jdk8-mips64-public/jaxws: src/share/jaxws_classes/com/sun/xml/internal/ws/util/Pool.java@9c07ef4934dd

     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  */

    26 package com.sun.xml.internal.ws.util;

    28 import com.sun.xml.internal.ws.api.pipe.Tube;

    29 import com.sun.xml.internal.ws.api.pipe.TubeCloner;

    31 import javax.xml.bind.JAXBContext;

    32 import javax.xml.bind.JAXBException;

    33 import java.util.concurrent.ConcurrentLinkedQueue;

    34 import java.lang.ref.WeakReference;

    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> {

    52     // volatile since multiple threads may access queue reference

    53     private volatile WeakReference<ConcurrentLinkedQueue<T>> queue;

    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     }

    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         }

    79         // overwrite the queue

    80         ConcurrentLinkedQueue<T> d = new ConcurrentLinkedQueue<T>();

    81         queue = new WeakReference<ConcurrentLinkedQueue<T>>(d);

    83         return d;

    84     }

    86     /**

    87      * Returns an object back to the pool.

    88      */

    89     public final void recycle(T t) {

    90         getQueue().offer(t);

    91     }

    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();

   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;

   113         public Marshaller(JAXBContext context) {

   114             this.context = context;

   115         }

   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     }

   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;

   134         public Unmarshaller(JAXBContext context) {

   135             this.context = context;

   136         }

   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     }

   149     /**

   150      * {@link Tube} pool.

   151      */

   152     public static final class TubePool extends Pool<Tube> {

   153         private final Tube master;

   155         public TubePool(Tube master) {

   156             this.master = master;

   157             recycle(master);    // we'll use master as a part of the pool, too.

   158         }

   160         @Override

   161         protected Tube create() {

   162             return TubeCloner.clone(master);

   163         }

   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         }

   176     }

   177 }

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