… | |
… | |
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 |
… | |
… | |
604 | 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 |
605 | earlier call to C<ev_loop_new>. |
607 | earlier call to C<ev_loop_new>. |
606 | |
608 | |
607 | =item ev_default_fork () |
609 | =item ev_default_fork () |
608 | |
610 | |
609 | 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 |
610 | 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 |
611 | 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 |
612 | 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 |
613 | 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 |
614 | 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. |
615 | |
622 | |
616 | 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 |
617 | 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 |
618 | 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). |
619 | |
629 | |
620 | 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 |
621 | 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 |
622 | quite nicely into a call to C<pthread_atfork>: |
632 | quite nicely into a call to C<pthread_atfork>: |
623 | |
633 | |
… | |
… | |
625 | |
635 | |
626 | =item ev_loop_fork (loop) |
636 | =item ev_loop_fork (loop) |
627 | |
637 | |
628 | 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 |
629 | 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 |
630 | 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 |
631 | entirely your own problem. |
641 | them is entirely your own problem. |
632 | |
642 | |
633 | =item int ev_is_default_loop (loop) |
643 | =item int ev_is_default_loop (loop) |
634 | |
644 | |
635 | 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 |
636 | otherwise. |
646 | otherwise. |
637 | |
647 | |
638 | =item unsigned int ev_loop_count (loop) |
648 | =item unsigned int ev_iteration (loop) |
639 | |
649 | |
640 | 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 |
641 | 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> |
642 | happily wraps around with enough iterations. |
652 | and happily wraps around with enough iterations. |
643 | |
653 | |
644 | 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 |
645 | "ticks" the number of loop iterations), as it roughly corresponds with |
655 | "ticks" the number of loop iterations), as it roughly corresponds with |
646 | 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. |
647 | |
658 | |
648 | =item unsigned int ev_loop_depth (loop) |
659 | =item unsigned int ev_depth (loop) |
649 | |
660 | |
650 | 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 |
651 | 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. |
652 | |
663 | |
653 | 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 |
654 | 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), |
655 | in which case it is higher. |
666 | in which case it is higher. |
656 | |
667 | |
657 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
668 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread |
658 | 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. |
659 | |
671 | |
660 | =item unsigned int ev_backend (loop) |
672 | =item unsigned int ev_backend (loop) |
661 | |
673 | |
662 | 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 |
663 | use. |
675 | use. |
… | |
… | |
672 | |
684 | |
673 | =item ev_now_update (loop) |
685 | =item ev_now_update (loop) |
674 | |
686 | |
675 | Establishes the current time by querying the kernel, updating the time |
687 | Establishes the current time by querying the kernel, updating the time |
676 | 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 |
677 | is usually done automatically within C<ev_loop ()>. |
689 | is usually done automatically within C<ev_run ()>. |
678 | |
690 | |
679 | 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 |
680 | 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 |
681 | the current time is a good idea. |
693 | the current time is a good idea. |
682 | |
694 | |
… | |
… | |
684 | |
696 | |
685 | =item ev_suspend (loop) |
697 | =item ev_suspend (loop) |
686 | |
698 | |
687 | =item ev_resume (loop) |
699 | =item ev_resume (loop) |
688 | |
700 | |
689 | 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 |
690 | 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. |
691 | |
703 | |
692 | 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 |
693 | 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 |
694 | 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 |
695 | 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> |
… | |
… | |
697 | C<ev_resume> directly afterwards to resume timer processing. |
709 | C<ev_resume> directly afterwards to resume timer processing. |
698 | |
710 | |
699 | 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 |
700 | 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 |
701 | 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 |
702 | occured while suspended). |
714 | occurred while suspended). |
703 | |
715 | |
704 | 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 |
705 | 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> |
706 | without a previous call to C<ev_suspend>. |
718 | without a previous call to C<ev_suspend>. |
707 | |
719 | |
708 | 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 |
709 | event loop time (see C<ev_now_update>). |
721 | event loop time (see C<ev_now_update>). |
710 | |
722 | |
711 | =item ev_loop (loop, int flags) |
723 | =item ev_run (loop, int flags) |
712 | |
724 | |
713 | 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 |
714 | 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 |
715 | 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>. |
716 | |
730 | |
717 | 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 |
718 | 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. |
719 | |
734 | |
720 | 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 |
721 | 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 |
722 | finished (especially in interactive programs), but having a program |
737 | finished (especially in interactive programs), but having a program |
723 | 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 |
724 | 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 |
725 | beauty. |
740 | beauty. |
726 | |
741 | |
727 | 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 |
728 | 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 |
729 | 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 |
730 | 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. |
731 | |
747 | |
732 | 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 |
733 | necessary) and will handle those and any already outstanding ones. It |
749 | necessary) and will handle those and any already outstanding ones. It |
734 | 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 |
735 | 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 |
736 | user-registered callback will be called), and will return after one |
752 | user-registered callback will be called), and will return after one |
737 | iteration of the loop. |
753 | iteration of the loop. |
738 | |
754 | |
739 | 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 |
740 | 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 |
741 | 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 |
742 | usually a better approach for this kind of thing. |
758 | usually a better approach for this kind of thing. |
743 | |
759 | |
744 | Here are the gory details of what C<ev_loop> does: |
760 | Here are the gory details of what C<ev_run> does: |
745 | |
761 | |
|
|
762 | - Increment loop depth. |
|
|
763 | - Reset the ev_break status. |
746 | - Before the first iteration, call any pending watchers. |
764 | - Before the first iteration, call any pending watchers. |
|
|
765 | LOOP: |
747 | * If EVFLAG_FORKCHECK was used, check for a fork. |
766 | - If EVFLAG_FORKCHECK was used, check for a fork. |
748 | - 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. |
749 | - Queue and call all prepare watchers. |
768 | - Queue and call all prepare watchers. |
|
|
769 | - If ev_break was called, goto FINISH. |
750 | - If we have been forked, detach and recreate the kernel state |
770 | - If we have been forked, detach and recreate the kernel state |
751 | as to not disturb the other process. |
771 | as to not disturb the other process. |
752 | - Update the kernel state with all outstanding changes. |
772 | - Update the kernel state with all outstanding changes. |
753 | - Update the "event loop time" (ev_now ()). |
773 | - Update the "event loop time" (ev_now ()). |
754 | - Calculate for how long to sleep or block, if at all |
774 | - Calculate for how long to sleep or block, if at all |
755 | (active idle watchers, EVLOOP_NONBLOCK or not having |
775 | (active idle watchers, EVRUN_NOWAIT or not having |
756 | any active watchers at all will result in not sleeping). |
776 | any active watchers at all will result in not sleeping). |
757 | - 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. |
758 | - Block the process, waiting for any events. |
779 | - Block the process, waiting for any events. |
759 | - Queue all outstanding I/O (fd) events. |
780 | - Queue all outstanding I/O (fd) events. |
760 | - 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. |
761 | - Queue all expired timers. |
782 | - Queue all expired timers. |
762 | - Queue all expired periodics. |
783 | - Queue all expired periodics. |
763 | - Unless any events are pending now, queue all idle watchers. |
784 | - Queue all idle watchers with priority higher than that of pending events. |
764 | - Queue all check watchers. |
785 | - Queue all check watchers. |
765 | - 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). |
766 | 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 |
767 | be handled here by queueing them when their watcher gets executed. |
788 | be handled here by queueing them when their watcher gets executed. |
768 | - 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 |
769 | were used, or there are no active watchers, return, otherwise |
790 | were used, or there are no active watchers, goto FINISH, otherwise |
770 | 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. |
771 | |
796 | |
772 | 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 |
773 | anymore. |
798 | anymore. |
774 | |
799 | |
775 | ... queue jobs here, make sure they register event watchers as long |
800 | ... queue jobs here, make sure they register event watchers as long |
776 | ... 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..) |
777 | ev_loop (my_loop, 0); |
802 | ev_run (my_loop, 0); |
778 | ... jobs done or somebody called unloop. yeah! |
803 | ... jobs done or somebody called unloop. yeah! |
779 | |
804 | |
780 | =item ev_unloop (loop, how) |
805 | =item ev_break (loop, how) |
781 | |
806 | |
782 | 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 |
783 | 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 |
784 | 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 |
785 | 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. |
786 | |
811 | |
787 | 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. |
788 | |
813 | |
789 | 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## |
790 | |
815 | |
791 | =item ev_ref (loop) |
816 | =item ev_ref (loop) |
792 | |
817 | |
793 | =item ev_unref (loop) |
818 | =item ev_unref (loop) |
794 | |
819 | |
795 | 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 |
796 | 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 |
797 | 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. |
798 | |
823 | |
799 | 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 |
800 | unregister, but that nevertheless should not keep C<ev_loop> from |
825 | unregister, but that nevertheless should not keep C<ev_run> from |
801 | 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> |
802 | before stopping it. |
827 | before stopping it. |
803 | |
828 | |
804 | 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 |
805 | 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 |
806 | 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 |
807 | 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 |
808 | 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 |
809 | 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 |
810 | before, respectively. Note also that libev might stop watchers itself |
835 | before, respectively. Note also that libev might stop watchers itself |
811 | (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> |
812 | in the callback). |
837 | in the callback). |
813 | |
838 | |
814 | 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> |
815 | running when nothing else is active. |
840 | running when nothing else is active. |
816 | |
841 | |
817 | ev_signal exitsig; |
842 | ev_signal exitsig; |
818 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
843 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
819 | ev_signal_start (loop, &exitsig); |
844 | ev_signal_start (loop, &exitsig); |
… | |
… | |
864 | 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>, |
865 | 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 |
866 | 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 |
867 | parallelity, then this setting will limit your transaction rate (if you |
892 | parallelity, then this setting will limit your transaction rate (if you |
868 | 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, |
869 | then you can't do more than 100 transations per second). |
894 | then you can't do more than 100 transactions per second). |
870 | |
895 | |
871 | Setting the I<timeout collect interval> can improve the opportunity for |
896 | Setting the I<timeout collect interval> can improve the opportunity for |
872 | saving power, as the program will "bundle" timer callback invocations that |
897 | saving power, as the program will "bundle" timer callback invocations that |
873 | 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 |
874 | 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 |
… | |
… | |
882 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
907 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
883 | |
908 | |
884 | =item ev_invoke_pending (loop) |
909 | =item ev_invoke_pending (loop) |
885 | |
910 | |
886 | This call will simply invoke all pending watchers while resetting their |
911 | This call will simply invoke all pending watchers while resetting their |
887 | pending state. Normally, C<ev_loop> does this automatically when required, |
912 | pending state. Normally, C<ev_run> does this automatically when required, |
888 | but when overriding the invoke callback this call comes handy. |
913 | but when overriding the invoke callback this call comes handy. |
889 | |
914 | |
890 | =item int ev_pending_count (loop) |
915 | =item int ev_pending_count (loop) |
891 | |
916 | |
892 | Returns the number of pending watchers - zero indicates that no watchers |
917 | Returns the number of pending watchers - zero indicates that no watchers |
893 | are pending. |
918 | are pending. |
894 | |
919 | |
895 | =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)) |
896 | |
921 | |
897 | This overrides the invoke pending functionality of the loop: Instead of |
922 | This overrides the invoke pending functionality of the loop: Instead of |
898 | 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 |
899 | 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 |
900 | invoke the actual watchers inside another context (another thread etc.). |
925 | invoke the actual watchers inside another context (another thread etc.). |
901 | |
926 | |
902 | 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 |
903 | callback. |
928 | callback. |
… | |
… | |
906 | |
931 | |
907 | 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 |
908 | 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 |
909 | each call to a libev function. |
934 | each call to a libev function. |
910 | |
935 | |
911 | 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 |
912 | 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 |
913 | 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 |
914 | and I<acquire> callbacks on the loop. |
939 | I<release> and I<acquire> callbacks on the loop. |
915 | |
940 | |
916 | 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 |
917 | suspended waiting for new events, and C<acquire> is called just |
942 | suspended waiting for new events, and C<acquire> is called just |
918 | afterwards. |
943 | afterwards. |
919 | |
944 | |
… | |
… | |
922 | |
947 | |
923 | While event loop modifications are allowed between invocations of |
948 | While event loop modifications are allowed between invocations of |
924 | 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 |
925 | 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 |
926 | 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 |
927 | 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 |
928 | to take note of any changes you made. |
953 | to take note of any changes you made. |
929 | |
954 | |
930 | 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 |
931 | invocations of C<release> and C<acquire>. |
956 | invocations of C<release> and C<acquire>. |
932 | |
957 | |
933 | 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 |
934 | document. |
959 | document. |
935 | |
960 | |
… | |
… | |
944 | 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, |
945 | 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 |
946 | 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 |
947 | any other purpose as well. |
972 | any other purpose as well. |
948 | |
973 | |
949 | =item ev_loop_verify (loop) |
974 | =item ev_verify (loop) |
950 | |
975 | |
951 | 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 |
952 | 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 |
953 | through all internal structures and checks them for validity. If anything |
978 | through all internal structures and checks them for validity. If anything |
954 | 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 |
… | |
… | |
972 | 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: |
973 | |
998 | |
974 | 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) |
975 | { |
1000 | { |
976 | ev_io_stop (w); |
1001 | ev_io_stop (w); |
977 | ev_unloop (loop, EVUNLOOP_ALL); |
1002 | ev_break (loop, EVBREAK_ALL); |
978 | } |
1003 | } |
979 | |
1004 | |
980 | struct ev_loop *loop = ev_default_loop (0); |
1005 | struct ev_loop *loop = ev_default_loop (0); |
981 | |
1006 | |
982 | ev_io stdin_watcher; |
1007 | ev_io stdin_watcher; |
983 | |
1008 | |
984 | ev_init (&stdin_watcher, my_cb); |
1009 | ev_init (&stdin_watcher, my_cb); |
985 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1010 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
986 | ev_io_start (loop, &stdin_watcher); |
1011 | ev_io_start (loop, &stdin_watcher); |
987 | |
1012 | |
988 | ev_loop (loop, 0); |
1013 | ev_run (loop, 0); |
989 | |
1014 | |
990 | 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 |
991 | 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 |
992 | stack). |
1017 | stack). |
993 | |
1018 | |
… | |
… | |
1057 | |
1082 | |
1058 | =item C<EV_PREPARE> |
1083 | =item C<EV_PREPARE> |
1059 | |
1084 | |
1060 | =item C<EV_CHECK> |
1085 | =item C<EV_CHECK> |
1061 | |
1086 | |
1062 | 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 |
1063 | 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 |
1064 | 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 |
1065 | 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 |
1066 | 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 |
1067 | (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 |
1068 | C<ev_loop> from blocking). |
1093 | C<ev_run> from blocking). |
1069 | |
1094 | |
1070 | =item C<EV_EMBED> |
1095 | =item C<EV_EMBED> |
1071 | |
1096 | |
1072 | 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. |
1073 | |
1098 | |
… | |
… | |
1372 | |
1397 | |
1373 | For example, to emulate how many other event libraries handle priorities, |
1398 | For example, to emulate how many other event libraries handle priorities, |
1374 | 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 |
1375 | 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 |
1376 | 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 |
1377 | 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 |
1378 | 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 |
1379 | workable. |
1404 | workable. |
1380 | |
1405 | |
1381 | Usually, however, the lock-out model implemented that way will perform |
1406 | Usually, however, the lock-out model implemented that way will perform |
1382 | 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, |
… | |
… | |
1396 | { |
1421 | { |
1397 | // stop the I/O watcher, we received the event, but |
1422 | // stop the I/O watcher, we received the event, but |
1398 | // are not yet ready to handle it. |
1423 | // are not yet ready to handle it. |
1399 | ev_io_stop (EV_A_ w); |
1424 | ev_io_stop (EV_A_ w); |
1400 | |
1425 | |
1401 | // start the idle watcher to ahndle the actual event. |
1426 | // start the idle watcher to handle the actual event. |
1402 | // it will not be executed as long as other watchers |
1427 | // it will not be executed as long as other watchers |
1403 | // with the default priority are receiving events. |
1428 | // with the default priority are receiving events. |
1404 | ev_idle_start (EV_A_ &idle); |
1429 | ev_idle_start (EV_A_ &idle); |
1405 | } |
1430 | } |
1406 | |
1431 | |
… | |
… | |
1460 | |
1485 | |
1461 | 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 |
1462 | 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 |
1463 | 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 |
1464 | descriptors for which non-blocking operation makes no sense (such as |
1489 | descriptors for which non-blocking operation makes no sense (such as |
1465 | files) - libev doesn't guarentee any specific behaviour in that case. |
1490 | files) - libev doesn't guarantee any specific behaviour in that case. |
1466 | |
1491 | |
1467 | 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 |
1468 | receive "spurious" readiness notifications, that is your callback might |
1493 | receive "spurious" readiness notifications, that is your callback might |
1469 | 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 |
1470 | 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 |
… | |
… | |
1538 | somewhere, as that would have given you a big clue). |
1563 | somewhere, as that would have given you a big clue). |
1539 | |
1564 | |
1540 | =head3 The special problem of accept()ing when you can't |
1565 | =head3 The special problem of accept()ing when you can't |
1541 | |
1566 | |
1542 | Many implementations of the POSIX C<accept> function (for example, |
1567 | Many implementations of the POSIX C<accept> function (for example, |
1543 | 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 |
1544 | connection from the pending queue in all error cases. |
1569 | connection from the pending queue in all error cases. |
1545 | |
1570 | |
1546 | For example, larger servers often run out of file descriptors (because |
1571 | For example, larger servers often run out of file descriptors (because |
1547 | 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 |
1548 | rejecting the connection, leading to libev signalling readiness on |
1573 | rejecting the connection, leading to libev signalling readiness on |
… | |
… | |
1614 | ... |
1639 | ... |
1615 | struct ev_loop *loop = ev_default_init (0); |
1640 | struct ev_loop *loop = ev_default_init (0); |
1616 | ev_io stdin_readable; |
1641 | ev_io stdin_readable; |
1617 | 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); |
1618 | ev_io_start (loop, &stdin_readable); |
1643 | ev_io_start (loop, &stdin_readable); |
1619 | ev_loop (loop, 0); |
1644 | ev_run (loop, 0); |
1620 | |
1645 | |
1621 | |
1646 | |
1622 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1647 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1623 | |
1648 | |
1624 | 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 |
… | |
… | |
1633 | 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 |
1634 | 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 |
1635 | 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 |
1636 | 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 |
1637 | 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 |
1638 | no longer true when a callback calls C<ev_loop> recursively). |
1663 | no longer true when a callback calls C<ev_run> recursively). |
1639 | |
1664 | |
1640 | =head3 Be smart about timeouts |
1665 | =head3 Be smart about timeouts |
1641 | |
1666 | |
1642 | 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 |
1643 | 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, |
… | |
… | |
1729 | ev_tstamp timeout = last_activity + 60.; |
1754 | ev_tstamp timeout = last_activity + 60.; |
1730 | |
1755 | |
1731 | // 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 |
1732 | if (timeout < now) |
1757 | if (timeout < now) |
1733 | { |
1758 | { |
1734 | // timeout occured, take action |
1759 | // timeout occurred, take action |
1735 | } |
1760 | } |
1736 | else |
1761 | else |
1737 | { |
1762 | { |
1738 | // callback was invoked, but there was some activity, re-arm |
1763 | // callback was invoked, but there was some activity, re-arm |
1739 | // the watcher to fire in last_activity + 60, which is |
1764 | // the watcher to fire in last_activity + 60, which is |
… | |
… | |
1766 | callback (loop, timer, EV_TIMER); |
1791 | callback (loop, timer, EV_TIMER); |
1767 | |
1792 | |
1768 | 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 |
1769 | C<last_activity>, no libev calls at all: |
1794 | C<last_activity>, no libev calls at all: |
1770 | |
1795 | |
1771 | last_actiivty = ev_now (loop); |
1796 | last_activity = ev_now (loop); |
1772 | |
1797 | |
1773 | 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 |
1774 | time-out is unlikely to be triggered, much more efficient. |
1799 | time-out is unlikely to be triggered, much more efficient. |
1775 | |
1800 | |
1776 | 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 |
… | |
… | |
1814 | |
1839 | |
1815 | =head3 The special problem of time updates |
1840 | =head3 The special problem of time updates |
1816 | |
1841 | |
1817 | 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 |
1818 | 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 |
1819 | 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 |
1820 | 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 |
1821 | lots of events in one iteration. |
1846 | lots of events in one iteration. |
1822 | |
1847 | |
1823 | The relative timeouts are calculated relative to the C<ev_now ()> |
1848 | The relative timeouts are calculated relative to the C<ev_now ()> |
1824 | 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 |
… | |
… | |
1941 | } |
1966 | } |
1942 | |
1967 | |
1943 | ev_timer mytimer; |
1968 | ev_timer mytimer; |
1944 | 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 */ |
1945 | ev_timer_again (&mytimer); /* start timer */ |
1970 | ev_timer_again (&mytimer); /* start timer */ |
1946 | ev_loop (loop, 0); |
1971 | ev_run (loop, 0); |
1947 | |
1972 | |
1948 | // 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": |
1949 | // reset the timeout to start ticking again at 10 seconds |
1974 | // reset the timeout to start ticking again at 10 seconds |
1950 | ev_timer_again (&mytimer); |
1975 | ev_timer_again (&mytimer); |
1951 | |
1976 | |
… | |
… | |
1977 | |
2002 | |
1978 | 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 |
1979 | 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 |
1980 | 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 |
1981 | 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 |
1982 | (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). |
1983 | |
2008 | |
1984 | =head3 Watcher-Specific Functions and Data Members |
2009 | =head3 Watcher-Specific Functions and Data Members |
1985 | |
2010 | |
1986 | =over 4 |
2011 | =over 4 |
1987 | |
2012 | |
… | |
… | |
2115 | Example: Call a callback every hour, or, more precisely, whenever the |
2140 | Example: Call a callback every hour, or, more precisely, whenever the |
2116 | system time is divisible by 3600. The callback invocation times have |
2141 | system time is divisible by 3600. The callback invocation times have |
2117 | potentially a lot of jitter, but good long-term stability. |
2142 | potentially a lot of jitter, but good long-term stability. |
2118 | |
2143 | |
2119 | static void |
2144 | static void |
2120 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2145 | clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
2121 | { |
2146 | { |
2122 | ... 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) |
2123 | } |
2148 | } |
2124 | |
2149 | |
2125 | ev_periodic hourly_tick; |
2150 | ev_periodic hourly_tick; |
… | |
… | |
2225 | Example: Try to exit cleanly on SIGINT. |
2250 | Example: Try to exit cleanly on SIGINT. |
2226 | |
2251 | |
2227 | static void |
2252 | static void |
2228 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2253 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2229 | { |
2254 | { |
2230 | ev_unloop (loop, EVUNLOOP_ALL); |
2255 | ev_break (loop, EVBREAK_ALL); |
2231 | } |
2256 | } |
2232 | |
2257 | |
2233 | ev_signal signal_watcher; |
2258 | ev_signal signal_watcher; |
2234 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2259 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2235 | ev_signal_start (loop, &signal_watcher); |
2260 | ev_signal_start (loop, &signal_watcher); |
… | |
… | |
2621 | |
2646 | |
2622 | 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: |
2623 | prepare watchers get invoked before the process blocks and check watchers |
2648 | prepare watchers get invoked before the process blocks and check watchers |
2624 | afterwards. |
2649 | afterwards. |
2625 | |
2650 | |
2626 | 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 |
2627 | 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> |
2628 | watchers. Other loops than the current one are fine, however. The |
2653 | watchers. Other loops than the current one are fine, however. The |
2629 | 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 |
2630 | 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, |
2631 | 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 |
… | |
… | |
2799 | |
2824 | |
2800 | if (timeout >= 0) |
2825 | if (timeout >= 0) |
2801 | // create/start timer |
2826 | // create/start timer |
2802 | |
2827 | |
2803 | // poll |
2828 | // poll |
2804 | ev_loop (EV_A_ 0); |
2829 | ev_run (EV_A_ 0); |
2805 | |
2830 | |
2806 | // stop timer again |
2831 | // stop timer again |
2807 | if (timeout >= 0) |
2832 | if (timeout >= 0) |
2808 | ev_timer_stop (EV_A_ &to); |
2833 | ev_timer_stop (EV_A_ &to); |
2809 | |
2834 | |
… | |
… | |
2887 | 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). |
2888 | |
2913 | |
2889 | =item ev_embed_sweep (loop, ev_embed *) |
2914 | =item ev_embed_sweep (loop, ev_embed *) |
2890 | |
2915 | |
2891 | 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 |
2892 | 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 |
2893 | appropriate way for embedded loops. |
2918 | appropriate way for embedded loops. |
2894 | |
2919 | |
2895 | =item struct ev_loop *other [read-only] |
2920 | =item struct ev_loop *other [read-only] |
2896 | |
2921 | |
2897 | The embedded event loop. |
2922 | The embedded event loop. |
… | |
… | |
2957 | 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 |
2958 | handlers will be invoked, too, of course. |
2983 | handlers will be invoked, too, of course. |
2959 | |
2984 | |
2960 | =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? |
2961 | |
2986 | |
2962 | 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 |
2963 | 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 |
2964 | sequence should be handled by libev without any problems. |
2989 | sequence should be handled by libev without any problems. |
2965 | |
2990 | |
2966 | This changes when the application actually wants to do event handling |
2991 | This changes when the application actually wants to do event handling |
2967 | 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 |
… | |
… | |
3001 | believe me. |
3026 | believe me. |
3002 | |
3027 | |
3003 | =back |
3028 | =back |
3004 | |
3029 | |
3005 | |
3030 | |
3006 | =head2 C<ev_async> - how to wake up another event loop |
3031 | =head2 C<ev_async> - how to wake up an event loop |
3007 | |
3032 | |
3008 | 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 |
3009 | asynchronous sources such as signal handlers (as opposed to multiple event |
3034 | asynchronous sources such as signal handlers (as opposed to multiple event |
3010 | loops - those are of course safe to use in different threads). |
3035 | loops - those are of course safe to use in different threads). |
3011 | |
3036 | |
3012 | 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, |
3013 | 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> |
3014 | 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 |
3015 | 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. |
3016 | safe. |
|
|
3017 | |
3041 | |
3018 | 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, |
3019 | too, are asynchronous in nature, and signals, too, will be compressed |
3043 | too, are asynchronous in nature, and signals, too, will be compressed |
3020 | (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 |
3021 | C<ev_async_sent> calls). |
3045 | C<ev_async_sent> calls). |
… | |
… | |
3333 | myclass obj; |
3357 | myclass obj; |
3334 | ev::io iow; |
3358 | ev::io iow; |
3335 | iow.set <myclass, &myclass::io_cb> (&obj); |
3359 | iow.set <myclass, &myclass::io_cb> (&obj); |
3336 | |
3360 | |
3337 | =item w->set (object *) |
3361 | =item w->set (object *) |
3338 | |
|
|
3339 | This is an B<experimental> feature that might go away in a future version. |
|
|
3340 | |
3362 | |
3341 | 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 |
3342 | 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 |
3343 | functor objects without having to manually specify the C<operator ()> all |
3365 | functor objects without having to manually specify the C<operator ()> all |
3344 | 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 |
… | |
… | |
3384 | 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 |
3385 | do this when the watcher is inactive (and not pending either). |
3407 | do this when the watcher is inactive (and not pending either). |
3386 | |
3408 | |
3387 | =item w->set ([arguments]) |
3409 | =item w->set ([arguments]) |
3388 | |
3410 | |
3389 | 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 |
3390 | 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 |
3391 | automatically stopped and restarted when reconfiguring it with this |
3413 | C counterpart, an active watcher gets automatically stopped and restarted |
3392 | method. |
3414 | when reconfiguring it with this method. |
3393 | |
3415 | |
3394 | =item w->start () |
3416 | =item w->start () |
3395 | |
3417 | |
3396 | 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 |
3397 | constructor already stores the event loop. |
3419 | constructor already stores the event loop. |
3398 | |
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 | |
3399 | =item w->stop () |
3427 | =item w->stop () |
3400 | |
3428 | |
3401 | 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. |
3402 | |
3430 | |
3403 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
3431 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
… | |
… | |
3415 | |
3443 | |
3416 | =back |
3444 | =back |
3417 | |
3445 | |
3418 | =back |
3446 | =back |
3419 | |
3447 | |
3420 | 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 |
3421 | the constructor. |
3449 | watchers in the constructor. |
3422 | |
3450 | |
3423 | class myclass |
3451 | class myclass |
3424 | { |
3452 | { |
3425 | 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); |
3426 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3455 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3427 | |
3456 | |
3428 | myclass (int fd) |
3457 | myclass (int fd) |
3429 | { |
3458 | { |
3430 | io .set <myclass, &myclass::io_cb > (this); |
3459 | io .set <myclass, &myclass::io_cb > (this); |
|
|
3460 | io2 .set <myclass, &myclass::io2_cb > (this); |
3431 | idle.set <myclass, &myclass::idle_cb> (this); |
3461 | idle.set <myclass, &myclass::idle_cb> (this); |
3432 | |
3462 | |
3433 | 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 |
3434 | } |
3467 | } |
3435 | }; |
3468 | }; |
3436 | |
3469 | |
3437 | |
3470 | |
3438 | =head1 OTHER LANGUAGE BINDINGS |
3471 | =head1 OTHER LANGUAGE BINDINGS |
… | |
… | |
3512 | 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, |
3513 | C<EV_A_> is used when other arguments are following. Example: |
3546 | C<EV_A_> is used when other arguments are following. Example: |
3514 | |
3547 | |
3515 | ev_unref (EV_A); |
3548 | ev_unref (EV_A); |
3516 | ev_timer_add (EV_A_ watcher); |
3549 | ev_timer_add (EV_A_ watcher); |
3517 | ev_loop (EV_A_ 0); |
3550 | ev_run (EV_A_ 0); |
3518 | |
3551 | |
3519 | 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, |
3520 | which is often provided by the following macro. |
3553 | which is often provided by the following macro. |
3521 | |
3554 | |
3522 | =item C<EV_P>, C<EV_P_> |
3555 | =item C<EV_P>, C<EV_P_> |
… | |
… | |
3562 | } |
3595 | } |
3563 | |
3596 | |
3564 | ev_check check; |
3597 | ev_check check; |
3565 | ev_check_init (&check, check_cb); |
3598 | ev_check_init (&check, check_cb); |
3566 | ev_check_start (EV_DEFAULT_ &check); |
3599 | ev_check_start (EV_DEFAULT_ &check); |
3567 | ev_loop (EV_DEFAULT_ 0); |
3600 | ev_run (EV_DEFAULT_ 0); |
3568 | |
3601 | |
3569 | =head1 EMBEDDING |
3602 | =head1 EMBEDDING |
3570 | |
3603 | |
3571 | Libev can (and often is) directly embedded into host |
3604 | Libev can (and often is) directly embedded into host |
3572 | applications. Examples of applications that embed it include the Deliantra |
3605 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3657 | 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 |
3658 | the absence of autoconf is documented for every option. |
3691 | the absence of autoconf is documented for every option. |
3659 | |
3692 | |
3660 | 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 |
3661 | 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 |
3662 | to redefine them before including F<ev.h> without breakign compatibility |
3695 | to redefine them before including F<ev.h> without breaking compatibility |
3663 | 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 |
3664 | 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 |
3665 | settings. |
3698 | settings. |
3666 | |
3699 | |
3667 | =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. |
3668 | |
3717 | |
3669 | =item EV_STANDALONE (h) |
3718 | =item EV_STANDALONE (h) |
3670 | |
3719 | |
3671 | 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 |
3672 | 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 |
… | |
… | |
3879 | 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, |
3880 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3929 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3881 | |
3930 | |
3882 | 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 |
3883 | 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 |
3884 | is not. Disabling watcher types mainly saves codesize. |
3933 | is not. Disabling watcher types mainly saves code size. |
3885 | |
3934 | |
3886 | =item EV_FEATURES |
3935 | =item EV_FEATURES |
3887 | |
3936 | |
3888 | 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 |
3889 | speed (but with the full API), you can define this symbol to request |
3938 | speed (but with the full API), you can define this symbol to request |
… | |
… | |
3909 | |
3958 | |
3910 | =item C<1> - faster/larger code |
3959 | =item C<1> - faster/larger code |
3911 | |
3960 | |
3912 | Use larger code to speed up some operations. |
3961 | Use larger code to speed up some operations. |
3913 | |
3962 | |
3914 | Currently this is used to override some inlining decisions (enlarging the roughly |
3963 | Currently this is used to override some inlining decisions (enlarging the |
3915 | 30% code size on amd64. |
3964 | code size by roughly 30% on amd64). |
3916 | |
3965 | |
3917 | When optimising for size, use of compiler flags such as C<-Os> with |
3966 | When optimising for size, use of compiler flags such as C<-Os> with |
3918 | gcc recommended, as well as C<-DNDEBUG>, as libev contains a number of |
3967 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
3919 | assertions. |
3968 | assertions. |
3920 | |
3969 | |
3921 | =item C<2> - faster/larger data structures |
3970 | =item C<2> - faster/larger data structures |
3922 | |
3971 | |
3923 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
3972 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
3924 | hash table sizes and so on. This will usually further increase codesize |
3973 | hash table sizes and so on. This will usually further increase code size |
3925 | and can additionally have an effect on the size of data structures at |
3974 | and can additionally have an effect on the size of data structures at |
3926 | runtime. |
3975 | runtime. |
3927 | |
3976 | |
3928 | =item C<4> - full API configuration |
3977 | =item C<4> - full API configuration |
3929 | |
3978 | |
… | |
… | |
3966 | I/O watcher then might come out at only 5Kb. |
4015 | I/O watcher then might come out at only 5Kb. |
3967 | |
4016 | |
3968 | =item EV_AVOID_STDIO |
4017 | =item EV_AVOID_STDIO |
3969 | |
4018 | |
3970 | 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 |
3971 | functions (printf, scanf, perror etc.). This will increase the codesize |
4020 | functions (printf, scanf, perror etc.). This will increase the code size |
3972 | 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 |
3973 | 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 |
3974 | big. |
4023 | big. |
3975 | |
4024 | |
3976 | 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 |
… | |
… | |
3980 | |
4029 | |
3981 | The highest supported signal number, +1 (or, the number of |
4030 | The highest supported signal number, +1 (or, the number of |
3982 | signals): Normally, libev tries to deduce the maximum number of signals |
4031 | signals): Normally, libev tries to deduce the maximum number of signals |
3983 | automatically, but sometimes this fails, in which case it can be |
4032 | automatically, but sometimes this fails, in which case it can be |
3984 | 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 |
3985 | 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 |
3986 | statically allocates some 12-24 bytes per signal number. |
4035 | statically allocates some 12-24 bytes per signal number. |
3987 | |
4036 | |
3988 | =item EV_PID_HASHSIZE |
4037 | =item EV_PID_HASHSIZE |
3989 | |
4038 | |
3990 | 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 |
… | |
… | |
4022 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
4071 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
4023 | will be C<0>. |
4072 | will be C<0>. |
4024 | |
4073 | |
4025 | =item EV_VERIFY |
4074 | =item EV_VERIFY |
4026 | |
4075 | |
4027 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4076 | Controls how much internal verification (see C<ev_verify ()>) will |
4028 | 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 |
4029 | 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 |
4030 | 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 |
4031 | 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 |
4032 | verification code will be called very frequently, which will slow down |
4081 | verification code will be called very frequently, which will slow down |
… | |
… | |
4036 | will be C<0>. |
4085 | will be C<0>. |
4037 | |
4086 | |
4038 | =item EV_COMMON |
4087 | =item EV_COMMON |
4039 | |
4088 | |
4040 | 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 |
4041 | 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 |
4042 | 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, |
4043 | though, and it must be identical each time. |
4092 | though, and it must be identical each time. |
4044 | |
4093 | |
4045 | For example, the perl EV module uses something like this: |
4094 | For example, the perl EV module uses something like this: |
4046 | |
4095 | |
… | |
… | |
4247 | userdata *u = ev_userdata (EV_A); |
4296 | userdata *u = ev_userdata (EV_A); |
4248 | pthread_mutex_lock (&u->lock); |
4297 | pthread_mutex_lock (&u->lock); |
4249 | } |
4298 | } |
4250 | |
4299 | |
4251 | 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 |
4252 | into C<ev_loop>: |
4301 | into C<ev_run>: |
4253 | |
4302 | |
4254 | void * |
4303 | void * |
4255 | l_run (void *thr_arg) |
4304 | l_run (void *thr_arg) |
4256 | { |
4305 | { |
4257 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4306 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4258 | |
4307 | |
4259 | l_acquire (EV_A); |
4308 | l_acquire (EV_A); |
4260 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4309 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4261 | ev_loop (EV_A_ 0); |
4310 | ev_run (EV_A_ 0); |
4262 | l_release (EV_A); |
4311 | l_release (EV_A); |
4263 | |
4312 | |
4264 | return 0; |
4313 | return 0; |
4265 | } |
4314 | } |
4266 | |
4315 | |
… | |
… | |
4318 | |
4367 | |
4319 | =head3 COROUTINES |
4368 | =head3 COROUTINES |
4320 | |
4369 | |
4321 | Libev is very accommodating to coroutines ("cooperative threads"): |
4370 | Libev is very accommodating to coroutines ("cooperative threads"): |
4322 | libev fully supports nesting calls to its functions from different |
4371 | libev fully supports nesting calls to its functions from different |
4323 | 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 |
4324 | different coroutines, and switch freely between both coroutines running |
4373 | different coroutines, and switch freely between both coroutines running |
4325 | 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 |
4326 | 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. |
4327 | |
4376 | |
4328 | 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 |
4329 | 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 |
4330 | they do not call any callbacks. |
4379 | they do not call any callbacks. |
4331 | |
4380 | |
4332 | =head2 COMPILER WARNINGS |
4381 | =head2 COMPILER WARNINGS |
4333 | |
4382 | |
4334 | 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 |
… | |
… | |
4345 | maintainable. |
4394 | maintainable. |
4346 | |
4395 | |
4347 | 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 |
4348 | 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 |
4349 | 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 |
4350 | warnings that resulted an extreme number of false positives. These have |
4399 | warnings that resulted in an extreme number of false positives. These have |
4351 | 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 |
4352 | such buggy versions. |
4401 | such buggy versions. |
4353 | |
4402 | |
4354 | While libev is written to generate as few warnings as possible, |
4403 | While libev is written to generate as few warnings as possible, |
4355 | "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 |
… | |
… | |
4391 | I suggest using suppression lists. |
4440 | I suggest using suppression lists. |
4392 | |
4441 | |
4393 | |
4442 | |
4394 | =head1 PORTABILITY NOTES |
4443 | =head1 PORTABILITY NOTES |
4395 | |
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 | |
4396 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4528 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
|
|
4529 | |
|
|
4530 | =head3 General issues |
4397 | |
4531 | |
4398 | 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 |
4399 | 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 |
4400 | model. Libev still offers limited functionality on this platform in |
4534 | model. Libev still offers limited functionality on this platform in |
4401 | 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 |
4402 | descriptors. This only applies when using Win32 natively, not when using |
4536 | descriptors. This only applies when using Win32 natively, not when using |
4403 | 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. |
4404 | |
4540 | |
4405 | Lifting these limitations would basically require the full |
4541 | Lifting these limitations would basically require the full |
4406 | 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, |
4407 | 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 |
4408 | 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). |
4409 | |
4545 | |
4410 | There is no supported compilation method available on windows except |
4546 | There is no supported compilation method available on windows except |
4411 | embedding it into other applications. |
4547 | embedding it into other applications. |
4412 | |
4548 | |
4413 | Sensible signal handling is officially unsupported by Microsoft - libev |
4549 | Sensible signal handling is officially unsupported by Microsoft - libev |
… | |
… | |
4441 | 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!): |
4442 | |
4578 | |
4443 | #include "evwrap.h" |
4579 | #include "evwrap.h" |
4444 | #include "ev.c" |
4580 | #include "ev.c" |
4445 | |
4581 | |
4446 | =over 4 |
|
|
4447 | |
|
|
4448 | =item The winsocket select function |
4582 | =head3 The winsocket C<select> function |
4449 | |
4583 | |
4450 | 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 |
4451 | 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 |
4452 | also extremely buggy). This makes select very inefficient, and also |
4586 | also extremely buggy). This makes select very inefficient, and also |
4453 | requires a mapping from file descriptors to socket handles (the Microsoft |
4587 | requires a mapping from file descriptors to socket handles (the Microsoft |
… | |
… | |
4462 | #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 */ |
4463 | |
4597 | |
4464 | 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 |
4465 | complexity in the O(n²) range when using win32. |
4599 | complexity in the O(n²) range when using win32. |
4466 | |
4600 | |
4467 | =item Limited number of file descriptors |
4601 | =head3 Limited number of file descriptors |
4468 | |
4602 | |
4469 | Windows has numerous arbitrary (and low) limits on things. |
4603 | Windows has numerous arbitrary (and low) limits on things. |
4470 | |
4604 | |
4471 | 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 |
4472 | 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 |
… | |
… | |
4487 | 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 |
4488 | (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, |
4489 | 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 |
4490 | 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. |
4491 | |
4625 | |
4492 | =back |
|
|
4493 | |
|
|
4494 | =head2 PORTABILITY REQUIREMENTS |
4626 | =head2 PORTABILITY REQUIREMENTS |
4495 | |
4627 | |
4496 | 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 |
4497 | backend-specific APIs, libev relies on a few additional extensions: |
4629 | backend-specific APIs, libev relies on a few additional extensions: |
4498 | |
4630 | |
… | |
… | |
4536 | watchers. |
4668 | watchers. |
4537 | |
4669 | |
4538 | =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 |
4539 | |
4671 | |
4540 | 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 |
4541 | 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 |
4542 | 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 |
4543 | implementations implementing IEEE 754, which is basically all existing |
4676 | implementations using IEEE 754, which is basically all existing ones. With |
4544 | ones. With IEEE 754 doubles, you get microsecond accuracy until at least |
4677 | IEEE 754 doubles, you get microsecond accuracy until at least 2200. |
4545 | 2200. |
|
|
4546 | |
4678 | |
4547 | =back |
4679 | =back |
4548 | |
4680 | |
4549 | If you know of other additional requirements drop me a note. |
4681 | If you know of other additional requirements drop me a note. |
4550 | |
4682 | |
… | |
… | |
4618 | involves iterating over all running async watchers or all signal numbers. |
4750 | involves iterating over all running async watchers or all signal numbers. |
4619 | |
4751 | |
4620 | =back |
4752 | =back |
4621 | |
4753 | |
4622 | |
4754 | |
4623 | =head1 PORTING FROM 3.X TO 4.X |
4755 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
4624 | |
4756 | |
4625 | The major version 4 introduced some minor incompatible changes to the API. |
4757 | The major version 4 introduced some minor incompatible changes to the API. |
4626 | |
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 | |
4627 | =over 4 |
4763 | =over 4 |
4628 | |
4764 | |
4629 | =item C<EV_TIMEOUT> replaced by C<EV_TIMER> in C<revents> |
4765 | =item function/symbol renames |
4630 | |
4766 | |
4631 | This is a simple rename - all other watcher types use their name |
4767 | A number of functions and symbols have been renamed: |
4632 | as revents flag, and now C<ev_timer> does, too. |
|
|
4633 | |
4768 | |
4634 | Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions |
4769 | ev_loop => ev_run |
4635 | and continue to be present for the forseeable future, so this is mostly a |
4770 | EVLOOP_NONBLOCK => EVRUN_NOWAIT |
4636 | documentation change. |
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 |
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4789 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
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4790 | typedef. |
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4791 | |
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4792 | =item C<EV_COMPAT3> backwards compatibility mechanism |
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4793 | |
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4794 | The backward compatibility mechanism can be controlled by |
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4795 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
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4796 | section. |
4637 | |
4797 | |
4638 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
4798 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
4639 | |
4799 | |
4640 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
4800 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
4641 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
4801 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |