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.Future;
  18 import java.util.concurrent.atomic.AtomicBoolean;
  19
  20
  21 @Slf4j
  22 public class EndlessConsumer implements Runnable
  23 {
  24   private final ExecutorService executor;
  25   private final String bootstrapServer;
  26   private final String groupId;
  27   private final String id;
  28   private final String topic;
  29   private final String autoOffsetReset;
  30
  31   private AtomicBoolean running = new AtomicBoolean();
  32   private long consumed = 0;
  33   private KafkaConsumer<String, String> consumer = null;
  34   private Future<?> future = null;
  35
  36   private final Map<Integer, Map<String, Integer>> seen = new HashMap<>();
  37
  38
  39   public EndlessConsumer(
  40       ExecutorService executor,
  41       String bootstrapServer,
  42       String groupId,
  43       String clientId,
  44       String topic,
  45       String autoOffsetReset)
  46   {
  47     this.executor = executor;
  48     this.bootstrapServer = bootstrapServer;
  49     this.groupId = groupId;
  50     this.id = clientId;
  51     this.topic = topic;
  52     this.autoOffsetReset = autoOffsetReset;
  53   }
  54
  55   @Override
  56   public void run()
  57   {
  58     try
  59     {
  60       Properties props = new Properties();
  61       props.put("bootstrap.servers", bootstrapServer);
  62       props.put("group.id", groupId);
  63       props.put("client.id", id);
  64       props.put("auto.offset.reset", autoOffsetReset);
  65       props.put("metadata.max.age.ms", "1000");
  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), new ConsumerRebalanceListener()
  73       {
  74         @Override
  75         public void onPartitionsRevoked(Collection<TopicPartition> partitions)
  76         {
  77           partitions.forEach(tp -> seen.remove(tp.partition()));
  78         }
  79
  80         @Override
  81         public void onPartitionsAssigned(Collection<TopicPartition> partitions)
  82         {
  83           partitions.forEach(tp -> seen.put(tp.partition(), new HashMap<>()));
  84         }
  85       });
  86
  87       while (true)
  88       {
  89         ConsumerRecords<String, String> records =
  90             consumer.poll(Duration.ofSeconds(1));
  91
  92         // Do something with the data...
  93         log.info("{} - Received {} messages", id, records.count());
  94         for (ConsumerRecord<String, String> record : records)
  95         {
  96           consumed++;
  97           log.info(
  98               "{} - {}: {}/{} - {}={}",
  99               id,
 100               record.offset(),
 101               record.topic(),
 102               record.partition(),
 103               record.key(),
 104               record.value()
 105           );
 106
 107           Integer partition = record.partition();
 108           String key = record.key() == null ? "NULL" : record.key();
 109           Map<String, Integer> byKey = seen.get(partition);
 110
 111           if (!byKey.containsKey(key))
 112             byKey.put(key, 0);
 113
 114           int seenByKey = byKey.get(key);
 115           seenByKey++;
 116           byKey.put(key, seenByKey);
 117         }
 118       }
 119     }
 120     catch(WakeupException e)
 121     {
 122       log.info("{} - RIIING!", id);
 123     }
 124     catch(Exception e)
 125     {
 126       log.error("{} - Unexpected error: {}", id, e.toString(), e);
 127       running.set(false); // Mark the instance as not running
 128     }
 129     finally
 130     {
 131       log.info("{} - Closing the KafkaConsumer", id);
 132       consumer.close();
 133
 134       for (Integer partition : seen.keySet())
 135       {
 136         Map<String, Integer> byKey = seen.get(partition);
 137         for (String key : byKey.keySet())
 138         {
 139           log.info(
 140               "{} - Seen {} messages for partition={}|key={}",
 141               id,
 142               byKey.get(key),
 143               partition,
 144               key);
 145         }
 146       }
 147
 148       log.info("{} - Consumer-Thread exiting", id);
 149     }
 150   }
 151
 152   public Map<Integer, Map<String, Integer>> getSeen()
 153   {
 154     return seen;
 155   }
 156
 157   public synchronized void start()
 158   {
 159     boolean stateChanged = running.compareAndSet(false, true);
 160     if (!stateChanged)
 161       throw new RuntimeException("Consumer instance " + id + " is already running!");
 162
 163     log.info("{} - Starting - consumed {} messages before", id, consumed);
 164     future = executor.submit(this);
 165   }
 166
 167   public synchronized void stop() throws ExecutionException, InterruptedException
 168   {
 169     boolean stateChanged = running.compareAndSet(true, false);
 170     if (!stateChanged)
 171       throw new RuntimeException("Consumer instance " + id + " is not running!");
 172
 173     log.info("{} - Stopping", id);
 174     consumer.wakeup();
 175     future.get();
 176     log.info("{} - Stopped - consumed {} messages so far", id, consumed);
 177   }
 178
 179   @PreDestroy
 180   public void destroy() throws ExecutionException, InterruptedException
 181   {
 182     log.info("{} - Destroy!", id);
 183     try
 184     {
 185       stop();
 186     }
 187     catch (IllegalStateException e)
 188     {
 189       log.info("{} - Was already stopped", id);
 190     }
 191     finally
 192     {
 193       log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
 194     }
 195   }
 196 }