/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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
* <p/>
* http://www.apache.org/licenses/LICENSE-2.0
* <p/>
* 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 kafka.examples.consumer;
import static net.sourceforge.argparse4j.impl.Arguments.store;
import java.io.Serializable;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Properties;
import java.util.concurrent.CountDownLatch;
import kafka.examples.common.serialization.CustomDeserializer;
import net.sourceforge.argparse4j.ArgumentParsers;
import net.sourceforge.argparse4j.inf.ArgumentParser;
import net.sourceforge.argparse4j.inf.ArgumentParserException;
import net.sourceforge.argparse4j.inf.Namespace;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRebalanceListener;
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;
/**
* <p>This example demonstrates the usage of basic poll loop and
* consumer coordination in a group<p>
*
* <p> Run multiple {@link BasicConsumeLoop} by providing same group id and
* different client id so that all the consumer instances belongs
* to a same group and consumption load gets re-balanced across
* the consumer instances.<p>
*/
public class BasicConsumeLoop<K extends Serializable, V extends Serializable> implements Runnable {
private static final Logger logger = LoggerFactory.getLogger(BasicConsumeLoop.class);
private final KafkaConsumer<K, V> consumer;
private final List<String> topics;
private final String clientId;
private CountDownLatch shutdownLatch = new CountDownLatch(1);
public BasicConsumeLoop(Properties configs, List<String> topics) {
this.clientId = configs.getProperty(ConsumerConfig.CLIENT_ID_CONFIG);
this.topics = topics;
this.consumer = new KafkaConsumer<>(configs);
}
@Override
public void run() {
try {
logger.info("Starting the Consumer : {}", clientId);
ConsumerRebalanceListener listener = new ConsumerRebalanceListener() {
@Override
public void onPartitionsRevoked(Collection<TopicPartition> partitions) {
logger.info("C : {}, Revoked partitionns : {}", clientId, partitions);
}
@Override
public void onPartitionsAssigned(Collection<TopicPartition> partitions) {
logger.info("C : {}, Assigned partitions : {}", clientId, partitions);
}
};
consumer.subscribe(topics, listener);
logger.info("C : {}, Started to process records", clientId);
while(true) {
ConsumerRecords<K, V> records = consumer.poll(Long.MAX_VALUE);
if(records.isEmpty()) {
logger.info("C : {}, Found no records", clientId);
continue;
}
logger.info("C : {} Total No. of records received : {}", clientId, records.count());
for (ConsumerRecord<K, V> record : records) {
logger.info("C : {}, Record received partition : {}, key : {}, value : {}, offset : {}",
clientId, record.partition(), record.key(), record.value(), record.offset());
sleep(50);
}
// `enable.auto.commit` set to true. coordinator automatically commits the offsets
// returned on the last poll(long) for all the subscribed list of topics and partitions
}
} catch (WakeupException e) {
// Ignore, we're closing
} finally {
consumer.close();
shutdownLatch.countDown();
logger.info("C : {}, consumer exited", clientId);
}
}
private void sleep(long millis) {
try {
Thread.sleep(millis);
} catch (InterruptedException e) {
logger.error("Error", e);
}
}
public void close() {
try {
consumer.wakeup();
shutdownLatch.await();
} catch (InterruptedException e) {
logger.error("Error", e);
}
}
public static void main(String[] args) throws InterruptedException {
ArgumentParser parser = argParser();
try {
Namespace result = parser.parseArgs(args);
List<String> topics = Arrays.asList(result.getString("topics").split(","));
Properties configs = getConsumerConfigs(result);
final BasicConsumeLoop<Serializable, Serializable> consumer = new BasicConsumeLoop<>(configs, topics);
consumer.run();
Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {
@Override
public void run() {
consumer.close();
}
}));
} catch (ArgumentParserException e) {
if(args.length == 0)
parser.printHelp();
else
parser.handleError(e);
System.exit(0);
}
}
private static Properties getConsumerConfigs(Namespace result) {
Properties configs = new Properties();
configs.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, result.getString("bootstrap.servers"));
configs.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, result.getString("auto.offset.reset"));
configs.put(ConsumerConfig.GROUP_ID_CONFIG, result.getString("groupId"));
configs.put(ConsumerConfig.CLIENT_ID_CONFIG, result.getString("clientId"));
configs.put(ConsumerConfig.MAX_PARTITION_FETCH_BYTES_CONFIG, result.getString("max.partition.fetch.bytes"));
configs.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, "true");
configs.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, CustomDeserializer.class.getName());
configs.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, CustomDeserializer.class.getName());
return configs;
}
/**
* Get the command-line argument parser.
*/
private static ArgumentParser argParser() {
ArgumentParser parser = ArgumentParsers
.newArgumentParser("basic-consumer-loop")
.defaultHelp(true)
.description("This example demonstrates kafka consumer auto subscription capabilities");
parser.addArgument("--bootstrap.servers").action(store())
.required(true)
.type(String.class)
.help("comma separated broker list");
parser.addArgument("--topics").action(store())
.required(true)
.type(String.class)
.help("consume messages from topics. Comma separated list e.g. t1,t2");
parser.addArgument("--groupId").action(store())
.required(true)
.type(String.class)
.help("Group Identifier");
parser.addArgument("--clientId").action(store())
.required(true)
.type(String.class)
.help("Client Identifier");
parser.addArgument("--auto.offset.reset").action(store())
.required(false)
.setDefault("earliest")
.type(String.class)
.choices("earliest", "latest")
.help("What to do when there is no initial offset in Kafka");
parser.addArgument("--max.partition.fetch.bytes").action(store())
.required(false)
.setDefault("1024")
.type(String.class)
.help("The maximum amount of data per-partition the server will return");
return parser;
}
}
/**
* $Log$
*
*/
