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/*
* 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 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>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 E} 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#get(Future, Class) Futures.get()}.
*
* @author Sven Mawson
* @since 1.0
*/
@Beta
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;
}
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