From: Andre Noll <maan@tuebingen.mpg.de>
Date: Sun, 23 Nov 2014 16:06:04 +0000 (+0100)
Subject: Merge branch 't/sound_device_lock'
X-Git-Tag: v0.5.4~47
X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=commitdiff_plain;h=8b71176b792089c47acc788e1c1e068e9375fd18;hp=abfb661f35e99e99c09a94d84839356d905af080

Merge branch 't/sound_device_lock'

Cooking since 2014-09-22.

* t/sound_device_lock:
  oss: Avoid sound artefacts on some setups.
  oss: Introduce sound device lock.
  audiod: Invalidate current audio format on close.
---

diff --git a/NEWS b/NEWS
index 305d9147..82e0f0d5 100644
--- a/NEWS
+++ b/NEWS
@@ -11,6 +11,7 @@ NEWS
 	- New sender subcommand: status.
 	- Improved help text for server and afs commands.
 	- audiod memory leak fixes.
+	- oss_writer improvements.
 
 Download: ./releases/paraslash-git.tar.bz2
 
diff --git a/audiod.c b/audiod.c
index d9df3847..f8eeccee 100644
--- a/audiod.c
+++ b/audiod.c
@@ -390,6 +390,7 @@ static void close_receiver(int slot_num)
 	task_reap(&s->receiver_node->task);
 	free(s->receiver_node);
 	s->receiver_node = NULL;
+	stat_task->current_audio_format_num = -1;
 	tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
 		&a->restart_barrier);
 }
diff --git a/oss_write.c b/oss_write.c
index d4bfd446..35f7b628 100644
--- a/oss_write.c
+++ b/oss_write.c
@@ -31,6 +31,29 @@ struct private_oss_write_data {
 	int bytes_per_frame;
 };
 
+/*
+ * We keep one bit of static storage to make sure only one instance of the oss
+ * writer is running at any given time.
+ */
+static bool sound_device_busy;
+
+static bool sound_device_is_busy(void)
+{
+	return sound_device_busy;
+}
+
+static void set_sound_device_busy(void)
+{
+	assert(!sound_device_busy);
+	sound_device_busy = true;
+}
+
+static void set_sound_device_idle(void)
+{
+	assert(sound_device_busy);
+	sound_device_busy = false;
+}
+
 static int get_oss_format(enum sample_format sf)
 {
 	switch (sf) {
@@ -50,7 +73,7 @@ static void oss_pre_select(struct sched *s, void *context)
 	struct private_oss_write_data *powd = wn->private_data;
 	int ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
 
-	if (ret == 0)
+	if (ret == 0 || (sound_device_is_busy() && !powd))
 		return;
 	if (ret < 0 || !powd)
 		return sched_min_delay(s);
@@ -65,6 +88,7 @@ static void oss_close(struct writer_node *wn)
 		return;
 	close(powd->fd);
 	free(powd);
+	set_sound_device_idle();
 }
 
 /*
@@ -165,6 +189,7 @@ static int oss_post_select(__a_unused struct sched *s, void *context)
 	size_t frames, bytes;
 	int ret;
 	char *data;
+	audio_buf_info abi;
 
 	ret = task_get_notification(wn->task);
 	if (ret < 0)
@@ -174,12 +199,16 @@ static int oss_post_select(__a_unused struct sched *s, void *context)
 		goto out;
 	if (!powd) {
 		int32_t rate, ch, format;
+
+		if (sound_device_is_busy())
+			return 0;
 		get_btr_sample_rate(btrn, &rate);
 		get_btr_channels(btrn, &ch);
 		get_btr_sample_format(btrn, &format);
 		ret = oss_init(wn, rate, ch, format);
 		if (ret < 0)
 			goto out;
+		set_sound_device_busy();
 		return 0;
 	}
 	btr_merge(btrn, wn->min_iqs);
@@ -192,6 +221,15 @@ static int oss_post_select(__a_unused struct sched *s, void *context)
 	ret = 0;
 	if (!FD_ISSET(powd->fd, &s->wfds))
 		goto out;
+	/* get maximal number of bytes that can be written */
+	ret = ioctl(powd->fd, SNDCTL_DSP_GETOSPACE, &abi);
+	if (ret >= 0) {
+		size_t max_frames = abi.bytes / powd->bytes_per_frame;
+		if (max_frames == 0)
+			goto out;
+		/* cap number of frames to avoid sound artefacts */
+		frames = PARA_MIN(frames, max_frames);
+	}
 	ret = xwrite(powd->fd, data, frames * powd->bytes_per_frame);
 	if (ret < 0)
 		goto out;