From 3fabe95013dba38b14f010df246c26b51740a16e Mon Sep 17 00:00:00 2001
From: Holger Just <hello@holgerjust.de>
Date: Wed, 20 Dec 2017 18:33:18 +0100
Subject: [PATCH] Refactor truncate_message filter

We extract some internal emthods to make the truncation flow clearer,
i.e. first we run the selectors, then we truncate the message, then we
insert the ellipsis message (if required).
---
 lib/rackstash/filter/truncate_message.rb | 52 ++++++++++++++++--------
 1 file changed, 35 insertions(+), 17 deletions(-)

diff --git a/lib/rackstash/filter/truncate_message.rb b/lib/rackstash/filter/truncate_message.rb
index 52330af..1d25063 100644
--- a/lib/rackstash/filter/truncate_message.rb
+++ b/lib/rackstash/filter/truncate_message.rb
@@ -97,36 +97,54 @@ module Rackstash
         end
         return event if messages.size <= 1
 
+        truncate(messages)
+
+        event
+      end
+
+      private
+
+      def truncate(messages)
         overall_size = overall_size_of(messages)
         ellipsis = nil
+
         until overall_size <= @max_size || messages.size <= 1
-          case @cut
-          when :top
-            msg = messages.shift
-          when :middle
-            msg = messages.delete_at(messages.size / 2)
-          when :bottom
-            msg = messages.pop
-          end
+          msg =
+            case @cut
+            when :top
+              messages.shift
+            when :middle
+              messages.delete_at(messages.size / 2)
+            when :bottom
+              messages.pop
+            end
+
           overall_size -= msg.size
+
           unless ellipsis || @ellipsis.nil?
             ellipsis = Rackstash::Message.new(@ellipsis)
             overall_size += ellipsis.size
           end
         end
 
-        if ellipsis
-          case @cut
-          when :top then messages.unshift(ellipsis)
-          when :middle then messages.insert((messages.size + 1) / 2, ellipsis)
-          when :bottom then messages.push(ellipsis)
-          end
-        end
+        # Insert the ellipsis message if we have truncated any messages
+        insert_into(messages, ellipsis) if ellipsis
 
-        event
+        messages
       end
 
-      private
+      def insert_into(messages, msg)
+        case @cut
+        when :top
+          messages.unshift(msg)
+        when :middle
+          messages.insert((messages.size + 1) / 2, msg)
+        when :bottom
+          messages.push(msg)
+        end
+
+        messages
+      end
 
       def overall_size_of(messages)
         messages.inject(0) { |sum, msg| sum + msg.size }