text: /**
   *    Copyright (C) 2015 MongoDB Inc.
   *
   *    This program is free software: you can redistribute it and/or  modify
   *    it under the terms of the GNU Affero General Public License, version 3,
   *    as published by the Free Software Foundation.
   *
   *    This program is distributed in the hope that it will be useful,
   *    but WITHOUT ANY WARRANTY; without even the implied warranty of
   *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *    GNU Affero General Public License for more details.
   *
   *    You should have received a copy of the GNU Affero General Public License
   *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
   *
   *    As a special exception, the copyright holders give permission to link the
   *    code of portions of this program with the OpenSSL library under certain
   *    conditions as described in each individual source file and distribute
   *    linked combinations including the program with the OpenSSL library. You
   *    must comply with the GNU Affero General Public License in all respects
   *    for all of the code used other than as permitted herein. If you modify
   *    file(s) with this exception, you may extend this exception to your
   *    version of the file(s), but you are not obligated to do so. If you do not
   *    wish to do so, delete this exception statement from your version. If you
   *    delete this exception statement from all source files in the program,
   *    then also delete it in the license file.
   */
  
  #define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kSharding
  
  #include "mongo/platform/basic.h"
  
  #include "mongo/db/s/sharded_connection_info.h"
  
  #include <boost/optional.hpp>
  #include <boost/utility/in_place_factory.hpp>
  
  #include "mongo/client/global_conn_pool.h"
  #include "mongo/db/client.h"
  #include "mongo/db/operation_context.h"
  #include "mongo/db/s/sharding_connection_hook_for_mongod.h"
  #include "mongo/platform/atomic_word.h"
  #include "mongo/s/chunk_version.h"
  #include "mongo/s/client/shard_connection.h"
  #include "mongo/util/log.h"
  
  namespace mongo {
  
  namespace {
  
  const auto clientSCI = Client::declareDecoration<boost::optional<ShardedConnectionInfo>>();
  
  }  // namespace
  
  ShardedConnectionInfo::ShardedConnectionInfo() {
      _forceVersionOk = false;
  }
  
  ShardedConnectionInfo::~ShardedConnectionInfo() = default;
  
  ShardedConnectionInfo* ShardedConnectionInfo::get(Client* client, bool create) {
      auto& current = clientSCI(client);
  
      if (!current && create) {
          LOG(1) << "entering shard mode for connection";
          current = boost::in_place();
      }
  
      return current ? &current.value() : nullptr;
  }
  
  void ShardedConnectionInfo::reset(Client* client) {
      clientSCI(client) = boost::none;
  }
  
  ChunkVersion ShardedConnectionInfo::getVersion(const std::string& ns) const {
      NSVersionMap::const_iterator it = _versions.find(ns);
      if (it != _versions.end()) {
          return it->second;
      } else {
          return ChunkVersion::UNSHARDED();
      }
  }
  
  void ShardedConnectionInfo::setVersion(const std::string& ns, const ChunkVersion& version) {
      _versions[ns] = version;
  }
  
  namespace {
  stdx::mutex addHookMutex;
  AtomicUInt32 alreadyAddedHook{0};
  }  // namespace
  
  void ShardedConnectionInfo::addHook() {
      if (alreadyAddedHook.loadRelaxed()) {
          return;
      }
      stdx::lock_guard<stdx::mutex> lk{addHookMutex};
      if (alreadyAddedHook.load()) {
          return;
      }
      log() << "first cluster operation detected, adding sharding hook to enable versioning "
               "and authentication to remote servers";
  
      globalConnPool.addHook(new ShardingConnectionHookForMongod(false));
      shardConnectionPool.addHook(new ShardingConnectionHookForMongod(true));
  
      alreadyAddedHook.store(1);
  }
  
  }  // namespace mongo
  