/*
* Copyright (c) 2010, 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. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* 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
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*/
package java.awt;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.atomic.AtomicBoolean;
import java.security.PrivilegedAction;
import java.security.AccessController;
import sun.awt.PeerEvent;
import sun.util.logging.PlatformLogger;
/**
* This utility class is used to suspend execution on a thread
* while still allowing {@code EventDispatchThread} to dispatch events.
* The API methods of the class are thread-safe.
*
* @author Anton Tarasov, Artem Ananiev
*
* @since 1.7
*/
class WaitDispatchSupport implements SecondaryLoop {
private final static PlatformLogger log =
PlatformLogger.getLogger("java.awt.event.WaitDispatchSupport");
private EventDispatchThread dispatchThread;
private EventFilter filter;
private volatile Conditional extCondition;
private volatile Conditional condition;
private long interval;
// Use a shared daemon timer to serve all the WaitDispatchSupports
private static Timer timer;
// When this WDS expires, we cancel the timer task leaving the
// shared timer up and running
private TimerTask timerTask;
private AtomicBoolean keepBlockingEDT = new AtomicBoolean(false);
private AtomicBoolean keepBlockingCT = new AtomicBoolean(false);
private static synchronized void initializeTimer() {
if (timer == null) {
timer = new Timer("AWT-WaitDispatchSupport-Timer", true);
}
}
/**
* Creates a {@code WaitDispatchSupport} instance to
* serve the given event dispatch thread.
*
* @param dispatchThread An event dispatch thread that
* should not stop dispatching events while waiting
*
* @since 1.7
*/
public WaitDispatchSupport(EventDispatchThread dispatchThread) {
this(dispatchThread, null);
}
/**
* Creates a {@code WaitDispatchSupport} instance to
* serve the given event dispatch thread.
*
* @param dispatchThread An event dispatch thread that
* should not stop dispatching events while waiting
* @param extCondition A conditional object used to determine
* if the loop should be terminated
*
* @since 1.7
*/
public WaitDispatchSupport(EventDispatchThread dispatchThread,
Conditional extCond)
{
if (dispatchThread == null) {
throw new IllegalArgumentException("The dispatchThread can not be null");
}
this.dispatchThread = dispatchThread;
this.extCondition = extCond;
this.condition = new Conditional() {
@Override
public boolean evaluate() {
if (log.isLoggable(PlatformLogger.FINEST)) {
log.finest("evaluate(): blockingEDT=" + keepBlockingEDT.get() +
", blockingCT=" + keepBlockingCT.get());
}
boolean extEvaluate =
(extCondition != null) ? extCondition.evaluate() : true;
if (!keepBlockingEDT.get() || !extEvaluate) {
if (timerTask != null) {
timerTask.cancel();
timerTask = null;
}
return false;
}
return true;
}
};
}
/**
* Creates a {@code WaitDispatchSupport} instance to
* serve the given event dispatch thread.
* <p>
* The {@link EventFilter} is set on the {@code dispatchThread}
* while waiting. The filter is removed on completion of the
* waiting process.
* <p>
*
*
* @param dispatchThread An event dispatch thread that
* should not stop dispatching events while waiting
* @param filter {@code EventFilter} to be set
* @param interval A time interval to wait for. Note that
* when the waiting process takes place on EDT
* there is no guarantee to stop it in the given time
*
* @since 1.7
*/
public WaitDispatchSupport(EventDispatchThread dispatchThread,
Conditional extCondition,
EventFilter filter, long interval)
{
this(dispatchThread, extCondition);
this.filter = filter;
if (interval < 0) {
throw new IllegalArgumentException("The interval value must be >= 0");
}
this.interval = interval;
if (interval != 0) {
initializeTimer();
}
}
/**
* @inheritDoc
*/
@Override
public boolean enter() {
log.fine("enter(): blockingEDT=" + keepBlockingEDT.get() +
", blockingCT=" + keepBlockingCT.get());
if (!keepBlockingEDT.compareAndSet(false, true)) {
log.fine("The secondary loop is already running, aborting");
return false;
}
final Runnable run = new Runnable() {
public void run() {
log.fine("Starting a new event pump");
if (filter == null) {
dispatchThread.pumpEvents(condition);
} else {
dispatchThread.pumpEventsForFilter(condition, filter);
}
}
};
// We have two mechanisms for blocking: if we're on the
// dispatch thread, start a new event pump; if we're
// on any other thread, call wait() on the treelock
Thread currentThread = Thread.currentThread();
if (currentThread == dispatchThread) {
log.finest("On dispatch thread: " + dispatchThread);
if (interval != 0) {
log.finest("scheduling the timer for " + interval + " ms");
timer.schedule(timerTask = new TimerTask() {
@Override
public void run() {
if (keepBlockingEDT.compareAndSet(true, false)) {
wakeupEDT();
}
}
}, interval);
}
// Dispose SequencedEvent we are dispatching on the the current
// AppContext, to prevent us from hang - see 4531693 for details
SequencedEvent currentSE = KeyboardFocusManager.
getCurrentKeyboardFocusManager().getCurrentSequencedEvent();
if (currentSE != null) {
log.fine("Dispose current SequencedEvent: " + currentSE);
currentSE.dispose();
}
// In case the exit() method is called before starting
// new event pump it will post the waking event to EDT.
// The event will be handled after the the new event pump
// starts. Thus, the enter() method will not hang.
//
// Event pump should be privileged. See 6300270.
AccessController.doPrivileged(new PrivilegedAction() {
public Object run() {
run.run();
return null;
}
});
} else {
log.finest("On non-dispatch thread: " + currentThread);
synchronized (getTreeLock()) {
if (filter != null) {
dispatchThread.addEventFilter(filter);
}
try {
EventQueue eq = dispatchThread.getEventQueue();
eq.postEvent(new PeerEvent(this, run, PeerEvent.PRIORITY_EVENT));
keepBlockingCT.set(true);
if (interval > 0) {
long currTime = System.currentTimeMillis();
while (keepBlockingCT.get() &&
((extCondition != null) ? extCondition.evaluate() : true) &&
(currTime + interval > System.currentTimeMillis()))
{
getTreeLock().wait(interval);
}
} else {
while (keepBlockingCT.get() &&
((extCondition != null) ? extCondition.evaluate() : true))
{
getTreeLock().wait();
}
}
log.fine("waitDone " + keepBlockingEDT.get() + " " + keepBlockingCT.get());
} catch (InterruptedException e) {
log.fine("Exception caught while waiting: " + e);
} finally {
if (filter != null) {
dispatchThread.removeEventFilter(filter);
}
}
// If the waiting process has been stopped because of the
// time interval passed or an exception occurred, the state
// should be changed
keepBlockingEDT.set(false);
keepBlockingCT.set(false);
}
}
return true;
}
/**
* @inheritDoc
*/
public boolean exit() {
log.fine("exit(): blockingEDT=" + keepBlockingEDT.get() +
", blockingCT=" + keepBlockingCT.get());
if (keepBlockingEDT.compareAndSet(true, false)) {
wakeupEDT();
return true;
}
return false;
}
private final static Object getTreeLock() {
return Component.LOCK;
}
private final Runnable wakingRunnable = new Runnable() {
public void run() {
log.fine("Wake up EDT");
synchronized (getTreeLock()) {
keepBlockingCT.set(false);
getTreeLock().notifyAll();
}
log.fine("Wake up EDT done");
}
};
private void wakeupEDT() {
log.finest("wakeupEDT(): EDT == " + dispatchThread);
EventQueue eq = dispatchThread.getEventQueue();
eq.postEvent(new PeerEvent(this, wakingRunnable, PeerEvent.PRIORITY_EVENT));
}
}