Refractor sleep in Scene rendering loop for better performance

~10 us improvement

2 files changed, 37 insertions, 28 deletions

diff --git a/src/subconscious/graphics/Scene.java b/src/subconscious/graphics/Scene.java
index 05161d5..c5938f1 100644
--- a/src/subconscious/graphics/Scene.java
+++ b/src/subconscious/graphics/Scene.java
@@ -8,6 +8,8 @@ import subconscious.graphics.widget.Dynamic;
 
 import subconscious.graphics.widget.PerfView;
 
+import java.lang.Thread;
+
 import java.util.ArrayList;
 import java.util.Map;
 
@@ -58,9 +60,10 @@ public abstract class Scene extends Panel
 	public final String UNIQUE_NAME;
 	private static int absScenesCount = 0;
 
-	protected final long DESIRED_FPS = 60;
-	protected final long DESIRED_DELTA_LOOP = (1000*1000*1000)/DESIRED_FPS;
-	protected final Map<RenderingHints.Key, ?> RENDERING_HINTS = Map.of(
+	public static final long DESIRED_FPS = 80;
+	public static final long DESIRED_DELTA_LOOP_NS = (1000*1000*1000)/DESIRED_FPS;
+	public static final long NO_DELAYS_PER_YELD = 15;
+	public static final Map<RenderingHints.Key, ?> RENDERING_HINTS = Map.of(
 		RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON,
 		RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON,
 		RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_SPEED,
@@ -119,7 +122,7 @@ public abstract class Scene extends Panel
 		this.build();
 
 		// TODO: this will be controlled in the settings
-		// this.addWidget(new PerfView("default-perfview", 0, 0));
+		this.addWidget(new PerfView("default-perfview", 0, 0));
 	}
 
 	public Scene(Game game) {
@@ -196,12 +199,9 @@ public abstract class Scene extends Panel
 
 	/* runnable implementation */
 	public void run() {
-		long beginLoopTime;
-		long endLoopTime;
-		long currentUpdateTime = System.nanoTime();
-		long lastUpdateTime;
-		long deltaLoop;
-		long gameDeltaTime;
+		long beforeTime, afterTime, timeDiff = 0, sleepTime;
+		long overSleepTime = 0L;
+		int noDelays = 0;
 
 		this.running = true;
 
@@ -222,12 +222,13 @@ public abstract class Scene extends Panel
 		}
 
 		while (running) {
-			beginLoopTime = System.nanoTime();
+			beforeTime = System.nanoTime();
 
+			// render on a double buffer
 			do {
 				do {
 					Graphics2D g = (Graphics2D) this.buffer.getDrawGraphics();
-					g.addRenderingHints(this.RENDERING_HINTS);
+					g.addRenderingHints(Scene.RENDERING_HINTS);
 					g.setFont(Fonts.DEFAULT);
 					this.render(g);
 					this.renderWidgets(g);
@@ -245,26 +246,34 @@ public abstract class Scene extends Panel
 				// can be ignored
 			}
 
-			lastUpdateTime = currentUpdateTime;
-			currentUpdateTime = System.nanoTime();
+			// update game and widgets
+			this.update(timeDiff);
+			this.updateWidgets(timeDiff);
+			this.game.update(timeDiff);
 
-			gameDeltaTime = currentUpdateTime - lastUpdateTime;
+			afterTime = System.nanoTime();
+			timeDiff = afterTime - beforeTime;
+			sleepTime = (Scene.DESIRED_DELTA_LOOP_NS - timeDiff) - overSleepTime;
 
-			// TODO: remove Scene.update?
-			this.update(gameDeltaTime);
-			this.updateWidgets(gameDeltaTime);
-			this.game.update(gameDeltaTime);
+			// if sleep is needed (too fast)
+			if (sleepTime > 0) {
+				try {
+					Thread.sleep(sleepTime/(1000*1000));
+				} catch (InterruptedException ex) {
+					// ex.printStackTrace();
+				}
 
-			endLoopTime = System.nanoTime();
-			deltaLoop = endLoopTime - beginLoopTime;
+				overSleepTime = (System.nanoTime() - afterTime) - sleepTime;
 
-			if (deltaLoop > this.DESIRED_DELTA_LOOP) {
-				// TODO: late => skip frame
+
+			// if sleep is not needed (too slow)
 			} else {
-				try {
-					Thread.sleep((this.DESIRED_DELTA_LOOP - deltaLoop)/(1000*1000));
-				} catch (InterruptedException ex) {
-					ex.printStackTrace();
+				overSleepTime = 0L;
+				// if the thread has been late for too much time, give up
+				// the cpu to other threads
+				if (++noDelays >= Scene.NO_DELAYS_PER_YELD) {
+					Thread.yield();
+					noDelays = 0;
 				}
 			}
 
diff --git a/src/subconscious/graphics/widget/ActorInfo.java b/src/subconscious/graphics/widget/ActorInfo.java
index a2b25ad..82aecd4 100644
--- a/src/subconscious/graphics/widget/ActorInfo.java
+++ b/src/subconscious/graphics/widget/ActorInfo.java
@@ -58,7 +58,7 @@ public class ActorInfo extends Widget {
 		this.observingActor = actor;
 	}
 
-	public void unsetActor() {
+	public synchronized void unsetActor() {
 		this.observingActor = null;
 	}