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

   1 package de.juplo.kafka;
   2
   3 import lombok.RequiredArgsConstructor;
   4 import lombok.extern.slf4j.Slf4j;
   5 import org.apache.kafka.clients.consumer.*;
   6 import org.apache.kafka.common.TopicPartition;
   7 import org.apache.kafka.common.errors.RecordDeserializationException;
   8 import org.apache.kafka.common.errors.WakeupException;
   9
  10 import javax.annotation.PreDestroy;
  11 import java.time.Duration;
  12 import java.util.*;
  13 import java.util.concurrent.ExecutionException;
  14 import java.util.concurrent.ExecutorService;
  15 import java.util.concurrent.locks.Condition;
  16 import java.util.concurrent.locks.Lock;
  17 import java.util.concurrent.locks.ReentrantLock;
  18
  19
  20 @Slf4j
  21 @RequiredArgsConstructor
  22 public class EndlessConsumer<K, V> implements Runnable
  23 {
  24   private final ExecutorService executor;
  25   private final String id;
  26   private final String topic;
  27   private final Consumer<K, V> consumer;
  28   private final ConsumerRebalanceListener rebalanceListener;
  29   private final RecordHandler<K, V> recordHandler;
  30
  31   private final Lock lock = new ReentrantLock();
  32   private final Condition condition = lock.newCondition();
  33   private boolean running = false;
  34   private Exception exception;
  35   private long consumed = 0;
  36
  37
  38
  39   @Override
  40   public void run()
  41   {
  42     try
  43     {
  44       log.info("{} - Subscribing to topic {}", id, topic);
  45       consumer.subscribe(Arrays.asList(topic), rebalanceListener);
  46
  47       while (true)
  48       {
  49         ConsumerRecords<K, V> records =
  50             consumer.poll(Duration.ofSeconds(1));
  51
  52         // Do something with the data...
  53         log.info("{} - Received {} messages", id, records.count());
  54         for (ConsumerRecord<K, V> record : records)
  55         {
  56           log.info(
  57               "{} - {}: {}/{} - {}={}",
  58               id,
  59               record.offset(),
  60               record.topic(),
  61               record.partition(),
  62               record.key(),
  63               record.value()
  64           );
  65
  66           recordHandler.accept(record);
  67
  68           consumed++;
  69         }
  70       }
  71     }
  72     catch(WakeupException e)
  73     {
  74       log.info("{} - RIIING! Request to stop consumption.", id);
  75       shutdown();
  76     }
  77     catch(RecordDeserializationException e)
  78     {
  79       TopicPartition tp = e.topicPartition();
  80       long offset = e.offset();
  81       log.error(
  82           "{} - Could not deserialize  message on topic {} with offset={}: {}",
  83           id,
  84           tp,
  85           offset,
  86           e.getCause().toString());
  87
  88       shutdown(e);
  89     }
  90     catch(Exception e)
  91     {
  92       log.error("{} - Unexpected error: {}", id, e.toString(), e);
  93       shutdown(e);
  94     }
  95     finally
  96     {
  97       log.info("{} - Consumer-Thread exiting", id);
  98     }
  99   }
 100
 101   private void shutdown()
 102   {
 103     shutdown(null);
 104   }
 105
 106   private void shutdown(Exception e)
 107   {
 108     lock.lock();
 109     try
 110     {
 111       try
 112       {
 113         log.info("{} - Unsubscribing from topic {}", id, topic);
 114         consumer.unsubscribe();
 115       }
 116       catch (Exception ue)
 117       {
 118         log.error(
 119             "{} - Error while unsubscribing from topic {}: {}",
 120             id,
 121             topic,
 122             ue.toString());
 123       }
 124       finally
 125       {
 126         running = false;
 127         exception = e;
 128         condition.signal();
 129       }
 130     }
 131     finally
 132     {
 133       lock.unlock();
 134     }
 135   }
 136
 137   public void start()
 138   {
 139     lock.lock();
 140     try
 141     {
 142       if (running)
 143         throw new IllegalStateException("Consumer instance " + id + " is already running!");
 144
 145       log.info("{} - Starting - consumed {} messages before", id, consumed);
 146       running = true;
 147       exception = null;
 148       executor.submit(this);
 149     }
 150     finally
 151     {
 152       lock.unlock();
 153     }
 154   }
 155
 156   public synchronized void stop() throws InterruptedException
 157   {
 158     lock.lock();
 159     try
 160     {
 161       if (!running)
 162         throw new IllegalStateException("Consumer instance " + id + " is not running!");
 163
 164       log.info("{} - Stopping", id);
 165       consumer.wakeup();
 166       condition.await();
 167       log.info("{} - Stopped - consumed {} messages so far", id, consumed);
 168     }
 169     finally
 170     {
 171       lock.unlock();
 172     }
 173   }
 174
 175   @PreDestroy
 176   public void destroy() throws ExecutionException, InterruptedException
 177   {
 178     log.info("{} - Destroy!", id);
 179     log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
 180   }
 181
 182   public boolean running()
 183   {
 184     lock.lock();
 185     try
 186     {
 187       return running;
 188     }
 189     finally
 190     {
 191       lock.unlock();
 192     }
 193   }
 194
 195   public Optional<Exception> exitStatus()
 196   {
 197     lock.lock();
 198     try
 199     {
 200       if (running)
 201         throw new IllegalStateException("No exit-status available: Consumer instance " + id + " is running!");
 202
 203       return Optional.ofNullable(exception);
 204     }
 205     finally
 206     {
 207       lock.unlock();
 208     }
 209   }
 210 }