Package com.hazelcast.jet.aggregate

Interface AggregateOperation2<T0,T1,A,R>

Type Parameters:
T0 - the type of item in stream-0
T1 - the type of item in stream-1
A - the type of the accumulator
R - the type of the aggregation result
All Superinterfaces:
AggregateOperation<A,R>, Serializable
public interface AggregateOperation2<T0,T1,A,R> extends AggregateOperation<A,R>
Specialization of AggregateOperation (refer to its extensive documentation) to the "arity-2" case with two data streams being aggregated over. AggregateOperations contains factories for the built-in implementations and you can create your own using the aggregate operation builder.

This example constructs an operation that sums up long values from two streams: 


 AggregateOperation2<Long, Long, LongAccumulator, Long> aggrOp = AggregateOperation
     .withCreate(LongAccumulator::new)
     .<Long>andAccumulate0(LongAccumulator::add)
     .<Long>andAccumulate1(LongAccumulator::add)
     .andFinish(LongAccumulator::get);

All the functions must be stateless and cooperative.

Since:
Jet 3.0

  • Method Details

    • accumulateFn0

      @Nonnull BiConsumerEx<? super A,? super T0> accumulateFn0()
      A primitive that updates the accumulator state to account for a new item coming from stream-0.

      The consumer must be stateless and cooperative.

    • accumulateFn1

      @Nonnull BiConsumerEx<? super A,? super T1> accumulateFn1()
      A primitive that updates the accumulator state to account for a new item coming from stream-1.

      The consumer must be stateless and cooperative.

    • withAccumulateFn0

      @Nonnull <T0_NEW> AggregateOperation2<T0_NEW,T1,A,R> withAccumulateFn0(@Nonnull BiConsumerEx<? super A,? super T0_NEW> newAccFn0)
      Returns a copy of this aggregate operation, but with the accumulate primitive at index 0 replaced with the one supplied here.

      The consumer must be stateless and cooperative.

    • withAccumulateFn1

      @Nonnull <T1_NEW> AggregateOperation2<T0,T1_NEW,A,R> withAccumulateFn1(@Nonnull BiConsumerEx<? super A,? super T1_NEW> newAccFn1)
      Returns a copy of this aggregate operation, but with the accumulate primitive at index 1 replaced with the one supplied here.

      The consumer must be stateless and cooperative.

    • withIdentityFinish

      @Nonnull AggregateOperation2<T0,T1,A,A> withIdentityFinish()
      Description copied from interface: AggregateOperation
      Returns a copy of this aggregate operation, but with the finish primitive replaced with the identity function. It will return the accumulator object as-is. The returned aggregate operation does not support the export primitive.
      Specified by:
      withIdentityFinish in interface AggregateOperation<T0,T1>

    • andThen

      @Nonnull <R_NEW> AggregateOperation2<T0,T1,A,R_NEW> andThen(FunctionEx<? super R,? extends R_NEW> thenFn)
      Description copied from interface: AggregateOperation
      Returns a copy of this aggregate operation, but with the export and finish primitives composed with the supplied thenFn. This replaces exportFn with exportFn.andThen(thenFn), same for finishFn. The main use case is to transform the result of an existing (library-provided) aggregate operation.

      The given function must be stateless and cooperative.

      Specified by:
      andThen in interface AggregateOperation<T0,T1>
      Type Parameters:
      R_NEW - the type of the returned aggregate operation's result
      Parameters:
      thenFn - the function to apply to the results of export and finish primitives