FutureGetDelegate.java

/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2012, Red Hat, Inc., and individual contributors
 * as indicated by the @author tags. See the copyright.txt file 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.capedwarf.common.threads;

import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicBoolean;

/**
 * @author <a href="mailto:ales.justin@jboss.org">Ales Justin</a>
 */
public abstract class FutureGetDelegate<T> implements Future<T> {
    private final AtomicBoolean invoked = new AtomicBoolean(false);
    private final Future<T> delegate;

    public FutureGetDelegate(Future<T> delegate) {
        this.delegate = delegate;
    }

    public boolean cancel(boolean mayInterruptIfRunning) {
        return delegate.cancel(mayInterruptIfRunning);
    }

    public boolean isCancelled() {
        return delegate.isCancelled();
    }

    public boolean isDone() {
        return delegate.isDone();
    }

    protected abstract void before();

    protected abstract void after(T result);

    public T get() throws InterruptedException, ExecutionException {
        boolean previous = invoked.getAndSet(true);
        if (previous == false) {
            before();
        }
        final T result = delegate.get();
        if (previous == false) {
            after(result);
        }
        return result;
    }

    public T get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException {
        boolean previous = invoked.getAndSet(true);
        if (previous == false) {
            before();
        }
        final T result = delegate.get(timeout, unit);
        if (previous == false) {
            after(result);
        }
        return result;
    }
}