Safe Message Queue with multiple threads

Question

Here is what I essentially have:

I have thread A that periodically checks for messages and processes them.

Threads B and C need to send messages to A.

Th

Answer 1

If you are not on windows or if you are implementing something which is cross platform in C++, try using the Queue from ACE libraries.

ACE_Message_Queue *msg_queue;

As a sample from ACE library samples, You can then use For putting message to the queue:

  ACE_NEW_RETURN (mb,
              ACE_Message_Block (rb.size (),
              ACE_Message_Block::MB_DATA,
              0,
              buffer),
              0);
  mb->msg_priority (ACE_Utils::truncate_cast (rb.size ()));
  mb->wr_ptr (rb.size ());

  ACE_DEBUG ((LM_DEBUG,
          "enqueueing message of size %d\n",
          mb->msg_priority ()));

 // Enqueue in priority order.
 if (msg_queue->enqueue_prio (mb) == -1)
ACE_ERROR ((LM_ERROR, "(%t) %p\n", "put_next"));

for getting from queue:

 ACE_Message_Block *mb = 0;

 msg_queue->dequeue_head (mb) == -1;
 int length = ACE_Utils::truncate_cast (mb->length ());

 if (length > 0)
   ACE_OS::puts (mb->rd_ptr ());

  // Free up the buffer memory and the Message_Block.
  ACE_Allocator::instance ()->free (mb->rd_ptr ());
  mb->release ();

The advantage is you can change the synchronization primitive very easily without having to write too much of code.