Refactor usage widget to not create a new thread

src/main/java/amidst/gui/main/viewer/PerViewerFacadeInjector.java

@@ -21,6 +21,7 @@
 import amidst.gui.main.viewer.widget.BiomeExporterProgressWidget;
 import amidst.gui.main.viewer.widget.BiomeToggleWidget;
 import amidst.gui.main.viewer.widget.BiomeWidget;
+import amidst.gui.main.viewer.widget.CpuUsageTimer;
 import amidst.gui.main.viewer.widget.CursorInformationWidget;
 import amidst.gui.main.viewer.widget.DebugWidget;
 import amidst.gui.main.viewer.widget.FpsWidget;
@@ -57,7 +58,7 @@ private static List<Widget> createWidgets(
 		BiomeToggleWidget biomeToggleWidget = new BiomeToggleWidget(CornerAnchorPoint.BOTTOM_RIGHT, biomeWidget, biomeSelection);
 		WorldOptions worldOptions = world.getWorldOptions();
 		return Arrays.asList(
-				new FpsWidget(                  CornerAnchorPoint.BOTTOM_LEFT,   new FramerateTimer(2),              settings.showFPS),
+				new FpsWidget(                  CornerAnchorPoint.BOTTOM_LEFT,   new FramerateTimer(2),       new CpuUsageTimer(1),      settings.showFPS),
 				new ScaleWidget(                CornerAnchorPoint.BOTTOM_CENTER, zoom,                               settings.showScale),
 				new SeedAndWorldTypeWidget(     CornerAnchorPoint.TOP_LEFT,      worldOptions.getWorldSeed(), worldOptions.getWorldType()),
 				new SelectedIconWidget(         CornerAnchorPoint.TOP_LEFT,      worldIconSelection),

src/main/java/amidst/gui/main/viewer/widget/CpuUsageTimer.java

@@ -0,0 +1,46 @@
+package amidst.gui.main.viewer.widget;
+
+import java.lang.management.ManagementFactory;
+
+import com.sun.management.OperatingSystemMXBean;
+
+import amidst.documentation.AmidstThread;
+import amidst.documentation.CalledOnlyBy;
+import amidst.documentation.NotThreadSafe;
+
+@SuppressWarnings("restriction")
+@NotThreadSafe
+public class CpuUsageTimer {
+	private final OperatingSystemMXBean operatingSystemMXBean;
+
+	private long lastTime;
+	private long msPerUpdate;
+
+	private float currentUsage = 0.0f;
+
+	@CalledOnlyBy(AmidstThread.EDT)
+	public CpuUsageTimer(int updatesPerSecond) {
+		this.operatingSystemMXBean = (OperatingSystemMXBean) ManagementFactory.getOperatingSystemMXBean();
+		msPerUpdate = (long) (1000d / updatesPerSecond);
+		reset();
+	}
+
+	@CalledOnlyBy(AmidstThread.EDT)
+	public void reset() {
+		lastTime = System.currentTimeMillis();
+	}
+
+	@CalledOnlyBy(AmidstThread.EDT)
+	public void tick() {
+		long currentTime = System.currentTimeMillis();
+		if (currentTime - lastTime > msPerUpdate) {
+			currentUsage = (float) (operatingSystemMXBean.getProcessCpuLoad() * 100);
+			lastTime = currentTime;
+		}
+	}
+
+	@CalledOnlyBy(AmidstThread.EDT)
+	public float getCurrentUsage() {
+		return currentUsage;
+	}
+}

src/main/java/amidst/gui/main/viewer/widget/FpsWidget.java

@@ -1,49 +1,34 @@
 package amidst.gui.main.viewer.widget;
 
-import java.lang.management.ManagementFactory;
 import java.util.Arrays;
 import java.util.List;
-import java.util.Timer;
-import java.util.TimerTask;
-
-import com.sun.management.OperatingSystemMXBean;
-
 import amidst.documentation.AmidstThread;
 import amidst.documentation.CalledOnlyBy;
 import amidst.documentation.NotThreadSafe;
 import amidst.settings.Setting;
 
-@SuppressWarnings("restriction")
 @NotThreadSafe
 public class FpsWidget extends TextWidget {
 	private final FramerateTimer fpsTimer;
+	private final CpuUsageTimer usageTimer;
 	private final Setting<Boolean> isVisibleSetting;
-	private final OperatingSystemMXBean operatingSystemMXBean;
-	private final Timer usageTimer = new Timer("UsageTimer", true);
-	private volatile double cpuLoad;
 
 	@CalledOnlyBy(AmidstThread.EDT)
-	public FpsWidget(CornerAnchorPoint anchor, FramerateTimer fpsTimer, Setting<Boolean> isVisibleSetting) {
+	public FpsWidget(CornerAnchorPoint anchor, FramerateTimer fpsTimer, CpuUsageTimer usageTimer, Setting<Boolean> isVisibleSetting) {
 		super(anchor);
 		this.fpsTimer = fpsTimer;
+		this.usageTimer = usageTimer;
 		this.isVisibleSetting = isVisibleSetting;
-		this.operatingSystemMXBean = (OperatingSystemMXBean) ManagementFactory.getOperatingSystemMXBean();
-
-		usageTimer.scheduleAtFixedRate(new TimerTask() {
-			@Override
-			public void run() {
-				cpuLoad = operatingSystemMXBean.getProcessCpuLoad() * 100;
-			}
-		}, 0, 500);
 	}
 
 	@CalledOnlyBy(AmidstThread.EDT)
 	@Override
 	protected List<String> updateTextLines() {
 		fpsTimer.tick();
+		usageTimer.tick();
 		if (isVisibleSetting.get()) {
 			return Arrays.asList(
-					"CPU: " + String.format("%.1f", cpuLoad) + "%",
+					"CPU: " + String.format("%.1f", usageTimer.getCurrentUsage()) + "%",
 					"FPS: " + String.format("%.1f", fpsTimer.getCurrentFPS()));
 		} else {
 			return null;

src/main/java/amidst/gui/main/viewer/widget/FramerateTimer.java

@@ -14,7 +14,7 @@ public class FramerateTimer {
 
 	@CalledOnlyBy(AmidstThread.EDT)
 	public FramerateTimer(int updatesPerSecond) {
-		msPerUpdate = (long) (1000f * (1f / updatesPerSecond));
+		msPerUpdate = (long) (1000d / updatesPerSecond);
 		reset();
 	}