Re: [Caml-list] POSIX time implementation

["Markus Weißmann" <markus.weissmann@in.tum.de>]

For the record:
I found another OCaml implementation of clock_gettime(2): oclock [7] 
(also available via opam).
Unfortunately oclock implements 'struct timespec { time_t, long }' as 
int64, making some conversion necessary, too.

regards
-Markus

[7] http://micdel.fr/oclock.html

On 2015-09-05 13:52, Markus W. Weißmann wrote:
> Hi,
>
> I was searching for an existing library implementing a
> clock_gettime(2) function that would deliver a ‘struct timespec’ [1]
> with the current time.
> I want it for my POSIX message queue implementation [2] for the timed
> functions that require an absolute ‘struct timespec’ for their
> timeout.
> So what a user of mqueue requires is a 1.) function to get the
> current time as ‘struct timespec’ and 2.) to add seconds/nanoseconds
> to such a value to create a timeout.
>
> The existing solutions I found:
> * The Unix library [3] implements ‘struct timeval’ as float (only
> microseconds, imho the float conversion is a bit of a hack — a clever
> one though)
> * Netsys.clock_gettime from ocamlnet [4] implements ’struct timespec’
> but has it as float/int for seconds/nanoseconds (whats with the 
> float?
> All systems I found use either in32 or int64 for time_t)
> * Mtime [5] implements clock_gettime(2) but seems to only offers 
> relative values
> * Ptime [6] appears to be the uber-POSIX time implementation but
> lacks clock_gettime (and probably always will)
>
> I’d like my library to be a good OCaml citizen and _not_ implement my
> own special purpose timing functions (which are incompatible to
> everyone else’s).
> Ptime looks like the ultimate solution for the datatype; ocamlnet
> gets the closest to my requirements — while being a gigantic library
> most of which has nothing to do with the domain of mqueue.
>
> I’m a bit stuck on this one and would like to get some advice —
> and/or corrections if I misinterpreted one of the above solutions.
>
> regards
> -Markus
>
> [1] 
> http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/time.h.html
> [2] http://mqueue.forge.ocamlcore.org/
> [3] http://caml.inria.fr/pub/docs/manual-ocaml/libref/Unix.html
> [4]
> 
> http://projects.camlcity.org/projects/dl/ocamlnet-4.0.4/doc/html-main/Netsys_posix.html
> [5] http://erratique.ch/software/mtime
> [6] http://erratique.ch/software/ptime
>
> --
> Markus Weißmann, M.Sc.
> Technische Universität München
> Institut für Informatik
> Boltzmannstr. 3
> D-85748 Garching
> Germany
> http://wwwknoll.in.tum.de/