/**
* 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
* <p>
* http://www.apache.org/licenses/LICENSE-2.0
* <p>
* 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.hadoop.hdfs.server.datanode.checker;
import com.google.common.base.Optional;
import com.google.common.util.concurrent.ListenableFuture;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.TimeUnit;
/**
* A class that can be used to schedule an asynchronous check on a given
* {@link Checkable}. If the check is successfully scheduled then a
* {@link ListenableFuture} is returned.
*
*/
@InterfaceAudience.Private
@InterfaceStability.Unstable
public interface AsyncChecker<K, V> {
/**
* Schedule an asynchronous check for the given object.
*
* @param target object to be checked.
*
* @param context the interpretation of the context depends on the
* target.
*
* @return returns a {@link Optional of ListenableFuture} that can be used to
* retrieve the result of the asynchronous check.
*/
Optional<ListenableFuture<V>> schedule(Checkable<K, V> target, K context);
/**
* Cancel all executing checks and wait for them to complete.
* First attempts a graceful cancellation, then cancels forcefully.
* Waits for the supplied timeout after both attempts.
*
* See {@link ExecutorService#awaitTermination} for a description of
* the parameters.
*
* @throws InterruptedException
*/
void shutdownAndWait(long timeout, TimeUnit timeUnit)
throws InterruptedException;
}