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 = '1.9765';
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 L<C<Time::HiRes::sleep()>|/sleep ( $floating_seconds )>, and
225 L<C<clock_nanosleep()>|/clock_nanosleep ( $which, $nanoseconds, $flags = 0)>.
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
236 L<C<Time::HiRes::sleep()>|/sleep ( $floating_seconds )>,
237 L<C<Time::HiRes::usleep()>|/usleep ( $useconds )>, and
238 L<C<clock_nanosleep()>|/clock_nanosleep ( $which, $nanoseconds, $flags = 0)>.
240 Do not expect nanosleep() to be exact down to one nanosecond.
241 Getting even accuracy of one thousand nanoseconds is good.
243 =item ualarm ( $useconds [, $interval_useconds ] )
245 Issues a C<ualarm> call; the C<$interval_useconds> is optional and
246 will be zero if unspecified, resulting in C<alarm>-like behaviour.
248 Returns the remaining time in the alarm in microseconds, or C<undef>
249 if an error occurred.
251 ualarm(0) will cancel an outstanding ualarm().
253 Note that the interaction between alarms and sleeps is unspecified.
257 tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] )
259 Returns the floating seconds between the two times, which should have
260 been returned by C<gettimeofday()>. If the second argument is omitted,
261 then the current time is used.
265 Returns a floating seconds since the epoch. This function can be
266 imported, resulting in a nice drop-in replacement for the C<time>
267 provided with core Perl; see the L</EXAMPLES> below.
269 B<NOTE 1>: This higher resolution timer can return values either less
270 or more than the core C<time()>, depending on whether your platform
271 rounds the higher resolution timer values up, down, or to the nearest second
272 to get the core C<time()>, but naturally the difference should be never
273 more than half a second. See also L</clock_getres>, if available
276 B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT, when
277 the C<time()> seconds since epoch rolled over to 1_000_000_000, the
278 default floating point format of Perl and the seconds since epoch have
279 conspired to produce an apparent bug: if you print the value of
280 C<Time::HiRes::time()> you seem to be getting only five decimals, not
281 six as promised (microseconds). Not to worry, the microseconds are
282 there (assuming your platform supports such granularity in the first
283 place). What is going on is that the default floating point format of
284 Perl only outputs 15 digits. In this case that means ten digits
285 before the decimal separator and five after. To see the microseconds
286 you can use either C<printf>/C<sprintf> with C<"%.6f">, or the
287 C<gettimeofday()> function in list context, which will give you the
288 seconds and microseconds as two separate values.
290 =item sleep ( $floating_seconds )
292 Sleeps for the specified amount of seconds. Returns the number of
293 seconds actually slept (a floating point value). This function can
294 be imported, resulting in a nice drop-in replacement for the C<sleep>
295 provided with perl, see the L</EXAMPLES> below.
297 Note that the interaction between alarms and sleeps is unspecified.
299 =item alarm ( $floating_seconds [, $interval_floating_seconds ] )
301 The C<SIGALRM> signal is sent after the specified number of seconds.
302 Implemented using C<setitimer()> if available, C<ualarm()> if not.
303 The C<$interval_floating_seconds> argument is optional and will be
304 zero if unspecified, resulting in C<alarm()>-like behaviour. This
305 function can be imported, resulting in a nice drop-in replacement for
306 the C<alarm> provided with perl, see the L</EXAMPLES> below.
308 Returns the remaining time in the alarm in seconds, or C<undef>
309 if an error occurred.
311 B<NOTE 1>: With some combinations of operating systems and Perl
312 releases C<SIGALRM> restarts C<select()>, instead of interrupting it.
313 This means that an C<alarm()> followed by a C<select()> may together
314 take the sum of the times specified for the C<alarm()> and the
315 C<select()>, not just the time of the C<alarm()>.
317 Note that the interaction between alarms and sleeps is unspecified.
319 =item setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )
321 Start up an interval timer: after a certain time, a signal ($which) arrives,
322 and more signals may keep arriving at certain intervals. To disable
323 an "itimer", use C<$floating_seconds> of zero. If the
324 C<$interval_floating_seconds> is set to zero (or unspecified), the
325 timer is disabled B<after> the next delivered signal.
327 Use of interval timers may interfere with C<alarm()>, C<sleep()>,
328 and C<usleep()>. In standard-speak the "interaction is unspecified",
329 which means that I<anything> may happen: it may work, it may not.
331 In scalar context, the remaining time in the timer is returned.
333 In list context, both the remaining time and the interval are returned.
335 There are usually three or four interval timers (signals) available: the
336 C<$which> can be C<ITIMER_REAL>, C<ITIMER_VIRTUAL>, C<ITIMER_PROF>, or
337 C<ITIMER_REALPROF>. Note that which ones are available depends: true
338 UNIX platforms usually have the first three, but only Solaris seems to
339 have C<ITIMER_REALPROF> (which is used to profile multithreaded programs).
340 Win32 unfortunately does not have interval timers.
342 C<ITIMER_REAL> results in C<alarm()>-like behaviour. Time is counted in
343 I<real time>; that is, wallclock time. C<SIGALRM> is delivered when
346 C<ITIMER_VIRTUAL> counts time in (process) I<virtual time>; that is,
347 only when the process is running. In multiprocessor/user/CPU systems
348 this may be more or less than real or wallclock time. (This time is
349 also known as the I<user time>.) C<SIGVTALRM> is delivered when the
352 C<ITIMER_PROF> counts time when either the process virtual time or when
353 the operating system is running on behalf of the process (such as I/O).
354 (This time is also known as the I<system time>.) (The sum of user
355 time and system time is known as the I<CPU time>.) C<SIGPROF> is
356 delivered when the timer expires. C<SIGPROF> can interrupt system calls.
358 The semantics of interval timers for multithreaded programs are
359 system-specific, and some systems may support additional interval
360 timers. For example, it is unspecified which thread gets the signals.
361 See your L<C<setitimer(2)>> documentation.
363 =item getitimer ( $which )
365 Return the remaining time in the interval timer specified by C<$which>.
367 In scalar context, the remaining time is returned.
369 In list context, both the remaining time and the interval are returned.
370 The interval is always what you put in using C<setitimer()>.
372 =item clock_gettime ( $which )
374 Return as seconds the current value of the POSIX high resolution timer
375 specified by C<$which>. All implementations that support POSIX high
376 resolution timers are supposed to support at least the C<$which> value
377 of C<CLOCK_REALTIME>, which is supposed to return results close to the
378 results of C<gettimeofday>, or the number of seconds since 00:00:00:00
379 January 1, 1970 Greenwich Mean Time (GMT). Do not assume that
380 CLOCK_REALTIME is zero, it might be one, or something else.
381 Another potentially useful (but not available everywhere) value is
382 C<CLOCK_MONOTONIC>, which guarantees a monotonically increasing time
383 value (unlike time() or gettimeofday(), which can be adjusted).
384 See your system documentation for other possibly supported values.
386 =item clock_getres ( $which )
388 Return as seconds the resolution of the POSIX high resolution timer
389 specified by C<$which>. All implementations that support POSIX high
390 resolution timers are supposed to support at least the C<$which> value
391 of C<CLOCK_REALTIME>, see L</clock_gettime>.
393 B<NOTE>: the resolution returned may be highly optimistic. Even if
394 the resolution is high (a small number), all it means is that you'll
395 be able to specify the arguments to clock_gettime() and clock_nanosleep()
396 with that resolution. The system might not actually be able to measure
397 events at that resolution, and the various overheads and the overall system
398 load are certain to affect any timings.
400 =item clock_nanosleep ( $which, $nanoseconds, $flags = 0)
402 Sleeps for the number of nanoseconds (1e9ths of a second) specified.
403 Returns the number of nanoseconds actually slept. The $which is the
404 "clock id", as with clock_gettime() and clock_getres(). The flags
405 default to zero but C<TIMER_ABSTIME> can specified (must be exported
406 explicitly) which means that C<$nanoseconds> is not a time interval
407 (as is the default) but instead an absolute time. Can sleep for more
408 than one second. Can also sleep for zero seconds, which often works
409 like a I<thread yield>. See also
410 L<C<Time::HiRes::sleep()>|/sleep ( $floating_seconds )>,
411 L<C<Time::HiRes::usleep()>|/usleep ( $useconds )>, and
412 L<C<Time::HiRes::nanosleep()>|/nanosleep ( $nanoseconds )>.
414 Do not expect clock_nanosleep() to be exact down to one nanosecond.
415 Getting even accuracy of one thousand nanoseconds is good.
419 Return as seconds the I<process time> (user + system time) spent by
420 the process since the first call to clock() (the definition is B<not>
421 "since the start of the process", though if you are lucky these times
422 may be quite close to each other, depending on the system). What this
423 means is that you probably need to store the result of your first call
424 to clock(), and subtract that value from the following results of clock().
426 The time returned also includes the process times of the terminated
427 child processes for which wait() has been executed. This value is
428 somewhat like the second value returned by the times() of core Perl,
429 but not necessarily identical. Note that due to backward
430 compatibility limitations the returned value may wrap around at about
431 2147 seconds or at about 36 minutes.
445 As L<perlfunc/stat> or L<perlfunc/lstat>
446 but with the access/modify/change file timestamps
447 in subsecond resolution, if the operating system and the filesystem
448 both support such timestamps. To override the standard stat():
450 use Time::HiRes qw(stat);
452 Test for the value of &Time::HiRes::d_hires_stat to find out whether
453 the operating system supports subsecond file timestamps: a value
454 larger than zero means yes. There are unfortunately no easy
455 ways to find out whether the filesystem supports such timestamps.
456 UNIX filesystems often do; NTFS does; FAT doesn't (FAT timestamp
457 granularity is B<two> seconds).
459 A zero return value of &Time::HiRes::d_hires_stat means that
460 Time::HiRes::stat is a no-op passthrough for CORE::stat()
461 (and likewise for lstat),
462 and therefore the timestamps will stay integers. The same
463 thing will happen if the filesystem does not do subsecond timestamps,
464 even if the &Time::HiRes::d_hires_stat is non-zero.
466 In any case do not expect nanosecond resolution, or even a microsecond
467 resolution. Also note that the modify/access timestamps might have
468 different resolutions, and that they need not be synchronized, e.g.
469 if the operations are
476 the access time stamp from t2 need not be greater-than the modify
477 time stamp from t1: it may be equal or I<less>.
482 but with the ability to set the access/modify file timestamps
483 in subsecond resolution, if the operating system and the filesystem,
484 and the mount options of the filesystem, all support such timestamps.
486 To override the standard utime():
488 use Time::HiRes qw(utime);
490 Test for the value of &Time::HiRes::d_hires_utime to find out whether
491 the operating system supports setting subsecond file timestamps.
493 As with CORE::utime(), passing undef as both the atime and mtime will
494 call the syscall with a NULL argument.
496 The actual achievable subsecond resolution depends on the combination
497 of the operating system and the filesystem.
499 Modifying the timestamps may not be possible at all: for example, the
500 C<noatime> filesystem mount option may prohibit you from changing the
501 access time timestamp.
503 Returns the number of files successfully changed.
509 use Time::HiRes qw(usleep ualarm gettimeofday tv_interval);
511 $microseconds = 750_000;
512 usleep($microseconds);
514 # signal alarm in 2.5s & every .1s thereafter
515 ualarm(2_500_000, 100_000);
519 # get seconds and microseconds since the epoch
520 ($s, $usec) = gettimeofday();
522 # measure elapsed time
523 # (could also do by subtracting 2 gettimeofday return values)
524 $t0 = [gettimeofday];
525 # do bunch of stuff here
526 $t1 = [gettimeofday];
528 $t0_t1 = tv_interval $t0, $t1;
530 $elapsed = tv_interval ($t0, [gettimeofday]);
531 $elapsed = tv_interval ($t0); # equivalent code
534 # replacements for time, alarm and sleep that know about
538 $now_fractions = Time::HiRes::time;
539 Time::HiRes::sleep (2.5);
540 Time::HiRes::alarm (10.6666666);
542 use Time::HiRes qw ( time alarm sleep );
543 $now_fractions = time;
547 # Arm an interval timer to go off first at 10 seconds and
548 # after that every 2.5 seconds, in process virtual time
550 use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time );
552 $SIG{VTALRM} = sub { print time, "\n" };
553 setitimer(ITIMER_VIRTUAL, 10, 2.5);
555 use Time::HiRes qw( clock_gettime clock_getres CLOCK_REALTIME );
556 # Read the POSIX high resolution timer.
557 my $high = clock_gettime(CLOCK_REALTIME);
558 # But how accurate we can be, really?
559 my $reso = clock_getres(CLOCK_REALTIME);
561 use Time::HiRes qw( clock_nanosleep TIMER_ABSTIME );
562 clock_nanosleep(CLOCK_REALTIME, 1e6);
563 clock_nanosleep(CLOCK_REALTIME, 2e9, TIMER_ABSTIME);
565 use Time::HiRes qw( clock );
566 my $clock0 = clock();
568 my $clock1 = clock();
569 my $clockd = $clock1 - $clock0;
571 use Time::HiRes qw( stat );
572 my ($atime, $mtime, $ctime) = (stat("istics"))[8, 9, 10];
576 In addition to the perl API described above, a C API is available for
577 extension writers. The following C functions are available in the
581 --------------- ----------------------
582 Time::NVtime NV (*)()
583 Time::U2time void (*)(pTHX_ UV ret[2])
585 Both functions return equivalent information (like C<gettimeofday>)
586 but with different representations. The names C<NVtime> and C<U2time>
587 were selected mainly because they are operating system independent.
588 (C<gettimeofday> is Unix-centric, though some platforms like Win32 and
589 VMS have emulations for it.)
591 Here is an example of using C<NVtime> from C:
593 NV (*myNVtime)(); /* Returns -1 on failure. */
594 SV **svp = hv_fetchs(PL_modglobal, "Time::NVtime", 0);
595 if (!svp) croak("Time::HiRes is required");
596 if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer");
597 myNVtime = INT2PTR(NV(*)(), SvIV(*svp));
598 printf("The current time is: %" NVff "\n", (*myNVtime)());
602 =head2 useconds or interval more than ...
604 In ualarm() you tried to use number of microseconds or interval (also
605 in microseconds) more than 1_000_000 and setitimer() is not available
606 in your system to emulate that case.
608 =head2 negative time not invented yet
610 You tried to use a negative time argument.
612 =head2 internal error: useconds < 0 (unsigned ... signed ...)
614 Something went horribly wrong-- the number of microseconds that cannot
615 become negative just became negative. Maybe your compiler is broken?
617 =head2 useconds or uinterval equal to or more than 1000000
619 In some platforms it is not possible to get an alarm with subsecond
620 resolution and later than one second.
622 =head2 unimplemented in this platform
624 Some calls simply aren't available, real or emulated, on every platform.
628 Notice that the core C<time()> maybe rounding rather than truncating.
629 What this means is that the core C<time()> may be reporting the time
630 as one second later than C<gettimeofday()> and C<Time::HiRes::time()>.
632 Adjusting the system clock (either manually or by services like ntp)
633 may cause problems, especially for long running programs that assume
634 a monotonously increasing time (note that all platforms do not adjust
635 time as gracefully as UNIX ntp does). For example in Win32 (and derived
636 platforms like Cygwin and MinGW) the Time::HiRes::time() may temporarily
637 drift off from the system clock (and the original time()) by up to 0.5
638 seconds. Time::HiRes will notice this eventually and recalibrate.
639 Note that since Time::HiRes 1.77 the clock_gettime(CLOCK_MONOTONIC)
640 might help in this (in case your system supports CLOCK_MONOTONIC).
642 Some systems have APIs but not implementations: for example QNX and Haiku
643 have the interval timer APIs but not the functionality.
645 In pre-Sierra macOS (pre-10.12, OS X) clock_getres(), clock_gettime()
646 and clock_nanosleep() are emulated using the Mach timers; as a side
647 effect of being emulated the CLOCK_REALTIME and CLOCK_MONOTONIC are
650 gnukfreebsd seems to have non-functional futimens() and utimensat()
651 (at least as of 10.1): therefore the hires utime() does not work.
655 Perl modules L<BSD::Resource>, L<Time::TAI64>.
657 Your system documentation for L<C<clock(3)>>, L<C<clock_gettime(2)>>,
658 L<C<clock_getres(3)>>, L<C<clock_nanosleep(3)>>, L<C<clock_settime(2)>>,
659 L<C<getitimer(2)>>, L<C<gettimeofday(2)>>, L<C<setitimer(2)>>, L<C<sleep(3)>>,
660 L<C<stat(2)>>, L<C<ualarm(3)>>.
664 D. Wegscheid <wegscd@whirlpool.com>
665 R. Schertler <roderick@argon.org>
666 J. Hietaniemi <jhi@iki.fi>
667 G. Aas <gisle@aas.no>
669 =head1 COPYRIGHT AND LICENSE
671 Copyright (c) 1996-2002 Douglas E. Wegscheid. All rights reserved.
673 Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 Jarkko Hietaniemi.
676 Copyright (C) 2011, 2012, 2013 Andrew Main (Zefram) <zefram@fysh.org>
678 This program is free software; you can redistribute it and/or modify
679 it under the same terms as Perl itself.