@EXPORT = qw( );
@EXPORT_OK = qw (usleep sleep ualarm alarm gettimeofday time tv_interval
- getitimer setitimer
+ getitimer setitimer nanosleep clock_gettime clock_getres
+ CLOCK_HIGHRES CLOCK_MONOTONIC CLOCK_PROCESS_CPUTIME_ID
+ CLOCK_REALTIME CLOCK_THREAD_CPUTIME_ID CLOCK_TIMEOFDAY
ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF ITIMER_REALPROF
d_usleep d_ualarm d_gettimeofday d_getitimer d_setitimer
- d_nanosleep);
+ d_nanosleep d_clock_gettime d_clock_getres);
-$VERSION = '1.39';
+$VERSION = '1.82';
$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/.*:://;
+ # print "AUTOLOAD: constname = $constname ($AUTOLOAD)\n";
+ die "&Time::HiRes::constant not defined" if $constname eq 'constant';
+ my ($error, $val) = constant($constname);
+ # print "AUTOLOAD: error = $error, val = $val\n";
+ if ($error) {
+ my (undef,$file,$line) = caller;
+ die "$error at $file line $line.\n";
}
{
no strict 'refs';
goto &$AUTOLOAD;
}
+sub import {
+ my $this = shift;
+ for my $i (@_) {
+ if (($i eq 'clock_getres' && !&d_clock_getres) ||
+ ($i eq 'clock_gettime' && !&d_clock_gettime) ||
+ ($i eq 'nanosleep' && !&d_nanosleep) ||
+ ($i eq 'usleep' && !&d_usleep) ||
+ ($i eq 'ualarm' && !&d_ualarm)) {
+ require Carp;
+ Carp::croak("Time::HiRes::$i(): unimplemented in this platform");
+ }
+ }
+ Time::HiRes->export_to_level(1, $this, @_);
+}
+
bootstrap Time::HiRes;
# Preloaded methods go here.
=head1 SYNOPSIS
- use Time::HiRes qw( usleep ualarm gettimeofday tv_interval );
+ use Time::HiRes qw( usleep ualarm gettimeofday tv_interval nanosleep
+ clock_gettime clock_getres );
usleep ($microseconds);
+ nanosleep ($nanoseconds);
ualarm ($microseconds);
ualarm ($microseconds, $interval_microseconds);
setitimer ($which, $floating_seconds, $floating_interval );
getitimer ($which);
-=head1 DESCRIPTION
+ $realtime = clock_gettime(CLOCK_REALTIME);
+ $resolution = clock_getres(CLOCK_REALTIME);
-The C<Time::HiRes> module implements a Perl interface to the usleep,
-ualarm, gettimeofday, and setitimer/getitimer system calls. 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.
+=head1 DESCRIPTION
-If your system lacks gettimeofday(2) or an emulation of it you don't
-get gettimeofday() or the one-arg form of tv_interval(). If you don't
-have nanosleep() or usleep(3) or select(2) you don't get Time::HiRes::usleep()
-or sleep(). If your system don't have ualarm(3) or setitimer(2) you
-don't get Time::HiRes::ualarm() or alarm().
+The C<Time::HiRes> module implements a Perl interface to the
+C<usleep>, C<nanosleep>, C<ualarm>, C<gettimeofday>, and
+C<setitimer>/C<getitimer> system calls, in other words, high
+resolution time and timers. See the L</EXAMPLES> section below and the
+test scripts for usage; see your system documentation for the
+description of the underlying C<nanosleep> or C<usleep>, C<ualarm>,
+C<gettimeofday>, and C<setitimer>/C<getitimer> calls.
+
+If your system lacks C<gettimeofday()> or an emulation of it you don't
+get C<gettimeofday()> or the one-argument form of C<tv_interval()>.
+If your system lacks all of C<nanosleep()>, C<usleep()>,
+C<select()>, and C<poll>, you don't get C<Time::HiRes::usleep()>,
+C<Time::HiRes::nanosleep()>, or C<Time::HiRes::sleep()>.
+If your system lacks both C<ualarm()> and C<setitimer()> you don't get
+C<Time::HiRes::ualarm()> or C<Time::HiRes::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
-behavior, and you should first check for the truth value of
-C<&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 usleep() with small enough values. Also,
-think twice whether using nanosecond accuracies in a Perl program is what
-you should be doing.)
+If your subsecond sleeping is implemented with C<nanosleep()> instead
+of C<usleep()>, you can mix subsecond sleeping with signals since
+C<nanosleep()> does not use signals. This, however, is not portable,
+and you should first check for the truth value of
+C<&Time::HiRes::d_nanosleep> to see whether you have nanosleep, and
+then carefully read your C<nanosleep()> C API documentation for any
+peculiarities.
+
+If you are using C<nanosleep> for something else than mixing sleeping
+with signals, 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 returns a 2 element array with the seconds and
+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).
+seconds like C<Time::HiRes::time()> (see below).
=item usleep ( $useconds )
-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.
+Sleeps for the number of microseconds (millionths of a second)
+specified. Returns the number of microseconds actually slept. Can
+sleep for more than one second, unlike the C<usleep> system call. See
+also C<Time::HiRes::usleep()> and C<Time::HiRes::sleep()>.
+
+Do not expect usleep() to be exact down to one microsecond.
+
+=item nanosleep ( $nanoseconds )
+
+Sleeps for the number of nanoseconds (1e9ths of a second) specified.
+Returns the number of nanoseconds actually slept (accurate only to
+microseconds, the nearest thousand of them). Can sleep for more than
+one second. See also C<Time::HiRes::sleep()> and
+C<Time::HiRes::usleep()>.
+
+Do not expect nanosleep() to be exact down to one nanosecond.
+Getting even accuracy of one thousand nanoseconds is good.
=item ualarm ( $useconds [, $interval_useconds ] )
-Issues a ualarm call; interval_useconds is optional and will be 0 if
-unspecified, resulting in alarm-like behaviour.
+Issues a C<ualarm> call; the C<$interval_useconds> is optional and
+will be zero if unspecified, resulting in C<alarm>-like behaviour.
+
+Note that the interaction between alarms and sleeps is unspecified.
=item tv_interval
-C<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,
+been returned by C<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 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). 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 C<%.6f>, or the gettimeofday() function in list
-context, which will give you the seconds and microseconds as two
-separate values.
+provided with core Perl; see the L</EXAMPLES> below.
+
+B<NOTE 1>: This higher resolution timer can return values either less
+or more than the core C<time()>, depending on whether your platform
+rounds the higher resolution timer values up, down, or to the nearest second
+to get the core C<time()>, but naturally the difference should be never
+more than half a second. See also L</clock_getres>, if available
+in your system.
+
+B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT, when
+the C<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
+C<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 the 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 C<printf>/C<sprintf> with C<"%.6f">, or the
+C<gettimeofday()> function in list context, which will give you the
+seconds and microseconds as two separate values.
=item sleep ( $floating_seconds )
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 C<sleep>
-provided with perl, see the EXAMPLES below.
+seconds actually slept (a floating point value). This function can
+be imported, resulting in a nice drop-in replacement for the C<sleep>
+provided with perl, see the L</EXAMPLES> below.
+
+Note that the interaction between alarms and sleeps is unspecified.
=item alarm ( $floating_seconds [, $interval_floating_seconds ] )
-The SIGALRM signal is sent after the specified number of seconds.
-Implemented using ualarm(). The $interval_floating_seconds argument
-is optional and will be 0 if unspecified, resulting in alarm()-like
+The C<SIGALRM> signal is sent after the specified number of seconds.
+Implemented using C<ualarm()>. The C<$interval_floating_seconds> argument
+is optional and will be zero if unspecified, resulting in C<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 C<alarm> provided with perl, see the L</EXAMPLES> below.
-B<NOTE 1>: With some platform - 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().
+B<NOTE 1>: With some combinations of operating systems and Perl
+releases C<SIGALRM> restarts C<select()>, instead of interrupting it.
+This means that an C<alarm()> followed by a C<select()> may together
+take the sum of the times specified for the the C<alarm()> and the
+C<select()>, not just the time of the C<alarm()>.
-=item setitimer
+Note that the interaction between alarms and sleeps is unspecified.
-C<setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )>
+=item setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )
Start up an interval timer: after a certain time, a signal arrives,
and more signals may keep arriving at certain intervals. To disable
-a timer, use time of zero. If interval is set to zero (or unspecified),
-the timer is disabled B<after> the next delivered signal.
+an "itimer", use C<$floating_seconds> of zero. If the
+C<$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 C<alarm()>, C<sleep()>,
+and C<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 usually three or four interval timers available: the $which
-can be ITIMER_REAL, ITIMER_VIRTUAL, ITIMER_PROF, or ITIMER_REALPROF.
-Note that which ones are available depends: true UNIX platforms have
-usually all first three, but for example Win32 and Cygwin only have
-ITIMER_REAL, and only Solaris seems to have ITIMER_REALPROF (which is
-used to profile multithreaded programs).
+There are usually three or four interval timers available: the
+C<$which> can be C<ITIMER_REAL>, C<ITIMER_VIRTUAL>, C<ITIMER_PROF>, or
+C<ITIMER_REALPROF>. Note that which ones are available depends: true
+UNIX platforms usually have the first three, but (for example) Win32
+and Cygwin have only C<ITIMER_REAL>, and only Solaris seems to have
+C<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
+C<ITIMER_REAL> results in C<alarm()>-like behaviour. Time is counted in
+I<real time>; that is, wallclock time. C<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 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.
+C<ITIMER_VIRTUAL> counts time in (process) I<virtual time>; that is,
+only 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>.) C<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.
+C<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>.) (The sum of user
+time and system time is known as the I<CPU time>.) C<SIGPROF> is
+delivered when the timer expires. C<SIGPROF> can interrupt system calls.
The semantics of interval timers for multithreaded programs are
system-specific, and some systems may support additional interval
-timers. See your setitimer() documentation.
+timers. See your C<setitimer()> documentation.
=item getitimer ( $which )
-Return the remaining time in the interval timer specified by $which.
+Return the remaining time in the interval timer specified by C<$which>.
In scalar context, the remaining time is returned.
In list context, both the remaining time and the interval are returned.
-The interval is always what you put in using setitimer().
+The interval is always what you put in using C<setitimer()>.
+
+=item clock_gettime ( $which )
+
+Return as seconds the current value of the POSIX high resolution timer
+specified by C<$which>. All implementations that support POSIX high
+resolution timers are supposed to support at least the C<$which> value
+of C<CLOCK_REALTIME>, which is supposed to return results close to the
+results of C<gettimeofday>, or the number of seconds since 00:00:00:00
+January 1, 1970 Greenwich Mean Time (GMT). Do not assume that
+CLOCK_REALTIME is zero, it might be one, or something else.
+Another potentially useful (but not available everywhere) value is
+C<CLOCK_MONOTONIC>, which guarantees a monotonically increasing time
+value (unlike time(), which can be adjusted). See your system
+documentation for other possibly supported values.
+
+=item clock_getres ( $which )
+
+Return as seconds the resolution of the POSIX high resolution timer
+specified by C<$which>. All implementations that support POSIX high
+resolution timers are supposed to support at least the C<$which> value
+of C<CLOCK_REALTIME>, see L</clock_gettime>.
=back
use Time::HiRes qw(usleep ualarm gettimeofday tv_interval);
$microseconds = 750_000;
- usleep $microseconds;
+ usleep($microseconds);
# signal alarm in 2.5s & every .1s thereafter
- ualarm 2_500_000, 100_000;
+ ualarm(2_500_000, 100_000);
# get seconds and microseconds since the epoch
- ($s, $usec) = gettimeofday;
+ ($s, $usec) = gettimeofday();
# measure elapsed time
# (could also do by subtracting 2 gettimeofday return values)
$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);
+ use Time::HiRes qw( clock_gettime clock_getres CLOCK_REALTIME );
+ # Read the POSIX high resolution timer.
+ my $high = clock_getres(CLOCK_REALTIME);
+ # But how accurate we can be, really?
+ my $reso = clock_getres(CLOCK_REALTIME);
+
=head1 C API
In addition to the perl API described above, a C API is available for
name C prototype
--------------- ----------------------
Time::NVtime double (*)()
- Time::U2time void (*)(UV ret[2])
+ Time::U2time void (*)(pTHX_ UV ret[2])
Both functions return equivalent information (like C<gettimeofday>)
but with different representations. The names C<NVtime> and C<U2time>
were selected mainly because they are operating system independent.
-(C<gettimeofday> is Un*x-centric.)
+(C<gettimeofday> is Unix-centric, though some platforms like Win32 and
+VMS have emulations for it.)
-Here is an example of using NVtime from C:
+Here is an example of using C<NVtime> from C:
- double (*myNVtime)();
+ double (*myNVtime)(); /* Returns -1 on failure. */
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 = INT2PTR(double(*)(), SvIV(*svp));
printf("The current time is: %f\n", (*myNVtime)());
+=head1 DIAGNOSTICS
+
+=head2 negative time not invented yet
+
+You tried to use a negative time argument.
+
+=head2 internal error: useconds < 0 (unsigned ... signed ...)
+
+Something went horribly wrong-- the number of microseconds that cannot
+become negative just became negative. Maybe your compiler is broken?
+
=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().
+Notice that the core C<time()> maybe rounding rather than truncating.
+What this means is that the core C<time()> may be reporting the time
+as one second later than C<gettimeofday()> and C<Time::HiRes::time()>.
+
+Adjusting the system clock (either manually or by services like ntp)
+may cause problems, especially for long running programs that assume
+a monotonously increasing time (note that all platforms do not adjust
+time as gracefully as UNIX ntp does). For example in Win32 (and derived
+platforms like Cygwin and MinGW) the Time::HiRes::time() may temporarily
+drift off from the system clock (and the original time()) by up to 0.5
+seconds. Time::HiRes will notice this eventually and recalibrate.
+Note that since Time::HiRes 1.77 the clock_gettime(CLOCK_MONOTONIC)
+might help in this (in case your system supports CLOCK_MONOTONIC).
+
+=head1 SEE ALSO
+
+Perl modules L<BSD::Resource>, L<Time::TAI64>.
+
+Your system documentation for C<clock_gettime>, C<clock_settime>,
+C<gettimeofday>, C<getitimer>, C<setitimer>, C<ualarm>.
=head1 AUTHORS
Copyright (c) 1996-2002 Douglas E. Wegscheid. All rights reserved.
-Copyright (c) 2002 Jarkko Hietaniemi. All rights reserved.
+Copyright (c) 2002, 2003, 2004, 2005 Jarkko Hietaniemi. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
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