NAME

Time::HiRes - Perl extension for ualarm, usleep, and gettimeofday

SYNOPSIS

  use Time::HiRes;

  Time::HiRes::usleep ($microseconds);

  Time::HiRes::ualarm ($microseconds, $interval_microseconds);

  $t0 = [Time::HiRes::gettimeofday];
  ($seconds, $microseconds) = Time::HiRes::gettimeofday;

  $elapsed = Time::HiRes::tv_interval ( $t0, [$seconds, $microseconds]);
  $elapsed = Time::HiRes::tv_interval ( $t0, [Time::HiRes::gettimeofday]);
  $elapsed = Time::HiRes::tv_interval ( $t0 );

  $now_fractions = Time::HiRes::time;

  Time::HiRes::sleep ($floating_seconds);

  Time::HiRes::alarm ($floating_seconds);
  Time::HiRes::alarm ($floating_seconds, $floating_interval);
 
  use Time::HiRes qw ( time alarm sleep );
  $now_fractions = time;
  sleep ($floating_seconds);
  alarm ($floating_seconds);

DESCRIPTION

The Time::HiRes package implements a Perl interface to 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.

Note that if your system does not implement usleep(), ualarm(), and gettimeofday(), you will not be able to use this module. If you are in this situation, see MISSING UALARM() AND FRIENDS below.

gettimeofday

Returns a 2 element array with the second and microseconds since the epoch.

usleep ( $useconds )

Issues a usleep for the # of microseconds specified. See also Time::HiRes::sleep.

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_gettimeofday] )

Returns the floating seconds between the two times, which should have been returned by Time::HiRes::gettimeofday. If the second is omitted, then the current time is use.

time

Returns a floating seconds since the epoch. This function can be exported, 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 exported, 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_seconds and issues a ualarm for the results. $interval_floating_seconds is optional and will be 0 if unspecified, resulting in alarm-like behaviour. This function can be exported, resulting in a nice drop-in replacement for the alarm provided with perl, see the EXAMPLES below.

EXAMPLES

  use Time::HiRes;

  $microseconds = 750_000;
  Time::HiRes::usleep ($microseconds);

  # signal alarm in 2.5s & every .1 s thereafter
  Time::HiRes::ualarm (2_500_000, 100_000);     

  # get seconds and microseconds since the epoch
  ($s, $usec) = Time::HiRes::gettimeofday;

  # measure elapsed time 
  # (could also do by subtracting 2 Time::HiRes:gettimeofday_f return values)
  $t0 = [Time::HiRes::gettimeofday];
  # do bunch of stuff here
  $t1 = [Time::HiRes::gettimeofday];
  # do more stuff here
  $t0_t1 = Time::HiRes::tv_interval ($t0, $t1);
  
  $elapsed = Time::HiRes::tv_interval ($t0, [Time::HiRes::gettimeofday]);
  $elapsed = Time::HiRes::tv_interval ($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);

AUTHOR

D. Wegscheid <wegscd@whirlpool.com>

REVISION

$Id: HiRes.pm,v 1.2 1996/12/30 13:28:40 wegscd Exp $

$Log: HiRes.pm,v $ Revision 1.2 1996/12/30 13:28:40 wegscd Update documentation 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

MISSING UALARM() AND FRIENDS

If you have a system that does not have ualarm(), usleep(), and gettimeofday(), and you want to see this module work with it, you have two options: modify the source code to work with your system, or get me access to your system to do it (no promises about timeliness on this one!).

I have received mail from HP-UX, Linux, and Solaris users in this boat, and it's hard for me to tell if it's a simple problem of not having the correct libraries installed or if the routines are missing altogether.

If you make changes, let me know so they can be integrated back into the source so other users can benefit from your work. Thanks...

COPYRIGHT

Copyright (c) 1996 Douglas E. Wegscheid. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

2 POD Errors

The following errors were encountered while parsing the POD:

Around line 81:

'=item' outside of any '=over'

Around line 121:

You forgot a '=back' before '=head1'