stream: add flush and drain command

spa/include/spa/graph/graph.h

@@ -233,10 +233,10 @@ static inline void
 spa_graph_node_add(struct spa_graph *graph,
 		   struct spa_graph_node *node)
 {
+	spa_debug("node %p add to graph %p", node, graph);
 	node->graph = graph;
 	spa_list_append(&graph->nodes, &node->link);
 	spa_graph_link_add(node, graph->state, &node->graph_link);
-	spa_debug("node %p add to graph %p", node, graph);
 }
 
 static inline void spa_graph_node_remove(struct spa_graph_node *node)

src/pipewire/stream.c

@@ -1223,3 +1223,32 @@ int pw_stream_queue_buffer(struct pw_stream *stream, struct pw_buffer *buffer)
 
 	return call_trigger(impl);
 }
+
+static int
+do_flush(struct spa_loop *loop,
+                 bool async, uint32_t seq, const void *data, size_t size, void *user_data)
+{
+	struct stream *impl = user_data;
+	struct buffer *b;
+
+	pw_log_trace("stream %p: flush", impl);
+	do {
+		b = pop_queue(impl, &impl->queued);
+		if (b != NULL)
+			push_queue(impl, &impl->dequeued, b);
+	}
+	while (b);
+
+	impl->time.queued = impl->queued.outcount = impl->dequeued.incount =
+		impl->dequeued.outcount = impl->queued.incount;
+
+	return 0;
+}
+
+int pw_stream_flush(struct pw_stream *stream, bool drain)
+{
+	struct stream *impl = SPA_CONTAINER_OF(stream, struct stream, this);
+	pw_loop_invoke(impl->core->data_loop,
+			do_flush, 1, NULL, 0, true, impl);
+	return 0;
+}

src/pipewire/stream.h

@@ -173,7 +173,8 @@ struct pw_buffer {
 					  *  returned in the time info. */
 };
 
-/** Events for a stream */
+/** Events for a stream. These events are always called from the mainloop
+ * unless explicitly documented otherwise. */
 struct pw_stream_events {
 #define PW_VERSION_STREAM_EVENTS	0
 	uint32_t version;
@@ -197,6 +198,9 @@ struct pw_stream_events {
 	 *  mainloop but can also be called directly from the realtime data
 	 *  thread if the user is prepared to deal with this. */
         void (*process) (void *data);
+
+	/** The stream is drained */
+        void (*drained) (void *data);
 };
 
 /** Convert a stream state to a readable string \memberof pw_stream */
@@ -307,9 +311,6 @@ int pw_stream_set_control(struct pw_stream *stream, const char *name, float valu
 /** Get a control value */
 int pw_stream_get_control(struct pw_stream *stream, const char *name, float *value);
 
-/** Activate or deactivate the stream \memberof pw_stream */
-int pw_stream_set_active(struct pw_stream *stream, bool active);
-
 /** A time structure \memberof pw_stream */
 struct pw_time {
 	int64_t now;			/**< the monotonic time */
@@ -333,6 +334,12 @@ struct pw_buffer *pw_stream_dequeue_buffer(struct pw_stream *stream);
 /** Submit a buffer for playback or recycle a buffer for capture. */
 int pw_stream_queue_buffer(struct pw_stream *stream, struct pw_buffer *buffer);
 
+/** Activate or deactivate the stream \memberof pw_stream */
+int pw_stream_set_active(struct pw_stream *stream, bool active);
+
+/** Flush a stream. When \a drain is true, the drained callback will
+ * be called when all data is played or recorded */
+int pw_stream_flush(struct pw_stream *stream, bool drain);
 
 #ifdef __cplusplus
 }