/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* 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
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/**
* This class is to let AWT shutdown automatically when a user is done
* with AWT. It tracks AWT state using the following parameters:
* <ul>
* <li><code>peerMap</code> - the map between the existing peer objects
* and their associated targets
* <li><code>toolkitThreadBusy</code> - whether the toolkit thread
* is waiting for a new native event to appear in its queue
* or is dispatching an event
* <li><code>busyThreadSet</code> - a set of all the event dispatch
* threads that are busy at this moment, i.e. those that are not
* waiting for a new event to appear in their event queue.
* </ul><p>
* AWT is considered to be in ready-to-shutdown state when
* <code>peerMap</code> is empty and <code>toolkitThreadBusy</code>
* is false and <code>busyThreadSet</code> is empty.
* The internal AWTAutoShutdown logic secures that the single non-daemon
* thread (<code>blockerThread</code>) is running when AWT is not in
* ready-to-shutdown state. This blocker thread is to prevent AWT from
* exiting since the toolkit thread is now daemon and all the event
* dispatch threads are started only when needed. Once it is detected
* that AWT is in ready-to-shutdown state this blocker thread waits
* for a certain timeout and if AWT state doesn't change during timeout
* this blocker thread terminates all the event dispatch threads and
* exits.
*/
/**
* This lock object is used to synchronize shutdown operations.
*/
/**
* This lock object is to secure that when a new blocker thread is
* started it will be the first who acquire the main lock after
* the thread that created the new blocker released the main lock
* by calling lock.wait() to wait for the blocker to start.
*/
/**
* This set keeps references to all the event dispatch threads that
* are busy at this moment, i.e. those that are not waiting for a
* new event to appear in their event queue.
* Access is synchronized on the main lock object.
*/
/**
* Indicates whether the toolkit thread is waiting for a new native
* event to appear or is dispatching an event.
*/
private boolean toolkitThreadBusy = false;
/**
* This is a map between components and their peers.
* we should work with in under activationLock&mainLock lock.
*/
/**
* References the alive non-daemon thread that is currently used
* for keeping AWT from exiting.
*/
/**
* We need this flag to secure that AWT state hasn't changed while
* we were waiting for the safety timeout to pass.
*/
private boolean timeoutPassed = false;
/**
* Once we detect that AWT is ready to shutdown we wait for a certain
* timeout to pass before stopping event dispatch threads.
*/
/**
* Constructor method is intentionally made private to secure
* a single instance. Use getInstance() to reference it.
*
* @see AWTAutoShutdown#getInstance
*/
private AWTAutoShutdown() {}
/**
* Returns reference to a single AWTAutoShutdown instance.
*/
return theInstance;
}
/**
* Notify that the toolkit thread is not waiting for a native event
* to appear in its queue.
*
* @see AWTAutoShutdown#notifyToolkitThreadFree
* @see AWTAutoShutdown#setToolkitBusy
* @see AWTAutoShutdown#isReadyToShutdown
*/
public static void notifyToolkitThreadBusy() {
getInstance().setToolkitBusy(true);
}
/**
* Notify that the toolkit thread is waiting for a native event
* to appear in its queue.
*
* @see AWTAutoShutdown#notifyToolkitThreadFree
* @see AWTAutoShutdown#setToolkitBusy
* @see AWTAutoShutdown#isReadyToShutdown
*/
public static void notifyToolkitThreadFree() {
getInstance().setToolkitBusy(false);
}
/**
* Add a specified thread to the set of busy event dispatch threads.
* If this set already contains the specified thread or the thread is null,
* the call leaves this set unchanged and returns silently.
*
* @param thread thread to be added to this set, if not present.
* @see AWTAutoShutdown#notifyThreadFree
* @see AWTAutoShutdown#isReadyToShutdown
*/
return;
}
synchronized (activationLock) {
synchronized (mainLock) {
if (blockerThread == null) {
} else if (isReadyToShutdown()) {
timeoutPassed = false;
}
}
}
}
/**
* Remove a specified thread from the set of busy event dispatch threads.
* If this set doesn't contain the specified thread or the thread is null,
* the call leaves this set unchanged and returns silently.
*
* @param thread thread to be removed from this set, if present.
* @see AWTAutoShutdown#notifyThreadBusy
* @see AWTAutoShutdown#isReadyToShutdown
*/
return;
}
synchronized (activationLock) {
synchronized (mainLock) {
if (isReadyToShutdown()) {
timeoutPassed = false;
}
}
}
}
/**
* Notify that the peermap has been updated, that means a new peer
* has been created or some existing peer has been disposed.
*
* @see AWTAutoShutdown#isReadyToShutdown
*/
void notifyPeerMapUpdated() {
synchronized (activationLock) {
synchronized (mainLock) {
} else {
timeoutPassed = false;
}
}
}
}
/**
* Determine whether AWT is currently in ready-to-shutdown state.
* AWT is considered to be in ready-to-shutdown state if
* <code>peerMap</code> is empty and <code>toolkitThreadBusy</code>
* is false and <code>busyThreadSet</code> is empty.
*
* @return true if AWT is in ready-to-shutdown state.
*/
private boolean isReadyToShutdown() {
return (!toolkitThreadBusy &&
busyThreadSet.isEmpty());
}
/**
* Notify about the toolkit thread state change.
*
* @param busy true if the toolkit thread state changes from idle
* to busy.
* @see AWTAutoShutdown#notifyToolkitThreadBusy
* @see AWTAutoShutdown#notifyToolkitThreadFree
* @see AWTAutoShutdown#isReadyToShutdown
*/
if (busy != toolkitThreadBusy) {
synchronized (activationLock) {
synchronized (mainLock) {
if (busy != toolkitThreadBusy) {
if (busy) {
if (blockerThread == null) {
} else if (isReadyToShutdown()) {
timeoutPassed = false;
}
} else {
if (isReadyToShutdown()) {
timeoutPassed = false;
}
}
}
}
}
}
}
/**
* Implementation of the Runnable interface.
* Incapsulates the blocker thread functionality.
*
* @see AWTAutoShutdown#isReadyToShutdown
*/
public void run() {
boolean interrupted = false;
synchronized (mainLock) {
try {
/* Notify that the thread is started. */
while (blockerThread == currentThread) {
timeoutPassed = false;
/*
* This loop is introduced to handle the following case:
* it is possible that while we are waiting for the
* safety timeout to pass AWT state can change to
* not-ready-to-shutdown and back to ready-to-shutdown.
* In this case we have to wait once again.
* NOTE: we shouldn't break into the outer loop
* in this case, since we may never be notified
* in an outer infinite wait at this point.
*/
while (isReadyToShutdown()) {
if (timeoutPassed) {
timeoutPassed = false;
break;
}
timeoutPassed = true;
}
}
} catch (InterruptedException e) {
interrupted = true;
} finally {
if (blockerThread == currentThread) {
}
}
}
if (!interrupted) {
}
}
}
/**
* Creates and starts a new blocker thread. Doesn't return until
* the new blocker thread starts.
*/
private void activateBlockerThread() {
try {
/* Wait for the blocker thread to start. */
} catch (InterruptedException e) {
e.printStackTrace();
}
}
synchronized (activationLock) {
synchronized (mainLock) {
}
}
}
synchronized (activationLock) {
synchronized (mainLock) {
}
}
}
}
synchronized (activationLock) {
synchronized (mainLock) {
}
}
}
synchronized (activationLock) {
synchronized (mainLock) {
}
}
}
}
} // class AWTAutoShutdown