update dashboard for better performance

app/helpers/application_helper.rb

@@ -248,15 +248,24 @@ module ApplicationHelper
   end
 
   def get_month_traffic
-    result = []
-    (0..30).each do |i|
-      visits = Impression.where( created_at: {
-        '$gte' => Time.now.beginning_of_day-i.days, 
-        '$lte' => Time.now.end_of_day-i.days}
-        ).count
-      result.push([ Time.now.beginning_of_day-i.days, visits])
+    site = Site.first
+    if site.month_traffic_cache.blank? or (site.month_traffic_cache['updated_at'] < (Time.now-1.day) rescue true)
+      site.month_traffic_cache = {}
+
+      site.month_traffic_cache['result'] = []
+      (1..30).each do |i|
+        visits = Impression.where( created_at: {
+          '$gte' => Time.now.beginning_of_day-i.days, 
+          '$lte' => Time.now.end_of_day-i.days}
+          ).distinct(:request_hash).count
+        site.month_traffic_cache['result'].push([ Time.now.beginning_of_day-i.days, visits])
+      end
+
+      site.month_traffic_cache['updated_at'] = Time.now
+      site.save
     end
-    [:name=> t(:visitors_count),:data=>result]
+    
+    [:name=> t(:visitors_count),:data=>site.month_traffic_cache['result']]
   end
 
   # def get_today_traffic

app/models/site.rb

@@ -51,6 +51,8 @@ class Site
   field :store_confirmation, :type => Boolean, :default => false
   field :meta_viewport, :type => Boolean, :default => false
 
+  field :month_traffic_cache
+
   belongs_to :design
   has_many :site_metas, :autosave => true, :dependent => :destroy
   validate :in_use_locales, :minimum_enabled_locales