Refactor: dry-out exception handling in output

lib/logstash/outputs/kafka.rb

@@ -50,6 +50,9 @@
 class LogStash::Outputs::Kafka < LogStash::Outputs::Base
 
   java_import org.apache.kafka.clients.producer.ProducerRecord
+  java_import org.apache.kafka.common.KafkaException
+  java_import org.apache.kafka.common.errors.RetriableException
+  java_import org.apache.kafka.common.errors.InterruptException
 
   include LogStash::PluginMixins::KafkaSupport
 
@@ -255,18 +258,9 @@ def retrying_send(batch)
 
       futures = batch.collect do |record| 
         begin
-          # send() can throw an exception even before the future is created.
           @producer.send(record)
-        rescue org.apache.kafka.common.errors.InterruptException,
-               org.apache.kafka.common.errors.RetriableException => e
-          logger.info("producer send failed, will retry sending", :exception => e.class, :message => e.message)
-          failures << record
-          nil
-        rescue org.apache.kafka.common.KafkaException => e
-          # This error is not retriable, drop event
-          # TODO: add DLQ support
-          logger.warn("producer send failed, dropping record",:exception => e.class, :message => e.message,
-                      :record_value => record.value)
+        rescue => e # send() can throw an exception even before the future is created
+          failures << record if handle_kafka_error(e, record) == :retry
           nil
         end
       end
@@ -277,18 +271,8 @@ def retrying_send(batch)
           begin
             future.get
           rescue java.util.concurrent.ExecutionException => e
-            # TODO(sissel): Add metric to count failures, possibly by exception type.
-            if e.get_cause.is_a? org.apache.kafka.common.errors.RetriableException or
-               e.get_cause.is_a? org.apache.kafka.common.errors.InterruptException
-              logger.info("producer send failed, will retry sending", :exception => e.cause.class,
-                          :message => e.cause.message)
-              failures << batch[i]
-            elsif e.get_cause.is_a? org.apache.kafka.common.KafkaException
-              # This error is not retriable, drop event
-              # TODO: add DLQ support
-              logger.warn("producer send failed, dropping record", :exception => e.cause.class,
-                          :message => e.cause.message, :record_value => batch[i].value)
-            end
+            record = batch[i]
+            failures << record if handle_kafka_error(e.cause, record) == :retry
           end
         end
       end
@@ -314,6 +298,22 @@ def close
 
   private
 
+  def handle_kafka_error(e, record)
+    # TODO(sissel): Add metric to count failures, possibly by exception type.
+    case e
+    when RetriableException, InterruptException
+      logger.info("producer send failed, will retry sending", :exception => e.class, :message => e.message)
+      return :retry
+    when KafkaException
+      # This error is not retriable, drop event
+      # TODO: add DLQ support
+      logger.warn("producer send failed, dropping record", :exception => e.class, :message => e.message, :record_value => record.value)
+    else
+      logger.error("producer send failed, unexpected exception", :exception => e.class, :message => e.message, :backtrace => e.backtrace)
+      raise e
+    end
+  end
+
   def write_to_kafka(event, serialized_data)
     if @message_key.nil?
       record = ProducerRecord.new(event.sprintf(@topic_id), serialized_data)
@@ -369,8 +369,7 @@ def create_producer
       org.apache.kafka.clients.producer.KafkaProducer.new(props)
     rescue => e
       logger.error("Unable to create Kafka producer from given configuration",
-                   :kafka_error_message => e,
-                   :cause => e.respond_to?(:getCause) ? e.getCause() : nil)
+                   :message => e.message, :exception => e.class, :cause => e.cause)
       raise e
     end
   end