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 ->
  78           {
  79             log.info("{} - removing partition: {}", id, tp);
  80             Map<String, Integer> removed = seen.remove(tp.partition());
  81             for (String key : removed.keySet())
  82             {
  83               log.info(
  84                   "{} - Seen {} messages for partition={}|key={}",
  85                   id,
  86                   removed.get(key),
  87                   tp.partition(),
  88                   key);
  89             }
  90           });
  91         }
  92
  93         @Override
  94         public void onPartitionsAssigned(Collection<TopicPartition> partitions)
  95         {
  96           partitions.forEach(tp ->
  97           {
  98             log.info("{} - adding partition: {}", id, tp);
  99             seen.put(tp.partition(), new HashMap<>());
 100           });
 101         }
 102       });
 103
 104       while (true)
 105       {
 106         ConsumerRecords<String, String> records =
 107             consumer.poll(Duration.ofSeconds(1));
 108
 109         // Do something with the data...
 110         log.info("{} - Received {} messages", id, records.count());
 111         for (ConsumerRecord<String, String> record : records)
 112         {
 113           consumed++;
 114           log.info(
 115               "{} - {}: {}/{} - {}={}",
 116               id,
 117               record.offset(),
 118               record.topic(),
 119               record.partition(),
 120               record.key(),
 121               record.value()
 122           );
 123
 124           Integer partition = record.partition();
 125           String key = record.key() == null ? "NULL" : record.key();
 126           Map<String, Integer> byKey = seen.get(partition);
 127
 128           if (!byKey.containsKey(key))
 129             byKey.put(key, 0);
 130
 131           int seenByKey = byKey.get(key);
 132           seenByKey++;
 133           byKey.put(key, seenByKey);
 134         }
 135       }
 136     }
 137     catch(WakeupException e)
 138     {
 139       log.info("{} - RIIING!", id);
 140     }
 141     catch(Exception e)
 142     {
 143       log.error("{} - Unexpected error: {}", id, e.toString(), e);
 144       running.set(false); // Mark the instance as not running
 145     }
 146     finally
 147     {
 148       log.info("{} - Closing the KafkaConsumer", id);
 149       consumer.close();
 150       log.info("{} - Consumer-Thread exiting", id);
 151     }
 152   }
 153
 154   public Map<Integer, Map<String, Integer>> getSeen()
 155   {
 156     return seen;
 157   }
 158
 159   public synchronized void start()
 160   {
 161     boolean stateChanged = running.compareAndSet(false, true);
 162     if (!stateChanged)
 163       throw new RuntimeException("Consumer instance " + id + " is already running!");
 164
 165     log.info("{} - Starting - consumed {} messages before", id, consumed);
 166     future = executor.submit(this);
 167   }
 168
 169   public synchronized void stop() throws ExecutionException, InterruptedException
 170   {
 171     boolean stateChanged = running.compareAndSet(true, false);
 172     if (!stateChanged)
 173       throw new RuntimeException("Consumer instance " + id + " is not running!");
 174
 175     log.info("{} - Stopping", id);
 176     consumer.wakeup();
 177     future.get();
 178     log.info("{} - Stopped - consumed {} messages so far", id, consumed);
 179   }
 180
 181   @PreDestroy
 182   public void destroy() throws ExecutionException, InterruptedException
 183   {
 184     log.info("{} - Destroy!", id);
 185     try
 186     {
 187       stop();
 188     }
 189     catch (IllegalStateException e)
 190     {
 191       log.info("{} - Was already stopped", id);
 192     }
 193     finally
 194     {
 195       log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
 196     }
 197   }
 198 }