perf(gui): reduce updates count for memory usage bar (#1000)

- disabled by default
- update only if label changed
- skip updates if app window becomes inactive

jadx-gui/src/main/java/jadx/gui/settings/JadxSettings.java

@@ -35,7 +35,7 @@ public class JadxSettings extends JadxCLIArgs {
 
 	private static final Path USER_HOME = Paths.get(System.getProperty("user.home"));
 	private static final int RECENT_PROJECTS_COUNT = 15;
-	private static final int CURRENT_SETTINGS_VERSION = 9;
+	private static final int CURRENT_SETTINGS_VERSION = 10;
 
 	private static final Font DEFAULT_FONT = new RSyntaxTextArea().getFont();
 
@@ -57,7 +57,7 @@ public class JadxSettings extends JadxCLIArgs {
 	protected String excludedPackages = "";
 	private boolean autoSaveProject = false;
 
-	private boolean showHeapUsageBar = true;
+	private boolean showHeapUsageBar = false;
 
 	private Map<String, WindowLocation> windowPos = new HashMap<>();
 	private int mainWindowExtendedState = JFrame.NORMAL;
@@ -436,6 +436,10 @@ public class JadxSettings extends JadxCLIArgs {
 		if (fromVersion == 8) {
 			fromVersion++;
 		}
+		if (fromVersion == 9) {
+			showHeapUsageBar = false;
+			fromVersion++;
+		}
 		settingsVersion = CURRENT_SETTINGS_VERSION;
 		sync();
 	}

jadx-gui/src/main/java/jadx/gui/ui/HeapUsageBar.java

 package jadx.gui.ui;
 
 import java.awt.*;
-import java.awt.event.ActionEvent;
-import java.awt.event.ActionListener;
 import java.awt.event.MouseAdapter;
 import java.awt.event.MouseEvent;
+import java.util.Objects;
+import java.util.concurrent.TimeUnit;
 
 import javax.swing.*;
+import javax.swing.FocusManager;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import hu.akarnokd.rxjava2.swing.SwingSchedulers;
+import io.reactivex.Flowable;
+import io.reactivex.disposables.Disposable;
+import io.reactivex.schedulers.Schedulers;
+
 import jadx.gui.utils.NLS;
 import jadx.gui.utils.UiUtils;
 
-public class HeapUsageBar extends JProgressBar implements ActionListener {
-	private static final Logger LOG = LoggerFactory.getLogger(HeapUsageBar.class);
+public class HeapUsageBar extends JProgressBar {
 	private static final long serialVersionUID = -8739563124249884967L;
 
-	private static final double TWO_TO_20 = 1048576d;
+	private static final Logger LOG = LoggerFactory.getLogger(HeapUsageBar.class);
+
+	private static final double GB = 1024 * 1024 * 1024;
 
 	private static final Color GREEN = new Color(0, 180, 0);
 	private static final Color RED = new Color(200, 0, 0);
 
 	private final transient Runtime runtime = Runtime.getRuntime();
-	private final transient Timer timer;
+	private final transient FocusManager focusManager = FocusManager.getCurrentManager();
 
 	private final double maxGB;
+	private final long limit;
+	private final String labelTemplate;
+
+	private transient Disposable timer;
+	private transient Color currentColor;
 
 	public HeapUsageBar() {
 		setBorderPainted(false);
 		setStringPainted(true);
-		setValue(10);
-		int maxKB = (int) (runtime.maxMemory() / 1024);
-		setMaximum(maxKB);
-		maxGB = maxKB / TWO_TO_20;
-		update();
-		timer = new Timer(2000, this);
+
+		long maxMemory = runtime.maxMemory();
+		maxGB = maxMemory / GB;
+		limit = maxMemory - UiUtils.MIN_FREE_MEMORY;
+		labelTemplate = NLS.str("heapUsage.text");
+
+		setMaximum((int) (maxMemory / 1024));
+		setColor(GREEN);
+
 		addMouseListener(new MouseAdapter() {
 			@Override
 			public void mouseClicked(MouseEvent e) {
 				Runtime.getRuntime().gc();
-				update();
+				HeapUsageBar.this.update();
 				if (LOG.isDebugEnabled()) {
 					LOG.debug("Memory used: {}", UiUtils.memoryInfo());
 				}
@@ -49,31 +64,74 @@ public class HeapUsageBar extends JProgressBar implements ActionListener {
 		});
 	}
 
-	public void update() {
-		long used = runtime.totalMemory() - runtime.freeMemory();
-		int usedKB = (int) (used / 1024);
-		setValue(usedKB);
-		setString(NLS.str("heapUsage.text", (usedKB / TWO_TO_20), maxGB));
-
-		if ((used + UiUtils.MIN_FREE_MEMORY) > runtime.maxMemory()) {
-			setForeground(RED);
+	@Override
+	public void setVisible(boolean enabled) {
+		super.setVisible(enabled);
+		if (enabled) {
+			startTimer();
 		} else {
-			setForeground(GREEN);
+			reset();
 		}
 	}
 
-	@Override
-	public void actionPerformed(ActionEvent e) {
+	private static class UpdateData {
+		int value;
+		String label;
+		Color color;
+	}
+
+	private static final UpdateData SKIP_UPDATE = new UpdateData();
+
+	private void startTimer() {
+		if (timer != null) {
+			return;
+		}
 		update();
+		timer = Flowable.interval(2, TimeUnit.SECONDS, Schedulers.newThread())
+				.map(i -> prepareUpdate())
+				.filter(update -> update != SKIP_UPDATE)
+				.distinctUntilChanged((a, b) -> Objects.equals(a.label, b.label)) // pass only if label changed
+				.subscribeOn(SwingSchedulers.edt())
+				.subscribe(this::applyUpdate);
 	}
 
-	@Override
-	public void setVisible(boolean aFlag) {
-		super.setVisible(aFlag);
-		if (aFlag) {
-			timer.start();
-		} else {
-			timer.stop();
+	public UpdateData prepareUpdate() {
+		if (focusManager.getActiveWindow() == null) {
+			// skip update if app window not active
+			return SKIP_UPDATE;
+		}
+		UpdateData updateData = new UpdateData();
+		long used = runtime.totalMemory() - runtime.freeMemory();
+		updateData.value = (int) (used / 1024);
+		updateData.label = String.format(labelTemplate, used / GB, maxGB);
+		updateData.color = used > limit ? RED : GREEN;
+		return updateData;
+	}
+
+	public void applyUpdate(UpdateData update) {
+		setValue(update.value);
+		setString(update.label);
+		setColor(update.color);
+	}
+
+	private void setColor(Color color) {
+		if (currentColor != color) {
+			setForeground(color);
+			currentColor = color;
+		}
+	}
+
+	private void update() {
+		UpdateData update = prepareUpdate();
+		if (update != SKIP_UPDATE) {
+			applyUpdate(update);
+		}
+	}
+
+	public void reset() {
+		if (timer != null) {
+			timer.dispose();
+			timer = null;
 		}
 	}
 }

jadx-gui/src/main/java/jadx/gui/ui/MainWindow.java

@@ -1116,6 +1116,7 @@ public class MainWindow extends JFrame {
 		settings.setMainWindowExtendedState(getExtendedState());
 		cancelBackgroundJobs();
 		wrapper.close();
+		heapUsageBar.reset();
 		dispose();
 
 		FileUtils.deleteTempRootDir();