com.bigdata.service.proxy.ThickFuture Maven / Gradle / Ivy
/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
[email protected]
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* Created on Jan 4, 2012
*/
package com.bigdata.service.proxy;
import java.io.Serializable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
* A thick {@link Future}. This is used to communicate the state of a
* {@link Future} to a remote client. The constructor blocks until the
* {@link Future} is done and then makes a record of the {@link Future}'s state.
* That state is serializable as the object returned by the {@link Future} is
* serializable.
*
* @author Bryan Thompson
* @version $Id$
*/
public class ThickFuture implements Future, Serializable {
/**
*
*/
private static final long serialVersionUID = 1L;
private final V outcome;
private final boolean cancelled;
private final ExecutionException cause;
/**
* Awaits the {@link Future} and then makes a serializable record of the
* {@link Future}'s state.
*/
public ThickFuture(final Future f) {
V outcome = null;
boolean cancelled = false;
ExecutionException cause = null;
try {
outcome = f.get();
} catch (InterruptedException e) {
cancelled = true;
} catch (ExecutionException e) {
cause = e;
}
this.outcome = outcome;
this.cancelled = cancelled;
this.cause = cause;
}
/**
* {@inheritDoc}
*
* The future can not be cancelled as it is already done.
*/
@Override
final public boolean cancel(boolean mayInterruptIfRunning) {
// Return [false] since the Future is already done.
return false;
}
@Override
final public boolean isCancelled() {
return cancelled;
}
/**
* {@inheritDoc}
*
* Always returns true.
*/
@Override
final public boolean isDone() {
// Always true.
return true;
}
/**
* {@inheritDoc}
*
* The {@link Future} is already done, so this method does not block.
*/
final public V get() throws InterruptedException, ExecutionException {
if (cancelled)
throw new InterruptedException();
if (cause != null)
throw cause;
return outcome;
}
/**
* {@inheritDoc}
*
* The {@link Future} is already done, so this method does not block.
*/
@Override
final public V get(long timeout, TimeUnit unit)
throws InterruptedException, ExecutionException, TimeoutException {
return get();
}
}