… | |
… | |
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); |
… | |
… | |
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 | Familiarity 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. |
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82 | |
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83 | =head1 WHAT TO READ WHEN IN A HURRY |
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84 | |
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85 | This manual tries to be very detailed, but unfortunately, this also makes |
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86 | it very long. If you just want to know the basics of libev, I suggest |
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87 | reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and |
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88 | look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and |
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89 | C<ev_timer> sections in L<WATCHER TYPES>. |
82 | |
90 | |
83 | =head1 ABOUT LIBEV |
91 | =head1 ABOUT LIBEV |
84 | |
92 | |
85 | Libev is an event loop: you register interest in certain events (such as a |
93 | Libev is an event loop: you register interest in certain events (such as a |
86 | file descriptor being readable or a timeout occurring), and it will manage |
94 | file descriptor being readable or a timeout occurring), and it will manage |
… | |
… | |
124 | this argument. |
132 | this argument. |
125 | |
133 | |
126 | =head2 TIME REPRESENTATION |
134 | =head2 TIME REPRESENTATION |
127 | |
135 | |
128 | Libev represents time as a single floating point number, representing |
136 | Libev represents time as a single floating point number, representing |
129 | the (fractional) number of seconds since the (POSIX) epoch (in practise |
137 | the (fractional) number of seconds since the (POSIX) epoch (in practice |
130 | somewhere near the beginning of 1970, details are complicated, don't |
138 | 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 |
139 | 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 |
140 | 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. |
141 | any calculations on it, you should treat it as some floating point value. |
134 | |
142 | |
… | |
… | |
165 | |
173 | |
166 | =item ev_tstamp ev_time () |
174 | =item ev_tstamp ev_time () |
167 | |
175 | |
168 | Returns the current time as libev would use it. Please note that the |
176 | 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 |
177 | C<ev_now> function is usually faster and also often returns the timestamp |
170 | you actually want to know. |
178 | you actually want to know. Also interesting is the combination of |
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179 | C<ev_update_now> and C<ev_now>. |
171 | |
180 | |
172 | =item ev_sleep (ev_tstamp interval) |
181 | =item ev_sleep (ev_tstamp interval) |
173 | |
182 | |
174 | Sleep for the given interval: The current thread will be blocked until |
183 | 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 |
184 | either it is interrupted or the given time interval has passed. Basically |
… | |
… | |
192 | as this indicates an incompatible change. Minor versions are usually |
201 | as this indicates an incompatible change. Minor versions are usually |
193 | compatible to older versions, so a larger minor version alone is usually |
202 | compatible to older versions, so a larger minor version alone is usually |
194 | not a problem. |
203 | not a problem. |
195 | |
204 | |
196 | Example: Make sure we haven't accidentally been linked against the wrong |
205 | Example: Make sure we haven't accidentally been linked against the wrong |
197 | version (note, however, that this will not detect ABI mismatches :). |
206 | version (note, however, that this will not detect other ABI mismatches, |
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207 | such as LFS or reentrancy). |
198 | |
208 | |
199 | assert (("libev version mismatch", |
209 | assert (("libev version mismatch", |
200 | ev_version_major () == EV_VERSION_MAJOR |
210 | ev_version_major () == EV_VERSION_MAJOR |
201 | && ev_version_minor () >= EV_VERSION_MINOR)); |
211 | && ev_version_minor () >= EV_VERSION_MINOR)); |
202 | |
212 | |
… | |
… | |
213 | assert (("sorry, no epoll, no sex", |
223 | assert (("sorry, no epoll, no sex", |
214 | ev_supported_backends () & EVBACKEND_EPOLL)); |
224 | ev_supported_backends () & EVBACKEND_EPOLL)); |
215 | |
225 | |
216 | =item unsigned int ev_recommended_backends () |
226 | =item unsigned int ev_recommended_backends () |
217 | |
227 | |
218 | Return the set of all backends compiled into this binary of libev and also |
228 | 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 |
229 | also recommended for this platform, meaning it will work for most file |
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230 | 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 |
231 | 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 |
232 | 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 |
233 | 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. |
234 | probe for if you specify no backends explicitly. |
224 | |
235 | |
225 | =item unsigned int ev_embeddable_backends () |
236 | =item unsigned int ev_embeddable_backends () |
226 | |
237 | |
227 | Returns the set of backends that are embeddable in other event loops. This |
238 | Returns the set of backends that are embeddable in other event loops. This |
228 | is the theoretical, all-platform, value. To find which backends |
239 | 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 |
240 | current system. To find which embeddable backends might be supported on |
230 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
241 | the current system, you would need to look at C<ev_embeddable_backends () |
231 | recommended ones. |
242 | & ev_supported_backends ()>, likewise for recommended ones. |
232 | |
243 | |
233 | See the description of C<ev_embed> watchers for more info. |
244 | See the description of C<ev_embed> watchers for more info. |
234 | |
245 | |
235 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT] |
246 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
236 | |
247 | |
237 | Sets the allocation function to use (the prototype is similar - the |
248 | Sets the allocation function to use (the prototype is similar - the |
238 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
249 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
239 | used to allocate and free memory (no surprises here). If it returns zero |
250 | used to allocate and free memory (no surprises here). If it returns zero |
240 | when memory needs to be allocated (C<size != 0>), the library might abort |
251 | when memory needs to be allocated (C<size != 0>), the library might abort |
… | |
… | |
266 | } |
277 | } |
267 | |
278 | |
268 | ... |
279 | ... |
269 | ev_set_allocator (persistent_realloc); |
280 | ev_set_allocator (persistent_realloc); |
270 | |
281 | |
271 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT] |
282 | =item ev_set_syserr_cb (void (*cb)(const char *msg)) |
272 | |
283 | |
273 | Set the callback function to call on a retryable system call error (such |
284 | Set the callback function to call on a retryable system call error (such |
274 | as failed select, poll, epoll_wait). The message is a printable string |
285 | as failed select, poll, epoll_wait). The message is a printable string |
275 | indicating the system call or subsystem causing the problem. If this |
286 | indicating the system call or subsystem causing the problem. If this |
276 | callback is set, then libev will expect it to remedy the situation, no |
287 | callback is set, then libev will expect it to remedy the situation, no |
… | |
… | |
290 | ... |
301 | ... |
291 | ev_set_syserr_cb (fatal_error); |
302 | ev_set_syserr_cb (fatal_error); |
292 | |
303 | |
293 | =back |
304 | =back |
294 | |
305 | |
295 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
306 | =head1 FUNCTIONS CONTROLLING EVENT LOOPS |
296 | |
307 | |
297 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
308 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
298 | I<not> optional in this case unless libev 3 compatibility is disabled, as |
309 | I<not> optional in this case unless libev 3 compatibility is disabled, as |
299 | libev 3 had an C<ev_loop> function colliding with the struct name). |
310 | libev 3 had an C<ev_loop> function colliding with the struct name). |
300 | |
311 | |
301 | The library knows two types of such loops, the I<default> loop, which |
312 | The library knows two types of such loops, the I<default> loop, which |
302 | supports signals and child events, and dynamically created event loops |
313 | supports child process events, and dynamically created event loops which |
303 | which do not. |
314 | do not. |
304 | |
315 | |
305 | =over 4 |
316 | =over 4 |
306 | |
317 | |
307 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
318 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
308 | |
319 | |
309 | This will initialise the default event loop if it hasn't been initialised |
320 | 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 |
321 | 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 |
322 | 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). |
323 | C<ev_loop_new>. |
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324 | |
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325 | If the default loop is already initialised then this function simply |
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326 | returns it (and ignores the flags. If that is troubling you, check |
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327 | C<ev_backend ()> afterwards). Otherwise it will create it with the given |
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328 | flags, which should almost always be C<0>, unless the caller is also the |
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329 | one calling C<ev_run> or otherwise qualifies as "the main program". |
313 | |
330 | |
314 | If you don't know what event loop to use, use the one returned from this |
331 | If you don't know what event loop to use, use the one returned from this |
315 | function. |
332 | function (or via the C<EV_DEFAULT> macro). |
316 | |
333 | |
317 | Note that this function is I<not> thread-safe, so if you want to use it |
334 | 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, |
335 | from multiple threads, you have to employ some kind of mutex (note also |
319 | as loops cannot be shared easily between threads anyway). |
336 | that this case is unlikely, as loops cannot be shared easily between |
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337 | threads anyway). |
320 | |
338 | |
321 | The default loop is the only loop that can handle C<ev_signal> and |
339 | 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 |
340 | 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 |
341 | 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 |
342 | 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 |
343 | C<SIGCHLD> signal handler I<after> calling C<ev_default_init>. |
326 | C<ev_default_init>. |
344 | |
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345 | Example: This is the most typical usage. |
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346 | |
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347 | if (!ev_default_loop (0)) |
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348 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
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349 | |
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350 | Example: Restrict libev to the select and poll backends, and do not allow |
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351 | environment settings to be taken into account: |
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352 | |
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353 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
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354 | |
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355 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
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356 | |
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357 | This will create and initialise a new event loop object. If the loop |
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358 | could not be initialised, returns false. |
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359 | |
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360 | This function is thread-safe, and one common way to use libev with |
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361 | threads is indeed to create one loop per thread, and using the default |
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362 | loop in the "main" or "initial" thread. |
327 | |
363 | |
328 | The flags argument can be used to specify special behaviour or specific |
364 | 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>). |
365 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
330 | |
366 | |
331 | The following flags are supported: |
367 | The following flags are supported: |
… | |
… | |
366 | environment variable. |
402 | environment variable. |
367 | |
403 | |
368 | =item C<EVFLAG_NOINOTIFY> |
404 | =item C<EVFLAG_NOINOTIFY> |
369 | |
405 | |
370 | When this flag is specified, then libev will not attempt to use the |
406 | When this flag is specified, then libev will not attempt to use the |
371 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
407 | I<inotify> API for its C<ev_stat> watchers. Apart from debugging and |
372 | testing, this flag can be useful to conserve inotify file descriptors, as |
408 | testing, this flag can be useful to conserve inotify file descriptors, as |
373 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
409 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
374 | |
410 | |
375 | =item C<EVFLAG_SIGNALFD> |
411 | =item C<EVFLAG_SIGNALFD> |
376 | |
412 | |
377 | When this flag is specified, then libev will attempt to use the |
413 | When this flag is specified, then libev will attempt to use the |
378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API |
414 | I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API |
379 | delivers signals synchronously, which makes it both faster and might make |
415 | delivers signals synchronously, which makes it both faster and might make |
380 | it possible to get the queued signal data. It can also simplify signal |
416 | it possible to get the queued signal data. It can also simplify signal |
381 | handling with threads, as long as you properly block signals in your |
417 | handling with threads, as long as you properly block signals in your |
382 | threads that are not interested in handling them. |
418 | threads that are not interested in handling them. |
383 | |
419 | |
… | |
… | |
427 | epoll scales either O(1) or O(active_fds). |
463 | epoll scales either O(1) or O(active_fds). |
428 | |
464 | |
429 | The epoll mechanism deserves honorable mention as the most misdesigned |
465 | The epoll mechanism deserves honorable mention as the most misdesigned |
430 | of the more advanced event mechanisms: mere annoyances include silently |
466 | of the more advanced event mechanisms: mere annoyances include silently |
431 | dropping file descriptors, requiring a system call per change per file |
467 | dropping file descriptors, requiring a system call per change per file |
432 | descriptor (and unnecessary guessing of parameters), problems with dup and |
468 | descriptor (and unnecessary guessing of parameters), problems with dup, |
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469 | returning before the timeout value, resulting in additional iterations |
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470 | (and only giving 5ms accuracy while select on the same platform gives |
433 | so on. The biggest issue is fork races, however - if a program forks then |
471 | 0.1ms) and so on. The biggest issue is fork races, however - if a program |
434 | I<both> parent and child process have to recreate the epoll set, which can |
472 | forks then I<both> parent and child process have to recreate the epoll |
435 | take considerable time (one syscall per file descriptor) and is of course |
473 | set, which can take considerable time (one syscall per file descriptor) |
436 | hard to detect. |
474 | and is of course hard to detect. |
437 | |
475 | |
438 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, but |
476 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, but |
439 | of course I<doesn't>, and epoll just loves to report events for totally |
477 | 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 |
478 | I<different> file descriptors (even already closed ones, so one cannot |
441 | even remove them from the set) than registered in the set (especially |
479 | even remove them from the set) than registered in the set (especially |
… | |
… | |
443 | employing an additional generation counter and comparing that against the |
481 | employing an additional generation counter and comparing that against the |
444 | events to filter out spurious ones, recreating the set when required. Last |
482 | events to filter out spurious ones, recreating the set when required. Last |
445 | not least, it also refuses to work with some file descriptors which work |
483 | not least, it also refuses to work with some file descriptors which work |
446 | perfectly fine with C<select> (files, many character devices...). |
484 | perfectly fine with C<select> (files, many character devices...). |
447 | |
485 | |
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486 | Epoll is truly the train wreck analog among event poll mechanisms. |
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487 | |
448 | While stopping, setting and starting an I/O watcher in the same iteration |
488 | While stopping, setting and starting an I/O watcher in the same iteration |
449 | will result in some caching, there is still a system call per such |
489 | will result in some caching, there is still a system call per such |
450 | incident (because the same I<file descriptor> could point to a different |
490 | incident (because the same I<file descriptor> could point to a different |
451 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
491 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
452 | file descriptors might not work very well if you register events for both |
492 | file descriptors might not work very well if you register events for both |
… | |
… | |
549 | If one or more of the backend flags are or'ed into the flags value, |
589 | If one or more of the backend flags are or'ed into the flags value, |
550 | then only these backends will be tried (in the reverse order as listed |
590 | then only these backends will be tried (in the reverse order as listed |
551 | here). If none are specified, all backends in C<ev_recommended_backends |
591 | here). If none are specified, all backends in C<ev_recommended_backends |
552 | ()> will be tried. |
592 | ()> will be tried. |
553 | |
593 | |
554 | Example: This is the most typical usage. |
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|
555 | |
|
|
556 | if (!ev_default_loop (0)) |
|
|
557 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
558 | |
|
|
559 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
560 | environment settings to be taken into account: |
|
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561 | |
|
|
562 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
563 | |
|
|
564 | Example: Use whatever libev has to offer, but make sure that kqueue is |
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565 | used if available (warning, breaks stuff, best use only with your own |
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566 | private event loop and only if you know the OS supports your types of |
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567 | fds): |
|
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568 | |
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569 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
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570 | |
|
|
571 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
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572 | |
|
|
573 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
|
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574 | always distinct from the default loop. |
|
|
575 | |
|
|
576 | Note that this function I<is> thread-safe, and one common way to use |
|
|
577 | libev with threads is indeed to create one loop per thread, and using the |
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578 | default loop in the "main" or "initial" thread. |
|
|
579 | |
|
|
580 | Example: Try to create a event loop that uses epoll and nothing else. |
594 | Example: Try to create a event loop that uses epoll and nothing else. |
581 | |
595 | |
582 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
596 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
583 | if (!epoller) |
597 | if (!epoller) |
584 | fatal ("no epoll found here, maybe it hides under your chair"); |
598 | fatal ("no epoll found here, maybe it hides under your chair"); |
585 | |
599 | |
|
|
600 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
601 | used if available. |
|
|
602 | |
|
|
603 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
604 | |
586 | =item ev_default_destroy () |
605 | =item ev_loop_destroy (loop) |
587 | |
606 | |
588 | Destroys the default loop (frees all memory and kernel state etc.). None |
607 | Destroys an event loop object (frees all memory and kernel state |
589 | of the active event watchers will be stopped in the normal sense, so |
608 | etc.). None of the active event watchers will be stopped in the normal |
590 | e.g. C<ev_is_active> might still return true. It is your responsibility to |
609 | sense, so e.g. C<ev_is_active> might still return true. It is your |
591 | either stop all watchers cleanly yourself I<before> calling this function, |
610 | responsibility to either stop all watchers cleanly yourself I<before> |
592 | or cope with the fact afterwards (which is usually the easiest thing, you |
611 | calling this function, or cope with the fact afterwards (which is usually |
593 | can just ignore the watchers and/or C<free ()> them for example). |
612 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
|
|
613 | for example). |
594 | |
614 | |
595 | Note that certain global state, such as signal state (and installed signal |
615 | Note that certain global state, such as signal state (and installed signal |
596 | handlers), will not be freed by this function, and related watchers (such |
616 | handlers), will not be freed by this function, and related watchers (such |
597 | as signal and child watchers) would need to be stopped manually. |
617 | as signal and child watchers) would need to be stopped manually. |
598 | |
618 | |
599 | In general it is not advisable to call this function except in the |
619 | This function is normally used on loop objects allocated by |
600 | rare occasion where you really need to free e.g. the signal handling |
620 | C<ev_loop_new>, but it can also be used on the default loop returned by |
|
|
621 | C<ev_default_loop>, in which case it is not thread-safe. |
|
|
622 | |
|
|
623 | Note that it is not advisable to call this function on the default loop |
|
|
624 | except in the rare occasion where you really need to free its resources. |
601 | pipe fds. If you need dynamically allocated loops it is better to use |
625 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
602 | C<ev_loop_new> and C<ev_loop_destroy>. |
626 | and C<ev_loop_destroy>. |
603 | |
627 | |
604 | =item ev_loop_destroy (loop) |
628 | =item ev_loop_fork (loop) |
605 | |
629 | |
606 | Like C<ev_default_destroy>, but destroys an event loop created by an |
|
|
607 | earlier call to C<ev_loop_new>. |
|
|
608 | |
|
|
609 | =item ev_default_fork () |
|
|
610 | |
|
|
611 | This function sets a flag that causes subsequent C<ev_run> iterations |
630 | This function sets a flag that causes subsequent C<ev_run> iterations to |
612 | to reinitialise the kernel state for backends that have one. Despite the |
631 | reinitialise the kernel state for backends that have one. Despite the |
613 | name, you can call it anytime, but it makes most sense after forking, in |
632 | name, you can call it anytime, but it makes most sense after forking, in |
614 | the child process (or both child and parent, but that again makes little |
633 | the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the |
615 | sense). You I<must> call it in the child before using any of the libev |
634 | child before resuming or calling C<ev_run>. |
616 | functions, and it will only take effect at the next C<ev_run> iteration. |
|
|
617 | |
635 | |
618 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
636 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
619 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
637 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
620 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
638 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
621 | during fork. |
639 | during fork. |
… | |
… | |
626 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
644 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
627 | difference, but libev will usually detect this case on its own and do a |
645 | difference, but libev will usually detect this case on its own and do a |
628 | costly reset of the backend). |
646 | costly reset of the backend). |
629 | |
647 | |
630 | The function itself is quite fast and it's usually not a problem to call |
648 | The function itself is quite fast and it's usually not a problem to call |
631 | it just in case after a fork. To make this easy, the function will fit in |
649 | it just in case after a fork. |
632 | quite nicely into a call to C<pthread_atfork>: |
|
|
633 | |
650 | |
|
|
651 | Example: Automate calling C<ev_loop_fork> on the default loop when |
|
|
652 | using pthreads. |
|
|
653 | |
|
|
654 | static void |
|
|
655 | post_fork_child (void) |
|
|
656 | { |
|
|
657 | ev_loop_fork (EV_DEFAULT); |
|
|
658 | } |
|
|
659 | |
|
|
660 | ... |
634 | pthread_atfork (0, 0, ev_default_fork); |
661 | pthread_atfork (0, 0, post_fork_child); |
635 | |
|
|
636 | =item ev_loop_fork (loop) |
|
|
637 | |
|
|
638 | Like C<ev_default_fork>, but acts on an event loop created by |
|
|
639 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
|
|
640 | after fork that you want to re-use in the child, and how you keep track of |
|
|
641 | them is entirely your own problem. |
|
|
642 | |
662 | |
643 | =item int ev_is_default_loop (loop) |
663 | =item int ev_is_default_loop (loop) |
644 | |
664 | |
645 | Returns true when the given loop is, in fact, the default loop, and false |
665 | Returns true when the given loop is, in fact, the default loop, and false |
646 | otherwise. |
666 | otherwise. |
… | |
… | |
657 | prepare and check phases. |
677 | prepare and check phases. |
658 | |
678 | |
659 | =item unsigned int ev_depth (loop) |
679 | =item unsigned int ev_depth (loop) |
660 | |
680 | |
661 | Returns the number of times C<ev_run> was entered minus the number of |
681 | Returns the number of times C<ev_run> was entered minus the number of |
662 | times C<ev_run> was exited, in other words, the recursion depth. |
682 | times C<ev_run> was exited normally, in other words, the recursion depth. |
663 | |
683 | |
664 | Outside C<ev_run>, this number is zero. In a callback, this number is |
684 | Outside C<ev_run>, this number is zero. In a callback, this number is |
665 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
685 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
666 | in which case it is higher. |
686 | in which case it is higher. |
667 | |
687 | |
668 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread |
688 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread, |
669 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
689 | throwing an exception etc.), doesn't count as "exit" - consider this |
670 | ungentleman-like behaviour unless it's really convenient. |
690 | as a hint to avoid such ungentleman-like behaviour unless it's really |
|
|
691 | convenient, in which case it is fully supported. |
671 | |
692 | |
672 | =item unsigned int ev_backend (loop) |
693 | =item unsigned int ev_backend (loop) |
673 | |
694 | |
674 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
695 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
675 | use. |
696 | use. |
… | |
… | |
736 | relying on all watchers to be stopped when deciding when a program has |
757 | relying on all watchers to be stopped when deciding when a program has |
737 | finished (especially in interactive programs), but having a program |
758 | finished (especially in interactive programs), but having a program |
738 | that automatically loops as long as it has to and no longer by virtue |
759 | that automatically loops as long as it has to and no longer by virtue |
739 | of relying on its watchers stopping correctly, that is truly a thing of |
760 | of relying on its watchers stopping correctly, that is truly a thing of |
740 | beauty. |
761 | beauty. |
|
|
762 | |
|
|
763 | This function is also I<mostly> exception-safe - you can break out of |
|
|
764 | a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++ |
|
|
765 | exception and so on. This does not decrement the C<ev_depth> value, nor |
|
|
766 | will it clear any outstanding C<EVBREAK_ONE> breaks. |
741 | |
767 | |
742 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
768 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
743 | those events and any already outstanding ones, but will not wait and |
769 | those events and any already outstanding ones, but will not wait and |
744 | block your process in case there are no events and will return after one |
770 | block your process in case there are no events and will return after one |
745 | iteration of the loop. This is sometimes useful to poll and handle new |
771 | iteration of the loop. This is sometimes useful to poll and handle new |
… | |
… | |
807 | Can be used to make a call to C<ev_run> return early (but only after it |
833 | Can be used to make a call to C<ev_run> return early (but only after it |
808 | has processed all outstanding events). The C<how> argument must be either |
834 | has processed all outstanding events). The C<how> argument must be either |
809 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
835 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
810 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
836 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
811 | |
837 | |
812 | This "unloop state" will be cleared when entering C<ev_run> again. |
838 | This "break state" will be cleared on the next call to C<ev_run>. |
813 | |
839 | |
814 | It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO## |
840 | It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in |
|
|
841 | which case it will have no effect. |
815 | |
842 | |
816 | =item ev_ref (loop) |
843 | =item ev_ref (loop) |
817 | |
844 | |
818 | =item ev_unref (loop) |
845 | =item ev_unref (loop) |
819 | |
846 | |
… | |
… | |
840 | running when nothing else is active. |
867 | running when nothing else is active. |
841 | |
868 | |
842 | ev_signal exitsig; |
869 | ev_signal exitsig; |
843 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
870 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
844 | ev_signal_start (loop, &exitsig); |
871 | ev_signal_start (loop, &exitsig); |
845 | evf_unref (loop); |
872 | ev_unref (loop); |
846 | |
873 | |
847 | Example: For some weird reason, unregister the above signal handler again. |
874 | Example: For some weird reason, unregister the above signal handler again. |
848 | |
875 | |
849 | ev_ref (loop); |
876 | ev_ref (loop); |
850 | ev_signal_stop (loop, &exitsig); |
877 | ev_signal_stop (loop, &exitsig); |
… | |
… | |
908 | |
935 | |
909 | =item ev_invoke_pending (loop) |
936 | =item ev_invoke_pending (loop) |
910 | |
937 | |
911 | This call will simply invoke all pending watchers while resetting their |
938 | This call will simply invoke all pending watchers while resetting their |
912 | pending state. Normally, C<ev_run> does this automatically when required, |
939 | pending state. Normally, C<ev_run> does this automatically when required, |
913 | but when overriding the invoke callback this call comes handy. |
940 | but when overriding the invoke callback this call comes handy. This |
|
|
941 | function can be invoked from a watcher - this can be useful for example |
|
|
942 | when you want to do some lengthy calculation and want to pass further |
|
|
943 | event handling to another thread (you still have to make sure only one |
|
|
944 | thread executes within C<ev_invoke_pending> or C<ev_run> of course). |
914 | |
945 | |
915 | =item int ev_pending_count (loop) |
946 | =item int ev_pending_count (loop) |
916 | |
947 | |
917 | Returns the number of pending watchers - zero indicates that no watchers |
948 | Returns the number of pending watchers - zero indicates that no watchers |
918 | are pending. |
949 | are pending. |
… | |
… | |
958 | See also the locking example in the C<THREADS> section later in this |
989 | See also the locking example in the C<THREADS> section later in this |
959 | document. |
990 | document. |
960 | |
991 | |
961 | =item ev_set_userdata (loop, void *data) |
992 | =item ev_set_userdata (loop, void *data) |
962 | |
993 | |
963 | =item ev_userdata (loop) |
994 | =item void *ev_userdata (loop) |
964 | |
995 | |
965 | Set and retrieve a single C<void *> associated with a loop. When |
996 | Set and retrieve a single C<void *> associated with a loop. When |
966 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
997 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
967 | C<0.> |
998 | C<0>. |
968 | |
999 | |
969 | These two functions can be used to associate arbitrary data with a loop, |
1000 | These two functions can be used to associate arbitrary data with a loop, |
970 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
1001 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
971 | C<acquire> callbacks described above, but of course can be (ab-)used for |
1002 | C<acquire> callbacks described above, but of course can be (ab-)used for |
972 | any other purpose as well. |
1003 | any other purpose as well. |
… | |
… | |
1100 | =item C<EV_FORK> |
1131 | =item C<EV_FORK> |
1101 | |
1132 | |
1102 | The event loop has been resumed in the child process after fork (see |
1133 | The event loop has been resumed in the child process after fork (see |
1103 | C<ev_fork>). |
1134 | C<ev_fork>). |
1104 | |
1135 | |
|
|
1136 | =item C<EV_CLEANUP> |
|
|
1137 | |
|
|
1138 | The event loop is about to be destroyed (see C<ev_cleanup>). |
|
|
1139 | |
1105 | =item C<EV_ASYNC> |
1140 | =item C<EV_ASYNC> |
1106 | |
1141 | |
1107 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1142 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1108 | |
1143 | |
1109 | =item C<EV_CUSTOM> |
1144 | =item C<EV_CUSTOM> |
… | |
… | |
1130 | programs, though, as the fd could already be closed and reused for another |
1165 | programs, though, as the fd could already be closed and reused for another |
1131 | thing, so beware. |
1166 | thing, so beware. |
1132 | |
1167 | |
1133 | =back |
1168 | =back |
1134 | |
1169 | |
1135 | =head2 WATCHER STATES |
|
|
1136 | |
|
|
1137 | There are various watcher states mentioned throughout this manual - |
|
|
1138 | active, pending and so on. In this section these states and the rules to |
|
|
1139 | transition between them will be described in more detail - and while these |
|
|
1140 | rules might look complicated, they usually do "the right thing". |
|
|
1141 | |
|
|
1142 | =over 4 |
|
|
1143 | |
|
|
1144 | =item initialiased |
|
|
1145 | |
|
|
1146 | Before a watcher can be registered with the event looop it has to be |
|
|
1147 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1148 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
|
|
1149 | |
|
|
1150 | In this state it is simply some block of memory that is suitable for use |
|
|
1151 | in an event loop. It can be moved around, freed, reused etc. at will. |
|
|
1152 | |
|
|
1153 | =item started/running/active |
|
|
1154 | |
|
|
1155 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
|
|
1156 | property of the event loop, and is actively waiting for events. While in |
|
|
1157 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1158 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1159 | and call libev functions on it that are documented to work on active watchers. |
|
|
1160 | |
|
|
1161 | =item pending |
|
|
1162 | |
|
|
1163 | If a watcher is active and libev determines that an event it is interested |
|
|
1164 | in has occured (such as a timer expiring), it will become pending. It will |
|
|
1165 | stay in this pending state until either it is stopped or its callback is |
|
|
1166 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1167 | callback. |
|
|
1168 | |
|
|
1169 | The watcher might or might not be active while it is pending (for example, |
|
|
1170 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1171 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1172 | but it is still property of the event loop at this time, so cannot be |
|
|
1173 | moved, freed or reused. And if it is active the rules described in the |
|
|
1174 | previous item still apply. |
|
|
1175 | |
|
|
1176 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1177 | via C<ev_feed_event>), in which case it becomes pending without being |
|
|
1178 | active. |
|
|
1179 | |
|
|
1180 | =item stopped |
|
|
1181 | |
|
|
1182 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1183 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
|
|
1184 | latter will clear any pending state the watcher might be in, regardless |
|
|
1185 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1186 | freeing it is often a good idea. |
|
|
1187 | |
|
|
1188 | While stopped (and not pending) the watcher is essentially in the |
|
|
1189 | initialised state, that is it can be reused, moved, modified in any way |
|
|
1190 | you wish. |
|
|
1191 | |
|
|
1192 | =back |
|
|
1193 | |
|
|
1194 | =head2 GENERIC WATCHER FUNCTIONS |
1170 | =head2 GENERIC WATCHER FUNCTIONS |
1195 | |
1171 | |
1196 | =over 4 |
1172 | =over 4 |
1197 | |
1173 | |
1198 | =item C<ev_init> (ev_TYPE *watcher, callback) |
1174 | =item C<ev_init> (ev_TYPE *watcher, callback) |
… | |
… | |
1339 | |
1315 | |
1340 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1316 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1341 | functions that do not need a watcher. |
1317 | functions that do not need a watcher. |
1342 | |
1318 | |
1343 | =back |
1319 | =back |
1344 | |
|
|
1345 | |
1320 | |
1346 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1321 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1347 | |
1322 | |
1348 | Each watcher has, by default, a member C<void *data> that you can change |
1323 | Each watcher has, by default, a member C<void *data> that you can change |
1349 | and read at any time: libev will completely ignore it. This can be used |
1324 | and read at any time: libev will completely ignore it. This can be used |
… | |
… | |
1405 | t2_cb (EV_P_ ev_timer *w, int revents) |
1380 | t2_cb (EV_P_ ev_timer *w, int revents) |
1406 | { |
1381 | { |
1407 | struct my_biggy big = (struct my_biggy *) |
1382 | struct my_biggy big = (struct my_biggy *) |
1408 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1383 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1409 | } |
1384 | } |
|
|
1385 | |
|
|
1386 | =head2 WATCHER STATES |
|
|
1387 | |
|
|
1388 | There are various watcher states mentioned throughout this manual - |
|
|
1389 | active, pending and so on. In this section these states and the rules to |
|
|
1390 | transition between them will be described in more detail - and while these |
|
|
1391 | rules might look complicated, they usually do "the right thing". |
|
|
1392 | |
|
|
1393 | =over 4 |
|
|
1394 | |
|
|
1395 | =item initialiased |
|
|
1396 | |
|
|
1397 | Before a watcher can be registered with the event looop it has to be |
|
|
1398 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1399 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
|
|
1400 | |
|
|
1401 | In this state it is simply some block of memory that is suitable for use |
|
|
1402 | in an event loop. It can be moved around, freed, reused etc. at will. |
|
|
1403 | |
|
|
1404 | =item started/running/active |
|
|
1405 | |
|
|
1406 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
|
|
1407 | property of the event loop, and is actively waiting for events. While in |
|
|
1408 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1409 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1410 | and call libev functions on it that are documented to work on active watchers. |
|
|
1411 | |
|
|
1412 | =item pending |
|
|
1413 | |
|
|
1414 | If a watcher is active and libev determines that an event it is interested |
|
|
1415 | in has occurred (such as a timer expiring), it will become pending. It will |
|
|
1416 | stay in this pending state until either it is stopped or its callback is |
|
|
1417 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1418 | callback. |
|
|
1419 | |
|
|
1420 | The watcher might or might not be active while it is pending (for example, |
|
|
1421 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1422 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1423 | but it is still property of the event loop at this time, so cannot be |
|
|
1424 | moved, freed or reused. And if it is active the rules described in the |
|
|
1425 | previous item still apply. |
|
|
1426 | |
|
|
1427 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1428 | via C<ev_feed_event>), in which case it becomes pending without being |
|
|
1429 | active. |
|
|
1430 | |
|
|
1431 | =item stopped |
|
|
1432 | |
|
|
1433 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1434 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
|
|
1435 | latter will clear any pending state the watcher might be in, regardless |
|
|
1436 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1437 | freeing it is often a good idea. |
|
|
1438 | |
|
|
1439 | While stopped (and not pending) the watcher is essentially in the |
|
|
1440 | initialised state, that is it can be reused, moved, modified in any way |
|
|
1441 | you wish. |
|
|
1442 | |
|
|
1443 | =back |
1410 | |
1444 | |
1411 | =head2 WATCHER PRIORITY MODELS |
1445 | =head2 WATCHER PRIORITY MODELS |
1412 | |
1446 | |
1413 | Many event loops support I<watcher priorities>, which are usually small |
1447 | Many event loops support I<watcher priorities>, which are usually small |
1414 | integers that influence the ordering of event callback invocation |
1448 | integers that influence the ordering of event callback invocation |
… | |
… | |
2233 | |
2267 | |
2234 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2268 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2235 | |
2269 | |
2236 | Signal watchers will trigger an event when the process receives a specific |
2270 | Signal watchers will trigger an event when the process receives a specific |
2237 | signal one or more times. Even though signals are very asynchronous, libev |
2271 | signal one or more times. Even though signals are very asynchronous, libev |
2238 | will try it's best to deliver signals synchronously, i.e. as part of the |
2272 | will try its best to deliver signals synchronously, i.e. as part of the |
2239 | normal event processing, like any other event. |
2273 | normal event processing, like any other event. |
2240 | |
2274 | |
2241 | If you want signals to be delivered truly asynchronously, just use |
2275 | If you want signals to be delivered truly asynchronously, just use |
2242 | C<sigaction> as you would do without libev and forget about sharing |
2276 | C<sigaction> as you would do without libev and forget about sharing |
2243 | the signal. You can even use C<ev_async> from a signal handler to |
2277 | the signal. You can even use C<ev_async> from a signal handler to |
… | |
… | |
3068 | disadvantage of having to use multiple event loops (which do not support |
3102 | disadvantage of having to use multiple event loops (which do not support |
3069 | signal watchers). |
3103 | signal watchers). |
3070 | |
3104 | |
3071 | When this is not possible, or you want to use the default loop for |
3105 | When this is not possible, or you want to use the default loop for |
3072 | other reasons, then in the process that wants to start "fresh", call |
3106 | other reasons, then in the process that wants to start "fresh", call |
3073 | C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying |
3107 | C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>. |
3074 | the default loop will "orphan" (not stop) all registered watchers, so you |
3108 | Destroying the default loop will "orphan" (not stop) all registered |
3075 | have to be careful not to execute code that modifies those watchers. Note |
3109 | watchers, so you have to be careful not to execute code that modifies |
3076 | also that in that case, you have to re-register any signal watchers. |
3110 | those watchers. Note also that in that case, you have to re-register any |
|
|
3111 | signal watchers. |
3077 | |
3112 | |
3078 | =head3 Watcher-Specific Functions and Data Members |
3113 | =head3 Watcher-Specific Functions and Data Members |
3079 | |
3114 | |
3080 | =over 4 |
3115 | =over 4 |
3081 | |
3116 | |
3082 | =item ev_fork_init (ev_signal *, callback) |
3117 | =item ev_fork_init (ev_fork *, callback) |
3083 | |
3118 | |
3084 | Initialises and configures the fork watcher - it has no parameters of any |
3119 | Initialises and configures the fork watcher - it has no parameters of any |
3085 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
3120 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
3086 | believe me. |
3121 | really. |
3087 | |
3122 | |
3088 | =back |
3123 | =back |
|
|
3124 | |
|
|
3125 | |
|
|
3126 | =head2 C<ev_cleanup> - even the best things end |
|
|
3127 | |
|
|
3128 | Cleanup watchers are called just before the event loop is being destroyed |
|
|
3129 | by a call to C<ev_loop_destroy>. |
|
|
3130 | |
|
|
3131 | While there is no guarantee that the event loop gets destroyed, cleanup |
|
|
3132 | watchers provide a convenient method to install cleanup hooks for your |
|
|
3133 | program, worker threads and so on - you just to make sure to destroy the |
|
|
3134 | loop when you want them to be invoked. |
|
|
3135 | |
|
|
3136 | Cleanup watchers are invoked in the same way as any other watcher. Unlike |
|
|
3137 | all other watchers, they do not keep a reference to the event loop (which |
|
|
3138 | makes a lot of sense if you think about it). Like all other watchers, you |
|
|
3139 | can call libev functions in the callback, except C<ev_cleanup_start>. |
|
|
3140 | |
|
|
3141 | =head3 Watcher-Specific Functions and Data Members |
|
|
3142 | |
|
|
3143 | =over 4 |
|
|
3144 | |
|
|
3145 | =item ev_cleanup_init (ev_cleanup *, callback) |
|
|
3146 | |
|
|
3147 | Initialises and configures the cleanup watcher - it has no parameters of |
|
|
3148 | any kind. There is a C<ev_cleanup_set> macro, but using it is utterly |
|
|
3149 | pointless, I assure you. |
|
|
3150 | |
|
|
3151 | =back |
|
|
3152 | |
|
|
3153 | Example: Register an atexit handler to destroy the default loop, so any |
|
|
3154 | cleanup functions are called. |
|
|
3155 | |
|
|
3156 | static void |
|
|
3157 | program_exits (void) |
|
|
3158 | { |
|
|
3159 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
3160 | } |
|
|
3161 | |
|
|
3162 | ... |
|
|
3163 | atexit (program_exits); |
3089 | |
3164 | |
3090 | |
3165 | |
3091 | =head2 C<ev_async> - how to wake up an event loop |
3166 | =head2 C<ev_async> - how to wake up an event loop |
3092 | |
3167 | |
3093 | In general, you cannot use an C<ev_run> from multiple threads or other |
3168 | In general, you cannot use an C<ev_run> from multiple threads or other |
… | |
… | |
3292 | loop!). |
3367 | loop!). |
3293 | |
3368 | |
3294 | =back |
3369 | =back |
3295 | |
3370 | |
3296 | |
3371 | |
|
|
3372 | =head1 COMMON OR USEFUL IDIOMS (OR BOTH) |
|
|
3373 | |
|
|
3374 | This section explains some common idioms that are not immediately |
|
|
3375 | obvious. Note that examples are sprinkled over the whole manual, and this |
|
|
3376 | section only contains stuff that wouldn't fit anywhere else. |
|
|
3377 | |
|
|
3378 | =over 4 |
|
|
3379 | |
|
|
3380 | =item Model/nested event loop invocations and exit conditions. |
|
|
3381 | |
|
|
3382 | Often (especially in GUI toolkits) there are places where you have |
|
|
3383 | I<modal> interaction, which is most easily implemented by recursively |
|
|
3384 | invoking C<ev_run>. |
|
|
3385 | |
|
|
3386 | This brings the problem of exiting - a callback might want to finish the |
|
|
3387 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
|
|
3388 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
|
|
3389 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
|
|
3390 | other combination: In these cases, C<ev_break> will not work alone. |
|
|
3391 | |
|
|
3392 | The solution is to maintain "break this loop" variable for each C<ev_run> |
|
|
3393 | invocation, and use a loop around C<ev_run> until the condition is |
|
|
3394 | triggered, using C<EVRUN_ONCE>: |
|
|
3395 | |
|
|
3396 | // main loop |
|
|
3397 | int exit_main_loop = 0; |
|
|
3398 | |
|
|
3399 | while (!exit_main_loop) |
|
|
3400 | ev_run (EV_DEFAULT_ EVRUN_ONCE); |
|
|
3401 | |
|
|
3402 | // in a model watcher |
|
|
3403 | int exit_nested_loop = 0; |
|
|
3404 | |
|
|
3405 | while (!exit_nested_loop) |
|
|
3406 | ev_run (EV_A_ EVRUN_ONCE); |
|
|
3407 | |
|
|
3408 | To exit from any of these loops, just set the corresponding exit variable: |
|
|
3409 | |
|
|
3410 | // exit modal loop |
|
|
3411 | exit_nested_loop = 1; |
|
|
3412 | |
|
|
3413 | // exit main program, after modal loop is finished |
|
|
3414 | exit_main_loop = 1; |
|
|
3415 | |
|
|
3416 | // exit both |
|
|
3417 | exit_main_loop = exit_nested_loop = 1; |
|
|
3418 | |
|
|
3419 | =back |
|
|
3420 | |
|
|
3421 | |
3297 | =head1 LIBEVENT EMULATION |
3422 | =head1 LIBEVENT EMULATION |
3298 | |
3423 | |
3299 | Libev offers a compatibility emulation layer for libevent. It cannot |
3424 | Libev offers a compatibility emulation layer for libevent. It cannot |
3300 | emulate the internals of libevent, so here are some usage hints: |
3425 | emulate the internals of libevent, so here are some usage hints: |
3301 | |
3426 | |
3302 | =over 4 |
3427 | =over 4 |
|
|
3428 | |
|
|
3429 | =item * Only the libevent-1.4.1-beta API is being emulated. |
|
|
3430 | |
|
|
3431 | This was the newest libevent version available when libev was implemented, |
|
|
3432 | and is still mostly unchanged in 2010. |
3303 | |
3433 | |
3304 | =item * Use it by including <event.h>, as usual. |
3434 | =item * Use it by including <event.h>, as usual. |
3305 | |
3435 | |
3306 | =item * The following members are fully supported: ev_base, ev_callback, |
3436 | =item * The following members are fully supported: ev_base, ev_callback, |
3307 | ev_arg, ev_fd, ev_res, ev_events. |
3437 | ev_arg, ev_fd, ev_res, ev_events. |
… | |
… | |
3313 | =item * Priorities are not currently supported. Initialising priorities |
3443 | =item * Priorities are not currently supported. Initialising priorities |
3314 | will fail and all watchers will have the same priority, even though there |
3444 | will fail and all watchers will have the same priority, even though there |
3315 | is an ev_pri field. |
3445 | is an ev_pri field. |
3316 | |
3446 | |
3317 | =item * In libevent, the last base created gets the signals, in libev, the |
3447 | =item * In libevent, the last base created gets the signals, in libev, the |
3318 | first base created (== the default loop) gets the signals. |
3448 | base that registered the signal gets the signals. |
3319 | |
3449 | |
3320 | =item * Other members are not supported. |
3450 | =item * Other members are not supported. |
3321 | |
3451 | |
3322 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
3452 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
3323 | to use the libev header file and library. |
3453 | to use the libev header file and library. |
… | |
… | |
3342 | Care has been taken to keep the overhead low. The only data member the C++ |
3472 | Care has been taken to keep the overhead low. The only data member the C++ |
3343 | classes add (compared to plain C-style watchers) is the event loop pointer |
3473 | classes add (compared to plain C-style watchers) is the event loop pointer |
3344 | that the watcher is associated with (or no additional members at all if |
3474 | that the watcher is associated with (or no additional members at all if |
3345 | you disable C<EV_MULTIPLICITY> when embedding libev). |
3475 | you disable C<EV_MULTIPLICITY> when embedding libev). |
3346 | |
3476 | |
3347 | Currently, functions, and static and non-static member functions can be |
3477 | Currently, functions, static and non-static member functions and classes |
3348 | used as callbacks. Other types should be easy to add as long as they only |
3478 | with C<operator ()> can be used as callbacks. Other types should be easy |
3349 | need one additional pointer for context. If you need support for other |
3479 | to add as long as they only need one additional pointer for context. If |
3350 | types of functors please contact the author (preferably after implementing |
3480 | you need support for other types of functors please contact the author |
3351 | it). |
3481 | (preferably after implementing it). |
3352 | |
3482 | |
3353 | Here is a list of things available in the C<ev> namespace: |
3483 | Here is a list of things available in the C<ev> namespace: |
3354 | |
3484 | |
3355 | =over 4 |
3485 | =over 4 |
3356 | |
3486 | |
… | |
… | |
4527 | =head3 C<kqueue> is buggy |
4657 | =head3 C<kqueue> is buggy |
4528 | |
4658 | |
4529 | The kqueue syscall is broken in all known versions - most versions support |
4659 | The kqueue syscall is broken in all known versions - most versions support |
4530 | only sockets, many support pipes. |
4660 | only sockets, many support pipes. |
4531 | |
4661 | |
4532 | Libev tries to work around this by not using C<kqueue> by default on |
4662 | Libev tries to work around this by not using C<kqueue> by default on this |
4533 | this rotten platform, but of course you can still ask for it when creating |
4663 | rotten platform, but of course you can still ask for it when creating a |
4534 | a loop. |
4664 | loop - embedding a socket-only kqueue loop into a select-based one is |
|
|
4665 | probably going to work well. |
4535 | |
4666 | |
4536 | =head3 C<poll> is buggy |
4667 | =head3 C<poll> is buggy |
4537 | |
4668 | |
4538 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
4669 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
4539 | implementation by something calling C<kqueue> internally around the 10.5.6 |
4670 | implementation by something calling C<kqueue> internally around the 10.5.6 |
… | |
… | |
4558 | |
4689 | |
4559 | =head3 C<errno> reentrancy |
4690 | =head3 C<errno> reentrancy |
4560 | |
4691 | |
4561 | The default compile environment on Solaris is unfortunately so |
4692 | The default compile environment on Solaris is unfortunately so |
4562 | thread-unsafe that you can't even use components/libraries compiled |
4693 | thread-unsafe that you can't even use components/libraries compiled |
4563 | without C<-D_REENTRANT> (as long as they use C<errno>), which, of course, |
4694 | without C<-D_REENTRANT> in a threaded program, which, of course, isn't |
4564 | isn't defined by default. |
4695 | defined by default. A valid, if stupid, implementation choice. |
4565 | |
4696 | |
4566 | If you want to use libev in threaded environments you have to make sure |
4697 | If you want to use libev in threaded environments you have to make sure |
4567 | it's compiled with C<_REENTRANT> defined. |
4698 | it's compiled with C<_REENTRANT> defined. |
4568 | |
4699 | |
4569 | =head3 Event port backend |
4700 | =head3 Event port backend |
4570 | |
4701 | |
4571 | The scalable event interface for Solaris is called "event ports". Unfortunately, |
4702 | The scalable event interface for Solaris is called "event |
4572 | this mechanism is very buggy. If you run into high CPU usage, your program |
4703 | ports". Unfortunately, this mechanism is very buggy in all major |
|
|
4704 | releases. If you run into high CPU usage, your program freezes or you get |
4573 | freezes or you get a large number of spurious wakeups, make sure you have |
4705 | a large number of spurious wakeups, make sure you have all the relevant |
4574 | all the relevant and latest kernel patches applied. No, I don't know which |
4706 | and latest kernel patches applied. No, I don't know which ones, but there |
4575 | ones, but there are multiple ones. |
4707 | are multiple ones to apply, and afterwards, event ports actually work |
|
|
4708 | great. |
4576 | |
4709 | |
4577 | If you can't get it to work, you can try running the program by setting |
4710 | If you can't get it to work, you can try running the program by setting |
4578 | the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and |
4711 | the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and |
4579 | C<select> backends. |
4712 | C<select> backends. |
4580 | |
4713 | |
4581 | =head2 AIX POLL BUG |
4714 | =head2 AIX POLL BUG |
4582 | |
4715 | |
4583 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
4716 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
4584 | this by trying to avoid the poll backend altogether (i.e. it's not even |
4717 | this by trying to avoid the poll backend altogether (i.e. it's not even |
4585 | compiled in), which normally isn't a big problem as C<select> works fine |
4718 | compiled in), which normally isn't a big problem as C<select> works fine |
4586 | with large bitsets, and AIX is dead anyway. |
4719 | with large bitsets on AIX, and AIX is dead anyway. |
4587 | |
4720 | |
4588 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4721 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4589 | |
4722 | |
4590 | =head3 General issues |
4723 | =head3 General issues |
4591 | |
4724 | |
… | |
… | |
4697 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
4830 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
4698 | assumes that the same (machine) code can be used to call any watcher |
4831 | assumes that the same (machine) code can be used to call any watcher |
4699 | callback: The watcher callbacks have different type signatures, but libev |
4832 | callback: The watcher callbacks have different type signatures, but libev |
4700 | calls them using an C<ev_watcher *> internally. |
4833 | calls them using an C<ev_watcher *> internally. |
4701 | |
4834 | |
|
|
4835 | =item pointer accesses must be thread-atomic |
|
|
4836 | |
|
|
4837 | Accessing a pointer value must be atomic, it must both be readable and |
|
|
4838 | writable in one piece - this is the case on all current architectures. |
|
|
4839 | |
4702 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
4840 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
4703 | |
4841 | |
4704 | The type C<sig_atomic_t volatile> (or whatever is defined as |
4842 | The type C<sig_atomic_t volatile> (or whatever is defined as |
4705 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
4843 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
4706 | threads. This is not part of the specification for C<sig_atomic_t>, but is |
4844 | threads. This is not part of the specification for C<sig_atomic_t>, but is |
… | |
… | |
4812 | =back |
4950 | =back |
4813 | |
4951 | |
4814 | |
4952 | |
4815 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
4953 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
4816 | |
4954 | |
4817 | The major version 4 introduced some minor incompatible changes to the API. |
4955 | The major version 4 introduced some incompatible changes to the API. |
4818 | |
4956 | |
4819 | At the moment, the C<ev.h> header file tries to implement superficial |
4957 | At the moment, the C<ev.h> header file provides compatibility definitions |
4820 | compatibility, so most programs should still compile. Those might be |
4958 | for all changes, so most programs should still compile. The compatibility |
4821 | removed in later versions of libev, so better update early than late. |
4959 | layer might be removed in later versions of libev, so better update to the |
|
|
4960 | new API early than late. |
4822 | |
4961 | |
4823 | =over 4 |
4962 | =over 4 |
|
|
4963 | |
|
|
4964 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
4965 | |
|
|
4966 | The backward compatibility mechanism can be controlled by |
|
|
4967 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
4968 | section. |
|
|
4969 | |
|
|
4970 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
|
|
4971 | |
|
|
4972 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
|
|
4973 | |
|
|
4974 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
4975 | ev_loop_fork (EV_DEFAULT); |
4824 | |
4976 | |
4825 | =item function/symbol renames |
4977 | =item function/symbol renames |
4826 | |
4978 | |
4827 | A number of functions and symbols have been renamed: |
4979 | A number of functions and symbols have been renamed: |
4828 | |
4980 | |
… | |
… | |
4847 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
4999 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
4848 | as all other watcher types. Note that C<ev_loop_fork> is still called |
5000 | as all other watcher types. Note that C<ev_loop_fork> is still called |
4849 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
5001 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
4850 | typedef. |
5002 | typedef. |
4851 | |
5003 | |
4852 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
4853 | |
|
|
4854 | The backward compatibility mechanism can be controlled by |
|
|
4855 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
4856 | section. |
|
|
4857 | |
|
|
4858 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
5004 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
4859 | |
5005 | |
4860 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
5006 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
4861 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
5007 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
4862 | and work, but the library code will of course be larger. |
5008 | and work, but the library code will of course be larger. |
… | |
… | |
4868 | |
5014 | |
4869 | =over 4 |
5015 | =over 4 |
4870 | |
5016 | |
4871 | =item active |
5017 | =item active |
4872 | |
5018 | |
4873 | A watcher is active as long as it has been started (has been attached to |
5019 | A watcher is active as long as it has been started and not yet stopped. |
4874 | an event loop) but not yet stopped (disassociated from the event loop). |
5020 | See L<WATCHER STATES> for details. |
4875 | |
5021 | |
4876 | =item application |
5022 | =item application |
4877 | |
5023 | |
4878 | In this document, an application is whatever is using libev. |
5024 | In this document, an application is whatever is using libev. |
|
|
5025 | |
|
|
5026 | =item backend |
|
|
5027 | |
|
|
5028 | The part of the code dealing with the operating system interfaces. |
4879 | |
5029 | |
4880 | =item callback |
5030 | =item callback |
4881 | |
5031 | |
4882 | The address of a function that is called when some event has been |
5032 | The address of a function that is called when some event has been |
4883 | detected. Callbacks are being passed the event loop, the watcher that |
5033 | detected. Callbacks are being passed the event loop, the watcher that |
4884 | received the event, and the actual event bitset. |
5034 | received the event, and the actual event bitset. |
4885 | |
5035 | |
4886 | =item callback invocation |
5036 | =item callback/watcher invocation |
4887 | |
5037 | |
4888 | The act of calling the callback associated with a watcher. |
5038 | The act of calling the callback associated with a watcher. |
4889 | |
5039 | |
4890 | =item event |
5040 | =item event |
4891 | |
5041 | |
… | |
… | |
4910 | The model used to describe how an event loop handles and processes |
5060 | The model used to describe how an event loop handles and processes |
4911 | watchers and events. |
5061 | watchers and events. |
4912 | |
5062 | |
4913 | =item pending |
5063 | =item pending |
4914 | |
5064 | |
4915 | A watcher is pending as soon as the corresponding event has been detected, |
5065 | A watcher is pending as soon as the corresponding event has been |
4916 | and stops being pending as soon as the watcher will be invoked or its |
5066 | detected. See L<WATCHER STATES> for details. |
4917 | pending status is explicitly cleared by the application. |
|
|
4918 | |
|
|
4919 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4920 | its pending status. |
|
|
4921 | |
5067 | |
4922 | =item real time |
5068 | =item real time |
4923 | |
5069 | |
4924 | The physical time that is observed. It is apparently strictly monotonic :) |
5070 | The physical time that is observed. It is apparently strictly monotonic :) |
4925 | |
5071 | |
… | |
… | |
4932 | =item watcher |
5078 | =item watcher |
4933 | |
5079 | |
4934 | A data structure that describes interest in certain events. Watchers need |
5080 | A data structure that describes interest in certain events. Watchers need |
4935 | to be started (attached to an event loop) before they can receive events. |
5081 | to be started (attached to an event loop) before they can receive events. |
4936 | |
5082 | |
4937 | =item watcher invocation |
|
|
4938 | |
|
|
4939 | The act of calling the callback associated with a watcher. |
|
|
4940 | |
|
|
4941 | =back |
5083 | =back |
4942 | |
5084 | |
4943 | =head1 AUTHOR |
5085 | =head1 AUTHOR |
4944 | |
5086 | |
4945 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
5087 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
|
|
5088 | Magnusson and Emanuele Giaquinta. |
4946 | |
5089 | |