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Fix a deadlock that happens if the next element sends an event and the previous element sends a buffer where the queu...

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Original commit message from CVS:
Fix a deadlock that happens if the next element sends an event and the previous element sends a buffer where the queue is full. See the comment in the code for the rest.
This commit is contained in:
Ronald S. Bultje 2003-12-14 13:14:35 +00:00
parent 8cf0d17c3f
commit 9111ea764c
2 changed files with 58 additions and 20 deletions
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39
gst/gstqueue.c
View file

@ -377,6 +377,20 @@ gst_queue_locked_flush (GstQueue *queue)
g_cond_signal (queue->item_del); g_cond_signal (queue->item_del);
} }
static void
gst_queue_handle_pending_events (GstQueue *queue)
{
/* check for events to send upstream */
while (!g_queue_is_empty (queue->events)){
GstQueueEventResponse *er = g_queue_pop_head (queue->events);
GST_CAT_DEBUG_OBJECT (GST_CAT_DATAFLOW, queue, "sending event upstream");
er->ret = gst_pad_event_default (GST_PAD_PEER (queue->sinkpad), er->event);
er->handled = TRUE;
g_cond_signal (queue->event_done);
GST_CAT_DEBUG_OBJECT (GST_CAT_DATAFLOW, queue, "event sent");
}
}
#define STATUS(queue, msg) \ #define STATUS(queue, msg) \
GST_CAT_LOG_OBJECT (GST_CAT_DATAFLOW, queue, \ GST_CAT_LOG_OBJECT (GST_CAT_DATAFLOW, queue, \
"(%s:%s) " msg ": %u of %u-%u buffers, %u of %u-%u " \ "(%s:%s) " msg ": %u of %u-%u buffers, %u of %u-%u " \
@ -412,15 +426,7 @@ restart:
g_mutex_lock (queue->qlock); g_mutex_lock (queue->qlock);
GST_CAT_LOG_OBJECT (GST_CAT_DATAFLOW, queue, "locked t:%p", g_thread_self ()); GST_CAT_LOG_OBJECT (GST_CAT_DATAFLOW, queue, "locked t:%p", g_thread_self ());
/* check for events to send upstream */ gst_queue_handle_pending_events (queue);
while (!g_queue_is_empty (queue->events)){
GstQueueEventResponse *er = g_queue_pop_head (queue->events);
GST_CAT_DEBUG_OBJECT (GST_CAT_DATAFLOW, queue, "sending event upstream");
er->ret = gst_pad_event_default (GST_PAD_PEER (pad), er->event);
er->handled = TRUE;
g_cond_signal (queue->event_done);
GST_CAT_DEBUG_OBJECT (GST_CAT_DATAFLOW, queue, "event sent");
}
/* assume don't need to flush this buffer when the queue is filled */ /* assume don't need to flush this buffer when the queue is filled */
queue->flush = FALSE; queue->flush = FALSE;
@ -569,6 +575,14 @@ restart:
} }
} }
/* OK, we've got a serious issue here. Imagine the situation
* where the puller (next element) is sending an event here,
* so it cannot pull events from the queue, and we cannot
* push data further because the queue is 'full' and therefore,
* we wait here (and do not handle events): deadlock! to solve
* that, we handle pending upstream events here, too. */
gst_queue_handle_pending_events (queue);
STATUS (queue, "waiting for item_del signal"); STATUS (queue, "waiting for item_del signal");
g_cond_wait (queue->item_del, queue->qlock); g_cond_wait (queue->item_del, queue->qlock);
STATUS (queue, "received item_del signal"); STATUS (queue, "received item_del signal");
@ -719,7 +733,6 @@ restart:
GST_CAT_LOG_OBJECT (GST_CAT_DATAFLOW, queue, "signalling item_del"); GST_CAT_LOG_OBJECT (GST_CAT_DATAFLOW, queue, "signalling item_del");
g_cond_signal (queue->item_del); g_cond_signal (queue->item_del);
g_mutex_unlock (queue->qlock); g_mutex_unlock (queue->qlock);
/* FIXME: I suppose this needs to be locked, since the EOS /* FIXME: I suppose this needs to be locked, since the EOS
@ -759,9 +772,15 @@ gst_queue_handle_src_event (GstPad *pad,
er.event = event; er.event = event;
er.handled = FALSE; er.handled = FALSE;
g_queue_push_tail (queue->events, &er); g_queue_push_tail (queue->events, &er);
GST_CAT_WARNING_OBJECT (GST_CAT_DATAFLOW, queue,
"Preparing for loop for event handler");
/* see the chain function on why this is here - it prevents a deadlock */
g_cond_signal (queue->item_del);
while (!er.handled) { while (!er.handled) {
g_cond_wait (queue->event_done, queue->qlock); g_cond_wait (queue->event_done, queue->qlock);
} }
GST_CAT_WARNING_OBJECT (GST_CAT_DATAFLOW, queue,
"Event handled");
res = er.ret; res = er.ret;
} else { } else {
res = gst_pad_event_default (pad, event); res = gst_pad_event_default (pad, event);

39
plugins/elements/gstqueue.c
View file

@ -377,6 +377,20 @@ gst_queue_locked_flush (GstQueue *queue)
g_cond_signal (queue->item_del); g_cond_signal (queue->item_del);
} }
static void
gst_queue_handle_pending_events (GstQueue *queue)
{
/* check for events to send upstream */
while (!g_queue_is_empty (queue->events)){
GstQueueEventResponse *er = g_queue_pop_head (queue->events);
GST_CAT_DEBUG_OBJECT (GST_CAT_DATAFLOW, queue, "sending event upstream");
er->ret = gst_pad_event_default (GST_PAD_PEER (queue->sinkpad), er->event);
er->handled = TRUE;
g_cond_signal (queue->event_done);
GST_CAT_DEBUG_OBJECT (GST_CAT_DATAFLOW, queue, "event sent");
}
}
#define STATUS(queue, msg) \ #define STATUS(queue, msg) \
GST_CAT_LOG_OBJECT (GST_CAT_DATAFLOW, queue, \ GST_CAT_LOG_OBJECT (GST_CAT_DATAFLOW, queue, \
"(%s:%s) " msg ": %u of %u-%u buffers, %u of %u-%u " \ "(%s:%s) " msg ": %u of %u-%u buffers, %u of %u-%u " \
@ -412,15 +426,7 @@ restart:
g_mutex_lock (queue->qlock); g_mutex_lock (queue->qlock);
GST_CAT_LOG_OBJECT (GST_CAT_DATAFLOW, queue, "locked t:%p", g_thread_self ()); GST_CAT_LOG_OBJECT (GST_CAT_DATAFLOW, queue, "locked t:%p", g_thread_self ());
/* check for events to send upstream */ gst_queue_handle_pending_events (queue);
while (!g_queue_is_empty (queue->events)){
GstQueueEventResponse *er = g_queue_pop_head (queue->events);
GST_CAT_DEBUG_OBJECT (GST_CAT_DATAFLOW, queue, "sending event upstream");
er->ret = gst_pad_event_default (GST_PAD_PEER (pad), er->event);
er->handled = TRUE;
g_cond_signal (queue->event_done);
GST_CAT_DEBUG_OBJECT (GST_CAT_DATAFLOW, queue, "event sent");
}
/* assume don't need to flush this buffer when the queue is filled */ /* assume don't need to flush this buffer when the queue is filled */
queue->flush = FALSE; queue->flush = FALSE;
@ -569,6 +575,14 @@ restart:
} }
} }
/* OK, we've got a serious issue here. Imagine the situation
* where the puller (next element) is sending an event here,
* so it cannot pull events from the queue, and we cannot
* push data further because the queue is 'full' and therefore,
* we wait here (and do not handle events): deadlock! to solve
* that, we handle pending upstream events here, too. */
gst_queue_handle_pending_events (queue);
STATUS (queue, "waiting for item_del signal"); STATUS (queue, "waiting for item_del signal");
g_cond_wait (queue->item_del, queue->qlock); g_cond_wait (queue->item_del, queue->qlock);
STATUS (queue, "received item_del signal"); STATUS (queue, "received item_del signal");
@ -719,7 +733,6 @@ restart:
GST_CAT_LOG_OBJECT (GST_CAT_DATAFLOW, queue, "signalling item_del"); GST_CAT_LOG_OBJECT (GST_CAT_DATAFLOW, queue, "signalling item_del");
g_cond_signal (queue->item_del); g_cond_signal (queue->item_del);
g_mutex_unlock (queue->qlock); g_mutex_unlock (queue->qlock);
/* FIXME: I suppose this needs to be locked, since the EOS /* FIXME: I suppose this needs to be locked, since the EOS
@ -759,9 +772,15 @@ gst_queue_handle_src_event (GstPad *pad,
er.event = event; er.event = event;
er.handled = FALSE; er.handled = FALSE;
g_queue_push_tail (queue->events, &er); g_queue_push_tail (queue->events, &er);
GST_CAT_WARNING_OBJECT (GST_CAT_DATAFLOW, queue,
"Preparing for loop for event handler");
/* see the chain function on why this is here - it prevents a deadlock */
g_cond_signal (queue->item_del);
while (!er.handled) { while (!er.handled) {
g_cond_wait (queue->event_done, queue->qlock); g_cond_wait (queue->event_done, queue->qlock);
} }
GST_CAT_WARNING_OBJECT (GST_CAT_DATAFLOW, queue,
"Event handled");
res = er.ret; res = er.ret;
} else { } else {
res = gst_pad_event_default (pad, event); res = gst_pad_event_default (pad, event);