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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 DynaLoader); |
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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 = '1.72'; |
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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); |
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27 | if ($error) { |
28 | my (undef,$file,$line) = caller; |
29 | die "$error at $file line $line.\n"; |
30 | } |
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31 | { |
32 | no strict 'refs'; |
33 | *$AUTOLOAD = sub { $val }; |
34 | } |
35 | goto &$AUTOLOAD; |
36 | } |
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37 | |
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38 | bootstrap Time::HiRes; |
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39 | |
40 | # Preloaded methods go here. |
41 | |
42 | sub tv_interval { |
43 | # probably could have been done in C |
44 | my ($a, $b) = @_; |
45 | $b = [gettimeofday()] unless defined($b); |
46 | (${$b}[0] - ${$a}[0]) + ((${$b}[1] - ${$a}[1]) / 1_000_000); |
47 | } |
48 | |
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49 | # Autoload methods go after =cut, and are processed by the autosplit program. |
50 | |
51 | 1; |
52 | __END__ |
53 | |
54 | =head1 NAME |
55 | |
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56 | Time::HiRes - High resolution alarm, sleep, gettimeofday, interval timers |
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57 | |
58 | =head1 SYNOPSIS |
59 | |
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60 | use Time::HiRes qw( usleep ualarm gettimeofday tv_interval nanosleep ); |
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61 | |
62 | usleep ($microseconds); |
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63 | nanosleep ($nanoseconds); |
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64 | |
65 | ualarm ($microseconds); |
66 | ualarm ($microseconds, $interval_microseconds); |
67 | |
68 | $t0 = [gettimeofday]; |
69 | ($seconds, $microseconds) = gettimeofday; |
70 | |
71 | $elapsed = tv_interval ( $t0, [$seconds, $microseconds]); |
72 | $elapsed = tv_interval ( $t0, [gettimeofday]); |
73 | $elapsed = tv_interval ( $t0 ); |
74 | |
75 | use Time::HiRes qw ( time alarm sleep ); |
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76 | |
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77 | $now_fractions = time; |
78 | sleep ($floating_seconds); |
79 | alarm ($floating_seconds); |
80 | alarm ($floating_seconds, $floating_interval); |
81 | |
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82 | use Time::HiRes qw( setitimer getitimer |
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83 | ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF ITIMER_REALPROF ); |
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84 | |
85 | setitimer ($which, $floating_seconds, $floating_interval ); |
86 | getitimer ($which); |
87 | |
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88 | =head1 DESCRIPTION |
89 | |
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90 | The C<Time::HiRes> module implements a Perl interface to the |
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91 | C<usleep>, C<nanosleep>, C<ualarm>, C<gettimeofday>, and |
92 | C<setitimer>/C<getitimer> system calls, in other words, high |
93 | resolution time and timers. See the L</EXAMPLES> section below and the |
94 | test scripts for usage; see your system documentation for the |
95 | description of the underlying C<nanosleep> or C<usleep>, C<ualarm>, |
96 | C<gettimeofday>, and C<setitimer>/C<getitimer> calls. |
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97 | |
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98 | If your system lacks C<gettimeofday()> or an emulation of it you don't |
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99 | get C<gettimeofday()> or the one-argument form of C<tv_interval()>. |
100 | If your system lacks all of C<nanosleep()>, C<usleep()>, and |
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101 | C<select()>, you don't get C<Time::HiRes::usleep()>, |
102 | C<Time::HiRes::nanosleep()>, or C<Time::HiRes::sleep()>. If your |
103 | system lacks both C<ualarm()> and C<setitimer()> you don't get |
104 | C<Time::HiRes::ualarm()> or C<Time::HiRes::alarm()>. |
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105 | |
106 | If you try to import an unimplemented function in the C<use> statement |
107 | it will fail at compile time. |
108 | |
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109 | If your subsecond sleeping is implemented with C<nanosleep()> instead |
110 | of C<usleep()>, you can mix subsecond sleeping with signals since |
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111 | C<nanosleep()> does not use signals. This, however, is not portable, |
112 | and you should first check for the truth value of |
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113 | C<&Time::HiRes::d_nanosleep> to see whether you have nanosleep, and |
114 | then carefully read your C<nanosleep()> C API documentation for any |
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115 | peculiarities. |
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116 | |
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117 | If you are using C<nanosleep> for something else than mixing sleeping |
118 | with signals, give some thought to whether Perl is the tool you should |
119 | be using for work requiring nanosecond accuracies. |
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120 | |
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121 | The following functions can be imported from this module. |
122 | No functions are exported by default. |
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123 | |
124 | =over 4 |
125 | |
126 | =item gettimeofday () |
127 | |
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128 | In array context returns a two-element array with the seconds and |
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129 | microseconds since the epoch. In scalar context returns floating |
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130 | seconds like C<Time::HiRes::time()> (see below). |
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131 | |
132 | =item usleep ( $useconds ) |
133 | |
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134 | Sleeps for the number of microseconds (millionths of a second) |
135 | specified. Returns the number of microseconds actually slept. Can |
136 | sleep for more than one second, unlike the C<usleep> system call. See |
137 | also C<Time::HiRes::usleep()> and C<Time::HiRes::sleep()>. |
138 | |
139 | Do not expect usleep() to be exact down to one microsecond. |
140 | |
141 | =item nanosleep ( $nanoseconds ) |
142 | |
143 | Sleeps for the number of nanoseconds (1e9ths of a second) specified. |
144 | Returns the number of nanoseconds actually slept (accurate only to |
145 | microseconds, the nearest thousand of them). Can sleep for more than |
146 | one second. See also C<Time::HiRes::sleep()> and |
147 | C<Time::HiRes::usleep()>. |
148 | |
149 | Do not expect nanosleep() to be exact down to one nanosecond. |
150 | Getting even accuracy of one thousand nanoseconds is good. |
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151 | |
152 | =item ualarm ( $useconds [, $interval_useconds ] ) |
153 | |
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154 | Issues a C<ualarm> call; the C<$interval_useconds> is optional and |
155 | will be zero if unspecified, resulting in C<alarm>-like behaviour. |
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156 | |
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157 | Note that the interaction between alarms and sleeps is unspecified. |
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158 | |
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159 | =item tv_interval |
160 | |
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161 | tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] ) |
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162 | |
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163 | Returns the floating seconds between the two times, which should have |
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164 | been returned by C<gettimeofday()>. If the second argument is omitted, |
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165 | then the current time is used. |
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166 | |
167 | =item time () |
168 | |
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169 | Returns a floating seconds since the epoch. This function can be |
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170 | imported, resulting in a nice drop-in replacement for the C<time> |
171 | provided with core Perl; see the L</EXAMPLES> below. |
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172 | |
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173 | B<NOTE 1>: This higher resolution timer can return values either less |
174 | or more than the core C<time()>, depending on whether your platform |
175 | rounds the higher resolution timer values up, down, or to the nearest second |
176 | to get the core C<time()>, but naturally the difference should be never |
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177 | more than half a second. |
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178 | |
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179 | B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT, when |
180 | the C<time()> seconds since epoch rolled over to 1_000_000_000, the |
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181 | default floating point format of Perl and the seconds since epoch have |
182 | conspired to produce an apparent bug: if you print the value of |
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183 | C<Time::HiRes::time()> you seem to be getting only five decimals, not |
184 | six as promised (microseconds). Not to worry, the microseconds are |
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185 | there (assuming your platform supports such granularity in the first |
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186 | place). What is going on is that the default floating point format of |
187 | Perl only outputs 15 digits. In this case that means ten digits |
188 | before the decimal separator and five after. To see the microseconds |
189 | you can use either C<printf>/C<sprintf> with C<"%.6f">, or the |
190 | C<gettimeofday()> function in list context, which will give you the |
191 | seconds and microseconds as two separate values. |
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192 | |
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193 | =item sleep ( $floating_seconds ) |
194 | |
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195 | Sleeps for the specified amount of seconds. Returns the number of |
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196 | seconds actually slept (a floating point value). This function can |
197 | be imported, resulting in a nice drop-in replacement for the C<sleep> |
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198 | provided with perl, see the L</EXAMPLES> below. |
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199 | |
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200 | Note that the interaction between alarms and sleeps is unspecified. |
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201 | |
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202 | =item alarm ( $floating_seconds [, $interval_floating_seconds ] ) |
203 | |
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204 | The C<SIGALRM> signal is sent after the specified number of seconds. |
205 | Implemented using C<ualarm()>. The C<$interval_floating_seconds> argument |
206 | is optional and will be zero if unspecified, resulting in C<alarm()>-like |
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207 | behaviour. This function can be imported, resulting in a nice drop-in |
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208 | replacement for the C<alarm> provided with perl, see the L</EXAMPLES> below. |
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209 | |
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210 | B<NOTE 1>: With some combinations of operating systems and Perl |
211 | releases C<SIGALRM> restarts C<select()>, instead of interrupting it. |
212 | This means that an C<alarm()> followed by a C<select()> may together |
213 | take the sum of the times specified for the the C<alarm()> and the |
214 | C<select()>, not just the time of the C<alarm()>. |
215 | |
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216 | Note that the interaction between alarms and sleeps is unspecified. |
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217 | |
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218 | =item setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] ) |
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219 | |
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220 | Start up an interval timer: after a certain time, a signal arrives, |
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221 | and more signals may keep arriving at certain intervals. To disable |
222 | an "itimer", use C<$floating_seconds> of zero. If the |
223 | C<$interval_floating_seconds> is set to zero (or unspecified), the |
224 | timer is disabled B<after> the next delivered signal. |
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225 | |
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226 | Use of interval timers may interfere with C<alarm()>, C<sleep()>, |
227 | and C<usleep()>. In standard-speak the "interaction is unspecified", |
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228 | which means that I<anything> may happen: it may work, it may not. |
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229 | |
230 | In scalar context, the remaining time in the timer is returned. |
231 | |
232 | In list context, both the remaining time and the interval are returned. |
233 | |
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234 | There are usually three or four interval timers available: the |
235 | C<$which> can be C<ITIMER_REAL>, C<ITIMER_VIRTUAL>, C<ITIMER_PROF>, or |
236 | C<ITIMER_REALPROF>. Note that which ones are available depends: true |
237 | UNIX platforms usually have the first three, but (for example) Win32 |
238 | and Cygwin have only C<ITIMER_REAL>, and only Solaris seems to have |
239 | C<ITIMER_REALPROF> (which is used to profile multithreaded programs). |
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240 | |
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241 | C<ITIMER_REAL> results in C<alarm()>-like behaviour. Time is counted in |
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242 | I<real time>; that is, wallclock time. C<SIGALRM> is delivered when |
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243 | the timer expires. |
244 | |
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245 | C<ITIMER_VIRTUAL> counts time in (process) I<virtual time>; that is, |
246 | only when the process is running. In multiprocessor/user/CPU systems |
247 | this may be more or less than real or wallclock time. (This time is |
248 | also known as the I<user time>.) C<SIGVTALRM> is delivered when the |
249 | timer expires. |
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250 | |
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251 | C<ITIMER_PROF> counts time when either the process virtual time or when |
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252 | the operating system is running on behalf of the process (such as I/O). |
253 | (This time is also known as the I<system time>.) (The sum of user |
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254 | time and system time is known as the I<CPU time>.) C<SIGPROF> is |
255 | delivered when the timer expires. C<SIGPROF> can interrupt system calls. |
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256 | |
257 | The semantics of interval timers for multithreaded programs are |
258 | system-specific, and some systems may support additional interval |
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259 | timers. See your C<setitimer()> documentation. |
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260 | |
261 | =item getitimer ( $which ) |
262 | |
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263 | Return the remaining time in the interval timer specified by C<$which>. |
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264 | |
265 | In scalar context, the remaining time is returned. |
266 | |
267 | In list context, both the remaining time and the interval are returned. |
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268 | The interval is always what you put in using C<setitimer()>. |
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269 | |
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270 | =back |
271 | |
272 | =head1 EXAMPLES |
273 | |
274 | use Time::HiRes qw(usleep ualarm gettimeofday tv_interval); |
275 | |
276 | $microseconds = 750_000; |
277 | usleep $microseconds; |
278 | |
279 | # signal alarm in 2.5s & every .1s thereafter |
280 | ualarm 2_500_000, 100_000; |
281 | |
282 | # get seconds and microseconds since the epoch |
283 | ($s, $usec) = gettimeofday; |
284 | |
285 | # measure elapsed time |
286 | # (could also do by subtracting 2 gettimeofday return values) |
287 | $t0 = [gettimeofday]; |
288 | # do bunch of stuff here |
289 | $t1 = [gettimeofday]; |
290 | # do more stuff here |
291 | $t0_t1 = tv_interval $t0, $t1; |
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292 | |
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293 | $elapsed = tv_interval ($t0, [gettimeofday]); |
294 | $elapsed = tv_interval ($t0); # equivalent code |
295 | |
296 | # |
297 | # replacements for time, alarm and sleep that know about |
298 | # floating seconds |
299 | # |
300 | use Time::HiRes; |
301 | $now_fractions = Time::HiRes::time; |
302 | Time::HiRes::sleep (2.5); |
303 | Time::HiRes::alarm (10.6666666); |
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304 | |
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305 | use Time::HiRes qw ( time alarm sleep ); |
306 | $now_fractions = time; |
307 | sleep (2.5); |
308 | alarm (10.6666666); |
309 | |
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310 | # Arm an interval timer to go off first at 10 seconds and |
311 | # after that every 2.5 seconds, in process virtual time |
312 | |
313 | use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time ); |
314 | |
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315 | $SIG{VTALRM} = sub { print time, "\n" }; |
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316 | setitimer(ITIMER_VIRTUAL, 10, 2.5); |
317 | |
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318 | =head1 C API |
319 | |
320 | In addition to the perl API described above, a C API is available for |
321 | extension writers. The following C functions are available in the |
322 | modglobal hash: |
323 | |
324 | name C prototype |
325 | --------------- ---------------------- |
326 | Time::NVtime double (*)() |
327 | Time::U2time void (*)(UV ret[2]) |
328 | |
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329 | Both functions return equivalent information (like C<gettimeofday>) |
330 | but with different representations. The names C<NVtime> and C<U2time> |
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331 | were selected mainly because they are operating system independent. |
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332 | (C<gettimeofday> is Unix-centric, though some platforms like Win32 and |
333 | VMS have emulations for it.) |
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334 | |
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335 | Here is an example of using C<NVtime> from C: |
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336 | |
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337 | double (*myNVtime)(); /* Returns -1 on failure. */ |
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338 | SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0); |
339 | if (!svp) croak("Time::HiRes is required"); |
340 | if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer"); |
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341 | myNVtime = INT2PTR(double(*)(), SvIV(*svp)); |
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342 | printf("The current time is: %f\n", (*myNVtime)()); |
343 | |
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344 | =head1 DIAGNOSTICS |
345 | |
346 | =head2 negative time not invented yet |
347 | |
348 | You tried to use a negative time argument. |
349 | |
350 | =head2 internal error: useconds < 0 (unsigned ... signed ...) |
351 | |
352 | Something went horribly wrong-- the number of microseconds that cannot |
353 | become negative just became negative. Maybe your compiler is broken? |
354 | |
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355 | =head1 CAVEATS |
356 | |
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357 | Notice that the core C<time()> maybe rounding rather than truncating. |
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358 | What this means is that the core C<time()> may be reporting the time |
359 | as one second later than C<gettimeofday()> and C<Time::HiRes::time()>. |
360 | |
361 | Adjusting the system clock (either manually or by services like ntp) |
362 | may cause problems, especially for long running programs that assume |
363 | a monotonously increasing time (note that all platforms do not adjust |
364 | time as gracefully as UNIX ntp does). For example in Win32 (and derived |
365 | platforms like Cygwin and MinGW) the Time::HiRes::time() may temporarily |
366 | drift off from the system clock (and the original time()) by up to 0.5 |
367 | seconds. Time::HiRes will notice this eventually and recalibrate. |
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368 | |
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369 | =head1 SEE ALSO |
370 | |
371 | L<BSD::Resource>, L<Time::TAI64>. |
372 | |
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373 | =head1 AUTHORS |
374 | |
375 | D. Wegscheid <wegscd@whirlpool.com> |
376 | R. Schertler <roderick@argon.org> |
377 | J. Hietaniemi <jhi@iki.fi> |
378 | G. Aas <gisle@aas.no> |
379 | |
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380 | =head1 COPYRIGHT AND LICENSE |
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381 | |
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382 | Copyright (c) 1996-2002 Douglas E. Wegscheid. All rights reserved. |
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383 | |
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384 | Copyright (c) 2002, 2003, 2004, 2005 Jarkko Hietaniemi. All rights reserved. |
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385 | |
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386 | This program is free software; you can redistribute it and/or modify |
387 | it under the same terms as Perl itself. |
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388 | |
389 | =cut |