/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
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 * and Distribution License("CDDL") (collectively, the "License").  You
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 * or glassfish/bootstrap/legal/LICENSE.txt.  See the License for the specific
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 * 
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
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 * as provided by Sun in the GPL Version 2 section of the License file that
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 * Header, with the fields enclosed by brackets [] replaced by your own
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 * If you wish your version of this file to be governed by only the CDDL or
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package com.sun.enterprise.util;

/**
 * Based on Concurrent Programming in Java, Second Edition,
 * by Doug Lea, page 222
 *
 */

public abstract class PoolBase implements Pool {

    private final Semaphore available_;
    private int numItems_;

    protected PoolBase(int numItems) {
        numItems_  = numItems;
        available_ = new SemaphoreImpl(numItems);
    }

    public void initialize() throws Exception {
        doInitializeItems(numItems_);
    }
    
    public Object getItem() throws InterruptedException {
        available_.acquire();
        return doGet();
    }
 
    public void returnItem(Object o) {
        if( doReturn(o) ) {
            available_.release();
        }
    }

    protected abstract Object doGet();
    protected abstract boolean doReturn(Object object);
    protected abstract void doInitializeItems(int numItems) throws Exception;

}