output_api: play() returns a length

The old API required an output plugin to not return until all data
passed to the play() method is consumed.  Some output plugins have to
loop to fulfill that requirement, and may block during that.  Simplify
these, by letting them consume only part of the buffer: make play()
return the length of the consumed data.

1 files changed, 15 insertions, 18 deletions

diff --git a/src/output/jack_plugin.c b/src/output/jack_plugin.c
index 2bcdf874..22841f8e 100644
--- a/src/output/jack_plugin.c
+++ b/src/output/jack_plugin.c
@@ -387,7 +387,7 @@ mpd_jack_write_samples(struct jack_data *jd, const void *src,
 	}
 }
 
-static bool
+static size_t
 mpd_jack_play(void *data, const char *buff, size_t size)
 {
 	struct jack_data *jd = data;
@@ -396,36 +396,33 @@ mpd_jack_play(void *data, const char *buff, size_t size)
 
 	if (jd->shutdown) {
 		g_warning("Refusing to play, because there is no client thread.");
-		return false;
+		return 0;
 	}
 
 	assert(size % frame_size == 0);
 	size /= frame_size;
-	while (size > 0 && !jd->shutdown) {
+
+	while (!jd->shutdown) {
 		space = jack_ringbuffer_write_space(jd->ringbuffer[0]);
 		space1 = jack_ringbuffer_write_space(jd->ringbuffer[1]);
 		if (space > space1)
 			/* send data symmetrically */
 			space = space1;
 
-		space /= sample_size;
-		if (space > 0) {
-			if (space > size)
-				space = size;
-
-			mpd_jack_write_samples(jd, buff, space);
-
-			buff += space * frame_size;
-			size -= space;
-		} else {
-			/* XXX do something more intelligent to
-			   synchronize */
-			g_usleep(1000);
-		}
+		if (space >= frame_size)
+			break;
 
+		/* XXX do something more intelligent to
+		   synchronize */
+		g_usleep(1000);
 	}
 
-	return true;
+	space /= sample_size;
+	if (space < size)
+		size = space;
+
+	mpd_jack_write_samples(jd, buff, size);
+	return size * frame_size;
 }
 
 const struct audio_output_plugin jackPlugin = {