Commit | Line | Data |
---|---|---|
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 | 22 | d_clock d_clock_nanosleep |
0f0eae2c | 23 | stat lstat |
75d5269b | 24 | ); |
bf8300de | 25 | |
4451fd4e | 26 | our $VERSION = '1.9728'; |
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 | 89 | clock_gettime clock_getres clock_nanosleep clock |
0f0eae2c | 90 | stat lstat ); |
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 | ||
0f0eae2c | 128 | use Time::HiRes qw( stat lstat ); |
bfe77af1 | 129 | |
c09e847b | 130 | my @stat = stat("file"); |
75d5269b | 131 | my @stat = stat(FH); |
0f0eae2c | 132 | my @stat = lstat("file"); |
75d5269b | 133 | |
dcf686c9 JH |
134 | =head1 DESCRIPTION |
135 | ||
4ed0e2d4 | 136 | The C<Time::HiRes> module implements a Perl interface to the |
44d3ce20 RGS |
137 | C<usleep>, C<nanosleep>, C<ualarm>, C<gettimeofday>, and |
138 | C<setitimer>/C<getitimer> system calls, in other words, high | |
139 | resolution time and timers. See the L</EXAMPLES> section below and the | |
140 | test scripts for usage; see your system documentation for the | |
141 | description of the underlying C<nanosleep> or C<usleep>, C<ualarm>, | |
142 | C<gettimeofday>, and C<setitimer>/C<getitimer> calls. | |
dcf686c9 | 143 | |
6937b144 | 144 | If your system lacks C<gettimeofday()> or an emulation of it you don't |
4ed0e2d4 | 145 | get C<gettimeofday()> or the one-argument form of C<tv_interval()>. |
82cbdcc3 SP |
146 | If your system lacks all of C<nanosleep()>, C<usleep()>, |
147 | C<select()>, and C<poll>, you don't get C<Time::HiRes::usleep()>, | |
148 | C<Time::HiRes::nanosleep()>, or C<Time::HiRes::sleep()>. | |
149 | If your system lacks both C<ualarm()> and C<setitimer()> you don't get | |
44d3ce20 | 150 | C<Time::HiRes::ualarm()> or C<Time::HiRes::alarm()>. |
3f2ee006 HS |
151 | |
152 | If you try to import an unimplemented function in the C<use> statement | |
153 | it will fail at compile time. | |
154 | ||
4ed0e2d4 RGS |
155 | If your subsecond sleeping is implemented with C<nanosleep()> instead |
156 | of C<usleep()>, you can mix subsecond sleeping with signals since | |
64a7a97c RGS |
157 | C<nanosleep()> does not use signals. This, however, is not portable, |
158 | and you should first check for the truth value of | |
4ed0e2d4 RGS |
159 | C<&Time::HiRes::d_nanosleep> to see whether you have nanosleep, and |
160 | then carefully read your C<nanosleep()> C API documentation for any | |
44d3ce20 | 161 | peculiarities. |
0be47ac6 | 162 | |
0cf8ddea RGS |
163 | If you are using C<nanosleep> for something else than mixing sleeping |
164 | with signals, give some thought to whether Perl is the tool you should | |
165 | be using for work requiring nanosecond accuracies. | |
dcf686c9 | 166 | |
bfe77af1 SP |
167 | Remember that unless you are working on a I<hard realtime> system, |
168 | any clocks and timers will be imprecise, especially so if you are working | |
169 | in a pre-emptive multiuser system. Understand the difference between | |
170 | I<wallclock time> and process time (in UNIX-like systems the sum of | |
171 | I<user> and I<system> times). Any attempt to sleep for X seconds will | |
0f0eae2c | 172 | most probably end up sleeping B<more> than that, but don't be surprised |
bfe77af1 SP |
173 | if you end up sleeping slightly B<less>. |
174 | ||
3c72ec00 JH |
175 | The following functions can be imported from this module. |
176 | No functions are exported by default. | |
dcf686c9 JH |
177 | |
178 | =over 4 | |
179 | ||
180 | =item gettimeofday () | |
181 | ||
0be47ac6 | 182 | In array context returns a two-element array with the seconds and |
f7916ddb | 183 | microseconds since the epoch. In scalar context returns floating |
6937b144 | 184 | seconds like C<Time::HiRes::time()> (see below). |
dcf686c9 JH |
185 | |
186 | =item usleep ( $useconds ) | |
187 | ||
44d3ce20 | 188 | Sleeps for the number of microseconds (millionths of a second) |
bfe77af1 SP |
189 | specified. Returns the number of microseconds actually slept. |
190 | Can sleep for more than one second, unlike the C<usleep> system call. | |
191 | Can also sleep for zero seconds, which often works like a I<thread yield>. | |
170c5524 SP |
192 | See also C<Time::HiRes::usleep()>, C<Time::HiRes::sleep()>, and |
193 | C<Time::HiRes::clock_nanosleep()>. | |
44d3ce20 RGS |
194 | |
195 | Do not expect usleep() to be exact down to one microsecond. | |
196 | ||
197 | =item nanosleep ( $nanoseconds ) | |
198 | ||
199 | Sleeps for the number of nanoseconds (1e9ths of a second) specified. | |
200 | Returns the number of nanoseconds actually slept (accurate only to | |
201 | microseconds, the nearest thousand of them). Can sleep for more than | |
bfe77af1 SP |
202 | one second. Can also sleep for zero seconds, which often works like |
203 | a I<thread yield>. See also C<Time::HiRes::sleep()>, | |
170c5524 | 204 | C<Time::HiRes::usleep()>, and C<Time::HiRes::clock_nanosleep()>. |
44d3ce20 RGS |
205 | |
206 | Do not expect nanosleep() to be exact down to one nanosecond. | |
207 | Getting even accuracy of one thousand nanoseconds is good. | |
dcf686c9 JH |
208 | |
209 | =item ualarm ( $useconds [, $interval_useconds ] ) | |
210 | ||
6937b144 MJD |
211 | Issues a C<ualarm> call; the C<$interval_useconds> is optional and |
212 | will be zero if unspecified, resulting in C<alarm>-like behaviour. | |
dcf686c9 | 213 | |
bf8300de RGS |
214 | Returns the remaining time in the alarm in microseconds, or C<undef> |
215 | if an error occurred. | |
216 | ||
bfe77af1 SP |
217 | ualarm(0) will cancel an outstanding ualarm(). |
218 | ||
993164ab | 219 | Note that the interaction between alarms and sleeps is unspecified. |
64a7a97c | 220 | |
443572f5 RB |
221 | =item tv_interval |
222 | ||
0be47ac6 | 223 | tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] ) |
dcf686c9 | 224 | |
f7916ddb | 225 | Returns the floating seconds between the two times, which should have |
6937b144 | 226 | been returned by C<gettimeofday()>. If the second argument is omitted, |
f7916ddb | 227 | then the current time is used. |
dcf686c9 JH |
228 | |
229 | =item time () | |
230 | ||
f7916ddb | 231 | Returns a floating seconds since the epoch. This function can be |
6937b144 MJD |
232 | imported, resulting in a nice drop-in replacement for the C<time> |
233 | provided with core Perl; see the L</EXAMPLES> below. | |
dcf686c9 | 234 | |
6937b144 MJD |
235 | B<NOTE 1>: This higher resolution timer can return values either less |
236 | or more than the core C<time()>, depending on whether your platform | |
237 | rounds the higher resolution timer values up, down, or to the nearest second | |
238 | to get the core C<time()>, but naturally the difference should be never | |
ced84e60 SP |
239 | more than half a second. See also L</clock_getres>, if available |
240 | in your system. | |
f7916ddb | 241 | |
6937b144 MJD |
242 | B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT, when |
243 | the C<time()> seconds since epoch rolled over to 1_000_000_000, the | |
0be47ac6 JH |
244 | default floating point format of Perl and the seconds since epoch have |
245 | conspired to produce an apparent bug: if you print the value of | |
4ed0e2d4 RGS |
246 | C<Time::HiRes::time()> you seem to be getting only five decimals, not |
247 | six as promised (microseconds). Not to worry, the microseconds are | |
64a7a97c | 248 | there (assuming your platform supports such granularity in the first |
4ed0e2d4 RGS |
249 | place). What is going on is that the default floating point format of |
250 | Perl only outputs 15 digits. In this case that means ten digits | |
251 | before the decimal separator and five after. To see the microseconds | |
252 | you can use either C<printf>/C<sprintf> with C<"%.6f">, or the | |
253 | C<gettimeofday()> function in list context, which will give you the | |
254 | seconds and microseconds as two separate values. | |
389199d8 | 255 | |
dcf686c9 JH |
256 | =item sleep ( $floating_seconds ) |
257 | ||
f7916ddb | 258 | Sleeps for the specified amount of seconds. Returns the number of |
64a7a97c RGS |
259 | seconds actually slept (a floating point value). This function can |
260 | be imported, resulting in a nice drop-in replacement for the C<sleep> | |
6937b144 | 261 | provided with perl, see the L</EXAMPLES> below. |
dcf686c9 | 262 | |
993164ab | 263 | Note that the interaction between alarms and sleeps is unspecified. |
64a7a97c | 264 | |
dcf686c9 JH |
265 | =item alarm ( $floating_seconds [, $interval_floating_seconds ] ) |
266 | ||
6937b144 | 267 | The C<SIGALRM> signal is sent after the specified number of seconds. |
bf8300de RGS |
268 | Implemented using C<setitimer()> if available, C<ualarm()> if not. |
269 | The C<$interval_floating_seconds> argument is optional and will be | |
270 | zero if unspecified, resulting in C<alarm()>-like behaviour. This | |
271 | function can be imported, resulting in a nice drop-in replacement for | |
272 | the C<alarm> provided with perl, see the L</EXAMPLES> below. | |
273 | ||
274 | Returns the remaining time in the alarm in seconds, or C<undef> | |
275 | if an error occurred. | |
dcf686c9 | 276 | |
64a7a97c RGS |
277 | B<NOTE 1>: With some combinations of operating systems and Perl |
278 | releases C<SIGALRM> restarts C<select()>, instead of interrupting it. | |
279 | This means that an C<alarm()> followed by a C<select()> may together | |
858dcda5 | 280 | take the sum of the times specified for the C<alarm()> and the |
64a7a97c RGS |
281 | C<select()>, not just the time of the C<alarm()>. |
282 | ||
993164ab | 283 | Note that the interaction between alarms and sleeps is unspecified. |
3f2ee006 | 284 | |
6937b144 | 285 | =item setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] ) |
3c72ec00 | 286 | |
bfe77af1 | 287 | Start up an interval timer: after a certain time, a signal ($which) arrives, |
64a7a97c RGS |
288 | and more signals may keep arriving at certain intervals. To disable |
289 | an "itimer", use C<$floating_seconds> of zero. If the | |
290 | C<$interval_floating_seconds> is set to zero (or unspecified), the | |
291 | timer is disabled B<after> the next delivered signal. | |
3c72ec00 | 292 | |
6937b144 MJD |
293 | Use of interval timers may interfere with C<alarm()>, C<sleep()>, |
294 | and C<usleep()>. In standard-speak the "interaction is unspecified", | |
0be47ac6 | 295 | which means that I<anything> may happen: it may work, it may not. |
3c72ec00 JH |
296 | |
297 | In scalar context, the remaining time in the timer is returned. | |
298 | ||
299 | In list context, both the remaining time and the interval are returned. | |
300 | ||
bfe77af1 | 301 | There are usually three or four interval timers (signals) available: the |
4ed0e2d4 RGS |
302 | C<$which> can be C<ITIMER_REAL>, C<ITIMER_VIRTUAL>, C<ITIMER_PROF>, or |
303 | C<ITIMER_REALPROF>. Note that which ones are available depends: true | |
e5620114 RGS |
304 | UNIX platforms usually have the first three, but only Solaris seems to |
305 | have C<ITIMER_REALPROF> (which is used to profile multithreaded programs). | |
0f0eae2c | 306 | Win32 unfortunately does not have interval timers. |
3c72ec00 | 307 | |
993164ab | 308 | C<ITIMER_REAL> results in C<alarm()>-like behaviour. Time is counted in |
6937b144 | 309 | I<real time>; that is, wallclock time. C<SIGALRM> is delivered when |
3c72ec00 JH |
310 | the timer expires. |
311 | ||
4ed0e2d4 RGS |
312 | C<ITIMER_VIRTUAL> counts time in (process) I<virtual time>; that is, |
313 | only when the process is running. In multiprocessor/user/CPU systems | |
314 | this may be more or less than real or wallclock time. (This time is | |
315 | also known as the I<user time>.) C<SIGVTALRM> is delivered when the | |
316 | timer expires. | |
3c72ec00 | 317 | |
6937b144 | 318 | C<ITIMER_PROF> counts time when either the process virtual time or when |
0be47ac6 JH |
319 | the operating system is running on behalf of the process (such as I/O). |
320 | (This time is also known as the I<system time>.) (The sum of user | |
6937b144 MJD |
321 | time and system time is known as the I<CPU time>.) C<SIGPROF> is |
322 | delivered when the timer expires. C<SIGPROF> can interrupt system calls. | |
3c72ec00 JH |
323 | |
324 | The semantics of interval timers for multithreaded programs are | |
325 | system-specific, and some systems may support additional interval | |
bfe77af1 SP |
326 | timers. For example, it is unspecified which thread gets the signals. |
327 | See your C<setitimer()> documentation. | |
3c72ec00 JH |
328 | |
329 | =item getitimer ( $which ) | |
330 | ||
6937b144 | 331 | Return the remaining time in the interval timer specified by C<$which>. |
3c72ec00 JH |
332 | |
333 | In scalar context, the remaining time is returned. | |
334 | ||
335 | In list context, both the remaining time and the interval are returned. | |
6937b144 | 336 | The interval is always what you put in using C<setitimer()>. |
3c72ec00 | 337 | |
ced84e60 SP |
338 | =item clock_gettime ( $which ) |
339 | ||
340 | Return as seconds the current value of the POSIX high resolution timer | |
341 | specified by C<$which>. All implementations that support POSIX high | |
342 | resolution timers are supposed to support at least the C<$which> value | |
343 | of C<CLOCK_REALTIME>, which is supposed to return results close to the | |
344 | results of C<gettimeofday>, or the number of seconds since 00:00:00:00 | |
345 | January 1, 1970 Greenwich Mean Time (GMT). Do not assume that | |
346 | CLOCK_REALTIME is zero, it might be one, or something else. | |
347 | Another potentially useful (but not available everywhere) value is | |
348 | C<CLOCK_MONOTONIC>, which guarantees a monotonically increasing time | |
e5620114 RGS |
349 | value (unlike time() or gettimeofday(), which can be adjusted). |
350 | See your system documentation for other possibly supported values. | |
ced84e60 SP |
351 | |
352 | =item clock_getres ( $which ) | |
353 | ||
354 | Return as seconds the resolution of the POSIX high resolution timer | |
355 | specified by C<$which>. All implementations that support POSIX high | |
356 | resolution timers are supposed to support at least the C<$which> value | |
170c5524 SP |
357 | of C<CLOCK_REALTIME>, see L</clock_gettime>. |
358 | ||
a8fb48f7 | 359 | =item clock_nanosleep ( $which, $nanoseconds, $flags = 0) |
170c5524 | 360 | |
a8fb48f7 SP |
361 | Sleeps for the number of nanoseconds (1e9ths of a second) specified. |
362 | Returns the number of nanoseconds actually slept. The $which is the | |
170c5524 SP |
363 | "clock id", as with clock_gettime() and clock_getres(). The flags |
364 | default to zero but C<TIMER_ABSTIME> can specified (must be exported | |
365 | explicitly) which means that C<$nanoseconds> is not a time interval | |
366 | (as is the default) but instead an absolute time. Can sleep for more | |
367 | than one second. Can also sleep for zero seconds, which often works | |
368 | like a I<thread yield>. See also C<Time::HiRes::sleep()>, | |
369 | C<Time::HiRes::usleep()>, and C<Time::HiRes::nanosleep()>. | |
370 | ||
371 | Do not expect clock_nanosleep() to be exact down to one nanosecond. | |
372 | Getting even accuracy of one thousand nanoseconds is good. | |
373 | ||
374 | =item clock() | |
375 | ||
376 | Return as seconds the I<process time> (user + system time) spent by | |
377 | the process since the first call to clock() (the definition is B<not> | |
378 | "since the start of the process", though if you are lucky these times | |
379 | may be quite close to each other, depending on the system). What this | |
380 | means is that you probably need to store the result of your first call | |
381 | to clock(), and subtract that value from the following results of clock(). | |
382 | ||
383 | The time returned also includes the process times of the terminated | |
384 | child processes for which wait() has been executed. This value is | |
385 | somewhat like the second value returned by the times() of core Perl, | |
386 | but not necessarily identical. Note that due to backward | |
ff7df920 SP |
387 | compatibility limitations the returned value may wrap around at about |
388 | 2147 seconds or at about 36 minutes. | |
ced84e60 | 389 | |
75d5269b SP |
390 | =item stat |
391 | ||
392 | =item stat FH | |
393 | ||
394 | =item stat EXPR | |
395 | ||
0f0eae2c Z |
396 | =item lstat |
397 | ||
398 | =item lstat FH | |
399 | ||
400 | =item lstat EXPR | |
401 | ||
402 | As L<perlfunc/stat> or L<perlfunc/lstat> | |
403 | but with the access/modify/change file timestamps | |
75d5269b SP |
404 | in subsecond resolution, if the operating system and the filesystem |
405 | both support such timestamps. To override the standard stat(): | |
406 | ||
407 | use Time::HiRes qw(stat); | |
408 | ||
409 | Test for the value of &Time::HiRes::d_hires_stat to find out whether | |
410 | the operating system supports subsecond file timestamps: a value | |
411 | larger than zero means yes. There are unfortunately no easy | |
412 | ways to find out whether the filesystem supports such timestamps. | |
c09e847b SP |
413 | UNIX filesystems often do; NTFS does; FAT doesn't (FAT timestamp |
414 | granularity is B<two> seconds). | |
75d5269b SP |
415 | |
416 | A zero return value of &Time::HiRes::d_hires_stat means that | |
0f0eae2c Z |
417 | Time::HiRes::stat is a no-op passthrough for CORE::stat() |
418 | (and likewise for lstat), | |
75d5269b | 419 | and therefore the timestamps will stay integers. The same |
bfe77af1 | 420 | thing will happen if the filesystem does not do subsecond timestamps, |
c09e847b | 421 | even if the &Time::HiRes::d_hires_stat is non-zero. |
75d5269b SP |
422 | |
423 | In any case do not expect nanosecond resolution, or even a microsecond | |
bfe77af1 SP |
424 | resolution. Also note that the modify/access timestamps might have |
425 | different resolutions, and that they need not be synchronized, e.g. | |
426 | if the operations are | |
427 | ||
428 | write | |
429 | stat # t1 | |
430 | read | |
431 | stat # t2 | |
432 | ||
433 | the access time stamp from t2 need not be greater-than the modify | |
434 | time stamp from t1: it may be equal or I<less>. | |
75d5269b | 435 | |
dcf686c9 JH |
436 | =back |
437 | ||
438 | =head1 EXAMPLES | |
439 | ||
440 | use Time::HiRes qw(usleep ualarm gettimeofday tv_interval); | |
441 | ||
442 | $microseconds = 750_000; | |
70cf0185 | 443 | usleep($microseconds); |
dcf686c9 JH |
444 | |
445 | # signal alarm in 2.5s & every .1s thereafter | |
70cf0185 | 446 | ualarm(2_500_000, 100_000); |
bfe77af1 SP |
447 | # cancel that ualarm |
448 | ualarm(0); | |
dcf686c9 JH |
449 | |
450 | # get seconds and microseconds since the epoch | |
70cf0185 | 451 | ($s, $usec) = gettimeofday(); |
dcf686c9 JH |
452 | |
453 | # measure elapsed time | |
454 | # (could also do by subtracting 2 gettimeofday return values) | |
455 | $t0 = [gettimeofday]; | |
456 | # do bunch of stuff here | |
457 | $t1 = [gettimeofday]; | |
458 | # do more stuff here | |
459 | $t0_t1 = tv_interval $t0, $t1; | |
0be47ac6 | 460 | |
dcf686c9 JH |
461 | $elapsed = tv_interval ($t0, [gettimeofday]); |
462 | $elapsed = tv_interval ($t0); # equivalent code | |
463 | ||
464 | # | |
465 | # replacements for time, alarm and sleep that know about | |
466 | # floating seconds | |
467 | # | |
468 | use Time::HiRes; | |
469 | $now_fractions = Time::HiRes::time; | |
470 | Time::HiRes::sleep (2.5); | |
471 | Time::HiRes::alarm (10.6666666); | |
0be47ac6 | 472 | |
dcf686c9 JH |
473 | use Time::HiRes qw ( time alarm sleep ); |
474 | $now_fractions = time; | |
475 | sleep (2.5); | |
476 | alarm (10.6666666); | |
477 | ||
3c72ec00 JH |
478 | # Arm an interval timer to go off first at 10 seconds and |
479 | # after that every 2.5 seconds, in process virtual time | |
480 | ||
481 | use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time ); | |
482 | ||
36d6c396 | 483 | $SIG{VTALRM} = sub { print time, "\n" }; |
3c72ec00 JH |
484 | setitimer(ITIMER_VIRTUAL, 10, 2.5); |
485 | ||
1a7d3a53 SP |
486 | use Time::HiRes qw( clock_gettime clock_getres CLOCK_REALTIME ); |
487 | # Read the POSIX high resolution timer. | |
0f0eae2c | 488 | my $high = clock_gettime(CLOCK_REALTIME); |
1a7d3a53 SP |
489 | # But how accurate we can be, really? |
490 | my $reso = clock_getres(CLOCK_REALTIME); | |
ced84e60 | 491 | |
170c5524 SP |
492 | use Time::HiRes qw( clock_nanosleep TIMER_ABSTIME ); |
493 | clock_nanosleep(CLOCK_REALTIME, 1e6); | |
494 | clock_nanosleep(CLOCK_REALTIME, 2e9, TIMER_ABSTIME); | |
495 | ||
496 | use Time::HiRes qw( clock ); | |
497 | my $clock0 = clock(); | |
498 | ... # Do something. | |
499 | my $clock1 = clock(); | |
500 | my $clockd = $clock1 - $clock0; | |
501 | ||
c09e847b SP |
502 | use Time::HiRes qw( stat ); |
503 | my ($atime, $mtime, $ctime) = (stat("istics"))[8, 9, 10]; | |
504 | ||
dcf686c9 JH |
505 | =head1 C API |
506 | ||
507 | In addition to the perl API described above, a C API is available for | |
508 | extension writers. The following C functions are available in the | |
509 | modglobal hash: | |
510 | ||
511 | name C prototype | |
512 | --------------- ---------------------- | |
120b53f9 | 513 | Time::NVtime NV (*)() |
06252d99 | 514 | Time::U2time void (*)(pTHX_ UV ret[2]) |
dcf686c9 | 515 | |
6937b144 MJD |
516 | Both functions return equivalent information (like C<gettimeofday>) |
517 | but with different representations. The names C<NVtime> and C<U2time> | |
dcf686c9 | 518 | were selected mainly because they are operating system independent. |
56c1b3bd RGS |
519 | (C<gettimeofday> is Unix-centric, though some platforms like Win32 and |
520 | VMS have emulations for it.) | |
dcf686c9 | 521 | |
6937b144 | 522 | Here is an example of using C<NVtime> from C: |
dcf686c9 | 523 | |
120b53f9 | 524 | NV (*myNVtime)(); /* Returns -1 on failure. */ |
dcf686c9 JH |
525 | SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0); |
526 | if (!svp) croak("Time::HiRes is required"); | |
527 | if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer"); | |
120b53f9 RS |
528 | myNVtime = INT2PTR(NV(*)(), SvIV(*svp)); |
529 | printf("The current time is: %" NVff "\n", (*myNVtime)()); | |
dcf686c9 | 530 | |
db0b859f JH |
531 | =head1 DIAGNOSTICS |
532 | ||
34f69483 SP |
533 | =head2 useconds or interval more than ... |
534 | ||
535 | In ualarm() you tried to use number of microseconds or interval (also | |
536 | in microseconds) more than 1_000_000 and setitimer() is not available | |
537 | in your system to emulate that case. | |
538 | ||
db0b859f JH |
539 | =head2 negative time not invented yet |
540 | ||
541 | You tried to use a negative time argument. | |
542 | ||
543 | =head2 internal error: useconds < 0 (unsigned ... signed ...) | |
544 | ||
545 | Something went horribly wrong-- the number of microseconds that cannot | |
546 | become negative just became negative. Maybe your compiler is broken? | |
547 | ||
bf8300de RGS |
548 | =head2 useconds or uinterval equal to or more than 1000000 |
549 | ||
550 | In some platforms it is not possible to get an alarm with subsecond | |
551 | resolution and later than one second. | |
552 | ||
553 | =head2 unimplemented in this platform | |
554 | ||
555 | Some calls simply aren't available, real or emulated, on every platform. | |
556 | ||
f03b998d JH |
557 | =head1 CAVEATS |
558 | ||
6937b144 | 559 | Notice that the core C<time()> maybe rounding rather than truncating. |
d8cb5b61 RGS |
560 | What this means is that the core C<time()> may be reporting the time |
561 | as one second later than C<gettimeofday()> and C<Time::HiRes::time()>. | |
562 | ||
563 | Adjusting the system clock (either manually or by services like ntp) | |
564 | may cause problems, especially for long running programs that assume | |
565 | a monotonously increasing time (note that all platforms do not adjust | |
566 | time as gracefully as UNIX ntp does). For example in Win32 (and derived | |
567 | platforms like Cygwin and MinGW) the Time::HiRes::time() may temporarily | |
568 | drift off from the system clock (and the original time()) by up to 0.5 | |
569 | seconds. Time::HiRes will notice this eventually and recalibrate. | |
ced84e60 | 570 | Note that since Time::HiRes 1.77 the clock_gettime(CLOCK_MONOTONIC) |
1a7d3a53 | 571 | might help in this (in case your system supports CLOCK_MONOTONIC). |
f03b998d | 572 | |
e5620114 RGS |
573 | Some systems have APIs but not implementations: for example QNX and Haiku |
574 | have the interval timer APIs but not the functionality. | |
575 | ||
26e22fd9 RGS |
576 | =head1 SEE ALSO |
577 | ||
ced84e60 SP |
578 | Perl modules L<BSD::Resource>, L<Time::TAI64>. |
579 | ||
bfe77af1 SP |
580 | Your system documentation for C<clock>, C<clock_gettime>, |
581 | C<clock_getres>, C<clock_nanosleep>, C<clock_settime>, C<getitimer>, | |
582 | C<gettimeofday>, C<setitimer>, C<sleep>, C<stat>, C<ualarm>. | |
26e22fd9 | 583 | |
dcf686c9 JH |
584 | =head1 AUTHORS |
585 | ||
586 | D. Wegscheid <wegscd@whirlpool.com> | |
587 | R. Schertler <roderick@argon.org> | |
588 | J. Hietaniemi <jhi@iki.fi> | |
589 | G. Aas <gisle@aas.no> | |
590 | ||
3f2ee006 | 591 | =head1 COPYRIGHT AND LICENSE |
dcf686c9 | 592 | |
3f2ee006 | 593 | Copyright (c) 1996-2002 Douglas E. Wegscheid. All rights reserved. |
dcf686c9 | 594 | |
bf8300de RGS |
595 | Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 Jarkko Hietaniemi. |
596 | All rights reserved. | |
dcf686c9 | 597 | |
0f0eae2c | 598 | Copyright (C) 2011, 2012, 2013 Andrew Main (Zefram) <zefram@fysh.org> |
91a2e9f6 | 599 | |
3f2ee006 HS |
600 | This program is free software; you can redistribute it and/or modify |
601 | it under the same terms as Perl itself. | |
dcf686c9 JH |
602 | |
603 | =cut |