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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 |
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 = '1.63'; |
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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 | bootstrap Time::HiRes; |
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36 | |
37 | # Preloaded methods go here. |
38 | |
39 | sub tv_interval { |
40 | # probably could have been done in C |
41 | my ($a, $b) = @_; |
42 | $b = [gettimeofday()] unless defined($b); |
43 | (${$b}[0] - ${$a}[0]) + ((${$b}[1] - ${$a}[1]) / 1_000_000); |
44 | } |
45 | |
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46 | # Autoload methods go after =cut, and are processed by the autosplit program. |
47 | |
48 | 1; |
49 | __END__ |
50 | |
51 | =head1 NAME |
52 | |
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53 | Time::HiRes - High resolution alarm, sleep, gettimeofday, interval timers |
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54 | |
55 | =head1 SYNOPSIS |
56 | |
57 | use Time::HiRes qw( usleep ualarm gettimeofday tv_interval ); |
58 | |
59 | usleep ($microseconds); |
60 | |
61 | ualarm ($microseconds); |
62 | ualarm ($microseconds, $interval_microseconds); |
63 | |
64 | $t0 = [gettimeofday]; |
65 | ($seconds, $microseconds) = gettimeofday; |
66 | |
67 | $elapsed = tv_interval ( $t0, [$seconds, $microseconds]); |
68 | $elapsed = tv_interval ( $t0, [gettimeofday]); |
69 | $elapsed = tv_interval ( $t0 ); |
70 | |
71 | use Time::HiRes qw ( time alarm sleep ); |
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72 | |
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73 | $now_fractions = time; |
74 | sleep ($floating_seconds); |
75 | alarm ($floating_seconds); |
76 | alarm ($floating_seconds, $floating_interval); |
77 | |
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78 | use Time::HiRes qw( setitimer getitimer |
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79 | ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF ITIMER_REALPROF ); |
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80 | |
81 | setitimer ($which, $floating_seconds, $floating_interval ); |
82 | getitimer ($which); |
83 | |
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84 | =head1 DESCRIPTION |
85 | |
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86 | The C<Time::HiRes> module implements a Perl interface to the |
87 | C<usleep>, C<ualarm>, C<gettimeofday>, and C<setitimer>/C<getitimer> |
88 | system calls, in other words, high resolution time and timers. See the |
89 | L</EXAMPLES> section below and the test scripts for usage; see your |
90 | system documentation for the description of the underlying |
91 | C<nanosleep> or C<usleep>, C<ualarm>, C<gettimeofday>, and |
92 | C<setitimer>/C<getitimer> calls. |
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93 | |
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94 | If your system lacks C<gettimeofday()> or an emulation of it you don't |
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95 | get C<gettimeofday()> or the one-argument form of C<tv_interval()>. |
96 | If your system lacks all of C<nanosleep()>, C<usleep()>, and |
97 | C<select()>, you don't get C<Time::HiRes::usleep()> or |
98 | C<Time::HiRes::sleep()>. If your system lacks both C<ualarm()> and |
99 | C<setitimer()> you don't get C<Time::HiRes::ualarm()> or |
100 | C<Time::HiRes::alarm()>. |
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101 | |
102 | If you try to import an unimplemented function in the C<use> statement |
103 | it will fail at compile time. |
104 | |
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105 | If your subsecond sleeping is implemented with C<nanosleep()> instead |
106 | of C<usleep()>, you can mix subsecond sleeping with signals since |
107 | C<nanosleep()> does not use signals. This, however is unportable, and |
108 | you should first check for the truth value of |
109 | C<&Time::HiRes::d_nanosleep> to see whether you have nanosleep, and |
110 | then carefully read your C<nanosleep()> C API documentation for any |
111 | peculiarities. (There is no separate interface to call |
112 | C<nanosleep()>; just use C<Time::HiRes::sleep()> or |
113 | C<Time::HiRes::usleep()> with small enough values.) |
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114 | |
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115 | Unless using C<nanosleep> for mixing sleeping with signals, give |
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116 | some thought to whether Perl is the tool you should be using for |
117 | work requiring nanosecond accuracies. |
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118 | |
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119 | The following functions can be imported from this module. |
120 | No functions are exported by default. |
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121 | |
122 | =over 4 |
123 | |
124 | =item gettimeofday () |
125 | |
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126 | In array context returns a two-element array with the seconds and |
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127 | microseconds since the epoch. In scalar context returns floating |
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128 | seconds like C<Time::HiRes::time()> (see below). |
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129 | |
130 | =item usleep ( $useconds ) |
131 | |
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132 | Sleeps for the number of microseconds specified. Returns the number |
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133 | of microseconds actually slept. Can sleep for more than one second, |
134 | unlike the C<usleep> system call. See also C<Time::HiRes::sleep()> below. |
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135 | |
136 | =item ualarm ( $useconds [, $interval_useconds ] ) |
137 | |
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138 | Issues a C<ualarm> call; the C<$interval_useconds> is optional and |
139 | will be zero if unspecified, resulting in C<alarm>-like behaviour. |
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140 | |
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141 | =item tv_interval |
142 | |
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143 | tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] ) |
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144 | |
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145 | Returns the floating seconds between the two times, which should have |
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146 | been returned by C<gettimeofday()>. If the second argument is omitted, |
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147 | then the current time is used. |
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148 | |
149 | =item time () |
150 | |
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151 | Returns a floating seconds since the epoch. This function can be |
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152 | imported, resulting in a nice drop-in replacement for the C<time> |
153 | provided with core Perl; see the L</EXAMPLES> below. |
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154 | |
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155 | B<NOTE 1>: This higher resolution timer can return values either less |
156 | or more than the core C<time()>, depending on whether your platform |
157 | rounds the higher resolution timer values up, down, or to the nearest second |
158 | to get the core C<time()>, but naturally the difference should be never |
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159 | more than half a second. |
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160 | |
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161 | B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT, when |
162 | the C<time()> seconds since epoch rolled over to 1_000_000_000, the |
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163 | default floating point format of Perl and the seconds since epoch have |
164 | conspired to produce an apparent bug: if you print the value of |
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165 | C<Time::HiRes::time()> you seem to be getting only five decimals, not |
166 | six as promised (microseconds). Not to worry, the microseconds are |
167 | there (assuming your platform supports such granularity in first |
168 | place). What is going on is that the default floating point format of |
169 | Perl only outputs 15 digits. In this case that means ten digits |
170 | before the decimal separator and five after. To see the microseconds |
171 | you can use either C<printf>/C<sprintf> with C<"%.6f">, or the |
172 | C<gettimeofday()> function in list context, which will give you the |
173 | seconds and microseconds as two separate values. |
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174 | |
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175 | =item sleep ( $floating_seconds ) |
176 | |
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177 | Sleeps for the specified amount of seconds. Returns the number of |
178 | seconds actually slept (a floating point value). This function can be |
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179 | imported, resulting in a nice drop-in replacement for the C<sleep> |
180 | provided with perl, see the L</EXAMPLES> below. |
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181 | |
182 | =item alarm ( $floating_seconds [, $interval_floating_seconds ] ) |
183 | |
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184 | The C<SIGALRM> signal is sent after the specified number of seconds. |
185 | Implemented using C<ualarm()>. The C<$interval_floating_seconds> argument |
186 | is optional and will be zero if unspecified, resulting in C<alarm()>-like |
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187 | behaviour. This function can be imported, resulting in a nice drop-in |
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188 | replacement for the C<alarm> provided with perl, see the L</EXAMPLES> below. |
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189 | |
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190 | B<NOTE 1>: With some operating system and Perl release combinations |
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191 | C<SIGALRM> restarts C<select()>, instead of interuping it. |
192 | This means that an C<alarm()> followed by a C<select()> |
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193 | may together take the sum of the times specified for the the |
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194 | C<alarm()> and the C<select()>, not just the time of the C<alarm()>. |
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195 | |
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196 | =item setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] ) |
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197 | |
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198 | Start up an interval timer: after a certain time, a signal arrives, |
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199 | and more signals may keep arriving at certain intervals. To disable a |
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200 | timer, use C<$floating_seconds> of zero. If the C<$interval_floating_seconds> |
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201 | is set to zero (or unspecified), the timer is disabled B<after> the |
202 | next delivered signal. |
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203 | |
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204 | Use of interval timers may interfere with C<alarm()>, C<sleep()>, |
205 | and C<usleep()>. In standard-speak the "interaction is unspecified", |
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206 | which means that I<anything> may happen: it may work, it may not. |
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207 | |
208 | In scalar context, the remaining time in the timer is returned. |
209 | |
210 | In list context, both the remaining time and the interval are returned. |
211 | |
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212 | There are usually three or four interval timers available: the |
213 | C<$which> can be C<ITIMER_REAL>, C<ITIMER_VIRTUAL>, C<ITIMER_PROF>, or |
214 | C<ITIMER_REALPROF>. Note that which ones are available depends: true |
215 | UNIX platforms usually have the first three, but (for example) Win32 |
216 | and Cygwin have only C<ITIMER_REAL>, and only Solaris seems to have |
217 | C<ITIMER_REALPROF> (which is used to profile multithreaded programs). |
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218 | |
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219 | C<ITIMER_REAL> results in C<alarm()>-like behavior. Time is counted in |
220 | I<real time>; that is, wallclock time. C<SIGALRM> is delivered when |
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221 | the timer expires. |
222 | |
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223 | C<ITIMER_VIRTUAL> counts time in (process) I<virtual time>; that is, |
224 | only when the process is running. In multiprocessor/user/CPU systems |
225 | this may be more or less than real or wallclock time. (This time is |
226 | also known as the I<user time>.) C<SIGVTALRM> is delivered when the |
227 | timer expires. |
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228 | |
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229 | C<ITIMER_PROF> counts time when either the process virtual time or when |
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230 | the operating system is running on behalf of the process (such as I/O). |
231 | (This time is also known as the I<system time>.) (The sum of user |
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232 | time and system time is known as the I<CPU time>.) C<SIGPROF> is |
233 | delivered when the timer expires. C<SIGPROF> can interrupt system calls. |
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234 | |
235 | The semantics of interval timers for multithreaded programs are |
236 | system-specific, and some systems may support additional interval |
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237 | timers. See your C<setitimer()> documentation. |
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238 | |
239 | =item getitimer ( $which ) |
240 | |
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241 | Return the remaining time in the interval timer specified by C<$which>. |
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242 | |
243 | In scalar context, the remaining time is returned. |
244 | |
245 | In list context, both the remaining time and the interval are returned. |
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246 | The interval is always what you put in using C<setitimer()>. |
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247 | |
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248 | =back |
249 | |
250 | =head1 EXAMPLES |
251 | |
252 | use Time::HiRes qw(usleep ualarm gettimeofday tv_interval); |
253 | |
254 | $microseconds = 750_000; |
255 | usleep $microseconds; |
256 | |
257 | # signal alarm in 2.5s & every .1s thereafter |
258 | ualarm 2_500_000, 100_000; |
259 | |
260 | # get seconds and microseconds since the epoch |
261 | ($s, $usec) = gettimeofday; |
262 | |
263 | # measure elapsed time |
264 | # (could also do by subtracting 2 gettimeofday return values) |
265 | $t0 = [gettimeofday]; |
266 | # do bunch of stuff here |
267 | $t1 = [gettimeofday]; |
268 | # do more stuff here |
269 | $t0_t1 = tv_interval $t0, $t1; |
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270 | |
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271 | $elapsed = tv_interval ($t0, [gettimeofday]); |
272 | $elapsed = tv_interval ($t0); # equivalent code |
273 | |
274 | # |
275 | # replacements for time, alarm and sleep that know about |
276 | # floating seconds |
277 | # |
278 | use Time::HiRes; |
279 | $now_fractions = Time::HiRes::time; |
280 | Time::HiRes::sleep (2.5); |
281 | Time::HiRes::alarm (10.6666666); |
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282 | |
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283 | use Time::HiRes qw ( time alarm sleep ); |
284 | $now_fractions = time; |
285 | sleep (2.5); |
286 | alarm (10.6666666); |
287 | |
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288 | # Arm an interval timer to go off first at 10 seconds and |
289 | # after that every 2.5 seconds, in process virtual time |
290 | |
291 | use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time ); |
292 | |
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293 | $SIG{VTALRM} = sub { print time, "\n" }; |
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294 | setitimer(ITIMER_VIRTUAL, 10, 2.5); |
295 | |
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296 | =head1 C API |
297 | |
298 | In addition to the perl API described above, a C API is available for |
299 | extension writers. The following C functions are available in the |
300 | modglobal hash: |
301 | |
302 | name C prototype |
303 | --------------- ---------------------- |
304 | Time::NVtime double (*)() |
305 | Time::U2time void (*)(UV ret[2]) |
306 | |
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307 | Both functions return equivalent information (like C<gettimeofday>) |
308 | but with different representations. The names C<NVtime> and C<U2time> |
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309 | were selected mainly because they are operating system independent. |
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310 | (C<gettimeofday> is Unix-centric, though some platforms like VMS have |
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311 | emulations for it.) |
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312 | |
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313 | Here is an example of using C<NVtime> from C: |
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314 | |
315 | double (*myNVtime)(); |
316 | SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0); |
317 | if (!svp) croak("Time::HiRes is required"); |
318 | if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer"); |
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319 | myNVtime = INT2PTR(double(*)(), SvIV(*svp)); |
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320 | printf("The current time is: %f\n", (*myNVtime)()); |
321 | |
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322 | =head1 DIAGNOSTICS |
323 | |
324 | =head2 negative time not invented yet |
325 | |
326 | You tried to use a negative time argument. |
327 | |
328 | =head2 internal error: useconds < 0 (unsigned ... signed ...) |
329 | |
330 | Something went horribly wrong-- the number of microseconds that cannot |
331 | become negative just became negative. Maybe your compiler is broken? |
332 | |
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333 | =head1 CAVEATS |
334 | |
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335 | Notice that the core C<time()> maybe rounding rather than truncating. |
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336 | What this means is that the core C<time()> may be reporting the time |
337 | as one second later than C<gettimeofday()> and C<Time::HiRes::time()>. |
338 | |
339 | Adjusting the system clock (either manually or by services like ntp) |
340 | may cause problems, especially for long running programs that assume |
341 | a monotonously increasing time (note that all platforms do not adjust |
342 | time as gracefully as UNIX ntp does). For example in Win32 (and derived |
343 | platforms like Cygwin and MinGW) the Time::HiRes::time() may temporarily |
344 | drift off from the system clock (and the original time()) by up to 0.5 |
345 | seconds. Time::HiRes will notice this eventually and recalibrate. |
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346 | |
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347 | =head1 AUTHORS |
348 | |
349 | D. Wegscheid <wegscd@whirlpool.com> |
350 | R. Schertler <roderick@argon.org> |
351 | J. Hietaniemi <jhi@iki.fi> |
352 | G. Aas <gisle@aas.no> |
353 | |
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354 | =head1 COPYRIGHT AND LICENSE |
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355 | |
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356 | Copyright (c) 1996-2002 Douglas E. Wegscheid. All rights reserved. |
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357 | |
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358 | Copyright (c) 2002,2003,2004 Jarkko Hietaniemi. All rights reserved. |
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359 | |
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360 | This program is free software; you can redistribute it and/or modify |
361 | it under the same terms as Perl itself. |
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362 | |
363 | =cut |