Re: os.clock conversion to milliseconds under MacOS X

["Gary V. Vaughan" <gary@...>]

> On Dec 17, 2014, at 11:09 AM, Gary V. Vaughan <gary@vaughan.pe> wrote:
> 
> On Dec 17, 2014, at 9:50 AM, Marco Bambini <marco@sqlabs.net> wrote:
>> what is the correct way to convert a difference between two os.clock values in milliseconds on MacOS X?
> 
> os.clock() only has 1-second resolution, but if the nearest 1000ms is enough for you then:
> 
>    $ lua
>    Lua 5.3.0  Copyright (C) 1994-2014 Lua.org, PUC-Rio
>> began = os.clock ()
>> local elapsed = os.difftime (os.clock (), began)
>> io.write (string.format ("%dms elapsed\n", 1000 * elapsed))
>    1000ms elapsed
> 
> otherwise, you might find the luaposix[1] time functions, with nanoseconds resolution, more useful:

I mean, *micro*second resolution...

>    $ lua
>    Lua 5.3.0  Copyright (C) 1994-2014 Lua.org, PUC-Rio
>> posix = require 'posix'
>> timersub, gettimeofday = posix.timersub, posix.gettimeofday
>> began = gettimeofday ()
>> elapsed = timersub (gettimeofday (), began)
>> io.write (string.format ("%.0fms elapsed\n", elapsed.sec * 1000 + elapsed.usec / 1000))
>    1758ms elapsed
> 
> HTH,
> -- 
> Gary V. Vaughan (gary AT vaughan DOT pe)