8152974: AWT hang occurrs when sequenced events arrive out of sequence

Reviewed-by: serb, prr, ssadetsky

src/java.desktop/share/classes/java/awt/SequencedEvent.java

@@ -135,11 +135,7 @@ class SequencedEvent extends AWTEvent implements ActiveEvent {
                     if (Thread.currentThread() instanceof EventDispatchThread) {
                         EventDispatchThread edt = (EventDispatchThread)
                                 Thread.currentThread();
-                        edt.pumpEvents(SentEvent.ID, new Conditional() {
-                            public boolean evaluate() {
-                                return !SequencedEvent.this.isFirstOrDisposed();
-                            }
-                        });
+                        edt.pumpEvents(ID, () -> !SequencedEvent.this.isFirstOrDisposed());
                     } else {
                         if (fxAppThreadIsDispatchThread) {
                             fxCheckSequenceThread.start();

test/jdk/java/awt/event/SequencedEvent/SequencedEventTest.java

@@ -0,0 +1,172 @@
+/*
+ * Copyright (c) 2018, 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.
+ */
+
+/*
+ * @test
+ * @bug 8152974
+ * @key headful
+ * @summary AWT hang occurrs when sequenced events arrive out of sequence
+ * @run main SequencedEventTest
+ */
+import sun.awt.AppContext;
+import sun.awt.SunToolkit;
+
+import java.awt.Robot;
+import java.awt.Point;
+import java.awt.Dimension;
+import java.awt.FlowLayout;
+import java.awt.AWTEvent;
+import java.awt.Toolkit;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import java.awt.event.InputEvent;
+import java.lang.reflect.Constructor;
+import java.util.concurrent.CountDownLatch;
+
+import javax.swing.JFrame;
+import javax.swing.JButton;
+import javax.swing.SwingUtilities;
+import javax.swing.JTextArea;
+
+public class SequencedEventTest extends JFrame implements ActionListener {
+    private JButton spamMeButton;
+    private static Robot robot;
+    private static SequencedEventTest window;
+    private static AppContext context;
+
+    public static void main(String[] args) throws Exception {
+        SwingUtilities.invokeAndWait(() ->  {
+            window = new SequencedEventTest();
+            window.setVisible(true);
+        });
+
+        robot = new Robot();
+        robot.waitForIdle();
+
+        Point pt  = window.spamMeButton.getLocationOnScreen();
+        Dimension d = window.spamMeButton.getSize();
+
+        robot.mouseMove(pt.x + d.width / 2, pt.y + d.height / 2);
+        robot.waitForIdle();
+        robot.mousePress(InputEvent.BUTTON1_DOWN_MASK);
+        robot.mouseRelease(InputEvent.BUTTON1_DOWN_MASK);
+        /*
+         *Cannot have robot.waitForIdle() here since it will block the test forever,
+         * in the case of failure and the test will timeout.
+         */
+
+        try {
+            /*
+             * Wait for 2 seconds, and then see if all the sequenced events are dispatched.
+             */
+            Thread.sleep(2000);
+            AWTEvent ev = Toolkit.getDefaultToolkit().getSystemEventQueue().
+                    peekEvent(java.awt.event.FocusEvent.FOCUS_LAST + 1);
+
+            if (ev != null)
+                throw new RuntimeException("Test case failed!");
+        } catch (InterruptedException e) {
+            throw new RuntimeException("Test case failed." + e.getMessage());
+        }
+
+        /*
+         * In the case of failure, the cleanup job cannot be executed, since it
+         * will block the test.
+         */
+        System.out.println("Test case succeeded.");
+        context.dispose();
+        SwingUtilities.invokeAndWait(() -> window.dispose());
+    }
+
+    public SequencedEventTest() {
+        super("Test Window");
+
+        setLayout(new FlowLayout());
+        JTextArea textBlock = new JTextArea("Lorem ipsum dolor sit amet...");
+        add(textBlock);
+
+        spamMeButton = new JButton("Press me!");
+        spamMeButton.addActionListener(this);
+        add(spamMeButton);
+        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+        pack();
+    }
+
+    @Override
+    public void actionPerformed(ActionEvent e) {
+        if(e.getSource() == spamMeButton) {
+            AWTEvent eventOne = getSequencedEvent();
+            AWTEvent eventFour = getSequencedEvent();
+            ThreadGroup tg = new ThreadGroup("TestThreadGroup" );
+            CountDownLatch latch = new CountDownLatch(1);
+            Thread t = new Thread(tg, () -> {
+                context = SunToolkit.createNewAppContext();
+                AWTEvent eventTwo = getSequencedEvent();
+                AWTEvent eventThree = getSequencedEvent();
+
+                Toolkit.getDefaultToolkit().getSystemEventQueue().postEvent(eventThree);
+                Toolkit.getDefaultToolkit().getSystemEventQueue().postEvent(new ActionEvent(this, 0, null));
+                Toolkit.getDefaultToolkit().getSystemEventQueue().postEvent(new ActionEvent(this, 1, null));
+                Toolkit.getDefaultToolkit().getSystemEventQueue().postEvent(eventTwo);
+
+                latch.countDown();
+            });
+
+            t.start();
+            try {
+                latch.await();
+            }catch (InterruptedException ex) {
+                throw new RuntimeException("Test case failed.");
+            }
+
+            Toolkit.getDefaultToolkit().getSystemEventQueue().postEvent(eventFour);
+            Toolkit.getDefaultToolkit().getSystemEventQueue().postEvent(new ActionEvent(this, 2, null));
+            Toolkit.getDefaultToolkit().getSystemEventQueue().postEvent(new ActionEvent(this, 3, null));
+            Toolkit.getDefaultToolkit().getSystemEventQueue().postEvent(eventOne);
+
+            try {
+                t.join();
+            } catch (InterruptedException ex) {
+                throw new RuntimeException("Test case failed.");
+            }
+        }
+    }
+
+    private AWTEvent getSequencedEvent()
+    {
+        AWTEvent wrapMe = new AWTEvent(this, AWTEvent.RESERVED_ID_MAX) {};
+
+        try {
+            /*
+             * SequencedEvent is a package private class, which cannot be instantiated
+             * by importing. So use reflection to create an instance.
+             */
+            Class<? extends AWTEvent> seqClass = (Class<? extends AWTEvent>) Class.forName("java.awt.SequencedEvent");
+            Constructor<? extends AWTEvent> seqConst = seqClass.getConstructor(AWTEvent.class);
+            seqConst.setAccessible(true);;
+            return seqConst.newInstance(wrapMe);
+        } catch (Throwable err) {
+            throw new RuntimeException("Unable to instantiate SequencedEvent",err);
+        }
+    }
+}