bin: add flag to disable resync state change

Add a GST_BIN_FLAG_NO_RESYNC that disables a resync when an element is added,
removed or linked in the bin. This is interesting for complex bins that
dynamically add elements to themselves and want to manage the state of those
elements without interference from resyncs.

See https://bugzilla.gnome.org/show_bug.cgi?id=690420

diff --git a/gst/gstbin.c b/gst/gstbin.c
index 13b1f9f..b0450b0 100644 (file)
--- a/gst/gstbin.c
+++ b/gst/gstbin.c
@@ -1126,7 +1126,8 @@ gst_bin_add_func (GstBin * bin, GstElement * element)
   bin->children = g_list_prepend (bin->children, element);
   bin->numchildren++;
   bin->children_cookie++;
-  bin->priv->structure_cookie++;
+  if (!GST_BIN_IS_NO_RESYNC (bin))
+    bin->priv->structure_cookie++;
 
   /* distribute the bus */
   gst_element_set_bus (element, bin->child_bus);
@@ -1372,7 +1373,8 @@ gst_bin_remove_func (GstBin * bin, GstElement * element)
    * so that others can detect a change in the children list. */
   bin->numchildren--;
   bin->children_cookie++;
-  bin->priv->structure_cookie++;
+  if (!GST_BIN_IS_NO_RESYNC (bin))
+    bin->priv->structure_cookie++;
 
   if (is_sink && !othersink) {
     /* we're not a sink anymore */
@@ -3553,7 +3555,8 @@ gst_bin_handle_message_func (GstBin * bin, GstMessage * message)
          * need to resync by updating the structure_cookie. */
         bin_remove_messages (bin, GST_MESSAGE_SRC (message),
             GST_MESSAGE_STRUCTURE_CHANGE);
-        bin->priv->structure_cookie++;
+        if (!GST_BIN_IS_NO_RESYNC (bin))
+          bin->priv->structure_cookie++;
       }
       GST_OBJECT_UNLOCK (bin);
 

diff --git a/gst/gstbin.h b/gst/gstbin.h
index 5bfb1a3..17d1441 100644 (file)
--- a/gst/gstbin.h
+++ b/gst/gstbin.h
@@ -40,6 +40,8 @@ G_BEGIN_DECLS
 
 /**
  * GstBinFlags:
+ * @GST_BIN_FLAG_NO_RESYNC: don't resync a state change when elements are
+ *             added or linked in the bin.
  * @GST_BIN_FLAG_LAST: the last enum in the series of flags for bins.
  * Derived classes can use this as first value in a list of flags.
  *
@@ -48,10 +50,22 @@ G_BEGIN_DECLS
  * and (un)set using GST_OBJECT_FLAG_SET () and GST_OBJECT_FLAG_UNSET ().
  */
 typedef enum {
+  GST_BIN_FLAG_NO_RESYNC       = (GST_ELEMENT_FLAG_LAST << 0),
   /* padding */
   GST_BIN_FLAG_LAST            = (GST_ELEMENT_FLAG_LAST << 5)
 } GstBinFlags;
 
+/**
+ * GST_BIN_IS_NO_RESYNC:
+ * @bin: A #GstBin
+ *
+ * Check if @bin will resync its state change when elements are added and
+ * removed.
+ *
+ * Since: 1.1.1
+ */
+#define GST_BIN_IS_NO_RESYNC(bin)        (GST_OBJECT_FLAG_IS_SET(bin,GST_BIN_FLAG_NO_RESYNC))
+
 typedef struct _GstBin GstBin;
 typedef struct _GstBinClass GstBinClass;
 typedef struct _GstBinPrivate GstBinPrivate;