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/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* This file incorporates work covered by the following license notice:
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed
* with this work for additional information regarding copyright
* ownership. The ASF licenses this file to you under the Apache
* License, Version 2.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.apache.org/licenses/LICENSE-2.0 .
*/
package com.sun.star.lib.util;
import java.util.LinkedList;
/**
* Helper class to asynchronously execute finalize methods.
*
* <p>Current JVMs seem not to be robust against long-running finalize methods,
* in that such long-running finalize methods may lead to OutOfMemoryErrors. This
* class mitigates the problem by asynchronously shifting the bodies of
* potentially long-running finalize methods into an extra thread. Classes that
* make use of this in their finalize methods are the proxies used in the
* intra-process JNI UNO bridge and the inter-process Java URP UNO bridge (where
* in both cases finalizers lead to synchronous UNO release calls).</p>
*
* <p>If JVMs are getting more mature and should no longer have problems with
* long-running finalize mehtods, this class could be removed again.</p>
*/
public final class AsynchronousFinalizer {
/**
* Add a job to be executed asynchronously.
*
* <p>The run method of the given job is called exactly once. If it terminates
* abnormally by throwing any Throwable, that is ignored.</p>
*
* @param job represents the body of some finalize method; must not be null.
*/
public static void add(Job job) {
synchronized (queue) {
boolean first = queue.isEmpty();
queue.add(job);
if (first) {
queue.notify();
}
}
}
/**
* An interface to represent bodies of finalize methods.
*
* Similar to <code>Runnable</code>, except that the run method may throw any
* <code>Throwable</code> (which is effectively ignored by
* <code>AsynchronousFinalizer.add</code>, similar to any <code>Throwables</code>
* raised by finalize being ignored).
*/
public interface Job {
void run() throws Throwable;
}
private static final LinkedList<Job> queue = new LinkedList<Job>();
static {
Thread t = new Thread() {
public void run() {
for (;;) {
Job j;
synchronized (queue) {
while (queue.isEmpty()) {
try {
queue.wait();
} catch (InterruptedException e) {}
}
j = queue.remove(0);
}
try {
j.run();
} catch (Throwable e) {}
}
}
};
t.setDaemon(true);
t.start();
}
private AsynchronousFinalizer() {}
}
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