… | |
… | |
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 |
… | |
… | |
118 | Libev is very configurable. In this manual the default (and most common) |
118 | Libev is very configurable. In this manual the default (and most common) |
119 | configuration will be described, which supports multiple event loops. For |
119 | configuration will be described, which supports multiple event loops. For |
120 | more info about various configuration options please have a look at |
120 | more info about various configuration options please have a look at |
121 | B<EMBED> section in this manual. If libev was configured without support |
121 | B<EMBED> section in this manual. If libev was configured without support |
122 | for multiple event loops, then all functions taking an initial argument of |
122 | for multiple event loops, then all functions taking an initial argument of |
123 | name C<loop> (which is always of type C<ev_loop *>) will not have |
123 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
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. |
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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 | |
… | |
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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. |
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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 |
… | |
… | |
370 | When this flag is specified, then libev will not attempt to use the |
370 | When this flag is specified, then libev will not attempt to use the |
371 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
371 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
372 | testing, this flag can be useful to conserve inotify file descriptors, as |
372 | testing, this flag can be useful to conserve inotify file descriptors, as |
373 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
373 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
374 | |
374 | |
375 | =item C<EVFLAG_NOSIGNALFD> |
375 | =item C<EVFLAG_SIGNALFD> |
376 | |
376 | |
377 | When this flag is specified, then libev will not attempt to use the |
377 | When this flag is specified, then libev will attempt to use the |
378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This is |
378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API |
379 | probably only useful to work around any bugs in libev. Consequently, this |
379 | delivers signals synchronously, which makes it both faster and might make |
380 | flag might go away once the signalfd functionality is considered stable, |
380 | it possible to get the queued signal data. It can also simplify signal |
381 | so it's useful mostly in environment variables and not in program code. |
381 | handling with threads, as long as you properly block signals in your |
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382 | threads that are not interested in handling them. |
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383 | |
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384 | Signalfd will not be used by default as this changes your signal mask, and |
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385 | there are a lot of shoddy libraries and programs (glib's threadpool for |
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386 | example) that can't properly initialise their signal masks. |
382 | |
387 | |
383 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
388 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
384 | |
389 | |
385 | This is your standard select(2) backend. Not I<completely> standard, as |
390 | This is your standard select(2) backend. Not I<completely> standard, as |
386 | libev tries to roll its own fd_set with no limits on the number of fds, |
391 | libev tries to roll its own fd_set with no limits on the number of fds, |
… | |
… | |
410 | |
415 | |
411 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
416 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
412 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
417 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
413 | |
418 | |
414 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
419 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
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420 | |
|
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421 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
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422 | kernels). |
415 | |
423 | |
416 | For few fds, this backend is a bit little slower than poll and select, |
424 | For few fds, this backend is a bit little slower than poll and select, |
417 | but it scales phenomenally better. While poll and select usually scale |
425 | but it scales phenomenally better. While poll and select usually scale |
418 | like O(total_fds) where n is the total number of fds (or the highest fd), |
426 | like O(total_fds) where n is the total number of fds (or the highest fd), |
419 | epoll scales either O(1) or O(active_fds). |
427 | epoll scales either O(1) or O(active_fds). |
… | |
… | |
559 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
567 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
560 | |
568 | |
561 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
569 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
562 | |
570 | |
563 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
571 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
564 | always distinct from the default loop. Unlike the default loop, it cannot |
572 | always distinct from the default loop. |
565 | handle signal and child watchers, and attempts to do so will be greeted by |
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566 | undefined behaviour (or a failed assertion if assertions are enabled). |
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567 | |
573 | |
568 | Note that this function I<is> thread-safe, and the recommended way to use |
574 | Note that this function I<is> thread-safe, and one common way to use |
569 | libev with threads is indeed to create one loop per thread, and using the |
575 | libev with threads is indeed to create one loop per thread, and using the |
570 | default loop in the "main" or "initial" thread. |
576 | default loop in the "main" or "initial" thread. |
571 | |
577 | |
572 | Example: Try to create a event loop that uses epoll and nothing else. |
578 | Example: Try to create a event loop that uses epoll and nothing else. |
573 | |
579 | |
… | |
… | |
575 | if (!epoller) |
581 | if (!epoller) |
576 | fatal ("no epoll found here, maybe it hides under your chair"); |
582 | fatal ("no epoll found here, maybe it hides under your chair"); |
577 | |
583 | |
578 | =item ev_default_destroy () |
584 | =item ev_default_destroy () |
579 | |
585 | |
580 | Destroys the default loop again (frees all memory and kernel state |
586 | Destroys the default loop (frees all memory and kernel state etc.). None |
581 | etc.). None of the active event watchers will be stopped in the normal |
587 | of the active event watchers will be stopped in the normal sense, so |
582 | sense, so e.g. C<ev_is_active> might still return true. It is your |
588 | e.g. C<ev_is_active> might still return true. It is your responsibility to |
583 | responsibility to either stop all watchers cleanly yourself I<before> |
589 | either stop all watchers cleanly yourself I<before> calling this function, |
584 | calling this function, or cope with the fact afterwards (which is usually |
590 | or cope with the fact afterwards (which is usually the easiest thing, you |
585 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
591 | can just ignore the watchers and/or C<free ()> them for example). |
586 | for example). |
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587 | |
592 | |
588 | Note that certain global state, such as signal state (and installed signal |
593 | Note that certain global state, such as signal state (and installed signal |
589 | handlers), will not be freed by this function, and related watchers (such |
594 | handlers), will not be freed by this function, and related watchers (such |
590 | as signal and child watchers) would need to be stopped manually. |
595 | as signal and child watchers) would need to be stopped manually. |
591 | |
596 | |
592 | In general it is not advisable to call this function except in the |
597 | In general it is not advisable to call this function except in the |
593 | rare occasion where you really need to free e.g. the signal handling |
598 | rare occasion where you really need to free e.g. the signal handling |
594 | pipe fds. If you need dynamically allocated loops it is better to use |
599 | pipe fds. If you need dynamically allocated loops it is better to use |
595 | C<ev_loop_new> and C<ev_loop_destroy>). |
600 | C<ev_loop_new> and C<ev_loop_destroy>. |
596 | |
601 | |
597 | =item ev_loop_destroy (loop) |
602 | =item ev_loop_destroy (loop) |
598 | |
603 | |
599 | Like C<ev_default_destroy>, but destroys an event loop created by an |
604 | Like C<ev_default_destroy>, but destroys an event loop created by an |
600 | earlier call to C<ev_loop_new>. |
605 | earlier call to C<ev_loop_new>. |
… | |
… | |
606 | name, you can call it anytime, but it makes most sense after forking, in |
611 | name, you can call it anytime, but it makes most sense after forking, in |
607 | the child process (or both child and parent, but that again makes little |
612 | the child process (or both child and parent, but that again makes little |
608 | sense). You I<must> call it in the child before using any of the libev |
613 | sense). You I<must> call it in the child before using any of the libev |
609 | functions, and it will only take effect at the next C<ev_loop> iteration. |
614 | functions, and it will only take effect at the next C<ev_loop> iteration. |
610 | |
615 | |
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616 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
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617 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
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618 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
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619 | during fork. |
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620 | |
611 | On the other hand, you only need to call this function in the child |
621 | On the other hand, you only need to call this function in the child |
612 | process if and only if you want to use the event library in the child. If |
622 | process if and only if you want to use the event loop in the child. If you |
613 | you just fork+exec, you don't have to call it at all. |
623 | just fork+exec or create a new loop in the child, you don't have to call |
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624 | it at all. |
614 | |
625 | |
615 | The function itself is quite fast and it's usually not a problem to call |
626 | The function itself is quite fast and it's usually not a problem to call |
616 | it just in case after a fork. To make this easy, the function will fit in |
627 | it just in case after a fork. To make this easy, the function will fit in |
617 | quite nicely into a call to C<pthread_atfork>: |
628 | quite nicely into a call to C<pthread_atfork>: |
618 | |
629 | |
… | |
… | |
620 | |
631 | |
621 | =item ev_loop_fork (loop) |
632 | =item ev_loop_fork (loop) |
622 | |
633 | |
623 | Like C<ev_default_fork>, but acts on an event loop created by |
634 | Like C<ev_default_fork>, but acts on an event loop created by |
624 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
635 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
625 | after fork that you want to re-use in the child, and how you do this is |
636 | after fork that you want to re-use in the child, and how you keep track of |
626 | entirely your own problem. |
637 | them is entirely your own problem. |
627 | |
638 | |
628 | =item int ev_is_default_loop (loop) |
639 | =item int ev_is_default_loop (loop) |
629 | |
640 | |
630 | Returns true when the given loop is, in fact, the default loop, and false |
641 | Returns true when the given loop is, in fact, the default loop, and false |
631 | otherwise. |
642 | otherwise. |
632 | |
643 | |
633 | =item unsigned int ev_loop_count (loop) |
644 | =item unsigned int ev_iteration (loop) |
634 | |
645 | |
635 | Returns the count of loop iterations for the loop, which is identical to |
646 | Returns the current iteration count for the loop, which is identical to |
636 | the number of times libev did poll for new events. It starts at C<0> and |
647 | the number of times libev did poll for new events. It starts at C<0> and |
637 | happily wraps around with enough iterations. |
648 | happily wraps around with enough iterations. |
638 | |
649 | |
639 | This value can sometimes be useful as a generation counter of sorts (it |
650 | This value can sometimes be useful as a generation counter of sorts (it |
640 | "ticks" the number of loop iterations), as it roughly corresponds with |
651 | "ticks" the number of loop iterations), as it roughly corresponds with |
641 | C<ev_prepare> and C<ev_check> calls. |
652 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
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|
653 | prepare and check phases. |
642 | |
654 | |
643 | =item unsigned int ev_loop_depth (loop) |
655 | =item unsigned int ev_depth (loop) |
644 | |
656 | |
645 | Returns the number of times C<ev_loop> was entered minus the number of |
657 | Returns the number of times C<ev_loop> was entered minus the number of |
646 | times C<ev_loop> was exited, in other words, the recursion depth. |
658 | times C<ev_loop> was exited, in other words, the recursion depth. |
647 | |
659 | |
648 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
660 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
649 | C<1>, unless C<ev_loop> was invoked recursively (or from another thread), |
661 | C<1>, unless C<ev_loop> was invoked recursively (or from another thread), |
650 | in which case it is higher. |
662 | in which case it is higher. |
651 | |
663 | |
652 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
664 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
653 | etc.), doesn't count as exit. |
665 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
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666 | ungentleman behaviour unless it's really convenient. |
654 | |
667 | |
655 | =item unsigned int ev_backend (loop) |
668 | =item unsigned int ev_backend (loop) |
656 | |
669 | |
657 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
670 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
658 | use. |
671 | use. |
… | |
… | |
692 | C<ev_resume> directly afterwards to resume timer processing. |
705 | C<ev_resume> directly afterwards to resume timer processing. |
693 | |
706 | |
694 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
707 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
695 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
708 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
696 | will be rescheduled (that is, they will lose any events that would have |
709 | will be rescheduled (that is, they will lose any events that would have |
697 | occured while suspended). |
710 | occurred while suspended). |
698 | |
711 | |
699 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
712 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
700 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
713 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
701 | without a previous call to C<ev_suspend>. |
714 | without a previous call to C<ev_suspend>. |
702 | |
715 | |
… | |
… | |
704 | event loop time (see C<ev_now_update>). |
717 | event loop time (see C<ev_now_update>). |
705 | |
718 | |
706 | =item ev_loop (loop, int flags) |
719 | =item ev_loop (loop, int flags) |
707 | |
720 | |
708 | Finally, this is it, the event handler. This function usually is called |
721 | Finally, this is it, the event handler. This function usually is called |
709 | after you initialised all your watchers and you want to start handling |
722 | after you have initialised all your watchers and you want to start |
710 | events. |
723 | handling events. |
711 | |
724 | |
712 | If the flags argument is specified as C<0>, it will not return until |
725 | If the flags argument is specified as C<0>, it will not return until |
713 | either no event watchers are active anymore or C<ev_unloop> was called. |
726 | either no event watchers are active anymore or C<ev_unloop> was called. |
714 | |
727 | |
715 | Please note that an explicit C<ev_unloop> is usually better than |
728 | Please note that an explicit C<ev_unloop> is usually better than |
… | |
… | |
779 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
792 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
780 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
793 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
781 | |
794 | |
782 | This "unloop state" will be cleared when entering C<ev_loop> again. |
795 | This "unloop state" will be cleared when entering C<ev_loop> again. |
783 | |
796 | |
784 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
797 | It is safe to call C<ev_unloop> from outside any C<ev_loop> calls. |
785 | |
798 | |
786 | =item ev_ref (loop) |
799 | =item ev_ref (loop) |
787 | |
800 | |
788 | =item ev_unref (loop) |
801 | =item ev_unref (loop) |
789 | |
802 | |
790 | Ref/unref can be used to add or remove a reference count on the event |
803 | Ref/unref can be used to add or remove a reference count on the event |
791 | loop: Every watcher keeps one reference, and as long as the reference |
804 | loop: Every watcher keeps one reference, and as long as the reference |
792 | count is nonzero, C<ev_loop> will not return on its own. |
805 | count is nonzero, C<ev_loop> will not return on its own. |
793 | |
806 | |
794 | If you have a watcher you never unregister that should not keep C<ev_loop> |
807 | This is useful when you have a watcher that you never intend to |
795 | from returning, call ev_unref() after starting, and ev_ref() before |
808 | unregister, but that nevertheless should not keep C<ev_loop> from |
|
|
809 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
796 | stopping it. |
810 | before stopping it. |
797 | |
811 | |
798 | As an example, libev itself uses this for its internal signal pipe: It |
812 | As an example, libev itself uses this for its internal signal pipe: It |
799 | is not visible to the libev user and should not keep C<ev_loop> from |
813 | is not visible to the libev user and should not keep C<ev_loop> from |
800 | exiting if no event watchers registered by it are active. It is also an |
814 | exiting if no event watchers registered by it are active. It is also an |
801 | excellent way to do this for generic recurring timers or from within |
815 | excellent way to do this for generic recurring timers or from within |
… | |
… | |
858 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
872 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
859 | as this approaches the timing granularity of most systems. Note that if |
873 | as this approaches the timing granularity of most systems. Note that if |
860 | you do transactions with the outside world and you can't increase the |
874 | you do transactions with the outside world and you can't increase the |
861 | parallelity, then this setting will limit your transaction rate (if you |
875 | parallelity, then this setting will limit your transaction rate (if you |
862 | need to poll once per transaction and the I/O collect interval is 0.01, |
876 | need to poll once per transaction and the I/O collect interval is 0.01, |
863 | then you can't do more than 100 transations per second). |
877 | then you can't do more than 100 transactions per second). |
864 | |
878 | |
865 | Setting the I<timeout collect interval> can improve the opportunity for |
879 | Setting the I<timeout collect interval> can improve the opportunity for |
866 | saving power, as the program will "bundle" timer callback invocations that |
880 | saving power, as the program will "bundle" timer callback invocations that |
867 | are "near" in time together, by delaying some, thus reducing the number of |
881 | are "near" in time together, by delaying some, thus reducing the number of |
868 | times the process sleeps and wakes up again. Another useful technique to |
882 | times the process sleeps and wakes up again. Another useful technique to |
… | |
… | |
916 | |
930 | |
917 | While event loop modifications are allowed between invocations of |
931 | While event loop modifications are allowed between invocations of |
918 | C<release> and C<acquire> (that's their only purpose after all), no |
932 | C<release> and C<acquire> (that's their only purpose after all), no |
919 | modifications done will affect the event loop, i.e. adding watchers will |
933 | modifications done will affect the event loop, i.e. adding watchers will |
920 | have no effect on the set of file descriptors being watched, or the time |
934 | have no effect on the set of file descriptors being watched, or the time |
921 | waited. USe an C<ev_async> watcher to wake up C<ev_loop> when you want it |
935 | waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it |
922 | to take note of any changes you made. |
936 | to take note of any changes you made. |
923 | |
937 | |
924 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
938 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
925 | invocations of C<release> and C<acquire>. |
939 | invocations of C<release> and C<acquire>. |
926 | |
940 | |
… | |
… | |
1023 | =item C<EV_WRITE> |
1037 | =item C<EV_WRITE> |
1024 | |
1038 | |
1025 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1039 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1026 | writable. |
1040 | writable. |
1027 | |
1041 | |
1028 | =item C<EV_TIMEOUT> |
1042 | =item C<EV_TIMER> |
1029 | |
1043 | |
1030 | The C<ev_timer> watcher has timed out. |
1044 | The C<ev_timer> watcher has timed out. |
1031 | |
1045 | |
1032 | =item C<EV_PERIODIC> |
1046 | =item C<EV_PERIODIC> |
1033 | |
1047 | |
… | |
… | |
1123 | |
1137 | |
1124 | ev_io w; |
1138 | ev_io w; |
1125 | ev_init (&w, my_cb); |
1139 | ev_init (&w, my_cb); |
1126 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1140 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1127 | |
1141 | |
1128 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
1142 | =item C<ev_TYPE_set> (ev_TYPE *watcher, [args]) |
1129 | |
1143 | |
1130 | This macro initialises the type-specific parts of a watcher. You need to |
1144 | This macro initialises the type-specific parts of a watcher. You need to |
1131 | call C<ev_init> at least once before you call this macro, but you can |
1145 | call C<ev_init> at least once before you call this macro, but you can |
1132 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1146 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1133 | macro on a watcher that is active (it can be pending, however, which is a |
1147 | macro on a watcher that is active (it can be pending, however, which is a |
… | |
… | |
1146 | |
1160 | |
1147 | Example: Initialise and set an C<ev_io> watcher in one step. |
1161 | Example: Initialise and set an C<ev_io> watcher in one step. |
1148 | |
1162 | |
1149 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1163 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1150 | |
1164 | |
1151 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
1165 | =item C<ev_TYPE_start> (loop, ev_TYPE *watcher) |
1152 | |
1166 | |
1153 | Starts (activates) the given watcher. Only active watchers will receive |
1167 | Starts (activates) the given watcher. Only active watchers will receive |
1154 | events. If the watcher is already active nothing will happen. |
1168 | events. If the watcher is already active nothing will happen. |
1155 | |
1169 | |
1156 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1170 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1157 | whole section. |
1171 | whole section. |
1158 | |
1172 | |
1159 | ev_io_start (EV_DEFAULT_UC, &w); |
1173 | ev_io_start (EV_DEFAULT_UC, &w); |
1160 | |
1174 | |
1161 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1175 | =item C<ev_TYPE_stop> (loop, ev_TYPE *watcher) |
1162 | |
1176 | |
1163 | Stops the given watcher if active, and clears the pending status (whether |
1177 | Stops the given watcher if active, and clears the pending status (whether |
1164 | the watcher was active or not). |
1178 | the watcher was active or not). |
1165 | |
1179 | |
1166 | It is possible that stopped watchers are pending - for example, |
1180 | It is possible that stopped watchers are pending - for example, |
… | |
… | |
1191 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1205 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1192 | |
1206 | |
1193 | Change the callback. You can change the callback at virtually any time |
1207 | Change the callback. You can change the callback at virtually any time |
1194 | (modulo threads). |
1208 | (modulo threads). |
1195 | |
1209 | |
1196 | =item ev_set_priority (ev_TYPE *watcher, priority) |
1210 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1197 | |
1211 | |
1198 | =item int ev_priority (ev_TYPE *watcher) |
1212 | =item int ev_priority (ev_TYPE *watcher) |
1199 | |
1213 | |
1200 | Set and query the priority of the watcher. The priority is a small |
1214 | Set and query the priority of the watcher. The priority is a small |
1201 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1215 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
… | |
… | |
1232 | returns its C<revents> bitset (as if its callback was invoked). If the |
1246 | returns its C<revents> bitset (as if its callback was invoked). If the |
1233 | watcher isn't pending it does nothing and returns C<0>. |
1247 | watcher isn't pending it does nothing and returns C<0>. |
1234 | |
1248 | |
1235 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1249 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1236 | callback to be invoked, which can be accomplished with this function. |
1250 | callback to be invoked, which can be accomplished with this function. |
|
|
1251 | |
|
|
1252 | =item ev_feed_event (loop, ev_TYPE *watcher, int revents) |
|
|
1253 | |
|
|
1254 | Feeds the given event set into the event loop, as if the specified event |
|
|
1255 | had happened for the specified watcher (which must be a pointer to an |
|
|
1256 | initialised but not necessarily started event watcher). Obviously you must |
|
|
1257 | not free the watcher as long as it has pending events. |
|
|
1258 | |
|
|
1259 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1260 | C<ev_clear_pending> will clear the pending event, even if the watcher was |
|
|
1261 | not started in the first place. |
|
|
1262 | |
|
|
1263 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
|
|
1264 | functions that do not need a watcher. |
1237 | |
1265 | |
1238 | =back |
1266 | =back |
1239 | |
1267 | |
1240 | |
1268 | |
1241 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1269 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
1352 | |
1380 | |
1353 | For example, to emulate how many other event libraries handle priorities, |
1381 | For example, to emulate how many other event libraries handle priorities, |
1354 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1382 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1355 | the normal watcher callback, you just start the idle watcher. The real |
1383 | the normal watcher callback, you just start the idle watcher. The real |
1356 | processing is done in the idle watcher callback. This causes libev to |
1384 | processing is done in the idle watcher callback. This causes libev to |
1357 | continously poll and process kernel event data for the watcher, but when |
1385 | continuously poll and process kernel event data for the watcher, but when |
1358 | the lock-out case is known to be rare (which in turn is rare :), this is |
1386 | the lock-out case is known to be rare (which in turn is rare :), this is |
1359 | workable. |
1387 | workable. |
1360 | |
1388 | |
1361 | Usually, however, the lock-out model implemented that way will perform |
1389 | Usually, however, the lock-out model implemented that way will perform |
1362 | miserably under the type of load it was designed to handle. In that case, |
1390 | miserably under the type of load it was designed to handle. In that case, |
… | |
… | |
1376 | { |
1404 | { |
1377 | // stop the I/O watcher, we received the event, but |
1405 | // stop the I/O watcher, we received the event, but |
1378 | // are not yet ready to handle it. |
1406 | // are not yet ready to handle it. |
1379 | ev_io_stop (EV_A_ w); |
1407 | ev_io_stop (EV_A_ w); |
1380 | |
1408 | |
1381 | // start the idle watcher to ahndle the actual event. |
1409 | // start the idle watcher to handle the actual event. |
1382 | // it will not be executed as long as other watchers |
1410 | // it will not be executed as long as other watchers |
1383 | // with the default priority are receiving events. |
1411 | // with the default priority are receiving events. |
1384 | ev_idle_start (EV_A_ &idle); |
1412 | ev_idle_start (EV_A_ &idle); |
1385 | } |
1413 | } |
1386 | |
1414 | |
… | |
… | |
1440 | |
1468 | |
1441 | If you cannot use non-blocking mode, then force the use of a |
1469 | If you cannot use non-blocking mode, then force the use of a |
1442 | known-to-be-good backend (at the time of this writing, this includes only |
1470 | known-to-be-good backend (at the time of this writing, this includes only |
1443 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1471 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1444 | descriptors for which non-blocking operation makes no sense (such as |
1472 | descriptors for which non-blocking operation makes no sense (such as |
1445 | files) - libev doesn't guarentee any specific behaviour in that case. |
1473 | files) - libev doesn't guarantee any specific behaviour in that case. |
1446 | |
1474 | |
1447 | Another thing you have to watch out for is that it is quite easy to |
1475 | Another thing you have to watch out for is that it is quite easy to |
1448 | receive "spurious" readiness notifications, that is your callback might |
1476 | receive "spurious" readiness notifications, that is your callback might |
1449 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1477 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1450 | because there is no data. Not only are some backends known to create a |
1478 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1515 | |
1543 | |
1516 | So when you encounter spurious, unexplained daemon exits, make sure you |
1544 | So when you encounter spurious, unexplained daemon exits, make sure you |
1517 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1545 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1518 | somewhere, as that would have given you a big clue). |
1546 | somewhere, as that would have given you a big clue). |
1519 | |
1547 | |
|
|
1548 | =head3 The special problem of accept()ing when you can't |
|
|
1549 | |
|
|
1550 | Many implementations of the POSIX C<accept> function (for example, |
|
|
1551 | found in post-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1552 | connection from the pending queue in all error cases. |
|
|
1553 | |
|
|
1554 | For example, larger servers often run out of file descriptors (because |
|
|
1555 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
|
|
1556 | rejecting the connection, leading to libev signalling readiness on |
|
|
1557 | the next iteration again (the connection still exists after all), and |
|
|
1558 | typically causing the program to loop at 100% CPU usage. |
|
|
1559 | |
|
|
1560 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1561 | operating systems, there is usually little the app can do to remedy the |
|
|
1562 | situation, and no known thread-safe method of removing the connection to |
|
|
1563 | cope with overload is known (to me). |
|
|
1564 | |
|
|
1565 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1566 | - when the program encounters an overload, it will just loop until the |
|
|
1567 | situation is over. While this is a form of busy waiting, no OS offers an |
|
|
1568 | event-based way to handle this situation, so it's the best one can do. |
|
|
1569 | |
|
|
1570 | A better way to handle the situation is to log any errors other than |
|
|
1571 | C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such |
|
|
1572 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1573 | what could be wrong ("raise the ulimit!"). For extra points one could stop |
|
|
1574 | the C<ev_io> watcher on the listening fd "for a while", which reduces CPU |
|
|
1575 | usage. |
|
|
1576 | |
|
|
1577 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1578 | descriptor for overload situations (e.g. by opening F</dev/null>), and |
|
|
1579 | when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>, |
|
|
1580 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1581 | clients under typical overload conditions. |
|
|
1582 | |
|
|
1583 | The last way to handle it is to simply log the error and C<exit>, as |
|
|
1584 | is often done with C<malloc> failures, but this results in an easy |
|
|
1585 | opportunity for a DoS attack. |
1520 | |
1586 | |
1521 | =head3 Watcher-Specific Functions |
1587 | =head3 Watcher-Specific Functions |
1522 | |
1588 | |
1523 | =over 4 |
1589 | =over 4 |
1524 | |
1590 | |
… | |
… | |
1671 | ev_tstamp timeout = last_activity + 60.; |
1737 | ev_tstamp timeout = last_activity + 60.; |
1672 | |
1738 | |
1673 | // if last_activity + 60. is older than now, we did time out |
1739 | // if last_activity + 60. is older than now, we did time out |
1674 | if (timeout < now) |
1740 | if (timeout < now) |
1675 | { |
1741 | { |
1676 | // timeout occured, take action |
1742 | // timeout occurred, take action |
1677 | } |
1743 | } |
1678 | else |
1744 | else |
1679 | { |
1745 | { |
1680 | // callback was invoked, but there was some activity, re-arm |
1746 | // callback was invoked, but there was some activity, re-arm |
1681 | // the watcher to fire in last_activity + 60, which is |
1747 | // the watcher to fire in last_activity + 60, which is |
… | |
… | |
1703 | to the current time (meaning we just have some activity :), then call the |
1769 | to the current time (meaning we just have some activity :), then call the |
1704 | callback, which will "do the right thing" and start the timer: |
1770 | callback, which will "do the right thing" and start the timer: |
1705 | |
1771 | |
1706 | ev_init (timer, callback); |
1772 | ev_init (timer, callback); |
1707 | last_activity = ev_now (loop); |
1773 | last_activity = ev_now (loop); |
1708 | callback (loop, timer, EV_TIMEOUT); |
1774 | callback (loop, timer, EV_TIMER); |
1709 | |
1775 | |
1710 | And when there is some activity, simply store the current time in |
1776 | And when there is some activity, simply store the current time in |
1711 | C<last_activity>, no libev calls at all: |
1777 | C<last_activity>, no libev calls at all: |
1712 | |
1778 | |
1713 | last_actiivty = ev_now (loop); |
1779 | last_activity = ev_now (loop); |
1714 | |
1780 | |
1715 | This technique is slightly more complex, but in most cases where the |
1781 | This technique is slightly more complex, but in most cases where the |
1716 | time-out is unlikely to be triggered, much more efficient. |
1782 | time-out is unlikely to be triggered, much more efficient. |
1717 | |
1783 | |
1718 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
1784 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
… | |
… | |
1837 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1903 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1838 | |
1904 | |
1839 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1905 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1840 | usage example. |
1906 | usage example. |
1841 | |
1907 | |
1842 | =item ev_timer_remaining (loop, ev_timer *) |
1908 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
1843 | |
1909 | |
1844 | Returns the remaining time until a timer fires. If the timer is active, |
1910 | Returns the remaining time until a timer fires. If the timer is active, |
1845 | then this time is relative to the current event loop time, otherwise it's |
1911 | then this time is relative to the current event loop time, otherwise it's |
1846 | the timeout value currently configured. |
1912 | the timeout value currently configured. |
1847 | |
1913 | |
1848 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
1914 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
1849 | C<5>. When the timer is started and one second passes, C<ev_timer_remain> |
1915 | C<5>. When the timer is started and one second passes, C<ev_timer_remaining> |
1850 | will return C<4>. When the timer expires and is restarted, it will return |
1916 | will return C<4>. When the timer expires and is restarted, it will return |
1851 | roughly C<7> (likely slightly less as callback invocation takes some time, |
1917 | roughly C<7> (likely slightly less as callback invocation takes some time, |
1852 | too), and so on. |
1918 | too), and so on. |
1853 | |
1919 | |
1854 | =item ev_tstamp repeat [read-write] |
1920 | =item ev_tstamp repeat [read-write] |
… | |
… | |
2114 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2180 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2115 | not be unduly interrupted. If you have a problem with system calls getting |
2181 | not be unduly interrupted. If you have a problem with system calls getting |
2116 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2182 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2117 | and unblock them in an C<ev_prepare> watcher. |
2183 | and unblock them in an C<ev_prepare> watcher. |
2118 | |
2184 | |
2119 | =head3 The special problem of inheritance over execve |
2185 | =head3 The special problem of inheritance over fork/execve/pthread_create |
2120 | |
2186 | |
2121 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2187 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2122 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2188 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2123 | stopping it again), that is, libev might or might not block the signal, |
2189 | stopping it again), that is, libev might or might not block the signal, |
2124 | and might or might not set or restore the installed signal handler. |
2190 | and might or might not set or restore the installed signal handler. |
… | |
… | |
2130 | |
2196 | |
2131 | This means that before calling C<exec> (from the child) you should reset |
2197 | This means that before calling C<exec> (from the child) you should reset |
2132 | the signal mask to whatever "default" you expect (all clear is a good |
2198 | the signal mask to whatever "default" you expect (all clear is a good |
2133 | choice usually). |
2199 | choice usually). |
2134 | |
2200 | |
2135 | In current versions of libev, you can ensure that the signal mask is not |
2201 | The simplest way to ensure that the signal mask is reset in the child is |
2136 | blocking any signals (except temporarily, so thread users watch out) by |
2202 | to install a fork handler with C<pthread_atfork> that resets it. That will |
2137 | specifying the C<EVFLAG_NOSIGNALFD> when creating the event loop. This is |
2203 | catch fork calls done by libraries (such as the libc) as well. |
2138 | not guaranteed for future versions, however. |
2204 | |
|
|
2205 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2206 | unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces |
|
|
2207 | the window of opportunity for problems, it will not go away, as libev |
|
|
2208 | I<has> to modify the signal mask, at least temporarily. |
|
|
2209 | |
|
|
2210 | So I can't stress this enough: I<If you do not reset your signal mask when |
|
|
2211 | you expect it to be empty, you have a race condition in your code>. This |
|
|
2212 | is not a libev-specific thing, this is true for most event libraries. |
2139 | |
2213 | |
2140 | =head3 Watcher-Specific Functions and Data Members |
2214 | =head3 Watcher-Specific Functions and Data Members |
2141 | |
2215 | |
2142 | =over 4 |
2216 | =over 4 |
2143 | |
2217 | |
… | |
… | |
2960 | =head3 Queueing |
3034 | =head3 Queueing |
2961 | |
3035 | |
2962 | C<ev_async> does not support queueing of data in any way. The reason |
3036 | C<ev_async> does not support queueing of data in any way. The reason |
2963 | is that the author does not know of a simple (or any) algorithm for a |
3037 | is that the author does not know of a simple (or any) algorithm for a |
2964 | multiple-writer-single-reader queue that works in all cases and doesn't |
3038 | multiple-writer-single-reader queue that works in all cases and doesn't |
2965 | need elaborate support such as pthreads. |
3039 | need elaborate support such as pthreads or unportable memory access |
|
|
3040 | semantics. |
2966 | |
3041 | |
2967 | That means that if you want to queue data, you have to provide your own |
3042 | That means that if you want to queue data, you have to provide your own |
2968 | queue. But at least I can tell you how to implement locking around your |
3043 | queue. But at least I can tell you how to implement locking around your |
2969 | queue: |
3044 | queue: |
2970 | |
3045 | |
… | |
… | |
3109 | |
3184 | |
3110 | If C<timeout> is less than 0, then no timeout watcher will be |
3185 | If C<timeout> is less than 0, then no timeout watcher will be |
3111 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3186 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3112 | repeat = 0) will be started. C<0> is a valid timeout. |
3187 | repeat = 0) will be started. C<0> is a valid timeout. |
3113 | |
3188 | |
3114 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
3189 | The callback has the type C<void (*cb)(int revents, void *arg)> and is |
3115 | passed an C<revents> set like normal event callbacks (a combination of |
3190 | passed an C<revents> set like normal event callbacks (a combination of |
3116 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
3191 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg> |
3117 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3192 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3118 | a timeout and an io event at the same time - you probably should give io |
3193 | a timeout and an io event at the same time - you probably should give io |
3119 | events precedence. |
3194 | events precedence. |
3120 | |
3195 | |
3121 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3196 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3122 | |
3197 | |
3123 | static void stdin_ready (int revents, void *arg) |
3198 | static void stdin_ready (int revents, void *arg) |
3124 | { |
3199 | { |
3125 | if (revents & EV_READ) |
3200 | if (revents & EV_READ) |
3126 | /* stdin might have data for us, joy! */; |
3201 | /* stdin might have data for us, joy! */; |
3127 | else if (revents & EV_TIMEOUT) |
3202 | else if (revents & EV_TIMER) |
3128 | /* doh, nothing entered */; |
3203 | /* doh, nothing entered */; |
3129 | } |
3204 | } |
3130 | |
3205 | |
3131 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3206 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3132 | |
3207 | |
3133 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
|
|
3134 | |
|
|
3135 | Feeds the given event set into the event loop, as if the specified event |
|
|
3136 | had happened for the specified watcher (which must be a pointer to an |
|
|
3137 | initialised but not necessarily started event watcher). |
|
|
3138 | |
|
|
3139 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
3208 | =item ev_feed_fd_event (loop, int fd, int revents) |
3140 | |
3209 | |
3141 | Feed an event on the given fd, as if a file descriptor backend detected |
3210 | Feed an event on the given fd, as if a file descriptor backend detected |
3142 | the given events it. |
3211 | the given events it. |
3143 | |
3212 | |
3144 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
3213 | =item ev_feed_signal_event (loop, int signum) |
3145 | |
3214 | |
3146 | Feed an event as if the given signal occurred (C<loop> must be the default |
3215 | Feed an event as if the given signal occurred (C<loop> must be the default |
3147 | loop!). |
3216 | loop!). |
3148 | |
3217 | |
3149 | =back |
3218 | =back |
… | |
… | |
3229 | |
3298 | |
3230 | =over 4 |
3299 | =over 4 |
3231 | |
3300 | |
3232 | =item ev::TYPE::TYPE () |
3301 | =item ev::TYPE::TYPE () |
3233 | |
3302 | |
3234 | =item ev::TYPE::TYPE (struct ev_loop *) |
3303 | =item ev::TYPE::TYPE (loop) |
3235 | |
3304 | |
3236 | =item ev::TYPE::~TYPE |
3305 | =item ev::TYPE::~TYPE |
3237 | |
3306 | |
3238 | The constructor (optionally) takes an event loop to associate the watcher |
3307 | The constructor (optionally) takes an event loop to associate the watcher |
3239 | with. If it is omitted, it will use C<EV_DEFAULT>. |
3308 | with. If it is omitted, it will use C<EV_DEFAULT>. |
… | |
… | |
3272 | myclass obj; |
3341 | myclass obj; |
3273 | ev::io iow; |
3342 | ev::io iow; |
3274 | iow.set <myclass, &myclass::io_cb> (&obj); |
3343 | iow.set <myclass, &myclass::io_cb> (&obj); |
3275 | |
3344 | |
3276 | =item w->set (object *) |
3345 | =item w->set (object *) |
3277 | |
|
|
3278 | This is an B<experimental> feature that might go away in a future version. |
|
|
3279 | |
3346 | |
3280 | This is a variation of a method callback - leaving out the method to call |
3347 | This is a variation of a method callback - leaving out the method to call |
3281 | will default the method to C<operator ()>, which makes it possible to use |
3348 | will default the method to C<operator ()>, which makes it possible to use |
3282 | functor objects without having to manually specify the C<operator ()> all |
3349 | functor objects without having to manually specify the C<operator ()> all |
3283 | the time. Incidentally, you can then also leave out the template argument |
3350 | the time. Incidentally, you can then also leave out the template argument |
… | |
… | |
3316 | Example: Use a plain function as callback. |
3383 | Example: Use a plain function as callback. |
3317 | |
3384 | |
3318 | static void io_cb (ev::io &w, int revents) { } |
3385 | static void io_cb (ev::io &w, int revents) { } |
3319 | iow.set <io_cb> (); |
3386 | iow.set <io_cb> (); |
3320 | |
3387 | |
3321 | =item w->set (struct ev_loop *) |
3388 | =item w->set (loop) |
3322 | |
3389 | |
3323 | Associates a different C<struct ev_loop> with this watcher. You can only |
3390 | Associates a different C<struct ev_loop> with this watcher. You can only |
3324 | do this when the watcher is inactive (and not pending either). |
3391 | do this when the watcher is inactive (and not pending either). |
3325 | |
3392 | |
3326 | =item w->set ([arguments]) |
3393 | =item w->set ([arguments]) |
… | |
… | |
3425 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3492 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3426 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3493 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3427 | |
3494 | |
3428 | =item Lua |
3495 | =item Lua |
3429 | |
3496 | |
3430 | Brian Maher has written a partial interface to libev |
3497 | Brian Maher has written a partial interface to libev for lua (at the |
3431 | for lua (only C<ev_io> and C<ev_timer>), to be found at |
3498 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
3432 | L<http://github.com/brimworks/lua-ev>. |
3499 | L<http://github.com/brimworks/lua-ev>. |
3433 | |
3500 | |
3434 | =back |
3501 | =back |
3435 | |
3502 | |
3436 | |
3503 | |
… | |
… | |
3591 | libev.m4 |
3658 | libev.m4 |
3592 | |
3659 | |
3593 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3660 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3594 | |
3661 | |
3595 | Libev can be configured via a variety of preprocessor symbols you have to |
3662 | Libev can be configured via a variety of preprocessor symbols you have to |
3596 | define before including any of its files. The default in the absence of |
3663 | define before including (or compiling) any of its files. The default in |
3597 | autoconf is documented for every option. |
3664 | the absence of autoconf is documented for every option. |
|
|
3665 | |
|
|
3666 | Symbols marked with "(h)" do not change the ABI, and can have different |
|
|
3667 | values when compiling libev vs. including F<ev.h>, so it is permissible |
|
|
3668 | to redefine them before including F<ev.h> without breaking compatibility |
|
|
3669 | to a compiled library. All other symbols change the ABI, which means all |
|
|
3670 | users of libev and the libev code itself must be compiled with compatible |
|
|
3671 | settings. |
3598 | |
3672 | |
3599 | =over 4 |
3673 | =over 4 |
3600 | |
3674 | |
3601 | =item EV_STANDALONE |
3675 | =item EV_STANDALONE (h) |
3602 | |
3676 | |
3603 | Must always be C<1> if you do not use autoconf configuration, which |
3677 | Must always be C<1> if you do not use autoconf configuration, which |
3604 | keeps libev from including F<config.h>, and it also defines dummy |
3678 | keeps libev from including F<config.h>, and it also defines dummy |
3605 | implementations for some libevent functions (such as logging, which is not |
3679 | implementations for some libevent functions (such as logging, which is not |
3606 | supported). It will also not define any of the structs usually found in |
3680 | supported). It will also not define any of the structs usually found in |
… | |
… | |
3756 | as well as for signal and thread safety in C<ev_async> watchers. |
3830 | as well as for signal and thread safety in C<ev_async> watchers. |
3757 | |
3831 | |
3758 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3832 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3759 | (from F<signal.h>), which is usually good enough on most platforms. |
3833 | (from F<signal.h>), which is usually good enough on most platforms. |
3760 | |
3834 | |
3761 | =item EV_H |
3835 | =item EV_H (h) |
3762 | |
3836 | |
3763 | The name of the F<ev.h> header file used to include it. The default if |
3837 | The name of the F<ev.h> header file used to include it. The default if |
3764 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3838 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3765 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3839 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3766 | |
3840 | |
3767 | =item EV_CONFIG_H |
3841 | =item EV_CONFIG_H (h) |
3768 | |
3842 | |
3769 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3843 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3770 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3844 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3771 | C<EV_H>, above. |
3845 | C<EV_H>, above. |
3772 | |
3846 | |
3773 | =item EV_EVENT_H |
3847 | =item EV_EVENT_H (h) |
3774 | |
3848 | |
3775 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3849 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3776 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3850 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3777 | |
3851 | |
3778 | =item EV_PROTOTYPES |
3852 | =item EV_PROTOTYPES (h) |
3779 | |
3853 | |
3780 | If defined to be C<0>, then F<ev.h> will not define any function |
3854 | If defined to be C<0>, then F<ev.h> will not define any function |
3781 | prototypes, but still define all the structs and other symbols. This is |
3855 | prototypes, but still define all the structs and other symbols. This is |
3782 | occasionally useful if you want to provide your own wrapper functions |
3856 | occasionally useful if you want to provide your own wrapper functions |
3783 | around libev functions. |
3857 | around libev functions. |
… | |
… | |
3805 | fine. |
3879 | fine. |
3806 | |
3880 | |
3807 | If your embedding application does not need any priorities, defining these |
3881 | If your embedding application does not need any priorities, defining these |
3808 | both to C<0> will save some memory and CPU. |
3882 | both to C<0> will save some memory and CPU. |
3809 | |
3883 | |
3810 | =item EV_PERIODIC_ENABLE |
3884 | =item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, |
|
|
3885 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
|
|
3886 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3811 | |
3887 | |
3812 | If undefined or defined to be C<1>, then periodic timers are supported. If |
3888 | If undefined or defined to be C<1> (and the platform supports it), then |
3813 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
3889 | the respective watcher type is supported. If defined to be C<0>, then it |
3814 | code. |
3890 | is not. Disabling watcher types mainly saves code size. |
3815 | |
3891 | |
3816 | =item EV_IDLE_ENABLE |
3892 | =item EV_FEATURES |
3817 | |
|
|
3818 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3819 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3820 | code. |
|
|
3821 | |
|
|
3822 | =item EV_EMBED_ENABLE |
|
|
3823 | |
|
|
3824 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3825 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3826 | watcher types, which therefore must not be disabled. |
|
|
3827 | |
|
|
3828 | =item EV_STAT_ENABLE |
|
|
3829 | |
|
|
3830 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3831 | defined to be C<0>, then they are not. |
|
|
3832 | |
|
|
3833 | =item EV_FORK_ENABLE |
|
|
3834 | |
|
|
3835 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3836 | defined to be C<0>, then they are not. |
|
|
3837 | |
|
|
3838 | =item EV_ASYNC_ENABLE |
|
|
3839 | |
|
|
3840 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3841 | defined to be C<0>, then they are not. |
|
|
3842 | |
|
|
3843 | =item EV_MINIMAL |
|
|
3844 | |
3893 | |
3845 | If you need to shave off some kilobytes of code at the expense of some |
3894 | If you need to shave off some kilobytes of code at the expense of some |
3846 | speed (but with the full API), define this symbol to C<1>. Currently this |
3895 | speed (but with the full API), you can define this symbol to request |
3847 | is used to override some inlining decisions, saves roughly 30% code size |
3896 | certain subsets of functionality. The default is to enable all features |
3848 | on amd64. It also selects a much smaller 2-heap for timer management over |
3897 | that can be enabled on the platform. |
3849 | the default 4-heap. |
|
|
3850 | |
3898 | |
3851 | You can save even more by disabling watcher types you do not need |
3899 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
3852 | and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert> |
3900 | with some broad features you want) and then selectively re-enable |
3853 | (C<-DNDEBUG>) will usually reduce code size a lot. |
3901 | additional parts you want, for example if you want everything minimal, |
|
|
3902 | but multiple event loop support, async and child watchers and the poll |
|
|
3903 | backend, use this: |
3854 | |
3904 | |
3855 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
3905 | #define EV_FEATURES 0 |
3856 | provide a bare-bones event library. See C<ev.h> for details on what parts |
3906 | #define EV_MULTIPLICITY 1 |
3857 | of the API are still available, and do not complain if this subset changes |
3907 | #define EV_USE_POLL 1 |
3858 | over time. |
3908 | #define EV_CHILD_ENABLE 1 |
|
|
3909 | #define EV_ASYNC_ENABLE 1 |
|
|
3910 | |
|
|
3911 | The actual value is a bitset, it can be a combination of the following |
|
|
3912 | values: |
|
|
3913 | |
|
|
3914 | =over 4 |
|
|
3915 | |
|
|
3916 | =item C<1> - faster/larger code |
|
|
3917 | |
|
|
3918 | Use larger code to speed up some operations. |
|
|
3919 | |
|
|
3920 | Currently this is used to override some inlining decisions (enlarging the |
|
|
3921 | code size by roughly 30% on amd64). |
|
|
3922 | |
|
|
3923 | When optimising for size, use of compiler flags such as C<-Os> with |
|
|
3924 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
|
|
3925 | assertions. |
|
|
3926 | |
|
|
3927 | =item C<2> - faster/larger data structures |
|
|
3928 | |
|
|
3929 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
|
|
3930 | hash table sizes and so on. This will usually further increase code size |
|
|
3931 | and can additionally have an effect on the size of data structures at |
|
|
3932 | runtime. |
|
|
3933 | |
|
|
3934 | =item C<4> - full API configuration |
|
|
3935 | |
|
|
3936 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
|
|
3937 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
|
|
3938 | |
|
|
3939 | =item C<8> - full API |
|
|
3940 | |
|
|
3941 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
|
|
3942 | details on which parts of the API are still available without this |
|
|
3943 | feature, and do not complain if this subset changes over time. |
|
|
3944 | |
|
|
3945 | =item C<16> - enable all optional watcher types |
|
|
3946 | |
|
|
3947 | Enables all optional watcher types. If you want to selectively enable |
|
|
3948 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
3949 | embed, async, child...) you can enable them manually by defining |
|
|
3950 | C<EV_watchertype_ENABLE> to C<1> instead. |
|
|
3951 | |
|
|
3952 | =item C<32> - enable all backends |
|
|
3953 | |
|
|
3954 | This enables all backends - without this feature, you need to enable at |
|
|
3955 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
|
|
3956 | |
|
|
3957 | =item C<64> - enable OS-specific "helper" APIs |
|
|
3958 | |
|
|
3959 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
3960 | default. |
|
|
3961 | |
|
|
3962 | =back |
|
|
3963 | |
|
|
3964 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
|
|
3965 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
3966 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
3967 | watchers, timers and monotonic clock support. |
|
|
3968 | |
|
|
3969 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
3970 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
|
|
3971 | your program might be left out as well - a binary starting a timer and an |
|
|
3972 | I/O watcher then might come out at only 5Kb. |
|
|
3973 | |
|
|
3974 | =item EV_AVOID_STDIO |
|
|
3975 | |
|
|
3976 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
|
|
3977 | functions (printf, scanf, perror etc.). This will increase the code size |
|
|
3978 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
3979 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
3980 | big. |
|
|
3981 | |
|
|
3982 | Note that error messages might become less precise when this option is |
|
|
3983 | enabled. |
3859 | |
3984 | |
3860 | =item EV_NSIG |
3985 | =item EV_NSIG |
3861 | |
3986 | |
3862 | The highest supported signal number, +1 (or, the number of |
3987 | The highest supported signal number, +1 (or, the number of |
3863 | signals): Normally, libev tries to deduce the maximum number of signals |
3988 | signals): Normally, libev tries to deduce the maximum number of signals |
3864 | automatically, but sometimes this fails, in which case it can be |
3989 | automatically, but sometimes this fails, in which case it can be |
3865 | specified. Also, using a lower number than detected (C<32> should be |
3990 | specified. Also, using a lower number than detected (C<32> should be |
3866 | good for about any system in existance) can save some memory, as libev |
3991 | good for about any system in existence) can save some memory, as libev |
3867 | statically allocates some 12-24 bytes per signal number. |
3992 | statically allocates some 12-24 bytes per signal number. |
3868 | |
3993 | |
3869 | =item EV_PID_HASHSIZE |
3994 | =item EV_PID_HASHSIZE |
3870 | |
3995 | |
3871 | C<ev_child> watchers use a small hash table to distribute workload by |
3996 | C<ev_child> watchers use a small hash table to distribute workload by |
3872 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
3997 | pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled), |
3873 | than enough. If you need to manage thousands of children you might want to |
3998 | usually more than enough. If you need to manage thousands of children you |
3874 | increase this value (I<must> be a power of two). |
3999 | might want to increase this value (I<must> be a power of two). |
3875 | |
4000 | |
3876 | =item EV_INOTIFY_HASHSIZE |
4001 | =item EV_INOTIFY_HASHSIZE |
3877 | |
4002 | |
3878 | C<ev_stat> watchers use a small hash table to distribute workload by |
4003 | C<ev_stat> watchers use a small hash table to distribute workload by |
3879 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
4004 | inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES> |
3880 | usually more than enough. If you need to manage thousands of C<ev_stat> |
4005 | disabled), usually more than enough. If you need to manage thousands of |
3881 | watchers you might want to increase this value (I<must> be a power of |
4006 | C<ev_stat> watchers you might want to increase this value (I<must> be a |
3882 | two). |
4007 | power of two). |
3883 | |
4008 | |
3884 | =item EV_USE_4HEAP |
4009 | =item EV_USE_4HEAP |
3885 | |
4010 | |
3886 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4011 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3887 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
4012 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3888 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
4013 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3889 | faster performance with many (thousands) of watchers. |
4014 | faster performance with many (thousands) of watchers. |
3890 | |
4015 | |
3891 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4016 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3892 | (disabled). |
4017 | will be C<0>. |
3893 | |
4018 | |
3894 | =item EV_HEAP_CACHE_AT |
4019 | =item EV_HEAP_CACHE_AT |
3895 | |
4020 | |
3896 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4021 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3897 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
4022 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3898 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
4023 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3899 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
4024 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3900 | but avoids random read accesses on heap changes. This improves performance |
4025 | but avoids random read accesses on heap changes. This improves performance |
3901 | noticeably with many (hundreds) of watchers. |
4026 | noticeably with many (hundreds) of watchers. |
3902 | |
4027 | |
3903 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4028 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3904 | (disabled). |
4029 | will be C<0>. |
3905 | |
4030 | |
3906 | =item EV_VERIFY |
4031 | =item EV_VERIFY |
3907 | |
4032 | |
3908 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4033 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
3909 | be done: If set to C<0>, no internal verification code will be compiled |
4034 | be done: If set to C<0>, no internal verification code will be compiled |
… | |
… | |
3911 | called. If set to C<2>, then the internal verification code will be |
4036 | called. If set to C<2>, then the internal verification code will be |
3912 | called once per loop, which can slow down libev. If set to C<3>, then the |
4037 | called once per loop, which can slow down libev. If set to C<3>, then the |
3913 | verification code will be called very frequently, which will slow down |
4038 | verification code will be called very frequently, which will slow down |
3914 | libev considerably. |
4039 | libev considerably. |
3915 | |
4040 | |
3916 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
4041 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3917 | C<0>. |
4042 | will be C<0>. |
3918 | |
4043 | |
3919 | =item EV_COMMON |
4044 | =item EV_COMMON |
3920 | |
4045 | |
3921 | By default, all watchers have a C<void *data> member. By redefining |
4046 | By default, all watchers have a C<void *data> member. By redefining |
3922 | this macro to a something else you can include more and other types of |
4047 | this macro to something else you can include more and other types of |
3923 | members. You have to define it each time you include one of the files, |
4048 | members. You have to define it each time you include one of the files, |
3924 | though, and it must be identical each time. |
4049 | though, and it must be identical each time. |
3925 | |
4050 | |
3926 | For example, the perl EV module uses something like this: |
4051 | For example, the perl EV module uses something like this: |
3927 | |
4052 | |
… | |
… | |
3980 | file. |
4105 | file. |
3981 | |
4106 | |
3982 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4107 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
3983 | that everybody includes and which overrides some configure choices: |
4108 | that everybody includes and which overrides some configure choices: |
3984 | |
4109 | |
3985 | #define EV_MINIMAL 1 |
4110 | #define EV_FEATURES 8 |
3986 | #define EV_USE_POLL 0 |
4111 | #define EV_USE_SELECT 1 |
3987 | #define EV_MULTIPLICITY 0 |
|
|
3988 | #define EV_PERIODIC_ENABLE 0 |
4112 | #define EV_PREPARE_ENABLE 1 |
|
|
4113 | #define EV_IDLE_ENABLE 1 |
3989 | #define EV_STAT_ENABLE 0 |
4114 | #define EV_SIGNAL_ENABLE 1 |
3990 | #define EV_FORK_ENABLE 0 |
4115 | #define EV_CHILD_ENABLE 1 |
|
|
4116 | #define EV_USE_STDEXCEPT 0 |
3991 | #define EV_CONFIG_H <config.h> |
4117 | #define EV_CONFIG_H <config.h> |
3992 | #define EV_MINPRI 0 |
|
|
3993 | #define EV_MAXPRI 0 |
|
|
3994 | |
4118 | |
3995 | #include "ev++.h" |
4119 | #include "ev++.h" |
3996 | |
4120 | |
3997 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4121 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
3998 | |
4122 | |
… | |
… | |
4227 | maintainable. |
4351 | maintainable. |
4228 | |
4352 | |
4229 | And of course, some compiler warnings are just plain stupid, or simply |
4353 | And of course, some compiler warnings are just plain stupid, or simply |
4230 | wrong (because they don't actually warn about the condition their message |
4354 | wrong (because they don't actually warn about the condition their message |
4231 | seems to warn about). For example, certain older gcc versions had some |
4355 | seems to warn about). For example, certain older gcc versions had some |
4232 | warnings that resulted an extreme number of false positives. These have |
4356 | warnings that resulted in an extreme number of false positives. These have |
4233 | been fixed, but some people still insist on making code warn-free with |
4357 | been fixed, but some people still insist on making code warn-free with |
4234 | such buggy versions. |
4358 | such buggy versions. |
4235 | |
4359 | |
4236 | While libev is written to generate as few warnings as possible, |
4360 | While libev is written to generate as few warnings as possible, |
4237 | "warn-free" code is not a goal, and it is recommended not to build libev |
4361 | "warn-free" code is not a goal, and it is recommended not to build libev |
… | |
… | |
4500 | involves iterating over all running async watchers or all signal numbers. |
4624 | involves iterating over all running async watchers or all signal numbers. |
4501 | |
4625 | |
4502 | =back |
4626 | =back |
4503 | |
4627 | |
4504 | |
4628 | |
|
|
4629 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
|
|
4630 | |
|
|
4631 | The major version 4 introduced some minor incompatible changes to the API. |
|
|
4632 | |
|
|
4633 | At the moment, the C<ev.h> header file tries to implement superficial |
|
|
4634 | compatibility, so most programs should still compile. Those might be |
|
|
4635 | removed in later versions of libev, so better update early than late. |
|
|
4636 | |
|
|
4637 | =over 4 |
|
|
4638 | |
|
|
4639 | =item C<ev_loop_count> renamed to C<ev_iteration> |
|
|
4640 | |
|
|
4641 | =item C<ev_loop_depth> renamed to C<ev_depth> |
|
|
4642 | |
|
|
4643 | =item C<ev_loop_verify> renamed to C<ev_verify> |
|
|
4644 | |
|
|
4645 | Most functions working on C<struct ev_loop> objects don't have an |
|
|
4646 | C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is |
|
|
4647 | still called C<ev_loop_fork> because it would otherwise clash with the |
|
|
4648 | C<ev_fork> typedef. |
|
|
4649 | |
|
|
4650 | =item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents> |
|
|
4651 | |
|
|
4652 | This is a simple rename - all other watcher types use their name |
|
|
4653 | as revents flag, and now C<ev_timer> does, too. |
|
|
4654 | |
|
|
4655 | Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions |
|
|
4656 | and continue to be present for the foreseeable future, so this is mostly a |
|
|
4657 | documentation change. |
|
|
4658 | |
|
|
4659 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
4660 | |
|
|
4661 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
4662 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
4663 | and work, but the library code will of course be larger. |
|
|
4664 | |
|
|
4665 | =back |
|
|
4666 | |
|
|
4667 | |
4505 | =head1 GLOSSARY |
4668 | =head1 GLOSSARY |
4506 | |
4669 | |
4507 | =over 4 |
4670 | =over 4 |
4508 | |
4671 | |
4509 | =item active |
4672 | =item active |
… | |
… | |
4530 | A change of state of some external event, such as data now being available |
4693 | A change of state of some external event, such as data now being available |
4531 | for reading on a file descriptor, time having passed or simply not having |
4694 | for reading on a file descriptor, time having passed or simply not having |
4532 | any other events happening anymore. |
4695 | any other events happening anymore. |
4533 | |
4696 | |
4534 | In libev, events are represented as single bits (such as C<EV_READ> or |
4697 | In libev, events are represented as single bits (such as C<EV_READ> or |
4535 | C<EV_TIMEOUT>). |
4698 | C<EV_TIMER>). |
4536 | |
4699 | |
4537 | =item event library |
4700 | =item event library |
4538 | |
4701 | |
4539 | A software package implementing an event model and loop. |
4702 | A software package implementing an event model and loop. |
4540 | |
4703 | |