117 lines
3.5 KiB
Java
117 lines
3.5 KiB
Java
/*
|
|
* Copyright (c) 1997, 2012, 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
|
|
* or visit www.oracle.com if you need additional information or have any
|
|
* questions.
|
|
*/
|
|
|
|
package com.sun.istack.internal;
|
|
|
|
import java.util.concurrent.ConcurrentLinkedQueue;
|
|
import java.lang.ref.WeakReference;
|
|
|
|
/**
|
|
* Pool of reusable objects that are indistinguishable from each other,
|
|
* such as JAXB marshallers.
|
|
*
|
|
* @author Kohsuke Kawaguchi
|
|
*/
|
|
public interface Pool<T> {
|
|
|
|
/**
|
|
* Gets a new object from the pool.
|
|
*
|
|
* <p>
|
|
* If no object is available in the pool, this method creates a new one.
|
|
*/
|
|
@NotNull T take();
|
|
|
|
/**
|
|
* Returns an object back to the pool.
|
|
*/
|
|
void recycle(@NotNull T t);
|
|
|
|
/**
|
|
* Default implementation that uses {@link ConcurrentLinkedQueue}
|
|
* as the data store.
|
|
*
|
|
* <h2>Note for Implementors</h2>
|
|
* <p>
|
|
* Don't rely on the fact that this class extends from {@link ConcurrentLinkedQueue}.
|
|
*/
|
|
public abstract class Impl<T> implements Pool<T> {
|
|
|
|
private volatile WeakReference<ConcurrentLinkedQueue<T>> queue;
|
|
|
|
/**
|
|
* Gets a new object from the pool.
|
|
*
|
|
* <p>
|
|
* If no object is available in the pool, this method creates a new one.
|
|
*
|
|
* @return
|
|
* always non-null.
|
|
*/
|
|
public final @NotNull T take() {
|
|
T t = getQueue().poll();
|
|
if(t==null) {
|
|
return create();
|
|
}
|
|
return t;
|
|
}
|
|
|
|
/**
|
|
* Returns an object back to the pool.
|
|
*/
|
|
public final void recycle(T t) {
|
|
getQueue().offer(t);
|
|
}
|
|
|
|
private ConcurrentLinkedQueue<T> getQueue() {
|
|
WeakReference<ConcurrentLinkedQueue<T>> q = queue;
|
|
if (q != null) {
|
|
ConcurrentLinkedQueue<T> d = q.get();
|
|
if (d != null) {
|
|
return d;
|
|
}
|
|
}
|
|
// overwrite the queue
|
|
ConcurrentLinkedQueue<T> d = new ConcurrentLinkedQueue<T>();
|
|
queue = new WeakReference<ConcurrentLinkedQueue<T>>(d);
|
|
|
|
return d;
|
|
}
|
|
|
|
/**
|
|
* Creates a new instance of object.
|
|
*
|
|
* <p>
|
|
* This method is used when someone wants to
|
|
* {@link #take() take} an object from an empty pool.
|
|
*
|
|
* <p>
|
|
* Also note that multiple threads may call this method
|
|
* concurrently.
|
|
*/
|
|
protected abstract @NotNull T create();
|
|
}
|
|
}
|