dmaap-adaptor-java/src/main/java/org/oran/dmaapadapter/tasks/KafkaTopicListener.java

   1 /*-
   2  * ========================LICENSE_START=================================
   3  * O-RAN-SC
   4  * %%
   5  * Copyright (C) 2021 Nordix Foundation
   6  * %%
   7  * Licensed under the Apache License, Version 2.0 (the "License");
   8  * you may not use this file except in compliance with the License.
   9  * You may obtain a copy of the License at
  10  *
  11  *      http://www.apache.org/licenses/LICENSE-2.0
  12  *
  13  * Unless required by applicable law or agreed to in writing, software
  14  * distributed under the License is distributed on an "AS IS" BASIS,
  15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  16  * See the License for the specific language governing permissions and
  17  * limitations under the License.
  18  * ========================LICENSE_END===================================
  19  */
  20
  21 package org.oran.dmaapadapter.tasks;
  22
  23 import java.util.Collections;
  24 import java.util.HashMap;
  25 import java.util.Map;
  26
  27 import org.apache.kafka.clients.consumer.ConsumerConfig;
  28 import org.apache.kafka.clients.consumer.ConsumerRecord;
  29 import org.apache.kafka.common.serialization.IntegerDeserializer;
  30 import org.apache.kafka.common.serialization.StringDeserializer;
  31 import org.oran.dmaapadapter.configuration.ApplicationConfig;
  32 import org.oran.dmaapadapter.repository.InfoType;
  33 import org.slf4j.Logger;
  34 import org.slf4j.LoggerFactory;
  35
  36 import reactor.core.Disposable;
  37 import reactor.core.publisher.Sinks;
  38 import reactor.core.publisher.Sinks.Many;
  39 import reactor.kafka.receiver.KafkaReceiver;
  40 import reactor.kafka.receiver.ReceiverOptions;
  41
  42 /**
  43  * The class streams incoming requests from a Kafka topic and sends them further
  44  * to a multi cast sink, which several other streams can connect to.
  45  */
  46 @SuppressWarnings("squid:S2629") // Invoke method(s) only conditionally
  47 public class KafkaTopicListener {
  48     private static final Logger logger = LoggerFactory.getLogger(KafkaTopicListener.class);
  49     private final ApplicationConfig applicationConfig;
  50     private final InfoType type;
  51     private final Many<String> output;
  52
  53     public KafkaTopicListener(ApplicationConfig applicationConfig, InfoType type) {
  54         this.applicationConfig = applicationConfig;
  55
  56         final int CONSUMER_BACKPRESSURE_BUFFER_SIZE = 1024 * 10;
  57         this.output = Sinks.many().multicast().onBackpressureBuffer(CONSUMER_BACKPRESSURE_BUFFER_SIZE);
  58
  59         this.type = type;
  60         startKafkaTopicReceiver();
  61     }
  62
  63     public Many<String> getOutput() {
  64         return this.output;
  65     }
  66
  67     private Disposable startKafkaTopicReceiver() {
  68         return KafkaReceiver.create(kafkaInputProperties()) //
  69                 .receive() //
  70                 .doOnNext(this::onReceivedData) //
  71                 .subscribe(null, //
  72                         this::onReceivedError, //
  73                         () -> logger.warn("KafkaTopicReceiver stopped"));
  74     }
  75
  76     private void onReceivedData(ConsumerRecord<Integer, String> input) {
  77         logger.debug("Received from kafka topic: {} :{}", this.type.getKafkaInputTopic(), input.value());
  78         output.emitNext(input.value(), Sinks.EmitFailureHandler.FAIL_FAST);
  79     }
  80
  81     private void onReceivedError(Throwable t) {
  82         logger.error("KafkaTopicReceiver error: {}", t.getMessage());
  83     }
  84
  85     private ReceiverOptions<Integer, String> kafkaInputProperties() {
  86         Map<String, Object> consumerProps = new HashMap<>();
  87         if (this.applicationConfig.getKafkaBootStrapServers().isEmpty()) {
  88             logger.error("No kafka boostrap server is setup");
  89         }
  90         consumerProps.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, this.applicationConfig.getKafkaBootStrapServers());
  91         consumerProps.put(ConsumerConfig.GROUP_ID_CONFIG, "osc-dmaap-adaptor");
  92         consumerProps.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, IntegerDeserializer.class);
  93         consumerProps.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
  94
  95         return ReceiverOptions.<Integer, String>create(consumerProps)
  96                 .subscription(Collections.singleton(this.type.getKafkaInputTopic()));
  97     }
  98
  99 }