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package com.sun.grizzly.util;

import java.util.concurrent.CancellationException;
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;

/**
 * Default {@link Future} implementation
 *
 * @author Alexey Stashok
 */
public class FutureImpl implements Future {
    private CountDownLatch latch = new CountDownLatch(1);
    private E result;
    private boolean isCancelled;
    private Throwable exception;

    public boolean cancel(boolean mayInterruptIfRunning) {
        if (isDone()) return false;

        isCancelled = true;
        notifyResult();

        return true;
    }

    public boolean isCancelled() {
        return isCancelled;
    }

    public boolean isDone() {
        return latch.getCount() < 1;
    }

    public E get() throws InterruptedException, ExecutionException {
        latch.await();
        if (isCancelled) {
            throw new CancellationException();
        } else if (exception != null) {
            throw new ExecutionException(exception);
        }

        return result;
    }

    public E get(long timeout, TimeUnit unit) throws InterruptedException,
            ExecutionException, TimeoutException {
        latch.await(timeout, unit);
        if (isCancelled) {
            throw new CancellationException();
        } else if (exception != null) {
            throw new ExecutionException(exception);
        }

        return result;
    }

    public E getResult() {
        return result;
    }

    public void setResult(E result) {
        this.result = result;
        notifyResult();
    }

    public Throwable getException() {
        return exception;
    }

    public void setException(Throwable exception) {
        this.exception = exception;
        notifyResult();
    }

    protected void notifyResult() {
        latch.countDown();
    }
}