com.hazelcast.jet.stream

Interface DistributedCollector<T,A,R>

Type Parameters:

T - the type of input elements to the reduction operation

A - the mutable accumulation type of the reduction operation (often hidden as an implementation detail)

R - the result type of the reduction operation

All Superinterfaces:

java.util.stream.Collector<T,A,R>, Serializable

public interface DistributedCollector<T,A,R>
extends java.util.stream.Collector<T,A,R>, Serializable

A mutable reduction operation that accumulates input elements into a mutable result container, optionally transforming the accumulated result into a final representation after all input elements have been processed.

See Also:

Collector, DistributedCollectors

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	DistributedCollector.Reducer<T,R> Interface for Jet specific distributed reducers which execute the terminal reduce operation over the current DistributedStream by building and executing a DAG.

Nested classes/interfaces inherited from interface java.util.stream.Collector

java.util.stream.Collector.Characteristics

Method Summary

Modifier and Type	Method and Description
DistributedBiConsumer<A,T>	accumulator() A function that folds a value into a mutable result container.
DistributedBinaryOperator<A>	combiner() A function that accepts two partial results and merges them.
DistributedFunction<A,R>	finisher() Perform the final transformation from the intermediate accumulation type A to the final result type R.
static <T,A,R> DistributedCollector<T,A,R>	of(DistributedSupplier<A> supplier, DistributedBiConsumer<A,T> accumulator, DistributedBinaryOperator<A> combiner, DistributedFunction<A,R> finisher, java.util.stream.Collector.Characteristics... characteristics) Returns a new DistributedCollector described by the given supplier, accumulator, combiner, and finisher functions.
static <T,R> DistributedCollector<T,R,R>	of(DistributedSupplier<R> supplier, DistributedBiConsumer<R,T> accumulator, DistributedBinaryOperator<R> combiner, java.util.stream.Collector.Characteristics... characteristics) Returns a new DistributedCollector described by the given supplier, accumulator, and combiner functions.
DistributedSupplier<A>	supplier() A function that creates and returns a new mutable result container.

Methods inherited from interface java.util.stream.Collector

characteristics, of, of

Method Detail

supplier

DistributedSupplier<A> supplier()

A function that creates and returns a new mutable result container.

Specified by:

supplier in interface java.util.stream.Collector<T,A,R>

Returns:

a function which returns a new, mutable result container

accumulator

DistributedBiConsumer<A,T> accumulator()

A function that folds a value into a mutable result container.

Specified by:

accumulator in interface java.util.stream.Collector<T,A,R>

Returns:

a function which folds a value into a mutable result container

combiner

DistributedBinaryOperator<A> combiner()

A function that accepts two partial results and merges them. The combiner function may fold state from one argument into the other and return that, or may return a new result container.

Specified by:

combiner in interface java.util.stream.Collector<T,A,R>

Returns:

a function which combines two partial results into a combined result

finisher

DistributedFunction<A,R> finisher()

Perform the final transformation from the intermediate accumulation type A to the final result type R.

If the characteristic IDENTITY_TRANSFORM is set, this function may be presumed to be an identity transform with an unchecked cast from A to R.

Specified by:

finisher in interface java.util.stream.Collector<T,A,R>

Returns:

a function which transforms the intermediate result to the final result

of

static <T,R> DistributedCollector<T,R,R> of(DistributedSupplier<R> supplier,
                                            DistributedBiConsumer<R,T> accumulator,
                                            DistributedBinaryOperator<R> combiner,
                                            java.util.stream.Collector.Characteristics... characteristics)

Returns a new DistributedCollector described by the given supplier, accumulator, and combiner functions. The resulting DistributedCollector has the Collector.Characteristics.IDENTITY_FINISH characteristic.

Type Parameters:

T - The type of input elements for the new collector

R - The type of intermediate accumulation result, and final result, for the new collector

Parameters:

supplier - The supplier function for the new collector

accumulator - The accumulator function for the new collector

combiner - The combiner function for the new collector

characteristics - The collector characteristics for the new collector

Returns:

the new DistributedCollector

Throws:

NullPointerException - if any argument is null

of

static <T,A,R> DistributedCollector<T,A,R> of(DistributedSupplier<A> supplier,
                                              DistributedBiConsumer<A,T> accumulator,
                                              DistributedBinaryOperator<A> combiner,
                                              DistributedFunction<A,R> finisher,
                                              java.util.stream.Collector.Characteristics... characteristics)

Returns a new DistributedCollector described by the given supplier, accumulator, combiner, and finisher functions.

Type Parameters:

T - The type of input elements for the new collector

A - The intermediate accumulation type of the new collector

R - The final result type of the new collector

Parameters:

supplier - The supplier function for the new collector

accumulator - The accumulator function for the new collector

combiner - The combiner function for the new collector

finisher - The finisher function for the new collector

characteristics - The collector characteristics for the new collector

Returns:

the new DistributedCollector

Throws:

NullPointerException - if any argument is null