text: /*
   *                Copyright Lingxi Li 2015.
   *             Copyright Andrey Semashev 2016.
   * Distributed under the Boost Software License, Version 1.0.
   *    (See accompanying file LICENSE_1_0.txt or copy at
   *          http://www.boost.org/LICENSE_1_0.txt)
   */
  /*!
   * \file   utility/ipc/reliable_message_queue.hpp
   * \author Lingxi Li
   * \author Andrey Semashev
   * \date   01.01.2016
   *
   * The header contains declaration of a reliable interprocess message queue.
   */
  
  #ifndef BOOST_LOG_UTILITY_IPC_RELIABLE_MESSAGE_QUEUE_HPP_INCLUDED_
  #define BOOST_LOG_UTILITY_IPC_RELIABLE_MESSAGE_QUEUE_HPP_INCLUDED_
  
  #include <boost/log/detail/config.hpp>
  #include <cstddef>
  #include <boost/cstdint.hpp>
  #include <boost/move/core.hpp>
  #include <boost/log/keywords/open_mode.hpp>
  #include <boost/log/keywords/name.hpp>
  #include <boost/log/keywords/capacity.hpp>
  #include <boost/log/keywords/block_size.hpp>
  #include <boost/log/keywords/overflow_policy.hpp>
  #include <boost/log/keywords/permissions.hpp>
  #include <boost/log/utility/open_mode.hpp>
  #include <boost/log/utility/permissions.hpp>
  #include <boost/log/utility/ipc/object_name.hpp>
  #include <boost/log/detail/parameter_tools.hpp>
  #include <boost/log/detail/header.hpp>
  
  #ifdef BOOST_HAS_PRAGMA_ONCE
  #pragma once
  #endif
  
  namespace boost {
  
  BOOST_LOG_OPEN_NAMESPACE
  
  namespace ipc {
  
  namespace aux {
  
  template< typename T, typename R >
  struct enable_if_byte {};
  template< typename R >
  struct enable_if_byte< char, R > { typedef R type; };
  template< typename R >
  struct enable_if_byte< signed char, R > { typedef R type; };
  template< typename R >
  struct enable_if_byte< unsigned char, R > { typedef R type; };
  
  } // namespace aux
  
  /*!
   * \brief A reliable interprocess message queue
   *
   * The queue implements a reliable one-way channel of passing messages from one or multiple writers to a single reader.
   * The format of the messages is user-defined and must be consistent across all writers and the reader. The queue does
   * not enforce any specific format of the messages, other than they should be supplied as a contiguous array of bytes.
   *
   * The queue internally uses a process-shared storage identified by an \c object_name (the queue name). Refer to \c object_name
   * documentation for details on restrictions imposed on object names.
   *
   * The queue storage is organized as a fixed number of blocks of a fixed size. The block size must be an integer power of 2 and
   * is expressed in bytes. Each written message, together with some metadata added by the queue, consumes an integer number
   * of blocks. Each read message received by the reader releases the blocks allocated for that message. As such the maximum size
   * of a message is slightly less than block size times capacity of the queue. For efficiency, it is recommended to choose
   * block size large enough to accommodate most of the messages to be passed through the queue.
   *
   * The queue is considered empty when no messages are enqueued (all blocks are free). The queue is considered full at the point
   * of enqueueing a message when there is not enough free blocks to accommodate the message.
   *
   * The queue is reliable in that it will not drop successfully sent messages that are not received by the reader, other than the
   * case when a non-empty queue is destroyed by the last user. If a message cannot be enqueued by the writer because the queue is
   * full, the queue can either block the writer or return an error or throw an exception, depending on the policy specified at
   * the queue creation. The policy is object local, i.e. different writers and the reader can have different overflow policies.
   *
   * If the queue is empty and the reader attempts to dequeue a message, it will block until a message is enqueued by a writer.
   *
   * A blocked reader or writer can be unblocked by calling \c stop_local. After this method is called, all threads blocked on
   * this particular object are released and return \c operation_result::aborted. The other instances of the queue (in the current
   * or other processes) are unaffected. In order to restore the normal functioning of the queue instance after the \c stop_local
   * call the user has to invoke \c reset_local.
   *
   * The queue does not guarantee any particular order of received messages from different writer threads. Messages sent by a
   * particular writer thread will be received in the order of sending.
   *
   * Methods of this class are not thread-safe, unless otherwise specified.
   */
  class reliable_message_queue
  {
  public:
      //! Result codes for various operations on the queue
      enum operation_result
      {
          succeeded,    //!< The operation has completed successfully
          no_space,     //!< The message could not be sent because the queue is full
          aborted       //!< The operation has been aborted because the queue method <tt>stop_local()</tt> has been called
      };
  
      //! Interprocess queue overflow policies
      enum overflow_policy
      {
          //! Block the send operation when the queue is full
          block_on_overflow,
          //! Return \c operation_result::no_space when the queue is full
          fail_on_overflow,
          //! Throw \c capacity_limit_reached exception when the queue is full
          throw_on_overflow
      };
  
      //! Queue message size type
      typedef uint32_t size_type;
  
  #if !defined(BOOST_LOG_DOXYGEN_PASS)
  
      BOOST_MOVABLE_BUT_NOT_COPYABLE(reliable_message_queue)
  
  private:
      typedef void (*receive_handler)(void* state, const void* data, size_type size);
  
      struct fixed_buffer_state
      {
          uint8_t* data;
          size_type size;
      };
  
      struct implementation;
      implementation* m_impl;
  
  #endif // !defined(BOOST_LOG_DOXYGEN_PASS)
  
  public:
      /*!
       * Default constructor. The method constructs an object that is not associated with any
       * message queue.
       *
       * \post <tt>is_open() == false</tt>
       */
      BOOST_CONSTEXPR reliable_message_queue() BOOST_NOEXCEPT : m_impl(NULL)
      {
      }
  
      /*!
       * Constructor. The method is used to construct an object and create the associated
       * message queue. The constructed object will be in running state if the message queue is
       * successfully created.
       *
       * \post <tt>is_open() == true</tt>
       *
       * \param name Name of the message queue to be associated with.
       * \param capacity Maximum number of allocation blocks the queue can hold.
       * \param block_size Size in bytes of allocation block. Must be a power of 2.
       * \param oflow_policy Queue behavior policy in case of overflow.
       * \param perms Access permissions for the associated message queue.
       */
      reliable_message_queue
      (
          open_mode::create_only_tag,
          object_name const& name,
          uint32_t capacity,
          size_type block_size,
          overflow_policy oflow_policy = block_on_overflow,
          permissions const& perms = permissions()
      ) :
          m_impl(NULL)
      {
          this->create(name, capacity, block_size, oflow_policy, perms);
      }
  
      /*!
       * Constructor. The method is used to construct an object and create or open the associated
       * message queue. The constructed object will be in running state if the message queue is
       * successfully created or opened. If the message queue that is identified by the name already
       * exists then the other queue parameters are ignored. The actual queue parameters can be obtained
       * with accessors from the constructed object.
       *
       * \post <tt>is_open() == true</tt>
       *
       * \param name Name of the message queue to be associated with.
       * \param capacity Maximum number of allocation blocks the queue can hold.
       * \param block_size Size in bytes of allocation block. Must be a power of 2.
       * \param oflow_policy Queue behavior policy in case of overflow.
       * \param perms Access permissions for the associated message queue.
       */
      reliable_message_queue
      (
          open_mode::open_or_create_tag,
          object_name const& name,
          uint32_t capacity,
          size_type block_size,
          overflow_policy oflow_policy = block_on_overflow,
          permissions const& perms = permissions()
      ) :
          m_impl(NULL)
      {
          this->open_or_create(name, capacity, block_size, oflow_policy, perms);
      }
  
      /*!
       * Constructor. The method is used to construct an object and open the existing
       * message queue. The constructed object will be in running state if the message queue is
       * successfully opened.
       *
       * \post <tt>is_open() == true</tt>
       *
       * \param name Name of the message queue to be associated with.
       * \param oflow_policy Queue behavior policy in case of overflow.
       * \param perms Access permissions for the associated message queue. The permissions will only be used
       *              if the queue implementation has to create system objects while operating.
       *              This parameter is currently not used on POSIX systems.
       */
      reliable_message_queue
      (
          open_mode::open_only_tag,
          object_name const& name,
          overflow_policy oflow_policy = block_on_overflow,
          permissions const& perms = permissions()
      ) :
          m_impl(NULL)
      {
          this->open(name, oflow_policy, perms);
      }
  
      /*!
       * Constructor with named parameters. The method is used to construct an object and create or open
       * the associated message queue. The constructed object will be in running state if the message queue is
       * successfully created.
       *
       * The following named parameters are accepted:
       *
       * * open_mode - One of the open mode tags: \c open_mode::create_only, \c open_mode::open_only or
       *               \c open_mode::open_or_create.
       * * name - Name of the message queue to be associated with.
       * * capacity - Maximum number of allocation blocks the queue can hold. Used only if the queue is created.
       * * block_size - Size in bytes of allocation block. Must be a power of 2. Used only if the queue is created.
       * * overflow_policy - Queue behavior policy in case of overflow, see \c overflow_policy.
       * * permissions - Access permissions for the associated message queue.
       *
       * \post <tt>is_open() == true</tt>
       */
  #if !defined(BOOST_LOG_DOXYGEN_PASS)
      BOOST_LOG_PARAMETRIZED_CONSTRUCTORS_CALL(reliable_message_queue, construct)
  #else
      template< typename... Args >
      explicit reliable_message_queue(Args const&... args);
  #endif
  
      /*!
       * Destructor. Calls <tt>close()</tt>.
       */
      ~reliable_message_queue() BOOST_NOEXCEPT
      {
          this->close();
      }
  
      /*!
       * Move constructor. The method move-constructs an object from \c other. After
       * the call, the constructed object becomes \c other, while \c other is left in
       * default constructed state.
       *
       * \param that The object to be moved.
       */
      reliable_message_queue(BOOST_RV_REF(reliable_message_queue) that) BOOST_NOEXCEPT :
          m_impl(that.m_impl)
      {
          that.m_impl = NULL;
      }
  
      /*!
       * Move assignment operator. If the object is associated with a message queue,
       * <tt>close()</tt> is first called and the precondition to calling <tt>close()</tt>
       * applies. After the call, the object becomes \a that while \a that is left
       * in default constructed state.
       *
       * \param that The object to be moved.
       *
       * \return A reference to the assigned object.
       */
      reliable_message_queue& operator= (BOOST_RV_REF(reliable_message_queue) that) BOOST_NOEXCEPT
      {
          reliable_message_queue other(static_cast< BOOST_RV_REF(reliable_message_queue) >(that));
          this->swap(other);
          return *this;
      }
  
      /*!
       * The method swaps the object with \a that.
       *
       * \param that The other object to swap with.
       */
      void swap(reliable_message_queue& that) BOOST_NOEXCEPT
      {
          implementation* p = m_impl;
          m_impl = that.m_impl;
          that.m_impl = p;
      }
  
      //! Swaps the two \c reliable_message_queue objects.
      friend void swap(reliable_message_queue& a, reliable_message_queue& b) BOOST_NOEXCEPT
      {
          a.swap(b);
      }
  
      /*!
       * The method creates the message queue to be associated with the object. After the call,
       * the object will be in running state if a message queue is successfully created.
       *
       * \pre <tt>is_open() == false</tt>
       * \post <tt>is_open() == true</tt>
       *
       * \param name Name of the message queue to be associated with.
       * \param capacity Maximum number of allocation blocks the queue can hold.
       * \param block_size Size in bytes of allocation block. Must be a power of 2.
       * \param oflow_policy Queue behavior policy in case of overflow.
       * \param perms Access permissions for the associated message queue.
       */
      BOOST_LOG_API void create
      (
          object_name const& name,
          uint32_t capacity,
          size_type block_size,
          overflow_policy oflow_policy = block_on_overflow,
          permissions const& perms = permissions()
      );
  
      /*!
       * The method creates or opens the message queue to be associated with the object.
       * After the call, the object will be in running state if a message queue is successfully
       * created or opened. If the message queue that is identified by the name already exists then
       * the other queue parameters are ignored. The actual queue parameters can be obtained
       * with accessors from this object after this method returns.
       *
       * \pre <tt>is_open() == false</tt>
       * \post <tt>is_open() == true</tt>
       *
       * \param name Name of the message queue to be associated with.
       * \param capacity Maximum number of allocation blocks the queue can hold.
       * \param block_size Size in bytes of allocation block. Must be a power of 2.
       * \param oflow_policy Queue behavior policy in case of overflow.
       * \param perms Access permissions for the associated message queue.
       */
      BOOST_LOG_API void open_or_create
      (
          object_name const& name,
          uint32_t capacity,
          size_type block_size,
          overflow_policy oflow_policy = block_on_overflow,
          permissions const& perms = permissions()
      );
  
      /*!
       * The method opens the existing message queue to be associated with the object.
       * After the call, the object will be in running state if a message queue is successfully
       * opened.
       *
       * \pre <tt>is_open() == false</tt>
       * \post <tt>is_open() == true</tt>
       *
       * \param name Name of the message queue to be associated with.
       * \param oflow_policy Queue behavior policy in case of overflow.
       * \param perms Access permissions for the associated message queue. The permissions will only be used
       *              if the queue implementation has to create system objects while operating.
       *              This parameter is currently not used on POSIX systems.
       */
      BOOST_LOG_API void open
      (
          object_name const& name,
          overflow_policy oflow_policy = block_on_overflow,
          permissions const& perms = permissions()
      );
  
      /*!
       * Tests whether the object is associated with any message queue.
       *
       * \return \c true if the object is associated with a message queue, and \c false otherwise.
       */
      bool is_open() const BOOST_NOEXCEPT
      {
          return m_impl != NULL;
      }
  
      /*!
       * This method empties the associated message queue. Concurrent calls to this method, <tt>send()</tt>,
       * <tt>try_send()</tt>, <tt>receive()</tt>, <tt>try_receive()</tt>, and <tt>stop_local()</tt> are allowed.
       *
       * \pre <tt>is_open() == true</tt>
       */
      BOOST_LOG_API void clear();
  
      /*!
       * The method returns the name of the associated message queue.
       *
       * \pre <tt>is_open() == true</tt>
       *
       * \return Name of the associated message queue
       */
      BOOST_LOG_API object_name const& name() const;
  
      /*!
       * The method returns the maximum number of allocation blocks the associated message queue
       * can hold. Note that the returned value may be different from the corresponding
       * value passed to the constructor or <tt>open_or_create()</tt>, for the message queue may
       * not have been created by this object.
       *
       * \pre <tt>is_open() == true</tt>
       *
       * \return Maximum number of allocation blocks the associated message queue can hold.
       */
      BOOST_LOG_API uint32_t capacity() const;
  
      /*!
       * The method returns the allocation block size, in bytes. Each message in the
       * associated message queue consumes an integer number of allocation blocks.
       * Note that the returned value may be different from the corresponding value passed
       * to the constructor or <tt>open_or_create()</tt>, for the message queue may not
       * have been created by this object.
       *
       * \pre <tt>is_open() == true</tt>
       *
       * \return Allocation block size, in bytes.
       */
      BOOST_LOG_API size_type block_size() const;
  
      /*!
       * The method wakes up all threads that are blocked in calls to <tt>send()</tt> or
       * <tt>receive()</tt>. Those calls would then return \c false with \c errno \c EINTR.
       * Note that, the method does not block until the woken-up threads have actually
       * returned from <tt>send()</tt> or <tt>receive()</tt>. Other means is needed to ensure
       * that calls to <tt>send()</tt> or <tt>receive()</tt> have returned, e.g., joining the
       * threads that might be blocking on the calls.
       *
       * The method also puts the object in stopped state. When in stopped state, calls to
       * <tt>send()</tt> or <tt>receive()</tt> will return immediately with return value
       * \c false and \c errno \c EINTR when they would otherwise block in running state.
       *
       * Concurrent calls to this method, <tt>send()</tt>, <tt>try_send()</tt>, <tt>receive()</tt>,
       * <tt>try_receive()</tt>, and <tt>clear()</tt> are allowed.
       *
       * \pre <tt>is_open() == true</tt>
       */
      BOOST_LOG_API void stop_local();
  
      /*!
       * The method puts the object in running state where calls to <tt>send()</tt> or
       * <tt>receive()</tt> may block. This method is not thread-safe.
       *
       * \pre <tt>is_open() == true</tt>
       */
      BOOST_LOG_API void reset_local();
  
      /*!
       * The method disassociates the associated message queue, if any. No other threads
       * should be using this object before calling this method. The <tt>stop_local()</tt> method
       * can be used to have any threads currently blocked in <tt>send()</tt> or
       * <tt>receive()</tt> return, and prevent further calls to them from blocking. Typically,
       * before calling this method, one would first call <tt>stop_local()</tt> and then join all
       * threads that might be blocking on <tt>send()</tt> or <tt>receive()</tt> to ensure that
       * they have returned from the calls. The associated message queue is destroyed if the
       * object represents the last outstanding reference to it.
       *
       * \post <tt>is_open() == false</tt>
       */
      void close() BOOST_NOEXCEPT
      {
          if (is_open())
              do_close();
      }
  
      /*!
       * The method sends a message to the associated message queue. When the object is in
       * running state and the queue has no free space for the message, the method either blocks
       * or throws an exception, depending on the overflow policy that was specified on the queue
       * opening/creation. If blocking policy is in effect, the blocking can be interrupted by
       * calling <tt>stop_local()</tt>, in which case the method returns \c operation_result::aborted.
       * When the object is already in the stopped state, the method does not block but returns
       * immediately with return value \c operation_result::aborted.
       *
       * It is possible to send an empty message by passing \c 0 to the parameter \c message_size.
       *
       * Concurrent calls to <tt>send()</tt>, <tt>try_send()</tt>, <tt>receive()</tt>, <tt>try_receive()</tt>,
       * <tt>stop_local()</tt>, and <tt>clear()</tt> are allowed.
       *
       * \pre <tt>is_open() == true</tt>
       *
       * \param message_data The message data to send. Ignored when \c message_size is \c 0.
       * \param message_size Size of the message data in bytes. If the size is larger than
       *                     the associated message queue capacity, an <tt>std::logic_error</tt> exception is thrown.
       *
       * \retval operation_result::succeeded if the operation is successful
       * \retval operation_result::no_space if \c overflow_policy::fail_on_overflow is in effect and the queue is full
       * \retval operation_result::aborted if the call was interrupted by <tt>stop_local()</tt>
       *
       * <b>Throws:</b> <tt>std::logic_error</tt> in case if the message size exceeds the queue
       *                capacity, <tt>system_error</tt> in case if a native OS method fails.
       */
      BOOST_LOG_API operation_result send(void const* message_data, size_type message_size);
  
      /*!
       * The method performs an attempt to send a message to the associated message queue.
       * The method is non-blocking, and always returns immediately.
       * <tt>boost::system::system_error</tt> is thrown for errors resulting from native
       * operating system calls. Note that it is possible to send an empty message by passing
       * \c 0 to the parameter \c message_size. Concurrent calls to <tt>send()</tt>,
       * <tt>try_send()</tt>, <tt>receive()</tt>, <tt>try_receive()</tt>, <tt>stop_local()</tt>,
       * and <tt>clear()</tt> are allowed.
       *
       * \pre <tt>is_open() == true</tt>
       *
       * \param message_data The message data to send. Ignored when \c message_size is \c 0.
       * \param message_size Size of the message data in bytes. If the size is larger than the
       *                     maximum size allowed by the associated message queue, an
       *                     <tt>std::logic_error</tt> exception is thrown.
       *
       * \return \c true if the message is successfully sent, and \c false otherwise (e.g.,
       *         when the queue is full).
       *
       * <b>Throws:</b> <tt>std::logic_error</tt> in case if the message size exceeds the queue
       *                capacity, <tt>system_error</tt> in case if a native OS method fails.
       */
      BOOST_LOG_API bool try_send(void const* message_data, size_type message_size);
  
      /*!
       * The method takes a message from the associated message queue. When the object is in
       * running state and the queue is empty, the method blocks. The blocking is interrupted
       * when <tt>stop_local()</tt> is called, in which case the method returns \c operation_result::aborted.
       * When the object is already in the stopped state and the queue is empty, the method
       * does not block but returns immediately with return value \c operation_result::aborted.
       *
       * Concurrent calls to <tt>send()</tt>, <tt>try_send()</tt>, <tt>receive()</tt>,
       * <tt>try_receive()</tt>, <tt>stop_local()</tt>, and <tt>clear()</tt> are allowed.
       *
       * \pre <tt>is_open() == true</tt>
       *
       * \param buffer The memory buffer to store the received message in.
       * \param buffer_size The size of the buffer, in bytes.
       * \param message_size Receives the size of the received message, in bytes.
       *
       * \retval operation_result::succeeded if the operation is successful
       * \retval operation_result::aborted if the call was interrupted by <tt>stop_local()</tt>
       */
      operation_result receive(void* buffer, size_type buffer_size, size_type& message_size)
      {
          fixed_buffer_state state = { static_cast< uint8_t* >(buffer), buffer_size };
          operation_result result = do_receive(&reliable_message_queue::fixed_buffer_receive_handler, &state);
          message_size = buffer_size - state.size;
          return result;
      }
  
      /*!
       * The method takes a message from the associated message queue. When the object is in
       * running state and the queue is empty, the method blocks. The blocking is interrupted
       * when <tt>stop_local()</tt> is called, in which case the method returns \c operation_result::aborted.
       * When the object is already in the stopped state and the queue is empty, the method
       * does not block but returns immediately with return value \c operation_result::aborted.
       *
       * Concurrent calls to <tt>send()</tt>, <tt>try_send()</tt>, <tt>receive()</tt>,
       * <tt>try_receive()</tt>, <tt>stop_local()</tt>, and <tt>clear()</tt> are allowed.
       *
       * \pre <tt>is_open() == true</tt>
       *
       * \param buffer The memory buffer to store the received message in.
       * \param message_size Receives the size of the received message, in bytes.
       *
       * \retval operation_result::succeeded if the operation is successful
       * \retval operation_result::aborted if the call was interrupted by <tt>stop_local()</tt>
       */
      template< typename ElementT, size_type SizeV >
  #if !defined(BOOST_LOG_DOXYGEN_PASS)
      typename aux::enable_if_byte< ElementT, operation_result >::type
  #else
      operation_result
  #endif
      receive(ElementT (&buffer)[SizeV], size_type& message_size)
      {
          return receive(buffer, SizeV, message_size);
      }
  
      /*!
       * The method takes a message from the associated message queue. When the object is in
       * running state and the queue is empty, the method blocks. The blocking is interrupted
       * when <tt>stop_local()</tt> is called, in which case the method returns \c operation_result::aborted.
       * When the object is already in the stopped state and the queue is empty, the method
       * does not block but returns immediately with return value \c operation_result::aborted.
       *
       * Concurrent calls to <tt>send()</tt>, <tt>try_send()</tt>, <tt>receive()</tt>,
       * <tt>try_receive()</tt>, <tt>stop_local()</tt>, and <tt>clear()</tt> are allowed.
       *
       * \pre <tt>is_open() == true</tt>
       *
       * \param container The container to store the received message in. The container should have
       *                  value type of <tt>char</tt>, <tt>signed char</tt> or <tt>unsigned char</tt>
       *                  and support inserting elements at the end.
       *
       * \retval operation_result::succeeded if the operation is successful
       * \retval operation_result::aborted if the call was interrupted by <tt>stop_local()</tt>
       */
      template< typename ContainerT >
  #if !defined(BOOST_LOG_DOXYGEN_PASS)
      typename aux::enable_if_byte< typename ContainerT::value_type, operation_result >::type
  #else
      operation_result
  #endif
      receive(ContainerT& container)
      {
          return do_receive(&reliable_message_queue::container_receive_handler< ContainerT >, &container);
      }
  
      /*!
       * The method performs an attempt to take a message from the associated message queue. The
       * method is non-blocking, and always returns immediately.
       *
       * Concurrent calls to <tt>send()</tt>, <tt>try_send()</tt>, <tt>receive()</tt>,
       * <tt>try_receive()</tt>, <tt>stop_local()</tt>, and <tt>clear()</tt> are allowed.
       *
       * \pre <tt>is_open() == true</tt>
       *
       * \param buffer The memory buffer to store the received message in.
       * \param buffer_size The size of the buffer, in bytes.
       * \param message_size Receives the size of the received message, in bytes.
       *
       * \return \c true if a message is successfully received, and \c false otherwise (e.g.,
       *         when the queue is empty).
       */
      bool try_receive(void* buffer, size_type buffer_size, size_type& message_size)
      {
          fixed_buffer_state state = { static_cast< uint8_t* >(buffer), buffer_size };
          bool result = do_try_receive(&reliable_message_queue::fixed_buffer_receive_handler, &state);
          message_size = buffer_size - state.size;
          return result;
      }
  
      /*!
       * The method performs an attempt to take a message from the associated message queue. The
       * method is non-blocking, and always returns immediately.
       *
       * Concurrent calls to <tt>send()</tt>, <tt>try_send()</tt>, <tt>receive()</tt>,
       * <tt>try_receive()</tt>, <tt>stop_local()</tt>, and <tt>clear()</tt> are allowed.
       *
       * \pre <tt>is_open() == true</tt>
       *
       * \param buffer The memory buffer to store the received message in.
       * \param message_size Receives the size of the received message, in bytes.
       *
       * \return \c true if a message is successfully received, and \c false otherwise (e.g.,
       *         when the queue is empty).
       */
      template< typename ElementT, size_type SizeV >
  #if !defined(BOOST_LOG_DOXYGEN_PASS)
      typename aux::enable_if_byte< ElementT, bool >::type
  #else
      bool
  #endif
      try_receive(ElementT (&buffer)[SizeV], size_type& message_size)
      {
          return try_receive(buffer, SizeV, message_size);
      }
  
      /*!
       * The method performs an attempt to take a message from the associated message queue. The
       * method is non-blocking, and always returns immediately.
       *
       * Concurrent calls to <tt>send()</tt>, <tt>try_send()</tt>, <tt>receive()</tt>,
       * <tt>try_receive()</tt>, <tt>stop_local()</tt>, and <tt>clear()</tt> are allowed.
       *
       * \pre <tt>is_open() == true</tt>
       *
       * \param container The container to store the received message in. The container should have
       *                  value type of <tt>char</tt>, <tt>signed char</tt> or <tt>unsigned char</tt>
       *                  and support inserting elements at the end.
       *
       * \return \c true if a message is successfully received, and \c false otherwise (e.g.,
       *         when the queue is empty).
       */
      template< typename ContainerT >
  #if !defined(BOOST_LOG_DOXYGEN_PASS)
      typename aux::enable_if_byte< typename ContainerT::value_type, bool >::type
  #else
      bool
  #endif
      try_receive(ContainerT& container)
      {
          return do_try_receive(&reliable_message_queue::container_receive_handler< ContainerT >, &container);
      }
  
      /*!
       * The method frees system-wide resources, associated with the interprocess queue with the supplied name.
       * The queue referred to by the specified name must not be opened in any process at the point of this call.
       * After this call succeeds a new queue with the specified name can be created.
       *
       * This call can be useful to recover from an earlier process misbehavior (e.g. a crash without properly
       * closing the message queue). In this case resources allocated for the interprocess queue may remain
       * allocated after the last process closed the queue, which in turn may prevent creating a new queue with
       * the same name. By calling this method before creating a queue the application can attempt to ensure
       * it starts with a clean slate.
       *
       * On some platforms resources associated with the queue are automatically reclaimed by the operating system
       * when the last process using those resources terminates (even if it terminates abnormally). On these
       * platforms this call may be a no-op. However, portable code should still call this method at appropriate
       * places to ensure compatibility with other platforms and future library versions, which may change implementation
       * of the queue.
       *
       * \param name Name of the message queue to be removed.
       */
      static BOOST_LOG_API void remove(object_name const& name);
  
  #if !defined(BOOST_LOG_DOXYGEN_PASS)
  private:
      //! Implementation of the constructor with named arguments
      template< typename ArgsT >
      void construct(ArgsT const& args)
      {
          m_impl = NULL;
          construct_dispatch(args[keywords::open_mode], args);
      }
  
      //! Implementation of the constructor with named arguments
      template< typename ArgsT >
      void construct_dispatch(open_mode::create_only_tag, ArgsT const& args)
      {
          this->create(args[keywords::name], args[keywords::capacity], args[keywords::block_size], args[keywords::overflow_policy | block_on_overflow], args[keywords::permissions | permissions()]);
      }
  
      //! Implementation of the constructor with named arguments
      template< typename ArgsT >
      void construct_dispatch(open_mode::open_or_create_tag, ArgsT const& args)
      {
          this->open_or_create(args[keywords::name], args[keywords::capacity], args[keywords::block_size], args[keywords::overflow_policy | block_on_overflow], args[keywords::permissions | permissions()]);
      }
  
      //! Implementation of the constructor with named arguments
      template< typename ArgsT >
      void construct_dispatch(open_mode::open_only_tag, ArgsT const& args)
      {
          this->open(args[keywords::name], args[keywords::overflow_policy | block_on_overflow], args[keywords::permissions | permissions()]);
      }
  
      //! Closes the message queue, if it's open
      BOOST_LOG_API void do_close() BOOST_NOEXCEPT;
  
      //! Receives the message from the queue and calls the handler to place the data in the user's storage
      BOOST_LOG_API operation_result do_receive(receive_handler handler, void* state);
      //! Attempts to receives the message from the queue and calls the handler to place the data in the user's storage
      BOOST_LOG_API bool do_try_receive(receive_handler handler, void* state);
  
      //! Fixed buffer receive handler
      static BOOST_LOG_API void fixed_buffer_receive_handler(void* state, const void* data, size_type size);
      //! Receive handler for a container
      template< typename ContainerT >
      static void container_receive_handler(void* state, const void* data, size_type size)
      {
          ContainerT* const container = static_cast< ContainerT* >(state);
          container->insert
          (
              container->end(),
              static_cast< typename ContainerT::value_type const* >(data),
              static_cast< typename ContainerT::value_type const* >(data) + size
          );
      }
  #endif
  };
  
  } // namespace ipc
  
  BOOST_LOG_CLOSE_NAMESPACE // namespace log
  
  } // namespace boost
  
  #include <boost/log/detail/footer.hpp>
  
  #endif // BOOST_LOG_UTILITY_IPC_RELIABLE_MESSAGE_QUEUE_HPP_INCLUDED_
  