8235638: NPE in LWWindowPeer.getOnscreenGraphics()

Reviewed-by: dmarkov, aivanov

src/java.desktop/macosx/classes/sun/lwawt/LWWindowPeer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2019, 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
@@ -324,7 +324,8 @@ public class LWWindowPeer
     }
 
     protected final Graphics getOnscreenGraphics(Color fg, Color bg, Font f) {
-        if (getSurfaceData() == null) {
+        SurfaceData surfaceData = getSurfaceData();
+        if (surfaceData == null) {
             return null;
         }
         if (fg == null) {
@@ -336,7 +337,7 @@ public class LWWindowPeer
         if (f == null) {
             f = DEFAULT_FONT;
         }
-        return new SunGraphics2D(getSurfaceData(), fg, bg, f);
+        return new SunGraphics2D(surfaceData, fg, bg, f);
     }
 
     @Override

test/jdk/java/awt/Frame/GetGraphicsStressTest/GetGraphicsStressTest.java

@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2019, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import java.awt.Frame;
+import java.awt.Graphics;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * @test
+ * @bug 8235638
+ * @key headful
+ */
+public final class GetGraphicsStressTest {
+
+    static volatile Throwable failed;
+    static volatile long endtime;
+
+    public static void main(final String[] args) throws Exception {
+        // Catch all uncaught exceptions and treat them as test failure
+        Thread.setDefaultUncaughtExceptionHandler((t, e) -> failed = e);
+
+        // Will run the test no more than 20 seconds
+        for (int i = 0; i < 4; i++) {
+            endtime = System.nanoTime() + TimeUnit.SECONDS.toNanos(5);
+            test();
+        }
+    }
+
+    private static void test() throws Exception {
+        Frame f = new Frame();
+        f.setSize(100, 100);
+        f.setLocationRelativeTo(null);
+        f.setVisible(true);
+
+        Thread thread1 = new Thread(() -> {
+            while (!isComplete()) {
+                f.removeNotify();
+                f.addNotify();
+            }
+        });
+        Thread thread2 = new Thread(() -> {
+            while (!isComplete()) {
+                Graphics g = f.getGraphics();
+                if (g != null) {
+                    g.dispose();
+                }
+            }
+        });
+        Thread thread3 = new Thread(() -> {
+            while (!isComplete()) {
+                Graphics g = f.getGraphics();
+                if (g != null) {
+                    g.dispose();
+                }
+            }
+        });
+        Thread thread4 = new Thread(() -> {
+            while (!isComplete()) {
+                Graphics g = f.getGraphics();
+                if (g != null) {
+                    g.drawLine(0, 0, 4, 4); // just in case...
+                    g.dispose();
+                }
+            }
+        });
+        thread1.start();
+        thread2.start();
+        thread3.start();
+        thread4.start();
+        thread1.join();
+        thread2.join();
+        thread3.join();
+        thread4.join();
+
+        f.dispose();
+        if (failed != null) {
+            System.err.println("Test failed");
+            failed.printStackTrace();
+            throw new RuntimeException(failed);
+        }
+    }
+
+    private static boolean isComplete() {
+        return endtime - System.nanoTime() < 0 || failed != null;
+    }
+}