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/beatmap/BeatmapParser.java

@@ -19,6 +19,7 @@
 package itdelatrisu.opsu.beatmap;
 
 import itdelatrisu.opsu.ErrorHandler;
+import itdelatrisu.opsu.Options;
 import itdelatrisu.opsu.Utils;
 import itdelatrisu.opsu.db.BeatmapDB;
 import itdelatrisu.opsu.io.MD5InputStreamWrapper;
@@ -83,6 +84,10 @@ public class BeatmapParser {
 		// create a new BeatmapSetList
 		BeatmapSetList.create();
 
+		// create a new watch service
+		if (Options.isWatchServiceEnabled())
+			BeatmapWatchService.create();
+
 		// parse all directories
 		parseDirectories(root.listFiles());
 	}
@@ -110,6 +115,9 @@ public class BeatmapParser {
 		List<Beatmap> cachedBeatmaps = new LinkedList<Beatmap>();  // loaded from database
 		List<Beatmap> parsedBeatmaps = new LinkedList<Beatmap>();  // loaded from parser
 
+		// watch service
+		BeatmapWatchService ws = (Options.isWatchServiceEnabled()) ? BeatmapWatchService.get() : null;
+
 		// parse directories
 		BeatmapSetNode lastNode = null;
 		for (File dir : dirs) {
@@ -162,6 +170,8 @@ public class BeatmapParser {
 			if (!beatmaps.isEmpty()) {
 				beatmaps.trimToSize();
 				allBeatmaps.add(beatmaps);
+				if (ws != null)
+					ws.registerAll(dir.toPath());
 			}
 
 			// stop parsing files (interrupted)