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_HIGHRES CLOCK_MONOTONIC CLOCK_PROCESS_CPUTIME_ID
16 CLOCK_REALTIME CLOCK_SOFTTIME CLOCK_THREAD_CPUTIME_ID
17 CLOCK_TIMEOFDAY CLOCKS_PER_SEC
18 ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF ITIMER_REALPROF
20 d_usleep d_ualarm d_gettimeofday d_getitimer d_setitimer
21 d_nanosleep d_clock_gettime d_clock_getres
22 d_clock d_clock_nanosleep
26 our $VERSION = '1.9725';
27 our $XS_VERSION = $VERSION;
28 $VERSION = eval $VERSION;
33 ($constname = $AUTOLOAD) =~ s/.*:://;
34 # print "AUTOLOAD: constname = $constname ($AUTOLOAD)\n";
35 die "&Time::HiRes::constant not defined" if $constname eq 'constant';
36 my ($error, $val) = constant($constname);
37 # print "AUTOLOAD: error = $error, val = $val\n";
39 my (undef,$file,$line) = caller;
40 die "$error at $file line $line.\n";
44 *$AUTOLOAD = sub { $val };
52 if (($i eq 'clock_getres' && !&d_clock_getres) ||
53 ($i eq 'clock_gettime' && !&d_clock_gettime) ||
54 ($i eq 'clock_nanosleep' && !&d_clock_nanosleep) ||
55 ($i eq 'clock' && !&d_clock) ||
56 ($i eq 'nanosleep' && !&d_nanosleep) ||
57 ($i eq 'usleep' && !&d_usleep) ||
58 ($i eq 'ualarm' && !&d_ualarm)) {
60 Carp::croak("Time::HiRes::$i(): unimplemented in this platform");
63 Time::HiRes->export_to_level(1, $this, @_);
66 bootstrap Time::HiRes;
68 # Preloaded methods go here.
71 # probably could have been done in C
73 $b = [gettimeofday()] unless defined($b);
74 (${$b}[0] - ${$a}[0]) + ((${$b}[1] - ${$a}[1]) / 1_000_000);
77 # Autoload methods go after =cut, and are processed by the autosplit program.
84 Time::HiRes - High resolution alarm, sleep, gettimeofday, interval timers
88 use Time::HiRes qw( usleep ualarm gettimeofday tv_interval nanosleep
89 clock_gettime clock_getres clock_nanosleep clock
92 usleep ($microseconds);
93 nanosleep ($nanoseconds);
95 ualarm ($microseconds);
96 ualarm ($microseconds, $interval_microseconds);
99 ($seconds, $microseconds) = gettimeofday;
101 $elapsed = tv_interval ( $t0, [$seconds, $microseconds]);
102 $elapsed = tv_interval ( $t0, [gettimeofday]);
103 $elapsed = tv_interval ( $t0 );
105 use Time::HiRes qw ( time alarm sleep );
107 $now_fractions = time;
108 sleep ($floating_seconds);
109 alarm ($floating_seconds);
110 alarm ($floating_seconds, $floating_interval);
112 use Time::HiRes qw( setitimer getitimer );
114 setitimer ($which, $floating_seconds, $floating_interval );
117 use Time::HiRes qw( clock_gettime clock_getres clock_nanosleep
118 ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF ITIMER_REALPROF );
120 $realtime = clock_gettime(CLOCK_REALTIME);
121 $resolution = clock_getres(CLOCK_REALTIME);
123 clock_nanosleep(CLOCK_REALTIME, 1.5e9);
124 clock_nanosleep(CLOCK_REALTIME, time()*1e9 + 10e9, TIMER_ABSTIME);
126 my $ticktock = clock();
128 use Time::HiRes qw( stat );
130 my @stat = stat("file");
135 The C<Time::HiRes> module implements a Perl interface to the
136 C<usleep>, C<nanosleep>, C<ualarm>, C<gettimeofday>, and
137 C<setitimer>/C<getitimer> system calls, in other words, high
138 resolution time and timers. See the L</EXAMPLES> section below and the
139 test scripts for usage; see your system documentation for the
140 description of the underlying C<nanosleep> or C<usleep>, C<ualarm>,
141 C<gettimeofday>, and C<setitimer>/C<getitimer> calls.
143 If your system lacks C<gettimeofday()> or an emulation of it you don't
144 get C<gettimeofday()> or the one-argument form of C<tv_interval()>.
145 If your system lacks all of C<nanosleep()>, C<usleep()>,
146 C<select()>, and C<poll>, you don't get C<Time::HiRes::usleep()>,
147 C<Time::HiRes::nanosleep()>, or C<Time::HiRes::sleep()>.
148 If your system lacks both C<ualarm()> and C<setitimer()> you don't get
149 C<Time::HiRes::ualarm()> or C<Time::HiRes::alarm()>.
151 If you try to import an unimplemented function in the C<use> statement
152 it will fail at compile time.
154 If your subsecond sleeping is implemented with C<nanosleep()> instead
155 of C<usleep()>, you can mix subsecond sleeping with signals since
156 C<nanosleep()> does not use signals. This, however, is not portable,
157 and you should first check for the truth value of
158 C<&Time::HiRes::d_nanosleep> to see whether you have nanosleep, and
159 then carefully read your C<nanosleep()> C API documentation for any
162 If you are using C<nanosleep> for something else than mixing sleeping
163 with signals, give some thought to whether Perl is the tool you should
164 be using for work requiring nanosecond accuracies.
166 Remember that unless you are working on a I<hard realtime> system,
167 any clocks and timers will be imprecise, especially so if you are working
168 in a pre-emptive multiuser system. Understand the difference between
169 I<wallclock time> and process time (in UNIX-like systems the sum of
170 I<user> and I<system> times). Any attempt to sleep for X seconds will
171 most probably end up sleeping B<more> than that, but don't be surpised
172 if you end up sleeping slightly B<less>.
174 The following functions can be imported from this module.
175 No functions are exported by default.
179 =item gettimeofday ()
181 In array context returns a two-element array with the seconds and
182 microseconds since the epoch. In scalar context returns floating
183 seconds like C<Time::HiRes::time()> (see below).
185 =item usleep ( $useconds )
187 Sleeps for the number of microseconds (millionths of a second)
188 specified. Returns the number of microseconds actually slept.
189 Can sleep for more than one second, unlike the C<usleep> system call.
190 Can also sleep for zero seconds, which often works like a I<thread yield>.
191 See also C<Time::HiRes::usleep()>, C<Time::HiRes::sleep()>, and
192 C<Time::HiRes::clock_nanosleep()>.
194 Do not expect usleep() to be exact down to one microsecond.
196 =item nanosleep ( $nanoseconds )
198 Sleeps for the number of nanoseconds (1e9ths of a second) specified.
199 Returns the number of nanoseconds actually slept (accurate only to
200 microseconds, the nearest thousand of them). Can sleep for more than
201 one second. Can also sleep for zero seconds, which often works like
202 a I<thread yield>. See also C<Time::HiRes::sleep()>,
203 C<Time::HiRes::usleep()>, and C<Time::HiRes::clock_nanosleep()>.
205 Do not expect nanosleep() to be exact down to one nanosecond.
206 Getting even accuracy of one thousand nanoseconds is good.
208 =item ualarm ( $useconds [, $interval_useconds ] )
210 Issues a C<ualarm> call; the C<$interval_useconds> is optional and
211 will be zero if unspecified, resulting in C<alarm>-like behaviour.
213 Returns the remaining time in the alarm in microseconds, or C<undef>
214 if an error occurred.
216 ualarm(0) will cancel an outstanding ualarm().
218 Note that the interaction between alarms and sleeps is unspecified.
222 tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] )
224 Returns the floating seconds between the two times, which should have
225 been returned by C<gettimeofday()>. If the second argument is omitted,
226 then the current time is used.
230 Returns a floating seconds since the epoch. This function can be
231 imported, resulting in a nice drop-in replacement for the C<time>
232 provided with core Perl; see the L</EXAMPLES> below.
234 B<NOTE 1>: This higher resolution timer can return values either less
235 or more than the core C<time()>, depending on whether your platform
236 rounds the higher resolution timer values up, down, or to the nearest second
237 to get the core C<time()>, but naturally the difference should be never
238 more than half a second. See also L</clock_getres>, if available
241 B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT, when
242 the C<time()> seconds since epoch rolled over to 1_000_000_000, the
243 default floating point format of Perl and the seconds since epoch have
244 conspired to produce an apparent bug: if you print the value of
245 C<Time::HiRes::time()> you seem to be getting only five decimals, not
246 six as promised (microseconds). Not to worry, the microseconds are
247 there (assuming your platform supports such granularity in the first
248 place). What is going on is that the default floating point format of
249 Perl only outputs 15 digits. In this case that means ten digits
250 before the decimal separator and five after. To see the microseconds
251 you can use either C<printf>/C<sprintf> with C<"%.6f">, or the
252 C<gettimeofday()> function in list context, which will give you the
253 seconds and microseconds as two separate values.
255 =item sleep ( $floating_seconds )
257 Sleeps for the specified amount of seconds. Returns the number of
258 seconds actually slept (a floating point value). This function can
259 be imported, resulting in a nice drop-in replacement for the C<sleep>
260 provided with perl, see the L</EXAMPLES> below.
262 Note that the interaction between alarms and sleeps is unspecified.
264 =item alarm ( $floating_seconds [, $interval_floating_seconds ] )
266 The C<SIGALRM> signal is sent after the specified number of seconds.
267 Implemented using C<setitimer()> if available, C<ualarm()> if not.
268 The C<$interval_floating_seconds> argument is optional and will be
269 zero if unspecified, resulting in C<alarm()>-like behaviour. This
270 function can be imported, resulting in a nice drop-in replacement for
271 the C<alarm> provided with perl, see the L</EXAMPLES> below.
273 Returns the remaining time in the alarm in seconds, or C<undef>
274 if an error occurred.
276 B<NOTE 1>: With some combinations of operating systems and Perl
277 releases C<SIGALRM> restarts C<select()>, instead of interrupting it.
278 This means that an C<alarm()> followed by a C<select()> may together
279 take the sum of the times specified for the C<alarm()> and the
280 C<select()>, not just the time of the C<alarm()>.
282 Note that the interaction between alarms and sleeps is unspecified.
284 =item setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )
286 Start up an interval timer: after a certain time, a signal ($which) arrives,
287 and more signals may keep arriving at certain intervals. To disable
288 an "itimer", use C<$floating_seconds> of zero. If the
289 C<$interval_floating_seconds> is set to zero (or unspecified), the
290 timer is disabled B<after> the next delivered signal.
292 Use of interval timers may interfere with C<alarm()>, C<sleep()>,
293 and C<usleep()>. In standard-speak the "interaction is unspecified",
294 which means that I<anything> may happen: it may work, it may not.
296 In scalar context, the remaining time in the timer is returned.
298 In list context, both the remaining time and the interval are returned.
300 There are usually three or four interval timers (signals) available: the
301 C<$which> can be C<ITIMER_REAL>, C<ITIMER_VIRTUAL>, C<ITIMER_PROF>, or
302 C<ITIMER_REALPROF>. Note that which ones are available depends: true
303 UNIX platforms usually have the first three, but only Solaris seems to
304 have C<ITIMER_REALPROF> (which is used to profile multithreaded programs).
305 Win32 unfortunately does not haveinterval timers.
307 C<ITIMER_REAL> results in C<alarm()>-like behaviour. Time is counted in
308 I<real time>; that is, wallclock time. C<SIGALRM> is delivered when
311 C<ITIMER_VIRTUAL> counts time in (process) I<virtual time>; that is,
312 only when the process is running. In multiprocessor/user/CPU systems
313 this may be more or less than real or wallclock time. (This time is
314 also known as the I<user time>.) C<SIGVTALRM> is delivered when the
317 C<ITIMER_PROF> counts time when either the process virtual time or when
318 the operating system is running on behalf of the process (such as I/O).
319 (This time is also known as the I<system time>.) (The sum of user
320 time and system time is known as the I<CPU time>.) C<SIGPROF> is
321 delivered when the timer expires. C<SIGPROF> can interrupt system calls.
323 The semantics of interval timers for multithreaded programs are
324 system-specific, and some systems may support additional interval
325 timers. For example, it is unspecified which thread gets the signals.
326 See your C<setitimer()> documentation.
328 =item getitimer ( $which )
330 Return the remaining time in the interval timer specified by C<$which>.
332 In scalar context, the remaining time is returned.
334 In list context, both the remaining time and the interval are returned.
335 The interval is always what you put in using C<setitimer()>.
337 =item clock_gettime ( $which )
339 Return as seconds the current value of the POSIX high resolution timer
340 specified by C<$which>. All implementations that support POSIX high
341 resolution timers are supposed to support at least the C<$which> value
342 of C<CLOCK_REALTIME>, which is supposed to return results close to the
343 results of C<gettimeofday>, or the number of seconds since 00:00:00:00
344 January 1, 1970 Greenwich Mean Time (GMT). Do not assume that
345 CLOCK_REALTIME is zero, it might be one, or something else.
346 Another potentially useful (but not available everywhere) value is
347 C<CLOCK_MONOTONIC>, which guarantees a monotonically increasing time
348 value (unlike time() or gettimeofday(), which can be adjusted).
349 See your system documentation for other possibly supported values.
351 =item clock_getres ( $which )
353 Return as seconds the resolution of the POSIX high resolution timer
354 specified by C<$which>. All implementations that support POSIX high
355 resolution timers are supposed to support at least the C<$which> value
356 of C<CLOCK_REALTIME>, see L</clock_gettime>.
358 =item clock_nanosleep ( $which, $nanoseconds, $flags = 0)
360 Sleeps for the number of nanoseconds (1e9ths of a second) specified.
361 Returns the number of nanoseconds actually slept. The $which is the
362 "clock id", as with clock_gettime() and clock_getres(). The flags
363 default to zero but C<TIMER_ABSTIME> can specified (must be exported
364 explicitly) which means that C<$nanoseconds> is not a time interval
365 (as is the default) but instead an absolute time. Can sleep for more
366 than one second. Can also sleep for zero seconds, which often works
367 like a I<thread yield>. See also C<Time::HiRes::sleep()>,
368 C<Time::HiRes::usleep()>, and C<Time::HiRes::nanosleep()>.
370 Do not expect clock_nanosleep() to be exact down to one nanosecond.
371 Getting even accuracy of one thousand nanoseconds is good.
375 Return as seconds the I<process time> (user + system time) spent by
376 the process since the first call to clock() (the definition is B<not>
377 "since the start of the process", though if you are lucky these times
378 may be quite close to each other, depending on the system). What this
379 means is that you probably need to store the result of your first call
380 to clock(), and subtract that value from the following results of clock().
382 The time returned also includes the process times of the terminated
383 child processes for which wait() has been executed. This value is
384 somewhat like the second value returned by the times() of core Perl,
385 but not necessarily identical. Note that due to backward
386 compatibility limitations the returned value may wrap around at about
387 2147 seconds or at about 36 minutes.
395 As L<perlfunc/stat> but with the access/modify/change file timestamps
396 in subsecond resolution, if the operating system and the filesystem
397 both support such timestamps. To override the standard stat():
399 use Time::HiRes qw(stat);
401 Test for the value of &Time::HiRes::d_hires_stat to find out whether
402 the operating system supports subsecond file timestamps: a value
403 larger than zero means yes. There are unfortunately no easy
404 ways to find out whether the filesystem supports such timestamps.
405 UNIX filesystems often do; NTFS does; FAT doesn't (FAT timestamp
406 granularity is B<two> seconds).
408 A zero return value of &Time::HiRes::d_hires_stat means that
409 Time::HiRes::stat is a no-op passthrough for CORE::stat(),
410 and therefore the timestamps will stay integers. The same
411 thing will happen if the filesystem does not do subsecond timestamps,
412 even if the &Time::HiRes::d_hires_stat is non-zero.
414 In any case do not expect nanosecond resolution, or even a microsecond
415 resolution. Also note that the modify/access timestamps might have
416 different resolutions, and that they need not be synchronized, e.g.
417 if the operations are
424 the access time stamp from t2 need not be greater-than the modify
425 time stamp from t1: it may be equal or I<less>.
431 use Time::HiRes qw(usleep ualarm gettimeofday tv_interval);
433 $microseconds = 750_000;
434 usleep($microseconds);
436 # signal alarm in 2.5s & every .1s thereafter
437 ualarm(2_500_000, 100_000);
441 # get seconds and microseconds since the epoch
442 ($s, $usec) = gettimeofday();
444 # measure elapsed time
445 # (could also do by subtracting 2 gettimeofday return values)
446 $t0 = [gettimeofday];
447 # do bunch of stuff here
448 $t1 = [gettimeofday];
450 $t0_t1 = tv_interval $t0, $t1;
452 $elapsed = tv_interval ($t0, [gettimeofday]);
453 $elapsed = tv_interval ($t0); # equivalent code
456 # replacements for time, alarm and sleep that know about
460 $now_fractions = Time::HiRes::time;
461 Time::HiRes::sleep (2.5);
462 Time::HiRes::alarm (10.6666666);
464 use Time::HiRes qw ( time alarm sleep );
465 $now_fractions = time;
469 # Arm an interval timer to go off first at 10 seconds and
470 # after that every 2.5 seconds, in process virtual time
472 use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time );
474 $SIG{VTALRM} = sub { print time, "\n" };
475 setitimer(ITIMER_VIRTUAL, 10, 2.5);
477 use Time::HiRes qw( clock_gettime clock_getres CLOCK_REALTIME );
478 # Read the POSIX high resolution timer.
479 my $high = clock_getres(CLOCK_REALTIME);
480 # But how accurate we can be, really?
481 my $reso = clock_getres(CLOCK_REALTIME);
483 use Time::HiRes qw( clock_nanosleep TIMER_ABSTIME );
484 clock_nanosleep(CLOCK_REALTIME, 1e6);
485 clock_nanosleep(CLOCK_REALTIME, 2e9, TIMER_ABSTIME);
487 use Time::HiRes qw( clock );
488 my $clock0 = clock();
490 my $clock1 = clock();
491 my $clockd = $clock1 - $clock0;
493 use Time::HiRes qw( stat );
494 my ($atime, $mtime, $ctime) = (stat("istics"))[8, 9, 10];
498 In addition to the perl API described above, a C API is available for
499 extension writers. The following C functions are available in the
503 --------------- ----------------------
504 Time::NVtime double (*)()
505 Time::U2time void (*)(pTHX_ UV ret[2])
507 Both functions return equivalent information (like C<gettimeofday>)
508 but with different representations. The names C<NVtime> and C<U2time>
509 were selected mainly because they are operating system independent.
510 (C<gettimeofday> is Unix-centric, though some platforms like Win32 and
511 VMS have emulations for it.)
513 Here is an example of using C<NVtime> from C:
515 double (*myNVtime)(); /* Returns -1 on failure. */
516 SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0);
517 if (!svp) croak("Time::HiRes is required");
518 if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer");
519 myNVtime = INT2PTR(double(*)(), SvIV(*svp));
520 printf("The current time is: %f\n", (*myNVtime)());
524 =head2 useconds or interval more than ...
526 In ualarm() you tried to use number of microseconds or interval (also
527 in microseconds) more than 1_000_000 and setitimer() is not available
528 in your system to emulate that case.
530 =head2 negative time not invented yet
532 You tried to use a negative time argument.
534 =head2 internal error: useconds < 0 (unsigned ... signed ...)
536 Something went horribly wrong-- the number of microseconds that cannot
537 become negative just became negative. Maybe your compiler is broken?
539 =head2 useconds or uinterval equal to or more than 1000000
541 In some platforms it is not possible to get an alarm with subsecond
542 resolution and later than one second.
544 =head2 unimplemented in this platform
546 Some calls simply aren't available, real or emulated, on every platform.
550 Notice that the core C<time()> maybe rounding rather than truncating.
551 What this means is that the core C<time()> may be reporting the time
552 as one second later than C<gettimeofday()> and C<Time::HiRes::time()>.
554 Adjusting the system clock (either manually or by services like ntp)
555 may cause problems, especially for long running programs that assume
556 a monotonously increasing time (note that all platforms do not adjust
557 time as gracefully as UNIX ntp does). For example in Win32 (and derived
558 platforms like Cygwin and MinGW) the Time::HiRes::time() may temporarily
559 drift off from the system clock (and the original time()) by up to 0.5
560 seconds. Time::HiRes will notice this eventually and recalibrate.
561 Note that since Time::HiRes 1.77 the clock_gettime(CLOCK_MONOTONIC)
562 might help in this (in case your system supports CLOCK_MONOTONIC).
564 Some systems have APIs but not implementations: for example QNX and Haiku
565 have the interval timer APIs but not the functionality.
569 Perl modules L<BSD::Resource>, L<Time::TAI64>.
571 Your system documentation for C<clock>, C<clock_gettime>,
572 C<clock_getres>, C<clock_nanosleep>, C<clock_settime>, C<getitimer>,
573 C<gettimeofday>, C<setitimer>, C<sleep>, C<stat>, C<ualarm>.
577 D. Wegscheid <wegscd@whirlpool.com>
578 R. Schertler <roderick@argon.org>
579 J. Hietaniemi <jhi@iki.fi>
580 G. Aas <gisle@aas.no>
582 =head1 COPYRIGHT AND LICENSE
584 Copyright (c) 1996-2002 Douglas E. Wegscheid. All rights reserved.
586 Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 Jarkko Hietaniemi.
589 Copyright (C) 2011, 2012 Andrew Main (Zefram) <zefram@fysh.org>
591 This program is free software; you can redistribute it and/or modify
592 it under the same terms as Perl itself.