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* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.tasks;
import org.elasticsearch.common.Nullable;
import java.util.Map;
import java.util.concurrent.atomic.AtomicReference;
/**
* A task that can be canceled
*/
public abstract class CancellableTask extends Task {
private final AtomicReference reason = new AtomicReference<>();
public CancellableTask(long id, String type, String action, String description, TaskId parentTaskId, Map headers) {
super(id, type, action, description, parentTaskId, headers);
}
/**
* This method is called by the task manager when this task is cancelled.
*/
final void cancel(String reason) {
assert reason != null;
this.reason.compareAndSet(null, reason);
onCancelled();
}
/**
* Returns true if this task should be automatically cancelled if the coordinating node that
* requested this task left the cluster.
*/
public boolean cancelOnParentLeaving() {
return true;
}
/**
* Returns true if this task can potentially have children that need to be cancelled when it parent is cancelled.
*/
public abstract boolean shouldCancelChildrenOnCancellation();
public boolean isCancelled() {
return reason.get() != null;
}
/**
* The reason the task was cancelled or null if it hasn't been cancelled.
*/
@Nullable
public String getReasonCancelled() {
return reason.get();
}
/**
* Called after the task is cancelled so that it can take any actions that it has to take.
*/
protected void onCancelled() {
}
}