/*
* Copyright 1999-2004 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.frameworkset.commons.pool.impl;
import java.lang.ref.SoftReference;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import com.frameworkset.commons.pool.BaseObjectPool;
import com.frameworkset.commons.pool.ObjectPool;
import com.frameworkset.commons.pool.PoolableObjectFactory;
/**
* A {@link java.lang.ref.SoftReference SoftReference} based
* {@link ObjectPool}.
*
* @author Rodney Waldhoff
* @version $Revision: 383290 $ $Date: 2006-03-05 02:00:15 -0500 (Sun, 05 Mar 2006) $
*/
public class SoftReferenceObjectPool extends BaseObjectPool implements ObjectPool {
public SoftReferenceObjectPool() {
_pool = new ArrayList();
_factory = null;
}
public SoftReferenceObjectPool(PoolableObjectFactory factory) {
_pool = new ArrayList();
_factory = factory;
}
public SoftReferenceObjectPool(PoolableObjectFactory factory, int initSize) throws Exception {
_pool = new ArrayList();
_factory = factory;
if(null != _factory) {
for(int i=0;i<initSize;i++) {
Object obj = _factory.makeObject();
_factory.passivateObject(obj);
_pool.add(new SoftReference(obj));
}
}
}
public synchronized Object borrowObject() throws Exception {
assertOpen();
Object obj = null;
while(null == obj) {
if(_pool.isEmpty()) {
if(null == _factory) {
throw new NoSuchElementException();
} else {
obj = _factory.makeObject();
}
} else {
SoftReference ref = (SoftReference)(_pool.remove(_pool.size() - 1));
obj = ref.get();
}
if(null != _factory && null != obj) {
_factory.activateObject(obj);
}
if (null != _factory && null != obj && !_factory.validateObject(obj)) {
_factory.destroyObject(obj);
obj = null;
}
}
_numActive++;
return obj;
}
public synchronized void returnObject(Object obj) throws Exception {
assertOpen();
boolean success = true;
if(!(_factory.validateObject(obj))) {
success = false;
} else {
try {
_factory.passivateObject(obj);
} catch(Exception e) {
success = false;
}
}
boolean shouldDestroy = !success;
_numActive--;
if(success) {
_pool.add(new SoftReference(obj));
}
notifyAll(); // _numActive has changed
if(shouldDestroy) {
try {
_factory.destroyObject(obj);
} catch(Exception e) {
// ignored
}
}
}
public synchronized void invalidateObject(Object obj) throws Exception {
assertOpen();
_numActive--;
_factory.destroyObject(obj);
notifyAll(); // _numActive has changed
}
/**
* Create an object, and place it into the pool.
* addObject() is useful for "pre-loading" a pool with idle objects.
*/
public synchronized void addObject() throws Exception {
assertOpen();
Object obj = _factory.makeObject();
_numActive++; // A little slimy - must do this because returnObject decrements it.
returnObject(obj);
}
/** Returns an approximation not less than the of the number of idle instances in the pool. */
public synchronized int getNumIdle() {
assertOpen();
return _pool.size();
}
public synchronized int getNumActive() {
assertOpen();
return _numActive;
}
public synchronized void clear() {
assertOpen();
if(null != _factory) {
Iterator iter = _pool.iterator();
while(iter.hasNext()) {
try {
Object obj = ((SoftReference)iter.next()).get();
if(null != obj) {
_factory.destroyObject(obj);
}
} catch(Exception e) {
// ignore error, keep destroying the rest
}
}
}
_pool.clear();
}
public synchronized void close() throws Exception {
clear();
_pool = null;
_factory = null;
super.close();
}
public synchronized void setFactory(PoolableObjectFactory factory) throws IllegalStateException {
assertOpen();
if(0 < getNumActive()) {
throw new IllegalStateException("Objects are already active");
} else {
clear();
_factory = factory;
}
}
/** My pool. */
private List _pool = null;
/** My {@link PoolableObjectFactory}. */
private PoolableObjectFactory _factory = null;
/** Number of active objects. */
private int _numActive = 0;
}