fix

@@ -9,6 +9,10 @@ const msg2row = require('./msg2row');
 const routeDecode = require('./route-decode');
 const crypto = global.yoho.crypto;
 
+const decodeUid = _.memoize(function(r) {
+    return crypto.decrypt(null, decodeURIComponent(r));
+});
+
 const durationType = {
     dcl: 'domcontentload',
     ld: 'domreadyload',
@@ -41,8 +45,7 @@ module.exports = (req, res, next) => {
 
             if (item.u) {
                 try {
-                    item.u = decodeURIComponent(item.u);
-                    item.u = crypto.decrypt(null, item.u);
+                    item.u = decodeUid(item.u);
                 } catch (e) {
                     logger.error('decode uid error ', item.u);
                     item.u = '0';