--- /dev/null
+/*-
+ * ========================LICENSE_START=================================
+ * O-RAN-SC
+ *
+ * Copyright (C) 2024: OpenInfra Foundation Europe
+ *
+ * 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.
+ * ========================LICENSE_END===================================
+ */
+
+package com.demo.consumer.consumer;
+
+import org.apache.kafka.clients.consumer.ConsumerRecord;
+import org.apache.kafka.clients.consumer.ConsumerRecords;
+import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.common.TopicPartition;
+import org.apache.kafka.common.errors.WakeupException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.stereotype.Component;
+
+import com.demo.consumer.messages.AbstractSimpleKafka;
+import com.demo.consumer.messages.KafkaMessageHandler;
+import com.demo.consumer.messages.MessageHelper;
+import com.demo.consumer.messages.PropertiesHelper;
+
+import lombok.Getter;
+import lombok.Setter;
+
+import java.util.Properties;
+import java.util.Collections;
+import java.util.List;
+import java.util.Optional;
+import java.time.Duration;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+@Component
+@Setter
+@Getter
+public class SimpleConsumer extends AbstractSimpleKafka {
+ private static final Logger log = LoggerFactory.getLogger(SimpleConsumer.class);
+
+ private KafkaConsumer<String, String> kafkaConsumer = null;
+ private final AtomicBoolean closed = new AtomicBoolean(false);
+
+ @Value("${vars.time:2000}")
+ private int TIME_OUT_MS;
+
+ public void run(String topicName, int numberOfRecords, KafkaMessageHandler callback) throws Exception {
+ Properties props = PropertiesHelper.getProperties();
+ // See if the number of records is provided
+ Optional<Integer> recs = Optional.ofNullable(numberOfRecords);
+
+ // adjust the number of records to get accordingly
+ Integer numOfRecs = recs.orElseGet(() -> Integer.parseInt(props.getProperty("max.poll.records")));
+ props.setProperty("max.poll.records", String.valueOf(numOfRecs));
+
+ // create the consumer
+ KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
+
+ // make the consumer available for graceful shutdown
+ setKafkaConsumer(consumer);
+ consumer.assign(Collections.singleton(new TopicPartition(topicName, 0)));
+ //consumer.seekToBeginning(consumer.assignment()); //--from-beginning
+ int recNum = numOfRecs;
+ while (recNum > 0) {
+ ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(TIME_OUT_MS));
+ recNum = records.count();
+ if (recNum == 0) {
+ log.info(MessageHelper.getSimpleJSONObject("No records retrieved").toJSONString());
+ break;
+ }
+
+ for (ConsumerRecord<String, String> record : records) {
+ callback.processMessage(topicName, record);
+ recNum--;
+ }
+ }
+ consumer.close();
+ }
+
+ private void close() throws Exception {
+ if (this.getKafkaConsumer() == null) {
+ log.info(MessageHelper.getSimpleJSONObject("The internal consumer is NULL").toJSONString());
+ return;
+ }
+ log.info(MessageHelper.getSimpleJSONObject("Closing consumer").toJSONString());
+ this.getKafkaConsumer().close();
+ }
+
+ public void runAlways(String topicName, KafkaMessageHandler callback) throws Exception {
+ Properties props = PropertiesHelper.getProperties();
+ // make the consumer available for graceful shutdown
+ setKafkaConsumer(new KafkaConsumer<>(props));
+
+ // keep running forever or until shutdown() is called from another thread.
+ try {
+ getKafkaConsumer().subscribe(List.of(topicName));
+ while (!closed.get()) {
+ ConsumerRecords<String, String> records = getKafkaConsumer().poll(Duration.ofMillis(TIME_OUT_MS));
+ if (records.count() == 0) {
+ log.info(MessageHelper.getSimpleJSONObject("No records retrieved").toJSONString());
+ }
+
+ for (ConsumerRecord<String, String> record : records) {
+ callback.processMessage(topicName, record);
+ log.info(MessageHelper.getSimpleJSONObject("Topic: " + topicName + "Message: " + record.value()).toJSONString());
+ }
+ }
+ } catch (WakeupException e) {
+ // Ignore exception if closing
+ if (!closed.get())
+ throw e;
+ }
+ }
+
+ public void shutdown() {
+ closed.set(true);
+ try {
+ log.info(MessageHelper.getSimpleJSONObject("Shutting down consumer").toJSONString());
+ } catch (Exception e) {
+ }
+ getKafkaConsumer().wakeup();
+ }
+
+ public KafkaConsumer<String, String> getKafkaConsumer() {
+ return kafkaConsumer;
+ }
+
+ public void setKafkaConsumer(KafkaConsumer<String, String> kafkaConsumer) {
+ this.kafkaConsumer = kafkaConsumer;
+ }
+}