get online user count method

app/libs/util/redis.rb

@@ -0,0 +1,9 @@
+module Util::Redis
+  class << self
+    def online_user_count
+      if Rails.cache.is_a?(ActiveSupport::Cache::RedisStore)
+        Rails.cache.data.scan(0, match: 'cache:_session_id:*', count: 100000).last.size
+      end
+    end
+  end
+end