[GitHub] [skywalking] zifeihan commented on issue #6456: ClassCastException from CallbackAdapterInterceptor to EnhancedInstance with spring-kafka

[GitBox <gi...@apache.org>]

zifeihan commented on issue #6456:
URL: https://github.com/apache/skywalking/issues/6456#issuecomment-786747586


   @yaojingguo thanks for report this issue, I may not have noticed that org.apache.kafka.clients.producer.KafkaProducer.InterceptorCallback wraps the callback of the doSend method. Therefore, Lambda callback caused the problem, I suggest modifying CallbackAdapterInterceptor to implement EnhancedInstance, and return callbackCache.getSnapshot() in getSkyWalkingDynamicField. like this,
   ```
   /**
    * implements Callback and EnhancedInstance, for kafka callback in lambda expression
    */
   public class CallbackAdapterInterceptor implements Callback, EnhancedInstance {
   
       /**
        * user Callback object
        */
       private CallbackCache callbackCache;
   
       public CallbackAdapterInterceptor(CallbackCache callbackCache) {
           this.callbackCache = callbackCache;
       }
   
       @Override
       public void onCompletion(RecordMetadata metadata, Exception exception) {
           ContextSnapshot snapshot = callbackCache.getSnapshot();
           AbstractSpan activeSpan = ContextManager.createLocalSpan("Kafka/Producer/Callback");
           SpanLayer.asMQ(activeSpan);
           activeSpan.setComponent(ComponentsDefine.KAFKA_PRODUCER);
           if (metadata != null) {
               Tags.MQ_TOPIC.set(activeSpan, metadata.topic());
           }
           ContextManager.continued(snapshot);
   
           try {
               callbackCache.getCallback().onCompletion(metadata, exception);
           } catch (Throwable t) {
               ContextManager.activeSpan().log(t);
               throw t;
           } finally {
               if (exception != null) {
                   ContextManager.activeSpan().log(exception);
               }
               ContextManager.stopSpan();
           }
       }
   
       @Override
       public Object getSkyWalkingDynamicField() {
           return callbackCache.getSnapshot();
       }
   
       @Override
       public void setSkyWalkingDynamicField(final Object value) {
   
       }
   ```
   
   welcome to submit pr for fix this bug, if you don’t have time, I will fix this bug later, @wu-sheng Suggestions are welcome


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