",
                 ( "filename", configuration_file_name )("error", parse_error.to_detail_string() ) );
          }
          catch ( fc::exception& except )
          {
            elog( "unexpected exception while reading configuration file ${filename}: ${error}",
                 ( "filename", configuration_file_name )("error", except.to_detail_string() ) );
          }
        }
  
        if( !node_configuration_loaded )
        {
          _node_configuration = detail::node_configuration();
  
  #ifdef GRAPHENE_TEST_NETWORK
          uint32_t port = GRAPHENE_NET_TEST_P2P_PORT;
  #else
          uint32_t port = GRAPHENE_NET_DEFAULT_P2P_PORT;
  #endif
          _node_configuration.listen_endpoint.set_port( port );
          _node_configuration.accept_incoming_connections = true;
          _node_configuration.wait_if_endpoint_is_busy = false;
  
          ilog( "generating new private key for this node" );
          _node_configuration.private_key = fc::ecc::private_key::generate();
        }
  
        _node_public_key = _node_configuration.private_key.get_public_key().serialize();
  
        fc::path potential_peer_database_file_name(_node_configuration_directory / POTENTIAL_PEER_DATABASE_FILENAME);
        try
        {
          _potential_peer_db.open(potential_peer_database_file_name);
  
          // push back the time on all peers loaded from the database so we will be able to retry them immediately
          for (peer_database::iterator itr = _potential_peer_db.begin(); itr != _potential_peer_db.end(); ++itr)
          {
            potential_peer_record updated_peer_record = *itr;
            updated_peer_record.last_connection_attempt_time = std::min<fc::time_point_sec>(updated_peer_record.last_connection_attempt_time,
                                                                                            fc::time_point::now() - fc::seconds(_peer_connection_retry_timeout));
            _potential_peer_db.update_entry(updated_peer_record);
          }
  
          trigger_p2p_network_connect_loop();
        }
        catch (fc::exception& except)
        {
          elog("unable to open peer database ${filename}: ${error}",
               ("filename", potential_peer_database_file_name)("error", except.to_detail_string()));
          throw;
        }
      }
  
      void node_impl::listen_to_p2p_network()
      {
        VERIFY_CORRECT_THREAD();
        if (!_node_configuration.accept_incoming_connections)
        {
          wlog("accept_incoming_connections is false, p2p network will not accept any incoming connections");
          return;
        }
  
        assert(_node_public_key != fc::ecc::public_key_data());
  
        fc::ip::endpoint listen_endpoint = _node_configuration.listen_endpoint;
        if( listen_endpoint.port() != 0 )
        {
          // if the user specified a port, we only want to bind to it if it's not already
          // being used by another application.  During normal operation, we set the
          // SO_REUSEADDR/SO_REUSEPORT flags so that we can bind outbound sockets to the
          // same local endpoint as we're listening on here.  On some platforms, setting
          // those flags will prevent us from detecting that other applications are
          // listening on that port.  We'd like to detect that, so we'll set up a temporary
          // tcp server without that flag to see if we can listen on that port.
          bool first = true;
          for( ;; )
          {
            bool listen_failed = false;
  
            try
            {
              fc::tcp_server temporary_server;
              if( listen_endpoint.get_address() != fc::ip::address() )
                temporary_server.listen( listen_endpoint );
              else
                temporary_server.listen( listen_endpoint.port() );
              break;
            }
            catch ( const fc::exception&)
            {
              listen_failed = true;
            }
  
            if (listen_failed)
            {
              if( _node_configuration.wait_if_endpoint_is_busy )
              {
                std::ostringstream error_message_stream;
                if( first )
                {
                  error_message_stream << "Unable to listen for connections on port " << listen_endpoint.port()
                                       << ", retrying in a few seconds\n";
                  error_message_stream << "You can wait for it to become available, or restart this program using\n";
                  error_message_stream << "the --p2p-port option to specify another port\n";
                  first = false;
                }
                else
                {
                  error_message_stream << "\nStill waiting for port " << listen_endpoint.port() << " to become available\n";
                }
                std::string error_message = error_message_stream.str();
                wlog(error_message);
                std::cout << "\033[31m" << error_message;  
                _delegate->error_encountered( error_message, fc::oexception() );
                fc::usleep( fc::seconds(5 ) );
              }
              else // don't wait, just find a random port
              {
                wlog( "unable to bind on the requested endpoint ${endpoint}, which probably means that endpoint is already in use",
                     ( "endpoint", listen_endpoint ) );
                listen_endpoint.set_port( 0 );
              }
            } // if (listen_failed)
          } // for(;;)
        } // if (listen_endpoint.port() != 0)
        else // port is 0
        {
          // if they requested a random port, we'll just assume it's available
          // (it may not be due to ip address, but we'll detect that in the next step)
        }
  
        _tcp_server.set_reuse_address();
        try
        {
          if( listen_endpoint.get_address() != fc::ip::address() )
            _tcp_server.listen( listen_endpoint );
          else
            _tcp_server.listen( listen_endpoint.port() );
          _actual_listening_endpoint = _tcp_server.get_local_endpoint();
          ilog( "listening for connections on endpoint ${endpoint} (our first choice)",
                ( "endpoint", _actual_listening_endpoint ) );
        }
        catch ( fc::exception& e )
        {
          FC_RETHROW_EXCEPTION( e, error, "unable to listen on ${endpoint}", ("endpoint",listen_endpoint ) );
        }
      }
  
      void node_impl::connect_to_p2p_network()
      {
        VERIFY_CORRECT_THREAD();
        assert(_node_public_key != fc::ecc::public_key_data());
  
        assert(!_accept_loop_complete.valid() &&
               !_p2p_network_connect_loop_done.valid() &&
               !_fetch_sync_items_loop_done.valid() &&
               !_fetch_item_loop_done.valid() &&
               !_advertise_inventory_loop_done.valid() &&
               !_terminate_inactive_connections_loop_done.valid() &&
               !_fetch_updated_peer_lists_loop_done.valid() &&
               !_bandwidth_monitor_loop_done.valid() &&
               !_dump_node_status_task_done.valid());
        if (_node_configuration.accept_incoming_connections)
          _accept_loop_complete = fc::async( [=](){ accept_loop(); }, "accept_loop");
        _p2p_network_connect_loop_done = fc::async( [=]() { p2p_network_connect_loop(); }, "p2p_network_connect_loop" );
        _fetch_sync_items_loop_done = fc::async( [=]() { fetch_sync_items_loop(); }, "fetch_sync_items_loop" );
        _fetch_item_loop_done = fc::async( [=]() { fetch_items_loop(); }, "fetch_items_loop" );
        _advertise_inventory_loop_done = fc::async( [=]() { advertise_inventory_loop(); }, "advertise_inventory_loop" );
        _terminate_inactive_connections_loop_done = fc::async( [=]() { terminate_inactive_connections_loop(); }, "terminate_inactive_connections_loop" );
        _fetch_updated_peer_lists_loop_done = fc::async([=](){ fetch_updated_peer_lists_loop(); }, "fetch_updated_peer_lists_loop");
        _bandwidth_monitor_loop_done = fc::async([=](){ bandwidth_monitor_loop(); }, "bandwidth_monitor_loop");
        _dump_node_status_task_done = fc::async([=](){ dump_node_status_task(); }, "dump_node_status_task");
      }
  
      void node_impl::add_node(const fc::ip::endpoint& ep)
      {
        VERIFY_CORRECT_THREAD();
        // if we're connecting to them, we believe they're not firewalled
        potential_peer_record updated_peer_record = _potential_peer_db.lookup_or_create_entry_for_endpoint(ep);
  
        // if we've recently connected to this peer, reset the last_connection_attempt_time to allow
        // us to immediately retry this peer
        updated_peer_record.last_connection_attempt_time = std::min<fc::time_point_sec>(updated_peer_record.last_connection_attempt_time,
                                                                                        fc::time_point::now() - fc::seconds(_peer_connection_retry_timeout));
        _add_once_node_list.push_back(updated_peer_record);
        _potential_peer_db.update_entry(updated_peer_record);
        trigger_p2p_network_connect_loop();
      }
  
      void node_impl::initiate_connect_to(const peer_connection_ptr& new_peer)
      {
        new_peer->get_socket().open();
        new_peer->get_socket().set_reuse_address();
        new_peer->connection_initiation_time = fc::time_point::now();
        _handshaking_connections.insert(new_peer);
        _rate_limiter.add_tcp_socket(&new_peer->get_socket());
  
        if (_node_is_shutting_down)
          return;
  
        std::weak_ptr<peer_connection> new_weak_peer(new_peer);
        new_peer->accept_or_connect_task_done = fc::async([this, new_weak_peer](){
          peer_connection_ptr new_peer(new_weak_peer.lock());
          assert(new_peer);
          if (!new_peer)
            return;
          connect_to_task(new_peer, *new_peer->get_remote_endpoint());
        }, "connect_to_task");
      }
  
      void node_impl::connect_to_endpoint(const fc::ip::endpoint& remote_endpoint)
      {
        VERIFY_CORRECT_THREAD();
        if (is_connection_to_endpoint_in_progress(remote_endpoint))
          FC_THROW_EXCEPTION(already_connected_to_requested_peer, "already connected to requested endpoint ${endpoint}",
                             ("endpoint", remote_endpoint));
  
        dlog("node_impl::connect_to_endpoint(${endpoint})", ("endpoint", remote_endpoint));
        peer_connection_ptr new_peer(peer_connection::make_shared(this));
        new_peer->set_remote_endpoint(remote_endpoint);
        initiate_connect_to(new_peer);
      }
  
      peer_connection_ptr node_impl::get_connection_to_endpoint( const fc::ip::endpoint& remote_endpoint )
      {
        VERIFY_CORRECT_THREAD();
        for( const peer_connection_ptr& active_peer : _active_connections )
        {
          fc::optional<fc::ip::endpoint> endpoint_for_this_peer( active_peer->get_remote_endpoint() );
          if( endpoint_for_this_peer && *endpoint_for_this_peer == remote_endpoint )
            return active_peer;
        }
        for( const peer_connection_ptr& handshaking_peer : _handshaking_connections )
        {
          fc::optional<fc::ip::endpoint> endpoint_for_this_peer( handshaking_peer->get_remote_endpoint() );
          if( endpoint_for_this_peer && *endpoint_for_this_peer == remote_endpoint )
            return handshaking_peer;
        }
        return peer_connection_ptr();
      }
  
      bool node_impl::is_connection_to_endpoint_in_progress( const fc::ip::endpoint& remote_endpoint )
      {
        VERIFY_CORRECT_THREAD();
        return get_connection_to_endpoint( remote_endpoint ) != peer_connection_ptr();
      }
  
      void node_impl::move_peer_to_active_list(const peer_connection_ptr& peer)
      {
        VERIFY_CORRECT_THREAD();
        _active_connections.insert(peer);
        _handshaking_connections.erase(peer);
        _closing_connections.erase(peer);
        _terminating_connections.erase(peer);
      }
  
      void node_impl::move_peer_to_closing_list(const peer_connection_ptr& peer)
      {
        VERIFY_CORRECT_THREAD();
        _active_connections.erase(peer);
        _handshaking_connections.erase(peer);
        _closing_connections.insert(peer);
        _terminating_connections.erase(peer);
      }
  
      void node_impl::move_peer_to_terminating_list(const peer_connection_ptr& peer)
      {
        VERIFY_CORRECT_THREAD();
        _active_connections.erase(peer);
        _handshaking_connections.erase(peer);
        _closing_connections.erase(peer);
        _terminating_connections.insert(peer);
      }
  
      void node_impl::dump_node_status()
      {
        VERIFY_CORRECT_THREAD();
        ilog( "----------------- PEER STATUS UPDATE --------------------" );
        ilog( " number of peers: ${active} active, ${handshaking}, ${closing} closing.  attempting to maintain ${desired} - ${maximum} peers",
             ( "active", _active_connections.size() )("handshaking", _handshaking_connections.size() )("closing",_closing_connections.size() )
             ( "desired", _desired_number_of_connections )("maximum", _maximum_number_of_connections ) );
        for( const peer_connection_ptr& peer : _active_connections )
        {
          ilog( "       active peer ${endpoint} peer_is_in_sync_with_us:${in_sync_with_us} we_are_in_sync_with_peer:${in_sync_with_them}",
               ( "endpoint", peer->get_remote_endpoint() )
               ( "in_sync_with_us", !peer->peer_needs_sync_items_from_us )("in_sync_with_them", !peer->we_need_sync_items_from_peer ) );
          if( peer->we_need_sync_items_from_peer )
            ilog( "              above peer has ${count} sync items we might need", ("count", peer->ids_of_items_to_get.size() ) );
          if (peer->inhibit_fetching_sync_blocks)
            ilog( "              we are not fetching sync blocks from the above peer (inhibit_fetching_sync_blocks == true)" );
  
        }
        for( const peer_connection_ptr& peer : _handshaking_connections )
        {
          ilog( "  handshaking peer ${endpoint} in state ours(${our_state}) theirs(${their_state})",
               ( "endpoint", peer->get_remote_endpoint() )("our_state", peer->our_state )("their_state", peer->their_state ) );
        }
  
        ilog( "--------- MEMORY USAGE ------------" );
        ilog( "node._active_sync_requests size: ${size}", ("size", _active_sync_requests.size() ) );
        ilog( "node._received_sync_items size: ${size}", ("size", _received_sync_items.size() ) );
        ilog( "node._new_received_sync_items size: ${size}", ("size", _new_received_sync_items.size() ) );
        ilog( "node._items_to_fetch size: ${size}", ("size", _items_to_fetch.size() ) );
        ilog( "node._new_inventory size: ${size}", ("size", _new_inventory.size() ) );
        ilog( "node._message_cache size: ${size}", ("size", _message_cache.size() ) );
        for( const peer_connection_ptr& peer : _active_connections )
        {
          ilog( "  peer ${endpoint}", ("endpoint", peer->get_remote_endpoint() ) );
          ilog( "    peer.ids_of_items_to_get size: ${size}", ("size", peer->ids_of_items_to_get.size() ) );
          ilog( "    peer.inventory_peer_advertised_to_us size: ${size}", ("size", peer->inventory_peer_advertised_to_us.size() ) );
          ilog( "    peer.inventory_advertised_to_peer size: ${size}", ("size", peer->inventory_advertised_to_peer.size() ) );
          ilog( "    peer.items_requested_from_peer size: ${size}", ("size", peer->items_requested_from_peer.size() ) );
          ilog( "    peer.sync_items_requested_from_peer size: ${size}", ("size", peer->sync_items_requested_from_peer.size() ) );
        }
        ilog( "--------- END MEMORY USAGE ------------" );
      }
  
      void node_impl::disconnect_from_peer( peer_connection* peer_to_disconnect,
                                            const std::string& reason_for_disconnect,
                                            bool caused_by_error /* = false */,
                                            const fc::oexception& error /* = fc::oexception() */ )
      {
        VERIFY_CORRECT_THREAD();
        move_peer_to_closing_list(peer_to_disconnect->shared_from_this());
  
        if (peer_to_disconnect->they_have_requested_close)
        {
          // the peer has already told us that it's ready to close the connection, so just close the connection
          peer_to_disconnect->close_connection();
        }
        else
        {
          // we're the first to try to want to close the connection
          fc::optional<fc::ip::endpoint> inbound_endpoint = peer_to_disconnect->get_endpoint_for_connecting();
          if (inbound_endpoint)
          {
            fc::optional<potential_peer_record> updated_peer_record = _potential_peer_db.lookup_entry_for_endpoint(*inbound_endpoint);
            if (updated_peer_record)
            {
              updated_peer_record->last_seen_time = fc::time_point::now();
              if (error)
                updated_peer_record->last_error = error;
              else
                updated_peer_record->last_error = fc::exception(FC_LOG_MESSAGE(info, reason_for_disconnect.c_str()));
              _potential_peer_db.update_entry(*updated_peer_record);
            }
          }
          peer_to_disconnect->we_have_requested_close = true;
          peer_to_disconnect->connection_closed_time = fc::time_point::now();
  
          closing_connection_message closing_message( reason_for_disconnect, caused_by_error, error );
          peer_to_disconnect->send_message( closing_message );
        }
  
        // notify the user.  This will be useful in testing, but we might want to remove it later;
        // it makes good sense to notify the user if other nodes think she is behaving badly, but
        // if we're just detecting and dissconnecting other badly-behaving nodes, they don't really care.
        if (caused_by_error)
        {
          std::ostringstream error_message;
          error_message << "I am disconnecting peer " << fc::variant( peer_to_disconnect->get_remote_endpoint() ).as_string() <<
                           " for reason: " << reason_for_disconnect;
          _delegate->error_encountered(error_message.str(), fc::oexception());
          dlog(error_message.str());
        }
        else
          dlog("Disconnecting from ${peer} for ${reason}", ("peer",peer_to_disconnect->get_remote_endpoint()) ("reason",reason_for_disconnect));
        // peer_to_disconnect->close_connection();
      }
  
      void node_impl::listen_on_endpoint( const fc::ip::endpoint& ep, bool wait_if_not_available )
      {
        VERIFY_CORRECT_THREAD();
        _node_configuration.listen_endpoint = ep;
        _node_configuration.wait_if_endpoint_is_busy = wait_if_not_available;
        save_node_configuration();
      }
  
      void node_impl::accept_incoming_connections(bool accept)
      {
        VERIFY_CORRECT_THREAD();
        _node_configuration.accept_incoming_connections = accept;
        save_node_configuration();
      }
  
      void node_impl::listen_on_port( uint16_t port, bool wait_if_not_available )
      {
        VERIFY_CORRECT_THREAD();
        _node_configuration.listen_endpoint = fc::ip::endpoint( fc::ip::address(), port );
        _node_configuration.wait_if_endpoint_is_busy = wait_if_not_available;
        save_node_configuration();
      }
  
      fc::ip::endpoint node_impl::get_actual_listening_endpoint() const
      {
        VERIFY_CORRECT_THREAD();
        return _actual_listening_endpoint;
      }
  
      std::vector<peer_status> node_impl::get_connected_peers() const
      {
        VERIFY_CORRECT_THREAD();
        std::vector<peer_status> statuses;
        for (const peer_connection_ptr& peer : _active_connections)
        {
          ASSERT_TASK_NOT_PREEMPTED(); // don't yield while iterating over _active_connections
  
          peer_status this_peer_status;
          this_peer_status.version = 0;
          fc::optional<fc::ip::endpoint> endpoint = peer->get_remote_endpoint();
          if (endpoint)
            this_peer_status.host = *endpoint;
          fc::mutable_variant_object peer_details;
          peer_details["addr"] = endpoint ? (std::string)*endpoint : std::string();
          peer_details["addrlocal"] = (std::string)peer->get_local_endpoint();
          peer_details["services"] = "00000001";
          peer_details["lastsend"] = peer->get_last_message_sent_time().sec_since_epoch();
          peer_details["lastrecv"] = peer->get_last_message_received_time().sec_since_epoch();
          peer_details["bytessent"] = peer->get_total_bytes_sent();
          peer_details["bytesrecv"] = peer->get_total_bytes_received();
          peer_details["conntime"] = peer->get_connection_time();
          peer_details["pingtime"] = "";
          peer_details["pingwait"] = "";
          peer_details["version"] = "";
          peer_details["subver"] = peer->user_agent;
          peer_details["inbound"] = peer->direction == peer_connection_direction::inbound;
          peer_details["firewall_status"] = peer->is_firewalled;
          peer_details["startingheight"] = "";
          peer_details["banscore"] = "";
          peer_details["syncnode"] = "";
  
          if (peer->fc_git_revision_sha)
          {
            std::string revision_string = *peer->fc_git_revision_sha;
            if (*peer->fc_git_revision_sha == fc::git_revision_sha)
              revision_string += " (same as ours)";
            else
              revision_string += " (different from ours)";
            peer_details["fc_git_revision_sha"] = revision_string;
  
          }
          if (peer->fc_git_revision_unix_timestamp)
          {
            peer_details["fc_git_revision_unix_timestamp"] = *peer->fc_git_revision_unix_timestamp;
            std::string age_string = fc::get_approximate_relative_time_string( *peer->fc_git_revision_unix_timestamp);
            if (*peer->fc_git_revision_unix_timestamp == fc::time_point_sec(fc::git_revision_unix_timestamp))
              age_string += " (same as ours)";
            else if (*peer->fc_git_revision_unix_timestamp > fc::time_point_sec(fc::git_revision_unix_timestamp))
              age_string += " (newer than ours)";
            else
              age_string += " (older than ours)";
            peer_details["fc_git_revision_age"] = age_string;
          }
  
          if (peer->platform)
            peer_details["platform"] = *peer->platform;
  
          // provide these for debugging
          // warning: these are just approximations, if the peer is "downstream" of us, they may
          // have received blocks from other peers that we are unaware of
          peer_details["current_head_block"] = peer->last_block_delegate_has_seen;
          peer_details["current_head_block_number"] = _delegate->get_block_number(peer->last_block_delegate_has_seen);
          peer_details["current_head_block_time"] = peer->last_block_time_delegate_has_seen;
  
          this_peer_status.info = peer_details;
          statuses.push_back(this_peer_status);
        }
        return statuses;
      }
  
      uint32_t node_impl::get_connection_count() const
      {
        VERIFY_CORRECT_THREAD();
        return (uint32_t)_active_connections.size();
      }
  
      void node_impl::broadcast( const message& item_to_broadcast, const message_propagation_data& propagation_data )
      {
        VERIFY_CORRECT_THREAD();
        fc::uint160_t hash_of_message_contents;
        if( item_to_broadcast.msg_type == graphene::net::block_message_type )
        {
          graphene::net::block_message block_message_to_broadcast = item_to_broadcast.as<graphene::net::block_message>();
          hash_of_message_contents = block_message_to_broadcast.block_id; // for debugging
          _most_recent_blocks_accepted.push_back( block_message_to_broadcast.block_id );
        }
        else if( item_to_broadcast.msg_type == graphene::net::trx_message_type )
        {
          graphene::net::trx_message transaction_message_to_broadcast = item_to_broadcast.as<graphene::net::trx_message>();
          hash_of_message_contents = transaction_message_to_broadcast.trx.id(); // for debugging
          dlog( "broadcasting trx: ${trx}", ("trx", transaction_message_to_broadcast) );
        }
        message_hash_type hash_of_item_to_broadcast = item_to_broadcast.id();
  
        _message_cache.cache_message( item_to_broadcast, hash_of_item_to_broadcast, propagation_data, hash_of_message_contents );
        _new_inventory.insert( item_id(item_to_broadcast.msg_type, hash_of_item_to_broadcast ) );
        trigger_advertise_inventory_loop();
      }
  
      void node_impl::broadcast( const message& item_to_broadcast )
      {
        VERIFY_CORRECT_THREAD();
        // this version is called directly from the client
        message_propagation_data propagation_data{fc::time_point::now(), fc::time_point::now(), _node_id};
        broadcast( item_to_broadcast, propagation_data );
      }
  
      void node_impl::sync_from(const item_id& current_head_block, const std::vector<uint32_t>& hard_fork_block_numbers)
      {
        VERIFY_CORRECT_THREAD();
        _most_recent_blocks_accepted.clear();
        _sync_item_type = current_head_block.item_type;
        _most_recent_blocks_accepted.push_back(current_head_block.item_hash);
        _hard_fork_block_numbers = hard_fork_block_numbers;
      }
  
      bool node_impl::is_connected() const
      {
        VERIFY_CORRECT_THREAD();
        return !_active_connections.empty();
      }
  
      std::vector<potential_peer_record> node_impl::get_potential_peers() const
      {
        VERIFY_CORRECT_THREAD();
        std::vector<potential_peer_record> result;
        // use explicit iterators here, for some reason the mac compiler can't used ranged-based for loops here
        for (peer_database::iterator itr = _potential_peer_db.begin(); itr != _potential_peer_db.end(); ++itr)
          result.push_back(*itr);
        return result;
      }
  
      void node_impl::set_advanced_node_parameters(const fc::variant_object& params)
      {
        VERIFY_CORRECT_THREAD();
        if (params.contains("peer_connection_retry_timeout"))
          _peer_connection_retry_timeout = params["peer_connection_retry_timeout"].as<uint32_t>();
        if (params.contains("desired_number_of_connections"))
          _desired_number_of_connections = params["desired_number_of_connections"].as<uint32_t>();
        if (params.contains("maximum_number_of_connections"))
          _maximum_number_of_connections = params["maximum_number_of_connections"].as<uint32_t>();
        if (params.contains("maximum_number_of_blocks_to_handle_at_one_time"))
          _maximum_number_of_blocks_to_handle_at_one_time = params["maximum_number_of_blocks_to_handle_at_one_time"].as<uint32_t>();
        if (params.contains("maximum_number_of_sync_blocks_to_prefetch"))
          _maximum_number_of_sync_blocks_to_prefetch = params["maximum_number_of_sync_blocks_to_prefetch"].as<uint32_t>();
        if (params.contains("maximum_blocks_per_peer_during_syncing"))
          _maximum_blocks_per_peer_during_syncing = params["maximum_blocks_per_peer_during_syncing"].as<uint32_t>();
  
        _desired_number_of_connections = std::min(_desired_number_of_connections, _maximum_number_of_connections);
  
        while (_active_connections.size() > _maximum_number_of_connections)
          disconnect_from_peer(_active_connections.begin()->get(),
                               "I have too many connections open");
        trigger_p2p_network_connect_loop();
      }
  
      fc::variant_object node_impl::get_advanced_node_parameters()
      {
        VERIFY_CORRECT_THREAD();
        fc::mutable_variant_object result;
        result["peer_connection_retry_timeout"] = _peer_connection_retry_timeout;
        result["desired_number_of_connections"] = _desired_number_of_connections;
        result["maximum_number_of_connections"] = _maximum_number_of_connections;
        result["maximum_number_of_blocks_to_handle_at_one_time"] = _maximum_number_of_blocks_to_handle_at_one_time;
        result["maximum_number_of_sync_blocks_to_prefetch"] = _maximum_number_of_sync_blocks_to_prefetch;
        result["maximum_blocks_per_peer_during_syncing"] = _maximum_blocks_per_peer_during_syncing;
        return result;
      }
  
      message_propagation_data node_impl::get_transaction_propagation_data( const graphene::net::transaction_id_type& transaction_id )
      {
        VERIFY_CORRECT_THREAD();
        return _message_cache.get_message_propagation_data( transaction_id );
      }
  
      message_propagation_data node_impl::get_block_propagation_data( const graphene::net::block_id_type& block_id )
      {
        VERIFY_CORRECT_THREAD();
        return _message_cache.get_message_propagation_data( block_id );
      }
  
      node_id_t node_impl::get_node_id() const
      {
        VERIFY_CORRECT_THREAD();
        return _node_id;
      }
      void node_impl::set_allowed_peers(const std::vector<node_id_t>& allowed_peers)
      {
        VERIFY_CORRECT_THREAD();
  #ifdef ENABLE_P2P_DEBUGGING_API
        _allowed_peers.clear();
        _allowed_peers.insert(allowed_peers.begin(), allowed_peers.end());
        std::list<peer_connection_ptr> peers_to_disconnect;
        if (!_allowed_peers.empty())
          for (const peer_connection_ptr& peer : _active_connections)
            if (_allowed_peers.find(peer->node_id) == _allowed_peers.end())
              peers_to_disconnect.push_back(peer);
        for (const peer_connection_ptr& peer : peers_to_disconnect)
          disconnect_from_peer(peer.get(), "My allowed_peers list has changed, and you're no longer allowed.  Bye.");
  #endif // ENABLE_P2P_DEBUGGING_API
      }
      void node_impl::clear_peer_database()
      {
        VERIFY_CORRECT_THREAD();
        _potential_peer_db.clear();
      }
  
      void node_impl::set_total_bandwidth_limit( uint32_t upload_bytes_per_second, uint32_t download_bytes_per_second )
      {
        VERIFY_CORRECT_THREAD();
        _rate_limiter.set_upload_limit( upload_bytes_per_second );
        _rate_limiter.set_download_limit( download_bytes_per_second );
      }
  
      void node_impl::disable_peer_advertising()
      {
        VERIFY_CORRECT_THREAD();
        _peer_advertising_disabled = true;
      }
  
      fc::variant_object node_impl::get_call_statistics() const
      {
        VERIFY_CORRECT_THREAD();
        return _delegate->get_call_statistics();
      }
  
      fc::variant_object node_impl::network_get_info() const
      {
        VERIFY_CORRECT_THREAD();
        fc::mutable_variant_object info;
        info["listening_on"] = _actual_listening_endpoint;
        info["node_public_key"] = _node_public_key;
        info["node_id"] = _node_id;
        info["firewalled"] = _is_firewalled;
  	  info["connections"] = _active_connections.size();
  	  item_hash_t head_block_id = _delegate->get_head_block_id();
  	  auto current_height = _delegate->get_block_number(head_block_id);
  	  info["current_block_height"] = current_height;
  	  info["target_block_height"] = _total_number_of_unfetched_items+ current_height;
        return info;
      }
      fc::variant_object node_impl::network_get_usage_stats() const
      {
        VERIFY_CORRECT_THREAD();
        std::vector<uint32_t> network_usage_by_second;
        network_usage_by_second.reserve(_average_network_read_speed_seconds.size());
        std::transform(_average_network_read_speed_seconds.begin(), _average_network_read_speed_seconds.end(),
                       _average_network_write_speed_seconds.begin(),
                       std::back_inserter(network_usage_by_second),
                       std::plus<uint32_t>());
  
        std::vector<uint32_t> network_usage_by_minute;
        network_usage_by_minute.reserve(_average_network_read_speed_minutes.size());
        std::transform(_average_network_read_speed_minutes.begin(), _average_network_read_speed_minutes.end(),
                       _average_network_write_speed_minutes.begin(),
                       std::back_inserter(network_usage_by_minute),
                       std::plus<uint32_t>());
  
        std::vector<uint32_t> network_usage_by_hour;
        network_usage_by_hour.reserve(_average_network_read_speed_hours.size());
        std::transform(_average_network_read_speed_hours.begin(), _average_network_read_speed_hours.end(),
                       _average_network_write_speed_hours.begin(),
                       std::back_inserter(network_usage_by_hour),
                       std::plus<uint32_t>());
  
        fc::mutable_variant_object result;
        result["usage_by_second"] = network_usage_by_second;
        result["usage_by_minute"] = network_usage_by_minute;
        result["usage_by_hour"] = network_usage_by_hour;
        return result;
      }
  
      bool node_impl::is_hard_fork_block(uint32_t block_number) const
      {
        return std::binary_search(_hard_fork_block_numbers.begin(), _hard_fork_block_numbers.end(), block_number);
      }
      uint32_t node_impl::get_next_known_hard_fork_block_number(uint32_t block_number) const
      {
        auto iter = std::upper_bound(_hard_fork_block_numbers.begin(), _hard_fork_block_numbers.end(),
                                     block_number);
        return iter != _hard_fork_block_numbers.end() ? *iter : 0;
      }
  
    }  // end namespace detail
  
  
  
    /////////////////////////////////////////////////////////////////////////////////////////////////////////////
    // implement node functions, they call the matching function in to detail::node_impl in the correct thread //
  
  #ifdef P2P_IN_DEDICATED_THREAD
  # define INVOKE_IN_IMPL(method_name, ...) \
      return my->_thread->async([&](){ return my->method_name(__VA_ARGS__); }, "thread invoke for method " BOOST_PP_STRINGIZE(method_name)).wait()
  #else
  # define INVOKE_IN_IMPL(method_name, ...) \
      return my->method_name(__VA_ARGS__)
  #endif // P2P_IN_DEDICATED_THREAD
  
    node::node(const std::string& user_agent) :
      my(new detail::node_impl(user_agent))
    {
    }
  
    node::~node()
    {
    }
  
    void node::set_node_delegate( node_delegate* del )
    {
      fc::thread* delegate_thread = &fc::thread::current();
      INVOKE_IN_IMPL(set_node_delegate, del, delegate_thread);
    }
  
    void node::load_configuration( const fc::path& configuration_directory )
    {
      INVOKE_IN_IMPL(load_configuration, configuration_directory);
    }
  
    void node::listen_to_p2p_network()
    {
      INVOKE_IN_IMPL(listen_to_p2p_network);
    }
  
    void node::connect_to_p2p_network()
    {
      INVOKE_IN_IMPL(connect_to_p2p_network);
    }
  
    void node::add_node( const fc::ip::endpoint& ep )
    {
      INVOKE_IN_IMPL(add_node, ep);
    }
  
    void node::connect_to_endpoint( const fc::ip::endpoint& remote_endpoint )
    {
      INVOKE_IN_IMPL(connect_to_endpoint, remote_endpoint);
    }
  
    void node::listen_on_endpoint(const fc::ip::endpoint& ep , bool wait_if_not_available)
    {
      INVOKE_IN_IMPL(listen_on_endpoint, ep, wait_if_not_available);
    }
  
    void node::accept_incoming_connections(bool accept)
    {
      INVOKE_IN_IMPL(accept_incoming_connections, accept);
    }
  
    void node::listen_on_port( uint16_t port, bool wait_if_not_available )
    {
      INVOKE_IN_IMPL(listen_on_port, port, wait_if_not_available);
    }
  
    fc::ip::endpoint node::get_actual_listening_endpoint() const
    {
      INVOKE_IN_IMPL(get_actual_listening_endpoint);
    }
  
    std::vector<peer_status> node::get_connected_peers() const
    {
      INVOKE_IN_IMPL(get_connected_peers);
    }
  
    uint32_t node::get_connection_count() const
    {
      INVOKE_IN_IMPL(get_connection_count);
    }
  
    void node::broadcast( const message& msg )
    {
      INVOKE_IN_IMPL(broadcast, msg);
    }
  
    void node::sync_from(const item_id& current_head_block, const std::vector<uint32_t>& hard_fork_block_numbers)
    {
      INVOKE_IN_IMPL(sync_from, current_head_block, hard_fork_block_numbers);
    }
  
    bool node::is_connected() const
    {
      INVOKE_IN_IMPL(is_connected);
    }
  
    std::vector<potential_peer_record> node::get_potential_peers()const
    {
      INVOKE_IN_IMPL(get_potential_peers);
    }
  
    void node::set_advanced_node_parameters( const fc::variant_object& params )
    {
      INVOKE_IN_IMPL(set_advanced_node_parameters, params);
    }
  
    fc::variant_object node::get_advanced_node_parameters()
    {
      INVOKE_IN_IMPL(get_advanced_node_parameters);
    }
  
    message_propagation_data node::get_transaction_propagation_data( const graphene::net::transaction_id_type& transaction_id )
    {
      INVOKE_IN_IMPL(get_transaction_propagation_data, transaction_id);
    }
  
    message_propagation_data node::get_block_propagation_data( const graphene::net::block_id_type& block_id )
    {
      INVOKE_IN_IMPL(get_block_propagation_data, block_id);
    }
  
    node_id_t node::get_node_id() const
    {
      INVOKE_IN_IMPL(get_node_id);
    }
  
    void node::set_allowed_peers( const std::vector<node_id_t>& allowed_peers )
    {
      INVOKE_IN_IMPL(set_allowed_peers, allowed_peers);
    }
  
    void node::clear_peer_database()
    {
      INVOKE_IN_IMPL(clear_peer_database);
    }
  
    void node::set_total_bandwidth_limit(uint32_t upload_bytes_per_second,
                                         uint32_t download_bytes_per_second)
    {
      INVOKE_IN_IMPL(set_total_bandwidth_limit, upload_bytes_per_second, download_bytes_per_second);
    }
  
    void node::disable_peer_advertising()
    {
      INVOKE_IN_IMPL(disable_peer_advertising);
    }
  
    fc::variant_object node::get_call_statistics() const
    {
      INVOKE_IN_IMPL(get_call_statistics);
    }
  
    fc::variant_object node::network_get_info() const
    {
      INVOKE_IN_IMPL(network_get_info);
    }
  
    fc::variant_object node::network_get_usage_stats() const
    {
      INVOKE_IN_IMPL(network_get_usage_stats);
    }
  
    void node::close()
    {
      INVOKE_IN_IMPL(close);
    }
  
    struct simulated_network::node_info
    {
      node_delegate* delegate;
      fc::future<void> message_sender_task_done;
      std::queue<message> messages_to_deliver;
      node_info(node_delegate* delegate) : delegate(delegate) {}
    };
  
    simulated_network::~simulated_network()
    {
      for( node_info* network_node_info : network_nodes )
      {
        network_node_info->message_sender_task_done.cancel_and_wait("~simulated_network()");
        delete network_node_info;
      }
    }
  
    void simulated_network::message_sender(node_info* destination_node)
    {
      while (!destination_node->messages_to_deliver.empty())
      {
        try
        {
          const message& message_to_deliver = destination_node->messages_to_deliver.front();
          if (message_to_deliver.msg_type == trx_message_type)
            destination_node->delegate->handle_transaction(message_to_deliver.as<trx_message>());
          else if (message_to_deliver.msg_type == block_message_type)
          {
            std::vector<fc::uint160_t> contained_transaction_message_ids;
            destination_node->delegate->handle_block(message_to_deliver.as<block_message>(), false, contained_transaction_message_ids);
          }
          else
            destination_node->delegate->handle_message(message_to_deliver);
        }
        catch ( const fc::exception& e )
        {
          elog( "${r}", ("r",e) );
        }
        destination_node->messages_to_deliver.pop();
      }
    }
  
    void simulated_network::broadcast( const message& item_to_broadcast  )
    {
      for (node_info* network_node_info : network_nodes)
      {
        network_node_info->messages_to_deliver.emplace(item_to_broadcast);
        if (!network_node_info->message_sender_task_done.valid() || network_node_info->message_sender_task_done.ready())
          network_node_info->message_sender_task_done = fc::async([=](){ message_sender(network_node_info); }, "simulated_network_sender");
      }
    }
  
    void simulated_network::add_node_delegate( node_delegate* node_delegate_to_add )
    {
      network_nodes.push_back(new node_info(node_delegate_to_add));
    }
  
    namespace detail
    {
  #define ROLLING_WINDOW_SIZE 1000
  #define INITIALIZE_ACCUMULATOR(r, data, method_name) \
        , BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _execution_accumulator))(boost::accumulators::tag::rolling_window::window_size = ROLLING_WINDOW_SIZE) \
        , BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _delay_before_accumulator))(boost::accumulators::tag::rolling_window::window_size = ROLLING_WINDOW_SIZE) \
        , BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _delay_after_accumulator))(boost::accumulators::tag::rolling_window::window_size = ROLLING_WINDOW_SIZE)
  
  
      statistics_gathering_node_delegate_wrapper::statistics_gathering_node_delegate_wrapper(node_delegate* delegate, fc::thread* thread_for_delegate_calls) :
        _node_delegate(delegate),
        _thread(thread_for_delegate_calls)
        BOOST_PP_SEQ_FOR_EACH(INITIALIZE_ACCUMULATOR, unused, NODE_DELEGATE_METHOD_NAMES)
      {}
  #undef INITIALIZE_ACCUMULATOR
  
      fc::variant_object statistics_gathering_node_delegate_wrapper::get_call_statistics()
      {
        fc::mutable_variant_object statistics;
        std::ostringstream note;
        note << "All times are in microseconds, mean is the average of the last " << ROLLING_WINDOW_SIZE << " call times";
        statistics["_note"] = note.str();
  
  #define ADD_STATISTICS_FOR_METHOD(r, data, method_name) \
        fc::mutable_variant_object BOOST_PP_CAT(method_name, _stats); \
        BOOST_PP_CAT(method_name, _stats)["min"] = boost::accumulators::min(BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _execution_accumulator))); \
        BOOST_PP_CAT(method_name, _stats)["mean"] = boost::accumulators::rolling_mean(BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _execution_accumulator))); \
        BOOST_PP_CAT(method_name, _stats)["max"] = boost::accumulators::max(BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _execution_accumulator))); \
        BOOST_PP_CAT(method_name, _stats)["sum"] = boost::accumulators::sum(BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _execution_accumulator))); \
        BOOST_PP_CAT(method_name, _stats)["delay_before_min"] = boost::accumulators::min(BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _delay_before_accumulator))); \
        BOOST_PP_CAT(method_name, _stats)["delay_before_mean"] = boost::accumulators::rolling_mean(BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _delay_before_accumulator))); \
        BOOST_PP_CAT(method_name, _stats)["delay_before_max"] = boost::accumulators::max(BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _delay_before_accumulator))); \
        BOOST_PP_CAT(method_name, _stats)["delay_before_sum"] = boost::accumulators::sum(BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _delay_before_accumulator))); \
        BOOST_PP_CAT(method_name, _stats)["delay_after_min"] = boost::accumulators::min(BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _delay_after_accumulator))); \
        BOOST_PP_CAT(method_name, _stats)["delay_after_mean"] = boost::accumulators::rolling_mean(BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _delay_after_accumulator))); \
        BOOST_PP_CAT(method_name, _stats)["delay_after_max"] = boost::accumulators::max(BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _delay_after_accumulator))); \
        BOOST_PP_CAT(method_name, _stats)["delay_after_sum"] = boost::accumulators::sum(BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _delay_after_accumulator))); \
        BOOST_PP_CAT(method_name, _stats)["count"] = boost::accumulators::count(BOOST_PP_CAT(_, BOOST_PP_CAT(method_name, _execution_accumulator))); \
        statistics[BOOST_PP_STRINGIZE(method_name)] = BOOST_PP_CAT(method_name, _stats);
  
        BOOST_PP_SEQ_FOR_EACH(ADD_STATISTICS_FOR_METHOD, unused, NODE_DELEGATE_METHOD_NAMES)
  #undef ADD_STATISTICS_FOR_METHOD
  
        return statistics;
      }
  
  // define VERBOSE_NODE_DELEGATE_LOGGING to log whenever the node delegate throws exceptions
  //#define VERBOSE_NODE_DELEGATE_LOGGING
  #ifdef VERBOSE_NODE_DELEGATE_LOGGING
  #  define INVOKE_AND_COLLECT_STATISTICS(method_name, ...) \
      try \
      { \
        call_statistics_collector statistics_collector(#method_name, \
                                                       &_ ## method_name ## _execution_accumulator, \
                                                       &_ ## method_name ## _delay_before_accumulator, \
                                                       &_ ## method_name ## _delay_after_accumulator); \
        if (_thread->is_current()) \
        { \
          call_statistics_collector::actual_execution_measurement_helper helper(statistics_collector); \
          return _node_delegate->method_name(__VA_ARGS__); \
        } \
        else \
          return _thread->async([&](){ \
            call_statistics_collector::actual_execution_measurement_helper helper(statistics_collector); \
            return _node_delegate->method_name(__VA_ARGS__); \
          }, "invoke " BOOST_STRINGIZE(method_name)).wait(); \
      } \
      catch (const fc::exception& e) \
      { \
        dlog("node_delegate threw fc::exception: ${e}", ("e", e)); \
        throw; \
      } \
      catch (const std::exception& e) \
      { \
        dlog("node_delegate threw std::exception: ${e}", ("e", e.what())); \
        throw; \
      } \
      catch (...) \
      { \
        dlog("node_delegate threw unrecognized exception"); \
        throw; \
      }
  #else
  #  define INVOKE_AND_COLLECT_STATISTICS(method_name, ...) \
      call_statistics_collector statistics_collector(#method_name, \
                                                     &_ ## method_name ## _execution_accumulator, \
                                                     &_ ## method_name ## _delay_before_accumulator, \
                                                     &_ ## method_name ## _delay_after_accumulator); \
      if (_thread->is_current()) \
      { \
        call_statistics_collector::actual_execution_measurement_helper helper(statistics_collector); \
        return _node_delegate->method_name(__VA_ARGS__); \
      } \
      else \
        return _thread->async([&](){ \
          call_statistics_collector::actual_execution_measurement_helper helper(statistics_collector); \
          return _node_delegate->method_name(__VA_ARGS__); \
        }, "invoke " BOOST_STRINGIZE(method_name)).wait()
  #endif
  
      bool statistics_gathering_node_delegate_wrapper::has_item( const net::item_id& id )
      {
        INVOKE_AND_COLLECT_STATISTICS(has_item, id);
      }
  
      void statistics_gathering_node_delegate_wrapper::handle_message( const message& message_to_handle )
      {
        INVOKE_AND_COLLECT_STATISTICS(handle_message, message_to_handle);
      }
  
      bool statistics_gathering_node_delegate_wrapper::handle_block( const graphene::net::block_message& block_message, bool sync_mode, std::vector<fc::uint160_t>& contained_transaction_message_ids,bool stoppable)
      {
        INVOKE_AND_COLLECT_STATISTICS(handle_block, block_message, sync_mode, contained_transaction_message_ids, stoppable);
      }
  
      void statistics_gathering_node_delegate_wrapper::handle_transaction( const graphene::net::trx_message& transaction_message )
      {
        INVOKE_AND_COLLECT_STATISTICS(handle_transaction, transaction_message);
      }
  
      std::vector<item_hash_t> statistics_gathering_node_delegate_wrapper::get_block_ids(const std::vector<item_hash_t>& blockchain_synopsis,
                                                                                         uint32_t& remaining_item_count,
                                                                                         uint32_t limit /* = 2000 */)
      {
        INVOKE_AND_COLLECT_STATISTICS(get_block_ids, blockchain_synopsis, remaining_item_count, limit);
      }
  
      message statistics_gathering_node_delegate_wrapper::get_item( const item_id& id )
      {
        INVOKE_AND_COLLECT_STATISTICS(get_item, id);
      }
  
      chain_id_type statistics_gathering_node_delegate_wrapper::get_chain_id() const
      {
        INVOKE_AND_COLLECT_STATISTICS(get_chain_id);
      }
  
      std::vector<item_hash_t> statistics_gathering_node_delegate_wrapper::get_blockchain_synopsis(const item_hash_t& reference_point, uint32_t number_of_blocks_after_reference_point)
      {
        INVOKE_AND_COLLECT_STATISTICS(get_blockchain_synopsis, reference_point, number_of_blocks_after_reference_point);
      }
  
      void statistics_gathering_node_delegate_wrapper::sync_status( uint32_t item_type, uint32_t item_count )
      {
        INVOKE_AND_COLLECT_STATISTICS(sync_status, item_type, item_count);
      }
  
      void statistics_gathering_node_delegate_wrapper::connection_count_changed( uint32_t c )
      {
        INVOKE_AND_COLLECT_STATISTICS(connection_count_changed, c);
      }
  
      uint32_t statistics_gathering_node_delegate_wrapper::get_block_number(const item_hash_t& block_id)
      {
        // this function doesn't need to block,
        ASSERT_TASK_NOT_PREEMPTED();
        return _node_delegate->get_block_number(block_id);
      }
  
      fc::time_point_sec statistics_gathering_node_delegate_wrapper::get_block_time(const item_hash_t& block_id)
      {
        INVOKE_AND_COLLECT_STATISTICS(get_block_time, block_id);
      }
  
      item_hash_t statistics_gathering_node_delegate_wrapper::get_head_block_id() const
      {
        INVOKE_AND_COLLECT_STATISTICS(get_head_block_id);
      }
  
      uint32_t statistics_gathering_node_delegate_wrapper::estimate_last_known_fork_from_git_revision_timestamp(uint32_t unix_timestamp) const
      {
        INVOKE_AND_COLLECT_STATISTICS(estimate_last_known_fork_from_git_revision_timestamp, unix_timestamp);
      }
  
      void statistics_gathering_node_delegate_wrapper::error_encountered(const std::string& message, const fc::oexception& error)
      {
        INVOKE_AND_COLLECT_STATISTICS(error_encountered, message, error);
      }
  
      uint8_t statistics_gathering_node_delegate_wrapper::get_current_block_interval_in_seconds() const
      {
        INVOKE_AND_COLLECT_STATISTICS(get_current_block_interval_in_seconds);
      }
  
  #undef INVOKE_AND_COLLECT_STATISTICS
  
    } // end namespace detail
  
  } } // end namespace graphene::net
  