package de.juplo.kafka;
+import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
-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.*;
+import org.apache.kafka.common.TopicPartition;
+import org.apache.kafka.common.errors.RecordDeserializationException;
import org.apache.kafka.common.errors.WakeupException;
-import org.apache.kafka.common.serialization.StringDeserializer;
+import javax.annotation.PreDestroy;
import java.time.Duration;
-import java.util.Arrays;
-import java.util.Properties;
+import java.util.*;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
@Slf4j
-public class SimpleConsumer
+@RequiredArgsConstructor
+public class EndlessConsumer<K, V> implements Runnable
{
+ private final ExecutorService executor;
+ private final String id;
+ private final String topic;
+ private final Consumer<K, V> consumer;
+ private final RebalanceListener rebalanceListener;
+ private final RecordHandler<K, V> recordHandler;
+
+ private final Lock lock = new ReentrantLock();
+ private final Condition condition = lock.newCondition();
+ private boolean running = false;
+ private Exception exception;
private long consumed = 0;
- private KafkaConsumer<String, String> consumer;
- private Lock lock = new ReentrantLock();
- private Condition stopped = lock.newCondition();
- public SimpleConsumer()
- {
- // tag::create[]
- Properties props = new Properties();
- props.put("bootstrap.servers", ":9092");
- props.put("group.id", "my-consumer"); // << Used for Offset-Commits
- // end::create[]
- props.put("auto.offset.reset", "earliest");
- // tag::create[]
- props.put("key.deserializer", StringDeserializer.class.getName());
- props.put("value.deserializer", StringDeserializer.class.getName());
-
- KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
- // end::create[]
- this.consumer = consumer;
- }
-
+ @Override
public void run()
{
- String id = "C";
-
try
{
- log.info("{} - Subscribing to topic test", id);
- consumer.subscribe(Arrays.asList("test"));
+ log.info("{} - Subscribing to topic {}", id, topic);
+ consumer.subscribe(Arrays.asList(topic), rebalanceListener);
- // tag::loop[]
while (true)
{
- ConsumerRecords<String, String> records =
+ ConsumerRecords<K, V> records =
consumer.poll(Duration.ofSeconds(1));
// Do something with the data...
- // end::loop[]
log.info("{} - Received {} messages", id, records.count());
- for (ConsumerRecord<String, String> record : records)
+ for (ConsumerRecord<K, V> record : records)
{
- consumed++;
log.info(
"{} - {}: {}/{} - {}={}",
id,
record.key(),
record.value()
);
+
+ recordHandler.accept(record);
+
+ consumed++;
}
- // tag::loop[]
+
+ rebalanceListener.beforeNextPoll();
}
- // end::loop[]
}
catch(WakeupException e)
{
- log.info("{} - RIIING!", id);
+ log.info("{} - RIIING! Request to stop consumption - commiting current offsets!", id);
+ consumer.commitSync();
+ shutdown();
+ }
+ catch(RecordDeserializationException e)
+ {
+ TopicPartition tp = e.topicPartition();
+ long offset = e.offset();
+ log.error(
+ "{} - Could not deserialize message on topic {} with offset={}: {}",
+ id,
+ tp,
+ offset,
+ e.getCause().toString());
+
+ consumer.commitSync();
+ shutdown(e);
}
catch(Exception e)
{
- log.error("{} - Unexpected error: {}", id, e.toString());
+ log.error("{} - Unexpected error: {}", id, e.toString(), e);
+ shutdown(e);
}
finally
{
- this.lock.lock();
- try
- {
- log.info("{} - Closing the KafkaConsumer", id);
- consumer.close();
- log.info("C - DONE!");
- stopped.signal();
- }
- finally
- {
- this.lock.unlock();
- log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
- }
+ log.info("{} - Consumer-Thread exiting", id);
}
}
-
- public static void main(String[] args) throws Exception
+ private void shutdown()
{
- SimpleConsumer instance = new SimpleConsumer();
+ shutdown(null);
+ }
- Runtime.getRuntime().addShutdownHook(new Thread(() ->
+ private void shutdown(Exception e)
+ {
+ lock.lock();
+ try
{
- instance.lock.lock();
try
{
- instance.consumer.wakeup();
- instance.stopped.await();
+ log.info("{} - Unsubscribing from topic {}", id, topic);
+ consumer.unsubscribe();
}
- catch (InterruptedException e)
+ catch (Exception ue)
{
- log.warn("Interrrupted while waiting for the consumer to stop!", e);
+ log.error(
+ "{} - Error while unsubscribing from topic {}: {}",
+ id,
+ topic,
+ ue.toString());
}
finally
{
- instance.lock.unlock();
+ running = false;
+ exception = e;
+ condition.signal();
}
- }));
+ }
+ finally
+ {
+ lock.unlock();
+ }
+ }
+
+ public void start()
+ {
+ lock.lock();
+ try
+ {
+ if (running)
+ throw new IllegalStateException("Consumer instance " + id + " is already running!");
+
+ log.info("{} - Starting - consumed {} messages before", id, consumed);
+ running = true;
+ exception = null;
+ executor.submit(this);
+ }
+ finally
+ {
+ lock.unlock();
+ }
+ }
- instance.run();
+ public synchronized void stop() throws InterruptedException
+ {
+ lock.lock();
+ try
+ {
+ if (!running)
+ throw new IllegalStateException("Consumer instance " + id + " is not running!");
+
+ log.info("{} - Stopping", id);
+ consumer.wakeup();
+ condition.await();
+ log.info("{} - Stopped - consumed {} messages so far", id, consumed);
+ }
+ finally
+ {
+ lock.unlock();
+ }
+ }
+
+ @PreDestroy
+ public void destroy() throws ExecutionException, InterruptedException
+ {
+ log.info("{} - Destroy!", id);
+ log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
+ }
+
+ public boolean running()
+ {
+ lock.lock();
+ try
+ {
+ return running;
+ }
+ finally
+ {
+ lock.unlock();
+ }
+ }
+
+ public Optional<Exception> exitStatus()
+ {
+ lock.lock();
+ try
+ {
+ if (running)
+ throw new IllegalStateException("No exit-status available: Consumer instance " + id + " is running!");
+
+ return Optional.ofNullable(exception);
+ }
+ finally
+ {
+ lock.unlock();
+ }
}
}
projects / demos / kafka / training / blobdiff