From 1e0d6afdbe862397fa1f6c03fb186a403af0820d Mon Sep 17 00:00:00 2001
From: Nick LaMuro <nicklamuro@gmail.com>
Date: Tue, 24 Apr 2018 16:25:01 -0500
Subject: [PATCH] Refactor get_ems_folders to create less strings

Creating some strings in this method is inevitable, since we are
generating string paths based on this compiled info, but there were a
lot of excessive strings being created because of it:

- Both of the strings in this method were being created every time
  this method was called.  For the "Datacenter".freeze one, it was
  just used as a comparison as well
- Using << where possible will avoid generating new substrings, so we
  are only creating one new string at most.
- Deferred the `.dup` of full_path until a new string was known that it
  would be generated.  This did require creating a new variable to hold
  on to the existing variable, but that wasn't a big deal and didn't
  increase the number of allocations.

Split up some ternary operators as well just to make running profilers
on this code easier to determine what as causing allocations
(granularity in tracing object allocations in ruby is only down to a
line by line basis).
---
 app/models/miq_request_workflow.rb | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/app/models/miq_request_workflow.rb b/app/models/miq_request_workflow.rb
index f6207b56db2..ba233e2c7ad 100644
--- a/app/models/miq_request_workflow.rb
+++ b/app/models/miq_request_workflow.rb
@@ -856,19 +856,25 @@ def ems_has_clusters?
   end
 
   def get_ems_folders(folder, dh = {}, full_path = "")
+    path = full_path
     if folder.evm_object_class == :EmsFolder
       if folder.hidden
         return dh if folder.name != 'vm'
       else
-        full_path += full_path.blank? ? folder.name.to_s : " / #{folder.name}"
-        dh[folder.id] = full_path unless folder.type == "Datacenter"
+        path = full_path.dup
+        if path.blank?
+          path << folder.name.to_s
+        else
+          path << " / ".freeze << folder.name
+        end
+        dh[folder.id] = path unless folder.type == "Datacenter".freeze
       end
     end
 
     # Process child folders
     @_get_ems_folders_prefix ||= _log.prefix
     node = load_ems_node(folder, @_get_ems_folders_prefix)
-    node.children.each { |child| get_ems_folders(child.attributes[:object], dh, full_path) } unless node.nil?
+    node.children.each { |child| get_ems_folders(child.attributes[:object], dh, path) } unless node.nil?
 
     dh
   end