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RePlay is a fork of the Play1 framework, created by Codeborne.

There is a newer version: 2.6.2

package play.libs;

import java.util.concurrent.*;
import java.util.function.Consumer;

public class Promise implements Future, Consumer {

    private final CountDownLatch taskLock = new CountDownLatch(1);

    @Override
    public boolean cancel(boolean mayInterruptIfRunning) {
        return false;
    }

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

    @Override
    public boolean isDone() {
        return invoked;
    }

    @Override
    public V get() throws InterruptedException, ExecutionException {
        taskLock.await();
        if (exception != null) {
            throw new ExecutionException(exception);
        }
        return result;
    }

    @Override
    public V get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException {
        if(!taskLock.await(timeout, unit)) {
          throw new TimeoutException(String.format("Promise didn't redeem in %s %s", timeout, unit));
        }

        if (exception != null) {
            throw new ExecutionException(exception);
        }
        return result;
    }
    protected boolean invoked;
    protected V result;
    protected Throwable exception;

    @Override
    public void accept(V result) {
        invokeWithResultOrException(result, null);
    }

    public void invokeWithException(Throwable t) {
        invokeWithResultOrException(null, t);
    }

    protected void invokeWithResultOrException(V result, Throwable t) {
        synchronized (this) {
            if (!invoked) {
                invoked = true;
                this.result = result;
                this.exception = t;
                taskLock.countDown();
            }
        }
    }
}