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/**
* ============LICENSE_START=======================================================
* org.onap.aai
* ================================================================================
* Copyright © 2017-2018 AT&T Intellectual Property. All rights reserved.
* Copyright © 2017-2018 European Software Marketing Ltd.
* ================================================================================
* 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 org.onap.aai.event.client;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import org.apache.kafka.clients.consumer.ConsumerConfig;
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.clients.consumer.OffsetAndMetadata;
import org.apache.kafka.common.TopicPartition;
import org.apache.kafka.common.serialization.StringDeserializer;
import org.onap.aai.cl.api.Logger;
import org.onap.aai.cl.eelf.LoggerFactory;
import org.onap.aai.event.api.EventConsumer;
import org.onap.aai.event.api.MessageWithOffset;
/**
* Event Bus Client consumer API for Kafka Implementation .Its a wrapper around KafkaConsumer which is NOT thread safe.
* The KafkaConsumer maintains TCP connections to the necessary brokers to fetch data. Failure to close the consumer
* after use will leak these connections Ref : https://kafka.apache.org/0102/javadoc/org/apache/kafka/clients/consumer/
* KafkaConsumer.html
*
*/
public class KafkaEventConsumer implements EventConsumer {
private static Logger log = LoggerFactory.getInstance().getLogger(KafkaEventConsumer.class);
@FunctionalInterface
public interface KafkaConsumerFactory {
public KafkaConsumer<String, String> createConsumer(Properties props);
}
private static KafkaConsumerFactory consumerFactory = KafkaConsumer::new;
private final KafkaConsumer<String, String> consumer;
/**
*
* @param hosts - A list of host/port pairs to use for establishing the initial connection to the Kafka cluster. The
* client will make use of all servers irrespective of which servers are specified here for
* bootstrapping—this list only impacts the initial hosts used to discover the full set of servers. This list
* should be in the form host1:port1,host2:port2,....
* @param topic - Topic to consume the messages from
* @param groupId - A unique string that identifies the consumer group this consumer belongs to
*/
public KafkaEventConsumer(String hosts, String topic, String groupId) {
Properties props = new Properties();
props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, hosts);
props.put(ConsumerConfig.GROUP_ID_CONFIG, groupId);
// Set this property, if auto commit should happen.
props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, "false");
props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
consumer = consumerFactory.createConsumer(props);
consumer.subscribe(Arrays.asList(topic));
}
/**
* Replace the consumer factory (intended to be used for testing purposes only).
*
* @param consumerFactory
*/
static void setConsumerFactory(KafkaConsumerFactory consumerFactory) {
KafkaEventConsumer.consumerFactory = consumerFactory;
}
@Override
public void close() {
consumer.close();
}
/**
*
*/
@Override
public Iterable<String> consume() throws Exception {
log.debug("Querying Kafka for messages");
ConsumerRecords<String, String> records = consumer.poll(0);
List<String> list = new ArrayList<>();
for (ConsumerRecord<String, String> record : records) {
list.add(record.value());
}
return list;
}
@Override
public Iterable<MessageWithOffset> consumeWithOffsets() throws Exception {
log.debug("Querying Kafka for messages");
ConsumerRecords<String, String> records = consumer.poll(0);
List<MessageWithOffset> list = new ArrayList<>();
for (ConsumerRecord<String, String> record : records) {
list.add(new MessageWithOffset(record.offset(), record.value()));
}
return list;
}
@Override
public Iterable<String> consumeAndCommit() throws Exception {
Iterable<String> result = consume();
consumer.commitSync();
return result;
}
@Override
public void commitOffsets() throws Exception {
consumer.commitSync();
}
@Override
public void commitOffsets(long offset) throws Exception {
Map<TopicPartition, OffsetAndMetadata> offsetsMap = new HashMap<>();
offsetsMap.put(consumer.assignment().iterator().next(), new OffsetAndMetadata(offset));
consumer.commitSync(offsetsMap);
}
}
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