From 030d2260a737a08b967eb5cd2d46205f7e315571 Mon Sep 17 00:00:00 2001
From: Sam <sam.saffron@gmail.com>
Date: Mon, 9 Sep 2013 16:02:13 +1000
Subject: [PATCH] Perf: don't allocate hashes OVER and OVER in a loop, its bad

---
 lib/avatar_lookup.rb | 27 ++++++++++++++++++++++-----
 1 file changed, 22 insertions(+), 5 deletions(-)

diff --git a/lib/avatar_lookup.rb b/lib/avatar_lookup.rb
index c48ee5cd2..aef319692 100644
--- a/lib/avatar_lookup.rb
+++ b/lib/avatar_lookup.rb
@@ -11,11 +11,28 @@ class AvatarLookup
 
   private
 
+  def self.lookup_columns
+    @lookup_columns ||= [:id,
+                            :email,
+                            :username,
+                            :use_uploaded_avatar,
+                            :uploaded_avatar_template,
+                            :uploaded_avatar_id]
+  end
+
   def users
-    @users ||= User.where(:id => @user_ids)
-                   .select([:id, :email, :username, :use_uploaded_avatar, :uploaded_avatar_template, :uploaded_avatar_id])
-                   .inject({}) do |hash, user|
-      hash.merge({user.id => user})
-    end
+    @users ||= user_lookup_hash
+  end
+
+  def user_lookup_hash
+    # adding tap here is a personal taste thing
+    hash = {}
+    User
+      .where(:id => @user_ids)
+      .select(AvatarLookup.lookup_columns)
+      .each{|user|
+        hash[user.id] = user
+      }
+    hash
   end
 end