/*
* Copyright (C) 2011 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.ExecutionException;
import java.util.concurrent.Future;
/**
* Provides a backup {@code Future} to replace an earlier failed {@code Future}.
* An implementation of this interface can be applied to an input {@code Future}
* with {@link Futures#withFallback}.
*
* @param <V> the result type of the provided backup {@code Future}
*
* @author Bruno Diniz
* @since 14.0
*/
@Beta
public interface FutureFallback<V> {
/**
* Returns a {@code Future} to be used in place of the {@code Future} that
* failed with the given exception. The exception is provided so that the
* {@code Fallback} implementation can conditionally determine whether to
* propagate the exception or to attempt to recover.
*
* @param t the exception that made the future fail. If the future's {@link
* Future#get() get} method throws an {@link ExecutionException}, then the
* cause is passed to this method. Any other thrown object is passed
* unaltered.
*/
ListenableFuture<V> create(Throwable t) throws Exception;
}