Interface PartitionReducer

  • All Known Implementing Classes:
    AbstractPartitionReducer

    public interface PartitionReducer
    PartitionReducer provides unit of work demarcation across partitions. It is not a JTA transaction; no resources are enlisted. Rather, it provides transactional flow semantics to facilitate finalizing merge or compensation logic.
    • Method Detail

      • beginPartitionedStep

        void beginPartitionedStep()
                           throws Exception
        The beginPartitionedStep method receives control at the start of partition processing. It receives control before the PartitionMapper is invoked and before any partitions are started.
        Throws:
        Exception - is thrown if an error occurs.
      • beforePartitionedStepCompletion

        void beforePartitionedStepCompletion()
                                      throws Exception
        The beforePartitionedStepCompletion method receives control at the end of partitioned step processing. It receives control after all partitions have completed. It does not receive control if the PartitionReducer is rolling back.
        Throws:
        Exception - is thrown if an error occurs.
      • rollbackPartitionedStep

        void rollbackPartitionedStep()
                              throws Exception

        The rollbackPartitionedStep method receives control if the runtime is rolling back a partitioned step. Any partition threads still running are allowed to complete before this method is invoked. This method receives control if any of the following conditions are true:

        1. One or more partitions end with a Batch Status of STOPPED or FAILED.
        2. Any of the following partitioned step callbacks throw an exception:
          PartitionMapper
          PartitionReducer
          PartitionCollector
          PartitionAnalyzer
        3. A job with partitioned steps is restarted.
        Throws:
        Exception - is thrown if an error occurs.
      • afterPartitionedStepCompletion

        void afterPartitionedStepCompletion​(PartitionReducer.PartitionStatus status)
                                     throws Exception
        The afterPartitionedStepCompletion method receives control at the end of a partition processing. It receives a status value that identifies the outcome of the partition processing. The status string value is either "COMMIT" or "ROLLBACK".
        Parameters:
        status - specifies the outcome of the partitioned step. Values are "COMMIT" or "ROLLBACK".
        Throws:
        Exception - is thrown if an error occurs.