org.apache.storm.streams.operations

Interface StateUpdater<T,S>

Type Parameters:

T - the value type

S - the state type

All Superinterfaces:

Operation, Serializable

public interface StateUpdater<T,S>
extends Operation

Interface for updating state.

Method Summary

Modifier and Type	Method and Description
S	apply(S state, T value) Returns a new state by applying the value on the current state.
S	init() The initial value of the state to start with.
static <T,S> StateUpdater<T,S>	of(S initialValue, BiFunction<? super S,? super T,? extends S> stateUpdateFn) A static factory to create a StateUpdater based on an initial value of the state and a state update function.

Method Detail

of

static <T,S> StateUpdater<T,S> of(S initialValue,
                                  BiFunction<? super S,? super T,? extends S> stateUpdateFn)

A static factory to create a StateUpdater based on an initial value of the state and a state update function.

Type Parameters:

T - the value type

S - the state type

Parameters:

initialValue - the intial value of the state

stateUpdateFn - the state update function

Returns:

the StateUpdater

init

S init()

The initial value of the state to start with.

Returns:

the initial value of the state

apply

S apply(S state,
        T value)

Returns a new state by applying the value on the current state.

Parameters:

state - the current state

value - the value

Returns:

the new state