pad: add variants of gst_pad_get_caps() that don't copy caps. Fixes #590941

In most places in core and baseclasses we just need the caps to do caps-
intersections. In that case ref'ed caps are enough (no need to copy).
This patch also switches the code to use the new functions.
API: gst_pad_get_caps_refed(), gst_pad_peer_get_caps_refed()

8 files changed, 97 insertions, 21 deletions

diff --git a/docs/gst/gstreamer-sections.txt b/docs/gst/gstreamer-sections.txt
index 9b712c3afb..c7b3d879fc 100644
--- a/docs/gst/gstreamer-sections.txt
+++ b/docs/gst/gstreamer-sections.txt
@@ -1343,6 +1343,7 @@ gst_pad_is_linked
 gst_pad_can_link
 
 gst_pad_get_caps
+gst_pad_get_caps_refed
 gst_pad_get_allowed_caps
 gst_pad_get_negotiated_caps
 gst_pad_get_pad_template_caps
@@ -1350,6 +1351,7 @@ gst_pad_set_caps
 
 gst_pad_get_peer
 gst_pad_peer_get_caps
+gst_pad_peer_get_caps_refed
 gst_pad_use_fixed_caps
 
 gst_pad_is_active
diff --git a/gst/gstghostpad.c b/gst/gstghostpad.c
index 6d52789a1c..4998718757 100644
--- a/gst/gstghostpad.c
+++ b/gst/gstghostpad.c
@@ -224,7 +224,7 @@ gst_proxy_pad_do_getcaps (GstPad * pad)
 
   if (target) {
     /* if we have a real target, proxy the call */
-    res = gst_pad_get_caps (target);
+    res = gst_pad_get_caps_refed (target);
 
     GST_DEBUG_OBJECT (pad, "get caps of target %s:%s : %" GST_PTR_FORMAT,
         GST_DEBUG_PAD_NAME (target), res);
diff --git a/gst/gstpad.c b/gst/gstpad.c
index 4d2232f87e..755a95ee91 100644
--- a/gst/gstpad.c
+++ b/gst/gstpad.c
@@ -2170,6 +2170,7 @@ gst_pad_get_caps_unlocked (GstPad * pad)
     goto done;
   }
 
+  /* this almost never happens */
   GST_CAT_DEBUG_OBJECT (GST_CAT_CAPS, pad, "pad has no caps");
   result = gst_caps_new_empty ();
 
@@ -2177,6 +2178,38 @@ done:
   return result;
 }
 
+/* FIXME-0.11: what about making this the default and using
+ * gst_caps_make_writable() explicitely where needed
+ */
+/**
+ * gst_pad_get_caps_refed:
+ * @pad: a  #GstPad to get the capabilities of.
+ *
+ * Gets the capabilities this pad can produce or consume. Preferred function if
+ * one only wants to read or intersect the caps.
+ *
+ * Returns: the caps of the pad with incremented ref-count.
+ *
+ * Since: 0.10.25
+ */
+GstCaps *
+gst_pad_get_caps_refed (GstPad * pad)
+{
+  GstCaps *result = NULL;
+
+  g_return_val_if_fail (GST_IS_PAD (pad), NULL);
+
+  GST_OBJECT_LOCK (pad);
+
+  GST_CAT_DEBUG_OBJECT (GST_CAT_CAPS, pad, "get pad caps");
+
+  result = gst_pad_get_caps_unlocked (pad);
+
+  GST_OBJECT_UNLOCK (pad);
+
+  return result;
+}
+
 /**
  * gst_pad_get_caps:
  * @pad: a  #GstPad to get the capabilities of.
@@ -2195,33 +2228,70 @@ done:
 GstCaps *
 gst_pad_get_caps (GstPad * pad)
 {
+  GstCaps *result = gst_pad_get_caps_refed (pad);
+
+  /* be sure that we have a copy */
+  if (G_LIKELY (result))
+    result = gst_caps_make_writable (result);
+
+  return result;
+}
+
+/* FIXME-0.11: what about making this the default and using
+ * gst_caps_make_writable() explicitely where needed
+ */
+/**
+ * gst_pad_peer_get_caps_refed:
+ * @pad: a  #GstPad to get the capabilities of.
+ *
+ * Gets the capabilities of the peer connected to this pad. Preferred function
+ * if one only wants to read or intersect the caps.
+ *
+ * Returns: the caps of the pad with incremented ref-count.
+ *
+ * Since: 0.10.25
+ */
+GstCaps *
+gst_pad_peer_get_caps_refed (GstPad * pad)
+{
+  GstPad *peerpad;
   GstCaps *result = NULL;
 
   g_return_val_if_fail (GST_IS_PAD (pad), NULL);
 
   GST_OBJECT_LOCK (pad);
 
-  GST_CAT_DEBUG_OBJECT (GST_CAT_CAPS, pad, "get pad caps");
-
-  result = gst_pad_get_caps_unlocked (pad);
+  GST_CAT_DEBUG_OBJECT (GST_CAT_CAPS, pad, "get peer caps");
 
-  /* be sure that we have a copy */
-  if (result)
-    result = gst_caps_make_writable (result);
+  peerpad = GST_PAD_PEER (pad);
+  if (G_UNLIKELY (peerpad == NULL))
+    goto no_peer;
 
+  gst_object_ref (peerpad);
   GST_OBJECT_UNLOCK (pad);
 
+  result = gst_pad_get_caps_refed (peerpad);
+
+  gst_object_unref (peerpad);
+
   return result;
+
+no_peer:
+  {
+    GST_OBJECT_UNLOCK (pad);
+    return NULL;
+  }
 }
 
 /**
  * gst_pad_peer_get_caps:
  * @pad: a  #GstPad to get the peer capabilities of.
  *
- * Gets the capabilities of the peer connected to this pad.
+ * Gets the capabilities of the peer connected to this pad. Similar to
+ * gst_pad_get_caps().
  *
- * Returns: the #GstCaps of the peer pad. This function returns a new caps, so
- * use gst_caps_unref to get rid of it. this function returns NULL if there is
+ * Returns: a newly allocated copy of the #GstCaps of the peer pad. Use
+ * gst_caps_unref() to get rid of it. This function returns %NULL if there is
  * no peer pad.
  */
 GstCaps *
@@ -2367,7 +2437,7 @@ gst_pad_acceptcaps_default (GstPad * pad, GstCaps * caps)
 
   GST_DEBUG_OBJECT (pad, "caps %" GST_PTR_FORMAT, caps);
 
-  allowed = gst_pad_get_caps (pad);
+  allowed = gst_pad_get_caps_refed (pad);
   if (!allowed)
     goto nothing_allowed;
 
@@ -2703,9 +2773,9 @@ gst_pad_get_allowed_caps (GstPad * pad)
 
   gst_object_ref (peer);
   GST_OBJECT_UNLOCK (pad);
-  mycaps = gst_pad_get_caps (pad);
+  mycaps = gst_pad_get_caps_refed (pad);
 
-  peercaps = gst_pad_get_caps (peer);
+  peercaps = gst_pad_get_caps_refed (peer);
   gst_object_unref (peer);
 
   caps = gst_caps_intersect (mycaps, peercaps);
diff --git a/gst/gstpad.h b/gst/gstpad.h
index e79adb2216..835ea0aacc 100644
--- a/gst/gstpad.h
+++ b/gst/gstpad.h
@@ -890,11 +890,13 @@ void			gst_pad_set_setcaps_function		(GstPad *pad, GstPadSetCapsFunction setcaps
 G_CONST_RETURN GstCaps*	gst_pad_get_pad_template_caps		(GstPad *pad);
 
 /* capsnego function for linked/unlinked pads */
+GstCaps *		gst_pad_get_caps_refed		(GstPad * pad);
 GstCaps *		gst_pad_get_caps			(GstPad * pad);
 void			gst_pad_fixate_caps			(GstPad * pad, GstCaps *caps);
 gboolean		gst_pad_accept_caps			(GstPad * pad, GstCaps *caps);
 gboolean		gst_pad_set_caps			(GstPad * pad, GstCaps *caps);
 
+GstCaps *		gst_pad_peer_get_caps_refed		(GstPad * pad);
 GstCaps *		gst_pad_peer_get_caps			(GstPad * pad);
 gboolean		gst_pad_peer_accept_caps		(GstPad * pad, GstCaps *caps);
 
diff --git a/gst/gstutils.c b/gst/gstutils.c
index d212f0f304..87a06a8407 100644
--- a/gst/gstutils.c
+++ b/gst/gstutils.c
@@ -2634,7 +2634,7 @@ intersect_caps_func (GstPad * pad, GValue * ret, GstPad * orig)
     GstCaps *peercaps, *existing;
 
     existing = g_value_get_pointer (ret);
-    peercaps = gst_pad_peer_get_caps (pad);
+    peercaps = gst_pad_peer_get_caps_refed (pad);
     if (G_LIKELY (peercaps)) {
       g_value_set_pointer (ret, gst_caps_intersect (existing, peercaps));
       gst_caps_unref (existing);
diff --git a/libs/gst/base/gstbasesrc.c b/libs/gst/base/gstbasesrc.c
index 91fc27b5db..8c78ba9503 100644
--- a/libs/gst/base/gstbasesrc.c
+++ b/libs/gst/base/gstbasesrc.c
@@ -2407,7 +2407,7 @@ gst_base_src_default_negotiate (GstBaseSrc * basesrc)
   gboolean result = FALSE;
 
   /* first see what is possible on our source pad */
-  thiscaps = gst_pad_get_caps (GST_BASE_SRC_PAD (basesrc));
+  thiscaps = gst_pad_get_caps_refed (GST_BASE_SRC_PAD (basesrc));
   GST_DEBUG_OBJECT (basesrc, "caps of src: %" GST_PTR_FORMAT, thiscaps);
   /* nothing or anything is allowed, we're done */
   if (thiscaps == NULL || gst_caps_is_any (thiscaps))
@@ -2417,7 +2417,7 @@ gst_base_src_default_negotiate (GstBaseSrc * basesrc)
     goto no_caps;
 
   /* get the peer caps */
-  peercaps = gst_pad_peer_get_caps (GST_BASE_SRC_PAD (basesrc));
+  peercaps = gst_pad_peer_get_caps_refed (GST_BASE_SRC_PAD (basesrc));
   GST_DEBUG_OBJECT (basesrc, "caps of peer: %" GST_PTR_FORMAT, peercaps);
   if (peercaps) {
     GstCaps *icaps;
diff --git a/libs/gst/base/gstbasetransform.c b/libs/gst/base/gstbasetransform.c
index 2e56962a85..19fbdfd47b 100644
--- a/libs/gst/base/gstbasetransform.c
+++ b/libs/gst/base/gstbasetransform.c
@@ -613,14 +613,14 @@ gst_base_transform_getcaps (GstPad * pad)
   otherpad = (pad == trans->srcpad) ? trans->sinkpad : trans->srcpad;
 
   /* we can do what the peer can */
-  caps = gst_pad_peer_get_caps (otherpad);
+  caps = gst_pad_peer_get_caps_refed (otherpad);
   if (caps) {
     GstCaps *temp;
     const GstCaps *templ;
 
     GST_DEBUG_OBJECT (pad, "peer caps  %" GST_PTR_FORMAT, caps);
 
-    /* filtered against our padtemplate */
+    /* filtered against our padtemplate on the other side */
     templ = gst_pad_get_pad_template_caps (otherpad);
     GST_DEBUG_OBJECT (pad, "our template  %" GST_PTR_FORMAT, templ);
     temp = gst_caps_intersect (caps, templ);
@@ -635,7 +635,7 @@ gst_base_transform_getcaps (GstPad * pad)
     if (caps == NULL)
       goto done;
 
-    /* and filter against the template again */
+    /* and filter against the template of this pad */
     templ = gst_pad_get_pad_template_caps (pad);
     GST_DEBUG_OBJECT (pad, "our template  %" GST_PTR_FORMAT, templ);
     temp = gst_caps_intersect (caps, templ);
@@ -856,7 +856,7 @@ gst_base_transform_find_transform (GstBaseTransform * trans, GstPad * pad,
 
     GST_DEBUG_OBJECT (trans, "othercaps now %" GST_PTR_FORMAT, othercaps);
 
-    peercaps = gst_pad_get_caps (otherpeer);
+    peercaps = gst_pad_get_caps_refed (otherpeer);
     intersect = gst_caps_intersect (peercaps, othercaps);
     gst_caps_unref (peercaps);
     gst_caps_unref (othercaps);
@@ -1002,7 +1002,7 @@ gst_base_transform_acceptcaps (GstPad * pad, GstCaps * caps)
     GST_DEBUG_OBJECT (pad, "non fixed accept caps %" GST_PTR_FORMAT, caps);
 
     /* get all the formats we can handle on this pad */
-    allowed = gst_pad_get_caps (pad);
+    allowed = gst_pad_get_caps_refed (pad);
     if (!allowed) {
       GST_DEBUG_OBJECT (pad, "gst_pad_get_caps() failed");
       goto no_transform_possible;
diff --git a/win32/common/libgstreamer.def b/win32/common/libgstreamer.def
index d3567d3c66..0a6bf6896b 100644
--- a/win32/common/libgstreamer.def
+++ b/win32/common/libgstreamer.def
@@ -586,6 +586,7 @@ EXPORTS
 	gst_pad_flags_get_type
 	gst_pad_get_allowed_caps
 	gst_pad_get_caps
+	gst_pad_get_caps_refed
 	gst_pad_get_direction
 	gst_pad_get_element_private
 	gst_pad_get_fixed_caps_func
@@ -615,6 +616,7 @@ EXPORTS
 	gst_pad_pause_task
 	gst_pad_peer_accept_caps
 	gst_pad_peer_get_caps
+	gst_pad_peer_get_caps_refed
 	gst_pad_peer_query
 	gst_pad_presence_get_type
 	gst_pad_proxy_getcaps