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ActivePassiveResolver.java
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ActivePassiveResolver.java
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/*
* Copyright (c) 2020, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
*
* WSO2 Inc. 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.wso2.micro.integrator.ntask.coordination.task.resolver;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.wso2.micro.integrator.ntask.coordination.task.ClusterCommunicator;
import java.util.List;
import java.util.Map;
import java.util.Random;
/**
* This resolver selects a random node from the available nodes in the cluster and resolves all the tasks to it. The
* tasks will be resolved to some other node only if the first node leaves the cluster.
*/
public class ActivePassiveResolver implements TaskLocationResolver {
private static final Log log = LogFactory.getLog(ActivePassiveResolver.class);
private String destinedNode = null;
@Override
public void init(Map<String, String> properties) {
throw new UnsupportedOperationException(
"Properties are not supported in " + ActivePassiveResolver.class.getSimpleName());
}
/**
* Provides the node id in which the task need to scheduled.
*
* @param taskName The name of the task.
* @return Node id fot the task.
*/
@Override
public String getTaskNodeLocation(ClusterCommunicator clusterCommunicator, String taskName) {
List<String> allNodesAvailableInCluster = clusterCommunicator.getAllNodeIds();
int noOfNodesInCluster = allNodesAvailableInCluster.size();
if (noOfNodesInCluster == 0) {
log.warn("No nodes are registered to the cluster successfully yet.");
return null;
}
if (destinedNode == null || !allNodesAvailableInCluster.contains(destinedNode)) {
int location = new Random().nextInt();
destinedNode = allNodesAvailableInCluster.get(Math.abs(location) % noOfNodesInCluster);
}
if (log.isDebugEnabled()) {
log.debug("The task : " + taskName + ", is resolved to node with id : " + destinedNode);
}
return destinedNode;
}
}