9 our @ISA = qw(Exporter);
12 # More or less this same list is in Makefile.PL. Should unify.
13 our @EXPORT_OK = qw (usleep sleep ualarm alarm gettimeofday time tv_interval
14 getitimer setitimer nanosleep clock_gettime clock_getres
20 CLOCK_MONOTONIC_COARSE
22 CLOCK_MONOTONIC_PRECISE
24 CLOCK_PROCESS_CPUTIME_ID
29 CLOCK_REALTIME_PRECISE
33 CLOCK_THREAD_CPUTIME_ID
46 d_usleep d_ualarm d_gettimeofday d_getitimer d_setitimer
47 d_nanosleep d_clock_gettime d_clock_getres
48 d_clock d_clock_nanosleep d_hires_stat
49 d_futimens d_utimensat d_hires_utime
53 our $VERSION = '1.9760';
54 our $XS_VERSION = $VERSION;
55 $VERSION = eval $VERSION;
60 ($constname = $AUTOLOAD) =~ s/.*:://;
61 # print "AUTOLOAD: constname = $constname ($AUTOLOAD)\n";
62 die "&Time::HiRes::constant not defined" if $constname eq 'constant';
63 my ($error, $val) = constant($constname);
64 # print "AUTOLOAD: error = $error, val = $val\n";
66 my (undef,$file,$line) = caller;
67 die "$error at $file line $line.\n";
71 *$AUTOLOAD = sub { $val };
79 if (($i eq 'clock_getres' && !&d_clock_getres) ||
80 ($i eq 'clock_gettime' && !&d_clock_gettime) ||
81 ($i eq 'clock_nanosleep' && !&d_clock_nanosleep) ||
82 ($i eq 'clock' && !&d_clock) ||
83 ($i eq 'nanosleep' && !&d_nanosleep) ||
84 ($i eq 'usleep' && !&d_usleep) ||
85 ($i eq 'utime' && !&d_hires_utime) ||
86 ($i eq 'ualarm' && !&d_ualarm)) {
88 Carp::croak("Time::HiRes::$i(): unimplemented in this platform");
91 Time::HiRes->export_to_level(1, $this, @_);
94 XSLoader::load( 'Time::HiRes', $XS_VERSION );
96 # Preloaded methods go here.
99 # probably could have been done in C
101 $b = [gettimeofday()] unless defined($b);
102 (${$b}[0] - ${$a}[0]) + ((${$b}[1] - ${$a}[1]) / 1_000_000);
105 # Autoload methods go after =cut, and are processed by the autosplit program.
112 Time::HiRes - High resolution alarm, sleep, gettimeofday, interval timers
116 use Time::HiRes qw( usleep ualarm gettimeofday tv_interval nanosleep
117 clock_gettime clock_getres clock_nanosleep clock
120 usleep ($microseconds);
121 nanosleep ($nanoseconds);
123 ualarm ($microseconds);
124 ualarm ($microseconds, $interval_microseconds);
126 $t0 = [gettimeofday];
127 ($seconds, $microseconds) = gettimeofday;
129 $elapsed = tv_interval ( $t0, [$seconds, $microseconds]);
130 $elapsed = tv_interval ( $t0, [gettimeofday]);
131 $elapsed = tv_interval ( $t0 );
133 use Time::HiRes qw ( time alarm sleep );
135 $now_fractions = time;
136 sleep ($floating_seconds);
137 alarm ($floating_seconds);
138 alarm ($floating_seconds, $floating_interval);
140 use Time::HiRes qw( setitimer getitimer );
142 setitimer ($which, $floating_seconds, $floating_interval );
145 use Time::HiRes qw( clock_gettime clock_getres clock_nanosleep
146 ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF
149 $realtime = clock_gettime(CLOCK_REALTIME);
150 $resolution = clock_getres(CLOCK_REALTIME);
152 clock_nanosleep(CLOCK_REALTIME, 1.5e9);
153 clock_nanosleep(CLOCK_REALTIME, time()*1e9 + 10e9, TIMER_ABSTIME);
155 my $ticktock = clock();
157 use Time::HiRes qw( stat lstat );
159 my @stat = stat("file");
161 my @stat = lstat("file");
163 use Time::HiRes qw( utime );
164 utime $floating_seconds, $floating_seconds, file...;
168 The C<Time::HiRes> module implements a Perl interface to the
169 C<usleep>, C<nanosleep>, C<ualarm>, C<gettimeofday>, and
170 C<setitimer>/C<getitimer> system calls, in other words, high
171 resolution time and timers. See the L</EXAMPLES> section below and the
172 test scripts for usage; see your system documentation for the
173 description of the underlying C<nanosleep> or C<usleep>, C<ualarm>,
174 C<gettimeofday>, and C<setitimer>/C<getitimer> calls.
176 If your system lacks C<gettimeofday()> or an emulation of it you don't
177 get C<gettimeofday()> or the one-argument form of C<tv_interval()>.
178 If your system lacks all of C<nanosleep()>, C<usleep()>,
179 C<select()>, and C<poll>, you don't get C<Time::HiRes::usleep()>,
180 C<Time::HiRes::nanosleep()>, or C<Time::HiRes::sleep()>.
181 If your system lacks both C<ualarm()> and C<setitimer()> you don't get
182 C<Time::HiRes::ualarm()> or C<Time::HiRes::alarm()>.
184 If you try to import an unimplemented function in the C<use> statement
185 it will fail at compile time.
187 If your subsecond sleeping is implemented with C<nanosleep()> instead
188 of C<usleep()>, you can mix subsecond sleeping with signals since
189 C<nanosleep()> does not use signals. This, however, is not portable,
190 and you should first check for the truth value of
191 C<&Time::HiRes::d_nanosleep> to see whether you have nanosleep, and
192 then carefully read your C<nanosleep()> C API documentation for any
195 If you are using C<nanosleep> for something else than mixing sleeping
196 with signals, give some thought to whether Perl is the tool you should
197 be using for work requiring nanosecond accuracies.
199 Remember that unless you are working on a I<hard realtime> system,
200 any clocks and timers will be imprecise, especially so if you are working
201 in a pre-emptive multiuser system. Understand the difference between
202 I<wallclock time> and process time (in UNIX-like systems the sum of
203 I<user> and I<system> times). Any attempt to sleep for X seconds will
204 most probably end up sleeping B<more> than that, but don't be surprised
205 if you end up sleeping slightly B<less>.
207 The following functions can be imported from this module.
208 No functions are exported by default.
212 =item gettimeofday ()
214 In array context returns a two-element array with the seconds and
215 microseconds since the epoch. In scalar context returns floating
216 seconds like C<Time::HiRes::time()> (see below).
218 =item usleep ( $useconds )
220 Sleeps for the number of microseconds (millionths of a second)
221 specified. Returns the number of microseconds actually slept.
222 Can sleep for more than one second, unlike the C<usleep> system call.
223 Can also sleep for zero seconds, which often works like a I<thread yield>.
224 See also C<Time::HiRes::usleep()>, C<Time::HiRes::sleep()>, and
225 C<Time::HiRes::clock_nanosleep()>.
227 Do not expect usleep() to be exact down to one microsecond.
229 =item nanosleep ( $nanoseconds )
231 Sleeps for the number of nanoseconds (1e9ths of a second) specified.
232 Returns the number of nanoseconds actually slept (accurate only to
233 microseconds, the nearest thousand of them). Can sleep for more than
234 one second. Can also sleep for zero seconds, which often works like
235 a I<thread yield>. See also C<Time::HiRes::sleep()>,
236 C<Time::HiRes::usleep()>, and C<Time::HiRes::clock_nanosleep()>.
238 Do not expect nanosleep() to be exact down to one nanosecond.
239 Getting even accuracy of one thousand nanoseconds is good.
241 =item ualarm ( $useconds [, $interval_useconds ] )
243 Issues a C<ualarm> call; the C<$interval_useconds> is optional and
244 will be zero if unspecified, resulting in C<alarm>-like behaviour.
246 Returns the remaining time in the alarm in microseconds, or C<undef>
247 if an error occurred.
249 ualarm(0) will cancel an outstanding ualarm().
251 Note that the interaction between alarms and sleeps is unspecified.
255 tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] )
257 Returns the floating seconds between the two times, which should have
258 been returned by C<gettimeofday()>. If the second argument is omitted,
259 then the current time is used.
263 Returns a floating seconds since the epoch. This function can be
264 imported, resulting in a nice drop-in replacement for the C<time>
265 provided with core Perl; see the L</EXAMPLES> below.
267 B<NOTE 1>: This higher resolution timer can return values either less
268 or more than the core C<time()>, depending on whether your platform
269 rounds the higher resolution timer values up, down, or to the nearest second
270 to get the core C<time()>, but naturally the difference should be never
271 more than half a second. See also L</clock_getres>, if available
274 B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT, when
275 the C<time()> seconds since epoch rolled over to 1_000_000_000, the
276 default floating point format of Perl and the seconds since epoch have
277 conspired to produce an apparent bug: if you print the value of
278 C<Time::HiRes::time()> you seem to be getting only five decimals, not
279 six as promised (microseconds). Not to worry, the microseconds are
280 there (assuming your platform supports such granularity in the first
281 place). What is going on is that the default floating point format of
282 Perl only outputs 15 digits. In this case that means ten digits
283 before the decimal separator and five after. To see the microseconds
284 you can use either C<printf>/C<sprintf> with C<"%.6f">, or the
285 C<gettimeofday()> function in list context, which will give you the
286 seconds and microseconds as two separate values.
288 =item sleep ( $floating_seconds )
290 Sleeps for the specified amount of seconds. Returns the number of
291 seconds actually slept (a floating point value). This function can
292 be imported, resulting in a nice drop-in replacement for the C<sleep>
293 provided with perl, see the L</EXAMPLES> below.
295 Note that the interaction between alarms and sleeps is unspecified.
297 =item alarm ( $floating_seconds [, $interval_floating_seconds ] )
299 The C<SIGALRM> signal is sent after the specified number of seconds.
300 Implemented using C<setitimer()> if available, C<ualarm()> if not.
301 The C<$interval_floating_seconds> argument is optional and will be
302 zero if unspecified, resulting in C<alarm()>-like behaviour. This
303 function can be imported, resulting in a nice drop-in replacement for
304 the C<alarm> provided with perl, see the L</EXAMPLES> below.
306 Returns the remaining time in the alarm in seconds, or C<undef>
307 if an error occurred.
309 B<NOTE 1>: With some combinations of operating systems and Perl
310 releases C<SIGALRM> restarts C<select()>, instead of interrupting it.
311 This means that an C<alarm()> followed by a C<select()> may together
312 take the sum of the times specified for the C<alarm()> and the
313 C<select()>, not just the time of the C<alarm()>.
315 Note that the interaction between alarms and sleeps is unspecified.
317 =item setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )
319 Start up an interval timer: after a certain time, a signal ($which) arrives,
320 and more signals may keep arriving at certain intervals. To disable
321 an "itimer", use C<$floating_seconds> of zero. If the
322 C<$interval_floating_seconds> is set to zero (or unspecified), the
323 timer is disabled B<after> the next delivered signal.
325 Use of interval timers may interfere with C<alarm()>, C<sleep()>,
326 and C<usleep()>. In standard-speak the "interaction is unspecified",
327 which means that I<anything> may happen: it may work, it may not.
329 In scalar context, the remaining time in the timer is returned.
331 In list context, both the remaining time and the interval are returned.
333 There are usually three or four interval timers (signals) available: the
334 C<$which> can be C<ITIMER_REAL>, C<ITIMER_VIRTUAL>, C<ITIMER_PROF>, or
335 C<ITIMER_REALPROF>. Note that which ones are available depends: true
336 UNIX platforms usually have the first three, but only Solaris seems to
337 have C<ITIMER_REALPROF> (which is used to profile multithreaded programs).
338 Win32 unfortunately does not have interval timers.
340 C<ITIMER_REAL> results in C<alarm()>-like behaviour. Time is counted in
341 I<real time>; that is, wallclock time. C<SIGALRM> is delivered when
344 C<ITIMER_VIRTUAL> counts time in (process) I<virtual time>; that is,
345 only when the process is running. In multiprocessor/user/CPU systems
346 this may be more or less than real or wallclock time. (This time is
347 also known as the I<user time>.) C<SIGVTALRM> is delivered when the
350 C<ITIMER_PROF> counts time when either the process virtual time or when
351 the operating system is running on behalf of the process (such as I/O).
352 (This time is also known as the I<system time>.) (The sum of user
353 time and system time is known as the I<CPU time>.) C<SIGPROF> is
354 delivered when the timer expires. C<SIGPROF> can interrupt system calls.
356 The semantics of interval timers for multithreaded programs are
357 system-specific, and some systems may support additional interval
358 timers. For example, it is unspecified which thread gets the signals.
359 See your C<setitimer()> documentation.
361 =item getitimer ( $which )
363 Return the remaining time in the interval timer specified by C<$which>.
365 In scalar context, the remaining time is returned.
367 In list context, both the remaining time and the interval are returned.
368 The interval is always what you put in using C<setitimer()>.
370 =item clock_gettime ( $which )
372 Return as seconds the current value of the POSIX high resolution timer
373 specified by C<$which>. All implementations that support POSIX high
374 resolution timers are supposed to support at least the C<$which> value
375 of C<CLOCK_REALTIME>, which is supposed to return results close to the
376 results of C<gettimeofday>, or the number of seconds since 00:00:00:00
377 January 1, 1970 Greenwich Mean Time (GMT). Do not assume that
378 CLOCK_REALTIME is zero, it might be one, or something else.
379 Another potentially useful (but not available everywhere) value is
380 C<CLOCK_MONOTONIC>, which guarantees a monotonically increasing time
381 value (unlike time() or gettimeofday(), which can be adjusted).
382 See your system documentation for other possibly supported values.
384 =item clock_getres ( $which )
386 Return as seconds the resolution of the POSIX high resolution timer
387 specified by C<$which>. All implementations that support POSIX high
388 resolution timers are supposed to support at least the C<$which> value
389 of C<CLOCK_REALTIME>, see L</clock_gettime>.
391 B<NOTE>: the resolution returned may be highly optimistic. Even if
392 the resolution is high (a small number), all it means is that you'll
393 be able to specify the arguments to clock_gettime() and clock_nanosleep()
394 with that resolution. The system might not actually be able to measure
395 events at that resolution, and the various overheads and the overall system
396 load are certain to affect any timings.
398 =item clock_nanosleep ( $which, $nanoseconds, $flags = 0)
400 Sleeps for the number of nanoseconds (1e9ths of a second) specified.
401 Returns the number of nanoseconds actually slept. The $which is the
402 "clock id", as with clock_gettime() and clock_getres(). The flags
403 default to zero but C<TIMER_ABSTIME> can specified (must be exported
404 explicitly) which means that C<$nanoseconds> is not a time interval
405 (as is the default) but instead an absolute time. Can sleep for more
406 than one second. Can also sleep for zero seconds, which often works
407 like a I<thread yield>. See also C<Time::HiRes::sleep()>,
408 C<Time::HiRes::usleep()>, and C<Time::HiRes::nanosleep()>.
410 Do not expect clock_nanosleep() to be exact down to one nanosecond.
411 Getting even accuracy of one thousand nanoseconds is good.
415 Return as seconds the I<process time> (user + system time) spent by
416 the process since the first call to clock() (the definition is B<not>
417 "since the start of the process", though if you are lucky these times
418 may be quite close to each other, depending on the system). What this
419 means is that you probably need to store the result of your first call
420 to clock(), and subtract that value from the following results of clock().
422 The time returned also includes the process times of the terminated
423 child processes for which wait() has been executed. This value is
424 somewhat like the second value returned by the times() of core Perl,
425 but not necessarily identical. Note that due to backward
426 compatibility limitations the returned value may wrap around at about
427 2147 seconds or at about 36 minutes.
441 As L<perlfunc/stat> or L<perlfunc/lstat>
442 but with the access/modify/change file timestamps
443 in subsecond resolution, if the operating system and the filesystem
444 both support such timestamps. To override the standard stat():
446 use Time::HiRes qw(stat);
448 Test for the value of &Time::HiRes::d_hires_stat to find out whether
449 the operating system supports subsecond file timestamps: a value
450 larger than zero means yes. There are unfortunately no easy
451 ways to find out whether the filesystem supports such timestamps.
452 UNIX filesystems often do; NTFS does; FAT doesn't (FAT timestamp
453 granularity is B<two> seconds).
455 A zero return value of &Time::HiRes::d_hires_stat means that
456 Time::HiRes::stat is a no-op passthrough for CORE::stat()
457 (and likewise for lstat),
458 and therefore the timestamps will stay integers. The same
459 thing will happen if the filesystem does not do subsecond timestamps,
460 even if the &Time::HiRes::d_hires_stat is non-zero.
462 In any case do not expect nanosecond resolution, or even a microsecond
463 resolution. Also note that the modify/access timestamps might have
464 different resolutions, and that they need not be synchronized, e.g.
465 if the operations are
472 the access time stamp from t2 need not be greater-than the modify
473 time stamp from t1: it may be equal or I<less>.
478 but with the ability to set the access/modify file timestamps
479 in subsecond resolution, if the operating system and the filesystem,
480 and the mount options of the filesystem, all support such timestamps.
482 To override the standard utime():
484 use Time::HiRes qw(utime);
486 Test for the value of &Time::HiRes::d_hires_utime to find out whether
487 the operating system supports setting subsecond file timestamps.
489 As with CORE::utime(), passing undef as both the atime and mtime will
490 call the syscall with a NULL argument.
492 The actual achievable subsecond resolution depends on the combination
493 of the operating system and the filesystem.
495 Modifying the timestamps may not be possible at all: for example, the
496 C<noatime> filesystem mount option may prohibit you from changing the
497 access time timestamp.
499 Returns the number of files successfully changed.
505 use Time::HiRes qw(usleep ualarm gettimeofday tv_interval);
507 $microseconds = 750_000;
508 usleep($microseconds);
510 # signal alarm in 2.5s & every .1s thereafter
511 ualarm(2_500_000, 100_000);
515 # get seconds and microseconds since the epoch
516 ($s, $usec) = gettimeofday();
518 # measure elapsed time
519 # (could also do by subtracting 2 gettimeofday return values)
520 $t0 = [gettimeofday];
521 # do bunch of stuff here
522 $t1 = [gettimeofday];
524 $t0_t1 = tv_interval $t0, $t1;
526 $elapsed = tv_interval ($t0, [gettimeofday]);
527 $elapsed = tv_interval ($t0); # equivalent code
530 # replacements for time, alarm and sleep that know about
534 $now_fractions = Time::HiRes::time;
535 Time::HiRes::sleep (2.5);
536 Time::HiRes::alarm (10.6666666);
538 use Time::HiRes qw ( time alarm sleep );
539 $now_fractions = time;
543 # Arm an interval timer to go off first at 10 seconds and
544 # after that every 2.5 seconds, in process virtual time
546 use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time );
548 $SIG{VTALRM} = sub { print time, "\n" };
549 setitimer(ITIMER_VIRTUAL, 10, 2.5);
551 use Time::HiRes qw( clock_gettime clock_getres CLOCK_REALTIME );
552 # Read the POSIX high resolution timer.
553 my $high = clock_gettime(CLOCK_REALTIME);
554 # But how accurate we can be, really?
555 my $reso = clock_getres(CLOCK_REALTIME);
557 use Time::HiRes qw( clock_nanosleep TIMER_ABSTIME );
558 clock_nanosleep(CLOCK_REALTIME, 1e6);
559 clock_nanosleep(CLOCK_REALTIME, 2e9, TIMER_ABSTIME);
561 use Time::HiRes qw( clock );
562 my $clock0 = clock();
564 my $clock1 = clock();
565 my $clockd = $clock1 - $clock0;
567 use Time::HiRes qw( stat );
568 my ($atime, $mtime, $ctime) = (stat("istics"))[8, 9, 10];
572 In addition to the perl API described above, a C API is available for
573 extension writers. The following C functions are available in the
577 --------------- ----------------------
578 Time::NVtime NV (*)()
579 Time::U2time void (*)(pTHX_ UV ret[2])
581 Both functions return equivalent information (like C<gettimeofday>)
582 but with different representations. The names C<NVtime> and C<U2time>
583 were selected mainly because they are operating system independent.
584 (C<gettimeofday> is Unix-centric, though some platforms like Win32 and
585 VMS have emulations for it.)
587 Here is an example of using C<NVtime> from C:
589 NV (*myNVtime)(); /* Returns -1 on failure. */
590 SV **svp = hv_fetchs(PL_modglobal, "Time::NVtime", 0);
591 if (!svp) croak("Time::HiRes is required");
592 if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer");
593 myNVtime = INT2PTR(NV(*)(), SvIV(*svp));
594 printf("The current time is: %" NVff "\n", (*myNVtime)());
598 =head2 useconds or interval more than ...
600 In ualarm() you tried to use number of microseconds or interval (also
601 in microseconds) more than 1_000_000 and setitimer() is not available
602 in your system to emulate that case.
604 =head2 negative time not invented yet
606 You tried to use a negative time argument.
608 =head2 internal error: useconds < 0 (unsigned ... signed ...)
610 Something went horribly wrong-- the number of microseconds that cannot
611 become negative just became negative. Maybe your compiler is broken?
613 =head2 useconds or uinterval equal to or more than 1000000
615 In some platforms it is not possible to get an alarm with subsecond
616 resolution and later than one second.
618 =head2 unimplemented in this platform
620 Some calls simply aren't available, real or emulated, on every platform.
624 Notice that the core C<time()> maybe rounding rather than truncating.
625 What this means is that the core C<time()> may be reporting the time
626 as one second later than C<gettimeofday()> and C<Time::HiRes::time()>.
628 Adjusting the system clock (either manually or by services like ntp)
629 may cause problems, especially for long running programs that assume
630 a monotonously increasing time (note that all platforms do not adjust
631 time as gracefully as UNIX ntp does). For example in Win32 (and derived
632 platforms like Cygwin and MinGW) the Time::HiRes::time() may temporarily
633 drift off from the system clock (and the original time()) by up to 0.5
634 seconds. Time::HiRes will notice this eventually and recalibrate.
635 Note that since Time::HiRes 1.77 the clock_gettime(CLOCK_MONOTONIC)
636 might help in this (in case your system supports CLOCK_MONOTONIC).
638 Some systems have APIs but not implementations: for example QNX and Haiku
639 have the interval timer APIs but not the functionality.
641 In pre-Sierra macOS (pre-10.12, OS X) clock_getres(), clock_gettime()
642 and clock_nanosleep() are emulated using the Mach timers; as a side
643 effect of being emulated the CLOCK_REALTIME and CLOCK_MONOTONIC are
646 gnukfreebsd seems to have non-functional futimens() and utimensat()
647 (at least as of 10.1): therefore the hires utime() does not work.
651 Perl modules L<BSD::Resource>, L<Time::TAI64>.
653 Your system documentation for C<clock>, C<clock_gettime>,
654 C<clock_getres>, C<clock_nanosleep>, C<clock_settime>, C<getitimer>,
655 C<gettimeofday>, C<setitimer>, C<sleep>, C<stat>, C<ualarm>.
659 D. Wegscheid <wegscd@whirlpool.com>
660 R. Schertler <roderick@argon.org>
661 J. Hietaniemi <jhi@iki.fi>
662 G. Aas <gisle@aas.no>
664 =head1 COPYRIGHT AND LICENSE
666 Copyright (c) 1996-2002 Douglas E. Wegscheid. All rights reserved.
668 Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 Jarkko Hietaniemi.
671 Copyright (C) 2011, 2012, 2013 Andrew Main (Zefram) <zefram@fysh.org>
673 This program is free software; you can redistribute it and/or modify
674 it under the same terms as Perl itself.