… | |
… | |
26 | puts ("stdin ready"); |
26 | puts ("stdin ready"); |
27 | // for one-shot events, one must manually stop the watcher |
27 | // for one-shot events, one must manually stop the watcher |
28 | // with its corresponding stop function. |
28 | // with its corresponding stop function. |
29 | ev_io_stop (EV_A_ w); |
29 | ev_io_stop (EV_A_ w); |
30 | |
30 | |
31 | // this causes all nested ev_loop's to stop iterating |
31 | // this causes all nested ev_run's to stop iterating |
32 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
32 | ev_break (EV_A_ EVBREAK_ALL); |
33 | } |
33 | } |
34 | |
34 | |
35 | // another callback, this time for a time-out |
35 | // another callback, this time for a time-out |
36 | static void |
36 | static void |
37 | timeout_cb (EV_P_ ev_timer *w, int revents) |
37 | timeout_cb (EV_P_ ev_timer *w, int revents) |
38 | { |
38 | { |
39 | puts ("timeout"); |
39 | puts ("timeout"); |
40 | // this causes the innermost ev_loop to stop iterating |
40 | // this causes the innermost ev_run to stop iterating |
41 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
41 | ev_break (EV_A_ EVBREAK_ONE); |
42 | } |
42 | } |
43 | |
43 | |
44 | int |
44 | int |
45 | main (void) |
45 | main (void) |
46 | { |
46 | { |
… | |
… | |
56 | // simple non-repeating 5.5 second timeout |
56 | // simple non-repeating 5.5 second timeout |
57 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
57 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
58 | ev_timer_start (loop, &timeout_watcher); |
58 | ev_timer_start (loop, &timeout_watcher); |
59 | |
59 | |
60 | // now wait for events to arrive |
60 | // now wait for events to arrive |
61 | ev_loop (loop, 0); |
61 | ev_run (loop, 0); |
62 | |
62 | |
63 | // unloop was called, so exit |
63 | // unloop was called, so exit |
64 | return 0; |
64 | return 0; |
65 | } |
65 | } |
66 | |
66 | |
… | |
… | |
75 | While this document tries to be as complete as possible in documenting |
75 | While this document tries to be as complete as possible in documenting |
76 | libev, its usage and the rationale behind its design, it is not a tutorial |
76 | libev, its usage and the rationale behind its design, it is not a tutorial |
77 | on event-based programming, nor will it introduce event-based programming |
77 | on event-based programming, nor will it introduce event-based programming |
78 | with libev. |
78 | with libev. |
79 | |
79 | |
80 | Familarity with event based programming techniques in general is assumed |
80 | Familiarity with event based programming techniques in general is assumed |
81 | throughout this document. |
81 | throughout this document. |
82 | |
82 | |
83 | =head1 ABOUT LIBEV |
83 | =head1 ABOUT LIBEV |
84 | |
84 | |
85 | Libev is an event loop: you register interest in certain events (such as a |
85 | Libev is an event loop: you register interest in certain events (such as a |
… | |
… | |
124 | this argument. |
124 | this argument. |
125 | |
125 | |
126 | =head2 TIME REPRESENTATION |
126 | =head2 TIME REPRESENTATION |
127 | |
127 | |
128 | Libev represents time as a single floating point number, representing |
128 | Libev represents time as a single floating point number, representing |
129 | the (fractional) number of seconds since the (POSIX) epoch (somewhere |
129 | the (fractional) number of seconds since the (POSIX) epoch (in practise |
130 | near the beginning of 1970, details are complicated, don't ask). This |
130 | somewhere near the beginning of 1970, details are complicated, don't |
131 | type is called C<ev_tstamp>, which is what you should use too. It usually |
131 | ask). This type is called C<ev_tstamp>, which is what you should use |
132 | aliases to the C<double> type in C. When you need to do any calculations |
132 | too. It usually aliases to the C<double> type in C. When you need to do |
133 | on it, you should treat it as some floating point value. Unlike the name |
133 | any calculations on it, you should treat it as some floating point value. |
|
|
134 | |
134 | component C<stamp> might indicate, it is also used for time differences |
135 | Unlike the name component C<stamp> might indicate, it is also used for |
135 | throughout libev. |
136 | time differences (e.g. delays) throughout libev. |
136 | |
137 | |
137 | =head1 ERROR HANDLING |
138 | =head1 ERROR HANDLING |
138 | |
139 | |
139 | Libev knows three classes of errors: operating system errors, usage errors |
140 | Libev knows three classes of errors: operating system errors, usage errors |
140 | and internal errors (bugs). |
141 | and internal errors (bugs). |
… | |
… | |
191 | as this indicates an incompatible change. Minor versions are usually |
192 | as this indicates an incompatible change. Minor versions are usually |
192 | compatible to older versions, so a larger minor version alone is usually |
193 | compatible to older versions, so a larger minor version alone is usually |
193 | not a problem. |
194 | not a problem. |
194 | |
195 | |
195 | Example: Make sure we haven't accidentally been linked against the wrong |
196 | Example: Make sure we haven't accidentally been linked against the wrong |
196 | version. |
197 | version (note, however, that this will not detect ABI mismatches :). |
197 | |
198 | |
198 | assert (("libev version mismatch", |
199 | assert (("libev version mismatch", |
199 | ev_version_major () == EV_VERSION_MAJOR |
200 | ev_version_major () == EV_VERSION_MAJOR |
200 | && ev_version_minor () >= EV_VERSION_MINOR)); |
201 | && ev_version_minor () >= EV_VERSION_MINOR)); |
201 | |
202 | |
… | |
… | |
291 | |
292 | |
292 | =back |
293 | =back |
293 | |
294 | |
294 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
295 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
295 | |
296 | |
296 | An event loop is described by a C<struct ev_loop *> (the C<struct> |
297 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
297 | is I<not> optional in this case, as there is also an C<ev_loop> |
298 | I<not> optional in case unless libev 3 compatibility is disabled, as libev |
298 | I<function>). |
299 | 3 had an C<ev_loop> function colliding with the struct name). |
299 | |
300 | |
300 | The library knows two types of such loops, the I<default> loop, which |
301 | The library knows two types of such loops, the I<default> loop, which |
301 | supports signals and child events, and dynamically created loops which do |
302 | supports signals and child events, and dynamically created event loops |
302 | not. |
303 | which do not. |
303 | |
304 | |
304 | =over 4 |
305 | =over 4 |
305 | |
306 | |
306 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
307 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
307 | |
308 | |
… | |
… | |
345 | useful to try out specific backends to test their performance, or to work |
346 | useful to try out specific backends to test their performance, or to work |
346 | around bugs. |
347 | around bugs. |
347 | |
348 | |
348 | =item C<EVFLAG_FORKCHECK> |
349 | =item C<EVFLAG_FORKCHECK> |
349 | |
350 | |
350 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
351 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
351 | a fork, you can also make libev check for a fork in each iteration by |
352 | make libev check for a fork in each iteration by enabling this flag. |
352 | enabling this flag. |
|
|
353 | |
353 | |
354 | This works by calling C<getpid ()> on every iteration of the loop, |
354 | This works by calling C<getpid ()> on every iteration of the loop, |
355 | and thus this might slow down your event loop if you do a lot of loop |
355 | and thus this might slow down your event loop if you do a lot of loop |
356 | iterations and little real work, but is usually not noticeable (on my |
356 | iterations and little real work, but is usually not noticeable (on my |
357 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
357 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
… | |
… | |
439 | of course I<doesn't>, and epoll just loves to report events for totally |
439 | of course I<doesn't>, and epoll just loves to report events for totally |
440 | I<different> file descriptors (even already closed ones, so one cannot |
440 | I<different> file descriptors (even already closed ones, so one cannot |
441 | even remove them from the set) than registered in the set (especially |
441 | even remove them from the set) than registered in the set (especially |
442 | on SMP systems). Libev tries to counter these spurious notifications by |
442 | on SMP systems). Libev tries to counter these spurious notifications by |
443 | employing an additional generation counter and comparing that against the |
443 | employing an additional generation counter and comparing that against the |
444 | events to filter out spurious ones, recreating the set when required. |
444 | events to filter out spurious ones, recreating the set when required. Last |
|
|
445 | not least, it also refuses to work with some file descriptors which work |
|
|
446 | perfectly fine with C<select> (files, many character devices...). |
445 | |
447 | |
446 | While stopping, setting and starting an I/O watcher in the same iteration |
448 | While stopping, setting and starting an I/O watcher in the same iteration |
447 | will result in some caching, there is still a system call per such |
449 | will result in some caching, there is still a system call per such |
448 | incident (because the same I<file descriptor> could point to a different |
450 | incident (because the same I<file descriptor> could point to a different |
449 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
451 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
… | |
… | |
567 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
569 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
568 | |
570 | |
569 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
571 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
570 | |
572 | |
571 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
573 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
572 | always distinct from the default loop. Unlike the default loop, it cannot |
574 | always distinct from the default loop. |
573 | handle signal and child watchers, and attempts to do so will be greeted by |
|
|
574 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
575 | |
575 | |
576 | Note that this function I<is> thread-safe, and the recommended way to use |
576 | Note that this function I<is> thread-safe, and one common way to use |
577 | libev with threads is indeed to create one loop per thread, and using the |
577 | libev with threads is indeed to create one loop per thread, and using the |
578 | default loop in the "main" or "initial" thread. |
578 | default loop in the "main" or "initial" thread. |
579 | |
579 | |
580 | Example: Try to create a event loop that uses epoll and nothing else. |
580 | Example: Try to create a event loop that uses epoll and nothing else. |
581 | |
581 | |
… | |
… | |
583 | if (!epoller) |
583 | if (!epoller) |
584 | fatal ("no epoll found here, maybe it hides under your chair"); |
584 | fatal ("no epoll found here, maybe it hides under your chair"); |
585 | |
585 | |
586 | =item ev_default_destroy () |
586 | =item ev_default_destroy () |
587 | |
587 | |
588 | Destroys the default loop again (frees all memory and kernel state |
588 | Destroys the default loop (frees all memory and kernel state etc.). None |
589 | etc.). None of the active event watchers will be stopped in the normal |
589 | of the active event watchers will be stopped in the normal sense, so |
590 | sense, so e.g. C<ev_is_active> might still return true. It is your |
590 | e.g. C<ev_is_active> might still return true. It is your responsibility to |
591 | responsibility to either stop all watchers cleanly yourself I<before> |
591 | either stop all watchers cleanly yourself I<before> calling this function, |
592 | calling this function, or cope with the fact afterwards (which is usually |
592 | or cope with the fact afterwards (which is usually the easiest thing, you |
593 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
593 | can just ignore the watchers and/or C<free ()> them for example). |
594 | for example). |
|
|
595 | |
594 | |
596 | Note that certain global state, such as signal state (and installed signal |
595 | Note that certain global state, such as signal state (and installed signal |
597 | handlers), will not be freed by this function, and related watchers (such |
596 | handlers), will not be freed by this function, and related watchers (such |
598 | as signal and child watchers) would need to be stopped manually. |
597 | as signal and child watchers) would need to be stopped manually. |
599 | |
598 | |
… | |
… | |
607 | Like C<ev_default_destroy>, but destroys an event loop created by an |
606 | Like C<ev_default_destroy>, but destroys an event loop created by an |
608 | earlier call to C<ev_loop_new>. |
607 | earlier call to C<ev_loop_new>. |
609 | |
608 | |
610 | =item ev_default_fork () |
609 | =item ev_default_fork () |
611 | |
610 | |
612 | This function sets a flag that causes subsequent C<ev_loop> iterations |
611 | This function sets a flag that causes subsequent C<ev_run> iterations |
613 | to reinitialise the kernel state for backends that have one. Despite the |
612 | to reinitialise the kernel state for backends that have one. Despite the |
614 | name, you can call it anytime, but it makes most sense after forking, in |
613 | name, you can call it anytime, but it makes most sense after forking, in |
615 | the child process (or both child and parent, but that again makes little |
614 | the child process (or both child and parent, but that again makes little |
616 | sense). You I<must> call it in the child before using any of the libev |
615 | sense). You I<must> call it in the child before using any of the libev |
617 | functions, and it will only take effect at the next C<ev_loop> iteration. |
616 | functions, and it will only take effect at the next C<ev_run> iteration. |
|
|
617 | |
|
|
618 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
|
|
619 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
|
|
620 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
|
|
621 | during fork. |
618 | |
622 | |
619 | On the other hand, you only need to call this function in the child |
623 | On the other hand, you only need to call this function in the child |
620 | process if and only if you want to use the event library in the child. If |
624 | process if and only if you want to use the event loop in the child. If |
621 | you just fork+exec, you don't have to call it at all. |
625 | you just fork+exec or create a new loop in the child, you don't have to |
|
|
626 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
|
|
627 | difference, but libev will usually detect this case on its own and do a |
|
|
628 | costly reset of the backend). |
622 | |
629 | |
623 | The function itself is quite fast and it's usually not a problem to call |
630 | The function itself is quite fast and it's usually not a problem to call |
624 | it just in case after a fork. To make this easy, the function will fit in |
631 | it just in case after a fork. To make this easy, the function will fit in |
625 | quite nicely into a call to C<pthread_atfork>: |
632 | quite nicely into a call to C<pthread_atfork>: |
626 | |
633 | |
… | |
… | |
628 | |
635 | |
629 | =item ev_loop_fork (loop) |
636 | =item ev_loop_fork (loop) |
630 | |
637 | |
631 | Like C<ev_default_fork>, but acts on an event loop created by |
638 | Like C<ev_default_fork>, but acts on an event loop created by |
632 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
639 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
633 | after fork that you want to re-use in the child, and how you do this is |
640 | after fork that you want to re-use in the child, and how you keep track of |
634 | entirely your own problem. |
641 | them is entirely your own problem. |
635 | |
642 | |
636 | =item int ev_is_default_loop (loop) |
643 | =item int ev_is_default_loop (loop) |
637 | |
644 | |
638 | Returns true when the given loop is, in fact, the default loop, and false |
645 | Returns true when the given loop is, in fact, the default loop, and false |
639 | otherwise. |
646 | otherwise. |
640 | |
647 | |
641 | =item unsigned int ev_loop_count (loop) |
648 | =item unsigned int ev_iteration (loop) |
642 | |
649 | |
643 | Returns the count of loop iterations for the loop, which is identical to |
650 | Returns the current iteration count for the event loop, which is identical |
644 | the number of times libev did poll for new events. It starts at C<0> and |
651 | to the number of times libev did poll for new events. It starts at C<0> |
645 | happily wraps around with enough iterations. |
652 | and happily wraps around with enough iterations. |
646 | |
653 | |
647 | This value can sometimes be useful as a generation counter of sorts (it |
654 | This value can sometimes be useful as a generation counter of sorts (it |
648 | "ticks" the number of loop iterations), as it roughly corresponds with |
655 | "ticks" the number of loop iterations), as it roughly corresponds with |
649 | C<ev_prepare> and C<ev_check> calls. |
656 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
|
|
657 | prepare and check phases. |
650 | |
658 | |
651 | =item unsigned int ev_loop_depth (loop) |
659 | =item unsigned int ev_depth (loop) |
652 | |
660 | |
653 | Returns the number of times C<ev_loop> was entered minus the number of |
661 | Returns the number of times C<ev_run> was entered minus the number of |
654 | times C<ev_loop> was exited, in other words, the recursion depth. |
662 | times C<ev_run> was exited, in other words, the recursion depth. |
655 | |
663 | |
656 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
664 | Outside C<ev_run>, this number is zero. In a callback, this number is |
657 | C<1>, unless C<ev_loop> was invoked recursively (or from another thread), |
665 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
658 | in which case it is higher. |
666 | in which case it is higher. |
659 | |
667 | |
660 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
668 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread |
661 | etc.), doesn't count as exit. |
669 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
|
|
670 | ungentleman-like behaviour unless it's really convenient. |
662 | |
671 | |
663 | =item unsigned int ev_backend (loop) |
672 | =item unsigned int ev_backend (loop) |
664 | |
673 | |
665 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
674 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
666 | use. |
675 | use. |
… | |
… | |
675 | |
684 | |
676 | =item ev_now_update (loop) |
685 | =item ev_now_update (loop) |
677 | |
686 | |
678 | Establishes the current time by querying the kernel, updating the time |
687 | Establishes the current time by querying the kernel, updating the time |
679 | returned by C<ev_now ()> in the progress. This is a costly operation and |
688 | returned by C<ev_now ()> in the progress. This is a costly operation and |
680 | is usually done automatically within C<ev_loop ()>. |
689 | is usually done automatically within C<ev_run ()>. |
681 | |
690 | |
682 | This function is rarely useful, but when some event callback runs for a |
691 | This function is rarely useful, but when some event callback runs for a |
683 | very long time without entering the event loop, updating libev's idea of |
692 | very long time without entering the event loop, updating libev's idea of |
684 | the current time is a good idea. |
693 | the current time is a good idea. |
685 | |
694 | |
… | |
… | |
687 | |
696 | |
688 | =item ev_suspend (loop) |
697 | =item ev_suspend (loop) |
689 | |
698 | |
690 | =item ev_resume (loop) |
699 | =item ev_resume (loop) |
691 | |
700 | |
692 | These two functions suspend and resume a loop, for use when the loop is |
701 | These two functions suspend and resume an event loop, for use when the |
693 | not used for a while and timeouts should not be processed. |
702 | loop is not used for a while and timeouts should not be processed. |
694 | |
703 | |
695 | A typical use case would be an interactive program such as a game: When |
704 | A typical use case would be an interactive program such as a game: When |
696 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
705 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
697 | would be best to handle timeouts as if no time had actually passed while |
706 | would be best to handle timeouts as if no time had actually passed while |
698 | the program was suspended. This can be achieved by calling C<ev_suspend> |
707 | the program was suspended. This can be achieved by calling C<ev_suspend> |
… | |
… | |
700 | C<ev_resume> directly afterwards to resume timer processing. |
709 | C<ev_resume> directly afterwards to resume timer processing. |
701 | |
710 | |
702 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
711 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
703 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
712 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
704 | will be rescheduled (that is, they will lose any events that would have |
713 | will be rescheduled (that is, they will lose any events that would have |
705 | occured while suspended). |
714 | occurred while suspended). |
706 | |
715 | |
707 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
716 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
708 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
717 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
709 | without a previous call to C<ev_suspend>. |
718 | without a previous call to C<ev_suspend>. |
710 | |
719 | |
711 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
720 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
712 | event loop time (see C<ev_now_update>). |
721 | event loop time (see C<ev_now_update>). |
713 | |
722 | |
714 | =item ev_loop (loop, int flags) |
723 | =item ev_run (loop, int flags) |
715 | |
724 | |
716 | Finally, this is it, the event handler. This function usually is called |
725 | Finally, this is it, the event handler. This function usually is called |
717 | after you have initialised all your watchers and you want to start |
726 | after you have initialised all your watchers and you want to start |
718 | handling events. |
727 | handling events. It will ask the operating system for any new events, call |
|
|
728 | the watcher callbacks, an then repeat the whole process indefinitely: This |
|
|
729 | is why event loops are called I<loops>. |
719 | |
730 | |
720 | If the flags argument is specified as C<0>, it will not return until |
731 | If the flags argument is specified as C<0>, it will keep handling events |
721 | either no event watchers are active anymore or C<ev_unloop> was called. |
732 | until either no event watchers are active anymore or C<ev_break> was |
|
|
733 | called. |
722 | |
734 | |
723 | Please note that an explicit C<ev_unloop> is usually better than |
735 | Please note that an explicit C<ev_break> is usually better than |
724 | relying on all watchers to be stopped when deciding when a program has |
736 | relying on all watchers to be stopped when deciding when a program has |
725 | finished (especially in interactive programs), but having a program |
737 | finished (especially in interactive programs), but having a program |
726 | that automatically loops as long as it has to and no longer by virtue |
738 | that automatically loops as long as it has to and no longer by virtue |
727 | of relying on its watchers stopping correctly, that is truly a thing of |
739 | of relying on its watchers stopping correctly, that is truly a thing of |
728 | beauty. |
740 | beauty. |
729 | |
741 | |
730 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
742 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
731 | those events and any already outstanding ones, but will not block your |
743 | those events and any already outstanding ones, but will not wait and |
732 | process in case there are no events and will return after one iteration of |
744 | block your process in case there are no events and will return after one |
733 | the loop. |
745 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
746 | events while doing lengthy calculations, to keep the program responsive. |
734 | |
747 | |
735 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
748 | A flags value of C<EVRUN_ONCE> will look for new events (waiting if |
736 | necessary) and will handle those and any already outstanding ones. It |
749 | necessary) and will handle those and any already outstanding ones. It |
737 | will block your process until at least one new event arrives (which could |
750 | will block your process until at least one new event arrives (which could |
738 | be an event internal to libev itself, so there is no guarantee that a |
751 | be an event internal to libev itself, so there is no guarantee that a |
739 | user-registered callback will be called), and will return after one |
752 | user-registered callback will be called), and will return after one |
740 | iteration of the loop. |
753 | iteration of the loop. |
741 | |
754 | |
742 | This is useful if you are waiting for some external event in conjunction |
755 | This is useful if you are waiting for some external event in conjunction |
743 | with something not expressible using other libev watchers (i.e. "roll your |
756 | with something not expressible using other libev watchers (i.e. "roll your |
744 | own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
757 | own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
745 | usually a better approach for this kind of thing. |
758 | usually a better approach for this kind of thing. |
746 | |
759 | |
747 | Here are the gory details of what C<ev_loop> does: |
760 | Here are the gory details of what C<ev_run> does: |
748 | |
761 | |
|
|
762 | - Increment loop depth. |
|
|
763 | - Reset the ev_break status. |
749 | - Before the first iteration, call any pending watchers. |
764 | - Before the first iteration, call any pending watchers. |
|
|
765 | LOOP: |
750 | * If EVFLAG_FORKCHECK was used, check for a fork. |
766 | - If EVFLAG_FORKCHECK was used, check for a fork. |
751 | - If a fork was detected (by any means), queue and call all fork watchers. |
767 | - If a fork was detected (by any means), queue and call all fork watchers. |
752 | - Queue and call all prepare watchers. |
768 | - Queue and call all prepare watchers. |
|
|
769 | - If ev_break was called, goto FINISH. |
753 | - If we have been forked, detach and recreate the kernel state |
770 | - If we have been forked, detach and recreate the kernel state |
754 | as to not disturb the other process. |
771 | as to not disturb the other process. |
755 | - Update the kernel state with all outstanding changes. |
772 | - Update the kernel state with all outstanding changes. |
756 | - Update the "event loop time" (ev_now ()). |
773 | - Update the "event loop time" (ev_now ()). |
757 | - Calculate for how long to sleep or block, if at all |
774 | - Calculate for how long to sleep or block, if at all |
758 | (active idle watchers, EVLOOP_NONBLOCK or not having |
775 | (active idle watchers, EVRUN_NOWAIT or not having |
759 | any active watchers at all will result in not sleeping). |
776 | any active watchers at all will result in not sleeping). |
760 | - Sleep if the I/O and timer collect interval say so. |
777 | - Sleep if the I/O and timer collect interval say so. |
|
|
778 | - Increment loop iteration counter. |
761 | - Block the process, waiting for any events. |
779 | - Block the process, waiting for any events. |
762 | - Queue all outstanding I/O (fd) events. |
780 | - Queue all outstanding I/O (fd) events. |
763 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
781 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
764 | - Queue all expired timers. |
782 | - Queue all expired timers. |
765 | - Queue all expired periodics. |
783 | - Queue all expired periodics. |
766 | - Unless any events are pending now, queue all idle watchers. |
784 | - Queue all idle watchers with priority higher than that of pending events. |
767 | - Queue all check watchers. |
785 | - Queue all check watchers. |
768 | - Call all queued watchers in reverse order (i.e. check watchers first). |
786 | - Call all queued watchers in reverse order (i.e. check watchers first). |
769 | Signals and child watchers are implemented as I/O watchers, and will |
787 | Signals and child watchers are implemented as I/O watchers, and will |
770 | be handled here by queueing them when their watcher gets executed. |
788 | be handled here by queueing them when their watcher gets executed. |
771 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
789 | - If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
772 | were used, or there are no active watchers, return, otherwise |
790 | were used, or there are no active watchers, goto FINISH, otherwise |
773 | continue with step *. |
791 | continue with step LOOP. |
|
|
792 | FINISH: |
|
|
793 | - Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
794 | - Decrement the loop depth. |
|
|
795 | - Return. |
774 | |
796 | |
775 | Example: Queue some jobs and then loop until no events are outstanding |
797 | Example: Queue some jobs and then loop until no events are outstanding |
776 | anymore. |
798 | anymore. |
777 | |
799 | |
778 | ... queue jobs here, make sure they register event watchers as long |
800 | ... queue jobs here, make sure they register event watchers as long |
779 | ... as they still have work to do (even an idle watcher will do..) |
801 | ... as they still have work to do (even an idle watcher will do..) |
780 | ev_loop (my_loop, 0); |
802 | ev_run (my_loop, 0); |
781 | ... jobs done or somebody called unloop. yeah! |
803 | ... jobs done or somebody called unloop. yeah! |
782 | |
804 | |
783 | =item ev_unloop (loop, how) |
805 | =item ev_break (loop, how) |
784 | |
806 | |
785 | Can be used to make a call to C<ev_loop> return early (but only after it |
807 | Can be used to make a call to C<ev_run> return early (but only after it |
786 | has processed all outstanding events). The C<how> argument must be either |
808 | has processed all outstanding events). The C<how> argument must be either |
787 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
809 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
788 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
810 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
789 | |
811 | |
790 | This "unloop state" will be cleared when entering C<ev_loop> again. |
812 | This "unloop state" will be cleared when entering C<ev_run> again. |
791 | |
813 | |
792 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
814 | It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO## |
793 | |
815 | |
794 | =item ev_ref (loop) |
816 | =item ev_ref (loop) |
795 | |
817 | |
796 | =item ev_unref (loop) |
818 | =item ev_unref (loop) |
797 | |
819 | |
798 | Ref/unref can be used to add or remove a reference count on the event |
820 | Ref/unref can be used to add or remove a reference count on the event |
799 | loop: Every watcher keeps one reference, and as long as the reference |
821 | loop: Every watcher keeps one reference, and as long as the reference |
800 | count is nonzero, C<ev_loop> will not return on its own. |
822 | count is nonzero, C<ev_run> will not return on its own. |
801 | |
823 | |
802 | This is useful when you have a watcher that you never intend to |
824 | This is useful when you have a watcher that you never intend to |
803 | unregister, but that nevertheless should not keep C<ev_loop> from |
825 | unregister, but that nevertheless should not keep C<ev_run> from |
804 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
826 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
805 | before stopping it. |
827 | before stopping it. |
806 | |
828 | |
807 | As an example, libev itself uses this for its internal signal pipe: It |
829 | As an example, libev itself uses this for its internal signal pipe: It |
808 | is not visible to the libev user and should not keep C<ev_loop> from |
830 | is not visible to the libev user and should not keep C<ev_run> from |
809 | exiting if no event watchers registered by it are active. It is also an |
831 | exiting if no event watchers registered by it are active. It is also an |
810 | excellent way to do this for generic recurring timers or from within |
832 | excellent way to do this for generic recurring timers or from within |
811 | third-party libraries. Just remember to I<unref after start> and I<ref |
833 | third-party libraries. Just remember to I<unref after start> and I<ref |
812 | before stop> (but only if the watcher wasn't active before, or was active |
834 | before stop> (but only if the watcher wasn't active before, or was active |
813 | before, respectively. Note also that libev might stop watchers itself |
835 | before, respectively. Note also that libev might stop watchers itself |
814 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
836 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
815 | in the callback). |
837 | in the callback). |
816 | |
838 | |
817 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
839 | Example: Create a signal watcher, but keep it from keeping C<ev_run> |
818 | running when nothing else is active. |
840 | running when nothing else is active. |
819 | |
841 | |
820 | ev_signal exitsig; |
842 | ev_signal exitsig; |
821 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
843 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
822 | ev_signal_start (loop, &exitsig); |
844 | ev_signal_start (loop, &exitsig); |
… | |
… | |
867 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
889 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
868 | as this approaches the timing granularity of most systems. Note that if |
890 | as this approaches the timing granularity of most systems. Note that if |
869 | you do transactions with the outside world and you can't increase the |
891 | you do transactions with the outside world and you can't increase the |
870 | parallelity, then this setting will limit your transaction rate (if you |
892 | parallelity, then this setting will limit your transaction rate (if you |
871 | need to poll once per transaction and the I/O collect interval is 0.01, |
893 | need to poll once per transaction and the I/O collect interval is 0.01, |
872 | then you can't do more than 100 transations per second). |
894 | then you can't do more than 100 transactions per second). |
873 | |
895 | |
874 | Setting the I<timeout collect interval> can improve the opportunity for |
896 | Setting the I<timeout collect interval> can improve the opportunity for |
875 | saving power, as the program will "bundle" timer callback invocations that |
897 | saving power, as the program will "bundle" timer callback invocations that |
876 | are "near" in time together, by delaying some, thus reducing the number of |
898 | are "near" in time together, by delaying some, thus reducing the number of |
877 | times the process sleeps and wakes up again. Another useful technique to |
899 | times the process sleeps and wakes up again. Another useful technique to |
… | |
… | |
885 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
907 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
886 | |
908 | |
887 | =item ev_invoke_pending (loop) |
909 | =item ev_invoke_pending (loop) |
888 | |
910 | |
889 | This call will simply invoke all pending watchers while resetting their |
911 | This call will simply invoke all pending watchers while resetting their |
890 | pending state. Normally, C<ev_loop> does this automatically when required, |
912 | pending state. Normally, C<ev_run> does this automatically when required, |
891 | but when overriding the invoke callback this call comes handy. |
913 | but when overriding the invoke callback this call comes handy. |
892 | |
914 | |
893 | =item int ev_pending_count (loop) |
915 | =item int ev_pending_count (loop) |
894 | |
916 | |
895 | Returns the number of pending watchers - zero indicates that no watchers |
917 | Returns the number of pending watchers - zero indicates that no watchers |
896 | are pending. |
918 | are pending. |
897 | |
919 | |
898 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
920 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
899 | |
921 | |
900 | This overrides the invoke pending functionality of the loop: Instead of |
922 | This overrides the invoke pending functionality of the loop: Instead of |
901 | invoking all pending watchers when there are any, C<ev_loop> will call |
923 | invoking all pending watchers when there are any, C<ev_run> will call |
902 | this callback instead. This is useful, for example, when you want to |
924 | this callback instead. This is useful, for example, when you want to |
903 | invoke the actual watchers inside another context (another thread etc.). |
925 | invoke the actual watchers inside another context (another thread etc.). |
904 | |
926 | |
905 | If you want to reset the callback, use C<ev_invoke_pending> as new |
927 | If you want to reset the callback, use C<ev_invoke_pending> as new |
906 | callback. |
928 | callback. |
… | |
… | |
909 | |
931 | |
910 | Sometimes you want to share the same loop between multiple threads. This |
932 | Sometimes you want to share the same loop between multiple threads. This |
911 | can be done relatively simply by putting mutex_lock/unlock calls around |
933 | can be done relatively simply by putting mutex_lock/unlock calls around |
912 | each call to a libev function. |
934 | each call to a libev function. |
913 | |
935 | |
914 | However, C<ev_loop> can run an indefinite time, so it is not feasible to |
936 | However, C<ev_run> can run an indefinite time, so it is not feasible |
915 | wait for it to return. One way around this is to wake up the loop via |
937 | to wait for it to return. One way around this is to wake up the event |
916 | C<ev_unloop> and C<av_async_send>, another way is to set these I<release> |
938 | loop via C<ev_break> and C<av_async_send>, another way is to set these |
917 | and I<acquire> callbacks on the loop. |
939 | I<release> and I<acquire> callbacks on the loop. |
918 | |
940 | |
919 | When set, then C<release> will be called just before the thread is |
941 | When set, then C<release> will be called just before the thread is |
920 | suspended waiting for new events, and C<acquire> is called just |
942 | suspended waiting for new events, and C<acquire> is called just |
921 | afterwards. |
943 | afterwards. |
922 | |
944 | |
… | |
… | |
925 | |
947 | |
926 | While event loop modifications are allowed between invocations of |
948 | While event loop modifications are allowed between invocations of |
927 | C<release> and C<acquire> (that's their only purpose after all), no |
949 | C<release> and C<acquire> (that's their only purpose after all), no |
928 | modifications done will affect the event loop, i.e. adding watchers will |
950 | modifications done will affect the event loop, i.e. adding watchers will |
929 | have no effect on the set of file descriptors being watched, or the time |
951 | have no effect on the set of file descriptors being watched, or the time |
930 | waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it |
952 | waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it |
931 | to take note of any changes you made. |
953 | to take note of any changes you made. |
932 | |
954 | |
933 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
955 | In theory, threads executing C<ev_run> will be async-cancel safe between |
934 | invocations of C<release> and C<acquire>. |
956 | invocations of C<release> and C<acquire>. |
935 | |
957 | |
936 | See also the locking example in the C<THREADS> section later in this |
958 | See also the locking example in the C<THREADS> section later in this |
937 | document. |
959 | document. |
938 | |
960 | |
… | |
… | |
947 | These two functions can be used to associate arbitrary data with a loop, |
969 | These two functions can be used to associate arbitrary data with a loop, |
948 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
970 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
949 | C<acquire> callbacks described above, but of course can be (ab-)used for |
971 | C<acquire> callbacks described above, but of course can be (ab-)used for |
950 | any other purpose as well. |
972 | any other purpose as well. |
951 | |
973 | |
952 | =item ev_loop_verify (loop) |
974 | =item ev_verify (loop) |
953 | |
975 | |
954 | This function only does something when C<EV_VERIFY> support has been |
976 | This function only does something when C<EV_VERIFY> support has been |
955 | compiled in, which is the default for non-minimal builds. It tries to go |
977 | compiled in, which is the default for non-minimal builds. It tries to go |
956 | through all internal structures and checks them for validity. If anything |
978 | through all internal structures and checks them for validity. If anything |
957 | is found to be inconsistent, it will print an error message to standard |
979 | is found to be inconsistent, it will print an error message to standard |
… | |
… | |
975 | become readable, you would create an C<ev_io> watcher for that: |
997 | become readable, you would create an C<ev_io> watcher for that: |
976 | |
998 | |
977 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
999 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
978 | { |
1000 | { |
979 | ev_io_stop (w); |
1001 | ev_io_stop (w); |
980 | ev_unloop (loop, EVUNLOOP_ALL); |
1002 | ev_break (loop, EVBREAK_ALL); |
981 | } |
1003 | } |
982 | |
1004 | |
983 | struct ev_loop *loop = ev_default_loop (0); |
1005 | struct ev_loop *loop = ev_default_loop (0); |
984 | |
1006 | |
985 | ev_io stdin_watcher; |
1007 | ev_io stdin_watcher; |
986 | |
1008 | |
987 | ev_init (&stdin_watcher, my_cb); |
1009 | ev_init (&stdin_watcher, my_cb); |
988 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1010 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
989 | ev_io_start (loop, &stdin_watcher); |
1011 | ev_io_start (loop, &stdin_watcher); |
990 | |
1012 | |
991 | ev_loop (loop, 0); |
1013 | ev_run (loop, 0); |
992 | |
1014 | |
993 | As you can see, you are responsible for allocating the memory for your |
1015 | As you can see, you are responsible for allocating the memory for your |
994 | watcher structures (and it is I<usually> a bad idea to do this on the |
1016 | watcher structures (and it is I<usually> a bad idea to do this on the |
995 | stack). |
1017 | stack). |
996 | |
1018 | |
… | |
… | |
1032 | =item C<EV_WRITE> |
1054 | =item C<EV_WRITE> |
1033 | |
1055 | |
1034 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1056 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1035 | writable. |
1057 | writable. |
1036 | |
1058 | |
1037 | =item C<EV_TIMEOUT> |
1059 | =item C<EV_TIMER> |
1038 | |
1060 | |
1039 | The C<ev_timer> watcher has timed out. |
1061 | The C<ev_timer> watcher has timed out. |
1040 | |
1062 | |
1041 | =item C<EV_PERIODIC> |
1063 | =item C<EV_PERIODIC> |
1042 | |
1064 | |
… | |
… | |
1060 | |
1082 | |
1061 | =item C<EV_PREPARE> |
1083 | =item C<EV_PREPARE> |
1062 | |
1084 | |
1063 | =item C<EV_CHECK> |
1085 | =item C<EV_CHECK> |
1064 | |
1086 | |
1065 | All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts |
1087 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
1066 | to gather new events, and all C<ev_check> watchers are invoked just after |
1088 | to gather new events, and all C<ev_check> watchers are invoked just after |
1067 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
1089 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
1068 | received events. Callbacks of both watcher types can start and stop as |
1090 | received events. Callbacks of both watcher types can start and stop as |
1069 | many watchers as they want, and all of them will be taken into account |
1091 | many watchers as they want, and all of them will be taken into account |
1070 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1092 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1071 | C<ev_loop> from blocking). |
1093 | C<ev_run> from blocking). |
1072 | |
1094 | |
1073 | =item C<EV_EMBED> |
1095 | =item C<EV_EMBED> |
1074 | |
1096 | |
1075 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1097 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1076 | |
1098 | |
… | |
… | |
1375 | |
1397 | |
1376 | For example, to emulate how many other event libraries handle priorities, |
1398 | For example, to emulate how many other event libraries handle priorities, |
1377 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1399 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1378 | the normal watcher callback, you just start the idle watcher. The real |
1400 | the normal watcher callback, you just start the idle watcher. The real |
1379 | processing is done in the idle watcher callback. This causes libev to |
1401 | processing is done in the idle watcher callback. This causes libev to |
1380 | continously poll and process kernel event data for the watcher, but when |
1402 | continuously poll and process kernel event data for the watcher, but when |
1381 | the lock-out case is known to be rare (which in turn is rare :), this is |
1403 | the lock-out case is known to be rare (which in turn is rare :), this is |
1382 | workable. |
1404 | workable. |
1383 | |
1405 | |
1384 | Usually, however, the lock-out model implemented that way will perform |
1406 | Usually, however, the lock-out model implemented that way will perform |
1385 | miserably under the type of load it was designed to handle. In that case, |
1407 | miserably under the type of load it was designed to handle. In that case, |
… | |
… | |
1399 | { |
1421 | { |
1400 | // stop the I/O watcher, we received the event, but |
1422 | // stop the I/O watcher, we received the event, but |
1401 | // are not yet ready to handle it. |
1423 | // are not yet ready to handle it. |
1402 | ev_io_stop (EV_A_ w); |
1424 | ev_io_stop (EV_A_ w); |
1403 | |
1425 | |
1404 | // start the idle watcher to ahndle the actual event. |
1426 | // start the idle watcher to handle the actual event. |
1405 | // it will not be executed as long as other watchers |
1427 | // it will not be executed as long as other watchers |
1406 | // with the default priority are receiving events. |
1428 | // with the default priority are receiving events. |
1407 | ev_idle_start (EV_A_ &idle); |
1429 | ev_idle_start (EV_A_ &idle); |
1408 | } |
1430 | } |
1409 | |
1431 | |
… | |
… | |
1463 | |
1485 | |
1464 | If you cannot use non-blocking mode, then force the use of a |
1486 | If you cannot use non-blocking mode, then force the use of a |
1465 | known-to-be-good backend (at the time of this writing, this includes only |
1487 | known-to-be-good backend (at the time of this writing, this includes only |
1466 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1488 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1467 | descriptors for which non-blocking operation makes no sense (such as |
1489 | descriptors for which non-blocking operation makes no sense (such as |
1468 | files) - libev doesn't guarentee any specific behaviour in that case. |
1490 | files) - libev doesn't guarantee any specific behaviour in that case. |
1469 | |
1491 | |
1470 | Another thing you have to watch out for is that it is quite easy to |
1492 | Another thing you have to watch out for is that it is quite easy to |
1471 | receive "spurious" readiness notifications, that is your callback might |
1493 | receive "spurious" readiness notifications, that is your callback might |
1472 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1494 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1473 | because there is no data. Not only are some backends known to create a |
1495 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1541 | somewhere, as that would have given you a big clue). |
1563 | somewhere, as that would have given you a big clue). |
1542 | |
1564 | |
1543 | =head3 The special problem of accept()ing when you can't |
1565 | =head3 The special problem of accept()ing when you can't |
1544 | |
1566 | |
1545 | Many implementations of the POSIX C<accept> function (for example, |
1567 | Many implementations of the POSIX C<accept> function (for example, |
1546 | found in port-2004 Linux) have the peculiar behaviour of not removing a |
1568 | found in post-2004 Linux) have the peculiar behaviour of not removing a |
1547 | connection from the pending queue in all error cases. |
1569 | connection from the pending queue in all error cases. |
1548 | |
1570 | |
1549 | For example, larger servers often run out of file descriptors (because |
1571 | For example, larger servers often run out of file descriptors (because |
1550 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
1572 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
1551 | rejecting the connection, leading to libev signalling readiness on |
1573 | rejecting the connection, leading to libev signalling readiness on |
… | |
… | |
1617 | ... |
1639 | ... |
1618 | struct ev_loop *loop = ev_default_init (0); |
1640 | struct ev_loop *loop = ev_default_init (0); |
1619 | ev_io stdin_readable; |
1641 | ev_io stdin_readable; |
1620 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1642 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1621 | ev_io_start (loop, &stdin_readable); |
1643 | ev_io_start (loop, &stdin_readable); |
1622 | ev_loop (loop, 0); |
1644 | ev_run (loop, 0); |
1623 | |
1645 | |
1624 | |
1646 | |
1625 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1647 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1626 | |
1648 | |
1627 | Timer watchers are simple relative timers that generate an event after a |
1649 | Timer watchers are simple relative timers that generate an event after a |
… | |
… | |
1636 | The callback is guaranteed to be invoked only I<after> its timeout has |
1658 | The callback is guaranteed to be invoked only I<after> its timeout has |
1637 | passed (not I<at>, so on systems with very low-resolution clocks this |
1659 | passed (not I<at>, so on systems with very low-resolution clocks this |
1638 | might introduce a small delay). If multiple timers become ready during the |
1660 | might introduce a small delay). If multiple timers become ready during the |
1639 | same loop iteration then the ones with earlier time-out values are invoked |
1661 | same loop iteration then the ones with earlier time-out values are invoked |
1640 | before ones of the same priority with later time-out values (but this is |
1662 | before ones of the same priority with later time-out values (but this is |
1641 | no longer true when a callback calls C<ev_loop> recursively). |
1663 | no longer true when a callback calls C<ev_run> recursively). |
1642 | |
1664 | |
1643 | =head3 Be smart about timeouts |
1665 | =head3 Be smart about timeouts |
1644 | |
1666 | |
1645 | Many real-world problems involve some kind of timeout, usually for error |
1667 | Many real-world problems involve some kind of timeout, usually for error |
1646 | recovery. A typical example is an HTTP request - if the other side hangs, |
1668 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
1732 | ev_tstamp timeout = last_activity + 60.; |
1754 | ev_tstamp timeout = last_activity + 60.; |
1733 | |
1755 | |
1734 | // if last_activity + 60. is older than now, we did time out |
1756 | // if last_activity + 60. is older than now, we did time out |
1735 | if (timeout < now) |
1757 | if (timeout < now) |
1736 | { |
1758 | { |
1737 | // timeout occured, take action |
1759 | // timeout occurred, take action |
1738 | } |
1760 | } |
1739 | else |
1761 | else |
1740 | { |
1762 | { |
1741 | // callback was invoked, but there was some activity, re-arm |
1763 | // callback was invoked, but there was some activity, re-arm |
1742 | // the watcher to fire in last_activity + 60, which is |
1764 | // the watcher to fire in last_activity + 60, which is |
… | |
… | |
1764 | to the current time (meaning we just have some activity :), then call the |
1786 | to the current time (meaning we just have some activity :), then call the |
1765 | callback, which will "do the right thing" and start the timer: |
1787 | callback, which will "do the right thing" and start the timer: |
1766 | |
1788 | |
1767 | ev_init (timer, callback); |
1789 | ev_init (timer, callback); |
1768 | last_activity = ev_now (loop); |
1790 | last_activity = ev_now (loop); |
1769 | callback (loop, timer, EV_TIMEOUT); |
1791 | callback (loop, timer, EV_TIMER); |
1770 | |
1792 | |
1771 | And when there is some activity, simply store the current time in |
1793 | And when there is some activity, simply store the current time in |
1772 | C<last_activity>, no libev calls at all: |
1794 | C<last_activity>, no libev calls at all: |
1773 | |
1795 | |
1774 | last_actiivty = ev_now (loop); |
1796 | last_activity = ev_now (loop); |
1775 | |
1797 | |
1776 | This technique is slightly more complex, but in most cases where the |
1798 | This technique is slightly more complex, but in most cases where the |
1777 | time-out is unlikely to be triggered, much more efficient. |
1799 | time-out is unlikely to be triggered, much more efficient. |
1778 | |
1800 | |
1779 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
1801 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
… | |
… | |
1817 | |
1839 | |
1818 | =head3 The special problem of time updates |
1840 | =head3 The special problem of time updates |
1819 | |
1841 | |
1820 | Establishing the current time is a costly operation (it usually takes at |
1842 | Establishing the current time is a costly operation (it usually takes at |
1821 | least two system calls): EV therefore updates its idea of the current |
1843 | least two system calls): EV therefore updates its idea of the current |
1822 | time only before and after C<ev_loop> collects new events, which causes a |
1844 | time only before and after C<ev_run> collects new events, which causes a |
1823 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1845 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1824 | lots of events in one iteration. |
1846 | lots of events in one iteration. |
1825 | |
1847 | |
1826 | The relative timeouts are calculated relative to the C<ev_now ()> |
1848 | The relative timeouts are calculated relative to the C<ev_now ()> |
1827 | time. This is usually the right thing as this timestamp refers to the time |
1849 | time. This is usually the right thing as this timestamp refers to the time |
… | |
… | |
1944 | } |
1966 | } |
1945 | |
1967 | |
1946 | ev_timer mytimer; |
1968 | ev_timer mytimer; |
1947 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1969 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1948 | ev_timer_again (&mytimer); /* start timer */ |
1970 | ev_timer_again (&mytimer); /* start timer */ |
1949 | ev_loop (loop, 0); |
1971 | ev_run (loop, 0); |
1950 | |
1972 | |
1951 | // and in some piece of code that gets executed on any "activity": |
1973 | // and in some piece of code that gets executed on any "activity": |
1952 | // reset the timeout to start ticking again at 10 seconds |
1974 | // reset the timeout to start ticking again at 10 seconds |
1953 | ev_timer_again (&mytimer); |
1975 | ev_timer_again (&mytimer); |
1954 | |
1976 | |
… | |
… | |
1980 | |
2002 | |
1981 | As with timers, the callback is guaranteed to be invoked only when the |
2003 | As with timers, the callback is guaranteed to be invoked only when the |
1982 | point in time where it is supposed to trigger has passed. If multiple |
2004 | point in time where it is supposed to trigger has passed. If multiple |
1983 | timers become ready during the same loop iteration then the ones with |
2005 | timers become ready during the same loop iteration then the ones with |
1984 | earlier time-out values are invoked before ones with later time-out values |
2006 | earlier time-out values are invoked before ones with later time-out values |
1985 | (but this is no longer true when a callback calls C<ev_loop> recursively). |
2007 | (but this is no longer true when a callback calls C<ev_run> recursively). |
1986 | |
2008 | |
1987 | =head3 Watcher-Specific Functions and Data Members |
2009 | =head3 Watcher-Specific Functions and Data Members |
1988 | |
2010 | |
1989 | =over 4 |
2011 | =over 4 |
1990 | |
2012 | |
… | |
… | |
2118 | Example: Call a callback every hour, or, more precisely, whenever the |
2140 | Example: Call a callback every hour, or, more precisely, whenever the |
2119 | system time is divisible by 3600. The callback invocation times have |
2141 | system time is divisible by 3600. The callback invocation times have |
2120 | potentially a lot of jitter, but good long-term stability. |
2142 | potentially a lot of jitter, but good long-term stability. |
2121 | |
2143 | |
2122 | static void |
2144 | static void |
2123 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2145 | clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
2124 | { |
2146 | { |
2125 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2147 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2126 | } |
2148 | } |
2127 | |
2149 | |
2128 | ev_periodic hourly_tick; |
2150 | ev_periodic hourly_tick; |
… | |
… | |
2228 | Example: Try to exit cleanly on SIGINT. |
2250 | Example: Try to exit cleanly on SIGINT. |
2229 | |
2251 | |
2230 | static void |
2252 | static void |
2231 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2253 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2232 | { |
2254 | { |
2233 | ev_unloop (loop, EVUNLOOP_ALL); |
2255 | ev_break (loop, EVBREAK_ALL); |
2234 | } |
2256 | } |
2235 | |
2257 | |
2236 | ev_signal signal_watcher; |
2258 | ev_signal signal_watcher; |
2237 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2259 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2238 | ev_signal_start (loop, &signal_watcher); |
2260 | ev_signal_start (loop, &signal_watcher); |
… | |
… | |
2624 | |
2646 | |
2625 | Prepare and check watchers are usually (but not always) used in pairs: |
2647 | Prepare and check watchers are usually (but not always) used in pairs: |
2626 | prepare watchers get invoked before the process blocks and check watchers |
2648 | prepare watchers get invoked before the process blocks and check watchers |
2627 | afterwards. |
2649 | afterwards. |
2628 | |
2650 | |
2629 | You I<must not> call C<ev_loop> or similar functions that enter |
2651 | You I<must not> call C<ev_run> or similar functions that enter |
2630 | the current event loop from either C<ev_prepare> or C<ev_check> |
2652 | the current event loop from either C<ev_prepare> or C<ev_check> |
2631 | watchers. Other loops than the current one are fine, however. The |
2653 | watchers. Other loops than the current one are fine, however. The |
2632 | rationale behind this is that you do not need to check for recursion in |
2654 | rationale behind this is that you do not need to check for recursion in |
2633 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2655 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2634 | C<ev_check> so if you have one watcher of each kind they will always be |
2656 | C<ev_check> so if you have one watcher of each kind they will always be |
… | |
… | |
2802 | |
2824 | |
2803 | if (timeout >= 0) |
2825 | if (timeout >= 0) |
2804 | // create/start timer |
2826 | // create/start timer |
2805 | |
2827 | |
2806 | // poll |
2828 | // poll |
2807 | ev_loop (EV_A_ 0); |
2829 | ev_run (EV_A_ 0); |
2808 | |
2830 | |
2809 | // stop timer again |
2831 | // stop timer again |
2810 | if (timeout >= 0) |
2832 | if (timeout >= 0) |
2811 | ev_timer_stop (EV_A_ &to); |
2833 | ev_timer_stop (EV_A_ &to); |
2812 | |
2834 | |
… | |
… | |
2890 | if you do not want that, you need to temporarily stop the embed watcher). |
2912 | if you do not want that, you need to temporarily stop the embed watcher). |
2891 | |
2913 | |
2892 | =item ev_embed_sweep (loop, ev_embed *) |
2914 | =item ev_embed_sweep (loop, ev_embed *) |
2893 | |
2915 | |
2894 | Make a single, non-blocking sweep over the embedded loop. This works |
2916 | Make a single, non-blocking sweep over the embedded loop. This works |
2895 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
2917 | similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most |
2896 | appropriate way for embedded loops. |
2918 | appropriate way for embedded loops. |
2897 | |
2919 | |
2898 | =item struct ev_loop *other [read-only] |
2920 | =item struct ev_loop *other [read-only] |
2899 | |
2921 | |
2900 | The embedded event loop. |
2922 | The embedded event loop. |
… | |
… | |
2960 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2982 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2961 | handlers will be invoked, too, of course. |
2983 | handlers will be invoked, too, of course. |
2962 | |
2984 | |
2963 | =head3 The special problem of life after fork - how is it possible? |
2985 | =head3 The special problem of life after fork - how is it possible? |
2964 | |
2986 | |
2965 | Most uses of C<fork()> consist of forking, then some simple calls to ste |
2987 | Most uses of C<fork()> consist of forking, then some simple calls to set |
2966 | up/change the process environment, followed by a call to C<exec()>. This |
2988 | up/change the process environment, followed by a call to C<exec()>. This |
2967 | sequence should be handled by libev without any problems. |
2989 | sequence should be handled by libev without any problems. |
2968 | |
2990 | |
2969 | This changes when the application actually wants to do event handling |
2991 | This changes when the application actually wants to do event handling |
2970 | in the child, or both parent in child, in effect "continuing" after the |
2992 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
3004 | believe me. |
3026 | believe me. |
3005 | |
3027 | |
3006 | =back |
3028 | =back |
3007 | |
3029 | |
3008 | |
3030 | |
3009 | =head2 C<ev_async> - how to wake up another event loop |
3031 | =head2 C<ev_async> - how to wake up an event loop |
3010 | |
3032 | |
3011 | In general, you cannot use an C<ev_loop> from multiple threads or other |
3033 | In general, you cannot use an C<ev_run> from multiple threads or other |
3012 | asynchronous sources such as signal handlers (as opposed to multiple event |
3034 | asynchronous sources such as signal handlers (as opposed to multiple event |
3013 | loops - those are of course safe to use in different threads). |
3035 | loops - those are of course safe to use in different threads). |
3014 | |
3036 | |
3015 | Sometimes, however, you need to wake up another event loop you do not |
3037 | Sometimes, however, you need to wake up an event loop you do not control, |
3016 | control, for example because it belongs to another thread. This is what |
3038 | for example because it belongs to another thread. This is what C<ev_async> |
3017 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
3039 | watchers do: as long as the C<ev_async> watcher is active, you can signal |
3018 | can signal it by calling C<ev_async_send>, which is thread- and signal |
3040 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3019 | safe. |
|
|
3020 | |
3041 | |
3021 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3042 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3022 | too, are asynchronous in nature, and signals, too, will be compressed |
3043 | too, are asynchronous in nature, and signals, too, will be compressed |
3023 | (i.e. the number of callback invocations may be less than the number of |
3044 | (i.e. the number of callback invocations may be less than the number of |
3024 | C<ev_async_sent> calls). |
3045 | C<ev_async_sent> calls). |
… | |
… | |
3179 | |
3200 | |
3180 | If C<timeout> is less than 0, then no timeout watcher will be |
3201 | If C<timeout> is less than 0, then no timeout watcher will be |
3181 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3202 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3182 | repeat = 0) will be started. C<0> is a valid timeout. |
3203 | repeat = 0) will be started. C<0> is a valid timeout. |
3183 | |
3204 | |
3184 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
3205 | The callback has the type C<void (*cb)(int revents, void *arg)> and is |
3185 | passed an C<revents> set like normal event callbacks (a combination of |
3206 | passed an C<revents> set like normal event callbacks (a combination of |
3186 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
3207 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg> |
3187 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3208 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3188 | a timeout and an io event at the same time - you probably should give io |
3209 | a timeout and an io event at the same time - you probably should give io |
3189 | events precedence. |
3210 | events precedence. |
3190 | |
3211 | |
3191 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3212 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3192 | |
3213 | |
3193 | static void stdin_ready (int revents, void *arg) |
3214 | static void stdin_ready (int revents, void *arg) |
3194 | { |
3215 | { |
3195 | if (revents & EV_READ) |
3216 | if (revents & EV_READ) |
3196 | /* stdin might have data for us, joy! */; |
3217 | /* stdin might have data for us, joy! */; |
3197 | else if (revents & EV_TIMEOUT) |
3218 | else if (revents & EV_TIMER) |
3198 | /* doh, nothing entered */; |
3219 | /* doh, nothing entered */; |
3199 | } |
3220 | } |
3200 | |
3221 | |
3201 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3222 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3202 | |
3223 | |
… | |
… | |
3336 | myclass obj; |
3357 | myclass obj; |
3337 | ev::io iow; |
3358 | ev::io iow; |
3338 | iow.set <myclass, &myclass::io_cb> (&obj); |
3359 | iow.set <myclass, &myclass::io_cb> (&obj); |
3339 | |
3360 | |
3340 | =item w->set (object *) |
3361 | =item w->set (object *) |
3341 | |
|
|
3342 | This is an B<experimental> feature that might go away in a future version. |
|
|
3343 | |
3362 | |
3344 | This is a variation of a method callback - leaving out the method to call |
3363 | This is a variation of a method callback - leaving out the method to call |
3345 | will default the method to C<operator ()>, which makes it possible to use |
3364 | will default the method to C<operator ()>, which makes it possible to use |
3346 | functor objects without having to manually specify the C<operator ()> all |
3365 | functor objects without having to manually specify the C<operator ()> all |
3347 | the time. Incidentally, you can then also leave out the template argument |
3366 | the time. Incidentally, you can then also leave out the template argument |
… | |
… | |
3387 | Associates a different C<struct ev_loop> with this watcher. You can only |
3406 | Associates a different C<struct ev_loop> with this watcher. You can only |
3388 | do this when the watcher is inactive (and not pending either). |
3407 | do this when the watcher is inactive (and not pending either). |
3389 | |
3408 | |
3390 | =item w->set ([arguments]) |
3409 | =item w->set ([arguments]) |
3391 | |
3410 | |
3392 | Basically the same as C<ev_TYPE_set>, with the same arguments. Must be |
3411 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
3393 | called at least once. Unlike the C counterpart, an active watcher gets |
3412 | method or a suitable start method must be called at least once. Unlike the |
3394 | automatically stopped and restarted when reconfiguring it with this |
3413 | C counterpart, an active watcher gets automatically stopped and restarted |
3395 | method. |
3414 | when reconfiguring it with this method. |
3396 | |
3415 | |
3397 | =item w->start () |
3416 | =item w->start () |
3398 | |
3417 | |
3399 | Starts the watcher. Note that there is no C<loop> argument, as the |
3418 | Starts the watcher. Note that there is no C<loop> argument, as the |
3400 | constructor already stores the event loop. |
3419 | constructor already stores the event loop. |
3401 | |
3420 | |
|
|
3421 | =item w->start ([arguments]) |
|
|
3422 | |
|
|
3423 | Instead of calling C<set> and C<start> methods separately, it is often |
|
|
3424 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
3425 | the configure C<set> method of the watcher. |
|
|
3426 | |
3402 | =item w->stop () |
3427 | =item w->stop () |
3403 | |
3428 | |
3404 | Stops the watcher if it is active. Again, no C<loop> argument. |
3429 | Stops the watcher if it is active. Again, no C<loop> argument. |
3405 | |
3430 | |
3406 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
3431 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
… | |
… | |
3418 | |
3443 | |
3419 | =back |
3444 | =back |
3420 | |
3445 | |
3421 | =back |
3446 | =back |
3422 | |
3447 | |
3423 | Example: Define a class with an IO and idle watcher, start one of them in |
3448 | Example: Define a class with two I/O and idle watchers, start the I/O |
3424 | the constructor. |
3449 | watchers in the constructor. |
3425 | |
3450 | |
3426 | class myclass |
3451 | class myclass |
3427 | { |
3452 | { |
3428 | ev::io io ; void io_cb (ev::io &w, int revents); |
3453 | ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
3454 | ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
3429 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3455 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3430 | |
3456 | |
3431 | myclass (int fd) |
3457 | myclass (int fd) |
3432 | { |
3458 | { |
3433 | io .set <myclass, &myclass::io_cb > (this); |
3459 | io .set <myclass, &myclass::io_cb > (this); |
|
|
3460 | io2 .set <myclass, &myclass::io2_cb > (this); |
3434 | idle.set <myclass, &myclass::idle_cb> (this); |
3461 | idle.set <myclass, &myclass::idle_cb> (this); |
3435 | |
3462 | |
3436 | io.start (fd, ev::READ); |
3463 | io.set (fd, ev::WRITE); // configure the watcher |
|
|
3464 | io.start (); // start it whenever convenient |
|
|
3465 | |
|
|
3466 | io2.start (fd, ev::READ); // set + start in one call |
3437 | } |
3467 | } |
3438 | }; |
3468 | }; |
3439 | |
3469 | |
3440 | |
3470 | |
3441 | =head1 OTHER LANGUAGE BINDINGS |
3471 | =head1 OTHER LANGUAGE BINDINGS |
… | |
… | |
3515 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3545 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3516 | C<EV_A_> is used when other arguments are following. Example: |
3546 | C<EV_A_> is used when other arguments are following. Example: |
3517 | |
3547 | |
3518 | ev_unref (EV_A); |
3548 | ev_unref (EV_A); |
3519 | ev_timer_add (EV_A_ watcher); |
3549 | ev_timer_add (EV_A_ watcher); |
3520 | ev_loop (EV_A_ 0); |
3550 | ev_run (EV_A_ 0); |
3521 | |
3551 | |
3522 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3552 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3523 | which is often provided by the following macro. |
3553 | which is often provided by the following macro. |
3524 | |
3554 | |
3525 | =item C<EV_P>, C<EV_P_> |
3555 | =item C<EV_P>, C<EV_P_> |
… | |
… | |
3565 | } |
3595 | } |
3566 | |
3596 | |
3567 | ev_check check; |
3597 | ev_check check; |
3568 | ev_check_init (&check, check_cb); |
3598 | ev_check_init (&check, check_cb); |
3569 | ev_check_start (EV_DEFAULT_ &check); |
3599 | ev_check_start (EV_DEFAULT_ &check); |
3570 | ev_loop (EV_DEFAULT_ 0); |
3600 | ev_run (EV_DEFAULT_ 0); |
3571 | |
3601 | |
3572 | =head1 EMBEDDING |
3602 | =head1 EMBEDDING |
3573 | |
3603 | |
3574 | Libev can (and often is) directly embedded into host |
3604 | Libev can (and often is) directly embedded into host |
3575 | applications. Examples of applications that embed it include the Deliantra |
3605 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3660 | define before including (or compiling) any of its files. The default in |
3690 | define before including (or compiling) any of its files. The default in |
3661 | the absence of autoconf is documented for every option. |
3691 | the absence of autoconf is documented for every option. |
3662 | |
3692 | |
3663 | Symbols marked with "(h)" do not change the ABI, and can have different |
3693 | Symbols marked with "(h)" do not change the ABI, and can have different |
3664 | values when compiling libev vs. including F<ev.h>, so it is permissible |
3694 | values when compiling libev vs. including F<ev.h>, so it is permissible |
3665 | to redefine them before including F<ev.h> without breakign compatibility |
3695 | to redefine them before including F<ev.h> without breaking compatibility |
3666 | to a compiled library. All other symbols change the ABI, which means all |
3696 | to a compiled library. All other symbols change the ABI, which means all |
3667 | users of libev and the libev code itself must be compiled with compatible |
3697 | users of libev and the libev code itself must be compiled with compatible |
3668 | settings. |
3698 | settings. |
3669 | |
3699 | |
3670 | =over 4 |
3700 | =over 4 |
|
|
3701 | |
|
|
3702 | =item EV_COMPAT3 (h) |
|
|
3703 | |
|
|
3704 | Backwards compatibility is a major concern for libev. This is why this |
|
|
3705 | release of libev comes with wrappers for the functions and symbols that |
|
|
3706 | have been renamed between libev version 3 and 4. |
|
|
3707 | |
|
|
3708 | You can disable these wrappers (to test compatibility with future |
|
|
3709 | versions) by defining C<EV_COMPAT3> to C<0> when compiling your |
|
|
3710 | sources. This has the additional advantage that you can drop the C<struct> |
|
|
3711 | from C<struct ev_loop> declarations, as libev will provide an C<ev_loop> |
|
|
3712 | typedef in that case. |
|
|
3713 | |
|
|
3714 | In some future version, the default for C<EV_COMPAT3> will become C<0>, |
|
|
3715 | and in some even more future version the compatibility code will be |
|
|
3716 | removed completely. |
3671 | |
3717 | |
3672 | =item EV_STANDALONE (h) |
3718 | =item EV_STANDALONE (h) |
3673 | |
3719 | |
3674 | Must always be C<1> if you do not use autoconf configuration, which |
3720 | Must always be C<1> if you do not use autoconf configuration, which |
3675 | keeps libev from including F<config.h>, and it also defines dummy |
3721 | keeps libev from including F<config.h>, and it also defines dummy |
… | |
… | |
3882 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
3928 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
3883 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3929 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3884 | |
3930 | |
3885 | If undefined or defined to be C<1> (and the platform supports it), then |
3931 | If undefined or defined to be C<1> (and the platform supports it), then |
3886 | the respective watcher type is supported. If defined to be C<0>, then it |
3932 | the respective watcher type is supported. If defined to be C<0>, then it |
3887 | is not. Disabling watcher types mainly saves codesize. |
3933 | is not. Disabling watcher types mainly saves code size. |
3888 | |
3934 | |
3889 | =item EV_MINIMAL |
3935 | =item EV_FEATURES |
3890 | |
3936 | |
3891 | If you need to shave off some kilobytes of code at the expense of some |
3937 | If you need to shave off some kilobytes of code at the expense of some |
3892 | speed (but with the full API), define this symbol to C<1>. Currently this |
3938 | speed (but with the full API), you can define this symbol to request |
3893 | is used to override some inlining decisions, saves roughly 30% code size |
3939 | certain subsets of functionality. The default is to enable all features |
3894 | on amd64. It also selects a much smaller 2-heap for timer management over |
3940 | that can be enabled on the platform. |
3895 | the default 4-heap. |
|
|
3896 | |
3941 | |
3897 | You can save even more by disabling watcher types you do not need |
3942 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
3898 | and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert> |
3943 | with some broad features you want) and then selectively re-enable |
3899 | (C<-DNDEBUG>) will usually reduce code size a lot. Disabling inotify, |
3944 | additional parts you want, for example if you want everything minimal, |
3900 | eventfd and signalfd will further help, and disabling backends one doesn't |
3945 | but multiple event loop support, async and child watchers and the poll |
3901 | need (e.g. poll, epoll, kqueue, ports) will help further. |
3946 | backend, use this: |
3902 | |
3947 | |
3903 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
3948 | #define EV_FEATURES 0 |
3904 | provide a bare-bones event library. See C<ev.h> for details on what parts |
|
|
3905 | of the API are still available, and do not complain if this subset changes |
|
|
3906 | over time. |
|
|
3907 | |
|
|
3908 | This example set of settings reduces the compiled size of libev from |
|
|
3909 | 23.9Kb to 7.7Kb on my GNU/Linux amd64 system (and leaves little |
|
|
3910 | in - there is also an effect on the amount of memory used). With |
|
|
3911 | an intelligent-enough linker (gcc+binutils do this when you use |
|
|
3912 | C<-Wl,--gc-sections -ffunction-sections>) further unused functions might |
|
|
3913 | be left out as well automatically - a binary starting a timer and an I/O |
|
|
3914 | watcher then might come out at only 5Kb. |
|
|
3915 | |
|
|
3916 | // tuning and API changes |
|
|
3917 | #define EV_MINIMAL 2 |
|
|
3918 | #define EV_MULTIPLICITY 0 |
3949 | #define EV_MULTIPLICITY 1 |
3919 | #define EV_MINPRI 0 |
|
|
3920 | #define EV_MAXPRI 0 |
|
|
3921 | |
|
|
3922 | // OS-specific backends |
|
|
3923 | #define EV_USE_INOTIFY 0 |
|
|
3924 | #define EV_USE_EVENTFD 0 |
|
|
3925 | #define EV_USE_SIGNALFD 0 |
|
|
3926 | #define EV_USE_REALTIME 0 |
|
|
3927 | #define EV_USE_MONOTONIC 0 |
|
|
3928 | #define EV_USE_CLOCK_SYSCALL 0 |
|
|
3929 | |
|
|
3930 | // disable all backends except select |
|
|
3931 | #define EV_USE_POLL 0 |
3950 | #define EV_USE_POLL 1 |
3932 | #define EV_USE_PORT 0 |
|
|
3933 | #define EV_USE_KQUEUE 0 |
|
|
3934 | #define EV_USE_EPOLL 0 |
|
|
3935 | |
|
|
3936 | // disable all watcher types that cna be disabled |
|
|
3937 | #define EV_STAT_ENABLE 0 |
|
|
3938 | #define EV_PERIODIC_ENABLE 0 |
|
|
3939 | #define EV_IDLE_ENABLE 0 |
|
|
3940 | #define EV_CHECK_ENABLE 0 |
|
|
3941 | #define EV_PREPARE_ENABLE 0 |
|
|
3942 | #define EV_FORK_ENABLE 0 |
|
|
3943 | #define EV_SIGNAL_ENABLE 0 |
|
|
3944 | #define EV_CHILD_ENABLE 0 |
3951 | #define EV_CHILD_ENABLE 1 |
3945 | #define EV_ASYNC_ENABLE 0 |
3952 | #define EV_ASYNC_ENABLE 1 |
3946 | #define EV_EMBED_ENABLE 0 |
3953 | |
|
|
3954 | The actual value is a bitset, it can be a combination of the following |
|
|
3955 | values: |
|
|
3956 | |
|
|
3957 | =over 4 |
|
|
3958 | |
|
|
3959 | =item C<1> - faster/larger code |
|
|
3960 | |
|
|
3961 | Use larger code to speed up some operations. |
|
|
3962 | |
|
|
3963 | Currently this is used to override some inlining decisions (enlarging the |
|
|
3964 | code size by roughly 30% on amd64). |
|
|
3965 | |
|
|
3966 | When optimising for size, use of compiler flags such as C<-Os> with |
|
|
3967 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
|
|
3968 | assertions. |
|
|
3969 | |
|
|
3970 | =item C<2> - faster/larger data structures |
|
|
3971 | |
|
|
3972 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
|
|
3973 | hash table sizes and so on. This will usually further increase code size |
|
|
3974 | and can additionally have an effect on the size of data structures at |
|
|
3975 | runtime. |
|
|
3976 | |
|
|
3977 | =item C<4> - full API configuration |
|
|
3978 | |
|
|
3979 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
|
|
3980 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
|
|
3981 | |
|
|
3982 | =item C<8> - full API |
|
|
3983 | |
|
|
3984 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
|
|
3985 | details on which parts of the API are still available without this |
|
|
3986 | feature, and do not complain if this subset changes over time. |
|
|
3987 | |
|
|
3988 | =item C<16> - enable all optional watcher types |
|
|
3989 | |
|
|
3990 | Enables all optional watcher types. If you want to selectively enable |
|
|
3991 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
3992 | embed, async, child...) you can enable them manually by defining |
|
|
3993 | C<EV_watchertype_ENABLE> to C<1> instead. |
|
|
3994 | |
|
|
3995 | =item C<32> - enable all backends |
|
|
3996 | |
|
|
3997 | This enables all backends - without this feature, you need to enable at |
|
|
3998 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
|
|
3999 | |
|
|
4000 | =item C<64> - enable OS-specific "helper" APIs |
|
|
4001 | |
|
|
4002 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
4003 | default. |
|
|
4004 | |
|
|
4005 | =back |
|
|
4006 | |
|
|
4007 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
|
|
4008 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
4009 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
4010 | watchers, timers and monotonic clock support. |
|
|
4011 | |
|
|
4012 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
4013 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
|
|
4014 | your program might be left out as well - a binary starting a timer and an |
|
|
4015 | I/O watcher then might come out at only 5Kb. |
3947 | |
4016 | |
3948 | =item EV_AVOID_STDIO |
4017 | =item EV_AVOID_STDIO |
3949 | |
4018 | |
3950 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
4019 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
3951 | functions (printf, scanf, perror etc.). This will increase the codesize |
4020 | functions (printf, scanf, perror etc.). This will increase the code size |
3952 | somewhat, but if your program doesn't otherwise depend on stdio and your |
4021 | somewhat, but if your program doesn't otherwise depend on stdio and your |
3953 | libc allows it, this avoids linking in the stdio library which is quite |
4022 | libc allows it, this avoids linking in the stdio library which is quite |
3954 | big. |
4023 | big. |
3955 | |
4024 | |
3956 | Note that error messages might become less precise when this option is |
4025 | Note that error messages might become less precise when this option is |
… | |
… | |
3960 | |
4029 | |
3961 | The highest supported signal number, +1 (or, the number of |
4030 | The highest supported signal number, +1 (or, the number of |
3962 | signals): Normally, libev tries to deduce the maximum number of signals |
4031 | signals): Normally, libev tries to deduce the maximum number of signals |
3963 | automatically, but sometimes this fails, in which case it can be |
4032 | automatically, but sometimes this fails, in which case it can be |
3964 | specified. Also, using a lower number than detected (C<32> should be |
4033 | specified. Also, using a lower number than detected (C<32> should be |
3965 | good for about any system in existance) can save some memory, as libev |
4034 | good for about any system in existence) can save some memory, as libev |
3966 | statically allocates some 12-24 bytes per signal number. |
4035 | statically allocates some 12-24 bytes per signal number. |
3967 | |
4036 | |
3968 | =item EV_PID_HASHSIZE |
4037 | =item EV_PID_HASHSIZE |
3969 | |
4038 | |
3970 | C<ev_child> watchers use a small hash table to distribute workload by |
4039 | C<ev_child> watchers use a small hash table to distribute workload by |
3971 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
4040 | pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled), |
3972 | than enough. If you need to manage thousands of children you might want to |
4041 | usually more than enough. If you need to manage thousands of children you |
3973 | increase this value (I<must> be a power of two). |
4042 | might want to increase this value (I<must> be a power of two). |
3974 | |
4043 | |
3975 | =item EV_INOTIFY_HASHSIZE |
4044 | =item EV_INOTIFY_HASHSIZE |
3976 | |
4045 | |
3977 | C<ev_stat> watchers use a small hash table to distribute workload by |
4046 | C<ev_stat> watchers use a small hash table to distribute workload by |
3978 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
4047 | inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES> |
3979 | usually more than enough. If you need to manage thousands of C<ev_stat> |
4048 | disabled), usually more than enough. If you need to manage thousands of |
3980 | watchers you might want to increase this value (I<must> be a power of |
4049 | C<ev_stat> watchers you might want to increase this value (I<must> be a |
3981 | two). |
4050 | power of two). |
3982 | |
4051 | |
3983 | =item EV_USE_4HEAP |
4052 | =item EV_USE_4HEAP |
3984 | |
4053 | |
3985 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4054 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3986 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
4055 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3987 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
4056 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3988 | faster performance with many (thousands) of watchers. |
4057 | faster performance with many (thousands) of watchers. |
3989 | |
4058 | |
3990 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4059 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3991 | (disabled). |
4060 | will be C<0>. |
3992 | |
4061 | |
3993 | =item EV_HEAP_CACHE_AT |
4062 | =item EV_HEAP_CACHE_AT |
3994 | |
4063 | |
3995 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4064 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3996 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
4065 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3997 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
4066 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3998 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
4067 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3999 | but avoids random read accesses on heap changes. This improves performance |
4068 | but avoids random read accesses on heap changes. This improves performance |
4000 | noticeably with many (hundreds) of watchers. |
4069 | noticeably with many (hundreds) of watchers. |
4001 | |
4070 | |
4002 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4071 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
4003 | (disabled). |
4072 | will be C<0>. |
4004 | |
4073 | |
4005 | =item EV_VERIFY |
4074 | =item EV_VERIFY |
4006 | |
4075 | |
4007 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4076 | Controls how much internal verification (see C<ev_verify ()>) will |
4008 | be done: If set to C<0>, no internal verification code will be compiled |
4077 | be done: If set to C<0>, no internal verification code will be compiled |
4009 | in. If set to C<1>, then verification code will be compiled in, but not |
4078 | in. If set to C<1>, then verification code will be compiled in, but not |
4010 | called. If set to C<2>, then the internal verification code will be |
4079 | called. If set to C<2>, then the internal verification code will be |
4011 | called once per loop, which can slow down libev. If set to C<3>, then the |
4080 | called once per loop, which can slow down libev. If set to C<3>, then the |
4012 | verification code will be called very frequently, which will slow down |
4081 | verification code will be called very frequently, which will slow down |
4013 | libev considerably. |
4082 | libev considerably. |
4014 | |
4083 | |
4015 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
4084 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
4016 | C<0>. |
4085 | will be C<0>. |
4017 | |
4086 | |
4018 | =item EV_COMMON |
4087 | =item EV_COMMON |
4019 | |
4088 | |
4020 | By default, all watchers have a C<void *data> member. By redefining |
4089 | By default, all watchers have a C<void *data> member. By redefining |
4021 | this macro to a something else you can include more and other types of |
4090 | this macro to something else you can include more and other types of |
4022 | members. You have to define it each time you include one of the files, |
4091 | members. You have to define it each time you include one of the files, |
4023 | though, and it must be identical each time. |
4092 | though, and it must be identical each time. |
4024 | |
4093 | |
4025 | For example, the perl EV module uses something like this: |
4094 | For example, the perl EV module uses something like this: |
4026 | |
4095 | |
… | |
… | |
4079 | file. |
4148 | file. |
4080 | |
4149 | |
4081 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4150 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4082 | that everybody includes and which overrides some configure choices: |
4151 | that everybody includes and which overrides some configure choices: |
4083 | |
4152 | |
4084 | #define EV_MINIMAL 1 |
4153 | #define EV_FEATURES 8 |
4085 | #define EV_USE_POLL 0 |
4154 | #define EV_USE_SELECT 1 |
4086 | #define EV_MULTIPLICITY 0 |
|
|
4087 | #define EV_PERIODIC_ENABLE 0 |
4155 | #define EV_PREPARE_ENABLE 1 |
|
|
4156 | #define EV_IDLE_ENABLE 1 |
4088 | #define EV_STAT_ENABLE 0 |
4157 | #define EV_SIGNAL_ENABLE 1 |
4089 | #define EV_FORK_ENABLE 0 |
4158 | #define EV_CHILD_ENABLE 1 |
|
|
4159 | #define EV_USE_STDEXCEPT 0 |
4090 | #define EV_CONFIG_H <config.h> |
4160 | #define EV_CONFIG_H <config.h> |
4091 | #define EV_MINPRI 0 |
|
|
4092 | #define EV_MAXPRI 0 |
|
|
4093 | |
4161 | |
4094 | #include "ev++.h" |
4162 | #include "ev++.h" |
4095 | |
4163 | |
4096 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4164 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4097 | |
4165 | |
… | |
… | |
4228 | userdata *u = ev_userdata (EV_A); |
4296 | userdata *u = ev_userdata (EV_A); |
4229 | pthread_mutex_lock (&u->lock); |
4297 | pthread_mutex_lock (&u->lock); |
4230 | } |
4298 | } |
4231 | |
4299 | |
4232 | The event loop thread first acquires the mutex, and then jumps straight |
4300 | The event loop thread first acquires the mutex, and then jumps straight |
4233 | into C<ev_loop>: |
4301 | into C<ev_run>: |
4234 | |
4302 | |
4235 | void * |
4303 | void * |
4236 | l_run (void *thr_arg) |
4304 | l_run (void *thr_arg) |
4237 | { |
4305 | { |
4238 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4306 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4239 | |
4307 | |
4240 | l_acquire (EV_A); |
4308 | l_acquire (EV_A); |
4241 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4309 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4242 | ev_loop (EV_A_ 0); |
4310 | ev_run (EV_A_ 0); |
4243 | l_release (EV_A); |
4311 | l_release (EV_A); |
4244 | |
4312 | |
4245 | return 0; |
4313 | return 0; |
4246 | } |
4314 | } |
4247 | |
4315 | |
… | |
… | |
4299 | |
4367 | |
4300 | =head3 COROUTINES |
4368 | =head3 COROUTINES |
4301 | |
4369 | |
4302 | Libev is very accommodating to coroutines ("cooperative threads"): |
4370 | Libev is very accommodating to coroutines ("cooperative threads"): |
4303 | libev fully supports nesting calls to its functions from different |
4371 | libev fully supports nesting calls to its functions from different |
4304 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4372 | coroutines (e.g. you can call C<ev_run> on the same loop from two |
4305 | different coroutines, and switch freely between both coroutines running |
4373 | different coroutines, and switch freely between both coroutines running |
4306 | the loop, as long as you don't confuse yourself). The only exception is |
4374 | the loop, as long as you don't confuse yourself). The only exception is |
4307 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4375 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4308 | |
4376 | |
4309 | Care has been taken to ensure that libev does not keep local state inside |
4377 | Care has been taken to ensure that libev does not keep local state inside |
4310 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4378 | C<ev_run>, and other calls do not usually allow for coroutine switches as |
4311 | they do not call any callbacks. |
4379 | they do not call any callbacks. |
4312 | |
4380 | |
4313 | =head2 COMPILER WARNINGS |
4381 | =head2 COMPILER WARNINGS |
4314 | |
4382 | |
4315 | Depending on your compiler and compiler settings, you might get no or a |
4383 | Depending on your compiler and compiler settings, you might get no or a |
… | |
… | |
4326 | maintainable. |
4394 | maintainable. |
4327 | |
4395 | |
4328 | And of course, some compiler warnings are just plain stupid, or simply |
4396 | And of course, some compiler warnings are just plain stupid, or simply |
4329 | wrong (because they don't actually warn about the condition their message |
4397 | wrong (because they don't actually warn about the condition their message |
4330 | seems to warn about). For example, certain older gcc versions had some |
4398 | seems to warn about). For example, certain older gcc versions had some |
4331 | warnings that resulted an extreme number of false positives. These have |
4399 | warnings that resulted in an extreme number of false positives. These have |
4332 | been fixed, but some people still insist on making code warn-free with |
4400 | been fixed, but some people still insist on making code warn-free with |
4333 | such buggy versions. |
4401 | such buggy versions. |
4334 | |
4402 | |
4335 | While libev is written to generate as few warnings as possible, |
4403 | While libev is written to generate as few warnings as possible, |
4336 | "warn-free" code is not a goal, and it is recommended not to build libev |
4404 | "warn-free" code is not a goal, and it is recommended not to build libev |
… | |
… | |
4372 | I suggest using suppression lists. |
4440 | I suggest using suppression lists. |
4373 | |
4441 | |
4374 | |
4442 | |
4375 | =head1 PORTABILITY NOTES |
4443 | =head1 PORTABILITY NOTES |
4376 | |
4444 | |
|
|
4445 | =head2 GNU/LINUX 32 BIT LIMITATIONS |
|
|
4446 | |
|
|
4447 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
4448 | interfaces but I<disables> them by default. |
|
|
4449 | |
|
|
4450 | That means that libev compiled in the default environment doesn't support |
|
|
4451 | files larger than 2GiB or so, which mainly affects C<ev_stat> watchers. |
|
|
4452 | |
|
|
4453 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
4454 | by enabling the large file API, which makes them incompatible with the |
|
|
4455 | standard libev compiled for their system. |
|
|
4456 | |
|
|
4457 | Likewise, libev cannot enable the large file API itself as this would |
|
|
4458 | suddenly make it incompatible to the default compile time environment, |
|
|
4459 | i.e. all programs not using special compile switches. |
|
|
4460 | |
|
|
4461 | =head2 OS/X AND DARWIN BUGS |
|
|
4462 | |
|
|
4463 | The whole thing is a bug if you ask me - basically any system interface |
|
|
4464 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
4465 | OpenGL drivers. |
|
|
4466 | |
|
|
4467 | =head3 C<kqueue> is buggy |
|
|
4468 | |
|
|
4469 | The kqueue syscall is broken in all known versions - most versions support |
|
|
4470 | only sockets, many support pipes. |
|
|
4471 | |
|
|
4472 | Libev tries to work around this by not using C<kqueue> by default on |
|
|
4473 | this rotten platform, but of course you can still ask for it when creating |
|
|
4474 | a loop. |
|
|
4475 | |
|
|
4476 | =head3 C<poll> is buggy |
|
|
4477 | |
|
|
4478 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
|
|
4479 | implementation by something calling C<kqueue> internally around the 10.5.6 |
|
|
4480 | release, so now C<kqueue> I<and> C<poll> are broken. |
|
|
4481 | |
|
|
4482 | Libev tries to work around this by not using C<poll> by default on |
|
|
4483 | this rotten platform, but of course you can still ask for it when creating |
|
|
4484 | a loop. |
|
|
4485 | |
|
|
4486 | =head3 C<select> is buggy |
|
|
4487 | |
|
|
4488 | All that's left is C<select>, and of course Apple found a way to fuck this |
|
|
4489 | one up as well: On OS/X, C<select> actively limits the number of file |
|
|
4490 | descriptors you can pass in to 1024 - your program suddenly crashes when |
|
|
4491 | you use more. |
|
|
4492 | |
|
|
4493 | There is an undocumented "workaround" for this - defining |
|
|
4494 | C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should> |
|
|
4495 | work on OS/X. |
|
|
4496 | |
|
|
4497 | =head2 SOLARIS PROBLEMS AND WORKAROUNDS |
|
|
4498 | |
|
|
4499 | =head3 C<errno> reentrancy |
|
|
4500 | |
|
|
4501 | The default compile environment on Solaris is unfortunately so |
|
|
4502 | thread-unsafe that you can't even use components/libraries compiled |
|
|
4503 | without C<-D_REENTRANT> (as long as they use C<errno>), which, of course, |
|
|
4504 | isn't defined by default. |
|
|
4505 | |
|
|
4506 | If you want to use libev in threaded environments you have to make sure |
|
|
4507 | it's compiled with C<_REENTRANT> defined. |
|
|
4508 | |
|
|
4509 | =head3 Event port backend |
|
|
4510 | |
|
|
4511 | The scalable event interface for Solaris is called "event ports". Unfortunately, |
|
|
4512 | this mechanism is very buggy. If you run into high CPU usage, your program |
|
|
4513 | freezes or you get a large number of spurious wakeups, make sure you have |
|
|
4514 | all the relevant and latest kernel patches applied. No, I don't know which |
|
|
4515 | ones, but there are multiple ones. |
|
|
4516 | |
|
|
4517 | If you can't get it to work, you can try running the program by setting |
|
|
4518 | the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and |
|
|
4519 | C<select> backends. |
|
|
4520 | |
|
|
4521 | =head2 AIX POLL BUG |
|
|
4522 | |
|
|
4523 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
|
|
4524 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
4525 | compiled in), which normally isn't a big problem as C<select> works fine |
|
|
4526 | with large bitsets, and AIX is dead anyway. |
|
|
4527 | |
4377 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4528 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
|
|
4529 | |
|
|
4530 | =head3 General issues |
4378 | |
4531 | |
4379 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4532 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4380 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4533 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4381 | model. Libev still offers limited functionality on this platform in |
4534 | model. Libev still offers limited functionality on this platform in |
4382 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4535 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4383 | descriptors. This only applies when using Win32 natively, not when using |
4536 | descriptors. This only applies when using Win32 natively, not when using |
4384 | e.g. cygwin. |
4537 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
4538 | as every compielr comes with a slightly differently broken/incompatible |
|
|
4539 | environment. |
4385 | |
4540 | |
4386 | Lifting these limitations would basically require the full |
4541 | Lifting these limitations would basically require the full |
4387 | re-implementation of the I/O system. If you are into these kinds of |
4542 | re-implementation of the I/O system. If you are into this kind of thing, |
4388 | things, then note that glib does exactly that for you in a very portable |
4543 | then note that glib does exactly that for you in a very portable way (note |
4389 | way (note also that glib is the slowest event library known to man). |
4544 | also that glib is the slowest event library known to man). |
4390 | |
4545 | |
4391 | There is no supported compilation method available on windows except |
4546 | There is no supported compilation method available on windows except |
4392 | embedding it into other applications. |
4547 | embedding it into other applications. |
4393 | |
4548 | |
4394 | Sensible signal handling is officially unsupported by Microsoft - libev |
4549 | Sensible signal handling is officially unsupported by Microsoft - libev |
… | |
… | |
4422 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4577 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4423 | |
4578 | |
4424 | #include "evwrap.h" |
4579 | #include "evwrap.h" |
4425 | #include "ev.c" |
4580 | #include "ev.c" |
4426 | |
4581 | |
4427 | =over 4 |
|
|
4428 | |
|
|
4429 | =item The winsocket select function |
4582 | =head3 The winsocket C<select> function |
4430 | |
4583 | |
4431 | The winsocket C<select> function doesn't follow POSIX in that it |
4584 | The winsocket C<select> function doesn't follow POSIX in that it |
4432 | requires socket I<handles> and not socket I<file descriptors> (it is |
4585 | requires socket I<handles> and not socket I<file descriptors> (it is |
4433 | also extremely buggy). This makes select very inefficient, and also |
4586 | also extremely buggy). This makes select very inefficient, and also |
4434 | requires a mapping from file descriptors to socket handles (the Microsoft |
4587 | requires a mapping from file descriptors to socket handles (the Microsoft |
… | |
… | |
4443 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4596 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4444 | |
4597 | |
4445 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4598 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4446 | complexity in the O(n²) range when using win32. |
4599 | complexity in the O(n²) range when using win32. |
4447 | |
4600 | |
4448 | =item Limited number of file descriptors |
4601 | =head3 Limited number of file descriptors |
4449 | |
4602 | |
4450 | Windows has numerous arbitrary (and low) limits on things. |
4603 | Windows has numerous arbitrary (and low) limits on things. |
4451 | |
4604 | |
4452 | Early versions of winsocket's select only supported waiting for a maximum |
4605 | Early versions of winsocket's select only supported waiting for a maximum |
4453 | of C<64> handles (probably owning to the fact that all windows kernels |
4606 | of C<64> handles (probably owning to the fact that all windows kernels |
… | |
… | |
4468 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4621 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4469 | (depending on windows version and/or the phase of the moon). To get more, |
4622 | (depending on windows version and/or the phase of the moon). To get more, |
4470 | you need to wrap all I/O functions and provide your own fd management, but |
4623 | you need to wrap all I/O functions and provide your own fd management, but |
4471 | the cost of calling select (O(n²)) will likely make this unworkable. |
4624 | the cost of calling select (O(n²)) will likely make this unworkable. |
4472 | |
4625 | |
4473 | =back |
|
|
4474 | |
|
|
4475 | =head2 PORTABILITY REQUIREMENTS |
4626 | =head2 PORTABILITY REQUIREMENTS |
4476 | |
4627 | |
4477 | In addition to a working ISO-C implementation and of course the |
4628 | In addition to a working ISO-C implementation and of course the |
4478 | backend-specific APIs, libev relies on a few additional extensions: |
4629 | backend-specific APIs, libev relies on a few additional extensions: |
4479 | |
4630 | |
… | |
… | |
4517 | watchers. |
4668 | watchers. |
4518 | |
4669 | |
4519 | =item C<double> must hold a time value in seconds with enough accuracy |
4670 | =item C<double> must hold a time value in seconds with enough accuracy |
4520 | |
4671 | |
4521 | The type C<double> is used to represent timestamps. It is required to |
4672 | The type C<double> is used to represent timestamps. It is required to |
4522 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4673 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
4523 | enough for at least into the year 4000. This requirement is fulfilled by |
4674 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
4675 | (the design goal for libev). This requirement is overfulfilled by |
4524 | implementations implementing IEEE 754, which is basically all existing |
4676 | implementations using IEEE 754, which is basically all existing ones. With |
4525 | ones. With IEEE 754 doubles, you get microsecond accuracy until at least |
4677 | IEEE 754 doubles, you get microsecond accuracy until at least 2200. |
4526 | 2200. |
|
|
4527 | |
4678 | |
4528 | =back |
4679 | =back |
4529 | |
4680 | |
4530 | If you know of other additional requirements drop me a note. |
4681 | If you know of other additional requirements drop me a note. |
4531 | |
4682 | |
… | |
… | |
4599 | involves iterating over all running async watchers or all signal numbers. |
4750 | involves iterating over all running async watchers or all signal numbers. |
4600 | |
4751 | |
4601 | =back |
4752 | =back |
4602 | |
4753 | |
4603 | |
4754 | |
|
|
4755 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
|
|
4756 | |
|
|
4757 | The major version 4 introduced some minor incompatible changes to the API. |
|
|
4758 | |
|
|
4759 | At the moment, the C<ev.h> header file tries to implement superficial |
|
|
4760 | compatibility, so most programs should still compile. Those might be |
|
|
4761 | removed in later versions of libev, so better update early than late. |
|
|
4762 | |
|
|
4763 | =over 4 |
|
|
4764 | |
|
|
4765 | =item function/symbol renames |
|
|
4766 | |
|
|
4767 | A number of functions and symbols have been renamed: |
|
|
4768 | |
|
|
4769 | ev_loop => ev_run |
|
|
4770 | EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
4771 | EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
4772 | |
|
|
4773 | ev_unloop => ev_break |
|
|
4774 | EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
4775 | EVUNLOOP_ONE => EVBREAK_ONE |
|
|
4776 | EVUNLOOP_ALL => EVBREAK_ALL |
|
|
4777 | |
|
|
4778 | EV_TIMEOUT => EV_TIMER |
|
|
4779 | |
|
|
4780 | ev_loop_count => ev_iteration |
|
|
4781 | ev_loop_depth => ev_depth |
|
|
4782 | ev_loop_verify => ev_verify |
|
|
4783 | |
|
|
4784 | Most functions working on C<struct ev_loop> objects don't have an |
|
|
4785 | C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and |
|
|
4786 | associated constants have been renamed to not collide with the C<struct |
|
|
4787 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
|
|
4788 | as all other watcher types. Note that C<ev_loop_fork> is still called |
|
|
4789 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
|
|
4790 | typedef. |
|
|
4791 | |
|
|
4792 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
4793 | |
|
|
4794 | The backward compatibility mechanism can be controlled by |
|
|
4795 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
4796 | section. |
|
|
4797 | |
|
|
4798 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
4799 | |
|
|
4800 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
4801 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
4802 | and work, but the library code will of course be larger. |
|
|
4803 | |
|
|
4804 | =back |
|
|
4805 | |
|
|
4806 | |
4604 | =head1 GLOSSARY |
4807 | =head1 GLOSSARY |
4605 | |
4808 | |
4606 | =over 4 |
4809 | =over 4 |
4607 | |
4810 | |
4608 | =item active |
4811 | =item active |
… | |
… | |
4629 | A change of state of some external event, such as data now being available |
4832 | A change of state of some external event, such as data now being available |
4630 | for reading on a file descriptor, time having passed or simply not having |
4833 | for reading on a file descriptor, time having passed or simply not having |
4631 | any other events happening anymore. |
4834 | any other events happening anymore. |
4632 | |
4835 | |
4633 | In libev, events are represented as single bits (such as C<EV_READ> or |
4836 | In libev, events are represented as single bits (such as C<EV_READ> or |
4634 | C<EV_TIMEOUT>). |
4837 | C<EV_TIMER>). |
4635 | |
4838 | |
4636 | =item event library |
4839 | =item event library |
4637 | |
4840 | |
4638 | A software package implementing an event model and loop. |
4841 | A software package implementing an event model and loop. |
4639 | |
4842 | |