1 /* 2 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package com.sun.xml.internal.ws.util; 27 28 import com.sun.xml.internal.ws.api.pipe.Tube; 29 import com.sun.xml.internal.ws.api.pipe.TubeCloner; 30 31 import javax.xml.bind.JAXBContext; 32 import javax.xml.bind.JAXBException; 33 import java.util.concurrent.ConcurrentLinkedQueue; 34 import java.lang.ref.WeakReference; 35 36 /** 37 * General-purpose object pool. 38 * 39 * <p> 40 * In many parts of the runtime, we need to pool instances of objects that 41 * are expensive to create (such as JAXB objects, StAX parsers, {@link Tube} instances.) 42 * 43 * <p> 44 * This class provides a default implementation of such a pool. 45 * 46 * TODO: improve the implementation 47 * 48 * @author Kohsuke Kawaguchi 49 */ 50 public abstract class Pool<T> { 51 52 // volatile since multiple threads may access queue reference 53 private volatile WeakReference<ConcurrentLinkedQueue<T>> queue; 54 55 /** 56 * Gets a new object from the pool. 57 * 58 * <p> 59 * If no object is available in the pool, this method creates a new one. 60 * 61 * @return 62 * always non-null. 63 */ 64 public final T take() { 65 T t = getQueue().poll(); 66 if(t==null) 67 return create(); 68 return t; 69 } 70 71 private ConcurrentLinkedQueue<T> getQueue() { 72 WeakReference<ConcurrentLinkedQueue<T>> q = queue; 73 if (q != null) { 74 ConcurrentLinkedQueue<T> d = q.get(); 75 if (d != null) 76 return d; 77 } 78 79 // overwrite the queue 80 ConcurrentLinkedQueue<T> d = new ConcurrentLinkedQueue<T>(); 81 queue = new WeakReference<ConcurrentLinkedQueue<T>>(d); 82 83 return d; 84 } 85 86 /** 87 * Returns an object back to the pool. 88 */ 89 public final void recycle(T t) { 90 getQueue().offer(t); 91 } 92 93 /** 94 * Creates a new instance of object. 95 * 96 * <p> 97 * This method is used when someone wants to 98 * {@link #take() take} an object from an empty pool. 99 * 100 * <p> 101 * Also note that multiple threads may call this method 102 * concurrently. 103 */ 104 protected abstract T create(); 105 106 107 /** 108 * JAXB {@link javax.xml.bind.Marshaller} pool. 109 */ 110 public static final class Marshaller extends Pool<javax.xml.bind.Marshaller> { 111 private final JAXBContext context; 112 113 public Marshaller(JAXBContext context) { 114 this.context = context; 115 } 116 117 @Override 118 protected javax.xml.bind.Marshaller create() { 119 try { 120 return context.createMarshaller(); 121 } catch (JAXBException e) { 122 // impossible 123 throw new AssertionError(e); 124 } 125 } 126 } 127 128 /** 129 * JAXB {@link javax.xml.bind.Marshaller} pool. 130 */ 131 public static final class Unmarshaller extends Pool<javax.xml.bind.Unmarshaller> { 132 private final JAXBContext context; 133 134 public Unmarshaller(JAXBContext context) { 135 this.context = context; 136 } 137 138 @Override 139 protected javax.xml.bind.Unmarshaller create() { 140 try { 141 return context.createUnmarshaller(); 142 } catch (JAXBException e) { 143 // impossible 144 throw new AssertionError(e); 145 } 146 } 147 } 148 149 /** 150 * {@link Tube} pool. 151 */ 152 public static final class TubePool extends Pool<Tube> { 153 private final Tube master; 154 155 public TubePool(Tube master) { 156 this.master = master; 157 recycle(master); // we'll use master as a part of the pool, too. 158 } 159 160 @Override 161 protected Tube create() { 162 return TubeCloner.clone(master); 163 } 164 165 /** 166 * 167 * @return master tubeline from pool 168 * @deprecated Expected to be used in rare cases where access to master 169 * tubeline is required and safe, such as Stub.close()." 170 */ 171 @Deprecated() 172 public final Tube takeMaster() { 173 return master; 174 } 175 176 } 177 }