… | |
… | |
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 practice |
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). |
… | |
… | |
164 | |
165 | |
165 | =item ev_tstamp ev_time () |
166 | =item ev_tstamp ev_time () |
166 | |
167 | |
167 | Returns the current time as libev would use it. Please note that the |
168 | Returns the current time as libev would use it. Please note that the |
168 | C<ev_now> function is usually faster and also often returns the timestamp |
169 | C<ev_now> function is usually faster and also often returns the timestamp |
169 | you actually want to know. |
170 | you actually want to know. Also interesting is the combination of |
|
|
171 | C<ev_update_now> and C<ev_now>. |
170 | |
172 | |
171 | =item ev_sleep (ev_tstamp interval) |
173 | =item ev_sleep (ev_tstamp interval) |
172 | |
174 | |
173 | Sleep for the given interval: The current thread will be blocked until |
175 | Sleep for the given interval: The current thread will be blocked until |
174 | either it is interrupted or the given time interval has passed. Basically |
176 | either it is interrupted or the given time interval has passed. Basically |
… | |
… | |
191 | as this indicates an incompatible change. Minor versions are usually |
193 | as this indicates an incompatible change. Minor versions are usually |
192 | compatible to older versions, so a larger minor version alone is usually |
194 | compatible to older versions, so a larger minor version alone is usually |
193 | not a problem. |
195 | not a problem. |
194 | |
196 | |
195 | Example: Make sure we haven't accidentally been linked against the wrong |
197 | Example: Make sure we haven't accidentally been linked against the wrong |
196 | version. |
198 | version (note, however, that this will not detect other ABI mismatches, |
|
|
199 | such as LFS or reentrancy). |
197 | |
200 | |
198 | assert (("libev version mismatch", |
201 | assert (("libev version mismatch", |
199 | ev_version_major () == EV_VERSION_MAJOR |
202 | ev_version_major () == EV_VERSION_MAJOR |
200 | && ev_version_minor () >= EV_VERSION_MINOR)); |
203 | && ev_version_minor () >= EV_VERSION_MINOR)); |
201 | |
204 | |
… | |
… | |
212 | assert (("sorry, no epoll, no sex", |
215 | assert (("sorry, no epoll, no sex", |
213 | ev_supported_backends () & EVBACKEND_EPOLL)); |
216 | ev_supported_backends () & EVBACKEND_EPOLL)); |
214 | |
217 | |
215 | =item unsigned int ev_recommended_backends () |
218 | =item unsigned int ev_recommended_backends () |
216 | |
219 | |
217 | Return the set of all backends compiled into this binary of libev and also |
220 | Return the set of all backends compiled into this binary of libev and |
218 | recommended for this platform. This set is often smaller than the one |
221 | also recommended for this platform, meaning it will work for most file |
|
|
222 | descriptor types. This set is often smaller than the one returned by |
219 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
223 | C<ev_supported_backends>, as for example kqueue is broken on most BSDs |
220 | most BSDs and will not be auto-detected unless you explicitly request it |
224 | and will not be auto-detected unless you explicitly request it (assuming |
221 | (assuming you know what you are doing). This is the set of backends that |
225 | you know what you are doing). This is the set of backends that libev will |
222 | libev will probe for if you specify no backends explicitly. |
226 | probe for if you specify no backends explicitly. |
223 | |
227 | |
224 | =item unsigned int ev_embeddable_backends () |
228 | =item unsigned int ev_embeddable_backends () |
225 | |
229 | |
226 | Returns the set of backends that are embeddable in other event loops. This |
230 | Returns the set of backends that are embeddable in other event loops. This |
227 | is the theoretical, all-platform, value. To find which backends |
231 | value is platform-specific but can include backends not available on the |
228 | might be supported on the current system, you would need to look at |
232 | current system. To find which embeddable backends might be supported on |
229 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
233 | the current system, you would need to look at C<ev_embeddable_backends () |
230 | recommended ones. |
234 | & ev_supported_backends ()>, likewise for recommended ones. |
231 | |
235 | |
232 | See the description of C<ev_embed> watchers for more info. |
236 | See the description of C<ev_embed> watchers for more info. |
233 | |
237 | |
234 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT] |
238 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT] |
235 | |
239 | |
… | |
… | |
291 | |
295 | |
292 | =back |
296 | =back |
293 | |
297 | |
294 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
298 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
295 | |
299 | |
296 | An event loop is described by a C<struct ev_loop *> (the C<struct> |
300 | 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> |
301 | I<not> optional in this case unless libev 3 compatibility is disabled, as |
298 | I<function>). |
302 | libev 3 had an C<ev_loop> function colliding with the struct name). |
299 | |
303 | |
300 | The library knows two types of such loops, the I<default> loop, which |
304 | 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 |
305 | supports signals and child events, and dynamically created event loops |
302 | not. |
306 | which do not. |
303 | |
307 | |
304 | =over 4 |
308 | =over 4 |
305 | |
309 | |
306 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
310 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
307 | |
311 | |
… | |
… | |
345 | useful to try out specific backends to test their performance, or to work |
349 | useful to try out specific backends to test their performance, or to work |
346 | around bugs. |
350 | around bugs. |
347 | |
351 | |
348 | =item C<EVFLAG_FORKCHECK> |
352 | =item C<EVFLAG_FORKCHECK> |
349 | |
353 | |
350 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
354 | 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 |
355 | make libev check for a fork in each iteration by enabling this flag. |
352 | enabling this flag. |
|
|
353 | |
356 | |
354 | This works by calling C<getpid ()> on every iteration of the loop, |
357 | 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 |
358 | 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 |
359 | 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 |
360 | 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 |
373 | 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 |
374 | 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 |
375 | 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. |
376 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
374 | |
377 | |
375 | =item C<EVFLAG_NOSIGFD> |
378 | =item C<EVFLAG_SIGNALFD> |
376 | |
379 | |
377 | When this flag is specified, then libev will not attempt to use the |
380 | 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 |
381 | 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 |
382 | delivers signals synchronously, which makes it both faster and might make |
380 | flag might go away once the signalfd functionality is considered stable, |
383 | 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. |
384 | handling with threads, as long as you properly block signals in your |
|
|
385 | threads that are not interested in handling them. |
|
|
386 | |
|
|
387 | Signalfd will not be used by default as this changes your signal mask, and |
|
|
388 | there are a lot of shoddy libraries and programs (glib's threadpool for |
|
|
389 | example) that can't properly initialise their signal masks. |
382 | |
390 | |
383 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
391 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
384 | |
392 | |
385 | This is your standard select(2) backend. Not I<completely> standard, as |
393 | 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, |
394 | libev tries to roll its own fd_set with no limits on the number of fds, |
… | |
… | |
434 | of course I<doesn't>, and epoll just loves to report events for totally |
442 | of course I<doesn't>, and epoll just loves to report events for totally |
435 | I<different> file descriptors (even already closed ones, so one cannot |
443 | I<different> file descriptors (even already closed ones, so one cannot |
436 | even remove them from the set) than registered in the set (especially |
444 | even remove them from the set) than registered in the set (especially |
437 | on SMP systems). Libev tries to counter these spurious notifications by |
445 | on SMP systems). Libev tries to counter these spurious notifications by |
438 | employing an additional generation counter and comparing that against the |
446 | employing an additional generation counter and comparing that against the |
439 | events to filter out spurious ones, recreating the set when required. |
447 | events to filter out spurious ones, recreating the set when required. Last |
|
|
448 | not least, it also refuses to work with some file descriptors which work |
|
|
449 | perfectly fine with C<select> (files, many character devices...). |
440 | |
450 | |
441 | While stopping, setting and starting an I/O watcher in the same iteration |
451 | While stopping, setting and starting an I/O watcher in the same iteration |
442 | will result in some caching, there is still a system call per such |
452 | will result in some caching, there is still a system call per such |
443 | incident (because the same I<file descriptor> could point to a different |
453 | incident (because the same I<file descriptor> could point to a different |
444 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
454 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
… | |
… | |
562 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
572 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
563 | |
573 | |
564 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
574 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
565 | |
575 | |
566 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
576 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
567 | always distinct from the default loop. Unlike the default loop, it cannot |
577 | always distinct from the default loop. |
568 | handle signal and child watchers, and attempts to do so will be greeted by |
|
|
569 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
570 | |
578 | |
571 | Note that this function I<is> thread-safe, and the recommended way to use |
579 | Note that this function I<is> thread-safe, and one common way to use |
572 | libev with threads is indeed to create one loop per thread, and using the |
580 | libev with threads is indeed to create one loop per thread, and using the |
573 | default loop in the "main" or "initial" thread. |
581 | default loop in the "main" or "initial" thread. |
574 | |
582 | |
575 | Example: Try to create a event loop that uses epoll and nothing else. |
583 | Example: Try to create a event loop that uses epoll and nothing else. |
576 | |
584 | |
… | |
… | |
578 | if (!epoller) |
586 | if (!epoller) |
579 | fatal ("no epoll found here, maybe it hides under your chair"); |
587 | fatal ("no epoll found here, maybe it hides under your chair"); |
580 | |
588 | |
581 | =item ev_default_destroy () |
589 | =item ev_default_destroy () |
582 | |
590 | |
583 | Destroys the default loop again (frees all memory and kernel state |
591 | Destroys the default loop (frees all memory and kernel state etc.). None |
584 | etc.). None of the active event watchers will be stopped in the normal |
592 | of the active event watchers will be stopped in the normal sense, so |
585 | sense, so e.g. C<ev_is_active> might still return true. It is your |
593 | e.g. C<ev_is_active> might still return true. It is your responsibility to |
586 | responsibility to either stop all watchers cleanly yourself I<before> |
594 | either stop all watchers cleanly yourself I<before> calling this function, |
587 | calling this function, or cope with the fact afterwards (which is usually |
595 | or cope with the fact afterwards (which is usually the easiest thing, you |
588 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
596 | can just ignore the watchers and/or C<free ()> them for example). |
589 | for example). |
|
|
590 | |
597 | |
591 | Note that certain global state, such as signal state (and installed signal |
598 | Note that certain global state, such as signal state (and installed signal |
592 | handlers), will not be freed by this function, and related watchers (such |
599 | handlers), will not be freed by this function, and related watchers (such |
593 | as signal and child watchers) would need to be stopped manually. |
600 | as signal and child watchers) would need to be stopped manually. |
594 | |
601 | |
… | |
… | |
602 | Like C<ev_default_destroy>, but destroys an event loop created by an |
609 | Like C<ev_default_destroy>, but destroys an event loop created by an |
603 | earlier call to C<ev_loop_new>. |
610 | earlier call to C<ev_loop_new>. |
604 | |
611 | |
605 | =item ev_default_fork () |
612 | =item ev_default_fork () |
606 | |
613 | |
607 | This function sets a flag that causes subsequent C<ev_loop> iterations |
614 | This function sets a flag that causes subsequent C<ev_run> iterations |
608 | to reinitialise the kernel state for backends that have one. Despite the |
615 | to reinitialise the kernel state for backends that have one. Despite the |
609 | name, you can call it anytime, but it makes most sense after forking, in |
616 | name, you can call it anytime, but it makes most sense after forking, in |
610 | the child process (or both child and parent, but that again makes little |
617 | the child process (or both child and parent, but that again makes little |
611 | sense). You I<must> call it in the child before using any of the libev |
618 | sense). You I<must> call it in the child before using any of the libev |
612 | functions, and it will only take effect at the next C<ev_loop> iteration. |
619 | functions, and it will only take effect at the next C<ev_run> iteration. |
|
|
620 | |
|
|
621 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
|
|
622 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
|
|
623 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
|
|
624 | during fork. |
613 | |
625 | |
614 | On the other hand, you only need to call this function in the child |
626 | On the other hand, you only need to call this function in the child |
615 | process if and only if you want to use the event library in the child. If |
627 | process if and only if you want to use the event loop in the child. If |
616 | you just fork+exec, you don't have to call it at all. |
628 | you just fork+exec or create a new loop in the child, you don't have to |
|
|
629 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
|
|
630 | difference, but libev will usually detect this case on its own and do a |
|
|
631 | costly reset of the backend). |
617 | |
632 | |
618 | The function itself is quite fast and it's usually not a problem to call |
633 | The function itself is quite fast and it's usually not a problem to call |
619 | it just in case after a fork. To make this easy, the function will fit in |
634 | it just in case after a fork. To make this easy, the function will fit in |
620 | quite nicely into a call to C<pthread_atfork>: |
635 | quite nicely into a call to C<pthread_atfork>: |
621 | |
636 | |
… | |
… | |
623 | |
638 | |
624 | =item ev_loop_fork (loop) |
639 | =item ev_loop_fork (loop) |
625 | |
640 | |
626 | Like C<ev_default_fork>, but acts on an event loop created by |
641 | Like C<ev_default_fork>, but acts on an event loop created by |
627 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
642 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
628 | after fork that you want to re-use in the child, and how you do this is |
643 | after fork that you want to re-use in the child, and how you keep track of |
629 | entirely your own problem. |
644 | them is entirely your own problem. |
630 | |
645 | |
631 | =item int ev_is_default_loop (loop) |
646 | =item int ev_is_default_loop (loop) |
632 | |
647 | |
633 | Returns true when the given loop is, in fact, the default loop, and false |
648 | Returns true when the given loop is, in fact, the default loop, and false |
634 | otherwise. |
649 | otherwise. |
635 | |
650 | |
636 | =item unsigned int ev_loop_count (loop) |
651 | =item unsigned int ev_iteration (loop) |
637 | |
652 | |
638 | Returns the count of loop iterations for the loop, which is identical to |
653 | Returns the current iteration count for the event loop, which is identical |
639 | the number of times libev did poll for new events. It starts at C<0> and |
654 | to the number of times libev did poll for new events. It starts at C<0> |
640 | happily wraps around with enough iterations. |
655 | and happily wraps around with enough iterations. |
641 | |
656 | |
642 | This value can sometimes be useful as a generation counter of sorts (it |
657 | This value can sometimes be useful as a generation counter of sorts (it |
643 | "ticks" the number of loop iterations), as it roughly corresponds with |
658 | "ticks" the number of loop iterations), as it roughly corresponds with |
644 | C<ev_prepare> and C<ev_check> calls. |
659 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
|
|
660 | prepare and check phases. |
645 | |
661 | |
646 | =item unsigned int ev_loop_depth (loop) |
662 | =item unsigned int ev_depth (loop) |
647 | |
663 | |
648 | Returns the number of times C<ev_loop> was entered minus the number of |
664 | Returns the number of times C<ev_run> was entered minus the number of |
649 | times C<ev_loop> was exited, in other words, the recursion depth. |
665 | times C<ev_run> was exited, in other words, the recursion depth. |
650 | |
666 | |
651 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
667 | Outside C<ev_run>, this number is zero. In a callback, this number is |
652 | C<1>, unless C<ev_loop> was invoked recursively (or from another thread), |
668 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
653 | in which case it is higher. |
669 | in which case it is higher. |
654 | |
670 | |
655 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
671 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread |
656 | etc.), doesn't count as exit. |
672 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
|
|
673 | ungentleman-like behaviour unless it's really convenient. |
657 | |
674 | |
658 | =item unsigned int ev_backend (loop) |
675 | =item unsigned int ev_backend (loop) |
659 | |
676 | |
660 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
677 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
661 | use. |
678 | use. |
… | |
… | |
670 | |
687 | |
671 | =item ev_now_update (loop) |
688 | =item ev_now_update (loop) |
672 | |
689 | |
673 | Establishes the current time by querying the kernel, updating the time |
690 | Establishes the current time by querying the kernel, updating the time |
674 | returned by C<ev_now ()> in the progress. This is a costly operation and |
691 | returned by C<ev_now ()> in the progress. This is a costly operation and |
675 | is usually done automatically within C<ev_loop ()>. |
692 | is usually done automatically within C<ev_run ()>. |
676 | |
693 | |
677 | This function is rarely useful, but when some event callback runs for a |
694 | This function is rarely useful, but when some event callback runs for a |
678 | very long time without entering the event loop, updating libev's idea of |
695 | very long time without entering the event loop, updating libev's idea of |
679 | the current time is a good idea. |
696 | the current time is a good idea. |
680 | |
697 | |
… | |
… | |
682 | |
699 | |
683 | =item ev_suspend (loop) |
700 | =item ev_suspend (loop) |
684 | |
701 | |
685 | =item ev_resume (loop) |
702 | =item ev_resume (loop) |
686 | |
703 | |
687 | These two functions suspend and resume a loop, for use when the loop is |
704 | These two functions suspend and resume an event loop, for use when the |
688 | not used for a while and timeouts should not be processed. |
705 | loop is not used for a while and timeouts should not be processed. |
689 | |
706 | |
690 | A typical use case would be an interactive program such as a game: When |
707 | A typical use case would be an interactive program such as a game: When |
691 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
708 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
692 | would be best to handle timeouts as if no time had actually passed while |
709 | would be best to handle timeouts as if no time had actually passed while |
693 | the program was suspended. This can be achieved by calling C<ev_suspend> |
710 | the program was suspended. This can be achieved by calling C<ev_suspend> |
… | |
… | |
695 | C<ev_resume> directly afterwards to resume timer processing. |
712 | C<ev_resume> directly afterwards to resume timer processing. |
696 | |
713 | |
697 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
714 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
698 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
715 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
699 | will be rescheduled (that is, they will lose any events that would have |
716 | will be rescheduled (that is, they will lose any events that would have |
700 | occured while suspended). |
717 | occurred while suspended). |
701 | |
718 | |
702 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
719 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
703 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
720 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
704 | without a previous call to C<ev_suspend>. |
721 | without a previous call to C<ev_suspend>. |
705 | |
722 | |
706 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
723 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
707 | event loop time (see C<ev_now_update>). |
724 | event loop time (see C<ev_now_update>). |
708 | |
725 | |
709 | =item ev_loop (loop, int flags) |
726 | =item ev_run (loop, int flags) |
710 | |
727 | |
711 | Finally, this is it, the event handler. This function usually is called |
728 | Finally, this is it, the event handler. This function usually is called |
712 | after you have initialised all your watchers and you want to start |
729 | after you have initialised all your watchers and you want to start |
713 | handling events. |
730 | handling events. It will ask the operating system for any new events, call |
|
|
731 | the watcher callbacks, an then repeat the whole process indefinitely: This |
|
|
732 | is why event loops are called I<loops>. |
714 | |
733 | |
715 | If the flags argument is specified as C<0>, it will not return until |
734 | If the flags argument is specified as C<0>, it will keep handling events |
716 | either no event watchers are active anymore or C<ev_unloop> was called. |
735 | until either no event watchers are active anymore or C<ev_break> was |
|
|
736 | called. |
717 | |
737 | |
718 | Please note that an explicit C<ev_unloop> is usually better than |
738 | Please note that an explicit C<ev_break> is usually better than |
719 | relying on all watchers to be stopped when deciding when a program has |
739 | relying on all watchers to be stopped when deciding when a program has |
720 | finished (especially in interactive programs), but having a program |
740 | finished (especially in interactive programs), but having a program |
721 | that automatically loops as long as it has to and no longer by virtue |
741 | that automatically loops as long as it has to and no longer by virtue |
722 | of relying on its watchers stopping correctly, that is truly a thing of |
742 | of relying on its watchers stopping correctly, that is truly a thing of |
723 | beauty. |
743 | beauty. |
724 | |
744 | |
725 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
745 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
726 | those events and any already outstanding ones, but will not block your |
746 | those events and any already outstanding ones, but will not wait and |
727 | process in case there are no events and will return after one iteration of |
747 | block your process in case there are no events and will return after one |
728 | the loop. |
748 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
749 | events while doing lengthy calculations, to keep the program responsive. |
729 | |
750 | |
730 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
751 | A flags value of C<EVRUN_ONCE> will look for new events (waiting if |
731 | necessary) and will handle those and any already outstanding ones. It |
752 | necessary) and will handle those and any already outstanding ones. It |
732 | will block your process until at least one new event arrives (which could |
753 | will block your process until at least one new event arrives (which could |
733 | be an event internal to libev itself, so there is no guarantee that a |
754 | be an event internal to libev itself, so there is no guarantee that a |
734 | user-registered callback will be called), and will return after one |
755 | user-registered callback will be called), and will return after one |
735 | iteration of the loop. |
756 | iteration of the loop. |
736 | |
757 | |
737 | This is useful if you are waiting for some external event in conjunction |
758 | This is useful if you are waiting for some external event in conjunction |
738 | with something not expressible using other libev watchers (i.e. "roll your |
759 | with something not expressible using other libev watchers (i.e. "roll your |
739 | own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
760 | own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
740 | usually a better approach for this kind of thing. |
761 | usually a better approach for this kind of thing. |
741 | |
762 | |
742 | Here are the gory details of what C<ev_loop> does: |
763 | Here are the gory details of what C<ev_run> does: |
743 | |
764 | |
|
|
765 | - Increment loop depth. |
|
|
766 | - Reset the ev_break status. |
744 | - Before the first iteration, call any pending watchers. |
767 | - Before the first iteration, call any pending watchers. |
|
|
768 | LOOP: |
745 | * If EVFLAG_FORKCHECK was used, check for a fork. |
769 | - If EVFLAG_FORKCHECK was used, check for a fork. |
746 | - If a fork was detected (by any means), queue and call all fork watchers. |
770 | - If a fork was detected (by any means), queue and call all fork watchers. |
747 | - Queue and call all prepare watchers. |
771 | - Queue and call all prepare watchers. |
|
|
772 | - If ev_break was called, goto FINISH. |
748 | - If we have been forked, detach and recreate the kernel state |
773 | - If we have been forked, detach and recreate the kernel state |
749 | as to not disturb the other process. |
774 | as to not disturb the other process. |
750 | - Update the kernel state with all outstanding changes. |
775 | - Update the kernel state with all outstanding changes. |
751 | - Update the "event loop time" (ev_now ()). |
776 | - Update the "event loop time" (ev_now ()). |
752 | - Calculate for how long to sleep or block, if at all |
777 | - Calculate for how long to sleep or block, if at all |
753 | (active idle watchers, EVLOOP_NONBLOCK or not having |
778 | (active idle watchers, EVRUN_NOWAIT or not having |
754 | any active watchers at all will result in not sleeping). |
779 | any active watchers at all will result in not sleeping). |
755 | - Sleep if the I/O and timer collect interval say so. |
780 | - Sleep if the I/O and timer collect interval say so. |
|
|
781 | - Increment loop iteration counter. |
756 | - Block the process, waiting for any events. |
782 | - Block the process, waiting for any events. |
757 | - Queue all outstanding I/O (fd) events. |
783 | - Queue all outstanding I/O (fd) events. |
758 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
784 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
759 | - Queue all expired timers. |
785 | - Queue all expired timers. |
760 | - Queue all expired periodics. |
786 | - Queue all expired periodics. |
761 | - Unless any events are pending now, queue all idle watchers. |
787 | - Queue all idle watchers with priority higher than that of pending events. |
762 | - Queue all check watchers. |
788 | - Queue all check watchers. |
763 | - Call all queued watchers in reverse order (i.e. check watchers first). |
789 | - Call all queued watchers in reverse order (i.e. check watchers first). |
764 | Signals and child watchers are implemented as I/O watchers, and will |
790 | Signals and child watchers are implemented as I/O watchers, and will |
765 | be handled here by queueing them when their watcher gets executed. |
791 | be handled here by queueing them when their watcher gets executed. |
766 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
792 | - If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
767 | were used, or there are no active watchers, return, otherwise |
793 | were used, or there are no active watchers, goto FINISH, otherwise |
768 | continue with step *. |
794 | continue with step LOOP. |
|
|
795 | FINISH: |
|
|
796 | - Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
797 | - Decrement the loop depth. |
|
|
798 | - Return. |
769 | |
799 | |
770 | Example: Queue some jobs and then loop until no events are outstanding |
800 | Example: Queue some jobs and then loop until no events are outstanding |
771 | anymore. |
801 | anymore. |
772 | |
802 | |
773 | ... queue jobs here, make sure they register event watchers as long |
803 | ... queue jobs here, make sure they register event watchers as long |
774 | ... as they still have work to do (even an idle watcher will do..) |
804 | ... as they still have work to do (even an idle watcher will do..) |
775 | ev_loop (my_loop, 0); |
805 | ev_run (my_loop, 0); |
776 | ... jobs done or somebody called unloop. yeah! |
806 | ... jobs done or somebody called unloop. yeah! |
777 | |
807 | |
778 | =item ev_unloop (loop, how) |
808 | =item ev_break (loop, how) |
779 | |
809 | |
780 | Can be used to make a call to C<ev_loop> return early (but only after it |
810 | Can be used to make a call to C<ev_run> return early (but only after it |
781 | has processed all outstanding events). The C<how> argument must be either |
811 | has processed all outstanding events). The C<how> argument must be either |
782 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
812 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
783 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
813 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
784 | |
814 | |
785 | This "unloop state" will be cleared when entering C<ev_loop> again. |
815 | This "unloop state" will be cleared when entering C<ev_run> again. |
786 | |
816 | |
787 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
817 | It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO## |
788 | |
818 | |
789 | =item ev_ref (loop) |
819 | =item ev_ref (loop) |
790 | |
820 | |
791 | =item ev_unref (loop) |
821 | =item ev_unref (loop) |
792 | |
822 | |
793 | Ref/unref can be used to add or remove a reference count on the event |
823 | Ref/unref can be used to add or remove a reference count on the event |
794 | loop: Every watcher keeps one reference, and as long as the reference |
824 | loop: Every watcher keeps one reference, and as long as the reference |
795 | count is nonzero, C<ev_loop> will not return on its own. |
825 | count is nonzero, C<ev_run> will not return on its own. |
796 | |
826 | |
797 | This is useful when you have a watcher that you never intend to |
827 | This is useful when you have a watcher that you never intend to |
798 | unregister, but that nevertheless should not keep C<ev_loop> from |
828 | unregister, but that nevertheless should not keep C<ev_run> from |
799 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
829 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
800 | before stopping it. |
830 | before stopping it. |
801 | |
831 | |
802 | As an example, libev itself uses this for its internal signal pipe: It |
832 | As an example, libev itself uses this for its internal signal pipe: It |
803 | is not visible to the libev user and should not keep C<ev_loop> from |
833 | is not visible to the libev user and should not keep C<ev_run> from |
804 | exiting if no event watchers registered by it are active. It is also an |
834 | exiting if no event watchers registered by it are active. It is also an |
805 | excellent way to do this for generic recurring timers or from within |
835 | excellent way to do this for generic recurring timers or from within |
806 | third-party libraries. Just remember to I<unref after start> and I<ref |
836 | third-party libraries. Just remember to I<unref after start> and I<ref |
807 | before stop> (but only if the watcher wasn't active before, or was active |
837 | before stop> (but only if the watcher wasn't active before, or was active |
808 | before, respectively. Note also that libev might stop watchers itself |
838 | before, respectively. Note also that libev might stop watchers itself |
809 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
839 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
810 | in the callback). |
840 | in the callback). |
811 | |
841 | |
812 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
842 | Example: Create a signal watcher, but keep it from keeping C<ev_run> |
813 | running when nothing else is active. |
843 | running when nothing else is active. |
814 | |
844 | |
815 | ev_signal exitsig; |
845 | ev_signal exitsig; |
816 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
846 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
817 | ev_signal_start (loop, &exitsig); |
847 | ev_signal_start (loop, &exitsig); |
… | |
… | |
862 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
892 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
863 | as this approaches the timing granularity of most systems. Note that if |
893 | as this approaches the timing granularity of most systems. Note that if |
864 | you do transactions with the outside world and you can't increase the |
894 | you do transactions with the outside world and you can't increase the |
865 | parallelity, then this setting will limit your transaction rate (if you |
895 | parallelity, then this setting will limit your transaction rate (if you |
866 | need to poll once per transaction and the I/O collect interval is 0.01, |
896 | need to poll once per transaction and the I/O collect interval is 0.01, |
867 | then you can't do more than 100 transations per second). |
897 | then you can't do more than 100 transactions per second). |
868 | |
898 | |
869 | Setting the I<timeout collect interval> can improve the opportunity for |
899 | Setting the I<timeout collect interval> can improve the opportunity for |
870 | saving power, as the program will "bundle" timer callback invocations that |
900 | saving power, as the program will "bundle" timer callback invocations that |
871 | are "near" in time together, by delaying some, thus reducing the number of |
901 | are "near" in time together, by delaying some, thus reducing the number of |
872 | times the process sleeps and wakes up again. Another useful technique to |
902 | times the process sleeps and wakes up again. Another useful technique to |
… | |
… | |
880 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
910 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
881 | |
911 | |
882 | =item ev_invoke_pending (loop) |
912 | =item ev_invoke_pending (loop) |
883 | |
913 | |
884 | This call will simply invoke all pending watchers while resetting their |
914 | This call will simply invoke all pending watchers while resetting their |
885 | pending state. Normally, C<ev_loop> does this automatically when required, |
915 | pending state. Normally, C<ev_run> does this automatically when required, |
886 | but when overriding the invoke callback this call comes handy. |
916 | but when overriding the invoke callback this call comes handy. This |
|
|
917 | function can be invoked from a watcher - this can be useful for example |
|
|
918 | when you want to do some lengthy calculation and want to pass further |
|
|
919 | event handling to another thread (you still have to make sure only one |
|
|
920 | thread executes within C<ev_invoke_pending> or C<ev_run> of course). |
887 | |
921 | |
888 | =item int ev_pending_count (loop) |
922 | =item int ev_pending_count (loop) |
889 | |
923 | |
890 | Returns the number of pending watchers - zero indicates that no watchers |
924 | Returns the number of pending watchers - zero indicates that no watchers |
891 | are pending. |
925 | are pending. |
892 | |
926 | |
893 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
927 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
894 | |
928 | |
895 | This overrides the invoke pending functionality of the loop: Instead of |
929 | This overrides the invoke pending functionality of the loop: Instead of |
896 | invoking all pending watchers when there are any, C<ev_loop> will call |
930 | invoking all pending watchers when there are any, C<ev_run> will call |
897 | this callback instead. This is useful, for example, when you want to |
931 | this callback instead. This is useful, for example, when you want to |
898 | invoke the actual watchers inside another context (another thread etc.). |
932 | invoke the actual watchers inside another context (another thread etc.). |
899 | |
933 | |
900 | If you want to reset the callback, use C<ev_invoke_pending> as new |
934 | If you want to reset the callback, use C<ev_invoke_pending> as new |
901 | callback. |
935 | callback. |
… | |
… | |
904 | |
938 | |
905 | Sometimes you want to share the same loop between multiple threads. This |
939 | Sometimes you want to share the same loop between multiple threads. This |
906 | can be done relatively simply by putting mutex_lock/unlock calls around |
940 | can be done relatively simply by putting mutex_lock/unlock calls around |
907 | each call to a libev function. |
941 | each call to a libev function. |
908 | |
942 | |
909 | However, C<ev_loop> can run an indefinite time, so it is not feasible to |
943 | However, C<ev_run> can run an indefinite time, so it is not feasible |
910 | wait for it to return. One way around this is to wake up the loop via |
944 | to wait for it to return. One way around this is to wake up the event |
911 | C<ev_unloop> and C<av_async_send>, another way is to set these I<release> |
945 | loop via C<ev_break> and C<av_async_send>, another way is to set these |
912 | and I<acquire> callbacks on the loop. |
946 | I<release> and I<acquire> callbacks on the loop. |
913 | |
947 | |
914 | When set, then C<release> will be called just before the thread is |
948 | When set, then C<release> will be called just before the thread is |
915 | suspended waiting for new events, and C<acquire> is called just |
949 | suspended waiting for new events, and C<acquire> is called just |
916 | afterwards. |
950 | afterwards. |
917 | |
951 | |
… | |
… | |
920 | |
954 | |
921 | While event loop modifications are allowed between invocations of |
955 | While event loop modifications are allowed between invocations of |
922 | C<release> and C<acquire> (that's their only purpose after all), no |
956 | C<release> and C<acquire> (that's their only purpose after all), no |
923 | modifications done will affect the event loop, i.e. adding watchers will |
957 | modifications done will affect the event loop, i.e. adding watchers will |
924 | have no effect on the set of file descriptors being watched, or the time |
958 | have no effect on the set of file descriptors being watched, or the time |
925 | waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it |
959 | waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it |
926 | to take note of any changes you made. |
960 | to take note of any changes you made. |
927 | |
961 | |
928 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
962 | In theory, threads executing C<ev_run> will be async-cancel safe between |
929 | invocations of C<release> and C<acquire>. |
963 | invocations of C<release> and C<acquire>. |
930 | |
964 | |
931 | See also the locking example in the C<THREADS> section later in this |
965 | See also the locking example in the C<THREADS> section later in this |
932 | document. |
966 | document. |
933 | |
967 | |
… | |
… | |
942 | These two functions can be used to associate arbitrary data with a loop, |
976 | These two functions can be used to associate arbitrary data with a loop, |
943 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
977 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
944 | C<acquire> callbacks described above, but of course can be (ab-)used for |
978 | C<acquire> callbacks described above, but of course can be (ab-)used for |
945 | any other purpose as well. |
979 | any other purpose as well. |
946 | |
980 | |
947 | =item ev_loop_verify (loop) |
981 | =item ev_verify (loop) |
948 | |
982 | |
949 | This function only does something when C<EV_VERIFY> support has been |
983 | This function only does something when C<EV_VERIFY> support has been |
950 | compiled in, which is the default for non-minimal builds. It tries to go |
984 | compiled in, which is the default for non-minimal builds. It tries to go |
951 | through all internal structures and checks them for validity. If anything |
985 | through all internal structures and checks them for validity. If anything |
952 | is found to be inconsistent, it will print an error message to standard |
986 | is found to be inconsistent, it will print an error message to standard |
… | |
… | |
963 | |
997 | |
964 | In the following description, uppercase C<TYPE> in names stands for the |
998 | In the following description, uppercase C<TYPE> in names stands for the |
965 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
999 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
966 | watchers and C<ev_io_start> for I/O watchers. |
1000 | watchers and C<ev_io_start> for I/O watchers. |
967 | |
1001 | |
968 | A watcher is a structure that you create and register to record your |
1002 | A watcher is an opaque structure that you allocate and register to record |
969 | interest in some event. For instance, if you want to wait for STDIN to |
1003 | your interest in some event. To make a concrete example, imagine you want |
970 | become readable, you would create an C<ev_io> watcher for that: |
1004 | to wait for STDIN to become readable, you would create an C<ev_io> watcher |
|
|
1005 | for that: |
971 | |
1006 | |
972 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
1007 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
973 | { |
1008 | { |
974 | ev_io_stop (w); |
1009 | ev_io_stop (w); |
975 | ev_unloop (loop, EVUNLOOP_ALL); |
1010 | ev_break (loop, EVBREAK_ALL); |
976 | } |
1011 | } |
977 | |
1012 | |
978 | struct ev_loop *loop = ev_default_loop (0); |
1013 | struct ev_loop *loop = ev_default_loop (0); |
979 | |
1014 | |
980 | ev_io stdin_watcher; |
1015 | ev_io stdin_watcher; |
981 | |
1016 | |
982 | ev_init (&stdin_watcher, my_cb); |
1017 | ev_init (&stdin_watcher, my_cb); |
983 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1018 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
984 | ev_io_start (loop, &stdin_watcher); |
1019 | ev_io_start (loop, &stdin_watcher); |
985 | |
1020 | |
986 | ev_loop (loop, 0); |
1021 | ev_run (loop, 0); |
987 | |
1022 | |
988 | As you can see, you are responsible for allocating the memory for your |
1023 | As you can see, you are responsible for allocating the memory for your |
989 | watcher structures (and it is I<usually> a bad idea to do this on the |
1024 | watcher structures (and it is I<usually> a bad idea to do this on the |
990 | stack). |
1025 | stack). |
991 | |
1026 | |
992 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
1027 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
993 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
1028 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
994 | |
1029 | |
995 | Each watcher structure must be initialised by a call to C<ev_init |
1030 | Each watcher structure must be initialised by a call to C<ev_init (watcher |
996 | (watcher *, callback)>, which expects a callback to be provided. This |
1031 | *, callback)>, which expects a callback to be provided. This callback is |
997 | callback gets invoked each time the event occurs (or, in the case of I/O |
1032 | invoked each time the event occurs (or, in the case of I/O watchers, each |
998 | watchers, each time the event loop detects that the file descriptor given |
1033 | time the event loop detects that the file descriptor given is readable |
999 | is readable and/or writable). |
1034 | and/or writable). |
1000 | |
1035 | |
1001 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
1036 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
1002 | macro to configure it, with arguments specific to the watcher type. There |
1037 | macro to configure it, with arguments specific to the watcher type. There |
1003 | is also a macro to combine initialisation and setting in one call: C<< |
1038 | is also a macro to combine initialisation and setting in one call: C<< |
1004 | ev_TYPE_init (watcher *, callback, ...) >>. |
1039 | ev_TYPE_init (watcher *, callback, ...) >>. |
… | |
… | |
1027 | =item C<EV_WRITE> |
1062 | =item C<EV_WRITE> |
1028 | |
1063 | |
1029 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1064 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1030 | writable. |
1065 | writable. |
1031 | |
1066 | |
1032 | =item C<EV_TIMEOUT> |
1067 | =item C<EV_TIMER> |
1033 | |
1068 | |
1034 | The C<ev_timer> watcher has timed out. |
1069 | The C<ev_timer> watcher has timed out. |
1035 | |
1070 | |
1036 | =item C<EV_PERIODIC> |
1071 | =item C<EV_PERIODIC> |
1037 | |
1072 | |
… | |
… | |
1055 | |
1090 | |
1056 | =item C<EV_PREPARE> |
1091 | =item C<EV_PREPARE> |
1057 | |
1092 | |
1058 | =item C<EV_CHECK> |
1093 | =item C<EV_CHECK> |
1059 | |
1094 | |
1060 | All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts |
1095 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
1061 | to gather new events, and all C<ev_check> watchers are invoked just after |
1096 | to gather new events, and all C<ev_check> watchers are invoked just after |
1062 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
1097 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
1063 | received events. Callbacks of both watcher types can start and stop as |
1098 | received events. Callbacks of both watcher types can start and stop as |
1064 | many watchers as they want, and all of them will be taken into account |
1099 | many watchers as they want, and all of them will be taken into account |
1065 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1100 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1066 | C<ev_loop> from blocking). |
1101 | C<ev_run> from blocking). |
1067 | |
1102 | |
1068 | =item C<EV_EMBED> |
1103 | =item C<EV_EMBED> |
1069 | |
1104 | |
1070 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1105 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1071 | |
1106 | |
… | |
… | |
1099 | example it might indicate that a fd is readable or writable, and if your |
1134 | example it might indicate that a fd is readable or writable, and if your |
1100 | callbacks is well-written it can just attempt the operation and cope with |
1135 | callbacks is well-written it can just attempt the operation and cope with |
1101 | the error from read() or write(). This will not work in multi-threaded |
1136 | the error from read() or write(). This will not work in multi-threaded |
1102 | programs, though, as the fd could already be closed and reused for another |
1137 | programs, though, as the fd could already be closed and reused for another |
1103 | thing, so beware. |
1138 | thing, so beware. |
|
|
1139 | |
|
|
1140 | =back |
|
|
1141 | |
|
|
1142 | =head2 WATCHER STATES |
|
|
1143 | |
|
|
1144 | There are various watcher states mentioned throughout this manual - |
|
|
1145 | active, pending and so on. In this section these states and the rules to |
|
|
1146 | transition between them will be described in more detail - and while these |
|
|
1147 | rules might look complicated, they usually do "the right thing". |
|
|
1148 | |
|
|
1149 | =over 4 |
|
|
1150 | |
|
|
1151 | =item initialiased |
|
|
1152 | |
|
|
1153 | Before a watcher can be registered with the event looop it has to be |
|
|
1154 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1155 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
|
|
1156 | |
|
|
1157 | In this state it is simply some block of memory that is suitable for use |
|
|
1158 | in an event loop. It can be moved around, freed, reused etc. at will. |
|
|
1159 | |
|
|
1160 | =item started/running/active |
|
|
1161 | |
|
|
1162 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
|
|
1163 | property of the event loop, and is actively waiting for events. While in |
|
|
1164 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1165 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1166 | and call libev functions on it that are documented to work on active watchers. |
|
|
1167 | |
|
|
1168 | =item pending |
|
|
1169 | |
|
|
1170 | If a watcher is active and libev determines that an event it is interested |
|
|
1171 | in has occurred (such as a timer expiring), it will become pending. It will |
|
|
1172 | stay in this pending state until either it is stopped or its callback is |
|
|
1173 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1174 | callback. |
|
|
1175 | |
|
|
1176 | The watcher might or might not be active while it is pending (for example, |
|
|
1177 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1178 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1179 | but it is still property of the event loop at this time, so cannot be |
|
|
1180 | moved, freed or reused. And if it is active the rules described in the |
|
|
1181 | previous item still apply. |
|
|
1182 | |
|
|
1183 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1184 | via C<ev_feed_event>), in which case it becomes pending without being |
|
|
1185 | active. |
|
|
1186 | |
|
|
1187 | =item stopped |
|
|
1188 | |
|
|
1189 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1190 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
|
|
1191 | latter will clear any pending state the watcher might be in, regardless |
|
|
1192 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1193 | freeing it is often a good idea. |
|
|
1194 | |
|
|
1195 | While stopped (and not pending) the watcher is essentially in the |
|
|
1196 | initialised state, that is it can be reused, moved, modified in any way |
|
|
1197 | you wish. |
1104 | |
1198 | |
1105 | =back |
1199 | =back |
1106 | |
1200 | |
1107 | =head2 GENERIC WATCHER FUNCTIONS |
1201 | =head2 GENERIC WATCHER FUNCTIONS |
1108 | |
1202 | |
… | |
… | |
1370 | |
1464 | |
1371 | For example, to emulate how many other event libraries handle priorities, |
1465 | For example, to emulate how many other event libraries handle priorities, |
1372 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1466 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1373 | the normal watcher callback, you just start the idle watcher. The real |
1467 | the normal watcher callback, you just start the idle watcher. The real |
1374 | processing is done in the idle watcher callback. This causes libev to |
1468 | processing is done in the idle watcher callback. This causes libev to |
1375 | continously poll and process kernel event data for the watcher, but when |
1469 | continuously poll and process kernel event data for the watcher, but when |
1376 | the lock-out case is known to be rare (which in turn is rare :), this is |
1470 | the lock-out case is known to be rare (which in turn is rare :), this is |
1377 | workable. |
1471 | workable. |
1378 | |
1472 | |
1379 | Usually, however, the lock-out model implemented that way will perform |
1473 | Usually, however, the lock-out model implemented that way will perform |
1380 | miserably under the type of load it was designed to handle. In that case, |
1474 | miserably under the type of load it was designed to handle. In that case, |
… | |
… | |
1394 | { |
1488 | { |
1395 | // stop the I/O watcher, we received the event, but |
1489 | // stop the I/O watcher, we received the event, but |
1396 | // are not yet ready to handle it. |
1490 | // are not yet ready to handle it. |
1397 | ev_io_stop (EV_A_ w); |
1491 | ev_io_stop (EV_A_ w); |
1398 | |
1492 | |
1399 | // start the idle watcher to ahndle the actual event. |
1493 | // start the idle watcher to handle the actual event. |
1400 | // it will not be executed as long as other watchers |
1494 | // it will not be executed as long as other watchers |
1401 | // with the default priority are receiving events. |
1495 | // with the default priority are receiving events. |
1402 | ev_idle_start (EV_A_ &idle); |
1496 | ev_idle_start (EV_A_ &idle); |
1403 | } |
1497 | } |
1404 | |
1498 | |
… | |
… | |
1458 | |
1552 | |
1459 | If you cannot use non-blocking mode, then force the use of a |
1553 | If you cannot use non-blocking mode, then force the use of a |
1460 | known-to-be-good backend (at the time of this writing, this includes only |
1554 | known-to-be-good backend (at the time of this writing, this includes only |
1461 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1555 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1462 | descriptors for which non-blocking operation makes no sense (such as |
1556 | descriptors for which non-blocking operation makes no sense (such as |
1463 | files) - libev doesn't guarentee any specific behaviour in that case. |
1557 | files) - libev doesn't guarantee any specific behaviour in that case. |
1464 | |
1558 | |
1465 | Another thing you have to watch out for is that it is quite easy to |
1559 | Another thing you have to watch out for is that it is quite easy to |
1466 | receive "spurious" readiness notifications, that is your callback might |
1560 | receive "spurious" readiness notifications, that is your callback might |
1467 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1561 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1468 | because there is no data. Not only are some backends known to create a |
1562 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1533 | |
1627 | |
1534 | So when you encounter spurious, unexplained daemon exits, make sure you |
1628 | So when you encounter spurious, unexplained daemon exits, make sure you |
1535 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1629 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1536 | somewhere, as that would have given you a big clue). |
1630 | somewhere, as that would have given you a big clue). |
1537 | |
1631 | |
|
|
1632 | =head3 The special problem of accept()ing when you can't |
|
|
1633 | |
|
|
1634 | Many implementations of the POSIX C<accept> function (for example, |
|
|
1635 | found in post-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1636 | connection from the pending queue in all error cases. |
|
|
1637 | |
|
|
1638 | For example, larger servers often run out of file descriptors (because |
|
|
1639 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
|
|
1640 | rejecting the connection, leading to libev signalling readiness on |
|
|
1641 | the next iteration again (the connection still exists after all), and |
|
|
1642 | typically causing the program to loop at 100% CPU usage. |
|
|
1643 | |
|
|
1644 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1645 | operating systems, there is usually little the app can do to remedy the |
|
|
1646 | situation, and no known thread-safe method of removing the connection to |
|
|
1647 | cope with overload is known (to me). |
|
|
1648 | |
|
|
1649 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1650 | - when the program encounters an overload, it will just loop until the |
|
|
1651 | situation is over. While this is a form of busy waiting, no OS offers an |
|
|
1652 | event-based way to handle this situation, so it's the best one can do. |
|
|
1653 | |
|
|
1654 | A better way to handle the situation is to log any errors other than |
|
|
1655 | C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such |
|
|
1656 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1657 | what could be wrong ("raise the ulimit!"). For extra points one could stop |
|
|
1658 | the C<ev_io> watcher on the listening fd "for a while", which reduces CPU |
|
|
1659 | usage. |
|
|
1660 | |
|
|
1661 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1662 | descriptor for overload situations (e.g. by opening F</dev/null>), and |
|
|
1663 | when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>, |
|
|
1664 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1665 | clients under typical overload conditions. |
|
|
1666 | |
|
|
1667 | The last way to handle it is to simply log the error and C<exit>, as |
|
|
1668 | is often done with C<malloc> failures, but this results in an easy |
|
|
1669 | opportunity for a DoS attack. |
1538 | |
1670 | |
1539 | =head3 Watcher-Specific Functions |
1671 | =head3 Watcher-Specific Functions |
1540 | |
1672 | |
1541 | =over 4 |
1673 | =over 4 |
1542 | |
1674 | |
… | |
… | |
1574 | ... |
1706 | ... |
1575 | struct ev_loop *loop = ev_default_init (0); |
1707 | struct ev_loop *loop = ev_default_init (0); |
1576 | ev_io stdin_readable; |
1708 | ev_io stdin_readable; |
1577 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1709 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1578 | ev_io_start (loop, &stdin_readable); |
1710 | ev_io_start (loop, &stdin_readable); |
1579 | ev_loop (loop, 0); |
1711 | ev_run (loop, 0); |
1580 | |
1712 | |
1581 | |
1713 | |
1582 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1714 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1583 | |
1715 | |
1584 | Timer watchers are simple relative timers that generate an event after a |
1716 | Timer watchers are simple relative timers that generate an event after a |
… | |
… | |
1593 | The callback is guaranteed to be invoked only I<after> its timeout has |
1725 | The callback is guaranteed to be invoked only I<after> its timeout has |
1594 | passed (not I<at>, so on systems with very low-resolution clocks this |
1726 | passed (not I<at>, so on systems with very low-resolution clocks this |
1595 | might introduce a small delay). If multiple timers become ready during the |
1727 | might introduce a small delay). If multiple timers become ready during the |
1596 | same loop iteration then the ones with earlier time-out values are invoked |
1728 | same loop iteration then the ones with earlier time-out values are invoked |
1597 | before ones of the same priority with later time-out values (but this is |
1729 | before ones of the same priority with later time-out values (but this is |
1598 | no longer true when a callback calls C<ev_loop> recursively). |
1730 | no longer true when a callback calls C<ev_run> recursively). |
1599 | |
1731 | |
1600 | =head3 Be smart about timeouts |
1732 | =head3 Be smart about timeouts |
1601 | |
1733 | |
1602 | Many real-world problems involve some kind of timeout, usually for error |
1734 | Many real-world problems involve some kind of timeout, usually for error |
1603 | recovery. A typical example is an HTTP request - if the other side hangs, |
1735 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
1689 | ev_tstamp timeout = last_activity + 60.; |
1821 | ev_tstamp timeout = last_activity + 60.; |
1690 | |
1822 | |
1691 | // if last_activity + 60. is older than now, we did time out |
1823 | // if last_activity + 60. is older than now, we did time out |
1692 | if (timeout < now) |
1824 | if (timeout < now) |
1693 | { |
1825 | { |
1694 | // timeout occured, take action |
1826 | // timeout occurred, take action |
1695 | } |
1827 | } |
1696 | else |
1828 | else |
1697 | { |
1829 | { |
1698 | // callback was invoked, but there was some activity, re-arm |
1830 | // callback was invoked, but there was some activity, re-arm |
1699 | // the watcher to fire in last_activity + 60, which is |
1831 | // the watcher to fire in last_activity + 60, which is |
… | |
… | |
1721 | to the current time (meaning we just have some activity :), then call the |
1853 | to the current time (meaning we just have some activity :), then call the |
1722 | callback, which will "do the right thing" and start the timer: |
1854 | callback, which will "do the right thing" and start the timer: |
1723 | |
1855 | |
1724 | ev_init (timer, callback); |
1856 | ev_init (timer, callback); |
1725 | last_activity = ev_now (loop); |
1857 | last_activity = ev_now (loop); |
1726 | callback (loop, timer, EV_TIMEOUT); |
1858 | callback (loop, timer, EV_TIMER); |
1727 | |
1859 | |
1728 | And when there is some activity, simply store the current time in |
1860 | And when there is some activity, simply store the current time in |
1729 | C<last_activity>, no libev calls at all: |
1861 | C<last_activity>, no libev calls at all: |
1730 | |
1862 | |
1731 | last_actiivty = ev_now (loop); |
1863 | last_activity = ev_now (loop); |
1732 | |
1864 | |
1733 | This technique is slightly more complex, but in most cases where the |
1865 | This technique is slightly more complex, but in most cases where the |
1734 | time-out is unlikely to be triggered, much more efficient. |
1866 | time-out is unlikely to be triggered, much more efficient. |
1735 | |
1867 | |
1736 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
1868 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
… | |
… | |
1774 | |
1906 | |
1775 | =head3 The special problem of time updates |
1907 | =head3 The special problem of time updates |
1776 | |
1908 | |
1777 | Establishing the current time is a costly operation (it usually takes at |
1909 | Establishing the current time is a costly operation (it usually takes at |
1778 | least two system calls): EV therefore updates its idea of the current |
1910 | least two system calls): EV therefore updates its idea of the current |
1779 | time only before and after C<ev_loop> collects new events, which causes a |
1911 | time only before and after C<ev_run> collects new events, which causes a |
1780 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1912 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1781 | lots of events in one iteration. |
1913 | lots of events in one iteration. |
1782 | |
1914 | |
1783 | The relative timeouts are calculated relative to the C<ev_now ()> |
1915 | The relative timeouts are calculated relative to the C<ev_now ()> |
1784 | time. This is usually the right thing as this timestamp refers to the time |
1916 | time. This is usually the right thing as this timestamp refers to the time |
… | |
… | |
1862 | Returns the remaining time until a timer fires. If the timer is active, |
1994 | Returns the remaining time until a timer fires. If the timer is active, |
1863 | then this time is relative to the current event loop time, otherwise it's |
1995 | then this time is relative to the current event loop time, otherwise it's |
1864 | the timeout value currently configured. |
1996 | the timeout value currently configured. |
1865 | |
1997 | |
1866 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
1998 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
1867 | C<5>. When the timer is started and one second passes, C<ev_timer_remain> |
1999 | C<5>. When the timer is started and one second passes, C<ev_timer_remaining> |
1868 | will return C<4>. When the timer expires and is restarted, it will return |
2000 | will return C<4>. When the timer expires and is restarted, it will return |
1869 | roughly C<7> (likely slightly less as callback invocation takes some time, |
2001 | roughly C<7> (likely slightly less as callback invocation takes some time, |
1870 | too), and so on. |
2002 | too), and so on. |
1871 | |
2003 | |
1872 | =item ev_tstamp repeat [read-write] |
2004 | =item ev_tstamp repeat [read-write] |
… | |
… | |
1901 | } |
2033 | } |
1902 | |
2034 | |
1903 | ev_timer mytimer; |
2035 | ev_timer mytimer; |
1904 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2036 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1905 | ev_timer_again (&mytimer); /* start timer */ |
2037 | ev_timer_again (&mytimer); /* start timer */ |
1906 | ev_loop (loop, 0); |
2038 | ev_run (loop, 0); |
1907 | |
2039 | |
1908 | // and in some piece of code that gets executed on any "activity": |
2040 | // and in some piece of code that gets executed on any "activity": |
1909 | // reset the timeout to start ticking again at 10 seconds |
2041 | // reset the timeout to start ticking again at 10 seconds |
1910 | ev_timer_again (&mytimer); |
2042 | ev_timer_again (&mytimer); |
1911 | |
2043 | |
… | |
… | |
1937 | |
2069 | |
1938 | As with timers, the callback is guaranteed to be invoked only when the |
2070 | As with timers, the callback is guaranteed to be invoked only when the |
1939 | point in time where it is supposed to trigger has passed. If multiple |
2071 | point in time where it is supposed to trigger has passed. If multiple |
1940 | timers become ready during the same loop iteration then the ones with |
2072 | timers become ready during the same loop iteration then the ones with |
1941 | earlier time-out values are invoked before ones with later time-out values |
2073 | earlier time-out values are invoked before ones with later time-out values |
1942 | (but this is no longer true when a callback calls C<ev_loop> recursively). |
2074 | (but this is no longer true when a callback calls C<ev_run> recursively). |
1943 | |
2075 | |
1944 | =head3 Watcher-Specific Functions and Data Members |
2076 | =head3 Watcher-Specific Functions and Data Members |
1945 | |
2077 | |
1946 | =over 4 |
2078 | =over 4 |
1947 | |
2079 | |
… | |
… | |
2075 | Example: Call a callback every hour, or, more precisely, whenever the |
2207 | Example: Call a callback every hour, or, more precisely, whenever the |
2076 | system time is divisible by 3600. The callback invocation times have |
2208 | system time is divisible by 3600. The callback invocation times have |
2077 | potentially a lot of jitter, but good long-term stability. |
2209 | potentially a lot of jitter, but good long-term stability. |
2078 | |
2210 | |
2079 | static void |
2211 | static void |
2080 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2212 | clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
2081 | { |
2213 | { |
2082 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2214 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2083 | } |
2215 | } |
2084 | |
2216 | |
2085 | ev_periodic hourly_tick; |
2217 | ev_periodic hourly_tick; |
… | |
… | |
2132 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2264 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2133 | not be unduly interrupted. If you have a problem with system calls getting |
2265 | not be unduly interrupted. If you have a problem with system calls getting |
2134 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2266 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2135 | and unblock them in an C<ev_prepare> watcher. |
2267 | and unblock them in an C<ev_prepare> watcher. |
2136 | |
2268 | |
2137 | =head3 The special problem of inheritance over execve |
2269 | =head3 The special problem of inheritance over fork/execve/pthread_create |
2138 | |
2270 | |
2139 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2271 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2140 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2272 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2141 | stopping it again), that is, libev might or might not block the signal, |
2273 | stopping it again), that is, libev might or might not block the signal, |
2142 | and might or might not set or restore the installed signal handler. |
2274 | and might or might not set or restore the installed signal handler. |
… | |
… | |
2152 | |
2284 | |
2153 | The simplest way to ensure that the signal mask is reset in the child is |
2285 | The simplest way to ensure that the signal mask is reset in the child is |
2154 | to install a fork handler with C<pthread_atfork> that resets it. That will |
2286 | to install a fork handler with C<pthread_atfork> that resets it. That will |
2155 | catch fork calls done by libraries (such as the libc) as well. |
2287 | catch fork calls done by libraries (such as the libc) as well. |
2156 | |
2288 | |
2157 | In current versions of libev, you can also ensure that the signal mask is |
2289 | In current versions of libev, the signal will not be blocked indefinitely |
2158 | not blocking any signals (except temporarily, so thread users watch out) |
2290 | unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces |
2159 | by specifying the C<EVFLAG_NOSIGFD> when creating the event loop. This |
2291 | the window of opportunity for problems, it will not go away, as libev |
2160 | is not guaranteed for future versions, however. |
2292 | I<has> to modify the signal mask, at least temporarily. |
|
|
2293 | |
|
|
2294 | So I can't stress this enough: I<If you do not reset your signal mask when |
|
|
2295 | you expect it to be empty, you have a race condition in your code>. This |
|
|
2296 | is not a libev-specific thing, this is true for most event libraries. |
2161 | |
2297 | |
2162 | =head3 Watcher-Specific Functions and Data Members |
2298 | =head3 Watcher-Specific Functions and Data Members |
2163 | |
2299 | |
2164 | =over 4 |
2300 | =over 4 |
2165 | |
2301 | |
… | |
… | |
2181 | Example: Try to exit cleanly on SIGINT. |
2317 | Example: Try to exit cleanly on SIGINT. |
2182 | |
2318 | |
2183 | static void |
2319 | static void |
2184 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2320 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2185 | { |
2321 | { |
2186 | ev_unloop (loop, EVUNLOOP_ALL); |
2322 | ev_break (loop, EVBREAK_ALL); |
2187 | } |
2323 | } |
2188 | |
2324 | |
2189 | ev_signal signal_watcher; |
2325 | ev_signal signal_watcher; |
2190 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2326 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2191 | ev_signal_start (loop, &signal_watcher); |
2327 | ev_signal_start (loop, &signal_watcher); |
… | |
… | |
2577 | |
2713 | |
2578 | Prepare and check watchers are usually (but not always) used in pairs: |
2714 | Prepare and check watchers are usually (but not always) used in pairs: |
2579 | prepare watchers get invoked before the process blocks and check watchers |
2715 | prepare watchers get invoked before the process blocks and check watchers |
2580 | afterwards. |
2716 | afterwards. |
2581 | |
2717 | |
2582 | You I<must not> call C<ev_loop> or similar functions that enter |
2718 | You I<must not> call C<ev_run> or similar functions that enter |
2583 | the current event loop from either C<ev_prepare> or C<ev_check> |
2719 | the current event loop from either C<ev_prepare> or C<ev_check> |
2584 | watchers. Other loops than the current one are fine, however. The |
2720 | watchers. Other loops than the current one are fine, however. The |
2585 | rationale behind this is that you do not need to check for recursion in |
2721 | rationale behind this is that you do not need to check for recursion in |
2586 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2722 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2587 | C<ev_check> so if you have one watcher of each kind they will always be |
2723 | C<ev_check> so if you have one watcher of each kind they will always be |
… | |
… | |
2755 | |
2891 | |
2756 | if (timeout >= 0) |
2892 | if (timeout >= 0) |
2757 | // create/start timer |
2893 | // create/start timer |
2758 | |
2894 | |
2759 | // poll |
2895 | // poll |
2760 | ev_loop (EV_A_ 0); |
2896 | ev_run (EV_A_ 0); |
2761 | |
2897 | |
2762 | // stop timer again |
2898 | // stop timer again |
2763 | if (timeout >= 0) |
2899 | if (timeout >= 0) |
2764 | ev_timer_stop (EV_A_ &to); |
2900 | ev_timer_stop (EV_A_ &to); |
2765 | |
2901 | |
… | |
… | |
2843 | if you do not want that, you need to temporarily stop the embed watcher). |
2979 | if you do not want that, you need to temporarily stop the embed watcher). |
2844 | |
2980 | |
2845 | =item ev_embed_sweep (loop, ev_embed *) |
2981 | =item ev_embed_sweep (loop, ev_embed *) |
2846 | |
2982 | |
2847 | Make a single, non-blocking sweep over the embedded loop. This works |
2983 | Make a single, non-blocking sweep over the embedded loop. This works |
2848 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
2984 | similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most |
2849 | appropriate way for embedded loops. |
2985 | appropriate way for embedded loops. |
2850 | |
2986 | |
2851 | =item struct ev_loop *other [read-only] |
2987 | =item struct ev_loop *other [read-only] |
2852 | |
2988 | |
2853 | The embedded event loop. |
2989 | The embedded event loop. |
… | |
… | |
2913 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3049 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2914 | handlers will be invoked, too, of course. |
3050 | handlers will be invoked, too, of course. |
2915 | |
3051 | |
2916 | =head3 The special problem of life after fork - how is it possible? |
3052 | =head3 The special problem of life after fork - how is it possible? |
2917 | |
3053 | |
2918 | Most uses of C<fork()> consist of forking, then some simple calls to ste |
3054 | Most uses of C<fork()> consist of forking, then some simple calls to set |
2919 | up/change the process environment, followed by a call to C<exec()>. This |
3055 | up/change the process environment, followed by a call to C<exec()>. This |
2920 | sequence should be handled by libev without any problems. |
3056 | sequence should be handled by libev without any problems. |
2921 | |
3057 | |
2922 | This changes when the application actually wants to do event handling |
3058 | This changes when the application actually wants to do event handling |
2923 | in the child, or both parent in child, in effect "continuing" after the |
3059 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
2957 | believe me. |
3093 | believe me. |
2958 | |
3094 | |
2959 | =back |
3095 | =back |
2960 | |
3096 | |
2961 | |
3097 | |
2962 | =head2 C<ev_async> - how to wake up another event loop |
3098 | =head2 C<ev_async> - how to wake up an event loop |
2963 | |
3099 | |
2964 | In general, you cannot use an C<ev_loop> from multiple threads or other |
3100 | In general, you cannot use an C<ev_run> from multiple threads or other |
2965 | asynchronous sources such as signal handlers (as opposed to multiple event |
3101 | asynchronous sources such as signal handlers (as opposed to multiple event |
2966 | loops - those are of course safe to use in different threads). |
3102 | loops - those are of course safe to use in different threads). |
2967 | |
3103 | |
2968 | Sometimes, however, you need to wake up another event loop you do not |
3104 | Sometimes, however, you need to wake up an event loop you do not control, |
2969 | control, for example because it belongs to another thread. This is what |
3105 | for example because it belongs to another thread. This is what C<ev_async> |
2970 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
3106 | watchers do: as long as the C<ev_async> watcher is active, you can signal |
2971 | can signal it by calling C<ev_async_send>, which is thread- and signal |
3107 | it by calling C<ev_async_send>, which is thread- and signal safe. |
2972 | safe. |
|
|
2973 | |
3108 | |
2974 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3109 | This functionality is very similar to C<ev_signal> watchers, as signals, |
2975 | too, are asynchronous in nature, and signals, too, will be compressed |
3110 | too, are asynchronous in nature, and signals, too, will be compressed |
2976 | (i.e. the number of callback invocations may be less than the number of |
3111 | (i.e. the number of callback invocations may be less than the number of |
2977 | C<ev_async_sent> calls). |
3112 | C<ev_async_sent> calls). |
… | |
… | |
3132 | |
3267 | |
3133 | If C<timeout> is less than 0, then no timeout watcher will be |
3268 | If C<timeout> is less than 0, then no timeout watcher will be |
3134 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3269 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3135 | repeat = 0) will be started. C<0> is a valid timeout. |
3270 | repeat = 0) will be started. C<0> is a valid timeout. |
3136 | |
3271 | |
3137 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
3272 | The callback has the type C<void (*cb)(int revents, void *arg)> and is |
3138 | passed an C<revents> set like normal event callbacks (a combination of |
3273 | passed an C<revents> set like normal event callbacks (a combination of |
3139 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
3274 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg> |
3140 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3275 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3141 | a timeout and an io event at the same time - you probably should give io |
3276 | a timeout and an io event at the same time - you probably should give io |
3142 | events precedence. |
3277 | events precedence. |
3143 | |
3278 | |
3144 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3279 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3145 | |
3280 | |
3146 | static void stdin_ready (int revents, void *arg) |
3281 | static void stdin_ready (int revents, void *arg) |
3147 | { |
3282 | { |
3148 | if (revents & EV_READ) |
3283 | if (revents & EV_READ) |
3149 | /* stdin might have data for us, joy! */; |
3284 | /* stdin might have data for us, joy! */; |
3150 | else if (revents & EV_TIMEOUT) |
3285 | else if (revents & EV_TIMER) |
3151 | /* doh, nothing entered */; |
3286 | /* doh, nothing entered */; |
3152 | } |
3287 | } |
3153 | |
3288 | |
3154 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3289 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3155 | |
3290 | |
… | |
… | |
3289 | myclass obj; |
3424 | myclass obj; |
3290 | ev::io iow; |
3425 | ev::io iow; |
3291 | iow.set <myclass, &myclass::io_cb> (&obj); |
3426 | iow.set <myclass, &myclass::io_cb> (&obj); |
3292 | |
3427 | |
3293 | =item w->set (object *) |
3428 | =item w->set (object *) |
3294 | |
|
|
3295 | This is an B<experimental> feature that might go away in a future version. |
|
|
3296 | |
3429 | |
3297 | This is a variation of a method callback - leaving out the method to call |
3430 | This is a variation of a method callback - leaving out the method to call |
3298 | will default the method to C<operator ()>, which makes it possible to use |
3431 | will default the method to C<operator ()>, which makes it possible to use |
3299 | functor objects without having to manually specify the C<operator ()> all |
3432 | functor objects without having to manually specify the C<operator ()> all |
3300 | the time. Incidentally, you can then also leave out the template argument |
3433 | the time. Incidentally, you can then also leave out the template argument |
… | |
… | |
3340 | Associates a different C<struct ev_loop> with this watcher. You can only |
3473 | Associates a different C<struct ev_loop> with this watcher. You can only |
3341 | do this when the watcher is inactive (and not pending either). |
3474 | do this when the watcher is inactive (and not pending either). |
3342 | |
3475 | |
3343 | =item w->set ([arguments]) |
3476 | =item w->set ([arguments]) |
3344 | |
3477 | |
3345 | Basically the same as C<ev_TYPE_set>, with the same arguments. Must be |
3478 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
3346 | called at least once. Unlike the C counterpart, an active watcher gets |
3479 | method or a suitable start method must be called at least once. Unlike the |
3347 | automatically stopped and restarted when reconfiguring it with this |
3480 | C counterpart, an active watcher gets automatically stopped and restarted |
3348 | method. |
3481 | when reconfiguring it with this method. |
3349 | |
3482 | |
3350 | =item w->start () |
3483 | =item w->start () |
3351 | |
3484 | |
3352 | Starts the watcher. Note that there is no C<loop> argument, as the |
3485 | Starts the watcher. Note that there is no C<loop> argument, as the |
3353 | constructor already stores the event loop. |
3486 | constructor already stores the event loop. |
3354 | |
3487 | |
|
|
3488 | =item w->start ([arguments]) |
|
|
3489 | |
|
|
3490 | Instead of calling C<set> and C<start> methods separately, it is often |
|
|
3491 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
3492 | the configure C<set> method of the watcher. |
|
|
3493 | |
3355 | =item w->stop () |
3494 | =item w->stop () |
3356 | |
3495 | |
3357 | Stops the watcher if it is active. Again, no C<loop> argument. |
3496 | Stops the watcher if it is active. Again, no C<loop> argument. |
3358 | |
3497 | |
3359 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
3498 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
… | |
… | |
3371 | |
3510 | |
3372 | =back |
3511 | =back |
3373 | |
3512 | |
3374 | =back |
3513 | =back |
3375 | |
3514 | |
3376 | Example: Define a class with an IO and idle watcher, start one of them in |
3515 | Example: Define a class with two I/O and idle watchers, start the I/O |
3377 | the constructor. |
3516 | watchers in the constructor. |
3378 | |
3517 | |
3379 | class myclass |
3518 | class myclass |
3380 | { |
3519 | { |
3381 | ev::io io ; void io_cb (ev::io &w, int revents); |
3520 | ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
3521 | ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
3382 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3522 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3383 | |
3523 | |
3384 | myclass (int fd) |
3524 | myclass (int fd) |
3385 | { |
3525 | { |
3386 | io .set <myclass, &myclass::io_cb > (this); |
3526 | io .set <myclass, &myclass::io_cb > (this); |
|
|
3527 | io2 .set <myclass, &myclass::io2_cb > (this); |
3387 | idle.set <myclass, &myclass::idle_cb> (this); |
3528 | idle.set <myclass, &myclass::idle_cb> (this); |
3388 | |
3529 | |
3389 | io.start (fd, ev::READ); |
3530 | io.set (fd, ev::WRITE); // configure the watcher |
|
|
3531 | io.start (); // start it whenever convenient |
|
|
3532 | |
|
|
3533 | io2.start (fd, ev::READ); // set + start in one call |
3390 | } |
3534 | } |
3391 | }; |
3535 | }; |
3392 | |
3536 | |
3393 | |
3537 | |
3394 | =head1 OTHER LANGUAGE BINDINGS |
3538 | =head1 OTHER LANGUAGE BINDINGS |
… | |
… | |
3442 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3586 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3443 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3587 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3444 | |
3588 | |
3445 | =item Lua |
3589 | =item Lua |
3446 | |
3590 | |
3447 | Brian Maher has written a partial interface to libev |
3591 | Brian Maher has written a partial interface to libev for lua (at the |
3448 | for lua (only C<ev_io> and C<ev_timer>), to be found at |
3592 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
3449 | L<http://github.com/brimworks/lua-ev>. |
3593 | L<http://github.com/brimworks/lua-ev>. |
3450 | |
3594 | |
3451 | =back |
3595 | =back |
3452 | |
3596 | |
3453 | |
3597 | |
… | |
… | |
3468 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3612 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3469 | C<EV_A_> is used when other arguments are following. Example: |
3613 | C<EV_A_> is used when other arguments are following. Example: |
3470 | |
3614 | |
3471 | ev_unref (EV_A); |
3615 | ev_unref (EV_A); |
3472 | ev_timer_add (EV_A_ watcher); |
3616 | ev_timer_add (EV_A_ watcher); |
3473 | ev_loop (EV_A_ 0); |
3617 | ev_run (EV_A_ 0); |
3474 | |
3618 | |
3475 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3619 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3476 | which is often provided by the following macro. |
3620 | which is often provided by the following macro. |
3477 | |
3621 | |
3478 | =item C<EV_P>, C<EV_P_> |
3622 | =item C<EV_P>, C<EV_P_> |
… | |
… | |
3518 | } |
3662 | } |
3519 | |
3663 | |
3520 | ev_check check; |
3664 | ev_check check; |
3521 | ev_check_init (&check, check_cb); |
3665 | ev_check_init (&check, check_cb); |
3522 | ev_check_start (EV_DEFAULT_ &check); |
3666 | ev_check_start (EV_DEFAULT_ &check); |
3523 | ev_loop (EV_DEFAULT_ 0); |
3667 | ev_run (EV_DEFAULT_ 0); |
3524 | |
3668 | |
3525 | =head1 EMBEDDING |
3669 | =head1 EMBEDDING |
3526 | |
3670 | |
3527 | Libev can (and often is) directly embedded into host |
3671 | Libev can (and often is) directly embedded into host |
3528 | applications. Examples of applications that embed it include the Deliantra |
3672 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3608 | libev.m4 |
3752 | libev.m4 |
3609 | |
3753 | |
3610 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3754 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3611 | |
3755 | |
3612 | Libev can be configured via a variety of preprocessor symbols you have to |
3756 | Libev can be configured via a variety of preprocessor symbols you have to |
3613 | define before including any of its files. The default in the absence of |
3757 | define before including (or compiling) any of its files. The default in |
3614 | autoconf is documented for every option. |
3758 | the absence of autoconf is documented for every option. |
|
|
3759 | |
|
|
3760 | Symbols marked with "(h)" do not change the ABI, and can have different |
|
|
3761 | values when compiling libev vs. including F<ev.h>, so it is permissible |
|
|
3762 | to redefine them before including F<ev.h> without breaking compatibility |
|
|
3763 | to a compiled library. All other symbols change the ABI, which means all |
|
|
3764 | users of libev and the libev code itself must be compiled with compatible |
|
|
3765 | settings. |
3615 | |
3766 | |
3616 | =over 4 |
3767 | =over 4 |
3617 | |
3768 | |
|
|
3769 | =item EV_COMPAT3 (h) |
|
|
3770 | |
|
|
3771 | Backwards compatibility is a major concern for libev. This is why this |
|
|
3772 | release of libev comes with wrappers for the functions and symbols that |
|
|
3773 | have been renamed between libev version 3 and 4. |
|
|
3774 | |
|
|
3775 | You can disable these wrappers (to test compatibility with future |
|
|
3776 | versions) by defining C<EV_COMPAT3> to C<0> when compiling your |
|
|
3777 | sources. This has the additional advantage that you can drop the C<struct> |
|
|
3778 | from C<struct ev_loop> declarations, as libev will provide an C<ev_loop> |
|
|
3779 | typedef in that case. |
|
|
3780 | |
|
|
3781 | In some future version, the default for C<EV_COMPAT3> will become C<0>, |
|
|
3782 | and in some even more future version the compatibility code will be |
|
|
3783 | removed completely. |
|
|
3784 | |
3618 | =item EV_STANDALONE |
3785 | =item EV_STANDALONE (h) |
3619 | |
3786 | |
3620 | Must always be C<1> if you do not use autoconf configuration, which |
3787 | Must always be C<1> if you do not use autoconf configuration, which |
3621 | keeps libev from including F<config.h>, and it also defines dummy |
3788 | keeps libev from including F<config.h>, and it also defines dummy |
3622 | implementations for some libevent functions (such as logging, which is not |
3789 | implementations for some libevent functions (such as logging, which is not |
3623 | supported). It will also not define any of the structs usually found in |
3790 | supported). It will also not define any of the structs usually found in |
… | |
… | |
3773 | as well as for signal and thread safety in C<ev_async> watchers. |
3940 | as well as for signal and thread safety in C<ev_async> watchers. |
3774 | |
3941 | |
3775 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3942 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3776 | (from F<signal.h>), which is usually good enough on most platforms. |
3943 | (from F<signal.h>), which is usually good enough on most platforms. |
3777 | |
3944 | |
3778 | =item EV_H |
3945 | =item EV_H (h) |
3779 | |
3946 | |
3780 | The name of the F<ev.h> header file used to include it. The default if |
3947 | The name of the F<ev.h> header file used to include it. The default if |
3781 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3948 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3782 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3949 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3783 | |
3950 | |
3784 | =item EV_CONFIG_H |
3951 | =item EV_CONFIG_H (h) |
3785 | |
3952 | |
3786 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3953 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3787 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3954 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3788 | C<EV_H>, above. |
3955 | C<EV_H>, above. |
3789 | |
3956 | |
3790 | =item EV_EVENT_H |
3957 | =item EV_EVENT_H (h) |
3791 | |
3958 | |
3792 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3959 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3793 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3960 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3794 | |
3961 | |
3795 | =item EV_PROTOTYPES |
3962 | =item EV_PROTOTYPES (h) |
3796 | |
3963 | |
3797 | If defined to be C<0>, then F<ev.h> will not define any function |
3964 | If defined to be C<0>, then F<ev.h> will not define any function |
3798 | prototypes, but still define all the structs and other symbols. This is |
3965 | prototypes, but still define all the structs and other symbols. This is |
3799 | occasionally useful if you want to provide your own wrapper functions |
3966 | occasionally useful if you want to provide your own wrapper functions |
3800 | around libev functions. |
3967 | around libev functions. |
… | |
… | |
3822 | fine. |
3989 | fine. |
3823 | |
3990 | |
3824 | If your embedding application does not need any priorities, defining these |
3991 | If your embedding application does not need any priorities, defining these |
3825 | both to C<0> will save some memory and CPU. |
3992 | both to C<0> will save some memory and CPU. |
3826 | |
3993 | |
3827 | =item EV_PERIODIC_ENABLE |
3994 | =item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, |
|
|
3995 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
|
|
3996 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3828 | |
3997 | |
3829 | If undefined or defined to be C<1>, then periodic timers are supported. If |
3998 | If undefined or defined to be C<1> (and the platform supports it), then |
3830 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
3999 | the respective watcher type is supported. If defined to be C<0>, then it |
3831 | code. |
4000 | is not. Disabling watcher types mainly saves code size. |
3832 | |
4001 | |
3833 | =item EV_IDLE_ENABLE |
4002 | =item EV_FEATURES |
3834 | |
|
|
3835 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3836 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3837 | code. |
|
|
3838 | |
|
|
3839 | =item EV_EMBED_ENABLE |
|
|
3840 | |
|
|
3841 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3842 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3843 | watcher types, which therefore must not be disabled. |
|
|
3844 | |
|
|
3845 | =item EV_STAT_ENABLE |
|
|
3846 | |
|
|
3847 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3848 | defined to be C<0>, then they are not. |
|
|
3849 | |
|
|
3850 | =item EV_FORK_ENABLE |
|
|
3851 | |
|
|
3852 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3853 | defined to be C<0>, then they are not. |
|
|
3854 | |
|
|
3855 | =item EV_ASYNC_ENABLE |
|
|
3856 | |
|
|
3857 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3858 | defined to be C<0>, then they are not. |
|
|
3859 | |
|
|
3860 | =item EV_MINIMAL |
|
|
3861 | |
4003 | |
3862 | If you need to shave off some kilobytes of code at the expense of some |
4004 | If you need to shave off some kilobytes of code at the expense of some |
3863 | speed (but with the full API), define this symbol to C<1>. Currently this |
4005 | speed (but with the full API), you can define this symbol to request |
3864 | is used to override some inlining decisions, saves roughly 30% code size |
4006 | certain subsets of functionality. The default is to enable all features |
3865 | on amd64. It also selects a much smaller 2-heap for timer management over |
4007 | that can be enabled on the platform. |
3866 | the default 4-heap. |
|
|
3867 | |
4008 | |
3868 | You can save even more by disabling watcher types you do not need |
4009 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
3869 | and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert> |
4010 | with some broad features you want) and then selectively re-enable |
3870 | (C<-DNDEBUG>) will usually reduce code size a lot. |
4011 | additional parts you want, for example if you want everything minimal, |
|
|
4012 | but multiple event loop support, async and child watchers and the poll |
|
|
4013 | backend, use this: |
3871 | |
4014 | |
3872 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
4015 | #define EV_FEATURES 0 |
3873 | provide a bare-bones event library. See C<ev.h> for details on what parts |
4016 | #define EV_MULTIPLICITY 1 |
3874 | of the API are still available, and do not complain if this subset changes |
4017 | #define EV_USE_POLL 1 |
3875 | over time. |
4018 | #define EV_CHILD_ENABLE 1 |
|
|
4019 | #define EV_ASYNC_ENABLE 1 |
|
|
4020 | |
|
|
4021 | The actual value is a bitset, it can be a combination of the following |
|
|
4022 | values: |
|
|
4023 | |
|
|
4024 | =over 4 |
|
|
4025 | |
|
|
4026 | =item C<1> - faster/larger code |
|
|
4027 | |
|
|
4028 | Use larger code to speed up some operations. |
|
|
4029 | |
|
|
4030 | Currently this is used to override some inlining decisions (enlarging the |
|
|
4031 | code size by roughly 30% on amd64). |
|
|
4032 | |
|
|
4033 | When optimising for size, use of compiler flags such as C<-Os> with |
|
|
4034 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
|
|
4035 | assertions. |
|
|
4036 | |
|
|
4037 | =item C<2> - faster/larger data structures |
|
|
4038 | |
|
|
4039 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
|
|
4040 | hash table sizes and so on. This will usually further increase code size |
|
|
4041 | and can additionally have an effect on the size of data structures at |
|
|
4042 | runtime. |
|
|
4043 | |
|
|
4044 | =item C<4> - full API configuration |
|
|
4045 | |
|
|
4046 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
|
|
4047 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
|
|
4048 | |
|
|
4049 | =item C<8> - full API |
|
|
4050 | |
|
|
4051 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
|
|
4052 | details on which parts of the API are still available without this |
|
|
4053 | feature, and do not complain if this subset changes over time. |
|
|
4054 | |
|
|
4055 | =item C<16> - enable all optional watcher types |
|
|
4056 | |
|
|
4057 | Enables all optional watcher types. If you want to selectively enable |
|
|
4058 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
4059 | embed, async, child...) you can enable them manually by defining |
|
|
4060 | C<EV_watchertype_ENABLE> to C<1> instead. |
|
|
4061 | |
|
|
4062 | =item C<32> - enable all backends |
|
|
4063 | |
|
|
4064 | This enables all backends - without this feature, you need to enable at |
|
|
4065 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
|
|
4066 | |
|
|
4067 | =item C<64> - enable OS-specific "helper" APIs |
|
|
4068 | |
|
|
4069 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
4070 | default. |
|
|
4071 | |
|
|
4072 | =back |
|
|
4073 | |
|
|
4074 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
|
|
4075 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
4076 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
4077 | watchers, timers and monotonic clock support. |
|
|
4078 | |
|
|
4079 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
4080 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
|
|
4081 | your program might be left out as well - a binary starting a timer and an |
|
|
4082 | I/O watcher then might come out at only 5Kb. |
|
|
4083 | |
|
|
4084 | =item EV_AVOID_STDIO |
|
|
4085 | |
|
|
4086 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
|
|
4087 | functions (printf, scanf, perror etc.). This will increase the code size |
|
|
4088 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
4089 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
4090 | big. |
|
|
4091 | |
|
|
4092 | Note that error messages might become less precise when this option is |
|
|
4093 | enabled. |
3876 | |
4094 | |
3877 | =item EV_NSIG |
4095 | =item EV_NSIG |
3878 | |
4096 | |
3879 | The highest supported signal number, +1 (or, the number of |
4097 | The highest supported signal number, +1 (or, the number of |
3880 | signals): Normally, libev tries to deduce the maximum number of signals |
4098 | signals): Normally, libev tries to deduce the maximum number of signals |
3881 | automatically, but sometimes this fails, in which case it can be |
4099 | automatically, but sometimes this fails, in which case it can be |
3882 | specified. Also, using a lower number than detected (C<32> should be |
4100 | specified. Also, using a lower number than detected (C<32> should be |
3883 | good for about any system in existance) can save some memory, as libev |
4101 | good for about any system in existence) can save some memory, as libev |
3884 | statically allocates some 12-24 bytes per signal number. |
4102 | statically allocates some 12-24 bytes per signal number. |
3885 | |
4103 | |
3886 | =item EV_PID_HASHSIZE |
4104 | =item EV_PID_HASHSIZE |
3887 | |
4105 | |
3888 | C<ev_child> watchers use a small hash table to distribute workload by |
4106 | C<ev_child> watchers use a small hash table to distribute workload by |
3889 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
4107 | pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled), |
3890 | than enough. If you need to manage thousands of children you might want to |
4108 | usually more than enough. If you need to manage thousands of children you |
3891 | increase this value (I<must> be a power of two). |
4109 | might want to increase this value (I<must> be a power of two). |
3892 | |
4110 | |
3893 | =item EV_INOTIFY_HASHSIZE |
4111 | =item EV_INOTIFY_HASHSIZE |
3894 | |
4112 | |
3895 | C<ev_stat> watchers use a small hash table to distribute workload by |
4113 | C<ev_stat> watchers use a small hash table to distribute workload by |
3896 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
4114 | inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES> |
3897 | usually more than enough. If you need to manage thousands of C<ev_stat> |
4115 | disabled), usually more than enough. If you need to manage thousands of |
3898 | watchers you might want to increase this value (I<must> be a power of |
4116 | C<ev_stat> watchers you might want to increase this value (I<must> be a |
3899 | two). |
4117 | power of two). |
3900 | |
4118 | |
3901 | =item EV_USE_4HEAP |
4119 | =item EV_USE_4HEAP |
3902 | |
4120 | |
3903 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4121 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3904 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
4122 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3905 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
4123 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3906 | faster performance with many (thousands) of watchers. |
4124 | faster performance with many (thousands) of watchers. |
3907 | |
4125 | |
3908 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4126 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3909 | (disabled). |
4127 | will be C<0>. |
3910 | |
4128 | |
3911 | =item EV_HEAP_CACHE_AT |
4129 | =item EV_HEAP_CACHE_AT |
3912 | |
4130 | |
3913 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4131 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3914 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
4132 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3915 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
4133 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3916 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
4134 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3917 | but avoids random read accesses on heap changes. This improves performance |
4135 | but avoids random read accesses on heap changes. This improves performance |
3918 | noticeably with many (hundreds) of watchers. |
4136 | noticeably with many (hundreds) of watchers. |
3919 | |
4137 | |
3920 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4138 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3921 | (disabled). |
4139 | will be C<0>. |
3922 | |
4140 | |
3923 | =item EV_VERIFY |
4141 | =item EV_VERIFY |
3924 | |
4142 | |
3925 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4143 | Controls how much internal verification (see C<ev_verify ()>) will |
3926 | be done: If set to C<0>, no internal verification code will be compiled |
4144 | be done: If set to C<0>, no internal verification code will be compiled |
3927 | in. If set to C<1>, then verification code will be compiled in, but not |
4145 | in. If set to C<1>, then verification code will be compiled in, but not |
3928 | called. If set to C<2>, then the internal verification code will be |
4146 | called. If set to C<2>, then the internal verification code will be |
3929 | called once per loop, which can slow down libev. If set to C<3>, then the |
4147 | called once per loop, which can slow down libev. If set to C<3>, then the |
3930 | verification code will be called very frequently, which will slow down |
4148 | verification code will be called very frequently, which will slow down |
3931 | libev considerably. |
4149 | libev considerably. |
3932 | |
4150 | |
3933 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
4151 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3934 | C<0>. |
4152 | will be C<0>. |
3935 | |
4153 | |
3936 | =item EV_COMMON |
4154 | =item EV_COMMON |
3937 | |
4155 | |
3938 | By default, all watchers have a C<void *data> member. By redefining |
4156 | By default, all watchers have a C<void *data> member. By redefining |
3939 | this macro to a something else you can include more and other types of |
4157 | this macro to something else you can include more and other types of |
3940 | members. You have to define it each time you include one of the files, |
4158 | members. You have to define it each time you include one of the files, |
3941 | though, and it must be identical each time. |
4159 | though, and it must be identical each time. |
3942 | |
4160 | |
3943 | For example, the perl EV module uses something like this: |
4161 | For example, the perl EV module uses something like this: |
3944 | |
4162 | |
… | |
… | |
3997 | file. |
4215 | file. |
3998 | |
4216 | |
3999 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4217 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4000 | that everybody includes and which overrides some configure choices: |
4218 | that everybody includes and which overrides some configure choices: |
4001 | |
4219 | |
4002 | #define EV_MINIMAL 1 |
4220 | #define EV_FEATURES 8 |
4003 | #define EV_USE_POLL 0 |
4221 | #define EV_USE_SELECT 1 |
4004 | #define EV_MULTIPLICITY 0 |
|
|
4005 | #define EV_PERIODIC_ENABLE 0 |
4222 | #define EV_PREPARE_ENABLE 1 |
|
|
4223 | #define EV_IDLE_ENABLE 1 |
4006 | #define EV_STAT_ENABLE 0 |
4224 | #define EV_SIGNAL_ENABLE 1 |
4007 | #define EV_FORK_ENABLE 0 |
4225 | #define EV_CHILD_ENABLE 1 |
|
|
4226 | #define EV_USE_STDEXCEPT 0 |
4008 | #define EV_CONFIG_H <config.h> |
4227 | #define EV_CONFIG_H <config.h> |
4009 | #define EV_MINPRI 0 |
|
|
4010 | #define EV_MAXPRI 0 |
|
|
4011 | |
4228 | |
4012 | #include "ev++.h" |
4229 | #include "ev++.h" |
4013 | |
4230 | |
4014 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4231 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4015 | |
4232 | |
… | |
… | |
4146 | userdata *u = ev_userdata (EV_A); |
4363 | userdata *u = ev_userdata (EV_A); |
4147 | pthread_mutex_lock (&u->lock); |
4364 | pthread_mutex_lock (&u->lock); |
4148 | } |
4365 | } |
4149 | |
4366 | |
4150 | The event loop thread first acquires the mutex, and then jumps straight |
4367 | The event loop thread first acquires the mutex, and then jumps straight |
4151 | into C<ev_loop>: |
4368 | into C<ev_run>: |
4152 | |
4369 | |
4153 | void * |
4370 | void * |
4154 | l_run (void *thr_arg) |
4371 | l_run (void *thr_arg) |
4155 | { |
4372 | { |
4156 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4373 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4157 | |
4374 | |
4158 | l_acquire (EV_A); |
4375 | l_acquire (EV_A); |
4159 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4376 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4160 | ev_loop (EV_A_ 0); |
4377 | ev_run (EV_A_ 0); |
4161 | l_release (EV_A); |
4378 | l_release (EV_A); |
4162 | |
4379 | |
4163 | return 0; |
4380 | return 0; |
4164 | } |
4381 | } |
4165 | |
4382 | |
… | |
… | |
4217 | |
4434 | |
4218 | =head3 COROUTINES |
4435 | =head3 COROUTINES |
4219 | |
4436 | |
4220 | Libev is very accommodating to coroutines ("cooperative threads"): |
4437 | Libev is very accommodating to coroutines ("cooperative threads"): |
4221 | libev fully supports nesting calls to its functions from different |
4438 | libev fully supports nesting calls to its functions from different |
4222 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4439 | coroutines (e.g. you can call C<ev_run> on the same loop from two |
4223 | different coroutines, and switch freely between both coroutines running |
4440 | different coroutines, and switch freely between both coroutines running |
4224 | the loop, as long as you don't confuse yourself). The only exception is |
4441 | the loop, as long as you don't confuse yourself). The only exception is |
4225 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4442 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4226 | |
4443 | |
4227 | Care has been taken to ensure that libev does not keep local state inside |
4444 | Care has been taken to ensure that libev does not keep local state inside |
4228 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4445 | C<ev_run>, and other calls do not usually allow for coroutine switches as |
4229 | they do not call any callbacks. |
4446 | they do not call any callbacks. |
4230 | |
4447 | |
4231 | =head2 COMPILER WARNINGS |
4448 | =head2 COMPILER WARNINGS |
4232 | |
4449 | |
4233 | Depending on your compiler and compiler settings, you might get no or a |
4450 | Depending on your compiler and compiler settings, you might get no or a |
… | |
… | |
4244 | maintainable. |
4461 | maintainable. |
4245 | |
4462 | |
4246 | And of course, some compiler warnings are just plain stupid, or simply |
4463 | And of course, some compiler warnings are just plain stupid, or simply |
4247 | wrong (because they don't actually warn about the condition their message |
4464 | wrong (because they don't actually warn about the condition their message |
4248 | seems to warn about). For example, certain older gcc versions had some |
4465 | seems to warn about). For example, certain older gcc versions had some |
4249 | warnings that resulted an extreme number of false positives. These have |
4466 | warnings that resulted in an extreme number of false positives. These have |
4250 | been fixed, but some people still insist on making code warn-free with |
4467 | been fixed, but some people still insist on making code warn-free with |
4251 | such buggy versions. |
4468 | such buggy versions. |
4252 | |
4469 | |
4253 | While libev is written to generate as few warnings as possible, |
4470 | While libev is written to generate as few warnings as possible, |
4254 | "warn-free" code is not a goal, and it is recommended not to build libev |
4471 | "warn-free" code is not a goal, and it is recommended not to build libev |
… | |
… | |
4290 | I suggest using suppression lists. |
4507 | I suggest using suppression lists. |
4291 | |
4508 | |
4292 | |
4509 | |
4293 | =head1 PORTABILITY NOTES |
4510 | =head1 PORTABILITY NOTES |
4294 | |
4511 | |
|
|
4512 | =head2 GNU/LINUX 32 BIT LIMITATIONS |
|
|
4513 | |
|
|
4514 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
4515 | interfaces but I<disables> them by default. |
|
|
4516 | |
|
|
4517 | That means that libev compiled in the default environment doesn't support |
|
|
4518 | files larger than 2GiB or so, which mainly affects C<ev_stat> watchers. |
|
|
4519 | |
|
|
4520 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
4521 | by enabling the large file API, which makes them incompatible with the |
|
|
4522 | standard libev compiled for their system. |
|
|
4523 | |
|
|
4524 | Likewise, libev cannot enable the large file API itself as this would |
|
|
4525 | suddenly make it incompatible to the default compile time environment, |
|
|
4526 | i.e. all programs not using special compile switches. |
|
|
4527 | |
|
|
4528 | =head2 OS/X AND DARWIN BUGS |
|
|
4529 | |
|
|
4530 | The whole thing is a bug if you ask me - basically any system interface |
|
|
4531 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
4532 | OpenGL drivers. |
|
|
4533 | |
|
|
4534 | =head3 C<kqueue> is buggy |
|
|
4535 | |
|
|
4536 | The kqueue syscall is broken in all known versions - most versions support |
|
|
4537 | only sockets, many support pipes. |
|
|
4538 | |
|
|
4539 | Libev tries to work around this by not using C<kqueue> by default on this |
|
|
4540 | rotten platform, but of course you can still ask for it when creating a |
|
|
4541 | loop - embedding a socket-only kqueue loop into a select-based one is |
|
|
4542 | probably going to work well. |
|
|
4543 | |
|
|
4544 | =head3 C<poll> is buggy |
|
|
4545 | |
|
|
4546 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
|
|
4547 | implementation by something calling C<kqueue> internally around the 10.5.6 |
|
|
4548 | release, so now C<kqueue> I<and> C<poll> are broken. |
|
|
4549 | |
|
|
4550 | Libev tries to work around this by not using C<poll> by default on |
|
|
4551 | this rotten platform, but of course you can still ask for it when creating |
|
|
4552 | a loop. |
|
|
4553 | |
|
|
4554 | =head3 C<select> is buggy |
|
|
4555 | |
|
|
4556 | All that's left is C<select>, and of course Apple found a way to fuck this |
|
|
4557 | one up as well: On OS/X, C<select> actively limits the number of file |
|
|
4558 | descriptors you can pass in to 1024 - your program suddenly crashes when |
|
|
4559 | you use more. |
|
|
4560 | |
|
|
4561 | There is an undocumented "workaround" for this - defining |
|
|
4562 | C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should> |
|
|
4563 | work on OS/X. |
|
|
4564 | |
|
|
4565 | =head2 SOLARIS PROBLEMS AND WORKAROUNDS |
|
|
4566 | |
|
|
4567 | =head3 C<errno> reentrancy |
|
|
4568 | |
|
|
4569 | The default compile environment on Solaris is unfortunately so |
|
|
4570 | thread-unsafe that you can't even use components/libraries compiled |
|
|
4571 | without C<-D_REENTRANT> in a threaded program, which, of course, isn't |
|
|
4572 | defined by default. A valid, if stupid, implementation choice. |
|
|
4573 | |
|
|
4574 | If you want to use libev in threaded environments you have to make sure |
|
|
4575 | it's compiled with C<_REENTRANT> defined. |
|
|
4576 | |
|
|
4577 | =head3 Event port backend |
|
|
4578 | |
|
|
4579 | The scalable event interface for Solaris is called "event |
|
|
4580 | ports". Unfortunately, this mechanism is very buggy in all major |
|
|
4581 | releases. If you run into high CPU usage, your program freezes or you get |
|
|
4582 | a large number of spurious wakeups, make sure you have all the relevant |
|
|
4583 | and latest kernel patches applied. No, I don't know which ones, but there |
|
|
4584 | are multiple ones to apply, and afterwards, event ports actually work |
|
|
4585 | great. |
|
|
4586 | |
|
|
4587 | If you can't get it to work, you can try running the program by setting |
|
|
4588 | the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and |
|
|
4589 | C<select> backends. |
|
|
4590 | |
|
|
4591 | =head2 AIX POLL BUG |
|
|
4592 | |
|
|
4593 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
|
|
4594 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
4595 | compiled in), which normally isn't a big problem as C<select> works fine |
|
|
4596 | with large bitsets on AIX, and AIX is dead anyway. |
|
|
4597 | |
4295 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4598 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
|
|
4599 | |
|
|
4600 | =head3 General issues |
4296 | |
4601 | |
4297 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4602 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4298 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4603 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4299 | model. Libev still offers limited functionality on this platform in |
4604 | model. Libev still offers limited functionality on this platform in |
4300 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4605 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4301 | descriptors. This only applies when using Win32 natively, not when using |
4606 | descriptors. This only applies when using Win32 natively, not when using |
4302 | e.g. cygwin. |
4607 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
4608 | as every compielr comes with a slightly differently broken/incompatible |
|
|
4609 | environment. |
4303 | |
4610 | |
4304 | Lifting these limitations would basically require the full |
4611 | Lifting these limitations would basically require the full |
4305 | re-implementation of the I/O system. If you are into these kinds of |
4612 | re-implementation of the I/O system. If you are into this kind of thing, |
4306 | things, then note that glib does exactly that for you in a very portable |
4613 | then note that glib does exactly that for you in a very portable way (note |
4307 | way (note also that glib is the slowest event library known to man). |
4614 | also that glib is the slowest event library known to man). |
4308 | |
4615 | |
4309 | There is no supported compilation method available on windows except |
4616 | There is no supported compilation method available on windows except |
4310 | embedding it into other applications. |
4617 | embedding it into other applications. |
4311 | |
4618 | |
4312 | Sensible signal handling is officially unsupported by Microsoft - libev |
4619 | Sensible signal handling is officially unsupported by Microsoft - libev |
… | |
… | |
4340 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4647 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4341 | |
4648 | |
4342 | #include "evwrap.h" |
4649 | #include "evwrap.h" |
4343 | #include "ev.c" |
4650 | #include "ev.c" |
4344 | |
4651 | |
4345 | =over 4 |
|
|
4346 | |
|
|
4347 | =item The winsocket select function |
4652 | =head3 The winsocket C<select> function |
4348 | |
4653 | |
4349 | The winsocket C<select> function doesn't follow POSIX in that it |
4654 | The winsocket C<select> function doesn't follow POSIX in that it |
4350 | requires socket I<handles> and not socket I<file descriptors> (it is |
4655 | requires socket I<handles> and not socket I<file descriptors> (it is |
4351 | also extremely buggy). This makes select very inefficient, and also |
4656 | also extremely buggy). This makes select very inefficient, and also |
4352 | requires a mapping from file descriptors to socket handles (the Microsoft |
4657 | requires a mapping from file descriptors to socket handles (the Microsoft |
… | |
… | |
4361 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4666 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4362 | |
4667 | |
4363 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4668 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4364 | complexity in the O(n²) range when using win32. |
4669 | complexity in the O(n²) range when using win32. |
4365 | |
4670 | |
4366 | =item Limited number of file descriptors |
4671 | =head3 Limited number of file descriptors |
4367 | |
4672 | |
4368 | Windows has numerous arbitrary (and low) limits on things. |
4673 | Windows has numerous arbitrary (and low) limits on things. |
4369 | |
4674 | |
4370 | Early versions of winsocket's select only supported waiting for a maximum |
4675 | Early versions of winsocket's select only supported waiting for a maximum |
4371 | of C<64> handles (probably owning to the fact that all windows kernels |
4676 | of C<64> handles (probably owning to the fact that all windows kernels |
… | |
… | |
4386 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4691 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4387 | (depending on windows version and/or the phase of the moon). To get more, |
4692 | (depending on windows version and/or the phase of the moon). To get more, |
4388 | you need to wrap all I/O functions and provide your own fd management, but |
4693 | you need to wrap all I/O functions and provide your own fd management, but |
4389 | the cost of calling select (O(n²)) will likely make this unworkable. |
4694 | the cost of calling select (O(n²)) will likely make this unworkable. |
4390 | |
4695 | |
4391 | =back |
|
|
4392 | |
|
|
4393 | =head2 PORTABILITY REQUIREMENTS |
4696 | =head2 PORTABILITY REQUIREMENTS |
4394 | |
4697 | |
4395 | In addition to a working ISO-C implementation and of course the |
4698 | In addition to a working ISO-C implementation and of course the |
4396 | backend-specific APIs, libev relies on a few additional extensions: |
4699 | backend-specific APIs, libev relies on a few additional extensions: |
4397 | |
4700 | |
… | |
… | |
4435 | watchers. |
4738 | watchers. |
4436 | |
4739 | |
4437 | =item C<double> must hold a time value in seconds with enough accuracy |
4740 | =item C<double> must hold a time value in seconds with enough accuracy |
4438 | |
4741 | |
4439 | The type C<double> is used to represent timestamps. It is required to |
4742 | The type C<double> is used to represent timestamps. It is required to |
4440 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4743 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
4441 | enough for at least into the year 4000. This requirement is fulfilled by |
4744 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
4745 | (the design goal for libev). This requirement is overfulfilled by |
4442 | implementations implementing IEEE 754, which is basically all existing |
4746 | implementations using IEEE 754, which is basically all existing ones. With |
4443 | ones. With IEEE 754 doubles, you get microsecond accuracy until at least |
4747 | IEEE 754 doubles, you get microsecond accuracy until at least 2200. |
4444 | 2200. |
|
|
4445 | |
4748 | |
4446 | =back |
4749 | =back |
4447 | |
4750 | |
4448 | If you know of other additional requirements drop me a note. |
4751 | If you know of other additional requirements drop me a note. |
4449 | |
4752 | |
… | |
… | |
4517 | involves iterating over all running async watchers or all signal numbers. |
4820 | involves iterating over all running async watchers or all signal numbers. |
4518 | |
4821 | |
4519 | =back |
4822 | =back |
4520 | |
4823 | |
4521 | |
4824 | |
|
|
4825 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
|
|
4826 | |
|
|
4827 | The major version 4 introduced some minor incompatible changes to the API. |
|
|
4828 | |
|
|
4829 | At the moment, the C<ev.h> header file tries to implement superficial |
|
|
4830 | compatibility, so most programs should still compile. Those might be |
|
|
4831 | removed in later versions of libev, so better update early than late. |
|
|
4832 | |
|
|
4833 | =over 4 |
|
|
4834 | |
|
|
4835 | =item function/symbol renames |
|
|
4836 | |
|
|
4837 | A number of functions and symbols have been renamed: |
|
|
4838 | |
|
|
4839 | ev_loop => ev_run |
|
|
4840 | EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
4841 | EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
4842 | |
|
|
4843 | ev_unloop => ev_break |
|
|
4844 | EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
4845 | EVUNLOOP_ONE => EVBREAK_ONE |
|
|
4846 | EVUNLOOP_ALL => EVBREAK_ALL |
|
|
4847 | |
|
|
4848 | EV_TIMEOUT => EV_TIMER |
|
|
4849 | |
|
|
4850 | ev_loop_count => ev_iteration |
|
|
4851 | ev_loop_depth => ev_depth |
|
|
4852 | ev_loop_verify => ev_verify |
|
|
4853 | |
|
|
4854 | Most functions working on C<struct ev_loop> objects don't have an |
|
|
4855 | C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and |
|
|
4856 | associated constants have been renamed to not collide with the C<struct |
|
|
4857 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
|
|
4858 | as all other watcher types. Note that C<ev_loop_fork> is still called |
|
|
4859 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
|
|
4860 | typedef. |
|
|
4861 | |
|
|
4862 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
4863 | |
|
|
4864 | The backward compatibility mechanism can be controlled by |
|
|
4865 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
4866 | section. |
|
|
4867 | |
|
|
4868 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
4869 | |
|
|
4870 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
4871 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
4872 | and work, but the library code will of course be larger. |
|
|
4873 | |
|
|
4874 | =back |
|
|
4875 | |
|
|
4876 | |
4522 | =head1 GLOSSARY |
4877 | =head1 GLOSSARY |
4523 | |
4878 | |
4524 | =over 4 |
4879 | =over 4 |
4525 | |
4880 | |
4526 | =item active |
4881 | =item active |
4527 | |
4882 | |
4528 | A watcher is active as long as it has been started (has been attached to |
4883 | A watcher is active as long as it has been started and not yet stopped. |
4529 | an event loop) but not yet stopped (disassociated from the event loop). |
4884 | See L<WATCHER STATES> for details. |
4530 | |
4885 | |
4531 | =item application |
4886 | =item application |
4532 | |
4887 | |
4533 | In this document, an application is whatever is using libev. |
4888 | In this document, an application is whatever is using libev. |
|
|
4889 | |
|
|
4890 | =item backend |
|
|
4891 | |
|
|
4892 | The part of the code dealing with the operating system interfaces. |
4534 | |
4893 | |
4535 | =item callback |
4894 | =item callback |
4536 | |
4895 | |
4537 | The address of a function that is called when some event has been |
4896 | The address of a function that is called when some event has been |
4538 | detected. Callbacks are being passed the event loop, the watcher that |
4897 | detected. Callbacks are being passed the event loop, the watcher that |
4539 | received the event, and the actual event bitset. |
4898 | received the event, and the actual event bitset. |
4540 | |
4899 | |
4541 | =item callback invocation |
4900 | =item callback/watcher invocation |
4542 | |
4901 | |
4543 | The act of calling the callback associated with a watcher. |
4902 | The act of calling the callback associated with a watcher. |
4544 | |
4903 | |
4545 | =item event |
4904 | =item event |
4546 | |
4905 | |
4547 | A change of state of some external event, such as data now being available |
4906 | A change of state of some external event, such as data now being available |
4548 | for reading on a file descriptor, time having passed or simply not having |
4907 | for reading on a file descriptor, time having passed or simply not having |
4549 | any other events happening anymore. |
4908 | any other events happening anymore. |
4550 | |
4909 | |
4551 | In libev, events are represented as single bits (such as C<EV_READ> or |
4910 | In libev, events are represented as single bits (such as C<EV_READ> or |
4552 | C<EV_TIMEOUT>). |
4911 | C<EV_TIMER>). |
4553 | |
4912 | |
4554 | =item event library |
4913 | =item event library |
4555 | |
4914 | |
4556 | A software package implementing an event model and loop. |
4915 | A software package implementing an event model and loop. |
4557 | |
4916 | |
… | |
… | |
4565 | The model used to describe how an event loop handles and processes |
4924 | The model used to describe how an event loop handles and processes |
4566 | watchers and events. |
4925 | watchers and events. |
4567 | |
4926 | |
4568 | =item pending |
4927 | =item pending |
4569 | |
4928 | |
4570 | A watcher is pending as soon as the corresponding event has been detected, |
4929 | A watcher is pending as soon as the corresponding event has been |
4571 | and stops being pending as soon as the watcher will be invoked or its |
4930 | detected. See L<WATCHER STATES> for details. |
4572 | pending status is explicitly cleared by the application. |
|
|
4573 | |
|
|
4574 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4575 | its pending status. |
|
|
4576 | |
4931 | |
4577 | =item real time |
4932 | =item real time |
4578 | |
4933 | |
4579 | The physical time that is observed. It is apparently strictly monotonic :) |
4934 | The physical time that is observed. It is apparently strictly monotonic :) |
4580 | |
4935 | |
… | |
… | |
4587 | =item watcher |
4942 | =item watcher |
4588 | |
4943 | |
4589 | A data structure that describes interest in certain events. Watchers need |
4944 | A data structure that describes interest in certain events. Watchers need |
4590 | to be started (attached to an event loop) before they can receive events. |
4945 | to be started (attached to an event loop) before they can receive events. |
4591 | |
4946 | |
4592 | =item watcher invocation |
|
|
4593 | |
|
|
4594 | The act of calling the callback associated with a watcher. |
|
|
4595 | |
|
|
4596 | =back |
4947 | =back |
4597 | |
4948 | |
4598 | =head1 AUTHOR |
4949 | =head1 AUTHOR |
4599 | |
4950 | |
4600 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
4951 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |