use the cached plugin settings to determine if enabled

Change-Id: Idae91f14090fba31391ef10b8472114b606a0322
Reviewed-on: https://gerrit.instructure.com/25023
Reviewed-by: Jacob Fugal <jacob@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>

app/models/plugin_setting.rb

@@ -98,9 +98,16 @@ class PluginSetting < ActiveRecord::Base
     read_attribute(:disabled) != true
   end
 
+  def self.cached_plugin_setting(name)
+    plugin_setting = Rails.cache.fetch(settings_cache_key(name)) do
+      PluginSetting.find_by_name(name.to_s) || :nil
+    end
+    plugin_setting = nil if plugin_setting == :nil
+    plugin_setting
+  end
+
   def self.settings_for_plugin(name, plugin=nil)
-    res = Rails.cache.fetch(settings_cache_key(name)) do
-      if (plugin_setting = PluginSetting.find_by_name(name.to_s)) && plugin_setting.valid_settings? && plugin_setting.enabled?
+    if (plugin_setting = cached_plugin_setting(name)) && plugin_setting.valid_settings? && plugin_setting.enabled?
       plugin_setting.plugin = plugin
       settings = plugin_setting.settings
     else
@@ -109,14 +116,11 @@ class PluginSetting < ActiveRecord::Base
       settings = plugin.default_settings
     end
 
-      settings || :nil
-    end
-    res = nil if res == :nil
-    res
+    settings
   end
 
   def self.settings_cache_key(name)
-    ["settings_for_plugin", name].cache_key
+    ["settings_for_plugin2", name].cache_key
   end
 
   def clear_cache

lib/canvas/plugin.rb

@@ -60,7 +60,7 @@ module Canvas
     end
 
     def enabled?
-      ps = PluginSetting.find_by_name(self.id.to_s)
+      ps = PluginSetting.cached_plugin_setting(self.id)
       return false unless ps
       ps.valid_settings? && ps.enabled?
     end