Apply modifications in pipeline to the records being passed to @ERROR label

lib/fluent/event_router.rb

@@ -116,6 +116,8 @@ def emit_stream(tag, es)
       if callback = find_callback
         callback.call(es)
       end
+    rescue Pipeline::OutputError => e
+      @emit_error_handler.handle_emits_error(tag, e.processed_es, e.internal_error)
     rescue => e
       @emit_error_handler.handle_emits_error(tag, es, e)
     end
@@ -161,6 +163,17 @@ def get(key)
     private
 
     class Pipeline
+
+      class OutputError < StandardError
+        attr_reader :internal_error
+        attr_reader :processed_es
+
+        def initialize(internal_error, processed_es)
+          @internal_error = internal_error
+          @processed_es = processed_es
+        end
+      end
+
       def initialize
         @filters = []
         @output = nil
@@ -178,7 +191,12 @@ def set_output(output)
 
       def emit_events(tag, es)
         processed = @optimizer.filter_stream(tag, es)
-        @output.emit_events(tag, processed)
+
+        begin
+          @output.emit_events(tag, processed)
+        rescue => e
+          raise OutputError.new(e, processed)
+        end
       end
 
       class FilterOptimizer

test/test_event_router.rb

@@ -326,6 +326,23 @@ def filter_with_time(tag, time, record); end
           event_router.emit('test', Engine.now, 'k' => 'v')
         end
       end
+
+      test 'can pass records modified by filters to handle_emits_error' do
+        filter = Class.new(FluentTestFilter) {
+          def filter_stream(_tag, es); end
+        }.new
+        event_router.add_rule('test', filter)
+        event_router.add_rule('test', error_output)
+
+        time = Engine.now
+        modified_es = OneEventStream.new(time, 'modified_label' => 'modified_value')
+
+        assert_rr do
+          stub(filter).filter_stream { modified_es }
+          mock(emit_handler).handle_emits_error('test', modified_es, is_a(RuntimeError))
+          event_router.emit('test', time, 'pre_label' => 'pre_value')
+        end
+      end
     end
   end
 end