com.hazelcast.jet.pipeline

Class AggregateBuilder<R0>

java.lang.Object

com.hazelcast.jet.pipeline.AggregateBuilder<R0>

Type Parameters:

R0 - type of the result of the aggregate operation applied to stage-0 (the one you obtained this builder from)

public class AggregateBuilder<R0>
extends Object

Offers a step-by-step API to build a pipeline stage that co-aggregates the data from several input stages. To obtain it, call BatchStage.aggregateBuilder() on the first stage you are co-aggregating and refer to that method's Javadoc for further details.

Note: this is not a builder of AggregateOperation. If that's what you are looking for, go here.

Since:

Jet 3.0

Method Summary

Modifier and Type	Method and Description
<T,R> Tag<R>	add(BatchStage<T> stage, AggregateOperation1<? super T,?,? extends R> aggrOp) Adds another stage that will contribute its data to the aggregate operation to be performed.
BatchStage<ItemsByTag>	build() Creates and returns a pipeline stage that performs the co-aggregation of the stages registered with this builder object.
<R> BatchStage<R>	build(FunctionEx<? super ItemsByTag,? extends R> finishFn) Creates and returns a pipeline stage that performs the co-aggregation of the stages registered with this builder object.
Tag<R0>	tag0() Returns the tag corresponding to the pipeline stage this builder was obtained from.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

tag0

@Nonnull
public Tag<R0> tag0()

Returns the tag corresponding to the pipeline stage this builder was obtained from. Use it to get the results for this stage from the ItemsByTag appearing in the output of the stage you are building.

add

@Nonnull
public <T,R> Tag<R> add(@Nonnull
                                 BatchStage<T> stage,
                                 @Nonnull
                                 AggregateOperation1<? super T,?,? extends R> aggrOp)

Adds another stage that will contribute its data to the aggregate operation to be performed. Returns the tag you'll use to get the results for this stage from the ItemsByTag appearing in the output of the stage you are building.

build

@Nonnull
public <R> BatchStage<R> build(@Nonnull
                                        FunctionEx<? super ItemsByTag,? extends R> finishFn)

Creates and returns a pipeline stage that performs the co-aggregation of the stages registered with this builder object. The composite aggregate operation places the results of the individual aggregate operations in an ItemsByTag and the finishFn you supply transforms it to the final result to emit. Use the tags you got from this builder in the implementation of finishFn to access the results.

Type Parameters:

R - the output item type

Parameters:

finishFn - the finishing function for the composite aggregate operation. It must be stateless and cooperative.

Returns:

a new stage representing the co-aggregation

build

@Nonnull
public BatchStage<ItemsByTag> build()

Creates and returns a pipeline stage that performs the co-aggregation of the stages registered with this builder object. The composite aggregate operation places the results of the individual aggregate operations in an ItemsByTag. Use the tags you got from this builder to access the results.

Returns:

a new stage representing the co-aggregation