PPT Slide
- int DetachMessageQueue(int msg_q_id) - Decrement the attach count by one; if the attach count reaches zero then delete the message queue file from the file system. Return -1 if msg_q_id is invalid.
- Extend Exit() so that any attached queues are automatically detached when the process ends, to keep things straight (just like auto-closing of any opened files).
- We will surround the critical section of code with a ReceiveMessage() call, which will block the calling process until a message is actually in the queue. The SendMessage() call will be used after the critical section to signal the other waiting process.