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 //////////////////////////////////////////////////////////////////////////////
 //
 // (C) Copyright Ion Gaztanaga 2005-2012. 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)
 //
 // See http://www.boost.org/libs/interprocess for documentation.
 //
 //////////////////////////////////////////////////////////////////////////////
 
 #ifndef BOOST_INTERPROCESS_MESSAGE_QUEUE_HPP
 #define BOOST_INTERPROCESS_MESSAGE_QUEUE_HPP
 
 #ifndef BOOST_CONFIG_HPP
 #  include <boost/config.hpp>
 #endif
 #
 #if defined(BOOST_HAS_PRAGMA_ONCE)
 #  pragma once
 #endif
 
 #include <boost/interprocess/detail/config_begin.hpp>
 #include <boost/interprocess/detail/workaround.hpp>
 
 #include <boost/interprocess/shared_memory_object.hpp>
 #include <boost/interprocess/detail/managed_open_or_create_impl.hpp>
 #include <boost/interprocess/sync/interprocess_condition.hpp>
 #include <boost/interprocess/sync/interprocess_mutex.hpp>
 #include <boost/interprocess/sync/scoped_lock.hpp>
 #include <boost/interprocess/detail/utilities.hpp>
 #include <boost/interprocess/timed_utils.hpp>
 #include <boost/interprocess/offset_ptr.hpp>
 #include <boost/interprocess/creation_tags.hpp>
 #include <boost/interprocess/exceptions.hpp>
 #include <boost/interprocess/permissions.hpp>
 #include <boost/interprocess/detail/type_traits.hpp>
 #include <boost/intrusive/pointer_traits.hpp>
 #include <boost/move/detail/type_traits.hpp> //make_unsigned, alignment_of
 #include <boost/intrusive/pointer_traits.hpp>
 #include <boost/move/detail/force_ptr.hpp>
 #include <boost/assert.hpp>
 #include <algorithm> //std::lower_bound
 #include <cstddef>   //std::size_t
 #include <cstring>   //memcpy
 
 
 //!\file
 //!Describes an inter-process message queue. This class allows sending
 //!messages between processes and allows blocking, non-blocking and timed
 //!sending and receiving.
 
 namespace boost{  namespace interprocess{
 
 namespace ipcdetail
 {
    template<class VoidPointer>
    class msg_queue_initialization_func_t;
 
 }
 
 //Blocking modes
 enum mqblock_types   {  blocking,   timed,   non_blocking   };
 
 //!A class that allows sending messages
 //!between processes.
 template<class VoidPointer>
 class message_queue_t
 {
    #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
 
    message_queue_t();
    #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
 
    public:
    typedef VoidPointer                                                 void_pointer;
    typedef typename boost::intrusive::
       pointer_traits<void_pointer>::template
          rebind_pointer<char>::type                                    char_ptr;
    typedef typename boost::intrusive::pointer_traits<char_ptr>::difference_type difference_type;
    typedef typename boost::container::dtl::make_unsigned<difference_type>::type        size_type;
 
    //!Creates a process shared message queue with name "name". For this message queue,
    //!the maximum number of messages will be "max_num_msg" and the maximum message size
    //!will be "max_msg_size". Throws on error and if the queue was previously created.
    message_queue_t(create_only_t,
                  const char *name,
                  size_type max_num_msg,
                  size_type max_msg_size,
                  const permissions &perm = permissions());
 
    //!Opens or creates a process shared message queue with name "name".
    //!If the queue is created, the maximum number of messages will be "max_num_msg"
    //!and the maximum message size will be "max_msg_size". If queue was previously
    //!created the queue will be opened and "max_num_msg" and "max_msg_size" parameters
    //!are ignored. Throws on error.
    message_queue_t(open_or_create_t,
                  const char *name,
                  size_type max_num_msg,
                  size_type max_msg_size,
                  const permissions &perm = permissions());
 
    //!Opens a previously created process shared message queue with name "name".
    //!If the queue was not previously created or there are no free resources,
    //!throws an error.
    message_queue_t(open_only_t, const char *name);
 
    #if defined(BOOST_INTERPROCESS_WCHAR_NAMED_RESOURCES) || defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
 
    //!Creates a process shared message queue with name "name". For this message queue,
    //!the maximum number of messages will be "max_num_msg" and the maximum message size
    //!will be "max_msg_size". Throws on error and if the queue was previously created.
    //! 
    //!Note: This function is only available on operating systems with
    //!      native wchar_t APIs (e.g. Windows).
    message_queue_t(create_only_t,
                  const wchar_t *name,
                  size_type max_num_msg,
                  size_type max_msg_size,
                  const permissions &perm = permissions());
 
    //!Opens or creates a process shared message queue with name "name".
    //!If the queue is created, the maximum number of messages will be "max_num_msg"
    //!and the maximum message size will be "max_msg_size". If queue was previously
    //!created the queue will be opened and "max_num_msg" and "max_msg_size" parameters
    //!are ignored. Throws on error.
    //! 
    //!Note: This function is only available on operating systems with
    //!      native wchar_t APIs (e.g. Windows).
    message_queue_t(open_or_create_t,
                  const wchar_t *name,
                  size_type max_num_msg,
                  size_type max_msg_size,
                  const permissions &perm = permissions());
 
    //!Opens a previously created process shared message queue with name "name".
    //!If the queue was not previously created or there are no free resources,
    //!throws an error.
    //! 
    //!Note: This function is only available on operating systems with
    //!      native wchar_t APIs (e.g. Windows).
    message_queue_t(open_only_t, const wchar_t *name);
 
    #endif //defined(BOOST_INTERPROCESS_WCHAR_NAMED_RESOURCES) || defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
 
    //!Creates a process shared message queue in anonymous memory. For this message queue,
    //!the maximum number of messages will be "max_num_msg" and the maximum message size
    //!will be "max_msg_size". Throws on error.
    message_queue_t(size_type max_num_msg,
                  size_type max_msg_size);
 
    //!Destroys *this and indicates that the calling process is finished using
    //!the resource. All opened message queues are still
    //!valid after destruction. The destructor function will deallocate
    //!any system resources allocated by the system for use by this process for
    //!this resource. The resource can still be opened again calling
    //!the open constructor overload. To erase the message queue from the system
    //!use remove().
    ~message_queue_t();
 
    //!Sends a message stored in buffer "buffer" with size "buffer_size" in the
    //!message queue with priority "priority". If the message queue is full
    //!the sender is blocked. Throws interprocess_error on error.
    void send (const void *buffer,     size_type buffer_size,
               unsigned int priority);
 
    //!Sends a message stored in buffer "buffer" with size "buffer_size" through the
    //!message queue with priority "priority". If the message queue is full
    //!the sender is not blocked and returns false, otherwise returns true.
    //!Throws interprocess_error on error.
    bool try_send    (const void *buffer,     size_type buffer_size,
                          unsigned int priority);
 
    //!Sends a message stored in buffer "buffer" with size "buffer_size" in the
    //!message queue with priority "priority". If the message queue is full
    //!the sender retries until time "abs_time" is reached. Returns true if
    //!the message has been successfully sent. Returns false if timeout is reached.
    //!Throws interprocess_error on error.
    template<class TimePoint>
    bool timed_send    (const void *buffer,     size_type buffer_size,
                            unsigned int priority,  const TimePoint& abs_time);
 
    //!Receives a message from the message queue. The message is stored in buffer
    //!"buffer", which has size "buffer_size". The received message has size
    //!"recvd_size" and priority "priority". If the message queue is empty
    //!the receiver is blocked. Throws interprocess_error on error.
    void receive (void *buffer,           size_type buffer_size,
                  size_type &recvd_size,unsigned int &priority);
 
    //!Receives a message from the message queue. The message is stored in buffer
    //!"buffer", which has size "buffer_size". The received message has size
    //!"recvd_size" and priority "priority". If the message queue is empty
    //!the receiver is not blocked and returns false, otherwise returns true.
    //!Throws interprocess_error on error.
    bool try_receive (void *buffer,           size_type buffer_size,
                      size_type &recvd_size,unsigned int &priority);
 
    //!Receives a message from the message queue. The message is stored in buffer
    //!"buffer", which has size "buffer_size". The received message has size
    //!"recvd_size" and priority "priority". If the message queue is empty
    //!the receiver retries until time "abs_time" is reached. Returns true if
    //!the message has been successfully sent. Returns false if timeout is reached.
    //!Throws interprocess_error on error.
    template<class TimePoint>
    bool timed_receive (void *buffer,           size_type buffer_size,
                        size_type &recvd_size,unsigned int &priority,
                        const TimePoint &abs_time);
 
    //!Returns the maximum number of messages allowed by the queue. The message
    //!queue must be opened or created previously. Otherwise, returns 0.
    //!Never throws
    size_type get_max_msg() const;
 
    //!Returns the maximum size of message allowed by the queue. The message
    //!queue must be opened or created previously. Otherwise, returns 0.
    //!Never throws
    size_type get_max_msg_size() const;
 
    //!Returns the number of messages currently stored.
    //!Never throws
    size_type get_num_msg() const;
 
    //!Removes the message queue from the system.
    //!Returns false on error. Never throws
    static bool remove(const char *name);
 
    #if defined(BOOST_INTERPROCESS_WCHAR_NAMED_RESOURCES) || defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
 
    //!Removes the message queue from the system.
    //!Returns false on error. Never throws
    //! 
    //!Note: This function is only available on operating systems with
    //!      native wchar_t APIs (e.g. Windows).
    static bool remove(const wchar_t *name);
 
    #endif
 
    #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
    private:
 
    friend class ipcdetail::msg_queue_initialization_func_t<VoidPointer>;
 
    template<mqblock_types Block, class TimePoint>
    bool do_receive(void *buffer,         size_type buffer_size,
                    size_type &recvd_size, unsigned int &priority,
                    const TimePoint &abs_time);
 
    template<mqblock_types Block, class TimePoint>
    bool do_send(const void *buffer,      size_type buffer_size,
                 unsigned int priority,   const TimePoint &abs_time);
 
    //!Returns the needed memory size for the shared message queue.
    //!Never throws
    static size_type get_mem_size(size_type max_msg_size, size_type max_num_msg);
    typedef ipcdetail::managed_open_or_create_impl<shared_memory_object, 0, true, false> open_create_impl_t;
    open_create_impl_t m_shmem;
 
    template<class Lock, class TimePoint>
    static bool do_cond_wait(ipcdetail::bool_<true>, interprocess_condition &cond, Lock &lock, const TimePoint &abs_time)
    {  return cond.timed_wait(lock, abs_time);  }
 
    template<class Lock, class TimePoint>
    static bool do_cond_wait(ipcdetail::bool_<false>, interprocess_condition &cond, Lock &lock, const TimePoint &)
    {  cond.wait(lock); return true;  }
 
    #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
 };
 
 #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
 
 namespace ipcdetail {
 
 //!This header is the prefix of each message in the queue
 template<class VoidPointer>
 class msg_hdr_t
 {
    typedef VoidPointer                                                           void_pointer;
    typedef typename boost::intrusive::
       pointer_traits<void_pointer>::template
          rebind_pointer<char>::type                                              char_ptr;
    typedef typename boost::intrusive::pointer_traits<char_ptr>::difference_type  difference_type;
    typedef typename boost::container::dtl::make_unsigned<difference_type>::type                  size_type;
 
    public:
    size_type               len;     // Message length
    unsigned int            priority;// Message priority
    //!Returns the data buffer associated with this this message
    void * data(){ return this+1; }  //
 };
 
 //!This functor is the predicate to order stored messages by priority
 template<class VoidPointer>
 class priority_functor
 {
    typedef typename boost::intrusive::
       pointer_traits<VoidPointer>::template
          rebind_pointer<msg_hdr_t<VoidPointer> >::type                  msg_hdr_ptr_t;
 
    public:
    bool operator()(const msg_hdr_ptr_t &msg1,
                    const msg_hdr_ptr_t &msg2) const
       {  return msg1->priority < msg2->priority;  }
 };
 
 //!This header is placed in the beginning of the shared memory and contains
 //!the data to control the queue. This class initializes the shared memory
 //!in the following way: in ascending memory address with proper alignment
 //!fillings:
 //!
 //!-> mq_hdr_t:
 //!   Main control block that controls the rest of the elements
 //!
 //!-> offset_ptr<msg_hdr_t> index [max_num_msg]
 //!   An array of pointers with size "max_num_msg" called index. Each pointer
 //!   points to a preallocated message. Elements of this array are
 //!   reordered in runtime in the following way:
 //!
 //!   IF BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX is defined:
 //!
 //!   When the current number of messages is "cur_num_msg", the array
 //!   is treated like a circular buffer. Starting from position "cur_first_msg"
 //!   "cur_num_msg" in a circular way, pointers point to inserted messages and the rest
 //!   point to free messages. Those "cur_num_msg" pointers are
 //!   ordered by the priority of the pointed message and by insertion order
 //!   if two messages have the same priority. So the next message to be
 //!   used in a "receive" is pointed by index [(cur_first_msg + cur_num_msg-1)%max_num_msg]
 //!   and the first free message ready to be used in a "send" operation is
 //!   [cur_first_msg] if circular buffer is extended from front,
 //!   [(cur_first_msg + cur_num_msg)%max_num_msg] otherwise.
 //!
 //!   This transforms the index in a circular buffer with an embedded free
 //!   message queue.
 //!
 //!   ELSE (BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX is NOT defined):
 //!
 //!   When the current number of messages is "cur_num_msg", the first
 //!   "cur_num_msg" pointers point to inserted messages and the rest
 //!   point to free messages. The first "cur_num_msg" pointers are
 //!   ordered by the priority of the pointed message and by insertion order
 //!   if two messages have the same priority. So the next message to be
 //!   used in a "receive" is pointed by index [cur_num_msg-1] and the first free
 //!   message ready to be used in a "send" operation is index [cur_num_msg].
 //!
 //!   This transforms the index in a fixed size priority queue with an embedded free
 //!   message queue.
 //!
 //!-> struct message_t
 //!   {
 //!      msg_hdr_t            header;
 //!      char[max_msg_size]   data;
 //!   } messages [max_num_msg];
 //!
 //!   An array of buffers of preallocated messages, each one prefixed with the
 //!   msg_hdr_t structure. Each of this message is pointed by one pointer of
 //!   the index structure.
 template<class VoidPointer>
 class mq_hdr_t
    : public ipcdetail::priority_functor<VoidPointer>
 {
    typedef VoidPointer                                                     void_pointer;
    typedef msg_hdr_t<void_pointer>                                         msg_header;
    typedef typename boost::intrusive::
       pointer_traits<void_pointer>::template
          rebind_pointer<msg_header>::type                                  msg_hdr_ptr_t;
    typedef typename boost::intrusive::pointer_traits
       <msg_hdr_ptr_t>::difference_type                                     difference_type;
    typedef typename boost::container::
       dtl::make_unsigned<difference_type>::type               size_type;
    typedef typename boost::intrusive::
       pointer_traits<void_pointer>::template
          rebind_pointer<msg_hdr_ptr_t>::type                              msg_hdr_ptr_ptr_t;
    typedef ipcdetail::managed_open_or_create_impl<shared_memory_object, 0, true, false> open_create_impl_t;
 
    public:
    //!Constructor. This object must be constructed in the beginning of the
    //!shared memory of the size returned by the function "get_mem_size".
    //!This constructor initializes the needed resources and creates
    //!the internal structures like the priority index. This can throw.
    mq_hdr_t(size_type max_num_msg, size_type max_msg_size)
       : m_max_num_msg(max_num_msg),
          m_max_msg_size(max_msg_size),
          m_cur_num_msg(0)
          #if defined(BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX)
          ,m_cur_first_msg(0u)
          ,m_blocked_senders(0u)
          ,m_blocked_receivers(0u)
          #endif
       {  this->initialize_memory();  }
 
    //!Returns true if the message queue is full
    bool is_full() const
       {  return m_cur_num_msg == m_max_num_msg;  }
 
    //!Returns true if the message queue is empty
    bool is_empty() const
       {  return !m_cur_num_msg;  }
 
    //!Frees the top priority message and saves it in the free message list
    void free_top_msg()
       {  --m_cur_num_msg;  }
 
    #if defined(BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX)
 
    typedef msg_hdr_ptr_t *iterator;
 
    size_type end_pos() const
    {
       const size_type space_until_bufend = m_max_num_msg - m_cur_first_msg;
       return space_until_bufend > m_cur_num_msg
          ? m_cur_first_msg + m_cur_num_msg : m_cur_num_msg - space_until_bufend;
    }
 
    //!Returns the inserted message with top priority
    msg_header &top_msg()
    {
       size_type pos = this->end_pos();
       return *mp_index[difference_type(pos ? --pos : m_max_num_msg - 1)];
    }
 
    //!Returns the inserted message with bottom priority
    msg_header &bottom_msg()
       {  return *mp_index[difference_type(m_cur_first_msg)];   }
 
    iterator inserted_ptr_begin() const
    {  return &mp_index[difference_type(m_cur_first_msg)]; }
 
    iterator inserted_ptr_end() const
       {  return &mp_index[difference_type(this->end_pos())];  }
 
    iterator lower_bound(const msg_hdr_ptr_t & value, priority_functor<VoidPointer> func)
    {
       iterator begin(this->inserted_ptr_begin()), end(this->inserted_ptr_end());
       if(end < begin){
          iterator idx_end = &mp_index[difference_type(m_max_num_msg)];
          iterator ret = std::lower_bound(begin, idx_end, value, func);
          if(idx_end == ret){
             iterator idx_beg = &mp_index[0];
             ret = std::lower_bound(idx_beg, end, value, func);
             //sanity check, these cases should not call lower_bound (optimized out)
             BOOST_ASSERT(ret != end);
             BOOST_ASSERT(ret != begin);
             return ret;
          }
          else{
             return ret;
          }
       }
       else{
          return std::lower_bound(begin, end, value, func);
       }
    }
 
    msg_header & insert_at(iterator where)
    {
       iterator it_inserted_ptr_end = this->inserted_ptr_end();
       iterator it_inserted_ptr_beg = this->inserted_ptr_begin();
       if(where == it_inserted_ptr_beg){
          //unsigned integer guarantees underflow
          m_cur_first_msg = m_cur_first_msg ? m_cur_first_msg : m_max_num_msg;
          --m_cur_first_msg;
          ++m_cur_num_msg;
          return *mp_index[difference_type(m_cur_first_msg)];
       }
       else if(where == it_inserted_ptr_end){
          ++m_cur_num_msg;
          return **it_inserted_ptr_end;
       }
       else{
          size_type pos  = size_type(where - &mp_index[0]);
          size_type circ_pos = pos >= m_cur_first_msg ? pos - m_cur_first_msg : pos + (m_max_num_msg - m_cur_first_msg);
          //Check if it's more efficient to move back or move front
          if(circ_pos < m_cur_num_msg/2){
             //The queue can't be full so m_cur_num_msg == 0 or m_cur_num_msg <= pos
             //indicates two step insertion
             if(!pos){
                pos   = m_max_num_msg;
                where = &mp_index[difference_type(m_max_num_msg-1u)];
             }
             else{
                --where;
             }
             const bool unique_segment = m_cur_first_msg && m_cur_first_msg <= pos;
             const size_type first_segment_beg  = unique_segment ? m_cur_first_msg : 1u;
             const size_type first_segment_end  = pos;
             const size_type second_segment_beg = unique_segment || !m_cur_first_msg ? m_max_num_msg : m_cur_first_msg;
             const size_type second_segment_end = m_max_num_msg;
             const msg_hdr_ptr_t backup   = *(&mp_index[0] + (unique_segment ?  first_segment_beg : second_segment_beg) - 1);
 
             //First segment
             if(!unique_segment){
                std::copy( &mp_index[0] + second_segment_beg
                         , &mp_index[0] + second_segment_end
                         , &mp_index[0] + second_segment_beg - 1);
                mp_index[difference_type(m_max_num_msg-1u)] = mp_index[0];
             }
             std::copy( &mp_index[0] + first_segment_beg
                      , &mp_index[0] + first_segment_end
                      , &mp_index[0] + first_segment_beg - 1);
             *where = backup;
             m_cur_first_msg = m_cur_first_msg ? m_cur_first_msg : m_max_num_msg;
             --m_cur_first_msg;
             ++m_cur_num_msg;
             return **where;
          }
          else{
             //The queue can't be full so end_pos < m_cur_first_msg
             //indicates two step insertion
             const size_type pos_end = this->end_pos();
             const bool unique_segment = pos < pos_end;
             const size_type first_segment_beg  = pos;
             const size_type first_segment_end  = unique_segment  ? pos_end : m_max_num_msg-1;
             const size_type second_segment_beg = 0u;
             const size_type second_segment_end = unique_segment ? 0u : pos_end;
             const msg_hdr_ptr_t backup   = *it_inserted_ptr_end;
 
             //First segment
             if(!unique_segment){
                std::copy_backward( &mp_index[0] + second_segment_beg
                                  , &mp_index[0] + second_segment_end
                                  , &mp_index[0] + second_segment_end + 1u);
                mp_index[0] = mp_index[difference_type(m_max_num_msg-1u)];
             }
             std::copy_backward( &mp_index[0] + first_segment_beg
                               , &mp_index[0] + first_segment_end
                               , &mp_index[0] + first_segment_end + 1u);
             *where = backup;
             ++m_cur_num_msg;
             return **where;
          }
       }
    }
 
    #else //BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX
 
    typedef msg_hdr_ptr_t *iterator;
 
    //!Returns the inserted message with top priority
    msg_header &top_msg()
       {  return *mp_index[difference_type(m_cur_num_msg-1u)];   }
 
    //!Returns the inserted message with bottom priority
    msg_header &bottom_msg()
       {  return *mp_index[0];   }
 
    iterator inserted_ptr_begin() const
    {  return &mp_index[0]; }
 
    iterator inserted_ptr_end() const
    {  return &mp_index[difference_type(m_cur_num_msg)]; }
 
    iterator lower_bound(const msg_hdr_ptr_t & value, priority_functor<VoidPointer> func)
    {  return std::lower_bound(this->inserted_ptr_begin(), this->inserted_ptr_end(), value, func);  }
 
    msg_header & insert_at(iterator pos)
    {
       const msg_hdr_ptr_t backup = *inserted_ptr_end();
       std::copy_backward(pos, inserted_ptr_end(), inserted_ptr_end()+1);
       *pos = backup;
       ++m_cur_num_msg;
       return **pos;
    }
 
    #endif   //BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX
 
    //!Inserts the first free message in the priority queue
    msg_header & queue_free_msg(unsigned int priority)
    {
       //Get priority queue's range
       iterator it  (inserted_ptr_begin()), it_end(inserted_ptr_end());
       //Optimize for non-priority usage
       if(m_cur_num_msg && priority > this->bottom_msg().priority){
          //Check for higher priority than all stored messages
          if(priority > this->top_msg().priority){
             it = it_end;
          }
          else{
             //Since we don't now which free message we will pick
             //build a dummy header for searches
             msg_header dummy_hdr;
             dummy_hdr.priority = priority;
 
             //Get free msg
             msg_hdr_ptr_t dummy_ptr(&dummy_hdr);
 
             //Check where the free message should be placed
             it = this->lower_bound(dummy_ptr, static_cast<priority_functor<VoidPointer>&>(*this));
          }
       }
       //Insert the free message in the correct position
       return this->insert_at(it);
    }
 
    //!Returns the number of bytes needed to construct a message queue with
    //!"max_num_size" maximum number of messages and "max_msg_size" maximum
    //!message size. Never throws.
    static size_type get_mem_size
       (size_type max_msg_size, size_type max_num_msg)
    {
       const size_type
        msg_hdr_align  = ::boost::container::dtl::alignment_of<msg_header>::value,
        index_align    = ::boost::container::dtl::alignment_of<msg_hdr_ptr_t>::value,
          r_hdr_size     = ipcdetail::ct_rounded_size<sizeof(mq_hdr_t), index_align>::value,
          r_index_size   = ipcdetail::get_rounded_size<size_type>(max_num_msg*sizeof(msg_hdr_ptr_t), msg_hdr_align),
          r_max_msg_size = ipcdetail::get_rounded_size<size_type>(max_msg_size, msg_hdr_align) + sizeof(msg_header);
       return r_hdr_size + r_index_size + (max_num_msg*r_max_msg_size) +
          open_create_impl_t::ManagedOpenOrCreateUserOffset;
    }
 
    //!Initializes the memory structures to preallocate messages and constructs the
    //!message index. Never throws.
    void initialize_memory()
    {
       const size_type
         msg_hdr_align  = ::boost::container::dtl::alignment_of<msg_header>::value,
         index_align    = ::boost::container::dtl::alignment_of<msg_hdr_ptr_t>::value,
          r_hdr_size     = ipcdetail::ct_rounded_size<sizeof(mq_hdr_t), index_align>::value,
          r_index_size   = ipcdetail::get_rounded_size<size_type>(m_max_num_msg*sizeof(msg_hdr_ptr_t), msg_hdr_align),
          r_max_msg_size = ipcdetail::get_rounded_size<size_type>(m_max_msg_size, msg_hdr_align) + sizeof(msg_header);
 
       //Pointer to the index
       msg_hdr_ptr_t *index =  move_detail::force_ptr<msg_hdr_ptr_t*>
                                  (reinterpret_cast<char*>(this)+r_hdr_size);
 
       //Pointer to the first message header
       msg_header *msg_hdr   =  move_detail::force_ptr<msg_header*>
                                  (reinterpret_cast<char*>(this)+r_hdr_size+r_index_size);
 
       //Initialize the pointer to the index
       mp_index             = index;
 
       //Initialize the index so each slot points to a preallocated message
       for(size_type i = 0; i < m_max_num_msg; ++i){
          index[i] = msg_hdr;
          msg_hdr  = move_detail::force_ptr<msg_header*>
                         (reinterpret_cast<char*>(msg_hdr)+r_max_msg_size);
       }
    }
 
    public:
    //Pointer to the index
    msg_hdr_ptr_ptr_t          mp_index;
    //Maximum number of messages of the queue
    const size_type            m_max_num_msg;
    //Maximum size of messages of the queue
    const size_type            m_max_msg_size;
    //Current number of messages
    size_type                  m_cur_num_msg;
    //Mutex to protect data structures
    interprocess_mutex         m_mutex;
    //Condition block receivers when there are no messages
    interprocess_condition     m_cond_recv;
    //Condition block senders when the queue is full
    interprocess_condition     m_cond_send;
    #if defined(BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX)
    //Current start offset in the circular index
    size_type                  m_cur_first_msg;
    size_type                  m_blocked_senders;
    size_type                  m_blocked_receivers;
    #endif
 };
 
 
 //!This is the atomic functor to be executed when creating or opening
 //!shared memory. Never throws
 template<class VoidPointer>
 class msg_queue_initialization_func_t
 {
    public:
    typedef typename boost::intrusive::
       pointer_traits<VoidPointer>::template
          rebind_pointer<char>::type                               char_ptr;
    typedef typename boost::intrusive::pointer_traits<char_ptr>::
       difference_type                                             difference_type;
    typedef typename boost::container::dtl::
       make_unsigned<difference_type>::type                        size_type;
 
    msg_queue_initialization_func_t(size_type maxmsg = 0,
                          size_type maxmsgsize = 0)
       : m_maxmsg (maxmsg), m_maxmsgsize(maxmsgsize) {}
 
    bool operator()(void *address, size_type, bool created)
    {
       char      *mptr;
 
       if(created){
          mptr     = reinterpret_cast<char*>(address);
          //Construct the message queue header at the beginning
          BOOST_INTERPROCESS_TRY{
             new (mptr) mq_hdr_t<VoidPointer>(m_maxmsg, m_maxmsgsize);
          }
          BOOST_INTERPROCESS_CATCH(...){
             return false;
          } BOOST_INTERPROCESS_CATCH_END
       }
       return true;
    }
 
    std::size_t get_min_size() const
    {
       return mq_hdr_t<VoidPointer>::get_mem_size(m_maxmsgsize, m_maxmsg)
       - message_queue_t<VoidPointer>::open_create_impl_t::ManagedOpenOrCreateUserOffset;
    }
 
    const size_type m_maxmsg;
    const size_type m_maxmsgsize;
 };
 
 }  //namespace ipcdetail {
 
 template<class VoidPointer>
 inline message_queue_t<VoidPointer>::~message_queue_t()
 {}
 
 template<class VoidPointer>
 inline typename message_queue_t<VoidPointer>::size_type message_queue_t<VoidPointer>::get_mem_size
    (size_type max_msg_size, size_type max_num_msg)
 {  return ipcdetail::mq_hdr_t<VoidPointer>::get_mem_size(max_msg_size, max_num_msg);   }
 
 template<class VoidPointer>
 inline message_queue_t<VoidPointer>::message_queue_t(create_only_t,
                                     const char *name,
                                     size_type max_num_msg,
                                     size_type max_msg_size,
                                     const permissions &perm)
       //Create shared memory and execute functor atomically
    :  m_shmem(create_only,
               name,
               get_mem_size(max_msg_size, max_num_msg),
               read_write,
               static_cast<void*>(0),
               //Prepare initialization functor
               ipcdetail::msg_queue_initialization_func_t<VoidPointer> (max_num_msg, max_msg_size),
               perm)
 {}
 
 template<class VoidPointer>
 inline message_queue_t<VoidPointer>::message_queue_t(open_or_create_t,
                                     const char *name,
                                     size_type max_num_msg,
                                     size_type max_msg_size,
                                     const permissions &perm)
       //Create shared memory and execute functor atomically
    :  m_shmem(open_or_create,
               name,
               get_mem_size(max_msg_size, max_num_msg),
               read_write,
               static_cast<void*>(0),
               //Prepare initialization functor
               ipcdetail::msg_queue_initialization_func_t<VoidPointer> (max_num_msg, max_msg_size),
               perm)
 {}
 
 template<class VoidPointer>
 inline message_queue_t<VoidPointer>::message_queue_t(open_only_t, const char *name)
    //Create shared memory and execute functor atomically
    :  m_shmem(open_only,
               name,
               read_write,
               static_cast<void*>(0),
               //Prepare initialization functor
               ipcdetail::msg_queue_initialization_func_t<VoidPointer> ())
 {}
 
 #if defined(BOOST_INTERPROCESS_WCHAR_NAMED_RESOURCES) || defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
 
 template<class VoidPointer>
 inline message_queue_t<VoidPointer>::message_queue_t(create_only_t,
                                     const wchar_t *name,
                                     size_type max_num_msg,
                                     size_type max_msg_size,
                                     const permissions &perm)
       //Create shared memory and execute functor atomically
    :  m_shmem(create_only,
               name,
               get_mem_size(max_msg_size, max_num_msg),
               read_write,
               static_cast<void*>(0),
               //Prepare initialization functor
               ipcdetail::msg_queue_initialization_func_t<VoidPointer> (max_num_msg, max_msg_size),
               perm)
 {}
 
 template<class VoidPointer>
 inline message_queue_t<VoidPointer>::message_queue_t(open_or_create_t,
                                     const wchar_t *name,
                                     size_type max_num_msg,
                                     size_type max_msg_size,
                                     const permissions &perm)
       //Create shared memory and execute functor atomically
    :  m_shmem(open_or_create,
               name,
               get_mem_size(max_msg_size, max_num_msg),
               read_write,
               static_cast<void*>(0),
               //Prepare initialization functor
               ipcdetail::msg_queue_initialization_func_t<VoidPointer> (max_num_msg, max_msg_size),
               perm)
 {}
 
 template<class VoidPointer>
 inline message_queue_t<VoidPointer>::message_queue_t(open_only_t, const wchar_t *name)
    //Create shared memory and execute functor atomically
    :  m_shmem(open_only,
               name,
               read_write,
               static_cast<void*>(0),
               //Prepare initialization functor
               ipcdetail::msg_queue_initialization_func_t<VoidPointer> ())
 {}
 
 #endif //defined(BOOST_INTERPROCESS_WCHAR_NAMED_RESOURCES) || defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
 
 template <class VoidPointer>
 inline message_queue_t<VoidPointer>::message_queue_t(size_type max_num_msg,
                                     size_type max_msg_size)
    :  m_shmem(get_mem_size(max_msg_size, max_num_msg),
             static_cast<void*>(0),
             //Prepare initialization functor
             ipcdetail::msg_queue_initialization_func_t<VoidPointer> (max_num_msg, max_msg_size))
 {}
 
 template<class VoidPointer>
 inline void message_queue_t<VoidPointer>::send
    (const void *buffer, size_type buffer_size, unsigned int priority)
 {  this->do_send<blocking>(buffer, buffer_size, priority, 0); }
 
 template<class VoidPointer>
 inline bool message_queue_t<VoidPointer>::try_send
    (const void *buffer, size_type buffer_size, unsigned int priority)
 {  return this->do_send<non_blocking>(buffer, buffer_size, priority, 0); }
 
 template<class VoidPointer>
 template<class TimePoint>
 inline bool message_queue_t<VoidPointer>::timed_send
    (const void *buffer, size_type buffer_size
    ,unsigned int priority, const TimePoint &abs_time)
 {
    if(ipcdetail::is_pos_infinity(abs_time)){
       this->send(buffer, buffer_size, priority);
       return true;
    }
    return this->do_send<timed>(buffer, buffer_size, priority, abs_time);
 }
 
 template<class VoidPointer>
 template<mqblock_types Block, class TimePoint>
 inline bool message_queue_t<VoidPointer>::do_send(
                                 const void *buffer,      size_type buffer_size,
                                 unsigned int priority,   const TimePoint &abs_time)
 {
    ipcdetail::mq_hdr_t<VoidPointer> *p_hdr = static_cast<ipcdetail::mq_hdr_t<VoidPointer>*>(m_shmem.get_user_address());
    //Check if buffer is smaller than maximum allowed
    if (buffer_size > p_hdr->m_max_msg_size) {
       throw interprocess_exception(size_error);
    }
 
    #if defined(BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX)
    bool notify_blocked_receivers = false;
    #endif
    //---------------------------------------------
    scoped_lock<interprocess_mutex> lock(p_hdr->m_mutex);
    //---------------------------------------------
    {
       //If the queue is full execute blocking logic
       if (p_hdr->is_full()) {
          BOOST_INTERPROCESS_TRY{
             #ifdef BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX
             ++p_hdr->m_blocked_senders;
             #endif
             switch(Block){
                case non_blocking :
                   #ifdef BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX
                   --p_hdr->m_blocked_senders;
                   #endif
                   return false;
                break;
 
                case blocking :
                   do{
                      (void)do_cond_wait(ipcdetail::bool_<false>(), p_hdr->m_cond_send, lock, abs_time);
                   }
                   while (p_hdr->is_full());
                break;
 
                case timed :
                   do{
                      if(!do_cond_wait(ipcdetail::bool_<Block == timed>(), p_hdr->m_cond_send, lock, abs_time)) {
                         if(p_hdr->is_full()){
                            #ifdef BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX
                            --p_hdr->m_blocked_senders;
                            #endif
                            return false;
                         }
                         break;
                      }
                   }
                   while (p_hdr->is_full());
                break;
                default:
                break;
             }
             #ifdef BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX
             --p_hdr->m_blocked_senders;
             #endif
          }
          BOOST_INTERPROCESS_CATCH(...){
             #ifdef BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX
             --p_hdr->m_blocked_senders;
             #endif
             BOOST_INTERPROCESS_RETHROW;
          } BOOST_INTERPROCESS_CATCH_END
       }
 
       #if defined(BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX)
       notify_blocked_receivers = 0 != p_hdr->m_blocked_receivers;
       #endif
       //Insert the first free message in the priority queue
       ipcdetail::msg_hdr_t<VoidPointer> &free_msg_hdr = p_hdr->queue_free_msg(priority);
 
       //Sanity check, free msgs are always cleaned when received
       BOOST_ASSERT(free_msg_hdr.priority == 0);
       BOOST_ASSERT(free_msg_hdr.len == 0);
 
       //Copy control data to the free message
       free_msg_hdr.priority = priority;
       free_msg_hdr.len      = buffer_size;
 
       //Copy user buffer to the message
       std::memcpy(free_msg_hdr.data(), buffer, buffer_size);
    }  // Lock end
 
    //Notify outside lock to avoid contention. This might produce some
    //spurious wakeups, but it's usually far better than notifying inside.
    //If this message changes the queue empty state, notify it to receivers
    #if defined(BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX)
    if (notify_blocked_receivers){
       p_hdr->m_cond_recv.notify_one();
    }
    #else
    p_hdr->m_cond_recv.notify_one();
    #endif
 
    return true;
 }
 
 template<class VoidPointer>
 inline void message_queue_t<VoidPointer>::receive(void *buffer,        size_type buffer_size,
                         size_type &recvd_size,   unsigned int &priority)
 {  this->do_receive<blocking>(buffer, buffer_size, recvd_size, priority, 0); }
 
 template<class VoidPointer>
 inline bool
    message_queue_t<VoidPointer>::try_receive(void *buffer,              size_type buffer_size,
                               size_type &recvd_size,   unsigned int &priority)
 {  return this->do_receive<non_blocking>(buffer, buffer_size, recvd_size, priority, 0); }
 
 template<class VoidPointer>
 template<class TimePoint>
 inline bool
    message_queue_t<VoidPointer>::timed_receive(void *buffer,            size_type buffer_size,
                                 size_type &recvd_size,   unsigned int &priority,
                                 const TimePoint &abs_time)
 {
    if(ipcdetail::is_pos_infinity(abs_time)){
       this->receive(buffer, buffer_size, recvd_size, priority);
       return true;
    }
    return this->do_receive<timed>(buffer, buffer_size, recvd_size, priority, abs_time);
 }
 
 template<class VoidPointer>
 template<mqblock_types Block, class TimePoint>
 inline bool
    message_queue_t<VoidPointer>::do_receive(
                           void *buffer,            size_type buffer_size,
                           size_type &recvd_size,   unsigned int &priority,
                           const TimePoint &abs_time)
 {
    ipcdetail::mq_hdr_t<VoidPointer> *p_hdr = static_cast<ipcdetail::mq_hdr_t<VoidPointer>*>(m_shmem.get_user_address());
    //Check if buffer is big enough for any message
    if (buffer_size < p_hdr->m_max_msg_size) {
       throw interprocess_exception(size_error);
    }
 
    #if defined(BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX)
    bool notify_blocked_senders = false;
    #endif
    //---------------------------------------------
    scoped_lock<interprocess_mutex> lock(p_hdr->m_mutex);
    //---------------------------------------------
    {
       //If there are no messages execute blocking logic
       if (p_hdr->is_empty()) {
          BOOST_INTERPROCESS_TRY{
             #if defined(BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX)
             ++p_hdr->m_blocked_receivers;
             #endif
             switch(Block){
                case non_blocking :
                   #if defined(BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX)
                   --p_hdr->m_blocked_receivers;
                   #endif
                   return false;
                break;
 
                case blocking :
                   do{
                      (void)do_cond_wait(ipcdetail::bool_<false>(), p_hdr->m_cond_recv, lock, abs_time);
                   }
                   while (p_hdr->is_empty());
                break;
 
                case timed :
                   do{
                      if(!do_cond_wait(ipcdetail::bool_<Block == timed>(), p_hdr->m_cond_recv, lock, abs_time)) {
                         if(p_hdr->is_empty()){
                            #if defined(BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX)
                            --p_hdr->m_blocked_receivers;
                            #endif
                            return false;
                         }
                         break;
                      }
                   }
                   while (p_hdr->is_empty());
                break;
 
                //Paranoia check
                default:
                break;
             }
             #if defined(BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX)
             --p_hdr->m_blocked_receivers;
             #endif
          }
          BOOST_INTERPROCESS_CATCH(...){
             #if defined(BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX)
             --p_hdr->m_blocked_receivers;
             #endif
             BOOST_INTERPROCESS_RETHROW;
          } BOOST_INTERPROCESS_CATCH_END
       }
 
       #ifdef BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX
       notify_blocked_senders = 0 != p_hdr->m_blocked_senders;
       #endif
 
       //There is at least one message ready to pick, get the top one
       ipcdetail::msg_hdr_t<VoidPointer> &top_msg = p_hdr->top_msg();
 
       //Get data from the message
       recvd_size     = top_msg.len;
       priority       = top_msg.priority;
 
       //Some cleanup to ease debugging
       top_msg.len       = 0;
       top_msg.priority  = 0;
 
       //Copy data to receiver's bufers
       std::memcpy(buffer, top_msg.data(), recvd_size);
 
       //Free top message and put it in the free message list
       p_hdr->free_top_msg();
    }  //Lock end
 
    //Notify outside lock to avoid contention. This might produce some
    //spurious wakeups, but it's usually far better than notifying inside.
    //If this reception changes the queue full state, notify senders
    #ifdef BOOST_INTERPROCESS_MSG_QUEUE_CIRCULAR_INDEX
    if (notify_blocked_senders){
       p_hdr->m_cond_send.notify_one();
    }
    #else
    p_hdr->m_cond_send.notify_one();
    #endif
 
    return true;
 }
 
 template<class VoidPointer>
 inline typename message_queue_t<VoidPointer>::size_type message_queue_t<VoidPointer>::get_max_msg() const
 {
    ipcdetail::mq_hdr_t<VoidPointer> *p_hdr = static_cast<ipcdetail::mq_hdr_t<VoidPointer>*>(m_shmem.get_user_address());
    return p_hdr ? p_hdr->m_max_num_msg : 0;  }
 
 template<class VoidPointer>
 inline typename message_queue_t<VoidPointer>::size_type message_queue_t<VoidPointer>::get_max_msg_size() const
 {
    ipcdetail::mq_hdr_t<VoidPointer> *p_hdr = static_cast<ipcdetail::mq_hdr_t<VoidPointer>*>(m_shmem.get_user_address());
    return p_hdr ? p_hdr->m_max_msg_size : 0;
 }
 
 template<class VoidPointer>
 inline typename message_queue_t<VoidPointer>::size_type message_queue_t<VoidPointer>::get_num_msg() const
 {
    ipcdetail::mq_hdr_t<VoidPointer> *p_hdr = static_cast<ipcdetail::mq_hdr_t<VoidPointer>*>(m_shmem.get_user_address());
    if(p_hdr){
       //---------------------------------------------
       scoped_lock<interprocess_mutex> lock(p_hdr->m_mutex);
       //---------------------------------------------
       return p_hdr->m_cur_num_msg;
    }
 
    return 0;
 }
 
 template<class VoidPointer>
 inline bool message_queue_t<VoidPointer>::remove(const char *name)
 {  return shared_memory_object::remove(name);  }
 
 #if defined(BOOST_INTERPROCESS_WCHAR_NAMED_RESOURCES) || defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
 
 template<class VoidPointer>
 inline bool message_queue_t<VoidPointer>::remove(const wchar_t *name)
 {  return shared_memory_object::remove(name);  }
 
 #endif
 
 #else
 
 //!Typedef for a default message queue
 //!to be used between processes
 typedef message_queue_t<offset_ptr<void> > message_queue;
 
 #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
 
 }} //namespace boost{  namespace interprocess{
 
 #include <boost/interprocess/detail/config_end.hpp>
 
 #endif   //#ifndef BOOST_INTERPROCESS_MESSAGE_QUEUE_HPP

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