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 RecordHandler<K, V> handler;
  29
  30   private final Lock lock = new ReentrantLock();
  31   private final Condition condition = lock.newCondition();
  32   private boolean running = false;
  33   private Exception exception;
  34   private long consumed = 0;
  35
  36
  37
  38   @Override
  39   public void run()
  40   {
  41     try
  42     {
  43       log.info("{} - Subscribing to topic {}", id, topic);
  44       consumer.subscribe(Arrays.asList(topic));
  45
  46       while (true)
  47       {
  48         ConsumerRecords<K, V> records =
  49             consumer.poll(Duration.ofSeconds(1));
  50
  51         // Do something with the data...
  52         log.info("{} - Received {} messages", id, records.count());
  53         for (ConsumerRecord<K, V> record : records)
  54         {
  55           log.info(
  56               "{} - {}: {}/{} - {}={}",
  57               id,
  58               record.offset(),
  59               record.topic(),
  60               record.partition(),
  61               record.key(),
  62               record.value()
  63           );
  64
  65           handler.accept(record);
  66
  67           consumed++;
  68         }
  69       }
  70     }
  71     catch(WakeupException e)
  72     {
  73       log.info("{} - RIIING! Request to stop consumption - commiting current offsets!", id);
  74       consumer.commitSync();
  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       consumer.commitSync();
  89       shutdown(e);
  90     }
  91     catch(Exception e)
  92     {
  93       log.error("{} - Unexpected error: {}", id, e.toString(), e);
  94       shutdown(e);
  95     }
  96     finally
  97     {
  98       log.info("{} - Consumer-Thread exiting", id);
  99     }
 100   }
 101
 102   private void shutdown()
 103   {
 104     shutdown(null);
 105   }
 106
 107   private void shutdown(Exception e)
 108   {
 109     lock.lock();
 110     try
 111     {
 112       try
 113       {
 114         log.info("{} - Unsubscribing from topic {}", id, topic);
 115         consumer.unsubscribe();
 116       }
 117       catch (Exception ue)
 118       {
 119         log.error(
 120             "{} - Error while unsubscribing from topic {}: {}",
 121             id,
 122             topic,
 123             ue.toString());
 124       }
 125       finally
 126       {
 127         running = false;
 128         exception = e;
 129         condition.signal();
 130       }
 131     }
 132     finally
 133     {
 134       lock.unlock();
 135     }
 136   }
 137
 138   public void start()
 139   {
 140     lock.lock();
 141     try
 142     {
 143       if (running)
 144         throw new IllegalStateException("Consumer instance " + id + " is already running!");
 145
 146       log.info("{} - Starting - consumed {} messages before", id, consumed);
 147       running = true;
 148       exception = null;
 149       executor.submit(this);
 150     }
 151     finally
 152     {
 153       lock.unlock();
 154     }
 155   }
 156
 157   public synchronized void stop() throws InterruptedException
 158   {
 159     lock.lock();
 160     try
 161     {
 162       if (!running)
 163         throw new IllegalStateException("Consumer instance " + id + " is not running!");
 164
 165       log.info("{} - Stopping", id);
 166       consumer.wakeup();
 167       condition.await();
 168       log.info("{} - Stopped - consumed {} messages so far", id, consumed);
 169     }
 170     finally
 171     {
 172       lock.unlock();
 173     }
 174   }
 175
 176   @PreDestroy
 177   public void destroy() throws ExecutionException, InterruptedException
 178   {
 179     log.info("{} - Destroy!", id);
 180     log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
 181   }
 182
 183   public boolean running()
 184   {
 185     lock.lock();
 186     try
 187     {
 188       return running;
 189     }
 190     finally
 191     {
 192       lock.unlock();
 193     }
 194   }
 195
 196   public Optional<Exception> exitStatus()
 197   {
 198     lock.lock();
 199     try
 200     {
 201       if (running)
 202         throw new IllegalStateException("No exit-status available: Consumer instance " + id + " is running!");
 203
 204       return Optional.ofNullable(exception);
 205     }
 206     finally
 207     {
 208       lock.unlock();
 209     }
 210   }
 211 }