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/*
* ====================================================================
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
*/
package ch.boye.httpclientandroidlib.concurrent;
import ch.boye.httpclientandroidlib.util.Args;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
* Basic implementation of the {@link Future} interface. <tt>BasicFuture<tt>
* can be put into a completed state by invoking any of the following methods:
* {@link #cancel()}, {@link #failed(Exception)}, or {@link #completed(Object)}.
*
* @param <T> the future result type of an asynchronous operation.
* @since 4.2
*/
public class BasicFuture<T> implements Future<T>, Cancellable {
private final FutureCallback<T> callback;
private volatile boolean completed;
private volatile boolean cancelled;
private volatile T result;
private volatile Exception ex;
public BasicFuture(final FutureCallback<T> 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);
}
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 {
Args.notNull(unit, "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 Exception 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) {
this.callback.cancelled();
}
return true;
}
public boolean cancel() {
return cancel(true);
}
}
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