org.neo4j.driver.internal.util.Futures Maven / Gradle / Ivy
/*
* Copyright (c) "Neo4j"
* Neo4j Sweden AB [http://neo4j.com]
*
* This file is part of Neo4j.
*
* 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 org.neo4j.driver.internal.util;
import static java.util.concurrent.CompletableFuture.completedFuture;
import static org.neo4j.driver.internal.util.ErrorUtil.addSuppressed;
import java.util.Objects;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionException;
import java.util.concurrent.CompletionStage;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.Supplier;
import org.neo4j.driver.internal.async.connection.EventLoopGroupFactory;
public final class Futures {
private static final CompletableFuture COMPLETED_WITH_NULL = completedFuture(null);
private Futures() {}
@SuppressWarnings("unchecked")
public static CompletableFuture completedWithNull() {
return (CompletableFuture) COMPLETED_WITH_NULL;
}
public static CompletableFuture completeWithNullIfNoError(CompletableFuture future, Throwable error) {
if (error != null) {
future.completeExceptionally(error);
} else {
future.complete(null);
}
return future;
}
public static CompletionStage asCompletionStage(io.netty.util.concurrent.Future future) {
CompletableFuture result = new CompletableFuture<>();
return asCompletionStage(future, result);
}
public static CompletionStage asCompletionStage(
io.netty.util.concurrent.Future future, CompletableFuture result) {
if (future.isCancelled()) {
result.cancel(true);
} else if (future.isSuccess()) {
result.complete(future.getNow());
} else if (future.cause() != null) {
result.completeExceptionally(future.cause());
} else {
future.addListener(ignore -> {
if (future.isCancelled()) {
result.cancel(true);
} else if (future.isSuccess()) {
result.complete(future.getNow());
} else {
result.completeExceptionally(future.cause());
}
});
}
return result;
}
public static CompletableFuture failedFuture(Throwable error) {
CompletableFuture result = new CompletableFuture<>();
result.completeExceptionally(error);
return result;
}
public static V blockingGet(CompletionStage stage) {
return blockingGet(stage, Futures::noOpInterruptHandler);
}
public static V blockingGet(CompletionStage stage, Runnable interruptHandler) {
EventLoopGroupFactory.assertNotInEventLoopThread();
Future future = stage.toCompletableFuture();
boolean interrupted = false;
try {
while (true) {
try {
return future.get();
} catch (InterruptedException e) {
// this thread was interrupted while waiting
// computation denoted by the future might still be running
interrupted = true;
// run the interrupt handler and ignore if it throws
// need to wait for IO thread to actually finish, can't simply re-rethrow
safeRun(interruptHandler);
} catch (ExecutionException e) {
ErrorUtil.rethrowAsyncException(e);
}
}
} finally {
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
public static T getNow(CompletionStage stage) {
return stage.toCompletableFuture().getNow(null);
}
public static T joinNowOrElseThrow(
CompletableFuture future, Supplier exceptionSupplier) {
if (future.isDone()) {
return future.join();
} else {
throw exceptionSupplier.get();
}
}
/**
* Helper method to extract cause of a {@link CompletionException}.
*
* When using {@link CompletionStage#whenComplete(BiConsumer)} and {@link CompletionStage#handle(BiFunction)} propagated exceptions might get wrapped in a
* {@link CompletionException}.
*
* @param error the exception to get cause for.
* @return cause of the given exception if it is a {@link CompletionException}, given exception otherwise.
*/
public static Throwable completionExceptionCause(Throwable error) {
if (error instanceof CompletionException) {
return error.getCause();
}
return error;
}
/**
* Helped method to turn given exception into a {@link CompletionException}.
*
* @param error the exception to convert.
* @return given exception wrapped with {@link CompletionException} if it's not one already.
*/
public static CompletionException asCompletionException(Throwable error) {
if (error instanceof CompletionException) {
return ((CompletionException) error);
}
return new CompletionException(error);
}
/**
* Combine given errors into a single {@link CompletionException} to be rethrown from inside a
* {@link CompletionStage} chain.
*
* @param error1 the first error or {@code null}.
* @param error2 the second error or {@code null}.
* @return {@code null} if both errors are null, {@link CompletionException} otherwise.
*/
public static CompletionException combineErrors(Throwable error1, Throwable error2) {
if (error1 != null && error2 != null) {
Throwable cause1 = completionExceptionCause(error1);
Throwable cause2 = completionExceptionCause(error2);
addSuppressed(cause1, cause2);
return asCompletionException(cause1);
} else if (error1 != null) {
return asCompletionException(error1);
} else if (error2 != null) {
return asCompletionException(error2);
} else {
return null;
}
}
/**
* Given a future, if the future completes successfully then return a new completed future with the completed value.
* Otherwise if the future completes with an error, then this method first saves the error in the error recorder, and then continues with the onErrorAction.
* @param future the future.
* @param errorRecorder saves error if the given future completes with an error.
* @param onErrorAction continues the future with this action if the future completes with an error.
* @param type
* @return a new completed future with the same completed value if the given future completes successfully, otherwise continues with the onErrorAction.
*/
@SuppressWarnings("ThrowableNotThrown")
public static CompletableFuture onErrorContinue(
CompletableFuture future,
Throwable errorRecorder,
Function> onErrorAction) {
Objects.requireNonNull(future);
return future.handle((value, error) -> {
if (error != null) {
// record error
Futures.combineErrors(errorRecorder, error);
return new CompletionResult(null, error);
}
return new CompletionResult<>(value, null);
})
.thenCompose(result -> {
if (result.value != null) {
return completedFuture(result.value);
} else {
return onErrorAction.apply(result.error);
}
});
}
public static BiConsumer futureCompletingConsumer(CompletableFuture future) {
return (value, throwable) -> {
if (throwable != null) {
future.completeExceptionally(throwable);
} else {
future.complete(value);
}
};
}
private static class CompletionResult {
T value;
Throwable error;
CompletionResult(T value, Throwable error) {
this.value = value;
this.error = error;
}
}
private static void safeRun(Runnable runnable) {
try {
runnable.run();
} catch (Throwable ignore) {
}
}
private static void noOpInterruptHandler() {}
}