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.Optional;
  14 import java.util.Properties;
  15 import java.util.concurrent.ExecutionException;
  16 import java.util.concurrent.ExecutorService;
  17 import java.util.concurrent.locks.Condition;
  18 import java.util.concurrent.locks.Lock;
  19 import java.util.concurrent.locks.ReentrantLock;
  20
  21
  22 @Slf4j
  23 public class EndlessConsumer implements Runnable
  24 {
  25   private final ExecutorService executor;
  26   private final String bootstrapServer;
  27   private final String groupId;
  28   private final String id;
  29   private final String topic;
  30   private final String autoOffsetReset;
  31
  32   private final Lock lock = new ReentrantLock();
  33   private final Condition condition = lock.newCondition();
  34   private boolean running = false;
  35   private Exception exception;
  36   private long consumed = 0;
  37   private KafkaConsumer<String, String> consumer = null;
  38
  39
  40   public EndlessConsumer(
  41       ExecutorService executor,
  42       String bootstrapServer,
  43       String groupId,
  44       String clientId,
  45       String topic,
  46       String autoOffsetReset)
  47   {
  48     this.executor = executor;
  49     this.bootstrapServer = bootstrapServer;
  50     this.groupId = groupId;
  51     this.id = clientId;
  52     this.topic = topic;
  53     this.autoOffsetReset = autoOffsetReset;
  54   }
  55
  56   @Override
  57   public void run()
  58   {
  59     try
  60     {
  61       Properties props = new Properties();
  62       props.put("bootstrap.servers", bootstrapServer);
  63       props.put("group.id", groupId);
  64       props.put("client.id", id);
  65       props.put("auto.offset.reset", autoOffsetReset);
  66       props.put("key.deserializer", StringDeserializer.class.getName());
  67       props.put("value.deserializer", StringDeserializer.class.getName());
  68
  69       this.consumer = new KafkaConsumer<>(props);
  70
  71       log.info("{} - Subscribing to topic {}", id, topic);
  72       consumer.subscribe(Arrays.asList(topic));
  73
  74       while (true)
  75       {
  76         ConsumerRecords<String, String> records =
  77             consumer.poll(Duration.ofSeconds(1));
  78
  79         // Do something with the data...
  80         log.info("{} - Received {} messages", id, records.count());
  81         for (ConsumerRecord<String, String> record : records)
  82         {
  83           consumed++;
  84           log.info(
  85               "{} - {}: {}/{} - {}={}",
  86               id,
  87               record.offset(),
  88               record.topic(),
  89               record.partition(),
  90               record.key(),
  91               record.value()
  92           );
  93         }
  94       }
  95     }
  96     catch(WakeupException e)
  97     {
  98       log.info("{} - RIIING!", id);
  99       shutdown();
 100     }
 101     catch(Exception e)
 102     {
 103       log.error("{} - Unexpected error: {}", id, e.toString(), e);
 104       shutdown(e);
 105     }
 106     finally
 107     {
 108       log.info("{} - Closing the KafkaConsumer", id);
 109       consumer.close();
 110       log.info("{} - Consumer-Thread exiting", id);
 111     }
 112   }
 113
 114   private void shutdown()
 115   {
 116     shutdown(null);
 117   }
 118
 119   private void shutdown(Exception e)
 120   {
 121     lock.lock();
 122     try
 123     {
 124       running = false;
 125       exception = e;
 126       condition.signal();
 127     }
 128     finally
 129     {
 130       lock.unlock();
 131     }
 132   }
 133
 134   public void start()
 135   {
 136     lock.lock();
 137     try
 138     {
 139       if (running)
 140         throw new IllegalStateException("Consumer instance " + id + " is already running!");
 141
 142       log.info("{} - Starting - consumed {} messages before", id, consumed);
 143       running = true;
 144       exception = null;
 145       executor.submit(this);
 146     }
 147     finally
 148     {
 149       lock.unlock();
 150     }
 151   }
 152
 153   public synchronized void stop() throws ExecutionException, InterruptedException
 154   {
 155     lock.lock();
 156     try
 157     {
 158       if (!running)
 159         throw new IllegalStateException("Consumer instance " + id + " is not running!");
 160
 161       log.info("{} - Stopping", id);
 162       consumer.wakeup();
 163       condition.await();
 164       log.info("{} - Stopped - consumed {} messages so far", id, consumed);
 165     }
 166     finally
 167     {
 168       lock.unlock();
 169     }
 170   }
 171
 172   @PreDestroy
 173   public void destroy() throws ExecutionException, InterruptedException
 174   {
 175     log.info("{} - Destroy!", id);
 176     try
 177     {
 178       stop();
 179     }
 180     catch (IllegalStateException e)
 181     {
 182       log.info("{} - Was already stopped", id);
 183     }
 184     catch (Exception e)
 185     {
 186       log.error("{} - Unexpected exception while trying to stop the consumer", id, e);
 187     }
 188     finally
 189     {
 190       log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
 191     }
 192   }
 193
 194   public boolean running()
 195   {
 196     lock.lock();
 197     try
 198     {
 199       return running;
 200     }
 201     finally
 202     {
 203       lock.unlock();
 204     }
 205   }
 206
 207   public Optional<Exception> exitStatus()
 208   {
 209     lock.lock();
 210     try
 211     {
 212       if (running)
 213         throw new IllegalStateException("No exit-status available: Consumer instance " + id + " is running!");
 214
 215       return Optional.ofNullable(exception);
 216     }
 217     finally
 218     {
 219       lock.unlock();
 220     }
 221   }
 222 }