gio: add g_async_result_is_tagged()

Rather than doing a two step first-check-the-GAsyncResult-subtype-then-
check-the-tag, add a GAsyncResult-level method so that you can do them
both at once, simplifying the code for "short-circuit" async return
values where the vmethod never gets called.

https://bugzilla.gnome.org/show_bug.cgi?id=661767

docs/reference/gio/gio-sections.txt

@@ -1199,6 +1199,7 @@ GAsyncResultIface
 GAsyncReadyCallback
 g_async_result_get_user_data
 g_async_result_get_source_object
+g_async_result_is_tagged
 g_async_result_legacy_propagate_error
 <SUBSECTION Standard>
 G_ASYNC_RESULT

gio/gasyncresult.c

@@ -194,3 +194,32 @@ g_async_result_legacy_propagate_error (GAsyncResult  *res,
   else
     return FALSE;
 }
+
+/**
+ * g_async_result_is_tagged:
+ * @result: a #GAsyncResult
+ * @source_tag: an application-defined tag
+ *
+ * Checks if @result has the given @source_tag (generally a function
+ * pointer indicating the function @result was created by).
+ *
+ * Returns: %TRUE if @result has the indicated @source_tag, %FALSE if
+ *   not.
+ *
+ * Since: 2.34
+ **/
+gboolean
+g_async_result_is_tagged (GAsyncResult  *res,
+			  gpointer       source_tag)
+{
+  GAsyncResultIface *iface;
+
+  g_return_val_if_fail (G_IS_ASYNC_RESULT (res), FALSE);
+
+  iface = G_ASYNC_RESULT_GET_IFACE (res);
+
+  if (!iface->is_tagged)
+    return FALSE;
+
+  return (* iface->is_tagged) (res, source_tag);
+}

gio/gasyncresult.h

@@ -50,6 +50,7 @@ typedef struct _GAsyncResultIface    GAsyncResultIface;
  * @g_iface: The parent interface.
  * @get_user_data: Gets the user data passed to the callback.
  * @get_source_object: Gets the source object that issued the asynchronous operation.
+ * @is_tagged: Checks if a result is tagged with a particular source.
  *
  * Interface definition for #GAsyncResult.
  **/
@@ -61,6 +62,9 @@ struct _GAsyncResultIface
 
   gpointer  (* get_user_data)     (GAsyncResult *res);
   GObject * (* get_source_object) (GAsyncResult *res);
+
+  gboolean  (* is_tagged)         (GAsyncResult *res,
+				   gpointer      tag);
 };
 
 GType    g_async_result_get_type          (void) G_GNUC_CONST;
@@ -71,6 +75,9 @@ GObject *g_async_result_get_source_object (GAsyncResult *res);
 GLIB_AVAILABLE_IN_2_34
 gboolean g_async_result_legacy_propagate_error (GAsyncResult  *res,
 						GError       **error);
+GLIB_AVAILABLE_IN_2_34
+gboolean g_async_result_is_tagged              (GAsyncResult  *res,
+						gpointer       source_tag);
 
 G_END_DECLS
 

gio/gbufferedinputstream.c

@@ -542,7 +542,6 @@ g_buffered_input_stream_fill_finish (GBufferedInputStream  *stream,
                                      GAsyncResult          *result,
                                      GError               **error)
 {
-  GSimpleAsyncResult *simple;
   GBufferedInputStreamClass *class;
 
   g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), -1);
@@ -550,14 +549,10 @@ g_buffered_input_stream_fill_finish (GBufferedInputStream  *stream,
 
   if (g_async_result_legacy_propagate_error (result, error))
     return -1;
-
+  else if (g_async_result_is_tagged (result, g_buffered_input_stream_fill_async))
-  if (G_IS_SIMPLE_ASYNC_RESULT (result))
     {
-      simple = G_SIMPLE_ASYNC_RESULT (result);
-
       /* Special case read of 0 bytes */
-      if (g_simple_async_result_get_source_tag (simple) == g_buffered_input_stream_fill_async)
+      return 0;
-        return 0;
     }
 
   class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);

gio/gfileenumerator.c

@@ -400,21 +400,16 @@ g_file_enumerator_next_files_finish (GFileEnumerator  *enumerator,
 				     GError          **error)
 {
   GFileEnumeratorClass *class;
-  GSimpleAsyncResult *simple;
   
   g_return_val_if_fail (G_IS_FILE_ENUMERATOR (enumerator), NULL);
   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
   
   if (g_async_result_legacy_propagate_error (result, error))
     return NULL;
-
+  else if (g_async_result_is_tagged (result, g_file_enumerator_next_files_async))
-  if (G_IS_SIMPLE_ASYNC_RESULT (result))
+    { 
-    {
-      simple = G_SIMPLE_ASYNC_RESULT (result);
-      
       /* Special case read of 0 files */
-      if (g_simple_async_result_get_source_tag (simple) == g_file_enumerator_next_files_async)
+      return NULL;
-	return NULL;
     }
   
   class = G_FILE_ENUMERATOR_GET_CLASS (enumerator);

gio/ginputstream.c

@@ -649,7 +649,6 @@ g_input_stream_read_finish (GInputStream  *stream,
 			    GAsyncResult  *result,
 			    GError       **error)
 {
-  GSimpleAsyncResult *simple;
   GInputStreamClass *class;
   
   g_return_val_if_fail (G_IS_INPUT_STREAM (stream), -1);
@@ -657,14 +656,10 @@ g_input_stream_read_finish (GInputStream  *stream,
 
   if (g_async_result_legacy_propagate_error (result, error))
     return -1;
-
+  else if (g_async_result_is_tagged (result, g_input_stream_read_async))
-  if (G_IS_SIMPLE_ASYNC_RESULT (result))
     {
-      simple = G_SIMPLE_ASYNC_RESULT (result);
-
       /* Special case read of 0 bytes */
-      if (g_simple_async_result_get_source_tag (simple) == g_input_stream_read_async)
+      return 0;
-	return 0;
     }
 
   class = G_INPUT_STREAM_GET_CLASS (stream);
@@ -889,7 +884,6 @@ g_input_stream_skip_finish (GInputStream  *stream,
 			    GAsyncResult  *result,
 			    GError       **error)
 {
-  GSimpleAsyncResult *simple;
   GInputStreamClass *class;
 
   g_return_val_if_fail (G_IS_INPUT_STREAM (stream), -1);
@@ -897,14 +891,10 @@ g_input_stream_skip_finish (GInputStream  *stream,
 
   if (g_async_result_legacy_propagate_error (result, error))
     return -1;
-
+  else if (g_async_result_is_tagged (result, g_input_stream_skip_async))
-  if (G_IS_SIMPLE_ASYNC_RESULT (result))
     {
-      simple = G_SIMPLE_ASYNC_RESULT (result);
-
       /* Special case skip of 0 bytes */
-      if (g_simple_async_result_get_source_tag (simple) == g_input_stream_skip_async)
+      return 0;
-	return 0;
     }
 
   class = G_INPUT_STREAM_GET_CLASS (stream);
@@ -988,7 +978,6 @@ g_input_stream_close_finish (GInputStream  *stream,
 			     GAsyncResult  *result,
 			     GError       **error)
 {
-  GSimpleAsyncResult *simple;
   GInputStreamClass *class;
 
   g_return_val_if_fail (G_IS_INPUT_STREAM (stream), FALSE);
@@ -996,14 +985,10 @@ g_input_stream_close_finish (GInputStream  *stream,
 
   if (g_async_result_legacy_propagate_error (result, error))
     return FALSE;
-
+  else if (g_async_result_is_tagged (result, g_input_stream_close_async))
-  if (G_IS_SIMPLE_ASYNC_RESULT (result))
     {
-      simple = G_SIMPLE_ASYNC_RESULT (result);
-
       /* Special case already closed */
-      if (g_simple_async_result_get_source_tag (simple) == g_input_stream_close_async)
+      return TRUE;
-	return TRUE;
     }
 
   class = G_INPUT_STREAM_GET_CLASS (stream);

gio/gio.symbols

@@ -119,6 +119,7 @@ g_desktop_app_info_set_desktop_env
 g_async_result_get_type
 g_async_result_get_user_data
 g_async_result_get_source_object
+g_async_result_is_tagged
 g_async_result_legacy_propagate_error
 g_buffered_input_stream_get_type
 g_buffered_input_stream_new

gio/giostream.c

@@ -515,7 +515,6 @@ g_io_stream_close_finish (GIOStream     *stream,
 			  GAsyncResult  *result,
 			  GError       **error)
 {
-  GSimpleAsyncResult *simple;
   GIOStreamClass *class;
 
   g_return_val_if_fail (G_IS_IO_STREAM (stream), FALSE);
@@ -523,14 +522,10 @@ g_io_stream_close_finish (GIOStream     *stream,
 
   if (g_async_result_legacy_propagate_error (result, error))
     return FALSE;
-
+  else if (g_async_result_is_tagged (result, g_io_stream_close_async))
-  if (G_IS_SIMPLE_ASYNC_RESULT (result))
     {
-      simple = G_SIMPLE_ASYNC_RESULT (result);
-
       /* Special case already closed */
-      if (g_simple_async_result_get_source_tag (simple) == g_io_stream_close_async)
+      return TRUE;
-	return TRUE;
     }
 
   class = G_IO_STREAM_GET_CLASS (stream);

gio/goutputstream.c

@@ -835,7 +835,6 @@ g_output_stream_write_finish (GOutputStream  *stream,
                               GAsyncResult   *result,
                               GError        **error)
 {
-  GSimpleAsyncResult *simple;
   GOutputStreamClass *class;
 
   g_return_val_if_fail (G_IS_OUTPUT_STREAM (stream), -1);
@@ -843,14 +842,10 @@ g_output_stream_write_finish (GOutputStream  *stream,
 
   if (g_async_result_legacy_propagate_error (result, error))
     return -1;
-
+  else if (g_async_result_is_tagged (result, g_output_stream_write_async))
-  if (G_IS_SIMPLE_ASYNC_RESULT (result))
     {
-      simple = G_SIMPLE_ASYNC_RESULT (result);
-
       /* Special case writes of 0 bytes */
-      if (g_simple_async_result_get_source_tag (simple) == g_output_stream_write_async)
+      return 0;
-	return 0;
     }
   
   class = G_OUTPUT_STREAM_GET_CLASS (stream);
@@ -1161,7 +1156,6 @@ g_output_stream_flush_finish (GOutputStream  *stream,
                               GAsyncResult   *result,
                               GError        **error)
 {
-  GSimpleAsyncResult *simple;
   GOutputStreamClass *klass;
 
   g_return_val_if_fail (G_IS_OUTPUT_STREAM (stream), FALSE);
@@ -1169,14 +1163,10 @@ g_output_stream_flush_finish (GOutputStream  *stream,
 
   if (g_async_result_legacy_propagate_error (result, error))
     return FALSE;
-
+  else if (g_async_result_is_tagged (result, g_output_stream_flush_async))
-  if (G_IS_SIMPLE_ASYNC_RESULT (result))
     {
-      simple = G_SIMPLE_ASYNC_RESULT (result);
-
       /* Special case default implementation */
-      if (g_simple_async_result_get_source_tag (simple) == g_output_stream_flush_async)
+      return 0;
-	return TRUE;
     }
 
   klass = G_OUTPUT_STREAM_GET_CLASS (stream);
@@ -1284,7 +1274,6 @@ g_output_stream_close_finish (GOutputStream  *stream,
                               GAsyncResult   *result,
                               GError        **error)
 {
-  GSimpleAsyncResult *simple;
   GOutputStreamClass *class;
 
   g_return_val_if_fail (G_IS_OUTPUT_STREAM (stream), FALSE);
@@ -1292,14 +1281,10 @@ g_output_stream_close_finish (GOutputStream  *stream,
 
   if (g_async_result_legacy_propagate_error (result, error))
     return FALSE;
-
+  else if (g_async_result_is_tagged (result, g_output_stream_close_async))
-  if (G_IS_SIMPLE_ASYNC_RESULT (result))
     {
-      simple = G_SIMPLE_ASYNC_RESULT (result);
-
       /* Special case already closed */
-      if (g_simple_async_result_get_source_tag (simple) == g_output_stream_close_async)
+      return TRUE;
-	return TRUE;
     }
 
   class = G_OUTPUT_STREAM_GET_CLASS (stream);

gio/gresolver.c

@@ -447,19 +447,14 @@ g_resolver_lookup_by_name_finish (GResolver     *resolver,
 
   if (g_async_result_legacy_propagate_error (result, error))
     return NULL;
-
+  else if (g_async_result_is_tagged (result, g_resolver_lookup_by_name_async))
-  if (G_IS_SIMPLE_ASYNC_RESULT (result))
     {
       GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (result);
+      GInetAddress *addr;
 
       /* Handle the stringified-IP-addr case */
-      if (g_simple_async_result_get_source_tag (simple) == g_resolver_lookup_by_name_async)
+      addr = g_simple_async_result_get_op_res_gpointer (simple);
-        {
+      return g_list_append (NULL, g_object_ref (addr));
-          GInetAddress *addr;
-
-          addr = g_simple_async_result_get_op_res_gpointer (simple);
-          return g_list_append (NULL, g_object_ref (addr));
-        }
     }
 
   addrs = G_RESOLVER_GET_CLASS (resolver)->

gio/gsimpleasyncresult.c

@@ -457,11 +457,19 @@ g_simple_async_result_get_source_object (GAsyncResult *res)
   return NULL;
 }
 
+static gboolean
+g_simple_async_result_is_tagged (GAsyncResult *res,
+				 gpointer      source_tag)
+{
+  return G_SIMPLE_ASYNC_RESULT (res)->source_tag == source_tag;
+}
+
 static void
 g_simple_async_result_async_result_iface_init (GAsyncResultIface *iface)
 {
   iface->get_user_data = g_simple_async_result_get_user_data;
   iface->get_source_object = g_simple_async_result_get_source_object;
+  iface->is_tagged = g_simple_async_result_is_tagged;
 }
 
 /**