org.apache.hawq.pxf.service.rest.ClusterNodesResource.java Source code

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Here is the source code for org.apache.hawq.pxf.service.rest.ClusterNodesResource.java

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package org.apache.hawq.pxf.service.rest;

/*
 * 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.
 */

import org.apache.catalina.connector.ClientAbortException;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.hdfs.DistributedFileSystem;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

/**
 * Class enhances the API of the HBASE rest server.
 * Example for querying API getClusterNodesInfo from a web client
 * <code>curl "http://localhost:51200/pxf/{version}/HadoopCluster/getNodesInfo"</code>
 * /pxf/ is made part of the path when there is a webapp by that name in tcServer.
 */
@Path("/" + Version.PXF_PROTOCOL_VERSION + "/HadoopCluster/")
public class ClusterNodesResource {
    private static final Log LOG = LogFactory.getLog(ClusterNodesResource.class);

    public ClusterNodesResource() {
    }

    /**
     * Function queries the Hadoop namenode with the getDataNodeStats API It
     * gets the host's IP and REST port of every HDFS data node in the cluster.
     * Then, it packs the results in JSON format and writes to the HTTP response
     * stream. Response Examples:<br>
     * <ol>
     * <li>When there are no datanodes - getDataNodeStats returns an empty array
     * <code>{"regions":[]}</code></li>
     * <li>When there are datanodes
     * <code>{"regions":[{"host":"1.2.3.1","port":50075},{"host":"1.2.3.2","port"
     * :50075}]}</code></li>
     * </ol>
     *
     * @return JSON response with nodes info
     * @throws Exception if failed to retrieve info
     */
    @GET
    @Path("getNodesInfo")
    @Produces("application/json")
    public Response read() throws Exception {
        LOG.debug("getNodesInfo started");
        StringBuilder jsonOutput = new StringBuilder("{\"regions\":[");
        try {
            /*
             * 1. Initialize the HADOOP client side API for a distributed file
             * system
             */
            Configuration conf = new Configuration();
            FileSystem fs = FileSystem.get(conf);
            DistributedFileSystem dfs = (DistributedFileSystem) fs;

            /*
             * 2. Query the namenode for the datanodes info. Only live nodes are
             * returned - in accordance with the results returned by
             * org.apache.hadoop.hdfs.tools.DFSAdmin#report().
             */
            DatanodeInfo[] liveNodes = dfs.getDataNodeStats(DatanodeReportType.LIVE);

            /*
             * 3. Pack the datanodes info in a JSON text format and write it to
             * the HTTP output stream.
             */
            String prefix = "";
            for (DatanodeInfo node : liveNodes) {
                verifyNode(node);
                // write one node to the HTTP stream
                jsonOutput.append(prefix).append(writeNode(node));
                prefix = ",";
            }
            jsonOutput.append("]}");
            LOG.debug("getNodesCluster output: " + jsonOutput);
        } catch (NodeDataException e) {
            LOG.error("Nodes verification failed", e);
            throw e;
        } catch (ClientAbortException e) {
            LOG.error("Remote connection closed by HAWQ", e);
            throw e;
        } catch (java.io.IOException e) {
            LOG.error("Unhandled exception thrown", e);
            throw e;
        }

        return Response.ok(jsonOutput.toString(), MediaType.APPLICATION_JSON_TYPE).build();
    }

    private class NodeDataException extends java.io.IOException {

        /**
         *
         */
        private static final long serialVersionUID = 1L;

        public NodeDataException(String paramString) {
            super(paramString);
        }
    }

    private void verifyNode(DatanodeInfo node) throws NodeDataException {
        int port = node.getInfoPort();
        String ip = node.getIpAddr();

        if (StringUtils.isEmpty(ip)) {
            throw new NodeDataException("Invalid IP: " + ip + " (Node " + node + ")");
        }

        if (port <= 0) {
            throw new NodeDataException("Invalid port: " + port + " (Node " + node + ")");
        }
    }

    String writeNode(DatanodeInfo node) throws java.io.IOException {
        return "{\"host\":\"" + node.getIpAddr() + "\",\"port\":" + node.getInfoPort() + "}";
    }
}