cancel a single job

Hey

I need to make sure that we can do several calls to ares_gethostbyname() in
the same "channel" and then later be able to ares_cancel() (or equivalent) a
single one them when I want to stop just one of multiple outstanding requests.

I want to do this by adding a "job id" return code to ares_gethostbyname() and
let ares_cancel() take such a job id as argument and it then kills that job
only. ares_cancel() would also accept a "magic" id that would kill all jobs,
making it work like today.

Good? Bad? Other ideas/approaches?

-- 
   c-ares -- my preferred DNS asynch resolver library