… | |
… | |
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 | { |
47 | // use the default event loop unless you have special needs |
47 | // use the default event loop unless you have special needs |
48 | struct ev_loop *loop = ev_default_loop (0); |
48 | struct ev_loop *loop = EV_DEFAULT; |
49 | |
49 | |
50 | // initialise an io watcher, then start it |
50 | // initialise an io watcher, then start it |
51 | // this one will watch for stdin to become readable |
51 | // this one will watch for stdin to become readable |
52 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
52 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
53 | ev_io_start (loop, &stdin_watcher); |
53 | ev_io_start (loop, &stdin_watcher); |
… | |
… | |
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 (in practise |
129 | the (fractional) number of seconds since the (POSIX) epoch (in practice |
130 | somewhere near the beginning of 1970, details are complicated, don't |
130 | somewhere near the beginning of 1970, details are complicated, don't |
131 | ask). This type is called C<ev_tstamp>, which is what you should use |
131 | ask). This type is called C<ev_tstamp>, which is what you should use |
132 | too. It usually aliases to the C<double> type in C. When you need to do |
132 | too. It usually aliases to the C<double> type in C. When you need to do |
133 | any calculations on it, you should treat it as some floating point value. |
133 | any calculations on it, you should treat it as some floating point value. |
134 | |
134 | |
… | |
… | |
165 | |
165 | |
166 | =item ev_tstamp ev_time () |
166 | =item ev_tstamp ev_time () |
167 | |
167 | |
168 | 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 |
169 | 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 |
170 | you actually want to know. |
170 | you actually want to know. Also interesting is the combination of |
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171 | C<ev_update_now> and C<ev_now>. |
171 | |
172 | |
172 | =item ev_sleep (ev_tstamp interval) |
173 | =item ev_sleep (ev_tstamp interval) |
173 | |
174 | |
174 | 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 |
175 | 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 |
… | |
… | |
192 | as this indicates an incompatible change. Minor versions are usually |
193 | as this indicates an incompatible change. Minor versions are usually |
193 | 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 |
194 | not a problem. |
195 | not a problem. |
195 | |
196 | |
196 | 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 |
197 | version (note, however, that this will not detect ABI mismatches :). |
198 | version (note, however, that this will not detect other ABI mismatches, |
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199 | such as LFS or reentrancy). |
198 | |
200 | |
199 | assert (("libev version mismatch", |
201 | assert (("libev version mismatch", |
200 | ev_version_major () == EV_VERSION_MAJOR |
202 | ev_version_major () == EV_VERSION_MAJOR |
201 | && ev_version_minor () >= EV_VERSION_MINOR)); |
203 | && ev_version_minor () >= EV_VERSION_MINOR)); |
202 | |
204 | |
… | |
… | |
213 | assert (("sorry, no epoll, no sex", |
215 | assert (("sorry, no epoll, no sex", |
214 | ev_supported_backends () & EVBACKEND_EPOLL)); |
216 | ev_supported_backends () & EVBACKEND_EPOLL)); |
215 | |
217 | |
216 | =item unsigned int ev_recommended_backends () |
218 | =item unsigned int ev_recommended_backends () |
217 | |
219 | |
218 | 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 |
219 | 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 |
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|
222 | descriptor types. This set is often smaller than the one returned by |
220 | 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 |
221 | 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 |
222 | (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 |
223 | libev will probe for if you specify no backends explicitly. |
226 | probe for if you specify no backends explicitly. |
224 | |
227 | |
225 | =item unsigned int ev_embeddable_backends () |
228 | =item unsigned int ev_embeddable_backends () |
226 | |
229 | |
227 | 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 |
228 | is the theoretical, all-platform, value. To find which backends |
231 | value is platform-specific but can include backends not available on the |
229 | 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 |
230 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
233 | the current system, you would need to look at C<ev_embeddable_backends () |
231 | recommended ones. |
234 | & ev_supported_backends ()>, likewise for recommended ones. |
232 | |
235 | |
233 | See the description of C<ev_embed> watchers for more info. |
236 | See the description of C<ev_embed> watchers for more info. |
234 | |
237 | |
235 | =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] |
236 | |
239 | |
… | |
… | |
290 | ... |
293 | ... |
291 | ev_set_syserr_cb (fatal_error); |
294 | ev_set_syserr_cb (fatal_error); |
292 | |
295 | |
293 | =back |
296 | =back |
294 | |
297 | |
295 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
298 | =head1 FUNCTIONS CONTROLLING EVENT LOOPS |
296 | |
299 | |
297 | 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 |
298 | 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 |
299 | I<function>). |
302 | libev 3 had an C<ev_loop> function colliding with the struct name). |
300 | |
303 | |
301 | 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 |
302 | supports signals and child events, and dynamically created loops which do |
305 | supports signals and child events, and dynamically created event loops |
303 | not. |
306 | which do not. |
304 | |
307 | |
305 | =over 4 |
308 | =over 4 |
306 | |
309 | |
307 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
310 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
308 | |
311 | |
309 | This will initialise the default event loop if it hasn't been initialised |
312 | This returns the "default" event loop object, which is what you should |
310 | yet and return it. If the default loop could not be initialised, returns |
313 | normally use when you just need "the event loop". Event loop objects and |
311 | false. If it already was initialised it simply returns it (and ignores the |
314 | the C<flags> parameter are described in more detail in the entry for |
312 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
315 | C<ev_loop_new>. |
|
|
316 | |
|
|
317 | If the default loop is already initialised then this function simply |
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318 | returns it (and ignores the flags. If that is troubling you, check |
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319 | C<ev_backend ()> afterwards). Otherwise it will create it with the given |
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320 | flags, which should almost always be C<0>, unless the caller is also the |
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321 | one calling C<ev_run> or otherwise qualifies as "the main program". |
313 | |
322 | |
314 | If you don't know what event loop to use, use the one returned from this |
323 | If you don't know what event loop to use, use the one returned from this |
315 | function. |
324 | function (or via the C<EV_DEFAULT> macro). |
316 | |
325 | |
317 | Note that this function is I<not> thread-safe, so if you want to use it |
326 | Note that this function is I<not> thread-safe, so if you want to use it |
318 | from multiple threads, you have to lock (note also that this is unlikely, |
327 | from multiple threads, you have to employ some kind of mutex (note also |
319 | as loops cannot be shared easily between threads anyway). |
328 | that this case is unlikely, as loops cannot be shared easily between |
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329 | threads anyway). |
320 | |
330 | |
321 | The default loop is the only loop that can handle C<ev_signal> and |
331 | The default loop is the only loop that can handle C<ev_child> watchers, |
322 | C<ev_child> watchers, and to do this, it always registers a handler |
332 | and to do this, it always registers a handler for C<SIGCHLD>. If this is |
323 | for C<SIGCHLD>. If this is a problem for your application you can either |
333 | a problem for your application you can either create a dynamic loop with |
324 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
334 | C<ev_loop_new> which doesn't do that, or you can simply overwrite the |
325 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
335 | C<SIGCHLD> signal handler I<after> calling C<ev_default_init>. |
326 | C<ev_default_init>. |
336 | |
|
|
337 | Example: This is the most typical usage. |
|
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338 | |
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339 | if (!ev_default_loop (0)) |
|
|
340 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
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341 | |
|
|
342 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
343 | environment settings to be taken into account: |
|
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344 | |
|
|
345 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
346 | |
|
|
347 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
|
|
348 | |
|
|
349 | This will create and initialise a new event loop object. If the loop |
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350 | could not be initialised, returns false. |
|
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351 | |
|
|
352 | Note that this function I<is> thread-safe, and one common way to use |
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353 | libev with threads is indeed to create one loop per thread, and using the |
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354 | default loop in the "main" or "initial" thread. |
327 | |
355 | |
328 | The flags argument can be used to specify special behaviour or specific |
356 | The flags argument can be used to specify special behaviour or specific |
329 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
357 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
330 | |
358 | |
331 | The following flags are supported: |
359 | The following flags are supported: |
… | |
… | |
439 | of course I<doesn't>, and epoll just loves to report events for totally |
467 | of course I<doesn't>, and epoll just loves to report events for totally |
440 | I<different> file descriptors (even already closed ones, so one cannot |
468 | I<different> file descriptors (even already closed ones, so one cannot |
441 | even remove them from the set) than registered in the set (especially |
469 | even remove them from the set) than registered in the set (especially |
442 | on SMP systems). Libev tries to counter these spurious notifications by |
470 | on SMP systems). Libev tries to counter these spurious notifications by |
443 | employing an additional generation counter and comparing that against the |
471 | employing an additional generation counter and comparing that against the |
444 | events to filter out spurious ones, recreating the set when required. |
472 | events to filter out spurious ones, recreating the set when required. Last |
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473 | not least, it also refuses to work with some file descriptors which work |
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|
474 | perfectly fine with C<select> (files, many character devices...). |
445 | |
475 | |
446 | While stopping, setting and starting an I/O watcher in the same iteration |
476 | While stopping, setting and starting an I/O watcher in the same iteration |
447 | will result in some caching, there is still a system call per such |
477 | will result in some caching, there is still a system call per such |
448 | incident (because the same I<file descriptor> could point to a different |
478 | incident (because the same I<file descriptor> could point to a different |
449 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
479 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
… | |
… | |
547 | If one or more of the backend flags are or'ed into the flags value, |
577 | If one or more of the backend flags are or'ed into the flags value, |
548 | then only these backends will be tried (in the reverse order as listed |
578 | then only these backends will be tried (in the reverse order as listed |
549 | here). If none are specified, all backends in C<ev_recommended_backends |
579 | here). If none are specified, all backends in C<ev_recommended_backends |
550 | ()> will be tried. |
580 | ()> will be tried. |
551 | |
581 | |
552 | Example: This is the most typical usage. |
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|
553 | |
|
|
554 | if (!ev_default_loop (0)) |
|
|
555 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
556 | |
|
|
557 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
558 | environment settings to be taken into account: |
|
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559 | |
|
|
560 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
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561 | |
|
|
562 | Example: Use whatever libev has to offer, but make sure that kqueue is |
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563 | used if available (warning, breaks stuff, best use only with your own |
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564 | private event loop and only if you know the OS supports your types of |
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565 | fds): |
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566 | |
|
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567 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
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568 | |
|
|
569 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
|
|
570 | |
|
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571 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
|
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572 | always distinct from the default loop. |
|
|
573 | |
|
|
574 | Note that this function I<is> thread-safe, and one common way to use |
|
|
575 | libev with threads is indeed to create one loop per thread, and using the |
|
|
576 | default loop in the "main" or "initial" thread. |
|
|
577 | |
|
|
578 | Example: Try to create a event loop that uses epoll and nothing else. |
582 | Example: Try to create a event loop that uses epoll and nothing else. |
579 | |
583 | |
580 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
584 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
581 | if (!epoller) |
585 | if (!epoller) |
582 | fatal ("no epoll found here, maybe it hides under your chair"); |
586 | fatal ("no epoll found here, maybe it hides under your chair"); |
583 | |
587 | |
|
|
588 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
589 | used if available. |
|
|
590 | |
|
|
591 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
592 | |
584 | =item ev_default_destroy () |
593 | =item ev_loop_destroy (loop) |
585 | |
594 | |
586 | Destroys the default loop (frees all memory and kernel state etc.). None |
595 | Destroys an event loop object (frees all memory and kernel state |
587 | of the active event watchers will be stopped in the normal sense, so |
596 | etc.). None of the active event watchers will be stopped in the normal |
588 | e.g. C<ev_is_active> might still return true. It is your responsibility to |
597 | sense, so e.g. C<ev_is_active> might still return true. It is your |
589 | either stop all watchers cleanly yourself I<before> calling this function, |
598 | responsibility to either stop all watchers cleanly yourself I<before> |
590 | or cope with the fact afterwards (which is usually the easiest thing, you |
599 | calling this function, or cope with the fact afterwards (which is usually |
591 | can just ignore the watchers and/or C<free ()> them for example). |
600 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
|
|
601 | for example). |
592 | |
602 | |
593 | Note that certain global state, such as signal state (and installed signal |
603 | Note that certain global state, such as signal state (and installed signal |
594 | handlers), will not be freed by this function, and related watchers (such |
604 | handlers), will not be freed by this function, and related watchers (such |
595 | as signal and child watchers) would need to be stopped manually. |
605 | as signal and child watchers) would need to be stopped manually. |
596 | |
606 | |
597 | In general it is not advisable to call this function except in the |
607 | This function is normally used on loop objects allocated by |
598 | rare occasion where you really need to free e.g. the signal handling |
608 | C<ev_loop_new>, but it can also be used on the default loop returned by |
|
|
609 | C<ev_default_loop>, in which case it is not thread-safe. |
|
|
610 | |
|
|
611 | Note that it is not advisable to call this function on the default loop |
|
|
612 | except in the rare occasion where you really need to free it's resources. |
599 | pipe fds. If you need dynamically allocated loops it is better to use |
613 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
600 | C<ev_loop_new> and C<ev_loop_destroy>. |
614 | and C<ev_loop_destroy>. |
601 | |
615 | |
602 | =item ev_loop_destroy (loop) |
616 | =item ev_loop_fork (loop) |
603 | |
617 | |
604 | Like C<ev_default_destroy>, but destroys an event loop created by an |
|
|
605 | earlier call to C<ev_loop_new>. |
|
|
606 | |
|
|
607 | =item ev_default_fork () |
|
|
608 | |
|
|
609 | This function sets a flag that causes subsequent C<ev_loop> iterations |
618 | This function sets a flag that causes subsequent C<ev_run> iterations to |
610 | to reinitialise the kernel state for backends that have one. Despite the |
619 | reinitialise the kernel state for backends that have one. Despite the |
611 | name, you can call it anytime, but it makes most sense after forking, in |
620 | name, you can call it anytime, but it makes most sense after forking, in |
612 | the child process (or both child and parent, but that again makes little |
621 | the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the |
613 | sense). You I<must> call it in the child before using any of the libev |
622 | child before resuming or calling C<ev_run>. |
614 | functions, and it will only take effect at the next C<ev_loop> iteration. |
|
|
615 | |
623 | |
616 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
624 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
617 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
625 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
618 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
626 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
619 | during fork. |
627 | during fork. |
620 | |
628 | |
621 | On the other hand, you only need to call this function in the child |
629 | On the other hand, you only need to call this function in the child |
622 | process if and only if you want to use the event loop in the child. If you |
630 | process if and only if you want to use the event loop in the child. If |
623 | just fork+exec or create a new loop in the child, you don't have to call |
631 | you just fork+exec or create a new loop in the child, you don't have to |
624 | it at all. |
632 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
|
|
633 | difference, but libev will usually detect this case on its own and do a |
|
|
634 | costly reset of the backend). |
625 | |
635 | |
626 | The function itself is quite fast and it's usually not a problem to call |
636 | The function itself is quite fast and it's usually not a problem to call |
627 | it just in case after a fork. To make this easy, the function will fit in |
637 | it just in case after a fork. |
628 | quite nicely into a call to C<pthread_atfork>: |
|
|
629 | |
638 | |
|
|
639 | Example: Automate calling C<ev_loop_fork> on the default loop when |
|
|
640 | using pthreads. |
|
|
641 | |
|
|
642 | static void |
|
|
643 | post_fork_child (void) |
|
|
644 | { |
|
|
645 | ev_loop_fork (EV_DEFAULT); |
|
|
646 | } |
|
|
647 | |
|
|
648 | ... |
630 | pthread_atfork (0, 0, ev_default_fork); |
649 | pthread_atfork (0, 0, post_fork_child); |
631 | |
|
|
632 | =item ev_loop_fork (loop) |
|
|
633 | |
|
|
634 | Like C<ev_default_fork>, but acts on an event loop created by |
|
|
635 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
|
|
636 | after fork that you want to re-use in the child, and how you keep track of |
|
|
637 | them is entirely your own problem. |
|
|
638 | |
650 | |
639 | =item int ev_is_default_loop (loop) |
651 | =item int ev_is_default_loop (loop) |
640 | |
652 | |
641 | Returns true when the given loop is, in fact, the default loop, and false |
653 | Returns true when the given loop is, in fact, the default loop, and false |
642 | otherwise. |
654 | otherwise. |
643 | |
655 | |
644 | =item unsigned int ev_iteration (loop) |
656 | =item unsigned int ev_iteration (loop) |
645 | |
657 | |
646 | Returns the current iteration count for the loop, which is identical to |
658 | Returns the current iteration count for the event loop, which is identical |
647 | the number of times libev did poll for new events. It starts at C<0> and |
659 | to the number of times libev did poll for new events. It starts at C<0> |
648 | happily wraps around with enough iterations. |
660 | and happily wraps around with enough iterations. |
649 | |
661 | |
650 | This value can sometimes be useful as a generation counter of sorts (it |
662 | This value can sometimes be useful as a generation counter of sorts (it |
651 | "ticks" the number of loop iterations), as it roughly corresponds with |
663 | "ticks" the number of loop iterations), as it roughly corresponds with |
652 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
664 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
653 | prepare and check phases. |
665 | prepare and check phases. |
654 | |
666 | |
655 | =item unsigned int ev_depth (loop) |
667 | =item unsigned int ev_depth (loop) |
656 | |
668 | |
657 | Returns the number of times C<ev_loop> was entered minus the number of |
669 | Returns the number of times C<ev_run> was entered minus the number of |
658 | times C<ev_loop> was exited, in other words, the recursion depth. |
670 | times C<ev_run> was exited, in other words, the recursion depth. |
659 | |
671 | |
660 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
672 | Outside C<ev_run>, this number is zero. In a callback, this number is |
661 | C<1>, unless C<ev_loop> was invoked recursively (or from another thread), |
673 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
662 | in which case it is higher. |
674 | in which case it is higher. |
663 | |
675 | |
664 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
676 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread |
665 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
677 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
666 | ungentleman behaviour unless it's really convenient. |
678 | ungentleman-like behaviour unless it's really convenient. |
667 | |
679 | |
668 | =item unsigned int ev_backend (loop) |
680 | =item unsigned int ev_backend (loop) |
669 | |
681 | |
670 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
682 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
671 | use. |
683 | use. |
… | |
… | |
680 | |
692 | |
681 | =item ev_now_update (loop) |
693 | =item ev_now_update (loop) |
682 | |
694 | |
683 | Establishes the current time by querying the kernel, updating the time |
695 | Establishes the current time by querying the kernel, updating the time |
684 | returned by C<ev_now ()> in the progress. This is a costly operation and |
696 | returned by C<ev_now ()> in the progress. This is a costly operation and |
685 | is usually done automatically within C<ev_loop ()>. |
697 | is usually done automatically within C<ev_run ()>. |
686 | |
698 | |
687 | This function is rarely useful, but when some event callback runs for a |
699 | This function is rarely useful, but when some event callback runs for a |
688 | very long time without entering the event loop, updating libev's idea of |
700 | very long time without entering the event loop, updating libev's idea of |
689 | the current time is a good idea. |
701 | the current time is a good idea. |
690 | |
702 | |
… | |
… | |
692 | |
704 | |
693 | =item ev_suspend (loop) |
705 | =item ev_suspend (loop) |
694 | |
706 | |
695 | =item ev_resume (loop) |
707 | =item ev_resume (loop) |
696 | |
708 | |
697 | These two functions suspend and resume a loop, for use when the loop is |
709 | These two functions suspend and resume an event loop, for use when the |
698 | not used for a while and timeouts should not be processed. |
710 | loop is not used for a while and timeouts should not be processed. |
699 | |
711 | |
700 | A typical use case would be an interactive program such as a game: When |
712 | A typical use case would be an interactive program such as a game: When |
701 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
713 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
702 | would be best to handle timeouts as if no time had actually passed while |
714 | would be best to handle timeouts as if no time had actually passed while |
703 | the program was suspended. This can be achieved by calling C<ev_suspend> |
715 | the program was suspended. This can be achieved by calling C<ev_suspend> |
… | |
… | |
705 | C<ev_resume> directly afterwards to resume timer processing. |
717 | C<ev_resume> directly afterwards to resume timer processing. |
706 | |
718 | |
707 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
719 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
708 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
720 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
709 | will be rescheduled (that is, they will lose any events that would have |
721 | will be rescheduled (that is, they will lose any events that would have |
710 | occured while suspended). |
722 | occurred while suspended). |
711 | |
723 | |
712 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
724 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
713 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
725 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
714 | without a previous call to C<ev_suspend>. |
726 | without a previous call to C<ev_suspend>. |
715 | |
727 | |
716 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
728 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
717 | event loop time (see C<ev_now_update>). |
729 | event loop time (see C<ev_now_update>). |
718 | |
730 | |
719 | =item ev_loop (loop, int flags) |
731 | =item ev_run (loop, int flags) |
720 | |
732 | |
721 | Finally, this is it, the event handler. This function usually is called |
733 | Finally, this is it, the event handler. This function usually is called |
722 | after you have initialised all your watchers and you want to start |
734 | after you have initialised all your watchers and you want to start |
723 | handling events. |
735 | handling events. It will ask the operating system for any new events, call |
|
|
736 | the watcher callbacks, an then repeat the whole process indefinitely: This |
|
|
737 | is why event loops are called I<loops>. |
724 | |
738 | |
725 | If the flags argument is specified as C<0>, it will not return until |
739 | If the flags argument is specified as C<0>, it will keep handling events |
726 | either no event watchers are active anymore or C<ev_unloop> was called. |
740 | until either no event watchers are active anymore or C<ev_break> was |
|
|
741 | called. |
727 | |
742 | |
728 | Please note that an explicit C<ev_unloop> is usually better than |
743 | Please note that an explicit C<ev_break> is usually better than |
729 | relying on all watchers to be stopped when deciding when a program has |
744 | relying on all watchers to be stopped when deciding when a program has |
730 | finished (especially in interactive programs), but having a program |
745 | finished (especially in interactive programs), but having a program |
731 | that automatically loops as long as it has to and no longer by virtue |
746 | that automatically loops as long as it has to and no longer by virtue |
732 | of relying on its watchers stopping correctly, that is truly a thing of |
747 | of relying on its watchers stopping correctly, that is truly a thing of |
733 | beauty. |
748 | beauty. |
734 | |
749 | |
735 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
750 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
736 | those events and any already outstanding ones, but will not block your |
751 | those events and any already outstanding ones, but will not wait and |
737 | process in case there are no events and will return after one iteration of |
752 | block your process in case there are no events and will return after one |
738 | the loop. |
753 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
754 | events while doing lengthy calculations, to keep the program responsive. |
739 | |
755 | |
740 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
756 | A flags value of C<EVRUN_ONCE> will look for new events (waiting if |
741 | necessary) and will handle those and any already outstanding ones. It |
757 | necessary) and will handle those and any already outstanding ones. It |
742 | will block your process until at least one new event arrives (which could |
758 | will block your process until at least one new event arrives (which could |
743 | be an event internal to libev itself, so there is no guarantee that a |
759 | be an event internal to libev itself, so there is no guarantee that a |
744 | user-registered callback will be called), and will return after one |
760 | user-registered callback will be called), and will return after one |
745 | iteration of the loop. |
761 | iteration of the loop. |
746 | |
762 | |
747 | This is useful if you are waiting for some external event in conjunction |
763 | This is useful if you are waiting for some external event in conjunction |
748 | with something not expressible using other libev watchers (i.e. "roll your |
764 | with something not expressible using other libev watchers (i.e. "roll your |
749 | own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
765 | own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
750 | usually a better approach for this kind of thing. |
766 | usually a better approach for this kind of thing. |
751 | |
767 | |
752 | Here are the gory details of what C<ev_loop> does: |
768 | Here are the gory details of what C<ev_run> does: |
753 | |
769 | |
|
|
770 | - Increment loop depth. |
|
|
771 | - Reset the ev_break status. |
754 | - Before the first iteration, call any pending watchers. |
772 | - Before the first iteration, call any pending watchers. |
|
|
773 | LOOP: |
755 | * If EVFLAG_FORKCHECK was used, check for a fork. |
774 | - If EVFLAG_FORKCHECK was used, check for a fork. |
756 | - If a fork was detected (by any means), queue and call all fork watchers. |
775 | - If a fork was detected (by any means), queue and call all fork watchers. |
757 | - Queue and call all prepare watchers. |
776 | - Queue and call all prepare watchers. |
|
|
777 | - If ev_break was called, goto FINISH. |
758 | - If we have been forked, detach and recreate the kernel state |
778 | - If we have been forked, detach and recreate the kernel state |
759 | as to not disturb the other process. |
779 | as to not disturb the other process. |
760 | - Update the kernel state with all outstanding changes. |
780 | - Update the kernel state with all outstanding changes. |
761 | - Update the "event loop time" (ev_now ()). |
781 | - Update the "event loop time" (ev_now ()). |
762 | - Calculate for how long to sleep or block, if at all |
782 | - Calculate for how long to sleep or block, if at all |
763 | (active idle watchers, EVLOOP_NONBLOCK or not having |
783 | (active idle watchers, EVRUN_NOWAIT or not having |
764 | any active watchers at all will result in not sleeping). |
784 | any active watchers at all will result in not sleeping). |
765 | - Sleep if the I/O and timer collect interval say so. |
785 | - Sleep if the I/O and timer collect interval say so. |
|
|
786 | - Increment loop iteration counter. |
766 | - Block the process, waiting for any events. |
787 | - Block the process, waiting for any events. |
767 | - Queue all outstanding I/O (fd) events. |
788 | - Queue all outstanding I/O (fd) events. |
768 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
789 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
769 | - Queue all expired timers. |
790 | - Queue all expired timers. |
770 | - Queue all expired periodics. |
791 | - Queue all expired periodics. |
771 | - Unless any events are pending now, queue all idle watchers. |
792 | - Queue all idle watchers with priority higher than that of pending events. |
772 | - Queue all check watchers. |
793 | - Queue all check watchers. |
773 | - Call all queued watchers in reverse order (i.e. check watchers first). |
794 | - Call all queued watchers in reverse order (i.e. check watchers first). |
774 | Signals and child watchers are implemented as I/O watchers, and will |
795 | Signals and child watchers are implemented as I/O watchers, and will |
775 | be handled here by queueing them when their watcher gets executed. |
796 | be handled here by queueing them when their watcher gets executed. |
776 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
797 | - If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
777 | were used, or there are no active watchers, return, otherwise |
798 | were used, or there are no active watchers, goto FINISH, otherwise |
778 | continue with step *. |
799 | continue with step LOOP. |
|
|
800 | FINISH: |
|
|
801 | - Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
802 | - Decrement the loop depth. |
|
|
803 | - Return. |
779 | |
804 | |
780 | Example: Queue some jobs and then loop until no events are outstanding |
805 | Example: Queue some jobs and then loop until no events are outstanding |
781 | anymore. |
806 | anymore. |
782 | |
807 | |
783 | ... queue jobs here, make sure they register event watchers as long |
808 | ... queue jobs here, make sure they register event watchers as long |
784 | ... as they still have work to do (even an idle watcher will do..) |
809 | ... as they still have work to do (even an idle watcher will do..) |
785 | ev_loop (my_loop, 0); |
810 | ev_run (my_loop, 0); |
786 | ... jobs done or somebody called unloop. yeah! |
811 | ... jobs done or somebody called unloop. yeah! |
787 | |
812 | |
788 | =item ev_unloop (loop, how) |
813 | =item ev_break (loop, how) |
789 | |
814 | |
790 | Can be used to make a call to C<ev_loop> return early (but only after it |
815 | Can be used to make a call to C<ev_run> return early (but only after it |
791 | has processed all outstanding events). The C<how> argument must be either |
816 | has processed all outstanding events). The C<how> argument must be either |
792 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
817 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
793 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
818 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
794 | |
819 | |
795 | This "unloop state" will be cleared when entering C<ev_loop> again. |
820 | This "unloop state" will be cleared when entering C<ev_run> again. |
796 | |
821 | |
797 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
822 | It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO## |
798 | |
823 | |
799 | =item ev_ref (loop) |
824 | =item ev_ref (loop) |
800 | |
825 | |
801 | =item ev_unref (loop) |
826 | =item ev_unref (loop) |
802 | |
827 | |
803 | Ref/unref can be used to add or remove a reference count on the event |
828 | Ref/unref can be used to add or remove a reference count on the event |
804 | loop: Every watcher keeps one reference, and as long as the reference |
829 | loop: Every watcher keeps one reference, and as long as the reference |
805 | count is nonzero, C<ev_loop> will not return on its own. |
830 | count is nonzero, C<ev_run> will not return on its own. |
806 | |
831 | |
807 | This is useful when you have a watcher that you never intend to |
832 | This is useful when you have a watcher that you never intend to |
808 | unregister, but that nevertheless should not keep C<ev_loop> from |
833 | unregister, but that nevertheless should not keep C<ev_run> from |
809 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
834 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
810 | before stopping it. |
835 | before stopping it. |
811 | |
836 | |
812 | As an example, libev itself uses this for its internal signal pipe: It |
837 | As an example, libev itself uses this for its internal signal pipe: It |
813 | is not visible to the libev user and should not keep C<ev_loop> from |
838 | is not visible to the libev user and should not keep C<ev_run> from |
814 | exiting if no event watchers registered by it are active. It is also an |
839 | exiting if no event watchers registered by it are active. It is also an |
815 | excellent way to do this for generic recurring timers or from within |
840 | excellent way to do this for generic recurring timers or from within |
816 | third-party libraries. Just remember to I<unref after start> and I<ref |
841 | third-party libraries. Just remember to I<unref after start> and I<ref |
817 | before stop> (but only if the watcher wasn't active before, or was active |
842 | before stop> (but only if the watcher wasn't active before, or was active |
818 | before, respectively. Note also that libev might stop watchers itself |
843 | before, respectively. Note also that libev might stop watchers itself |
819 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
844 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
820 | in the callback). |
845 | in the callback). |
821 | |
846 | |
822 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
847 | Example: Create a signal watcher, but keep it from keeping C<ev_run> |
823 | running when nothing else is active. |
848 | running when nothing else is active. |
824 | |
849 | |
825 | ev_signal exitsig; |
850 | ev_signal exitsig; |
826 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
851 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
827 | ev_signal_start (loop, &exitsig); |
852 | ev_signal_start (loop, &exitsig); |
… | |
… | |
872 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
897 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
873 | as this approaches the timing granularity of most systems. Note that if |
898 | as this approaches the timing granularity of most systems. Note that if |
874 | you do transactions with the outside world and you can't increase the |
899 | you do transactions with the outside world and you can't increase the |
875 | parallelity, then this setting will limit your transaction rate (if you |
900 | parallelity, then this setting will limit your transaction rate (if you |
876 | need to poll once per transaction and the I/O collect interval is 0.01, |
901 | need to poll once per transaction and the I/O collect interval is 0.01, |
877 | then you can't do more than 100 transations per second). |
902 | then you can't do more than 100 transactions per second). |
878 | |
903 | |
879 | Setting the I<timeout collect interval> can improve the opportunity for |
904 | Setting the I<timeout collect interval> can improve the opportunity for |
880 | saving power, as the program will "bundle" timer callback invocations that |
905 | saving power, as the program will "bundle" timer callback invocations that |
881 | are "near" in time together, by delaying some, thus reducing the number of |
906 | are "near" in time together, by delaying some, thus reducing the number of |
882 | times the process sleeps and wakes up again. Another useful technique to |
907 | times the process sleeps and wakes up again. Another useful technique to |
… | |
… | |
890 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
915 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
891 | |
916 | |
892 | =item ev_invoke_pending (loop) |
917 | =item ev_invoke_pending (loop) |
893 | |
918 | |
894 | This call will simply invoke all pending watchers while resetting their |
919 | This call will simply invoke all pending watchers while resetting their |
895 | pending state. Normally, C<ev_loop> does this automatically when required, |
920 | pending state. Normally, C<ev_run> does this automatically when required, |
896 | but when overriding the invoke callback this call comes handy. |
921 | but when overriding the invoke callback this call comes handy. This |
|
|
922 | function can be invoked from a watcher - this can be useful for example |
|
|
923 | when you want to do some lengthy calculation and want to pass further |
|
|
924 | event handling to another thread (you still have to make sure only one |
|
|
925 | thread executes within C<ev_invoke_pending> or C<ev_run> of course). |
897 | |
926 | |
898 | =item int ev_pending_count (loop) |
927 | =item int ev_pending_count (loop) |
899 | |
928 | |
900 | Returns the number of pending watchers - zero indicates that no watchers |
929 | Returns the number of pending watchers - zero indicates that no watchers |
901 | are pending. |
930 | are pending. |
902 | |
931 | |
903 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
932 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
904 | |
933 | |
905 | This overrides the invoke pending functionality of the loop: Instead of |
934 | This overrides the invoke pending functionality of the loop: Instead of |
906 | invoking all pending watchers when there are any, C<ev_loop> will call |
935 | invoking all pending watchers when there are any, C<ev_run> will call |
907 | this callback instead. This is useful, for example, when you want to |
936 | this callback instead. This is useful, for example, when you want to |
908 | invoke the actual watchers inside another context (another thread etc.). |
937 | invoke the actual watchers inside another context (another thread etc.). |
909 | |
938 | |
910 | If you want to reset the callback, use C<ev_invoke_pending> as new |
939 | If you want to reset the callback, use C<ev_invoke_pending> as new |
911 | callback. |
940 | callback. |
… | |
… | |
914 | |
943 | |
915 | Sometimes you want to share the same loop between multiple threads. This |
944 | Sometimes you want to share the same loop between multiple threads. This |
916 | can be done relatively simply by putting mutex_lock/unlock calls around |
945 | can be done relatively simply by putting mutex_lock/unlock calls around |
917 | each call to a libev function. |
946 | each call to a libev function. |
918 | |
947 | |
919 | However, C<ev_loop> can run an indefinite time, so it is not feasible to |
948 | However, C<ev_run> can run an indefinite time, so it is not feasible |
920 | wait for it to return. One way around this is to wake up the loop via |
949 | to wait for it to return. One way around this is to wake up the event |
921 | C<ev_unloop> and C<av_async_send>, another way is to set these I<release> |
950 | loop via C<ev_break> and C<av_async_send>, another way is to set these |
922 | and I<acquire> callbacks on the loop. |
951 | I<release> and I<acquire> callbacks on the loop. |
923 | |
952 | |
924 | When set, then C<release> will be called just before the thread is |
953 | When set, then C<release> will be called just before the thread is |
925 | suspended waiting for new events, and C<acquire> is called just |
954 | suspended waiting for new events, and C<acquire> is called just |
926 | afterwards. |
955 | afterwards. |
927 | |
956 | |
… | |
… | |
930 | |
959 | |
931 | While event loop modifications are allowed between invocations of |
960 | While event loop modifications are allowed between invocations of |
932 | C<release> and C<acquire> (that's their only purpose after all), no |
961 | C<release> and C<acquire> (that's their only purpose after all), no |
933 | modifications done will affect the event loop, i.e. adding watchers will |
962 | modifications done will affect the event loop, i.e. adding watchers will |
934 | have no effect on the set of file descriptors being watched, or the time |
963 | have no effect on the set of file descriptors being watched, or the time |
935 | waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it |
964 | waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it |
936 | to take note of any changes you made. |
965 | to take note of any changes you made. |
937 | |
966 | |
938 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
967 | In theory, threads executing C<ev_run> will be async-cancel safe between |
939 | invocations of C<release> and C<acquire>. |
968 | invocations of C<release> and C<acquire>. |
940 | |
969 | |
941 | See also the locking example in the C<THREADS> section later in this |
970 | See also the locking example in the C<THREADS> section later in this |
942 | document. |
971 | document. |
943 | |
972 | |
… | |
… | |
952 | These two functions can be used to associate arbitrary data with a loop, |
981 | These two functions can be used to associate arbitrary data with a loop, |
953 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
982 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
954 | C<acquire> callbacks described above, but of course can be (ab-)used for |
983 | C<acquire> callbacks described above, but of course can be (ab-)used for |
955 | any other purpose as well. |
984 | any other purpose as well. |
956 | |
985 | |
957 | =item ev_loop_verify (loop) |
986 | =item ev_verify (loop) |
958 | |
987 | |
959 | This function only does something when C<EV_VERIFY> support has been |
988 | This function only does something when C<EV_VERIFY> support has been |
960 | compiled in, which is the default for non-minimal builds. It tries to go |
989 | compiled in, which is the default for non-minimal builds. It tries to go |
961 | through all internal structures and checks them for validity. If anything |
990 | through all internal structures and checks them for validity. If anything |
962 | is found to be inconsistent, it will print an error message to standard |
991 | is found to be inconsistent, it will print an error message to standard |
… | |
… | |
973 | |
1002 | |
974 | In the following description, uppercase C<TYPE> in names stands for the |
1003 | In the following description, uppercase C<TYPE> in names stands for the |
975 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
1004 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
976 | watchers and C<ev_io_start> for I/O watchers. |
1005 | watchers and C<ev_io_start> for I/O watchers. |
977 | |
1006 | |
978 | A watcher is a structure that you create and register to record your |
1007 | A watcher is an opaque structure that you allocate and register to record |
979 | interest in some event. For instance, if you want to wait for STDIN to |
1008 | your interest in some event. To make a concrete example, imagine you want |
980 | become readable, you would create an C<ev_io> watcher for that: |
1009 | to wait for STDIN to become readable, you would create an C<ev_io> watcher |
|
|
1010 | for that: |
981 | |
1011 | |
982 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
1012 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
983 | { |
1013 | { |
984 | ev_io_stop (w); |
1014 | ev_io_stop (w); |
985 | ev_unloop (loop, EVUNLOOP_ALL); |
1015 | ev_break (loop, EVBREAK_ALL); |
986 | } |
1016 | } |
987 | |
1017 | |
988 | struct ev_loop *loop = ev_default_loop (0); |
1018 | struct ev_loop *loop = ev_default_loop (0); |
989 | |
1019 | |
990 | ev_io stdin_watcher; |
1020 | ev_io stdin_watcher; |
991 | |
1021 | |
992 | ev_init (&stdin_watcher, my_cb); |
1022 | ev_init (&stdin_watcher, my_cb); |
993 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1023 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
994 | ev_io_start (loop, &stdin_watcher); |
1024 | ev_io_start (loop, &stdin_watcher); |
995 | |
1025 | |
996 | ev_loop (loop, 0); |
1026 | ev_run (loop, 0); |
997 | |
1027 | |
998 | As you can see, you are responsible for allocating the memory for your |
1028 | As you can see, you are responsible for allocating the memory for your |
999 | watcher structures (and it is I<usually> a bad idea to do this on the |
1029 | watcher structures (and it is I<usually> a bad idea to do this on the |
1000 | stack). |
1030 | stack). |
1001 | |
1031 | |
1002 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
1032 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
1003 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
1033 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
1004 | |
1034 | |
1005 | Each watcher structure must be initialised by a call to C<ev_init |
1035 | Each watcher structure must be initialised by a call to C<ev_init (watcher |
1006 | (watcher *, callback)>, which expects a callback to be provided. This |
1036 | *, callback)>, which expects a callback to be provided. This callback is |
1007 | callback gets invoked each time the event occurs (or, in the case of I/O |
1037 | invoked each time the event occurs (or, in the case of I/O watchers, each |
1008 | watchers, each time the event loop detects that the file descriptor given |
1038 | time the event loop detects that the file descriptor given is readable |
1009 | is readable and/or writable). |
1039 | and/or writable). |
1010 | |
1040 | |
1011 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
1041 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
1012 | macro to configure it, with arguments specific to the watcher type. There |
1042 | macro to configure it, with arguments specific to the watcher type. There |
1013 | is also a macro to combine initialisation and setting in one call: C<< |
1043 | is also a macro to combine initialisation and setting in one call: C<< |
1014 | ev_TYPE_init (watcher *, callback, ...) >>. |
1044 | ev_TYPE_init (watcher *, callback, ...) >>. |
… | |
… | |
1065 | |
1095 | |
1066 | =item C<EV_PREPARE> |
1096 | =item C<EV_PREPARE> |
1067 | |
1097 | |
1068 | =item C<EV_CHECK> |
1098 | =item C<EV_CHECK> |
1069 | |
1099 | |
1070 | All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts |
1100 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
1071 | to gather new events, and all C<ev_check> watchers are invoked just after |
1101 | to gather new events, and all C<ev_check> watchers are invoked just after |
1072 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
1102 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
1073 | received events. Callbacks of both watcher types can start and stop as |
1103 | received events. Callbacks of both watcher types can start and stop as |
1074 | many watchers as they want, and all of them will be taken into account |
1104 | many watchers as they want, and all of them will be taken into account |
1075 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1105 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1076 | C<ev_loop> from blocking). |
1106 | C<ev_run> from blocking). |
1077 | |
1107 | |
1078 | =item C<EV_EMBED> |
1108 | =item C<EV_EMBED> |
1079 | |
1109 | |
1080 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1110 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1081 | |
1111 | |
1082 | =item C<EV_FORK> |
1112 | =item C<EV_FORK> |
1083 | |
1113 | |
1084 | The event loop has been resumed in the child process after fork (see |
1114 | The event loop has been resumed in the child process after fork (see |
1085 | C<ev_fork>). |
1115 | C<ev_fork>). |
|
|
1116 | |
|
|
1117 | =item C<EV_CLEANUP> |
|
|
1118 | |
|
|
1119 | The event loop is abotu to be destroyed (see C<ev_cleanup>). |
1086 | |
1120 | |
1087 | =item C<EV_ASYNC> |
1121 | =item C<EV_ASYNC> |
1088 | |
1122 | |
1089 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1123 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1090 | |
1124 | |
… | |
… | |
1109 | example it might indicate that a fd is readable or writable, and if your |
1143 | example it might indicate that a fd is readable or writable, and if your |
1110 | callbacks is well-written it can just attempt the operation and cope with |
1144 | callbacks is well-written it can just attempt the operation and cope with |
1111 | the error from read() or write(). This will not work in multi-threaded |
1145 | the error from read() or write(). This will not work in multi-threaded |
1112 | programs, though, as the fd could already be closed and reused for another |
1146 | programs, though, as the fd could already be closed and reused for another |
1113 | thing, so beware. |
1147 | thing, so beware. |
|
|
1148 | |
|
|
1149 | =back |
|
|
1150 | |
|
|
1151 | =head2 WATCHER STATES |
|
|
1152 | |
|
|
1153 | There are various watcher states mentioned throughout this manual - |
|
|
1154 | active, pending and so on. In this section these states and the rules to |
|
|
1155 | transition between them will be described in more detail - and while these |
|
|
1156 | rules might look complicated, they usually do "the right thing". |
|
|
1157 | |
|
|
1158 | =over 4 |
|
|
1159 | |
|
|
1160 | =item initialiased |
|
|
1161 | |
|
|
1162 | Before a watcher can be registered with the event looop it has to be |
|
|
1163 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1164 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
|
|
1165 | |
|
|
1166 | In this state it is simply some block of memory that is suitable for use |
|
|
1167 | in an event loop. It can be moved around, freed, reused etc. at will. |
|
|
1168 | |
|
|
1169 | =item started/running/active |
|
|
1170 | |
|
|
1171 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
|
|
1172 | property of the event loop, and is actively waiting for events. While in |
|
|
1173 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1174 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1175 | and call libev functions on it that are documented to work on active watchers. |
|
|
1176 | |
|
|
1177 | =item pending |
|
|
1178 | |
|
|
1179 | If a watcher is active and libev determines that an event it is interested |
|
|
1180 | in has occurred (such as a timer expiring), it will become pending. It will |
|
|
1181 | stay in this pending state until either it is stopped or its callback is |
|
|
1182 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1183 | callback. |
|
|
1184 | |
|
|
1185 | The watcher might or might not be active while it is pending (for example, |
|
|
1186 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1187 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1188 | but it is still property of the event loop at this time, so cannot be |
|
|
1189 | moved, freed or reused. And if it is active the rules described in the |
|
|
1190 | previous item still apply. |
|
|
1191 | |
|
|
1192 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1193 | via C<ev_feed_event>), in which case it becomes pending without being |
|
|
1194 | active. |
|
|
1195 | |
|
|
1196 | =item stopped |
|
|
1197 | |
|
|
1198 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1199 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
|
|
1200 | latter will clear any pending state the watcher might be in, regardless |
|
|
1201 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1202 | freeing it is often a good idea. |
|
|
1203 | |
|
|
1204 | While stopped (and not pending) the watcher is essentially in the |
|
|
1205 | initialised state, that is it can be reused, moved, modified in any way |
|
|
1206 | you wish. |
1114 | |
1207 | |
1115 | =back |
1208 | =back |
1116 | |
1209 | |
1117 | =head2 GENERIC WATCHER FUNCTIONS |
1210 | =head2 GENERIC WATCHER FUNCTIONS |
1118 | |
1211 | |
… | |
… | |
1380 | |
1473 | |
1381 | For example, to emulate how many other event libraries handle priorities, |
1474 | For example, to emulate how many other event libraries handle priorities, |
1382 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1475 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1383 | the normal watcher callback, you just start the idle watcher. The real |
1476 | the normal watcher callback, you just start the idle watcher. The real |
1384 | processing is done in the idle watcher callback. This causes libev to |
1477 | processing is done in the idle watcher callback. This causes libev to |
1385 | continously poll and process kernel event data for the watcher, but when |
1478 | continuously poll and process kernel event data for the watcher, but when |
1386 | the lock-out case is known to be rare (which in turn is rare :), this is |
1479 | the lock-out case is known to be rare (which in turn is rare :), this is |
1387 | workable. |
1480 | workable. |
1388 | |
1481 | |
1389 | Usually, however, the lock-out model implemented that way will perform |
1482 | Usually, however, the lock-out model implemented that way will perform |
1390 | miserably under the type of load it was designed to handle. In that case, |
1483 | miserably under the type of load it was designed to handle. In that case, |
… | |
… | |
1404 | { |
1497 | { |
1405 | // stop the I/O watcher, we received the event, but |
1498 | // stop the I/O watcher, we received the event, but |
1406 | // are not yet ready to handle it. |
1499 | // are not yet ready to handle it. |
1407 | ev_io_stop (EV_A_ w); |
1500 | ev_io_stop (EV_A_ w); |
1408 | |
1501 | |
1409 | // start the idle watcher to ahndle the actual event. |
1502 | // start the idle watcher to handle the actual event. |
1410 | // it will not be executed as long as other watchers |
1503 | // it will not be executed as long as other watchers |
1411 | // with the default priority are receiving events. |
1504 | // with the default priority are receiving events. |
1412 | ev_idle_start (EV_A_ &idle); |
1505 | ev_idle_start (EV_A_ &idle); |
1413 | } |
1506 | } |
1414 | |
1507 | |
… | |
… | |
1468 | |
1561 | |
1469 | If you cannot use non-blocking mode, then force the use of a |
1562 | If you cannot use non-blocking mode, then force the use of a |
1470 | known-to-be-good backend (at the time of this writing, this includes only |
1563 | known-to-be-good backend (at the time of this writing, this includes only |
1471 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1564 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1472 | descriptors for which non-blocking operation makes no sense (such as |
1565 | descriptors for which non-blocking operation makes no sense (such as |
1473 | files) - libev doesn't guarentee any specific behaviour in that case. |
1566 | files) - libev doesn't guarantee any specific behaviour in that case. |
1474 | |
1567 | |
1475 | Another thing you have to watch out for is that it is quite easy to |
1568 | Another thing you have to watch out for is that it is quite easy to |
1476 | receive "spurious" readiness notifications, that is your callback might |
1569 | receive "spurious" readiness notifications, that is your callback might |
1477 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1570 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1478 | because there is no data. Not only are some backends known to create a |
1571 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1622 | ... |
1715 | ... |
1623 | struct ev_loop *loop = ev_default_init (0); |
1716 | struct ev_loop *loop = ev_default_init (0); |
1624 | ev_io stdin_readable; |
1717 | ev_io stdin_readable; |
1625 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1718 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1626 | ev_io_start (loop, &stdin_readable); |
1719 | ev_io_start (loop, &stdin_readable); |
1627 | ev_loop (loop, 0); |
1720 | ev_run (loop, 0); |
1628 | |
1721 | |
1629 | |
1722 | |
1630 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1723 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1631 | |
1724 | |
1632 | Timer watchers are simple relative timers that generate an event after a |
1725 | Timer watchers are simple relative timers that generate an event after a |
… | |
… | |
1641 | The callback is guaranteed to be invoked only I<after> its timeout has |
1734 | The callback is guaranteed to be invoked only I<after> its timeout has |
1642 | passed (not I<at>, so on systems with very low-resolution clocks this |
1735 | passed (not I<at>, so on systems with very low-resolution clocks this |
1643 | might introduce a small delay). If multiple timers become ready during the |
1736 | might introduce a small delay). If multiple timers become ready during the |
1644 | same loop iteration then the ones with earlier time-out values are invoked |
1737 | same loop iteration then the ones with earlier time-out values are invoked |
1645 | before ones of the same priority with later time-out values (but this is |
1738 | before ones of the same priority with later time-out values (but this is |
1646 | no longer true when a callback calls C<ev_loop> recursively). |
1739 | no longer true when a callback calls C<ev_run> recursively). |
1647 | |
1740 | |
1648 | =head3 Be smart about timeouts |
1741 | =head3 Be smart about timeouts |
1649 | |
1742 | |
1650 | Many real-world problems involve some kind of timeout, usually for error |
1743 | Many real-world problems involve some kind of timeout, usually for error |
1651 | recovery. A typical example is an HTTP request - if the other side hangs, |
1744 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
1737 | ev_tstamp timeout = last_activity + 60.; |
1830 | ev_tstamp timeout = last_activity + 60.; |
1738 | |
1831 | |
1739 | // if last_activity + 60. is older than now, we did time out |
1832 | // if last_activity + 60. is older than now, we did time out |
1740 | if (timeout < now) |
1833 | if (timeout < now) |
1741 | { |
1834 | { |
1742 | // timeout occured, take action |
1835 | // timeout occurred, take action |
1743 | } |
1836 | } |
1744 | else |
1837 | else |
1745 | { |
1838 | { |
1746 | // callback was invoked, but there was some activity, re-arm |
1839 | // callback was invoked, but there was some activity, re-arm |
1747 | // the watcher to fire in last_activity + 60, which is |
1840 | // the watcher to fire in last_activity + 60, which is |
… | |
… | |
1822 | |
1915 | |
1823 | =head3 The special problem of time updates |
1916 | =head3 The special problem of time updates |
1824 | |
1917 | |
1825 | Establishing the current time is a costly operation (it usually takes at |
1918 | Establishing the current time is a costly operation (it usually takes at |
1826 | least two system calls): EV therefore updates its idea of the current |
1919 | least two system calls): EV therefore updates its idea of the current |
1827 | time only before and after C<ev_loop> collects new events, which causes a |
1920 | time only before and after C<ev_run> collects new events, which causes a |
1828 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1921 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1829 | lots of events in one iteration. |
1922 | lots of events in one iteration. |
1830 | |
1923 | |
1831 | The relative timeouts are calculated relative to the C<ev_now ()> |
1924 | The relative timeouts are calculated relative to the C<ev_now ()> |
1832 | time. This is usually the right thing as this timestamp refers to the time |
1925 | time. This is usually the right thing as this timestamp refers to the time |
… | |
… | |
1949 | } |
2042 | } |
1950 | |
2043 | |
1951 | ev_timer mytimer; |
2044 | ev_timer mytimer; |
1952 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2045 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1953 | ev_timer_again (&mytimer); /* start timer */ |
2046 | ev_timer_again (&mytimer); /* start timer */ |
1954 | ev_loop (loop, 0); |
2047 | ev_run (loop, 0); |
1955 | |
2048 | |
1956 | // and in some piece of code that gets executed on any "activity": |
2049 | // and in some piece of code that gets executed on any "activity": |
1957 | // reset the timeout to start ticking again at 10 seconds |
2050 | // reset the timeout to start ticking again at 10 seconds |
1958 | ev_timer_again (&mytimer); |
2051 | ev_timer_again (&mytimer); |
1959 | |
2052 | |
… | |
… | |
1985 | |
2078 | |
1986 | As with timers, the callback is guaranteed to be invoked only when the |
2079 | As with timers, the callback is guaranteed to be invoked only when the |
1987 | point in time where it is supposed to trigger has passed. If multiple |
2080 | point in time where it is supposed to trigger has passed. If multiple |
1988 | timers become ready during the same loop iteration then the ones with |
2081 | timers become ready during the same loop iteration then the ones with |
1989 | earlier time-out values are invoked before ones with later time-out values |
2082 | earlier time-out values are invoked before ones with later time-out values |
1990 | (but this is no longer true when a callback calls C<ev_loop> recursively). |
2083 | (but this is no longer true when a callback calls C<ev_run> recursively). |
1991 | |
2084 | |
1992 | =head3 Watcher-Specific Functions and Data Members |
2085 | =head3 Watcher-Specific Functions and Data Members |
1993 | |
2086 | |
1994 | =over 4 |
2087 | =over 4 |
1995 | |
2088 | |
… | |
… | |
2123 | Example: Call a callback every hour, or, more precisely, whenever the |
2216 | Example: Call a callback every hour, or, more precisely, whenever the |
2124 | system time is divisible by 3600. The callback invocation times have |
2217 | system time is divisible by 3600. The callback invocation times have |
2125 | potentially a lot of jitter, but good long-term stability. |
2218 | potentially a lot of jitter, but good long-term stability. |
2126 | |
2219 | |
2127 | static void |
2220 | static void |
2128 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2221 | clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
2129 | { |
2222 | { |
2130 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2223 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2131 | } |
2224 | } |
2132 | |
2225 | |
2133 | ev_periodic hourly_tick; |
2226 | ev_periodic hourly_tick; |
… | |
… | |
2233 | Example: Try to exit cleanly on SIGINT. |
2326 | Example: Try to exit cleanly on SIGINT. |
2234 | |
2327 | |
2235 | static void |
2328 | static void |
2236 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2329 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2237 | { |
2330 | { |
2238 | ev_unloop (loop, EVUNLOOP_ALL); |
2331 | ev_break (loop, EVBREAK_ALL); |
2239 | } |
2332 | } |
2240 | |
2333 | |
2241 | ev_signal signal_watcher; |
2334 | ev_signal signal_watcher; |
2242 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2335 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2243 | ev_signal_start (loop, &signal_watcher); |
2336 | ev_signal_start (loop, &signal_watcher); |
… | |
… | |
2629 | |
2722 | |
2630 | Prepare and check watchers are usually (but not always) used in pairs: |
2723 | Prepare and check watchers are usually (but not always) used in pairs: |
2631 | prepare watchers get invoked before the process blocks and check watchers |
2724 | prepare watchers get invoked before the process blocks and check watchers |
2632 | afterwards. |
2725 | afterwards. |
2633 | |
2726 | |
2634 | You I<must not> call C<ev_loop> or similar functions that enter |
2727 | You I<must not> call C<ev_run> or similar functions that enter |
2635 | the current event loop from either C<ev_prepare> or C<ev_check> |
2728 | the current event loop from either C<ev_prepare> or C<ev_check> |
2636 | watchers. Other loops than the current one are fine, however. The |
2729 | watchers. Other loops than the current one are fine, however. The |
2637 | rationale behind this is that you do not need to check for recursion in |
2730 | rationale behind this is that you do not need to check for recursion in |
2638 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2731 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2639 | C<ev_check> so if you have one watcher of each kind they will always be |
2732 | C<ev_check> so if you have one watcher of each kind they will always be |
… | |
… | |
2807 | |
2900 | |
2808 | if (timeout >= 0) |
2901 | if (timeout >= 0) |
2809 | // create/start timer |
2902 | // create/start timer |
2810 | |
2903 | |
2811 | // poll |
2904 | // poll |
2812 | ev_loop (EV_A_ 0); |
2905 | ev_run (EV_A_ 0); |
2813 | |
2906 | |
2814 | // stop timer again |
2907 | // stop timer again |
2815 | if (timeout >= 0) |
2908 | if (timeout >= 0) |
2816 | ev_timer_stop (EV_A_ &to); |
2909 | ev_timer_stop (EV_A_ &to); |
2817 | |
2910 | |
… | |
… | |
2895 | if you do not want that, you need to temporarily stop the embed watcher). |
2988 | if you do not want that, you need to temporarily stop the embed watcher). |
2896 | |
2989 | |
2897 | =item ev_embed_sweep (loop, ev_embed *) |
2990 | =item ev_embed_sweep (loop, ev_embed *) |
2898 | |
2991 | |
2899 | Make a single, non-blocking sweep over the embedded loop. This works |
2992 | Make a single, non-blocking sweep over the embedded loop. This works |
2900 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
2993 | similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most |
2901 | appropriate way for embedded loops. |
2994 | appropriate way for embedded loops. |
2902 | |
2995 | |
2903 | =item struct ev_loop *other [read-only] |
2996 | =item struct ev_loop *other [read-only] |
2904 | |
2997 | |
2905 | The embedded event loop. |
2998 | The embedded event loop. |
… | |
… | |
2965 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3058 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2966 | handlers will be invoked, too, of course. |
3059 | handlers will be invoked, too, of course. |
2967 | |
3060 | |
2968 | =head3 The special problem of life after fork - how is it possible? |
3061 | =head3 The special problem of life after fork - how is it possible? |
2969 | |
3062 | |
2970 | Most uses of C<fork()> consist of forking, then some simple calls to ste |
3063 | Most uses of C<fork()> consist of forking, then some simple calls to set |
2971 | up/change the process environment, followed by a call to C<exec()>. This |
3064 | up/change the process environment, followed by a call to C<exec()>. This |
2972 | sequence should be handled by libev without any problems. |
3065 | sequence should be handled by libev without any problems. |
2973 | |
3066 | |
2974 | This changes when the application actually wants to do event handling |
3067 | This changes when the application actually wants to do event handling |
2975 | in the child, or both parent in child, in effect "continuing" after the |
3068 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
2991 | disadvantage of having to use multiple event loops (which do not support |
3084 | disadvantage of having to use multiple event loops (which do not support |
2992 | signal watchers). |
3085 | signal watchers). |
2993 | |
3086 | |
2994 | When this is not possible, or you want to use the default loop for |
3087 | When this is not possible, or you want to use the default loop for |
2995 | other reasons, then in the process that wants to start "fresh", call |
3088 | other reasons, then in the process that wants to start "fresh", call |
2996 | C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying |
3089 | C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>. |
2997 | the default loop will "orphan" (not stop) all registered watchers, so you |
3090 | Destroying the default loop will "orphan" (not stop) all registered |
2998 | have to be careful not to execute code that modifies those watchers. Note |
3091 | watchers, so you have to be careful not to execute code that modifies |
2999 | also that in that case, you have to re-register any signal watchers. |
3092 | those watchers. Note also that in that case, you have to re-register any |
|
|
3093 | signal watchers. |
3000 | |
3094 | |
3001 | =head3 Watcher-Specific Functions and Data Members |
3095 | =head3 Watcher-Specific Functions and Data Members |
3002 | |
3096 | |
3003 | =over 4 |
3097 | =over 4 |
3004 | |
3098 | |
3005 | =item ev_fork_init (ev_signal *, callback) |
3099 | =item ev_fork_init (ev_fork *, callback) |
3006 | |
3100 | |
3007 | Initialises and configures the fork watcher - it has no parameters of any |
3101 | Initialises and configures the fork watcher - it has no parameters of any |
3008 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
3102 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
3009 | believe me. |
3103 | believe me. |
3010 | |
3104 | |
3011 | =back |
3105 | =back |
3012 | |
3106 | |
3013 | |
3107 | |
|
|
3108 | =head2 C<ev_cleanup> - even the best things end |
|
|
3109 | |
|
|
3110 | Cleanup watchers are called just before the event loop they are registered |
|
|
3111 | with is being destroyed. |
|
|
3112 | |
|
|
3113 | While there is no guarantee that the event loop gets destroyed, cleanup |
|
|
3114 | watchers provide a convenient method to install cleanup hooks for your |
|
|
3115 | program, worker threads and so on - you just to make sure to destroy the |
|
|
3116 | loop when you want them to be invoked. |
|
|
3117 | |
|
|
3118 | Cleanup watchers are invoked in the same way as any other watcher. Unlike |
|
|
3119 | all other watchers, they do not keep a reference to the event loop (which |
|
|
3120 | makes a lot of sense if you think about it). Like all other watchers, you |
|
|
3121 | can call libev functions in the callback, except C<ev_cleanup_start>. |
|
|
3122 | |
|
|
3123 | =head3 Watcher-Specific Functions and Data Members |
|
|
3124 | |
|
|
3125 | =over 4 |
|
|
3126 | |
|
|
3127 | =item ev_cleanup_init (ev_cleanup *, callback) |
|
|
3128 | |
|
|
3129 | Initialises and configures the cleanup watcher - it has no parameters of |
|
|
3130 | any kind. There is a C<ev_cleanup_set> macro, but using it is utterly |
|
|
3131 | pointless, believe me. |
|
|
3132 | |
|
|
3133 | =back |
|
|
3134 | |
|
|
3135 | Example: Register an atexit handler to destroy the default loop, so any |
|
|
3136 | cleanup functions are called. |
|
|
3137 | |
|
|
3138 | static void |
|
|
3139 | program_exits (void) |
|
|
3140 | { |
|
|
3141 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
3142 | } |
|
|
3143 | |
|
|
3144 | ... |
|
|
3145 | atexit (program_exits); |
|
|
3146 | |
|
|
3147 | |
3014 | =head2 C<ev_async> - how to wake up another event loop |
3148 | =head2 C<ev_async> - how to wake up an event loop |
3015 | |
3149 | |
3016 | In general, you cannot use an C<ev_loop> from multiple threads or other |
3150 | In general, you cannot use an C<ev_run> from multiple threads or other |
3017 | asynchronous sources such as signal handlers (as opposed to multiple event |
3151 | asynchronous sources such as signal handlers (as opposed to multiple event |
3018 | loops - those are of course safe to use in different threads). |
3152 | loops - those are of course safe to use in different threads). |
3019 | |
3153 | |
3020 | Sometimes, however, you need to wake up another event loop you do not |
3154 | Sometimes, however, you need to wake up an event loop you do not control, |
3021 | control, for example because it belongs to another thread. This is what |
3155 | for example because it belongs to another thread. This is what C<ev_async> |
3022 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
3156 | watchers do: as long as the C<ev_async> watcher is active, you can signal |
3023 | can signal it by calling C<ev_async_send>, which is thread- and signal |
3157 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3024 | safe. |
|
|
3025 | |
3158 | |
3026 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3159 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3027 | too, are asynchronous in nature, and signals, too, will be compressed |
3160 | too, are asynchronous in nature, and signals, too, will be compressed |
3028 | (i.e. the number of callback invocations may be less than the number of |
3161 | (i.e. the number of callback invocations may be less than the number of |
3029 | C<ev_async_sent> calls). |
3162 | C<ev_async_sent> calls). |
… | |
… | |
3341 | myclass obj; |
3474 | myclass obj; |
3342 | ev::io iow; |
3475 | ev::io iow; |
3343 | iow.set <myclass, &myclass::io_cb> (&obj); |
3476 | iow.set <myclass, &myclass::io_cb> (&obj); |
3344 | |
3477 | |
3345 | =item w->set (object *) |
3478 | =item w->set (object *) |
3346 | |
|
|
3347 | This is an B<experimental> feature that might go away in a future version. |
|
|
3348 | |
3479 | |
3349 | This is a variation of a method callback - leaving out the method to call |
3480 | This is a variation of a method callback - leaving out the method to call |
3350 | will default the method to C<operator ()>, which makes it possible to use |
3481 | will default the method to C<operator ()>, which makes it possible to use |
3351 | functor objects without having to manually specify the C<operator ()> all |
3482 | functor objects without having to manually specify the C<operator ()> all |
3352 | the time. Incidentally, you can then also leave out the template argument |
3483 | the time. Incidentally, you can then also leave out the template argument |
… | |
… | |
3392 | Associates a different C<struct ev_loop> with this watcher. You can only |
3523 | Associates a different C<struct ev_loop> with this watcher. You can only |
3393 | do this when the watcher is inactive (and not pending either). |
3524 | do this when the watcher is inactive (and not pending either). |
3394 | |
3525 | |
3395 | =item w->set ([arguments]) |
3526 | =item w->set ([arguments]) |
3396 | |
3527 | |
3397 | Basically the same as C<ev_TYPE_set>, with the same arguments. Must be |
3528 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
3398 | called at least once. Unlike the C counterpart, an active watcher gets |
3529 | method or a suitable start method must be called at least once. Unlike the |
3399 | automatically stopped and restarted when reconfiguring it with this |
3530 | C counterpart, an active watcher gets automatically stopped and restarted |
3400 | method. |
3531 | when reconfiguring it with this method. |
3401 | |
3532 | |
3402 | =item w->start () |
3533 | =item w->start () |
3403 | |
3534 | |
3404 | Starts the watcher. Note that there is no C<loop> argument, as the |
3535 | Starts the watcher. Note that there is no C<loop> argument, as the |
3405 | constructor already stores the event loop. |
3536 | constructor already stores the event loop. |
3406 | |
3537 | |
|
|
3538 | =item w->start ([arguments]) |
|
|
3539 | |
|
|
3540 | Instead of calling C<set> and C<start> methods separately, it is often |
|
|
3541 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
3542 | the configure C<set> method of the watcher. |
|
|
3543 | |
3407 | =item w->stop () |
3544 | =item w->stop () |
3408 | |
3545 | |
3409 | Stops the watcher if it is active. Again, no C<loop> argument. |
3546 | Stops the watcher if it is active. Again, no C<loop> argument. |
3410 | |
3547 | |
3411 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
3548 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
… | |
… | |
3423 | |
3560 | |
3424 | =back |
3561 | =back |
3425 | |
3562 | |
3426 | =back |
3563 | =back |
3427 | |
3564 | |
3428 | Example: Define a class with an IO and idle watcher, start one of them in |
3565 | Example: Define a class with two I/O and idle watchers, start the I/O |
3429 | the constructor. |
3566 | watchers in the constructor. |
3430 | |
3567 | |
3431 | class myclass |
3568 | class myclass |
3432 | { |
3569 | { |
3433 | ev::io io ; void io_cb (ev::io &w, int revents); |
3570 | ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
3571 | ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
3434 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3572 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3435 | |
3573 | |
3436 | myclass (int fd) |
3574 | myclass (int fd) |
3437 | { |
3575 | { |
3438 | io .set <myclass, &myclass::io_cb > (this); |
3576 | io .set <myclass, &myclass::io_cb > (this); |
|
|
3577 | io2 .set <myclass, &myclass::io2_cb > (this); |
3439 | idle.set <myclass, &myclass::idle_cb> (this); |
3578 | idle.set <myclass, &myclass::idle_cb> (this); |
3440 | |
3579 | |
3441 | io.start (fd, ev::READ); |
3580 | io.set (fd, ev::WRITE); // configure the watcher |
|
|
3581 | io.start (); // start it whenever convenient |
|
|
3582 | |
|
|
3583 | io2.start (fd, ev::READ); // set + start in one call |
3442 | } |
3584 | } |
3443 | }; |
3585 | }; |
3444 | |
3586 | |
3445 | |
3587 | |
3446 | =head1 OTHER LANGUAGE BINDINGS |
3588 | =head1 OTHER LANGUAGE BINDINGS |
… | |
… | |
3520 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3662 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3521 | C<EV_A_> is used when other arguments are following. Example: |
3663 | C<EV_A_> is used when other arguments are following. Example: |
3522 | |
3664 | |
3523 | ev_unref (EV_A); |
3665 | ev_unref (EV_A); |
3524 | ev_timer_add (EV_A_ watcher); |
3666 | ev_timer_add (EV_A_ watcher); |
3525 | ev_loop (EV_A_ 0); |
3667 | ev_run (EV_A_ 0); |
3526 | |
3668 | |
3527 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3669 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3528 | which is often provided by the following macro. |
3670 | which is often provided by the following macro. |
3529 | |
3671 | |
3530 | =item C<EV_P>, C<EV_P_> |
3672 | =item C<EV_P>, C<EV_P_> |
… | |
… | |
3570 | } |
3712 | } |
3571 | |
3713 | |
3572 | ev_check check; |
3714 | ev_check check; |
3573 | ev_check_init (&check, check_cb); |
3715 | ev_check_init (&check, check_cb); |
3574 | ev_check_start (EV_DEFAULT_ &check); |
3716 | ev_check_start (EV_DEFAULT_ &check); |
3575 | ev_loop (EV_DEFAULT_ 0); |
3717 | ev_run (EV_DEFAULT_ 0); |
3576 | |
3718 | |
3577 | =head1 EMBEDDING |
3719 | =head1 EMBEDDING |
3578 | |
3720 | |
3579 | Libev can (and often is) directly embedded into host |
3721 | Libev can (and often is) directly embedded into host |
3580 | applications. Examples of applications that embed it include the Deliantra |
3722 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3671 | to a compiled library. All other symbols change the ABI, which means all |
3813 | to a compiled library. All other symbols change the ABI, which means all |
3672 | users of libev and the libev code itself must be compiled with compatible |
3814 | users of libev and the libev code itself must be compiled with compatible |
3673 | settings. |
3815 | settings. |
3674 | |
3816 | |
3675 | =over 4 |
3817 | =over 4 |
|
|
3818 | |
|
|
3819 | =item EV_COMPAT3 (h) |
|
|
3820 | |
|
|
3821 | Backwards compatibility is a major concern for libev. This is why this |
|
|
3822 | release of libev comes with wrappers for the functions and symbols that |
|
|
3823 | have been renamed between libev version 3 and 4. |
|
|
3824 | |
|
|
3825 | You can disable these wrappers (to test compatibility with future |
|
|
3826 | versions) by defining C<EV_COMPAT3> to C<0> when compiling your |
|
|
3827 | sources. This has the additional advantage that you can drop the C<struct> |
|
|
3828 | from C<struct ev_loop> declarations, as libev will provide an C<ev_loop> |
|
|
3829 | typedef in that case. |
|
|
3830 | |
|
|
3831 | In some future version, the default for C<EV_COMPAT3> will become C<0>, |
|
|
3832 | and in some even more future version the compatibility code will be |
|
|
3833 | removed completely. |
3676 | |
3834 | |
3677 | =item EV_STANDALONE (h) |
3835 | =item EV_STANDALONE (h) |
3678 | |
3836 | |
3679 | Must always be C<1> if you do not use autoconf configuration, which |
3837 | Must always be C<1> if you do not use autoconf configuration, which |
3680 | keeps libev from including F<config.h>, and it also defines dummy |
3838 | keeps libev from including F<config.h>, and it also defines dummy |
… | |
… | |
3887 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
4045 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
3888 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
4046 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3889 | |
4047 | |
3890 | If undefined or defined to be C<1> (and the platform supports it), then |
4048 | If undefined or defined to be C<1> (and the platform supports it), then |
3891 | the respective watcher type is supported. If defined to be C<0>, then it |
4049 | the respective watcher type is supported. If defined to be C<0>, then it |
3892 | is not. Disabling watcher types mainly saves codesize. |
4050 | is not. Disabling watcher types mainly saves code size. |
3893 | |
4051 | |
3894 | =item EV_FEATURES |
4052 | =item EV_FEATURES |
3895 | |
4053 | |
3896 | If you need to shave off some kilobytes of code at the expense of some |
4054 | If you need to shave off some kilobytes of code at the expense of some |
3897 | speed (but with the full API), you can define this symbol to request |
4055 | speed (but with the full API), you can define this symbol to request |
… | |
… | |
3917 | |
4075 | |
3918 | =item C<1> - faster/larger code |
4076 | =item C<1> - faster/larger code |
3919 | |
4077 | |
3920 | Use larger code to speed up some operations. |
4078 | Use larger code to speed up some operations. |
3921 | |
4079 | |
3922 | Currently this is used to override some inlining decisions (enlarging the roughly |
4080 | Currently this is used to override some inlining decisions (enlarging the |
3923 | 30% code size on amd64. |
4081 | code size by roughly 30% on amd64). |
3924 | |
4082 | |
3925 | When optimising for size, use of compiler flags such as C<-Os> with |
4083 | When optimising for size, use of compiler flags such as C<-Os> with |
3926 | gcc recommended, as well as C<-DNDEBUG>, as libev contains a number of |
4084 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
3927 | assertions. |
4085 | assertions. |
3928 | |
4086 | |
3929 | =item C<2> - faster/larger data structures |
4087 | =item C<2> - faster/larger data structures |
3930 | |
4088 | |
3931 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
4089 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
3932 | hash table sizes and so on. This will usually further increase codesize |
4090 | hash table sizes and so on. This will usually further increase code size |
3933 | and can additionally have an effect on the size of data structures at |
4091 | and can additionally have an effect on the size of data structures at |
3934 | runtime. |
4092 | runtime. |
3935 | |
4093 | |
3936 | =item C<4> - full API configuration |
4094 | =item C<4> - full API configuration |
3937 | |
4095 | |
… | |
… | |
3974 | I/O watcher then might come out at only 5Kb. |
4132 | I/O watcher then might come out at only 5Kb. |
3975 | |
4133 | |
3976 | =item EV_AVOID_STDIO |
4134 | =item EV_AVOID_STDIO |
3977 | |
4135 | |
3978 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
4136 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
3979 | functions (printf, scanf, perror etc.). This will increase the codesize |
4137 | functions (printf, scanf, perror etc.). This will increase the code size |
3980 | somewhat, but if your program doesn't otherwise depend on stdio and your |
4138 | somewhat, but if your program doesn't otherwise depend on stdio and your |
3981 | libc allows it, this avoids linking in the stdio library which is quite |
4139 | libc allows it, this avoids linking in the stdio library which is quite |
3982 | big. |
4140 | big. |
3983 | |
4141 | |
3984 | Note that error messages might become less precise when this option is |
4142 | Note that error messages might become less precise when this option is |
… | |
… | |
3988 | |
4146 | |
3989 | The highest supported signal number, +1 (or, the number of |
4147 | The highest supported signal number, +1 (or, the number of |
3990 | signals): Normally, libev tries to deduce the maximum number of signals |
4148 | signals): Normally, libev tries to deduce the maximum number of signals |
3991 | automatically, but sometimes this fails, in which case it can be |
4149 | automatically, but sometimes this fails, in which case it can be |
3992 | specified. Also, using a lower number than detected (C<32> should be |
4150 | specified. Also, using a lower number than detected (C<32> should be |
3993 | good for about any system in existance) can save some memory, as libev |
4151 | good for about any system in existence) can save some memory, as libev |
3994 | statically allocates some 12-24 bytes per signal number. |
4152 | statically allocates some 12-24 bytes per signal number. |
3995 | |
4153 | |
3996 | =item EV_PID_HASHSIZE |
4154 | =item EV_PID_HASHSIZE |
3997 | |
4155 | |
3998 | C<ev_child> watchers use a small hash table to distribute workload by |
4156 | C<ev_child> watchers use a small hash table to distribute workload by |
… | |
… | |
4030 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
4188 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
4031 | will be C<0>. |
4189 | will be C<0>. |
4032 | |
4190 | |
4033 | =item EV_VERIFY |
4191 | =item EV_VERIFY |
4034 | |
4192 | |
4035 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4193 | Controls how much internal verification (see C<ev_verify ()>) will |
4036 | be done: If set to C<0>, no internal verification code will be compiled |
4194 | be done: If set to C<0>, no internal verification code will be compiled |
4037 | in. If set to C<1>, then verification code will be compiled in, but not |
4195 | in. If set to C<1>, then verification code will be compiled in, but not |
4038 | called. If set to C<2>, then the internal verification code will be |
4196 | called. If set to C<2>, then the internal verification code will be |
4039 | called once per loop, which can slow down libev. If set to C<3>, then the |
4197 | called once per loop, which can slow down libev. If set to C<3>, then the |
4040 | verification code will be called very frequently, which will slow down |
4198 | verification code will be called very frequently, which will slow down |
… | |
… | |
4044 | will be C<0>. |
4202 | will be C<0>. |
4045 | |
4203 | |
4046 | =item EV_COMMON |
4204 | =item EV_COMMON |
4047 | |
4205 | |
4048 | By default, all watchers have a C<void *data> member. By redefining |
4206 | By default, all watchers have a C<void *data> member. By redefining |
4049 | this macro to a something else you can include more and other types of |
4207 | this macro to something else you can include more and other types of |
4050 | members. You have to define it each time you include one of the files, |
4208 | members. You have to define it each time you include one of the files, |
4051 | though, and it must be identical each time. |
4209 | though, and it must be identical each time. |
4052 | |
4210 | |
4053 | For example, the perl EV module uses something like this: |
4211 | For example, the perl EV module uses something like this: |
4054 | |
4212 | |
… | |
… | |
4255 | userdata *u = ev_userdata (EV_A); |
4413 | userdata *u = ev_userdata (EV_A); |
4256 | pthread_mutex_lock (&u->lock); |
4414 | pthread_mutex_lock (&u->lock); |
4257 | } |
4415 | } |
4258 | |
4416 | |
4259 | The event loop thread first acquires the mutex, and then jumps straight |
4417 | The event loop thread first acquires the mutex, and then jumps straight |
4260 | into C<ev_loop>: |
4418 | into C<ev_run>: |
4261 | |
4419 | |
4262 | void * |
4420 | void * |
4263 | l_run (void *thr_arg) |
4421 | l_run (void *thr_arg) |
4264 | { |
4422 | { |
4265 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4423 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4266 | |
4424 | |
4267 | l_acquire (EV_A); |
4425 | l_acquire (EV_A); |
4268 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4426 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4269 | ev_loop (EV_A_ 0); |
4427 | ev_run (EV_A_ 0); |
4270 | l_release (EV_A); |
4428 | l_release (EV_A); |
4271 | |
4429 | |
4272 | return 0; |
4430 | return 0; |
4273 | } |
4431 | } |
4274 | |
4432 | |
… | |
… | |
4326 | |
4484 | |
4327 | =head3 COROUTINES |
4485 | =head3 COROUTINES |
4328 | |
4486 | |
4329 | Libev is very accommodating to coroutines ("cooperative threads"): |
4487 | Libev is very accommodating to coroutines ("cooperative threads"): |
4330 | libev fully supports nesting calls to its functions from different |
4488 | libev fully supports nesting calls to its functions from different |
4331 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4489 | coroutines (e.g. you can call C<ev_run> on the same loop from two |
4332 | different coroutines, and switch freely between both coroutines running |
4490 | different coroutines, and switch freely between both coroutines running |
4333 | the loop, as long as you don't confuse yourself). The only exception is |
4491 | the loop, as long as you don't confuse yourself). The only exception is |
4334 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4492 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4335 | |
4493 | |
4336 | Care has been taken to ensure that libev does not keep local state inside |
4494 | Care has been taken to ensure that libev does not keep local state inside |
4337 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4495 | C<ev_run>, and other calls do not usually allow for coroutine switches as |
4338 | they do not call any callbacks. |
4496 | they do not call any callbacks. |
4339 | |
4497 | |
4340 | =head2 COMPILER WARNINGS |
4498 | =head2 COMPILER WARNINGS |
4341 | |
4499 | |
4342 | Depending on your compiler and compiler settings, you might get no or a |
4500 | Depending on your compiler and compiler settings, you might get no or a |
… | |
… | |
4353 | maintainable. |
4511 | maintainable. |
4354 | |
4512 | |
4355 | And of course, some compiler warnings are just plain stupid, or simply |
4513 | And of course, some compiler warnings are just plain stupid, or simply |
4356 | wrong (because they don't actually warn about the condition their message |
4514 | wrong (because they don't actually warn about the condition their message |
4357 | seems to warn about). For example, certain older gcc versions had some |
4515 | seems to warn about). For example, certain older gcc versions had some |
4358 | warnings that resulted an extreme number of false positives. These have |
4516 | warnings that resulted in an extreme number of false positives. These have |
4359 | been fixed, but some people still insist on making code warn-free with |
4517 | been fixed, but some people still insist on making code warn-free with |
4360 | such buggy versions. |
4518 | such buggy versions. |
4361 | |
4519 | |
4362 | While libev is written to generate as few warnings as possible, |
4520 | While libev is written to generate as few warnings as possible, |
4363 | "warn-free" code is not a goal, and it is recommended not to build libev |
4521 | "warn-free" code is not a goal, and it is recommended not to build libev |
… | |
… | |
4399 | I suggest using suppression lists. |
4557 | I suggest using suppression lists. |
4400 | |
4558 | |
4401 | |
4559 | |
4402 | =head1 PORTABILITY NOTES |
4560 | =head1 PORTABILITY NOTES |
4403 | |
4561 | |
|
|
4562 | =head2 GNU/LINUX 32 BIT LIMITATIONS |
|
|
4563 | |
|
|
4564 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
4565 | interfaces but I<disables> them by default. |
|
|
4566 | |
|
|
4567 | That means that libev compiled in the default environment doesn't support |
|
|
4568 | files larger than 2GiB or so, which mainly affects C<ev_stat> watchers. |
|
|
4569 | |
|
|
4570 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
4571 | by enabling the large file API, which makes them incompatible with the |
|
|
4572 | standard libev compiled for their system. |
|
|
4573 | |
|
|
4574 | Likewise, libev cannot enable the large file API itself as this would |
|
|
4575 | suddenly make it incompatible to the default compile time environment, |
|
|
4576 | i.e. all programs not using special compile switches. |
|
|
4577 | |
|
|
4578 | =head2 OS/X AND DARWIN BUGS |
|
|
4579 | |
|
|
4580 | The whole thing is a bug if you ask me - basically any system interface |
|
|
4581 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
4582 | OpenGL drivers. |
|
|
4583 | |
|
|
4584 | =head3 C<kqueue> is buggy |
|
|
4585 | |
|
|
4586 | The kqueue syscall is broken in all known versions - most versions support |
|
|
4587 | only sockets, many support pipes. |
|
|
4588 | |
|
|
4589 | Libev tries to work around this by not using C<kqueue> by default on this |
|
|
4590 | rotten platform, but of course you can still ask for it when creating a |
|
|
4591 | loop - embedding a socket-only kqueue loop into a select-based one is |
|
|
4592 | probably going to work well. |
|
|
4593 | |
|
|
4594 | =head3 C<poll> is buggy |
|
|
4595 | |
|
|
4596 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
|
|
4597 | implementation by something calling C<kqueue> internally around the 10.5.6 |
|
|
4598 | release, so now C<kqueue> I<and> C<poll> are broken. |
|
|
4599 | |
|
|
4600 | Libev tries to work around this by not using C<poll> by default on |
|
|
4601 | this rotten platform, but of course you can still ask for it when creating |
|
|
4602 | a loop. |
|
|
4603 | |
|
|
4604 | =head3 C<select> is buggy |
|
|
4605 | |
|
|
4606 | All that's left is C<select>, and of course Apple found a way to fuck this |
|
|
4607 | one up as well: On OS/X, C<select> actively limits the number of file |
|
|
4608 | descriptors you can pass in to 1024 - your program suddenly crashes when |
|
|
4609 | you use more. |
|
|
4610 | |
|
|
4611 | There is an undocumented "workaround" for this - defining |
|
|
4612 | C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should> |
|
|
4613 | work on OS/X. |
|
|
4614 | |
|
|
4615 | =head2 SOLARIS PROBLEMS AND WORKAROUNDS |
|
|
4616 | |
|
|
4617 | =head3 C<errno> reentrancy |
|
|
4618 | |
|
|
4619 | The default compile environment on Solaris is unfortunately so |
|
|
4620 | thread-unsafe that you can't even use components/libraries compiled |
|
|
4621 | without C<-D_REENTRANT> in a threaded program, which, of course, isn't |
|
|
4622 | defined by default. A valid, if stupid, implementation choice. |
|
|
4623 | |
|
|
4624 | If you want to use libev in threaded environments you have to make sure |
|
|
4625 | it's compiled with C<_REENTRANT> defined. |
|
|
4626 | |
|
|
4627 | =head3 Event port backend |
|
|
4628 | |
|
|
4629 | The scalable event interface for Solaris is called "event |
|
|
4630 | ports". Unfortunately, this mechanism is very buggy in all major |
|
|
4631 | releases. If you run into high CPU usage, your program freezes or you get |
|
|
4632 | a large number of spurious wakeups, make sure you have all the relevant |
|
|
4633 | and latest kernel patches applied. No, I don't know which ones, but there |
|
|
4634 | are multiple ones to apply, and afterwards, event ports actually work |
|
|
4635 | great. |
|
|
4636 | |
|
|
4637 | If you can't get it to work, you can try running the program by setting |
|
|
4638 | the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and |
|
|
4639 | C<select> backends. |
|
|
4640 | |
|
|
4641 | =head2 AIX POLL BUG |
|
|
4642 | |
|
|
4643 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
|
|
4644 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
4645 | compiled in), which normally isn't a big problem as C<select> works fine |
|
|
4646 | with large bitsets on AIX, and AIX is dead anyway. |
|
|
4647 | |
4404 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4648 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
|
|
4649 | |
|
|
4650 | =head3 General issues |
4405 | |
4651 | |
4406 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4652 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4407 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4653 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4408 | model. Libev still offers limited functionality on this platform in |
4654 | model. Libev still offers limited functionality on this platform in |
4409 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4655 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4410 | descriptors. This only applies when using Win32 natively, not when using |
4656 | descriptors. This only applies when using Win32 natively, not when using |
4411 | e.g. cygwin. |
4657 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
4658 | as every compielr comes with a slightly differently broken/incompatible |
|
|
4659 | environment. |
4412 | |
4660 | |
4413 | Lifting these limitations would basically require the full |
4661 | Lifting these limitations would basically require the full |
4414 | re-implementation of the I/O system. If you are into these kinds of |
4662 | re-implementation of the I/O system. If you are into this kind of thing, |
4415 | things, then note that glib does exactly that for you in a very portable |
4663 | then note that glib does exactly that for you in a very portable way (note |
4416 | way (note also that glib is the slowest event library known to man). |
4664 | also that glib is the slowest event library known to man). |
4417 | |
4665 | |
4418 | There is no supported compilation method available on windows except |
4666 | There is no supported compilation method available on windows except |
4419 | embedding it into other applications. |
4667 | embedding it into other applications. |
4420 | |
4668 | |
4421 | Sensible signal handling is officially unsupported by Microsoft - libev |
4669 | Sensible signal handling is officially unsupported by Microsoft - libev |
… | |
… | |
4449 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4697 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4450 | |
4698 | |
4451 | #include "evwrap.h" |
4699 | #include "evwrap.h" |
4452 | #include "ev.c" |
4700 | #include "ev.c" |
4453 | |
4701 | |
4454 | =over 4 |
|
|
4455 | |
|
|
4456 | =item The winsocket select function |
4702 | =head3 The winsocket C<select> function |
4457 | |
4703 | |
4458 | The winsocket C<select> function doesn't follow POSIX in that it |
4704 | The winsocket C<select> function doesn't follow POSIX in that it |
4459 | requires socket I<handles> and not socket I<file descriptors> (it is |
4705 | requires socket I<handles> and not socket I<file descriptors> (it is |
4460 | also extremely buggy). This makes select very inefficient, and also |
4706 | also extremely buggy). This makes select very inefficient, and also |
4461 | requires a mapping from file descriptors to socket handles (the Microsoft |
4707 | requires a mapping from file descriptors to socket handles (the Microsoft |
… | |
… | |
4470 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4716 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4471 | |
4717 | |
4472 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4718 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4473 | complexity in the O(n²) range when using win32. |
4719 | complexity in the O(n²) range when using win32. |
4474 | |
4720 | |
4475 | =item Limited number of file descriptors |
4721 | =head3 Limited number of file descriptors |
4476 | |
4722 | |
4477 | Windows has numerous arbitrary (and low) limits on things. |
4723 | Windows has numerous arbitrary (and low) limits on things. |
4478 | |
4724 | |
4479 | Early versions of winsocket's select only supported waiting for a maximum |
4725 | Early versions of winsocket's select only supported waiting for a maximum |
4480 | of C<64> handles (probably owning to the fact that all windows kernels |
4726 | of C<64> handles (probably owning to the fact that all windows kernels |
… | |
… | |
4495 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4741 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4496 | (depending on windows version and/or the phase of the moon). To get more, |
4742 | (depending on windows version and/or the phase of the moon). To get more, |
4497 | you need to wrap all I/O functions and provide your own fd management, but |
4743 | you need to wrap all I/O functions and provide your own fd management, but |
4498 | the cost of calling select (O(n²)) will likely make this unworkable. |
4744 | the cost of calling select (O(n²)) will likely make this unworkable. |
4499 | |
4745 | |
4500 | =back |
|
|
4501 | |
|
|
4502 | =head2 PORTABILITY REQUIREMENTS |
4746 | =head2 PORTABILITY REQUIREMENTS |
4503 | |
4747 | |
4504 | In addition to a working ISO-C implementation and of course the |
4748 | In addition to a working ISO-C implementation and of course the |
4505 | backend-specific APIs, libev relies on a few additional extensions: |
4749 | backend-specific APIs, libev relies on a few additional extensions: |
4506 | |
4750 | |
… | |
… | |
4544 | watchers. |
4788 | watchers. |
4545 | |
4789 | |
4546 | =item C<double> must hold a time value in seconds with enough accuracy |
4790 | =item C<double> must hold a time value in seconds with enough accuracy |
4547 | |
4791 | |
4548 | The type C<double> is used to represent timestamps. It is required to |
4792 | The type C<double> is used to represent timestamps. It is required to |
4549 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4793 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
4550 | enough for at least into the year 4000. This requirement is fulfilled by |
4794 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
4795 | (the design goal for libev). This requirement is overfulfilled by |
4551 | implementations implementing IEEE 754, which is basically all existing |
4796 | implementations using IEEE 754, which is basically all existing ones. With |
4552 | ones. With IEEE 754 doubles, you get microsecond accuracy until at least |
4797 | IEEE 754 doubles, you get microsecond accuracy until at least 2200. |
4553 | 2200. |
|
|
4554 | |
4798 | |
4555 | =back |
4799 | =back |
4556 | |
4800 | |
4557 | If you know of other additional requirements drop me a note. |
4801 | If you know of other additional requirements drop me a note. |
4558 | |
4802 | |
… | |
… | |
4636 | compatibility, so most programs should still compile. Those might be |
4880 | compatibility, so most programs should still compile. Those might be |
4637 | removed in later versions of libev, so better update early than late. |
4881 | removed in later versions of libev, so better update early than late. |
4638 | |
4882 | |
4639 | =over 4 |
4883 | =over 4 |
4640 | |
4884 | |
4641 | =item C<ev_loop_count> renamed to C<ev_iteration> |
4885 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
4642 | |
4886 | |
4643 | =item C<ev_loop_depth> renamed to C<ev_depth> |
4887 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
4644 | |
4888 | |
4645 | =item C<ev_loop_verify> renamed to C<ev_verify> |
4889 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
4890 | ev_loop_fork (EV_DEFAULT); |
|
|
4891 | |
|
|
4892 | =item function/symbol renames |
|
|
4893 | |
|
|
4894 | A number of functions and symbols have been renamed: |
|
|
4895 | |
|
|
4896 | ev_loop => ev_run |
|
|
4897 | EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
4898 | EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
4899 | |
|
|
4900 | ev_unloop => ev_break |
|
|
4901 | EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
4902 | EVUNLOOP_ONE => EVBREAK_ONE |
|
|
4903 | EVUNLOOP_ALL => EVBREAK_ALL |
|
|
4904 | |
|
|
4905 | EV_TIMEOUT => EV_TIMER |
|
|
4906 | |
|
|
4907 | ev_loop_count => ev_iteration |
|
|
4908 | ev_loop_depth => ev_depth |
|
|
4909 | ev_loop_verify => ev_verify |
4646 | |
4910 | |
4647 | Most functions working on C<struct ev_loop> objects don't have an |
4911 | Most functions working on C<struct ev_loop> objects don't have an |
4648 | C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is |
4912 | C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and |
|
|
4913 | associated constants have been renamed to not collide with the C<struct |
|
|
4914 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
|
|
4915 | as all other watcher types. Note that C<ev_loop_fork> is still called |
4649 | still called C<ev_loop_fork> because it would otherwise clash with the |
4916 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
4650 | C<ev_fork> typedef. |
4917 | typedef. |
4651 | |
4918 | |
4652 | =item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents> |
4919 | =item C<EV_COMPAT3> backwards compatibility mechanism |
4653 | |
4920 | |
4654 | This is a simple rename - all other watcher types use their name |
4921 | The backward compatibility mechanism can be controlled by |
4655 | as revents flag, and now C<ev_timer> does, too. |
4922 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
4656 | |
4923 | section. |
4657 | Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions |
|
|
4658 | and continue to be present for the forseeable future, so this is mostly a |
|
|
4659 | documentation change. |
|
|
4660 | |
4924 | |
4661 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
4925 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
4662 | |
4926 | |
4663 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
4927 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
4664 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
4928 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
… | |
… | |
4671 | |
4935 | |
4672 | =over 4 |
4936 | =over 4 |
4673 | |
4937 | |
4674 | =item active |
4938 | =item active |
4675 | |
4939 | |
4676 | A watcher is active as long as it has been started (has been attached to |
4940 | A watcher is active as long as it has been started and not yet stopped. |
4677 | an event loop) but not yet stopped (disassociated from the event loop). |
4941 | See L<WATCHER STATES> for details. |
4678 | |
4942 | |
4679 | =item application |
4943 | =item application |
4680 | |
4944 | |
4681 | In this document, an application is whatever is using libev. |
4945 | In this document, an application is whatever is using libev. |
|
|
4946 | |
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|
4947 | =item backend |
|
|
4948 | |
|
|
4949 | The part of the code dealing with the operating system interfaces. |
4682 | |
4950 | |
4683 | =item callback |
4951 | =item callback |
4684 | |
4952 | |
4685 | The address of a function that is called when some event has been |
4953 | The address of a function that is called when some event has been |
4686 | detected. Callbacks are being passed the event loop, the watcher that |
4954 | detected. Callbacks are being passed the event loop, the watcher that |
4687 | received the event, and the actual event bitset. |
4955 | received the event, and the actual event bitset. |
4688 | |
4956 | |
4689 | =item callback invocation |
4957 | =item callback/watcher invocation |
4690 | |
4958 | |
4691 | The act of calling the callback associated with a watcher. |
4959 | The act of calling the callback associated with a watcher. |
4692 | |
4960 | |
4693 | =item event |
4961 | =item event |
4694 | |
4962 | |
… | |
… | |
4713 | The model used to describe how an event loop handles and processes |
4981 | The model used to describe how an event loop handles and processes |
4714 | watchers and events. |
4982 | watchers and events. |
4715 | |
4983 | |
4716 | =item pending |
4984 | =item pending |
4717 | |
4985 | |
4718 | A watcher is pending as soon as the corresponding event has been detected, |
4986 | A watcher is pending as soon as the corresponding event has been |
4719 | and stops being pending as soon as the watcher will be invoked or its |
4987 | detected. See L<WATCHER STATES> for details. |
4720 | pending status is explicitly cleared by the application. |
|
|
4721 | |
|
|
4722 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4723 | its pending status. |
|
|
4724 | |
4988 | |
4725 | =item real time |
4989 | =item real time |
4726 | |
4990 | |
4727 | The physical time that is observed. It is apparently strictly monotonic :) |
4991 | The physical time that is observed. It is apparently strictly monotonic :) |
4728 | |
4992 | |
… | |
… | |
4735 | =item watcher |
4999 | =item watcher |
4736 | |
5000 | |
4737 | A data structure that describes interest in certain events. Watchers need |
5001 | A data structure that describes interest in certain events. Watchers need |
4738 | to be started (attached to an event loop) before they can receive events. |
5002 | to be started (attached to an event loop) before they can receive events. |
4739 | |
5003 | |
4740 | =item watcher invocation |
|
|
4741 | |
|
|
4742 | The act of calling the callback associated with a watcher. |
|
|
4743 | |
|
|
4744 | =back |
5004 | =back |
4745 | |
5005 | |
4746 | =head1 AUTHOR |
5006 | =head1 AUTHOR |
4747 | |
5007 | |
4748 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
5008 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |