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1 | package Time::HiRes; |
2 | |
3 | use strict; |
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4 | use vars qw($VERSION $XS_VERSION @ISA @EXPORT @EXPORT_OK $AUTOLOAD); |
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5 | |
6 | require Exporter; |
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7 | require DynaLoader; |
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8 | |
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9 | @ISA = qw(Exporter); |
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10 | |
11 | @EXPORT = qw( ); |
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12 | @EXPORT_OK = qw (usleep sleep ualarm alarm gettimeofday time tv_interval |
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13 | getitimer setitimer nanosleep |
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14 | ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF ITIMER_REALPROF |
15 | d_usleep d_ualarm d_gettimeofday d_getitimer d_setitimer |
16 | d_nanosleep); |
17 | |
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18 | $VERSION = '1.71'; |
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19 | $XS_VERSION = $VERSION; |
20 | $VERSION = eval $VERSION; |
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21 | |
22 | sub AUTOLOAD { |
23 | my $constname; |
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24 | ($constname = $AUTOLOAD) =~ s/.*:://; |
25 | die "&Time::HiRes::constant not defined" if $constname eq 'constant'; |
26 | my ($error, $val) = constant($constname); |
27 | if ($error) { die $error; } |
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28 | { |
29 | no strict 'refs'; |
30 | *$AUTOLOAD = sub { $val }; |
31 | } |
32 | goto &$AUTOLOAD; |
33 | } |
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34 | |
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35 | eval { |
36 | require XSLoader; |
37 | XSLoader::load('Time::HiRes', $XS_VERSION); |
38 | 1; |
39 | } or do { |
40 | require DynaLoader; |
41 | local @ISA = qw(DynaLoader); |
42 | bootstrap Time::HiRes $XS_VERSION; |
43 | }; |
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44 | |
45 | # Preloaded methods go here. |
46 | |
47 | sub tv_interval { |
48 | # probably could have been done in C |
49 | my ($a, $b) = @_; |
50 | $b = [gettimeofday()] unless defined($b); |
51 | (${$b}[0] - ${$a}[0]) + ((${$b}[1] - ${$a}[1]) / 1_000_000); |
52 | } |
53 | |
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54 | # Autoload methods go after =cut, and are processed by the autosplit program. |
55 | |
56 | 1; |
57 | __END__ |
58 | |
59 | =head1 NAME |
60 | |
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61 | Time::HiRes - High resolution alarm, sleep, gettimeofday, interval timers |
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62 | |
63 | =head1 SYNOPSIS |
64 | |
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65 | use Time::HiRes qw( usleep ualarm gettimeofday tv_interval nanosleep ); |
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66 | |
67 | usleep ($microseconds); |
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68 | nanosleep ($nanoseconds); |
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69 | |
70 | ualarm ($microseconds); |
71 | ualarm ($microseconds, $interval_microseconds); |
72 | |
73 | $t0 = [gettimeofday]; |
74 | ($seconds, $microseconds) = gettimeofday; |
75 | |
76 | $elapsed = tv_interval ( $t0, [$seconds, $microseconds]); |
77 | $elapsed = tv_interval ( $t0, [gettimeofday]); |
78 | $elapsed = tv_interval ( $t0 ); |
79 | |
80 | use Time::HiRes qw ( time alarm sleep ); |
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81 | |
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82 | $now_fractions = time; |
83 | sleep ($floating_seconds); |
84 | alarm ($floating_seconds); |
85 | alarm ($floating_seconds, $floating_interval); |
86 | |
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87 | use Time::HiRes qw( setitimer getitimer |
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88 | ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF ITIMER_REALPROF ); |
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89 | |
90 | setitimer ($which, $floating_seconds, $floating_interval ); |
91 | getitimer ($which); |
92 | |
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93 | =head1 DESCRIPTION |
94 | |
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95 | The C<Time::HiRes> module implements a Perl interface to the |
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96 | C<usleep>, C<nanosleep>, C<ualarm>, C<gettimeofday>, and |
97 | C<setitimer>/C<getitimer> system calls, in other words, high |
98 | resolution time and timers. See the L</EXAMPLES> section below and the |
99 | test scripts for usage; see your system documentation for the |
100 | description of the underlying C<nanosleep> or C<usleep>, C<ualarm>, |
101 | C<gettimeofday>, and C<setitimer>/C<getitimer> calls. |
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102 | |
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103 | If your system lacks C<gettimeofday()> or an emulation of it you don't |
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104 | get C<gettimeofday()> or the one-argument form of C<tv_interval()>. |
105 | If your system lacks all of C<nanosleep()>, C<usleep()>, and |
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106 | C<select()>, you don't get C<Time::HiRes::usleep()>, |
107 | C<Time::HiRes::nanosleep()>, or C<Time::HiRes::sleep()>. If your |
108 | system lacks both C<ualarm()> and C<setitimer()> you don't get |
109 | C<Time::HiRes::ualarm()> or C<Time::HiRes::alarm()>. |
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110 | |
111 | If you try to import an unimplemented function in the C<use> statement |
112 | it will fail at compile time. |
113 | |
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114 | If your subsecond sleeping is implemented with C<nanosleep()> instead |
115 | of C<usleep()>, you can mix subsecond sleeping with signals since |
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116 | C<nanosleep()> does not use signals. This, however, is not portable, |
117 | and you should first check for the truth value of |
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118 | C<&Time::HiRes::d_nanosleep> to see whether you have nanosleep, and |
119 | then carefully read your C<nanosleep()> C API documentation for any |
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120 | peculiarities. |
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121 | |
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122 | Unless using C<nanosleep> for mixing sleeping with signals, give |
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123 | some thought to whether Perl is the tool you should be using for |
124 | work requiring nanosecond accuracies. |
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125 | |
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126 | The following functions can be imported from this module. |
127 | No functions are exported by default. |
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128 | |
129 | =over 4 |
130 | |
131 | =item gettimeofday () |
132 | |
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133 | In array context returns a two-element array with the seconds and |
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134 | microseconds since the epoch. In scalar context returns floating |
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135 | seconds like C<Time::HiRes::time()> (see below). |
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136 | |
137 | =item usleep ( $useconds ) |
138 | |
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139 | Sleeps for the number of microseconds (millionths of a second) |
140 | specified. Returns the number of microseconds actually slept. Can |
141 | sleep for more than one second, unlike the C<usleep> system call. See |
142 | also C<Time::HiRes::usleep()> and C<Time::HiRes::sleep()>. |
143 | |
144 | Do not expect usleep() to be exact down to one microsecond. |
145 | |
146 | =item nanosleep ( $nanoseconds ) |
147 | |
148 | Sleeps for the number of nanoseconds (1e9ths of a second) specified. |
149 | Returns the number of nanoseconds actually slept (accurate only to |
150 | microseconds, the nearest thousand of them). Can sleep for more than |
151 | one second. See also C<Time::HiRes::sleep()> and |
152 | C<Time::HiRes::usleep()>. |
153 | |
154 | Do not expect nanosleep() to be exact down to one nanosecond. |
155 | Getting even accuracy of one thousand nanoseconds is good. |
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156 | |
157 | =item ualarm ( $useconds [, $interval_useconds ] ) |
158 | |
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159 | Issues a C<ualarm> call; the C<$interval_useconds> is optional and |
160 | will be zero if unspecified, resulting in C<alarm>-like behaviour. |
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161 | |
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162 | Note that the interaction between alarms and sleeps is unspecified. |
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163 | |
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164 | =item tv_interval |
165 | |
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166 | tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] ) |
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167 | |
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168 | Returns the floating seconds between the two times, which should have |
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169 | been returned by C<gettimeofday()>. If the second argument is omitted, |
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170 | then the current time is used. |
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171 | |
172 | =item time () |
173 | |
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174 | Returns a floating seconds since the epoch. This function can be |
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175 | imported, resulting in a nice drop-in replacement for the C<time> |
176 | provided with core Perl; see the L</EXAMPLES> below. |
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177 | |
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178 | B<NOTE 1>: This higher resolution timer can return values either less |
179 | or more than the core C<time()>, depending on whether your platform |
180 | rounds the higher resolution timer values up, down, or to the nearest second |
181 | to get the core C<time()>, but naturally the difference should be never |
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182 | more than half a second. |
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183 | |
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184 | B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT, when |
185 | the C<time()> seconds since epoch rolled over to 1_000_000_000, the |
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186 | default floating point format of Perl and the seconds since epoch have |
187 | conspired to produce an apparent bug: if you print the value of |
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188 | C<Time::HiRes::time()> you seem to be getting only five decimals, not |
189 | six as promised (microseconds). Not to worry, the microseconds are |
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190 | there (assuming your platform supports such granularity in the first |
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191 | place). What is going on is that the default floating point format of |
192 | Perl only outputs 15 digits. In this case that means ten digits |
193 | before the decimal separator and five after. To see the microseconds |
194 | you can use either C<printf>/C<sprintf> with C<"%.6f">, or the |
195 | C<gettimeofday()> function in list context, which will give you the |
196 | seconds and microseconds as two separate values. |
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197 | |
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198 | =item sleep ( $floating_seconds ) |
199 | |
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200 | Sleeps for the specified amount of seconds. Returns the number of |
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201 | seconds actually slept (a floating point value). This function can |
202 | be imported, resulting in a nice drop-in replacement for the C<sleep> |
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203 | provided with perl, see the L</EXAMPLES> below. |
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204 | |
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205 | Note that the interaction between alarms and sleeps is unspecified. |
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206 | |
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207 | =item alarm ( $floating_seconds [, $interval_floating_seconds ] ) |
208 | |
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209 | The C<SIGALRM> signal is sent after the specified number of seconds. |
210 | Implemented using C<ualarm()>. The C<$interval_floating_seconds> argument |
211 | is optional and will be zero if unspecified, resulting in C<alarm()>-like |
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212 | behaviour. This function can be imported, resulting in a nice drop-in |
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213 | replacement for the C<alarm> provided with perl, see the L</EXAMPLES> below. |
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214 | |
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215 | B<NOTE 1>: With some combinations of operating systems and Perl |
216 | releases C<SIGALRM> restarts C<select()>, instead of interrupting it. |
217 | This means that an C<alarm()> followed by a C<select()> may together |
218 | take the sum of the times specified for the the C<alarm()> and the |
219 | C<select()>, not just the time of the C<alarm()>. |
220 | |
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221 | Note that the interaction between alarms and sleeps is unspecified. |
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222 | |
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223 | =item setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] ) |
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224 | |
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225 | Start up an interval timer: after a certain time, a signal arrives, |
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226 | and more signals may keep arriving at certain intervals. To disable |
227 | an "itimer", use C<$floating_seconds> of zero. If the |
228 | C<$interval_floating_seconds> is set to zero (or unspecified), the |
229 | timer is disabled B<after> the next delivered signal. |
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230 | |
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231 | Use of interval timers may interfere with C<alarm()>, C<sleep()>, |
232 | and C<usleep()>. In standard-speak the "interaction is unspecified", |
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233 | which means that I<anything> may happen: it may work, it may not. |
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234 | |
235 | In scalar context, the remaining time in the timer is returned. |
236 | |
237 | In list context, both the remaining time and the interval are returned. |
238 | |
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239 | There are usually three or four interval timers available: the |
240 | C<$which> can be C<ITIMER_REAL>, C<ITIMER_VIRTUAL>, C<ITIMER_PROF>, or |
241 | C<ITIMER_REALPROF>. Note that which ones are available depends: true |
242 | UNIX platforms usually have the first three, but (for example) Win32 |
243 | and Cygwin have only C<ITIMER_REAL>, and only Solaris seems to have |
244 | C<ITIMER_REALPROF> (which is used to profile multithreaded programs). |
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245 | |
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246 | C<ITIMER_REAL> results in C<alarm()>-like behaviour. Time is counted in |
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247 | I<real time>; that is, wallclock time. C<SIGALRM> is delivered when |
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248 | the timer expires. |
249 | |
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250 | C<ITIMER_VIRTUAL> counts time in (process) I<virtual time>; that is, |
251 | only when the process is running. In multiprocessor/user/CPU systems |
252 | this may be more or less than real or wallclock time. (This time is |
253 | also known as the I<user time>.) C<SIGVTALRM> is delivered when the |
254 | timer expires. |
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255 | |
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256 | C<ITIMER_PROF> counts time when either the process virtual time or when |
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257 | the operating system is running on behalf of the process (such as I/O). |
258 | (This time is also known as the I<system time>.) (The sum of user |
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259 | time and system time is known as the I<CPU time>.) C<SIGPROF> is |
260 | delivered when the timer expires. C<SIGPROF> can interrupt system calls. |
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261 | |
262 | The semantics of interval timers for multithreaded programs are |
263 | system-specific, and some systems may support additional interval |
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264 | timers. See your C<setitimer()> documentation. |
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265 | |
266 | =item getitimer ( $which ) |
267 | |
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268 | Return the remaining time in the interval timer specified by C<$which>. |
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269 | |
270 | In scalar context, the remaining time is returned. |
271 | |
272 | In list context, both the remaining time and the interval are returned. |
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273 | The interval is always what you put in using C<setitimer()>. |
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274 | |
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275 | =back |
276 | |
277 | =head1 EXAMPLES |
278 | |
279 | use Time::HiRes qw(usleep ualarm gettimeofday tv_interval); |
280 | |
281 | $microseconds = 750_000; |
282 | usleep $microseconds; |
283 | |
284 | # signal alarm in 2.5s & every .1s thereafter |
285 | ualarm 2_500_000, 100_000; |
286 | |
287 | # get seconds and microseconds since the epoch |
288 | ($s, $usec) = gettimeofday; |
289 | |
290 | # measure elapsed time |
291 | # (could also do by subtracting 2 gettimeofday return values) |
292 | $t0 = [gettimeofday]; |
293 | # do bunch of stuff here |
294 | $t1 = [gettimeofday]; |
295 | # do more stuff here |
296 | $t0_t1 = tv_interval $t0, $t1; |
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297 | |
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298 | $elapsed = tv_interval ($t0, [gettimeofday]); |
299 | $elapsed = tv_interval ($t0); # equivalent code |
300 | |
301 | # |
302 | # replacements for time, alarm and sleep that know about |
303 | # floating seconds |
304 | # |
305 | use Time::HiRes; |
306 | $now_fractions = Time::HiRes::time; |
307 | Time::HiRes::sleep (2.5); |
308 | Time::HiRes::alarm (10.6666666); |
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309 | |
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310 | use Time::HiRes qw ( time alarm sleep ); |
311 | $now_fractions = time; |
312 | sleep (2.5); |
313 | alarm (10.6666666); |
314 | |
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315 | # Arm an interval timer to go off first at 10 seconds and |
316 | # after that every 2.5 seconds, in process virtual time |
317 | |
318 | use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time ); |
319 | |
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320 | $SIG{VTALRM} = sub { print time, "\n" }; |
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321 | setitimer(ITIMER_VIRTUAL, 10, 2.5); |
322 | |
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323 | =head1 C API |
324 | |
325 | In addition to the perl API described above, a C API is available for |
326 | extension writers. The following C functions are available in the |
327 | modglobal hash: |
328 | |
329 | name C prototype |
330 | --------------- ---------------------- |
331 | Time::NVtime double (*)() |
332 | Time::U2time void (*)(UV ret[2]) |
333 | |
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334 | Both functions return equivalent information (like C<gettimeofday>) |
335 | but with different representations. The names C<NVtime> and C<U2time> |
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336 | were selected mainly because they are operating system independent. |
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337 | (C<gettimeofday> is Unix-centric, though some platforms like Win32 and |
338 | VMS have emulations for it.) |
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339 | |
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340 | Here is an example of using C<NVtime> from C: |
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341 | |
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342 | double (*myNVtime)(); /* Returns -1 on failure. */ |
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343 | SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0); |
344 | if (!svp) croak("Time::HiRes is required"); |
345 | if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer"); |
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346 | myNVtime = INT2PTR(double(*)(), SvIV(*svp)); |
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347 | printf("The current time is: %f\n", (*myNVtime)()); |
348 | |
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349 | =head1 DIAGNOSTICS |
350 | |
351 | =head2 negative time not invented yet |
352 | |
353 | You tried to use a negative time argument. |
354 | |
355 | =head2 internal error: useconds < 0 (unsigned ... signed ...) |
356 | |
357 | Something went horribly wrong-- the number of microseconds that cannot |
358 | become negative just became negative. Maybe your compiler is broken? |
359 | |
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360 | =head1 CAVEATS |
361 | |
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362 | Notice that the core C<time()> maybe rounding rather than truncating. |
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363 | What this means is that the core C<time()> may be reporting the time |
364 | as one second later than C<gettimeofday()> and C<Time::HiRes::time()>. |
365 | |
366 | Adjusting the system clock (either manually or by services like ntp) |
367 | may cause problems, especially for long running programs that assume |
368 | a monotonously increasing time (note that all platforms do not adjust |
369 | time as gracefully as UNIX ntp does). For example in Win32 (and derived |
370 | platforms like Cygwin and MinGW) the Time::HiRes::time() may temporarily |
371 | drift off from the system clock (and the original time()) by up to 0.5 |
372 | seconds. Time::HiRes will notice this eventually and recalibrate. |
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373 | |
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374 | =head1 SEE ALSO |
375 | |
376 | L<BSD::Resource>, L<Time::TAI64>. |
377 | |
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378 | =head1 AUTHORS |
379 | |
380 | D. Wegscheid <wegscd@whirlpool.com> |
381 | R. Schertler <roderick@argon.org> |
382 | J. Hietaniemi <jhi@iki.fi> |
383 | G. Aas <gisle@aas.no> |
384 | |
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385 | =head1 COPYRIGHT AND LICENSE |
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386 | |
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387 | Copyright (c) 1996-2002 Douglas E. Wegscheid. All rights reserved. |
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388 | |
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389 | Copyright (c) 2002,2003,2004,2005 Jarkko Hietaniemi. All rights reserved. |
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390 | |
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391 | This program is free software; you can redistribute it and/or modify |
392 | it under the same terms as Perl itself. |
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393 | |
394 | =cut |