Update webstats_common.lua

plugins/webstats/lua/webstats_common.lua

@@ -266,8 +266,6 @@ end
 function _M.cron(self)
 
     local timer_every_get_data = function (premature)
-        self:cronPre()
-
         
         local llen, _ = ngx.shared.mw_total:llen(total_key)
         -- self:D("PID:"..tostring(ngx.worker.id())..",llen:"..tostring(llen))
@@ -275,6 +273,8 @@ function _M.cron(self)
             return true
         end
 
+        self:cronPre()
+
         ngx.update_time()
         local begin = ngx.now()