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 ualarm, usleep, and gettimeofday
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, ualarm,
84 and gettimeofday system calls. See the EXAMPLES section below and the test
85 scripts for usage; see your system documentation for the description of
86 the underlying gettimeofday, usleep, and ualarm calls.
88 If your system lacks gettimeofday(2) you don't get gettimeofday() or the
89 one-arg form of tv_interval(). If you don't have usleep(3) or select(2)
90 you don't get usleep() or sleep(). If your system don't have ualarm(3)
91 or setitimer(2) you don't get ualarm() or alarm().
92 If you try to import an unimplemented function in the C<use> statement
93 it will fail at compile time.
95 The following functions can be imported from this module.
96 No functions are exported by default.
100 =item gettimeofday ()
102 In array context it returns a 2 element array with the seconds and
103 microseconds since the epoch. In scalar context it returns floating
104 seconds like Time::HiRes::time() (see below).
106 =item usleep ( $useconds )
108 Issues a usleep for the number of microseconds specified. See also
109 Time::HiRes::sleep() below.
111 =item ualarm ( $useconds [, $interval_useconds ] )
113 Issues a ualarm call; interval_useconds is optional and will be 0 if
114 unspecified, resulting in alarm-like behaviour.
118 S<tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] )>
120 Returns the floating seconds between the two times, which should have been
121 returned by gettimeofday(). If the second argument is omitted, then the
122 current time is used.
126 Returns a floating seconds since the epoch. This function can be imported,
127 resulting in a nice drop-in replacement for the C<time> provided with perl,
128 see the EXAMPLES below.
130 B<NOTE>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT the
131 default floating point format of Perl and the seconds since epoch
132 have conspired to produce an apparent bug: if you print the value
133 of Time::HiRes::time() you seem to be getting only five decimals,
134 not six as promised (microseconds). Not to worry, the microseconds
135 are there (assuming your platform supports such granularity).
136 What is going on is that the default floating point format of Perl
137 only outputs 15 digits. In this case that means ten digits before the
138 decimal separator and five after. To see the microseconds you can use
139 either printf/sprintf with C<%.6f>, or the gettimeofday() function in
140 list context, which will give you the seconds and microseconds as two
143 =item sleep ( $floating_seconds )
145 Converts $floating_seconds to microseconds and issues a usleep for the
146 result. This function can be imported, resulting in a nice drop-in
147 replacement for the C<sleep> provided with perl, see the EXAMPLES below.
149 =item alarm ( $floating_seconds [, $interval_floating_seconds ] )
151 Converts $floating_seconds and $interval_floating_seconds and issues
152 a ualarm for the results. The $interval_floating_seconds argument
153 is optional and will be 0 if unspecified, resulting in alarm-like
154 behaviour. This function can be imported, resulting in a nice drop-in
155 replacement for the C<alarm> provided with perl, see the EXAMPLES below.
159 S<setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )>
161 Start up an interval timer: after a certain time, a signal is arrives,
162 and more may keep arriving at certain intervals. To disable a timer,
163 use time of zero. If interval is set to zero (or unspecified), the
164 timer is disabled after the next delivered signal.
166 Use of interval timers may interfere with alarm(), sleep(), and usleep().
167 In standard-speak the "interaction is unspecified", which means that
168 I<anything> may happen: it may work, it may not.
170 In scalar context, the remaining time in the timer is returned.
172 In list context, both the remaining time and the interval are returned.
174 There are three interval timers: the $which can be ITIMER_REAL,
175 ITIMER_VIRTUAL, or ITIMER_PROF.
177 ITIMER_REAL results in alarm()-like behavior. Time is counted in
178 I<real time>, that is, wallclock time. SIGALRM is delivered when
181 ITIMER_VIRTUAL counts time in (process) I<virtual time>, that is, only
182 when the process is running. In multiprocessing/user/CPU systems this
183 may be much less than real time. (This time is also known as the
184 I<user time>.) SIGVTALRM is delivered when the timer expires.
186 ITIMER_PROF counts time when either the process virtual time or when
187 the operating system is running on behalf of the process (such as
188 I/O). (This time is also known as the I<system time>.) (Collectively
189 these times are also known as the I<CPU time>.) SIGPROF is delivered
190 when the timer expires. SIGPROF can interrupt system calls.
192 The semantics of interval timers for multithreaded programs are
193 system-specific, and some systems may support additional interval
194 timers. See your setitimer() documentation.
196 =item getitimer ( $which )
198 Return the remaining time in the interval timer specified by $which.
200 In scalar context, the remaining time is returned.
202 In list context, both the remaining time and the interval are returned.
203 The interval is always what you put in using setitimer().
209 use Time::HiRes qw(usleep ualarm gettimeofday tv_interval);
211 $microseconds = 750_000;
212 usleep $microseconds;
214 # signal alarm in 2.5s & every .1s thereafter
215 ualarm 2_500_000, 100_000;
217 # get seconds and microseconds since the epoch
218 ($s, $usec) = gettimeofday;
220 # measure elapsed time
221 # (could also do by subtracting 2 gettimeofday return values)
222 $t0 = [gettimeofday];
223 # do bunch of stuff here
224 $t1 = [gettimeofday];
226 $t0_t1 = tv_interval $t0, $t1;
228 $elapsed = tv_interval ($t0, [gettimeofday]);
229 $elapsed = tv_interval ($t0); # equivalent code
232 # replacements for time, alarm and sleep that know about
236 $now_fractions = Time::HiRes::time;
237 Time::HiRes::sleep (2.5);
238 Time::HiRes::alarm (10.6666666);
240 use Time::HiRes qw ( time alarm sleep );
241 $now_fractions = time;
245 # Arm an interval timer to go off first at 10 seconds and
246 # after that every 2.5 seconds, in process virtual time
248 use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time );
250 $SIG{VTLARM} = sub { print time, "\n" };
251 setitimer(ITIMER_VIRTUAL, 10, 2.5);
255 In addition to the perl API described above, a C API is available for
256 extension writers. The following C functions are available in the
260 --------------- ----------------------
261 Time::NVtime double (*)()
262 Time::U2time void (*)(UV ret[2])
264 Both functions return equivalent information (like C<gettimeofday>)
265 but with different representations. The names C<NVtime> and C<U2time>
266 were selected mainly because they are operating system independent.
267 (C<gettimeofday> is Un*x-centric.)
269 Here is an example of using NVtime from C:
271 double (*myNVtime)();
272 SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0);
273 if (!svp) croak("Time::HiRes is required");
274 if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer");
275 myNVtime = (double(*)()) SvIV(*svp);
276 printf("The current time is: %f\n", (*myNVtime)());
280 Notice that the core time() maybe rounding rather than truncating.
281 What this means that the core time() may be giving time one second
282 later than gettimeofday(), also known as Time::HiRes::time().
286 D. Wegscheid <wegscd@whirlpool.com>
287 R. Schertler <roderick@argon.org>
288 J. Hietaniemi <jhi@iki.fi>
289 G. Aas <gisle@aas.no>
293 $Id: HiRes.pm,v 1.20 1999/03/16 02:26:13 wegscd Exp $
296 Revision 1.20 1999/03/16 02:26:13 wegscd
297 Add documentation for NVTime and U2Time.
299 Revision 1.19 1998/09/30 02:34:42 wegscd
300 No changes, bump version.
302 Revision 1.18 1998/07/07 02:41:35 wegscd
303 No changes, bump version.
305 Revision 1.17 1998/07/02 01:45:13 wegscd
308 Revision 1.16 1997/11/13 02:06:36 wegscd
309 version bump to accomodate HiRes.xs fix.
311 Revision 1.15 1997/11/11 02:17:59 wegscd
312 POD editing, courtesy of Gisle Aas.
314 Revision 1.14 1997/11/06 03:14:35 wegscd
315 Update version # for Makefile.PL and HiRes.xs changes.
317 Revision 1.13 1997/11/05 05:36:25 wegscd
318 change version # for Makefile.pl and HiRes.xs changes.
320 Revision 1.12 1997/10/13 20:55:33 wegscd
321 Force a new version for Makefile.PL changes.
323 Revision 1.11 1997/09/05 19:59:33 wegscd
324 New version to bump version for README and Makefile.PL fixes.
327 Revision 1.10 1997/05/23 01:11:38 wegscd
328 Conditional compilation; EXPORT_FAIL fixes.
330 Revision 1.2 1996/12/30 13:28:40 wegscd
331 Update documentation for what to do when missing ualarm() and friends.
333 Revision 1.1 1996/10/17 20:53:31 wegscd
334 Fix =head1 being next to __END__ so pod2man works
336 Revision 1.0 1996/09/03 18:25:15 wegscd
341 Copyright (c) 1996-1997 Douglas E. Wegscheid.
342 All rights reserved. This program is free software; you can
343 redistribute it and/or modify it under the same terms as Perl itself.