queue/Playlist: add interface QueueListener, replacing calls to idle_add()

Makefile.am

@@ -166,6 +166,7 @@ libmpd_a_SOURCES = \
 	src/queue/PlaylistEdit.cxx \
 	src/queue/PlaylistTag.cxx \
 	src/queue/PlaylistState.cxx src/queue/PlaylistState.hxx \
+	src/queue/Listener.hxx \
 	src/ReplayGainConfig.cxx src/ReplayGainConfig.hxx \
 	src/ReplayGainInfo.cxx src/ReplayGainInfo.hxx \
 	src/DetachedSong.cxx src/DetachedSong.hxx \

src/Partition.cxx

@@ -29,7 +29,7 @@ Partition::Partition(Instance &_instance,
 		     unsigned max_length,
 		     unsigned buffer_chunks,
 		     unsigned buffered_before_play)
-	:instance(_instance), playlist(max_length),
+	:instance(_instance), playlist(max_length, *this),
 	 outputs(*this),
 	 pc(*this, outputs, buffer_chunks, buffered_before_play)
 {
@@ -74,6 +74,24 @@ Partition::SyncWithPlayer()
 	playlist.SyncWithPlayer(pc);
 }
 
+void
+Partition::OnQueueModified()
+{
+	EmitIdle(IDLE_PLAYLIST);
+}
+
+void
+Partition::OnQueueOptionsChanged()
+{
+	EmitIdle(IDLE_OPTIONS);
+}
+
+void
+Partition::OnQueueSongStarted()
+{
+	EmitIdle(IDLE_PLAYER);
+}
+
 void
 Partition::OnPlayerSync()
 {

src/Partition.hxx

@@ -21,6 +21,7 @@
 #define MPD_PARTITION_HXX
 
 #include "queue/Playlist.hxx"
+#include "queue/Listener.hxx"
 #include "output/MultipleOutputs.hxx"
 #include "mixer/Listener.hxx"
 #include "player/Control.hxx"
@@ -36,7 +37,7 @@ class SongLoader;
  * A partition of the Music Player Daemon.  It is a separate unit with
  * a playlist, a player, outputs etc.
  */
-struct Partition final : private PlayerListener, private MixerListener {
+struct Partition final : QueueListener, PlayerListener, MixerListener {
 	Instance &instance;
 
 	struct playlist playlist;
@@ -200,6 +201,11 @@ struct Partition final : private PlayerListener, private MixerListener {
 	void SyncWithPlayer();
 
 private:
+	/* virtual methods from class QueueListener */
+	void OnQueueModified() override;
+	void OnQueueOptionsChanged() override;
+	void OnQueueSongStarted() override;
+
 	/* virtual methods from class PlayerListener */
 	virtual void OnPlayerSync() override;
 	virtual void OnPlayerTagModified() override;

src/queue/Listener.hxx

@@ -0,0 +1,43 @@
+/*
+ * 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_QUEUE_LISTENER_HXX
+#define MPD_QUEUE_LISTENER_HXX
+
+class QueueListener {
+public:
+	/**
+	 * Called after the queue has been modified.
+	 */
+	virtual void OnQueueModified() = 0;
+
+	/**
+	 * Called after a playback options have been changed.
+	 */
+	virtual void OnQueueOptionsChanged() = 0;
+
+	/**
+	 * Called after the player has started playing a new song.
+	 * This gets called by playlist::SyncWithPlayer() after it has
+	 * been notified by the player thread.
+	 */
+	virtual void OnQueueSongStarted() = 0;
+};
+
+#endif

src/queue/Playlist.cxx

@@ -19,10 +19,10 @@
 
 #include "config.h"
 #include "Playlist.hxx"
+#include "Listener.hxx"
 #include "PlaylistError.hxx"
 #include "player/Control.hxx"
 #include "DetachedSong.hxx"
-#include "Idle.hxx"
 #include "Log.hxx"
 
 #include <assert.h>
@@ -86,7 +86,7 @@ playlist::QueuedSongStarted(PlayerControl &pc)
 	if (queue.consume)
 		DeleteOrder(pc, old_current);
 
-	idle_add(IDLE_PLAYER);
+	listener.OnQueueSongStarted();
 
 	SongStarted();
 }
@@ -245,7 +245,7 @@ playlist::SetRepeat(PlayerControl &pc, bool status)
 	   might change when repeat mode is toggled */
 	UpdateQueuedSong(pc, GetQueuedSong());
 
-	idle_add(IDLE_OPTIONS);
+	listener.OnQueueOptionsChanged();
 }
 
 static void
@@ -272,7 +272,7 @@ playlist::SetSingle(PlayerControl &pc, bool status)
 	   might change when single mode is toggled */
 	UpdateQueuedSong(pc, GetQueuedSong());
 
-	idle_add(IDLE_OPTIONS);
+	listener.OnQueueOptionsChanged();
 }
 
 void
@@ -282,7 +282,7 @@ playlist::SetConsume(bool status)
 		return;
 
 	queue.consume = status;
-	idle_add(IDLE_OPTIONS);
+	listener.OnQueueOptionsChanged();
 }
 
 void
@@ -319,7 +319,7 @@ playlist::SetRandom(PlayerControl &pc, bool status)
 
 	UpdateQueuedSong(pc, queued_song);
 
-	idle_add(IDLE_OPTIONS);
+	listener.OnQueueOptionsChanged();
 }
 
 int

src/queue/Playlist.hxx

@@ -30,6 +30,7 @@ class Error;
 class SongLoader;
 class SongTime;
 class SignedSongTime;
+class QueueListener;
 
 struct playlist {
 	/**
@@ -37,6 +38,8 @@ struct playlist {
 	 */
 	Queue queue;
 
+	QueueListener &listener;
+
 	/**
 	 * This value is true if the player is currently playing (or
 	 * should be playing).
@@ -85,8 +88,11 @@ struct playlist {
 	 */
 	int queued;
 
-	playlist(unsigned max_length)
-		:queue(max_length), playing(false),
+	playlist(unsigned max_length,
+		 QueueListener &_listener)
+		:queue(max_length),
+		 listener(_listener),
+		 playing(false),
 		 bulk_edit(false),
 		 current(-1), queued(-1) {
 	}
@@ -129,7 +135,8 @@ struct playlist {
 protected:
 	/**
 	 * Called by all editing methods after a modification.
-	 * Updates the queue version and emits #IDLE_PLAYLIST.
+	 * Updates the queue version and invokes
+	 * QueueListener::OnQueueModified().
 	 */
 	void OnModified();
 

src/queue/PlaylistEdit.cxx

@@ -25,12 +25,12 @@
 
 #include "config.h"
 #include "Playlist.hxx"
+#include "Listener.hxx"
 #include "PlaylistError.hxx"
 #include "player/Control.hxx"
 #include "util/Error.hxx"
 #include "DetachedSong.hxx"
 #include "SongLoader.hxx"
-#include "Idle.hxx"
 
 #include <memory>
 
@@ -47,7 +47,7 @@ playlist::OnModified()
 
 	queue.IncrementVersion();
 
-	idle_add(IDLE_PLAYLIST);
+	listener.OnQueueModified();
 }
 
 void

src/queue/PlaylistUpdate.cxx

@@ -22,7 +22,6 @@
 #include "db/Interface.hxx"
 #include "db/LightSong.hxx"
 #include "DetachedSong.hxx"
-#include "Idle.hxx"
 #include "util/Error.hxx"
 
 static bool