package Time::HiRes;
use strict;
-use vars qw($VERSION @ISA @EXPORT @EXPORT_OK $AUTOLOAD);
+use vars qw($VERSION $XS_VERSION @ISA @EXPORT @EXPORT_OK $AUTOLOAD);
require Exporter;
-use XSLoader;
+require DynaLoader;
-@ISA = qw(Exporter);
+@ISA = qw(Exporter DynaLoader);
@EXPORT = qw( );
@EXPORT_OK = qw (usleep sleep ualarm alarm gettimeofday time tv_interval
- getitimer setitimer ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF);
-
-$VERSION = '1.21';
+ getitimer setitimer
+ ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF ITIMER_REALPROF
+ d_usleep d_ualarm d_gettimeofday d_getitimer d_setitimer
+ d_nanosleep);
+
+$VERSION = '1.47';
+$XS_VERSION = $VERSION;
+$VERSION = eval $VERSION;
sub AUTOLOAD {
my $constname;
- ($constname= $AUTOLOAD) =~ s/.*:://;
- my $val = constant($constname, @_ ? $_[0] : 0);
- if ($!) {
- my ($pack,$file,$line) = caller;
- die "Your vendor has not defined Time::HiRes macro $constname, used at $file line $line.\n";
- }
+ ($constname = $AUTOLOAD) =~ s/.*:://;
+ die "&Time::HiRes::constant not defined" if $constname eq 'constant';
+ my ($error, $val) = constant($constname);
+ if ($error) { die $error; }
{
no strict 'refs';
*$AUTOLOAD = sub { $val };
goto &$AUTOLOAD;
}
-XSLoader::load 'Time::HiRes', $VERSION;
+bootstrap Time::HiRes;
# Preloaded methods go here.
=head1 NAME
-Time::HiRes - High resolution ualarm, usleep, and gettimeofday
+Time::HiRes - High resolution alarm, sleep, gettimeofday, interval timers
=head1 SYNOPSIS
alarm ($floating_seconds, $floating_interval);
use Time::HiRes qw( setitimer getitimer
- ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF );
+ ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF ITIMER_REALPROF );
setitimer ($which, $floating_seconds, $floating_interval );
getitimer ($which);
=head1 DESCRIPTION
-The C<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.
+The Time::HiRes module implements a Perl interface to the usleep,
+ualarm, gettimeofday, and setitimer/getitimer system calls, in other
+words, high resolution time and timers. See the EXAMPLES section below
+and the test scripts for usage; see your system documentation for the
+description of the underlying nanosleep or usleep, ualarm,
+gettimeofday, and setitimer/getitimer calls.
+
+If your system lacks gettimeofday() or an emulation of it you don't
+get gettimeofday() or the one-arg form of tv_interval(). If you don't
+have any of the nanosleep() or usleep() or select() you don't get
+Time::HiRes::usleep() or Time::HiRes::sleep(). If your system don't
+have either ualarm() or setitimer() you don't get
+Time::HiRes::ualarm() or Time::HiRes::alarm().
-If your system lacks gettimeofday(2) you don't get gettimeofday() 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 C<use> statement
it will fail at compile time.
+If your subsecond sleeping is implemented with nanosleep() instead of
+usleep(), you can mix subsecond sleeping with signals since
+nanosleep() does not use signals. This however is unportable, and you
+should first check for the truth value of &Time::HiRes::d_nanosleep to
+see whether you have nanosleep, and then read carefully your
+nanosleep() C API documentation for any peculiarities. (There is no
+separate interface to call nanosleep(); just use Time::HiRes::sleep()
+or Time::HiRes::usleep() with small enough values.)
+
+Unless using nanosleep for mixing sleeping with signals, also give
+some thought to whether Perl is the tool you should be using for work
+requiring nanosecond accuracies.
+
The following functions can be imported from this module.
No functions are exported by default.
=item gettimeofday ()
-In array context it returns a 2 element array with the seconds and
-microseconds since the epoch. In scalar context it returns floating
+In array context returns a two-element array with the seconds and
+microseconds since the epoch. In scalar context returns floating
seconds like Time::HiRes::time() (see below).
=item usleep ( $useconds )
-Issues a usleep for the number of microseconds specified. See also
-Time::HiRes::sleep() below.
+Sleeps for the number of microseconds specified. Returns the number
+of microseconds actually slept. Can sleep for more than one second
+unlike the usleep system call. See also Time::HiRes::sleep() below.
=item ualarm ( $useconds [, $interval_useconds ] )
-Issues a ualarm call; interval_useconds is optional and will be 0 if
-unspecified, resulting in alarm-like behaviour.
+Issues a ualarm call; the $interval_useconds is optional and
+will be zero if unspecified, resulting in alarm-like behaviour.
=item tv_interval
-S<tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] )>
+tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] )
-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.
+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.
=item time ()
-Returns a floating seconds since the epoch. This function can be imported,
-resulting in a nice drop-in replacement for the C<time> provided with perl,
-see the EXAMPLES below.
+Returns a floating seconds since the epoch. This function can be
+imported, resulting in a nice drop-in replacement for the time
+provided with core Perl, see the EXAMPLES below.
+
+B<NOTE 1>: this higher resolution timer can return values either less
+or more than the core time(), depending on whether your platforms
+rounds the higher resolution timer values up, down, or to the nearest
+to get the core time(), but naturally the difference should be never
+more than half a second.
+
+B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT (when
+the time() seconds since epoch rolled over to 1_000_000_000), the
+default floating point format of Perl and the seconds since epoch have
+conspired to produce an apparent bug: if you print the value of
+Time::HiRes::time() you seem to be getting only five decimals, not six
+as promised (microseconds). Not to worry, the microseconds are there
+(assuming your platform supports such granularity in first place).
+What is going on is that the default floating point format of Perl
+only outputs 15 digits. In this case that means ten digits before the
+decimal separator and five after. To see the microseconds you can use
+either printf/sprintf with "%.6f", or the gettimeofday() function in
+list context, which will give you the seconds and microseconds as two
+separate values.
=item 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 C<sleep> provided with perl, see the EXAMPLES below.
+Sleeps for the specified amount of seconds. Returns the number of
+seconds actually slept (a floating point value). This function can be
+imported, resulting in a nice drop-in replacement for the sleep
+provided with perl, see the EXAMPLES below.
=item alarm ( $floating_seconds [, $interval_floating_seconds ] )
-Converts $floating_seconds and $interval_floating_seconds and issues
-a ualarm for the results. The $interval_floating_seconds argument
-is optional and will be 0 if unspecified, resulting in alarm-like
+The SIGALRM signal is sent after the specified number of seconds.
+Implemented using ualarm(). The $interval_floating_seconds argument
+is optional and will be zero if unspecified, resulting in alarm()-like
behaviour. This function can be imported, resulting in a nice drop-in
-replacement for the C<alarm> provided with perl, see the EXAMPLES below.
+replacement for the alarm provided with perl, see the EXAMPLES below.
+
+B<NOTE 1>: With some operating system and Perl release combinations
+select() gets restarted by SIGALRM, instead of dropping out of
+select(). This means that an alarm() followed by a select()
+may together take the sum of the times specified for the the
+alarm() and the select(), not just the time of the alarm().
=item setitimer
-S<setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )>
+setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )
-Start up an interval timer: after a certain time, a signal is arrives,
-and more may keep arriving at certain intervals. To disable a timer,
-use time of zero. If interval is set to zero (or unspecified), the
-timer is disabled after the next delivered signal.
+Start up an interval timer: after a certain time, a signal arrives,
+and more signals may keep arriving at certain intervals. To disable a
+timer, use $floating_seconds of zero. If the $interval_floating_seconds
+is set to zero (or unspecified), the timer is disabled B<after> the
+next delivered signal.
-Use of interval timers may interfere with alarm(), sleep(), and usleep().
-In standard-speak the "interaction is unspecified", which means that
-I<anything> may happen: it may work, it may not.
+Use of interval timers may interfere with alarm(), sleep(),
+and usleep(). In standard-speak the "interaction is unspecified",
+
which means that I<anything> may happen: it may work, it may not.
In scalar context, the remaining time in the timer is returned.
In list context, both the remaining time and the interval are returned.
-There are three interval timers: the $which can be ITIMER_REAL,
-ITIMER_VIRTUAL, or ITIMER_PROF.
+There are usually three or four interval timers available: the $which
+can be ITIMER_REAL, ITIMER_VIRTUAL, ITIMER_PROF, or ITIMER_REALPROF.
+Note that which ones are available depends: true UNIX platforms have
+usually all first three, but for example Win32 and Cygwin only have
+ITIMER_REAL, and only Solaris seems to have ITIMER_REALPROF (which is
+used to profile multithreaded programs).
ITIMER_REAL results in alarm()-like behavior. Time is counted in
I<real time>, that is, wallclock time. SIGALRM is delivered when
the timer expires.
ITIMER_VIRTUAL counts time in (process) I<virtual time>, that is, only
-when the process is running. In multiprocessing/user/CPU systems this
-may be much less than real time. (This time is also known as the
-I<user time>.) SIGVTALRM is delivered when the timer expires.
+when the process is running. In multiprocessor/user/CPU systems this
+may be more or less than real or wallclock time. (This time is also
+known as the I<user time>.) SIGVTALRM is delivered when the timer expires.
ITIMER_PROF counts time when either the process virtual time or when
-the operating system is running on behalf of the process (such as
-I/O). (This time is also known as the I<system time>.) (Collectively
-these times are also known as the I<CPU time>.) SIGPROF is delivered
-when the timer expires. SIGPROF can interrupt system calls.
+the operating system is running on behalf of the process (such as I/O).
+(This time is also known as the I<system time>.) (The sum of user
+time and system time is known as the I<CPU time>.) SIGPROF is
+delivered when the timer expires. SIGPROF can interrupt system calls.
The semantics of interval timers for multithreaded programs are
system-specific, and some systems may support additional interval
$t1 = [gettimeofday];
# do more stuff here
$t0_t1 = tv_interval $t0, $t1;
-
+
$elapsed = tv_interval ($t0, [gettimeofday]);
$elapsed = tv_interval ($t0); # equivalent code
$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);
use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time );
- $SIG{VTLARM} = sub { print time, "\n" };
+ $SIG{VTALRM} = sub { print time, "\n" };
setitimer(ITIMER_VIRTUAL, 10, 2.5);
=head1 C API
Time::NVtime double (*)()
Time::U2time void (*)(UV ret[2])
-Both functions return equivalent information (like C<gettimeofday>)
-but with different representations. The names C<NVtime> and C<U2time>
+Both functions return equivalent information (like gettimeofday)
+but with different representations. The names NVtime and U2time
were selected mainly because they are operating system independent.
-(C<gettimeofday> is Un*x-centric.)
+(gettimeofday is Unix-centric, though some platforms like VMS have
+emulations for it.)
Here is an example of using NVtime from C:
SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0);
if (!svp) croak("Time::HiRes is required");
if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer");
- myNVtime = (double(*)()) SvIV(*svp);
+ myNVtime = INT2PTR(double(*)(), SvIV(*svp));
printf("The current time is: %f\n", (*myNVtime)());
+=head1 CAVEATS
+
+Notice that the core time() maybe rounding rather than truncating.
+What this means that the core time() may be giving time one second
+later than gettimeofday(), also known as Time::HiRes::time().
+
=head1 AUTHORS
D. Wegscheid <wegscd@whirlpool.com>
J. Hietaniemi <jhi@iki.fi>
G. Aas <gisle@aas.no>
-=head1 REVISION
-
-$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 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
+=head1 COPYRIGHT AND LICENSE
-Revision 1.0 1996/09/03 18:25:15 wegscd
-Initial revision
+Copyright (c) 1996-2002 Douglas E. Wegscheid. All rights reserved.
-=head1 COPYRIGHT
+Copyright (c) 2002,2003 Jarkko Hietaniemi. All rights reserved.
-Copyright (c) 1996-1997 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.
+This program is free software; you can redistribute it and/or modify
+it under the same terms as Perl itself.
=cut
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