hires(3)

NAME

Time::HiRes - High resolution ualarm, usleep, and gettime
ofday

SYNOPSIS

use Time::HiRes qw( usleep ualarm gettimeofday tv_interval );
usleep ($microseconds);
ualarm ($microseconds);
ualarm ($microseconds, $interval_microseconds);
$t0 = [gettimeofday];
($seconds, $microseconds) = gettimeofday;
$elapsed  =  tv_interval  (  $t0,  [$seconds, $microseconds]);
$elapsed = tv_interval ( $t0, [gettimeofday]);
$elapsed = tv_interval ( $t0 );
use Time::HiRes qw ( time alarm sleep );
$now_fractions = time;
sleep ($floating_seconds);
alarm ($floating_seconds);
alarm ($floating_seconds, $floating_interval);

DESCRIPTION

The "Time::HiRes" module implements a Perl interface to
the usleep, ualarm, and gettimeofday system calls. See the
EXAMPLES section below and the test scripts for usage; see
your system documentation for the description of the
underlying gettimeofday, usleep, and ualarm calls.

If your system lacks gettimeofday(2) you don't get get_ timeofday() or the one-arg form of tv_interval(). If you don't have usleep(3) or select(2) you don't get usleep() or sleep(). If your system don't have ualarm(3) or setitimer(2) you don't get ualarm() or alarm(). If you try to import an unimplemented function in the "use"
statement it will fail at compile time.

The following functions can be imported from this module.
No functions are exported by default.

gettimeofday (): In array context it returns a 2 element array with the
seconds and microseconds since the epoch. In scalar
context it returns floating seconds like
Time::HiRes::time() (see below).
usleep ( $useconds ): Issues a usleep for the number of microseconds speci
fied. See also Time::HiRes::sleep() below.
ualarm ( $useconds [, $interval_useconds ] ): Issues a ualarm call; interval_useconds is optional
and will be 0 if unspecified, resulting in alarm-like
behaviour.
tv_interval ( $ref_to_gettimeofday [, $ref_to_later_get timeofday] ): Returns the floating seconds between the two times,
which should have been returned by gettimeofday(). If the second argument is omitted, then the current time
is used.
time (): Returns a floating seconds since the epoch. This func
tion can be imported, resulting in a nice drop-in
replacement for the "time" provided with perl, see the
EXAMPLES below.
sleep ( $floating_seconds ): Converts $floating_seconds to microseconds and issues
a usleep for the result. This function can be
imported, resulting in a nice drop-in replacement for
the "sleep" provided with perl, see the EXAMPLES
below.
alarm ( $floating_seconds [, $interval_floating_seconds ] ): Converts $floating_seconds and $interval_floating_sec
onds and issues a ualarm for the results. The $inter
val_floating_seconds argument is optional and will be
0 if unspecified, resulting in alarm-like behaviour.
This function can be imported, resulting in a nice
drop-in replacement for the "alarm" provided with
perl, see the EXAMPLES below.

EXAMPLES

use Time::HiRes qw(usleep ualarm gettimeofday tv_inter
val);
$microseconds = 750_000; usleep $microseconds;
# signal alarm in 2.5s & every .1s thereafter ualarm 2_500_000, 100_000;
# get seconds and microseconds since the epoch ($s, $usec) = gettimeofday;
# measure elapsed time # (could also do by subtracting 2 gettimeofday return
values) $t0 = [gettimeofday]; # do bunch of stuff here $t1 = [gettimeofday]; # do more stuff here $t0_t1 = tv_interval $t0, $t1;
$elapsed = tv_interval ($t0, [gettimeofday]); $elapsed = tv_interval ($t0); # equivalent code
# # replacements for time, alarm and sleep that know about # floating seconds # use Time::HiRes; $now_fractions = Time::HiRes::time; Time::HiRes::sleep (2.5); Time::HiRes::alarm (10.6666666);
use Time::HiRes qw ( time alarm sleep ); $now_fractions = time; sleep (2.5); alarm (10.6666666);

C API

In addition to the perl API described above, a C API is available for extension writers. The following C functions are available in the modglobal hash:: name C prototype
--------------- ---------------------Time::NVtime double (*)()
Time::U2time void (*)(UV ret[2])
Both functions return equivalent information (like "get timeofday") but with different representations. The names "NVtime" and "U2time" were selected mainly because they are operating system independent. ("gettimeofday" is Un*x-centric.)
Here is an example of using NVtime from C:: double (*myNVtime)();
SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12,; 0);
if (!svp) croak("Time::HiRes is required");
if (!SvIOK(*svp)) croak("Time::NVtime isn't a function; pointer");
myNVtime = (double(*)()) SvIV(*svp);
printf("The current time is: %f0, (*myNVtime)());

AUTHORS

D. Wegscheid <wegscd@whirlpool.com> R. Schertler <roder
ick@argon.org> J. Hietaniemi <jhi@iki.fi> G. Aas
<gisle@aas.no>

REVISION

$Id: HiRes.pm,v 1.20 1999/03/16 02:26:13 wegscd Exp $

$Log: HiRes.pm,v $ Revision 1.20 1999/03/16 02:26:13
wegscd Add documentation for NVTime and U2Time.

Revision 1.19 1998/09/30 02:34:42 wegscd No changes,
bump version.

Revision 1.18 1998/07/07 02:41:35 wegscd No changes,
bump version.

Revision 1.17 1998/07/02 01:45:13 wegscd Bump version to
1.17

Revision 1.16 1997/11/13 02:06:36 wegscd version bump to
accomodate HiRes.xs fix.

Revision 1.15 1997/11/11 02:17:59 wegscd POD editing,
courtesy of Gisle Aas.

Revision 1.14 1997/11/06 03:14:35 wegscd Update version
# for Makefile.PL and HiRes.xs changes.

Revision 1.13 1997/11/05 05:36:25 wegscd change version
# for Makefile.pl and HiRes.xs changes.

Revision 1.12 1997/10/13 20:55:33 wegscd Force a new
version for Makefile.PL changes.

Revision 1.11 1997/09/05 19:59:33 wegscd New version to
bump version for README and Makefile.PL fixes. Fix bad
RCS log.

Revision 1.10 1997/05/23 01:11:38 wegscd Conditional
compilation; EXPORT_FAIL fixes.

Revision 1.2 1996/12/30 13:28:40 wegscd Update documen
tation for what to do when missing ualarm() and friends.

Revision 1.1 1996/10/17 20:53:31 wegscd Fix =head1 being
next to __END__ so pod2man works

Revision 1.0 1996/09/03 18:25:15 wegscd Initial revision

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