juplo.de Git - demos/kafka/training/blob - src/main/java/de/juplo/kafka/EndlessConsumer.java

   1 package de.juplo.kafka;
   2
   3 import lombok.extern.slf4j.Slf4j;
   4 import org.apache.kafka.clients.consumer.ConsumerRecord;
   5 import org.apache.kafka.clients.consumer.ConsumerRecords;
   6 import org.apache.kafka.clients.consumer.KafkaConsumer;
   7 import org.apache.kafka.common.errors.WakeupException;
   8 import org.apache.kafka.common.serialization.StringDeserializer;
   9
  10 import javax.annotation.PreDestroy;
  11 import java.time.Duration;
  12 import java.util.Arrays;
  13 import java.util.Properties;
  14 import java.util.concurrent.ExecutionException;
  15 import java.util.concurrent.ExecutorService;
  16 import java.util.concurrent.Future;
  17 import java.util.concurrent.atomic.AtomicBoolean;
  18
  19
  20 @Slf4j
  21 public class EndlessConsumer implements Runnable
  22 {
  23   private final ExecutorService executor;
  24   private final String bootstrapServer;
  25   private final String groupId;
  26   private final String id;
  27   private final String topic;
  28
  29   private AtomicBoolean running = new AtomicBoolean();
  30   private long consumed = 0;
  31   private KafkaConsumer<String, String> consumer = null;
  32   private Future<?> future = null;
  33
  34   public EndlessConsumer(
  35       ExecutorService executor,
  36       String bootstrapServer,
  37       String groupId,
  38       String clientId,
  39       String topic)
  40   {
  41     this.executor = executor;
  42     this.bootstrapServer = bootstrapServer;
  43     this.groupId = groupId;
  44     this.id = clientId;
  45     this.topic = topic;
  46   }
  47
  48   @Override
  49   public void run()
  50   {
  51     Properties props = new Properties();
  52     props.put("bootstrap.servers", bootstrapServer);
  53     props.put("group.id", groupId);
  54     props.put("client.id", id);
  55     props.put("auto.offset.reset", "earliest");
  56     props.put("key.deserializer", StringDeserializer.class.getName());
  57     props.put("value.deserializer", StringDeserializer.class.getName());
  58
  59     this.consumer = new KafkaConsumer<>(props);
  60
  61     try
  62     {
  63       log.info("{} - Subscribing to topic {}", id, topic);
  64       consumer.subscribe(Arrays.asList(topic));
  65
  66       while (true)
  67       {
  68         ConsumerRecords<String, String> records =
  69             consumer.poll(Duration.ofSeconds(1));
  70
  71         // Do something with the data...
  72         log.info("{} - Received {} messages", id, records.count());
  73         for (ConsumerRecord<String, String> record : records)
  74         {
  75           consumed++;
  76           log.info(
  77               "{} - {}: {}/{} - {}={}",
  78               id,
  79               record.offset(),
  80               record.topic(),
  81               record.partition(),
  82               record.key(),
  83               record.value()
  84           );
  85         }
  86       }
  87     }
  88     catch(WakeupException e)
  89     {
  90       log.info("{} - RIIING!", id);
  91     }
  92     catch(Exception e)
  93     {
  94       log.error("{} - Unexpected error: {}", id, e.toString());
  95       running.set(false); // Mark the instance as not running
  96     }
  97     finally
  98     {
  99       log.info("{} - Closing the KafkaConsumer", id);
 100       consumer.close();
 101       log.info("{} - Consumer-Thread exiting", id);
 102     }
 103   }
 104
 105
 106   public synchronized void start()
 107   {
 108     boolean stateChanged = running.compareAndSet(false, true);
 109     if (!stateChanged)
 110       throw new RuntimeException("Consumer instance " + id + " is already running!");
 111
 112     log.info("{} - Starting - consumed {} messages before", id, consumed);
 113     future = executor.submit(this);
 114   }
 115
 116   public synchronized void stop() throws ExecutionException, InterruptedException
 117   {
 118     boolean stateChanged = running.compareAndSet(true, false);
 119     if (!stateChanged)
 120       throw new RuntimeException("Consumer instance " + id + " is not running!");
 121
 122     log.info("{} - Stopping", id);
 123     consumer.wakeup();
 124     future.get();
 125     log.info("{} - Stopped - consumed {} messages so far", id, consumed);
 126   }
 127
 128   @PreDestroy
 129   public void destroy() throws ExecutionException, InterruptedException
 130   {
 131     log.info("{} - Destroy!", id);
 132     try
 133     {
 134       stop();
 135     }
 136     catch (IllegalStateException e)
 137     {
 138       log.info("{} - Was already stopped", id);
 139     }
 140     finally
 141     {
 142       log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
 143     }
 144   }
 145 }