X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=osx_write.c;h=d278d02c8ed5be97ffb0eb56b15825343c02e21c;hp=edb9f9230268c65703372e587e63140501e5e697;hb=831db326fc8977846792634c177c5811165c287a;hpb=9de1287d67c9562e9140c6dc7deb0c01c4e10cc0

diff --git a/osx_write.c b/osx_write.c
index edb9f923..d278d02c 100644
--- a/osx_write.c
+++ b/osx_write.c
@@ -43,9 +43,28 @@ struct private_osx_write_data {
 	unsigned sample_format;
 	/** Number of channels of the current audio stream. */
 	unsigned channels;
-	/** Serializes access to buffer tree nodes. */
+	/**
+	 * Serializes access to buffer tree nodes between the writer and
+	 * the callback which runs in a different thread.
+	 */
 	int mutex;
-	/** The btr node of the callback. */
+	/**
+	 * The btr node of the callback.
+	 *
+	 * Although access to the btr node is serialized between the writer and
+	 * the callback via the above mutex, this does not stop other buffer
+	 * tree nodes, for example the decoder, to race against the osx
+	 * callback.
+	 *
+	 * However, since all operations on buffer tree nodes are local in the
+	 * sense that they only affect one level in the buffer tree (i.e.
+	 * parent or child nodes, but not the grandparent or the
+	 * grandchildren), we may work around this problem by using another
+	 * buffer tree node for the callback.
+	 *
+	 * The writer grabs the mutex in its post_select method and pushes down
+	 * the buffers to the callback node.
+	 */
 	struct btr_node *callback_btrn;
 };
 
@@ -59,10 +78,14 @@ static OSStatus osx_callback(void *cb_arg, __a_unused AudioUnitRenderActionFlags
 {
 	int i;
 	struct writer_node *wn = cb_arg;
-	struct private_osx_write_data *powd = wn->private_data;
+	struct private_osx_write_data *powd;
 	size_t samples_have, samples_want = 0;
 
+	powd = wn->private_data;
 	mutex_lock(powd->mutex);
+	powd = wn->private_data;
+	if (!powd || !wn->btrn)
+		goto out;
 	/*
 	 * We fill with zeros if no data was yet written and we do not have
 	 * enough to fill all buffers.
@@ -217,18 +240,18 @@ e0:
 	return ret;
 }
 
-__malloc static void *osx_write_parse_config_or_die(const char *options)
+__malloc static void *osx_write_parse_config_or_die(int argc, char **argv)
 {
 	struct osx_write_args_info *conf = para_calloc(sizeof(*conf));
 
 	/* exits on errors */
-	osx_cmdline_parser_string(options, conf, "osx_write");
+	osx_write_cmdline_parser(argc, argv, conf);
 	return conf;
 }
 
 static void osx_free_config(void *conf)
 {
-	osx_cmdline_parser_free(conf);
+	osx_write_cmdline_parser_free(conf);
 }
 
 static void osx_write_close(struct writer_node *wn)
@@ -266,7 +289,7 @@ static void osx_write_pre_select(struct sched *s, struct task *t)
 	}
 
 	mutex_lock(powd->mutex);
-	ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
+	ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_INTERNAL);
 	if (ret < 0)
 		drain_delay_nec = need_drain_delay(powd);
 	mutex_unlock(powd->mutex);
@@ -298,23 +321,23 @@ static void osx_write_post_select(__a_unused struct sched *s, struct task *t)
 		AudioOutputUnitStart(powd->audio_unit);
 	}
 	mutex_lock(powd->mutex);
-	btr_pushdown(btrn);
-	ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
+	ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_INTERNAL);
+	if (ret > 0)
+		btr_pushdown(btrn);
 	if (ret < 0 && need_drain_delay(powd))
 		ret = 0;
-	mutex_unlock(powd->mutex);
-
-	if (ret >= 0)
-		goto out;
+	if (ret >= 0) {
+		mutex_unlock(powd->mutex);
+		return;
+	}
 	AudioOutputUnitStop(powd->audio_unit);
 	AudioUnitUninitialize(powd->audio_unit);
 	CloseComponent(powd->audio_unit);
-	btr_remove_node(powd->callback_btrn);
-	btr_free_node(powd->callback_btrn);
+	btr_remove_node(&powd->callback_btrn);
+	mutex_unlock(powd->mutex);
 remove_btrn:
-	btr_remove_node(btrn);
+	btr_remove_node(&wn->btrn);
 	PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
-out:
 	t->error = ret;
 }
 
@@ -327,16 +350,15 @@ void osx_write_init(struct writer *w)
 {
 	struct osx_write_args_info dummy;
 
-	osx_cmdline_parser_init(&dummy);
+	osx_write_cmdline_parser_init(&dummy);
 	w->close = osx_write_close;
 	w->pre_select = osx_write_pre_select;
 	w->post_select = osx_write_post_select;
 	w->parse_config_or_die = osx_write_parse_config_or_die;
 	w->free_config = osx_free_config;
-	w->shutdown = NULL; /* nothing to do */
 	w->help = (struct ggo_help) {
 		.short_help = osx_write_args_info_help,
 		.detailed_help = osx_write_args_info_detailed_help
 	};
-	osx_cmdline_parser_free(&dummy);
+	osx_write_cmdline_parser_free(&dummy);
 }