Package org.apache.flink.streaming.tests.artificialstate

Class ArtificalOperatorStateMapper<IN,​OUT>

  • All Implemented Interfaces:
    Serializable, Function, MapFunction<IN,​OUT>, RichFunction, CheckpointedFunction
    public class ArtificalOperatorStateMapper<IN,​OUT>
extends RichMapFunction<IN,​OUT>
implements CheckpointedFunction
    A self-verifiable RichMapFunction used to verify checkpointing and restore semantics for various kinds of operator state.

    For verifying broadcast state, the each subtask stores as broadcast state a map of (Integer, String) entries, key being the subtask index, and value being a String that corresponds to the subtask index. The total number of subtasks is also stored as broadcast state. On restore, each subtask should be restored with exactly the same broadcast state, with one entry for each subtask in the previous run.

    For verifying union state, each subtask of this operator stores its own subtask index as a subset of the whole union state. On restore, each subtask's restored union state should have one entry for each subtask in the previous run.

    All input elements to the operator arre simply passed through a user-provided map function and emitted.

    See Also:
    Serialized Form

    • Constructor Detail

      • ArtificalOperatorStateMapper

        public ArtificalOperatorStateMapper​(MapFunction<IN,​OUT> mapFunction)

    • Method Detail

      • map

        public OUT map​(IN value)
        throws Exception
        Description copied from interface: MapFunction
        The mapping method. Takes an element from the input data set and transforms it into exactly one element.
        Specified by:
        map in interface MapFunction<IN,​OUT>
        Specified by:
        map in class RichMapFunction<IN,​OUT>
        Parameters:
        value - The input value.
        Returns:
        The transformed value
        Throws:
        Exception - This method may throw exceptions. Throwing an exception will cause the operation to fail and may trigger recovery.

      • initializeState

        public void initializeState​(FunctionInitializationContext context)
                     throws Exception
        Description copied from interface: CheckpointedFunction
        This method is called when the parallel function instance is created during distributed execution. Functions typically set up their state storing data structures in this method.
        Specified by:
        initializeState in interface CheckpointedFunction
        Parameters:
        context - the context for initializing the operator
        Throws:
        Exception - Thrown, if state could not be created ot restored.