9 our @ISA = qw(Exporter DynaLoader);
12 our @EXPORT_OK = qw (usleep sleep ualarm alarm gettimeofday time tv_interval
13 getitimer setitimer nanosleep clock_gettime clock_getres
15 CLOCK_BOOTTIME CLOCK_HIGHRES
16 CLOCK_MONOTONIC CLOCK_MONOTONIC_COARSE
17 CLOCK_MONOTONIC_PRECISE CLOCK_MONOTONIC_RAW
18 CLOCK_PROCESS_CPUTIME_ID
19 CLOCK_REALTIME CLOCK_REALTIME_COARSE
20 CLOCK_REALTIME_FAST CLOCK_REALTIME_PRECISE
21 CLOCK_SECOND CLOCK_SOFTTIME CLOCK_THREAD_CPUTIME_ID
22 CLOCK_TIMEOFDAY CLOCKS_PER_SEC
23 ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF ITIMER_REALPROF
25 d_usleep d_ualarm d_gettimeofday d_getitimer d_setitimer
26 d_nanosleep d_clock_gettime d_clock_getres
27 d_clock d_clock_nanosleep
31 our $VERSION = '1.9733';
32 our $XS_VERSION = $VERSION;
33 $VERSION = eval $VERSION;
38 ($constname = $AUTOLOAD) =~ s/.*:://;
39 # print "AUTOLOAD: constname = $constname ($AUTOLOAD)\n";
40 die "&Time::HiRes::constant not defined" if $constname eq 'constant';
41 my ($error, $val) = constant($constname);
42 # print "AUTOLOAD: error = $error, val = $val\n";
44 my (undef,$file,$line) = caller;
45 die "$error at $file line $line.\n";
49 *$AUTOLOAD = sub { $val };
57 if (($i eq 'clock_getres' && !&d_clock_getres) ||
58 ($i eq 'clock_gettime' && !&d_clock_gettime) ||
59 ($i eq 'clock_nanosleep' && !&d_clock_nanosleep) ||
60 ($i eq 'clock' && !&d_clock) ||
61 ($i eq 'nanosleep' && !&d_nanosleep) ||
62 ($i eq 'usleep' && !&d_usleep) ||
63 ($i eq 'ualarm' && !&d_ualarm)) {
65 Carp::croak("Time::HiRes::$i(): unimplemented in this platform");
68 Time::HiRes->export_to_level(1, $this, @_);
71 bootstrap Time::HiRes;
73 # Preloaded methods go here.
76 # probably could have been done in C
78 $b = [gettimeofday()] unless defined($b);
79 (${$b}[0] - ${$a}[0]) + ((${$b}[1] - ${$a}[1]) / 1_000_000);
82 # Autoload methods go after =cut, and are processed by the autosplit program.
89 Time::HiRes - High resolution alarm, sleep, gettimeofday, interval timers
93 use Time::HiRes qw( usleep ualarm gettimeofday tv_interval nanosleep
94 clock_gettime clock_getres clock_nanosleep clock
97 usleep ($microseconds);
98 nanosleep ($nanoseconds);
100 ualarm ($microseconds);
101 ualarm ($microseconds, $interval_microseconds);
103 $t0 = [gettimeofday];
104 ($seconds, $microseconds) = gettimeofday;
106 $elapsed = tv_interval ( $t0, [$seconds, $microseconds]);
107 $elapsed = tv_interval ( $t0, [gettimeofday]);
108 $elapsed = tv_interval ( $t0 );
110 use Time::HiRes qw ( time alarm sleep );
112 $now_fractions = time;
113 sleep ($floating_seconds);
114 alarm ($floating_seconds);
115 alarm ($floating_seconds, $floating_interval);
117 use Time::HiRes qw( setitimer getitimer );
119 setitimer ($which, $floating_seconds, $floating_interval );
122 use Time::HiRes qw( clock_gettime clock_getres clock_nanosleep
123 ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF
126 $realtime = clock_gettime(CLOCK_REALTIME);
127 $resolution = clock_getres(CLOCK_REALTIME);
129 clock_nanosleep(CLOCK_REALTIME, 1.5e9);
130 clock_nanosleep(CLOCK_REALTIME, time()*1e9 + 10e9, TIMER_ABSTIME);
132 my $ticktock = clock();
134 use Time::HiRes qw( stat lstat );
136 my @stat = stat("file");
138 my @stat = lstat("file");
142 The C<Time::HiRes> module implements a Perl interface to the
143 C<usleep>, C<nanosleep>, C<ualarm>, C<gettimeofday>, and
144 C<setitimer>/C<getitimer> system calls, in other words, high
145 resolution time and timers. See the L</EXAMPLES> section below and the
146 test scripts for usage; see your system documentation for the
147 description of the underlying C<nanosleep> or C<usleep>, C<ualarm>,
148 C<gettimeofday>, and C<setitimer>/C<getitimer> calls.
150 If your system lacks C<gettimeofday()> or an emulation of it you don't
151 get C<gettimeofday()> or the one-argument form of C<tv_interval()>.
152 If your system lacks all of C<nanosleep()>, C<usleep()>,
153 C<select()>, and C<poll>, you don't get C<Time::HiRes::usleep()>,
154 C<Time::HiRes::nanosleep()>, or C<Time::HiRes::sleep()>.
155 If your system lacks both C<ualarm()> and C<setitimer()> you don't get
156 C<Time::HiRes::ualarm()> or C<Time::HiRes::alarm()>.
158 If you try to import an unimplemented function in the C<use> statement
159 it will fail at compile time.
161 If your subsecond sleeping is implemented with C<nanosleep()> instead
162 of C<usleep()>, you can mix subsecond sleeping with signals since
163 C<nanosleep()> does not use signals. This, however, is not portable,
164 and you should first check for the truth value of
165 C<&Time::HiRes::d_nanosleep> to see whether you have nanosleep, and
166 then carefully read your C<nanosleep()> C API documentation for any
169 If you are using C<nanosleep> for something else than mixing sleeping
170 with signals, give some thought to whether Perl is the tool you should
171 be using for work requiring nanosecond accuracies.
173 Remember that unless you are working on a I<hard realtime> system,
174 any clocks and timers will be imprecise, especially so if you are working
175 in a pre-emptive multiuser system. Understand the difference between
176 I<wallclock time> and process time (in UNIX-like systems the sum of
177 I<user> and I<system> times). Any attempt to sleep for X seconds will
178 most probably end up sleeping B<more> than that, but don't be surprised
179 if you end up sleeping slightly B<less>.
181 The following functions can be imported from this module.
182 No functions are exported by default.
186 =item gettimeofday ()
188 In array context returns a two-element array with the seconds and
189 microseconds since the epoch. In scalar context returns floating
190 seconds like C<Time::HiRes::time()> (see below).
192 =item usleep ( $useconds )
194 Sleeps for the number of microseconds (millionths of a second)
195 specified. Returns the number of microseconds actually slept.
196 Can sleep for more than one second, unlike the C<usleep> system call.
197 Can also sleep for zero seconds, which often works like a I<thread yield>.
198 See also C<Time::HiRes::usleep()>, C<Time::HiRes::sleep()>, and
199 C<Time::HiRes::clock_nanosleep()>.
201 Do not expect usleep() to be exact down to one microsecond.
203 =item nanosleep ( $nanoseconds )
205 Sleeps for the number of nanoseconds (1e9ths of a second) specified.
206 Returns the number of nanoseconds actually slept (accurate only to
207 microseconds, the nearest thousand of them). Can sleep for more than
208 one second. Can also sleep for zero seconds, which often works like
209 a I<thread yield>. See also C<Time::HiRes::sleep()>,
210 C<Time::HiRes::usleep()>, and C<Time::HiRes::clock_nanosleep()>.
212 Do not expect nanosleep() to be exact down to one nanosecond.
213 Getting even accuracy of one thousand nanoseconds is good.
215 =item ualarm ( $useconds [, $interval_useconds ] )
217 Issues a C<ualarm> call; the C<$interval_useconds> is optional and
218 will be zero if unspecified, resulting in C<alarm>-like behaviour.
220 Returns the remaining time in the alarm in microseconds, or C<undef>
221 if an error occurred.
223 ualarm(0) will cancel an outstanding ualarm().
225 Note that the interaction between alarms and sleeps is unspecified.
229 tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] )
231 Returns the floating seconds between the two times, which should have
232 been returned by C<gettimeofday()>. If the second argument is omitted,
233 then the current time is used.
237 Returns a floating seconds since the epoch. This function can be
238 imported, resulting in a nice drop-in replacement for the C<time>
239 provided with core Perl; see the L</EXAMPLES> below.
241 B<NOTE 1>: This higher resolution timer can return values either less
242 or more than the core C<time()>, depending on whether your platform
243 rounds the higher resolution timer values up, down, or to the nearest second
244 to get the core C<time()>, but naturally the difference should be never
245 more than half a second. See also L</clock_getres>, if available
248 B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT, when
249 the C<time()> seconds since epoch rolled over to 1_000_000_000, the
250 default floating point format of Perl and the seconds since epoch have
251 conspired to produce an apparent bug: if you print the value of
252 C<Time::HiRes::time()> you seem to be getting only five decimals, not
253 six as promised (microseconds). Not to worry, the microseconds are
254 there (assuming your platform supports such granularity in the first
255 place). What is going on is that the default floating point format of
256 Perl only outputs 15 digits. In this case that means ten digits
257 before the decimal separator and five after. To see the microseconds
258 you can use either C<printf>/C<sprintf> with C<"%.6f">, or the
259 C<gettimeofday()> function in list context, which will give you the
260 seconds and microseconds as two separate values.
262 =item sleep ( $floating_seconds )
264 Sleeps for the specified amount of seconds. Returns the number of
265 seconds actually slept (a floating point value). This function can
266 be imported, resulting in a nice drop-in replacement for the C<sleep>
267 provided with perl, see the L</EXAMPLES> below.
269 Note that the interaction between alarms and sleeps is unspecified.
271 =item alarm ( $floating_seconds [, $interval_floating_seconds ] )
273 The C<SIGALRM> signal is sent after the specified number of seconds.
274 Implemented using C<setitimer()> if available, C<ualarm()> if not.
275 The C<$interval_floating_seconds> argument is optional and will be
276 zero if unspecified, resulting in C<alarm()>-like behaviour. This
277 function can be imported, resulting in a nice drop-in replacement for
278 the C<alarm> provided with perl, see the L</EXAMPLES> below.
280 Returns the remaining time in the alarm in seconds, or C<undef>
281 if an error occurred.
283 B<NOTE 1>: With some combinations of operating systems and Perl
284 releases C<SIGALRM> restarts C<select()>, instead of interrupting it.
285 This means that an C<alarm()> followed by a C<select()> may together
286 take the sum of the times specified for the C<alarm()> and the
287 C<select()>, not just the time of the C<alarm()>.
289 Note that the interaction between alarms and sleeps is unspecified.
291 =item setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )
293 Start up an interval timer: after a certain time, a signal ($which) arrives,
294 and more signals may keep arriving at certain intervals. To disable
295 an "itimer", use C<$floating_seconds> of zero. If the
296 C<$interval_floating_seconds> is set to zero (or unspecified), the
297 timer is disabled B<after> the next delivered signal.
299 Use of interval timers may interfere with C<alarm()>, C<sleep()>,
300 and C<usleep()>. In standard-speak the "interaction is unspecified",
301 which means that I<anything> may happen: it may work, it may not.
303 In scalar context, the remaining time in the timer is returned.
305 In list context, both the remaining time and the interval are returned.
307 There are usually three or four interval timers (signals) available: the
308 C<$which> can be C<ITIMER_REAL>, C<ITIMER_VIRTUAL>, C<ITIMER_PROF>, or
309 C<ITIMER_REALPROF>. Note that which ones are available depends: true
310 UNIX platforms usually have the first three, but only Solaris seems to
311 have C<ITIMER_REALPROF> (which is used to profile multithreaded programs).
312 Win32 unfortunately does not have interval timers.
314 C<ITIMER_REAL> results in C<alarm()>-like behaviour. Time is counted in
315 I<real time>; that is, wallclock time. C<SIGALRM> is delivered when
318 C<ITIMER_VIRTUAL> counts time in (process) I<virtual time>; that is,
319 only when the process is running. In multiprocessor/user/CPU systems
320 this may be more or less than real or wallclock time. (This time is
321 also known as the I<user time>.) C<SIGVTALRM> is delivered when the
324 C<ITIMER_PROF> counts time when either the process virtual time or when
325 the operating system is running on behalf of the process (such as I/O).
326 (This time is also known as the I<system time>.) (The sum of user
327 time and system time is known as the I<CPU time>.) C<SIGPROF> is
328 delivered when the timer expires. C<SIGPROF> can interrupt system calls.
330 The semantics of interval timers for multithreaded programs are
331 system-specific, and some systems may support additional interval
332 timers. For example, it is unspecified which thread gets the signals.
333 See your C<setitimer()> documentation.
335 =item getitimer ( $which )
337 Return the remaining time in the interval timer specified by C<$which>.
339 In scalar context, the remaining time is returned.
341 In list context, both the remaining time and the interval are returned.
342 The interval is always what you put in using C<setitimer()>.
344 =item clock_gettime ( $which )
346 Return as seconds the current value of the POSIX high resolution timer
347 specified by C<$which>. All implementations that support POSIX high
348 resolution timers are supposed to support at least the C<$which> value
349 of C<CLOCK_REALTIME>, which is supposed to return results close to the
350 results of C<gettimeofday>, or the number of seconds since 00:00:00:00
351 January 1, 1970 Greenwich Mean Time (GMT). Do not assume that
352 CLOCK_REALTIME is zero, it might be one, or something else.
353 Another potentially useful (but not available everywhere) value is
354 C<CLOCK_MONOTONIC>, which guarantees a monotonically increasing time
355 value (unlike time() or gettimeofday(), which can be adjusted).
356 See your system documentation for other possibly supported values.
358 =item clock_getres ( $which )
360 Return as seconds the resolution of the POSIX high resolution timer
361 specified by C<$which>. All implementations that support POSIX high
362 resolution timers are supposed to support at least the C<$which> value
363 of C<CLOCK_REALTIME>, see L</clock_gettime>.
365 B<NOTE>: the resolution returned may be highly optimistic. Even if
366 the resolution is high (a small number), all it means is that you'll
367 be able to specify the arguments to clock_gettime() and clock_nanosleep()
368 with that resolution. The system might not actually be able to measure
369 events at that resolution, and the various overheads and the overall system
370 load are certain to affect any timings.
372 =item clock_nanosleep ( $which, $nanoseconds, $flags = 0)
374 Sleeps for the number of nanoseconds (1e9ths of a second) specified.
375 Returns the number of nanoseconds actually slept. The $which is the
376 "clock id", as with clock_gettime() and clock_getres(). The flags
377 default to zero but C<TIMER_ABSTIME> can specified (must be exported
378 explicitly) which means that C<$nanoseconds> is not a time interval
379 (as is the default) but instead an absolute time. Can sleep for more
380 than one second. Can also sleep for zero seconds, which often works
381 like a I<thread yield>. See also C<Time::HiRes::sleep()>,
382 C<Time::HiRes::usleep()>, and C<Time::HiRes::nanosleep()>.
384 Do not expect clock_nanosleep() to be exact down to one nanosecond.
385 Getting even accuracy of one thousand nanoseconds is good.
389 Return as seconds the I<process time> (user + system time) spent by
390 the process since the first call to clock() (the definition is B<not>
391 "since the start of the process", though if you are lucky these times
392 may be quite close to each other, depending on the system). What this
393 means is that you probably need to store the result of your first call
394 to clock(), and subtract that value from the following results of clock().
396 The time returned also includes the process times of the terminated
397 child processes for which wait() has been executed. This value is
398 somewhat like the second value returned by the times() of core Perl,
399 but not necessarily identical. Note that due to backward
400 compatibility limitations the returned value may wrap around at about
401 2147 seconds or at about 36 minutes.
415 As L<perlfunc/stat> or L<perlfunc/lstat>
416 but with the access/modify/change file timestamps
417 in subsecond resolution, if the operating system and the filesystem
418 both support such timestamps. To override the standard stat():
420 use Time::HiRes qw(stat);
422 Test for the value of &Time::HiRes::d_hires_stat to find out whether
423 the operating system supports subsecond file timestamps: a value
424 larger than zero means yes. There are unfortunately no easy
425 ways to find out whether the filesystem supports such timestamps.
426 UNIX filesystems often do; NTFS does; FAT doesn't (FAT timestamp
427 granularity is B<two> seconds).
429 A zero return value of &Time::HiRes::d_hires_stat means that
430 Time::HiRes::stat is a no-op passthrough for CORE::stat()
431 (and likewise for lstat),
432 and therefore the timestamps will stay integers. The same
433 thing will happen if the filesystem does not do subsecond timestamps,
434 even if the &Time::HiRes::d_hires_stat is non-zero.
436 In any case do not expect nanosecond resolution, or even a microsecond
437 resolution. Also note that the modify/access timestamps might have
438 different resolutions, and that they need not be synchronized, e.g.
439 if the operations are
446 the access time stamp from t2 need not be greater-than the modify
447 time stamp from t1: it may be equal or I<less>.
453 use Time::HiRes qw(usleep ualarm gettimeofday tv_interval);
455 $microseconds = 750_000;
456 usleep($microseconds);
458 # signal alarm in 2.5s & every .1s thereafter
459 ualarm(2_500_000, 100_000);
463 # get seconds and microseconds since the epoch
464 ($s, $usec) = gettimeofday();
466 # measure elapsed time
467 # (could also do by subtracting 2 gettimeofday return values)
468 $t0 = [gettimeofday];
469 # do bunch of stuff here
470 $t1 = [gettimeofday];
472 $t0_t1 = tv_interval $t0, $t1;
474 $elapsed = tv_interval ($t0, [gettimeofday]);
475 $elapsed = tv_interval ($t0); # equivalent code
478 # replacements for time, alarm and sleep that know about
482 $now_fractions = Time::HiRes::time;
483 Time::HiRes::sleep (2.5);
484 Time::HiRes::alarm (10.6666666);
486 use Time::HiRes qw ( time alarm sleep );
487 $now_fractions = time;
491 # Arm an interval timer to go off first at 10 seconds and
492 # after that every 2.5 seconds, in process virtual time
494 use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time );
496 $SIG{VTALRM} = sub { print time, "\n" };
497 setitimer(ITIMER_VIRTUAL, 10, 2.5);
499 use Time::HiRes qw( clock_gettime clock_getres CLOCK_REALTIME );
500 # Read the POSIX high resolution timer.
501 my $high = clock_gettime(CLOCK_REALTIME);
502 # But how accurate we can be, really?
503 my $reso = clock_getres(CLOCK_REALTIME);
505 use Time::HiRes qw( clock_nanosleep TIMER_ABSTIME );
506 clock_nanosleep(CLOCK_REALTIME, 1e6);
507 clock_nanosleep(CLOCK_REALTIME, 2e9, TIMER_ABSTIME);
509 use Time::HiRes qw( clock );
510 my $clock0 = clock();
512 my $clock1 = clock();
513 my $clockd = $clock1 - $clock0;
515 use Time::HiRes qw( stat );
516 my ($atime, $mtime, $ctime) = (stat("istics"))[8, 9, 10];
520 In addition to the perl API described above, a C API is available for
521 extension writers. The following C functions are available in the
525 --------------- ----------------------
526 Time::NVtime NV (*)()
527 Time::U2time void (*)(pTHX_ UV ret[2])
529 Both functions return equivalent information (like C<gettimeofday>)
530 but with different representations. The names C<NVtime> and C<U2time>
531 were selected mainly because they are operating system independent.
532 (C<gettimeofday> is Unix-centric, though some platforms like Win32 and
533 VMS have emulations for it.)
535 Here is an example of using C<NVtime> from C:
537 NV (*myNVtime)(); /* Returns -1 on failure. */
538 SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0);
539 if (!svp) croak("Time::HiRes is required");
540 if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer");
541 myNVtime = INT2PTR(NV(*)(), SvIV(*svp));
542 printf("The current time is: %" NVff "\n", (*myNVtime)());
546 =head2 useconds or interval more than ...
548 In ualarm() you tried to use number of microseconds or interval (also
549 in microseconds) more than 1_000_000 and setitimer() is not available
550 in your system to emulate that case.
552 =head2 negative time not invented yet
554 You tried to use a negative time argument.
556 =head2 internal error: useconds < 0 (unsigned ... signed ...)
558 Something went horribly wrong-- the number of microseconds that cannot
559 become negative just became negative. Maybe your compiler is broken?
561 =head2 useconds or uinterval equal to or more than 1000000
563 In some platforms it is not possible to get an alarm with subsecond
564 resolution and later than one second.
566 =head2 unimplemented in this platform
568 Some calls simply aren't available, real or emulated, on every platform.
572 Notice that the core C<time()> maybe rounding rather than truncating.
573 What this means is that the core C<time()> may be reporting the time
574 as one second later than C<gettimeofday()> and C<Time::HiRes::time()>.
576 Adjusting the system clock (either manually or by services like ntp)
577 may cause problems, especially for long running programs that assume
578 a monotonously increasing time (note that all platforms do not adjust
579 time as gracefully as UNIX ntp does). For example in Win32 (and derived
580 platforms like Cygwin and MinGW) the Time::HiRes::time() may temporarily
581 drift off from the system clock (and the original time()) by up to 0.5
582 seconds. Time::HiRes will notice this eventually and recalibrate.
583 Note that since Time::HiRes 1.77 the clock_gettime(CLOCK_MONOTONIC)
584 might help in this (in case your system supports CLOCK_MONOTONIC).
586 Some systems have APIs but not implementations: for example QNX and Haiku
587 have the interval timer APIs but not the functionality.
589 In OS X clock_getres(), clock_gettime() and clock_nanosleep() are
590 emulated using the Mach timers; as a side effect of being emulated
591 the CLOCK_REALTIME and CLOCK_MONOTONIC are the same timer.
595 Perl modules L<BSD::Resource>, L<Time::TAI64>.
597 Your system documentation for C<clock>, C<clock_gettime>,
598 C<clock_getres>, C<clock_nanosleep>, C<clock_settime>, C<getitimer>,
599 C<gettimeofday>, C<setitimer>, C<sleep>, C<stat>, C<ualarm>.
603 D. Wegscheid <wegscd@whirlpool.com>
604 R. Schertler <roderick@argon.org>
605 J. Hietaniemi <jhi@iki.fi>
606 G. Aas <gisle@aas.no>
608 =head1 COPYRIGHT AND LICENSE
610 Copyright (c) 1996-2002 Douglas E. Wegscheid. All rights reserved.
612 Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 Jarkko Hietaniemi.
615 Copyright (C) 2011, 2012, 2013 Andrew Main (Zefram) <zefram@fysh.org>
617 This program is free software; you can redistribute it and/or modify
618 it under the same terms as Perl itself.