nl_tokens: 请求前的操作
pl_tokens: function ( ) { var self = this ; if ( this . counted ) { return this . getRequestCount ( ) . then ( function ( count ) { count = count || 0 ; //如果请求数超过限制则 setTimeout 排队 if ( <mask> >= config . requestLimit ) { return Promise . delay ( config . requestTimeout ) . then ( self . onBeforeHandle ) ; } return count ; } ) . then ( increment ) . then ( this . saveRequestCount ) ; } return Promise . resolve ( ) ; }