From a79b1807d79ec16e37a69a4ca0e54a85f90389a9 Mon Sep 17 00:00:00 2001
From: Sam <sam.saffron@gmail.com>
Date: Fri, 14 Nov 2014 17:51:04 +1100
Subject: [PATCH] FEATURE: attempt to recover from corrupt markdown engine

---
 lib/pretty_text.rb | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/lib/pretty_text.rb b/lib/pretty_text.rb
index 2c4622815c6..81846f75e7a 100644
--- a/lib/pretty_text.rb
+++ b/lib/pretty_text.rb
@@ -116,6 +116,12 @@ module PrettyText
     @ctx
   end
 
+  def self.reset_context
+    @ctx_init.synchronize do
+      @ctx = nil
+    end
+  end
+
   def self.decorate_context(context)
     context.eval("Discourse.SiteSettings = #{SiteSetting.client_settings_json};")
     context.eval("Discourse.CDN = '#{Rails.configuration.action_controller.asset_host}';")
@@ -151,6 +157,19 @@ module PrettyText
       baked = context.eval('Discourse.Markdown.markdownConverter(opts).makeHtml(raw)')
     end
 
+    if baked.blank? && !(opts || {})[:skip_blank_test]
+      # we may have a js engine issue
+      test = markdown("a", skip_blank_test: true)
+      if test.blank?
+        Rails.logger.warn("Markdown engine appears to have crashed, resetting context")
+        reset_context
+        opts ||= {}
+        opts = opts.dup
+        opts[:skip_blank_test] = true
+        baked = markdown(text, opts)
+      end
+    end
+
     baked
   end