PERF: cache all site_text in memory

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