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

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Here is the source code for org.apache.hawq.pxf.service.rest.AnalyzerResource.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.hawq.pxf.api.Analyzer;
import org.apache.hawq.pxf.api.AnalyzerStats;
import org.apache.hawq.pxf.service.AnalyzerFactory;
import org.apache.hawq.pxf.service.utilities.ProtocolData;
import org.apache.hawq.pxf.service.utilities.SecuredHDFS;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import javax.servlet.ServletContext;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.HttpHeaders;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import java.io.IOException;
import java.util.Map;

/*
 * Class enhances the API of the WEBHDFS REST server.
 * Returns the data fragments that a data resource is made of, enabling parallel processing of the data resource.
 * Example for querying API ANALYZER from a web client
 * curl -i "http://localhost:50070/pxf/v2/Analyzer/getEstimatedStats?path=/dir1/dir2/*txt"
 * /pxf/ is made part of the path when there is a webapp by that name in tcServer.
 */
@Path("/" + Version.PXF_PROTOCOL_VERSION + "/Analyzer/")
public class AnalyzerResource extends RestResource {
    private Log Log;

    public AnalyzerResource() throws IOException {
        Log = LogFactory.getLog(AnalyzerResource.class);
    }

    /*
     * Returns estimated statistics for the given path (data source).
     * Example for querying API ANALYZER from a web client
     * curl -i "http://localhost:50070/pxf/v2/Analyzer/getEstimatedStats?path=/dir1/dir2/*txt"
     * A default answer, unless an analyzer implements getEstimatedStats, would be:
     * {"PXFDataSourceStats":[{"blockSize":67108864,"numberOfBlocks":1000,"numberOfTuples":1000000}]}
     * Currently only HDFS is implemented to calculate the block size and block number,
     * and returns -1 for number of tuples.
     * Example:
     * {"PXFDataSourceStats":[{"blockSize":67108864,"numberOfBlocks":3,"numberOfTuples":-1}]}
     *
     * @param servletContext Servlet context contains attributes required by SecuredHDFS
     * @param headers Holds HTTP headers from request
     * @param path Holds URI path option used in this request
     */
    @GET
    @Path("getEstimatedStats")
    @Produces("application/json")
    public Response getEstimatedStats(@Context ServletContext servletContext, @Context final HttpHeaders headers,
            @QueryParam("path") String path) throws Exception {

        if (Log.isDebugEnabled()) {
            StringBuilder startmsg = new StringBuilder(
                    "ANALYZER/getEstimatedStats started for path \"" + path + "\"");
            if (headers != null) {
                for (String header : headers.getRequestHeaders().keySet()) {
                    startmsg.append(" Header: ").append(header).append(" Value: ")
                            .append(headers.getRequestHeader(header));
                }
            }
            Log.debug(startmsg);
        }

        /* Convert headers into a regular map */
        Map<String, String> params = convertToCaseInsensitiveMap(headers.getRequestHeaders());

        /* Store protocol level properties and verify */
        final ProtocolData protData = new ProtocolData(params);
        SecuredHDFS.verifyToken(protData, servletContext);

        /*
         * Analyzer is a special case in which it is hard to tell if user didn't
         * specify one, or specified a profile that doesn't include one, or it's
         * an actual protocol violation. Since we can only test protocol level
         * logic, we assume (like before) that it's a user error, which is the
         * case in most likelihood. When analyzer module is removed in the near
         * future, this assumption will go away with it.
         */
        if (protData.getAnalyzer() == null) {
            throw new IllegalArgumentException(
                    "PXF 'Analyzer' class was not found. Please supply it in the LOCATION clause or use it in a PXF profile in order to run ANALYZE on this table");
        }

        /* Create an analyzer instance with API level parameters */
        final Analyzer analyzer = AnalyzerFactory.create(protData);

        /*
           * Function queries the pxf Analyzer for the data fragments of the resource
         * The fragments are returned in a string formatted in JSON    
         */
        String jsonOutput = AnalyzerStats.dataToJSON(analyzer.getEstimatedStats(path));

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