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.locks.Condition;
  17 import java.util.concurrent.locks.Lock;
  18 import java.util.concurrent.locks.ReentrantLock;
  19
  20
  21 @Slf4j
  22 public class EndlessConsumer implements Runnable
  23 {
  24   private final ExecutorService executor;
  25   private final String bootstrapServer;
  26   private final String groupId;
  27   private final String id;
  28   private final String topic;
  29   private final String autoOffsetReset;
  30
  31   private final Lock lock = new ReentrantLock();
  32   private final Condition condition = lock.newCondition();
  33   private boolean running = false;
  34   private long consumed = 0;
  35   private KafkaConsumer<String, String> consumer = null;
  36
  37
  38   public EndlessConsumer(
  39       ExecutorService executor,
  40       String bootstrapServer,
  41       String groupId,
  42       String clientId,
  43       String topic,
  44       String autoOffsetReset)
  45   {
  46     this.executor = executor;
  47     this.bootstrapServer = bootstrapServer;
  48     this.groupId = groupId;
  49     this.id = clientId;
  50     this.topic = topic;
  51     this.autoOffsetReset = autoOffsetReset;
  52   }
  53
  54   @Override
  55   public void run()
  56   {
  57     try
  58     {
  59       Properties props = new Properties();
  60       props.put("bootstrap.servers", bootstrapServer);
  61       props.put("group.id", groupId);
  62       props.put("client.id", id);
  63       props.put("auto.offset.reset", autoOffsetReset);
  64       props.put("key.deserializer", StringDeserializer.class.getName());
  65       props.put("value.deserializer", StringDeserializer.class.getName());
  66
  67       this.consumer = new KafkaConsumer<>(props);
  68
  69       log.info("{} - Subscribing to topic {}", id, topic);
  70       consumer.subscribe(Arrays.asList(topic));
  71
  72       while (true)
  73       {
  74         ConsumerRecords<String, String> records =
  75             consumer.poll(Duration.ofSeconds(1));
  76
  77         // Do something with the data...
  78         log.info("{} - Received {} messages", id, records.count());
  79         for (ConsumerRecord<String, String> record : records)
  80         {
  81           consumed++;
  82           log.info(
  83               "{} - {}: {}/{} - {}={}",
  84               id,
  85               record.offset(),
  86               record.topic(),
  87               record.partition(),
  88               record.key(),
  89               record.value()
  90           );
  91         }
  92       }
  93     }
  94     catch(WakeupException e)
  95     {
  96       log.info("{} - RIIING!", id);
  97       shutdown();
  98     }
  99     catch(Exception e)
 100     {
 101       log.error("{} - Unexpected error: {}", id, e.toString(), e);
 102       shutdown();
 103     }
 104     finally
 105     {
 106       log.info("{} - Closing the KafkaConsumer", id);
 107       consumer.close();
 108       log.info("{} - Consumer-Thread exiting", id);
 109     }
 110   }
 111
 112   private void shutdown()
 113   {
 114     lock.lock();
 115     try
 116     {
 117       running = false;
 118       condition.signal();
 119     }
 120     finally
 121     {
 122       lock.unlock();
 123     }
 124   }
 125
 126   public void start()
 127   {
 128     lock.lock();
 129     try
 130     {
 131       if (running)
 132         throw new IllegalStateException("Consumer instance " + id + " is already running!");
 133
 134       log.info("{} - Starting - consumed {} messages before", id, consumed);
 135       running = true;
 136       executor.submit(this);
 137     }
 138     finally
 139     {
 140       lock.unlock();
 141     }
 142   }
 143
 144   public synchronized void stop() throws ExecutionException, InterruptedException
 145   {
 146     lock.lock();
 147     try
 148     {
 149       if (!running)
 150         throw new IllegalStateException("Consumer instance " + id + " is not running!");
 151
 152       log.info("{} - Stopping", id);
 153       consumer.wakeup();
 154       condition.await();
 155       log.info("{} - Stopped - consumed {} messages so far", id, consumed);
 156     }
 157     finally
 158     {
 159       lock.unlock();
 160     }
 161   }
 162
 163   @PreDestroy
 164   public void destroy() throws ExecutionException, InterruptedException
 165   {
 166     log.info("{} - Destroy!", id);
 167     try
 168     {
 169       stop();
 170     }
 171     catch (IllegalStateException e)
 172     {
 173       log.info("{} - Was already stopped", id);
 174     }
 175     catch (Exception e)
 176     {
 177       log.error("{} - Unexpected exception while trying to stop the consumer", id, e);
 178     }
 179     finally
 180     {
 181       log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
 182     }
 183   }
 184 }