output/Client: new interface to replace direct access to class PlayerControl

src/output/Client.hxx

+/*
+ * Copyright 2003-2016 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_OUTPUT_CLIENT_HXX
+#define MPD_OUTPUT_CLIENT_HXX
+
+#include "check.h"
+
+/**
+ * An interface between the #AudioOutput and the #Player.
+ */
+class AudioOutputClient {
+public:
+	/**
+	 * Notify the client that we have consumed a few chunks.  This
+	 * is called from within the output thread.  The client may
+	 * perform actions to refill the #MusicPipe.
+	 */
+	virtual void ChunksConsumed() = 0;
+
+	/**
+	 * The #AudioOutput has modified the "enabled" flag, and the
+	 * client shall make the #AudioOutput apply this new setting.
+	 * This is called from any thread, one which can't send an
+	 * AudioOutput::Command to the output thread; only the client
+	 * can do that safely.
+	 */
+	virtual void ApplyEnabled() = 0;
+};
+
+#endif

src/output/Init.cxx

@@ -275,7 +275,7 @@ audio_output_new(EventLoop &event_loop,
 		 const ReplayGainConfig &replay_gain_config,
 		 const ConfigBlock &block,
 		 MixerListener &mixer_listener,
-		 PlayerControl &pc)
+		 AudioOutputClient &client)
 {
 	const AudioOutputPlugin *plugin;
 
@@ -311,6 +311,6 @@ audio_output_new(EventLoop &event_loop,
 		throw;
 	}
 
-	ao->player_control = &pc;
+	ao->client = &client;
 	return ao;
 }

src/output/Internal.hxx

@@ -37,9 +37,9 @@ class MusicPipe;
 class EventLoop;
 class Mixer;
 class MixerListener;
+class AudioOutputClient;
 struct MusicChunk;
 struct ConfigBlock;
-struct PlayerControl;
 struct AudioOutputPlugin;
 struct ReplayGainConfig;
 
@@ -261,7 +261,7 @@ struct AudioOutput {
 	 * The PlayerControl object which "owns" this output.  This
 	 * object is needed to signal command completion.
 	 */
-	PlayerControl *player_control;
+	AudioOutputClient *client;
 
 	/**
 	 * A reference to the #MusicPipe and the current position.
@@ -510,7 +510,7 @@ audio_output_new(EventLoop &event_loop,
 		 const ReplayGainConfig &replay_gain_config,
 		 const ConfigBlock &block,
 		 MixerListener &mixer_listener,
-		 PlayerControl &pc);
+		 AudioOutputClient &client);
 
 void
 audio_output_free(AudioOutput *ao);

src/output/MultipleOutputs.cxx

@@ -53,11 +53,11 @@ static AudioOutput *
 LoadOutput(EventLoop &event_loop,
 	   const ReplayGainConfig &replay_gain_config,
 	   MixerListener &mixer_listener,
-	   PlayerControl &pc, const ConfigBlock &block)
+	   AudioOutputClient &client, const ConfigBlock &block)
 try {
 	return audio_output_new(event_loop, replay_gain_config, block,
 				mixer_listener,
-				pc);
+				client);
 } catch (const std::runtime_error &e) {
 	if (block.line > 0)
 		std::throw_with_nested(FormatRuntimeError("Failed to configure output in line %i",
@@ -69,13 +69,13 @@ try {
 void
 MultipleOutputs::Configure(EventLoop &event_loop,
 			   const ReplayGainConfig &replay_gain_config,
-			   PlayerControl &pc)
+			   AudioOutputClient &client)
 {
 	for (const auto *param = config_get_block(ConfigBlockOption::AUDIO_OUTPUT);
 	     param != nullptr; param = param->next) {
 		auto output = LoadOutput(event_loop, replay_gain_config,
 					 mixer_listener,
-					 pc, *param);
+					 client, *param);
 		if (FindByName(output->name) != nullptr)
 			throw FormatRuntimeError("output devices with identical "
 						 "names: %s", output->name);
@@ -88,7 +88,7 @@ MultipleOutputs::Configure(EventLoop &event_loop,
 		const ConfigBlock empty;
 		auto output = LoadOutput(event_loop, replay_gain_config,
 					 mixer_listener,
-					 pc, empty);
+					 client, empty);
 		outputs.push_back(output);
 	}
 }

src/output/MultipleOutputs.hxx

@@ -39,8 +39,8 @@ class MusicBuffer;
 class MusicPipe;
 class EventLoop;
 class MixerListener;
+class AudioOutputClient;
 struct MusicChunk;
-struct PlayerControl;
 struct AudioOutput;
 struct ReplayGainConfig;
 
@@ -78,7 +78,7 @@ public:
 
 	void Configure(EventLoop &event_loop,
 		       const ReplayGainConfig &replay_gain_config,
-		       PlayerControl &pc);
+		       AudioOutputClient &client);
 
 	/**
 	 * Returns the total number of audio output devices, including

src/output/OutputCommand.cxx

@@ -28,6 +28,7 @@
 #include "OutputCommand.hxx"
 #include "MultipleOutputs.hxx"
 #include "Internal.hxx"
+#include "Client.hxx"
 #include "player/Control.hxx"
 #include "mixer/MixerControl.hxx"
 #include "mixer/Volume.hxx"
@@ -53,7 +54,7 @@ audio_output_enable_index(MultipleOutputs &outputs, unsigned idx)
 		idle_add(IDLE_MIXER);
 	}
 
-	ao.player_control->LockUpdateAudio();
+	ao.client->ApplyEnabled();
 
 	++audio_output_state_version;
 
@@ -80,7 +81,7 @@ audio_output_disable_index(MultipleOutputs &outputs, unsigned idx)
 		idle_add(IDLE_MIXER);
 	}
 
-	ao.player_control->LockUpdateAudio();
+	ao.client->ApplyEnabled();
 
 	++audio_output_state_version;
 
@@ -106,7 +107,7 @@ audio_output_toggle_index(MultipleOutputs &outputs, unsigned idx)
 		}
 	}
 
-	ao.player_control->LockUpdateAudio();
+	ao.client->ApplyEnabled();
 
 	++audio_output_state_version;
 

src/output/OutputThread.cxx

@@ -19,6 +19,7 @@
 
 #include "config.h"
 #include "Internal.hxx"
+#include "Client.hxx"
 #include "OutputAPI.hxx"
 #include "Domain.hxx"
 #include "pcm/PcmMix.hxx"
@@ -28,7 +29,6 @@
 #include "filter/plugins/ReplayGainFilterPlugin.hxx"
 #include "mixer/MixerInternal.hxx"
 #include "mixer/plugins/SoftwareMixerPlugin.hxx"
-#include "player/Control.hxx"
 #include "MusicPipe.hxx"
 #include "MusicChunk.hxx"
 #include "thread/Util.hxx"
@@ -504,7 +504,7 @@ AudioOutput::Play()
 			   give it a chance to refill the pipe before
 			   it runs empty */
 			const ScopeUnlock unlock(mutex);
-			player_control->LockSignal();
+			client->ChunksConsumed();
 			n = 0;
 		}
 
@@ -516,7 +516,7 @@ AudioOutput::Play()
 	} while (chunk != nullptr);
 
 	const ScopeUnlock unlock(mutex);
-	player_control->LockSignal();
+	client->ChunksConsumed();
 
 	return true;
 }

src/player/Control.hxx

@@ -20,6 +20,7 @@
 #ifndef MPD_PLAYER_CONTROL_HXX
 #define MPD_PLAYER_CONTROL_HXX
 
+#include "output/Client.hxx"
 #include "AudioFormat.hxx"
 #include "thread/Mutex.hxx"
 #include "thread/Cond.hxx"
@@ -96,7 +97,7 @@ struct player_status {
 	SongTime elapsed_time;
 };
 
-struct PlayerControl {
+struct PlayerControl final : AudioOutputClient {
 	PlayerListener &listener;
 
 	MultipleOutputs &outputs;
@@ -527,6 +528,15 @@ public:
 	double GetTotalPlayTime() const {
 		return total_play_time;
 	}
+
+	/* virtual methods from AudioOutputClient */
+	void ChunksConsumed() override {
+		LockSignal();
+	}
+
+	void ApplyEnabled() override {
+		LockUpdateAudio();
+	}
 };
 
 #endif

test/run_output.cxx

@@ -20,6 +20,7 @@
 #include "config.h"
 #include "output/Internal.hxx"
 #include "output/OutputPlugin.hxx"
+#include "output/Client.hxx"
 #include "config/Param.hxx"
 #include "config/ConfigGlobal.hxx"
 #include "config/ConfigOption.hxx"
@@ -32,7 +33,6 @@
 #include "ReplayGainConfig.hxx"
 #include "pcm/PcmConvert.hxx"
 #include "filter/FilterRegistry.hxx"
-#include "player/Control.hxx"
 #include "util/RuntimeError.hxx"
 #include "util/ScopeExit.hxx"
 #include "Log.hxx"
@@ -43,6 +43,16 @@
 #include <stdlib.h>
 #include <stdio.h>
 
+class DummyAudioOutputClient final : public AudioOutputClient {
+public:
+	/* virtual methods from AudioOutputClient */
+	void ChunksConsumed() override {
+	}
+
+	void ApplyEnabled() override {
+	}
+};
+
 const FilterPlugin *
 filter_plugin_by_name(gcc_unused const char *name)
 {
@@ -50,21 +60,9 @@ filter_plugin_by_name(gcc_unused const char *name)
 	return NULL;
 }
 
-PlayerControl::PlayerControl(PlayerListener &_listener,
-			     MultipleOutputs &_outputs,
-			     unsigned _buffer_chunks,
-			     unsigned _buffered_before_play,
-			     AudioFormat _configured_audio_format,
-			     const ReplayGainConfig &_replay_gain_config)
-	:listener(_listener), outputs(_outputs),
-	 buffer_chunks(_buffer_chunks),
-	 buffered_before_play(_buffered_before_play),
-	 configured_audio_format(_configured_audio_format),
-	 replay_gain_config(_replay_gain_config) {}
-PlayerControl::~PlayerControl() {}
-
 static AudioOutput *
-load_audio_output(EventLoop &event_loop, const char *name)
+load_audio_output(EventLoop &event_loop, AudioOutputClient &client,
+		  const char *name)
 {
 	const auto *param = config_find_block(ConfigBlockOption::AUDIO_OUTPUT,
 					      "name", name);
@@ -72,15 +70,9 @@ load_audio_output(EventLoop &event_loop, const char *name)
 		throw FormatRuntimeError("No such configured audio output: %s\n",
 					 name);
 
-	static struct PlayerControl dummy_player_control(*(PlayerListener *)nullptr,
-							 *(MultipleOutputs *)nullptr,
-							 32, 4,
-							 AudioFormat::Undefined(),
-							 ReplayGainConfig());
-
 	return audio_output_new(event_loop, ReplayGainConfig(), *param,
 				*(MixerListener *)nullptr,
-				dummy_player_control);
+				client);
 }
 
 static void
@@ -150,7 +142,8 @@ try {
 
 	/* initialize the audio output */
 
-	AudioOutput *ao = load_audio_output(event_loop, argv[2]);
+	DummyAudioOutputClient client;
+	AudioOutput *ao = load_audio_output(event_loop, client, argv[2]);
 
 	/* parse the audio format */