introduce PlaylistObserver

app/src/main/java/ch/blinkenlights/android/medialibrary/LibraryObserver.java

@@ -26,9 +26,8 @@ public class LibraryObserver {
 	 * by the receiver
 	 */
 	public enum Type {
-		ANY,         // Any type may have changed
+		SONG,        // Change affected song entries
-		SONG,        // Change only affected song entries
+		PLAYLIST,    // Change affected playlists
-		PLAYLIST,    // Change only affected playlists
 	}
 
 	/**
@@ -42,9 +41,10 @@ public class LibraryObserver {
 	 * to be overriden by the registered observer.
 	 *
 	 * @param type one of LibraryObserver.Type
+	 * @param id hint of which id changed for type, -1 if unspecified.
 	 * @param ongoing whether or not to expect more events soon.
 	 */
-	public void onChange(Type type, boolean ongoing) {
+	public void onChange(Type type, long id, boolean ongoing) {
 		// NOOP, should be overriden.
 	}
 }

app/src/main/java/ch/blinkenlights/android/medialibrary/MediaLibrary.java

@@ -324,11 +324,15 @@ public class MediaLibrary  {
 
 	/**
 	 * Broadcasts a change to all registered observers
+	 *
+	 * @param type the type of this event.
+	 * @param id the id of type which changed, -1 if unknown
+	 * @param ongoing whether or not to expect more of these updates soon
 	 */
-	static void notifyObserver(LibraryObserver.Type type, boolean ongoing) {
+	static void notifyObserver(LibraryObserver.Type type, long id, boolean ongoing) {
 		ArrayList<LibraryObserver> list = sLibraryObservers;
 		for (int i = list.size(); --i != -1; )
-			list.get(i).onChange(type, ongoing);
+			list.get(i).onChange(type, id, ongoing);
 	}
 
 	/**
@@ -357,7 +361,8 @@ public class MediaLibrary  {
 
 		if (rows > 0) {
 			getBackend(context).cleanOrphanedEntries(true);
-			notifyObserver(LibraryObserver.Type.ANY, false);
+			notifyObserver(LibraryObserver.Type.SONG, id, false);
+			notifyObserver(LibraryObserver.Type.PLAYLIST, -1, false);
 		}
 		return rows;
 	}
@@ -389,7 +394,7 @@ public class MediaLibrary  {
 		long id = getBackend(context).insert(MediaLibrary.TABLE_PLAYLISTS, null, v);
 
 		if (id != -1)
-			notifyObserver(LibraryObserver.Type.PLAYLIST, false);
+			notifyObserver(LibraryObserver.Type.PLAYLIST, id, false);
 		return id;
 	}
 
@@ -407,7 +412,7 @@ public class MediaLibrary  {
 		boolean removed = (rows > 0);
 
 		if (removed)
-			notifyObserver(LibraryObserver.Type.PLAYLIST, false);
+			notifyObserver(LibraryObserver.Type.PLAYLIST, id, false);
 		return removed;
 	}
 
@@ -445,7 +450,7 @@ public class MediaLibrary  {
 		int rows = getBackend(context).bulkInsert(MediaLibrary.TABLE_PLAYLISTS_SONGS, null, bulk);
 
 		if (rows > 0)
-			notifyObserver(LibraryObserver.Type.PLAYLIST, false);
+			notifyObserver(LibraryObserver.Type.PLAYLIST, playlistId, false);
 		return rows;
 	}
 
@@ -461,7 +466,7 @@ public class MediaLibrary  {
 		int rows = getBackend(context).delete(MediaLibrary.TABLE_PLAYLISTS_SONGS, selection, selectionArgs);
 
 		if (rows > 0)
-			notifyObserver(LibraryObserver.Type.PLAYLIST, false);
+			notifyObserver(LibraryObserver.Type.PLAYLIST, -1, false);
 		return rows;
 	}
 
@@ -483,8 +488,10 @@ public class MediaLibrary  {
 			removePlaylist(context, playlistId);
 		}
 
-		if (newId != -1)
+		if (newId != -1) {
-			notifyObserver(LibraryObserver.Type.PLAYLIST, false);
+			notifyObserver(LibraryObserver.Type.PLAYLIST, playlistId, false);
+			notifyObserver(LibraryObserver.Type.PLAYLIST, newId, false);
+		}
 		return newId;
 	}
 
@@ -529,7 +536,7 @@ public class MediaLibrary  {
 		selection = MediaLibrary.PlaylistSongColumns._ID+"="+from;
 		getBackend(context).update(MediaLibrary.TABLE_PLAYLISTS_SONGS, v, selection, null);
 
-		notifyObserver(LibraryObserver.Type.PLAYLIST, false);
+		notifyObserver(LibraryObserver.Type.PLAYLIST, playlistId, false);
 	}
 
 	/**

app/src/main/java/ch/blinkenlights/android/medialibrary/MediaScanner.java

@@ -205,7 +205,7 @@ public class MediaScanner implements Handler.Callback {
 
 		switch (rpc) {
 			case MSG_NOTIFY_CHANGE: {
-				MediaLibrary.notifyObserver(LibraryObserver.Type.SONG, true);
+				MediaLibrary.notifyObserver(LibraryObserver.Type.SONG, -1, true);
 				break;
 			}
 			case MSG_SCAN_FINISHED: {
@@ -216,6 +216,8 @@ public class MediaScanner implements Handler.Callback {
 				if (mPendingCleanup) {
 					mPendingCleanup = false;
 					mBackend.cleanOrphanedEntries(true);
+					// scan run possibly deleted file which may affect playlists:
+					MediaLibrary.notifyObserver(LibraryObserver.Type.PLAYLIST, -1, false);
 				}
 
 				// Send a last change notification to all observers.
@@ -224,7 +226,7 @@ public class MediaScanner implements Handler.Callback {
 				// also signals that this will be our last update
 				// for this scan.
 				mHandler.removeMessages(MSG_NOTIFY_CHANGE);
-				MediaLibrary.notifyObserver(LibraryObserver.Type.ANY, false);
+				MediaLibrary.notifyObserver(LibraryObserver.Type.SONG, -1, false);
 
 				updateNotification(false);
 				break;

app/src/main/java/ch/blinkenlights/android/vanilla/PlaybackService.java

@@ -431,6 +431,10 @@ public final class PlaybackService extends Service
 	 * Reference to precreated ReadAhead thread
 	 */
 	private ReadaheadThread mReadahead;
+	/**
+	 * Referente to our playlist observer
+	 */
+	private PlaylistObserver mPlaylistObserver;
 	/**
 	 * Reference to precreated BASTP Object
 	 */
@@ -502,6 +506,8 @@ public final class PlaybackService extends Service
 		mRemoteControlClient = new RemoteControl().getClient(this);
 		mRemoteControlClient.initializeRemote();
 
+		mPlaylistObserver = new PlaylistObserver();
+
 		mLooper = thread.getLooper();
 		mHandler = new Handler(mLooper, this);
 
@@ -616,6 +622,7 @@ public final class PlaybackService extends Service
 		enterSleepState();
 
 		MediaLibrary.unregisterLibraryObserver(mObserver);
+		mPlaylistObserver.unregister();
 
 		if (mMediaPlayer != null) {
 			mMediaPlayer.release();
@@ -1932,7 +1939,7 @@ public final class PlaybackService extends Service
 
 	private final LibraryObserver mObserver = new LibraryObserver() {
 		@Override
-		public void onChange(LibraryObserver.Type type, boolean ongoing)
+		public void onChange(LibraryObserver.Type type, long id, boolean ongoing)
 		{
 			MediaUtils.onMediaChange();
 			onMediaChange();

app/src/main/java/ch/blinkenlights/android/vanilla/PlaylistObserver.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2018 Adrian Ulrich <adrian@blinkenlights.ch>
+ *
+ * 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 3 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, see <http://www.gnu.org/licenses/>.
+ */
+
+package ch.blinkenlights.android.vanilla;
+
+import ch.blinkenlights.android.medialibrary.MediaLibrary;
+import ch.blinkenlights.android.medialibrary.LibraryObserver;
+
+import android.os.Environment;
+import android.os.Handler;
+import android.os.HandlerThread;
+import android.os.Message;
+import android.os.Process;
+
+import java.io.File;
+import android.util.Log;
+
+
+public class PlaylistObserver implements Handler.Callback {
+	/**
+	 * Handler thread used to perform playlist sync.
+	 */
+	private Handler mHandler;
+	/**
+	 * Directory which holds observed playlists.
+	 */
+	private File mPlaylists = new File(Environment.getExternalStorageDirectory(), "Playlists");
+
+
+	public PlaylistObserver() {
+		// Create thread which will be used for background work.
+		HandlerThread handlerThread = new HandlerThread("PlaylistWriter", Process.THREAD_PRIORITY_LOWEST);
+		handlerThread.start();
+		mHandler = new Handler(handlerThread.getLooper(), this);
+		// Register to receive media library events.
+		MediaLibrary.registerLibraryObserver(mObserver);
+	}
+
+	/**
+	 * Unregisters this observer, the object must not be used anymore
+	 * after this function was called.
+	 */
+	public void unregister() {
+		MediaLibrary.unregisterLibraryObserver(mObserver);
+	}
+
+	@Override
+	public boolean handleMessage(Message message) {
+		return true;
+	}
+
+	/**
+	 * Library observer callback which notifies us about media library
+	 * events.
+	 */
+	private final LibraryObserver mObserver = new LibraryObserver() {
+		@Override
+		public void onChange(LibraryObserver.Type type, long id, boolean ongoing) {
+			Log.v("VanillaMusic", "onChange type = "+type+", id = "+id+" ongoing = "+ongoing);
+		}
+	};
+
+	// TODO:
+	// Use FileObserver to track playlist changes?
+	// how do we check modifications? write a shadow-dir in private app storage with same mtimes?
+}

app/src/main/java/ch/blinkenlights/android/vanilla/ScheduledLibraryUpdate.java

@@ -133,7 +133,7 @@ public class ScheduledLibraryUpdate extends JobService {
 	 */
 	private final LibraryObserver mObserver = new LibraryObserver() {
 		@Override
-		public void onChange(LibraryObserver.Type type, boolean ongoing) {
+		public void onChange(LibraryObserver.Type type, long id, boolean ongoing) {
 			if (!ongoing) {
 				jobFinished(mJobParams, false);
 				finalizeScan();