From 9f3b0b8f3aa4e983db5962423ada7945b4f59a35 Mon Sep 17 00:00:00 2001
From: Wim Taymans <wim.taymans@gmail.com>
Date: Wed, 21 Mar 2007 11:52:04 +0000
Subject: [PATCH] gst/gstbin.c: Prepare for release where we warn against
 possible app breakage in the case of live pipelines along wit...

Original commit message from CVS:
* gst/gstbin.c: (gst_bin_get_type), (gst_bin_element_set_state):
Prepare for release where we warn against possible app breakage in the
case of live pipelines along with an env var to enable/disable live
preroll mode (GST_COMPAT=[no-]live-preroll).
---
 ChangeLog    |  7 +++++++
 gst/gstbin.c | 35 ++++++++++++++++++++++++++++++++++-
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index ec084a5e1b..ad6eebf8d6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2007-03-21  Wim Taymans  <wim@fluendo.com>
+
+	* gst/gstbin.c: (gst_bin_get_type), (gst_bin_element_set_state):
+	Prepare for release where we warn against possible app breakage in the
+	case of live pipelines along with an env var to enable/disable live
+	preroll mode (GST_COMPAT=[no-]live-preroll).
+
 2007-03-20  Zaheer Abbas Merali  <zaheerabbas at merali dot org>
 
 	* plugins/elements/gstidentity.c (gst_identity_check_imperfect_offset):
diff --git a/gst/gstbin.c b/gst/gstbin.c
index 9eab23aaf7..78a6d15da6 100644
--- a/gst/gstbin.c
+++ b/gst/gstbin.c
@@ -176,6 +176,16 @@
  * their duration when it changes so we return inaccurate values. */
 #undef DURATION_CACHING
 
+/* latency is by default disabled for non CVS for now.
+ * live-preroll and no-live-preroll in the environment var GST_COMPAT
+ * to enables or disable it respectively.
+ */
+#if GST_VERSION_NANO == 1
+static gboolean enable_latency = TRUE;
+#else
+static gboolean enable_latency = FALSE;
+#endif
+
 GST_DEBUG_CATEGORY_STATIC (bin_debug);
 #define GST_CAT_DEFAULT bin_debug
 
@@ -253,6 +263,7 @@ GType
 gst_bin_get_type (void)
 {
   static GType gst_bin_type = 0;
+  const gchar *compat;
 
   if (G_UNLIKELY (gst_bin_type == 0)) {
     static const GTypeInfo bin_info = {
@@ -281,6 +292,15 @@ gst_bin_get_type (void)
 
     GST_DEBUG_CATEGORY_INIT (bin_debug, "bin", GST_DEBUG_BOLD,
         "debugging info for the 'bin' container element");
+
+    /* compatibility stuff */
+    compat = g_getenv ("GST_COMPAT");
+    if (compat != NULL) {
+      if (strstr (compat, "no-live-preroll"))
+        enable_latency = FALSE;
+      else if (strstr (compat, "live-preroll"))
+        enable_latency = TRUE;
+    }
   }
   return gst_bin_type;
 }
@@ -1824,12 +1844,25 @@ gst_bin_element_set_state (GstBin * bin, GstElement * element,
     GstMessage *message = GST_MESSAGE_CAST (found->data);
     GstObject *src = GST_MESSAGE_SRC (message);
 
+
     GST_DEBUG_OBJECT (element, "element message %p, %s async busy",
         message, GST_ELEMENT_NAME (src));
     /* only wait for upward state changes */
-    if (next > current)
+    if (next > current) {
+      /* We found an async element check if we can force its state to change or
+       * if we have to wait for it to preroll. */
+      if (G_UNLIKELY (!enable_latency)) {
+        g_warning ("Future versions of GStreamer will wait for element \"%s\"\n"
+            "\tto preroll in order to perform correct latency calculations.\n"
+            "\tPlease verify that the application continues to work correctly by\n"
+            "\tsetting the environment variable GST_COMPAT to a value containing\n"
+            "\tthe string 'live-preroll'.", GST_ELEMENT_NAME (element));
+        goto no_latency;
+      }
       goto was_busy;
+    }
   }
+no_latency:
   GST_OBJECT_UNLOCK (bin);
 
   GST_DEBUG_OBJECT (bin,