Added a WatchService to watch the beatmap directory tree for changes.

Any CREATE and DELETE that occur in the song menu state will now show a notification and modify the behavior of the 'F5' key. Changes that occur in other states will force a reload upon entering the song menu.

This is part of osu!, but as it's not incredibly helpful, I've left it disabled by default.  It can be enabled in the options menu.

Signed-off-by: Jeffrey Han <itdelatrisu@gmail.com>

src/itdelatrisu/opsu/states/OptionsMenu.java

@@ -97,7 +97,8 @@ public class OptionsMenu extends BasicGameState {
 			GameOption.FIXED_OD,
 			GameOption.CHECKPOINT,
 			GameOption.REPLAY_SEEKING,
-			GameOption.DISABLE_UPDATER
+			GameOption.DISABLE_UPDATER,
+			GameOption.ENABLE_WATCH_SERVICE
 		});
 
 		/** Total number of tabs. */

src/itdelatrisu/opsu/states/SongMenu.java

@@ -36,6 +36,8 @@ import itdelatrisu.opsu.beatmap.BeatmapParser;
 import itdelatrisu.opsu.beatmap.BeatmapSetList;
 import itdelatrisu.opsu.beatmap.BeatmapSetNode;
 import itdelatrisu.opsu.beatmap.BeatmapSortOrder;
+import itdelatrisu.opsu.beatmap.BeatmapWatchService;
+import itdelatrisu.opsu.beatmap.BeatmapWatchService.BeatmapWatchServiceListener;
 import itdelatrisu.opsu.db.BeatmapDB;
 import itdelatrisu.opsu.db.ScoreDB;
 import itdelatrisu.opsu.states.ButtonMenu.MenuState;
@@ -47,6 +49,9 @@ import itdelatrisu.opsu.ui.animations.AnimatedValue;
 import itdelatrisu.opsu.ui.animations.AnimationEquation;
 
 import java.io.File;
+import java.nio.file.Path;
+import java.nio.file.StandardWatchEventKinds;
+import java.nio.file.WatchEvent.Kind;
 import java.util.Map;
 import java.util.Stack;
 
@@ -205,6 +210,9 @@ public class SongMenu extends BasicGameState {
 	/** The text length of the last string in the search TextField. */
 	private int lastSearchTextLength = -1;
 
+	/** Whether the song folder changed (notified via the watch service). */
+	private boolean songFolderChanged = false;
+
 	// game-related variables
 	private GameContainer container;
 	private StateBasedGame game;
@@ -283,6 +291,19 @@ public class SongMenu extends BasicGameState {
 		int loaderDim = GameImage.MENU_MUSICNOTE.getImage().getWidth();
 		SpriteSheet spr = new SpriteSheet(GameImage.MENU_LOADER.getImage(), loaderDim, loaderDim);
 		loader = new Animation(spr, 50);
+
+		// beatmap watch service listener
+		final StateBasedGame game_ = game;
+		BeatmapWatchService.addListener(new BeatmapWatchServiceListener() {
+			@Override
+			public void eventReceived(Kind<?> kind, Path child) {
+				if (!songFolderChanged && kind != StandardWatchEventKinds.ENTRY_MODIFY) {
+					songFolderChanged = true;
+					if (game_.getCurrentStateID() == Opsu.STATE_SONGMENU)
+						UI.sendBarNotification("Changes in Songs folder detected. Hit F5 to refresh.");
+				}
+			}
+		});
 	}
 
 	@Override
@@ -775,8 +796,12 @@ public class SongMenu extends BasicGameState {
 			break;
 		case Input.KEY_F5:
 			SoundController.playSound(SoundEffect.MENUHIT);
-			((ButtonMenu) game.getState(Opsu.STATE_BUTTONMENU)).setMenuState(MenuState.RELOAD);
-			game.enterState(Opsu.STATE_BUTTONMENU);
+			if (songFolderChanged)
+				reloadBeatmaps(false);
+			else {
+				((ButtonMenu) game.getState(Opsu.STATE_BUTTONMENU)).setMenuState(MenuState.RELOAD);
+				game.enterState(Opsu.STATE_BUTTONMENU);
+			}
 			break;
 		case Input.KEY_DELETE:
 			if (focusNode == null)
@@ -949,8 +974,12 @@ public class SongMenu extends BasicGameState {
 		// reset song stack
 		randomStack = new Stack<SongNode>();
 
+		// reload beatmaps if song folder changed
+		if (songFolderChanged && stateAction != MenuState.RELOAD)
+			reloadBeatmaps(false);
+
 		// set focus node if not set (e.g. theme song playing)
-		if (focusNode == null && BeatmapSetList.get().size() > 0)
+		else if (focusNode == null && BeatmapSetList.get().size() > 0)
 			setFocus(BeatmapSetList.get().getRandomNode(), -1, true, true);
 
 		// reset music track
@@ -1069,44 +1098,7 @@ public class SongMenu extends BasicGameState {
 				}
 				break;
 			case RELOAD:  // reload beatmaps
-				// reset state and node references
-				MusicController.reset();
-				startNode = focusNode = null;
-				scoreMap = null;
-				focusScores = null;
-				oldFocusNode = null;
-				randomStack = new Stack<SongNode>();
-				songInfo = null;
-				hoverOffset.setTime(0);
-				hoverIndex = -1;
-				search.setText("");
-				searchTimer = SEARCH_DELAY;
-				searchTransitionTimer = SEARCH_TRANSITION_TIME;
-				searchResultString = null;
-
-				// reload songs in new thread
-				reloadThread = new Thread() {
-					@Override
-					public void run() {
-						// clear the beatmap cache
-						BeatmapDB.clearDatabase();
-
-						// invoke unpacker and parser
-						File beatmapDir = Options.getBeatmapDir();
-						OszUnpacker.unpackAllFiles(Options.getOSZDir(), beatmapDir);
-						BeatmapParser.parseAllFiles(beatmapDir);
-
-						// initialize song list
-						if (BeatmapSetList.get().size() > 0) {
-							BeatmapSetList.get().init();
-							setFocus(BeatmapSetList.get().getRandomNode(), -1, true, true);
-						} else
-							MusicController.playThemeSong();
-
-						reloadThread = null;
-					}
-				};
-				reloadThread.start();
+				reloadBeatmaps(true);
 				break;
 			default:
 				break;
@@ -1310,6 +1302,58 @@ public class SongMenu extends BasicGameState {
 			return null;  // incorrect map
 	}
 
+	/**
+	 * Reloads all beatmaps.
+	 * @param fullReload if true, also clear the beatmap cache and invoke the unpacker
+	 */
+	private void reloadBeatmaps(final boolean fullReload) {
+		songFolderChanged = false;
+
+		// reset state and node references
+		MusicController.reset();
+		startNode = focusNode = null;
+		scoreMap = null;
+		focusScores = null;
+		oldFocusNode = null;
+		randomStack = new Stack<SongNode>();
+		songInfo = null;
+		hoverOffset.setTime(0);
+		hoverIndex = -1;
+		search.setText("");
+		searchTimer = SEARCH_DELAY;
+		searchTransitionTimer = SEARCH_TRANSITION_TIME;
+		searchResultString = null;
+
+		// reload songs in new thread
+		reloadThread = new Thread() {
+			@Override
+			public void run() {
+				File beatmapDir = Options.getBeatmapDir();
+
+				if (fullReload) {
+					// clear the beatmap cache
+					BeatmapDB.clearDatabase();
+	
+					// invoke unpacker
+					OszUnpacker.unpackAllFiles(Options.getOSZDir(), beatmapDir);
+				}
+
+				// invoke parser
+				BeatmapParser.parseAllFiles(beatmapDir);
+
+				// initialize song list
+				if (BeatmapSetList.get().size() > 0) {
+					BeatmapSetList.get().init();
+					setFocus(BeatmapSetList.get().getRandomNode(), -1, true, true);
+				} else
+					MusicController.playThemeSong();
+
+				reloadThread = null;
+			}
+		};
+		reloadThread.start();
+	}
+
 	/**
 	 * Starts the game.
 	 */

src/itdelatrisu/opsu/states/Splash.java

@@ -27,6 +27,7 @@ import itdelatrisu.opsu.audio.MusicController;
 import itdelatrisu.opsu.audio.SoundController;
 import itdelatrisu.opsu.beatmap.BeatmapParser;
 import itdelatrisu.opsu.beatmap.BeatmapSetList;
+import itdelatrisu.opsu.beatmap.BeatmapWatchService;
 import itdelatrisu.opsu.replay.ReplayImporter;
 import itdelatrisu.opsu.ui.UI;
 import itdelatrisu.opsu.ui.animations.AnimatedValue;
@@ -63,6 +64,9 @@ public class Splash extends BasicGameState {
 	/** Whether the skin being loaded is a new skin (for program restarts). */
 	private boolean newSkin = false;
 
+	/** Whether the watch service is newly enabled (for program restarts). */
+	private boolean watchServiceChange = false;
+
 	/** Logo alpha level. */
 	private AnimatedValue logoAlpha;
 
@@ -84,6 +88,9 @@ public class Splash extends BasicGameState {
 		if (Options.getSkin() != null)
 			this.newSkin = (Options.getSkin().getDirectory() != Options.getSkinDir());
 
+		// check if watch service newly enabled
+		this.watchServiceChange = Options.isWatchServiceEnabled() && BeatmapWatchService.get() == null;
+
 		// load Utils class first (needed in other 'init' methods)
 		Utils.init(container, game);
 
@@ -108,13 +115,18 @@ public class Splash extends BasicGameState {
 
 			// resources already loaded (from application restart)
 			if (BeatmapSetList.get() != null) {
-				// reload sounds if skin changed
-				if (newSkin) {
+				if (newSkin || watchServiceChange) {  // need to reload resources
 					thread = new Thread() {
 						@Override
 						public void run() {
+							// reload beatmaps if watch service newly enabled
+							if (watchServiceChange)
+								BeatmapParser.parseAllFiles(Options.getBeatmapDir());
+
+							// reload sounds if skin changed
 							// TODO: only reload each sound if actually needed?
-							SoundController.init();
+							if (newSkin)
+								SoundController.init();
 
 							finished = true;
 							thread = null;