A function provided by an asynchronous service provider to cancel a service that has been requested.
A function provided by an asynchronous service provider to cancel a service that has been requested.
由异步服务提供的函数，在取消服务时使用。
A function provided by an asynchronous service provider to cancel a service that has been requested.
由异步服务提供的函数，在取消服务时使用。