| /* |
| * Copyright (C) 2008 The Guava Authors |
| * |
| * 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 com.google.common.util.concurrent; |
| |
| import com.google.common.annotations.Beta; |
| import com.google.common.annotations.GwtCompatible; |
| import com.google.errorprone.annotations.CanIgnoreReturnValue; |
| 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; |
| |
| /** |
| * A {@code CheckedFuture} is a {@link ListenableFuture} that includes versions of the {@code get} |
| * methods that can throw a checked exception. This makes it easier to create a future that executes |
| * logic which can throw an exception. |
| * |
| * <p><b>Warning:</b> We recommend against using {@code CheckedFuture} in new projects. {@code |
| * CheckedFuture} is difficult to build libraries atop. {@code CheckedFuture} ports of methods like |
| * {@link Futures#transformAsync} have historically had bugs, and some of these bugs are necessary, |
| * unavoidable consequences of the {@code CheckedFuture} API. Additionally, {@code CheckedFuture} |
| * encourages users to take exceptions from one thread and rethrow them in another, producing |
| * confusing stack traces. |
| * |
| * <p>A common implementation is {@link Futures#immediateCheckedFuture}. |
| * |
| * <p>Implementations of this interface must adapt the exceptions thrown by {@code Future#get()}: |
| * {@link CancellationException}, {@link ExecutionException} and {@link InterruptedException} into |
| * the type specified by the {@code X} type parameter. |
| * |
| * <p>This interface also extends the ListenableFuture interface to allow listeners to be added. |
| * This allows the future to be used as a normal {@link Future} or as an asynchronous callback |
| * mechanism as needed. This allows multiple callbacks to be registered for a particular task, and |
| * the future will guarantee execution of all listeners when the task completes. |
| * |
| * <p>For a simpler alternative to CheckedFuture, consider accessing Future values with {@link |
| * Futures#getChecked(Future, Class) Futures.getChecked()}. |
| * |
| * @author Sven Mawson |
| * @since 1.0 |
| * @deprecated {@link CheckedFuture} cannot properly support the chained operations that are the |
| * primary goal of {@link ListenableFuture}. {@code CheckedFuture} also encourages users to |
| * rethrow exceptions from one thread in another thread, producing misleading stack traces. |
| * Additionally, it has a surprising policy about which exceptions to map and which to leave |
| * untouched. Guava users who want a {@code CheckedFuture} can fork the classes for their own |
| * use, possibly specializing them to the particular exception type they use. We recommend that |
| * most people use {@code ListenableFuture} and perform any exception wrapping themselves. This |
| * class is scheduled for removal from Guava in January 2019. |
| */ |
| // TODO(b/72241575): Remove by 2019-01 |
| @Beta |
| @CanIgnoreReturnValue |
| @Deprecated |
| @GwtCompatible |
| public interface CheckedFuture<V, X extends Exception> extends ListenableFuture<V> { |
| |
| /** |
| * Exception checking version of {@link Future#get()} that will translate {@link |
| * InterruptedException}, {@link CancellationException} and {@link ExecutionException} into |
| * application-specific exceptions. |
| * |
| * @return the result of executing the future. |
| * @throws X on interruption, cancellation or execution exceptions. |
| */ |
| V checkedGet() throws X; |
| |
| /** |
| * Exception checking version of {@link Future#get(long, TimeUnit)} that will translate {@link |
| * InterruptedException}, {@link CancellationException} and {@link ExecutionException} into |
| * application-specific exceptions. On timeout this method throws a normal {@link |
| * TimeoutException}. |
| * |
| * @return the result of executing the future. |
| * @throws TimeoutException if retrieving the result timed out. |
| * @throws X on interruption, cancellation or execution exceptions. |
| */ |
| V checkedGet(long timeout, TimeUnit unit) throws TimeoutException, X; |
| } |