com.hazelcast.jet.aggregate.AggregateOperation2 Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2018, 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.jet.function.DistributedBiConsumer;
import com.hazelcast.jet.function.DistributedFunction;
import javax.annotation.Nonnull;
/**
* Specialization of {@link AggregateOperation} to the "arity-2" case with
* two data streams being aggregated over. 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);
* }
*
* @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
*/
public interface AggregateOperation2 extends AggregateOperation {
/**
* A primitive that updates the accumulator state to account for a new
* item coming from stream-0.
*/
@Nonnull
DistributedBiConsumer accumulateFn0();
/**
* A primitive that updates the accumulator state to account for a new
* item coming from stream-1.
*/
@Nonnull
DistributedBiConsumer accumulateFn1();
/**
* Returns a copy of this aggregate operation, but with the {@code
* accumulate} primitive at index 0 replaced with the one supplied here.
*/
@Nonnull
AggregateOperation2 withAccumulateFn0(
@Nonnull DistributedBiConsumer newAccFn0
);
/**
* Returns a copy of this aggregate operation, but with the {@code
* accumulate} primitive at index 1 replaced with the one supplied here.
*/
@Nonnull
AggregateOperation2 withAccumulateFn1(
@Nonnull DistributedBiConsumer newAccFn1
);
// Override with a narrowed return type
@Nonnull @Override
AggregateOperation2 withFinishFn(
@Nonnull DistributedFunction finishFn
);
}