From c41b0ade28790ffdb0e484b41cd7929c4e145dec Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20Dr=C3=B6ge?= <sebastian.droege@collabora.co.uk>
Date: Thu, 7 Apr 2011 11:19:57 +0200
Subject: [PATCH] bus: Use a construct-only property to distinguish between
 child buses and normal buses

This allows to only create the socketpair when it is really required instead
of always creating it and immediately destroying it again for child buses.

https://bugzilla.gnome.org/show_bug.cgi?id=647005
---
 gst/gst_private.h |  8 ------
 gst/gstbin.c      |  3 +--
 gst/gstbus.c      | 69 ++++++++++++++++++++++++++++++++++++++---------
 3 files changed, 57 insertions(+), 23 deletions(-)

diff --git a/gst/gst_private.h b/gst/gst_private.h
index 487a547da1..da8a50a80c 100644
--- a/gst/gst_private.h
+++ b/gst/gst_private.h
@@ -51,9 +51,6 @@ extern const char             g_log_domain_gstreamer[];
 /* for the pad cache */
 #include "gstpad.h"
 
-/* for GstBus */
-#include "gstbus.h"
-
 G_BEGIN_DECLS
 
 /* used by gstparse.c and grammar.y */
@@ -139,11 +136,6 @@ gint priv_gst_date_time_compare (gconstpointer dt1, gconstpointer dt2);
 extern gboolean _gst_disable_registry_cache;
 #endif
 
-/* Secret API used by GstBin to set the bus in child bus mode
- * without sockets and everything. See bug #646624.
- */
-void _priv_gst_bus_set_child_mode (GstBus * bus);
-
 /* provide inline gst_g_value_get_foo_unchecked(), used in gststructure.c */
 #define DEFINE_INLINE_G_VALUE_GET_UNCHECKED(ret_type,name_type,v_field) \
 static inline ret_type                                                  \
diff --git a/gst/gstbin.c b/gst/gstbin.c
index ee8c98bdf1..d4375f843c 100644
--- a/gst/gstbin.c
+++ b/gst/gstbin.c
@@ -540,12 +540,11 @@ gst_bin_init (GstBin * bin, GstBinClass * klass)
   bin->clock_dirty = FALSE;
 
   /* Set up a bus for listening to child elements */
-  bus = gst_bus_new ();
+  bus = g_object_new (GST_TYPE_BUS, "enable-async", FALSE, NULL);
   bin->child_bus = bus;
   GST_DEBUG_OBJECT (bin, "using bus %" GST_PTR_FORMAT " to listen to children",
       bus);
   gst_bus_set_sync_handler (bus, (GstBusSyncHandler) bin_bus_handler, bin);
-  _priv_gst_bus_set_child_mode (bus);
 
   bin->priv = GST_BIN_GET_PRIVATE (bin);
   bin->priv->asynchandling = DEFAULT_ASYNC_HANDLING;
diff --git a/gst/gstbus.c b/gst/gstbus.c
index e2d6220f0d..c102fb9585 100644
--- a/gst/gstbus.c
+++ b/gst/gstbus.c
@@ -89,6 +89,14 @@ enum
   LAST_SIGNAL
 };
 
+#define DEFAULT_ENABLE_ASYNC (TRUE)
+
+enum
+{
+  PROP_0,
+  PROP_ENABLE_ASYNC
+};
+
 static void gst_bus_dispose (GObject * object);
 
 static GstObjectClass *parent_class = NULL;
@@ -100,6 +108,7 @@ struct _GstBusPrivate
   GCond *queue_cond;
   GSource *watch_id;
 
+  gboolean enable_async;
   GstPoll *poll;
   GPollFD pollfd;
 };
@@ -134,6 +143,33 @@ marshal_VOID__MINIOBJECT (GClosure * closure, GValue * return_value,
   callback (data1, gst_value_get_mini_object (param_values + 1), data2);
 }
 
+static void
+gst_bus_set_property (GObject * object,
+    guint prop_id, const GValue * value, GParamSpec * pspec)
+{
+  GstBus *bus = GST_BUS_CAST (object);
+
+  switch (prop_id) {
+    case PROP_ENABLE_ASYNC:
+      bus->priv->enable_async = g_value_get_boolean (value);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+static void
+gst_bus_constructed (GObject * object)
+{
+  GstBus *bus = GST_BUS_CAST (object);
+
+  if (bus->priv->enable_async) {
+    bus->priv->poll = gst_poll_new_timer ();
+    gst_poll_get_read_gpollfd (bus->priv->poll, &bus->priv->pollfd);
+  }
+}
+
 static void
 gst_bus_class_init (GstBusClass * klass)
 {
@@ -142,6 +178,25 @@ gst_bus_class_init (GstBusClass * klass)
   parent_class = g_type_class_peek_parent (klass);
 
   gobject_class->dispose = gst_bus_dispose;
+  gobject_class->set_property = gst_bus_set_property;
+  gobject_class->constructed = gst_bus_constructed;
+
+  /* GstBus:enable-async:
+   *
+   * Enable async message delivery support for bus watches,
+   * gst_bus_pop() and similar API. Without this only the
+   * synchronous message handlers are called.
+   *
+   * This property is used to create the child element buses
+   * in #GstBin.
+   *
+   * Since: 0.10.33
+   */
+  g_object_class_install_property (gobject_class, PROP_ENABLE_ASYNC,
+      g_param_spec_boolean ("enable-async", "Enable Async",
+          "Enable async message delivery for bus watches and gst_bus_pop()",
+          DEFAULT_ENABLE_ASYNC,
+          G_PARAM_CONSTRUCT_ONLY | G_PARAM_WRITABLE | G_PARAM_STATIC_STRINGS));
 
   /**
    * GstBus::sync-message:
@@ -191,8 +246,7 @@ gst_bus_init (GstBus * bus)
   bus->priv = G_TYPE_INSTANCE_GET_PRIVATE (bus, GST_TYPE_BUS, GstBusPrivate);
   bus->priv->queue_cond = g_cond_new ();
 
-  bus->priv->poll = gst_poll_new_timer ();
-  gst_poll_get_read_gpollfd (bus->priv->poll, &bus->priv->pollfd);
+  bus->priv->enable_async = DEFAULT_ENABLE_ASYNC;
 
   GST_DEBUG_OBJECT (bus, "created");
 }
@@ -1285,14 +1339,3 @@ error:
     return;
   }
 }
-
-/* Secret API used by GstBin to set the bus in child bus mode
- * without sockets and everything. See bug #646624.
- */
-void
-_priv_gst_bus_set_child_mode (GstBus * bus)
-{
-  if (bus->priv->poll)
-    gst_poll_free (bus->priv->poll);
-  bus->priv->poll = NULL;
-}