FutureImpl.java

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package com.sun.grizzly.util;

import java.util.concurrent.CancellationException;
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<R> implements Future<R> {

    private final Object sync;

    private boolean isDone;

    private boolean isCancelled;
    private Throwable failure;

    protected R result;

    public FutureImpl() {
        this(new Object());
    }

    public FutureImpl(Object sync) {
        this.sync = sync;
    }

    public R getResult() {
        synchronized(sync) {
            return result;
        }
    }

    public void setResult(R result) {
        synchronized(sync) {
            this.result = result;
            notifyHaveResult();
        }
    }

    public boolean cancel(boolean mayInterruptIfRunning) {
        synchronized(sync) {
            isCancelled = true;
            notifyHaveResult();
            return true;
        }
    }

    public boolean isCancelled() {
        synchronized(sync) {
            return isCancelled;
        }
    }

    public boolean isDone() {
        synchronized(sync) {
            return isDone;
        }
    }

    public R get() throws InterruptedException, ExecutionException {
        synchronized (sync) {
            for (;;) {
                if (isDone) {
                    if (isCancelled) {
                        throw new CancellationException();
                    } else if (failure != null) {
                        throw new ExecutionException(failure);
                    } else if (result != null) {
                        return result;
                    }
                }

                sync.wait();
            }
        }
    }

    public R get(long timeout, TimeUnit unit) throws
            InterruptedException, ExecutionException, TimeoutException {
        long startTime = System.currentTimeMillis();
        long timeoutMillis = TimeUnit.MILLISECONDS.convert(timeout, unit);
        synchronized (sync) {
            for (;;) {
                if (isDone) {
                    if (isCancelled) {
                        throw new CancellationException();
                    } else if (failure != null) {
                        throw new ExecutionException(failure);
                    } else if (result != null) {
                        return result;
                    }
                } else if (System.currentTimeMillis() - startTime > timeoutMillis) {
                    throw new TimeoutException();
                }

                sync.wait(timeoutMillis);
            }
        }
    }

    public void setException(Throwable failure) {
        synchronized(sync) {
            this.failure = failure;
            notifyHaveResult();
        }
    }

    protected void notifyHaveResult() {
        isDone = true;
        sync.notifyAll();
    }
}