Boost C++ Libraries

boost/log/utility/ipc/reliable_message_queue.hpp

/*
 *                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; };
#if defined(__cpp_lib_byte) && __cpp_lib_byte >= 201603
template< typename R >
struct enable_if_byte< std::byte, R > { typedef R type; };
#endif

} // 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 <tt>operation_result::aborted</tt>.
     * 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
     * <tt>operation_result::aborted</tt> 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_