net.hasor.utils.future.BasicFuture Maven / Gradle / Ivy
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/*
* Copyright 2008-2009 the original author or authors.
*
* 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 net.hasor.utils.future;
import java.util.concurrent.*;
/**
* Basic implementation of the {@link Future} interface. BasicFuture
* can be put into a completed state by invoking any of the following methods:
* {@link #cancel()}, {@link #failed(Throwable)}, or {@link #completed(Object)}.
*
* @param the future result type of an asynchronous operation.
* @since 4.2
*/
public class BasicFuture implements Future, Cancellable {
private final FutureCallback callback;
private volatile boolean completed;
private volatile boolean cancelled;
private volatile T result;
private volatile Throwable ex;
public BasicFuture() {
super();
this.callback = null;
}
public BasicFuture(T value) {
this();
this.completed = true;
this.result = value;
}
public BasicFuture(final FutureCallback callback) {
super();
this.callback = callback;
}
public boolean isCancelled() {
return this.cancelled;
}
public boolean isDone() {
return this.completed;
}
private T getResult() throws ExecutionException {
if (this.ex != null) {
throw new ExecutionException(this.ex.getMessage(), this.ex);
}
return this.result;
}
public synchronized T get() throws InterruptedException, ExecutionException {
while (!this.completed) {
wait();
}
return getResult();
}
public synchronized T get(final long timeout, final TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException {
if (unit == null) {
throw new NullPointerException("Time unit");
}
final long msecs = unit.toMillis(timeout);
final long startTime = (msecs <= 0) ? 0 : System.currentTimeMillis();
long waitTime = msecs;
if (this.completed) {
return getResult();
} else if (waitTime <= 0) {
throw new TimeoutException();
} else {
for (; ; ) {
wait(waitTime);
if (this.completed) {
return getResult();
} else {
waitTime = msecs - (System.currentTimeMillis() - startTime);
if (waitTime <= 0) {
throw new TimeoutException();
}
}
}
}
}
public boolean completed(final T result) {
synchronized (this) {
if (this.completed) {
return false;
}
this.completed = true;
this.result = result;
notifyAll();
}
if (this.callback != null) {
this.callback.completed(result);
}
return true;
}
public boolean failed(final Throwable exception) {
synchronized (this) {
if (this.completed) {
return false;
}
this.completed = true;
this.ex = exception;
notifyAll();
}
if (this.callback != null) {
this.callback.failed(exception);
}
return true;
}
public boolean cancel(final boolean mayInterruptIfRunning) {
synchronized (this) {
if (this.completed) {
return false;
}
this.completed = true;
this.cancelled = true;
notifyAll();
}
if (this.callback != null) {
if (this.callback instanceof CancellFutureCallback) {
((CancellFutureCallback) this.callback).cancelled();
} else {
this.failed(new CancellationException());
}
}
return true;
}
public boolean cancel() {
return cancel(true);
}
}