mixer: added flag "open"

src/mixer/alsa_mixer.c

@@ -230,4 +230,5 @@ const struct mixer_plugin alsa_mixer = {
 	.close = alsa_mixer_close,
 	.get_volume = alsa_mixer_get_volume,
 	.set_volume = alsa_mixer_set_volume,
+	.global = true,
 };

src/mixer/oss_mixer.c

@@ -198,4 +198,5 @@ const struct mixer_plugin oss_mixer = {
 	.close = oss_mixer_close,
 	.get_volume = oss_mixer_get_volume,
 	.set_volume = oss_mixer_set_volume,
+	.global = true,
 };

src/mixer_api.c

@@ -27,4 +27,5 @@ mixer_init(struct mixer *mixer, const struct mixer_plugin *plugin)
 {
 	mixer->plugin = plugin;
 	mixer->mutex = g_mutex_new();
+	mixer->open = false;
 }

src/mixer_api.h

@@ -33,6 +33,11 @@ struct mixer {
 	 * implementation, so plugins don't have to deal with that.
 	 */
 	GMutex *mutex;
+
+	/**
+	 * Is the mixer device currently open?
+	 */
+	bool open;
 };
 
 void

src/mixer_control.c

@@ -76,7 +76,12 @@ mixer_open(struct mixer *mixer)
 	assert(mixer->plugin != NULL);
 
 	g_mutex_lock(mixer->mutex);
-	success = mixer->plugin->open(mixer);
+
+	if (mixer->open)
+		success = true;
+	else
+		success = mixer->open = mixer->plugin->open(mixer);
+
 	g_mutex_unlock(mixer->mutex);
 
 	return success;
@@ -89,10 +94,22 @@ mixer_close(struct mixer *mixer)
 	assert(mixer->plugin != NULL);
 
 	g_mutex_lock(mixer->mutex);
-	mixer->plugin->close(mixer);
+
+	if (mixer->open) {
+		mixer->plugin->close(mixer);
+		mixer->open = false;
+	}
+
 	g_mutex_unlock(mixer->mutex);
 }
 
+void
+mixer_auto_close(struct mixer *mixer)
+{
+	if (!mixer->plugin->global)
+		mixer_close(mixer);
+}
+
 int
 mixer_get_volume(struct mixer *mixer)
 {
@@ -100,8 +117,16 @@ mixer_get_volume(struct mixer *mixer)
 
 	assert(mixer != NULL);
 
+	if (mixer->plugin->global && !mixer_open(mixer))
+		return -1;
+
 	g_mutex_lock(mixer->mutex);
-	volume = mixer->plugin->get_volume(mixer);
+
+	if (mixer->open) {
+		volume = mixer->plugin->get_volume(mixer);
+	} else
+		volume = -1;
+
 	g_mutex_unlock(mixer->mutex);
 
 	return volume;
@@ -114,8 +139,16 @@ mixer_set_volume(struct mixer *mixer, unsigned volume)
 
 	assert(mixer != NULL);
 
+	if (mixer->plugin->global && !mixer_open(mixer))
+		return false;
+
 	g_mutex_lock(mixer->mutex);
-	success = mixer->plugin->set_volume(mixer, volume);
+
+	if (mixer->open) {
+		success = mixer->plugin->set_volume(mixer, volume);
+	} else
+		success = false;
+
 	g_mutex_unlock(mixer->mutex);
 
 	return success;

src/mixer_control.h

@@ -46,6 +46,13 @@ mixer_open(struct mixer *mixer);
 void
 mixer_close(struct mixer *mixer);
 
+/**
+ * Close the mixer unless the plugin's "global" flag is set.  This is
+ * called when the #audio_output is closed.
+ */
+void
+mixer_auto_close(struct mixer *mixer);
+
 int
 mixer_get_volume(struct mixer *mixer);
 

src/mixer_plugin.h

@@ -68,6 +68,13 @@ struct mixer_plugin {
 	 * @return true on success
 	 */
 	bool (*set_volume)(struct mixer *mixer, unsigned volume);
+
+	/**
+	 * If true, then the mixer is automatically opened, even if
+	 * its audio output is not open.  If false, then the mixer is
+	 * disabled as long as its audio output is closed.
+	 */
+	bool global;
 };
 
 #endif

src/output_control.c

@@ -22,6 +22,7 @@
 #include "output_internal.h"
 #include "output_thread.h"
 #include "mixer_control.h"
+#include "mixer_plugin.h"
 
 #include <assert.h>
 #include <stdlib.h>
@@ -149,7 +150,7 @@ void audio_output_close(struct audio_output *ao)
 	assert(!ao->open || ao->fail_timer == NULL);
 
 	if (ao->mixer != NULL)
-		mixer_close(ao->mixer);
+		mixer_auto_close(ao->mixer);
 
 	if (ao->open)
 		ao_command(ao, AO_COMMAND_CLOSE);