/*
* Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
*
* This software is open source.
* See the bottom of this file for the licence.
*/
package org.dom4j.util;
import java.lang.ref.WeakReference;
/**
* <p>
* <code>PerThreadSingleton</code> is an implementation of the
* SingletonStrategy used to provide common factory access to a single object
* instance based on an implementation strategy for one object instance per
* thread. This is useful in replace of the ThreadLocal usage.
* </p>
*
* @author <a href="mailto:ddlucas@users.sourceforge.net">David Lucas </a>
* @version $Revision: 1.3 $
*/
public class PerThreadSingleton implements SingletonStrategy {
private String singletonClassName = null;
private ThreadLocal perThreadCache = new ThreadLocal();
public PerThreadSingleton() {
}
public void reset() {
perThreadCache = new ThreadLocal();
}
public Object instance() {
Object singletonInstancePerThread = null;
// use weak reference to prevent cyclic reference during GC
WeakReference ref = (WeakReference) perThreadCache.get();
// singletonInstancePerThread=perThreadCache.get();
// if (singletonInstancePerThread==null) {
if (ref == null || ref.get() == null) {
Class clazz = null;
try {
clazz = Thread.currentThread().getContextClassLoader().loadClass(
singletonClassName);
singletonInstancePerThread = clazz.newInstance();
} catch (Exception ignore) {
try {
clazz = Class.forName(singletonClassName);
singletonInstancePerThread = clazz.newInstance();
} catch (Exception ignore2) {
}
}
perThreadCache.set(new WeakReference(singletonInstancePerThread));
} else {
singletonInstancePerThread = ref.get();
}
return singletonInstancePerThread;
}
public void setSingletonClassName(String singletonClassName) {
this.singletonClassName = singletonClassName;
}
}
/*
* Redistribution and use of this software and associated documentation
* ("Software"), with or without modification, are permitted provided that the
* following conditions are met:
*
* 1. Redistributions of source code must retain copyright statements and
* notices. Redistributions must also contain a copy of this document.
*
* 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 name "DOM4J" must not be used to endorse or promote products derived
* from this Software without prior written permission of MetaStuff, Ltd. For
* written permission, please contact dom4j-info@metastuff.com.
*
* 4. Products derived from this Software may not be called "DOM4J" nor may
* "DOM4J" appear in their names without prior written permission of MetaStuff,
* Ltd. DOM4J is a registered trademark of MetaStuff, Ltd.
*
* 5. Due credit should be given to the DOM4J Project - http://dom4j.sourceforge.net
*
* THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS ``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 METASTUFF, LTD. 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.
*
* Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
*/