/*
* JBoss, Home of Professional Open Source
* Copyright 2010, Red Hat Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.as.ee.component;
import java.util.concurrent.ExecutionException;
/**
* A lazy value that is computed on demand.
*
* @author Stuart Douglas
*/
public abstract class LazyValue<T> {
private volatile T value = null;
private volatile boolean run = false;
public T get() throws InterruptedException, ExecutionException {
if (!run) {
synchronized (this) {
if (!run) {
value = compute();
run = true;
}
}
}
return value;
}
protected abstract T compute();
}