/**
* 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
*
* 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 org.apache.hadoop.hdfs.util;
import org.apache.hadoop.classification.InterfaceAudience;
/**
* Provides a simple interface where one thread can mark an operation
* for cancellation, and another thread can poll for whether the
* cancellation has occurred.
*/
@InterfaceAudience.Private
public class Canceler {
/**
* If the operation has been canceled, set to the reason why
* it has been canceled (eg standby moving to active)
*/
private volatile String cancelReason = null;
/**
* Requests that the current operation be canceled if it is still running.
* This does not block until the cancellation is successful.
* @param reason the reason why cancellation is requested
*/
public void cancel(String reason) {
this.cancelReason = reason;
}
public boolean isCancelled() {
return cancelReason != null;
}
public String getCancellationReason() {
return cancelReason;
}
}