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

      All Methods Instance Methods Abstract Methods 
      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 Detail

      • 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.