Springify: Start/Stop prüft, ob der Container schon/noch läuft

[demos/kafka/training] / src / main / java / de / juplo / kafka / EndlessConsumer.java

diff --git a/src/main/java/de/juplo/kafka/EndlessConsumer.java b/src/main/java/de/juplo/kafka/EndlessConsumer.java
index 472e07d..a5a5ce6 100644 (file)
--- a/src/main/java/de/juplo/kafka/EndlessConsumer.java
+++ b/src/main/java/de/juplo/kafka/EndlessConsumer.java
@@ -6,8 +6,10 @@ import org.apache.kafka.clients.consumer.ConsumerRecord;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.kafka.annotation.KafkaListener;
+import org.springframework.kafka.config.KafkaListenerEndpointRegistry;
 import org.springframework.stereotype.Component;
 
+import javax.annotation.PreDestroy;
 import java.util.List;
 import java.util.function.Consumer;
 
@@ -17,11 +19,14 @@ import java.util.function.Consumer;
 @RequiredArgsConstructor
 public class EndlessConsumer<K, V>
 {
+  @Autowired
+  private KafkaListenerEndpointRegistry registry;
   @Value("${consumer.client-id}")
   String id;
   @Autowired
   Consumer<ConsumerRecord<K, V>> handler;
 
+  private long consumed = 0;
 
   @KafkaListener(
       id = "${consumer.client-id}",
@@ -46,6 +51,50 @@ public class EndlessConsumer<K, V>
       );
 
       handler.accept(record);
+
+      consumed++;
+    }
+  }
+
+
+  public synchronized void start()
+  {
+    if (registry.getListenerContainer(id).isChildRunning())
+      throw new IllegalStateException("Consumer instance " + id + " is already running!");
+
+    log.info("{} - Starting - consumed {} messages before", id, consumed);
+    registry.getListenerContainer(id).start();
+  }
+
+  public synchronized void stop()
+  {
+    if (!registry.getListenerContainer(id).isChildRunning())
+      throw new IllegalStateException("Consumer instance " + id + " is not running!");
+
+    log.info("{} - Stopping", id);
+    registry.getListenerContainer(id).stop();
+    log.info("{} - Stopped - consumed {} messages so far", id, consumed);
+  }
+
+  @PreDestroy
+  public void destroy()
+  {
+    log.info("{} - Destroy!", id);
+    try
+    {
+      stop();
+    }
+    catch (IllegalStateException e)
+    {
+      log.info("{} - Was already stopped", id);
+    }
+    catch (Exception e)
+    {
+      log.error("{} - Unexpected exception while trying to stop the consumer", id, e);
+    }
+    finally
+    {
+      log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
     }
   }
 }