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Java > Open Source Codes > com > sun > enterprise > util > PoolBase


1 /*
2  * The contents of this file are subject to the terms
3  * of the Common Development and Distribution License
4  * (the License). You may not use this file except in
5  * compliance with the License.
6  *
7  * You can obtain a copy of the license at
8  * https://glassfish.dev.java.net/public/CDDLv1.0.html or
9  * glassfish/bootstrap/legal/CDDLv1.0.txt.
10  * See the License for the specific language governing
11  * permissions and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL
14  * Header Notice in each file and include the License file
15  * at glassfish/bootstrap/legal/CDDLv1.0.txt.
16  * If applicable, add the following below the CDDL Header,
17  * with the fields enclosed by brackets [] replaced by
18  * you own identifying information:
19  * "Portions Copyrighted [year] [name of copyright owner]"
20  *
21  * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
22  */
23 package com.sun.enterprise.util;
24
25 /**
26  * Based on Concurrent Programming in Java, Second Edition,
27  * by Doug Lea, page 222
28  *
29  */
30
31 public abstract class PoolBase implements Pool {
32
33     private final Semaphore available_;
34     private int numItems_;
35
36     protected PoolBase(int numItems) {
37         numItems_ = numItems;
38         available_ = new SemaphoreImpl(numItems);
39     }
40
41     public void initialize() throws Exception JavaDoc {
42         doInitializeItems(numItems_);
43     }
44     
45     public Object JavaDoc getItem() throws InterruptedException JavaDoc {
46         available_.acquire();
47         return doGet();
48     }
49  
50     public void returnItem(Object JavaDoc o) {
51         if( doReturn(o) ) {
52             available_.release();
53         }
54     }
55
56     protected abstract Object JavaDoc doGet();
57     protected abstract boolean doReturn(Object JavaDoc object);
58     protected abstract void doInitializeItems(int numItems) throws Exception JavaDoc;
59
60 }
61
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