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/*
* Filename: AbstractPool.java
*
* Copyright 2000-2001 by iPlanet/Sun Microsystems, Inc.,
* 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
* All rights reserved.
*
* This software is the confidential and proprietary information
* of iPlanet/Sun Microsystems, Inc. ("Confidential Information").
* You shall not disclose such Confidential Information and shall
* use it only in accordance with the terms of the license
* agreement you entered into with iPlanet/Sun Microsystems.
*/
/**
* <BR> <I>$Source: /cvs/glassfish/appserv-commons/src/java/com/sun/enterprise/util/pool/ArrayListPool.java,v $</I>
* @author $Author: tcfujii $
* @version $Revision: 1.4 $ $Date: 2007/05/05 05:32:16 $
*/
package com.sun.enterprise.util.pool;
import java.util.Collection;
import java.util.ArrayList;
/**
* <p>Abstract pool provides the basic implementation of an object pool. The implementation
* uses a linked list to maintain a collection of (available) objects. If the pool is
* empty it simply creates one using the ObjectFactory instance. Subclasses can change
* this behaviour by overriding getObject(...) and returnObject(....) methods. This
* class provides basic support for synchronization, event notification, pool shutdown
* and pool object recycling. It also does some very basic bookkeeping like the
* number of objects created, number of threads waiting for object.
* <p> Subclasses can make use of these book-keeping data to provide complex pooling
* mechanism like LRU / MRU / Random. Also, note that AbstractPool does not have a
* notion of pool limit. It is upto to the derived classes to implement these features.
* <p>This class does not define the canCreate() method.
*/
public abstract class ArrayListPool
extends AbstractPool
{
protected ArrayList arrayList;
protected ArrayListPool(ObjectFactory factory) {
super.factory = factory;
super.collection = this.arrayList = new ArrayList(6);
}
protected ArrayListPool(ObjectFactory factory, int initialCapacity) {
super.factory = factory;
super.collection = this.arrayList = new ArrayList(initialCapacity);
}
/**
* Notification when an object is put back into the pool (checkin).
* @param The object to be returned back to the pool.
* @return Any non null value can be returned to signal that the object
* was indeed added to the pool. This class always adds the object to the
* pool (at the end of the collection), it returns non-null value.
* Subclasses can override this behaviour.
*/
protected Object checkin(Object object) {
collection.add(object);
return this;
}
/**
* Notification when an object is given out from the pool (checout).
* @return The object that has to be returned to the application. A null
* value must be returned if no object can be returned to the application. Since this
* class always returns the last node from the collection, it returns non-null value.
* Subclasses can override this behaviour.
*/
protected Object checkout() {
return arrayList.remove(arrayList.size() - 1);
}
/**
* Notification when an object is given out from the pool (checout).
* @return The object that has to be returned to the application. A null
* value must be returned if no object can be returned to the application. Since this
* class always returns the last node from the collection, it returns non-null value.
* Subclasses can override this behaviour.
*/
protected Object checkout(long param) {
return arrayList.remove(arrayList.size() - 1);
}
/**
* Notification when an object is given out from the pool (checout).
* @return The object that has to be returned to the application. A null
* value must be returned if no object can be returned to the application. Since this
* class always returns the last node from the collection, it returns non-null value.
* Subclasses can override this behaviour.
*/
protected Object checkout(Object param) {
return arrayList.remove(arrayList.size() - 1);
}
} |
