code: /**
   * Copyright 2009 Saptarshi Guha
   *
   *   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.
   */
  
  package org.godhuli.rhipe;
  
  
  import com.google.protobuf.InvalidProtocolBufferException;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.mapreduce.Partitioner;
  import org.godhuli.rhipe.REXPProtos.REXP;
  
  public class RHPartitionerText extends Partitioner<RHBytesWritable, RHBytesWritable> {
      protected static final Log LOG = LogFactory.getLog(RHPartitionerText.class);
  
      public int getPartition(final RHBytesWritable key, final RHBytesWritable value, final int numReduceTasks) {
          int hashcode = 0;
          try {
              final REXP r = key.getParsed();
              for (int i = RHMRHelper.PARTITION_START; i <= RHMRHelper.PARTITION_END; i++) {
                  // System.err.print( r.getStringValue(i).getStrval());
                  final byte[] a = r.getStringValue(i).getStrval().getBytes();
                  hashcode = hashCode(a, hashcode);
                  // System.err.println(" hashcode="+hashcode);
              }
          }
          catch (InvalidProtocolBufferException e) {
              LOG.error(e);
          }
          return (hashcode & Integer.MAX_VALUE) % numReduceTasks;
      }
  
      protected int hashCode(final byte[] b, int currentHash) {
          for (int i = 0; i < b.length; i++) {
              currentHash = 31 * currentHash + b[i];
          }
          return currentHash;
      }
  
  }