@Override public boolean source(FlowProcess<JobConf> flowProcess,
SourceCall<Object[], RecordReader> sourceCall) throws IOException {
NullWritable key = (NullWritable) sourceCall.getContext()[0];
ElephantRecordWritable value = (ElephantRecordWritable) sourceCall.getContext()[1];
boolean result = sourceCall.getInput().next(key, value);
if (!result)
return false;