plugins/elements/gstqueue.*: When downstream returns UNEXPECTED from pushing a buffer, don't try to push more buffers...

Original commit message from CVS:
* plugins/elements/gstqueue.c: (gst_queue_locked_enqueue),
(gst_queue_handle_sink_event), (gst_queue_chain),
(gst_queue_push_one), (gst_queue_handle_src_query),
(gst_queue_sink_activate_push), (gst_queue_src_activate_push):
* plugins/elements/gstqueue.h:
When downstream returns UNEXPECTED from pushing a buffer, don't try to
push more buffers but allow pushing of EOS and NEWSEGMENT.
Add some more debug info here and there. Fixes #476514.

ChangeLog

@@ -1,3 +1,14 @@
+2007-09-14  Wim Taymans  <wim.taymans@gmail.com>
+
+	* plugins/elements/gstqueue.c: (gst_queue_locked_enqueue),
+	(gst_queue_handle_sink_event), (gst_queue_chain),
+	(gst_queue_push_one), (gst_queue_handle_src_query),
+	(gst_queue_sink_activate_push), (gst_queue_src_activate_push):
+	* plugins/elements/gstqueue.h:
+	When downstream returns UNEXPECTED from pushing a buffer, don't try to
+	push more buffers but allow pushing of EOS and NEWSEGMENT.
+	Add some more debug info here and there. Fixes #476514.
+
 2007-09-14  Wim Taymans  <wim.taymans@gmail.com>
 
 	* libs/gst/base/gstbasesink.c: (gst_base_sink_init),

plugins/elements/gstqueue.c

@@ -616,7 +616,7 @@ gst_queue_locked_flush (GstQueue * queue)
   GST_QUEUE_SIGNAL_DEL (queue);
 }
 
-/* enqueue an item an update the level stats */
+/* enqueue an item an update the level stats, with QUEUE_LOCK */
 static void
 gst_queue_locked_enqueue (GstQueue * queue, gpointer item)
 {
@@ -636,9 +636,15 @@ gst_queue_locked_enqueue (GstQueue * queue, gpointer item)
         /* Zero the thresholds, this makes sure the queue is completely
          * filled and we can read all data from the queue. */
         GST_QUEUE_CLEAR_LEVEL (queue->min_threshold);
+        /* mark the queue as EOS. This prevents us from accepting more data. */
+        GST_CAT_LOG_OBJECT (queue_dataflow, queue, "got EOS from upstream");
+        queue->eos = TRUE;
         break;
       case GST_EVENT_NEWSEGMENT:
         apply_segment (queue, event, &queue->sink_segment);
+        /* a new segment allows us to accept more buffers if we got UNEXPECTED
+         * from downstream */
+        queue->unexpected = FALSE;
         break;
       default:
         break;
@@ -747,6 +753,8 @@ gst_queue_handle_sink_event (GstPad * pad, GstEvent * event)
       GST_QUEUE_MUTEX_LOCK (queue);
       gst_queue_locked_flush (queue);
       queue->srcresult = GST_FLOW_OK;
+      queue->eos = FALSE;
+      queue->unexpected = FALSE;
       if (gst_pad_is_linked (queue->srcpad)) {
         gst_pad_start_task (queue->srcpad, (GstTaskFunction) gst_queue_loop,
             queue->srcpad);
@@ -762,6 +770,9 @@ gst_queue_handle_sink_event (GstPad * pad, GstEvent * event)
       if (GST_EVENT_IS_SERIALIZED (event)) {
         /* serialized events go in the queue */
         GST_QUEUE_MUTEX_LOCK_CHECK (queue, out_flushing);
+        /* refuse more events on EOS */
+        if (queue->eos)
+          goto out_eos;
         gst_queue_locked_enqueue (queue, event);
         GST_QUEUE_MUTEX_UNLOCK (queue);
       } else {
@@ -776,6 +787,15 @@ done:
   /* ERRORS */
 out_flushing:
   {
+    GST_CAT_LOG_OBJECT (queue_dataflow, queue,
+        "refusing event, we are flushing");
+    GST_QUEUE_MUTEX_UNLOCK (queue);
+    gst_buffer_unref (event);
+    return FALSE;
+  }
+out_eos:
+  {
+    GST_CAT_LOG_OBJECT (queue_dataflow, queue, "refusing event, we are EOS");
     GST_QUEUE_MUTEX_UNLOCK (queue);
     gst_buffer_unref (event);
     return FALSE;
@@ -815,6 +835,11 @@ gst_queue_chain (GstPad * pad, GstBuffer * buffer)
 
   /* we have to lock the queue since we span threads */
   GST_QUEUE_MUTEX_LOCK_CHECK (queue, out_flushing);
+  /* when we received EOS, we refuse any more data */
+  if (queue->eos)
+    goto out_eos;
+  if (queue->unexpected)
+    goto out_unexpected;
 
   timestamp = GST_BUFFER_TIMESTAMP (buffer);
   duration = GST_BUFFER_DURATION (buffer);
@@ -910,6 +935,25 @@ out_flushing:
 
     return ret;
   }
+out_eos:
+  {
+    GST_CAT_LOG_OBJECT (queue_dataflow, queue, "exit because we received EOS");
+    GST_QUEUE_MUTEX_UNLOCK (queue);
+
+    gst_buffer_unref (buffer);
+
+    return GST_FLOW_UNEXPECTED;
+  }
+out_unexpected:
+  {
+    GST_CAT_LOG_OBJECT (queue_dataflow, queue,
+        "exit because we received UNEXPECTED");
+    GST_QUEUE_MUTEX_UNLOCK (queue);
+
+    gst_buffer_unref (buffer);
+
+    return GST_FLOW_UNEXPECTED;
+  }
 }
 
 /* dequeue an item from the queue an push it downstream. This functions returns
@@ -924,6 +968,7 @@ gst_queue_push_one (GstQueue * queue)
   if (data == NULL)
     goto no_item;
 
+next:
   if (GST_IS_BUFFER (data)) {
     GstBuffer *buffer = GST_BUFFER_CAST (data);
 
@@ -933,6 +978,42 @@ gst_queue_push_one (GstQueue * queue)
 
     /* need to check for srcresult here as well */
     GST_QUEUE_MUTEX_LOCK_CHECK (queue, out_flushing);
+
+    if (result == GST_FLOW_UNEXPECTED) {
+      GST_CAT_LOG_OBJECT (queue_dataflow, queue,
+          "got UNEXPECTED from downstream");
+      /* stop pushing buffers, we dequeue all items until we see an item that we
+       * can push again, which is EOS or NEWSEGMENT. If there is nothing in the
+       * queue we can push, we set a flag to make the sinkpad refuse more
+       * buffers with an UNEXPECTED return value. */
+      while ((data = gst_queue_locked_dequeue (queue))) {
+        if (GST_IS_BUFFER (data)) {
+          GST_CAT_LOG_OBJECT (queue_dataflow, queue,
+              "dropping UNEXPECTED buffer %p", data);
+          gst_buffer_unref (GST_BUFFER_CAST (data));
+        } else if (GST_IS_EVENT (data)) {
+          GstEvent *event = GST_EVENT_CAST (data);
+          GstEventType type = GST_EVENT_TYPE (event);
+
+          if (type == GST_EVENT_EOS || type == GST_EVENT_NEWSEGMENT) {
+            /* we found a pushable item in the queue, push it out */
+            GST_CAT_LOG_OBJECT (queue_dataflow, queue,
+                "pushing pushable event %s after UNEXPECTED %p",
+                GST_EVENT_TYPE_NAME (event));
+            goto next;
+          }
+          GST_CAT_LOG_OBJECT (queue_dataflow, queue,
+              "dropping UNEXPECTED event %p", event);
+          gst_event_unref (event);
+        }
+      }
+      /* no more items in the queue. Set the unexpected flag so that upstream
+       * make us refuse any more buffers on the sinkpad. Since we will still
+       * accept EOS and NEWSEGMENT we return _FLOW_OK to the caller so that the
+       * task function does not shut down. */
+      queue->unexpected = TRUE;
+      result = GST_FLOW_OK;
+    }
   } else if (GST_IS_EVENT (data)) {
     GstEvent *event = GST_EVENT_CAST (data);
     GstEventType type = GST_EVENT_TYPE (event);
@@ -943,8 +1024,11 @@ gst_queue_push_one (GstQueue * queue)
 
     GST_QUEUE_MUTEX_LOCK_CHECK (queue, out_flushing);
     /* if we're EOS, return UNEXPECTED so that the task pauses. */
-    if (type == GST_EVENT_EOS)
+    if (type == GST_EVENT_EOS) {
+      GST_CAT_LOG_OBJECT (queue_dataflow, queue,
+          "pushed EOS event %p, return UNEXPECTED", event);
       result = GST_FLOW_UNEXPECTED;
+    }
   }
   return result;
 
@@ -1106,6 +1190,8 @@ gst_queue_sink_activate_push (GstPad * pad, gboolean active)
   if (active) {
     GST_QUEUE_MUTEX_LOCK (queue);
     queue->srcresult = GST_FLOW_OK;
+    queue->eos = FALSE;
+    queue->unexpected = FALSE;
     GST_QUEUE_MUTEX_UNLOCK (queue);
   } else {
     /* step 1, unblock chain function */
@@ -1131,6 +1217,8 @@ gst_queue_src_activate_push (GstPad * pad, gboolean active)
   if (active) {
     GST_QUEUE_MUTEX_LOCK (queue);
     queue->srcresult = GST_FLOW_OK;
+    queue->eos = FALSE;
+    queue->unexpected = FALSE;
     /* we do not start the task yet if the pad is not connected */
     if (gst_pad_is_linked (pad))
       result = gst_pad_start_task (pad, (GstTaskFunction) gst_queue_loop, pad);

plugins/elements/gstqueue.h

@@ -87,6 +87,8 @@ struct _GstQueue {
 
   /* flowreturn when srcpad is paused */
   GstFlowReturn srcresult;
+  gboolean      unexpected;
+  gboolean      eos;
 
   /* the queue of data we're keeping our grubby hands on */
   GQueue *queue;