[mutter/gnome-3-36] screen-cast-src: Notify about the stream being closed after dispatch

[Jonas Ådahl <jadahl src gnome org>]

commit 63fc71f05bebca6a247db783c3a7672ed574dea7
Author: Jonas Ådahl <jadahl gmail com>
Date:   Tue May 12 16:14:00 2020 +0200

    screen-cast-src: Notify about the stream being closed after dispatch
    
    We're iterating inside the PipeWire loop when detecting PipeWire errors,
    and shouldn't destroy the PipeWire objects mid-iteration. Avoid this by
    first disabling the stream src (effectively stopping the recording),
    then notifying about it being closed in an idle callback. The
    notification eventually makes the rest of the screen cast code clean up
    the objects, including the src and the associated PipeWire objects, but
    will do so outside the PipeWire loop iteration.
    
    Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/1251
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1251
    (cherry picked from commit c8e12ead08fd8ee8593b033c1f1a624f94a47ed9)

 src/backends/meta-screen-cast-stream-src.c | 31 ++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)
---
diff --git a/src/backends/meta-screen-cast-stream-src.c b/src/backends/meta-screen-cast-stream-src.c
index ad0d9ed79..c614f06fe 100644
--- a/src/backends/meta-screen-cast-stream-src.c
+++ b/src/backends/meta-screen-cast-stream-src.c
@@ -68,6 +68,7 @@ typedef struct _MetaPipeWireSource
 {
   GSource base;
 
+  MetaScreenCastStreamSrc *src;
   struct pw_loop *pipewire_loop;
 } MetaPipeWireSource;
 
@@ -81,6 +82,7 @@ typedef struct _MetaScreenCastStreamSrcPrivate
   struct spa_hook pipewire_core_listener;
 
   gboolean is_enabled;
+  gboolean emit_closed_after_dispatch;
 
   struct pw_stream *pipewire_stream;
   struct spa_hook pipewire_stream_listener;
@@ -540,12 +542,6 @@ meta_screen_cast_stream_src_disable (MetaScreenCastStreamSrc *src)
   priv->is_enabled = FALSE;
 }
 
-static void
-meta_screen_cast_stream_src_notify_closed (MetaScreenCastStreamSrc *src)
-{
-  g_signal_emit (src, signals[CLOSED], 0);
-}
-
 static void
 on_stream_state_changed (void                 *data,
                          enum pw_stream_state  old,
@@ -560,7 +556,9 @@ on_stream_state_changed (void                 *data,
     {
     case PW_STREAM_STATE_ERROR:
       g_warning ("pipewire stream error: %s", error_message);
-      meta_screen_cast_stream_src_notify_closed (src);
+      if (meta_screen_cast_stream_src_is_enabled (src))
+        meta_screen_cast_stream_src_disable (src);
+      priv->emit_closed_after_dispatch = TRUE;
       break;
     case PW_STREAM_STATE_PAUSED:
       if (priv->node_id == SPA_ID_INVALID && priv->pipewire_stream)
@@ -828,11 +826,17 @@ on_core_error (void       *data,
               const char *message)
 {
   MetaScreenCastStreamSrc *src = data;
+  MetaScreenCastStreamSrcPrivate *priv =
+    meta_screen_cast_stream_src_get_instance_private (src);
 
   g_warning ("pipewire remote error: id:%u %s", id, message);
 
   if (id == PW_ID_CORE && res == -EPIPE)
-    meta_screen_cast_stream_src_notify_closed (src);
+    {
+      if (meta_screen_cast_stream_src_is_enabled (src))
+        meta_screen_cast_stream_src_disable (src);
+      priv->emit_closed_after_dispatch = TRUE;
+    }
 }
 
 static gboolean
@@ -849,12 +853,18 @@ pipewire_loop_source_dispatch (GSource     *source,
                                gpointer     user_data)
 {
   MetaPipeWireSource *pipewire_source = (MetaPipeWireSource *) source;
+  MetaScreenCastStreamSrc *src = pipewire_source->src;
+  MetaScreenCastStreamSrcPrivate *priv =
+    meta_screen_cast_stream_src_get_instance_private (src);
   int result;
 
   result = pw_loop_iterate (pipewire_source->pipewire_loop, 0);
   if (result < 0)
     g_warning ("pipewire_loop_iterate failed: %s", spa_strerror (result));
 
+  if (priv->emit_closed_after_dispatch)
+    g_signal_emit (src, signals[CLOSED], 0);
+
   return TRUE;
 }
 
@@ -876,13 +886,14 @@ static GSourceFuncs pipewire_source_funcs =
 };
 
 static MetaPipeWireSource *
-create_pipewire_source (void)
+create_pipewire_source (MetaScreenCastStreamSrc *src)
 {
   MetaPipeWireSource *pipewire_source;
 
   pipewire_source =
     (MetaPipeWireSource *) g_source_new (&pipewire_source_funcs,
                                          sizeof (MetaPipeWireSource));
+  pipewire_source->src = src;
   pipewire_source->pipewire_loop = pw_loop_new (NULL);
   if (!pipewire_source->pipewire_loop)
     {
@@ -914,7 +925,7 @@ meta_screen_cast_stream_src_initable_init (GInitable     *initable,
   MetaScreenCastStreamSrcPrivate *priv =
     meta_screen_cast_stream_src_get_instance_private (src);
 
-  priv->pipewire_source = create_pipewire_source ();
+  priv->pipewire_source = create_pipewire_source (src);
   if (!priv->pipewire_source)
     {
       g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,