/**
* Copyright (C) 2006 Google Inc.
*
* Licensed 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
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.opensymphony.xwork2.inject.util;
import java.lang.ref.Reference;
import java.lang.ref.ReferenceQueue;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* Starts a background thread that cleans up after reclaimed referents.
*
* @author Bob Lee (crazybob@google.com)
*/
class FinalizableReferenceQueue extends ReferenceQueue<Object> {
private static final Logger logger =
Logger.getLogger(FinalizableReferenceQueue.class.getName());
private FinalizableReferenceQueue() {}
void cleanUp(Reference reference) {
try {
((FinalizableReference) reference).finalizeReferent();
} catch (Throwable t) {
deliverBadNews(t);
}
}
void deliverBadNews(Throwable t) {
logger.log(Level.SEVERE, "Error cleaning up after reference.", t);
}
void start() {
Thread thread = new Thread("FinalizableReferenceQueue") {
@Override
public void run() {
while (true) {
try {
cleanUp(remove());
} catch (InterruptedException e) { /* ignore */ }
}
}
};
thread.setDaemon(true);
thread.start();
}
static ReferenceQueue<Object> instance = createAndStart();
static FinalizableReferenceQueue createAndStart() {
FinalizableReferenceQueue queue = new FinalizableReferenceQueue();
queue.start();
return queue;
}
/**
* Gets instance.
*/
public static ReferenceQueue<Object> getInstance() {
return instance;
}
}