gst-launch: add a sync bus handler and move state-change logging there

The sync handler is called for all mesages, the event loop we previously used
was not. In the sync handler trigger pipeline dot dumps and call access for a
file in tmp-dir to add markers interceptable by strace and co.

1 files changed, 50 insertions, 12 deletions

diff --git a/tools/gst-launch.c b/tools/gst-launch.c
index e8f4bacf3..6ff3ed763 100644
--- a/tools/gst-launch.c
+++ b/tools/gst-launch.c
@@ -560,22 +560,10 @@ event_loop (GstElement * pipeline, gboolean blocking, GstState target_state)
       case GST_MESSAGE_STATE_CHANGED:{
         GstState old, new, pending;
 
-        gst_message_parse_state_changed (message, &old, &new, &pending);
-
         /* we only care about pipeline state change messages */
         if (GST_MESSAGE_SRC (message) != GST_OBJECT_CAST (pipeline))
           break;
 
-        /* dump graph for pipeline state changes */
-        {
-          gchar *dump_name = g_strdup_printf ("gst-launch.%s_%s",
-              gst_element_state_get_name (old),
-              gst_element_state_get_name (new));
-          GST_DEBUG_BIN_TO_DOT_FILE_WITH_TS (GST_BIN (pipeline),
-              GST_DEBUG_GRAPH_SHOW_ALL, dump_name);
-          g_free (dump_name);
-        }
-
         /* ignore when we are buffering since then we mess with the states
          * ourselves. */
         if (buffering) {
@@ -583,6 +571,8 @@ event_loop (GstElement * pipeline, gboolean blocking, GstState target_state)
           break;
         }
 
+        gst_message_parse_state_changed (message, &old, &new, &pending);
+
         /* if we reached the final target state, exit */
         if (target_state == GST_STATE_PAUSED && new == target_state)
           goto exit;
@@ -675,6 +665,48 @@ exit:
   }
 }
 
+static GstBusSyncReply
+bus_sync_handler (GstBus * bus, GstMessage * message, gpointer data)
+{
+  GstElement *pipeline = (GstElement *) data;
+
+  switch (GST_MESSAGE_TYPE (message)) {
+    case GST_MESSAGE_STATE_CHANGED:
+      /* we only care about pipeline state change messages */
+      if (GST_MESSAGE_SRC (message) == GST_OBJECT_CAST (pipeline)) {
+        GstState old, new, pending;
+        gchar *state_transition_name;
+
+        gst_message_parse_state_changed (message, &old, &new, &pending);
+
+        state_transition_name = g_strdup_printf ("%s_%s",
+            gst_element_state_get_name (old), gst_element_state_get_name (new));
+
+        /* dump graph for (some) pipeline state changes */
+        {
+          gchar *dump_name = g_strconcat ("gst-launch.", state_transition_name,
+              NULL);
+          GST_DEBUG_BIN_TO_DOT_FILE_WITH_TS (GST_BIN (pipeline),
+              GST_DEBUG_GRAPH_SHOW_ALL, dump_name);
+          g_free (dump_name);
+        }
+
+        /* place a marker into e.g. strace logs */
+        {
+          gchar *access_name = g_strconcat (g_get_tmp_dir (), G_DIR_SEPARATOR_S,
+              "gst-launch", G_DIR_SEPARATOR_S, state_transition_name, NULL);
+          access (access_name, R_OK);
+          g_free (access_name);
+        }
+
+        g_free (state_transition_name);
+      }
+    default:
+      break;
+  }
+  return GST_BUS_PASS;
+}
+
 int
 main (int argc, char *argv[])
 {
@@ -822,6 +854,7 @@ main (int argc, char *argv[])
   if (!savefile) {
     GstState state, pending;
     GstStateChangeReturn ret;
+    GstBus *bus;
 
     /* If the top-level object is not a pipeline, place it in a pipeline. */
     if (!GST_IS_PIPELINE (pipeline)) {
@@ -834,6 +867,11 @@ main (int argc, char *argv[])
       gst_bin_add (GST_BIN (real_pipeline), pipeline);
       pipeline = real_pipeline;
     }
+
+    bus = gst_element_get_bus (pipeline);
+    gst_bus_set_sync_handler (bus, bus_sync_handler, (gpointer) pipeline);
+    gst_object_unref (bus);
+
     PRINT (_("Setting pipeline to PAUSED ...\n"));
     ret = gst_element_set_state (pipeline, GST_STATE_PAUSED);