code: @Override
      public void prepareToRead(RecordReader reader, PigSplit split) throws IOException
      {
          this.reader = reader;
          this.split = split;
          setIOSerializations(split.getConf());
      }
docs: Initializes LoadFunc for reading data.  This will be called during execution
  before any calls to getNext.  The RecordReader needs to be passed here because
  it has been instantiated for a particular InputSplit.
  
  @param reader {@link org.apache.hadoop.mapreduce.RecordReader} to be used by this instance of the LoadFunc
  @param split  The input {@link org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigSplit} to process
  @throws java.io.IOException if there is an exception during initialization