Package org.apache.flink.runtime.state

Interface StateTransformationFunction<S,T>

Type Parameters:
S - type of the previous state that is the bases for the computation of the new state.
T - type of the element value that is used to compute the change of state.
@Internal public interface StateTransformationFunction<S,T>
Interface for a binary function that is used for push-down of state transformation into state backends. The function takes as inputs the old state and an element. From those inputs, the function computes the new state.

  • Method Summary

    Modifier and Type
    Method
    Description
    S
    apply(S previousState, T value)
    Binary function that applies a given value to the given old state to compute the new state.

  • Method Details

    • apply

      S apply(S previousState, T value) throws Exception
      Binary function that applies a given value to the given old state to compute the new state.
      Parameters:
      previousState - the previous state that is the basis for the transformation.
      value - the value that the implementation applies to the old state to obtain the new state.
      Returns:
      the new state, computed by applying the given value on the given old state.
      Throws:
      Exception - if something goes wrong in applying the transformation function.