Chain.java 文件源码

/**
 * Returns the OutputCollector to be used by a Mapper instance in the chain.
 *
 * @param mapperIndex index of the Mapper instance to get the OutputCollector.
 * @param output      the original OutputCollector of the task.
 * @param reporter    the reporter of the task.
 * @return the OutputCollector to be used in the chain.
 */
@SuppressWarnings({"unchecked"})
public OutputCollector getMapperCollector(int mapperIndex,
                                          OutputCollector output,
                                          Reporter reporter) {
  Serialization keySerialization = mappersKeySerialization.get(mapperIndex);
  Serialization valueSerialization =
    mappersValueSerialization.get(mapperIndex);
  return new ChainOutputCollector(mapperIndex, keySerialization,
                                  valueSerialization, output, reporter);
}