org.apache.batik.util.CleanerThread Maven / Gradle / Ivy
/*
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
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 org.apache.batik.util;
import java.lang.ref.Reference;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.SoftReference;
import java.lang.ref.WeakReference;
import java.lang.ref.PhantomReference;
/**
* One line Class Desc
*
* Complete Class Desc
*
* @author l449433
* @version $Id: CleanerThread.java 1808023 2017-09-11 12:43:22Z ssteiner $
*/
public class CleanerThread extends Thread {
static volatile ReferenceQueue queue = null;
static CleanerThread thread = null;
public static ReferenceQueue getReferenceQueue() {
if ( queue == null ) {
synchronized (CleanerThread.class) {
queue = new ReferenceQueue();
thread = new CleanerThread();
}
}
return queue;
}
/**
* If objects registered with the reference queue associated with
* this class implement this interface then the 'cleared' method
* will be called when the reference is queued.
*/
public interface ReferenceCleared {
/* Called when the reference is cleared */
void cleared();
}
/**
* A SoftReference subclass that automatically registers with
* the cleaner ReferenceQueue.
*/
public abstract static class SoftReferenceCleared extends SoftReference
implements ReferenceCleared {
public SoftReferenceCleared(Object o) {
super (o, CleanerThread.getReferenceQueue());
}
}
/**
* A WeakReference subclass that automatically registers with
* the cleaner ReferenceQueue.
*/
public abstract static class WeakReferenceCleared extends WeakReference
implements ReferenceCleared {
public WeakReferenceCleared(Object o) {
super (o, CleanerThread.getReferenceQueue());
}
}
/**
* A PhantomReference subclass that automatically registers with
* the cleaner ReferenceQueue.
*/
public abstract static class PhantomReferenceCleared
extends PhantomReference
implements ReferenceCleared {
public PhantomReferenceCleared(Object o) {
super (o, CleanerThread.getReferenceQueue());
}
}
protected CleanerThread() {
super("Batik CleanerThread");
setDaemon(true);
start();
}
public void run() {
while(true) {
try {
Reference ref;
try {
ref = queue.remove();
// System.err.println("Cleaned: " + ref);
} catch (InterruptedException ie) {
continue;
}
if (ref instanceof ReferenceCleared) {
ReferenceCleared rc = (ReferenceCleared)ref;
rc.cleared();
}
} catch (ThreadDeath td) {
throw td;
} catch (Throwable t) {
t.printStackTrace();
}
}
}
}