glimagesink: Only cache pool, don't manage it

GLImage does not use any kind of internal pool. There was some
remaining code and comment stating that it was managing the
pool, and it was in fact setting the active state when doing
to ready state.

* Only create the pool if requested and in propose_allocation
* Cache the pool to avoid reallocation on spurious reconfigure
* Don't try to deactivate the pool (we don't own it)

https://bugzilla.gnome.org/show_bug.cgi?id=745705

ext/gl/gstglimagesink.c

@@ -722,13 +722,7 @@ gst_glimage_sink_change_state (GstElement * element, GstStateChange transition)
       }
 
       glimage_sink->window_id = 0;
-      //but do not reset glimage_sink->new_window_id
+      /* but do not reset glimage_sink->new_window_id */
-
-      if (glimage_sink->pool) {
-        gst_buffer_pool_set_active (glimage_sink->pool, FALSE);
-        gst_object_unref (glimage_sink->pool);
-        glimage_sink->pool = NULL;
-      }
 
       GST_VIDEO_SINK_WIDTH (glimage_sink) = 1;
       GST_VIDEO_SINK_HEIGHT (glimage_sink) = 1;
@@ -830,8 +824,6 @@ gst_glimage_sink_set_caps (GstBaseSink * bsink, GstCaps * caps)
   gint display_par_n, display_par_d;
   guint display_ratio_num, display_ratio_den;
   GstVideoInfo vinfo;
-  GstStructure *structure;
-  GstBufferPool *newpool, *oldpool;
   GstCapsFeatures *gl_features;
   GstCaps *uploaded_caps;
 
@@ -896,24 +888,6 @@ gst_glimage_sink_set_caps (GstBaseSink * bsink, GstCaps * caps)
   if (!_ensure_gl_setup (glimage_sink))
     return FALSE;
 
-  newpool = gst_gl_buffer_pool_new (glimage_sink->context);
-  structure = gst_buffer_pool_get_config (newpool);
-  gst_buffer_pool_config_set_params (structure, caps, vinfo.size, 2, 0);
-  gst_buffer_pool_set_config (newpool, structure);
-
-  oldpool = glimage_sink->pool;
-  /* we don't activate the pool yet, this will be done by downstream after it
-   * has configured the pool. If downstream does not want our pool we will
-   * activate it when we render into it */
-  glimage_sink->pool = newpool;
-
-  /* unref the old sink */
-  if (oldpool) {
-    /* we don't deactivate, some elements might still be using it, it will
-     * be deactivated when the last ref is gone */
-    gst_object_unref (oldpool);
-  }
-
   if (glimage_sink->upload)
     gst_object_unref (glimage_sink->upload);
   glimage_sink->upload = gst_gl_upload_new (glimage_sink->context);
@@ -1133,7 +1107,6 @@ static gboolean
 gst_glimage_sink_propose_allocation (GstBaseSink * bsink, GstQuery * query)
 {
   GstGLImageSink *glimage_sink = GST_GLIMAGE_SINK (bsink);
-  GstBufferPool *pool;
   GstStructure *config;
   GstCaps *caps;
   guint size;
@@ -1147,47 +1120,45 @@ gst_glimage_sink_propose_allocation (GstBaseSink * bsink, GstQuery * query)
   if (caps == NULL)
     goto no_caps;
 
-  if ((pool = glimage_sink->pool))
+  if (need_pool) {
-    gst_object_ref (pool);
-
-  if (pool != NULL) {
-    GstCaps *pcaps;
-
-    /* we had a pool, check caps */
-    GST_DEBUG_OBJECT (glimage_sink, "check existing pool caps");
-    config = gst_buffer_pool_get_config (pool);
-    gst_buffer_pool_config_get_params (config, &pcaps, &size, NULL, NULL);
-
-    if (!gst_caps_is_equal (caps, pcaps)) {
-      GST_DEBUG_OBJECT (glimage_sink, "pool has different caps");
-      /* different caps, we can't use this pool */
-      gst_object_unref (pool);
-      pool = NULL;
-    }
-    gst_structure_free (config);
-  }
-
-  if (pool == NULL && need_pool) {
     GstVideoInfo info;
 
     if (!gst_video_info_from_caps (&info, caps))
       goto invalid_caps;
 
-    GST_DEBUG_OBJECT (glimage_sink, "create new pool");
-    pool = gst_gl_buffer_pool_new (glimage_sink->context);
-
     /* the normal size of a frame */
     size = info.size;
 
-    config = gst_buffer_pool_get_config (pool);
+    if (glimage_sink->pool) {
+      GstCaps *pcaps;
+
+      /* we had a pool, check caps */
+      GST_DEBUG_OBJECT (glimage_sink, "check existing pool caps");
+      config = gst_buffer_pool_get_config (glimage_sink->pool);
+      gst_buffer_pool_config_get_params (config, &pcaps, &size, NULL, NULL);
+
+      if (!gst_caps_is_equal (caps, pcaps)) {
+        GST_DEBUG_OBJECT (glimage_sink, "pool has different caps");
+        /* different caps, we can't use this pool */
+        gst_object_unref (glimage_sink->pool);
+        glimage_sink->pool = NULL;
+      }
+      gst_structure_free (config);
+    }
+
+    if (glimage_sink->pool == NULL) {
+      GST_DEBUG_OBJECT (glimage_sink, "create new pool");
+
+      glimage_sink->pool = gst_gl_buffer_pool_new (glimage_sink->context);
+      config = gst_buffer_pool_get_config (glimage_sink->pool);
       gst_buffer_pool_config_set_params (config, caps, size, 0, 0);
-    if (!gst_buffer_pool_set_config (pool, config))
+
+      if (!gst_buffer_pool_set_config (glimage_sink->pool, config))
         goto config_failed;
     }
+
     /* we need at least 2 buffer because we hold on to the last one */
-  if (pool) {
+    gst_query_add_allocation_pool (query, glimage_sink->pool, size, 2, 0);
-    gst_query_add_allocation_pool (query, pool, size, 2, 0);
-    gst_object_unref (pool);
   }
 
   gst_gl_upload_propose_allocation (glimage_sink->upload, NULL, query);
@@ -1200,17 +1171,17 @@ gst_glimage_sink_propose_allocation (GstBaseSink * bsink, GstQuery * query)
   /* ERRORS */
 no_caps:
   {
-    GST_DEBUG_OBJECT (bsink, "no caps specified");
+    GST_WARNING_OBJECT (bsink, "no caps specified");
     return FALSE;
   }
 invalid_caps:
   {
-    GST_DEBUG_OBJECT (bsink, "invalid caps specified");
+    GST_WARNING_OBJECT (bsink, "invalid caps specified");
     return FALSE;
   }
 config_failed:
   {
-    GST_DEBUG_OBJECT (bsink, "failed setting config");
+    GST_WARNING_OBJECT (bsink, "failed setting config");
     return FALSE;
   }
 }