Re: PROPOSAL(S): threadWaitError and threadWaitErrorSTM

Seems rather simple, just use epoll's EPOLLERR event type. There's more types (like the EPOLLPRI type you mentioned), but I would not argue for adding those as such events may not be portable to platforms that don't support epoll (i.e. platforms that only have kqueue/select), whereas EPOLLERR should be available in some form for all platforms. Cheers, Merijn On Mar 17, 2014, at 14:23 , Andreas Voellmy wrote:

Hi Merijn,

I see how you'd wait for exceptional conditions using select(). Epoll is a bit different... How would you do it with epoll? Is it using the EPOLLPRI event type?

Andi

On Sun, Mar 16, 2014 at 1:16 PM, Merijn Verstraaten wrote: I just went with the common documentation name, I know this includes out-of-band data, etc. If it makes you happier, feel free to consider this proposal with s/Error/Exceptional, regardless of how it's called, it'd be nice if we could use this from within Haskell.

Cheers, Merijn

On Mar 16, 2014, at 16:09 , Brandon Allbery wrote:

...

On Sun, Mar 16, 2014 at 10:25 AM, Merijn Verstraaten wrote: threadWaitError :: Fd -> IO () threadWaitErrorSTM :: Fd -> IO (STM (), IO ())

to allow for blocking on detecting error condition on file descriptors, similar to what C's select() allows.

If you mean the third bitmask, it is not for errors (notwithstanding the documentation on some systems); an "exceptional condition" is not an error, it's MSG_OOB data. Errors show as "ready" on the appropriate mask (read or write) since a read (resp. write) will return immediately with the error instead of blocking.

See http://stackoverflow.com/questions/1342712/nix-select-and-exceptfds-errorfds... and http://man7.org/linux/man-pages/man2/select_tut.2.html for more information.

-- brandon s allbery kf8nh sine nomine associates allbery.b@gmail.com ballbery@sinenomine.net unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net

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