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.ConsumerRebalanceListener;
   5 import org.apache.kafka.clients.consumer.ConsumerRecord;
   6 import org.apache.kafka.clients.consumer.ConsumerRecords;
   7 import org.apache.kafka.clients.consumer.KafkaConsumer;
   8 import org.apache.kafka.common.TopicPartition;
   9 import org.apache.kafka.common.errors.WakeupException;
  10 import org.apache.kafka.common.serialization.StringDeserializer;
  11
  12 import javax.annotation.PreDestroy;
  13 import java.time.Duration;
  14 import java.util.*;
  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 long consumed = 0;
  36   private KafkaConsumer<String, String> consumer = null;
  37
  38
  39   private final Map<Integer, Map<String, Integer>> seen = new HashMap<>();
  40
  41
  42   public EndlessConsumer(
  43       ExecutorService executor,
  44       String bootstrapServer,
  45       String groupId,
  46       String clientId,
  47       String topic,
  48       String autoOffsetReset)
  49   {
  50     this.executor = executor;
  51     this.bootstrapServer = bootstrapServer;
  52     this.groupId = groupId;
  53     this.id = clientId;
  54     this.topic = topic;
  55     this.autoOffsetReset = autoOffsetReset;
  56   }
  57
  58   @Override
  59   public void run()
  60   {
  61     try
  62     {
  63       Properties props = new Properties();
  64       props.put("bootstrap.servers", bootstrapServer);
  65       props.put("group.id", groupId);
  66       props.put("client.id", id);
  67       props.put("auto.offset.reset", autoOffsetReset);
  68       props.put("metadata.max.age.ms", "1000");
  69       props.put("key.deserializer", StringDeserializer.class.getName());
  70       props.put("value.deserializer", StringDeserializer.class.getName());
  71
  72       this.consumer = new KafkaConsumer<>(props);
  73
  74       log.info("{} - Subscribing to topic {}", id, topic);
  75       consumer.subscribe(Arrays.asList(topic), new ConsumerRebalanceListener()
  76       {
  77         @Override
  78         public void onPartitionsRevoked(Collection<TopicPartition> partitions)
  79         {
  80           partitions.forEach(tp ->
  81           {
  82             log.info("{} - removing partition: {}", id, tp);
  83             Map<String, Integer> removed = seen.remove(tp.partition());
  84             for (String key : removed.keySet())
  85             {
  86               log.info(
  87                   "{} - Seen {} messages for partition={}|key={}",
  88                   id,
  89                   removed.get(key),
  90                   tp.partition(),
  91                   key);
  92             }
  93           });
  94         }
  95
  96         @Override
  97         public void onPartitionsAssigned(Collection<TopicPartition> partitions)
  98         {
  99           partitions.forEach(tp ->
 100           {
 101             log.info("{} - adding partition: {}", id, tp);
 102             seen.put(tp.partition(), new HashMap<>());
 103           });
 104         }
 105       });
 106
 107       while (true)
 108       {
 109         ConsumerRecords<String, String> records =
 110             consumer.poll(Duration.ofSeconds(1));
 111
 112         // Do something with the data...
 113         log.info("{} - Received {} messages", id, records.count());
 114         for (ConsumerRecord<String, String> record : records)
 115         {
 116           consumed++;
 117           log.info(
 118               "{} - {}: {}/{} - {}={}",
 119               id,
 120               record.offset(),
 121               record.topic(),
 122               record.partition(),
 123               record.key(),
 124               record.value()
 125           );
 126
 127           Integer partition = record.partition();
 128           String key = record.key() == null ? "NULL" : record.key();
 129           Map<String, Integer> byKey = seen.get(partition);
 130
 131           if (!byKey.containsKey(key))
 132             byKey.put(key, 0);
 133
 134           int seenByKey = byKey.get(key);
 135           seenByKey++;
 136           byKey.put(key, seenByKey);
 137         }
 138       }
 139     }
 140     catch(WakeupException e)
 141     {
 142       log.info("{} - RIIING!", id);
 143       shutdown();
 144     }
 145     catch(Exception e)
 146     {
 147       log.error("{} - Unexpected error: {}", id, e.toString(), e);
 148       shutdown();
 149     }
 150     finally
 151     {
 152       log.info("{} - Closing the KafkaConsumer", id);
 153       consumer.close();
 154       log.info("{} - Consumer-Thread exiting", id);
 155     }
 156   }
 157
 158   private void shutdown()
 159   {
 160     lock.lock();
 161     try
 162     {
 163       running = false;
 164       condition.signal();
 165     }
 166     finally
 167     {
 168       lock.unlock();
 169     }
 170   }
 171
 172   public Map<Integer, Map<String, Integer>> getSeen()
 173   {
 174     return seen;
 175   }
 176
 177   public void start()
 178   {
 179     lock.lock();
 180     try
 181     {
 182       if (running)
 183         throw new IllegalStateException("Consumer instance " + id + " is already running!");
 184
 185       log.info("{} - Starting - consumed {} messages before", id, consumed);
 186       running = true;
 187       executor.submit(this);
 188     }
 189     finally
 190     {
 191       lock.unlock();
 192     }
 193   }
 194
 195   public synchronized void stop() throws ExecutionException, InterruptedException
 196   {
 197     lock.lock();
 198     try
 199     {
 200       if (!running)
 201         throw new IllegalStateException("Consumer instance " + id + " is not running!");
 202
 203       log.info("{} - Stopping", id);
 204       consumer.wakeup();
 205       condition.await();
 206       log.info("{} - Stopped - consumed {} messages so far", id, consumed);
 207     }
 208     finally
 209     {
 210       lock.unlock();
 211     }
 212   }
 213
 214   @PreDestroy
 215   public void destroy() throws ExecutionException, InterruptedException
 216   {
 217     log.info("{} - Destroy!", id);
 218     try
 219     {
 220       stop();
 221     }
 222     catch (IllegalStateException e)
 223     {
 224       log.info("{} - Was already stopped", id);
 225     }
 226     catch (Exception e)
 227     {
 228       log.error("{} - Unexpected exception while trying to stop the consumer", id, e);
 229     }
 230     finally
 231     {
 232       log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
 233     }
 234   }
 235 }