Gikoskos

To understand it better here's the solution to the producer/consumer problem (from wikipedia), using mutexes and semaphores:

  mtx buffer_mutex;
  sem fillCount = 0;
  sem emptyCount = BUFFER_SIZE;
  
  procedure producer() 
  {
      while (true) 
      {
          item = produceItem();
          down(emptyCount);
          down(buffer_mutex);
          putItemIntoBuffer(item);
          up(buffer_mutex);
          up(fillCount);
      }
  }
  
  procedure consumer() 
  {
      while (true) 
      {
          down(fillCount);
          down(buffer_mutex);
          item = removeItemFromBuffer();
          up(buffer_mutex);
          up(emptyCount);
          consumeItem(item);
      }
  }

  int avl = 0;
  
  procedure producer() 
  {
      while (true) 
      {
          item = produceItem();
          region R when (avl < BUFFER_SIZE)
          {
              putItemIntoBuffer(item);
              avl++;
          }
      }
  }
  
  procedure consumer() 
  {
     while (true) 
     {
         region R when (avl > 0)
         {
             item = removeItemFromBuffer();
             avl--;
         }
         consumeItem(item);
     }
  }