1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/jaxws_classes/com/sun/istack/internal/Pool.java Tue Mar 06 16:09:35 2012 -0800
1.3 @@ -0,0 +1,116 @@
1.4 +/*
1.5 + * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation. Oracle designates this
1.11 + * particular file as subject to the "Classpath" exception as provided
1.12 + * by Oracle in the LICENSE file that accompanied this code.
1.13 + *
1.14 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.15 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.16 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.17 + * version 2 for more details (a copy is included in the LICENSE file that
1.18 + * accompanied this code).
1.19 + *
1.20 + * You should have received a copy of the GNU General Public License version
1.21 + * 2 along with this work; if not, write to the Free Software Foundation,
1.22 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.23 + *
1.24 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.25 + * or visit www.oracle.com if you need additional information or have any
1.26 + * questions.
1.27 + */
1.28 +
1.29 +package com.sun.istack.internal;
1.30 +
1.31 +import java.util.concurrent.ConcurrentLinkedQueue;
1.32 +import java.lang.ref.WeakReference;
1.33 +
1.34 +/**
1.35 + * Pool of reusable objects that are indistinguishable from each other,
1.36 + * such as JAXB marshallers.
1.37 + *
1.38 + * @author Kohsuke Kawaguchi
1.39 + */
1.40 +public interface Pool<T> {
1.41 +
1.42 + /**
1.43 + * Gets a new object from the pool.
1.44 + *
1.45 + * <p>
1.46 + * If no object is available in the pool, this method creates a new one.
1.47 + */
1.48 + @NotNull T take();
1.49 +
1.50 + /**
1.51 + * Returns an object back to the pool.
1.52 + */
1.53 + void recycle(@NotNull T t);
1.54 +
1.55 + /**
1.56 + * Default implementation that uses {@link ConcurrentLinkedQueue}
1.57 + * as the data store.
1.58 + *
1.59 + * <h2>Note for Implementors</h2>
1.60 + * <p>
1.61 + * Don't rely on the fact that this class extends from {@link ConcurrentLinkedQueue}.
1.62 + */
1.63 + public abstract class Impl<T> implements Pool<T> {
1.64 +
1.65 + private volatile WeakReference<ConcurrentLinkedQueue<T>> queue;
1.66 +
1.67 + /**
1.68 + * Gets a new object from the pool.
1.69 + *
1.70 + * <p>
1.71 + * If no object is available in the pool, this method creates a new one.
1.72 + *
1.73 + * @return
1.74 + * always non-null.
1.75 + */
1.76 + public final @NotNull T take() {
1.77 + T t = getQueue().poll();
1.78 + if(t==null) {
1.79 + return create();
1.80 + }
1.81 + return t;
1.82 + }
1.83 +
1.84 + /**
1.85 + * Returns an object back to the pool.
1.86 + */
1.87 + public final void recycle(T t) {
1.88 + getQueue().offer(t);
1.89 + }
1.90 +
1.91 + private ConcurrentLinkedQueue<T> getQueue() {
1.92 + WeakReference<ConcurrentLinkedQueue<T>> q = queue;
1.93 + if (q != null) {
1.94 + ConcurrentLinkedQueue<T> d = q.get();
1.95 + if (d != null) {
1.96 + return d;
1.97 + }
1.98 + }
1.99 + // overwrite the queue
1.100 + ConcurrentLinkedQueue<T> d = new ConcurrentLinkedQueue<T>();
1.101 + queue = new WeakReference<ConcurrentLinkedQueue<T>>(d);
1.102 +
1.103 + return d;
1.104 + }
1.105 +
1.106 + /**
1.107 + * Creates a new instance of object.
1.108 + *
1.109 + * <p>
1.110 + * This method is used when someone wants to
1.111 + * {@link #take() take} an object from an empty pool.
1.112 + *
1.113 + * <p>
1.114 + * Also note that multiple threads may call this method
1.115 + * concurrently.
1.116 + */
1.117 + protected abstract @NotNull T create();
1.118 + }
1.119 +}
