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
131 (when the time() seconds since epoch rolled over to 1_000_000_000),
132 the default floating point format of Perl and the seconds since epoch
133 have conspired to produce an apparent bug: if you print the value of
134 Time::HiRes::time() you seem to be getting only five decimals, not six
135 as promised (microseconds). Not to worry, the microseconds are there
136 (assuming your platform supports such granularity). What is going on
137 is that the default floating point format of Perl only outputs 15
138 digits. In this case that means ten digits before the decimal
139 separator and five after. To see the microseconds you can use either
140 printf/sprintf with C<%.6f>, or the gettimeofday() function in list
141 context, which will give you the seconds and microseconds as two
144 =item sleep ( $floating_seconds )
146 Converts $floating_seconds to microseconds and issues a usleep for the
147 result. This function can be imported, resulting in a nice drop-in
148 replacement for the C<sleep> provided with perl, see the EXAMPLES below.
150 =item alarm ( $floating_seconds [, $interval_floating_seconds ] )
152 Converts $floating_seconds and $interval_floating_seconds and issues
153 a ualarm for the results. The $interval_floating_seconds argument
154 is optional and will be 0 if unspecified, resulting in alarm-like
155 behaviour. This function can be imported, resulting in a nice drop-in
156 replacement for the C<alarm> provided with perl, see the EXAMPLES below.
160 S<setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )>
162 Start up an interval timer: after a certain time, a signal is arrives,
163 and more may keep arriving at certain intervals. To disable a timer,
164 use time of zero. If interval is set to zero (or unspecified), the
165 timer is disabled after the next delivered signal.
167 Use of interval timers may interfere with alarm(), sleep(), and usleep().
168 In standard-speak the "interaction is unspecified", which means that
169 I<anything> may happen: it may work, it may not.
171 In scalar context, the remaining time in the timer is returned.
173 In list context, both the remaining time and the interval are returned.
175 There are three interval timers: the $which can be ITIMER_REAL,
176 ITIMER_VIRTUAL, or ITIMER_PROF.
178 ITIMER_REAL results in alarm()-like behavior. Time is counted in
179 I<real time>, that is, wallclock time. SIGALRM is delivered when
182 ITIMER_VIRTUAL counts time in (process) I<virtual time>, that is, only
183 when the process is running. In multiprocessing/user/CPU systems this
184 may be much less than real time. (This time is also known as the
185 I<user time>.) SIGVTALRM is delivered when the timer expires.
187 ITIMER_PROF counts time when either the process virtual time or when
188 the operating system is running on behalf of the process (such as
189 I/O). (This time is also known as the I<system time>.) (Collectively
190 these times are also known as the I<CPU time>.) SIGPROF is delivered
191 when the timer expires. SIGPROF can interrupt system calls.
193 The semantics of interval timers for multithreaded programs are
194 system-specific, and some systems may support additional interval
195 timers. See your setitimer() documentation.
197 =item getitimer ( $which )
199 Return the remaining time in the interval timer specified by $which.
201 In scalar context, the remaining time is returned.
203 In list context, both the remaining time and the interval are returned.
204 The interval is always what you put in using setitimer().
210 use Time::HiRes qw(usleep ualarm gettimeofday tv_interval);
212 $microseconds = 750_000;
213 usleep $microseconds;
215 # signal alarm in 2.5s & every .1s thereafter
216 ualarm 2_500_000, 100_000;
218 # get seconds and microseconds since the epoch
219 ($s, $usec) = gettimeofday;
221 # measure elapsed time
222 # (could also do by subtracting 2 gettimeofday return values)
223 $t0 = [gettimeofday];
224 # do bunch of stuff here
225 $t1 = [gettimeofday];
227 $t0_t1 = tv_interval $t0, $t1;
229 $elapsed = tv_interval ($t0, [gettimeofday]);
230 $elapsed = tv_interval ($t0); # equivalent code
233 # replacements for time, alarm and sleep that know about
237 $now_fractions = Time::HiRes::time;
238 Time::HiRes::sleep (2.5);
239 Time::HiRes::alarm (10.6666666);
241 use Time::HiRes qw ( time alarm sleep );
242 $now_fractions = time;
246 # Arm an interval timer to go off first at 10 seconds and
247 # after that every 2.5 seconds, in process virtual time
249 use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time );
251 $SIG{VTLARM} = sub { print time, "\n" };
252 setitimer(ITIMER_VIRTUAL, 10, 2.5);
256 In addition to the perl API described above, a C API is available for
257 extension writers. The following C functions are available in the
261 --------------- ----------------------
262 Time::NVtime double (*)()
263 Time::U2time void (*)(UV ret[2])
265 Both functions return equivalent information (like C<gettimeofday>)
266 but with different representations. The names C<NVtime> and C<U2time>
267 were selected mainly because they are operating system independent.
268 (C<gettimeofday> is Un*x-centric.)
270 Here is an example of using NVtime from C:
272 double (*myNVtime)();
273 SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0);
274 if (!svp) croak("Time::HiRes is required");
275 if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer");
276 myNVtime = (double(*)()) SvIV(*svp);
277 printf("The current time is: %f\n", (*myNVtime)());
281 Notice that the core time() maybe rounding rather than truncating.
282 What this means that the core time() may be giving time one second
283 later than gettimeofday(), also known as Time::HiRes::time().
287 D. Wegscheid <wegscd@whirlpool.com>
288 R. Schertler <roderick@argon.org>
289 J. Hietaniemi <jhi@iki.fi>
290 G. Aas <gisle@aas.no>
294 $Id: HiRes.pm,v 1.20 1999/03/16 02:26:13 wegscd Exp $
297 Revision 1.20 1999/03/16 02:26:13 wegscd
298 Add documentation for NVTime and U2Time.
300 Revision 1.19 1998/09/30 02:34:42 wegscd
301 No changes, bump version.
303 Revision 1.18 1998/07/07 02:41:35 wegscd
304 No changes, bump version.
306 Revision 1.17 1998/07/02 01:45:13 wegscd
309 Revision 1.16 1997/11/13 02:06:36 wegscd
310 version bump to accomodate HiRes.xs fix.
312 Revision 1.15 1997/11/11 02:17:59 wegscd
313 POD editing, courtesy of Gisle Aas.
315 Revision 1.14 1997/11/06 03:14:35 wegscd
316 Update version # for Makefile.PL and HiRes.xs changes.
318 Revision 1.13 1997/11/05 05:36:25 wegscd
319 change version # for Makefile.pl and HiRes.xs changes.
321 Revision 1.12 1997/10/13 20:55:33 wegscd
322 Force a new version for Makefile.PL changes.
324 Revision 1.11 1997/09/05 19:59:33 wegscd
325 New version to bump version for README and Makefile.PL fixes.
328 Revision 1.10 1997/05/23 01:11:38 wegscd
329 Conditional compilation; EXPORT_FAIL fixes.
331 Revision 1.2 1996/12/30 13:28:40 wegscd
332 Update documentation for what to do when missing ualarm() and friends.
334 Revision 1.1 1996/10/17 20:53:31 wegscd
335 Fix =head1 being next to __END__ so pod2man works
337 Revision 1.0 1996/09/03 18:25:15 wegscd
342 Copyright (c) 1996-1997 Douglas E. Wegscheid.
343 All rights reserved. This program is free software; you can
344 redistribute it and/or modify it under the same terms as Perl itself.