Changeset 3847

Timestamp:

Oct 25, 2011 4:36:46 AM (13 years ago)

Author:

bennylp

Message:

More #1394: fixed deadlock when format change is reported by vid_stream, which cause the clock to stop. It waits for the callback to return, but the callback is waiting to lock the jb_mutex, which is currently being held by the stopping clock. The workaround is to queue the event and report it later

File:

• pjproject/trunk/pjmedia/src/pjmedia/vid_stream.c (modified) (3 diffs)

pjproject/trunk/pjmedia/src/pjmedia/vid_stream.c

@@ -122 +122 @@
     unsigned                 dec_max_size;  /**< Size of decoded/raw picture*/
     pjmedia_frame            dec_frame;     /**< Current decoded frame.     */
+    pjmedia_event            fmt_event;     /**< Buffered fmt_changed event
+                                                 to avoid deadlock          */
 
     unsigned                 frame_size;    /**< Size of encoded base frame.*/
@@ -347 +349 @@
         switch (event->type) {
         case PJMEDIA_EVENT_FMT_CHANGED:
-            /* Update param from codec */
-            pjmedia_vid_codec_get_param(stream->codec, stream->info.codec_param);
-
-            /* Update decoding channel port info */
-            pjmedia_format_copy(&stream->dec->port.info.fmt,
-                                &stream->info.codec_param->dec_fmt);
-
             /* we process the event */
             ++event->proc_cnt;
 
-            dump_port_info(event->data.fmt_changed.dir==PJMEDIA_DIR_DECODING ?
-                            stream->dec : stream->enc,
-                          "changed");
-            break;
+            /* Copy the event to avoid deadlock if we publish the event
+             * now. This happens because fmt_event may trigger restart
+             * while we're still holding the jb_mutex.
+             */
+            pj_memcpy(&stream->fmt_event, event, sizeof(*event));
+            return PJ_SUCCESS;
         default:
             break;
@@ -1071 +1068 @@
         frame->size = 0;
         return PJ_SUCCESS;
+    }
+
+    /* Report pending events. Do not publish the event while holding the
+     * jb_mutex as that would lead to deadlock. It should be safe to
+     * operate on fmt_event without the mutex because format change normally
+     * would only occur once during the start of the media.
+     */
+    if (stream->fmt_event.type != PJMEDIA_EVENT_NONE) {
+        /* Update param from codec */
+        pjmedia_vid_codec_get_param(stream->codec, stream->info.codec_param);
+
+        /* Update decoding channel port info */
+        pjmedia_format_copy(&stream->dec->port.info.fmt,
+                            &stream->info.codec_param->dec_fmt);
+
+        dump_port_info(stream->fmt_event.data.fmt_changed.dir==PJMEDIA_DIR_DECODING ?
+                        stream->dec : stream->enc,
+                      "changed");
+
+        pjmedia_event_publish(&stream->epub, &stream->fmt_event);
+
+        stream->fmt_event.type = PJMEDIA_EVENT_NONE;
     }