From 83559bbf458cbef1e4a52dc3bd0702cd7f0d311b Mon Sep 17 00:00:00 2001
From: Sam Saffron <sam.saffron@gmail.com>
Date: Mon, 1 Jun 2015 11:55:07 +1000
Subject: [PATCH] posts read may enter concurrently, retry

---
 app/models/user.rb | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/app/models/user.rb b/app/models/user.rb
index 8500f4973f1..0b528cbefeb 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -373,13 +373,21 @@ class User < ActiveRecord::Base
     create_visit_record!(date) unless visit_record_for(date)
   end
 
-  def update_posts_read!(num_posts, now=Time.zone.now)
+  def update_posts_read!(num_posts, now=Time.zone.now, _retry=false)
     if user_visit = visit_record_for(now.to_date)
       user_visit.posts_read += num_posts
       user_visit.save
       user_visit
     else
-      create_visit_record!(now.to_date, num_posts)
+      begin
+        create_visit_record!(now.to_date, num_posts)
+      rescue ActiveRecord::RecordNotUnique
+        if !_retry
+          update_posts_read!(num_posts, now, _retry=true)
+        else
+          raise
+        end
+      end
     end
   end