8305578: X11GraphicsDevice.pGetBounds() is slow in remote X11 sessions

Reviewed-by: avu, serb

src/java.desktop/unix/classes/sun/awt/X11/XToolkit.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2023, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -116,6 +116,7 @@ import java.security.PrivilegedAction;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
+import java.util.Hashtable;
 import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.Map;
@@ -358,6 +359,11 @@ public final class XToolkit extends UNIXToolkit implements Runnable {
                         } finally {
                             awtLock();
                         }
+                    } else {
+                        final XAtom XA_NET_WORKAREA = XAtom.get("_NET_WORKAREA");
+                        final boolean rootWindowWorkareaResized = (ev.get_type() == XConstants.PropertyNotify
+                                && ev.get_xproperty().get_atom() == XA_NET_WORKAREA.getAtom());
+                        if (rootWindowWorkareaResized) resetScreenInsetsCache();
                     }
                 }
             });
@@ -843,8 +849,7 @@ public final class XToolkit extends UNIXToolkit implements Runnable {
      * When two screens overlap and the first contains a dock(*****), then
      * _NET_WORKAREA may start at point x1,y1 and end at point x2,y2.
      */
-    @Override
-    public Insets getScreenInsets(final GraphicsConfiguration gc) {
+    private Insets getScreenInsetsImpl(final GraphicsConfiguration gc) {
         GraphicsDevice gd = gc.getDevice();
         XNETProtocol np = XWM.getWM().getNETProtocol();
         if (np == null || !(gd instanceof X11GraphicsDevice) || !np.active()) {
@@ -872,6 +877,30 @@ public final class XToolkit extends UNIXToolkit implements Runnable {
         }
     }
 
+    private void resetScreenInsetsCache() {
+        final GraphicsDevice[] devices = ((X11GraphicsEnvironment)GraphicsEnvironment.
+                getLocalGraphicsEnvironment()).getScreenDevices();
+        for (var gd : devices) {
+            ((X11GraphicsDevice)gd).resetInsets();
+        }
+    }
+
+    @Override
+    public Insets getScreenInsets(final GraphicsConfiguration gc) {
+        final X11GraphicsDevice device = (X11GraphicsDevice) gc.getDevice();
+        Insets insets = device.getInsets();
+        if (insets == null) {
+            synchronized (device) {
+                insets = device.getInsets();
+                if (insets == null) {
+                    insets = getScreenInsetsImpl(gc);
+                    device.setInsets(insets);
+                }
+            }
+        }
+        return (Insets) insets.clone();
+    }
+
     /*
      * The current implementation of disabling background erasing for
      * canvases is that we don't set any native background color

src/java.desktop/unix/classes/sun/awt/X11GraphicsDevice.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -30,6 +30,7 @@ import java.awt.DisplayMode;
 import java.awt.GraphicsConfiguration;
 import java.awt.GraphicsDevice;
 import java.awt.GraphicsEnvironment;
+import java.awt.Insets;
 import java.awt.Rectangle;
 import java.awt.Window;
 import java.security.AccessController;
@@ -37,6 +38,7 @@ import java.security.PrivilegedAction;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.Objects;
 
 import sun.awt.util.ThreadGroupUtils;
 import sun.java2d.SunGraphicsEnvironment;
@@ -66,12 +68,15 @@ public final class X11GraphicsDevice extends GraphicsDevice
     private static Boolean xrandrExtSupported;
     private SunDisplayChanger topLevels = new SunDisplayChanger();
     private DisplayMode origDisplayMode;
+    private volatile Rectangle bounds;
+    private volatile Insets insets;
     private boolean shutdownHookRegistered;
     private int scale;
 
     public X11GraphicsDevice(int screennum) {
         this.screen = screennum;
         this.scale = initScaleFactor();
+        this.bounds = getBoundsImpl();
     }
 
     /**
@@ -118,7 +123,7 @@ public final class X11GraphicsDevice extends GraphicsDevice
         return Region.clipRound(x / (double)getScaleFactor());
     }
 
-    public Rectangle getBounds() {
+    private Rectangle getBoundsImpl() {
         Rectangle rect = pGetBounds(getScreen());
         if (getScaleFactor() != 1) {
             rect.x = scaleDown(rect.x);
@@ -129,6 +134,23 @@ public final class X11GraphicsDevice extends GraphicsDevice
         return rect;
     }
 
+    public Rectangle getBounds() {
+        return bounds.getBounds();
+    }
+
+    public Insets getInsets() {
+        return insets;
+    }
+
+    public void setInsets(Insets newInsets) {
+        Objects.requireNonNull(newInsets);
+        insets = newInsets;
+    }
+
+    public void resetInsets() {
+        insets = null;
+    }
+
     /**
      * Returns the identification string associated with this graphics
      * device.
@@ -516,6 +538,8 @@ public final class X11GraphicsDevice extends GraphicsDevice
     @Override
     public synchronized void displayChanged() {
         scale = initScaleFactor();
+        bounds = getBoundsImpl();
+        insets = null;
         // On X11 the visuals do not change, and therefore we don't need
         // to reset the defaultConfig, config, doubleBufferVisuals,
         // neither do we need to reset the native data.