Java example source code file (Atom.java)

This example Java source code file (Atom.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

aref, atom, atomicreference, iatom, ipersistentmap, iseq, object

The Atom.java Java example source code

/**
 *   Copyright (c) Rich Hickey. All rights reserved.
 *   The use and distribution terms for this software are covered by the
 *   Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
 *   which can be found in the file epl-v10.html at the root of this distribution.
 *   By using this software in any fashion, you are agreeing to be bound by
 * 	 the terms of this license.
 *   You must not remove this notice, or any other, from this software.
 **/

/* rich Jan 1, 2009 */

package clojure.lang;

import java.util.concurrent.atomic.AtomicReference;

final public class Atom extends ARef implements IAtom{
final AtomicReference state;

public Atom(Object state){
	this.state = new AtomicReference(state);
}

public Atom(Object state, IPersistentMap meta){
	super(meta);
	this.state = new AtomicReference(state);
}

public Object deref(){
	return state.get();
}

public Object swap(IFn f) {
	for(; ;)
		{
		Object v = deref();
		Object newv = f.invoke(v);
		validate(newv);
		if(state.compareAndSet(v, newv))
			{
			notifyWatches(v, newv);
			return newv;
			}
		}
}

public Object swap(IFn f, Object arg) {
	for(; ;)
		{
		Object v = deref();
		Object newv = f.invoke(v, arg);
		validate(newv);
		if(state.compareAndSet(v, newv))
			{
			notifyWatches(v, newv);
			return newv;
			}
		}
}

public Object swap(IFn f, Object arg1, Object arg2) {
	for(; ;)
		{
		Object v = deref();
		Object newv = f.invoke(v, arg1, arg2);
		validate(newv);
		if(state.compareAndSet(v, newv))
			{
			notifyWatches(v, newv);
			return newv;
			}
		}
}

public Object swap(IFn f, Object x, Object y, ISeq args) {
	for(; ;)
		{
		Object v = deref();
		Object newv = f.applyTo(RT.listStar(v, x, y, args));
		validate(newv);
		if(state.compareAndSet(v, newv))
			{
			notifyWatches(v, newv);
			return newv;
			}
		}
}

public boolean compareAndSet(Object oldv, Object newv){
	validate(newv);
	boolean ret = state.compareAndSet(oldv, newv);
	if(ret)
		notifyWatches(oldv, newv);
	return ret;
}

public Object reset(Object newval){
	Object oldval = state.get();
	validate(newval);
	state.set(newval);
	notifyWatches(oldval, newval);
	return newval;
}
}