| /* |
| * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//pool/src/java/org/apache/commons/pool/impl/StackObjectPool.java,v 1.1 2001/04/14 16:41:56 rwaldhoff Exp $ |
| * $Revision: 1.1 $ |
| * $Date: 2001/04/14 16:41:56 $ |
| * |
| * ==================================================================== |
| * |
| * The Apache Software License, Version 1.1 |
| * |
| * Copyright (c) 1999-2001 The Apache Software Foundation. All rights |
| * reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in |
| * the documentation and/or other materials provided with the |
| * distribution. |
| * |
| * 3. The end-user documentation included with the redistribution, if |
| * any, must include the following acknowlegement: |
| * "This product includes software developed by the |
| * Apache Software Foundation (http://www.apache.org/)." |
| * Alternately, this acknowlegement may appear in the software itself, |
| * if and wherever such third-party acknowlegements normally appear. |
| * |
| * 4. The names "The Jakarta Project", "Commons", and "Apache Software |
| * Foundation" must not be used to endorse or promote products derived |
| * from this software without prior written permission. For written |
| * permission, please contact apache@apache.org. |
| * |
| * 5. Products derived from this software may not be called "Apache" |
| * nor may "Apache" appear in their names without prior written |
| * permission of the Apache Group. |
| * |
| * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED |
| * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
| * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR |
| * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
| * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
| * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| * ==================================================================== |
| * |
| * This software consists of voluntary contributions made by many |
| * individuals on behalf of the Apache Software Foundation. For more |
| * information on the Apache Software Foundation, please see |
| * <http://www.apache.org/>. |
| * |
| */ |
| |
| package org.apache.commons.pool.impl; |
| |
| import org.apache.commons.pool.*; |
| import java.util.Stack; |
| import java.util.NoSuchElementException; |
| import java.util.Enumeration; |
| |
| /** |
| * A simple, {@link java.util.Stack Stack}-based {@link ObjectPool} implementation. |
| * <p> |
| * Given a {@link PoolableObjectFactory}, this class will maintain |
| * a simple pool of instances. A finite number of "sleeping" |
| * or idle instances is enforced, but when the pool is |
| * empty, new instances are created to support the new load. |
| * Hence this class places no limit on the number of "active" |
| * instances created by the pool, but is quite useful for |
| * re-using <tt>Object</tt>s without introducing |
| * artificial limits. |
| * |
| * @author Rodney Waldhoff |
| * @version $Id: StackObjectPool.java,v 1.1 2001/04/14 16:41:56 rwaldhoff Exp $ |
| */ |
| public class StackObjectPool implements ObjectPool { |
| /** |
| * Create a new pool using |
| * no factory. Clients must first populate the pool |
| * using {@link #returnObject(java.lang.Object)} |
| * before they can be {@link #borrowObject borrowed}. |
| */ |
| public StackObjectPool() { |
| this((PoolableObjectFactory)null,DEFAULT_MAX_SLEEPING,DEFAULT_INIT_SLEEPING_CAPACITY); |
| } |
| |
| /** |
| * Create a new pool using |
| * no factory. Clients must first populate the pool |
| * using {@link #returnObject(java.lang.Object)} |
| * before they can be {@link #borrowObject borrowed}. |
| */ |
| public StackObjectPool(int max) { |
| this((PoolableObjectFactory)null,max,DEFAULT_INIT_SLEEPING_CAPACITY); |
| } |
| |
| /** |
| * Create a new pool using |
| * no factory. Clients must first populate the pool |
| * using {@link #returnObject(java.lang.Object)} |
| * before they can be {@link #borrowObject borrowed}. |
| */ |
| public StackObjectPool(int max, int init) { |
| this((PoolableObjectFactory)null,max,init); |
| } |
| |
| /** |
| * Create a new <tt>StackObjectPool</tt> using |
| * the specified <i>factory</i> to create new instances. |
| * |
| * @param factory the {@link PoolableObjectFactory} used to populate the pool |
| */ |
| public StackObjectPool(PoolableObjectFactory factory) { |
| this(factory,DEFAULT_MAX_SLEEPING,DEFAULT_INIT_SLEEPING_CAPACITY); |
| } |
| |
| /** |
| * Create a new <tt>SimpleObjectPool</tt> using |
| * the specified <i>factory</i> to create new instances, |
| * capping the number of "sleeping" instances to <i>max</i> |
| * |
| * @param factory the {@link PoolableObjectFactory} used to populate the pool |
| * @param max cap on the number of "sleeping" instances in the pool |
| */ |
| public StackObjectPool(PoolableObjectFactory factory, int max) { |
| this(factory,max,DEFAULT_INIT_SLEEPING_CAPACITY); |
| } |
| |
| /** |
| * Create a new <tt>SimpleObjectPool</tt> using |
| * the specified <i>factory</i> to create new instances, |
| * capping the number of "sleeping" instances to <i>max</i>, |
| * and initially allocating a container capable of containing |
| * at least <i>init</i> instances. |
| * |
| * @param factory the {@link PoolableObjectFactory} used to populate the pool |
| * @param max cap on the number of "sleeping" instances in the pool |
| * @param init initial size of the pool (this specifies the size of the container, |
| * it does not cause the pool to be pre-populated.) |
| */ |
| public StackObjectPool(PoolableObjectFactory factory, int max, int init) { |
| _factory = factory; |
| _maxSleeping = (max < 0 ? DEFAULT_MAX_SLEEPING : max); |
| int initcapacity = (init < 1 ? DEFAULT_INIT_SLEEPING_CAPACITY : init); |
| _pool = new Stack(); |
| _pool.ensureCapacity( initcapacity > _maxSleeping ? _maxSleeping : initcapacity); |
| } |
| |
| public synchronized Object borrowObject() { |
| Object obj = null; |
| try { |
| obj = _pool.pop(); |
| } catch(Exception e) { |
| if(null == _factory) { |
| throw new NoSuchElementException(); |
| } else { |
| obj = _factory.makeObject(); |
| } |
| } |
| if(null != _factory && null != obj) { |
| _factory.activateObject(obj); |
| } |
| _numActive++; |
| return obj; |
| } |
| |
| public synchronized void returnObject(Object obj) { |
| _numActive--; |
| if(null == _factory || _factory.validateObject(obj)) { |
| if(null != _factory) { |
| try { |
| _factory.passivateObject(obj); |
| } catch(Exception e) { |
| _factory.destroyObject(obj); |
| return; |
| } |
| } |
| if(_pool.size() < _maxSleeping) { |
| _pool.push(obj); |
| } else { |
| if(null != _factory) { |
| _factory.destroyObject(obj); |
| } |
| } |
| } else { |
| if(null != _factory) { |
| _factory.destroyObject(obj); |
| } |
| } |
| } |
| |
| public int numIdle() { |
| return _pool.size(); |
| } |
| |
| public int numActive() { |
| return _numActive; |
| } |
| |
| public synchronized void clear() throws UnsupportedOperationException { |
| if(null != _factory) { |
| Enumeration enum = _pool.elements(); |
| while(enum.hasMoreElements()) { |
| _factory.destroyObject(enum.nextElement()); |
| } |
| } |
| _pool.clear(); |
| } |
| |
| synchronized public void close() { |
| clear(); |
| _pool = null; |
| _factory = null; |
| } |
| |
| synchronized public void setFactory(PoolableObjectFactory factory) throws IllegalStateException, UnsupportedOperationException { |
| if(0 < numActive()) { |
| throw new IllegalStateException("Objects are already active"); |
| } else { |
| clear(); |
| _factory = factory; |
| } |
| } |
| |
| /** The default cap on the number of "sleeping" instances in the pool. */ |
| protected static final int DEFAULT_MAX_SLEEPING = 8; |
| |
| /** |
| * The default initial size of the pool |
| * (this specifies the size of the container, it does not |
| * cause the pool to be pre-populated.) |
| */ |
| protected static final int DEFAULT_INIT_SLEEPING_CAPACITY = 4; |
| |
| /** My pool. */ |
| protected Stack _pool = null; |
| |
| /** My {@link PoolableObjectFactory}. */ |
| protected PoolableObjectFactory _factory = null; |
| |
| /** The cap on the number of "sleeping" instances in the pool. */ |
| protected int _maxSleeping = DEFAULT_MAX_SLEEPING; |
| |
| protected int _numActive = 0; |
| } |
