meta: Move the clear operation to its own vfunc

Some transforms always assumed that the transformation was some kind of copy. So adding a "clear" operation didn't work out in practice. Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5830>
2024-12-26 10:10:32 +00:00 · 2023-12-18 13:40:53 -05:00 · 2023-12-18 13:40:53 -05:00 · 2a9c4e3270
commit 2a9c4e3270
parent 73338aa1ae
5 changed files with 68 additions and 54 deletions
--- a/girs/Gst-1.0.gir
+++ b/girs/Gst-1.0.gir
@ -22164,16 +22164,6 @@ In hindsight, this tag should have been called "memory-layout".</doc>
      <source-position filename="../subprojects/gstreamer/gst/gstmeta.h"/>
      <type name="utf8" c:type="gchar*"/>
    </constant>
-    <function-macro name="META_TRANSFORM_IS_CLEAR" c:identifier="GST_META_TRANSFORM_IS_CLEAR" version="1.24" introspectable="0">
-      <doc xml:space="preserve" filename="../subprojects/gstreamer/gst/gstmeta.h">Check if the transform type is clearing the content of the meta without
-freeing it.</doc>
-      <source-position filename="../subprojects/gstreamer/gst/gstmeta.h"/>
-      <parameters>
-        <parameter name="type">
-          <doc xml:space="preserve" filename="../subprojects/gstreamer/gst/gstmeta.h">a transform type</doc>
-        </parameter>
-      </parameters>
-    </function-macro>
    <function-macro name="META_TRANSFORM_IS_COPY" c:identifier="GST_META_TRANSFORM_IS_COPY" introspectable="0">
      <doc xml:space="preserve" filename="../subprojects/gstreamer/gst/gstmeta.h">Check if the transform type is a copy transform</doc>
      <source-position filename="../subprojects/gstreamer/gst/gstmeta.h"/>
@ -26093,6 +26083,24 @@ transform function.</doc>
        </parameters>
      </function>
    </record>
+    <callback name="MetaClearFunction" c:type="GstMetaClearFunction" version="1.24">
+      <doc xml:space="preserve" filename="../subprojects/gstreamer/gst/gstmeta.h">Clears the content of the meta. This will be called by the GstBufferPool
+when a pooled buffer is returned.</doc>
+      <source-position filename="../subprojects/gstreamer/gst/gstmeta.h"/>
+      <return-value transfer-ownership="none">
+        <type name="none" c:type="void"/>
+      </return-value>
+      <parameters>
+        <parameter name="buffer" transfer-ownership="none">
+          <doc xml:space="preserve" filename="../subprojects/gstreamer/gst/gstmeta.h">a #GstBuffer</doc>
+          <type name="Buffer" c:type="GstBuffer*"/>
+        </parameter>
+        <parameter name="meta" transfer-ownership="none">
+          <doc xml:space="preserve" filename="../subprojects/gstreamer/gst/gstmeta.h">a #GstMeta</doc>
+          <type name="Meta" c:type="GstMeta*"/>
+        </parameter>
+      </parameters>
+    </callback>
    <callback name="MetaDeserializeFunction" c:type="GstMetaDeserializeFunction" version="1.24">
      <doc xml:space="preserve" filename="../subprojects/gstreamer/gst/gstmeta.h">Recreate a #GstMeta from serialized data returned by
 #GstMetaSerializeFunction and add it to @buffer.</doc>
@ -26196,6 +26204,12 @@ meta.</doc>
 meta.</doc>
        <type name="MetaDeserializeFunction" c:type="GstMetaDeserializeFunction"/>
      </field>
+      <field name="clear_func" version="1.24" writable="1">
+        <doc xml:space="preserve" filename="../subprojects/gstreamer/gst/gstmeta.h">Function for clearing the metadata, or %NULL if not supported by this
+meta. This is called by the buffer pool when a buffer is returned for
+pooled metas.</doc>
+        <type name="MetaClearFunction" c:type="GstMetaClearFunction"/>
+      </field>
      <method name="is_custom" c:identifier="gst_meta_info_is_custom" version="1.20">
        <source-position filename="../subprojects/gstreamer/gst/gstmeta.h"/>
        <return-value transfer-ownership="none">
--- a/subprojects/gst-plugins-bad/gst-libs/gst/analytics/gstanalyticsmeta.c
+++ b/subprojects/gst-plugins-bad/gst-libs/gst/analytics/gstanalyticsmeta.c
@ -344,39 +344,41 @@ gst_analytics_relation_meta_transform (GstBuffer * transbuf,

      return FALSE;
    }
-  } else if (GST_META_TRANSFORM_IS_CLEAR (type)) {
-    GstAnalyticsRelationMeta *rmeta = (GstAnalyticsRelationMeta *) meta;
-    gsize adj_mat_data_size =
-        (sizeof (guint8) * rmeta->rel_order * rmeta->rel_order);
-
-    rmeta->next_id = 0;
-    rmeta->offset = 0;
-    rmeta->length = 0;
-    if (adj_mat_data_size) {
-      /* Only clear data and not lines addresses occupying begining of this
-       * array. */
-      memset (rmeta->adj_mat + rmeta->rel_order, 0, adj_mat_data_size);
-    }
-
-    return TRUE;
  }

  return FALSE;
 }

+static void
+gst_analytics_relation_meta_clear (GstBuffer * buffer, GstMeta * meta)
+{
+  GstAnalyticsRelationMeta *rmeta = (GstAnalyticsRelationMeta *) meta;
+  gsize adj_mat_data_size =
+      (sizeof (guint8) * rmeta->rel_order * rmeta->rel_order);
+
+  rmeta->next_id = 0;
+  rmeta->offset = 0;
+  rmeta->length = 0;
+  if (adj_mat_data_size) {
+    /* Only clear data and not lines addresses occupying begining of this
+     * array. */
+    memset (rmeta->adj_mat + rmeta->rel_order, 0, adj_mat_data_size);
+  }
+}

 const GstMetaInfo *
 gst_analytics_relation_meta_get_info (void)
 {
  static const GstMetaInfo *info = NULL;
  if (g_once_init_enter ((GstMetaInfo **) & info)) {
-    const GstMetaInfo *meta =
+    GstMetaInfo *meta = (GstMetaInfo *)
        gst_meta_register (GST_ANALYTICS_RELATION_META_API_TYPE,
        "GstAnalyticsRelationMeta",
        sizeof (GstAnalyticsRelationMeta),
        gst_analytics_relation_meta_init,
        gst_analytics_relation_meta_free,
        gst_analytics_relation_meta_transform);
+    meta->clear_func = gst_analytics_relation_meta_clear;
    g_once_init_leave ((GstMetaInfo **) & info, (GstMetaInfo *) meta);
  }
  return info;
--- a/subprojects/gstreamer/gst/gstbufferpool.c
+++ b/subprojects/gstreamer/gst/gstbufferpool.c
@ -1221,10 +1221,8 @@ remove_meta_unpooled (GstBuffer * buffer, GstMeta ** meta, gpointer user_data)
    const GstMetaInfo *info = (*meta)->info;

    /* If we can clear it, don't free it */
-    if (info->transform_func) {
-      info->transform_func (NULL, *meta, buffer, _gst_meta_transform_clear,
-          NULL);
-    }
+    if (info->clear_func)
+      info->clear_func (buffer, *meta);
  }
  return TRUE;
 }
--- a/subprojects/gstreamer/gst/gstmeta.c
+++ b/subprojects/gstreamer/gst/gstmeta.c
@ -56,7 +56,6 @@ static GHashTable *metainfo = NULL;
 static GRWLock lock;

 GQuark _gst_meta_transform_copy;
-GQuark _gst_meta_transform_clear;
 GQuark _gst_meta_tag_memory;
 GQuark _gst_meta_tag_memory_reference;

@ -82,7 +81,6 @@ _priv_gst_meta_initialize (void)
  metainfo = g_hash_table_new_full (g_str_hash, g_str_equal, NULL, free_info);

  _gst_meta_transform_copy = g_quark_from_static_string ("gst-copy");
-  _gst_meta_transform_clear = g_quark_from_static_string ("gst-clear");
  _gst_meta_tag_memory = g_quark_from_static_string ("memory");
  _gst_meta_tag_memory_reference =
      g_quark_from_static_string ("memory-reference");
@ -430,7 +428,7 @@ gst_meta_register_internal (GType api, const gchar * impl, gsize size,
  if (type == G_TYPE_INVALID)
    return NULL;

-  info = (GstMetaInfo *) g_new (GstMetaInfoImpl, 1);
+  info = (GstMetaInfo *) g_new0 (GstMetaInfoImpl, 1);
  info->api = api;
  info->type = type;
  info->size = size;
--- a/subprojects/gstreamer/gst/gstmeta.h
+++ b/subprojects/gstreamer/gst/gstmeta.h
@ -197,27 +197,6 @@ typedef struct {
  gsize size;
 } GstMetaTransformCopy;

-/**
- * gst_meta_transform_clear:
- *
- * GQuark for the "gst-clear" transform.
- *
- * Since: 1.24
- */
-
-GST_API GQuark _gst_meta_transform_clear;
-
-/**
- * GST_META_TRANSFORM_IS_CLEAR:
- * @type: a transform type
- *
- * Check if the transform type is clearing the content of the meta without
- * freeing it.
- *
- * Since: 1.24
- */
-#define GST_META_TRANSFORM_IS_CLEAR(type) ((type) == _gst_meta_transform_clear)
-
 /**
 * GstMetaTransformFunction:
 * @transbuf: a #GstBuffer
@ -301,6 +280,18 @@ typedef gboolean (*GstMetaSerializeFunction) (const GstMeta *meta,
 typedef GstMeta *(*GstMetaDeserializeFunction) (const GstMetaInfo *info,
    GstBuffer *buffer, const guint8 *data, gsize size, guint8 version);

+/**
+ * GstMetaClearFunction:
+ * @buffer: a #GstBuffer
+ * @meta: a #GstMeta
+ *
+ * Clears the content of the meta. This will be called by the GstBufferPool
+ * when a pooled buffer is returned.
+ *
+ * Since: 1.24
+ */
+typedef void (*GstMetaClearFunction) (GstBuffer *buffer, GstMeta *meta);
+
 /**
 * GstMetaInfo.serialize_func:
 *
@ -319,6 +310,16 @@ typedef GstMeta *(*GstMetaDeserializeFunction) (const GstMetaInfo *info,
 * Since: 1.24
 */

+/**
+ * GstMetaInfo.clear_func:
+ *
+ * Function for clearing the metadata, or %NULL if not supported by this
+ * meta. This is called by the buffer pool when a buffer is returned for
+ * pooled metas.
+ *
+ * Since: 1.24
+ */
+
 /**
 * GstMetaInfo:
 * @api: tag identifying the metadata structure and api
@ -345,6 +346,7 @@ struct _GstMetaInfo {
  GstMetaTransformFunction   transform_func;
  GstMetaSerializeFunction   serialize_func;
  GstMetaDeserializeFunction deserialize_func;
+  GstMetaClearFunction       clear_func;

  /* No padding needed, GstMetaInfo is always allocated by GStreamer and is
   * not subclassable or stack-allocatable, so we can extend it as we please