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126 | .IX Title "LIBEV 3" |
126 | .IX Title "LIBEV 3" |
127 | .TH LIBEV 3 "2011-01-31" "libev-4.04" "libev - high performance full featured event loop" |
127 | .TH LIBEV 3 "2013-06-07" "libev-4.15" "libev - high performance full featured event loop" |
128 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
128 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
129 | .\" way too many mistakes in technical documents. |
129 | .\" way too many mistakes in technical documents. |
130 | .if n .ad l |
130 | .if n .ad l |
131 | .nh |
131 | .nh |
132 | .SH "NAME" |
132 | .SH "NAME" |
… | |
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244 | loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, \f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and |
244 | loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, \f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and |
245 | \&\f(CW\*(C`ev_check\*(C'\fR watchers) as well as file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even |
245 | \&\f(CW\*(C`ev_check\*(C'\fR watchers) as well as file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even |
246 | limited support for fork events (\f(CW\*(C`ev_fork\*(C'\fR). |
246 | limited support for fork events (\f(CW\*(C`ev_fork\*(C'\fR). |
247 | .PP |
247 | .PP |
248 | It also is quite fast (see this |
248 | It also is quite fast (see this |
249 | <benchmark> comparing it to libevent |
249 | benchmark <http://libev.schmorp.de/bench.html> comparing it to libevent |
250 | for example). |
250 | for example). |
251 | .SS "\s-1CONVENTIONS\s0" |
251 | .SS "\s-1CONVENTIONS\s0" |
252 | .IX Subsection "CONVENTIONS" |
252 | .IX Subsection "CONVENTIONS" |
253 | Libev is very configurable. In this manual the default (and most common) |
253 | Libev is very configurable. In this manual the default (and most common) |
254 | configuration will be described, which supports multiple event loops. For |
254 | configuration will be described, which supports multiple event loops. For |
… | |
… | |
294 | .IP "ev_tstamp ev_time ()" 4 |
294 | .IP "ev_tstamp ev_time ()" 4 |
295 | .IX Item "ev_tstamp ev_time ()" |
295 | .IX Item "ev_tstamp ev_time ()" |
296 | Returns the current time as libev would use it. Please note that the |
296 | Returns the current time as libev would use it. Please note that the |
297 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
297 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
298 | you actually want to know. Also interesting is the combination of |
298 | you actually want to know. Also interesting is the combination of |
299 | \&\f(CW\*(C`ev_update_now\*(C'\fR and \f(CW\*(C`ev_now\*(C'\fR. |
299 | \&\f(CW\*(C`ev_now_update\*(C'\fR and \f(CW\*(C`ev_now\*(C'\fR. |
300 | .IP "ev_sleep (ev_tstamp interval)" 4 |
300 | .IP "ev_sleep (ev_tstamp interval)" 4 |
301 | .IX Item "ev_sleep (ev_tstamp interval)" |
301 | .IX Item "ev_sleep (ev_tstamp interval)" |
302 | Sleep for the given interval: The current thread will be blocked until |
302 | Sleep for the given interval: The current thread will be blocked |
303 | either it is interrupted or the given time interval has passed. Basically |
303 | until either it is interrupted or the given time interval has |
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|
304 | passed (approximately \- it might return a bit earlier even if not |
|
|
305 | interrupted). Returns immediately if \f(CW\*(C`interval <= 0\*(C'\fR. |
|
|
306 | .Sp |
304 | this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
307 | Basically this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
|
|
308 | .Sp |
|
|
309 | The range of the \f(CW\*(C`interval\*(C'\fR is limited \- libev only guarantees to work |
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|
310 | with sleep times of up to one day (\f(CW\*(C`interval <= 86400\*(C'\fR). |
305 | .IP "int ev_version_major ()" 4 |
311 | .IP "int ev_version_major ()" 4 |
306 | .IX Item "int ev_version_major ()" |
312 | .IX Item "int ev_version_major ()" |
307 | .PD 0 |
313 | .PD 0 |
308 | .IP "int ev_version_minor ()" 4 |
314 | .IP "int ev_version_minor ()" 4 |
309 | .IX Item "int ev_version_minor ()" |
315 | .IX Item "int ev_version_minor ()" |
… | |
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361 | current system. To find which embeddable backends might be supported on |
367 | current system. To find which embeddable backends might be supported on |
362 | the current system, you would need to look at \f(CW\*(C`ev_embeddable_backends () |
368 | the current system, you would need to look at \f(CW\*(C`ev_embeddable_backends () |
363 | & ev_supported_backends ()\*(C'\fR, likewise for recommended ones. |
369 | & ev_supported_backends ()\*(C'\fR, likewise for recommended ones. |
364 | .Sp |
370 | .Sp |
365 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
371 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
366 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 |
372 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size) throw ())" 4 |
367 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" |
373 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size) throw ())" |
368 | Sets the allocation function to use (the prototype is similar \- the |
374 | Sets the allocation function to use (the prototype is similar \- the |
369 | semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is |
375 | semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is |
370 | used to allocate and free memory (no surprises here). If it returns zero |
376 | used to allocate and free memory (no surprises here). If it returns zero |
371 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
377 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
372 | or take some potentially destructive action. |
378 | or take some potentially destructive action. |
… | |
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398 | \& } |
404 | \& } |
399 | \& |
405 | \& |
400 | \& ... |
406 | \& ... |
401 | \& ev_set_allocator (persistent_realloc); |
407 | \& ev_set_allocator (persistent_realloc); |
402 | .Ve |
408 | .Ve |
403 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg))" 4 |
409 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg) throw ())" 4 |
404 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg))" |
410 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg) throw ())" |
405 | Set the callback function to call on a retryable system call error (such |
411 | Set the callback function to call on a retryable system call error (such |
406 | as failed select, poll, epoll_wait). The message is a printable string |
412 | as failed select, poll, epoll_wait). The message is a printable string |
407 | indicating the system call or subsystem causing the problem. If this |
413 | indicating the system call or subsystem causing the problem. If this |
408 | callback is set, then libev will expect it to remedy the situation, no |
414 | callback is set, then libev will expect it to remedy the situation, no |
409 | matter what, when it returns. That is, libev will generally retry the |
415 | matter what, when it returns. That is, libev will generally retry the |
… | |
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508 | .IX Item "EVFLAG_NOENV" |
514 | .IX Item "EVFLAG_NOENV" |
509 | If this flag bit is or'ed into the flag value (or the program runs setuid |
515 | If this flag bit is or'ed into the flag value (or the program runs setuid |
510 | or setgid) then libev will \fInot\fR look at the environment variable |
516 | or setgid) then libev will \fInot\fR look at the environment variable |
511 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
517 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
512 | override the flags completely if it is found in the environment. This is |
518 | override the flags completely if it is found in the environment. This is |
513 | useful to try out specific backends to test their performance, or to work |
519 | useful to try out specific backends to test their performance, to work |
514 | around bugs. |
520 | around bugs, or to make libev threadsafe (accessing environment variables |
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|
521 | cannot be done in a threadsafe way, but usually it works if no other |
|
|
522 | thread modifies them). |
515 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
523 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
516 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
524 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
517 | .IX Item "EVFLAG_FORKCHECK" |
525 | .IX Item "EVFLAG_FORKCHECK" |
518 | Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also |
526 | Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also |
519 | make libev check for a fork in each iteration by enabling this flag. |
527 | make libev check for a fork in each iteration by enabling this flag. |
… | |
… | |
553 | example) that can't properly initialise their signal masks. |
561 | example) that can't properly initialise their signal masks. |
554 | .ie n .IP """EVFLAG_NOSIGMASK""" 4 |
562 | .ie n .IP """EVFLAG_NOSIGMASK""" 4 |
555 | .el .IP "\f(CWEVFLAG_NOSIGMASK\fR" 4 |
563 | .el .IP "\f(CWEVFLAG_NOSIGMASK\fR" 4 |
556 | .IX Item "EVFLAG_NOSIGMASK" |
564 | .IX Item "EVFLAG_NOSIGMASK" |
557 | When this flag is specified, then libev will avoid to modify the signal |
565 | When this flag is specified, then libev will avoid to modify the signal |
558 | mask. Specifically, this means you ahve to make sure signals are unblocked |
566 | mask. Specifically, this means you have to make sure signals are unblocked |
559 | when you want to receive them. |
567 | when you want to receive them. |
560 | .Sp |
568 | .Sp |
561 | This behaviour is useful when you want to do your own signal handling, or |
569 | This behaviour is useful when you want to do your own signal handling, or |
562 | want to handle signals only in specific threads and want to avoid libev |
570 | want to handle signals only in specific threads and want to avoid libev |
563 | unblocking the signals. |
571 | unblocking the signals. |
… | |
… | |
601 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
609 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
602 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
610 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
603 | Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
611 | Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
604 | kernels). |
612 | kernels). |
605 | .Sp |
613 | .Sp |
606 | For few fds, this backend is a bit little slower than poll and select, |
614 | For few fds, this backend is a bit little slower than poll and select, but |
607 | but it scales phenomenally better. While poll and select usually scale |
615 | it scales phenomenally better. While poll and select usually scale like |
608 | like O(total_fds) where n is the total number of fds (or the highest fd), |
616 | O(total_fds) where total_fds is the total number of fds (or the highest |
609 | epoll scales either O(1) or O(active_fds). |
617 | fd), epoll scales either O(1) or O(active_fds). |
610 | .Sp |
618 | .Sp |
611 | The epoll mechanism deserves honorable mention as the most misdesigned |
619 | The epoll mechanism deserves honorable mention as the most misdesigned |
612 | of the more advanced event mechanisms: mere annoyances include silently |
620 | of the more advanced event mechanisms: mere annoyances include silently |
613 | dropping file descriptors, requiring a system call per change per file |
621 | dropping file descriptors, requiring a system call per change per file |
614 | descriptor (and unnecessary guessing of parameters), problems with dup, |
622 | descriptor (and unnecessary guessing of parameters), problems with dup, |
… | |
… | |
617 | 0.1ms) and so on. The biggest issue is fork races, however \- if a program |
625 | 0.1ms) and so on. The biggest issue is fork races, however \- if a program |
618 | forks then \fIboth\fR parent and child process have to recreate the epoll |
626 | forks then \fIboth\fR parent and child process have to recreate the epoll |
619 | set, which can take considerable time (one syscall per file descriptor) |
627 | set, which can take considerable time (one syscall per file descriptor) |
620 | and is of course hard to detect. |
628 | and is of course hard to detect. |
621 | .Sp |
629 | .Sp |
622 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, but |
630 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, |
623 | of course \fIdoesn't\fR, and epoll just loves to report events for totally |
631 | but of course \fIdoesn't\fR, and epoll just loves to report events for |
624 | \&\fIdifferent\fR file descriptors (even already closed ones, so one cannot |
632 | totally \fIdifferent\fR file descriptors (even already closed ones, so |
625 | even remove them from the set) than registered in the set (especially |
633 | one cannot even remove them from the set) than registered in the set |
626 | on \s-1SMP\s0 systems). Libev tries to counter these spurious notifications by |
634 | (especially on \s-1SMP\s0 systems). Libev tries to counter these spurious |
627 | employing an additional generation counter and comparing that against the |
635 | notifications by employing an additional generation counter and comparing |
628 | events to filter out spurious ones, recreating the set when required. Last |
636 | that against the events to filter out spurious ones, recreating the set |
|
|
637 | when required. Epoll also erroneously rounds down timeouts, but gives you |
|
|
638 | no way to know when and by how much, so sometimes you have to busy-wait |
|
|
639 | because epoll returns immediately despite a nonzero timeout. And last |
629 | not least, it also refuses to work with some file descriptors which work |
640 | not least, it also refuses to work with some file descriptors which work |
630 | perfectly fine with \f(CW\*(C`select\*(C'\fR (files, many character devices...). |
641 | perfectly fine with \f(CW\*(C`select\*(C'\fR (files, many character devices...). |
631 | .Sp |
642 | .Sp |
632 | Epoll is truly the train wreck analog among event poll mechanisms, |
643 | Epoll is truly the train wreck among event poll mechanisms, a frankenpoll, |
633 | a frankenpoll, cobbled together in a hurry, no thought to design or |
644 | cobbled together in a hurry, no thought to design or interaction with |
634 | interaction with others. |
645 | others. Oh, the pain, will it ever stop... |
635 | .Sp |
646 | .Sp |
636 | While stopping, setting and starting an I/O watcher in the same iteration |
647 | While stopping, setting and starting an I/O watcher in the same iteration |
637 | will result in some caching, there is still a system call per such |
648 | will result in some caching, there is still a system call per such |
638 | incident (because the same \fIfile descriptor\fR could point to a different |
649 | incident (because the same \fIfile descriptor\fR could point to a different |
639 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
650 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
… | |
… | |
676 | .Sp |
687 | .Sp |
677 | It scales in the same way as the epoll backend, but the interface to the |
688 | It scales in the same way as the epoll backend, but the interface to the |
678 | kernel is more efficient (which says nothing about its actual speed, of |
689 | kernel is more efficient (which says nothing about its actual speed, of |
679 | course). While stopping, setting and starting an I/O watcher does never |
690 | course). While stopping, setting and starting an I/O watcher does never |
680 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
691 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
681 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (but |
692 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (you |
682 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
693 | might have to leak fd's on fork, but it's more sane than epoll) and it |
683 | cases |
694 | drops fds silently in similarly hard-to-detect cases. |
684 | .Sp |
695 | .Sp |
685 | This backend usually performs well under most conditions. |
696 | This backend usually performs well under most conditions. |
686 | .Sp |
697 | .Sp |
687 | While nominally embeddable in other event loops, this doesn't work |
698 | While nominally embeddable in other event loops, this doesn't work |
688 | everywhere, so you might need to test for this. And since it is broken |
699 | everywhere, so you might need to test for this. And since it is broken |
… | |
… | |
717 | among the OS-specific backends (I vastly prefer correctness over speed |
728 | among the OS-specific backends (I vastly prefer correctness over speed |
718 | hacks). |
729 | hacks). |
719 | .Sp |
730 | .Sp |
720 | On the negative side, the interface is \fIbizarre\fR \- so bizarre that |
731 | On the negative side, the interface is \fIbizarre\fR \- so bizarre that |
721 | even sun itself gets it wrong in their code examples: The event polling |
732 | even sun itself gets it wrong in their code examples: The event polling |
722 | function sometimes returning events to the caller even though an error |
733 | function sometimes returns events to the caller even though an error |
723 | occurred, but with no indication whether it has done so or not (yes, it's |
734 | occurred, but with no indication whether it has done so or not (yes, it's |
724 | even documented that way) \- deadly for edge-triggered interfaces where |
735 | even documented that way) \- deadly for edge-triggered interfaces where you |
725 | you absolutely have to know whether an event occurred or not because you |
736 | absolutely have to know whether an event occurred or not because you have |
726 | have to re-arm the watcher. |
737 | to re-arm the watcher. |
727 | .Sp |
738 | .Sp |
728 | Fortunately libev seems to be able to work around these idiocies. |
739 | Fortunately libev seems to be able to work around these idiocies. |
729 | .Sp |
740 | .Sp |
730 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
741 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
731 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
742 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
… | |
… | |
900 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
911 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
901 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
912 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
902 | .Sp |
913 | .Sp |
903 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
914 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
904 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
915 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
905 | .IP "ev_run (loop, int flags)" 4 |
916 | .IP "bool ev_run (loop, int flags)" 4 |
906 | .IX Item "ev_run (loop, int flags)" |
917 | .IX Item "bool ev_run (loop, int flags)" |
907 | Finally, this is it, the event handler. This function usually is called |
918 | Finally, this is it, the event handler. This function usually is called |
908 | after you have initialised all your watchers and you want to start |
919 | after you have initialised all your watchers and you want to start |
909 | handling events. It will ask the operating system for any new events, call |
920 | handling events. It will ask the operating system for any new events, call |
910 | the watcher callbacks, an then repeat the whole process indefinitely: This |
921 | the watcher callbacks, and then repeat the whole process indefinitely: This |
911 | is why event loops are called \fIloops\fR. |
922 | is why event loops are called \fIloops\fR. |
912 | .Sp |
923 | .Sp |
913 | If the flags argument is specified as \f(CW0\fR, it will keep handling events |
924 | If the flags argument is specified as \f(CW0\fR, it will keep handling events |
914 | until either no event watchers are active anymore or \f(CW\*(C`ev_break\*(C'\fR was |
925 | until either no event watchers are active anymore or \f(CW\*(C`ev_break\*(C'\fR was |
915 | called. |
926 | called. |
|
|
927 | .Sp |
|
|
928 | The return value is false if there are no more active watchers (which |
|
|
929 | usually means \*(L"all jobs done\*(R" or \*(L"deadlock\*(R"), and true in all other cases |
|
|
930 | (which usually means " you should call \f(CW\*(C`ev_run\*(C'\fR again"). |
916 | .Sp |
931 | .Sp |
917 | Please note that an explicit \f(CW\*(C`ev_break\*(C'\fR is usually better than |
932 | Please note that an explicit \f(CW\*(C`ev_break\*(C'\fR is usually better than |
918 | relying on all watchers to be stopped when deciding when a program has |
933 | relying on all watchers to be stopped when deciding when a program has |
919 | finished (especially in interactive programs), but having a program |
934 | finished (especially in interactive programs), but having a program |
920 | that automatically loops as long as it has to and no longer by virtue |
935 | that automatically loops as long as it has to and no longer by virtue |
921 | of relying on its watchers stopping correctly, that is truly a thing of |
936 | of relying on its watchers stopping correctly, that is truly a thing of |
922 | beauty. |
937 | beauty. |
923 | .Sp |
938 | .Sp |
924 | This function is also \fImostly\fR exception-safe \- you can break out of |
939 | This function is \fImostly\fR exception-safe \- you can break out of a |
925 | a \f(CW\*(C`ev_run\*(C'\fR call by calling \f(CW\*(C`longjmp\*(C'\fR in a callback, throwing a \*(C+ |
940 | \&\f(CW\*(C`ev_run\*(C'\fR call by calling \f(CW\*(C`longjmp\*(C'\fR in a callback, throwing a \*(C+ |
926 | exception and so on. This does not decrement the \f(CW\*(C`ev_depth\*(C'\fR value, nor |
941 | exception and so on. This does not decrement the \f(CW\*(C`ev_depth\*(C'\fR value, nor |
927 | will it clear any outstanding \f(CW\*(C`EVBREAK_ONE\*(C'\fR breaks. |
942 | will it clear any outstanding \f(CW\*(C`EVBREAK_ONE\*(C'\fR breaks. |
928 | .Sp |
943 | .Sp |
929 | A flags value of \f(CW\*(C`EVRUN_NOWAIT\*(C'\fR will look for new events, will handle |
944 | A flags value of \f(CW\*(C`EVRUN_NOWAIT\*(C'\fR will look for new events, will handle |
930 | those events and any already outstanding ones, but will not wait and |
945 | those events and any already outstanding ones, but will not wait and |
… | |
… | |
942 | This is useful if you are waiting for some external event in conjunction |
957 | This is useful if you are waiting for some external event in conjunction |
943 | with something not expressible using other libev watchers (i.e. "roll your |
958 | with something not expressible using other libev watchers (i.e. "roll your |
944 | own \f(CW\*(C`ev_run\*(C'\fR"). However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
959 | own \f(CW\*(C`ev_run\*(C'\fR"). However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
945 | usually a better approach for this kind of thing. |
960 | usually a better approach for this kind of thing. |
946 | .Sp |
961 | .Sp |
947 | Here are the gory details of what \f(CW\*(C`ev_run\*(C'\fR does: |
962 | Here are the gory details of what \f(CW\*(C`ev_run\*(C'\fR does (this is for your |
|
|
963 | understanding, not a guarantee that things will work exactly like this in |
|
|
964 | future versions): |
948 | .Sp |
965 | .Sp |
949 | .Vb 10 |
966 | .Vb 10 |
950 | \& \- Increment loop depth. |
967 | \& \- Increment loop depth. |
951 | \& \- Reset the ev_break status. |
968 | \& \- Reset the ev_break status. |
952 | \& \- Before the first iteration, call any pending watchers. |
969 | \& \- Before the first iteration, call any pending watchers. |
… | |
… | |
1067 | overhead for the actual polling but can deliver many events at once. |
1084 | overhead for the actual polling but can deliver many events at once. |
1068 | .Sp |
1085 | .Sp |
1069 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
1086 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
1070 | time collecting I/O events, so you can handle more events per iteration, |
1087 | time collecting I/O events, so you can handle more events per iteration, |
1071 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
1088 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
1072 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
1089 | \&\f(CW\*(C`ev_timer\*(C'\fR) will not be affected. Setting this to a non-null value will |
1073 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
1090 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
1074 | sleep time ensures that libev will not poll for I/O events more often then |
1091 | sleep time ensures that libev will not poll for I/O events more often then |
1075 | once per this interval, on average. |
1092 | once per this interval, on average (as long as the host time resolution is |
|
|
1093 | good enough). |
1076 | .Sp |
1094 | .Sp |
1077 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
1095 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
1078 | to spend more time collecting timeouts, at the expense of increased |
1096 | to spend more time collecting timeouts, at the expense of increased |
1079 | latency/jitter/inexactness (the watcher callback will be called |
1097 | latency/jitter/inexactness (the watcher callback will be called |
1080 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
1098 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
… | |
… | |
1124 | this callback instead. This is useful, for example, when you want to |
1142 | this callback instead. This is useful, for example, when you want to |
1125 | invoke the actual watchers inside another context (another thread etc.). |
1143 | invoke the actual watchers inside another context (another thread etc.). |
1126 | .Sp |
1144 | .Sp |
1127 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
1145 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
1128 | callback. |
1146 | callback. |
1129 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0), void (*acquire)(\s-1EV_P\s0))" 4 |
1147 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0) throw (), void (*acquire)(\s-1EV_P\s0) throw ())" 4 |
1130 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))" |
1148 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P) throw (), void (*acquire)(EV_P) throw ())" |
1131 | Sometimes you want to share the same loop between multiple threads. This |
1149 | Sometimes you want to share the same loop between multiple threads. This |
1132 | can be done relatively simply by putting mutex_lock/unlock calls around |
1150 | can be done relatively simply by putting mutex_lock/unlock calls around |
1133 | each call to a libev function. |
1151 | each call to a libev function. |
1134 | .Sp |
1152 | .Sp |
1135 | However, \f(CW\*(C`ev_run\*(C'\fR can run an indefinite time, so it is not feasible |
1153 | However, \f(CW\*(C`ev_run\*(C'\fR can run an indefinite time, so it is not feasible |
1136 | to wait for it to return. One way around this is to wake up the event |
1154 | to wait for it to return. One way around this is to wake up the event |
1137 | loop via \f(CW\*(C`ev_break\*(C'\fR and \f(CW\*(C`av_async_send\*(C'\fR, another way is to set these |
1155 | loop via \f(CW\*(C`ev_break\*(C'\fR and \f(CW\*(C`ev_async_send\*(C'\fR, another way is to set these |
1138 | \&\fIrelease\fR and \fIacquire\fR callbacks on the loop. |
1156 | \&\fIrelease\fR and \fIacquire\fR callbacks on the loop. |
1139 | .Sp |
1157 | .Sp |
1140 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
1158 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
1141 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
1159 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
1142 | afterwards. |
1160 | afterwards. |
… | |
… | |
1283 | .PD 0 |
1301 | .PD 0 |
1284 | .ie n .IP """EV_CHECK""" 4 |
1302 | .ie n .IP """EV_CHECK""" 4 |
1285 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1303 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1286 | .IX Item "EV_CHECK" |
1304 | .IX Item "EV_CHECK" |
1287 | .PD |
1305 | .PD |
1288 | All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_run\*(C'\fR starts |
1306 | All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_run\*(C'\fR starts to |
1289 | to gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are invoked just after |
1307 | gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are queued (not invoked) |
1290 | \&\f(CW\*(C`ev_run\*(C'\fR has gathered them, but before it invokes any callbacks for any |
1308 | just after \f(CW\*(C`ev_run\*(C'\fR has gathered them, but before it queues any callbacks |
|
|
1309 | for any received events. That means \f(CW\*(C`ev_prepare\*(C'\fR watchers are the last |
|
|
1310 | watchers invoked before the event loop sleeps or polls for new events, and |
|
|
1311 | \&\f(CW\*(C`ev_check\*(C'\fR watchers will be invoked before any other watchers of the same |
|
|
1312 | or lower priority within an event loop iteration. |
|
|
1313 | .Sp |
1291 | received events. Callbacks of both watcher types can start and stop as |
1314 | Callbacks of both watcher types can start and stop as many watchers as |
1292 | many watchers as they want, and all of them will be taken into account |
1315 | they want, and all of them will be taken into account (for example, a |
1293 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
1316 | \&\f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep \f(CW\*(C`ev_run\*(C'\fR from |
1294 | \&\f(CW\*(C`ev_run\*(C'\fR from blocking). |
1317 | blocking). |
1295 | .ie n .IP """EV_EMBED""" 4 |
1318 | .ie n .IP """EV_EMBED""" 4 |
1296 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1319 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1297 | .IX Item "EV_EMBED" |
1320 | .IX Item "EV_EMBED" |
1298 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1321 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1299 | .ie n .IP """EV_FORK""" 4 |
1322 | .ie n .IP """EV_FORK""" 4 |
… | |
… | |
1420 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
1443 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
1421 | it). |
1444 | it). |
1422 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1445 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1423 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1446 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1424 | Returns the callback currently set on the watcher. |
1447 | Returns the callback currently set on the watcher. |
1425 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1448 | .IP "ev_set_cb (ev_TYPE *watcher, callback)" 4 |
1426 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1449 | .IX Item "ev_set_cb (ev_TYPE *watcher, callback)" |
1427 | Change the callback. You can change the callback at virtually any time |
1450 | Change the callback. You can change the callback at virtually any time |
1428 | (modulo threads). |
1451 | (modulo threads). |
1429 | .IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 |
1452 | .IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 |
1430 | .IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" |
1453 | .IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" |
1431 | .PD 0 |
1454 | .PD 0 |
… | |
… | |
1487 | .IX Subsection "WATCHER STATES" |
1510 | .IX Subsection "WATCHER STATES" |
1488 | There are various watcher states mentioned throughout this manual \- |
1511 | There are various watcher states mentioned throughout this manual \- |
1489 | active, pending and so on. In this section these states and the rules to |
1512 | active, pending and so on. In this section these states and the rules to |
1490 | transition between them will be described in more detail \- and while these |
1513 | transition between them will be described in more detail \- and while these |
1491 | rules might look complicated, they usually do \*(L"the right thing\*(R". |
1514 | rules might look complicated, they usually do \*(L"the right thing\*(R". |
1492 | .IP "initialiased" 4 |
1515 | .IP "initialised" 4 |
1493 | .IX Item "initialiased" |
1516 | .IX Item "initialised" |
1494 | Before a watcher can be registered with the event looop it has to be |
1517 | Before a watcher can be registered with the event loop it has to be |
1495 | initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to |
1518 | initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to |
1496 | \&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. |
1519 | \&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. |
1497 | .Sp |
1520 | .Sp |
1498 | In this state it is simply some block of memory that is suitable for |
1521 | In this state it is simply some block of memory that is suitable for |
1499 | use in an event loop. It can be moved around, freed, reused etc. at |
1522 | use in an event loop. It can be moved around, freed, reused etc. at |
… | |
… | |
1871 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1894 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1872 | monotonic clock option helps a lot here). |
1895 | monotonic clock option helps a lot here). |
1873 | .PP |
1896 | .PP |
1874 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1897 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1875 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1898 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1876 | might introduce a small delay). If multiple timers become ready during the |
1899 | might introduce a small delay, see \*(L"the special problem of being too |
|
|
1900 | early\*(R", below). If multiple timers become ready during the same loop |
1877 | same loop iteration then the ones with earlier time-out values are invoked |
1901 | iteration then the ones with earlier time-out values are invoked before |
1878 | before ones of the same priority with later time-out values (but this is |
1902 | ones of the same priority with later time-out values (but this is no |
1879 | no longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
1903 | longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
1880 | .PP |
1904 | .PP |
1881 | \fIBe smart about timeouts\fR |
1905 | \fIBe smart about timeouts\fR |
1882 | .IX Subsection "Be smart about timeouts" |
1906 | .IX Subsection "Be smart about timeouts" |
1883 | .PP |
1907 | .PP |
1884 | Many real-world problems involve some kind of timeout, usually for error |
1908 | Many real-world problems involve some kind of timeout, usually for error |
… | |
… | |
1966 | .Sp |
1990 | .Sp |
1967 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
1991 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
1968 | but remember the time of last activity, and check for a real timeout only |
1992 | but remember the time of last activity, and check for a real timeout only |
1969 | within the callback: |
1993 | within the callback: |
1970 | .Sp |
1994 | .Sp |
1971 | .Vb 1 |
1995 | .Vb 3 |
|
|
1996 | \& ev_tstamp timeout = 60.; |
1972 | \& ev_tstamp last_activity; // time of last activity |
1997 | \& ev_tstamp last_activity; // time of last activity |
|
|
1998 | \& ev_timer timer; |
1973 | \& |
1999 | \& |
1974 | \& static void |
2000 | \& static void |
1975 | \& callback (EV_P_ ev_timer *w, int revents) |
2001 | \& callback (EV_P_ ev_timer *w, int revents) |
1976 | \& { |
2002 | \& { |
1977 | \& ev_tstamp now = ev_now (EV_A); |
2003 | \& // calculate when the timeout would happen |
1978 | \& ev_tstamp timeout = last_activity + 60.; |
2004 | \& ev_tstamp after = last_activity \- ev_now (EV_A) + timeout; |
1979 | \& |
2005 | \& |
1980 | \& // if last_activity + 60. is older than now, we did time out |
2006 | \& // if negative, it means we the timeout already occurred |
1981 | \& if (timeout < now) |
2007 | \& if (after < 0.) |
1982 | \& { |
2008 | \& { |
1983 | \& // timeout occurred, take action |
2009 | \& // timeout occurred, take action |
1984 | \& } |
2010 | \& } |
1985 | \& else |
2011 | \& else |
1986 | \& { |
2012 | \& { |
1987 | \& // callback was invoked, but there was some activity, re\-arm |
2013 | \& // callback was invoked, but there was some recent |
1988 | \& // the watcher to fire in last_activity + 60, which is |
2014 | \& // activity. simply restart the timer to time out |
1989 | \& // guaranteed to be in the future, so "again" is positive: |
2015 | \& // after "after" seconds, which is the earliest time |
1990 | \& w\->repeat = timeout \- now; |
2016 | \& // the timeout can occur. |
|
|
2017 | \& ev_timer_set (w, after, 0.); |
1991 | \& ev_timer_again (EV_A_ w); |
2018 | \& ev_timer_start (EV_A_ w); |
1992 | \& } |
2019 | \& } |
1993 | \& } |
2020 | \& } |
1994 | .Ve |
2021 | .Ve |
1995 | .Sp |
2022 | .Sp |
1996 | To summarise the callback: first calculate the real timeout (defined |
2023 | To summarise the callback: first calculate in how many seconds the |
1997 | as \*(L"60 seconds after the last activity\*(R"), then check if that time has |
2024 | timeout will occur (by calculating the absolute time when it would occur, |
1998 | been reached, which means something \fIdid\fR, in fact, time out. Otherwise |
2025 | \&\f(CW\*(C`last_activity + timeout\*(C'\fR, and subtracting the current time, \f(CW\*(C`ev_now |
1999 | the callback was invoked too early (\f(CW\*(C`timeout\*(C'\fR is in the future), so |
2026 | (EV_A)\*(C'\fR from that). |
2000 | re-schedule the timer to fire at that future time, to see if maybe we have |
|
|
2001 | a timeout then. |
|
|
2002 | .Sp |
2027 | .Sp |
2003 | Note how \f(CW\*(C`ev_timer_again\*(C'\fR is used, taking advantage of the |
2028 | If this value is negative, then we are already past the timeout, i.e. we |
2004 | \&\f(CW\*(C`ev_timer_again\*(C'\fR optimisation when the timer is already running. |
2029 | timed out, and need to do whatever is needed in this case. |
|
|
2030 | .Sp |
|
|
2031 | Otherwise, we now the earliest time at which the timeout would trigger, |
|
|
2032 | and simply start the timer with this timeout value. |
|
|
2033 | .Sp |
|
|
2034 | In other words, each time the callback is invoked it will check whether |
|
|
2035 | the timeout occurred. If not, it will simply reschedule itself to check |
|
|
2036 | again at the earliest time it could time out. Rinse. Repeat. |
2005 | .Sp |
2037 | .Sp |
2006 | This scheme causes more callback invocations (about one every 60 seconds |
2038 | This scheme causes more callback invocations (about one every 60 seconds |
2007 | minus half the average time between activity), but virtually no calls to |
2039 | minus half the average time between activity), but virtually no calls to |
2008 | libev to change the timeout. |
2040 | libev to change the timeout. |
2009 | .Sp |
2041 | .Sp |
2010 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
2042 | To start the machinery, simply initialise the watcher and set |
2011 | to the current time (meaning we just have some activity :), then call the |
2043 | \&\f(CW\*(C`last_activity\*(C'\fR to the current time (meaning there was some activity just |
2012 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
2044 | now), then call the callback, which will \*(L"do the right thing\*(R" and start |
|
|
2045 | the timer: |
2013 | .Sp |
2046 | .Sp |
2014 | .Vb 3 |
2047 | .Vb 3 |
|
|
2048 | \& last_activity = ev_now (EV_A); |
2015 | \& ev_init (timer, callback); |
2049 | \& ev_init (&timer, callback); |
2016 | \& last_activity = ev_now (loop); |
2050 | \& callback (EV_A_ &timer, 0); |
2017 | \& callback (loop, timer, EV_TIMER); |
|
|
2018 | .Ve |
2051 | .Ve |
2019 | .Sp |
2052 | .Sp |
2020 | And when there is some activity, simply store the current time in |
2053 | When there is some activity, simply store the current time in |
2021 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
2054 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
2022 | .Sp |
2055 | .Sp |
2023 | .Vb 1 |
2056 | .Vb 2 |
|
|
2057 | \& if (activity detected) |
2024 | \& last_activity = ev_now (loop); |
2058 | \& last_activity = ev_now (EV_A); |
|
|
2059 | .Ve |
|
|
2060 | .Sp |
|
|
2061 | When your timeout value changes, then the timeout can be changed by simply |
|
|
2062 | providing a new value, stopping the timer and calling the callback, which |
|
|
2063 | will again do the right thing (for example, time out immediately :). |
|
|
2064 | .Sp |
|
|
2065 | .Vb 3 |
|
|
2066 | \& timeout = new_value; |
|
|
2067 | \& ev_timer_stop (EV_A_ &timer); |
|
|
2068 | \& callback (EV_A_ &timer, 0); |
2025 | .Ve |
2069 | .Ve |
2026 | .Sp |
2070 | .Sp |
2027 | This technique is slightly more complex, but in most cases where the |
2071 | This technique is slightly more complex, but in most cases where the |
2028 | time-out is unlikely to be triggered, much more efficient. |
2072 | time-out is unlikely to be triggered, much more efficient. |
2029 | .Sp |
|
|
2030 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
|
|
2031 | callback :) \- just change the timeout and invoke the callback, which will |
|
|
2032 | fix things for you. |
|
|
2033 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
2073 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
2034 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
2074 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
2035 | If there is not one request, but many thousands (millions...), all |
2075 | If there is not one request, but many thousands (millions...), all |
2036 | employing some kind of timeout with the same timeout value, then one can |
2076 | employing some kind of timeout with the same timeout value, then one can |
2037 | do even better: |
2077 | do even better: |
… | |
… | |
2061 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
2101 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
2062 | rather complicated, but extremely efficient, something that really pays |
2102 | rather complicated, but extremely efficient, something that really pays |
2063 | off after the first million or so of active timers, i.e. it's usually |
2103 | off after the first million or so of active timers, i.e. it's usually |
2064 | overkill :) |
2104 | overkill :) |
2065 | .PP |
2105 | .PP |
|
|
2106 | \fIThe special problem of being too early\fR |
|
|
2107 | .IX Subsection "The special problem of being too early" |
|
|
2108 | .PP |
|
|
2109 | If you ask a timer to call your callback after three seconds, then |
|
|
2110 | you expect it to be invoked after three seconds \- but of course, this |
|
|
2111 | cannot be guaranteed to infinite precision. Less obviously, it cannot be |
|
|
2112 | guaranteed to any precision by libev \- imagine somebody suspending the |
|
|
2113 | process with a \s-1STOP\s0 signal for a few hours for example. |
|
|
2114 | .PP |
|
|
2115 | So, libev tries to invoke your callback as soon as possible \fIafter\fR the |
|
|
2116 | delay has occurred, but cannot guarantee this. |
|
|
2117 | .PP |
|
|
2118 | A less obvious failure mode is calling your callback too early: many event |
|
|
2119 | loops compare timestamps with a \*(L"elapsed delay >= requested delay\*(R", but |
|
|
2120 | this can cause your callback to be invoked much earlier than you would |
|
|
2121 | expect. |
|
|
2122 | .PP |
|
|
2123 | To see why, imagine a system with a clock that only offers full second |
|
|
2124 | resolution (think windows if you can't come up with a broken enough \s-1OS\s0 |
|
|
2125 | yourself). If you schedule a one-second timer at the time 500.9, then the |
|
|
2126 | event loop will schedule your timeout to elapse at a system time of 500 |
|
|
2127 | (500.9 truncated to the resolution) + 1, or 501. |
|
|
2128 | .PP |
|
|
2129 | If an event library looks at the timeout 0.1s later, it will see \*(L"501 >= |
|
|
2130 | 501\*(R" and invoke the callback 0.1s after it was started, even though a |
|
|
2131 | one-second delay was requested \- this is being \*(L"too early\*(R", despite best |
|
|
2132 | intentions. |
|
|
2133 | .PP |
|
|
2134 | This is the reason why libev will never invoke the callback if the elapsed |
|
|
2135 | delay equals the requested delay, but only when the elapsed delay is |
|
|
2136 | larger than the requested delay. In the example above, libev would only invoke |
|
|
2137 | the callback at system time 502, or 1.1s after the timer was started. |
|
|
2138 | .PP |
|
|
2139 | So, while libev cannot guarantee that your callback will be invoked |
|
|
2140 | exactly when requested, it \fIcan\fR and \fIdoes\fR guarantee that the requested |
|
|
2141 | delay has actually elapsed, or in other words, it always errs on the \*(L"too |
|
|
2142 | late\*(R" side of things. |
|
|
2143 | .PP |
2066 | \fIThe special problem of time updates\fR |
2144 | \fIThe special problem of time updates\fR |
2067 | .IX Subsection "The special problem of time updates" |
2145 | .IX Subsection "The special problem of time updates" |
2068 | .PP |
2146 | .PP |
2069 | Establishing the current time is a costly operation (it usually takes at |
2147 | Establishing the current time is a costly operation (it usually takes |
2070 | least two system calls): \s-1EV\s0 therefore updates its idea of the current |
2148 | at least one system call): \s-1EV\s0 therefore updates its idea of the current |
2071 | time only before and after \f(CW\*(C`ev_run\*(C'\fR collects new events, which causes a |
2149 | time only before and after \f(CW\*(C`ev_run\*(C'\fR collects new events, which causes a |
2072 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
2150 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
2073 | lots of events in one iteration. |
2151 | lots of events in one iteration. |
2074 | .PP |
2152 | .PP |
2075 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2153 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
… | |
… | |
2083 | .Ve |
2161 | .Ve |
2084 | .PP |
2162 | .PP |
2085 | If the event loop is suspended for a long time, you can also force an |
2163 | If the event loop is suspended for a long time, you can also force an |
2086 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2164 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2087 | ()\*(C'\fR. |
2165 | ()\*(C'\fR. |
|
|
2166 | .PP |
|
|
2167 | \fIThe special problem of unsynchronised clocks\fR |
|
|
2168 | .IX Subsection "The special problem of unsynchronised clocks" |
|
|
2169 | .PP |
|
|
2170 | Modern systems have a variety of clocks \- libev itself uses the normal |
|
|
2171 | \&\*(L"wall clock\*(R" clock and, if available, the monotonic clock (to avoid time |
|
|
2172 | jumps). |
|
|
2173 | .PP |
|
|
2174 | Neither of these clocks is synchronised with each other or any other clock |
|
|
2175 | on the system, so \f(CW\*(C`ev_time ()\*(C'\fR might return a considerably different time |
|
|
2176 | than \f(CW\*(C`gettimeofday ()\*(C'\fR or \f(CW\*(C`time ()\*(C'\fR. On a GNU/Linux system, for example, |
|
|
2177 | a call to \f(CW\*(C`gettimeofday\*(C'\fR might return a second count that is one higher |
|
|
2178 | than a directly following call to \f(CW\*(C`time\*(C'\fR. |
|
|
2179 | .PP |
|
|
2180 | The moral of this is to only compare libev-related timestamps with |
|
|
2181 | \&\f(CW\*(C`ev_time ()\*(C'\fR and \f(CW\*(C`ev_now ()\*(C'\fR, at least if you want better precision than |
|
|
2182 | a second or so. |
|
|
2183 | .PP |
|
|
2184 | One more problem arises due to this lack of synchronisation: if libev uses |
|
|
2185 | the system monotonic clock and you compare timestamps from \f(CW\*(C`ev_time\*(C'\fR |
|
|
2186 | or \f(CW\*(C`ev_now\*(C'\fR from when you started your timer and when your callback is |
|
|
2187 | invoked, you will find that sometimes the callback is a bit \*(L"early\*(R". |
|
|
2188 | .PP |
|
|
2189 | This is because \f(CW\*(C`ev_timer\*(C'\fRs work in real time, not wall clock time, so |
|
|
2190 | libev makes sure your callback is not invoked before the delay happened, |
|
|
2191 | \&\fImeasured according to the real time\fR, not the system clock. |
|
|
2192 | .PP |
|
|
2193 | If your timeouts are based on a physical timescale (e.g. \*(L"time out this |
|
|
2194 | connection after 100 seconds\*(R") then this shouldn't bother you as it is |
|
|
2195 | exactly the right behaviour. |
|
|
2196 | .PP |
|
|
2197 | If you want to compare wall clock/system timestamps to your timers, then |
|
|
2198 | you need to use \f(CW\*(C`ev_periodic\*(C'\fRs, as these are based on the wall clock |
|
|
2199 | time, where your comparisons will always generate correct results. |
2088 | .PP |
2200 | .PP |
2089 | \fIThe special problems of suspended animation\fR |
2201 | \fIThe special problems of suspended animation\fR |
2090 | .IX Subsection "The special problems of suspended animation" |
2202 | .IX Subsection "The special problems of suspended animation" |
2091 | .PP |
2203 | .PP |
2092 | When you leave the server world it is quite customary to hit machines that |
2204 | When you leave the server world it is quite customary to hit machines that |
… | |
… | |
2136 | trigger at exactly 10 second intervals. If, however, your program cannot |
2248 | trigger at exactly 10 second intervals. If, however, your program cannot |
2137 | keep up with the timer (because it takes longer than those 10 seconds to |
2249 | keep up with the timer (because it takes longer than those 10 seconds to |
2138 | do stuff) the timer will not fire more than once per event loop iteration. |
2250 | do stuff) the timer will not fire more than once per event loop iteration. |
2139 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
2251 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
2140 | .IX Item "ev_timer_again (loop, ev_timer *)" |
2252 | .IX Item "ev_timer_again (loop, ev_timer *)" |
2141 | This will act as if the timer timed out and restart it again if it is |
2253 | This will act as if the timer timed out, and restarts it again if it is |
2142 | repeating. The exact semantics are: |
2254 | repeating. It basically works like calling \f(CW\*(C`ev_timer_stop\*(C'\fR, updating the |
|
|
2255 | timeout to the \f(CW\*(C`repeat\*(C'\fR value and calling \f(CW\*(C`ev_timer_start\*(C'\fR. |
2143 | .Sp |
2256 | .Sp |
|
|
2257 | The exact semantics are as in the following rules, all of which will be |
|
|
2258 | applied to the watcher: |
|
|
2259 | .RS 4 |
2144 | If the timer is pending, its pending status is cleared. |
2260 | .IP "If the timer is pending, the pending status is always cleared." 4 |
2145 | .Sp |
2261 | .IX Item "If the timer is pending, the pending status is always cleared." |
|
|
2262 | .PD 0 |
2146 | If the timer is started but non-repeating, stop it (as if it timed out). |
2263 | .IP "If the timer is started but non-repeating, stop it (as if it timed out, without invoking it)." 4 |
2147 | .Sp |
2264 | .IX Item "If the timer is started but non-repeating, stop it (as if it timed out, without invoking it)." |
2148 | If the timer is repeating, either start it if necessary (with the |
2265 | .ie n .IP "If the timer is repeating, make the ""repeat"" value the new timeout and start the timer, if necessary." 4 |
2149 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
2266 | .el .IP "If the timer is repeating, make the \f(CWrepeat\fR value the new timeout and start the timer, if necessary." 4 |
|
|
2267 | .IX Item "If the timer is repeating, make the repeat value the new timeout and start the timer, if necessary." |
|
|
2268 | .RE |
|
|
2269 | .RS 4 |
|
|
2270 | .PD |
2150 | .Sp |
2271 | .Sp |
2151 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
2272 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
2152 | usage example. |
2273 | usage example. |
|
|
2274 | .RE |
2153 | .IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4 |
2275 | .IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4 |
2154 | .IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)" |
2276 | .IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)" |
2155 | Returns the remaining time until a timer fires. If the timer is active, |
2277 | Returns the remaining time until a timer fires. If the timer is active, |
2156 | then this time is relative to the current event loop time, otherwise it's |
2278 | then this time is relative to the current event loop time, otherwise it's |
2157 | the timeout value currently configured. |
2279 | the timeout value currently configured. |
… | |
… | |
2277 | .Sp |
2399 | .Sp |
2278 | Another way to think about it (for the mathematically inclined) is that |
2400 | Another way to think about it (for the mathematically inclined) is that |
2279 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2401 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2280 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
2402 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
2281 | .Sp |
2403 | .Sp |
2282 | For numerical stability it is preferable that the \f(CW\*(C`offset\*(C'\fR value is near |
2404 | The \f(CW\*(C`interval\*(C'\fR \fI\s-1MUST\s0\fR be positive, and for numerical stability, the |
2283 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
2405 | interval value should be higher than \f(CW\*(C`1/8192\*(C'\fR (which is around 100 |
2284 | this value, and in fact is often specified as zero. |
2406 | microseconds) and \f(CW\*(C`offset\*(C'\fR should be higher than \f(CW0\fR and should have |
|
|
2407 | at most a similar magnitude as the current time (say, within a factor of |
|
|
2408 | ten). Typical values for offset are, in fact, \f(CW0\fR or something between |
|
|
2409 | \&\f(CW0\fR and \f(CW\*(C`interval\*(C'\fR, which is also the recommended range. |
2285 | .Sp |
2410 | .Sp |
2286 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2411 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2287 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
2412 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
2288 | will of course deteriorate. Libev itself tries to be exact to be about one |
2413 | will of course deteriorate. Libev itself tries to be exact to be about one |
2289 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
2414 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
… | |
… | |
2617 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
2742 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
2618 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
2743 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
2619 | .IX Subsection "ev_stat - did the file attributes just change?" |
2744 | .IX Subsection "ev_stat - did the file attributes just change?" |
2620 | This watches a file system path for attribute changes. That is, it calls |
2745 | This watches a file system path for attribute changes. That is, it calls |
2621 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2746 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2622 | and sees if it changed compared to the last time, invoking the callback if |
2747 | and sees if it changed compared to the last time, invoking the callback |
2623 | it did. |
2748 | if it did. Starting the watcher \f(CW\*(C`stat\*(C'\fR's the file, so only changes that |
|
|
2749 | happen after the watcher has been started will be reported. |
2624 | .PP |
2750 | .PP |
2625 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2751 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2626 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
2752 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
2627 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
2753 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
2628 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
2754 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
… | |
… | |
2859 | Apart from keeping your process non-blocking (which is a useful |
2985 | Apart from keeping your process non-blocking (which is a useful |
2860 | effect on its own sometimes), idle watchers are a good place to do |
2986 | effect on its own sometimes), idle watchers are a good place to do |
2861 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2987 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2862 | event loop has handled all outstanding events. |
2988 | event loop has handled all outstanding events. |
2863 | .PP |
2989 | .PP |
|
|
2990 | \fIAbusing an \f(CI\*(C`ev_idle\*(C'\fI watcher for its side-effect\fR |
|
|
2991 | .IX Subsection "Abusing an ev_idle watcher for its side-effect" |
|
|
2992 | .PP |
|
|
2993 | As long as there is at least one active idle watcher, libev will never |
|
|
2994 | sleep unnecessarily. Or in other words, it will loop as fast as possible. |
|
|
2995 | For this to work, the idle watcher doesn't need to be invoked at all \- the |
|
|
2996 | lowest priority will do. |
|
|
2997 | .PP |
|
|
2998 | This mode of operation can be useful together with an \f(CW\*(C`ev_check\*(C'\fR watcher, |
|
|
2999 | to do something on each event loop iteration \- for example to balance load |
|
|
3000 | between different connections. |
|
|
3001 | .PP |
|
|
3002 | See \*(L"Abusing an ev_check watcher for its side-effect\*(R" for a longer |
|
|
3003 | example. |
|
|
3004 | .PP |
2864 | \fIWatcher-Specific Functions and Data Members\fR |
3005 | \fIWatcher-Specific Functions and Data Members\fR |
2865 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3006 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2866 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
3007 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
2867 | .IX Item "ev_idle_init (ev_idle *, callback)" |
3008 | .IX Item "ev_idle_init (ev_idle *, callback)" |
2868 | Initialises and configures the idle watcher \- it has no parameters of any |
3009 | Initialises and configures the idle watcher \- it has no parameters of any |
… | |
… | |
2873 | .IX Subsection "Examples" |
3014 | .IX Subsection "Examples" |
2874 | .PP |
3015 | .PP |
2875 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
3016 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
2876 | callback, free it. Also, use no error checking, as usual. |
3017 | callback, free it. Also, use no error checking, as usual. |
2877 | .PP |
3018 | .PP |
2878 | .Vb 7 |
3019 | .Vb 5 |
2879 | \& static void |
3020 | \& static void |
2880 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
3021 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2881 | \& { |
3022 | \& { |
|
|
3023 | \& // stop the watcher |
|
|
3024 | \& ev_idle_stop (loop, w); |
|
|
3025 | \& |
|
|
3026 | \& // now we can free it |
2882 | \& free (w); |
3027 | \& free (w); |
|
|
3028 | \& |
2883 | \& // now do something you wanted to do when the program has |
3029 | \& // now do something you wanted to do when the program has |
2884 | \& // no longer anything immediate to do. |
3030 | \& // no longer anything immediate to do. |
2885 | \& } |
3031 | \& } |
2886 | \& |
3032 | \& |
2887 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
3033 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
… | |
… | |
2889 | \& ev_idle_start (loop, idle_watcher); |
3035 | \& ev_idle_start (loop, idle_watcher); |
2890 | .Ve |
3036 | .Ve |
2891 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
3037 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
2892 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
3038 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2893 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
3039 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2894 | Prepare and check watchers are usually (but not always) used in pairs: |
3040 | Prepare and check watchers are often (but not always) used in pairs: |
2895 | prepare watchers get invoked before the process blocks and check watchers |
3041 | prepare watchers get invoked before the process blocks and check watchers |
2896 | afterwards. |
3042 | afterwards. |
2897 | .PP |
3043 | .PP |
2898 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter |
3044 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter |
2899 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
3045 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
… | |
… | |
2927 | with priority higher than or equal to the event loop and one coroutine |
3073 | with priority higher than or equal to the event loop and one coroutine |
2928 | of lower priority, but only once, using idle watchers to keep the event |
3074 | of lower priority, but only once, using idle watchers to keep the event |
2929 | loop from blocking if lower-priority coroutines are active, thus mapping |
3075 | loop from blocking if lower-priority coroutines are active, thus mapping |
2930 | low-priority coroutines to idle/background tasks). |
3076 | low-priority coroutines to idle/background tasks). |
2931 | .PP |
3077 | .PP |
2932 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
3078 | When used for this purpose, it is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers |
2933 | priority, to ensure that they are being run before any other watchers |
3079 | highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) priority, to ensure that they are being run before |
2934 | after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR watchers). |
3080 | any other watchers after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR |
|
|
3081 | watchers). |
2935 | .PP |
3082 | .PP |
2936 | Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not |
3083 | Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not |
2937 | activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they |
3084 | activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they |
2938 | might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As |
3085 | might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As |
2939 | \&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event |
3086 | \&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event |
2940 | loops those other event loops might be in an unusable state until their |
3087 | loops those other event loops might be in an unusable state until their |
2941 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
3088 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
2942 | others). |
3089 | others). |
|
|
3090 | .PP |
|
|
3091 | \fIAbusing an \f(CI\*(C`ev_check\*(C'\fI watcher for its side-effect\fR |
|
|
3092 | .IX Subsection "Abusing an ev_check watcher for its side-effect" |
|
|
3093 | .PP |
|
|
3094 | \&\f(CW\*(C`ev_check\*(C'\fR (and less often also \f(CW\*(C`ev_prepare\*(C'\fR) watchers can also be |
|
|
3095 | useful because they are called once per event loop iteration. For |
|
|
3096 | example, if you want to handle a large number of connections fairly, you |
|
|
3097 | normally only do a bit of work for each active connection, and if there |
|
|
3098 | is more work to do, you wait for the next event loop iteration, so other |
|
|
3099 | connections have a chance of making progress. |
|
|
3100 | .PP |
|
|
3101 | Using an \f(CW\*(C`ev_check\*(C'\fR watcher is almost enough: it will be called on the |
|
|
3102 | next event loop iteration. However, that isn't as soon as possible \- |
|
|
3103 | without external events, your \f(CW\*(C`ev_check\*(C'\fR watcher will not be invoked. |
|
|
3104 | .PP |
|
|
3105 | This is where \f(CW\*(C`ev_idle\*(C'\fR watchers come in handy \- all you need is a |
|
|
3106 | single global idle watcher that is active as long as you have one active |
|
|
3107 | \&\f(CW\*(C`ev_check\*(C'\fR watcher. The \f(CW\*(C`ev_idle\*(C'\fR watcher makes sure the event loop |
|
|
3108 | will not sleep, and the \f(CW\*(C`ev_check\*(C'\fR watcher makes sure a callback gets |
|
|
3109 | invoked. Neither watcher alone can do that. |
2943 | .PP |
3110 | .PP |
2944 | \fIWatcher-Specific Functions and Data Members\fR |
3111 | \fIWatcher-Specific Functions and Data Members\fR |
2945 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3112 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2946 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
3113 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
2947 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
3114 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
… | |
… | |
3152 | \fIWatcher-Specific Functions and Data Members\fR |
3319 | \fIWatcher-Specific Functions and Data Members\fR |
3153 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3320 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3154 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3321 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3155 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3322 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3156 | .PD 0 |
3323 | .PD 0 |
3157 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3324 | .IP "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)" 4 |
3158 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3325 | .IX Item "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)" |
3159 | .PD |
3326 | .PD |
3160 | Configures the watcher to embed the given loop, which must be |
3327 | Configures the watcher to embed the given loop, which must be |
3161 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
3328 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
3162 | invoked automatically, otherwise it is the responsibility of the callback |
3329 | invoked automatically, otherwise it is the responsibility of the callback |
3163 | to invoke it (it will continue to be called until the sweep has been done, |
3330 | to invoke it (it will continue to be called until the sweep has been done, |
… | |
… | |
3226 | .ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" |
3393 | .ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" |
3227 | .el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
3394 | .el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
3228 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
3395 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
3229 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
3396 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
3230 | whoever is a good citizen cared to tell libev about it by calling |
3397 | whoever is a good citizen cared to tell libev about it by calling |
3231 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
3398 | \&\f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the event loop blocks next |
3232 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
3399 | and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, and only in the child |
3233 | and only in the child after the fork. If whoever good citizen calling |
3400 | after the fork. If whoever good citizen calling \f(CW\*(C`ev_default_fork\*(C'\fR cheats |
3234 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
3401 | and calls it in the wrong process, the fork handlers will be invoked, too, |
3235 | handlers will be invoked, too, of course. |
3402 | of course. |
3236 | .PP |
3403 | .PP |
3237 | \fIThe special problem of life after fork \- how is it possible?\fR |
3404 | \fIThe special problem of life after fork \- how is it possible?\fR |
3238 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3405 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3239 | .PP |
3406 | .PP |
3240 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to set |
3407 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to set |
… | |
… | |
3326 | it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe. |
3493 | it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe. |
3327 | .PP |
3494 | .PP |
3328 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
3495 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
3329 | too, are asynchronous in nature, and signals, too, will be compressed |
3496 | too, are asynchronous in nature, and signals, too, will be compressed |
3330 | (i.e. the number of callback invocations may be less than the number of |
3497 | (i.e. the number of callback invocations may be less than the number of |
3331 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). In fact, you could use signal watchers as a kind |
3498 | \&\f(CW\*(C`ev_async_send\*(C'\fR calls). In fact, you could use signal watchers as a kind |
3332 | of \*(L"global async watchers\*(R" by using a watcher on an otherwise unused |
3499 | of \*(L"global async watchers\*(R" by using a watcher on an otherwise unused |
3333 | signal, and \f(CW\*(C`ev_feed_signal\*(C'\fR to signal this watcher from another thread, |
3500 | signal, and \f(CW\*(C`ev_feed_signal\*(C'\fR to signal this watcher from another thread, |
3334 | even without knowing which loop owns the signal. |
3501 | even without knowing which loop owns the signal. |
3335 | .PP |
|
|
3336 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
|
|
3337 | just the default loop. |
|
|
3338 | .PP |
3502 | .PP |
3339 | \fIQueueing\fR |
3503 | \fIQueueing\fR |
3340 | .IX Subsection "Queueing" |
3504 | .IX Subsection "Queueing" |
3341 | .PP |
3505 | .PP |
3342 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
3506 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
… | |
… | |
3437 | Unlike \f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, |
3601 | Unlike \f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, |
3438 | signal or similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the |
3602 | signal or similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the |
3439 | embedding section below on what exactly this means). |
3603 | embedding section below on what exactly this means). |
3440 | .Sp |
3604 | .Sp |
3441 | Note that, as with other watchers in libev, multiple events might get |
3605 | Note that, as with other watchers in libev, multiple events might get |
3442 | compressed into a single callback invocation (another way to look at this |
3606 | compressed into a single callback invocation (another way to look at |
3443 | is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered, set on \f(CW\*(C`ev_async_send\*(C'\fR, |
3607 | this is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered: they are set on |
3444 | reset when the event loop detects that). |
3608 | \&\f(CW\*(C`ev_async_send\*(C'\fR, reset when the event loop detects that). |
3445 | .Sp |
3609 | .Sp |
3446 | This call incurs the overhead of a system call only once per event loop |
3610 | This call incurs the overhead of at most one extra system call per event |
3447 | iteration, so while the overhead might be noticeable, it doesn't apply to |
3611 | loop iteration, if the event loop is blocked, and no syscall at all if |
3448 | repeated calls to \f(CW\*(C`ev_async_send\*(C'\fR for the same event loop. |
3612 | the event loop (or your program) is processing events. That means that |
|
|
3613 | repeated calls are basically free (there is no need to avoid calls for |
|
|
3614 | performance reasons) and that the overhead becomes smaller (typically |
|
|
3615 | zero) under load. |
3449 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3616 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3450 | .IX Item "bool = ev_async_pending (ev_async *)" |
3617 | .IX Item "bool = ev_async_pending (ev_async *)" |
3451 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3618 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3452 | watcher but the event has not yet been processed (or even noted) by the |
3619 | watcher but the event has not yet been processed (or even noted) by the |
3453 | event loop. |
3620 | event loop. |
… | |
… | |
3501 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3668 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3502 | .Ve |
3669 | .Ve |
3503 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
3670 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
3504 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
3671 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
3505 | Feed an event on the given fd, as if a file descriptor backend detected |
3672 | Feed an event on the given fd, as if a file descriptor backend detected |
3506 | the given events it. |
3673 | the given events. |
3507 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
3674 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
3508 | .IX Item "ev_feed_signal_event (loop, int signum)" |
3675 | .IX Item "ev_feed_signal_event (loop, int signum)" |
3509 | Feed an event as if the given signal occurred. See also \f(CW\*(C`ev_feed_signal\*(C'\fR, |
3676 | Feed an event as if the given signal occurred. See also \f(CW\*(C`ev_feed_signal\*(C'\fR, |
3510 | which is async-safe. |
3677 | which is async-safe. |
3511 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3678 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
… | |
… | |
3585 | \& { |
3752 | \& { |
3586 | \& struct my_biggy big = (struct my_biggy *) |
3753 | \& struct my_biggy big = (struct my_biggy *) |
3587 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
3754 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
3588 | \& } |
3755 | \& } |
3589 | .Ve |
3756 | .Ve |
|
|
3757 | .SS "\s-1AVOIDING\s0 \s-1FINISHING\s0 \s-1BEFORE\s0 \s-1RETURNING\s0" |
|
|
3758 | .IX Subsection "AVOIDING FINISHING BEFORE RETURNING" |
|
|
3759 | Often you have structures like this in event-based programs: |
|
|
3760 | .PP |
|
|
3761 | .Vb 4 |
|
|
3762 | \& callback () |
|
|
3763 | \& { |
|
|
3764 | \& free (request); |
|
|
3765 | \& } |
|
|
3766 | \& |
|
|
3767 | \& request = start_new_request (..., callback); |
|
|
3768 | .Ve |
|
|
3769 | .PP |
|
|
3770 | The intent is to start some \*(L"lengthy\*(R" operation. The \f(CW\*(C`request\*(C'\fR could be |
|
|
3771 | used to cancel the operation, or do other things with it. |
|
|
3772 | .PP |
|
|
3773 | It's not uncommon to have code paths in \f(CW\*(C`start_new_request\*(C'\fR that |
|
|
3774 | immediately invoke the callback, for example, to report errors. Or you add |
|
|
3775 | some caching layer that finds that it can skip the lengthy aspects of the |
|
|
3776 | operation and simply invoke the callback with the result. |
|
|
3777 | .PP |
|
|
3778 | The problem here is that this will happen \fIbefore\fR \f(CW\*(C`start_new_request\*(C'\fR |
|
|
3779 | has returned, so \f(CW\*(C`request\*(C'\fR is not set. |
|
|
3780 | .PP |
|
|
3781 | Even if you pass the request by some safer means to the callback, you |
|
|
3782 | might want to do something to the request after starting it, such as |
|
|
3783 | canceling it, which probably isn't working so well when the callback has |
|
|
3784 | already been invoked. |
|
|
3785 | .PP |
|
|
3786 | A common way around all these issues is to make sure that |
|
|
3787 | \&\f(CW\*(C`start_new_request\*(C'\fR \fIalways\fR returns before the callback is invoked. If |
|
|
3788 | \&\f(CW\*(C`start_new_request\*(C'\fR immediately knows the result, it can artificially |
|
|
3789 | delay invoking the callback by using a \f(CW\*(C`prepare\*(C'\fR or \f(CW\*(C`idle\*(C'\fR watcher for |
|
|
3790 | example, or more sneakily, by reusing an existing (stopped) watcher and |
|
|
3791 | pushing it into the pending queue: |
|
|
3792 | .PP |
|
|
3793 | .Vb 2 |
|
|
3794 | \& ev_set_cb (watcher, callback); |
|
|
3795 | \& ev_feed_event (EV_A_ watcher, 0); |
|
|
3796 | .Ve |
|
|
3797 | .PP |
|
|
3798 | This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is |
|
|
3799 | invoked, while not delaying callback invocation too much. |
3590 | .SS "\s-1MODEL/NESTED\s0 \s-1EVENT\s0 \s-1LOOP\s0 \s-1INVOCATIONS\s0 \s-1AND\s0 \s-1EXIT\s0 \s-1CONDITIONS\s0" |
3800 | .SS "\s-1MODEL/NESTED\s0 \s-1EVENT\s0 \s-1LOOP\s0 \s-1INVOCATIONS\s0 \s-1AND\s0 \s-1EXIT\s0 \s-1CONDITIONS\s0" |
3591 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
3801 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
3592 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
3802 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
3593 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
3803 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
3594 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
3804 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
3595 | .PP |
3805 | .PP |
3596 | This brings the problem of exiting \- a callback might want to finish the |
3806 | This brings the problem of exiting \- a callback might want to finish the |
3597 | main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but |
3807 | main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but |
3598 | a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one |
3808 | a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one |
3599 | and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some |
3809 | and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some |
3600 | other combination: In these cases, \f(CW\*(C`ev_break\*(C'\fR will not work alone. |
3810 | other combination: In these cases, a simple \f(CW\*(C`ev_break\*(C'\fR will not work. |
3601 | .PP |
3811 | .PP |
3602 | The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR |
3812 | The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR |
3603 | invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is |
3813 | invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is |
3604 | triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR: |
3814 | triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR: |
3605 | .PP |
3815 | .PP |
… | |
… | |
3608 | \& int exit_main_loop = 0; |
3818 | \& int exit_main_loop = 0; |
3609 | \& |
3819 | \& |
3610 | \& while (!exit_main_loop) |
3820 | \& while (!exit_main_loop) |
3611 | \& ev_run (EV_DEFAULT_ EVRUN_ONCE); |
3821 | \& ev_run (EV_DEFAULT_ EVRUN_ONCE); |
3612 | \& |
3822 | \& |
3613 | \& // in a model watcher |
3823 | \& // in a modal watcher |
3614 | \& int exit_nested_loop = 0; |
3824 | \& int exit_nested_loop = 0; |
3615 | \& |
3825 | \& |
3616 | \& while (!exit_nested_loop) |
3826 | \& while (!exit_nested_loop) |
3617 | \& ev_run (EV_A_ EVRUN_ONCE); |
3827 | \& ev_run (EV_A_ EVRUN_ONCE); |
3618 | .Ve |
3828 | .Ve |
… | |
… | |
3810 | .PP |
4020 | .PP |
3811 | .Vb 6 |
4021 | .Vb 6 |
3812 | \& void |
4022 | \& void |
3813 | \& wait_for_event (ev_watcher *w) |
4023 | \& wait_for_event (ev_watcher *w) |
3814 | \& { |
4024 | \& { |
3815 | \& ev_cb_set (w) = current_coro; |
4025 | \& ev_set_cb (w, current_coro); |
3816 | \& switch_to (libev_coro); |
4026 | \& switch_to (libev_coro); |
3817 | \& } |
4027 | \& } |
3818 | .Ve |
4028 | .Ve |
3819 | .PP |
4029 | .PP |
3820 | That basically suspends the coroutine inside \f(CW\*(C`wait_for_event\*(C'\fR and |
4030 | That basically suspends the coroutine inside \f(CW\*(C`wait_for_event\*(C'\fR and |
3821 | continues the libev coroutine, which, when appropriate, switches back to |
4031 | continues the libev coroutine, which, when appropriate, switches back to |
3822 | this or any other coroutine. I am sure if you sue this your own :) |
4032 | this or any other coroutine. |
3823 | .PP |
4033 | .PP |
3824 | You can do similar tricks if you have, say, threads with an event queue \- |
4034 | You can do similar tricks if you have, say, threads with an event queue \- |
3825 | instead of storing a coroutine, you store the queue object and instead of |
4035 | instead of storing a coroutine, you store the queue object and instead of |
3826 | switching to a coroutine, you push the watcher onto the queue and notify |
4036 | switching to a coroutine, you push the watcher onto the queue and notify |
3827 | any waiters. |
4037 | any waiters. |
3828 | .PP |
4038 | .PP |
3829 | To embed libev, see \s-1EMBEDDING\s0, but in short, it's easiest to create two |
4039 | To embed libev, see \*(L"\s-1EMBEDDING\s0\*(R", but in short, it's easiest to create two |
3830 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
4040 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
3831 | .PP |
4041 | .PP |
3832 | .Vb 4 |
4042 | .Vb 4 |
3833 | \& // my_ev.h |
4043 | \& // my_ev.h |
3834 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
4044 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
… | |
… | |
3873 | .IP "\(bu" 4 |
4083 | .IP "\(bu" 4 |
3874 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
4084 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
3875 | to use the libev header file and library. |
4085 | to use the libev header file and library. |
3876 | .SH "\*(C+ SUPPORT" |
4086 | .SH "\*(C+ SUPPORT" |
3877 | .IX Header " SUPPORT" |
4087 | .IX Header " SUPPORT" |
|
|
4088 | .SS "C \s-1API\s0" |
|
|
4089 | .IX Subsection "C API" |
|
|
4090 | The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the |
|
|
4091 | libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 |
|
|
4092 | will work fine. |
|
|
4093 | .PP |
|
|
4094 | Proper exception specifications might have to be added to callbacks passed |
|
|
4095 | to libev: exceptions may be thrown only from watcher callbacks, all |
|
|
4096 | other callbacks (allocator, syserr, loop acquire/release and periodic |
|
|
4097 | reschedule callbacks) must not throw exceptions, and might need a \f(CW\*(C`throw |
|
|
4098 | ()\*(C'\fR specification. If you have code that needs to be compiled as both C |
|
|
4099 | and \*(C+ you can use the \f(CW\*(C`EV_THROW\*(C'\fR macro for this: |
|
|
4100 | .PP |
|
|
4101 | .Vb 6 |
|
|
4102 | \& static void |
|
|
4103 | \& fatal_error (const char *msg) EV_THROW |
|
|
4104 | \& { |
|
|
4105 | \& perror (msg); |
|
|
4106 | \& abort (); |
|
|
4107 | \& } |
|
|
4108 | \& |
|
|
4109 | \& ... |
|
|
4110 | \& ev_set_syserr_cb (fatal_error); |
|
|
4111 | .Ve |
|
|
4112 | .PP |
|
|
4113 | The only \s-1API\s0 functions that can currently throw exceptions are \f(CW\*(C`ev_run\*(C'\fR, |
|
|
4114 | \&\f(CW\*(C`ev_invoke\*(C'\fR, \f(CW\*(C`ev_invoke_pending\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR (the latter |
|
|
4115 | because it runs cleanup watchers). |
|
|
4116 | .PP |
|
|
4117 | Throwing exceptions in watcher callbacks is only supported if libev itself |
|
|
4118 | is compiled with a \*(C+ compiler or your C and \*(C+ environments allow |
|
|
4119 | throwing exceptions through C libraries (most do). |
|
|
4120 | .SS "\*(C+ \s-1API\s0" |
|
|
4121 | .IX Subsection " API" |
3878 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
4122 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
3879 | you to use some convenience methods to start/stop watchers and also change |
4123 | you to use some convenience methods to start/stop watchers and also change |
3880 | the callback model to a model using method callbacks on objects. |
4124 | the callback model to a model using method callbacks on objects. |
3881 | .PP |
4125 | .PP |
3882 | To use it, |
4126 | To use it, |
… | |
… | |
3898 | Currently, functions, static and non-static member functions and classes |
4142 | Currently, functions, static and non-static member functions and classes |
3899 | with \f(CW\*(C`operator ()\*(C'\fR can be used as callbacks. Other types should be easy |
4143 | with \f(CW\*(C`operator ()\*(C'\fR can be used as callbacks. Other types should be easy |
3900 | to add as long as they only need one additional pointer for context. If |
4144 | to add as long as they only need one additional pointer for context. If |
3901 | you need support for other types of functors please contact the author |
4145 | you need support for other types of functors please contact the author |
3902 | (preferably after implementing it). |
4146 | (preferably after implementing it). |
|
|
4147 | .PP |
|
|
4148 | For all this to work, your \*(C+ compiler either has to use the same calling |
|
|
4149 | conventions as your C compiler (for static member functions), or you have |
|
|
4150 | to embed libev and compile libev itself as \*(C+. |
3903 | .PP |
4151 | .PP |
3904 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
4152 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
3905 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
4153 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
3906 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
4154 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
3907 | .IX Item "ev::READ, ev::WRITE etc." |
4155 | .IX Item "ev::READ, ev::WRITE etc." |
… | |
… | |
3915 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
4163 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
3916 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
4164 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
3917 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
4165 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
3918 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
4166 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
3919 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
4167 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
3920 | defines by many implementations. |
4168 | defined by many implementations. |
3921 | .Sp |
4169 | .Sp |
3922 | All of those classes have these methods: |
4170 | All of those classes have these methods: |
3923 | .RS 4 |
4171 | .RS 4 |
3924 | .IP "ev::TYPE::TYPE ()" 4 |
4172 | .IP "ev::TYPE::TYPE ()" 4 |
3925 | .IX Item "ev::TYPE::TYPE ()" |
4173 | .IX Item "ev::TYPE::TYPE ()" |
… | |
… | |
4016 | .IX Item "w->set (loop)" |
4264 | .IX Item "w->set (loop)" |
4017 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
4265 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
4018 | do this when the watcher is inactive (and not pending either). |
4266 | do this when the watcher is inactive (and not pending either). |
4019 | .IP "w\->set ([arguments])" 4 |
4267 | .IP "w\->set ([arguments])" 4 |
4020 | .IX Item "w->set ([arguments])" |
4268 | .IX Item "w->set ([arguments])" |
4021 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Either this |
4269 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR (except for \f(CW\*(C`ev::embed\*(C'\fR watchers>), |
4022 | method or a suitable start method must be called at least once. Unlike the |
4270 | with the same arguments. Either this method or a suitable start method |
4023 | C counterpart, an active watcher gets automatically stopped and restarted |
4271 | must be called at least once. Unlike the C counterpart, an active watcher |
4024 | when reconfiguring it with this method. |
4272 | gets automatically stopped and restarted when reconfiguring it with this |
|
|
4273 | method. |
|
|
4274 | .Sp |
|
|
4275 | For \f(CW\*(C`ev::embed\*(C'\fR watchers this method is called \f(CW\*(C`set_embed\*(C'\fR, to avoid |
|
|
4276 | clashing with the \f(CW\*(C`set (loop)\*(C'\fR method. |
4025 | .IP "w\->start ()" 4 |
4277 | .IP "w\->start ()" 4 |
4026 | .IX Item "w->start ()" |
4278 | .IX Item "w->start ()" |
4027 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
4279 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
4028 | constructor already stores the event loop. |
4280 | constructor already stores the event loop. |
4029 | .IP "w\->start ([arguments])" 4 |
4281 | .IP "w\->start ([arguments])" 4 |
… | |
… | |
4056 | .PP |
4308 | .PP |
4057 | .Vb 5 |
4309 | .Vb 5 |
4058 | \& class myclass |
4310 | \& class myclass |
4059 | \& { |
4311 | \& { |
4060 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
4312 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
4061 | \& ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
4313 | \& ev::io io2 ; void io2_cb (ev::io &w, int revents); |
4062 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
4314 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
4063 | \& |
4315 | \& |
4064 | \& myclass (int fd) |
4316 | \& myclass (int fd) |
4065 | \& { |
4317 | \& { |
4066 | \& io .set <myclass, &myclass::io_cb > (this); |
4318 | \& io .set <myclass, &myclass::io_cb > (this); |
… | |
… | |
4105 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
4357 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
4106 | makes rev work even on mingw. |
4358 | makes rev work even on mingw. |
4107 | .IP "Haskell" 4 |
4359 | .IP "Haskell" 4 |
4108 | .IX Item "Haskell" |
4360 | .IX Item "Haskell" |
4109 | A haskell binding to libev is available at |
4361 | A haskell binding to libev is available at |
4110 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
4362 | http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev <http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>. |
4111 | .IP "D" 4 |
4363 | .IP "D" 4 |
4112 | .IX Item "D" |
4364 | .IX Item "D" |
4113 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4365 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4114 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
4366 | be found at <http://www.llucax.com.ar/proj/ev.d/index.html>. |
4115 | .IP "Ocaml" 4 |
4367 | .IP "Ocaml" 4 |
4116 | .IX Item "Ocaml" |
4368 | .IX Item "Ocaml" |
4117 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4369 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4118 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
4370 | http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/ <http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
4119 | .IP "Lua" 4 |
4371 | .IP "Lua" 4 |
4120 | .IX Item "Lua" |
4372 | .IX Item "Lua" |
4121 | Brian Maher has written a partial interface to libev for lua (at the |
4373 | Brian Maher has written a partial interface to libev for lua (at the |
4122 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
4374 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
4123 | <http://github.com/brimworks/lua\-ev>. |
4375 | http://github.com/brimworks/lua\-ev <http://github.com/brimworks/lua-ev>. |
|
|
4376 | .IP "Javascript" 4 |
|
|
4377 | .IX Item "Javascript" |
|
|
4378 | Node.js (<http://nodejs.org>) uses libev as the underlying event library. |
|
|
4379 | .IP "Others" 4 |
|
|
4380 | .IX Item "Others" |
|
|
4381 | There are others, and I stopped counting. |
4124 | .SH "MACRO MAGIC" |
4382 | .SH "MACRO MAGIC" |
4125 | .IX Header "MACRO MAGIC" |
4383 | .IX Header "MACRO MAGIC" |
4126 | Libev can be compiled with a variety of options, the most fundamental |
4384 | Libev can be compiled with a variety of options, the most fundamental |
4127 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
4385 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
4128 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
4386 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
… | |
… | |
4163 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
4421 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
4164 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
4422 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
4165 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
4423 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
4166 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
4424 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
4167 | Similar to the other two macros, this gives you the value of the default |
4425 | Similar to the other two macros, this gives you the value of the default |
4168 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
4426 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). The default loop |
|
|
4427 | will be initialised if it isn't already initialised. |
|
|
4428 | .Sp |
|
|
4429 | For non-multiplicity builds, these macros do nothing, so you always have |
|
|
4430 | to initialise the loop somewhere. |
4169 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
4431 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
4170 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
4432 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
4171 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
4433 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
4172 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
4434 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
4173 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
4435 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
… | |
… | |
4328 | supported). It will also not define any of the structs usually found in |
4590 | supported). It will also not define any of the structs usually found in |
4329 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
4591 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
4330 | .Sp |
4592 | .Sp |
4331 | In standalone mode, libev will still try to automatically deduce the |
4593 | In standalone mode, libev will still try to automatically deduce the |
4332 | configuration, but has to be more conservative. |
4594 | configuration, but has to be more conservative. |
|
|
4595 | .IP "\s-1EV_USE_FLOOR\s0" 4 |
|
|
4596 | .IX Item "EV_USE_FLOOR" |
|
|
4597 | If defined to be \f(CW1\fR, libev will use the \f(CW\*(C`floor ()\*(C'\fR function for its |
|
|
4598 | periodic reschedule calculations, otherwise libev will fall back on a |
|
|
4599 | portable (slower) implementation. If you enable this, you usually have to |
|
|
4600 | link against libm or something equivalent. Enabling this when the \f(CW\*(C`floor\*(C'\fR |
|
|
4601 | function is not available will fail, so the safe default is to not enable |
|
|
4602 | this. |
4333 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
4603 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
4334 | .IX Item "EV_USE_MONOTONIC" |
4604 | .IX Item "EV_USE_MONOTONIC" |
4335 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
4605 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
4336 | monotonic clock option at both compile time and runtime. Otherwise no |
4606 | monotonic clock option at both compile time and runtime. Otherwise no |
4337 | use of the monotonic clock option will be attempted. If you enable this, |
4607 | use of the monotonic clock option will be attempted. If you enable this, |
… | |
… | |
4411 | .IX Item "EV_WIN32_CLOSE_FD(fd)" |
4681 | .IX Item "EV_WIN32_CLOSE_FD(fd)" |
4412 | If programs implement their own fd to handle mapping on win32, then this |
4682 | If programs implement their own fd to handle mapping on win32, then this |
4413 | macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister |
4683 | macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister |
4414 | file descriptors again. Note that the replacement function has to close |
4684 | file descriptors again. Note that the replacement function has to close |
4415 | the underlying \s-1OS\s0 handle. |
4685 | the underlying \s-1OS\s0 handle. |
|
|
4686 | .IP "\s-1EV_USE_WSASOCKET\s0" 4 |
|
|
4687 | .IX Item "EV_USE_WSASOCKET" |
|
|
4688 | If defined to be \f(CW1\fR, libev will use \f(CW\*(C`WSASocket\*(C'\fR to create its internal |
|
|
4689 | communication socket, which works better in some environments. Otherwise, |
|
|
4690 | the normal \f(CW\*(C`socket\*(C'\fR function will be used, which works better in other |
|
|
4691 | environments. |
4416 | .IP "\s-1EV_USE_POLL\s0" 4 |
4692 | .IP "\s-1EV_USE_POLL\s0" 4 |
4417 | .IX Item "EV_USE_POLL" |
4693 | .IX Item "EV_USE_POLL" |
4418 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
4694 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
4419 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
4695 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
4420 | takes precedence over select. |
4696 | takes precedence over select. |
… | |
… | |
4449 | .IX Item "EV_USE_INOTIFY" |
4725 | .IX Item "EV_USE_INOTIFY" |
4450 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
4726 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
4451 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
4727 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
4452 | be detected at runtime. If undefined, it will be enabled if the headers |
4728 | be detected at runtime. If undefined, it will be enabled if the headers |
4453 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4729 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4730 | .IP "\s-1EV_NO_SMP\s0" 4 |
|
|
4731 | .IX Item "EV_NO_SMP" |
|
|
4732 | If defined to be \f(CW1\fR, libev will assume that memory is always coherent |
|
|
4733 | between threads, that is, threads can be used, but threads never run on |
|
|
4734 | different cpus (or different cpu cores). This reduces dependencies |
|
|
4735 | and makes libev faster. |
|
|
4736 | .IP "\s-1EV_NO_THREADS\s0" 4 |
|
|
4737 | .IX Item "EV_NO_THREADS" |
|
|
4738 | If defined to be \f(CW1\fR, libev will assume that it will never be called from |
|
|
4739 | different threads (that includes signal handlers), which is a stronger |
|
|
4740 | assumption than \f(CW\*(C`EV_NO_SMP\*(C'\fR, above. This reduces dependencies and makes |
|
|
4741 | libev faster. |
4454 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
4742 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
4455 | .IX Item "EV_ATOMIC_T" |
4743 | .IX Item "EV_ATOMIC_T" |
4456 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
4744 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
4457 | access is atomic with respect to other threads or signal contexts. No such |
4745 | access is atomic with respect to other threads or signal contexts. No |
4458 | type is easily found in the C language, so you can provide your own type |
4746 | such type is easily found in the C language, so you can provide your own |
4459 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
4747 | type that you know is safe for your purposes. It is used both for signal |
4460 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
4748 | handler \*(L"locking\*(R" as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR |
|
|
4749 | watchers. |
4461 | .Sp |
4750 | .Sp |
4462 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4751 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4463 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4752 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4464 | .IP "\s-1EV_H\s0 (h)" 4 |
4753 | .IP "\s-1EV_H\s0 (h)" 4 |
4465 | .IX Item "EV_H (h)" |
4754 | .IX Item "EV_H (h)" |
… | |
… | |
4486 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
4775 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
4487 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
4776 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
4488 | additional independent event loops. Otherwise there will be no support |
4777 | additional independent event loops. Otherwise there will be no support |
4489 | for multiple event loops and there is no first event loop pointer |
4778 | for multiple event loops and there is no first event loop pointer |
4490 | argument. Instead, all functions act on the single default loop. |
4779 | argument. Instead, all functions act on the single default loop. |
|
|
4780 | .Sp |
|
|
4781 | Note that \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR will no longer provide a |
|
|
4782 | default loop when multiplicity is switched off \- you always have to |
|
|
4783 | initialise the loop manually in this case. |
4491 | .IP "\s-1EV_MINPRI\s0" 4 |
4784 | .IP "\s-1EV_MINPRI\s0" 4 |
4492 | .IX Item "EV_MINPRI" |
4785 | .IX Item "EV_MINPRI" |
4493 | .PD 0 |
4786 | .PD 0 |
4494 | .IP "\s-1EV_MAXPRI\s0" 4 |
4787 | .IP "\s-1EV_MAXPRI\s0" 4 |
4495 | .IX Item "EV_MAXPRI" |
4788 | .IX Item "EV_MAXPRI" |
… | |
… | |
4531 | \& #define EV_CHILD_ENABLE 1 |
4824 | \& #define EV_CHILD_ENABLE 1 |
4532 | \& #define EV_ASYNC_ENABLE 1 |
4825 | \& #define EV_ASYNC_ENABLE 1 |
4533 | .Ve |
4826 | .Ve |
4534 | .Sp |
4827 | .Sp |
4535 | The actual value is a bitset, it can be a combination of the following |
4828 | The actual value is a bitset, it can be a combination of the following |
4536 | values: |
4829 | values (by default, all of these are enabled): |
4537 | .RS 4 |
4830 | .RS 4 |
4538 | .ie n .IP "1 \- faster/larger code" 4 |
4831 | .ie n .IP "1 \- faster/larger code" 4 |
4539 | .el .IP "\f(CW1\fR \- faster/larger code" 4 |
4832 | .el .IP "\f(CW1\fR \- faster/larger code" 4 |
4540 | .IX Item "1 - faster/larger code" |
4833 | .IX Item "1 - faster/larger code" |
4541 | Use larger code to speed up some operations. |
4834 | Use larger code to speed up some operations. |
… | |
… | |
4544 | code size by roughly 30% on amd64). |
4837 | code size by roughly 30% on amd64). |
4545 | .Sp |
4838 | .Sp |
4546 | When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with |
4839 | When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with |
4547 | gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of |
4840 | gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of |
4548 | assertions. |
4841 | assertions. |
|
|
4842 | .Sp |
|
|
4843 | The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler |
|
|
4844 | (e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR). |
4549 | .ie n .IP "2 \- faster/larger data structures" 4 |
4845 | .ie n .IP "2 \- faster/larger data structures" 4 |
4550 | .el .IP "\f(CW2\fR \- faster/larger data structures" 4 |
4846 | .el .IP "\f(CW2\fR \- faster/larger data structures" 4 |
4551 | .IX Item "2 - faster/larger data structures" |
4847 | .IX Item "2 - faster/larger data structures" |
4552 | Replaces the small 2\-heap for timer management by a faster 4\-heap, larger |
4848 | Replaces the small 2\-heap for timer management by a faster 4\-heap, larger |
4553 | hash table sizes and so on. This will usually further increase code size |
4849 | hash table sizes and so on. This will usually further increase code size |
4554 | and can additionally have an effect on the size of data structures at |
4850 | and can additionally have an effect on the size of data structures at |
4555 | runtime. |
4851 | runtime. |
|
|
4852 | .Sp |
|
|
4853 | The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler |
|
|
4854 | (e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR). |
4556 | .ie n .IP "4 \- full \s-1API\s0 configuration" 4 |
4855 | .ie n .IP "4 \- full \s-1API\s0 configuration" 4 |
4557 | .el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4 |
4856 | .el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4 |
4558 | .IX Item "4 - full API configuration" |
4857 | .IX Item "4 - full API configuration" |
4559 | This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and |
4858 | This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and |
4560 | enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1). |
4859 | enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1). |
… | |
… | |
4592 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
4891 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
4593 | when you use \f(CW\*(C`\-Wl,\-\-gc\-sections \-ffunction\-sections\*(C'\fR) functions unused by |
4892 | when you use \f(CW\*(C`\-Wl,\-\-gc\-sections \-ffunction\-sections\*(C'\fR) functions unused by |
4594 | your program might be left out as well \- a binary starting a timer and an |
4893 | your program might be left out as well \- a binary starting a timer and an |
4595 | I/O watcher then might come out at only 5Kb. |
4894 | I/O watcher then might come out at only 5Kb. |
4596 | .RE |
4895 | .RE |
|
|
4896 | .IP "\s-1EV_API_STATIC\s0" 4 |
|
|
4897 | .IX Item "EV_API_STATIC" |
|
|
4898 | If this symbol is defined (by default it is not), then all identifiers |
|
|
4899 | will have static linkage. This means that libev will not export any |
|
|
4900 | identifiers, and you cannot link against libev anymore. This can be useful |
|
|
4901 | when you embed libev, only want to use libev functions in a single file, |
|
|
4902 | and do not want its identifiers to be visible. |
|
|
4903 | .Sp |
|
|
4904 | To use this, define \f(CW\*(C`EV_API_STATIC\*(C'\fR and include \fIev.c\fR in the file that |
|
|
4905 | wants to use libev. |
|
|
4906 | .Sp |
|
|
4907 | This option only works when libev is compiled with a C compiler, as \*(C+ |
|
|
4908 | doesn't support the required declaration syntax. |
4597 | .IP "\s-1EV_AVOID_STDIO\s0" 4 |
4909 | .IP "\s-1EV_AVOID_STDIO\s0" 4 |
4598 | .IX Item "EV_AVOID_STDIO" |
4910 | .IX Item "EV_AVOID_STDIO" |
4599 | If this is set to \f(CW1\fR at compiletime, then libev will avoid using stdio |
4911 | If this is set to \f(CW1\fR at compiletime, then libev will avoid using stdio |
4600 | functions (printf, scanf, perror etc.). This will increase the code size |
4912 | functions (printf, scanf, perror etc.). This will increase the code size |
4601 | somewhat, but if your program doesn't otherwise depend on stdio and your |
4913 | somewhat, but if your program doesn't otherwise depend on stdio and your |
… | |
… | |
4978 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
5290 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
4979 | model. Libev still offers limited functionality on this platform in |
5291 | model. Libev still offers limited functionality on this platform in |
4980 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
5292 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
4981 | descriptors. This only applies when using Win32 natively, not when using |
5293 | descriptors. This only applies when using Win32 natively, not when using |
4982 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
5294 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
4983 | as every compielr comes with a slightly differently broken/incompatible |
5295 | as every compiler comes with a slightly differently broken/incompatible |
4984 | environment. |
5296 | environment. |
4985 | .PP |
5297 | .PP |
4986 | Lifting these limitations would basically require the full |
5298 | Lifting these limitations would basically require the full |
4987 | re-implementation of the I/O system. If you are into this kind of thing, |
5299 | re-implementation of the I/O system. If you are into this kind of thing, |
4988 | then note that glib does exactly that for you in a very portable way (note |
5300 | then note that glib does exactly that for you in a very portable way (note |
… | |
… | |
5107 | thread\*(R" or will block signals process-wide, both behaviours would |
5419 | thread\*(R" or will block signals process-wide, both behaviours would |
5108 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
5420 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
5109 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
5421 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
5110 | .Sp |
5422 | .Sp |
5111 | The most portable way to handle signals is to block signals in all threads |
5423 | The most portable way to handle signals is to block signals in all threads |
5112 | except the initial one, and run the default loop in the initial thread as |
5424 | except the initial one, and run the signal handling loop in the initial |
5113 | well. |
5425 | thread as well. |
5114 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
5426 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
5115 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
5427 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
5116 | .IX Item "long must be large enough for common memory allocation sizes" |
5428 | .IX Item "long must be large enough for common memory allocation sizes" |
5117 | To improve portability and simplify its \s-1API\s0, libev uses \f(CW\*(C`long\*(C'\fR internally |
5429 | To improve portability and simplify its \s-1API\s0, libev uses \f(CW\*(C`long\*(C'\fR internally |
5118 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
5430 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
… | |
… | |
5124 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5436 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5125 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5437 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5126 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
5438 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
5127 | good enough for at least into the year 4000 with millisecond accuracy |
5439 | good enough for at least into the year 4000 with millisecond accuracy |
5128 | (the design goal for libev). This requirement is overfulfilled by |
5440 | (the design goal for libev). This requirement is overfulfilled by |
5129 | implementations using \s-1IEEE\s0 754, which is basically all existing ones. With |
5441 | implementations using \s-1IEEE\s0 754, which is basically all existing ones. |
|
|
5442 | .Sp |
5130 | \&\s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least 2200. |
5443 | With \s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least the |
|
|
5444 | year 2255 (and millisecond accuracy till the year 287396 \- by then, libev |
|
|
5445 | is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or |
|
|
5446 | something like that, just kidding). |
5131 | .PP |
5447 | .PP |
5132 | If you know of other additional requirements drop me a note. |
5448 | If you know of other additional requirements drop me a note. |
5133 | .SH "ALGORITHMIC COMPLEXITIES" |
5449 | .SH "ALGORITHMIC COMPLEXITIES" |
5134 | .IX Header "ALGORITHMIC COMPLEXITIES" |
5450 | .IX Header "ALGORITHMIC COMPLEXITIES" |
5135 | In this section the complexities of (many of) the algorithms used inside |
5451 | In this section the complexities of (many of) the algorithms used inside |
… | |
… | |
5189 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
5505 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
5190 | .IP "Processing signals: O(max_signal_number)" 4 |
5506 | .IP "Processing signals: O(max_signal_number)" 4 |
5191 | .IX Item "Processing signals: O(max_signal_number)" |
5507 | .IX Item "Processing signals: O(max_signal_number)" |
5192 | .PD |
5508 | .PD |
5193 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
5509 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
5194 | calls in the current loop iteration. Checking for async and signal events |
5510 | calls in the current loop iteration and the loop is currently |
|
|
5511 | blocked. Checking for async and signal events involves iterating over all |
5195 | involves iterating over all running async watchers or all signal numbers. |
5512 | running async watchers or all signal numbers. |
5196 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
5513 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
5197 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
5514 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
5198 | The major version 4 introduced some incompatible changes to the \s-1API\s0. |
5515 | The major version 4 introduced some incompatible changes to the \s-1API\s0. |
5199 | .PP |
5516 | .PP |
5200 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
5517 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
… | |
… | |
5203 | new \s-1API\s0 early than late. |
5520 | new \s-1API\s0 early than late. |
5204 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
5521 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
5205 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
5522 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
5206 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
5523 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
5207 | The backward compatibility mechanism can be controlled by |
5524 | The backward compatibility mechanism can be controlled by |
5208 | \&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1MACROS\s0\*(R" in \s-1PREPROCESSOR\s0 \s-1SYMBOLS\s0 in the \s-1EMBEDDING\s0 |
5525 | \&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0\*(R" in the \*(L"\s-1EMBEDDING\s0\*(R" |
5209 | section. |
5526 | section. |
5210 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
5527 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
5211 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
5528 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
5212 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
5529 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
5213 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
5530 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
… | |
… | |
5297 | .IX Item "real time" |
5614 | .IX Item "real time" |
5298 | The physical time that is observed. It is apparently strictly monotonic :) |
5615 | The physical time that is observed. It is apparently strictly monotonic :) |
5299 | .IP "wall-clock time" 4 |
5616 | .IP "wall-clock time" 4 |
5300 | .IX Item "wall-clock time" |
5617 | .IX Item "wall-clock time" |
5301 | The time and date as shown on clocks. Unlike real time, it can actually |
5618 | The time and date as shown on clocks. Unlike real time, it can actually |
5302 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
5619 | be wrong and jump forwards and backwards, e.g. when you adjust your |
5303 | clock. |
5620 | clock. |
5304 | .IP "watcher" 4 |
5621 | .IP "watcher" 4 |
5305 | .IX Item "watcher" |
5622 | .IX Item "watcher" |
5306 | A data structure that describes interest in certain events. Watchers need |
5623 | A data structure that describes interest in certain events. Watchers need |
5307 | to be started (attached to an event loop) before they can receive events. |
5624 | to be started (attached to an event loop) before they can receive events. |