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. Returns the
109 number of microseconds actually slept. See also Time::HiRes::sleep()
112 =item ualarm ( $useconds [, $interval_useconds ] )
114 Issues a ualarm call; interval_useconds is optional and will be 0 if
115 unspecified, resulting in alarm-like behaviour.
119 S<tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] )>
121 Returns the floating seconds between the two times, which should have been
122 returned by gettimeofday(). If the second argument is omitted, then the
123 current time is used.
127 Returns a floating seconds since the epoch. This function can be imported,
128 resulting in a nice drop-in replacement for the C<time> provided with perl,
129 see the EXAMPLES below.
131 B<NOTE>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT
132 (when the time() seconds since epoch rolled over to 1_000_000_000),
133 the default floating point format of Perl and the seconds since epoch
134 have conspired to produce an apparent bug: if you print the value of
135 Time::HiRes::time() you seem to be getting only five decimals, not six
136 as promised (microseconds). Not to worry, the microseconds are there
137 (assuming your platform supports such granularity). What is going on
138 is that the default floating point format of Perl only outputs 15
139 digits. In this case that means ten digits before the decimal
140 separator and five after. To see the microseconds you can use either
141 printf/sprintf with C<%.6f>, or the gettimeofday() function in list
142 context, which will give you the seconds and microseconds as two
145 =item sleep ( $floating_seconds )
147 Converts $floating_seconds to microseconds and issues a usleep for the
148 result. Returns the number of seconds actually slept (a floating
149 point value). This function can be imported, resulting in a nice
150 drop-in replacement for the C<sleep> provided with perl, see the
153 =item alarm ( $floating_seconds [, $interval_floating_seconds ] )
155 Converts $floating_seconds and $interval_floating_seconds and issues
156 a ualarm for the results. The $interval_floating_seconds argument
157 is optional and will be 0 if unspecified, resulting in alarm-like
158 behaviour. This function can be imported, resulting in a nice drop-in
159 replacement for the C<alarm> provided with perl, see the EXAMPLES below.
163 S<setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )>
165 Start up an interval timer: after a certain time, a signal is arrives,
166 and more may keep arriving at certain intervals. To disable a timer,
167 use time of zero. If interval is set to zero (or unspecified), the
168 timer is disabled after the next delivered signal.
170 Use of interval timers may interfere with alarm(), sleep(), and usleep().
171 In standard-speak the "interaction is unspecified", which means that
172 I<anything> may happen: it may work, it may not.
174 In scalar context, the remaining time in the timer is returned.
176 In list context, both the remaining time and the interval are returned.
178 There are three interval timers: the $which can be ITIMER_REAL,
179 ITIMER_VIRTUAL, or ITIMER_PROF.
181 ITIMER_REAL results in alarm()-like behavior. Time is counted in
182 I<real time>, that is, wallclock time. SIGALRM is delivered when
185 ITIMER_VIRTUAL counts time in (process) I<virtual time>, that is, only
186 when the process is running. In multiprocessing/user/CPU systems this
187 may be much less than real time. (This time is also known as the
188 I<user time>.) SIGVTALRM is delivered when the timer expires.
190 ITIMER_PROF counts time when either the process virtual time or when
191 the operating system is running on behalf of the process (such as
192 I/O). (This time is also known as the I<system time>.) (Collectively
193 these times are also known as the I<CPU time>.) SIGPROF is delivered
194 when the timer expires. SIGPROF can interrupt system calls.
196 The semantics of interval timers for multithreaded programs are
197 system-specific, and some systems may support additional interval
198 timers. See your setitimer() documentation.
200 =item getitimer ( $which )
202 Return the remaining time in the interval timer specified by $which.
204 In scalar context, the remaining time is returned.
206 In list context, both the remaining time and the interval are returned.
207 The interval is always what you put in using setitimer().
213 use Time::HiRes qw(usleep ualarm gettimeofday tv_interval);
215 $microseconds = 750_000;
216 usleep $microseconds;
218 # signal alarm in 2.5s & every .1s thereafter
219 ualarm 2_500_000, 100_000;
221 # get seconds and microseconds since the epoch
222 ($s, $usec) = gettimeofday;
224 # measure elapsed time
225 # (could also do by subtracting 2 gettimeofday return values)
226 $t0 = [gettimeofday];
227 # do bunch of stuff here
228 $t1 = [gettimeofday];
230 $t0_t1 = tv_interval $t0, $t1;
232 $elapsed = tv_interval ($t0, [gettimeofday]);
233 $elapsed = tv_interval ($t0); # equivalent code
236 # replacements for time, alarm and sleep that know about
240 $now_fractions = Time::HiRes::time;
241 Time::HiRes::sleep (2.5);
242 Time::HiRes::alarm (10.6666666);
244 use Time::HiRes qw ( time alarm sleep );
245 $now_fractions = time;
249 # Arm an interval timer to go off first at 10 seconds and
250 # after that every 2.5 seconds, in process virtual time
252 use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time );
254 $SIG{VTLARM} = sub { print time, "\n" };
255 setitimer(ITIMER_VIRTUAL, 10, 2.5);
259 In addition to the perl API described above, a C API is available for
260 extension writers. The following C functions are available in the
264 --------------- ----------------------
265 Time::NVtime double (*)()
266 Time::U2time void (*)(UV ret[2])
268 Both functions return equivalent information (like C<gettimeofday>)
269 but with different representations. The names C<NVtime> and C<U2time>
270 were selected mainly because they are operating system independent.
271 (C<gettimeofday> is Un*x-centric.)
273 Here is an example of using NVtime from C:
275 double (*myNVtime)();
276 SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0);
277 if (!svp) croak("Time::HiRes is required");
278 if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer");
279 myNVtime = (double(*)()) SvIV(*svp);
280 printf("The current time is: %f\n", (*myNVtime)());
284 Notice that the core time() maybe rounding rather than truncating.
285 What this means that the core time() may be giving time one second
286 later than gettimeofday(), also known as Time::HiRes::time().
290 D. Wegscheid <wegscd@whirlpool.com>
291 R. Schertler <roderick@argon.org>
292 J. Hietaniemi <jhi@iki.fi>
293 G. Aas <gisle@aas.no>
297 $Id: HiRes.pm,v 1.20 1999/03/16 02:26:13 wegscd Exp $
300 Revision 1.20 1999/03/16 02:26:13 wegscd
301 Add documentation for NVTime and U2Time.
303 Revision 1.19 1998/09/30 02:34:42 wegscd
304 No changes, bump version.
306 Revision 1.18 1998/07/07 02:41:35 wegscd
307 No changes, bump version.
309 Revision 1.17 1998/07/02 01:45:13 wegscd
312 Revision 1.16 1997/11/13 02:06:36 wegscd
313 version bump to accomodate HiRes.xs fix.
315 Revision 1.15 1997/11/11 02:17:59 wegscd
316 POD editing, courtesy of Gisle Aas.
318 Revision 1.14 1997/11/06 03:14:35 wegscd
319 Update version # for Makefile.PL and HiRes.xs changes.
321 Revision 1.13 1997/11/05 05:36:25 wegscd
322 change version # for Makefile.pl and HiRes.xs changes.
324 Revision 1.12 1997/10/13 20:55:33 wegscd
325 Force a new version for Makefile.PL changes.
327 Revision 1.11 1997/09/05 19:59:33 wegscd
328 New version to bump version for README and Makefile.PL fixes.
331 Revision 1.10 1997/05/23 01:11:38 wegscd
332 Conditional compilation; EXPORT_FAIL fixes.
334 Revision 1.2 1996/12/30 13:28:40 wegscd
335 Update documentation for what to do when missing ualarm() and friends.
337 Revision 1.1 1996/10/17 20:53:31 wegscd
338 Fix =head1 being next to __END__ so pod2man works
340 Revision 1.0 1996/09/03 18:25:15 wegscd
345 Copyright (c) 1996-1997 Douglas E. Wegscheid.
346 All rights reserved. This program is free software; you can
347 redistribute it and/or modify it under the same terms as Perl itself.