X-Git-Url: https://juplo.de/gitweb/?a=blobdiff_plain;f=src%2Fmain%2Fjava%2Fde%2Fjuplo%2Fkafka%2FEndlessConsumer.java;h=92802b981f5bcf465758c9b257949ad6b104f8b6;hb=1c97cf9d1a93d5cfb6f1123cb45f644238798608;hp=e4d969748e896ff18863cd465b6e8ab9ee91c2be;hpb=95b1d2d6fd83c68aa0db3e426f173921600e44a6;p=demos%2Fkafka%2Ftraining

diff --git a/src/main/java/de/juplo/kafka/EndlessConsumer.java b/src/main/java/de/juplo/kafka/EndlessConsumer.java
index e4d9697..92802b9 100644
--- a/src/main/java/de/juplo/kafka/EndlessConsumer.java
+++ b/src/main/java/de/juplo/kafka/EndlessConsumer.java
@@ -1,68 +1,58 @@
 package de.juplo.kafka;
 
+import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
-import org.apache.kafka.clients.consumer.ConsumerRecord;
-import org.apache.kafka.clients.consumer.ConsumerRecords;
-import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.clients.consumer.*;
+import org.apache.kafka.common.TopicPartition;
+import org.apache.kafka.common.errors.RecordDeserializationException;
 import org.apache.kafka.common.errors.WakeupException;
-import org.apache.kafka.common.serialization.StringDeserializer;
 
+import javax.annotation.PreDestroy;
 import java.time.Duration;
-import java.util.Arrays;
-import java.util.Properties;
+import java.util.*;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
 import java.util.concurrent.locks.Condition;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
 
 
 @Slf4j
-public class SimpleConsumer
+@RequiredArgsConstructor
+public class EndlessConsumer<K, V> implements Runnable
 {
+  private final ExecutorService executor;
+  private final String id;
+  private final String topic;
+  private final Consumer<K, V> consumer;
+  private final RebalanceListener rebalanceListener;
+  private final RecordHandler<K, V> recordHandler;
+
+  private final Lock lock = new ReentrantLock();
+  private final Condition condition = lock.newCondition();
+  private boolean running = false;
+  private Exception exception;
   private long consumed = 0;
-  private KafkaConsumer<String, String> consumer;
-  private Lock lock = new ReentrantLock();
-  private Condition stopped = lock.newCondition();
 
 
-  public SimpleConsumer()
-  {
-    // tag::create[]
-    Properties props = new Properties();
-    props.put("bootstrap.servers", ":9092");
-    props.put("group.id", "my-consumer"); // << Used for Offset-Commits
-    // end::create[]
-    props.put("auto.offset.reset", "earliest");
-    // tag::create[]
-    props.put("key.deserializer", StringDeserializer.class.getName());
-    props.put("value.deserializer", StringDeserializer.class.getName());
-
-    KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
-    // end::create[]
-    this.consumer = consumer;
-  }
-
 
+  @Override
   public void run()
   {
-    String id = "C";
-
     try
     {
-      log.info("{} - Subscribing to topic test", id);
-      consumer.subscribe(Arrays.asList("test"));
+      log.info("{} - Subscribing to topic {}", id, topic);
+      consumer.subscribe(Arrays.asList(topic), rebalanceListener);
 
-      // tag::loop[]
       while (true)
       {
-        ConsumerRecords<String, String> records =
+        ConsumerRecords<K, V> records =
             consumer.poll(Duration.ofSeconds(1));
 
         // Do something with the data...
-        // end::loop[]
         log.info("{} - Received {} messages", id, records.count());
-        for (ConsumerRecord<String, String> record : records)
+        for (ConsumerRecord<K, V> record : records)
         {
-          consumed++;
           log.info(
               "{} - {}: {}/{} - {}={}",
               id,
@@ -72,60 +62,153 @@ public class SimpleConsumer
               record.key(),
               record.value()
           );
+
+          recordHandler.accept(record);
+
+          consumed++;
         }
-        // tag::loop[]
+
+        rebalanceListener.beforeNextPoll();
       }
-      // end::loop[]
     }
     catch(WakeupException e)
     {
-      log.info("{} - RIIING!", id);
+      log.info("{} - RIIING! Request to stop consumption - commiting current offsets!", id);
+      consumer.commitSync();
+      shutdown();
+    }
+    catch(RecordDeserializationException e)
+    {
+      TopicPartition tp = e.topicPartition();
+      long offset = e.offset();
+      log.error(
+          "{} - Could not deserialize  message on topic {} with offset={}: {}",
+          id,
+          tp,
+          offset,
+          e.getCause().toString());
+
+      consumer.commitSync();
+      shutdown(e);
     }
     catch(Exception e)
     {
-      log.error("{} - Unexpected error: {}", id, e.toString());
+      log.error("{} - Unexpected error: {}", id, e.toString(), e);
+      shutdown(e);
     }
     finally
     {
-      this.lock.lock();
-      try
-      {
-        log.info("{} - Closing the KafkaConsumer", id);
-        consumer.close();
-        log.info("C - DONE!");
-        stopped.signal();
-      }
-      finally
-      {
-        this.lock.unlock();
-        log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
-      }
+      log.info("{} - Consumer-Thread exiting", id);
     }
   }
 
-
-  public static void main(String[] args) throws Exception
+  private void shutdown()
   {
-    SimpleConsumer instance = new SimpleConsumer();
+    shutdown(null);
+  }
 
-    Runtime.getRuntime().addShutdownHook(new Thread(() ->
+  private void shutdown(Exception e)
+  {
+    lock.lock();
+    try
     {
-      instance.lock.lock();
       try
       {
-        instance.consumer.wakeup();
-        instance.stopped.await();
+        log.info("{} - Unsubscribing from topic {}", id, topic);
+        consumer.unsubscribe();
       }
-      catch (InterruptedException e)
+      catch (Exception ue)
       {
-        log.warn("Interrrupted while waiting for the consumer to stop!", e);
+        log.error(
+            "{} - Error while unsubscribing from topic {}: {}",
+            id,
+            topic,
+            ue.toString());
       }
       finally
       {
-        instance.lock.unlock();
+        running = false;
+        exception = e;
+        condition.signal();
       }
-    }));
+    }
+    finally
+    {
+      lock.unlock();
+    }
+  }
+
+  public void start()
+  {
+    lock.lock();
+    try
+    {
+      if (running)
+        throw new IllegalStateException("Consumer instance " + id + " is already running!");
+
+      log.info("{} - Starting - consumed {} messages before", id, consumed);
+      running = true;
+      exception = null;
+      executor.submit(this);
+    }
+    finally
+    {
+      lock.unlock();
+    }
+  }
 
-    instance.run();
+  public synchronized void stop() throws InterruptedException
+  {
+    lock.lock();
+    try
+    {
+      if (!running)
+        throw new IllegalStateException("Consumer instance " + id + " is not running!");
+
+      log.info("{} - Stopping", id);
+      consumer.wakeup();
+      condition.await();
+      log.info("{} - Stopped - consumed {} messages so far", id, consumed);
+    }
+    finally
+    {
+      lock.unlock();
+    }
+  }
+
+  @PreDestroy
+  public void destroy() throws ExecutionException, InterruptedException
+  {
+    log.info("{} - Destroy!", id);
+    log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
+  }
+
+  public boolean running()
+  {
+    lock.lock();
+    try
+    {
+      return running;
+    }
+    finally
+    {
+      lock.unlock();
+    }
+  }
+
+  public Optional<Exception> exitStatus()
+  {
+    lock.lock();
+    try
+    {
+      if (running)
+        throw new IllegalStateException("No exit-status available: Consumer instance " + id + " is running!");
+
+      return Optional.ofNullable(exception);
+    }
+    finally
+    {
+      lock.unlock();
+    }
   }
 }