| /* |
| * 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.cassandra.spark.utils; |
| |
| import java.util.ArrayList; |
| import java.util.Collection; |
| import java.util.List; |
| import java.util.Objects; |
| import java.util.concurrent.CompletableFuture; |
| import java.util.concurrent.ExecutionException; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.TimeoutException; |
| import java.util.function.Consumer; |
| import java.util.stream.Collectors; |
| |
| import org.jetbrains.annotations.NotNull; |
| import org.jetbrains.annotations.Nullable; |
| |
| public final class FutureUtils |
| { |
| public static final class FutureResult<T> |
| { |
| @Nullable |
| public final T value; |
| @Nullable |
| public final Throwable throwable; |
| |
| private FutureResult(@Nullable T value, @Nullable Throwable throwable) |
| { |
| this.value = value; |
| this.throwable = throwable; |
| } |
| |
| public static <T> FutureResult<T> failed(@NotNull Throwable throwable) |
| { |
| return new FutureResult<>(null, throwable); |
| } |
| |
| public static <T> FutureResult<T> success(@Nullable T value) |
| { |
| return new FutureResult<>(value, null); |
| } |
| |
| @Nullable |
| public T value() |
| { |
| return value; |
| } |
| |
| public boolean isSuccess() |
| { |
| return throwable == null; |
| } |
| } |
| |
| private FutureUtils() |
| { |
| throw new IllegalStateException(getClass() + " is static utility class and shall not be instantiated"); |
| } |
| |
| /** |
| * Await all futures and combine into single result |
| * |
| * @param <T> result type returned by this method |
| * @param futures collection of futures |
| * @param acceptPartialResult if false, fail the entire request if a single failure occurs, if true just log partial failures |
| * @param onFailure consumer of errors |
| * @return result of all combined futures |
| */ |
| public static <T> List<T> awaitAll(Collection<CompletableFuture<T>> futures, |
| boolean acceptPartialResult, |
| Consumer<Throwable> onFailure) |
| { |
| List<T> result = new ArrayList<>(futures.size()); |
| for (CompletableFuture<T> future : futures) |
| { |
| FutureResult<T> futureResult = await(future, onFailure); |
| if (futureResult.throwable != null) |
| { |
| // Failed |
| if (!acceptPartialResult) |
| { |
| throw new RuntimeException(ThrowableUtils.rootCause(futureResult.throwable)); |
| } |
| } |
| else if (futureResult.value != null) |
| { |
| // Success |
| result.add(futureResult.value); |
| } |
| } |
| return result; |
| } |
| |
| /** |
| * Await a future and return result |
| * |
| * @param future the future |
| * @param logger consumer to log errors |
| * @param <T> result type returned by this method |
| * @return result of the future |
| */ |
| @NotNull |
| public static <T> FutureResult<T> await(CompletableFuture<T> future, Consumer<Throwable> logger) |
| { |
| try |
| { |
| return FutureResult.success(future.get()); |
| } |
| catch (InterruptedException exception) |
| { |
| Thread.currentThread().interrupt(); |
| throw new RuntimeException(exception); |
| } |
| catch (ExecutionException exception) |
| { |
| logger.accept(exception); |
| return FutureResult.failed(exception); |
| } |
| } |
| |
| /** |
| * Combine futures into a single future that completes when all futures complete successfully, or fails if any future fails |
| * |
| * @param <T> result type returned by this method |
| * @param futures array of futures |
| * @return a single future that combines all future results |
| */ |
| public static <T> CompletableFuture<List<T>> combine(List<CompletableFuture<T>> futures) |
| { |
| CompletableFuture<List<T>> result = new CompletableFuture<>(); |
| CompletableFuture.allOf(futures.toArray(new CompletableFuture[0])) |
| .whenComplete((aVoid, aThrowable) -> { |
| if (aThrowable == null) |
| { |
| try |
| { |
| // Combine future results into a single list: get is called, but it will not block as all the futures have completed |
| result.complete(awaitAll(futures, false, throwable -> { })); |
| } |
| catch (Throwable throwable) |
| { |
| result.completeExceptionally(ThrowableUtils.rootCause(throwable)); |
| } |
| } |
| else |
| { |
| result.completeExceptionally(aThrowable); |
| } |
| }); |
| return result; |
| } |
| |
| /** |
| * Makes a best-effort attempt to obtain results of a collection of completable futures |
| * within the specified timeout, then combines and returns all received non-null values |
| * |
| * @param futures list of futures to obtain results from |
| * @param timeout duration of the timeout to use |
| * @param timeUnit units of the timeout |
| * @return list on non-null values obtained |
| */ |
| public static <T> List<T> bestEffortGet(List<CompletableFuture<T>> futures, long timeout, TimeUnit timeUnit) |
| { |
| try |
| { |
| // As a barrier |
| CompletableFuture.allOf(futures.toArray(new CompletableFuture[0])) |
| .get(timeout, timeUnit); |
| } |
| catch (InterruptedException | ExecutionException | TimeoutException exception) |
| { |
| // Do nothing, cancel later |
| } |
| return futures.stream() |
| .map(future -> { |
| if (future.isDone()) |
| { |
| // Convert exception into null and ignore later |
| return future.exceptionally(t -> null) |
| .join(); |
| } |
| else |
| { |
| future.cancel(true); |
| return null; |
| } |
| }) |
| .filter(Objects::nonNull) |
| .collect(Collectors.toList()); |
| } |
| } |