1 /*
   2  * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package sun.lwawt.macosx;
  27 
  28 import sun.awt.AWTAutoShutdown;
  29 
  30 /**
  31  * Support class for keeping AWT alive when it's embedded in another toolkit.
  32  * This is done by sending a dummy native event to the native event loop.
  33  */
  34 final class AWTKeepAlive extends Thread {
  35     private final static AWTKeepAlive theInstance = new AWTKeepAlive();
  36     static {
  37         theInstance.setName("AWTKeepAlive");
  38         theInstance.setDaemon(true);
  39     }
  40 
  41     /**
  42      * An interval for sending pings.
  43      *
  44      * Generally, it must be twice as less than the SAFETY_TIMEOUT
  45      * in an auto-shutdown machinery of the mebedder's toolkit.
  46      * Both AWT and FX use 1000 ms safety interval currently.
  47      */
  48     private static final int PING_TIMEOUT = 500;
  49 
  50     /**
  51      * Activate the AWTKeepAlive thread.
  52      */
  53     public static void activate() {
  54         theInstance.start();
  55     }
  56 
  57     @Override
  58     public void run() {
  59         try {
  60             do {
  61                 if (!AWTAutoShutdown.getInstance().isReadyToShutdown()) {
  62                     // Send a dummy native event
  63                     LWCToolkit.getLWCToolkit().syncNativeQueue(1);
  64                 }
  65                 Thread.sleep(PING_TIMEOUT);
  66             } while (true);
  67         } catch (InterruptedException ex) {
  68         }
  69     }
  70 }