/*
* 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.cluster;
import org.elasticsearch.common.Nullable;
import org.elasticsearch.common.util.concurrent.EsRejectedExecutionException;
/**
* A task that can update the cluster state.
*/
abstract public class ClusterStateUpdateTask {
/**
* Update the cluster state based on the current state. Return the *same instance* if no state
* should be changed.
*/
abstract public ClusterState execute(ClusterState currentState) throws Exception;
/**
* A callback called when execute fails.
*/
abstract public void onFailure(String source, @Nullable Throwable t);
/**
* indicates whether this task should only run if current node is master
*/
public boolean runOnlyOnMaster() {
return true;
}
/**
* called when the task was rejected because the local node is no longer master
*/
public void onNoLongerMaster(String source) {
onFailure(source, new EsRejectedExecutionException("no longer master. source: [" + source + "]"));
}
}