PERF: cache all site_text in memory

app/models/site_text.rb

@@ -2,11 +2,19 @@ require_dependency 'site_text_type'
 require_dependency 'site_text_class_methods'
 
 class SiteText < ActiveRecord::Base
+
+  # needed for site text class methods
+  @mutex = Mutex.new
+  @text_for_cache = {}
   extend SiteTextClassMethods
   self.primary_key = 'text_type'
 
   validates_presence_of :value
 
+  after_save do
+    MessageBus.publish '/text_for', self.text_type
+  end
+
   def self.formats
     @formats ||= Enum.new(:plain, :markdown, :html, :css)
   end

lib/site_setting_extension.rb

@@ -289,6 +289,7 @@ module SiteSettingExtension
   protected
 
   def clear_cache!
+    MessageBus.publish '/text_for', 'site_settings'
     Rails.cache.delete(SiteSettingExtension.client_settings_cache_key)
   end
 

lib/site_text_class_methods.rb

@@ -16,6 +16,41 @@ module SiteTextClassMethods
   end
 
   def text_for(text_type, replacements=nil)
+    text = nil
+    text = cached_text_for(text_type) if replacements.blank?
+    text ||= uncached_text_for(text_type, replacements)
+  end
+
+  def cached_text_for(text_type)
+    ensure_subscribed!
+    @mutex.synchronize do
+      cache = @text_for_cache[RailsMultisite::ConnectionManagement.current_db]
+      cache[text_type] if cache
+    end
+  end
+
+  def store_cached_text_for(text_type, result)
+    ensure_subscribed!
+    @mutex.synchronize do
+      cache = (@text_for_cache[RailsMultisite::ConnectionManagement.current_db] ||= {})
+      cache[text_type] = result
+    end
+  end
+
+  def ensure_subscribed!
+    return if @subscribed
+    @mutex.synchronize do
+      MessageBus.subscribe("/text_for") do |message|
+        @mutex.synchronize do
+          @text_for_cache[message.site_id] = nil
+        end
+      end
+    end
+  end
+
+  def uncached_text_for(text_type, replacements=nil)
+    store_cache = replacements.blank?
+
     replacements ||= {}
     replacements = {site_name: SiteSetting.title}.merge!(replacements)
     replacements = SiteSetting.settings_hash.merge!(replacements)
@@ -34,6 +69,11 @@ module SiteTextClassMethods
       replacements[m[2..-2].to_sym] || m
     end
 
+    if store_cache
+      result.freeze
+      store_cached_text_for(text_type, result)
+    end
+
     result
   end
 

spec/models/site_text_spec.rb

@@ -8,13 +8,29 @@ describe SiteText do
   describe "#text_for" do
 
     it "returns an empty string for a missing text_type" do
-      SiteText.text_for('breaking.bad').should == ""
+      SiteText.text_for('something_random').should == ""
     end
 
     it "returns the default value for a text` type with a default" do
       SiteText.text_for("usage_tips").should be_present
     end
 
+    it "correctly expires and bypasses cache" do
+      SiteSetting.enable_sso = false
+      text = SiteText.create!(text_type: "got.sso", value: "got sso: %{enable_sso}")
+      SiteText.text_for("got.sso").should == "got sso: false"
+      SiteText.text_for("got.sso").frozen? == true
+
+      SiteSetting.enable_sso = true
+      SiteText.text_for("got.sso").should == "got sso: true"
+
+      text.value = "I gots sso: %{enable_sso}"
+      text.save!
+
+      SiteText.text_for("got.sso").should == "I gots sso: true"
+      SiteText.text_for("got.sso", enable_sso: "frog").should == "I gots sso: frog"
+    end
+
     context "without replacements" do
       let!(:site_text) { Fabricate(:site_text_basic) }
 
@@ -46,12 +62,12 @@ describe SiteText do
       let!(:site_text) { Fabricate(:site_text_site_setting) }
 
       it "replaces site_settings by default" do
-        SiteSetting.stubs(:title).returns("Evil Trout")
+        SiteSetting.title = "Evil Trout"
         SiteText.text_for('site.replacement').should == "Evil Trout is evil."
       end
 
       it "allows us to override the default site settings" do
-        SiteSetting.stubs(:title).returns("Evil Trout")
+        SiteSetting.title = "Evil Trout"
         SiteText.text_for('site.replacement', title: 'Good Tuna').should == "Good Tuna is evil."
       end