tee: Add allow-not-linked property

This property avoids not linked error when all the pads are unlinked
or when there are no source pads. This is useful in dynamic pipelines
where it can happen that for a short time there are no pads at all or
all downstream pads are not linked yet.

https://bugzilla.gnome.org/show_bug.cgi?id=746436

plugins/elements/gsttee.c

@@ -84,6 +84,7 @@ gst_tee_pull_mode_get_type (void)
 #define DEFAULT_PROP_SILENT		TRUE
 #define DEFAULT_PROP_LAST_MESSAGE	NULL
 #define DEFAULT_PULL_MODE		GST_TEE_PULL_MODE_NEVER
+#define DEFAULT_PROP_ALLOW_NOT_LINKED	FALSE
 
 enum
 {
@@ -94,6 +95,7 @@ enum
   PROP_LAST_MESSAGE,
   PROP_PULL_MODE,
   PROP_ALLOC_PAD,
+  PROP_ALLOW_NOT_LINKED,
 };
 
 static GstStaticPadTemplate tee_src_template =
@@ -265,6 +267,23 @@ gst_tee_class_init (GstTeeClass * klass)
   g_object_class_install_property (gobject_class, PROP_ALLOC_PAD,
       pspec_alloc_pad);
 
+  /**
+   * GstTee:allow-not-linked
+   *
+   * This property makes sink pad return GST_FLOW_OK even if there are no
+   * source pads or any of them is linked.
+   *
+   * This is useful to avoid errors when you have a dynamic pipeline and during
+   * a reconnection you can have all the pads unlinked or removed.
+   *
+   * Since: 1.6
+   */
+  g_object_class_install_property (gobject_class, PROP_ALLOW_NOT_LINKED,
+      g_param_spec_boolean ("allow-not-linked", "Allow not linked",
+          "Return GTS_FLOW_OK even if there are not source pads or all are "
+          "unlinked", DEFAULT_PROP_ALLOW_NOT_LINKED,
+          G_PARAM_CONSTRUCT | G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+
   gst_element_class_set_static_metadata (gstelement_class,
       "Tee pipe fitting",
       "Generic",
@@ -487,6 +506,9 @@ gst_tee_set_property (GObject * object, guint prop_id, const GValue * value,
       GST_OBJECT_UNLOCK (pad);
       break;
     }
+    case PROP_ALLOW_NOT_LINKED:
+      tee->allow_not_linked = g_value_get_boolean (value);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -520,6 +542,9 @@ gst_tee_get_property (GObject * object, guint prop_id, GValue * value,
     case PROP_ALLOC_PAD:
       g_value_set_object (value, tee->allocpad);
       break;
+    case PROP_ALLOW_NOT_LINKED:
+      g_value_set_boolean (value, tee->allow_not_linked);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -636,6 +661,10 @@ gst_tee_handle_data (GstTee * tee, gpointer data, gboolean is_list)
 
     gst_object_unref (pad);
 
+    if (ret == GST_FLOW_NOT_LINKED && tee->allow_not_linked) {
+      ret = GST_FLOW_OK;
+    }
+
     return ret;
   }
 
@@ -643,7 +672,11 @@ gst_tee_handle_data (GstTee * tee, gpointer data, gboolean is_list)
   g_list_foreach (pads, (GFunc) clear_pads, tee);
 
 restart:
-  cret = GST_FLOW_NOT_LINKED;
+  if (tee->allow_not_linked) {
+    cret = GST_FLOW_OK;
+  } else {
+    cret = GST_FLOW_NOT_LINKED;
+  }
   pads = GST_ELEMENT_CAST (tee)->srcpads;
   cookie = GST_ELEMENT_CAST (tee)->pads_cookie;
 
@@ -709,13 +742,23 @@ restart:
   /* ERRORS */
 no_pads:
   {
-    GST_DEBUG_OBJECT (tee, "there are no pads, return not-linked");
-    ret = GST_FLOW_NOT_LINKED;
-    goto error;
+    if (tee->allow_not_linked) {
+      GST_DEBUG_OBJECT (tee, "there are no pads, dropping %s",
+          is_list ? "buffer-list" : "buffer");
+      ret = GST_FLOW_OK;
+    } else {
+      GST_DEBUG_OBJECT (tee, "there are no pads, return not-linked");
+      ret = GST_FLOW_NOT_LINKED;
+    }
+    goto end;
   }
 error:
   {
     GST_DEBUG_OBJECT (tee, "received error %s", gst_flow_get_name (ret));
+    goto end;
+  }
+end:
+  {
     GST_OBJECT_UNLOCK (tee);
     gst_mini_object_unref (GST_MINI_OBJECT_CAST (data));
     return ret;

plugins/elements/gsttee.h

@@ -79,6 +79,8 @@ struct _GstTee {
   GstPadMode      sink_mode;
   GstTeePullMode  pull_mode;
   GstPad         *pull_pad;
+
+  gboolean        allow_not_linked;
 };
 
 struct _GstTeeClass {

tests/check/elements/tee.c

@@ -625,6 +625,79 @@ GST_START_TEST (test_request_pads)
 
 GST_END_TEST;
 
+GST_START_TEST (test_allow_not_linked)
+{
+  GstElement *tee;
+  GstPad *src1, *src2;
+  GstBuffer *buffer;
+  GstPad *srcpad;
+  GstCaps *caps;
+  GstSegment segment;
+
+  static GstStaticPadTemplate srctemplate = GST_STATIC_PAD_TEMPLATE ("src",
+      GST_PAD_SRC,
+      GST_PAD_ALWAYS,
+      GST_STATIC_CAPS_ANY);
+
+  caps = gst_caps_new_empty_simple ("test/test");
+
+  tee = gst_check_setup_element ("tee");
+  fail_unless (tee);
+  g_object_set (tee, "allow-not-linked", TRUE, NULL);
+
+  srcpad = gst_check_setup_src_pad (tee, &srctemplate);
+  gst_pad_set_active (srcpad, TRUE);
+
+  gst_pad_push_event (srcpad, gst_event_new_stream_start ("test"));
+  gst_segment_init (&segment, GST_FORMAT_BYTES);
+  gst_pad_push_event (srcpad, gst_event_new_stream_start ("test"));
+  gst_pad_set_caps (srcpad, caps);
+  gst_caps_unref (caps);
+  gst_pad_push_event (srcpad, gst_event_new_segment (&segment));
+
+  fail_unless (gst_element_set_state (tee,
+          GST_STATE_PLAYING) == GST_STATE_CHANGE_SUCCESS);
+
+  buffer = gst_buffer_new ();
+  fail_unless (buffer);
+
+  fail_unless (gst_pad_push (srcpad, gst_buffer_ref (buffer)) == GST_FLOW_OK);
+
+  src1 = gst_element_get_request_pad (tee, "src_%u");
+
+  fail_unless (gst_pad_push (srcpad, gst_buffer_ref (buffer)) == GST_FLOW_OK);
+
+  src2 = gst_element_get_request_pad (tee, "src_%u");
+
+  fail_unless (gst_pad_push (srcpad, gst_buffer_ref (buffer)) == GST_FLOW_OK);
+
+  g_object_set (tee, "allow-not-linked", FALSE, NULL);
+
+  fail_unless (gst_pad_push (srcpad,
+          gst_buffer_ref (buffer)) == GST_FLOW_NOT_LINKED);
+
+  gst_element_release_request_pad (tee, src1);
+
+  fail_unless (gst_pad_push (srcpad,
+          gst_buffer_ref (buffer)) == GST_FLOW_NOT_LINKED);
+
+  gst_element_release_request_pad (tee, src2);
+  g_object_unref (src1);
+  g_object_unref (src2);
+
+  fail_unless (gst_pad_push (srcpad,
+          gst_buffer_ref (buffer)) == GST_FLOW_NOT_LINKED);
+
+  gst_pad_set_active (srcpad, FALSE);
+  gst_check_teardown_src_pad (tee);
+  gst_check_teardown_element (tee);
+
+  fail_if (buffer->mini_object.refcount != 1);
+  gst_buffer_unref (buffer);
+}
+
+GST_END_TEST;
+
 static Suite *
 tee_suite (void)
 {
@@ -642,6 +715,7 @@ tee_suite (void)
   tcase_add_test (tc_chain, test_internal_links);
   tcase_add_test (tc_chain, test_flow_aggregation);
   tcase_add_test (tc_chain, test_request_pads);
+  tcase_add_test (tc_chain, test_allow_not_linked);
 
   return s;
 }