/
FutureUtil.java
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/
FutureUtil.java
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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.
*/
package org.apache.pulsar.common.util;
import com.google.common.util.concurrent.MoreExecutors;
import java.time.Duration;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.function.Predicate;
import java.util.function.Supplier;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import javax.annotation.Nonnull;
import javax.annotation.concurrent.ThreadSafe;
/**
* This class is aimed at simplifying work with {@code CompletableFuture}.
*/
public class FutureUtil {
/**
* Return a future that represents the completion of the futures in the provided Collection.
*
* @param futures futures to wait for
* @return a new CompletableFuture that is completed when all of the given CompletableFutures complete
*/
public static CompletableFuture<Void> waitForAll(Collection<? extends CompletableFuture<?>> futures) {
return CompletableFuture.allOf(futures.toArray(new CompletableFuture[0]));
}
public static CompletableFuture<Void> runWithCurrentThread(Runnable runnable) {
return CompletableFuture.runAsync(
() -> runnable.run(), MoreExecutors.directExecutor());
}
public static <T> CompletableFuture<List<T>> waitForAll(Stream<CompletableFuture<List<T>>> futures) {
return futures.reduce(CompletableFuture.completedFuture(new ArrayList<>()),
(pre, curr) -> pre.thenCompose(preV -> curr.thenApply(currV -> {
preV.addAll(currV);
return preV;
})));
}
/**
* Make the dest future complete after another one. {@param dest} is will be completed with the same value as
* {@param src}, or be completed with the same error as {@param src}.
*/
public static <T> void completeAfter(final CompletableFuture<T> dest, CompletableFuture<T> src) {
src.whenComplete((v, ex) -> {
if (ex != null) {
dest.completeExceptionally(ex);
} else {
dest.complete(v);
}
});
}
/**
* Make the dest future complete after others. {@param dest} is will be completed with a {@link Void} value
* if all the futures of {@param src} is completed, or be completed exceptionally with the same error as the first
* one completed exceptionally future of {@param src}.
*/
public static void completeAfterAll(final CompletableFuture<Void> dest,
CompletableFuture<? extends Object>... src) {
FutureUtil.waitForAll(Arrays.asList(src)).whenComplete((ignore, ex) -> {
if (ex != null) {
dest.completeExceptionally(ex);
} else {
dest.complete(null);
}
});
}
/**
* Return a future that represents the completion of any future in the provided Collection.
*
* @param futures futures to wait any
* @return a new CompletableFuture that is completed when any of the given CompletableFutures complete
*/
public static CompletableFuture<Object> waitForAny(Collection<? extends CompletableFuture<?>> futures) {
return CompletableFuture.anyOf(futures.toArray(new CompletableFuture[0]));
}
/**
* Return a future that represents the completion of any future that match the predicate in the provided Collection.
*
* @param futures futures to wait any
* @param tester if any future match the predicate
* @return a new CompletableFuture that is completed when any of the given CompletableFutures match the tester
*/
public static CompletableFuture<Optional<Object>> waitForAny(Collection<? extends CompletableFuture<?>> futures,
Predicate<Object> tester) {
return waitForAny(futures).thenCompose(v -> {
if (tester.test(v)) {
futures.forEach(f -> {
if (!f.isDone()) {
f.cancel(true);
}
});
return CompletableFuture.completedFuture(Optional.of(v));
}
Collection<CompletableFuture<?>> doneFutures = futures.stream()
.filter(f -> f.isDone())
.collect(Collectors.toList());
futures.removeAll(doneFutures);
Optional<?> value = doneFutures.stream()
.filter(f -> !f.isCompletedExceptionally())
.map(CompletableFuture::join)
.filter(tester)
.findFirst();
if (!value.isPresent()) {
if (futures.size() == 0) {
return CompletableFuture.completedFuture(Optional.empty());
}
return waitForAny(futures, tester);
}
futures.forEach(f -> {
if (!f.isDone()) {
f.cancel(true);
}
});
return CompletableFuture.completedFuture(Optional.of(value.get()));
});
}
/**
* Return a future that represents the completion of the futures in the provided Collection.
* The future will support {@link CompletableFuture#cancel(boolean)}. It will cancel
* all unfinished futures when the future gets cancelled.
*
* @param futures futures to wait for
* @return a new CompletableFuture that is completed when all of the given CompletableFutures complete
*/
public static CompletableFuture<Void> waitForAllAndSupportCancel(
Collection<? extends CompletableFuture<?>> futures) {
CompletableFuture[] futuresArray = futures.toArray(new CompletableFuture[0]);
CompletableFuture<Void> combinedFuture = CompletableFuture.allOf(futuresArray);
whenCancelledOrTimedOut(combinedFuture, () -> {
for (CompletableFuture completableFuture : futuresArray) {
if (!completableFuture.isDone()) {
completableFuture.cancel(false);
}
}
});
return combinedFuture;
}
/**
* If the future is cancelled or times out, the cancel action will be invoked.
*
* The action is executed once if the future completes with
* {@link java.util.concurrent.CancellationException} or {@link TimeoutException}
*
* @param future future to attach the action to
* @param cancelAction action to invoke if the future is cancelled or times out
*/
public static void whenCancelledOrTimedOut(CompletableFuture<?> future, Runnable cancelAction) {
CompletableFutureCancellationHandler cancellationHandler =
new CompletableFutureCancellationHandler();
cancellationHandler.setCancelAction(cancelAction);
cancellationHandler.attachToFuture(future);
}
public static <T> CompletableFuture<T> failedFuture(Throwable t) {
CompletableFuture<T> future = new CompletableFuture<>();
future.completeExceptionally(t);
return future;
}
public static Throwable unwrapCompletionException(Throwable ex) {
if (ex instanceof CompletionException) {
return ex.getCause();
} else if (ex instanceof ExecutionException) {
return ex.getCause();
} else {
return ex;
}
}
@ThreadSafe
public static class Sequencer<T> {
private CompletableFuture<T> sequencerFuture = CompletableFuture.completedFuture(null);
private final boolean allowExceptionBreakChain;
public Sequencer(boolean allowExceptionBreakChain) {
this.allowExceptionBreakChain = allowExceptionBreakChain;
}
public static <T> Sequencer<T> create(boolean allowExceptionBreakChain) {
return new Sequencer<>(allowExceptionBreakChain);
}
public static <T> Sequencer<T> create() {
return new Sequencer<>(false);
}
/**
* @throws NullPointerException NPE when param is null
*/
public synchronized CompletableFuture<T> sequential(Supplier<CompletableFuture<T>> newTask) {
Objects.requireNonNull(newTask);
if (sequencerFuture.isDone()) {
if (sequencerFuture.isCompletedExceptionally() && allowExceptionBreakChain) {
return sequencerFuture;
}
return sequencerFuture = newTask.get();
}
return sequencerFuture = allowExceptionBreakChain
? sequencerFuture.thenCompose(__ -> newTask.get())
: sequencerFuture.exceptionally(ex -> null).thenCompose(__ -> newTask.get());
}
}
/**
* Creates a new {@link CompletableFuture} instance with timeout handling.
*
* @param timeout the duration of the timeout
* @param executor the executor to use for scheduling the timeout
* @param exceptionSupplier the supplier for creating the exception
* @param <T> type parameter for the future
* @return the new {@link CompletableFuture} instance
*/
public static <T> CompletableFuture<T> createFutureWithTimeout(Duration timeout,
ScheduledExecutorService executor,
Supplier<Throwable> exceptionSupplier) {
return addTimeoutHandling(new CompletableFuture<>(), timeout, executor, exceptionSupplier);
}
/**
* Adds timeout handling to an existing {@link CompletableFuture}.
*
* @param future the target future
* @param timeout the duration of the timeout
* @param executor the executor to use for scheduling the timeout
* @param exceptionSupplier the supplier for creating the exception
* @param <T> type parameter for the future
* @return returns the original target future
*/
public static <T> CompletableFuture<T> addTimeoutHandling(CompletableFuture<T> future, Duration timeout,
ScheduledExecutorService executor,
Supplier<Throwable> exceptionSupplier) {
ScheduledFuture<?> scheduledFuture = executor.schedule(() -> {
if (!future.isDone()) {
future.completeExceptionally(exceptionSupplier.get());
}
}, timeout.toMillis(), TimeUnit.MILLISECONDS);
future.whenComplete((res, exception) -> scheduledFuture.cancel(false));
return future;
}
/**
* @throws RejectedExecutionException if this task cannot be accepted for execution
* @throws NullPointerException if one of params is null
*/
public static <T> @Nonnull CompletableFuture<T> composeAsync(Supplier<CompletableFuture<T>> futureSupplier,
Executor executor) {
Objects.requireNonNull(futureSupplier);
Objects.requireNonNull(executor);
final CompletableFuture<T> future = new CompletableFuture<>();
try {
executor.execute(() -> futureSupplier.get().whenComplete((result, error) -> {
if (error != null) {
future.completeExceptionally(error);
return;
}
future.complete(result);
}));
} catch (RejectedExecutionException ex) {
future.completeExceptionally(ex);
}
return future;
}
/**
* Creates a low-overhead timeout exception which is performance optimized to minimize allocations
* and cpu consumption. It sets the stacktrace of the exception to the given source class and
* source method name. The instances of this class can be cached or stored as constants and reused
* multiple times.
*
* @param message exception message
* @param sourceClass source class for manually filled in stacktrace
* @param sourceMethod source method name for manually filled in stacktrace
* @return new TimeoutException instance
*/
public static TimeoutException createTimeoutException(String message, Class<?> sourceClass, String sourceMethod) {
return new LowOverheadTimeoutException(message, sourceClass, sourceMethod);
}
private static class LowOverheadTimeoutException extends TimeoutException {
private static final long serialVersionUID = 1L;
LowOverheadTimeoutException(String message, Class<?> sourceClass, String sourceMethod) {
super(message);
setStackTrace(new StackTraceElement[]{new StackTraceElement(sourceClass.getName(), sourceMethod,
null, -1)});
}
@Override
public synchronized Throwable fillInStackTrace() {
return this;
}
}
public static <T> Optional<Throwable> getException(CompletableFuture<T> future) {
if (future != null && future.isCompletedExceptionally()) {
try {
future.get();
} catch (InterruptedException e) {
return Optional.ofNullable(e);
} catch (ExecutionException e) {
return Optional.ofNullable(e.getCause());
}
}
return Optional.empty();
}
/**
* Wrap throwable exception to CompletionException if that exception is not an instance of CompletionException.
*
* @param throwable Exception
* @return CompletionException
*/
public static CompletionException wrapToCompletionException(Throwable throwable) {
if (throwable instanceof CompletionException) {
return (CompletionException) throwable;
} else {
return new CompletionException(throwable);
}
}
/**
* Executes an operation using the supplied {@link Executor}
* and notify failures on the supplied {@link CompletableFuture}.
*
* @param runnable the runnable to execute
* @param executor the executor to use for executing the runnable
* @param completableFuture the future to complete in case of exceptions
* @return
*/
public static void safeRunAsync(Runnable runnable,
Executor executor,
CompletableFuture completableFuture) {
CompletableFuture
.runAsync(runnable, executor)
.exceptionally((throwable) -> {
completableFuture.completeExceptionally(throwable);
return null;
});
}
}