Switch to a LRU cache for beatmap background images.

Created a separate BeatmapImageCache class to handle cache operations.  The cache now uses File objects as keys, rather than Beatmap objects (which was buggy).

Also renamed "OsuHitObjectResult" helper class to "HitObjectResult".

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

src/itdelatrisu/opsu/beatmap/Beatmap.java

@@ -22,12 +22,10 @@ import itdelatrisu.opsu.Options;
 
 import java.io.File;
 import java.util.ArrayList;
-import java.util.HashMap;
 import java.util.LinkedList;
 
 import org.newdawn.slick.Color;
 import org.newdawn.slick.Image;
-import org.newdawn.slick.SlickException;
 import org.newdawn.slick.util.Log;
 
 /**
@@ -37,11 +35,13 @@ public class Beatmap implements Comparable<Beatmap> {
 	/** Game modes. */
 	public static final byte MODE_OSU = 0, MODE_TAIKO = 1, MODE_CTB = 2, MODE_MANIA = 3;
 
-	/** Map of all loaded background images. */
-	private static HashMap<Beatmap, Image> bgImageMap = new HashMap<Beatmap, Image>();
+	/** Background image cache. */
+	private static final BeatmapImageCache bgImageCache = new BeatmapImageCache();
 
-	/** Maximum number of cached images before all get erased. */
-	private static final int MAX_CACHE_SIZE = 10;
+	/**
+	 * Returns the background image cache.
+	 */
+	public static BeatmapImageCache getBackgroundImageCache() { return bgImageCache; }
 
 	/** The OSU File object associated with this beatmap. */
 	private File file;
@@ -156,11 +156,11 @@ public class Beatmap implements Comparable<Beatmap> {
 	 * [Events]
 	 */
 
-	/** Background image file name. */
-	public String bg;
+	/** Background image file. */
+	public File bg;
 
-	/** Background video file name. */
-//	public String video;
+	/** Background video file. */
+//	public File video;
 
 	/** All break periods (start time, end time, ...). */
 	public ArrayList<Integer> breaks;
@@ -201,30 +201,6 @@ public class Beatmap implements Comparable<Beatmap> {
 	/** Last object end time (in ms). */
 	public int endTime = -1;
 
-	/**
-	 * Destroys all cached background images and resets the cache.
-	 */
-	public static void clearImageCache() {
-		for (Image img : bgImageMap.values()) {
-			if (img != null && !img.isDestroyed()) {
-				try {
-					img.destroy();
-				} catch (SlickException e) {
-					Log.warn(String.format("Failed to destroy image '%s'.", img.getResourceReference()), e);
-				}
-			}
-		}
-		resetImageCache();
-	}
-
-	/**
-	 * Resets the image cache.
-	 * This does NOT destroy images, so be careful of memory leaks!
-	 */
-	public static void resetImageCache() {
-		bgImageMap = new HashMap<Beatmap, Image>();
-	}
-
 	/**
 	 * Constructor.
 	 * @param file the file associated with this beatmap
@@ -287,12 +263,10 @@ public class Beatmap implements Comparable<Beatmap> {
 		if (bg == null)
 			return false;
 		try {
-			Image bgImage = bgImageMap.get(this);
+			Image bgImage = bgImageCache.get(this);
 			if (bgImage == null) {
-				if (bgImageMap.size() > MAX_CACHE_SIZE)
-					clearImageCache();
-				bgImage = new Image(new File(file.getParentFile(), bg).getAbsolutePath());
-				bgImageMap.put(this, bgImage);
+				bgImage = new Image(bg.getAbsolutePath());
+				bgImageCache.put(this, bgImage);
 			}
 
 			int swidth = width;

src/itdelatrisu/opsu/beatmap/BeatmapImageCache.java

@@ -0,0 +1,86 @@
+/*
+ * opsu! - an open-source osu! client
+ * Copyright (C) 2014, 2015 Jeffrey Han
+ *
+ * opsu! 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.
+ *
+ * opsu! 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 opsu!.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package itdelatrisu.opsu.beatmap;
+
+import java.io.File;
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+import org.newdawn.slick.Image;
+import org.newdawn.slick.SlickException;
+import org.newdawn.slick.util.Log;
+
+/**
+ * LRU cache for beatmap background images.
+ */
+public class BeatmapImageCache {
+	/** Maximum number of cached images. */
+	private static final int MAX_CACHE_SIZE = 10;
+
+	/** Map of all loaded background images. */
+	private LinkedHashMap<File, Image> cache;
+
+	/**
+	 * Constructor.
+	 */
+	@SuppressWarnings("serial")
+	public BeatmapImageCache() {
+		this.cache = new LinkedHashMap<File, Image>(MAX_CACHE_SIZE + 1, 1.1f, true) {
+			@Override
+			protected boolean removeEldestEntry(Map.Entry<File, Image> eldest) {
+				if (size() > MAX_CACHE_SIZE) {
+					// destroy the eldest image
+					Image img = eldest.getValue();
+					if (img != null && !img.isDestroyed()) {
+						try {
+							img.destroy();
+						} catch (SlickException e) {
+							Log.warn(String.format("Failed to destroy image '%s'.", img.getResourceReference()), e);
+						}
+					}
+					return true;
+				}
+				return false;
+			}
+		};
+	}
+
+	/**
+	 * Returns the image mapped to the specified beatmap.
+     * @param beatmap the Beatmap
+	 * @return the Image, or {@code null} if no such mapping exists
+	 */
+	public Image get(Beatmap beatmap) { return cache.get(beatmap.bg); }
+
+	/**
+	 * Creates a mapping from the specified beatmap to the given image.
+	 * @param beatmap the Beatmap
+	 * @param image the Image
+	 * @return the previously mapped Image, or {@code null} if no such mapping existed
+	 */
+	public Image put(Beatmap beatmap, Image image) { return cache.put(beatmap.bg, image); }
+
+	/**
+	 * Removes all entries from the cache.
+	 * <p>
+	 * NOTE: This does NOT destroy the images in the cache, and will cause
+	 * memory leaks if all images have not been destroyed.
+	 */
+	public void clear() { cache.clear(); }
+}

src/itdelatrisu/opsu/beatmap/BeatmapParser.java

@@ -440,7 +440,7 @@ public class BeatmapParser {
 							tokens[2] = tokens[2].replaceAll("^\"|\"$", "");
 							String ext = BeatmapParser.getExtension(tokens[2]);
 							if (ext.equals("jpg") || ext.equals("png"))
-								beatmap.bg = getDBString(tokens[2]);
+								beatmap.bg = new File(dir, getDBString(tokens[2]));
 							break;
 						case "2":  // break periods
 							try {