Smarter garbage collection.

Move garbage collector calls to better spots, and run only when total used memory crosses a threshold (150MB) for non-critical areas.

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

src/itdelatrisu/opsu/Utils.java

@@ -98,6 +98,12 @@ public class Utils {
 		Arrays.sort(illegalChars);
 	}
 
+	/** Minimum memory used by the JVM (in bytes) before running "optional" garbage collection. */
+	private static final long GC_MEMORY_THRESHOLD = 150 * 1_000_000L;  // 150MB
+
+	/** Baseline memory used by the JVM (in bytes). */
+	private static long baselineMemoryUsed = 0;
+
 	// game-related variables
 	private static Input input;
 
@@ -689,4 +695,23 @@ public static void setSSLCertValidation(boolean enabled) {
 			HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());
 		} catch (Exception e) {}
 	}
+
+	/**
+	 * Runs the garbage collector.
+	 * @param force if false, garbage collection will only run if current memory
+	 *              usage is above a threshold
+	 */
+	public static final void gc(boolean force) {
+		if (!force && getUsedMemory() - baselineMemoryUsed < GC_MEMORY_THRESHOLD)
+			return;
+
+		System.gc();
+		baselineMemoryUsed = getUsedMemory();
+	}
+
+	/** Returns the amount memory used by the JVM (in bytes). */
+	public static long getUsedMemory() {
+		Runtime r = Runtime.getRuntime();
+		return r.totalMemory() - r.freeMemory();
+	}
 }

src/itdelatrisu/opsu/audio/MusicController.java

@@ -19,6 +19,7 @@
 package itdelatrisu.opsu.audio;
 
 import itdelatrisu.opsu.ErrorHandler;
+import itdelatrisu.opsu.Utils;
 import itdelatrisu.opsu.beatmap.Beatmap;
 import itdelatrisu.opsu.beatmap.BeatmapParser;
 import itdelatrisu.opsu.beatmap.TimingPoint;
@@ -103,7 +104,7 @@ public static void play(final Beatmap beatmap, final boolean loop, final boolean
 			}
 
 			reset();
-			System.gc();
+			Utils.gc(false);
 
 			switch (BeatmapParser.getExtension(beatmap.audioFilename.getName())) {
 			case "ogg":

src/itdelatrisu/opsu/beatmap/BeatmapSetList.java

@@ -201,7 +201,7 @@ else if (ePrev != null && ePrev.index == expandedIndex)
 			File audioFile = MusicController.getBeatmap().audioFilename;
 			if (audioFile != null && audioFile.equals(beatmap.audioFilename)) {
 				MusicController.reset();
-				System.gc();  // TODO: why can't files be deleted without calling this?
+				Utils.gc(true);  // TODO: why can't files be deleted without calling this?
 			}
 		}
 

src/itdelatrisu/opsu/states/Game.java

@@ -1702,6 +1702,8 @@ public void loadBeatmap(Beatmap beatmap) {
 			BeatmapDB.load(beatmap, BeatmapDB.LOAD_ARRAY);
 		BeatmapParser.parseHitObjects(beatmap);
 		HitSound.setDefaultSampleSet(beatmap.sampleSet);
+
+		Utils.gc(true);
 	}
 
 	/**
@@ -1741,8 +1743,6 @@ public void resetGameData() {
 			video = null;
 		}
 		videoSeekTime = 0;
-
-		System.gc();
 	}
 
 	/**

src/itdelatrisu/opsu/states/Splash.java

@@ -137,6 +137,8 @@ public void run() {
 							if (newSkin)
 								SoundController.init();
 
+							Utils.gc(true);
+
 							finished = true;
 							thread = null;
 						}
@@ -169,6 +171,8 @@ public void run() {
 						// load sounds
 						SoundController.init();
 
+						Utils.gc(true);
+
 						finished = true;
 						thread = null;
 					}