Commit | Line | Data |
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dcf686c9 JH |
1 | package Time::HiRes; |
2 | ||
90e44bf6 | 3 | { use 5.006; } |
dcf686c9 | 4 | use strict; |
dcf686c9 JH |
5 | |
6 | require Exporter; | |
3f2ee006 | 7 | require DynaLoader; |
dcf686c9 | 8 | |
90e44bf6 | 9 | our @ISA = qw(Exporter DynaLoader); |
dcf686c9 | 10 | |
90e44bf6 Z |
11 | our @EXPORT = qw( ); |
12 | our @EXPORT_OK = qw (usleep sleep ualarm alarm gettimeofday time tv_interval | |
ced84e60 | 13 | getitimer setitimer nanosleep clock_gettime clock_getres |
170c5524 | 14 | clock clock_nanosleep |
ced84e60 | 15 | CLOCK_HIGHRES CLOCK_MONOTONIC CLOCK_PROCESS_CPUTIME_ID |
170c5524 SP |
16 | CLOCK_REALTIME CLOCK_SOFTTIME CLOCK_THREAD_CPUTIME_ID |
17 | CLOCK_TIMEOFDAY CLOCKS_PER_SEC | |
3f2ee006 | 18 | ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF ITIMER_REALPROF |
170c5524 | 19 | TIMER_ABSTIME |
3f2ee006 | 20 | d_usleep d_ualarm d_gettimeofday d_getitimer d_setitimer |
170c5524 | 21 | d_nanosleep d_clock_gettime d_clock_getres |
75d5269b SP |
22 | d_clock d_clock_nanosleep |
23 | stat | |
24 | ); | |
bf8300de | 25 | |
858dcda5 | 26 | our $VERSION = '1.9725'; |
90e44bf6 | 27 | our $XS_VERSION = $VERSION; |
105cd853 | 28 | $VERSION = eval $VERSION; |
3c72ec00 | 29 | |
90e44bf6 | 30 | our $AUTOLOAD; |
3c72ec00 JH |
31 | sub AUTOLOAD { |
32 | my $constname; | |
98b50af3 | 33 | ($constname = $AUTOLOAD) =~ s/.*:://; |
ced84e60 | 34 | # print "AUTOLOAD: constname = $constname ($AUTOLOAD)\n"; |
98b50af3 JH |
35 | die "&Time::HiRes::constant not defined" if $constname eq 'constant'; |
36 | my ($error, $val) = constant($constname); | |
ced84e60 | 37 | # print "AUTOLOAD: error = $error, val = $val\n"; |
0cf8ddea RGS |
38 | if ($error) { |
39 | my (undef,$file,$line) = caller; | |
40 | die "$error at $file line $line.\n"; | |
41 | } | |
3c72ec00 JH |
42 | { |
43 | no strict 'refs'; | |
44 | *$AUTOLOAD = sub { $val }; | |
45 | } | |
46 | goto &$AUTOLOAD; | |
47 | } | |
dcf686c9 | 48 | |
ced84e60 SP |
49 | sub import { |
50 | my $this = shift; | |
51 | for my $i (@_) { | |
170c5524 SP |
52 | if (($i eq 'clock_getres' && !&d_clock_getres) || |
53 | ($i eq 'clock_gettime' && !&d_clock_gettime) || | |
54 | ($i eq 'clock_nanosleep' && !&d_clock_nanosleep) || | |
55 | ($i eq 'clock' && !&d_clock) || | |
56 | ($i eq 'nanosleep' && !&d_nanosleep) || | |
57 | ($i eq 'usleep' && !&d_usleep) || | |
58 | ($i eq 'ualarm' && !&d_ualarm)) { | |
ced84e60 SP |
59 | require Carp; |
60 | Carp::croak("Time::HiRes::$i(): unimplemented in this platform"); | |
61 | } | |
62 | } | |
63 | Time::HiRes->export_to_level(1, $this, @_); | |
64 | } | |
65 | ||
0cf8ddea | 66 | bootstrap Time::HiRes; |
dcf686c9 JH |
67 | |
68 | # Preloaded methods go here. | |
69 | ||
70 | sub tv_interval { | |
71 | # probably could have been done in C | |
72 | my ($a, $b) = @_; | |
73 | $b = [gettimeofday()] unless defined($b); | |
74 | (${$b}[0] - ${$a}[0]) + ((${$b}[1] - ${$a}[1]) / 1_000_000); | |
75 | } | |
76 | ||
dcf686c9 JH |
77 | # Autoload methods go after =cut, and are processed by the autosplit program. |
78 | ||
79 | 1; | |
80 | __END__ | |
81 | ||
82 | =head1 NAME | |
83 | ||
f7916ddb | 84 | Time::HiRes - High resolution alarm, sleep, gettimeofday, interval timers |
dcf686c9 JH |
85 | |
86 | =head1 SYNOPSIS | |
87 | ||
ced84e60 | 88 | use Time::HiRes qw( usleep ualarm gettimeofday tv_interval nanosleep |
75d5269b SP |
89 | clock_gettime clock_getres clock_nanosleep clock |
90 | stat ); | |
dcf686c9 JH |
91 | |
92 | usleep ($microseconds); | |
44d3ce20 | 93 | nanosleep ($nanoseconds); |
dcf686c9 JH |
94 | |
95 | ualarm ($microseconds); | |
96 | ualarm ($microseconds, $interval_microseconds); | |
97 | ||
98 | $t0 = [gettimeofday]; | |
99 | ($seconds, $microseconds) = gettimeofday; | |
100 | ||
101 | $elapsed = tv_interval ( $t0, [$seconds, $microseconds]); | |
102 | $elapsed = tv_interval ( $t0, [gettimeofday]); | |
103 | $elapsed = tv_interval ( $t0 ); | |
104 | ||
105 | use Time::HiRes qw ( time alarm sleep ); | |
3c72ec00 | 106 | |
dcf686c9 JH |
107 | $now_fractions = time; |
108 | sleep ($floating_seconds); | |
109 | alarm ($floating_seconds); | |
110 | alarm ($floating_seconds, $floating_interval); | |
111 | ||
bfe77af1 | 112 | use Time::HiRes qw( setitimer getitimer ); |
3c72ec00 JH |
113 | |
114 | setitimer ($which, $floating_seconds, $floating_interval ); | |
115 | getitimer ($which); | |
116 | ||
bfe77af1 SP |
117 | use Time::HiRes qw( clock_gettime clock_getres clock_nanosleep |
118 | ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF ITIMER_REALPROF ); | |
119 | ||
82cbdcc3 SP |
120 | $realtime = clock_gettime(CLOCK_REALTIME); |
121 | $resolution = clock_getres(CLOCK_REALTIME); | |
ced84e60 | 122 | |
a8fb48f7 SP |
123 | clock_nanosleep(CLOCK_REALTIME, 1.5e9); |
124 | clock_nanosleep(CLOCK_REALTIME, time()*1e9 + 10e9, TIMER_ABSTIME); | |
170c5524 SP |
125 | |
126 | my $ticktock = clock(); | |
127 | ||
bfe77af1 SP |
128 | use Time::HiRes qw( stat ); |
129 | ||
c09e847b | 130 | my @stat = stat("file"); |
75d5269b SP |
131 | my @stat = stat(FH); |
132 | ||
dcf686c9 JH |
133 | =head1 DESCRIPTION |
134 | ||
4ed0e2d4 | 135 | The C<Time::HiRes> module implements a Perl interface to the |
44d3ce20 RGS |
136 | C<usleep>, C<nanosleep>, C<ualarm>, C<gettimeofday>, and |
137 | C<setitimer>/C<getitimer> system calls, in other words, high | |
138 | resolution time and timers. See the L</EXAMPLES> section below and the | |
139 | test scripts for usage; see your system documentation for the | |
140 | description of the underlying C<nanosleep> or C<usleep>, C<ualarm>, | |
141 | C<gettimeofday>, and C<setitimer>/C<getitimer> calls. | |
dcf686c9 | 142 | |
6937b144 | 143 | If your system lacks C<gettimeofday()> or an emulation of it you don't |
4ed0e2d4 | 144 | get C<gettimeofday()> or the one-argument form of C<tv_interval()>. |
82cbdcc3 SP |
145 | If your system lacks all of C<nanosleep()>, C<usleep()>, |
146 | C<select()>, and C<poll>, you don't get C<Time::HiRes::usleep()>, | |
147 | C<Time::HiRes::nanosleep()>, or C<Time::HiRes::sleep()>. | |
148 | If your system lacks both C<ualarm()> and C<setitimer()> you don't get | |
44d3ce20 | 149 | C<Time::HiRes::ualarm()> or C<Time::HiRes::alarm()>. |
3f2ee006 HS |
150 | |
151 | If you try to import an unimplemented function in the C<use> statement | |
152 | it will fail at compile time. | |
153 | ||
4ed0e2d4 RGS |
154 | If your subsecond sleeping is implemented with C<nanosleep()> instead |
155 | of C<usleep()>, you can mix subsecond sleeping with signals since | |
64a7a97c RGS |
156 | C<nanosleep()> does not use signals. This, however, is not portable, |
157 | and you should first check for the truth value of | |
4ed0e2d4 RGS |
158 | C<&Time::HiRes::d_nanosleep> to see whether you have nanosleep, and |
159 | then carefully read your C<nanosleep()> C API documentation for any | |
44d3ce20 | 160 | peculiarities. |
0be47ac6 | 161 | |
0cf8ddea RGS |
162 | If you are using C<nanosleep> for something else than mixing sleeping |
163 | with signals, give some thought to whether Perl is the tool you should | |
164 | be using for work requiring nanosecond accuracies. | |
dcf686c9 | 165 | |
bfe77af1 SP |
166 | Remember that unless you are working on a I<hard realtime> system, |
167 | any clocks and timers will be imprecise, especially so if you are working | |
168 | in a pre-emptive multiuser system. Understand the difference between | |
169 | I<wallclock time> and process time (in UNIX-like systems the sum of | |
170 | I<user> and I<system> times). Any attempt to sleep for X seconds will | |
171 | most probably end up sleeping B<more> than that, but don't be surpised | |
172 | if you end up sleeping slightly B<less>. | |
173 | ||
3c72ec00 JH |
174 | The following functions can be imported from this module. |
175 | No functions are exported by default. | |
dcf686c9 JH |
176 | |
177 | =over 4 | |
178 | ||
179 | =item gettimeofday () | |
180 | ||
0be47ac6 | 181 | In array context returns a two-element array with the seconds and |
f7916ddb | 182 | microseconds since the epoch. In scalar context returns floating |
6937b144 | 183 | seconds like C<Time::HiRes::time()> (see below). |
dcf686c9 JH |
184 | |
185 | =item usleep ( $useconds ) | |
186 | ||
44d3ce20 | 187 | Sleeps for the number of microseconds (millionths of a second) |
bfe77af1 SP |
188 | specified. Returns the number of microseconds actually slept. |
189 | Can sleep for more than one second, unlike the C<usleep> system call. | |
190 | Can also sleep for zero seconds, which often works like a I<thread yield>. | |
170c5524 SP |
191 | See also C<Time::HiRes::usleep()>, C<Time::HiRes::sleep()>, and |
192 | C<Time::HiRes::clock_nanosleep()>. | |
44d3ce20 RGS |
193 | |
194 | Do not expect usleep() to be exact down to one microsecond. | |
195 | ||
196 | =item nanosleep ( $nanoseconds ) | |
197 | ||
198 | Sleeps for the number of nanoseconds (1e9ths of a second) specified. | |
199 | Returns the number of nanoseconds actually slept (accurate only to | |
200 | microseconds, the nearest thousand of them). Can sleep for more than | |
bfe77af1 SP |
201 | one second. Can also sleep for zero seconds, which often works like |
202 | a I<thread yield>. See also C<Time::HiRes::sleep()>, | |
170c5524 | 203 | C<Time::HiRes::usleep()>, and C<Time::HiRes::clock_nanosleep()>. |
44d3ce20 RGS |
204 | |
205 | Do not expect nanosleep() to be exact down to one nanosecond. | |
206 | Getting even accuracy of one thousand nanoseconds is good. | |
dcf686c9 JH |
207 | |
208 | =item ualarm ( $useconds [, $interval_useconds ] ) | |
209 | ||
6937b144 MJD |
210 | Issues a C<ualarm> call; the C<$interval_useconds> is optional and |
211 | will be zero if unspecified, resulting in C<alarm>-like behaviour. | |
dcf686c9 | 212 | |
bf8300de RGS |
213 | Returns the remaining time in the alarm in microseconds, or C<undef> |
214 | if an error occurred. | |
215 | ||
bfe77af1 SP |
216 | ualarm(0) will cancel an outstanding ualarm(). |
217 | ||
993164ab | 218 | Note that the interaction between alarms and sleeps is unspecified. |
64a7a97c | 219 | |
443572f5 RB |
220 | =item tv_interval |
221 | ||
0be47ac6 | 222 | tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] ) |
dcf686c9 | 223 | |
f7916ddb | 224 | Returns the floating seconds between the two times, which should have |
6937b144 | 225 | been returned by C<gettimeofday()>. If the second argument is omitted, |
f7916ddb | 226 | then the current time is used. |
dcf686c9 JH |
227 | |
228 | =item time () | |
229 | ||
f7916ddb | 230 | Returns a floating seconds since the epoch. This function can be |
6937b144 MJD |
231 | imported, resulting in a nice drop-in replacement for the C<time> |
232 | provided with core Perl; see the L</EXAMPLES> below. | |
dcf686c9 | 233 | |
6937b144 MJD |
234 | B<NOTE 1>: This higher resolution timer can return values either less |
235 | or more than the core C<time()>, depending on whether your platform | |
236 | rounds the higher resolution timer values up, down, or to the nearest second | |
237 | to get the core C<time()>, but naturally the difference should be never | |
ced84e60 SP |
238 | more than half a second. See also L</clock_getres>, if available |
239 | in your system. | |
f7916ddb | 240 | |
6937b144 MJD |
241 | B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT, when |
242 | the C<time()> seconds since epoch rolled over to 1_000_000_000, the | |
0be47ac6 JH |
243 | default floating point format of Perl and the seconds since epoch have |
244 | conspired to produce an apparent bug: if you print the value of | |
4ed0e2d4 RGS |
245 | C<Time::HiRes::time()> you seem to be getting only five decimals, not |
246 | six as promised (microseconds). Not to worry, the microseconds are | |
64a7a97c | 247 | there (assuming your platform supports such granularity in the first |
4ed0e2d4 RGS |
248 | place). What is going on is that the default floating point format of |
249 | Perl only outputs 15 digits. In this case that means ten digits | |
250 | before the decimal separator and five after. To see the microseconds | |
251 | you can use either C<printf>/C<sprintf> with C<"%.6f">, or the | |
252 | C<gettimeofday()> function in list context, which will give you the | |
253 | seconds and microseconds as two separate values. | |
389199d8 | 254 | |
dcf686c9 JH |
255 | =item sleep ( $floating_seconds ) |
256 | ||
f7916ddb | 257 | Sleeps for the specified amount of seconds. Returns the number of |
64a7a97c RGS |
258 | seconds actually slept (a floating point value). This function can |
259 | be imported, resulting in a nice drop-in replacement for the C<sleep> | |
6937b144 | 260 | provided with perl, see the L</EXAMPLES> below. |
dcf686c9 | 261 | |
993164ab | 262 | Note that the interaction between alarms and sleeps is unspecified. |
64a7a97c | 263 | |
dcf686c9 JH |
264 | =item alarm ( $floating_seconds [, $interval_floating_seconds ] ) |
265 | ||
6937b144 | 266 | The C<SIGALRM> signal is sent after the specified number of seconds. |
bf8300de RGS |
267 | Implemented using C<setitimer()> if available, C<ualarm()> if not. |
268 | The C<$interval_floating_seconds> argument is optional and will be | |
269 | zero if unspecified, resulting in C<alarm()>-like behaviour. This | |
270 | function can be imported, resulting in a nice drop-in replacement for | |
271 | the C<alarm> provided with perl, see the L</EXAMPLES> below. | |
272 | ||
273 | Returns the remaining time in the alarm in seconds, or C<undef> | |
274 | if an error occurred. | |
dcf686c9 | 275 | |
64a7a97c RGS |
276 | B<NOTE 1>: With some combinations of operating systems and Perl |
277 | releases C<SIGALRM> restarts C<select()>, instead of interrupting it. | |
278 | This means that an C<alarm()> followed by a C<select()> may together | |
858dcda5 | 279 | take the sum of the times specified for the C<alarm()> and the |
64a7a97c RGS |
280 | C<select()>, not just the time of the C<alarm()>. |
281 | ||
993164ab | 282 | Note that the interaction between alarms and sleeps is unspecified. |
3f2ee006 | 283 | |
6937b144 | 284 | =item setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] ) |
3c72ec00 | 285 | |
bfe77af1 | 286 | Start up an interval timer: after a certain time, a signal ($which) arrives, |
64a7a97c RGS |
287 | and more signals may keep arriving at certain intervals. To disable |
288 | an "itimer", use C<$floating_seconds> of zero. If the | |
289 | C<$interval_floating_seconds> is set to zero (or unspecified), the | |
290 | timer is disabled B<after> the next delivered signal. | |
3c72ec00 | 291 | |
6937b144 MJD |
292 | Use of interval timers may interfere with C<alarm()>, C<sleep()>, |
293 | and C<usleep()>. In standard-speak the "interaction is unspecified", | |
0be47ac6 | 294 | which means that I<anything> may happen: it may work, it may not. |
3c72ec00 JH |
295 | |
296 | In scalar context, the remaining time in the timer is returned. | |
297 | ||
298 | In list context, both the remaining time and the interval are returned. | |
299 | ||
bfe77af1 | 300 | There are usually three or four interval timers (signals) available: the |
4ed0e2d4 RGS |
301 | C<$which> can be C<ITIMER_REAL>, C<ITIMER_VIRTUAL>, C<ITIMER_PROF>, or |
302 | C<ITIMER_REALPROF>. Note that which ones are available depends: true | |
e5620114 RGS |
303 | UNIX platforms usually have the first three, but only Solaris seems to |
304 | have C<ITIMER_REALPROF> (which is used to profile multithreaded programs). | |
305 | Win32 unfortunately does not haveinterval timers. | |
3c72ec00 | 306 | |
993164ab | 307 | C<ITIMER_REAL> results in C<alarm()>-like behaviour. Time is counted in |
6937b144 | 308 | I<real time>; that is, wallclock time. C<SIGALRM> is delivered when |
3c72ec00 JH |
309 | the timer expires. |
310 | ||
4ed0e2d4 RGS |
311 | C<ITIMER_VIRTUAL> counts time in (process) I<virtual time>; that is, |
312 | only when the process is running. In multiprocessor/user/CPU systems | |
313 | this may be more or less than real or wallclock time. (This time is | |
314 | also known as the I<user time>.) C<SIGVTALRM> is delivered when the | |
315 | timer expires. | |
3c72ec00 | 316 | |
6937b144 | 317 | C<ITIMER_PROF> counts time when either the process virtual time or when |
0be47ac6 JH |
318 | the operating system is running on behalf of the process (such as I/O). |
319 | (This time is also known as the I<system time>.) (The sum of user | |
6937b144 MJD |
320 | time and system time is known as the I<CPU time>.) C<SIGPROF> is |
321 | delivered when the timer expires. C<SIGPROF> can interrupt system calls. | |
3c72ec00 JH |
322 | |
323 | The semantics of interval timers for multithreaded programs are | |
324 | system-specific, and some systems may support additional interval | |
bfe77af1 SP |
325 | timers. For example, it is unspecified which thread gets the signals. |
326 | See your C<setitimer()> documentation. | |
3c72ec00 JH |
327 | |
328 | =item getitimer ( $which ) | |
329 | ||
6937b144 | 330 | Return the remaining time in the interval timer specified by C<$which>. |
3c72ec00 JH |
331 | |
332 | In scalar context, the remaining time is returned. | |
333 | ||
334 | In list context, both the remaining time and the interval are returned. | |
6937b144 | 335 | The interval is always what you put in using C<setitimer()>. |
3c72ec00 | 336 | |
ced84e60 SP |
337 | =item clock_gettime ( $which ) |
338 | ||
339 | Return as seconds the current value of the POSIX high resolution timer | |
340 | specified by C<$which>. All implementations that support POSIX high | |
341 | resolution timers are supposed to support at least the C<$which> value | |
342 | of C<CLOCK_REALTIME>, which is supposed to return results close to the | |
343 | results of C<gettimeofday>, or the number of seconds since 00:00:00:00 | |
344 | January 1, 1970 Greenwich Mean Time (GMT). Do not assume that | |
345 | CLOCK_REALTIME is zero, it might be one, or something else. | |
346 | Another potentially useful (but not available everywhere) value is | |
347 | C<CLOCK_MONOTONIC>, which guarantees a monotonically increasing time | |
e5620114 RGS |
348 | value (unlike time() or gettimeofday(), which can be adjusted). |
349 | See your system documentation for other possibly supported values. | |
ced84e60 SP |
350 | |
351 | =item clock_getres ( $which ) | |
352 | ||
353 | Return as seconds the resolution of the POSIX high resolution timer | |
354 | specified by C<$which>. All implementations that support POSIX high | |
355 | resolution timers are supposed to support at least the C<$which> value | |
170c5524 SP |
356 | of C<CLOCK_REALTIME>, see L</clock_gettime>. |
357 | ||
a8fb48f7 | 358 | =item clock_nanosleep ( $which, $nanoseconds, $flags = 0) |
170c5524 | 359 | |
a8fb48f7 SP |
360 | Sleeps for the number of nanoseconds (1e9ths of a second) specified. |
361 | Returns the number of nanoseconds actually slept. The $which is the | |
170c5524 SP |
362 | "clock id", as with clock_gettime() and clock_getres(). The flags |
363 | default to zero but C<TIMER_ABSTIME> can specified (must be exported | |
364 | explicitly) which means that C<$nanoseconds> is not a time interval | |
365 | (as is the default) but instead an absolute time. Can sleep for more | |
366 | than one second. Can also sleep for zero seconds, which often works | |
367 | like a I<thread yield>. See also C<Time::HiRes::sleep()>, | |
368 | C<Time::HiRes::usleep()>, and C<Time::HiRes::nanosleep()>. | |
369 | ||
370 | Do not expect clock_nanosleep() to be exact down to one nanosecond. | |
371 | Getting even accuracy of one thousand nanoseconds is good. | |
372 | ||
373 | =item clock() | |
374 | ||
375 | Return as seconds the I<process time> (user + system time) spent by | |
376 | the process since the first call to clock() (the definition is B<not> | |
377 | "since the start of the process", though if you are lucky these times | |
378 | may be quite close to each other, depending on the system). What this | |
379 | means is that you probably need to store the result of your first call | |
380 | to clock(), and subtract that value from the following results of clock(). | |
381 | ||
382 | The time returned also includes the process times of the terminated | |
383 | child processes for which wait() has been executed. This value is | |
384 | somewhat like the second value returned by the times() of core Perl, | |
385 | but not necessarily identical. Note that due to backward | |
ff7df920 SP |
386 | compatibility limitations the returned value may wrap around at about |
387 | 2147 seconds or at about 36 minutes. | |
ced84e60 | 388 | |
75d5269b SP |
389 | =item stat |
390 | ||
391 | =item stat FH | |
392 | ||
393 | =item stat EXPR | |
394 | ||
395 | As L<perlfunc/stat> but with the access/modify/change file timestamps | |
396 | in subsecond resolution, if the operating system and the filesystem | |
397 | both support such timestamps. To override the standard stat(): | |
398 | ||
399 | use Time::HiRes qw(stat); | |
400 | ||
401 | Test for the value of &Time::HiRes::d_hires_stat to find out whether | |
402 | the operating system supports subsecond file timestamps: a value | |
403 | larger than zero means yes. There are unfortunately no easy | |
404 | ways to find out whether the filesystem supports such timestamps. | |
c09e847b SP |
405 | UNIX filesystems often do; NTFS does; FAT doesn't (FAT timestamp |
406 | granularity is B<two> seconds). | |
75d5269b SP |
407 | |
408 | A zero return value of &Time::HiRes::d_hires_stat means that | |
409 | Time::HiRes::stat is a no-op passthrough for CORE::stat(), | |
410 | and therefore the timestamps will stay integers. The same | |
bfe77af1 | 411 | thing will happen if the filesystem does not do subsecond timestamps, |
c09e847b | 412 | even if the &Time::HiRes::d_hires_stat is non-zero. |
75d5269b SP |
413 | |
414 | In any case do not expect nanosecond resolution, or even a microsecond | |
bfe77af1 SP |
415 | resolution. Also note that the modify/access timestamps might have |
416 | different resolutions, and that they need not be synchronized, e.g. | |
417 | if the operations are | |
418 | ||
419 | write | |
420 | stat # t1 | |
421 | read | |
422 | stat # t2 | |
423 | ||
424 | the access time stamp from t2 need not be greater-than the modify | |
425 | time stamp from t1: it may be equal or I<less>. | |
75d5269b | 426 | |
dcf686c9 JH |
427 | =back |
428 | ||
429 | =head1 EXAMPLES | |
430 | ||
431 | use Time::HiRes qw(usleep ualarm gettimeofday tv_interval); | |
432 | ||
433 | $microseconds = 750_000; | |
70cf0185 | 434 | usleep($microseconds); |
dcf686c9 JH |
435 | |
436 | # signal alarm in 2.5s & every .1s thereafter | |
70cf0185 | 437 | ualarm(2_500_000, 100_000); |
bfe77af1 SP |
438 | # cancel that ualarm |
439 | ualarm(0); | |
dcf686c9 JH |
440 | |
441 | # get seconds and microseconds since the epoch | |
70cf0185 | 442 | ($s, $usec) = gettimeofday(); |
dcf686c9 JH |
443 | |
444 | # measure elapsed time | |
445 | # (could also do by subtracting 2 gettimeofday return values) | |
446 | $t0 = [gettimeofday]; | |
447 | # do bunch of stuff here | |
448 | $t1 = [gettimeofday]; | |
449 | # do more stuff here | |
450 | $t0_t1 = tv_interval $t0, $t1; | |
0be47ac6 | 451 | |
dcf686c9 JH |
452 | $elapsed = tv_interval ($t0, [gettimeofday]); |
453 | $elapsed = tv_interval ($t0); # equivalent code | |
454 | ||
455 | # | |
456 | # replacements for time, alarm and sleep that know about | |
457 | # floating seconds | |
458 | # | |
459 | use Time::HiRes; | |
460 | $now_fractions = Time::HiRes::time; | |
461 | Time::HiRes::sleep (2.5); | |
462 | Time::HiRes::alarm (10.6666666); | |
0be47ac6 | 463 | |
dcf686c9 JH |
464 | use Time::HiRes qw ( time alarm sleep ); |
465 | $now_fractions = time; | |
466 | sleep (2.5); | |
467 | alarm (10.6666666); | |
468 | ||
3c72ec00 JH |
469 | # Arm an interval timer to go off first at 10 seconds and |
470 | # after that every 2.5 seconds, in process virtual time | |
471 | ||
472 | use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time ); | |
473 | ||
36d6c396 | 474 | $SIG{VTALRM} = sub { print time, "\n" }; |
3c72ec00 JH |
475 | setitimer(ITIMER_VIRTUAL, 10, 2.5); |
476 | ||
1a7d3a53 SP |
477 | use Time::HiRes qw( clock_gettime clock_getres CLOCK_REALTIME ); |
478 | # Read the POSIX high resolution timer. | |
479 | my $high = clock_getres(CLOCK_REALTIME); | |
480 | # But how accurate we can be, really? | |
481 | my $reso = clock_getres(CLOCK_REALTIME); | |
ced84e60 | 482 | |
170c5524 SP |
483 | use Time::HiRes qw( clock_nanosleep TIMER_ABSTIME ); |
484 | clock_nanosleep(CLOCK_REALTIME, 1e6); | |
485 | clock_nanosleep(CLOCK_REALTIME, 2e9, TIMER_ABSTIME); | |
486 | ||
487 | use Time::HiRes qw( clock ); | |
488 | my $clock0 = clock(); | |
489 | ... # Do something. | |
490 | my $clock1 = clock(); | |
491 | my $clockd = $clock1 - $clock0; | |
492 | ||
c09e847b SP |
493 | use Time::HiRes qw( stat ); |
494 | my ($atime, $mtime, $ctime) = (stat("istics"))[8, 9, 10]; | |
495 | ||
dcf686c9 JH |
496 | =head1 C API |
497 | ||
498 | In addition to the perl API described above, a C API is available for | |
499 | extension writers. The following C functions are available in the | |
500 | modglobal hash: | |
501 | ||
502 | name C prototype | |
503 | --------------- ---------------------- | |
504 | Time::NVtime double (*)() | |
06252d99 | 505 | Time::U2time void (*)(pTHX_ UV ret[2]) |
dcf686c9 | 506 | |
6937b144 MJD |
507 | Both functions return equivalent information (like C<gettimeofday>) |
508 | but with different representations. The names C<NVtime> and C<U2time> | |
dcf686c9 | 509 | were selected mainly because they are operating system independent. |
56c1b3bd RGS |
510 | (C<gettimeofday> is Unix-centric, though some platforms like Win32 and |
511 | VMS have emulations for it.) | |
dcf686c9 | 512 | |
6937b144 | 513 | Here is an example of using C<NVtime> from C: |
dcf686c9 | 514 | |
993164ab | 515 | double (*myNVtime)(); /* Returns -1 on failure. */ |
dcf686c9 JH |
516 | SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0); |
517 | if (!svp) croak("Time::HiRes is required"); | |
518 | if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer"); | |
356234a5 | 519 | myNVtime = INT2PTR(double(*)(), SvIV(*svp)); |
dcf686c9 JH |
520 | printf("The current time is: %f\n", (*myNVtime)()); |
521 | ||
db0b859f JH |
522 | =head1 DIAGNOSTICS |
523 | ||
34f69483 SP |
524 | =head2 useconds or interval more than ... |
525 | ||
526 | In ualarm() you tried to use number of microseconds or interval (also | |
527 | in microseconds) more than 1_000_000 and setitimer() is not available | |
528 | in your system to emulate that case. | |
529 | ||
db0b859f JH |
530 | =head2 negative time not invented yet |
531 | ||
532 | You tried to use a negative time argument. | |
533 | ||
534 | =head2 internal error: useconds < 0 (unsigned ... signed ...) | |
535 | ||
536 | Something went horribly wrong-- the number of microseconds that cannot | |
537 | become negative just became negative. Maybe your compiler is broken? | |
538 | ||
bf8300de RGS |
539 | =head2 useconds or uinterval equal to or more than 1000000 |
540 | ||
541 | In some platforms it is not possible to get an alarm with subsecond | |
542 | resolution and later than one second. | |
543 | ||
544 | =head2 unimplemented in this platform | |
545 | ||
546 | Some calls simply aren't available, real or emulated, on every platform. | |
547 | ||
f03b998d JH |
548 | =head1 CAVEATS |
549 | ||
6937b144 | 550 | Notice that the core C<time()> maybe rounding rather than truncating. |
d8cb5b61 RGS |
551 | What this means is that the core C<time()> may be reporting the time |
552 | as one second later than C<gettimeofday()> and C<Time::HiRes::time()>. | |
553 | ||
554 | Adjusting the system clock (either manually or by services like ntp) | |
555 | may cause problems, especially for long running programs that assume | |
556 | a monotonously increasing time (note that all platforms do not adjust | |
557 | time as gracefully as UNIX ntp does). For example in Win32 (and derived | |
558 | platforms like Cygwin and MinGW) the Time::HiRes::time() may temporarily | |
559 | drift off from the system clock (and the original time()) by up to 0.5 | |
560 | seconds. Time::HiRes will notice this eventually and recalibrate. | |
ced84e60 | 561 | Note that since Time::HiRes 1.77 the clock_gettime(CLOCK_MONOTONIC) |
1a7d3a53 | 562 | might help in this (in case your system supports CLOCK_MONOTONIC). |
f03b998d | 563 | |
e5620114 RGS |
564 | Some systems have APIs but not implementations: for example QNX and Haiku |
565 | have the interval timer APIs but not the functionality. | |
566 | ||
26e22fd9 RGS |
567 | =head1 SEE ALSO |
568 | ||
ced84e60 SP |
569 | Perl modules L<BSD::Resource>, L<Time::TAI64>. |
570 | ||
bfe77af1 SP |
571 | Your system documentation for C<clock>, C<clock_gettime>, |
572 | C<clock_getres>, C<clock_nanosleep>, C<clock_settime>, C<getitimer>, | |
573 | C<gettimeofday>, C<setitimer>, C<sleep>, C<stat>, C<ualarm>. | |
26e22fd9 | 574 | |
dcf686c9 JH |
575 | =head1 AUTHORS |
576 | ||
577 | D. Wegscheid <wegscd@whirlpool.com> | |
578 | R. Schertler <roderick@argon.org> | |
579 | J. Hietaniemi <jhi@iki.fi> | |
580 | G. Aas <gisle@aas.no> | |
581 | ||
3f2ee006 | 582 | =head1 COPYRIGHT AND LICENSE |
dcf686c9 | 583 | |
3f2ee006 | 584 | Copyright (c) 1996-2002 Douglas E. Wegscheid. All rights reserved. |
dcf686c9 | 585 | |
bf8300de RGS |
586 | Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 Jarkko Hietaniemi. |
587 | All rights reserved. | |
dcf686c9 | 588 | |
858dcda5 | 589 | Copyright (C) 2011, 2012 Andrew Main (Zefram) <zefram@fysh.org> |
91a2e9f6 | 590 | |
3f2ee006 HS |
591 | This program is free software; you can redistribute it and/or modify |
592 | it under the same terms as Perl itself. | |
dcf686c9 JH |
593 | |
594 | =cut |