x11: don't block in buffer acquire

Don't ever block when acquiring a buffer from the bufferpool in the fallback
mode. If we block, we might deadlock when going to PAUSED because we never
unlock when going to paused.

The acquire can block when there are no more buffers in the pool, this is a
sign that the pool is too small. Since we are the only ones using the pool in
the fallback case and because we scale the buffer, someone else must be using
our pool as well and is doing something bad.

2 files changed, 16 insertions, 8 deletions

diff --git a/sys/ximage/ximagesink.c b/sys/ximage/ximagesink.c
index 6fa3a35e6..1540d962d 100644
--- a/sys/ximage/ximagesink.c
+++ b/sys/ximage/ximagesink.c
@@ -1312,6 +1312,7 @@ gst_ximagesink_show_frame (GstVideoSink * vsink, GstBuffer * buf)
     res = GST_FLOW_OK;
   } else {
     GstVideoFrame src, dest;
+    GstBufferPoolAcquireParams params = { 0, };
 
     /* Else we have to copy the data into our private image, */
     /* if we have one... */
@@ -1324,8 +1325,11 @@ gst_ximagesink_show_frame (GstVideoSink * vsink, GstBuffer * buf)
     if (!gst_buffer_pool_set_active (ximagesink->pool, TRUE))
       goto activate_failed;
 
-    /* take a buffer from our pool */
-    res = gst_buffer_pool_acquire_buffer (ximagesink->pool, &to_put, NULL);
+    /* take a buffer from our pool, if there is no buffer in the pool something
+     * is seriously wrong, waiting for the pool here might deadlock when we try
+     * to go to PAUSED because we never flush the pool. */
+    params.flags = GST_BUFFER_POOL_ACQUIRE_FLAG_DONTWAIT;
+    res = gst_buffer_pool_acquire_buffer (ximagesink->pool, &to_put, &params);
     if (res != GST_FLOW_OK)
       goto no_buffer;
 
@@ -1367,12 +1371,12 @@ no_buffer:
   {
     /* No image available. That's very bad ! */
     GST_WARNING_OBJECT (ximagesink, "could not create image");
-    return res;
+    return GST_FLOW_OK;
   }
 invalid_buffer:
   {
     /* No Window available to put our image into */
-    GST_WARNING_OBJECT (ximagesink, "could map image");
+    GST_WARNING_OBJECT (ximagesink, "could not map image");
     res = GST_FLOW_OK;
     goto done;
   }
diff --git a/sys/xvimage/xvimagesink.c b/sys/xvimage/xvimagesink.c
index e631b2a03..c766d2510 100644
--- a/sys/xvimage/xvimagesink.c
+++ b/sys/xvimage/xvimagesink.c
@@ -1831,6 +1831,7 @@ gst_xvimagesink_show_frame (GstVideoSink * vsink, GstBuffer * buf)
     res = GST_FLOW_OK;
   } else {
     GstVideoFrame src, dest;
+    GstBufferPoolAcquireParams params = { 0, };
 
     /* Else we have to copy the data into our private image, */
     /* if we have one... */
@@ -1843,8 +1844,11 @@ gst_xvimagesink_show_frame (GstVideoSink * vsink, GstBuffer * buf)
     if (!gst_buffer_pool_set_active (xvimagesink->pool, TRUE))
       goto activate_failed;
 
-    /* take a buffer from our pool */
-    res = gst_buffer_pool_acquire_buffer (xvimagesink->pool, &to_put, NULL);
+    /* take a buffer from our pool, if there is no buffer in the pool something
+     * is seriously wrong, waiting for the pool here might deadlock when we try
+     * to go to PAUSED because we never flush the pool then. */
+    params.flags = GST_BUFFER_POOL_ACQUIRE_FLAG_DONTWAIT;
+    res = gst_buffer_pool_acquire_buffer (xvimagesink->pool, &to_put, &params);
     if (res != GST_FLOW_OK)
       goto no_buffer;
 
@@ -1886,12 +1890,12 @@ no_buffer:
   {
     /* No image available. That's very bad ! */
     GST_WARNING_OBJECT (xvimagesink, "could not create image");
-    return res;
+    return GST_FLOW_OK;
   }
 invalid_buffer:
   {
     /* No Window available to put our image into */
-    GST_WARNING_OBJECT (xvimagesink, "could map image");
+    GST_WARNING_OBJECT (xvimagesink, "could not map image");
     res = GST_FLOW_OK;
     goto done;
   }