4 use vars qw($VERSION $XS_VERSION @ISA @EXPORT @EXPORT_OK $AUTOLOAD);
9 @ISA = qw(Exporter DynaLoader);
12 @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
27 $XS_VERSION = $VERSION;
28 $VERSION = eval $VERSION;
32 ($constname = $AUTOLOAD) =~ s/.*:://;
33 # print "AUTOLOAD: constname = $constname ($AUTOLOAD)\n";
34 die "&Time::HiRes::constant not defined" if $constname eq 'constant';
35 my ($error, $val) = constant($constname);
36 # print "AUTOLOAD: error = $error, val = $val\n";
38 my (undef,$file,$line) = caller;
39 die "$error at $file line $line.\n";
43 *$AUTOLOAD = sub { $val };
51 if (($i eq 'clock_getres' && !&d_clock_getres) ||
52 ($i eq 'clock_gettime' && !&d_clock_gettime) ||
53 ($i eq 'clock_nanosleep' && !&d_clock_nanosleep) ||
54 ($i eq 'clock' && !&d_clock) ||
55 ($i eq 'nanosleep' && !&d_nanosleep) ||
56 ($i eq 'usleep' && !&d_usleep) ||
57 ($i eq 'ualarm' && !&d_ualarm)) {
59 Carp::croak("Time::HiRes::$i(): unimplemented in this platform");
62 Time::HiRes->export_to_level(1, $this, @_);
65 bootstrap Time::HiRes;
67 # Preloaded methods go here.
70 # probably could have been done in C
72 $b = [gettimeofday()] unless defined($b);
73 (${$b}[0] - ${$a}[0]) + ((${$b}[1] - ${$a}[1]) / 1_000_000);
76 # Autoload methods go after =cut, and are processed by the autosplit program.
83 Time::HiRes - High resolution alarm, sleep, gettimeofday, interval timers
87 use Time::HiRes qw( usleep ualarm gettimeofday tv_interval nanosleep
88 clock_gettime clock_getres clock_nanosleep clock
91 usleep ($microseconds);
92 nanosleep ($nanoseconds);
94 ualarm ($microseconds);
95 ualarm ($microseconds, $interval_microseconds);
98 ($seconds, $microseconds) = gettimeofday;
100 $elapsed = tv_interval ( $t0, [$seconds, $microseconds]);
101 $elapsed = tv_interval ( $t0, [gettimeofday]);
102 $elapsed = tv_interval ( $t0 );
104 use Time::HiRes qw ( time alarm sleep );
106 $now_fractions = time;
107 sleep ($floating_seconds);
108 alarm ($floating_seconds);
109 alarm ($floating_seconds, $floating_interval);
111 use Time::HiRes qw( setitimer getitimer
112 ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF ITIMER_REALPROF );
114 setitimer ($which, $floating_seconds, $floating_interval );
117 $realtime = clock_gettime(CLOCK_REALTIME);
118 $resolution = clock_getres(CLOCK_REALTIME);
120 clock_nanosleep(CLOCK_REALTIME, 1.5);
121 clock_nanosleep(CLOCK_REALTIME, time() + 10, TIMER_ABSTIME);
123 my $ticktock = clock();
125 my @stat = stat("file");
130 The C<Time::HiRes> module implements a Perl interface to the
131 C<usleep>, C<nanosleep>, C<ualarm>, C<gettimeofday>, and
132 C<setitimer>/C<getitimer> system calls, in other words, high
133 resolution time and timers. See the L</EXAMPLES> section below and the
134 test scripts for usage; see your system documentation for the
135 description of the underlying C<nanosleep> or C<usleep>, C<ualarm>,
136 C<gettimeofday>, and C<setitimer>/C<getitimer> calls.
138 If your system lacks C<gettimeofday()> or an emulation of it you don't
139 get C<gettimeofday()> or the one-argument form of C<tv_interval()>.
140 If your system lacks all of C<nanosleep()>, C<usleep()>,
141 C<select()>, and C<poll>, you don't get C<Time::HiRes::usleep()>,
142 C<Time::HiRes::nanosleep()>, or C<Time::HiRes::sleep()>.
143 If your system lacks both C<ualarm()> and C<setitimer()> you don't get
144 C<Time::HiRes::ualarm()> or C<Time::HiRes::alarm()>.
146 If you try to import an unimplemented function in the C<use> statement
147 it will fail at compile time.
149 If your subsecond sleeping is implemented with C<nanosleep()> instead
150 of C<usleep()>, you can mix subsecond sleeping with signals since
151 C<nanosleep()> does not use signals. This, however, is not portable,
152 and you should first check for the truth value of
153 C<&Time::HiRes::d_nanosleep> to see whether you have nanosleep, and
154 then carefully read your C<nanosleep()> C API documentation for any
157 If you are using C<nanosleep> for something else than mixing sleeping
158 with signals, give some thought to whether Perl is the tool you should
159 be using for work requiring nanosecond accuracies.
161 The following functions can be imported from this module.
162 No functions are exported by default.
166 =item gettimeofday ()
168 In array context returns a two-element array with the seconds and
169 microseconds since the epoch. In scalar context returns floating
170 seconds like C<Time::HiRes::time()> (see below).
172 =item usleep ( $useconds )
174 Sleeps for the number of microseconds (millionths of a second)
175 specified. Returns the number of microseconds actually slept. Can
176 sleep for more than one second, unlike the C<usleep> system call. Can
177 also sleep for zero seconds, which often works like a I<thread yield>.
178 See also C<Time::HiRes::usleep()>, C<Time::HiRes::sleep()>, and
179 C<Time::HiRes::clock_nanosleep()>.
181 Do not expect usleep() to be exact down to one microsecond.
183 =item nanosleep ( $nanoseconds )
185 Sleeps for the number of nanoseconds (1e9ths of a second) specified.
186 Returns the number of nanoseconds actually slept (accurate only to
187 microseconds, the nearest thousand of them). Can sleep for more than
188 one second. Can also sleep for zero seconds, which often works like a
189 I<thread yield>. See also C<Time::HiRes::sleep()>,
190 C<Time::HiRes::usleep()>, and C<Time::HiRes::clock_nanosleep()>.
192 Do not expect nanosleep() to be exact down to one nanosecond.
193 Getting even accuracy of one thousand nanoseconds is good.
195 =item ualarm ( $useconds [, $interval_useconds ] )
197 Issues a C<ualarm> call; the C<$interval_useconds> is optional and
198 will be zero if unspecified, resulting in C<alarm>-like behaviour.
200 Note that the interaction between alarms and sleeps is unspecified.
204 tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] )
206 Returns the floating seconds between the two times, which should have
207 been returned by C<gettimeofday()>. If the second argument is omitted,
208 then the current time is used.
212 Returns a floating seconds since the epoch. This function can be
213 imported, resulting in a nice drop-in replacement for the C<time>
214 provided with core Perl; see the L</EXAMPLES> below.
216 B<NOTE 1>: This higher resolution timer can return values either less
217 or more than the core C<time()>, depending on whether your platform
218 rounds the higher resolution timer values up, down, or to the nearest second
219 to get the core C<time()>, but naturally the difference should be never
220 more than half a second. See also L</clock_getres>, if available
223 B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT, when
224 the C<time()> seconds since epoch rolled over to 1_000_000_000, the
225 default floating point format of Perl and the seconds since epoch have
226 conspired to produce an apparent bug: if you print the value of
227 C<Time::HiRes::time()> you seem to be getting only five decimals, not
228 six as promised (microseconds). Not to worry, the microseconds are
229 there (assuming your platform supports such granularity in the first
230 place). What is going on is that the default floating point format of
231 Perl only outputs 15 digits. In this case that means ten digits
232 before the decimal separator and five after. To see the microseconds
233 you can use either C<printf>/C<sprintf> with C<"%.6f">, or the
234 C<gettimeofday()> function in list context, which will give you the
235 seconds and microseconds as two separate values.
237 =item sleep ( $floating_seconds )
239 Sleeps for the specified amount of seconds. Returns the number of
240 seconds actually slept (a floating point value). This function can
241 be imported, resulting in a nice drop-in replacement for the C<sleep>
242 provided with perl, see the L</EXAMPLES> below.
244 Note that the interaction between alarms and sleeps is unspecified.
246 =item alarm ( $floating_seconds [, $interval_floating_seconds ] )
248 The C<SIGALRM> signal is sent after the specified number of seconds.
249 Implemented using C<ualarm()>. The C<$interval_floating_seconds> argument
250 is optional and will be zero if unspecified, resulting in C<alarm()>-like
251 behaviour. This function can be imported, resulting in a nice drop-in
252 replacement for the C<alarm> provided with perl, see the L</EXAMPLES> below.
254 B<NOTE 1>: With some combinations of operating systems and Perl
255 releases C<SIGALRM> restarts C<select()>, instead of interrupting it.
256 This means that an C<alarm()> followed by a C<select()> may together
257 take the sum of the times specified for the the C<alarm()> and the
258 C<select()>, not just the time of the C<alarm()>.
260 Note that the interaction between alarms and sleeps is unspecified.
262 =item setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )
264 Start up an interval timer: after a certain time, a signal arrives,
265 and more signals may keep arriving at certain intervals. To disable
266 an "itimer", use C<$floating_seconds> of zero. If the
267 C<$interval_floating_seconds> is set to zero (or unspecified), the
268 timer is disabled B<after> the next delivered signal.
270 Use of interval timers may interfere with C<alarm()>, C<sleep()>,
271 and C<usleep()>. In standard-speak the "interaction is unspecified",
272 which means that I<anything> may happen: it may work, it may not.
274 In scalar context, the remaining time in the timer is returned.
276 In list context, both the remaining time and the interval are returned.
278 There are usually three or four interval timers available: the
279 C<$which> can be C<ITIMER_REAL>, C<ITIMER_VIRTUAL>, C<ITIMER_PROF>, or
280 C<ITIMER_REALPROF>. Note that which ones are available depends: true
281 UNIX platforms usually have the first three, but (for example) Win32
282 and Cygwin have only C<ITIMER_REAL>, and only Solaris seems to have
283 C<ITIMER_REALPROF> (which is used to profile multithreaded programs).
285 C<ITIMER_REAL> results in C<alarm()>-like behaviour. Time is counted in
286 I<real time>; that is, wallclock time. C<SIGALRM> is delivered when
289 C<ITIMER_VIRTUAL> counts time in (process) I<virtual time>; that is,
290 only when the process is running. In multiprocessor/user/CPU systems
291 this may be more or less than real or wallclock time. (This time is
292 also known as the I<user time>.) C<SIGVTALRM> is delivered when the
295 C<ITIMER_PROF> counts time when either the process virtual time or when
296 the operating system is running on behalf of the process (such as I/O).
297 (This time is also known as the I<system time>.) (The sum of user
298 time and system time is known as the I<CPU time>.) C<SIGPROF> is
299 delivered when the timer expires. C<SIGPROF> can interrupt system calls.
301 The semantics of interval timers for multithreaded programs are
302 system-specific, and some systems may support additional interval
303 timers. See your C<setitimer()> documentation.
305 =item getitimer ( $which )
307 Return the remaining time in the interval timer specified by C<$which>.
309 In scalar context, the remaining time is returned.
311 In list context, both the remaining time and the interval are returned.
312 The interval is always what you put in using C<setitimer()>.
314 =item clock_gettime ( $which )
316 Return as seconds the current value of the POSIX high resolution timer
317 specified by C<$which>. All implementations that support POSIX high
318 resolution timers are supposed to support at least the C<$which> value
319 of C<CLOCK_REALTIME>, which is supposed to return results close to the
320 results of C<gettimeofday>, or the number of seconds since 00:00:00:00
321 January 1, 1970 Greenwich Mean Time (GMT). Do not assume that
322 CLOCK_REALTIME is zero, it might be one, or something else.
323 Another potentially useful (but not available everywhere) value is
324 C<CLOCK_MONOTONIC>, which guarantees a monotonically increasing time
325 value (unlike time(), which can be adjusted). See your system
326 documentation for other possibly supported values.
328 =item clock_getres ( $which )
330 Return as seconds the resolution of the POSIX high resolution timer
331 specified by C<$which>. All implementations that support POSIX high
332 resolution timers are supposed to support at least the C<$which> value
333 of C<CLOCK_REALTIME>, see L</clock_gettime>.
335 =item clock_nanosleep ( $which, $seconds, $flags = 0)
337 Sleeps for the number of seconds (1e9ths of a second) specified.
338 Returns the number of seconds actually slept. The $which is the
339 "clock id", as with clock_gettime() and clock_getres(). The flags
340 default to zero but C<TIMER_ABSTIME> can specified (must be exported
341 explicitly) which means that C<$nanoseconds> is not a time interval
342 (as is the default) but instead an absolute time. Can sleep for more
343 than one second. Can also sleep for zero seconds, which often works
344 like a I<thread yield>. See also C<Time::HiRes::sleep()>,
345 C<Time::HiRes::usleep()>, and C<Time::HiRes::nanosleep()>.
347 Do not expect clock_nanosleep() to be exact down to one nanosecond.
348 Getting even accuracy of one thousand nanoseconds is good.
352 Return as seconds the I<process time> (user + system time) spent by
353 the process since the first call to clock() (the definition is B<not>
354 "since the start of the process", though if you are lucky these times
355 may be quite close to each other, depending on the system). What this
356 means is that you probably need to store the result of your first call
357 to clock(), and subtract that value from the following results of clock().
359 The time returned also includes the process times of the terminated
360 child processes for which wait() has been executed. This value is
361 somewhat like the second value returned by the times() of core Perl,
362 but not necessarily identical. Note that due to backward
363 compatibility limitations the returned value may wrap around at about
364 2147 seconds or at about 36 minutes.
372 As L<perlfunc/stat> but with the access/modify/change file timestamps
373 in subsecond resolution, if the operating system and the filesystem
374 both support such timestamps. To override the standard stat():
376 use Time::HiRes qw(stat);
378 Test for the value of &Time::HiRes::d_hires_stat to find out whether
379 the operating system supports subsecond file timestamps: a value
380 larger than zero means yes. There are unfortunately no easy
381 ways to find out whether the filesystem supports such timestamps.
382 UNIX filesystems often do; NTFS does; FAT doesn't (FAT timestamp
383 granularity is B<two> seconds).
385 A zero return value of &Time::HiRes::d_hires_stat means that
386 Time::HiRes::stat is a no-op passthrough for CORE::stat(),
387 and therefore the timestamps will stay integers. The same
388 will happen if the filesystem does not do subsecond timestamps,
389 even if the &Time::HiRes::d_hires_stat is non-zero.
391 In any case do not expect nanosecond resolution, or even a microsecond
398 use Time::HiRes qw(usleep ualarm gettimeofday tv_interval);
400 $microseconds = 750_000;
401 usleep($microseconds);
403 # signal alarm in 2.5s & every .1s thereafter
404 ualarm(2_500_000, 100_000);
406 # get seconds and microseconds since the epoch
407 ($s, $usec) = gettimeofday();
409 # measure elapsed time
410 # (could also do by subtracting 2 gettimeofday return values)
411 $t0 = [gettimeofday];
412 # do bunch of stuff here
413 $t1 = [gettimeofday];
415 $t0_t1 = tv_interval $t0, $t1;
417 $elapsed = tv_interval ($t0, [gettimeofday]);
418 $elapsed = tv_interval ($t0); # equivalent code
421 # replacements for time, alarm and sleep that know about
425 $now_fractions = Time::HiRes::time;
426 Time::HiRes::sleep (2.5);
427 Time::HiRes::alarm (10.6666666);
429 use Time::HiRes qw ( time alarm sleep );
430 $now_fractions = time;
434 # Arm an interval timer to go off first at 10 seconds and
435 # after that every 2.5 seconds, in process virtual time
437 use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time );
439 $SIG{VTALRM} = sub { print time, "\n" };
440 setitimer(ITIMER_VIRTUAL, 10, 2.5);
442 use Time::HiRes qw( clock_gettime clock_getres CLOCK_REALTIME );
443 # Read the POSIX high resolution timer.
444 my $high = clock_getres(CLOCK_REALTIME);
445 # But how accurate we can be, really?
446 my $reso = clock_getres(CLOCK_REALTIME);
448 use Time::HiRes qw( clock_nanosleep TIMER_ABSTIME );
449 clock_nanosleep(CLOCK_REALTIME, 1e6);
450 clock_nanosleep(CLOCK_REALTIME, 2e9, TIMER_ABSTIME);
452 use Time::HiRes qw( clock );
453 my $clock0 = clock();
455 my $clock1 = clock();
456 my $clockd = $clock1 - $clock0;
458 use Time::HiRes qw( stat );
459 my ($atime, $mtime, $ctime) = (stat("istics"))[8, 9, 10];
463 In addition to the perl API described above, a C API is available for
464 extension writers. The following C functions are available in the
468 --------------- ----------------------
469 Time::NVtime double (*)()
470 Time::U2time void (*)(pTHX_ UV ret[2])
472 Both functions return equivalent information (like C<gettimeofday>)
473 but with different representations. The names C<NVtime> and C<U2time>
474 were selected mainly because they are operating system independent.
475 (C<gettimeofday> is Unix-centric, though some platforms like Win32 and
476 VMS have emulations for it.)
478 Here is an example of using C<NVtime> from C:
480 double (*myNVtime)(); /* Returns -1 on failure. */
481 SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0);
482 if (!svp) croak("Time::HiRes is required");
483 if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer");
484 myNVtime = INT2PTR(double(*)(), SvIV(*svp));
485 printf("The current time is: %f\n", (*myNVtime)());
489 =head2 useconds or interval more than ...
491 In ualarm() you tried to use number of microseconds or interval (also
492 in microseconds) more than 1_000_000 and setitimer() is not available
493 in your system to emulate that case.
495 =head2 negative time not invented yet
497 You tried to use a negative time argument.
499 =head2 internal error: useconds < 0 (unsigned ... signed ...)
501 Something went horribly wrong-- the number of microseconds that cannot
502 become negative just became negative. Maybe your compiler is broken?
506 Notice that the core C<time()> maybe rounding rather than truncating.
507 What this means is that the core C<time()> may be reporting the time
508 as one second later than C<gettimeofday()> and C<Time::HiRes::time()>.
510 Adjusting the system clock (either manually or by services like ntp)
511 may cause problems, especially for long running programs that assume
512 a monotonously increasing time (note that all platforms do not adjust
513 time as gracefully as UNIX ntp does). For example in Win32 (and derived
514 platforms like Cygwin and MinGW) the Time::HiRes::time() may temporarily
515 drift off from the system clock (and the original time()) by up to 0.5
516 seconds. Time::HiRes will notice this eventually and recalibrate.
517 Note that since Time::HiRes 1.77 the clock_gettime(CLOCK_MONOTONIC)
518 might help in this (in case your system supports CLOCK_MONOTONIC).
522 Perl modules L<BSD::Resource>, L<Time::TAI64>.
524 Your system documentation for C<clock_gettime>, C<clock_settime>,
525 C<gettimeofday>, C<getitimer>, C<setitimer>, C<ualarm>.
529 D. Wegscheid <wegscd@whirlpool.com>
530 R. Schertler <roderick@argon.org>
531 J. Hietaniemi <jhi@iki.fi>
532 G. Aas <gisle@aas.no>
534 =head1 COPYRIGHT AND LICENSE
536 Copyright (c) 1996-2002 Douglas E. Wegscheid. All rights reserved.
538 Copyright (c) 2002, 2003, 2004, 2005, 2006 Jarkko Hietaniemi. All rights reserved.
540 This program is free software; you can redistribute it and/or modify
541 it under the same terms as Perl itself.