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/*
* Copyright (c) 2017 BSI Business Systems Integration AG.
* 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:
* BSI Business Systems Integration AG - initial API and implementation
*/
package org.eclipse.scout.sdk.core.s.environment;
import java.util.concurrent.CancellationException;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionException;
import java.util.function.Supplier;
import org.eclipse.scout.sdk.core.log.SdkLog;
import org.eclipse.scout.sdk.core.util.FinalValue;
/**
* <h3>{@link Future}</h3>
*
* @since 7.1.0
*/
public class Future<V> extends CompletableFuture<Supplier<V>> implements IFuture<V> {
/**
* Creates a completed {@link IFuture} with the specified result.
*
* @param result
* The result of the {@link IFuture}. May be {@code null}.
* @return An already completed {@link IFuture} with the specified value.
*/
public static <T> IFuture<T> completed(T result) {
return completed(result, null);
}
/**
* Creates a completed {@link IFuture} with the specified result or exception.
*
* @param result
* The result of the {@link IFuture}. May be {@code null}.
* @param error
* The exception of the {@link IFuture}. May be {@code null}.
* @return An already completed {@link IFuture} with the specified results.
*/
public static <T> IFuture<T> completed(T result, Throwable error) {
return completed(() -> result, error);
}
/**
* Creates a completed {@link IFuture} that uses the result supplier specified to compute the value.
*
* @param resultExtractor
* The {@link Supplier} that provides the result of the resulting {@link IFuture}. The {@link Supplier} is
* only invoked if the provided error is {@code null}.
* @param error
* The exception of the {@link IFuture}. May be {@code null}.
* @return An already completed {@link IFuture} either holding the specified error (if not {@code null}) or the result
* as computed by the {@link Supplier} specified.
*/
public static <T> IFuture<T> completed(Supplier<T> resultExtractor, Throwable error) {
return new Future<T>().doCompletion(false, error, resultExtractor);
}
/**
* Waits until all of the futures specified have completed. A future is completed if it ends successfully, threw an
* exception or was cancelled.
*
* @param futures
* The futures to wait for
* @throws RuntimeException
* if there was an exception during the execution of the future.
*/
public static void awaitAll(Iterable<? extends IFuture<?>> futures) {
if (futures == null) {
return;
}
for (IFuture<?> future : futures) {
if (future != null) {
future.awaitDoneThrowingOnError();
}
}
}
@Override
public Future<V> awaitDoneThrowingOnErrorOrCancel() {
result();
return this;
}
@Override
public Future<V> awaitDoneThrowingOnError() {
try {
join();
}
catch (CancellationException e) {
SdkLog.debug("Cancellation silently ignored", e);
}
return this;
}
protected Future<V> doCompletion(boolean isCancelled, Throwable error, Supplier<V> resultExtractor) {
if (isCancelled) {
completeExceptionally(new CancellationException());
}
else {
if (error == null) {
if (resultExtractor == null) {
complete(() -> null); // the supplier should never be null. only the result provided by the supplier may be null
}
else {
FinalValue<V> cachedResult = new FinalValue<>();
complete(() -> cachedResult.computeIfAbsentAndGet(resultExtractor));
}
}
else {
completeExceptionally(error);
}
}
return this;
}
@Override
public V result() {
try {
return join().get();
}
catch (CompletionException e) {
SdkLog.debug("Future completed with errors.", e);
Throwable cause = e.getCause();
if (cause instanceof RuntimeException) {
throw (RuntimeException) cause;
}
throw e;
}
}
}
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