Re: [Caml-list] POSIX time implementation

["Milan Stanojević" <milanst@gmail.com>]

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Jane Street's Core_kernel has Time_ns module. Time is represented as an
int, number of nanoseconds since unix epoch. Time_ns.now uses
clock_gettime(CLOCK_REALTIME)
There are also usual functions for operating on time and time spans.
Not sure if Core_kernel is too big for your project.
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/


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