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3 | .\" Standard preamble: |
4 | .\" ======================================================================== |
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124 | .\" ======================================================================== |
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125 | .\" |
126 | .IX Title "LIBEV 3" |
126 | .IX Title "LIBEV 3" |
127 | .TH LIBEV 3 "2011-01-11" "libev-4.03" "libev - high performance full featured event loop" |
127 | .TH LIBEV 3 "2012-05-06" "libev-4.11" "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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189 | \& ev_timer_start (loop, &timeout_watcher); |
189 | \& ev_timer_start (loop, &timeout_watcher); |
190 | \& |
190 | \& |
191 | \& // now wait for events to arrive |
191 | \& // now wait for events to arrive |
192 | \& ev_run (loop, 0); |
192 | \& ev_run (loop, 0); |
193 | \& |
193 | \& |
194 | \& // unloop was called, so exit |
194 | \& // break was called, so exit |
195 | \& return 0; |
195 | \& return 0; |
196 | \& } |
196 | \& } |
197 | .Ve |
197 | .Ve |
198 | .SH "ABOUT THIS DOCUMENT" |
198 | .SH "ABOUT THIS DOCUMENT" |
199 | .IX Header "ABOUT THIS DOCUMENT" |
199 | .IX Header "ABOUT THIS DOCUMENT" |
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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 |
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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 |
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|
305 | interrupted). Returns immediately if \f(CW\*(C`interval <= 0\*(C'\fR. |
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|
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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553 | example) that can't properly initialise their signal masks. |
559 | example) that can't properly initialise their signal masks. |
554 | .ie n .IP """EVFLAG_NOSIGMASK""" 4 |
560 | .ie n .IP """EVFLAG_NOSIGMASK""" 4 |
555 | .el .IP "\f(CWEVFLAG_NOSIGMASK\fR" 4 |
561 | .el .IP "\f(CWEVFLAG_NOSIGMASK\fR" 4 |
556 | .IX Item "EVFLAG_NOSIGMASK" |
562 | .IX Item "EVFLAG_NOSIGMASK" |
557 | When this flag is specified, then libev will avoid to modify the signal |
563 | 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 |
564 | mask. Specifically, this means you have to make sure signals are unblocked |
559 | when you want to receive them. |
565 | when you want to receive them. |
560 | .Sp |
566 | .Sp |
561 | This behaviour is useful when you want to do your own signal handling, or |
567 | 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 |
568 | want to handle signals only in specific threads and want to avoid libev |
563 | unblocking the signals. |
569 | unblocking the signals. |
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|
570 | .Sp |
|
|
571 | It's also required by \s-1POSIX\s0 in a threaded program, as libev calls |
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|
572 | \&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. |
564 | .Sp |
573 | .Sp |
565 | This flag's behaviour will become the default in future versions of libev. |
574 | This flag's behaviour will become the default in future versions of libev. |
566 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
575 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
567 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
576 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
568 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
577 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
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598 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
607 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
599 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
608 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
600 | Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
609 | Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
601 | kernels). |
610 | kernels). |
602 | .Sp |
611 | .Sp |
603 | For few fds, this backend is a bit little slower than poll and select, |
612 | For few fds, this backend is a bit little slower than poll and select, but |
604 | but it scales phenomenally better. While poll and select usually scale |
613 | it scales phenomenally better. While poll and select usually scale like |
605 | like O(total_fds) where n is the total number of fds (or the highest fd), |
614 | O(total_fds) where total_fds is the total number of fds (or the highest |
606 | epoll scales either O(1) or O(active_fds). |
615 | fd), epoll scales either O(1) or O(active_fds). |
607 | .Sp |
616 | .Sp |
608 | The epoll mechanism deserves honorable mention as the most misdesigned |
617 | The epoll mechanism deserves honorable mention as the most misdesigned |
609 | of the more advanced event mechanisms: mere annoyances include silently |
618 | of the more advanced event mechanisms: mere annoyances include silently |
610 | dropping file descriptors, requiring a system call per change per file |
619 | dropping file descriptors, requiring a system call per change per file |
611 | descriptor (and unnecessary guessing of parameters), problems with dup, |
620 | descriptor (and unnecessary guessing of parameters), problems with dup, |
… | |
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614 | 0.1ms) and so on. The biggest issue is fork races, however \- if a program |
623 | 0.1ms) and so on. The biggest issue is fork races, however \- if a program |
615 | forks then \fIboth\fR parent and child process have to recreate the epoll |
624 | forks then \fIboth\fR parent and child process have to recreate the epoll |
616 | set, which can take considerable time (one syscall per file descriptor) |
625 | set, which can take considerable time (one syscall per file descriptor) |
617 | and is of course hard to detect. |
626 | and is of course hard to detect. |
618 | .Sp |
627 | .Sp |
619 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, but |
628 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, |
620 | of course \fIdoesn't\fR, and epoll just loves to report events for totally |
629 | but of course \fIdoesn't\fR, and epoll just loves to report events for |
621 | \&\fIdifferent\fR file descriptors (even already closed ones, so one cannot |
630 | totally \fIdifferent\fR file descriptors (even already closed ones, so |
622 | even remove them from the set) than registered in the set (especially |
631 | one cannot even remove them from the set) than registered in the set |
623 | on \s-1SMP\s0 systems). Libev tries to counter these spurious notifications by |
632 | (especially on \s-1SMP\s0 systems). Libev tries to counter these spurious |
624 | employing an additional generation counter and comparing that against the |
633 | notifications by employing an additional generation counter and comparing |
625 | events to filter out spurious ones, recreating the set when required. Last |
634 | that against the events to filter out spurious ones, recreating the set |
|
|
635 | when required. Epoll also erroneously rounds down timeouts, but gives you |
|
|
636 | no way to know when and by how much, so sometimes you have to busy-wait |
|
|
637 | because epoll returns immediately despite a nonzero timeout. And last |
626 | not least, it also refuses to work with some file descriptors which work |
638 | not least, it also refuses to work with some file descriptors which work |
627 | perfectly fine with \f(CW\*(C`select\*(C'\fR (files, many character devices...). |
639 | perfectly fine with \f(CW\*(C`select\*(C'\fR (files, many character devices...). |
628 | .Sp |
640 | .Sp |
629 | Epoll is truly the train wreck analog among event poll mechanisms, |
641 | Epoll is truly the train wreck among event poll mechanisms, a frankenpoll, |
630 | a frankenpoll, cobbled together in a hurry, no thought to design or |
642 | cobbled together in a hurry, no thought to design or interaction with |
631 | interaction with others. |
643 | others. Oh, the pain, will it ever stop... |
632 | .Sp |
644 | .Sp |
633 | While stopping, setting and starting an I/O watcher in the same iteration |
645 | While stopping, setting and starting an I/O watcher in the same iteration |
634 | will result in some caching, there is still a system call per such |
646 | will result in some caching, there is still a system call per such |
635 | incident (because the same \fIfile descriptor\fR could point to a different |
647 | incident (because the same \fIfile descriptor\fR could point to a different |
636 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
648 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
… | |
… | |
673 | .Sp |
685 | .Sp |
674 | It scales in the same way as the epoll backend, but the interface to the |
686 | It scales in the same way as the epoll backend, but the interface to the |
675 | kernel is more efficient (which says nothing about its actual speed, of |
687 | kernel is more efficient (which says nothing about its actual speed, of |
676 | course). While stopping, setting and starting an I/O watcher does never |
688 | course). While stopping, setting and starting an I/O watcher does never |
677 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
689 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
678 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (but |
690 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (you |
679 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
691 | might have to leak fd's on fork, but it's more sane than epoll) and it |
680 | cases |
692 | drops fds silently in similarly hard-to-detect cases |
681 | .Sp |
693 | .Sp |
682 | This backend usually performs well under most conditions. |
694 | This backend usually performs well under most conditions. |
683 | .Sp |
695 | .Sp |
684 | While nominally embeddable in other event loops, this doesn't work |
696 | While nominally embeddable in other event loops, this doesn't work |
685 | everywhere, so you might need to test for this. And since it is broken |
697 | everywhere, so you might need to test for this. And since it is broken |
… | |
… | |
714 | among the OS-specific backends (I vastly prefer correctness over speed |
726 | among the OS-specific backends (I vastly prefer correctness over speed |
715 | hacks). |
727 | hacks). |
716 | .Sp |
728 | .Sp |
717 | On the negative side, the interface is \fIbizarre\fR \- so bizarre that |
729 | On the negative side, the interface is \fIbizarre\fR \- so bizarre that |
718 | even sun itself gets it wrong in their code examples: The event polling |
730 | even sun itself gets it wrong in their code examples: The event polling |
719 | function sometimes returning events to the caller even though an error |
731 | function sometimes returns events to the caller even though an error |
720 | occurred, but with no indication whether it has done so or not (yes, it's |
732 | occurred, but with no indication whether it has done so or not (yes, it's |
721 | even documented that way) \- deadly for edge-triggered interfaces where |
733 | even documented that way) \- deadly for edge-triggered interfaces where you |
722 | you absolutely have to know whether an event occurred or not because you |
734 | absolutely have to know whether an event occurred or not because you have |
723 | have to re-arm the watcher. |
735 | to re-arm the watcher. |
724 | .Sp |
736 | .Sp |
725 | Fortunately libev seems to be able to work around these idiocies. |
737 | Fortunately libev seems to be able to work around these idiocies. |
726 | .Sp |
738 | .Sp |
727 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
739 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
728 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
740 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
… | |
… | |
897 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
909 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
898 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
910 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
899 | .Sp |
911 | .Sp |
900 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
912 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
901 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
913 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
902 | .IP "ev_run (loop, int flags)" 4 |
914 | .IP "bool ev_run (loop, int flags)" 4 |
903 | .IX Item "ev_run (loop, int flags)" |
915 | .IX Item "bool ev_run (loop, int flags)" |
904 | Finally, this is it, the event handler. This function usually is called |
916 | Finally, this is it, the event handler. This function usually is called |
905 | after you have initialised all your watchers and you want to start |
917 | after you have initialised all your watchers and you want to start |
906 | handling events. It will ask the operating system for any new events, call |
918 | handling events. It will ask the operating system for any new events, call |
907 | the watcher callbacks, an then repeat the whole process indefinitely: This |
919 | the watcher callbacks, and then repeat the whole process indefinitely: This |
908 | is why event loops are called \fIloops\fR. |
920 | is why event loops are called \fIloops\fR. |
909 | .Sp |
921 | .Sp |
910 | If the flags argument is specified as \f(CW0\fR, it will keep handling events |
922 | If the flags argument is specified as \f(CW0\fR, it will keep handling events |
911 | until either no event watchers are active anymore or \f(CW\*(C`ev_break\*(C'\fR was |
923 | until either no event watchers are active anymore or \f(CW\*(C`ev_break\*(C'\fR was |
912 | called. |
924 | called. |
|
|
925 | .Sp |
|
|
926 | The return value is false if there are no more active watchers (which |
|
|
927 | usually means \*(L"all jobs done\*(R" or \*(L"deadlock\*(R"), and true in all other cases |
|
|
928 | (which usually means " you should call \f(CW\*(C`ev_run\*(C'\fR again"). |
913 | .Sp |
929 | .Sp |
914 | Please note that an explicit \f(CW\*(C`ev_break\*(C'\fR is usually better than |
930 | Please note that an explicit \f(CW\*(C`ev_break\*(C'\fR is usually better than |
915 | relying on all watchers to be stopped when deciding when a program has |
931 | relying on all watchers to be stopped when deciding when a program has |
916 | finished (especially in interactive programs), but having a program |
932 | finished (especially in interactive programs), but having a program |
917 | that automatically loops as long as it has to and no longer by virtue |
933 | that automatically loops as long as it has to and no longer by virtue |
918 | of relying on its watchers stopping correctly, that is truly a thing of |
934 | of relying on its watchers stopping correctly, that is truly a thing of |
919 | beauty. |
935 | beauty. |
920 | .Sp |
936 | .Sp |
921 | This function is also \fImostly\fR exception-safe \- you can break out of |
937 | This function is \fImostly\fR exception-safe \- you can break out of a |
922 | a \f(CW\*(C`ev_run\*(C'\fR call by calling \f(CW\*(C`longjmp\*(C'\fR in a callback, throwing a \*(C+ |
938 | \&\f(CW\*(C`ev_run\*(C'\fR call by calling \f(CW\*(C`longjmp\*(C'\fR in a callback, throwing a \*(C+ |
923 | exception and so on. This does not decrement the \f(CW\*(C`ev_depth\*(C'\fR value, nor |
939 | exception and so on. This does not decrement the \f(CW\*(C`ev_depth\*(C'\fR value, nor |
924 | will it clear any outstanding \f(CW\*(C`EVBREAK_ONE\*(C'\fR breaks. |
940 | will it clear any outstanding \f(CW\*(C`EVBREAK_ONE\*(C'\fR breaks. |
925 | .Sp |
941 | .Sp |
926 | A flags value of \f(CW\*(C`EVRUN_NOWAIT\*(C'\fR will look for new events, will handle |
942 | A flags value of \f(CW\*(C`EVRUN_NOWAIT\*(C'\fR will look for new events, will handle |
927 | those events and any already outstanding ones, but will not wait and |
943 | those events and any already outstanding ones, but will not wait and |
… | |
… | |
939 | This is useful if you are waiting for some external event in conjunction |
955 | This is useful if you are waiting for some external event in conjunction |
940 | with something not expressible using other libev watchers (i.e. "roll your |
956 | with something not expressible using other libev watchers (i.e. "roll your |
941 | 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 |
957 | 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 |
942 | usually a better approach for this kind of thing. |
958 | usually a better approach for this kind of thing. |
943 | .Sp |
959 | .Sp |
944 | Here are the gory details of what \f(CW\*(C`ev_run\*(C'\fR does: |
960 | Here are the gory details of what \f(CW\*(C`ev_run\*(C'\fR does (this is for your |
|
|
961 | understanding, not a guarantee that things will work exactly like this in |
|
|
962 | future versions): |
945 | .Sp |
963 | .Sp |
946 | .Vb 10 |
964 | .Vb 10 |
947 | \& \- Increment loop depth. |
965 | \& \- Increment loop depth. |
948 | \& \- Reset the ev_break status. |
966 | \& \- Reset the ev_break status. |
949 | \& \- Before the first iteration, call any pending watchers. |
967 | \& \- Before the first iteration, call any pending watchers. |
… | |
… | |
985 | .Sp |
1003 | .Sp |
986 | .Vb 4 |
1004 | .Vb 4 |
987 | \& ... queue jobs here, make sure they register event watchers as long |
1005 | \& ... queue jobs here, make sure they register event watchers as long |
988 | \& ... as they still have work to do (even an idle watcher will do..) |
1006 | \& ... as they still have work to do (even an idle watcher will do..) |
989 | \& ev_run (my_loop, 0); |
1007 | \& ev_run (my_loop, 0); |
990 | \& ... jobs done or somebody called unloop. yeah! |
1008 | \& ... jobs done or somebody called break. yeah! |
991 | .Ve |
1009 | .Ve |
992 | .IP "ev_break (loop, how)" 4 |
1010 | .IP "ev_break (loop, how)" 4 |
993 | .IX Item "ev_break (loop, how)" |
1011 | .IX Item "ev_break (loop, how)" |
994 | Can be used to make a call to \f(CW\*(C`ev_run\*(C'\fR return early (but only after it |
1012 | Can be used to make a call to \f(CW\*(C`ev_run\*(C'\fR return early (but only after it |
995 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
1013 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
… | |
… | |
1064 | overhead for the actual polling but can deliver many events at once. |
1082 | overhead for the actual polling but can deliver many events at once. |
1065 | .Sp |
1083 | .Sp |
1066 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
1084 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
1067 | time collecting I/O events, so you can handle more events per iteration, |
1085 | time collecting I/O events, so you can handle more events per iteration, |
1068 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
1086 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
1069 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
1087 | \&\f(CW\*(C`ev_timer\*(C'\fR) will not be affected. Setting this to a non-null value will |
1070 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
1088 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
1071 | sleep time ensures that libev will not poll for I/O events more often then |
1089 | sleep time ensures that libev will not poll for I/O events more often then |
1072 | once per this interval, on average. |
1090 | once per this interval, on average (as long as the host time resolution is |
|
|
1091 | good enough). |
1073 | .Sp |
1092 | .Sp |
1074 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
1093 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
1075 | to spend more time collecting timeouts, at the expense of increased |
1094 | to spend more time collecting timeouts, at the expense of increased |
1076 | latency/jitter/inexactness (the watcher callback will be called |
1095 | latency/jitter/inexactness (the watcher callback will be called |
1077 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
1096 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
… | |
… | |
1121 | this callback instead. This is useful, for example, when you want to |
1140 | this callback instead. This is useful, for example, when you want to |
1122 | invoke the actual watchers inside another context (another thread etc.). |
1141 | invoke the actual watchers inside another context (another thread etc.). |
1123 | .Sp |
1142 | .Sp |
1124 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
1143 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
1125 | callback. |
1144 | callback. |
1126 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0), void (*acquire)(\s-1EV_P\s0))" 4 |
1145 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0) throw (), void (*acquire)(\s-1EV_P\s0) throw ())" 4 |
1127 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))" |
1146 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P) throw (), void (*acquire)(EV_P) throw ())" |
1128 | Sometimes you want to share the same loop between multiple threads. This |
1147 | Sometimes you want to share the same loop between multiple threads. This |
1129 | can be done relatively simply by putting mutex_lock/unlock calls around |
1148 | can be done relatively simply by putting mutex_lock/unlock calls around |
1130 | each call to a libev function. |
1149 | each call to a libev function. |
1131 | .Sp |
1150 | .Sp |
1132 | However, \f(CW\*(C`ev_run\*(C'\fR can run an indefinite time, so it is not feasible |
1151 | However, \f(CW\*(C`ev_run\*(C'\fR can run an indefinite time, so it is not feasible |
1133 | to wait for it to return. One way around this is to wake up the event |
1152 | to wait for it to return. One way around this is to wake up the event |
1134 | loop via \f(CW\*(C`ev_break\*(C'\fR and \f(CW\*(C`av_async_send\*(C'\fR, another way is to set these |
1153 | loop via \f(CW\*(C`ev_break\*(C'\fR and \f(CW\*(C`ev_async_send\*(C'\fR, another way is to set these |
1135 | \&\fIrelease\fR and \fIacquire\fR callbacks on the loop. |
1154 | \&\fIrelease\fR and \fIacquire\fR callbacks on the loop. |
1136 | .Sp |
1155 | .Sp |
1137 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
1156 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
1138 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
1157 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
1139 | afterwards. |
1158 | afterwards. |
… | |
… | |
1280 | .PD 0 |
1299 | .PD 0 |
1281 | .ie n .IP """EV_CHECK""" 4 |
1300 | .ie n .IP """EV_CHECK""" 4 |
1282 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1301 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1283 | .IX Item "EV_CHECK" |
1302 | .IX Item "EV_CHECK" |
1284 | .PD |
1303 | .PD |
1285 | All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_run\*(C'\fR starts |
1304 | All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_run\*(C'\fR starts to |
1286 | to gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are invoked just after |
1305 | gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are queued (not invoked) |
1287 | \&\f(CW\*(C`ev_run\*(C'\fR has gathered them, but before it invokes any callbacks for any |
1306 | just after \f(CW\*(C`ev_run\*(C'\fR has gathered them, but before it queues any callbacks |
|
|
1307 | for any received events. That means \f(CW\*(C`ev_prepare\*(C'\fR watchers are the last |
|
|
1308 | watchers invoked before the event loop sleeps or polls for new events, and |
|
|
1309 | \&\f(CW\*(C`ev_check\*(C'\fR watchers will be invoked before any other watchers of the same |
|
|
1310 | or lower priority within an event loop iteration. |
|
|
1311 | .Sp |
1288 | received events. Callbacks of both watcher types can start and stop as |
1312 | Callbacks of both watcher types can start and stop as many watchers as |
1289 | many watchers as they want, and all of them will be taken into account |
1313 | they want, and all of them will be taken into account (for example, a |
1290 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
1314 | \&\f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep \f(CW\*(C`ev_run\*(C'\fR from |
1291 | \&\f(CW\*(C`ev_run\*(C'\fR from blocking). |
1315 | blocking). |
1292 | .ie n .IP """EV_EMBED""" 4 |
1316 | .ie n .IP """EV_EMBED""" 4 |
1293 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1317 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1294 | .IX Item "EV_EMBED" |
1318 | .IX Item "EV_EMBED" |
1295 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1319 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1296 | .ie n .IP """EV_FORK""" 4 |
1320 | .ie n .IP """EV_FORK""" 4 |
… | |
… | |
1417 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
1441 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
1418 | it). |
1442 | it). |
1419 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1443 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1420 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1444 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1421 | Returns the callback currently set on the watcher. |
1445 | Returns the callback currently set on the watcher. |
1422 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1446 | .IP "ev_set_cb (ev_TYPE *watcher, callback)" 4 |
1423 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1447 | .IX Item "ev_set_cb (ev_TYPE *watcher, callback)" |
1424 | Change the callback. You can change the callback at virtually any time |
1448 | Change the callback. You can change the callback at virtually any time |
1425 | (modulo threads). |
1449 | (modulo threads). |
1426 | .IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 |
1450 | .IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 |
1427 | .IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" |
1451 | .IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" |
1428 | .PD 0 |
1452 | .PD 0 |
… | |
… | |
1486 | active, pending and so on. In this section these states and the rules to |
1510 | active, pending and so on. In this section these states and the rules to |
1487 | transition between them will be described in more detail \- and while these |
1511 | transition between them will be described in more detail \- and while these |
1488 | rules might look complicated, they usually do \*(L"the right thing\*(R". |
1512 | rules might look complicated, they usually do \*(L"the right thing\*(R". |
1489 | .IP "initialiased" 4 |
1513 | .IP "initialiased" 4 |
1490 | .IX Item "initialiased" |
1514 | .IX Item "initialiased" |
1491 | Before a watcher can be registered with the event looop it has to be |
1515 | Before a watcher can be registered with the event loop it has to be |
1492 | initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to |
1516 | initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to |
1493 | \&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. |
1517 | \&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. |
1494 | .Sp |
1518 | .Sp |
1495 | In this state it is simply some block of memory that is suitable for use |
1519 | In this state it is simply some block of memory that is suitable for |
1496 | in an event loop. It can be moved around, freed, reused etc. at will. |
1520 | use in an event loop. It can be moved around, freed, reused etc. at |
|
|
1521 | will \- as long as you either keep the memory contents intact, or call |
|
|
1522 | \&\f(CW\*(C`ev_TYPE_init\*(C'\fR again. |
1497 | .IP "started/running/active" 4 |
1523 | .IP "started/running/active" 4 |
1498 | .IX Item "started/running/active" |
1524 | .IX Item "started/running/active" |
1499 | Once a watcher has been started with a call to \f(CW\*(C`ev_TYPE_start\*(C'\fR it becomes |
1525 | Once a watcher has been started with a call to \f(CW\*(C`ev_TYPE_start\*(C'\fR it becomes |
1500 | property of the event loop, and is actively waiting for events. While in |
1526 | property of the event loop, and is actively waiting for events. While in |
1501 | this state it cannot be accessed (except in a few documented ways), moved, |
1527 | this state it cannot be accessed (except in a few documented ways), moved, |
… | |
… | |
1526 | latter will clear any pending state the watcher might be in, regardless |
1552 | latter will clear any pending state the watcher might be in, regardless |
1527 | of whether it was active or not, so stopping a watcher explicitly before |
1553 | of whether it was active or not, so stopping a watcher explicitly before |
1528 | freeing it is often a good idea. |
1554 | freeing it is often a good idea. |
1529 | .Sp |
1555 | .Sp |
1530 | While stopped (and not pending) the watcher is essentially in the |
1556 | While stopped (and not pending) the watcher is essentially in the |
1531 | initialised state, that is it can be reused, moved, modified in any way |
1557 | initialised state, that is, it can be reused, moved, modified in any way |
1532 | you wish. |
1558 | you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR |
|
|
1559 | it again). |
1533 | .SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
1560 | .SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
1534 | .IX Subsection "WATCHER PRIORITY MODELS" |
1561 | .IX Subsection "WATCHER PRIORITY MODELS" |
1535 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1562 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1536 | integers that influence the ordering of event callback invocation |
1563 | integers that influence the ordering of event callback invocation |
1537 | between watchers in some way, all else being equal. |
1564 | between watchers in some way, all else being equal. |
… | |
… | |
1865 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1892 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1866 | monotonic clock option helps a lot here). |
1893 | monotonic clock option helps a lot here). |
1867 | .PP |
1894 | .PP |
1868 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1895 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1869 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1896 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1870 | might introduce a small delay). If multiple timers become ready during the |
1897 | might introduce a small delay, see \*(L"the special problem of being too |
|
|
1898 | early\*(R", below). If multiple timers become ready during the same loop |
1871 | same loop iteration then the ones with earlier time-out values are invoked |
1899 | iteration then the ones with earlier time-out values are invoked before |
1872 | before ones of the same priority with later time-out values (but this is |
1900 | ones of the same priority with later time-out values (but this is no |
1873 | no longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
1901 | longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
1874 | .PP |
1902 | .PP |
1875 | \fIBe smart about timeouts\fR |
1903 | \fIBe smart about timeouts\fR |
1876 | .IX Subsection "Be smart about timeouts" |
1904 | .IX Subsection "Be smart about timeouts" |
1877 | .PP |
1905 | .PP |
1878 | Many real-world problems involve some kind of timeout, usually for error |
1906 | Many real-world problems involve some kind of timeout, usually for error |
… | |
… | |
1960 | .Sp |
1988 | .Sp |
1961 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
1989 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
1962 | but remember the time of last activity, and check for a real timeout only |
1990 | but remember the time of last activity, and check for a real timeout only |
1963 | within the callback: |
1991 | within the callback: |
1964 | .Sp |
1992 | .Sp |
1965 | .Vb 1 |
1993 | .Vb 3 |
|
|
1994 | \& ev_tstamp timeout = 60.; |
1966 | \& ev_tstamp last_activity; // time of last activity |
1995 | \& ev_tstamp last_activity; // time of last activity |
|
|
1996 | \& ev_timer timer; |
1967 | \& |
1997 | \& |
1968 | \& static void |
1998 | \& static void |
1969 | \& callback (EV_P_ ev_timer *w, int revents) |
1999 | \& callback (EV_P_ ev_timer *w, int revents) |
1970 | \& { |
2000 | \& { |
1971 | \& ev_tstamp now = ev_now (EV_A); |
2001 | \& // calculate when the timeout would happen |
1972 | \& ev_tstamp timeout = last_activity + 60.; |
2002 | \& ev_tstamp after = last_activity \- ev_now (EV_A) + timeout; |
1973 | \& |
2003 | \& |
1974 | \& // if last_activity + 60. is older than now, we did time out |
2004 | \& // if negative, it means we the timeout already occurred |
1975 | \& if (timeout < now) |
2005 | \& if (after < 0.) |
1976 | \& { |
2006 | \& { |
1977 | \& // timeout occurred, take action |
2007 | \& // timeout occurred, take action |
1978 | \& } |
2008 | \& } |
1979 | \& else |
2009 | \& else |
1980 | \& { |
2010 | \& { |
1981 | \& // callback was invoked, but there was some activity, re\-arm |
2011 | \& // callback was invoked, but there was some recent |
1982 | \& // the watcher to fire in last_activity + 60, which is |
2012 | \& // activity. simply restart the timer to time out |
1983 | \& // guaranteed to be in the future, so "again" is positive: |
2013 | \& // after "after" seconds, which is the earliest time |
1984 | \& w\->repeat = timeout \- now; |
2014 | \& // the timeout can occur. |
|
|
2015 | \& ev_timer_set (w, after, 0.); |
1985 | \& ev_timer_again (EV_A_ w); |
2016 | \& ev_timer_start (EV_A_ w); |
1986 | \& } |
2017 | \& } |
1987 | \& } |
2018 | \& } |
1988 | .Ve |
2019 | .Ve |
1989 | .Sp |
2020 | .Sp |
1990 | To summarise the callback: first calculate the real timeout (defined |
2021 | To summarise the callback: first calculate in how many seconds the |
1991 | as \*(L"60 seconds after the last activity\*(R"), then check if that time has |
2022 | timeout will occur (by calculating the absolute time when it would occur, |
1992 | been reached, which means something \fIdid\fR, in fact, time out. Otherwise |
2023 | \&\f(CW\*(C`last_activity + timeout\*(C'\fR, and subtracting the current time, \f(CW\*(C`ev_now |
1993 | the callback was invoked too early (\f(CW\*(C`timeout\*(C'\fR is in the future), so |
2024 | (EV_A)\*(C'\fR from that). |
1994 | re-schedule the timer to fire at that future time, to see if maybe we have |
|
|
1995 | a timeout then. |
|
|
1996 | .Sp |
2025 | .Sp |
1997 | Note how \f(CW\*(C`ev_timer_again\*(C'\fR is used, taking advantage of the |
2026 | If this value is negative, then we are already past the timeout, i.e. we |
1998 | \&\f(CW\*(C`ev_timer_again\*(C'\fR optimisation when the timer is already running. |
2027 | timed out, and need to do whatever is needed in this case. |
|
|
2028 | .Sp |
|
|
2029 | Otherwise, we now the earliest time at which the timeout would trigger, |
|
|
2030 | and simply start the timer with this timeout value. |
|
|
2031 | .Sp |
|
|
2032 | In other words, each time the callback is invoked it will check whether |
|
|
2033 | the timeout occurred. If not, it will simply reschedule itself to check |
|
|
2034 | again at the earliest time it could time out. Rinse. Repeat. |
1999 | .Sp |
2035 | .Sp |
2000 | This scheme causes more callback invocations (about one every 60 seconds |
2036 | This scheme causes more callback invocations (about one every 60 seconds |
2001 | minus half the average time between activity), but virtually no calls to |
2037 | minus half the average time between activity), but virtually no calls to |
2002 | libev to change the timeout. |
2038 | libev to change the timeout. |
2003 | .Sp |
2039 | .Sp |
2004 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
2040 | To start the machinery, simply initialise the watcher and set |
2005 | to the current time (meaning we just have some activity :), then call the |
2041 | \&\f(CW\*(C`last_activity\*(C'\fR to the current time (meaning there was some activity just |
2006 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
2042 | now), then call the callback, which will \*(L"do the right thing\*(R" and start |
|
|
2043 | the timer: |
2007 | .Sp |
2044 | .Sp |
2008 | .Vb 3 |
2045 | .Vb 3 |
|
|
2046 | \& last_activity = ev_now (EV_A); |
2009 | \& ev_init (timer, callback); |
2047 | \& ev_init (&timer, callback); |
2010 | \& last_activity = ev_now (loop); |
2048 | \& callback (EV_A_ &timer, 0); |
2011 | \& callback (loop, timer, EV_TIMER); |
|
|
2012 | .Ve |
2049 | .Ve |
2013 | .Sp |
2050 | .Sp |
2014 | And when there is some activity, simply store the current time in |
2051 | When there is some activity, simply store the current time in |
2015 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
2052 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
2016 | .Sp |
2053 | .Sp |
2017 | .Vb 1 |
2054 | .Vb 2 |
|
|
2055 | \& if (activity detected) |
2018 | \& last_activity = ev_now (loop); |
2056 | \& last_activity = ev_now (EV_A); |
|
|
2057 | .Ve |
|
|
2058 | .Sp |
|
|
2059 | When your timeout value changes, then the timeout can be changed by simply |
|
|
2060 | providing a new value, stopping the timer and calling the callback, which |
|
|
2061 | will again do the right thing (for example, time out immediately :). |
|
|
2062 | .Sp |
|
|
2063 | .Vb 3 |
|
|
2064 | \& timeout = new_value; |
|
|
2065 | \& ev_timer_stop (EV_A_ &timer); |
|
|
2066 | \& callback (EV_A_ &timer, 0); |
2019 | .Ve |
2067 | .Ve |
2020 | .Sp |
2068 | .Sp |
2021 | This technique is slightly more complex, but in most cases where the |
2069 | This technique is slightly more complex, but in most cases where the |
2022 | time-out is unlikely to be triggered, much more efficient. |
2070 | time-out is unlikely to be triggered, much more efficient. |
2023 | .Sp |
|
|
2024 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
|
|
2025 | callback :) \- just change the timeout and invoke the callback, which will |
|
|
2026 | fix things for you. |
|
|
2027 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
2071 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
2028 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
2072 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
2029 | If there is not one request, but many thousands (millions...), all |
2073 | If there is not one request, but many thousands (millions...), all |
2030 | employing some kind of timeout with the same timeout value, then one can |
2074 | employing some kind of timeout with the same timeout value, then one can |
2031 | do even better: |
2075 | do even better: |
… | |
… | |
2055 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
2099 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
2056 | rather complicated, but extremely efficient, something that really pays |
2100 | rather complicated, but extremely efficient, something that really pays |
2057 | off after the first million or so of active timers, i.e. it's usually |
2101 | off after the first million or so of active timers, i.e. it's usually |
2058 | overkill :) |
2102 | overkill :) |
2059 | .PP |
2103 | .PP |
|
|
2104 | \fIThe special problem of being too early\fR |
|
|
2105 | .IX Subsection "The special problem of being too early" |
|
|
2106 | .PP |
|
|
2107 | If you ask a timer to call your callback after three seconds, then |
|
|
2108 | you expect it to be invoked after three seconds \- but of course, this |
|
|
2109 | cannot be guaranteed to infinite precision. Less obviously, it cannot be |
|
|
2110 | guaranteed to any precision by libev \- imagine somebody suspending the |
|
|
2111 | process with a \s-1STOP\s0 signal for a few hours for example. |
|
|
2112 | .PP |
|
|
2113 | So, libev tries to invoke your callback as soon as possible \fIafter\fR the |
|
|
2114 | delay has occurred, but cannot guarantee this. |
|
|
2115 | .PP |
|
|
2116 | A less obvious failure mode is calling your callback too early: many event |
|
|
2117 | loops compare timestamps with a \*(L"elapsed delay >= requested delay\*(R", but |
|
|
2118 | this can cause your callback to be invoked much earlier than you would |
|
|
2119 | expect. |
|
|
2120 | .PP |
|
|
2121 | To see why, imagine a system with a clock that only offers full second |
|
|
2122 | resolution (think windows if you can't come up with a broken enough \s-1OS\s0 |
|
|
2123 | yourself). If you schedule a one-second timer at the time 500.9, then the |
|
|
2124 | event loop will schedule your timeout to elapse at a system time of 500 |
|
|
2125 | (500.9 truncated to the resolution) + 1, or 501. |
|
|
2126 | .PP |
|
|
2127 | If an event library looks at the timeout 0.1s later, it will see \*(L"501 >= |
|
|
2128 | 501\*(R" and invoke the callback 0.1s after it was started, even though a |
|
|
2129 | one-second delay was requested \- this is being \*(L"too early\*(R", despite best |
|
|
2130 | intentions. |
|
|
2131 | .PP |
|
|
2132 | This is the reason why libev will never invoke the callback if the elapsed |
|
|
2133 | delay equals the requested delay, but only when the elapsed delay is |
|
|
2134 | larger than the requested delay. In the example above, libev would only invoke |
|
|
2135 | the callback at system time 502, or 1.1s after the timer was started. |
|
|
2136 | .PP |
|
|
2137 | So, while libev cannot guarantee that your callback will be invoked |
|
|
2138 | exactly when requested, it \fIcan\fR and \fIdoes\fR guarantee that the requested |
|
|
2139 | delay has actually elapsed, or in other words, it always errs on the \*(L"too |
|
|
2140 | late\*(R" side of things. |
|
|
2141 | .PP |
2060 | \fIThe special problem of time updates\fR |
2142 | \fIThe special problem of time updates\fR |
2061 | .IX Subsection "The special problem of time updates" |
2143 | .IX Subsection "The special problem of time updates" |
2062 | .PP |
2144 | .PP |
2063 | Establishing the current time is a costly operation (it usually takes at |
2145 | Establishing the current time is a costly operation (it usually takes |
2064 | least two system calls): \s-1EV\s0 therefore updates its idea of the current |
2146 | at least one system call): \s-1EV\s0 therefore updates its idea of the current |
2065 | time only before and after \f(CW\*(C`ev_run\*(C'\fR collects new events, which causes a |
2147 | time only before and after \f(CW\*(C`ev_run\*(C'\fR collects new events, which causes a |
2066 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
2148 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
2067 | lots of events in one iteration. |
2149 | lots of events in one iteration. |
2068 | .PP |
2150 | .PP |
2069 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2151 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
… | |
… | |
2077 | .Ve |
2159 | .Ve |
2078 | .PP |
2160 | .PP |
2079 | If the event loop is suspended for a long time, you can also force an |
2161 | If the event loop is suspended for a long time, you can also force an |
2080 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2162 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2081 | ()\*(C'\fR. |
2163 | ()\*(C'\fR. |
|
|
2164 | .PP |
|
|
2165 | \fIThe special problem of unsynchronised clocks\fR |
|
|
2166 | .IX Subsection "The special problem of unsynchronised clocks" |
|
|
2167 | .PP |
|
|
2168 | Modern systems have a variety of clocks \- libev itself uses the normal |
|
|
2169 | \&\*(L"wall clock\*(R" clock and, if available, the monotonic clock (to avoid time |
|
|
2170 | jumps). |
|
|
2171 | .PP |
|
|
2172 | Neither of these clocks is synchronised with each other or any other clock |
|
|
2173 | on the system, so \f(CW\*(C`ev_time ()\*(C'\fR might return a considerably different time |
|
|
2174 | than \f(CW\*(C`gettimeofday ()\*(C'\fR or \f(CW\*(C`time ()\*(C'\fR. On a GNU/Linux system, for example, |
|
|
2175 | a call to \f(CW\*(C`gettimeofday\*(C'\fR might return a second count that is one higher |
|
|
2176 | than a directly following call to \f(CW\*(C`time\*(C'\fR. |
|
|
2177 | .PP |
|
|
2178 | The moral of this is to only compare libev-related timestamps with |
|
|
2179 | \&\f(CW\*(C`ev_time ()\*(C'\fR and \f(CW\*(C`ev_now ()\*(C'\fR, at least if you want better precision than |
|
|
2180 | a second or so. |
|
|
2181 | .PP |
|
|
2182 | One more problem arises due to this lack of synchronisation: if libev uses |
|
|
2183 | the system monotonic clock and you compare timestamps from \f(CW\*(C`ev_time\*(C'\fR |
|
|
2184 | or \f(CW\*(C`ev_now\*(C'\fR from when you started your timer and when your callback is |
|
|
2185 | invoked, you will find that sometimes the callback is a bit \*(L"early\*(R". |
|
|
2186 | .PP |
|
|
2187 | This is because \f(CW\*(C`ev_timer\*(C'\fRs work in real time, not wall clock time, so |
|
|
2188 | libev makes sure your callback is not invoked before the delay happened, |
|
|
2189 | \&\fImeasured according to the real time\fR, not the system clock. |
|
|
2190 | .PP |
|
|
2191 | If your timeouts are based on a physical timescale (e.g. \*(L"time out this |
|
|
2192 | connection after 100 seconds\*(R") then this shouldn't bother you as it is |
|
|
2193 | exactly the right behaviour. |
|
|
2194 | .PP |
|
|
2195 | If you want to compare wall clock/system timestamps to your timers, then |
|
|
2196 | you need to use \f(CW\*(C`ev_periodic\*(C'\fRs, as these are based on the wall clock |
|
|
2197 | time, where your comparisons will always generate correct results. |
2082 | .PP |
2198 | .PP |
2083 | \fIThe special problems of suspended animation\fR |
2199 | \fIThe special problems of suspended animation\fR |
2084 | .IX Subsection "The special problems of suspended animation" |
2200 | .IX Subsection "The special problems of suspended animation" |
2085 | .PP |
2201 | .PP |
2086 | When you leave the server world it is quite customary to hit machines that |
2202 | When you leave the server world it is quite customary to hit machines that |
… | |
… | |
2130 | trigger at exactly 10 second intervals. If, however, your program cannot |
2246 | trigger at exactly 10 second intervals. If, however, your program cannot |
2131 | keep up with the timer (because it takes longer than those 10 seconds to |
2247 | keep up with the timer (because it takes longer than those 10 seconds to |
2132 | do stuff) the timer will not fire more than once per event loop iteration. |
2248 | do stuff) the timer will not fire more than once per event loop iteration. |
2133 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
2249 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
2134 | .IX Item "ev_timer_again (loop, ev_timer *)" |
2250 | .IX Item "ev_timer_again (loop, ev_timer *)" |
2135 | This will act as if the timer timed out and restart it again if it is |
2251 | This will act as if the timer timed out, and restarts it again if it is |
2136 | repeating. The exact semantics are: |
2252 | repeating. It basically works like calling \f(CW\*(C`ev_timer_stop\*(C'\fR, updating the |
|
|
2253 | timeout to the \f(CW\*(C`repeat\*(C'\fR value and calling \f(CW\*(C`ev_timer_start\*(C'\fR. |
2137 | .Sp |
2254 | .Sp |
|
|
2255 | The exact semantics are as in the following rules, all of which will be |
|
|
2256 | applied to the watcher: |
|
|
2257 | .RS 4 |
2138 | If the timer is pending, its pending status is cleared. |
2258 | .IP "If the timer is pending, the pending status is always cleared." 4 |
2139 | .Sp |
2259 | .IX Item "If the timer is pending, the pending status is always cleared." |
|
|
2260 | .PD 0 |
2140 | If the timer is started but non-repeating, stop it (as if it timed out). |
2261 | .IP "If the timer is started but non-repeating, stop it (as if it timed out, without invoking it)." 4 |
2141 | .Sp |
2262 | .IX Item "If the timer is started but non-repeating, stop it (as if it timed out, without invoking it)." |
2142 | If the timer is repeating, either start it if necessary (with the |
2263 | .ie n .IP "If the timer is repeating, make the ""repeat"" value the new timeout and start the timer, if necessary." 4 |
2143 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
2264 | .el .IP "If the timer is repeating, make the \f(CWrepeat\fR value the new timeout and start the timer, if necessary." 4 |
|
|
2265 | .IX Item "If the timer is repeating, make the repeat value the new timeout and start the timer, if necessary." |
|
|
2266 | .RE |
|
|
2267 | .RS 4 |
|
|
2268 | .PD |
2144 | .Sp |
2269 | .Sp |
2145 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
2270 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
2146 | usage example. |
2271 | usage example. |
|
|
2272 | .RE |
2147 | .IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4 |
2273 | .IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4 |
2148 | .IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)" |
2274 | .IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)" |
2149 | Returns the remaining time until a timer fires. If the timer is active, |
2275 | Returns the remaining time until a timer fires. If the timer is active, |
2150 | then this time is relative to the current event loop time, otherwise it's |
2276 | then this time is relative to the current event loop time, otherwise it's |
2151 | the timeout value currently configured. |
2277 | the timeout value currently configured. |
… | |
… | |
2271 | .Sp |
2397 | .Sp |
2272 | Another way to think about it (for the mathematically inclined) is that |
2398 | Another way to think about it (for the mathematically inclined) is that |
2273 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2399 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2274 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
2400 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
2275 | .Sp |
2401 | .Sp |
2276 | For numerical stability it is preferable that the \f(CW\*(C`offset\*(C'\fR value is near |
2402 | The \f(CW\*(C`interval\*(C'\fR \fI\s-1MUST\s0\fR be positive, and for numerical stability, the |
2277 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
2403 | interval value should be higher than \f(CW\*(C`1/8192\*(C'\fR (which is around 100 |
2278 | this value, and in fact is often specified as zero. |
2404 | microseconds) and \f(CW\*(C`offset\*(C'\fR should be higher than \f(CW0\fR and should have |
|
|
2405 | at most a similar magnitude as the current time (say, within a factor of |
|
|
2406 | ten). Typical values for offset are, in fact, \f(CW0\fR or something between |
|
|
2407 | \&\f(CW0\fR and \f(CW\*(C`interval\*(C'\fR, which is also the recommended range. |
2279 | .Sp |
2408 | .Sp |
2280 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2409 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2281 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
2410 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
2282 | will of course deteriorate. Libev itself tries to be exact to be about one |
2411 | will of course deteriorate. Libev itself tries to be exact to be about one |
2283 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
2412 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
… | |
… | |
2429 | .IX Subsection "The special problem of inheritance over fork/execve/pthread_create" |
2558 | .IX Subsection "The special problem of inheritance over fork/execve/pthread_create" |
2430 | .PP |
2559 | .PP |
2431 | Both the signal mask (\f(CW\*(C`sigprocmask\*(C'\fR) and the signal disposition |
2560 | Both the signal mask (\f(CW\*(C`sigprocmask\*(C'\fR) and the signal disposition |
2432 | (\f(CW\*(C`sigaction\*(C'\fR) are unspecified after starting a signal watcher (and after |
2561 | (\f(CW\*(C`sigaction\*(C'\fR) are unspecified after starting a signal watcher (and after |
2433 | stopping it again), that is, libev might or might not block the signal, |
2562 | stopping it again), that is, libev might or might not block the signal, |
2434 | and might or might not set or restore the installed signal handler. |
2563 | and might or might not set or restore the installed signal handler (but |
|
|
2564 | see \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR). |
2435 | .PP |
2565 | .PP |
2436 | While this does not matter for the signal disposition (libev never |
2566 | While this does not matter for the signal disposition (libev never |
2437 | sets signals to \f(CW\*(C`SIG_IGN\*(C'\fR, so handlers will be reset to \f(CW\*(C`SIG_DFL\*(C'\fR on |
2567 | sets signals to \f(CW\*(C`SIG_IGN\*(C'\fR, so handlers will be reset to \f(CW\*(C`SIG_DFL\*(C'\fR on |
2438 | \&\f(CW\*(C`execve\*(C'\fR), this matters for the signal mask: many programs do not expect |
2568 | \&\f(CW\*(C`execve\*(C'\fR), this matters for the signal mask: many programs do not expect |
2439 | certain signals to be blocked. |
2569 | certain signals to be blocked. |
… | |
… | |
2852 | Apart from keeping your process non-blocking (which is a useful |
2982 | Apart from keeping your process non-blocking (which is a useful |
2853 | effect on its own sometimes), idle watchers are a good place to do |
2983 | effect on its own sometimes), idle watchers are a good place to do |
2854 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2984 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2855 | event loop has handled all outstanding events. |
2985 | event loop has handled all outstanding events. |
2856 | .PP |
2986 | .PP |
|
|
2987 | \fIAbusing an \f(CI\*(C`ev_idle\*(C'\fI watcher for its side-effect\fR |
|
|
2988 | .IX Subsection "Abusing an ev_idle watcher for its side-effect" |
|
|
2989 | .PP |
|
|
2990 | As long as there is at least one active idle watcher, libev will never |
|
|
2991 | sleep unnecessarily. Or in other words, it will loop as fast as possible. |
|
|
2992 | For this to work, the idle watcher doesn't need to be invoked at all \- the |
|
|
2993 | lowest priority will do. |
|
|
2994 | .PP |
|
|
2995 | This mode of operation can be useful together with an \f(CW\*(C`ev_check\*(C'\fR watcher, |
|
|
2996 | to do something on each event loop iteration \- for example to balance load |
|
|
2997 | between different connections. |
|
|
2998 | .PP |
|
|
2999 | See \*(L"Abusing an ev_check watcher for its side-effect\*(R" for a longer |
|
|
3000 | example. |
|
|
3001 | .PP |
2857 | \fIWatcher-Specific Functions and Data Members\fR |
3002 | \fIWatcher-Specific Functions and Data Members\fR |
2858 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3003 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2859 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
3004 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
2860 | .IX Item "ev_idle_init (ev_idle *, callback)" |
3005 | .IX Item "ev_idle_init (ev_idle *, callback)" |
2861 | Initialises and configures the idle watcher \- it has no parameters of any |
3006 | Initialises and configures the idle watcher \- it has no parameters of any |
… | |
… | |
2866 | .IX Subsection "Examples" |
3011 | .IX Subsection "Examples" |
2867 | .PP |
3012 | .PP |
2868 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
3013 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
2869 | callback, free it. Also, use no error checking, as usual. |
3014 | callback, free it. Also, use no error checking, as usual. |
2870 | .PP |
3015 | .PP |
2871 | .Vb 7 |
3016 | .Vb 5 |
2872 | \& static void |
3017 | \& static void |
2873 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
3018 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2874 | \& { |
3019 | \& { |
|
|
3020 | \& // stop the watcher |
|
|
3021 | \& ev_idle_stop (loop, w); |
|
|
3022 | \& |
|
|
3023 | \& // now we can free it |
2875 | \& free (w); |
3024 | \& free (w); |
|
|
3025 | \& |
2876 | \& // now do something you wanted to do when the program has |
3026 | \& // now do something you wanted to do when the program has |
2877 | \& // no longer anything immediate to do. |
3027 | \& // no longer anything immediate to do. |
2878 | \& } |
3028 | \& } |
2879 | \& |
3029 | \& |
2880 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
3030 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
… | |
… | |
2882 | \& ev_idle_start (loop, idle_watcher); |
3032 | \& ev_idle_start (loop, idle_watcher); |
2883 | .Ve |
3033 | .Ve |
2884 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
3034 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
2885 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
3035 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2886 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
3036 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2887 | Prepare and check watchers are usually (but not always) used in pairs: |
3037 | Prepare and check watchers are often (but not always) used in pairs: |
2888 | prepare watchers get invoked before the process blocks and check watchers |
3038 | prepare watchers get invoked before the process blocks and check watchers |
2889 | afterwards. |
3039 | afterwards. |
2890 | .PP |
3040 | .PP |
2891 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter |
3041 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter |
2892 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
3042 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
… | |
… | |
2920 | with priority higher than or equal to the event loop and one coroutine |
3070 | with priority higher than or equal to the event loop and one coroutine |
2921 | of lower priority, but only once, using idle watchers to keep the event |
3071 | of lower priority, but only once, using idle watchers to keep the event |
2922 | loop from blocking if lower-priority coroutines are active, thus mapping |
3072 | loop from blocking if lower-priority coroutines are active, thus mapping |
2923 | low-priority coroutines to idle/background tasks). |
3073 | low-priority coroutines to idle/background tasks). |
2924 | .PP |
3074 | .PP |
2925 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
3075 | When used for this purpose, it is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers |
2926 | priority, to ensure that they are being run before any other watchers |
3076 | highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) priority, to ensure that they are being run before |
2927 | after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR watchers). |
3077 | any other watchers after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR |
|
|
3078 | watchers). |
2928 | .PP |
3079 | .PP |
2929 | Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not |
3080 | Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not |
2930 | activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they |
3081 | activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they |
2931 | might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As |
3082 | might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As |
2932 | \&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event |
3083 | \&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event |
2933 | loops those other event loops might be in an unusable state until their |
3084 | loops those other event loops might be in an unusable state until their |
2934 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
3085 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
2935 | others). |
3086 | others). |
|
|
3087 | .PP |
|
|
3088 | \fIAbusing an \f(CI\*(C`ev_check\*(C'\fI watcher for its side-effect\fR |
|
|
3089 | .IX Subsection "Abusing an ev_check watcher for its side-effect" |
|
|
3090 | .PP |
|
|
3091 | \&\f(CW\*(C`ev_check\*(C'\fR (and less often also \f(CW\*(C`ev_prepare\*(C'\fR) watchers can also be |
|
|
3092 | useful because they are called once per event loop iteration. For |
|
|
3093 | example, if you want to handle a large number of connections fairly, you |
|
|
3094 | normally only do a bit of work for each active connection, and if there |
|
|
3095 | is more work to do, you wait for the next event loop iteration, so other |
|
|
3096 | connections have a chance of making progress. |
|
|
3097 | .PP |
|
|
3098 | Using an \f(CW\*(C`ev_check\*(C'\fR watcher is almost enough: it will be called on the |
|
|
3099 | next event loop iteration. However, that isn't as soon as possible \- |
|
|
3100 | without external events, your \f(CW\*(C`ev_check\*(C'\fR watcher will not be invoked. |
|
|
3101 | .PP |
|
|
3102 | This is where \f(CW\*(C`ev_idle\*(C'\fR watchers come in handy \- all you need is a |
|
|
3103 | single global idle watcher that is active as long as you have one active |
|
|
3104 | \&\f(CW\*(C`ev_check\*(C'\fR watcher. The \f(CW\*(C`ev_idle\*(C'\fR watcher makes sure the event loop |
|
|
3105 | will not sleep, and the \f(CW\*(C`ev_check\*(C'\fR watcher makes sure a callback gets |
|
|
3106 | invoked. Neither watcher alone can do that. |
2936 | .PP |
3107 | .PP |
2937 | \fIWatcher-Specific Functions and Data Members\fR |
3108 | \fIWatcher-Specific Functions and Data Members\fR |
2938 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3109 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2939 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
3110 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
2940 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
3111 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
… | |
… | |
3307 | \& atexit (program_exits); |
3478 | \& atexit (program_exits); |
3308 | .Ve |
3479 | .Ve |
3309 | .ie n .SS """ev_async"" \- how to wake up an event loop" |
3480 | .ie n .SS """ev_async"" \- how to wake up an event loop" |
3310 | .el .SS "\f(CWev_async\fP \- how to wake up an event loop" |
3481 | .el .SS "\f(CWev_async\fP \- how to wake up an event loop" |
3311 | .IX Subsection "ev_async - how to wake up an event loop" |
3482 | .IX Subsection "ev_async - how to wake up an event loop" |
3312 | In general, you cannot use an \f(CW\*(C`ev_run\*(C'\fR from multiple threads or other |
3483 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
3313 | asynchronous sources such as signal handlers (as opposed to multiple event |
3484 | asynchronous sources such as signal handlers (as opposed to multiple event |
3314 | loops \- those are of course safe to use in different threads). |
3485 | loops \- those are of course safe to use in different threads). |
3315 | .PP |
3486 | .PP |
3316 | Sometimes, however, you need to wake up an event loop you do not control, |
3487 | Sometimes, however, you need to wake up an event loop you do not control, |
3317 | for example because it belongs to another thread. This is what \f(CW\*(C`ev_async\*(C'\fR |
3488 | for example because it belongs to another thread. This is what \f(CW\*(C`ev_async\*(C'\fR |
… | |
… | |
3319 | it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe. |
3490 | it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe. |
3320 | .PP |
3491 | .PP |
3321 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
3492 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
3322 | too, are asynchronous in nature, and signals, too, will be compressed |
3493 | too, are asynchronous in nature, and signals, too, will be compressed |
3323 | (i.e. the number of callback invocations may be less than the number of |
3494 | (i.e. the number of callback invocations may be less than the number of |
3324 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). In fact, you could use signal watchers as a kind |
3495 | \&\f(CW\*(C`ev_async_send\*(C'\fR calls). In fact, you could use signal watchers as a kind |
3325 | of \*(L"global async watchers\*(R" by using a watcher on an otherwise unused |
3496 | of \*(L"global async watchers\*(R" by using a watcher on an otherwise unused |
3326 | signal, and \f(CW\*(C`ev_feed_signal\*(C'\fR to signal this watcher from another thread, |
3497 | signal, and \f(CW\*(C`ev_feed_signal\*(C'\fR to signal this watcher from another thread, |
3327 | even without knowing which loop owns the signal. |
3498 | even without knowing which loop owns the signal. |
3328 | .PP |
|
|
3329 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
|
|
3330 | just the default loop. |
|
|
3331 | .PP |
3499 | .PP |
3332 | \fIQueueing\fR |
3500 | \fIQueueing\fR |
3333 | .IX Subsection "Queueing" |
3501 | .IX Subsection "Queueing" |
3334 | .PP |
3502 | .PP |
3335 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
3503 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
… | |
… | |
3422 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
3590 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
3423 | trust me. |
3591 | trust me. |
3424 | .IP "ev_async_send (loop, ev_async *)" 4 |
3592 | .IP "ev_async_send (loop, ev_async *)" 4 |
3425 | .IX Item "ev_async_send (loop, ev_async *)" |
3593 | .IX Item "ev_async_send (loop, ev_async *)" |
3426 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
3594 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
3427 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
3595 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop, and instantly |
|
|
3596 | returns. |
|
|
3597 | .Sp |
3428 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, signal or |
3598 | Unlike \f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, |
3429 | similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
3599 | signal or similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the |
3430 | section below on what exactly this means). |
3600 | embedding section below on what exactly this means). |
3431 | .Sp |
3601 | .Sp |
3432 | Note that, as with other watchers in libev, multiple events might get |
3602 | Note that, as with other watchers in libev, multiple events might get |
3433 | compressed into a single callback invocation (another way to look at this |
3603 | compressed into a single callback invocation (another way to look at |
3434 | is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered, set on \f(CW\*(C`ev_async_send\*(C'\fR, |
3604 | this is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered: they are set on |
3435 | reset when the event loop detects that). |
3605 | \&\f(CW\*(C`ev_async_send\*(C'\fR, reset when the event loop detects that). |
3436 | .Sp |
3606 | .Sp |
3437 | This call incurs the overhead of a system call only once per event loop |
3607 | This call incurs the overhead of at most one extra system call per event |
3438 | iteration, so while the overhead might be noticeable, it doesn't apply to |
3608 | loop iteration, if the event loop is blocked, and no syscall at all if |
3439 | repeated calls to \f(CW\*(C`ev_async_send\*(C'\fR for the same event loop. |
3609 | the event loop (or your program) is processing events. That means that |
|
|
3610 | repeated calls are basically free (there is no need to avoid calls for |
|
|
3611 | performance reasons) and that the overhead becomes smaller (typically |
|
|
3612 | zero) under load. |
3440 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3613 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3441 | .IX Item "bool = ev_async_pending (ev_async *)" |
3614 | .IX Item "bool = ev_async_pending (ev_async *)" |
3442 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3615 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3443 | watcher but the event has not yet been processed (or even noted) by the |
3616 | watcher but the event has not yet been processed (or even noted) by the |
3444 | event loop. |
3617 | event loop. |
… | |
… | |
3492 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3665 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3493 | .Ve |
3666 | .Ve |
3494 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
3667 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
3495 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
3668 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
3496 | Feed an event on the given fd, as if a file descriptor backend detected |
3669 | Feed an event on the given fd, as if a file descriptor backend detected |
3497 | the given events it. |
3670 | the given events. |
3498 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
3671 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
3499 | .IX Item "ev_feed_signal_event (loop, int signum)" |
3672 | .IX Item "ev_feed_signal_event (loop, int signum)" |
3500 | Feed an event as if the given signal occurred. See also \f(CW\*(C`ev_feed_signal\*(C'\fR, |
3673 | Feed an event as if the given signal occurred. See also \f(CW\*(C`ev_feed_signal\*(C'\fR, |
3501 | which is async-safe. |
3674 | which is async-safe. |
3502 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3675 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
… | |
… | |
3576 | \& { |
3749 | \& { |
3577 | \& struct my_biggy big = (struct my_biggy *) |
3750 | \& struct my_biggy big = (struct my_biggy *) |
3578 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
3751 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
3579 | \& } |
3752 | \& } |
3580 | .Ve |
3753 | .Ve |
|
|
3754 | .SS "\s-1AVOIDING\s0 \s-1FINISHING\s0 \s-1BEFORE\s0 \s-1RETURNING\s0" |
|
|
3755 | .IX Subsection "AVOIDING FINISHING BEFORE RETURNING" |
|
|
3756 | Often you have structures like this in event-based programs: |
|
|
3757 | .PP |
|
|
3758 | .Vb 4 |
|
|
3759 | \& callback () |
|
|
3760 | \& { |
|
|
3761 | \& free (request); |
|
|
3762 | \& } |
|
|
3763 | \& |
|
|
3764 | \& request = start_new_request (..., callback); |
|
|
3765 | .Ve |
|
|
3766 | .PP |
|
|
3767 | The intent is to start some \*(L"lengthy\*(R" operation. The \f(CW\*(C`request\*(C'\fR could be |
|
|
3768 | used to cancel the operation, or do other things with it. |
|
|
3769 | .PP |
|
|
3770 | It's not uncommon to have code paths in \f(CW\*(C`start_new_request\*(C'\fR that |
|
|
3771 | immediately invoke the callback, for example, to report errors. Or you add |
|
|
3772 | some caching layer that finds that it can skip the lengthy aspects of the |
|
|
3773 | operation and simply invoke the callback with the result. |
|
|
3774 | .PP |
|
|
3775 | The problem here is that this will happen \fIbefore\fR \f(CW\*(C`start_new_request\*(C'\fR |
|
|
3776 | has returned, so \f(CW\*(C`request\*(C'\fR is not set. |
|
|
3777 | .PP |
|
|
3778 | Even if you pass the request by some safer means to the callback, you |
|
|
3779 | might want to do something to the request after starting it, such as |
|
|
3780 | canceling it, which probably isn't working so well when the callback has |
|
|
3781 | already been invoked. |
|
|
3782 | .PP |
|
|
3783 | A common way around all these issues is to make sure that |
|
|
3784 | \&\f(CW\*(C`start_new_request\*(C'\fR \fIalways\fR returns before the callback is invoked. If |
|
|
3785 | \&\f(CW\*(C`start_new_request\*(C'\fR immediately knows the result, it can artificially |
|
|
3786 | delay invoking the callback by e.g. using a \f(CW\*(C`prepare\*(C'\fR or \f(CW\*(C`idle\*(C'\fR watcher |
|
|
3787 | for example, or more sneakily, by reusing an existing (stopped) watcher |
|
|
3788 | and pushing it into the pending queue: |
|
|
3789 | .PP |
|
|
3790 | .Vb 2 |
|
|
3791 | \& ev_set_cb (watcher, callback); |
|
|
3792 | \& ev_feed_event (EV_A_ watcher, 0); |
|
|
3793 | .Ve |
|
|
3794 | .PP |
|
|
3795 | This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is |
|
|
3796 | invoked, while not delaying callback invocation too much. |
3581 | .SS "\s-1MODEL/NESTED\s0 \s-1EVENT\s0 \s-1LOOP\s0 \s-1INVOCATIONS\s0 \s-1AND\s0 \s-1EXIT\s0 \s-1CONDITIONS\s0" |
3797 | .SS "\s-1MODEL/NESTED\s0 \s-1EVENT\s0 \s-1LOOP\s0 \s-1INVOCATIONS\s0 \s-1AND\s0 \s-1EXIT\s0 \s-1CONDITIONS\s0" |
3582 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
3798 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
3583 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
3799 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
3584 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
3800 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
3585 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
3801 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
… | |
… | |
3599 | \& int exit_main_loop = 0; |
3815 | \& int exit_main_loop = 0; |
3600 | \& |
3816 | \& |
3601 | \& while (!exit_main_loop) |
3817 | \& while (!exit_main_loop) |
3602 | \& ev_run (EV_DEFAULT_ EVRUN_ONCE); |
3818 | \& ev_run (EV_DEFAULT_ EVRUN_ONCE); |
3603 | \& |
3819 | \& |
3604 | \& // in a model watcher |
3820 | \& // in a modal watcher |
3605 | \& int exit_nested_loop = 0; |
3821 | \& int exit_nested_loop = 0; |
3606 | \& |
3822 | \& |
3607 | \& while (!exit_nested_loop) |
3823 | \& while (!exit_nested_loop) |
3608 | \& ev_run (EV_A_ EVRUN_ONCE); |
3824 | \& ev_run (EV_A_ EVRUN_ONCE); |
3609 | .Ve |
3825 | .Ve |
… | |
… | |
3658 | \& // now associate this with the loop |
3874 | \& // now associate this with the loop |
3659 | \& ev_set_userdata (EV_A_ u); |
3875 | \& ev_set_userdata (EV_A_ u); |
3660 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
3876 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
3661 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
3877 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
3662 | \& |
3878 | \& |
3663 | \& // then create the thread running ev_loop |
3879 | \& // then create the thread running ev_run |
3664 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
3880 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
3665 | \& } |
3881 | \& } |
3666 | .Ve |
3882 | .Ve |
3667 | .PP |
3883 | .PP |
3668 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
3884 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
… | |
… | |
3801 | .PP |
4017 | .PP |
3802 | .Vb 6 |
4018 | .Vb 6 |
3803 | \& void |
4019 | \& void |
3804 | \& wait_for_event (ev_watcher *w) |
4020 | \& wait_for_event (ev_watcher *w) |
3805 | \& { |
4021 | \& { |
3806 | \& ev_cb_set (w) = current_coro; |
4022 | \& ev_set_cb (w, current_coro); |
3807 | \& switch_to (libev_coro); |
4023 | \& switch_to (libev_coro); |
3808 | \& } |
4024 | \& } |
3809 | .Ve |
4025 | .Ve |
3810 | .PP |
4026 | .PP |
3811 | That basically suspends the coroutine inside \f(CW\*(C`wait_for_event\*(C'\fR and |
4027 | That basically suspends the coroutine inside \f(CW\*(C`wait_for_event\*(C'\fR and |
3812 | continues the libev coroutine, which, when appropriate, switches back to |
4028 | continues the libev coroutine, which, when appropriate, switches back to |
3813 | this or any other coroutine. I am sure if you sue this your own :) |
4029 | this or any other coroutine. |
3814 | .PP |
4030 | .PP |
3815 | You can do similar tricks if you have, say, threads with an event queue \- |
4031 | You can do similar tricks if you have, say, threads with an event queue \- |
3816 | instead of storing a coroutine, you store the queue object and instead of |
4032 | instead of storing a coroutine, you store the queue object and instead of |
3817 | switching to a coroutine, you push the watcher onto the queue and notify |
4033 | switching to a coroutine, you push the watcher onto the queue and notify |
3818 | any waiters. |
4034 | any waiters. |
3819 | .PP |
4035 | .PP |
3820 | To embed libev, see \s-1EMBEDDING\s0, but in short, it's easiest to create two |
4036 | To embed libev, see \*(L"\s-1EMBEDDING\s0\*(R", but in short, it's easiest to create two |
3821 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
4037 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
3822 | .PP |
4038 | .PP |
3823 | .Vb 4 |
4039 | .Vb 4 |
3824 | \& // my_ev.h |
4040 | \& // my_ev.h |
3825 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
4041 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
… | |
… | |
3864 | .IP "\(bu" 4 |
4080 | .IP "\(bu" 4 |
3865 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
4081 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
3866 | to use the libev header file and library. |
4082 | to use the libev header file and library. |
3867 | .SH "\*(C+ SUPPORT" |
4083 | .SH "\*(C+ SUPPORT" |
3868 | .IX Header " SUPPORT" |
4084 | .IX Header " SUPPORT" |
|
|
4085 | .SS "C \s-1API\s0" |
|
|
4086 | .IX Subsection "C API" |
|
|
4087 | The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the |
|
|
4088 | libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 |
|
|
4089 | will work fine. |
|
|
4090 | .PP |
|
|
4091 | Proper exception specifications might have to be added to callbacks passed |
|
|
4092 | to libev: exceptions may be thrown only from watcher callbacks, all |
|
|
4093 | other callbacks (allocator, syserr, loop acquire/release and periodioc |
|
|
4094 | reschedule callbacks) must not throw exceptions, and might need a \f(CW\*(C`throw |
|
|
4095 | ()\*(C'\fR specification. If you have code that needs to be compiled as both C |
|
|
4096 | and \*(C+ you can use the \f(CW\*(C`EV_THROW\*(C'\fR macro for this: |
|
|
4097 | .PP |
|
|
4098 | .Vb 6 |
|
|
4099 | \& static void |
|
|
4100 | \& fatal_error (const char *msg) EV_THROW |
|
|
4101 | \& { |
|
|
4102 | \& perror (msg); |
|
|
4103 | \& abort (); |
|
|
4104 | \& } |
|
|
4105 | \& |
|
|
4106 | \& ... |
|
|
4107 | \& ev_set_syserr_cb (fatal_error); |
|
|
4108 | .Ve |
|
|
4109 | .PP |
|
|
4110 | The only \s-1API\s0 functions that can currently throw exceptions are \f(CW\*(C`ev_run\*(C'\fR, |
|
|
4111 | \&\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 |
|
|
4112 | because it runs cleanup watchers). |
|
|
4113 | .PP |
|
|
4114 | Throwing exceptions in watcher callbacks is only supported if libev itself |
|
|
4115 | is compiled with a \*(C+ compiler or your C and \*(C+ environments allow |
|
|
4116 | throwing exceptions through C libraries (most do). |
|
|
4117 | .SS "\*(C+ \s-1API\s0" |
|
|
4118 | .IX Subsection " API" |
3869 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
4119 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
3870 | you to use some convenience methods to start/stop watchers and also change |
4120 | you to use some convenience methods to start/stop watchers and also change |
3871 | the callback model to a model using method callbacks on objects. |
4121 | the callback model to a model using method callbacks on objects. |
3872 | .PP |
4122 | .PP |
3873 | To use it, |
4123 | To use it, |
… | |
… | |
3889 | Currently, functions, static and non-static member functions and classes |
4139 | Currently, functions, static and non-static member functions and classes |
3890 | with \f(CW\*(C`operator ()\*(C'\fR can be used as callbacks. Other types should be easy |
4140 | with \f(CW\*(C`operator ()\*(C'\fR can be used as callbacks. Other types should be easy |
3891 | to add as long as they only need one additional pointer for context. If |
4141 | to add as long as they only need one additional pointer for context. If |
3892 | you need support for other types of functors please contact the author |
4142 | you need support for other types of functors please contact the author |
3893 | (preferably after implementing it). |
4143 | (preferably after implementing it). |
|
|
4144 | .PP |
|
|
4145 | For all this to work, your \*(C+ compiler either has to use the same calling |
|
|
4146 | conventions as your C compiler (for static member functions), or you have |
|
|
4147 | to embed libev and compile libev itself as \*(C+. |
3894 | .PP |
4148 | .PP |
3895 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
4149 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
3896 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
4150 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
3897 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
4151 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
3898 | .IX Item "ev::READ, ev::WRITE etc." |
4152 | .IX Item "ev::READ, ev::WRITE etc." |
… | |
… | |
3906 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
4160 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
3907 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
4161 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
3908 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
4162 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
3909 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
4163 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
3910 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
4164 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
3911 | defines by many implementations. |
4165 | defined by many implementations. |
3912 | .Sp |
4166 | .Sp |
3913 | All of those classes have these methods: |
4167 | All of those classes have these methods: |
3914 | .RS 4 |
4168 | .RS 4 |
3915 | .IP "ev::TYPE::TYPE ()" 4 |
4169 | .IP "ev::TYPE::TYPE ()" 4 |
3916 | .IX Item "ev::TYPE::TYPE ()" |
4170 | .IX Item "ev::TYPE::TYPE ()" |
… | |
… | |
4047 | .PP |
4301 | .PP |
4048 | .Vb 5 |
4302 | .Vb 5 |
4049 | \& class myclass |
4303 | \& class myclass |
4050 | \& { |
4304 | \& { |
4051 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
4305 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
4052 | \& ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
4306 | \& ev::io io2 ; void io2_cb (ev::io &w, int revents); |
4053 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
4307 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
4054 | \& |
4308 | \& |
4055 | \& myclass (int fd) |
4309 | \& myclass (int fd) |
4056 | \& { |
4310 | \& { |
4057 | \& io .set <myclass, &myclass::io_cb > (this); |
4311 | \& io .set <myclass, &myclass::io_cb > (this); |
… | |
… | |
4096 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
4350 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
4097 | makes rev work even on mingw. |
4351 | makes rev work even on mingw. |
4098 | .IP "Haskell" 4 |
4352 | .IP "Haskell" 4 |
4099 | .IX Item "Haskell" |
4353 | .IX Item "Haskell" |
4100 | A haskell binding to libev is available at |
4354 | A haskell binding to libev is available at |
4101 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
4355 | http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev <http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>. |
4102 | .IP "D" 4 |
4356 | .IP "D" 4 |
4103 | .IX Item "D" |
4357 | .IX Item "D" |
4104 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4358 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4105 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
4359 | be found at <http://www.llucax.com.ar/proj/ev.d/index.html>. |
4106 | .IP "Ocaml" 4 |
4360 | .IP "Ocaml" 4 |
4107 | .IX Item "Ocaml" |
4361 | .IX Item "Ocaml" |
4108 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4362 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4109 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
4363 | http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/ <http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
4110 | .IP "Lua" 4 |
4364 | .IP "Lua" 4 |
4111 | .IX Item "Lua" |
4365 | .IX Item "Lua" |
4112 | Brian Maher has written a partial interface to libev for lua (at the |
4366 | Brian Maher has written a partial interface to libev for lua (at the |
4113 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
4367 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
4114 | <http://github.com/brimworks/lua\-ev>. |
4368 | http://github.com/brimworks/lua\-ev <http://github.com/brimworks/lua-ev>. |
|
|
4369 | .IP "Javascript" 4 |
|
|
4370 | .IX Item "Javascript" |
|
|
4371 | Node.js (<http://nodejs.org>) uses libev as the underlying event library. |
|
|
4372 | .IP "Others" 4 |
|
|
4373 | .IX Item "Others" |
|
|
4374 | There are others, and I stopped counting. |
4115 | .SH "MACRO MAGIC" |
4375 | .SH "MACRO MAGIC" |
4116 | .IX Header "MACRO MAGIC" |
4376 | .IX Header "MACRO MAGIC" |
4117 | Libev can be compiled with a variety of options, the most fundamental |
4377 | Libev can be compiled with a variety of options, the most fundamental |
4118 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
4378 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
4119 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
4379 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
… | |
… | |
4154 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
4414 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
4155 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
4415 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
4156 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
4416 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
4157 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
4417 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
4158 | Similar to the other two macros, this gives you the value of the default |
4418 | Similar to the other two macros, this gives you the value of the default |
4159 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
4419 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). The default loop |
|
|
4420 | will be initialised if it isn't already initialised. |
|
|
4421 | .Sp |
|
|
4422 | For non-multiplicity builds, these macros do nothing, so you always have |
|
|
4423 | to initialise the loop somewhere. |
4160 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
4424 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
4161 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
4425 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
4162 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
4426 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
4163 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
4427 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
4164 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
4428 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
… | |
… | |
4319 | supported). It will also not define any of the structs usually found in |
4583 | supported). It will also not define any of the structs usually found in |
4320 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
4584 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
4321 | .Sp |
4585 | .Sp |
4322 | In standalone mode, libev will still try to automatically deduce the |
4586 | In standalone mode, libev will still try to automatically deduce the |
4323 | configuration, but has to be more conservative. |
4587 | configuration, but has to be more conservative. |
|
|
4588 | .IP "\s-1EV_USE_FLOOR\s0" 4 |
|
|
4589 | .IX Item "EV_USE_FLOOR" |
|
|
4590 | If defined to be \f(CW1\fR, libev will use the \f(CW\*(C`floor ()\*(C'\fR function for its |
|
|
4591 | periodic reschedule calculations, otherwise libev will fall back on a |
|
|
4592 | portable (slower) implementation. If you enable this, you usually have to |
|
|
4593 | link against libm or something equivalent. Enabling this when the \f(CW\*(C`floor\*(C'\fR |
|
|
4594 | function is not available will fail, so the safe default is to not enable |
|
|
4595 | this. |
4324 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
4596 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
4325 | .IX Item "EV_USE_MONOTONIC" |
4597 | .IX Item "EV_USE_MONOTONIC" |
4326 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
4598 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
4327 | monotonic clock option at both compile time and runtime. Otherwise no |
4599 | monotonic clock option at both compile time and runtime. Otherwise no |
4328 | use of the monotonic clock option will be attempted. If you enable this, |
4600 | use of the monotonic clock option will be attempted. If you enable this, |
… | |
… | |
4402 | .IX Item "EV_WIN32_CLOSE_FD(fd)" |
4674 | .IX Item "EV_WIN32_CLOSE_FD(fd)" |
4403 | If programs implement their own fd to handle mapping on win32, then this |
4675 | If programs implement their own fd to handle mapping on win32, then this |
4404 | macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister |
4676 | macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister |
4405 | file descriptors again. Note that the replacement function has to close |
4677 | file descriptors again. Note that the replacement function has to close |
4406 | the underlying \s-1OS\s0 handle. |
4678 | the underlying \s-1OS\s0 handle. |
|
|
4679 | .IP "\s-1EV_USE_WSASOCKET\s0" 4 |
|
|
4680 | .IX Item "EV_USE_WSASOCKET" |
|
|
4681 | If defined to be \f(CW1\fR, libev will use \f(CW\*(C`WSASocket\*(C'\fR to create its internal |
|
|
4682 | communication socket, which works better in some environments. Otherwise, |
|
|
4683 | the normal \f(CW\*(C`socket\*(C'\fR function will be used, which works better in other |
|
|
4684 | enviornments. |
4407 | .IP "\s-1EV_USE_POLL\s0" 4 |
4685 | .IP "\s-1EV_USE_POLL\s0" 4 |
4408 | .IX Item "EV_USE_POLL" |
4686 | .IX Item "EV_USE_POLL" |
4409 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
4687 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
4410 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
4688 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
4411 | takes precedence over select. |
4689 | takes precedence over select. |
… | |
… | |
4440 | .IX Item "EV_USE_INOTIFY" |
4718 | .IX Item "EV_USE_INOTIFY" |
4441 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
4719 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
4442 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
4720 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
4443 | be detected at runtime. If undefined, it will be enabled if the headers |
4721 | be detected at runtime. If undefined, it will be enabled if the headers |
4444 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4722 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4723 | .IP "\s-1EV_NO_SMP\s0" 4 |
|
|
4724 | .IX Item "EV_NO_SMP" |
|
|
4725 | If defined to be \f(CW1\fR, libev will assume that memory is always coherent |
|
|
4726 | between threads, that is, threads can be used, but threads never run on |
|
|
4727 | different cpus (or different cpu cores). This reduces dependencies |
|
|
4728 | and makes libev faster. |
|
|
4729 | .IP "\s-1EV_NO_THREADS\s0" 4 |
|
|
4730 | .IX Item "EV_NO_THREADS" |
|
|
4731 | If defined to be \f(CW1\fR, libev will assume that it will never be called |
|
|
4732 | from different threads, which is a stronger assumption than \f(CW\*(C`EV_NO_SMP\*(C'\fR, |
|
|
4733 | above. This reduces dependencies and makes libev faster. |
4445 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
4734 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
4446 | .IX Item "EV_ATOMIC_T" |
4735 | .IX Item "EV_ATOMIC_T" |
4447 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
4736 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
4448 | access is atomic with respect to other threads or signal contexts. No such |
4737 | access is atomic and serialised with respect to other threads or signal |
4449 | type is easily found in the C language, so you can provide your own type |
4738 | contexts. No such type is easily found in the C language, so you can |
4450 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
4739 | provide your own type that you know is safe for your purposes. It is used |
4451 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
4740 | both for signal handler \*(L"locking\*(R" as well as for signal and thread safety |
|
|
4741 | in \f(CW\*(C`ev_async\*(C'\fR watchers. |
4452 | .Sp |
4742 | .Sp |
4453 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4743 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4454 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4744 | (from \fIsignal.h\fR), which is usually good enough on most platforms, |
|
|
4745 | although strictly speaking using a type that also implies a memory fence |
|
|
4746 | is required. |
4455 | .IP "\s-1EV_H\s0 (h)" 4 |
4747 | .IP "\s-1EV_H\s0 (h)" 4 |
4456 | .IX Item "EV_H (h)" |
4748 | .IX Item "EV_H (h)" |
4457 | The name of the \fIev.h\fR header file used to include it. The default if |
4749 | The name of the \fIev.h\fR header file used to include it. The default if |
4458 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
4750 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
4459 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
4751 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
… | |
… | |
4477 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
4769 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
4478 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
4770 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
4479 | additional independent event loops. Otherwise there will be no support |
4771 | additional independent event loops. Otherwise there will be no support |
4480 | for multiple event loops and there is no first event loop pointer |
4772 | for multiple event loops and there is no first event loop pointer |
4481 | argument. Instead, all functions act on the single default loop. |
4773 | argument. Instead, all functions act on the single default loop. |
|
|
4774 | .Sp |
|
|
4775 | Note that \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR will no longer provide a |
|
|
4776 | default loop when multiplicity is switched off \- you always have to |
|
|
4777 | initialise the loop manually in this case. |
4482 | .IP "\s-1EV_MINPRI\s0" 4 |
4778 | .IP "\s-1EV_MINPRI\s0" 4 |
4483 | .IX Item "EV_MINPRI" |
4779 | .IX Item "EV_MINPRI" |
4484 | .PD 0 |
4780 | .PD 0 |
4485 | .IP "\s-1EV_MAXPRI\s0" 4 |
4781 | .IP "\s-1EV_MAXPRI\s0" 4 |
4486 | .IX Item "EV_MAXPRI" |
4782 | .IX Item "EV_MAXPRI" |
… | |
… | |
4522 | \& #define EV_CHILD_ENABLE 1 |
4818 | \& #define EV_CHILD_ENABLE 1 |
4523 | \& #define EV_ASYNC_ENABLE 1 |
4819 | \& #define EV_ASYNC_ENABLE 1 |
4524 | .Ve |
4820 | .Ve |
4525 | .Sp |
4821 | .Sp |
4526 | The actual value is a bitset, it can be a combination of the following |
4822 | The actual value is a bitset, it can be a combination of the following |
4527 | values: |
4823 | values (by default, all of these are enabled): |
4528 | .RS 4 |
4824 | .RS 4 |
4529 | .ie n .IP "1 \- faster/larger code" 4 |
4825 | .ie n .IP "1 \- faster/larger code" 4 |
4530 | .el .IP "\f(CW1\fR \- faster/larger code" 4 |
4826 | .el .IP "\f(CW1\fR \- faster/larger code" 4 |
4531 | .IX Item "1 - faster/larger code" |
4827 | .IX Item "1 - faster/larger code" |
4532 | Use larger code to speed up some operations. |
4828 | Use larger code to speed up some operations. |
… | |
… | |
4535 | code size by roughly 30% on amd64). |
4831 | code size by roughly 30% on amd64). |
4536 | .Sp |
4832 | .Sp |
4537 | When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with |
4833 | When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with |
4538 | gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of |
4834 | gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of |
4539 | assertions. |
4835 | assertions. |
|
|
4836 | .Sp |
|
|
4837 | The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler |
|
|
4838 | (e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR). |
4540 | .ie n .IP "2 \- faster/larger data structures" 4 |
4839 | .ie n .IP "2 \- faster/larger data structures" 4 |
4541 | .el .IP "\f(CW2\fR \- faster/larger data structures" 4 |
4840 | .el .IP "\f(CW2\fR \- faster/larger data structures" 4 |
4542 | .IX Item "2 - faster/larger data structures" |
4841 | .IX Item "2 - faster/larger data structures" |
4543 | Replaces the small 2\-heap for timer management by a faster 4\-heap, larger |
4842 | Replaces the small 2\-heap for timer management by a faster 4\-heap, larger |
4544 | hash table sizes and so on. This will usually further increase code size |
4843 | hash table sizes and so on. This will usually further increase code size |
4545 | and can additionally have an effect on the size of data structures at |
4844 | and can additionally have an effect on the size of data structures at |
4546 | runtime. |
4845 | runtime. |
|
|
4846 | .Sp |
|
|
4847 | The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler |
|
|
4848 | (e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR). |
4547 | .ie n .IP "4 \- full \s-1API\s0 configuration" 4 |
4849 | .ie n .IP "4 \- full \s-1API\s0 configuration" 4 |
4548 | .el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4 |
4850 | .el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4 |
4549 | .IX Item "4 - full API configuration" |
4851 | .IX Item "4 - full API configuration" |
4550 | This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and |
4852 | This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and |
4551 | enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1). |
4853 | enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1). |
… | |
… | |
4583 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
4885 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
4584 | when you use \f(CW\*(C`\-Wl,\-\-gc\-sections \-ffunction\-sections\*(C'\fR) functions unused by |
4886 | when you use \f(CW\*(C`\-Wl,\-\-gc\-sections \-ffunction\-sections\*(C'\fR) functions unused by |
4585 | your program might be left out as well \- a binary starting a timer and an |
4887 | your program might be left out as well \- a binary starting a timer and an |
4586 | I/O watcher then might come out at only 5Kb. |
4888 | I/O watcher then might come out at only 5Kb. |
4587 | .RE |
4889 | .RE |
|
|
4890 | .IP "\s-1EV_API_STATIC\s0" 4 |
|
|
4891 | .IX Item "EV_API_STATIC" |
|
|
4892 | If this symbol is defined (by default it is not), then all identifiers |
|
|
4893 | will have static linkage. This means that libev will not export any |
|
|
4894 | identifiers, and you cannot link against libev anymore. This can be useful |
|
|
4895 | when you embed libev, only want to use libev functions in a single file, |
|
|
4896 | and do not want its identifiers to be visible. |
|
|
4897 | .Sp |
|
|
4898 | To use this, define \f(CW\*(C`EV_API_STATIC\*(C'\fR and include \fIev.c\fR in the file that |
|
|
4899 | wants to use libev. |
|
|
4900 | .Sp |
|
|
4901 | This option only works when libev is compiled with a C compiler, as \*(C+ |
|
|
4902 | doesn't support the required declaration syntax. |
4588 | .IP "\s-1EV_AVOID_STDIO\s0" 4 |
4903 | .IP "\s-1EV_AVOID_STDIO\s0" 4 |
4589 | .IX Item "EV_AVOID_STDIO" |
4904 | .IX Item "EV_AVOID_STDIO" |
4590 | If this is set to \f(CW1\fR at compiletime, then libev will avoid using stdio |
4905 | If this is set to \f(CW1\fR at compiletime, then libev will avoid using stdio |
4591 | functions (printf, scanf, perror etc.). This will increase the code size |
4906 | functions (printf, scanf, perror etc.). This will increase the code size |
4592 | somewhat, but if your program doesn't otherwise depend on stdio and your |
4907 | somewhat, but if your program doesn't otherwise depend on stdio and your |
… | |
… | |
4969 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
5284 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
4970 | model. Libev still offers limited functionality on this platform in |
5285 | model. Libev still offers limited functionality on this platform in |
4971 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
5286 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
4972 | descriptors. This only applies when using Win32 natively, not when using |
5287 | descriptors. This only applies when using Win32 natively, not when using |
4973 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
5288 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
4974 | as every compielr comes with a slightly differently broken/incompatible |
5289 | as every compiler comes with a slightly differently broken/incompatible |
4975 | environment. |
5290 | environment. |
4976 | .PP |
5291 | .PP |
4977 | Lifting these limitations would basically require the full |
5292 | Lifting these limitations would basically require the full |
4978 | re-implementation of the I/O system. If you are into this kind of thing, |
5293 | re-implementation of the I/O system. If you are into this kind of thing, |
4979 | then note that glib does exactly that for you in a very portable way (note |
5294 | then note that glib does exactly that for you in a very portable way (note |
… | |
… | |
5115 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5430 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5116 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5431 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5117 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
5432 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
5118 | good enough for at least into the year 4000 with millisecond accuracy |
5433 | good enough for at least into the year 4000 with millisecond accuracy |
5119 | (the design goal for libev). This requirement is overfulfilled by |
5434 | (the design goal for libev). This requirement is overfulfilled by |
5120 | implementations using \s-1IEEE\s0 754, which is basically all existing ones. With |
5435 | implementations using \s-1IEEE\s0 754, which is basically all existing ones. |
|
|
5436 | .Sp |
5121 | \&\s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least 2200. |
5437 | With \s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least the |
|
|
5438 | year 2255 (and millisecond accuracy till the year 287396 \- by then, libev |
|
|
5439 | is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or |
|
|
5440 | something like that, just kidding). |
5122 | .PP |
5441 | .PP |
5123 | If you know of other additional requirements drop me a note. |
5442 | If you know of other additional requirements drop me a note. |
5124 | .SH "ALGORITHMIC COMPLEXITIES" |
5443 | .SH "ALGORITHMIC COMPLEXITIES" |
5125 | .IX Header "ALGORITHMIC COMPLEXITIES" |
5444 | .IX Header "ALGORITHMIC COMPLEXITIES" |
5126 | In this section the complexities of (many of) the algorithms used inside |
5445 | In this section the complexities of (many of) the algorithms used inside |
… | |
… | |
5180 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
5499 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
5181 | .IP "Processing signals: O(max_signal_number)" 4 |
5500 | .IP "Processing signals: O(max_signal_number)" 4 |
5182 | .IX Item "Processing signals: O(max_signal_number)" |
5501 | .IX Item "Processing signals: O(max_signal_number)" |
5183 | .PD |
5502 | .PD |
5184 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
5503 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
5185 | calls in the current loop iteration. Checking for async and signal events |
5504 | calls in the current loop iteration and the loop is currently |
|
|
5505 | blocked. Checking for async and signal events involves iterating over all |
5186 | involves iterating over all running async watchers or all signal numbers. |
5506 | running async watchers or all signal numbers. |
5187 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
5507 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
5188 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
5508 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
5189 | The major version 4 introduced some incompatible changes to the \s-1API\s0. |
5509 | The major version 4 introduced some incompatible changes to the \s-1API\s0. |
5190 | .PP |
5510 | .PP |
5191 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
5511 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
… | |
… | |
5194 | new \s-1API\s0 early than late. |
5514 | new \s-1API\s0 early than late. |
5195 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
5515 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
5196 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
5516 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
5197 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
5517 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
5198 | The backward compatibility mechanism can be controlled by |
5518 | The backward compatibility mechanism can be controlled by |
5199 | \&\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 |
5519 | \&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0\*(R" in the \*(L"\s-1EMBEDDING\s0\*(R" |
5200 | section. |
5520 | section. |
5201 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
5521 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
5202 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
5522 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
5203 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
5523 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
5204 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
5524 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
… | |
… | |
5288 | .IX Item "real time" |
5608 | .IX Item "real time" |
5289 | The physical time that is observed. It is apparently strictly monotonic :) |
5609 | The physical time that is observed. It is apparently strictly monotonic :) |
5290 | .IP "wall-clock time" 4 |
5610 | .IP "wall-clock time" 4 |
5291 | .IX Item "wall-clock time" |
5611 | .IX Item "wall-clock time" |
5292 | The time and date as shown on clocks. Unlike real time, it can actually |
5612 | The time and date as shown on clocks. Unlike real time, it can actually |
5293 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
5613 | be wrong and jump forwards and backwards, e.g. when you adjust your |
5294 | clock. |
5614 | clock. |
5295 | .IP "watcher" 4 |
5615 | .IP "watcher" 4 |
5296 | .IX Item "watcher" |
5616 | .IX Item "watcher" |
5297 | A data structure that describes interest in certain events. Watchers need |
5617 | A data structure that describes interest in certain events. Watchers need |
5298 | to be started (attached to an event loop) before they can receive events. |
5618 | to be started (attached to an event loop) before they can receive events. |
5299 | .SH "AUTHOR" |
5619 | .SH "AUTHOR" |
5300 | .IX Header "AUTHOR" |
5620 | .IX Header "AUTHOR" |
5301 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
5621 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
5302 | Magnusson and Emanuele Giaquinta. |
5622 | Magnusson and Emanuele Giaquinta, and minor corrections by many others. |