com.google.common.util.concurrent.CheckedFuture Maven / Gradle / Ivy
/*
* Original Guava code is copyright (C) 2015 The Guava Authors.
* Modifications from Guava are copyright (C) 2015 DiffPlug.
*
* 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 java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
/**
* 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.
*
* Warning: 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.
*
*
A common implementation is {@link Futures#immediateCheckedFuture}.
*
*
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.
*
*
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.
*
*
For a simpler alternative to CheckedFuture, consider accessing Future
* values with {@link Futures#getChecked(Future, Class) Futures.getChecked()}.
*
* @author Sven Mawson
* @since 1.0
*/
@Beta
@GwtCompatible
public interface CheckedFuture
extends ListenableFuture {
/**
* 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;
}