[alsa-devel] [PATCH] Add async support to pulse and jack plugins

[Takashi Iwai]

This patch adds async support to pulse and jack plugins.
I tested only jack plugin, so far.  The pulse might be buggy due to
possible races.

Anyway, as you can see, the implementation is pretty simple for a
plugin with a parallel thread like jack or pulse.  For other cases
like oss plugin, it might be more difficult.


Takashi

---
diff -r 0833aa56dbe2 jack/pcm_jack.c
--- a/jack/pcm_jack.c	Tue May 13 13:16:06 2008 +0200
+++ b/jack/pcm_jack.c	Tue May 20 13:07:57 2008 +0200
@@ -48,6 +48,8 @@
 
 	jack_port_t **ports;
 	jack_client_t *client;
+
+	int call_async;
 } snd_pcm_jack_t;
 
 static void snd_pcm_jack_free(snd_pcm_jack_t *jack)
@@ -90,6 +92,18 @@
 	*revents = pfds[0].revents;
 	return 0;
 }
+
+#if SND_PCM_IOPLUG_VERSION >= 0x010002
+static int snd_pcm_jack_async(snd_pcm_ioplug_t *io, int sig, pid_t pid)
+{
+	snd_pcm_jack_t *jack = io->private_data;
+	if (sig < 0)
+		jack->call_async = 0;
+	else
+		jack->call_async = 1;
+	return 0;
+}
+#endif
 
 static snd_pcm_sframes_t snd_pcm_jack_pointer(snd_pcm_ioplug_t *io)
 {
@@ -145,6 +159,11 @@
 
 	write(jack->fd, buf, 1); /* for polling */
 
+#if SND_PCM_IOPLUG_VERSION >= 0x010002
+	/* call async handlers if needed */
+	if (jack->call_async)
+		snd_pcm_ioplug_call_async_handlers(io);
+#endif
 	return 0;
 }
 
@@ -238,6 +257,9 @@
 	.pointer = snd_pcm_jack_pointer,
 	.prepare = snd_pcm_jack_prepare,
 	.poll_revents = snd_pcm_jack_poll_revents,
+#if SND_PCM_IOPLUG_VERSION >= 0x010002
+	.async = snd_pcm_jack_async,
+#endif
 };
 
 #define ARRAY_SIZE(ary)	(sizeof(ary)/sizeof(ary[0]))
@@ -372,6 +394,9 @@
 	jack->io.poll_fd = fd[1];
 	jack->io.poll_events = POLLIN;
 	jack->io.mmap_rw = 1;
+#if SND_PCM_IOPLUG_VERSION >= 0x010002
+	jack->io.no_signal_async = 1;
+#endif
 
 	err = snd_pcm_ioplug_create(&jack->io, name, stream, mode);
 	if (err < 0) {
diff -r 0833aa56dbe2 pulse/pcm_pulse.c
--- a/pulse/pcm_pulse.c	Tue May 13 13:16:06 2008 +0200
+++ b/pulse/pcm_pulse.c	Tue May 20 13:07:57 2008 +0200
@@ -45,6 +45,8 @@
     pa_sample_spec ss;
     unsigned int frame_size;
     pa_buffer_attr buffer_attr;
+
+    int call_async;
 } snd_pcm_pulse_t;
 
 static void update_ptr(snd_pcm_pulse_t *pcm)
@@ -365,6 +367,11 @@
     assert(pcm->p);
 
     pulse_poll_activate(pcm->p);
+
+#if SND_PCM_IOPLUG_VERSION >= 0x010002
+    if (pcm->call_async)
+      snd_pcm_ioplug_call_async_handlers(&pcm->io);
+#endif
 }
 
 static void stream_underrun_cb(pa_stream *p, void *userdata) {
@@ -446,6 +453,18 @@
 
 	return err;
 }
+
+#if SND_PCM_IOPLUG_VERSION >= 0x010002
+static int pulse_pcm_async(snd_pcm_ioplug_t *io, int sig, pid_t pid)
+{
+  snd_pcm_pulse_t *pcm = io->private_data;
+  if (sig < 0)
+    pcm->call_async = 0;
+  else
+    pcm->call_async = 1;
+  return 0;
+}
+#endif
 
 static int pulse_prepare(snd_pcm_ioplug_t *io)
 {
@@ -620,6 +639,9 @@
     .prepare = pulse_prepare,
     .hw_params = pulse_hw_params,
     .close = pulse_close,
+#if SND_PCM_IOPLUG_VERSION >= 0x010002
+    .async = pulse_pcm_async,
+#endif
 };
 
 
@@ -635,6 +657,9 @@
     .prepare = pulse_prepare,
     .hw_params = pulse_hw_params,
     .close = pulse_close,
+#if SND_PCM_IOPLUG_VERSION >= 0x010002
+    .async = pulse_pcm_async,
+#endif
 };
 
 
@@ -746,6 +771,9 @@
 	pcm->io.poll_fd = -1;
 	pcm->io.poll_events = 0;
 	pcm->io.mmap_rw = 0;
+#if SND_PCM_IOPLUG_VERSION >= 0x010002
+	pcm->io.no_signal_async = 1;
+#endif
 	pcm->io.callback = stream == SND_PCM_STREAM_PLAYBACK ?
 		&pulse_playback_callback : &pulse_capture_callback;
 	pcm->io.private_data = pcm;