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 - commiting current offsets!", id);
  75       consumer.commitSync();
  76       shutdown();
  77     }
  78     catch(RecordDeserializationException e)
  79     {
  80       TopicPartition tp = e.topicPartition();
  81       long offset = e.offset();
  82       log.error(
  83           "{} - Could not deserialize  message on topic {} with offset={}: {}",
  84           id,
  85           tp,
  86           offset,
  87           e.getCause().toString());
  88
  89       consumer.commitSync();
  90       shutdown(e);
  91     }
  92     catch(Exception e)
  93     {
  94       log.error("{} - Unexpected error: {}", id, e.toString(), e);
  95       shutdown(e);
  96     }
  97     finally
  98     {
  99       log.info("{} - Consumer-Thread exiting", id);
 100     }
 101   }
 102
 103   private void shutdown()
 104   {
 105     shutdown(null);
 106   }
 107
 108   private void shutdown(Exception e)
 109   {
 110     lock.lock();
 111     try
 112     {
 113       try
 114       {
 115         log.info("{} - Unsubscribing from topic {}", id, topic);
 116         consumer.unsubscribe();
 117       }
 118       catch (Exception ue)
 119       {
 120         log.error(
 121             "{} - Error while unsubscribing from topic {}: {}",
 122             id,
 123             topic,
 124             ue.toString());
 125       }
 126       finally
 127       {
 128         running = false;
 129         exception = e;
 130         condition.signal();
 131       }
 132     }
 133     finally
 134     {
 135       lock.unlock();
 136     }
 137   }
 138
 139   public void start()
 140   {
 141     lock.lock();
 142     try
 143     {
 144       if (running)
 145         throw new IllegalStateException("Consumer instance " + id + " is already running!");
 146
 147       log.info("{} - Starting - consumed {} messages before", id, consumed);
 148       running = true;
 149       exception = null;
 150       executor.submit(this);
 151     }
 152     finally
 153     {
 154       lock.unlock();
 155     }
 156   }
 157
 158   public synchronized void stop() throws InterruptedException
 159   {
 160     lock.lock();
 161     try
 162     {
 163       if (!running)
 164         throw new IllegalStateException("Consumer instance " + id + " is not running!");
 165
 166       log.info("{} - Stopping", id);
 167       consumer.wakeup();
 168       condition.await();
 169       log.info("{} - Stopped - consumed {} messages so far", id, consumed);
 170     }
 171     finally
 172     {
 173       lock.unlock();
 174     }
 175   }
 176
 177   @PreDestroy
 178   public void destroy() throws ExecutionException, InterruptedException
 179   {
 180     log.info("{} - Destroy!", id);
 181     log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
 182   }
 183
 184   public boolean running()
 185   {
 186     lock.lock();
 187     try
 188     {
 189       return running;
 190     }
 191     finally
 192     {
 193       lock.unlock();
 194     }
 195   }
 196
 197   public Optional<Exception> exitStatus()
 198   {
 199     lock.lock();
 200     try
 201     {
 202       if (running)
 203         throw new IllegalStateException("No exit-status available: Consumer instance " + id + " is running!");
 204
 205       return Optional.ofNullable(exception);
 206     }
 207     finally
 208     {
 209       lock.unlock();
 210     }
 211   }
 212 }