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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 = '1.57'; |
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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 C<usleep>, |
87 | C<ualarm>, C<gettimeofday>, and C<setitimer>/C<getitimer> system calls, in other |
88 | words, high resolution time and timers. See the L</EXAMPLES> section below |
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89 | and the test scripts for usage; see your system documentation for the |
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90 | description of the underlying C<nanosleep> or C<usleep>, C<ualarm>, |
91 | C<gettimeofday>, and C<setitimer>/C<getitimer> calls. |
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92 | |
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93 | If your system lacks C<gettimeofday()> or an emulation of it you don't |
94 | get C<gettimeofday()> or the one-argument form of C<tv_interval()>. If your system lacks all of |
95 | C<nanosleep()>, C<usleep()>, and C<select()>, you don't get |
96 | C<Time::HiRes::usleep()> or C<Time::HiRes::sleep()>. If your system lacks both |
97 | C<ualarm()> and C<setitimer()> you don't get |
98 | C<Time::HiRes::ualarm()> or C<Time::HiRes::alarm()>. |
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99 | |
100 | If you try to import an unimplemented function in the C<use> statement |
101 | it will fail at compile time. |
102 | |
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103 | If your subsecond sleeping is implemented with C<nanosleep()> instead of |
104 | C<usleep()>, you can mix subsecond sleeping with signals since |
105 | C<nanosleep()> does not use signals. This, however is unportable, and you |
106 | should first check for the truth value of C<&Time::HiRes::d_nanosleep> to |
107 | see whether you have nanosleep, and then carefully read your |
108 | C<nanosleep()> C API documentation for any peculiarities. (There is no |
109 | separate interface to call C<nanosleep()>; just use C<Time::HiRes::sleep()> |
110 | or C<Time::HiRes::usleep()> with small enough values.) |
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111 | |
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112 | Unless using C<nanosleep> for mixing sleeping with signals, give |
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113 | some thought to whether Perl is the tool you should be using for work |
114 | requiring nanosecond accuracies. |
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115 | |
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116 | The following functions can be imported from this module. |
117 | No functions are exported by default. |
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118 | |
119 | =over 4 |
120 | |
121 | =item gettimeofday () |
122 | |
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123 | In array context returns a two-element array with the seconds and |
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124 | microseconds since the epoch. In scalar context returns floating |
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125 | seconds like C<Time::HiRes::time()> (see below). |
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126 | |
127 | =item usleep ( $useconds ) |
128 | |
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129 | Sleeps for the number of microseconds specified. Returns the number |
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130 | of microseconds actually slept. Can sleep for more than one second, |
131 | unlike the C<usleep> system call. See also C<Time::HiRes::sleep()> below. |
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132 | |
133 | =item ualarm ( $useconds [, $interval_useconds ] ) |
134 | |
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135 | Issues a C<ualarm> call; the C<$interval_useconds> is optional and |
136 | will be zero if unspecified, resulting in C<alarm>-like behaviour. |
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137 | |
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138 | =item tv_interval |
139 | |
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140 | tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] ) |
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141 | |
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142 | Returns the floating seconds between the two times, which should have |
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143 | been returned by C<gettimeofday()>. If the second argument is omitted, |
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144 | then the current time is used. |
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145 | |
146 | =item time () |
147 | |
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148 | Returns a floating seconds since the epoch. This function can be |
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149 | imported, resulting in a nice drop-in replacement for the C<time> |
150 | provided with core Perl; see the L</EXAMPLES> below. |
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151 | |
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152 | B<NOTE 1>: This higher resolution timer can return values either less |
153 | or more than the core C<time()>, depending on whether your platform |
154 | rounds the higher resolution timer values up, down, or to the nearest second |
155 | to get the core C<time()>, but naturally the difference should be never |
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156 | more than half a second. |
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157 | |
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158 | B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT, when |
159 | the C<time()> seconds since epoch rolled over to 1_000_000_000, the |
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160 | default floating point format of Perl and the seconds since epoch have |
161 | conspired to produce an apparent bug: if you print the value of |
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162 | C<Time::HiRes::time()> you seem to be getting only five decimals, not six |
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163 | as promised (microseconds). Not to worry, the microseconds are there |
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164 | (assuming your platform supports such granularity in first place). |
165 | What is going on is that the default floating point format of Perl |
166 | only outputs 15 digits. In this case that means ten digits before the |
167 | decimal separator and five after. To see the microseconds you can use |
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168 | either C<printf>/C<sprintf> with C<"%.6f">, or the C<gettimeofday()> function in |
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169 | list context, which will give you the seconds and microseconds as two |
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170 | separate values. |
171 | |
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172 | =item sleep ( $floating_seconds ) |
173 | |
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174 | Sleeps for the specified amount of seconds. Returns the number of |
175 | seconds actually slept (a floating point value). This function can be |
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176 | imported, resulting in a nice drop-in replacement for the C<sleep> |
177 | provided with perl, see the L</EXAMPLES> below. |
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178 | |
179 | =item alarm ( $floating_seconds [, $interval_floating_seconds ] ) |
180 | |
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181 | The C<SIGALRM> signal is sent after the specified number of seconds. |
182 | Implemented using C<ualarm()>. The C<$interval_floating_seconds> argument |
183 | is optional and will be zero if unspecified, resulting in C<alarm()>-like |
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184 | behaviour. This function can be imported, resulting in a nice drop-in |
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185 | replacement for the C<alarm> provided with perl, see the L</EXAMPLES> below. |
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186 | |
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187 | B<NOTE 1>: With some operating system and Perl release combinations |
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188 | C<SIGALRM> restarts C<select()>, instead of interuping it. |
189 | This means that an C<alarm()> followed by a C<select()> |
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190 | may together take the sum of the times specified for the the |
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191 | C<alarm()> and the C<select()>, not just the time of the C<alarm()>. |
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192 | |
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193 | =item setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] ) |
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194 | |
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195 | Start up an interval timer: after a certain time, a signal arrives, |
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196 | and more signals may keep arriving at certain intervals. To disable a |
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197 | timer, use C<$floating_seconds> of zero. If the C<$interval_floating_seconds> |
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198 | is set to zero (or unspecified), the timer is disabled B<after> the |
199 | next delivered signal. |
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200 | |
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201 | Use of interval timers may interfere with C<alarm()>, C<sleep()>, |
202 | and C<usleep()>. In standard-speak the "interaction is unspecified", |
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203 | which means that I<anything> may happen: it may work, it may not. |
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204 | |
205 | In scalar context, the remaining time in the timer is returned. |
206 | |
207 | In list context, both the remaining time and the interval are returned. |
208 | |
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209 | There are usually three or four interval timers available: the C<$which> |
210 | can be C<ITIMER_REAL>, C<ITIMER_VIRTUAL>, C<ITIMER_PROF>, or C<ITIMER_REALPROF>. |
211 | Note that which ones are available depends: true UNIX platforms usually |
212 | have the first three, but (for example) Win32 and Cygwin have only |
213 | C<ITIMER_REAL>, and only Solaris seems to have C<ITIMER_REALPROF> (which is |
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214 | used to profile multithreaded programs). |
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215 | |
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216 | C<ITIMER_REAL> results in C<alarm()>-like behavior. Time is counted in |
217 | I<real time>; that is, wallclock time. C<SIGALRM> is delivered when |
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218 | the timer expires. |
219 | |
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220 | C<ITIMER_VIRTUAL> counts time in (process) I<virtual time>; that is, only |
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221 | when the process is running. In multiprocessor/user/CPU systems this |
222 | may be more or less than real or wallclock time. (This time is also |
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223 | known as the I<user time>.) C<SIGVTALRM> is delivered when the timer expires. |
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224 | |
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225 | C<ITIMER_PROF> counts time when either the process virtual time or when |
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226 | the operating system is running on behalf of the process (such as I/O). |
227 | (This time is also known as the I<system time>.) (The sum of user |
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228 | time and system time is known as the I<CPU time>.) C<SIGPROF> is |
229 | delivered when the timer expires. C<SIGPROF> can interrupt system calls. |
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230 | |
231 | The semantics of interval timers for multithreaded programs are |
232 | system-specific, and some systems may support additional interval |
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233 | timers. See your C<setitimer()> documentation. |
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234 | |
235 | =item getitimer ( $which ) |
236 | |
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237 | Return the remaining time in the interval timer specified by C<$which>. |
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238 | |
239 | In scalar context, the remaining time is returned. |
240 | |
241 | In list context, both the remaining time and the interval are returned. |
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242 | The interval is always what you put in using C<setitimer()>. |
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243 | |
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244 | =back |
245 | |
246 | =head1 EXAMPLES |
247 | |
248 | use Time::HiRes qw(usleep ualarm gettimeofday tv_interval); |
249 | |
250 | $microseconds = 750_000; |
251 | usleep $microseconds; |
252 | |
253 | # signal alarm in 2.5s & every .1s thereafter |
254 | ualarm 2_500_000, 100_000; |
255 | |
256 | # get seconds and microseconds since the epoch |
257 | ($s, $usec) = gettimeofday; |
258 | |
259 | # measure elapsed time |
260 | # (could also do by subtracting 2 gettimeofday return values) |
261 | $t0 = [gettimeofday]; |
262 | # do bunch of stuff here |
263 | $t1 = [gettimeofday]; |
264 | # do more stuff here |
265 | $t0_t1 = tv_interval $t0, $t1; |
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266 | |
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267 | $elapsed = tv_interval ($t0, [gettimeofday]); |
268 | $elapsed = tv_interval ($t0); # equivalent code |
269 | |
270 | # |
271 | # replacements for time, alarm and sleep that know about |
272 | # floating seconds |
273 | # |
274 | use Time::HiRes; |
275 | $now_fractions = Time::HiRes::time; |
276 | Time::HiRes::sleep (2.5); |
277 | Time::HiRes::alarm (10.6666666); |
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278 | |
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279 | use Time::HiRes qw ( time alarm sleep ); |
280 | $now_fractions = time; |
281 | sleep (2.5); |
282 | alarm (10.6666666); |
283 | |
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284 | # Arm an interval timer to go off first at 10 seconds and |
285 | # after that every 2.5 seconds, in process virtual time |
286 | |
287 | use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time ); |
288 | |
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289 | $SIG{VTALRM} = sub { print time, "\n" }; |
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290 | setitimer(ITIMER_VIRTUAL, 10, 2.5); |
291 | |
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292 | =head1 C API |
293 | |
294 | In addition to the perl API described above, a C API is available for |
295 | extension writers. The following C functions are available in the |
296 | modglobal hash: |
297 | |
298 | name C prototype |
299 | --------------- ---------------------- |
300 | Time::NVtime double (*)() |
301 | Time::U2time void (*)(UV ret[2]) |
302 | |
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303 | Both functions return equivalent information (like C<gettimeofday>) |
304 | but with different representations. The names C<NVtime> and C<U2time> |
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305 | were selected mainly because they are operating system independent. |
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306 | (C<gettimeofday> is Unix-centric, though some platforms like VMS have |
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307 | emulations for it.) |
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308 | |
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309 | Here is an example of using C<NVtime> from C: |
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310 | |
311 | double (*myNVtime)(); |
312 | SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0); |
313 | if (!svp) croak("Time::HiRes is required"); |
314 | if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer"); |
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315 | myNVtime = INT2PTR(double(*)(), SvIV(*svp)); |
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316 | printf("The current time is: %f\n", (*myNVtime)()); |
317 | |
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318 | =head1 DIAGNOSTICS |
319 | |
320 | =head2 negative time not invented yet |
321 | |
322 | You tried to use a negative time argument. |
323 | |
324 | =head2 internal error: useconds < 0 (unsigned ... signed ...) |
325 | |
326 | Something went horribly wrong-- the number of microseconds that cannot |
327 | become negative just became negative. Maybe your compiler is broken? |
328 | |
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329 | =head1 CAVEATS |
330 | |
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331 | Notice that the core C<time()> maybe rounding rather than truncating. |
332 | What this means is that the core C<time()> may be reporting the time as one second |
333 | later than C<gettimeofday()> and C<Time::HiRes::time()>. |
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334 | |
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335 | =head1 AUTHORS |
336 | |
337 | D. Wegscheid <wegscd@whirlpool.com> |
338 | R. Schertler <roderick@argon.org> |
339 | J. Hietaniemi <jhi@iki.fi> |
340 | G. Aas <gisle@aas.no> |
341 | |
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342 | =head1 COPYRIGHT AND LICENSE |
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343 | |
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344 | Copyright (c) 1996-2002 Douglas E. Wegscheid. All rights reserved. |
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345 | |
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346 | Copyright (c) 2002,2003,2004 Jarkko Hietaniemi. All rights reserved. |
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347 | |
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348 | This program is free software; you can redistribute it and/or modify |
349 | it under the same terms as Perl itself. |
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350 | |
351 | =cut |