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/*******************************************************************************
* Copyright (c) 2014 Wind River Systems, Inc. and others. All rights reserved.
* This program and the accompanying materials are made available under the terms
* of the Eclipse Public License v1.0 which accompanies this distribution, and is
* available at http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Wind River Systems - initial API and implementation
*******************************************************************************/
package org.eclipse.tcf.debug.test.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;
import org.eclipse.tcf.protocol.Protocol;
/**
* Copied and adapted from org.eclipse.cdt.dsf.concurrent.
*
* A convenience class that allows a client to retrieve data from services
* synchronously from a non-dispatch thread. This class is different from
* a Callable<V> in that it allows the implementation code to calculate
* the result in several dispatches, rather than requiring it to return the
* data at end of Callable#call method.
* <p>
* Usage:<br/>
* <pre>
* class DataQuery extends Query<Data> {
* protected void execute(DataCallback<Data> callback) {
* callback.setData(fSlowService.getData());
* callback.done();
* }
* }
*
* DsfExecutor executor = getExecutor();
* DataQuery query = new DataQuery();
* executor.submit(query);
*
* try {
* Data data = query.get();
* }
*
* </pre>
* <p>
* @see java.util.concurrent.Callable
*
*/
abstract public class Query<V> implements Future<V>
{
private class QueryCallback extends DataCallback<V> {
boolean fExecuted = false;
boolean fCompleted = false;
private QueryCallback() {
super(null);
}
@Override
public synchronized void handleCompleted() {
fCompleted = true;
notifyAll();
}
public synchronized boolean isCompleted() {
return fCompleted;
}
public synchronized boolean setExecuted() {
if (fExecuted || isCanceled()) {
// already executed or canceled
return false;
}
fExecuted = true;
return true;
}
};
private final QueryCallback fCallback = new QueryCallback();
/**
* The no-argument constructor
*/
public Query() {}
public V get() throws InterruptedException, ExecutionException {
invoke();
Throwable error;
V data;
synchronized (fCallback) {
while (!isDone()) {
fCallback.wait();
}
error = fCallback.getError();
data = fCallback.getData();
}
if (error instanceof CancellationException) {
throw new CancellationException();
} else if (error != null) {
throw new ExecutionException(error);
}
return data;
}
public V get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException {
invoke();
long timeLeft = unit.toMillis(timeout);
long timeoutTime = System.currentTimeMillis() + unit.toMillis(timeout);
Throwable error;
V data;
synchronized (fCallback) {
while (!isDone()) {
if (timeLeft <= 0) {
throw new TimeoutException();
}
fCallback.wait(timeLeft);
timeLeft = timeoutTime - System.currentTimeMillis();
}
error = fCallback.getError();
data = fCallback.getData();
}
if (error instanceof CancellationException) {
throw new CancellationException();
} else if (error != null) {
throw new ExecutionException(error);
}
return data;
}
/**
* Don't try to interrupt the DSF executor thread, just ignore the request
* if set.
*/
public boolean cancel(boolean mayInterruptIfRunning) {
boolean completed = false;
synchronized (fCallback) {
completed = fCallback.isCompleted();
if (!completed) {
fCallback.cancel();
fCallback.notifyAll();
}
}
return !completed;
}
public boolean isCancelled() { return fCallback.isCanceled(); }
public boolean isDone() {
synchronized (fCallback) {
// If future is canceled, return right away.
return fCallback.isCompleted() || fCallback.isCanceled();
}
}
abstract protected void execute(DataCallback<V> callback);
public void invoke() {
Protocol.invokeLater(new Runnable() {
public void run() {
if (fCallback.setExecuted()) {
execute(fCallback);
}
}
});
}
}
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