org.apache.hadoop.hdfs.server.diskbalancer.connectors.JsonNodeConnector Maven / Gradle / Ivy
/**
* 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.server.diskbalancer.connectors;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ObjectReader;
import com.google.common.base.Preconditions;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.hdfs.server.diskbalancer.datamodel.DiskBalancerCluster;
import org.apache.hadoop.hdfs.server.diskbalancer.datamodel
.DiskBalancerDataNode;
import java.io.File;
import java.net.URL;
import java.util.List;
/**
* A connector that understands JSON data cluster models.
*/
public class JsonNodeConnector implements ClusterConnector {
private static final Logger LOG =
LoggerFactory.getLogger(JsonNodeConnector.class);
private static final ObjectReader READER =
new ObjectMapper().readerFor(DiskBalancerCluster.class);
private final URL clusterURI;
/**
* Constructs a JsonNodeConnector.
* @param clusterURI - A file URL that contains cluster information.
*/
public JsonNodeConnector(URL clusterURI) {
this.clusterURI = clusterURI;
}
/**
* getNodes function connects to a cluster definition file
* and returns nodes defined in that file.
*
* @return Array of DiskBalancerDataNodes
*/
@Override
public List getNodes() throws Exception {
Preconditions.checkNotNull(this.clusterURI);
String dataFilePath = this.clusterURI.getPath();
LOG.info("Reading cluster info from file : " + dataFilePath);
DiskBalancerCluster cluster = READER.readValue(new File(dataFilePath));
String message = String.format("Found %d node(s)",
cluster.getNodes().size());
LOG.info(message);
return cluster.getNodes();
}
/**
* Returns info about the connector.
*
* @return String.
*/
@Override
public String getConnectorInfo() {
return "Json Cluster Connector : Connects to a JSON file that describes a" +
" cluster : " + clusterURI.toString();
}
}