Mixer: add class MixerListener

Use a listener interface instead of GlobalEvents.

src/mixer/Listener.hxx

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_MIXER_LISTENER_HXX
+#define MPD_MIXER_LISTENER_HXX
+
+class Mixer;
+
+/**
+ * An interface that listens on events from mixer plugins.  The
+ * methods must be thread-safe and non-blocking.
+ */
+class MixerListener {
+public:
+	virtual void OnMixerVolumeChanged(Mixer &mixer, int volume) = 0;
+};
+
+#endif

src/mixer/MixerControl.cxx

@@ -27,10 +27,11 @@
 Mixer *
 mixer_new(EventLoop &event_loop,
 	  const MixerPlugin &plugin, AudioOutput &ao,
+	  MixerListener &listener,
 	  const config_param &param,
 	  Error &error)
 {
-	Mixer *mixer = plugin.init(event_loop, ao, param, error);
+	Mixer *mixer = plugin.init(event_loop, ao, listener, param, error);
 
 	assert(mixer == nullptr || mixer->IsPlugin(plugin));
 

src/mixer/MixerControl.hxx

@@ -30,10 +30,12 @@ class Mixer;
 class EventLoop;
 struct AudioOutput;
 struct MixerPlugin;
+class MixerListener;
 struct config_param;
 
 Mixer *
 mixer_new(EventLoop &event_loop, const MixerPlugin &plugin, AudioOutput &ao,
+	  MixerListener &listener,
 	  const config_param &param,
 	  Error &error);
 

src/mixer/MixerInternal.hxx

@@ -25,10 +25,14 @@
 #include "thread/Mutex.hxx"
 #include "Compiler.h"
 
+class MixerListener;
+
 class Mixer {
 public:
 	const MixerPlugin &plugin;
 
+	MixerListener &listener;
+
 	/**
 	 * This mutex protects all of the mixer struct, including its
 	 * implementation, so plugins don't have to deal with that.
@@ -47,8 +51,8 @@ public:
 	bool failed;
 
 public:
-	explicit Mixer(const MixerPlugin &_plugin)
-		:plugin(_plugin),
+	explicit Mixer(const MixerPlugin &_plugin, MixerListener &_listener)
+		:plugin(_plugin), listener(_listener),
 		 open(false),
 		 failed(false) {}
 

src/mixer/MixerPlugin.hxx

@@ -30,6 +30,7 @@
 struct config_param;
 struct AudioOutput;
 class Mixer;
+class MixerListener;
 class EventLoop;
 class Error;
 
@@ -44,6 +45,7 @@ struct MixerPlugin {
 	 * @return a mixer object, or nullptr on error
 	 */
 	Mixer *(*init)(EventLoop &event_loop, AudioOutput &ao,
+		       MixerListener &listener,
 		       const config_param &param,
 		       Error &error);
 

src/mixer/Volume.cxx

@@ -21,7 +21,6 @@
 #include "Volume.hxx"
 #include "output/MultipleOutputs.hxx"
 #include "Idle.hxx"
-#include "GlobalEvents.hxx"
 #include "util/StringUtil.hxx"
 #include "util/Domain.hxx"
 #include "system/PeriodClock.hxx"
@@ -41,22 +40,11 @@ static int last_hardware_volume = -1;
 /** the age of #last_hardware_volume */
 static PeriodClock hardware_volume_clock;
 
-/**
- * Handler for #GlobalEvents::MIXER.
- */
-static void
-mixer_event_callback(void)
+void
+InvalidateHardwareVolume()
 {
 	/* flush the hardware volume cache */
 	last_hardware_volume = -1;
-
-	/* notify clients */
-	idle_add(IDLE_MIXER);
-}
-
-void volume_init(void)
-{
-	GlobalEvents::Register(GlobalEvents::MIXER, mixer_event_callback);
 }
 
 int

src/mixer/Volume.hxx

@@ -26,7 +26,8 @@
 
 class MultipleOutputs;
 
-void volume_init(void);
+void
+InvalidateHardwareVolume();
 
 gcc_pure
 int

src/mixer/plugins/AlsaMixerPlugin.cxx

@@ -19,8 +19,8 @@
 
 #include "config.h"
 #include "mixer/MixerInternal.hxx"
+#include "mixer/Listener.hxx"
 #include "output/OutputAPI.hxx"
-#include "GlobalEvents.hxx"
 #include "event/MultiSocketMonitor.hxx"
 #include "event/DeferredMonitor.hxx"
 #include "event/Loop.hxx"
@@ -76,8 +76,9 @@ class AlsaMixer final : public Mixer {
 	AlsaMixerMonitor *monitor;
 
 public:
-	AlsaMixer(EventLoop &_event_loop)
-		:Mixer(alsa_mixer_plugin), event_loop(_event_loop) {}
+	AlsaMixer(EventLoop &_event_loop, MixerListener &_listener)
+		:Mixer(alsa_mixer_plugin, _listener),
+		 event_loop(_event_loop) {}
 
 	virtual ~AlsaMixer();
 
@@ -142,10 +143,15 @@ AlsaMixerMonitor::DispatchSockets()
  */
 
 static int
-alsa_mixer_elem_callback(gcc_unused snd_mixer_elem_t *elem, unsigned mask)
+alsa_mixer_elem_callback(snd_mixer_elem_t *elem, unsigned mask)
 {
-	if (mask & SND_CTL_EVENT_MASK_VALUE)
-		GlobalEvents::Emit(GlobalEvents::MIXER);
+	AlsaMixer &mixer = *(AlsaMixer *)
+		snd_mixer_elem_get_callback_private(elem);
+
+	if (mask & SND_CTL_EVENT_MASK_VALUE) {
+		int volume = mixer.GetVolume(IgnoreError());
+		mixer.listener.OnMixerVolumeChanged(mixer, volume);
+	}
 
 	return 0;
 }
@@ -168,10 +174,11 @@ AlsaMixer::Configure(const config_param &param)
 
 static Mixer *
 alsa_mixer_init(EventLoop &event_loop, gcc_unused AudioOutput &ao,
+		MixerListener &listener,
 		const config_param &param,
 		gcc_unused Error &error)
 {
-	AlsaMixer *am = new AlsaMixer(event_loop);
+	AlsaMixer *am = new AlsaMixer(event_loop, listener);
 	am->Configure(param);
 
 	return am;
@@ -236,6 +243,7 @@ AlsaMixer::Setup(Error &error)
 	snd_mixer_selem_get_playback_volume_range(elem, &volume_min,
 						  &volume_max);
 
+	snd_mixer_elem_set_callback_private(elem, this);
 	snd_mixer_elem_set_callback(elem, alsa_mixer_elem_callback);
 
 	monitor = new AlsaMixerMonitor(event_loop, handle);

src/mixer/plugins/OssMixerPlugin.cxx

@@ -49,7 +49,8 @@ class OssMixer final : public Mixer {
 	int volume_control;
 
 public:
-	OssMixer():Mixer(oss_mixer_plugin) {}
+	OssMixer(MixerListener &_listener)
+		:Mixer(oss_mixer_plugin, _listener) {}
 
 	bool Configure(const config_param &param, Error &error);
 
@@ -98,10 +99,11 @@ OssMixer::Configure(const config_param &param, Error &error)
 
 static Mixer *
 oss_mixer_init(gcc_unused EventLoop &event_loop, gcc_unused AudioOutput &ao,
+	       MixerListener &listener,
 	       const config_param &param,
 	       Error &error)
 {
-	OssMixer *om = new OssMixer();
+	OssMixer *om = new OssMixer(listener);
 
 	if (!om->Configure(param, error)) {
 		delete om;

src/mixer/plugins/PulseMixerPlugin.cxx

@@ -20,8 +20,8 @@
 #include "config.h"
 #include "PulseMixerPlugin.hxx"
 #include "mixer/MixerInternal.hxx"
+#include "mixer/Listener.hxx"
 #include "output/plugins/PulseOutputPlugin.hxx"
-#include "GlobalEvents.hxx"
 #include "util/Error.hxx"
 #include "util/Domain.hxx"
 #include "Log.hxx"
@@ -41,9 +41,9 @@ class PulseMixer final : public Mixer {
 	struct pa_cvolume volume;
 
 public:
-	PulseMixer(PulseOutput &_output)
-		:Mixer(pulse_mixer_plugin),
-		output(_output), online(false)
+	PulseMixer(PulseOutput &_output, MixerListener &_listener)
+		:Mixer(pulse_mixer_plugin, _listener),
+		 output(_output), online(false)
 	{
 	}
 
@@ -75,7 +75,7 @@ PulseMixer::Offline()
 
 	online = false;
 
-	GlobalEvents::Emit(GlobalEvents::MIXER);
+	listener.OnMixerVolumeChanged(*this, -1);
 }
 
 inline void
@@ -92,7 +92,7 @@ PulseMixer::VolumeCallback(const pa_sink_input_info *i, int eol)
 	online = true;
 	volume = i->volume;
 
-	GlobalEvents::Emit(GlobalEvents::MIXER);
+	listener.OnMixerVolumeChanged(*this, GetVolume(IgnoreError()));
 }
 
 /**
@@ -165,11 +165,12 @@ pulse_mixer_on_change(PulseMixer &pm,
 
 static Mixer *
 pulse_mixer_init(gcc_unused EventLoop &event_loop, AudioOutput &ao,
+		 MixerListener &listener,
 		 gcc_unused const config_param &param,
 		 gcc_unused Error &error)
 {
 	PulseOutput &po = (PulseOutput &)ao;
-	PulseMixer *pm = new PulseMixer(po);
+	PulseMixer *pm = new PulseMixer(po, listener);
 
 	pulse_output_set_mixer(po, *pm);
 

src/mixer/plugins/RoarMixerPlugin.cxx

@@ -29,9 +29,9 @@ class RoarMixer final : public Mixer {
 	RoarOutput &self;
 
 public:
-	RoarMixer(RoarOutput &_output)
-		:Mixer(roar_mixer_plugin),
-		self(_output) {}
+	RoarMixer(RoarOutput &_output, MixerListener &_listener)
+		:Mixer(roar_mixer_plugin, _listener),
+		 self(_output) {}
 
 	/* virtual methods from class Mixer */
 	virtual bool Open(gcc_unused Error &error) override {
@@ -47,10 +47,11 @@ public:
 
 static Mixer *
 roar_mixer_init(gcc_unused EventLoop &event_loop, AudioOutput &ao,
+		MixerListener &listener,
 		gcc_unused const config_param &param,
 		gcc_unused Error &error)
 {
-	return new RoarMixer((RoarOutput &)ao);
+	return new RoarMixer((RoarOutput &)ao, listener);
 }
 
 int

src/mixer/plugins/SoftwareMixerPlugin.cxx

@@ -52,8 +52,8 @@ class SoftwareMixer final : public Mixer {
 	unsigned volume;
 
 public:
-	SoftwareMixer()
-		:Mixer(software_mixer_plugin),
+	SoftwareMixer(MixerListener &_listener)
+		:Mixer(software_mixer_plugin, _listener),
 		 filter(CreateVolumeFilter()),
 		 owns_filter(true),
 		 volume(100)
@@ -86,10 +86,11 @@ public:
 static Mixer *
 software_mixer_init(gcc_unused EventLoop &event_loop,
 		    gcc_unused AudioOutput &ao,
+		    MixerListener &listener,
 		    gcc_unused const config_param &param,
 		    gcc_unused Error &error)
 {
-	return new SoftwareMixer();
+	return new SoftwareMixer(listener);
 }
 
 bool

src/mixer/plugins/WinmmMixerPlugin.cxx

@@ -34,8 +34,8 @@ class WinmmMixer final : public Mixer {
 	WinmmOutput &output;
 
 public:
-	WinmmMixer(WinmmOutput &_output)
-		:Mixer(winmm_mixer_plugin),
+	WinmmMixer(WinmmOutput &_output, MixerListener &_listener)
+		:Mixer(winmm_mixer_plugin, _listener),
 		output(_output) {
 	}
 
@@ -68,10 +68,11 @@ winmm_volume_encode(int volume)
 
 static Mixer *
 winmm_mixer_init(gcc_unused EventLoop &event_loop, AudioOutput &ao,
+		 MixerListener &listener,
 		 gcc_unused const config_param &param,
 		 gcc_unused Error &error)
 {
-	return new WinmmMixer((WinmmOutput &)ao);
+	return new WinmmMixer((WinmmOutput &)ao, listener);
 }
 
 int