… | |
… | |
411 | make libev check for a fork in each iteration by enabling this flag. |
411 | make libev check for a fork in each iteration by enabling this flag. |
412 | |
412 | |
413 | This works by calling C<getpid ()> on every iteration of the loop, |
413 | This works by calling C<getpid ()> on every iteration of the loop, |
414 | and thus this might slow down your event loop if you do a lot of loop |
414 | and thus this might slow down your event loop if you do a lot of loop |
415 | iterations and little real work, but is usually not noticeable (on my |
415 | iterations and little real work, but is usually not noticeable (on my |
416 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
416 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn |
417 | without a system call and thus I<very> fast, but my GNU/Linux system also has |
417 | sequence without a system call and thus I<very> fast, but my GNU/Linux |
418 | C<pthread_atfork> which is even faster). |
418 | system also has C<pthread_atfork> which is even faster). (Update: glibc |
|
|
419 | versions 2.25 apparently removed the C<getpid> optimisation again). |
419 | |
420 | |
420 | The big advantage of this flag is that you can forget about fork (and |
421 | The big advantage of this flag is that you can forget about fork (and |
421 | forget about forgetting to tell libev about forking, although you still |
422 | forget about forgetting to tell libev about forking, although you still |
422 | have to ignore C<SIGPIPE>) when you use this flag. |
423 | have to ignore C<SIGPIPE>) when you use this flag. |
423 | |
424 | |
… | |
… | |
2113 | |
2114 | |
2114 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
2115 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
2115 | |
2116 | |
2116 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
2117 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
2117 | |
2118 | |
2118 | Configure the timer to trigger after C<after> seconds. If C<repeat> |
2119 | Configure the timer to trigger after C<after> seconds (fractional and |
2119 | is C<0.>, then it will automatically be stopped once the timeout is |
2120 | negative values are supported). If C<repeat> is C<0.>, then it will |
2120 | reached. If it is positive, then the timer will automatically be |
2121 | automatically be stopped once the timeout is reached. If it is positive, |
2121 | configured to trigger again C<repeat> seconds later, again, and again, |
2122 | then the timer will automatically be configured to trigger again C<repeat> |
2122 | until stopped manually. |
2123 | seconds later, again, and again, until stopped manually. |
2123 | |
2124 | |
2124 | The timer itself will do a best-effort at avoiding drift, that is, if |
2125 | The timer itself will do a best-effort at avoiding drift, that is, if |
2125 | you configure a timer to trigger every 10 seconds, then it will normally |
2126 | you configure a timer to trigger every 10 seconds, then it will normally |
2126 | trigger at exactly 10 second intervals. If, however, your program cannot |
2127 | trigger at exactly 10 second intervals. If, however, your program cannot |
2127 | keep up with the timer (because it takes longer than those 10 seconds to |
2128 | keep up with the timer (because it takes longer than those 10 seconds to |
… | |
… | |
2224 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
2225 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
2225 | it, as it uses a relative timeout). |
2226 | it, as it uses a relative timeout). |
2226 | |
2227 | |
2227 | C<ev_periodic> watchers can also be used to implement vastly more complex |
2228 | C<ev_periodic> watchers can also be used to implement vastly more complex |
2228 | timers, such as triggering an event on each "midnight, local time", or |
2229 | timers, such as triggering an event on each "midnight, local time", or |
2229 | other complicated rules. This cannot be done with C<ev_timer> watchers, as |
2230 | other complicated rules. This cannot easily be done with C<ev_timer> |
2230 | those cannot react to time jumps. |
2231 | watchers, as those cannot react to time jumps. |
2231 | |
2232 | |
2232 | As with timers, the callback is guaranteed to be invoked only when the |
2233 | As with timers, the callback is guaranteed to be invoked only when the |
2233 | point in time where it is supposed to trigger has passed. If multiple |
2234 | point in time where it is supposed to trigger has passed. If multiple |
2234 | timers become ready during the same loop iteration then the ones with |
2235 | timers become ready during the same loop iteration then the ones with |
2235 | earlier time-out values are invoked before ones with later time-out values |
2236 | earlier time-out values are invoked before ones with later time-out values |
… | |
… | |
2321 | |
2322 | |
2322 | NOTE: I<< This callback must always return a time that is higher than or |
2323 | NOTE: I<< This callback must always return a time that is higher than or |
2323 | equal to the passed C<now> value >>. |
2324 | equal to the passed C<now> value >>. |
2324 | |
2325 | |
2325 | This can be used to create very complex timers, such as a timer that |
2326 | This can be used to create very complex timers, such as a timer that |
2326 | triggers on "next midnight, local time". To do this, you would calculate the |
2327 | triggers on "next midnight, local time". To do this, you would calculate |
2327 | next midnight after C<now> and return the timestamp value for this. How |
2328 | the next midnight after C<now> and return the timestamp value for |
2328 | you do this is, again, up to you (but it is not trivial, which is the main |
2329 | this. Here is a (completely untested, no error checking) example on how to |
2329 | reason I omitted it as an example). |
2330 | do this: |
|
|
2331 | |
|
|
2332 | #include <time.h> |
|
|
2333 | |
|
|
2334 | static ev_tstamp |
|
|
2335 | my_rescheduler (ev_periodic *w, ev_tstamp now) |
|
|
2336 | { |
|
|
2337 | time_t tnow = (time_t)now; |
|
|
2338 | struct tm tm; |
|
|
2339 | localtime_r (&tnow, &tm); |
|
|
2340 | |
|
|
2341 | tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day |
|
|
2342 | ++tm.tm_mday; // midnight next day |
|
|
2343 | |
|
|
2344 | return mktime (&tm); |
|
|
2345 | } |
|
|
2346 | |
|
|
2347 | Note: this code might run into trouble on days that have more then two |
|
|
2348 | midnights (beginning and end). |
2330 | |
2349 | |
2331 | =back |
2350 | =back |
2332 | |
2351 | |
2333 | =item ev_periodic_again (loop, ev_periodic *) |
2352 | =item ev_periodic_again (loop, ev_periodic *) |
2334 | |
2353 | |
… | |
… | |
3517 | |
3536 | |
3518 | There are some other functions of possible interest. Described. Here. Now. |
3537 | There are some other functions of possible interest. Described. Here. Now. |
3519 | |
3538 | |
3520 | =over 4 |
3539 | =over 4 |
3521 | |
3540 | |
3522 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
3541 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg) |
3523 | |
3542 | |
3524 | This function combines a simple timer and an I/O watcher, calls your |
3543 | This function combines a simple timer and an I/O watcher, calls your |
3525 | callback on whichever event happens first and automatically stops both |
3544 | callback on whichever event happens first and automatically stops both |
3526 | watchers. This is useful if you want to wait for a single event on an fd |
3545 | watchers. This is useful if you want to wait for a single event on an fd |
3527 | or timeout without having to allocate/configure/start/stop/free one or |
3546 | or timeout without having to allocate/configure/start/stop/free one or |