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 =item sleep ( $floating_seconds )
132 Converts $floating_seconds to microseconds and issues a usleep for the
133 result. This function can be imported, resulting in a nice drop-in
134 replacement for the C<sleep> provided with perl, see the EXAMPLES below.
136 =item alarm ( $floating_seconds [, $interval_floating_seconds ] )
138 Converts $floating_seconds and $interval_floating_seconds and issues
139 a ualarm for the results. The $interval_floating_seconds argument
140 is optional and will be 0 if unspecified, resulting in alarm-like
141 behaviour. This function can be imported, resulting in a nice drop-in
142 replacement for the C<alarm> provided with perl, see the EXAMPLES below.
146 S<setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )>
148 Start up an interval timer: after a certain time, a signal is arrives,
149 and more may keep arriving at certain intervals. To disable a timer,
150 use time of zero. If interval is set to zero (or unspecified), the
151 timer is disabled after the next delivered signal.
153 Use of interval timers may interfere with alarm(), sleep(), and usleep().
154 In standard-speak the "interaction is unspecified", which means that
155 I<anything> may happen: it may work, it may not.
157 In scalar context, the remaining time in the timer is returned.
159 In list context, both the remaining time and the interval are returned.
161 There are three interval timers: the $which can be ITIMER_REAL,
162 ITIMER_VIRTUAL, or ITIMER_PROF.
164 ITIMER_REAL results in alarm()-like behavior. Time is counted in
165 I<real time>, that is, wallclock time. SIGALRM is delivered when
168 ITIMER_VIRTUAL counts time in (process) I<virtual time>, that is, only
169 when the process is running. In multiprocessing/user/CPU systems this
170 may be much less than real time. (This time is also known as the
171 I<user time>.) SIGVTALRM is delivered when the timer expires.
173 ITIMER_PROF counts time when either the process virtual time or when
174 the operating system is running on behalf of the process (such as
175 I/O). (This time is also known as the I<system time>.) (Collectively
176 these times are also known as the I<CPU time>.) SIGPROF is delivered
177 when the timer expires. SIGPROF can interrupt system calls.
179 The semantics of interval timers for multithreaded programs are
180 system-specific, and some systems may support additional interval
181 timers. See your setitimer() documentation.
183 =item getitimer ( $which )
185 Return the remaining time in the interval timer specified by $which.
187 In scalar context, the remaining time is returned.
189 In list context, both the remaining time and the interval are returned.
190 The interval is always what you put in using setitimer().
196 use Time::HiRes qw(usleep ualarm gettimeofday tv_interval);
198 $microseconds = 750_000;
199 usleep $microseconds;
201 # signal alarm in 2.5s & every .1s thereafter
202 ualarm 2_500_000, 100_000;
204 # get seconds and microseconds since the epoch
205 ($s, $usec) = gettimeofday;
207 # measure elapsed time
208 # (could also do by subtracting 2 gettimeofday return values)
209 $t0 = [gettimeofday];
210 # do bunch of stuff here
211 $t1 = [gettimeofday];
213 $t0_t1 = tv_interval $t0, $t1;
215 $elapsed = tv_interval ($t0, [gettimeofday]);
216 $elapsed = tv_interval ($t0); # equivalent code
219 # replacements for time, alarm and sleep that know about
223 $now_fractions = Time::HiRes::time;
224 Time::HiRes::sleep (2.5);
225 Time::HiRes::alarm (10.6666666);
227 use Time::HiRes qw ( time alarm sleep );
228 $now_fractions = time;
232 # Arm an interval timer to go off first at 10 seconds and
233 # after that every 2.5 seconds, in process virtual time
235 use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time );
237 $SIG{VTLARM} = sub { print time, "\n" };
238 setitimer(ITIMER_VIRTUAL, 10, 2.5);
242 In addition to the perl API described above, a C API is available for
243 extension writers. The following C functions are available in the
247 --------------- ----------------------
248 Time::NVtime double (*)()
249 Time::U2time void (*)(UV ret[2])
251 Both functions return equivalent information (like C<gettimeofday>)
252 but with different representations. The names C<NVtime> and C<U2time>
253 were selected mainly because they are operating system independent.
254 (C<gettimeofday> is Un*x-centric.)
256 Here is an example of using NVtime from C:
258 double (*myNVtime)();
259 SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0);
260 if (!svp) croak("Time::HiRes is required");
261 if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer");
262 myNVtime = (double(*)()) SvIV(*svp);
263 printf("The current time is: %f\n", (*myNVtime)());
267 D. Wegscheid <wegscd@whirlpool.com>
268 R. Schertler <roderick@argon.org>
269 J. Hietaniemi <jhi@iki.fi>
270 G. Aas <gisle@aas.no>
274 $Id: HiRes.pm,v 1.20 1999/03/16 02:26:13 wegscd Exp $
277 Revision 1.20 1999/03/16 02:26:13 wegscd
278 Add documentation for NVTime and U2Time.
280 Revision 1.19 1998/09/30 02:34:42 wegscd
281 No changes, bump version.
283 Revision 1.18 1998/07/07 02:41:35 wegscd
284 No changes, bump version.
286 Revision 1.17 1998/07/02 01:45:13 wegscd
289 Revision 1.16 1997/11/13 02:06:36 wegscd
290 version bump to accomodate HiRes.xs fix.
292 Revision 1.15 1997/11/11 02:17:59 wegscd
293 POD editing, courtesy of Gisle Aas.
295 Revision 1.14 1997/11/06 03:14:35 wegscd
296 Update version # for Makefile.PL and HiRes.xs changes.
298 Revision 1.13 1997/11/05 05:36:25 wegscd
299 change version # for Makefile.pl and HiRes.xs changes.
301 Revision 1.12 1997/10/13 20:55:33 wegscd
302 Force a new version for Makefile.PL changes.
304 Revision 1.11 1997/09/05 19:59:33 wegscd
305 New version to bump version for README and Makefile.PL fixes.
308 Revision 1.10 1997/05/23 01:11:38 wegscd
309 Conditional compilation; EXPORT_FAIL fixes.
311 Revision 1.2 1996/12/30 13:28:40 wegscd
312 Update documentation for what to do when missing ualarm() and friends.
314 Revision 1.1 1996/10/17 20:53:31 wegscd
315 Fix =head1 being next to __END__ so pod2man works
317 Revision 1.0 1996/09/03 18:25:15 wegscd
322 Copyright (c) 1996-1997 Douglas E. Wegscheid.
323 All rights reserved. This program is free software; you can
324 redistribute it and/or modify it under the same terms as Perl itself.