Oclock

Precise POSIX clock for OCaml

This OCaml module provides access to precise time information (in nanoseconds) on POSIX-compatible system (Linux, FreeBSD, OpenBSD, etc.). It is made possible through the clock_gettime (2) family of functions. Though times are given in nanoseconds, their actual accurracies vary greatly depending on the system.

Useful links

Easy install (with OPAM)

opam update
opam install oclock

Done.

Requirements

Just the usual suspects: GNU Make, GCC, OCaml, and optionally Findlib (i.e., ocamlfind).

Also, a true POSIX system, i.e., not MacOS. Indeed MacOS does not support clock_gettime. There are alternatives but I do not have a Mac... if you are interested in extending the library, let me know.

Installation

make

Build the library.

make install

Install the library in the standard ocaml directory. Depending on your system you may have to `sudo` the last command or to run it as root.

Usage

Manually:

ocamlc -I +oclock oclock.cma ...
ocamlopt -I +oclock oclock.cmxa ...

Or with ocamlfind:

ocamlfind ocamlc -package oclock ...
ocamlfind ocamlopt -package oclock ...

Documentation

To build the API documentation in HTML, use:

make doc

Then, open doc/index.html with your favorite browser.

Available clocks differ under the various POSIX systems (e.g., see Linux, OpenBSD, and FreeBSD man-pages). Most differences between systems are levelled out by the OCaml interface.

Two examples are also provided in the examples directory:

getcputime gets the CPU-time consumed by a process given its PID.
realtime gets the real time since the Epoch, and evaluates the clock precision inside OCaml.

License

Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.