BasicFuture.java

/*
 * Copyright 2014 Avanza Bank AB
 *
 * 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.avanza.astrix.beans.core;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

public final class BasicFuture<T> implements Future<T> {

	private final CountDownLatch done = new CountDownLatch(1);
	private volatile T result;
	
	public BasicFuture(T result) {
		this.result = result;
		this.done.countDown();
	}
	
	public BasicFuture() {
	}
	
	public void set(T result) {
		synchronized (done) {
			if (isDone()) {
				throw new IllegalStateException("Future already set");
			}
			this.result = result;
			done.countDown();
		}
	}
	
	@Override
	public boolean cancel(boolean mayInterruptIfRunning) {
		return false;
	}

	@Override
	public boolean isCancelled() {
		return false;
	}

	@Override
	public boolean isDone() {
		return done.getCount() == 0;
	}

	@Override
	public T get() throws InterruptedException, ExecutionException {
		done.await();
		return result;
	}

	@Override
	public T get(long timeout, TimeUnit unit)
			throws InterruptedException, ExecutionException,
			TimeoutException {
		done.await(timeout, unit);
		return result;
	}
}