4 use vars qw($VERSION @ISA @EXPORT @EXPORT_OK $AUTOLOAD);
12 @EXPORT_OK = qw (usleep sleep ualarm alarm gettimeofday time tv_interval
13 getitimer setitimer ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF);
19 ($constname= $AUTOLOAD) =~ s/.*:://;
20 my $val = constant($constname, @_ ? $_[0] : 0);
22 my ($pack,$file,$line) = caller;
23 die "Your vendor has not defined Time::HiRes macro $constname, used at $file line $line.\n";
27 *$AUTOLOAD = sub { $val };
32 XSLoader::load 'Time::HiRes', $VERSION;
34 # Preloaded methods go here.
37 # probably could have been done in C
39 $b = [gettimeofday()] unless defined($b);
40 (${$b}[0] - ${$a}[0]) + ((${$b}[1] - ${$a}[1]) / 1_000_000);
43 # Autoload methods go after =cut, and are processed by the autosplit program.
50 Time::HiRes - High resolution alarm, sleep, gettimeofday, interval timers
54 use Time::HiRes qw( usleep ualarm gettimeofday tv_interval );
56 usleep ($microseconds);
58 ualarm ($microseconds);
59 ualarm ($microseconds, $interval_microseconds);
62 ($seconds, $microseconds) = gettimeofday;
64 $elapsed = tv_interval ( $t0, [$seconds, $microseconds]);
65 $elapsed = tv_interval ( $t0, [gettimeofday]);
66 $elapsed = tv_interval ( $t0 );
68 use Time::HiRes qw ( time alarm sleep );
70 $now_fractions = time;
71 sleep ($floating_seconds);
72 alarm ($floating_seconds);
73 alarm ($floating_seconds, $floating_interval);
75 use Time::HiRes qw( setitimer getitimer
76 ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF );
78 setitimer ($which, $floating_seconds, $floating_interval );
83 The C<Time::HiRes> module implements a Perl interface to the usleep,
84 ualarm, gettimeofday, and setitimer/getitimer system calls. See the
85 EXAMPLES section below and the test scripts for usage; see your system
86 documentation for the description of the underlying usleep, ualarm,
87 gettimeofday, and setitimer/getitimer calls.
89 If your system lacks gettimeofday(2) or an emulation of it you don't
90 get gettimeofday() or the one-arg form of tv_interval().
91 If you don't have usleep(3) or select(2) you don't get usleep()
92 or sleep(). If your system don't have ualarm(3) or setitimer(2) you
93 don't get ualarm() or alarm(). If you try to import an unimplemented
94 function in the C<use> statement it will fail at compile time.
96 The following functions can be imported from this module.
97 No functions are exported by default.
101 =item gettimeofday ()
103 In array context returns a 2 element array with the seconds and
104 microseconds since the epoch. In scalar context returns floating
105 seconds like Time::HiRes::time() (see below).
107 =item usleep ( $useconds )
109 Sleeps for the number of microseconds specified. Returns the number
110 of microseconds actually slept. Can sleep for more than one second
111 unlike the usleep system call. See also Time::HiRes::sleep() below.
113 =item ualarm ( $useconds [, $interval_useconds ] )
115 Issues a ualarm call; interval_useconds is optional and will be 0 if
116 unspecified, resulting in alarm-like behaviour.
120 C<tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] )>
122 Returns the floating seconds between the two times, which should have
123 been returned by gettimeofday(). If the second argument is omitted,
124 then the current time is used.
128 Returns a floating seconds since the epoch. This function can be
129 imported, resulting in a nice drop-in replacement for the C<time>
130 provided with core Perl, see the EXAMPLES below.
132 B<NOTE 1>: this higher resolution timer can return values either less or
133 more than the core time(), depending on whether your platforms rounds
134 the higher resolution timer values up, down, or to the nearest to get
135 the core time(), but naturally the difference should be never more than
138 B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT
139 (when the time() seconds since epoch rolled over to 1_000_000_000),
140 the default floating point format of Perl and the seconds since epoch
141 have conspired to produce an apparent bug: if you print the value of
142 Time::HiRes::time() you seem to be getting only five decimals, not six
143 as promised (microseconds). Not to worry, the microseconds are there
144 (assuming your platform supports such granularity). What is going on
145 is that the default floating point format of Perl only outputs 15
146 digits. In this case that means ten digits before the decimal
147 separator and five after. To see the microseconds you can use either
148 printf/sprintf with C<%.6f>, or the gettimeofday() function in list
149 context, which will give you the seconds and microseconds as two
152 =item sleep ( $floating_seconds )
154 Sleeps for the specified amount of seconds. Returns the number of
155 seconds actually slept (a floating point value). This function can be
156 imported, resulting in a nice drop-in replacement for the C<sleep>
157 provided with perl, see the EXAMPLES below.
159 =item alarm ( $floating_seconds [, $interval_floating_seconds ] )
161 The SIGALRM signal is sent after the specfified number of seconds.
162 Implemented using ualarm(). The $interval_floating_seconds argument
163 is optional and will be 0 if unspecified, resulting in alarm()-like
164 behaviour. This function can be imported, resulting in a nice drop-in
165 replacement for the C<alarm> provided with perl, see the EXAMPLES below.
169 C<setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )>
171 Start up an interval timer: after a certain time, a signal is arrives,
172 and more may keep arriving at certain intervals. To disable a timer,
173 use time of zero. If interval is set to zero (or unspecified), the
174 timer is disabled after the next delivered signal.
176 Use of interval timers may interfere with alarm(), sleep(), and usleep().
177 In standard-speak the "interaction is unspecified", which means that
178 I<anything> may happen: it may work, it may not.
180 In scalar context, the remaining time in the timer is returned.
182 In list context, both the remaining time and the interval are returned.
184 There are three interval timers: the $which can be ITIMER_REAL,
185 ITIMER_VIRTUAL, or ITIMER_PROF.
187 ITIMER_REAL results in alarm()-like behavior. Time is counted in
188 I<real time>, that is, wallclock time. SIGALRM is delivered when
191 ITIMER_VIRTUAL counts time in (process) I<virtual time>, that is, only
192 when the process is running. In multiprocessing/user/CPU systems this
193 may be much less than real time. (This time is also known as the
194 I<user time>.) SIGVTALRM is delivered when the timer expires.
196 ITIMER_PROF counts time when either the process virtual time or when
197 the operating system is running on behalf of the process (such as
198 I/O). (This time is also known as the I<system time>.) (Collectively
199 these times are also known as the I<CPU time>.) SIGPROF is delivered
200 when the timer expires. SIGPROF can interrupt system calls.
202 The semantics of interval timers for multithreaded programs are
203 system-specific, and some systems may support additional interval
204 timers. See your setitimer() documentation.
206 =item getitimer ( $which )
208 Return the remaining time in the interval timer specified by $which.
210 In scalar context, the remaining time is returned.
212 In list context, both the remaining time and the interval are returned.
213 The interval is always what you put in using setitimer().
219 use Time::HiRes qw(usleep ualarm gettimeofday tv_interval);
221 $microseconds = 750_000;
222 usleep $microseconds;
224 # signal alarm in 2.5s & every .1s thereafter
225 ualarm 2_500_000, 100_000;
227 # get seconds and microseconds since the epoch
228 ($s, $usec) = gettimeofday;
230 # measure elapsed time
231 # (could also do by subtracting 2 gettimeofday return values)
232 $t0 = [gettimeofday];
233 # do bunch of stuff here
234 $t1 = [gettimeofday];
236 $t0_t1 = tv_interval $t0, $t1;
238 $elapsed = tv_interval ($t0, [gettimeofday]);
239 $elapsed = tv_interval ($t0); # equivalent code
242 # replacements for time, alarm and sleep that know about
246 $now_fractions = Time::HiRes::time;
247 Time::HiRes::sleep (2.5);
248 Time::HiRes::alarm (10.6666666);
250 use Time::HiRes qw ( time alarm sleep );
251 $now_fractions = time;
255 # Arm an interval timer to go off first at 10 seconds and
256 # after that every 2.5 seconds, in process virtual time
258 use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time );
260 $SIG{VTLARM} = sub { print time, "\n" };
261 setitimer(ITIMER_VIRTUAL, 10, 2.5);
265 In addition to the perl API described above, a C API is available for
266 extension writers. The following C functions are available in the
270 --------------- ----------------------
271 Time::NVtime double (*)()
272 Time::U2time void (*)(UV ret[2])
274 Both functions return equivalent information (like C<gettimeofday>)
275 but with different representations. The names C<NVtime> and C<U2time>
276 were selected mainly because they are operating system independent.
277 (C<gettimeofday> is Un*x-centric.)
279 Here is an example of using NVtime from C:
281 double (*myNVtime)();
282 SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0);
283 if (!svp) croak("Time::HiRes is required");
284 if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer");
285 myNVtime = (double(*)()) SvIV(*svp);
286 printf("The current time is: %f\n", (*myNVtime)());
290 Notice that the core time() maybe rounding rather than truncating.
291 What this means that the core time() may be giving time one second
292 later than gettimeofday(), also known as Time::HiRes::time().
296 D. Wegscheid <wegscd@whirlpool.com>
297 R. Schertler <roderick@argon.org>
298 J. Hietaniemi <jhi@iki.fi>
299 G. Aas <gisle@aas.no>
303 $Id: HiRes.pm,v 1.20 1999/03/16 02:26:13 wegscd Exp $
306 Revision 1.20 1999/03/16 02:26:13 wegscd
307 Add documentation for NVTime and U2Time.
309 Revision 1.19 1998/09/30 02:34:42 wegscd
310 No changes, bump version.
312 Revision 1.18 1998/07/07 02:41:35 wegscd
313 No changes, bump version.
315 Revision 1.17 1998/07/02 01:45:13 wegscd
318 Revision 1.16 1997/11/13 02:06:36 wegscd
319 version bump to accomodate HiRes.xs fix.
321 Revision 1.15 1997/11/11 02:17:59 wegscd
322 POD editing, courtesy of Gisle Aas.
324 Revision 1.14 1997/11/06 03:14:35 wegscd
325 Update version # for Makefile.PL and HiRes.xs changes.
327 Revision 1.13 1997/11/05 05:36:25 wegscd
328 change version # for Makefile.pl and HiRes.xs changes.
330 Revision 1.12 1997/10/13 20:55:33 wegscd
331 Force a new version for Makefile.PL changes.
333 Revision 1.11 1997/09/05 19:59:33 wegscd
334 New version to bump version for README and Makefile.PL fixes.
337 Revision 1.10 1997/05/23 01:11:38 wegscd
338 Conditional compilation; EXPORT_FAIL fixes.
340 Revision 1.2 1996/12/30 13:28:40 wegscd
341 Update documentation for what to do when missing ualarm() and friends.
343 Revision 1.1 1996/10/17 20:53:31 wegscd
344 Fix =head1 being next to __END__ so pod2man works
346 Revision 1.0 1996/09/03 18:25:15 wegscd
351 Copyright (c) 1996-1997 Douglas E. Wegscheid.
352 All rights reserved. This program is free software; you can
353 redistribute it and/or modify it under the same terms as Perl itself.