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.StringDeserializer;
  30 import org.oran.dmaapadapter.configuration.ApplicationConfig;
  31 import org.oran.dmaapadapter.repository.InfoType;
  32 import org.slf4j.Logger;
  33 import org.slf4j.LoggerFactory;
  34
  35 import reactor.core.Disposable;
  36 import reactor.core.publisher.Sinks;
  37 import reactor.core.publisher.Sinks.Many;
  38 import reactor.kafka.receiver.KafkaReceiver;
  39 import reactor.kafka.receiver.ReceiverOptions;
  40
  41 /**
  42  * The class streams incoming requests from a Kafka topic and sends them further
  43  * to a multi cast sink, which several other streams can connect to.
  44  */
  45 @SuppressWarnings("squid:S2629") // Invoke method(s) only conditionally
  46 public class KafkaTopicListener {
  47     private static final Logger logger = LoggerFactory.getLogger(KafkaTopicListener.class);
  48     private final ApplicationConfig applicationConfig;
  49     private final InfoType type;
  50     private Many<String> output;
  51     private Disposable topicReceiverTask;
  52
  53     public KafkaTopicListener(ApplicationConfig applicationConfig, InfoType type) {
  54         this.applicationConfig = applicationConfig;
  55         this.type = type;
  56     }
  57
  58     public Many<String> getOutput() {
  59         return this.output;
  60     }
  61
  62     public void start() {
  63         stop();
  64         final int CONSUMER_BACKPRESSURE_BUFFER_SIZE = 1024 * 10;
  65         this.output = Sinks.many().multicast().onBackpressureBuffer(CONSUMER_BACKPRESSURE_BUFFER_SIZE);
  66         logger.debug("Listening to kafka topic: {} type :{}", this.type.getKafkaInputTopic(), type.getId());
  67         topicReceiverTask = KafkaReceiver.create(kafkaInputProperties()) //
  68                 .receive() //
  69                 .doOnNext(this::onReceivedData) //
  70                 .subscribe(null, //
  71                         this::onReceivedError, //
  72                         () -> logger.warn("KafkaTopicReceiver stopped"));
  73     }
  74
  75     private void stop() {
  76         if (topicReceiverTask != null) {
  77             topicReceiverTask.dispose();
  78             topicReceiverTask = null;
  79         }
  80     }
  81
  82     private void onReceivedData(ConsumerRecord<String, String> input) {
  83         logger.debug("Received from kafka topic: {} :{}", this.type.getKafkaInputTopic(), input.value());
  84         output.emitNext(input.value(), Sinks.EmitFailureHandler.FAIL_FAST);
  85     }
  86
  87     private void onReceivedError(Throwable t) {
  88         logger.error("KafkaTopicReceiver error: {}", t.getMessage());
  89     }
  90
  91     private ReceiverOptions<String, String> kafkaInputProperties() {
  92         Map<String, Object> consumerProps = new HashMap<>();
  93         if (this.applicationConfig.getKafkaBootStrapServers().isEmpty()) {
  94             logger.error("No kafka boostrap server is setup");
  95         }
  96         consumerProps.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, this.applicationConfig.getKafkaBootStrapServers());
  97         consumerProps.put(ConsumerConfig.GROUP_ID_CONFIG, "osc-dmaap-adaptor");
  98         consumerProps.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
  99         consumerProps.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
 100
 101         return ReceiverOptions.<String, String>create(consumerProps)
 102                 .subscription(Collections.singleton(this.type.getKafkaInputTopic()));
 103     }
 104
 105 }