com.hazelcast.jet.aggregate.AggregateOperation2 Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2021, Hazelcast, Inc. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.hazelcast.jet.aggregate;
import com.hazelcast.function.BiConsumerEx;
import com.hazelcast.function.FunctionEx;
import com.hazelcast.jet.core.Processor;
import javax.annotation.Nonnull;
/**
* Specialization of {@code AggregateOperation} (refer to its {@linkplain
* AggregateOperation extensive documentation}) to the "arity-2" case with
* two data streams being aggregated over. {@link AggregateOperations}
* contains factories for the built-in implementations and you can create
* your own using the {@linkplain AggregateOperation#withCreate aggregate
* operation builder}.
*
* This example constructs an operation that sums up {@code long} values
* from two streams:
*
{@code
* AggregateOperation2 aggrOp = AggregateOperation
* .withCreate(LongAccumulator::new)
* .andAccumulate0(LongAccumulator::add)
* .andAccumulate1(LongAccumulator::add)
* .andFinish(LongAccumulator::get);
* }
*
* All the functions must be stateless and {@linkplain
* Processor#isCooperative() cooperative}.
*
* @param the type of item in stream-0
* @param the type of item in stream-1
* @param the type of the accumulator
* @param the type of the aggregation result
*
* @since Jet 3.0
*/
public interface AggregateOperation2 extends AggregateOperation {
/**
* A primitive that updates the accumulator state to account for a new
* item coming from stream-0.
*
* The consumer must be stateless and {@linkplain Processor#isCooperative()
* cooperative}.
*/
@Nonnull
BiConsumerEx accumulateFn0();
/**
* A primitive that updates the accumulator state to account for a new
* item coming from stream-1.
*
* The consumer must be stateless and {@linkplain Processor#isCooperative()
* cooperative}.
*/
@Nonnull
BiConsumerEx accumulateFn1();
/**
* Returns a copy of this aggregate operation, but with the {@code
* accumulate} primitive at index 0 replaced with the one supplied here.
*
* The consumer must be stateless and {@linkplain Processor#isCooperative()
* cooperative}.
*/
@Nonnull
AggregateOperation2 withAccumulateFn0(
@Nonnull BiConsumerEx newAccFn0
);
/**
* Returns a copy of this aggregate operation, but with the {@code
* accumulate} primitive at index 1 replaced with the one supplied here.
*
* The consumer must be stateless and {@linkplain Processor#isCooperative()
* cooperative}.
*/
@Nonnull
AggregateOperation2 withAccumulateFn1(
@Nonnull BiConsumerEx newAccFn1
);
// Narrows the return type
@Nonnull @Override
AggregateOperation2 withIdentityFinish();
// Narrows the return type
@Nonnull @Override
AggregateOperation2 andThen(FunctionEx thenFn);
}