org.springframework.cloud.stream.ExponentialMovingAverageProcessor.java Source code

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Here is the source code for org.springframework.cloud.stream.ExponentialMovingAverageProcessor.java

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/*
 *  Copyright 2016 original author or authors.
 *
 *  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 org.springframework.cloud.stream;

import java.io.IOException;
import java.time.Duration;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.stream.annotation.Input;
import org.springframework.cloud.stream.annotation.Output;
import org.springframework.cloud.stream.annotation.StreamListener;
import org.springframework.cloud.stream.messaging.Processor;
import org.springframework.stereotype.Component;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

import reactor.core.publisher.Flux;

/**
 * @author Vinicius Carvalho
 */
@Component

public class ExponentialMovingAverageProcessor {

    private ObjectMapper mapper;
    private ExponentialMovingAverageProperties properties;

    @Autowired
    public ExponentialMovingAverageProcessor(ObjectMapper mapper, ExponentialMovingAverageProperties properties) {
        this.mapper = mapper;
        this.properties = properties;
    }

    @StreamListener
    @Output(Processor.OUTPUT)
    public Flux<GroupedMovingAverage> computeEWMA(@Input(Processor.INPUT) Flux<String> emitter) {
        return emitter.map(s -> {
            JsonNode payload = null;
            try {
                payload = mapper.readTree(s);
            } catch (IOException e) {
                e.printStackTrace();
            }
            return payload;
        }).window(Duration.ofSeconds(properties.getWindow()))
                .flatMap(w -> w.groupBy(jsonNode -> jsonNode.get(properties.getGroupKey()).asText())
                        .flatMap(group -> group.reduce(new ExponentialMovingAverage(), (ewma, node) -> {
                            ewma.compute(node.get(properties.getFieldName()).asDouble());
                            return ewma;
                        }).map(ewma1 -> {
                            return new GroupedMovingAverage(group.key(), ewma1.getCurrentValue());
                        })));
    }

}