edu.indiana.d2i.htrc.io.mem.MemCachedRecordWriter.java Source code

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/*
#
# Copyright 2012 The Trustees of Indiana University
#
# Licensed 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.
#
# -----------------------------------------------------------------
#
# Project: knn
# File:  MemCachedRecordWriter.java
# Description:  
#
# -----------------------------------------------------------------
# 
 */

package edu.indiana.d2i.htrc.io.mem;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;

import net.spy.memcached.transcoders.Transcoder;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.mahout.math.VectorWritable;

import edu.indiana.d2i.htrc.HTRCConstants;
import edu.indiana.d2i.htrc.kmeans.MemKMeansConfig;

// should change hard code class
public class MemCachedRecordWriter<K extends Writable, V extends Writable> extends RecordWriter<K, V> {

    private static final Log logger = LogFactory.getLog(MemCachedRecordWriter.class);

    private ThreadedMemcachedClient client = null;
    private Transcoder<V> transcoder = null;
    private final int MAX_EXPIRE;

    private String NameSpace = "";

    public MemCachedRecordWriter(Configuration conf) {
        // read configuration
        MAX_EXPIRE = conf.getInt(HTRCConstants.MEMCACHED_MAX_EXPIRE, -1);
        int numClients = conf.getInt(HTRCConstants.MEMCACHED_CLIENT_NUM, -1);
        String[] hostArray = conf.getStrings(HTRCConstants.MEMCACHED_HOSTS);
        List<String> hosts = Arrays.asList(hostArray);
        Class<?> writableClass = conf.getClass("mapred.output.value.class", Writable.class);

        String namespace = conf.get(MemKMeansConfig.KEY_NS);
        if (namespace != null)
            NameSpace = namespace;

        client = ThreadedMemcachedClient.getThreadedMemcachedClient(numClients, hosts);
        transcoder = new HadoopWritableTranscoder<V>(conf, writableClass);
    }

    @Override
    public void close(TaskAttemptContext arg0) throws IOException, InterruptedException {
        client.close();
    }

    @Override
    public void write(K key, V val) throws IOException, InterruptedException {
        //      System.out.println(key.toString() + " " + ((VectorWritable)val).get());

        //      client.getCache().set(NameSpace + key.toString(), MAX_EXPIRE, val, transcoder);
        client.getCache().set(key.toString(), MAX_EXPIRE, val, transcoder);

        // validate
        //      V vecWritable = client.getCache().get(NameSpace + key.toString(),
        //            transcoder);
        //      if (vecWritable == null) {
        //         throw new RuntimeException(key.toString()
        //               + " is not written to Memcached.");
        //      } else {
        //         logger.info(key.toString());
        //      }
    }

}