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.ConsumerRecord;
   5 import org.apache.kafka.clients.consumer.ConsumerRecords;
   6 import org.apache.kafka.clients.consumer.KafkaConsumer;
   7 import org.apache.kafka.common.errors.WakeupException;
   8 import org.apache.kafka.common.serialization.StringDeserializer;
   9
  10 import javax.annotation.PreDestroy;
  11 import java.time.Duration;
  12 import java.util.Arrays;
  13 import java.util.Properties;
  14 import java.util.concurrent.ExecutionException;
  15 import java.util.concurrent.ExecutorService;
  16 import java.util.concurrent.Future;
  17 import java.util.concurrent.atomic.AtomicBoolean;
  18
  19
  20 @Slf4j
  21 public class EndlessConsumer implements Runnable
  22 {
  23   private final ExecutorService executor;
  24   private final String bootstrapServer;
  25   private final String groupId;
  26   private final String id;
  27   private final String topic;
  28   private final String autoOffsetReset;
  29
  30   private AtomicBoolean running = new AtomicBoolean();
  31   private long consumed = 0;
  32   private KafkaConsumer<String, String> consumer = null;
  33   private Future<?> future = null;
  34
  35   public EndlessConsumer(
  36       ExecutorService executor,
  37       String bootstrapServer,
  38       String groupId,
  39       String clientId,
  40       String topic,
  41       String autoOffsetReset)
  42   {
  43     this.executor = executor;
  44     this.bootstrapServer = bootstrapServer;
  45     this.groupId = groupId;
  46     this.id = clientId;
  47     this.topic = topic;
  48     this.autoOffsetReset = autoOffsetReset;
  49   }
  50
  51   @Override
  52   public void run()
  53   {
  54     try
  55     {
  56       Properties props = new Properties();
  57       props.put("bootstrap.servers", bootstrapServer);
  58       props.put("group.id", groupId);
  59       props.put("client.id", id);
  60       props.put("auto.offset.reset", autoOffsetReset);
  61       props.put("key.deserializer", StringDeserializer.class.getName());
  62       props.put("value.deserializer", StringDeserializer.class.getName());
  63
  64       this.consumer = new KafkaConsumer<>(props);
  65
  66       log.info("{} - Subscribing to topic {}", id, topic);
  67       consumer.subscribe(Arrays.asList(topic));
  68
  69       while (true)
  70       {
  71         ConsumerRecords<String, String> records =
  72             consumer.poll(Duration.ofSeconds(1));
  73
  74         // Do something with the data...
  75         log.info("{} - Received {} messages", id, records.count());
  76         for (ConsumerRecord<String, String> record : records)
  77         {
  78           consumed++;
  79           log.info(
  80               "{} - {}: {}/{} - {}={}",
  81               id,
  82               record.offset(),
  83               record.topic(),
  84               record.partition(),
  85               record.key(),
  86               record.value()
  87           );
  88         }
  89       }
  90     }
  91     catch(WakeupException e)
  92     {
  93       log.info("{} - RIIING!", id);
  94     }
  95     catch(Exception e)
  96     {
  97       log.error("{} - Unexpected error: {}", id, e.toString(), e);
  98       running.set(false); // Mark the instance as not running
  99     }
 100     finally
 101     {
 102       log.info("{} - Closing the KafkaConsumer", id);
 103       consumer.close();
 104       log.info("{} - Consumer-Thread exiting", id);
 105     }
 106   }
 107
 108
 109   public synchronized void start()
 110   {
 111     boolean stateChanged = running.compareAndSet(false, true);
 112     if (!stateChanged)
 113       throw new RuntimeException("Consumer instance " + id + " is already running!");
 114
 115     log.info("{} - Starting - consumed {} messages before", id, consumed);
 116     future = executor.submit(this);
 117   }
 118
 119   public synchronized void stop() throws ExecutionException, InterruptedException
 120   {
 121     boolean stateChanged = running.compareAndSet(true, false);
 122     if (!stateChanged)
 123       throw new RuntimeException("Consumer instance " + id + " is not running!");
 124
 125     log.info("{} - Stopping", id);
 126     consumer.wakeup();
 127     future.get();
 128     log.info("{} - Stopped - consumed {} messages so far", id, consumed);
 129   }
 130
 131   @PreDestroy
 132   public void destroy() throws ExecutionException, InterruptedException
 133   {
 134     log.info("{} - Destroy!", id);
 135     try
 136     {
 137       stop();
 138     }
 139     catch (IllegalStateException e)
 140     {
 141       log.info("{} - Was already stopped", id);
 142     }
 143     finally
 144     {
 145       log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
 146     }
 147   }
 148 }