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@OmerRaviv
Created July 24, 2012 16:35
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boost::interprocess::message_queue, where the underlying implementation uses a circular buffer
//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2005-2009. 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
#include <boost/interprocess/detail/config_begin.hpp>
#include <boost/interprocess/detail/workaround.hpp>
#include <boost/interprocess/windows_shared_memory.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/detail/utilities.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/detail/no_exceptions_support.hpp>
#include <boost/interprocess/detail/type_traits.hpp>
#include <boost/pointer_to_other.hpp>
#include <boost/type_traits/make_unsigned.hpp>
#include <boost/type_traits/alignment_of.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{
//!A class that allows sending messages
//!between processes.
template<class VoidPointer>
class message_queue_t
{
/// @cond
//Blocking modes
enum block_t { blocking, timed, non_blocking };
message_queue_t();
/// @endcond
public:
typedef VoidPointer void_pointer;
typedef typename boost::pointer_to_other<void_pointer, char>::type char_ptr;
typedef typename std::iterator_traits<char_ptr>::difference_type difference_type;
//typedef typename boost::make_unsigned<difference_type>::type size_type;
typedef __int32 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 create_only,
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 open_or_create,
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 was not previously created or there are no free resources,
//!throws an error.
message_queue_t(open_only_t open_only,
const char *name);
//!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.
bool timed_send (const void *buffer, size_type buffer_size,
unsigned int priority, const boost::posix_time::ptime& 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.
bool timed_receive (void *buffer, size_type buffer_size,
size_type &recvd_size,unsigned int &priority,
const boost::posix_time::ptime &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();
//!Removes the message queue from the system.
//!Returns false on error. Never throws
static bool remove(const char *name);
/// @cond
private:
typedef boost::posix_time::ptime ptime;
bool do_receive(block_t block,
void *buffer, size_type buffer_size,
size_type &recvd_size, unsigned int &priority,
const ptime &abs_time);
bool do_send(block_t block,
const void *buffer, size_type buffer_size,
unsigned int priority, const ptime &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);
ipcdetail::managed_open_or_create_impl<windows_shared_memory,false> m_shmem;
// ipcdetail::managed_open_or_create_impl<shared_memory_object> m_shmem;
/// @endcond
};
/// @cond
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::
pointer_to_other<VoidPointer, char>::type char_ptr;
typedef typename std::iterator_traits<char_ptr>::difference_type difference_type;
//typedef typename boost::make_unsigned<difference_type>::type size_type;
typedef typename __int32 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 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. The elements of this array are
//! reordered in runtime in the following way:
//!
//! 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 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
{
typedef VoidPointer void_pointer;
typedef msg_hdr_t<void_pointer> msg_header;
typedef typename boost::
pointer_to_other<void_pointer, msg_header>::type msg_hdr_ptr_t;
typedef typename std::iterator_traits<msg_hdr_ptr_t>::difference_type difference_type;
//typedef typename boost::make_unsigned<difference_type>::type size_type;
typedef __int32 size_type;
typedef typename boost::
pointer_to_other<void_pointer, msg_hdr_ptr_t>::type msg_hdr_ptr_ptr_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)
{ this->initialize_memory(); }
//!Returns the inserted message with top priority, the next message to be read
msg_header * top_msg()
{ return mp_index[m_first_msg_index].get(); }
//!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 location of the message that was read.
void free_top_msg()
{
--m_cur_num_msg;
m_first_msg_index = (m_first_msg_index + 1) % m_max_num_msg; // cyclic buffer, slide over to the start if neccesary
}
//!Returns the first free msg of the free message queue, to write to.
msg_header * free_msg()
{
size_t last_msg_index = (m_first_msg_index + m_cur_num_msg) % m_max_num_msg; // cyclic buffer
++m_cur_num_msg;
return mp_index[last_msg_index].get();
}
//!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::alignment_of<msg_header>::value,
index_align = ::boost::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)sizeof(msg_hdr_ptr_t)*max_num_msg, (size_type)msg_hdr_align),
r_max_msg_size = ipcdetail::get_rounded_size(max_msg_size, msg_hdr_align) + sizeof(msg_header);
return r_hdr_size + r_index_size + (max_num_msg*r_max_msg_size) +
ipcdetail::managed_open_or_create_impl<windows_shared_memory, false>::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::alignment_of<msg_header>::value,
index_align = ::boost::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)sizeof(msg_hdr_ptr_t)*m_max_num_msg, (size_type)msg_hdr_align),
r_max_msg_size = ipcdetail::get_rounded_size(m_max_msg_size, msg_hdr_align) + sizeof(msg_header);
//Pointer to the index
msg_hdr_ptr_t *index = reinterpret_cast<msg_hdr_ptr_t*>
(reinterpret_cast<char*>(this)+r_hdr_size);
//Pointer to the first message header
msg_header *msg_hdr = reinterpret_cast<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 = reinterpret_cast<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;
//The location of the first message, the one that should be received next
size_type m_first_msg_index;
//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;
};
//!This is the atomic functor to be executed when creating or opening
//!shared memory. Never throws
template<class VoidPointer>
class initialization_func_t
{
public:
typedef typename boost::pointer_to_other<VoidPointer, char>::type char_ptr;
typedef typename std::iterator_traits<char_ptr>::difference_type difference_type;
//typedef typename boost::make_unsigned<difference_type>::type size_type;
typedef __int32 size_type;
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_TRY{
new (mptr) mq_hdr_t<VoidPointer>(m_maxmsg, m_maxmsgsize);
}
BOOST_CATCH(...){
return false;
}
BOOST_CATCH_END
}
return true;
}
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 create_only,
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::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 open_or_create,
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::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 open_only,
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::initialization_func_t<VoidPointer> ())
{}
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, ptime()); }
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, ptime()); }
template<class VoidPointer>
inline bool message_queue_t<VoidPointer>::timed_send
(const void *buffer, size_type buffer_size
,unsigned int priority, const boost::posix_time::ptime &abs_time)
{
if(abs_time == boost::posix_time::pos_infin){
this->send(buffer, buffer_size, priority);
return true;
}
return this->do_send(timed, buffer, buffer_size, priority, abs_time);
}
template<class VoidPointer>
inline bool message_queue_t<VoidPointer>::do_send(block_t block,
const void *buffer, size_type buffer_size,
unsigned int priority, const boost::posix_time::ptime &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);
}
//---------------------------------------------
scoped_lock<interprocess_mutex> lock(p_hdr->m_mutex);
//---------------------------------------------
{
//If the queue is full execute blocking logic
if (p_hdr->is_full()) {
switch(block){
case non_blocking :
return false;
break;
case blocking :
do{
p_hdr->m_cond_send.wait(lock);
}
while (p_hdr->is_full());
break;
case timed :
do{
if(!p_hdr->m_cond_send.timed_wait(lock, abs_time)){
if(p_hdr->is_full())
return false;
break;
}
}
while (p_hdr->is_full());
break;
default:
break;
}
}
//Get the first free message from free message queue
ipcdetail::msg_hdr_t<VoidPointer> *free_msg = p_hdr->free_msg();
if (free_msg == 0) {
throw interprocess_exception("boost::interprocess::message_queue corrupted");
}
//Copy control data to the free message
free_msg->priority = priority;
free_msg->len = buffer_size;
//Copy user buffer to the message
std::memcpy(free_msg->data(), buffer, buffer_size);
bool was_empty = p_hdr->is_empty();
//Insert the first free message in the priority queue
//If this message changes the queue empty state, notify it to receivers
if (was_empty){
// return true; // PERF tweak by omer. we'll be doing timed checks if buffer is empty or not, so no need for a cond variable.UNCOMMENT FOR PERF
p_hdr->m_cond_recv.notify_one();
}
} // Lock end
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, ptime()); }
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, ptime()); }
template<class VoidPointer>
inline bool
message_queue_t<VoidPointer>::timed_receive(void *buffer, size_type buffer_size,
size_type &recvd_size, unsigned int &priority,
const boost::posix_time::ptime &abs_time)
{
if(abs_time == boost::posix_time::pos_infin){
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>
inline bool
message_queue_t<VoidPointer>::do_receive(block_t block,
void *buffer, size_type buffer_size,
size_type &recvd_size, unsigned int &priority,
const boost::posix_time::ptime &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);
}
//---------------------------------------------
scoped_lock<interprocess_mutex> lock(p_hdr->m_mutex);
//---------------------------------------------
{
//If there are no messages execute blocking logic
if (p_hdr->is_empty()) {
switch(block){
case non_blocking :
return false;
break;
case blocking :
do{
p_hdr->m_cond_recv.wait(lock);
}
while (p_hdr->is_empty());
break;
case timed :
do{
if(!p_hdr->m_cond_recv.timed_wait(lock, abs_time)){
if(p_hdr->is_empty())
return false;
break;
}
}
while (p_hdr->is_empty());
break;
//Paranoia check
default:
break;
}
}
//Thre is at least message ready to pick, get the top one
ipcdetail::msg_hdr_t<VoidPointer> *top_msg = p_hdr->top_msg();
//Paranoia check
if (top_msg == 0) {
throw interprocess_exception("boost::interprocess::message_queue corrupted");
}
//Get data from the message
recvd_size = top_msg->len;
priority = top_msg->priority;
//Copy data to receiver's bufers
std::memcpy(buffer, top_msg->data(), recvd_size);
bool was_full = p_hdr->is_full();
//Free top message and put it in the free message list
p_hdr->free_top_msg();
//If this reception changes the queue full state, notify senders
if (was_full){
p_hdr->m_cond_send.notify_one();
}
} //Lock end
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()
{
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 true;; }
/// @endcond
}} //namespace boost{ namespace interprocess{
#include <boost/interprocess/detail/config_end.hpp>
#endif //#ifndef BOOST_INTERPROCESS_MESSAGE_QUEUE_HPP
@OmerRaviv
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This code needs to be cleaned up - all mention of message priority should be removed, the new implementation completely ignores it.

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