docs/random/queue

   1             thread 1                                         thread2
   2
   3                                                            // the queue is empty
   4                                                            while (!queue->level_buffers) {
   5                                                              STATUS("queue: %s U released lock\n");
   6                                                              GST_OBJECT_UNLOCK (queue);
   7
   8   // thread1 is scheduled and puts a lot of buffers
   9   // in the queue
  10
  11   // thread1 has put the last buffer on the queue
  12   // here. A signal is going to be emitted
  13
  14   tosignal = (queue->level_buffers >= 0);
  15   queue->level_buffers++;
  16
  17   /* we can unlock now */
  18   GST_OBJECT_UNLOCK (queue);
  19
  20   if (tosignal) {
  21     g_mutex_lock (queue->emptylock);
  22     g_cond_signal (queue->emptycond);
  23     g_mutex_unlock (queue->emptylock);
  24   }
  25
  26                                                              g_mutex_lock (queue->emptylock);
  27                                                              // wait forever
  28                                                              g_cond_wait (queue->emptycond, queue->emptylock);
  29                                                              g_mutex_unlock (queue->emptylock);
  30                                                              GST_OBJECT_LOCK (queue);
  31                                                            }
  32
  33
  34   // thread 1 will also wait forever because the
  35   // queue is filled....
  36
  37
  38