Attention is currently required from: fixeria, laforge.

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1 comment:

• File library/Mutex.ttcn:

  • Patch Set #2, Line 19: port MutexPT LOCK; /* port for LOCKing the mutex */

    But why would you want to lock the Mutex twice? Is this a normal scenario?

    Sure reentrant mutexes are a thing :) This is usually only needed in more complex scenarios than what we aim here though.
    This can be used for instance to implement semaphores, which eg. allow up to N-concurrent users where N can be defined.

    Can you explain your idea a bit more?

    Yes, you have 1 port which has LOCK and UNLOCK operations.

    	alt {
    	[lock_count == 0] pt.get_call(LOCK) -> sender {
    	   lock_sender = sender;
    	   lock_count++;
    	   pt.send_response(sender, LOCK);
    	}
    	[lock_count > 0] pt.get_call(LOCK) -> sender {
    	   if (lock_count > 0) {
    		   if(and sender != lock_sender) {
    			  error();
    		  } else {
    			  /* Make the component wait until mutex is unlocked: */
    			  lock_queue := lock_queue & { sender };
    			  return;
    		  }
    	   lock_sender = sender;
    	   lock_count++;
    	   pt.send_response(sender, LOCK);
    	}
    	[lock_count == 0] pt.get_call(UNLOCK) -> sender {
    	   errror();
    	}
    	[lock_count > 0] pt.get_call(UNLOCK) -> sender {
    	   if (sender != lock_sender)
    		   error();
    	   lock_count--;
    	   pt.send_response(sender, UNLOCK);
    	   if (lock_count == 0) {
    		   if (lengthof(lock_queue) > 0)
    			  sender := lock_queue[0]
    			  //TODO: HERE pop lock_queue[0] from queue
    			  /* Tell first component waiting in the queue that it finally acquired the lock: */
    			  pt.send_response(sender, LOCK);
    			  lock_count++;
    	   }
    	}

    	}

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