… | |
… | |
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. |
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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 (somewhere |
137 | the (fractional) number of seconds since the (POSIX) epoch (in practice |
130 | near the beginning of 1970, details are complicated, don't ask). This |
138 | somewhere near the beginning of 1970, details are complicated, don't |
131 | type is called C<ev_tstamp>, which is what you should use too. It usually |
139 | ask). This type is called C<ev_tstamp>, which is what you should use |
132 | aliases to the C<double> type in C. When you need to do any calculations |
140 | too. It usually aliases to the C<double> type in C. When you need to do |
133 | on it, you should treat it as some floating point value. Unlike the name |
141 | any calculations on it, you should treat it as some floating point value. |
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142 | |
134 | component C<stamp> might indicate, it is also used for time differences |
143 | Unlike the name component C<stamp> might indicate, it is also used for |
135 | throughout libev. |
144 | time differences (e.g. delays) throughout libev. |
136 | |
145 | |
137 | =head1 ERROR HANDLING |
146 | =head1 ERROR HANDLING |
138 | |
147 | |
139 | Libev knows three classes of errors: operating system errors, usage errors |
148 | Libev knows three classes of errors: operating system errors, usage errors |
140 | and internal errors (bugs). |
149 | and internal errors (bugs). |
… | |
… | |
164 | |
173 | |
165 | =item ev_tstamp ev_time () |
174 | =item ev_tstamp ev_time () |
166 | |
175 | |
167 | 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 |
168 | 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 |
169 | 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>. |
170 | |
180 | |
171 | =item ev_sleep (ev_tstamp interval) |
181 | =item ev_sleep (ev_tstamp interval) |
172 | |
182 | |
173 | 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 |
174 | 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 |
… | |
… | |
191 | as this indicates an incompatible change. Minor versions are usually |
201 | as this indicates an incompatible change. Minor versions are usually |
192 | 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 |
193 | not a problem. |
203 | not a problem. |
194 | |
204 | |
195 | 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 |
196 | version. |
206 | version (note, however, that this will not detect other ABI mismatches, |
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207 | such as LFS or reentrancy). |
197 | |
208 | |
198 | assert (("libev version mismatch", |
209 | assert (("libev version mismatch", |
199 | ev_version_major () == EV_VERSION_MAJOR |
210 | ev_version_major () == EV_VERSION_MAJOR |
200 | && ev_version_minor () >= EV_VERSION_MINOR)); |
211 | && ev_version_minor () >= EV_VERSION_MINOR)); |
201 | |
212 | |
… | |
… | |
212 | assert (("sorry, no epoll, no sex", |
223 | assert (("sorry, no epoll, no sex", |
213 | ev_supported_backends () & EVBACKEND_EPOLL)); |
224 | ev_supported_backends () & EVBACKEND_EPOLL)); |
214 | |
225 | |
215 | =item unsigned int ev_recommended_backends () |
226 | =item unsigned int ev_recommended_backends () |
216 | |
227 | |
217 | 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 |
218 | 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 |
219 | 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 |
220 | 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 |
221 | (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 |
222 | libev will probe for if you specify no backends explicitly. |
234 | probe for if you specify no backends explicitly. |
223 | |
235 | |
224 | =item unsigned int ev_embeddable_backends () |
236 | =item unsigned int ev_embeddable_backends () |
225 | |
237 | |
226 | 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 |
227 | is the theoretical, all-platform, value. To find which backends |
239 | value is platform-specific but can include backends not available on the |
228 | might be supported on the current system, you would need to look at |
240 | current system. To find which embeddable backends might be supported on |
229 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
241 | the current system, you would need to look at C<ev_embeddable_backends () |
230 | recommended ones. |
242 | & ev_supported_backends ()>, likewise for recommended ones. |
231 | |
243 | |
232 | See the description of C<ev_embed> watchers for more info. |
244 | See the description of C<ev_embed> watchers for more info. |
233 | |
245 | |
234 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT] |
246 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
235 | |
247 | |
236 | Sets the allocation function to use (the prototype is similar - the |
248 | Sets the allocation function to use (the prototype is similar - the |
237 | 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 |
238 | 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 |
239 | 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 |
… | |
… | |
265 | } |
277 | } |
266 | |
278 | |
267 | ... |
279 | ... |
268 | ev_set_allocator (persistent_realloc); |
280 | ev_set_allocator (persistent_realloc); |
269 | |
281 | |
270 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT] |
282 | =item ev_set_syserr_cb (void (*cb)(const char *msg)) |
271 | |
283 | |
272 | 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 |
273 | 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 |
274 | indicating the system call or subsystem causing the problem. If this |
286 | indicating the system call or subsystem causing the problem. If this |
275 | 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 |
… | |
… | |
287 | } |
299 | } |
288 | |
300 | |
289 | ... |
301 | ... |
290 | ev_set_syserr_cb (fatal_error); |
302 | ev_set_syserr_cb (fatal_error); |
291 | |
303 | |
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304 | =item ev_feed_signal (int signum) |
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305 | |
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306 | This function can be used to "simulate" a signal receive. It is completely |
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307 | safe to call this function at any time, from any context, including signal |
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308 | handlers or random threads. |
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309 | |
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310 | It's main use is to customise signal handling in your process, especially |
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311 | in the presence of threads. For example, you could block signals |
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312 | by default in all threads (and specifying C<EVFLAG_NOSIGMASK> when |
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313 | creating any loops), and in one thread, use C<sigwait> or any other |
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314 | mechanism to wait for signals, then "deliver" them to libev by calling |
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315 | C<ev_feed_signal>. |
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316 | |
292 | =back |
317 | =back |
293 | |
318 | |
294 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
319 | =head1 FUNCTIONS CONTROLLING EVENT LOOPS |
295 | |
320 | |
296 | An event loop is described by a C<struct ev_loop *> (the C<struct> |
321 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
297 | is I<not> optional in this case, as there is also an C<ev_loop> |
322 | I<not> optional in this case unless libev 3 compatibility is disabled, as |
298 | I<function>). |
323 | libev 3 had an C<ev_loop> function colliding with the struct name). |
299 | |
324 | |
300 | The library knows two types of such loops, the I<default> loop, which |
325 | The library knows two types of such loops, the I<default> loop, which |
301 | supports signals and child events, and dynamically created loops which do |
326 | supports child process events, and dynamically created event loops which |
302 | not. |
327 | do not. |
303 | |
328 | |
304 | =over 4 |
329 | =over 4 |
305 | |
330 | |
306 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
331 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
307 | |
332 | |
308 | This will initialise the default event loop if it hasn't been initialised |
333 | This returns the "default" event loop object, which is what you should |
309 | yet and return it. If the default loop could not be initialised, returns |
334 | normally use when you just need "the event loop". Event loop objects and |
310 | false. If it already was initialised it simply returns it (and ignores the |
335 | the C<flags> parameter are described in more detail in the entry for |
311 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
336 | C<ev_loop_new>. |
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337 | |
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338 | If the default loop is already initialised then this function simply |
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339 | returns it (and ignores the flags. If that is troubling you, check |
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340 | C<ev_backend ()> afterwards). Otherwise it will create it with the given |
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341 | flags, which should almost always be C<0>, unless the caller is also the |
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342 | one calling C<ev_run> or otherwise qualifies as "the main program". |
312 | |
343 | |
313 | If you don't know what event loop to use, use the one returned from this |
344 | If you don't know what event loop to use, use the one returned from this |
314 | function. |
345 | function (or via the C<EV_DEFAULT> macro). |
315 | |
346 | |
316 | Note that this function is I<not> thread-safe, so if you want to use it |
347 | Note that this function is I<not> thread-safe, so if you want to use it |
317 | from multiple threads, you have to lock (note also that this is unlikely, |
348 | from multiple threads, you have to employ some kind of mutex (note also |
318 | as loops cannot be shared easily between threads anyway). |
349 | that this case is unlikely, as loops cannot be shared easily between |
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350 | threads anyway). |
319 | |
351 | |
320 | The default loop is the only loop that can handle C<ev_signal> and |
352 | The default loop is the only loop that can handle C<ev_child> watchers, |
321 | C<ev_child> watchers, and to do this, it always registers a handler |
353 | and to do this, it always registers a handler for C<SIGCHLD>. If this is |
322 | for C<SIGCHLD>. If this is a problem for your application you can either |
354 | a problem for your application you can either create a dynamic loop with |
323 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
355 | C<ev_loop_new> which doesn't do that, or you can simply overwrite the |
324 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
356 | C<SIGCHLD> signal handler I<after> calling C<ev_default_init>. |
325 | C<ev_default_init>. |
357 | |
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358 | Example: This is the most typical usage. |
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359 | |
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360 | if (!ev_default_loop (0)) |
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361 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
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362 | |
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363 | Example: Restrict libev to the select and poll backends, and do not allow |
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364 | environment settings to be taken into account: |
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365 | |
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366 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
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367 | |
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368 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
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369 | |
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370 | This will create and initialise a new event loop object. If the loop |
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371 | could not be initialised, returns false. |
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372 | |
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373 | This function is thread-safe, and one common way to use libev with |
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374 | threads is indeed to create one loop per thread, and using the default |
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375 | loop in the "main" or "initial" thread. |
326 | |
376 | |
327 | The flags argument can be used to specify special behaviour or specific |
377 | The flags argument can be used to specify special behaviour or specific |
328 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
378 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
329 | |
379 | |
330 | The following flags are supported: |
380 | The following flags are supported: |
… | |
… | |
365 | environment variable. |
415 | environment variable. |
366 | |
416 | |
367 | =item C<EVFLAG_NOINOTIFY> |
417 | =item C<EVFLAG_NOINOTIFY> |
368 | |
418 | |
369 | When this flag is specified, then libev will not attempt to use the |
419 | When this flag is specified, then libev will not attempt to use the |
370 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
420 | I<inotify> API for its C<ev_stat> watchers. Apart from debugging and |
371 | testing, this flag can be useful to conserve inotify file descriptors, as |
421 | testing, this flag can be useful to conserve inotify file descriptors, as |
372 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
422 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
373 | |
423 | |
374 | =item C<EVFLAG_SIGNALFD> |
424 | =item C<EVFLAG_SIGNALFD> |
375 | |
425 | |
376 | When this flag is specified, then libev will attempt to use the |
426 | When this flag is specified, then libev will attempt to use the |
377 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API |
427 | I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API |
378 | delivers signals synchronously, which makes it both faster and might make |
428 | delivers signals synchronously, which makes it both faster and might make |
379 | it possible to get the queued signal data. It can also simplify signal |
429 | it possible to get the queued signal data. It can also simplify signal |
380 | handling with threads, as long as you properly block signals in your |
430 | handling with threads, as long as you properly block signals in your |
381 | threads that are not interested in handling them. |
431 | threads that are not interested in handling them. |
382 | |
432 | |
383 | Signalfd will not be used by default as this changes your signal mask, and |
433 | Signalfd will not be used by default as this changes your signal mask, and |
384 | there are a lot of shoddy libraries and programs (glib's threadpool for |
434 | there are a lot of shoddy libraries and programs (glib's threadpool for |
385 | example) that can't properly initialise their signal masks. |
435 | example) that can't properly initialise their signal masks. |
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436 | |
|
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437 | =item C<EVFLAG_NOSIGMASK> |
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438 | |
|
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439 | When this flag is specified, then libev will avoid to modify the signal |
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440 | mask. Specifically, this means you ahve to make sure signals are unblocked |
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441 | when you want to receive them. |
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442 | |
|
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443 | This behaviour is useful when you want to do your own signal handling, or |
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444 | want to handle signals only in specific threads and want to avoid libev |
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445 | unblocking the signals. |
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446 | |
|
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447 | This flag's behaviour will become the default in future versions of libev. |
386 | |
448 | |
387 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
449 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
388 | |
450 | |
389 | This is your standard select(2) backend. Not I<completely> standard, as |
451 | This is your standard select(2) backend. Not I<completely> standard, as |
390 | libev tries to roll its own fd_set with no limits on the number of fds, |
452 | libev tries to roll its own fd_set with no limits on the number of fds, |
… | |
… | |
426 | epoll scales either O(1) or O(active_fds). |
488 | epoll scales either O(1) or O(active_fds). |
427 | |
489 | |
428 | The epoll mechanism deserves honorable mention as the most misdesigned |
490 | The epoll mechanism deserves honorable mention as the most misdesigned |
429 | of the more advanced event mechanisms: mere annoyances include silently |
491 | of the more advanced event mechanisms: mere annoyances include silently |
430 | dropping file descriptors, requiring a system call per change per file |
492 | dropping file descriptors, requiring a system call per change per file |
431 | descriptor (and unnecessary guessing of parameters), problems with dup and |
493 | descriptor (and unnecessary guessing of parameters), problems with dup, |
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494 | returning before the timeout value, resulting in additional iterations |
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495 | (and only giving 5ms accuracy while select on the same platform gives |
432 | so on. The biggest issue is fork races, however - if a program forks then |
496 | 0.1ms) and so on. The biggest issue is fork races, however - if a program |
433 | I<both> parent and child process have to recreate the epoll set, which can |
497 | forks then I<both> parent and child process have to recreate the epoll |
434 | take considerable time (one syscall per file descriptor) and is of course |
498 | set, which can take considerable time (one syscall per file descriptor) |
435 | hard to detect. |
499 | and is of course hard to detect. |
436 | |
500 | |
437 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, but |
501 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, but |
438 | of course I<doesn't>, and epoll just loves to report events for totally |
502 | of course I<doesn't>, and epoll just loves to report events for totally |
439 | I<different> file descriptors (even already closed ones, so one cannot |
503 | I<different> file descriptors (even already closed ones, so one cannot |
440 | even remove them from the set) than registered in the set (especially |
504 | even remove them from the set) than registered in the set (especially |
441 | on SMP systems). Libev tries to counter these spurious notifications by |
505 | on SMP systems). Libev tries to counter these spurious notifications by |
442 | employing an additional generation counter and comparing that against the |
506 | employing an additional generation counter and comparing that against the |
443 | events to filter out spurious ones, recreating the set when required. |
507 | events to filter out spurious ones, recreating the set when required. Last |
|
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508 | not least, it also refuses to work with some file descriptors which work |
|
|
509 | perfectly fine with C<select> (files, many character devices...). |
|
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510 | |
|
|
511 | Epoll is truly the train wreck analog among event poll mechanisms. |
444 | |
512 | |
445 | While stopping, setting and starting an I/O watcher in the same iteration |
513 | While stopping, setting and starting an I/O watcher in the same iteration |
446 | will result in some caching, there is still a system call per such |
514 | will result in some caching, there is still a system call per such |
447 | incident (because the same I<file descriptor> could point to a different |
515 | incident (because the same I<file descriptor> could point to a different |
448 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
516 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
… | |
… | |
537 | |
605 | |
538 | Try all backends (even potentially broken ones that wouldn't be tried |
606 | Try all backends (even potentially broken ones that wouldn't be tried |
539 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
607 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
540 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
608 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
541 | |
609 | |
542 | It is definitely not recommended to use this flag. |
610 | It is definitely not recommended to use this flag, use whatever |
|
|
611 | C<ev_recommended_backends ()> returns, or simply do not specify a backend |
|
|
612 | at all. |
|
|
613 | |
|
|
614 | =item C<EVBACKEND_MASK> |
|
|
615 | |
|
|
616 | Not a backend at all, but a mask to select all backend bits from a |
|
|
617 | C<flags> value, in case you want to mask out any backends from a flags |
|
|
618 | value (e.g. when modifying the C<LIBEV_FLAGS> environment variable). |
543 | |
619 | |
544 | =back |
620 | =back |
545 | |
621 | |
546 | If one or more of the backend flags are or'ed into the flags value, |
622 | If one or more of the backend flags are or'ed into the flags value, |
547 | then only these backends will be tried (in the reverse order as listed |
623 | then only these backends will be tried (in the reverse order as listed |
548 | here). If none are specified, all backends in C<ev_recommended_backends |
624 | here). If none are specified, all backends in C<ev_recommended_backends |
549 | ()> will be tried. |
625 | ()> will be tried. |
550 | |
626 | |
551 | Example: This is the most typical usage. |
|
|
552 | |
|
|
553 | if (!ev_default_loop (0)) |
|
|
554 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
555 | |
|
|
556 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
557 | environment settings to be taken into account: |
|
|
558 | |
|
|
559 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
560 | |
|
|
561 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
562 | used if available (warning, breaks stuff, best use only with your own |
|
|
563 | private event loop and only if you know the OS supports your types of |
|
|
564 | fds): |
|
|
565 | |
|
|
566 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
567 | |
|
|
568 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
|
|
569 | |
|
|
570 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
|
|
571 | always distinct from the default loop. |
|
|
572 | |
|
|
573 | Note that this function I<is> thread-safe, and one common way to use |
|
|
574 | libev with threads is indeed to create one loop per thread, and using the |
|
|
575 | default loop in the "main" or "initial" thread. |
|
|
576 | |
|
|
577 | Example: Try to create a event loop that uses epoll and nothing else. |
627 | Example: Try to create a event loop that uses epoll and nothing else. |
578 | |
628 | |
579 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
629 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
580 | if (!epoller) |
630 | if (!epoller) |
581 | fatal ("no epoll found here, maybe it hides under your chair"); |
631 | fatal ("no epoll found here, maybe it hides under your chair"); |
582 | |
632 | |
|
|
633 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
634 | used if available. |
|
|
635 | |
|
|
636 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
637 | |
583 | =item ev_default_destroy () |
638 | =item ev_loop_destroy (loop) |
584 | |
639 | |
585 | Destroys the default loop (frees all memory and kernel state etc.). None |
640 | Destroys an event loop object (frees all memory and kernel state |
586 | of the active event watchers will be stopped in the normal sense, so |
641 | etc.). None of the active event watchers will be stopped in the normal |
587 | e.g. C<ev_is_active> might still return true. It is your responsibility to |
642 | sense, so e.g. C<ev_is_active> might still return true. It is your |
588 | either stop all watchers cleanly yourself I<before> calling this function, |
643 | responsibility to either stop all watchers cleanly yourself I<before> |
589 | or cope with the fact afterwards (which is usually the easiest thing, you |
644 | calling this function, or cope with the fact afterwards (which is usually |
590 | can just ignore the watchers and/or C<free ()> them for example). |
645 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
|
|
646 | for example). |
591 | |
647 | |
592 | Note that certain global state, such as signal state (and installed signal |
648 | Note that certain global state, such as signal state (and installed signal |
593 | handlers), will not be freed by this function, and related watchers (such |
649 | handlers), will not be freed by this function, and related watchers (such |
594 | as signal and child watchers) would need to be stopped manually. |
650 | as signal and child watchers) would need to be stopped manually. |
595 | |
651 | |
596 | In general it is not advisable to call this function except in the |
652 | This function is normally used on loop objects allocated by |
597 | rare occasion where you really need to free e.g. the signal handling |
653 | C<ev_loop_new>, but it can also be used on the default loop returned by |
|
|
654 | C<ev_default_loop>, in which case it is not thread-safe. |
|
|
655 | |
|
|
656 | Note that it is not advisable to call this function on the default loop |
|
|
657 | except in the rare occasion where you really need to free its resources. |
598 | pipe fds. If you need dynamically allocated loops it is better to use |
658 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
599 | C<ev_loop_new> and C<ev_loop_destroy>. |
659 | and C<ev_loop_destroy>. |
600 | |
660 | |
601 | =item ev_loop_destroy (loop) |
661 | =item ev_loop_fork (loop) |
602 | |
662 | |
603 | Like C<ev_default_destroy>, but destroys an event loop created by an |
|
|
604 | earlier call to C<ev_loop_new>. |
|
|
605 | |
|
|
606 | =item ev_default_fork () |
|
|
607 | |
|
|
608 | This function sets a flag that causes subsequent C<ev_loop> iterations |
663 | This function sets a flag that causes subsequent C<ev_run> iterations to |
609 | to reinitialise the kernel state for backends that have one. Despite the |
664 | reinitialise the kernel state for backends that have one. Despite the |
610 | name, you can call it anytime, but it makes most sense after forking, in |
665 | name, you can call it anytime, but it makes most sense after forking, in |
611 | the child process (or both child and parent, but that again makes little |
666 | the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the |
612 | sense). You I<must> call it in the child before using any of the libev |
667 | child before resuming or calling C<ev_run>. |
613 | functions, and it will only take effect at the next C<ev_loop> iteration. |
|
|
614 | |
668 | |
615 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
669 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
616 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
670 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
617 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
671 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
618 | during fork. |
672 | during fork. |
619 | |
673 | |
620 | On the other hand, you only need to call this function in the child |
674 | On the other hand, you only need to call this function in the child |
621 | process if and only if you want to use the event loop in the child. If you |
675 | process if and only if you want to use the event loop in the child. If |
622 | just fork+exec or create a new loop in the child, you don't have to call |
676 | you just fork+exec or create a new loop in the child, you don't have to |
623 | it at all. |
677 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
|
|
678 | difference, but libev will usually detect this case on its own and do a |
|
|
679 | costly reset of the backend). |
624 | |
680 | |
625 | The function itself is quite fast and it's usually not a problem to call |
681 | The function itself is quite fast and it's usually not a problem to call |
626 | it just in case after a fork. To make this easy, the function will fit in |
682 | it just in case after a fork. |
627 | quite nicely into a call to C<pthread_atfork>: |
|
|
628 | |
683 | |
|
|
684 | Example: Automate calling C<ev_loop_fork> on the default loop when |
|
|
685 | using pthreads. |
|
|
686 | |
|
|
687 | static void |
|
|
688 | post_fork_child (void) |
|
|
689 | { |
|
|
690 | ev_loop_fork (EV_DEFAULT); |
|
|
691 | } |
|
|
692 | |
|
|
693 | ... |
629 | pthread_atfork (0, 0, ev_default_fork); |
694 | pthread_atfork (0, 0, post_fork_child); |
630 | |
|
|
631 | =item ev_loop_fork (loop) |
|
|
632 | |
|
|
633 | Like C<ev_default_fork>, but acts on an event loop created by |
|
|
634 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
|
|
635 | after fork that you want to re-use in the child, and how you keep track of |
|
|
636 | them is entirely your own problem. |
|
|
637 | |
695 | |
638 | =item int ev_is_default_loop (loop) |
696 | =item int ev_is_default_loop (loop) |
639 | |
697 | |
640 | Returns true when the given loop is, in fact, the default loop, and false |
698 | Returns true when the given loop is, in fact, the default loop, and false |
641 | otherwise. |
699 | otherwise. |
642 | |
700 | |
643 | =item unsigned int ev_iteration (loop) |
701 | =item unsigned int ev_iteration (loop) |
644 | |
702 | |
645 | Returns the current iteration count for the loop, which is identical to |
703 | Returns the current iteration count for the event loop, which is identical |
646 | the number of times libev did poll for new events. It starts at C<0> and |
704 | to the number of times libev did poll for new events. It starts at C<0> |
647 | happily wraps around with enough iterations. |
705 | and happily wraps around with enough iterations. |
648 | |
706 | |
649 | This value can sometimes be useful as a generation counter of sorts (it |
707 | This value can sometimes be useful as a generation counter of sorts (it |
650 | "ticks" the number of loop iterations), as it roughly corresponds with |
708 | "ticks" the number of loop iterations), as it roughly corresponds with |
651 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
709 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
652 | prepare and check phases. |
710 | prepare and check phases. |
653 | |
711 | |
654 | =item unsigned int ev_depth (loop) |
712 | =item unsigned int ev_depth (loop) |
655 | |
713 | |
656 | Returns the number of times C<ev_loop> was entered minus the number of |
714 | Returns the number of times C<ev_run> was entered minus the number of |
657 | times C<ev_loop> was exited, in other words, the recursion depth. |
715 | times C<ev_run> was exited normally, in other words, the recursion depth. |
658 | |
716 | |
659 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
717 | Outside C<ev_run>, this number is zero. In a callback, this number is |
660 | C<1>, unless C<ev_loop> was invoked recursively (or from another thread), |
718 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
661 | in which case it is higher. |
719 | in which case it is higher. |
662 | |
720 | |
663 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
721 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread, |
664 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
722 | throwing an exception etc.), doesn't count as "exit" - consider this |
665 | ungentleman behaviour unless it's really convenient. |
723 | as a hint to avoid such ungentleman-like behaviour unless it's really |
|
|
724 | convenient, in which case it is fully supported. |
666 | |
725 | |
667 | =item unsigned int ev_backend (loop) |
726 | =item unsigned int ev_backend (loop) |
668 | |
727 | |
669 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
728 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
670 | use. |
729 | use. |
… | |
… | |
679 | |
738 | |
680 | =item ev_now_update (loop) |
739 | =item ev_now_update (loop) |
681 | |
740 | |
682 | Establishes the current time by querying the kernel, updating the time |
741 | Establishes the current time by querying the kernel, updating the time |
683 | returned by C<ev_now ()> in the progress. This is a costly operation and |
742 | returned by C<ev_now ()> in the progress. This is a costly operation and |
684 | is usually done automatically within C<ev_loop ()>. |
743 | is usually done automatically within C<ev_run ()>. |
685 | |
744 | |
686 | This function is rarely useful, but when some event callback runs for a |
745 | This function is rarely useful, but when some event callback runs for a |
687 | very long time without entering the event loop, updating libev's idea of |
746 | very long time without entering the event loop, updating libev's idea of |
688 | the current time is a good idea. |
747 | the current time is a good idea. |
689 | |
748 | |
… | |
… | |
691 | |
750 | |
692 | =item ev_suspend (loop) |
751 | =item ev_suspend (loop) |
693 | |
752 | |
694 | =item ev_resume (loop) |
753 | =item ev_resume (loop) |
695 | |
754 | |
696 | These two functions suspend and resume a loop, for use when the loop is |
755 | These two functions suspend and resume an event loop, for use when the |
697 | not used for a while and timeouts should not be processed. |
756 | loop is not used for a while and timeouts should not be processed. |
698 | |
757 | |
699 | A typical use case would be an interactive program such as a game: When |
758 | A typical use case would be an interactive program such as a game: When |
700 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
759 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
701 | would be best to handle timeouts as if no time had actually passed while |
760 | would be best to handle timeouts as if no time had actually passed while |
702 | the program was suspended. This can be achieved by calling C<ev_suspend> |
761 | the program was suspended. This can be achieved by calling C<ev_suspend> |
… | |
… | |
704 | C<ev_resume> directly afterwards to resume timer processing. |
763 | C<ev_resume> directly afterwards to resume timer processing. |
705 | |
764 | |
706 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
765 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
707 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
766 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
708 | will be rescheduled (that is, they will lose any events that would have |
767 | will be rescheduled (that is, they will lose any events that would have |
709 | occured while suspended). |
768 | occurred while suspended). |
710 | |
769 | |
711 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
770 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
712 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
771 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
713 | without a previous call to C<ev_suspend>. |
772 | without a previous call to C<ev_suspend>. |
714 | |
773 | |
715 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
774 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
716 | event loop time (see C<ev_now_update>). |
775 | event loop time (see C<ev_now_update>). |
717 | |
776 | |
718 | =item ev_loop (loop, int flags) |
777 | =item ev_run (loop, int flags) |
719 | |
778 | |
720 | Finally, this is it, the event handler. This function usually is called |
779 | Finally, this is it, the event handler. This function usually is called |
721 | after you have initialised all your watchers and you want to start |
780 | after you have initialised all your watchers and you want to start |
722 | handling events. |
781 | handling events. It will ask the operating system for any new events, call |
|
|
782 | the watcher callbacks, an then repeat the whole process indefinitely: This |
|
|
783 | is why event loops are called I<loops>. |
723 | |
784 | |
724 | If the flags argument is specified as C<0>, it will not return until |
785 | If the flags argument is specified as C<0>, it will keep handling events |
725 | either no event watchers are active anymore or C<ev_unloop> was called. |
786 | until either no event watchers are active anymore or C<ev_break> was |
|
|
787 | called. |
726 | |
788 | |
727 | Please note that an explicit C<ev_unloop> is usually better than |
789 | Please note that an explicit C<ev_break> is usually better than |
728 | relying on all watchers to be stopped when deciding when a program has |
790 | relying on all watchers to be stopped when deciding when a program has |
729 | finished (especially in interactive programs), but having a program |
791 | finished (especially in interactive programs), but having a program |
730 | that automatically loops as long as it has to and no longer by virtue |
792 | that automatically loops as long as it has to and no longer by virtue |
731 | of relying on its watchers stopping correctly, that is truly a thing of |
793 | of relying on its watchers stopping correctly, that is truly a thing of |
732 | beauty. |
794 | beauty. |
733 | |
795 | |
|
|
796 | This function is also I<mostly> exception-safe - you can break out of |
|
|
797 | a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++ |
|
|
798 | exception and so on. This does not decrement the C<ev_depth> value, nor |
|
|
799 | will it clear any outstanding C<EVBREAK_ONE> breaks. |
|
|
800 | |
734 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
801 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
735 | those events and any already outstanding ones, but will not block your |
802 | those events and any already outstanding ones, but will not wait and |
736 | process in case there are no events and will return after one iteration of |
803 | block your process in case there are no events and will return after one |
737 | the loop. |
804 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
805 | events while doing lengthy calculations, to keep the program responsive. |
738 | |
806 | |
739 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
807 | A flags value of C<EVRUN_ONCE> will look for new events (waiting if |
740 | necessary) and will handle those and any already outstanding ones. It |
808 | necessary) and will handle those and any already outstanding ones. It |
741 | will block your process until at least one new event arrives (which could |
809 | will block your process until at least one new event arrives (which could |
742 | be an event internal to libev itself, so there is no guarantee that a |
810 | be an event internal to libev itself, so there is no guarantee that a |
743 | user-registered callback will be called), and will return after one |
811 | user-registered callback will be called), and will return after one |
744 | iteration of the loop. |
812 | iteration of the loop. |
745 | |
813 | |
746 | This is useful if you are waiting for some external event in conjunction |
814 | This is useful if you are waiting for some external event in conjunction |
747 | with something not expressible using other libev watchers (i.e. "roll your |
815 | with something not expressible using other libev watchers (i.e. "roll your |
748 | own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
816 | own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
749 | usually a better approach for this kind of thing. |
817 | usually a better approach for this kind of thing. |
750 | |
818 | |
751 | Here are the gory details of what C<ev_loop> does: |
819 | Here are the gory details of what C<ev_run> does: |
752 | |
820 | |
|
|
821 | - Increment loop depth. |
|
|
822 | - Reset the ev_break status. |
753 | - Before the first iteration, call any pending watchers. |
823 | - Before the first iteration, call any pending watchers. |
|
|
824 | LOOP: |
754 | * If EVFLAG_FORKCHECK was used, check for a fork. |
825 | - If EVFLAG_FORKCHECK was used, check for a fork. |
755 | - If a fork was detected (by any means), queue and call all fork watchers. |
826 | - If a fork was detected (by any means), queue and call all fork watchers. |
756 | - Queue and call all prepare watchers. |
827 | - Queue and call all prepare watchers. |
|
|
828 | - If ev_break was called, goto FINISH. |
757 | - If we have been forked, detach and recreate the kernel state |
829 | - If we have been forked, detach and recreate the kernel state |
758 | as to not disturb the other process. |
830 | as to not disturb the other process. |
759 | - Update the kernel state with all outstanding changes. |
831 | - Update the kernel state with all outstanding changes. |
760 | - Update the "event loop time" (ev_now ()). |
832 | - Update the "event loop time" (ev_now ()). |
761 | - Calculate for how long to sleep or block, if at all |
833 | - Calculate for how long to sleep or block, if at all |
762 | (active idle watchers, EVLOOP_NONBLOCK or not having |
834 | (active idle watchers, EVRUN_NOWAIT or not having |
763 | any active watchers at all will result in not sleeping). |
835 | any active watchers at all will result in not sleeping). |
764 | - Sleep if the I/O and timer collect interval say so. |
836 | - Sleep if the I/O and timer collect interval say so. |
|
|
837 | - Increment loop iteration counter. |
765 | - Block the process, waiting for any events. |
838 | - Block the process, waiting for any events. |
766 | - Queue all outstanding I/O (fd) events. |
839 | - Queue all outstanding I/O (fd) events. |
767 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
840 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
768 | - Queue all expired timers. |
841 | - Queue all expired timers. |
769 | - Queue all expired periodics. |
842 | - Queue all expired periodics. |
770 | - Unless any events are pending now, queue all idle watchers. |
843 | - Queue all idle watchers with priority higher than that of pending events. |
771 | - Queue all check watchers. |
844 | - Queue all check watchers. |
772 | - Call all queued watchers in reverse order (i.e. check watchers first). |
845 | - Call all queued watchers in reverse order (i.e. check watchers first). |
773 | Signals and child watchers are implemented as I/O watchers, and will |
846 | Signals and child watchers are implemented as I/O watchers, and will |
774 | be handled here by queueing them when their watcher gets executed. |
847 | be handled here by queueing them when their watcher gets executed. |
775 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
848 | - If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
776 | were used, or there are no active watchers, return, otherwise |
849 | were used, or there are no active watchers, goto FINISH, otherwise |
777 | continue with step *. |
850 | continue with step LOOP. |
|
|
851 | FINISH: |
|
|
852 | - Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
853 | - Decrement the loop depth. |
|
|
854 | - Return. |
778 | |
855 | |
779 | Example: Queue some jobs and then loop until no events are outstanding |
856 | Example: Queue some jobs and then loop until no events are outstanding |
780 | anymore. |
857 | anymore. |
781 | |
858 | |
782 | ... queue jobs here, make sure they register event watchers as long |
859 | ... queue jobs here, make sure they register event watchers as long |
783 | ... as they still have work to do (even an idle watcher will do..) |
860 | ... as they still have work to do (even an idle watcher will do..) |
784 | ev_loop (my_loop, 0); |
861 | ev_run (my_loop, 0); |
785 | ... jobs done or somebody called unloop. yeah! |
862 | ... jobs done or somebody called unloop. yeah! |
786 | |
863 | |
787 | =item ev_unloop (loop, how) |
864 | =item ev_break (loop, how) |
788 | |
865 | |
789 | Can be used to make a call to C<ev_loop> return early (but only after it |
866 | Can be used to make a call to C<ev_run> return early (but only after it |
790 | has processed all outstanding events). The C<how> argument must be either |
867 | has processed all outstanding events). The C<how> argument must be either |
791 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
868 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
792 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
869 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
793 | |
870 | |
794 | This "unloop state" will be cleared when entering C<ev_loop> again. |
871 | This "break state" will be cleared on the next call to C<ev_run>. |
795 | |
872 | |
796 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
873 | It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in |
|
|
874 | which case it will have no effect. |
797 | |
875 | |
798 | =item ev_ref (loop) |
876 | =item ev_ref (loop) |
799 | |
877 | |
800 | =item ev_unref (loop) |
878 | =item ev_unref (loop) |
801 | |
879 | |
802 | Ref/unref can be used to add or remove a reference count on the event |
880 | Ref/unref can be used to add or remove a reference count on the event |
803 | loop: Every watcher keeps one reference, and as long as the reference |
881 | loop: Every watcher keeps one reference, and as long as the reference |
804 | count is nonzero, C<ev_loop> will not return on its own. |
882 | count is nonzero, C<ev_run> will not return on its own. |
805 | |
883 | |
806 | This is useful when you have a watcher that you never intend to |
884 | This is useful when you have a watcher that you never intend to |
807 | unregister, but that nevertheless should not keep C<ev_loop> from |
885 | unregister, but that nevertheless should not keep C<ev_run> from |
808 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
886 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
809 | before stopping it. |
887 | before stopping it. |
810 | |
888 | |
811 | As an example, libev itself uses this for its internal signal pipe: It |
889 | As an example, libev itself uses this for its internal signal pipe: It |
812 | is not visible to the libev user and should not keep C<ev_loop> from |
890 | is not visible to the libev user and should not keep C<ev_run> from |
813 | exiting if no event watchers registered by it are active. It is also an |
891 | exiting if no event watchers registered by it are active. It is also an |
814 | excellent way to do this for generic recurring timers or from within |
892 | excellent way to do this for generic recurring timers or from within |
815 | third-party libraries. Just remember to I<unref after start> and I<ref |
893 | third-party libraries. Just remember to I<unref after start> and I<ref |
816 | before stop> (but only if the watcher wasn't active before, or was active |
894 | before stop> (but only if the watcher wasn't active before, or was active |
817 | before, respectively. Note also that libev might stop watchers itself |
895 | before, respectively. Note also that libev might stop watchers itself |
818 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
896 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
819 | in the callback). |
897 | in the callback). |
820 | |
898 | |
821 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
899 | Example: Create a signal watcher, but keep it from keeping C<ev_run> |
822 | running when nothing else is active. |
900 | running when nothing else is active. |
823 | |
901 | |
824 | ev_signal exitsig; |
902 | ev_signal exitsig; |
825 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
903 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
826 | ev_signal_start (loop, &exitsig); |
904 | ev_signal_start (loop, &exitsig); |
827 | evf_unref (loop); |
905 | ev_unref (loop); |
828 | |
906 | |
829 | Example: For some weird reason, unregister the above signal handler again. |
907 | Example: For some weird reason, unregister the above signal handler again. |
830 | |
908 | |
831 | ev_ref (loop); |
909 | ev_ref (loop); |
832 | ev_signal_stop (loop, &exitsig); |
910 | ev_signal_stop (loop, &exitsig); |
… | |
… | |
871 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
949 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
872 | as this approaches the timing granularity of most systems. Note that if |
950 | as this approaches the timing granularity of most systems. Note that if |
873 | you do transactions with the outside world and you can't increase the |
951 | you do transactions with the outside world and you can't increase the |
874 | parallelity, then this setting will limit your transaction rate (if you |
952 | parallelity, then this setting will limit your transaction rate (if you |
875 | need to poll once per transaction and the I/O collect interval is 0.01, |
953 | need to poll once per transaction and the I/O collect interval is 0.01, |
876 | then you can't do more than 100 transations per second). |
954 | then you can't do more than 100 transactions per second). |
877 | |
955 | |
878 | Setting the I<timeout collect interval> can improve the opportunity for |
956 | Setting the I<timeout collect interval> can improve the opportunity for |
879 | saving power, as the program will "bundle" timer callback invocations that |
957 | saving power, as the program will "bundle" timer callback invocations that |
880 | are "near" in time together, by delaying some, thus reducing the number of |
958 | are "near" in time together, by delaying some, thus reducing the number of |
881 | times the process sleeps and wakes up again. Another useful technique to |
959 | times the process sleeps and wakes up again. Another useful technique to |
… | |
… | |
889 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
967 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
890 | |
968 | |
891 | =item ev_invoke_pending (loop) |
969 | =item ev_invoke_pending (loop) |
892 | |
970 | |
893 | This call will simply invoke all pending watchers while resetting their |
971 | This call will simply invoke all pending watchers while resetting their |
894 | pending state. Normally, C<ev_loop> does this automatically when required, |
972 | pending state. Normally, C<ev_run> does this automatically when required, |
895 | but when overriding the invoke callback this call comes handy. |
973 | but when overriding the invoke callback this call comes handy. This |
|
|
974 | function can be invoked from a watcher - this can be useful for example |
|
|
975 | when you want to do some lengthy calculation and want to pass further |
|
|
976 | event handling to another thread (you still have to make sure only one |
|
|
977 | thread executes within C<ev_invoke_pending> or C<ev_run> of course). |
896 | |
978 | |
897 | =item int ev_pending_count (loop) |
979 | =item int ev_pending_count (loop) |
898 | |
980 | |
899 | Returns the number of pending watchers - zero indicates that no watchers |
981 | Returns the number of pending watchers - zero indicates that no watchers |
900 | are pending. |
982 | are pending. |
901 | |
983 | |
902 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
984 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
903 | |
985 | |
904 | This overrides the invoke pending functionality of the loop: Instead of |
986 | This overrides the invoke pending functionality of the loop: Instead of |
905 | invoking all pending watchers when there are any, C<ev_loop> will call |
987 | invoking all pending watchers when there are any, C<ev_run> will call |
906 | this callback instead. This is useful, for example, when you want to |
988 | this callback instead. This is useful, for example, when you want to |
907 | invoke the actual watchers inside another context (another thread etc.). |
989 | invoke the actual watchers inside another context (another thread etc.). |
908 | |
990 | |
909 | If you want to reset the callback, use C<ev_invoke_pending> as new |
991 | If you want to reset the callback, use C<ev_invoke_pending> as new |
910 | callback. |
992 | callback. |
… | |
… | |
913 | |
995 | |
914 | Sometimes you want to share the same loop between multiple threads. This |
996 | Sometimes you want to share the same loop between multiple threads. This |
915 | can be done relatively simply by putting mutex_lock/unlock calls around |
997 | can be done relatively simply by putting mutex_lock/unlock calls around |
916 | each call to a libev function. |
998 | each call to a libev function. |
917 | |
999 | |
918 | However, C<ev_loop> can run an indefinite time, so it is not feasible to |
1000 | However, C<ev_run> can run an indefinite time, so it is not feasible |
919 | wait for it to return. One way around this is to wake up the loop via |
1001 | to wait for it to return. One way around this is to wake up the event |
920 | C<ev_unloop> and C<av_async_send>, another way is to set these I<release> |
1002 | loop via C<ev_break> and C<av_async_send>, another way is to set these |
921 | and I<acquire> callbacks on the loop. |
1003 | I<release> and I<acquire> callbacks on the loop. |
922 | |
1004 | |
923 | When set, then C<release> will be called just before the thread is |
1005 | When set, then C<release> will be called just before the thread is |
924 | suspended waiting for new events, and C<acquire> is called just |
1006 | suspended waiting for new events, and C<acquire> is called just |
925 | afterwards. |
1007 | afterwards. |
926 | |
1008 | |
… | |
… | |
929 | |
1011 | |
930 | While event loop modifications are allowed between invocations of |
1012 | While event loop modifications are allowed between invocations of |
931 | C<release> and C<acquire> (that's their only purpose after all), no |
1013 | C<release> and C<acquire> (that's their only purpose after all), no |
932 | modifications done will affect the event loop, i.e. adding watchers will |
1014 | modifications done will affect the event loop, i.e. adding watchers will |
933 | have no effect on the set of file descriptors being watched, or the time |
1015 | have no effect on the set of file descriptors being watched, or the time |
934 | waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it |
1016 | waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it |
935 | to take note of any changes you made. |
1017 | to take note of any changes you made. |
936 | |
1018 | |
937 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
1019 | In theory, threads executing C<ev_run> will be async-cancel safe between |
938 | invocations of C<release> and C<acquire>. |
1020 | invocations of C<release> and C<acquire>. |
939 | |
1021 | |
940 | See also the locking example in the C<THREADS> section later in this |
1022 | See also the locking example in the C<THREADS> section later in this |
941 | document. |
1023 | document. |
942 | |
1024 | |
943 | =item ev_set_userdata (loop, void *data) |
1025 | =item ev_set_userdata (loop, void *data) |
944 | |
1026 | |
945 | =item ev_userdata (loop) |
1027 | =item void *ev_userdata (loop) |
946 | |
1028 | |
947 | Set and retrieve a single C<void *> associated with a loop. When |
1029 | Set and retrieve a single C<void *> associated with a loop. When |
948 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
1030 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
949 | C<0.> |
1031 | C<0>. |
950 | |
1032 | |
951 | These two functions can be used to associate arbitrary data with a loop, |
1033 | These two functions can be used to associate arbitrary data with a loop, |
952 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
1034 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
953 | C<acquire> callbacks described above, but of course can be (ab-)used for |
1035 | C<acquire> callbacks described above, but of course can be (ab-)used for |
954 | any other purpose as well. |
1036 | any other purpose as well. |
955 | |
1037 | |
956 | =item ev_loop_verify (loop) |
1038 | =item ev_verify (loop) |
957 | |
1039 | |
958 | This function only does something when C<EV_VERIFY> support has been |
1040 | This function only does something when C<EV_VERIFY> support has been |
959 | compiled in, which is the default for non-minimal builds. It tries to go |
1041 | compiled in, which is the default for non-minimal builds. It tries to go |
960 | through all internal structures and checks them for validity. If anything |
1042 | through all internal structures and checks them for validity. If anything |
961 | is found to be inconsistent, it will print an error message to standard |
1043 | is found to be inconsistent, it will print an error message to standard |
… | |
… | |
972 | |
1054 | |
973 | In the following description, uppercase C<TYPE> in names stands for the |
1055 | In the following description, uppercase C<TYPE> in names stands for the |
974 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
1056 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
975 | watchers and C<ev_io_start> for I/O watchers. |
1057 | watchers and C<ev_io_start> for I/O watchers. |
976 | |
1058 | |
977 | A watcher is a structure that you create and register to record your |
1059 | A watcher is an opaque structure that you allocate and register to record |
978 | interest in some event. For instance, if you want to wait for STDIN to |
1060 | your interest in some event. To make a concrete example, imagine you want |
979 | become readable, you would create an C<ev_io> watcher for that: |
1061 | to wait for STDIN to become readable, you would create an C<ev_io> watcher |
|
|
1062 | for that: |
980 | |
1063 | |
981 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
1064 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
982 | { |
1065 | { |
983 | ev_io_stop (w); |
1066 | ev_io_stop (w); |
984 | ev_unloop (loop, EVUNLOOP_ALL); |
1067 | ev_break (loop, EVBREAK_ALL); |
985 | } |
1068 | } |
986 | |
1069 | |
987 | struct ev_loop *loop = ev_default_loop (0); |
1070 | struct ev_loop *loop = ev_default_loop (0); |
988 | |
1071 | |
989 | ev_io stdin_watcher; |
1072 | ev_io stdin_watcher; |
990 | |
1073 | |
991 | ev_init (&stdin_watcher, my_cb); |
1074 | ev_init (&stdin_watcher, my_cb); |
992 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1075 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
993 | ev_io_start (loop, &stdin_watcher); |
1076 | ev_io_start (loop, &stdin_watcher); |
994 | |
1077 | |
995 | ev_loop (loop, 0); |
1078 | ev_run (loop, 0); |
996 | |
1079 | |
997 | As you can see, you are responsible for allocating the memory for your |
1080 | As you can see, you are responsible for allocating the memory for your |
998 | watcher structures (and it is I<usually> a bad idea to do this on the |
1081 | watcher structures (and it is I<usually> a bad idea to do this on the |
999 | stack). |
1082 | stack). |
1000 | |
1083 | |
1001 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
1084 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
1002 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
1085 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
1003 | |
1086 | |
1004 | Each watcher structure must be initialised by a call to C<ev_init |
1087 | Each watcher structure must be initialised by a call to C<ev_init (watcher |
1005 | (watcher *, callback)>, which expects a callback to be provided. This |
1088 | *, callback)>, which expects a callback to be provided. This callback is |
1006 | callback gets invoked each time the event occurs (or, in the case of I/O |
1089 | invoked each time the event occurs (or, in the case of I/O watchers, each |
1007 | watchers, each time the event loop detects that the file descriptor given |
1090 | time the event loop detects that the file descriptor given is readable |
1008 | is readable and/or writable). |
1091 | and/or writable). |
1009 | |
1092 | |
1010 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
1093 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
1011 | macro to configure it, with arguments specific to the watcher type. There |
1094 | macro to configure it, with arguments specific to the watcher type. There |
1012 | is also a macro to combine initialisation and setting in one call: C<< |
1095 | is also a macro to combine initialisation and setting in one call: C<< |
1013 | ev_TYPE_init (watcher *, callback, ...) >>. |
1096 | ev_TYPE_init (watcher *, callback, ...) >>. |
… | |
… | |
1064 | |
1147 | |
1065 | =item C<EV_PREPARE> |
1148 | =item C<EV_PREPARE> |
1066 | |
1149 | |
1067 | =item C<EV_CHECK> |
1150 | =item C<EV_CHECK> |
1068 | |
1151 | |
1069 | All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts |
1152 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
1070 | to gather new events, and all C<ev_check> watchers are invoked just after |
1153 | to gather new events, and all C<ev_check> watchers are invoked just after |
1071 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
1154 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
1072 | received events. Callbacks of both watcher types can start and stop as |
1155 | received events. Callbacks of both watcher types can start and stop as |
1073 | many watchers as they want, and all of them will be taken into account |
1156 | many watchers as they want, and all of them will be taken into account |
1074 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1157 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1075 | C<ev_loop> from blocking). |
1158 | C<ev_run> from blocking). |
1076 | |
1159 | |
1077 | =item C<EV_EMBED> |
1160 | =item C<EV_EMBED> |
1078 | |
1161 | |
1079 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1162 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1080 | |
1163 | |
1081 | =item C<EV_FORK> |
1164 | =item C<EV_FORK> |
1082 | |
1165 | |
1083 | The event loop has been resumed in the child process after fork (see |
1166 | The event loop has been resumed in the child process after fork (see |
1084 | C<ev_fork>). |
1167 | C<ev_fork>). |
|
|
1168 | |
|
|
1169 | =item C<EV_CLEANUP> |
|
|
1170 | |
|
|
1171 | The event loop is about to be destroyed (see C<ev_cleanup>). |
1085 | |
1172 | |
1086 | =item C<EV_ASYNC> |
1173 | =item C<EV_ASYNC> |
1087 | |
1174 | |
1088 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1175 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1089 | |
1176 | |
… | |
… | |
1261 | |
1348 | |
1262 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1349 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1263 | functions that do not need a watcher. |
1350 | functions that do not need a watcher. |
1264 | |
1351 | |
1265 | =back |
1352 | =back |
1266 | |
|
|
1267 | |
1353 | |
1268 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1354 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1269 | |
1355 | |
1270 | Each watcher has, by default, a member C<void *data> that you can change |
1356 | Each watcher has, by default, a member C<void *data> that you can change |
1271 | and read at any time: libev will completely ignore it. This can be used |
1357 | and read at any time: libev will completely ignore it. This can be used |
… | |
… | |
1327 | t2_cb (EV_P_ ev_timer *w, int revents) |
1413 | t2_cb (EV_P_ ev_timer *w, int revents) |
1328 | { |
1414 | { |
1329 | struct my_biggy big = (struct my_biggy *) |
1415 | struct my_biggy big = (struct my_biggy *) |
1330 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1416 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1331 | } |
1417 | } |
|
|
1418 | |
|
|
1419 | =head2 WATCHER STATES |
|
|
1420 | |
|
|
1421 | There are various watcher states mentioned throughout this manual - |
|
|
1422 | active, pending and so on. In this section these states and the rules to |
|
|
1423 | transition between them will be described in more detail - and while these |
|
|
1424 | rules might look complicated, they usually do "the right thing". |
|
|
1425 | |
|
|
1426 | =over 4 |
|
|
1427 | |
|
|
1428 | =item initialiased |
|
|
1429 | |
|
|
1430 | Before a watcher can be registered with the event looop it has to be |
|
|
1431 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1432 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
|
|
1433 | |
|
|
1434 | In this state it is simply some block of memory that is suitable for use |
|
|
1435 | in an event loop. It can be moved around, freed, reused etc. at will. |
|
|
1436 | |
|
|
1437 | =item started/running/active |
|
|
1438 | |
|
|
1439 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
|
|
1440 | property of the event loop, and is actively waiting for events. While in |
|
|
1441 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1442 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1443 | and call libev functions on it that are documented to work on active watchers. |
|
|
1444 | |
|
|
1445 | =item pending |
|
|
1446 | |
|
|
1447 | If a watcher is active and libev determines that an event it is interested |
|
|
1448 | in has occurred (such as a timer expiring), it will become pending. It will |
|
|
1449 | stay in this pending state until either it is stopped or its callback is |
|
|
1450 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1451 | callback. |
|
|
1452 | |
|
|
1453 | The watcher might or might not be active while it is pending (for example, |
|
|
1454 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1455 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1456 | but it is still property of the event loop at this time, so cannot be |
|
|
1457 | moved, freed or reused. And if it is active the rules described in the |
|
|
1458 | previous item still apply. |
|
|
1459 | |
|
|
1460 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1461 | via C<ev_feed_event>), in which case it becomes pending without being |
|
|
1462 | active. |
|
|
1463 | |
|
|
1464 | =item stopped |
|
|
1465 | |
|
|
1466 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1467 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
|
|
1468 | latter will clear any pending state the watcher might be in, regardless |
|
|
1469 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1470 | freeing it is often a good idea. |
|
|
1471 | |
|
|
1472 | While stopped (and not pending) the watcher is essentially in the |
|
|
1473 | initialised state, that is it can be reused, moved, modified in any way |
|
|
1474 | you wish. |
|
|
1475 | |
|
|
1476 | =back |
1332 | |
1477 | |
1333 | =head2 WATCHER PRIORITY MODELS |
1478 | =head2 WATCHER PRIORITY MODELS |
1334 | |
1479 | |
1335 | Many event loops support I<watcher priorities>, which are usually small |
1480 | Many event loops support I<watcher priorities>, which are usually small |
1336 | integers that influence the ordering of event callback invocation |
1481 | integers that influence the ordering of event callback invocation |
… | |
… | |
1379 | |
1524 | |
1380 | For example, to emulate how many other event libraries handle priorities, |
1525 | For example, to emulate how many other event libraries handle priorities, |
1381 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1526 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1382 | the normal watcher callback, you just start the idle watcher. The real |
1527 | the normal watcher callback, you just start the idle watcher. The real |
1383 | processing is done in the idle watcher callback. This causes libev to |
1528 | processing is done in the idle watcher callback. This causes libev to |
1384 | continously poll and process kernel event data for the watcher, but when |
1529 | continuously poll and process kernel event data for the watcher, but when |
1385 | the lock-out case is known to be rare (which in turn is rare :), this is |
1530 | the lock-out case is known to be rare (which in turn is rare :), this is |
1386 | workable. |
1531 | workable. |
1387 | |
1532 | |
1388 | Usually, however, the lock-out model implemented that way will perform |
1533 | Usually, however, the lock-out model implemented that way will perform |
1389 | miserably under the type of load it was designed to handle. In that case, |
1534 | miserably under the type of load it was designed to handle. In that case, |
… | |
… | |
1403 | { |
1548 | { |
1404 | // stop the I/O watcher, we received the event, but |
1549 | // stop the I/O watcher, we received the event, but |
1405 | // are not yet ready to handle it. |
1550 | // are not yet ready to handle it. |
1406 | ev_io_stop (EV_A_ w); |
1551 | ev_io_stop (EV_A_ w); |
1407 | |
1552 | |
1408 | // start the idle watcher to ahndle the actual event. |
1553 | // start the idle watcher to handle the actual event. |
1409 | // it will not be executed as long as other watchers |
1554 | // it will not be executed as long as other watchers |
1410 | // with the default priority are receiving events. |
1555 | // with the default priority are receiving events. |
1411 | ev_idle_start (EV_A_ &idle); |
1556 | ev_idle_start (EV_A_ &idle); |
1412 | } |
1557 | } |
1413 | |
1558 | |
… | |
… | |
1467 | |
1612 | |
1468 | If you cannot use non-blocking mode, then force the use of a |
1613 | If you cannot use non-blocking mode, then force the use of a |
1469 | known-to-be-good backend (at the time of this writing, this includes only |
1614 | known-to-be-good backend (at the time of this writing, this includes only |
1470 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1615 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1471 | descriptors for which non-blocking operation makes no sense (such as |
1616 | descriptors for which non-blocking operation makes no sense (such as |
1472 | files) - libev doesn't guarentee any specific behaviour in that case. |
1617 | files) - libev doesn't guarantee any specific behaviour in that case. |
1473 | |
1618 | |
1474 | Another thing you have to watch out for is that it is quite easy to |
1619 | Another thing you have to watch out for is that it is quite easy to |
1475 | receive "spurious" readiness notifications, that is your callback might |
1620 | receive "spurious" readiness notifications, that is your callback might |
1476 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1621 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1477 | because there is no data. Not only are some backends known to create a |
1622 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1621 | ... |
1766 | ... |
1622 | struct ev_loop *loop = ev_default_init (0); |
1767 | struct ev_loop *loop = ev_default_init (0); |
1623 | ev_io stdin_readable; |
1768 | ev_io stdin_readable; |
1624 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1769 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1625 | ev_io_start (loop, &stdin_readable); |
1770 | ev_io_start (loop, &stdin_readable); |
1626 | ev_loop (loop, 0); |
1771 | ev_run (loop, 0); |
1627 | |
1772 | |
1628 | |
1773 | |
1629 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1774 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1630 | |
1775 | |
1631 | Timer watchers are simple relative timers that generate an event after a |
1776 | Timer watchers are simple relative timers that generate an event after a |
… | |
… | |
1640 | The callback is guaranteed to be invoked only I<after> its timeout has |
1785 | The callback is guaranteed to be invoked only I<after> its timeout has |
1641 | passed (not I<at>, so on systems with very low-resolution clocks this |
1786 | passed (not I<at>, so on systems with very low-resolution clocks this |
1642 | might introduce a small delay). If multiple timers become ready during the |
1787 | might introduce a small delay). If multiple timers become ready during the |
1643 | same loop iteration then the ones with earlier time-out values are invoked |
1788 | same loop iteration then the ones with earlier time-out values are invoked |
1644 | before ones of the same priority with later time-out values (but this is |
1789 | before ones of the same priority with later time-out values (but this is |
1645 | no longer true when a callback calls C<ev_loop> recursively). |
1790 | no longer true when a callback calls C<ev_run> recursively). |
1646 | |
1791 | |
1647 | =head3 Be smart about timeouts |
1792 | =head3 Be smart about timeouts |
1648 | |
1793 | |
1649 | Many real-world problems involve some kind of timeout, usually for error |
1794 | Many real-world problems involve some kind of timeout, usually for error |
1650 | recovery. A typical example is an HTTP request - if the other side hangs, |
1795 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
1736 | ev_tstamp timeout = last_activity + 60.; |
1881 | ev_tstamp timeout = last_activity + 60.; |
1737 | |
1882 | |
1738 | // if last_activity + 60. is older than now, we did time out |
1883 | // if last_activity + 60. is older than now, we did time out |
1739 | if (timeout < now) |
1884 | if (timeout < now) |
1740 | { |
1885 | { |
1741 | // timeout occured, take action |
1886 | // timeout occurred, take action |
1742 | } |
1887 | } |
1743 | else |
1888 | else |
1744 | { |
1889 | { |
1745 | // callback was invoked, but there was some activity, re-arm |
1890 | // callback was invoked, but there was some activity, re-arm |
1746 | // the watcher to fire in last_activity + 60, which is |
1891 | // the watcher to fire in last_activity + 60, which is |
… | |
… | |
1773 | callback (loop, timer, EV_TIMER); |
1918 | callback (loop, timer, EV_TIMER); |
1774 | |
1919 | |
1775 | And when there is some activity, simply store the current time in |
1920 | And when there is some activity, simply store the current time in |
1776 | C<last_activity>, no libev calls at all: |
1921 | C<last_activity>, no libev calls at all: |
1777 | |
1922 | |
1778 | last_actiivty = ev_now (loop); |
1923 | last_activity = ev_now (loop); |
1779 | |
1924 | |
1780 | This technique is slightly more complex, but in most cases where the |
1925 | This technique is slightly more complex, but in most cases where the |
1781 | time-out is unlikely to be triggered, much more efficient. |
1926 | time-out is unlikely to be triggered, much more efficient. |
1782 | |
1927 | |
1783 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
1928 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
… | |
… | |
1821 | |
1966 | |
1822 | =head3 The special problem of time updates |
1967 | =head3 The special problem of time updates |
1823 | |
1968 | |
1824 | Establishing the current time is a costly operation (it usually takes at |
1969 | Establishing the current time is a costly operation (it usually takes at |
1825 | least two system calls): EV therefore updates its idea of the current |
1970 | least two system calls): EV therefore updates its idea of the current |
1826 | time only before and after C<ev_loop> collects new events, which causes a |
1971 | time only before and after C<ev_run> collects new events, which causes a |
1827 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1972 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1828 | lots of events in one iteration. |
1973 | lots of events in one iteration. |
1829 | |
1974 | |
1830 | The relative timeouts are calculated relative to the C<ev_now ()> |
1975 | The relative timeouts are calculated relative to the C<ev_now ()> |
1831 | time. This is usually the right thing as this timestamp refers to the time |
1976 | time. This is usually the right thing as this timestamp refers to the time |
… | |
… | |
1948 | } |
2093 | } |
1949 | |
2094 | |
1950 | ev_timer mytimer; |
2095 | ev_timer mytimer; |
1951 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2096 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1952 | ev_timer_again (&mytimer); /* start timer */ |
2097 | ev_timer_again (&mytimer); /* start timer */ |
1953 | ev_loop (loop, 0); |
2098 | ev_run (loop, 0); |
1954 | |
2099 | |
1955 | // and in some piece of code that gets executed on any "activity": |
2100 | // and in some piece of code that gets executed on any "activity": |
1956 | // reset the timeout to start ticking again at 10 seconds |
2101 | // reset the timeout to start ticking again at 10 seconds |
1957 | ev_timer_again (&mytimer); |
2102 | ev_timer_again (&mytimer); |
1958 | |
2103 | |
… | |
… | |
1984 | |
2129 | |
1985 | As with timers, the callback is guaranteed to be invoked only when the |
2130 | As with timers, the callback is guaranteed to be invoked only when the |
1986 | point in time where it is supposed to trigger has passed. If multiple |
2131 | point in time where it is supposed to trigger has passed. If multiple |
1987 | timers become ready during the same loop iteration then the ones with |
2132 | timers become ready during the same loop iteration then the ones with |
1988 | earlier time-out values are invoked before ones with later time-out values |
2133 | earlier time-out values are invoked before ones with later time-out values |
1989 | (but this is no longer true when a callback calls C<ev_loop> recursively). |
2134 | (but this is no longer true when a callback calls C<ev_run> recursively). |
1990 | |
2135 | |
1991 | =head3 Watcher-Specific Functions and Data Members |
2136 | =head3 Watcher-Specific Functions and Data Members |
1992 | |
2137 | |
1993 | =over 4 |
2138 | =over 4 |
1994 | |
2139 | |
… | |
… | |
2122 | Example: Call a callback every hour, or, more precisely, whenever the |
2267 | Example: Call a callback every hour, or, more precisely, whenever the |
2123 | system time is divisible by 3600. The callback invocation times have |
2268 | system time is divisible by 3600. The callback invocation times have |
2124 | potentially a lot of jitter, but good long-term stability. |
2269 | potentially a lot of jitter, but good long-term stability. |
2125 | |
2270 | |
2126 | static void |
2271 | static void |
2127 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2272 | clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
2128 | { |
2273 | { |
2129 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2274 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2130 | } |
2275 | } |
2131 | |
2276 | |
2132 | ev_periodic hourly_tick; |
2277 | ev_periodic hourly_tick; |
… | |
… | |
2155 | |
2300 | |
2156 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2301 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2157 | |
2302 | |
2158 | Signal watchers will trigger an event when the process receives a specific |
2303 | Signal watchers will trigger an event when the process receives a specific |
2159 | signal one or more times. Even though signals are very asynchronous, libev |
2304 | signal one or more times. Even though signals are very asynchronous, libev |
2160 | will try it's best to deliver signals synchronously, i.e. as part of the |
2305 | will try its best to deliver signals synchronously, i.e. as part of the |
2161 | normal event processing, like any other event. |
2306 | normal event processing, like any other event. |
2162 | |
2307 | |
2163 | If you want signals to be delivered truly asynchronously, just use |
2308 | If you want signals to be delivered truly asynchronously, just use |
2164 | C<sigaction> as you would do without libev and forget about sharing |
2309 | C<sigaction> as you would do without libev and forget about sharing |
2165 | the signal. You can even use C<ev_async> from a signal handler to |
2310 | the signal. You can even use C<ev_async> from a signal handler to |
… | |
… | |
2208 | |
2353 | |
2209 | So I can't stress this enough: I<If you do not reset your signal mask when |
2354 | So I can't stress this enough: I<If you do not reset your signal mask when |
2210 | you expect it to be empty, you have a race condition in your code>. This |
2355 | you expect it to be empty, you have a race condition in your code>. This |
2211 | is not a libev-specific thing, this is true for most event libraries. |
2356 | is not a libev-specific thing, this is true for most event libraries. |
2212 | |
2357 | |
|
|
2358 | =head3 The special problem of threads signal handling |
|
|
2359 | |
|
|
2360 | POSIX threads has problematic signal handling semantics, specifically, |
|
|
2361 | a lot of functionality (sigfd, sigwait etc.) only really works if all |
|
|
2362 | threads in a process block signals, which is hard to achieve. |
|
|
2363 | |
|
|
2364 | When you want to use sigwait (or mix libev signal handling with your own |
|
|
2365 | for the same signals), you can tackle this problem by globally blocking |
|
|
2366 | all signals before creating any threads (or creating them with a fully set |
|
|
2367 | sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating |
|
|
2368 | loops. Then designate one thread as "signal receiver thread" which handles |
|
|
2369 | these signals. You can pass on any signals that libev might be interested |
|
|
2370 | in by calling C<ev_feed_signal>. |
|
|
2371 | |
2213 | =head3 Watcher-Specific Functions and Data Members |
2372 | =head3 Watcher-Specific Functions and Data Members |
2214 | |
2373 | |
2215 | =over 4 |
2374 | =over 4 |
2216 | |
2375 | |
2217 | =item ev_signal_init (ev_signal *, callback, int signum) |
2376 | =item ev_signal_init (ev_signal *, callback, int signum) |
… | |
… | |
2232 | Example: Try to exit cleanly on SIGINT. |
2391 | Example: Try to exit cleanly on SIGINT. |
2233 | |
2392 | |
2234 | static void |
2393 | static void |
2235 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2394 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2236 | { |
2395 | { |
2237 | ev_unloop (loop, EVUNLOOP_ALL); |
2396 | ev_break (loop, EVBREAK_ALL); |
2238 | } |
2397 | } |
2239 | |
2398 | |
2240 | ev_signal signal_watcher; |
2399 | ev_signal signal_watcher; |
2241 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2400 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2242 | ev_signal_start (loop, &signal_watcher); |
2401 | ev_signal_start (loop, &signal_watcher); |
… | |
… | |
2628 | |
2787 | |
2629 | Prepare and check watchers are usually (but not always) used in pairs: |
2788 | Prepare and check watchers are usually (but not always) used in pairs: |
2630 | prepare watchers get invoked before the process blocks and check watchers |
2789 | prepare watchers get invoked before the process blocks and check watchers |
2631 | afterwards. |
2790 | afterwards. |
2632 | |
2791 | |
2633 | You I<must not> call C<ev_loop> or similar functions that enter |
2792 | You I<must not> call C<ev_run> or similar functions that enter |
2634 | the current event loop from either C<ev_prepare> or C<ev_check> |
2793 | the current event loop from either C<ev_prepare> or C<ev_check> |
2635 | watchers. Other loops than the current one are fine, however. The |
2794 | watchers. Other loops than the current one are fine, however. The |
2636 | rationale behind this is that you do not need to check for recursion in |
2795 | rationale behind this is that you do not need to check for recursion in |
2637 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2796 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2638 | C<ev_check> so if you have one watcher of each kind they will always be |
2797 | C<ev_check> so if you have one watcher of each kind they will always be |
… | |
… | |
2806 | |
2965 | |
2807 | if (timeout >= 0) |
2966 | if (timeout >= 0) |
2808 | // create/start timer |
2967 | // create/start timer |
2809 | |
2968 | |
2810 | // poll |
2969 | // poll |
2811 | ev_loop (EV_A_ 0); |
2970 | ev_run (EV_A_ 0); |
2812 | |
2971 | |
2813 | // stop timer again |
2972 | // stop timer again |
2814 | if (timeout >= 0) |
2973 | if (timeout >= 0) |
2815 | ev_timer_stop (EV_A_ &to); |
2974 | ev_timer_stop (EV_A_ &to); |
2816 | |
2975 | |
… | |
… | |
2894 | if you do not want that, you need to temporarily stop the embed watcher). |
3053 | if you do not want that, you need to temporarily stop the embed watcher). |
2895 | |
3054 | |
2896 | =item ev_embed_sweep (loop, ev_embed *) |
3055 | =item ev_embed_sweep (loop, ev_embed *) |
2897 | |
3056 | |
2898 | Make a single, non-blocking sweep over the embedded loop. This works |
3057 | Make a single, non-blocking sweep over the embedded loop. This works |
2899 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
3058 | similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most |
2900 | appropriate way for embedded loops. |
3059 | appropriate way for embedded loops. |
2901 | |
3060 | |
2902 | =item struct ev_loop *other [read-only] |
3061 | =item struct ev_loop *other [read-only] |
2903 | |
3062 | |
2904 | The embedded event loop. |
3063 | The embedded event loop. |
… | |
… | |
2964 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3123 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2965 | handlers will be invoked, too, of course. |
3124 | handlers will be invoked, too, of course. |
2966 | |
3125 | |
2967 | =head3 The special problem of life after fork - how is it possible? |
3126 | =head3 The special problem of life after fork - how is it possible? |
2968 | |
3127 | |
2969 | Most uses of C<fork()> consist of forking, then some simple calls to ste |
3128 | Most uses of C<fork()> consist of forking, then some simple calls to set |
2970 | up/change the process environment, followed by a call to C<exec()>. This |
3129 | up/change the process environment, followed by a call to C<exec()>. This |
2971 | sequence should be handled by libev without any problems. |
3130 | sequence should be handled by libev without any problems. |
2972 | |
3131 | |
2973 | This changes when the application actually wants to do event handling |
3132 | This changes when the application actually wants to do event handling |
2974 | in the child, or both parent in child, in effect "continuing" after the |
3133 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
2990 | disadvantage of having to use multiple event loops (which do not support |
3149 | disadvantage of having to use multiple event loops (which do not support |
2991 | signal watchers). |
3150 | signal watchers). |
2992 | |
3151 | |
2993 | When this is not possible, or you want to use the default loop for |
3152 | When this is not possible, or you want to use the default loop for |
2994 | other reasons, then in the process that wants to start "fresh", call |
3153 | other reasons, then in the process that wants to start "fresh", call |
2995 | C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying |
3154 | C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>. |
2996 | the default loop will "orphan" (not stop) all registered watchers, so you |
3155 | Destroying the default loop will "orphan" (not stop) all registered |
2997 | have to be careful not to execute code that modifies those watchers. Note |
3156 | watchers, so you have to be careful not to execute code that modifies |
2998 | also that in that case, you have to re-register any signal watchers. |
3157 | those watchers. Note also that in that case, you have to re-register any |
|
|
3158 | signal watchers. |
2999 | |
3159 | |
3000 | =head3 Watcher-Specific Functions and Data Members |
3160 | =head3 Watcher-Specific Functions and Data Members |
3001 | |
3161 | |
3002 | =over 4 |
3162 | =over 4 |
3003 | |
3163 | |
3004 | =item ev_fork_init (ev_signal *, callback) |
3164 | =item ev_fork_init (ev_fork *, callback) |
3005 | |
3165 | |
3006 | Initialises and configures the fork watcher - it has no parameters of any |
3166 | Initialises and configures the fork watcher - it has no parameters of any |
3007 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
3167 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
3008 | believe me. |
3168 | really. |
3009 | |
3169 | |
3010 | =back |
3170 | =back |
3011 | |
3171 | |
3012 | |
3172 | |
|
|
3173 | =head2 C<ev_cleanup> - even the best things end |
|
|
3174 | |
|
|
3175 | Cleanup watchers are called just before the event loop is being destroyed |
|
|
3176 | by a call to C<ev_loop_destroy>. |
|
|
3177 | |
|
|
3178 | While there is no guarantee that the event loop gets destroyed, cleanup |
|
|
3179 | watchers provide a convenient method to install cleanup hooks for your |
|
|
3180 | program, worker threads and so on - you just to make sure to destroy the |
|
|
3181 | loop when you want them to be invoked. |
|
|
3182 | |
|
|
3183 | Cleanup watchers are invoked in the same way as any other watcher. Unlike |
|
|
3184 | all other watchers, they do not keep a reference to the event loop (which |
|
|
3185 | makes a lot of sense if you think about it). Like all other watchers, you |
|
|
3186 | can call libev functions in the callback, except C<ev_cleanup_start>. |
|
|
3187 | |
|
|
3188 | =head3 Watcher-Specific Functions and Data Members |
|
|
3189 | |
|
|
3190 | =over 4 |
|
|
3191 | |
|
|
3192 | =item ev_cleanup_init (ev_cleanup *, callback) |
|
|
3193 | |
|
|
3194 | Initialises and configures the cleanup watcher - it has no parameters of |
|
|
3195 | any kind. There is a C<ev_cleanup_set> macro, but using it is utterly |
|
|
3196 | pointless, I assure you. |
|
|
3197 | |
|
|
3198 | =back |
|
|
3199 | |
|
|
3200 | Example: Register an atexit handler to destroy the default loop, so any |
|
|
3201 | cleanup functions are called. |
|
|
3202 | |
|
|
3203 | static void |
|
|
3204 | program_exits (void) |
|
|
3205 | { |
|
|
3206 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
3207 | } |
|
|
3208 | |
|
|
3209 | ... |
|
|
3210 | atexit (program_exits); |
|
|
3211 | |
|
|
3212 | |
3013 | =head2 C<ev_async> - how to wake up another event loop |
3213 | =head2 C<ev_async> - how to wake up an event loop |
3014 | |
3214 | |
3015 | In general, you cannot use an C<ev_loop> from multiple threads or other |
3215 | In general, you cannot use an C<ev_run> from multiple threads or other |
3016 | asynchronous sources such as signal handlers (as opposed to multiple event |
3216 | asynchronous sources such as signal handlers (as opposed to multiple event |
3017 | loops - those are of course safe to use in different threads). |
3217 | loops - those are of course safe to use in different threads). |
3018 | |
3218 | |
3019 | Sometimes, however, you need to wake up another event loop you do not |
3219 | Sometimes, however, you need to wake up an event loop you do not control, |
3020 | control, for example because it belongs to another thread. This is what |
3220 | for example because it belongs to another thread. This is what C<ev_async> |
3021 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
3221 | watchers do: as long as the C<ev_async> watcher is active, you can signal |
3022 | can signal it by calling C<ev_async_send>, which is thread- and signal |
3222 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3023 | safe. |
|
|
3024 | |
3223 | |
3025 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3224 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3026 | too, are asynchronous in nature, and signals, too, will be compressed |
3225 | too, are asynchronous in nature, and signals, too, will be compressed |
3027 | (i.e. the number of callback invocations may be less than the number of |
3226 | (i.e. the number of callback invocations may be less than the number of |
3028 | C<ev_async_sent> calls). |
3227 | C<ev_async_sent> calls). In fact, you could use signal watchers as a kind |
|
|
3228 | of "global async watchers" by using a watcher on an otherwise unused |
|
|
3229 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
|
|
3230 | even without knowing which loop owns the signal. |
3029 | |
3231 | |
3030 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
3232 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
3031 | just the default loop. |
3233 | just the default loop. |
3032 | |
3234 | |
3033 | =head3 Queueing |
3235 | =head3 Queueing |
… | |
… | |
3209 | Feed an event on the given fd, as if a file descriptor backend detected |
3411 | Feed an event on the given fd, as if a file descriptor backend detected |
3210 | the given events it. |
3412 | the given events it. |
3211 | |
3413 | |
3212 | =item ev_feed_signal_event (loop, int signum) |
3414 | =item ev_feed_signal_event (loop, int signum) |
3213 | |
3415 | |
3214 | Feed an event as if the given signal occurred (C<loop> must be the default |
3416 | Feed an event as if the given signal occurred. See also C<ev_feed_signal>, |
3215 | loop!). |
3417 | which is async-safe. |
|
|
3418 | |
|
|
3419 | =back |
|
|
3420 | |
|
|
3421 | |
|
|
3422 | =head1 COMMON OR USEFUL IDIOMS (OR BOTH) |
|
|
3423 | |
|
|
3424 | This section explains some common idioms that are not immediately |
|
|
3425 | obvious. Note that examples are sprinkled over the whole manual, and this |
|
|
3426 | section only contains stuff that wouldn't fit anywhere else. |
|
|
3427 | |
|
|
3428 | =over 4 |
|
|
3429 | |
|
|
3430 | =item Model/nested event loop invocations and exit conditions. |
|
|
3431 | |
|
|
3432 | Often (especially in GUI toolkits) there are places where you have |
|
|
3433 | I<modal> interaction, which is most easily implemented by recursively |
|
|
3434 | invoking C<ev_run>. |
|
|
3435 | |
|
|
3436 | This brings the problem of exiting - a callback might want to finish the |
|
|
3437 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
|
|
3438 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
|
|
3439 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
|
|
3440 | other combination: In these cases, C<ev_break> will not work alone. |
|
|
3441 | |
|
|
3442 | The solution is to maintain "break this loop" variable for each C<ev_run> |
|
|
3443 | invocation, and use a loop around C<ev_run> until the condition is |
|
|
3444 | triggered, using C<EVRUN_ONCE>: |
|
|
3445 | |
|
|
3446 | // main loop |
|
|
3447 | int exit_main_loop = 0; |
|
|
3448 | |
|
|
3449 | while (!exit_main_loop) |
|
|
3450 | ev_run (EV_DEFAULT_ EVRUN_ONCE); |
|
|
3451 | |
|
|
3452 | // in a model watcher |
|
|
3453 | int exit_nested_loop = 0; |
|
|
3454 | |
|
|
3455 | while (!exit_nested_loop) |
|
|
3456 | ev_run (EV_A_ EVRUN_ONCE); |
|
|
3457 | |
|
|
3458 | To exit from any of these loops, just set the corresponding exit variable: |
|
|
3459 | |
|
|
3460 | // exit modal loop |
|
|
3461 | exit_nested_loop = 1; |
|
|
3462 | |
|
|
3463 | // exit main program, after modal loop is finished |
|
|
3464 | exit_main_loop = 1; |
|
|
3465 | |
|
|
3466 | // exit both |
|
|
3467 | exit_main_loop = exit_nested_loop = 1; |
3216 | |
3468 | |
3217 | =back |
3469 | =back |
3218 | |
3470 | |
3219 | |
3471 | |
3220 | =head1 LIBEVENT EMULATION |
3472 | =head1 LIBEVENT EMULATION |
3221 | |
3473 | |
3222 | Libev offers a compatibility emulation layer for libevent. It cannot |
3474 | Libev offers a compatibility emulation layer for libevent. It cannot |
3223 | emulate the internals of libevent, so here are some usage hints: |
3475 | emulate the internals of libevent, so here are some usage hints: |
3224 | |
3476 | |
3225 | =over 4 |
3477 | =over 4 |
|
|
3478 | |
|
|
3479 | =item * Only the libevent-1.4.1-beta API is being emulated. |
|
|
3480 | |
|
|
3481 | This was the newest libevent version available when libev was implemented, |
|
|
3482 | and is still mostly unchanged in 2010. |
3226 | |
3483 | |
3227 | =item * Use it by including <event.h>, as usual. |
3484 | =item * Use it by including <event.h>, as usual. |
3228 | |
3485 | |
3229 | =item * The following members are fully supported: ev_base, ev_callback, |
3486 | =item * The following members are fully supported: ev_base, ev_callback, |
3230 | ev_arg, ev_fd, ev_res, ev_events. |
3487 | ev_arg, ev_fd, ev_res, ev_events. |
… | |
… | |
3236 | =item * Priorities are not currently supported. Initialising priorities |
3493 | =item * Priorities are not currently supported. Initialising priorities |
3237 | will fail and all watchers will have the same priority, even though there |
3494 | will fail and all watchers will have the same priority, even though there |
3238 | is an ev_pri field. |
3495 | is an ev_pri field. |
3239 | |
3496 | |
3240 | =item * In libevent, the last base created gets the signals, in libev, the |
3497 | =item * In libevent, the last base created gets the signals, in libev, the |
3241 | first base created (== the default loop) gets the signals. |
3498 | base that registered the signal gets the signals. |
3242 | |
3499 | |
3243 | =item * Other members are not supported. |
3500 | =item * Other members are not supported. |
3244 | |
3501 | |
3245 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
3502 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
3246 | to use the libev header file and library. |
3503 | to use the libev header file and library. |
… | |
… | |
3265 | Care has been taken to keep the overhead low. The only data member the C++ |
3522 | Care has been taken to keep the overhead low. The only data member the C++ |
3266 | classes add (compared to plain C-style watchers) is the event loop pointer |
3523 | classes add (compared to plain C-style watchers) is the event loop pointer |
3267 | that the watcher is associated with (or no additional members at all if |
3524 | that the watcher is associated with (or no additional members at all if |
3268 | you disable C<EV_MULTIPLICITY> when embedding libev). |
3525 | you disable C<EV_MULTIPLICITY> when embedding libev). |
3269 | |
3526 | |
3270 | Currently, functions, and static and non-static member functions can be |
3527 | Currently, functions, static and non-static member functions and classes |
3271 | used as callbacks. Other types should be easy to add as long as they only |
3528 | with C<operator ()> can be used as callbacks. Other types should be easy |
3272 | need one additional pointer for context. If you need support for other |
3529 | to add as long as they only need one additional pointer for context. If |
3273 | types of functors please contact the author (preferably after implementing |
3530 | you need support for other types of functors please contact the author |
3274 | it). |
3531 | (preferably after implementing it). |
3275 | |
3532 | |
3276 | Here is a list of things available in the C<ev> namespace: |
3533 | Here is a list of things available in the C<ev> namespace: |
3277 | |
3534 | |
3278 | =over 4 |
3535 | =over 4 |
3279 | |
3536 | |
… | |
… | |
3340 | myclass obj; |
3597 | myclass obj; |
3341 | ev::io iow; |
3598 | ev::io iow; |
3342 | iow.set <myclass, &myclass::io_cb> (&obj); |
3599 | iow.set <myclass, &myclass::io_cb> (&obj); |
3343 | |
3600 | |
3344 | =item w->set (object *) |
3601 | =item w->set (object *) |
3345 | |
|
|
3346 | This is an B<experimental> feature that might go away in a future version. |
|
|
3347 | |
3602 | |
3348 | This is a variation of a method callback - leaving out the method to call |
3603 | This is a variation of a method callback - leaving out the method to call |
3349 | will default the method to C<operator ()>, which makes it possible to use |
3604 | will default the method to C<operator ()>, which makes it possible to use |
3350 | functor objects without having to manually specify the C<operator ()> all |
3605 | functor objects without having to manually specify the C<operator ()> all |
3351 | the time. Incidentally, you can then also leave out the template argument |
3606 | the time. Incidentally, you can then also leave out the template argument |
… | |
… | |
3391 | Associates a different C<struct ev_loop> with this watcher. You can only |
3646 | Associates a different C<struct ev_loop> with this watcher. You can only |
3392 | do this when the watcher is inactive (and not pending either). |
3647 | do this when the watcher is inactive (and not pending either). |
3393 | |
3648 | |
3394 | =item w->set ([arguments]) |
3649 | =item w->set ([arguments]) |
3395 | |
3650 | |
3396 | Basically the same as C<ev_TYPE_set>, with the same arguments. Must be |
3651 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
3397 | called at least once. Unlike the C counterpart, an active watcher gets |
3652 | method or a suitable start method must be called at least once. Unlike the |
3398 | automatically stopped and restarted when reconfiguring it with this |
3653 | C counterpart, an active watcher gets automatically stopped and restarted |
3399 | method. |
3654 | when reconfiguring it with this method. |
3400 | |
3655 | |
3401 | =item w->start () |
3656 | =item w->start () |
3402 | |
3657 | |
3403 | Starts the watcher. Note that there is no C<loop> argument, as the |
3658 | Starts the watcher. Note that there is no C<loop> argument, as the |
3404 | constructor already stores the event loop. |
3659 | constructor already stores the event loop. |
3405 | |
3660 | |
|
|
3661 | =item w->start ([arguments]) |
|
|
3662 | |
|
|
3663 | Instead of calling C<set> and C<start> methods separately, it is often |
|
|
3664 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
3665 | the configure C<set> method of the watcher. |
|
|
3666 | |
3406 | =item w->stop () |
3667 | =item w->stop () |
3407 | |
3668 | |
3408 | Stops the watcher if it is active. Again, no C<loop> argument. |
3669 | Stops the watcher if it is active. Again, no C<loop> argument. |
3409 | |
3670 | |
3410 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
3671 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
… | |
… | |
3422 | |
3683 | |
3423 | =back |
3684 | =back |
3424 | |
3685 | |
3425 | =back |
3686 | =back |
3426 | |
3687 | |
3427 | Example: Define a class with an IO and idle watcher, start one of them in |
3688 | Example: Define a class with two I/O and idle watchers, start the I/O |
3428 | the constructor. |
3689 | watchers in the constructor. |
3429 | |
3690 | |
3430 | class myclass |
3691 | class myclass |
3431 | { |
3692 | { |
3432 | ev::io io ; void io_cb (ev::io &w, int revents); |
3693 | ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
3694 | ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
3433 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3695 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3434 | |
3696 | |
3435 | myclass (int fd) |
3697 | myclass (int fd) |
3436 | { |
3698 | { |
3437 | io .set <myclass, &myclass::io_cb > (this); |
3699 | io .set <myclass, &myclass::io_cb > (this); |
|
|
3700 | io2 .set <myclass, &myclass::io2_cb > (this); |
3438 | idle.set <myclass, &myclass::idle_cb> (this); |
3701 | idle.set <myclass, &myclass::idle_cb> (this); |
3439 | |
3702 | |
3440 | io.start (fd, ev::READ); |
3703 | io.set (fd, ev::WRITE); // configure the watcher |
|
|
3704 | io.start (); // start it whenever convenient |
|
|
3705 | |
|
|
3706 | io2.start (fd, ev::READ); // set + start in one call |
3441 | } |
3707 | } |
3442 | }; |
3708 | }; |
3443 | |
3709 | |
3444 | |
3710 | |
3445 | =head1 OTHER LANGUAGE BINDINGS |
3711 | =head1 OTHER LANGUAGE BINDINGS |
… | |
… | |
3519 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3785 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3520 | C<EV_A_> is used when other arguments are following. Example: |
3786 | C<EV_A_> is used when other arguments are following. Example: |
3521 | |
3787 | |
3522 | ev_unref (EV_A); |
3788 | ev_unref (EV_A); |
3523 | ev_timer_add (EV_A_ watcher); |
3789 | ev_timer_add (EV_A_ watcher); |
3524 | ev_loop (EV_A_ 0); |
3790 | ev_run (EV_A_ 0); |
3525 | |
3791 | |
3526 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3792 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3527 | which is often provided by the following macro. |
3793 | which is often provided by the following macro. |
3528 | |
3794 | |
3529 | =item C<EV_P>, C<EV_P_> |
3795 | =item C<EV_P>, C<EV_P_> |
… | |
… | |
3569 | } |
3835 | } |
3570 | |
3836 | |
3571 | ev_check check; |
3837 | ev_check check; |
3572 | ev_check_init (&check, check_cb); |
3838 | ev_check_init (&check, check_cb); |
3573 | ev_check_start (EV_DEFAULT_ &check); |
3839 | ev_check_start (EV_DEFAULT_ &check); |
3574 | ev_loop (EV_DEFAULT_ 0); |
3840 | ev_run (EV_DEFAULT_ 0); |
3575 | |
3841 | |
3576 | =head1 EMBEDDING |
3842 | =head1 EMBEDDING |
3577 | |
3843 | |
3578 | Libev can (and often is) directly embedded into host |
3844 | Libev can (and often is) directly embedded into host |
3579 | applications. Examples of applications that embed it include the Deliantra |
3845 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3670 | to a compiled library. All other symbols change the ABI, which means all |
3936 | to a compiled library. All other symbols change the ABI, which means all |
3671 | users of libev and the libev code itself must be compiled with compatible |
3937 | users of libev and the libev code itself must be compiled with compatible |
3672 | settings. |
3938 | settings. |
3673 | |
3939 | |
3674 | =over 4 |
3940 | =over 4 |
|
|
3941 | |
|
|
3942 | =item EV_COMPAT3 (h) |
|
|
3943 | |
|
|
3944 | Backwards compatibility is a major concern for libev. This is why this |
|
|
3945 | release of libev comes with wrappers for the functions and symbols that |
|
|
3946 | have been renamed between libev version 3 and 4. |
|
|
3947 | |
|
|
3948 | You can disable these wrappers (to test compatibility with future |
|
|
3949 | versions) by defining C<EV_COMPAT3> to C<0> when compiling your |
|
|
3950 | sources. This has the additional advantage that you can drop the C<struct> |
|
|
3951 | from C<struct ev_loop> declarations, as libev will provide an C<ev_loop> |
|
|
3952 | typedef in that case. |
|
|
3953 | |
|
|
3954 | In some future version, the default for C<EV_COMPAT3> will become C<0>, |
|
|
3955 | and in some even more future version the compatibility code will be |
|
|
3956 | removed completely. |
3675 | |
3957 | |
3676 | =item EV_STANDALONE (h) |
3958 | =item EV_STANDALONE (h) |
3677 | |
3959 | |
3678 | Must always be C<1> if you do not use autoconf configuration, which |
3960 | Must always be C<1> if you do not use autoconf configuration, which |
3679 | keeps libev from including F<config.h>, and it also defines dummy |
3961 | keeps libev from including F<config.h>, and it also defines dummy |
… | |
… | |
3886 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
4168 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
3887 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
4169 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3888 | |
4170 | |
3889 | If undefined or defined to be C<1> (and the platform supports it), then |
4171 | If undefined or defined to be C<1> (and the platform supports it), then |
3890 | the respective watcher type is supported. If defined to be C<0>, then it |
4172 | the respective watcher type is supported. If defined to be C<0>, then it |
3891 | is not. Disabling watcher types mainly saves codesize. |
4173 | is not. Disabling watcher types mainly saves code size. |
3892 | |
4174 | |
3893 | =item EV_FEATURES |
4175 | =item EV_FEATURES |
3894 | |
4176 | |
3895 | If you need to shave off some kilobytes of code at the expense of some |
4177 | If you need to shave off some kilobytes of code at the expense of some |
3896 | speed (but with the full API), you can define this symbol to request |
4178 | speed (but with the full API), you can define this symbol to request |
… | |
… | |
3916 | |
4198 | |
3917 | =item C<1> - faster/larger code |
4199 | =item C<1> - faster/larger code |
3918 | |
4200 | |
3919 | Use larger code to speed up some operations. |
4201 | Use larger code to speed up some operations. |
3920 | |
4202 | |
3921 | Currently this is used to override some inlining decisions (enlarging the roughly |
4203 | Currently this is used to override some inlining decisions (enlarging the |
3922 | 30% code size on amd64. |
4204 | code size by roughly 30% on amd64). |
3923 | |
4205 | |
3924 | When optimising for size, use of compiler flags such as C<-Os> with |
4206 | When optimising for size, use of compiler flags such as C<-Os> with |
3925 | gcc recommended, as well as C<-DNDEBUG>, as libev contains a number of |
4207 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
3926 | assertions. |
4208 | assertions. |
3927 | |
4209 | |
3928 | =item C<2> - faster/larger data structures |
4210 | =item C<2> - faster/larger data structures |
3929 | |
4211 | |
3930 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
4212 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
3931 | hash table sizes and so on. This will usually further increase codesize |
4213 | hash table sizes and so on. This will usually further increase code size |
3932 | and can additionally have an effect on the size of data structures at |
4214 | and can additionally have an effect on the size of data structures at |
3933 | runtime. |
4215 | runtime. |
3934 | |
4216 | |
3935 | =item C<4> - full API configuration |
4217 | =item C<4> - full API configuration |
3936 | |
4218 | |
… | |
… | |
3973 | I/O watcher then might come out at only 5Kb. |
4255 | I/O watcher then might come out at only 5Kb. |
3974 | |
4256 | |
3975 | =item EV_AVOID_STDIO |
4257 | =item EV_AVOID_STDIO |
3976 | |
4258 | |
3977 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
4259 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
3978 | functions (printf, scanf, perror etc.). This will increase the codesize |
4260 | functions (printf, scanf, perror etc.). This will increase the code size |
3979 | somewhat, but if your program doesn't otherwise depend on stdio and your |
4261 | somewhat, but if your program doesn't otherwise depend on stdio and your |
3980 | libc allows it, this avoids linking in the stdio library which is quite |
4262 | libc allows it, this avoids linking in the stdio library which is quite |
3981 | big. |
4263 | big. |
3982 | |
4264 | |
3983 | Note that error messages might become less precise when this option is |
4265 | Note that error messages might become less precise when this option is |
… | |
… | |
3987 | |
4269 | |
3988 | The highest supported signal number, +1 (or, the number of |
4270 | The highest supported signal number, +1 (or, the number of |
3989 | signals): Normally, libev tries to deduce the maximum number of signals |
4271 | signals): Normally, libev tries to deduce the maximum number of signals |
3990 | automatically, but sometimes this fails, in which case it can be |
4272 | automatically, but sometimes this fails, in which case it can be |
3991 | specified. Also, using a lower number than detected (C<32> should be |
4273 | specified. Also, using a lower number than detected (C<32> should be |
3992 | good for about any system in existance) can save some memory, as libev |
4274 | good for about any system in existence) can save some memory, as libev |
3993 | statically allocates some 12-24 bytes per signal number. |
4275 | statically allocates some 12-24 bytes per signal number. |
3994 | |
4276 | |
3995 | =item EV_PID_HASHSIZE |
4277 | =item EV_PID_HASHSIZE |
3996 | |
4278 | |
3997 | C<ev_child> watchers use a small hash table to distribute workload by |
4279 | C<ev_child> watchers use a small hash table to distribute workload by |
… | |
… | |
4029 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
4311 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
4030 | will be C<0>. |
4312 | will be C<0>. |
4031 | |
4313 | |
4032 | =item EV_VERIFY |
4314 | =item EV_VERIFY |
4033 | |
4315 | |
4034 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4316 | Controls how much internal verification (see C<ev_verify ()>) will |
4035 | be done: If set to C<0>, no internal verification code will be compiled |
4317 | be done: If set to C<0>, no internal verification code will be compiled |
4036 | in. If set to C<1>, then verification code will be compiled in, but not |
4318 | in. If set to C<1>, then verification code will be compiled in, but not |
4037 | called. If set to C<2>, then the internal verification code will be |
4319 | called. If set to C<2>, then the internal verification code will be |
4038 | called once per loop, which can slow down libev. If set to C<3>, then the |
4320 | called once per loop, which can slow down libev. If set to C<3>, then the |
4039 | verification code will be called very frequently, which will slow down |
4321 | verification code will be called very frequently, which will slow down |
… | |
… | |
4043 | will be C<0>. |
4325 | will be C<0>. |
4044 | |
4326 | |
4045 | =item EV_COMMON |
4327 | =item EV_COMMON |
4046 | |
4328 | |
4047 | By default, all watchers have a C<void *data> member. By redefining |
4329 | By default, all watchers have a C<void *data> member. By redefining |
4048 | this macro to a something else you can include more and other types of |
4330 | this macro to something else you can include more and other types of |
4049 | members. You have to define it each time you include one of the files, |
4331 | members. You have to define it each time you include one of the files, |
4050 | though, and it must be identical each time. |
4332 | though, and it must be identical each time. |
4051 | |
4333 | |
4052 | For example, the perl EV module uses something like this: |
4334 | For example, the perl EV module uses something like this: |
4053 | |
4335 | |
… | |
… | |
4254 | userdata *u = ev_userdata (EV_A); |
4536 | userdata *u = ev_userdata (EV_A); |
4255 | pthread_mutex_lock (&u->lock); |
4537 | pthread_mutex_lock (&u->lock); |
4256 | } |
4538 | } |
4257 | |
4539 | |
4258 | The event loop thread first acquires the mutex, and then jumps straight |
4540 | The event loop thread first acquires the mutex, and then jumps straight |
4259 | into C<ev_loop>: |
4541 | into C<ev_run>: |
4260 | |
4542 | |
4261 | void * |
4543 | void * |
4262 | l_run (void *thr_arg) |
4544 | l_run (void *thr_arg) |
4263 | { |
4545 | { |
4264 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4546 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4265 | |
4547 | |
4266 | l_acquire (EV_A); |
4548 | l_acquire (EV_A); |
4267 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4549 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4268 | ev_loop (EV_A_ 0); |
4550 | ev_run (EV_A_ 0); |
4269 | l_release (EV_A); |
4551 | l_release (EV_A); |
4270 | |
4552 | |
4271 | return 0; |
4553 | return 0; |
4272 | } |
4554 | } |
4273 | |
4555 | |
… | |
… | |
4325 | |
4607 | |
4326 | =head3 COROUTINES |
4608 | =head3 COROUTINES |
4327 | |
4609 | |
4328 | Libev is very accommodating to coroutines ("cooperative threads"): |
4610 | Libev is very accommodating to coroutines ("cooperative threads"): |
4329 | libev fully supports nesting calls to its functions from different |
4611 | libev fully supports nesting calls to its functions from different |
4330 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4612 | coroutines (e.g. you can call C<ev_run> on the same loop from two |
4331 | different coroutines, and switch freely between both coroutines running |
4613 | different coroutines, and switch freely between both coroutines running |
4332 | the loop, as long as you don't confuse yourself). The only exception is |
4614 | the loop, as long as you don't confuse yourself). The only exception is |
4333 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4615 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4334 | |
4616 | |
4335 | Care has been taken to ensure that libev does not keep local state inside |
4617 | Care has been taken to ensure that libev does not keep local state inside |
4336 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4618 | C<ev_run>, and other calls do not usually allow for coroutine switches as |
4337 | they do not call any callbacks. |
4619 | they do not call any callbacks. |
4338 | |
4620 | |
4339 | =head2 COMPILER WARNINGS |
4621 | =head2 COMPILER WARNINGS |
4340 | |
4622 | |
4341 | Depending on your compiler and compiler settings, you might get no or a |
4623 | Depending on your compiler and compiler settings, you might get no or a |
… | |
… | |
4352 | maintainable. |
4634 | maintainable. |
4353 | |
4635 | |
4354 | And of course, some compiler warnings are just plain stupid, or simply |
4636 | And of course, some compiler warnings are just plain stupid, or simply |
4355 | wrong (because they don't actually warn about the condition their message |
4637 | wrong (because they don't actually warn about the condition their message |
4356 | seems to warn about). For example, certain older gcc versions had some |
4638 | seems to warn about). For example, certain older gcc versions had some |
4357 | warnings that resulted an extreme number of false positives. These have |
4639 | warnings that resulted in an extreme number of false positives. These have |
4358 | been fixed, but some people still insist on making code warn-free with |
4640 | been fixed, but some people still insist on making code warn-free with |
4359 | such buggy versions. |
4641 | such buggy versions. |
4360 | |
4642 | |
4361 | While libev is written to generate as few warnings as possible, |
4643 | While libev is written to generate as few warnings as possible, |
4362 | "warn-free" code is not a goal, and it is recommended not to build libev |
4644 | "warn-free" code is not a goal, and it is recommended not to build libev |
… | |
… | |
4398 | I suggest using suppression lists. |
4680 | I suggest using suppression lists. |
4399 | |
4681 | |
4400 | |
4682 | |
4401 | =head1 PORTABILITY NOTES |
4683 | =head1 PORTABILITY NOTES |
4402 | |
4684 | |
|
|
4685 | =head2 GNU/LINUX 32 BIT LIMITATIONS |
|
|
4686 | |
|
|
4687 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
4688 | interfaces but I<disables> them by default. |
|
|
4689 | |
|
|
4690 | That means that libev compiled in the default environment doesn't support |
|
|
4691 | files larger than 2GiB or so, which mainly affects C<ev_stat> watchers. |
|
|
4692 | |
|
|
4693 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
4694 | by enabling the large file API, which makes them incompatible with the |
|
|
4695 | standard libev compiled for their system. |
|
|
4696 | |
|
|
4697 | Likewise, libev cannot enable the large file API itself as this would |
|
|
4698 | suddenly make it incompatible to the default compile time environment, |
|
|
4699 | i.e. all programs not using special compile switches. |
|
|
4700 | |
|
|
4701 | =head2 OS/X AND DARWIN BUGS |
|
|
4702 | |
|
|
4703 | The whole thing is a bug if you ask me - basically any system interface |
|
|
4704 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
4705 | OpenGL drivers. |
|
|
4706 | |
|
|
4707 | =head3 C<kqueue> is buggy |
|
|
4708 | |
|
|
4709 | The kqueue syscall is broken in all known versions - most versions support |
|
|
4710 | only sockets, many support pipes. |
|
|
4711 | |
|
|
4712 | Libev tries to work around this by not using C<kqueue> by default on this |
|
|
4713 | rotten platform, but of course you can still ask for it when creating a |
|
|
4714 | loop - embedding a socket-only kqueue loop into a select-based one is |
|
|
4715 | probably going to work well. |
|
|
4716 | |
|
|
4717 | =head3 C<poll> is buggy |
|
|
4718 | |
|
|
4719 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
|
|
4720 | implementation by something calling C<kqueue> internally around the 10.5.6 |
|
|
4721 | release, so now C<kqueue> I<and> C<poll> are broken. |
|
|
4722 | |
|
|
4723 | Libev tries to work around this by not using C<poll> by default on |
|
|
4724 | this rotten platform, but of course you can still ask for it when creating |
|
|
4725 | a loop. |
|
|
4726 | |
|
|
4727 | =head3 C<select> is buggy |
|
|
4728 | |
|
|
4729 | All that's left is C<select>, and of course Apple found a way to fuck this |
|
|
4730 | one up as well: On OS/X, C<select> actively limits the number of file |
|
|
4731 | descriptors you can pass in to 1024 - your program suddenly crashes when |
|
|
4732 | you use more. |
|
|
4733 | |
|
|
4734 | There is an undocumented "workaround" for this - defining |
|
|
4735 | C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should> |
|
|
4736 | work on OS/X. |
|
|
4737 | |
|
|
4738 | =head2 SOLARIS PROBLEMS AND WORKAROUNDS |
|
|
4739 | |
|
|
4740 | =head3 C<errno> reentrancy |
|
|
4741 | |
|
|
4742 | The default compile environment on Solaris is unfortunately so |
|
|
4743 | thread-unsafe that you can't even use components/libraries compiled |
|
|
4744 | without C<-D_REENTRANT> in a threaded program, which, of course, isn't |
|
|
4745 | defined by default. A valid, if stupid, implementation choice. |
|
|
4746 | |
|
|
4747 | If you want to use libev in threaded environments you have to make sure |
|
|
4748 | it's compiled with C<_REENTRANT> defined. |
|
|
4749 | |
|
|
4750 | =head3 Event port backend |
|
|
4751 | |
|
|
4752 | The scalable event interface for Solaris is called "event |
|
|
4753 | ports". Unfortunately, this mechanism is very buggy in all major |
|
|
4754 | releases. If you run into high CPU usage, your program freezes or you get |
|
|
4755 | a large number of spurious wakeups, make sure you have all the relevant |
|
|
4756 | and latest kernel patches applied. No, I don't know which ones, but there |
|
|
4757 | are multiple ones to apply, and afterwards, event ports actually work |
|
|
4758 | great. |
|
|
4759 | |
|
|
4760 | If you can't get it to work, you can try running the program by setting |
|
|
4761 | the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and |
|
|
4762 | C<select> backends. |
|
|
4763 | |
|
|
4764 | =head2 AIX POLL BUG |
|
|
4765 | |
|
|
4766 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
|
|
4767 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
4768 | compiled in), which normally isn't a big problem as C<select> works fine |
|
|
4769 | with large bitsets on AIX, and AIX is dead anyway. |
|
|
4770 | |
4403 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4771 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
|
|
4772 | |
|
|
4773 | =head3 General issues |
4404 | |
4774 | |
4405 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4775 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4406 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4776 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4407 | model. Libev still offers limited functionality on this platform in |
4777 | model. Libev still offers limited functionality on this platform in |
4408 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4778 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4409 | descriptors. This only applies when using Win32 natively, not when using |
4779 | descriptors. This only applies when using Win32 natively, not when using |
4410 | e.g. cygwin. |
4780 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
4781 | as every compielr comes with a slightly differently broken/incompatible |
|
|
4782 | environment. |
4411 | |
4783 | |
4412 | Lifting these limitations would basically require the full |
4784 | Lifting these limitations would basically require the full |
4413 | re-implementation of the I/O system. If you are into these kinds of |
4785 | re-implementation of the I/O system. If you are into this kind of thing, |
4414 | things, then note that glib does exactly that for you in a very portable |
4786 | then note that glib does exactly that for you in a very portable way (note |
4415 | way (note also that glib is the slowest event library known to man). |
4787 | also that glib is the slowest event library known to man). |
4416 | |
4788 | |
4417 | There is no supported compilation method available on windows except |
4789 | There is no supported compilation method available on windows except |
4418 | embedding it into other applications. |
4790 | embedding it into other applications. |
4419 | |
4791 | |
4420 | Sensible signal handling is officially unsupported by Microsoft - libev |
4792 | Sensible signal handling is officially unsupported by Microsoft - libev |
… | |
… | |
4448 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4820 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4449 | |
4821 | |
4450 | #include "evwrap.h" |
4822 | #include "evwrap.h" |
4451 | #include "ev.c" |
4823 | #include "ev.c" |
4452 | |
4824 | |
4453 | =over 4 |
|
|
4454 | |
|
|
4455 | =item The winsocket select function |
4825 | =head3 The winsocket C<select> function |
4456 | |
4826 | |
4457 | The winsocket C<select> function doesn't follow POSIX in that it |
4827 | The winsocket C<select> function doesn't follow POSIX in that it |
4458 | requires socket I<handles> and not socket I<file descriptors> (it is |
4828 | requires socket I<handles> and not socket I<file descriptors> (it is |
4459 | also extremely buggy). This makes select very inefficient, and also |
4829 | also extremely buggy). This makes select very inefficient, and also |
4460 | requires a mapping from file descriptors to socket handles (the Microsoft |
4830 | requires a mapping from file descriptors to socket handles (the Microsoft |
… | |
… | |
4469 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4839 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4470 | |
4840 | |
4471 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4841 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4472 | complexity in the O(n²) range when using win32. |
4842 | complexity in the O(n²) range when using win32. |
4473 | |
4843 | |
4474 | =item Limited number of file descriptors |
4844 | =head3 Limited number of file descriptors |
4475 | |
4845 | |
4476 | Windows has numerous arbitrary (and low) limits on things. |
4846 | Windows has numerous arbitrary (and low) limits on things. |
4477 | |
4847 | |
4478 | Early versions of winsocket's select only supported waiting for a maximum |
4848 | Early versions of winsocket's select only supported waiting for a maximum |
4479 | of C<64> handles (probably owning to the fact that all windows kernels |
4849 | of C<64> handles (probably owning to the fact that all windows kernels |
… | |
… | |
4494 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4864 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4495 | (depending on windows version and/or the phase of the moon). To get more, |
4865 | (depending on windows version and/or the phase of the moon). To get more, |
4496 | you need to wrap all I/O functions and provide your own fd management, but |
4866 | you need to wrap all I/O functions and provide your own fd management, but |
4497 | the cost of calling select (O(n²)) will likely make this unworkable. |
4867 | the cost of calling select (O(n²)) will likely make this unworkable. |
4498 | |
4868 | |
4499 | =back |
|
|
4500 | |
|
|
4501 | =head2 PORTABILITY REQUIREMENTS |
4869 | =head2 PORTABILITY REQUIREMENTS |
4502 | |
4870 | |
4503 | In addition to a working ISO-C implementation and of course the |
4871 | In addition to a working ISO-C implementation and of course the |
4504 | backend-specific APIs, libev relies on a few additional extensions: |
4872 | backend-specific APIs, libev relies on a few additional extensions: |
4505 | |
4873 | |
… | |
… | |
4511 | Libev assumes not only that all watcher pointers have the same internal |
4879 | Libev assumes not only that all watcher pointers have the same internal |
4512 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
4880 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
4513 | assumes that the same (machine) code can be used to call any watcher |
4881 | assumes that the same (machine) code can be used to call any watcher |
4514 | callback: The watcher callbacks have different type signatures, but libev |
4882 | callback: The watcher callbacks have different type signatures, but libev |
4515 | calls them using an C<ev_watcher *> internally. |
4883 | calls them using an C<ev_watcher *> internally. |
|
|
4884 | |
|
|
4885 | =item pointer accesses must be thread-atomic |
|
|
4886 | |
|
|
4887 | Accessing a pointer value must be atomic, it must both be readable and |
|
|
4888 | writable in one piece - this is the case on all current architectures. |
4516 | |
4889 | |
4517 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
4890 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
4518 | |
4891 | |
4519 | The type C<sig_atomic_t volatile> (or whatever is defined as |
4892 | The type C<sig_atomic_t volatile> (or whatever is defined as |
4520 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
4893 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
… | |
… | |
4543 | watchers. |
4916 | watchers. |
4544 | |
4917 | |
4545 | =item C<double> must hold a time value in seconds with enough accuracy |
4918 | =item C<double> must hold a time value in seconds with enough accuracy |
4546 | |
4919 | |
4547 | The type C<double> is used to represent timestamps. It is required to |
4920 | The type C<double> is used to represent timestamps. It is required to |
4548 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4921 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
4549 | enough for at least into the year 4000. This requirement is fulfilled by |
4922 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
4923 | (the design goal for libev). This requirement is overfulfilled by |
4550 | implementations implementing IEEE 754, which is basically all existing |
4924 | implementations using IEEE 754, which is basically all existing ones. With |
4551 | ones. With IEEE 754 doubles, you get microsecond accuracy until at least |
4925 | IEEE 754 doubles, you get microsecond accuracy until at least 2200. |
4552 | 2200. |
|
|
4553 | |
4926 | |
4554 | =back |
4927 | =back |
4555 | |
4928 | |
4556 | If you know of other additional requirements drop me a note. |
4929 | If you know of other additional requirements drop me a note. |
4557 | |
4930 | |
… | |
… | |
4627 | =back |
5000 | =back |
4628 | |
5001 | |
4629 | |
5002 | |
4630 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
5003 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
4631 | |
5004 | |
4632 | The major version 4 introduced some minor incompatible changes to the API. |
5005 | The major version 4 introduced some incompatible changes to the API. |
4633 | |
5006 | |
4634 | At the moment, the C<ev.h> header file tries to implement superficial |
5007 | At the moment, the C<ev.h> header file provides compatibility definitions |
4635 | compatibility, so most programs should still compile. Those might be |
5008 | for all changes, so most programs should still compile. The compatibility |
4636 | removed in later versions of libev, so better update early than late. |
5009 | layer might be removed in later versions of libev, so better update to the |
|
|
5010 | new API early than late. |
4637 | |
5011 | |
4638 | =over 4 |
5012 | =over 4 |
4639 | |
5013 | |
4640 | =item C<ev_loop_count> renamed to C<ev_iteration> |
5014 | =item C<EV_COMPAT3> backwards compatibility mechanism |
4641 | |
5015 | |
4642 | =item C<ev_loop_depth> renamed to C<ev_depth> |
5016 | The backward compatibility mechanism can be controlled by |
|
|
5017 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
5018 | section. |
4643 | |
5019 | |
4644 | =item C<ev_loop_verify> renamed to C<ev_verify> |
5020 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
|
|
5021 | |
|
|
5022 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
|
|
5023 | |
|
|
5024 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
5025 | ev_loop_fork (EV_DEFAULT); |
|
|
5026 | |
|
|
5027 | =item function/symbol renames |
|
|
5028 | |
|
|
5029 | A number of functions and symbols have been renamed: |
|
|
5030 | |
|
|
5031 | ev_loop => ev_run |
|
|
5032 | EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
5033 | EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
5034 | |
|
|
5035 | ev_unloop => ev_break |
|
|
5036 | EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
5037 | EVUNLOOP_ONE => EVBREAK_ONE |
|
|
5038 | EVUNLOOP_ALL => EVBREAK_ALL |
|
|
5039 | |
|
|
5040 | EV_TIMEOUT => EV_TIMER |
|
|
5041 | |
|
|
5042 | ev_loop_count => ev_iteration |
|
|
5043 | ev_loop_depth => ev_depth |
|
|
5044 | ev_loop_verify => ev_verify |
4645 | |
5045 | |
4646 | Most functions working on C<struct ev_loop> objects don't have an |
5046 | Most functions working on C<struct ev_loop> objects don't have an |
4647 | C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is |
5047 | C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and |
|
|
5048 | associated constants have been renamed to not collide with the C<struct |
|
|
5049 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
|
|
5050 | as all other watcher types. Note that C<ev_loop_fork> is still called |
4648 | still called C<ev_loop_fork> because it would otherwise clash with the |
5051 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
4649 | C<ev_fork> typedef. |
5052 | typedef. |
4650 | |
|
|
4651 | =item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents> |
|
|
4652 | |
|
|
4653 | This is a simple rename - all other watcher types use their name |
|
|
4654 | as revents flag, and now C<ev_timer> does, too. |
|
|
4655 | |
|
|
4656 | Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions |
|
|
4657 | and continue to be present for the forseeable future, so this is mostly a |
|
|
4658 | documentation change. |
|
|
4659 | |
5053 | |
4660 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
5054 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
4661 | |
5055 | |
4662 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
5056 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
4663 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
5057 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
… | |
… | |
4670 | |
5064 | |
4671 | =over 4 |
5065 | =over 4 |
4672 | |
5066 | |
4673 | =item active |
5067 | =item active |
4674 | |
5068 | |
4675 | A watcher is active as long as it has been started (has been attached to |
5069 | A watcher is active as long as it has been started and not yet stopped. |
4676 | an event loop) but not yet stopped (disassociated from the event loop). |
5070 | See L<WATCHER STATES> for details. |
4677 | |
5071 | |
4678 | =item application |
5072 | =item application |
4679 | |
5073 | |
4680 | In this document, an application is whatever is using libev. |
5074 | In this document, an application is whatever is using libev. |
|
|
5075 | |
|
|
5076 | =item backend |
|
|
5077 | |
|
|
5078 | The part of the code dealing with the operating system interfaces. |
4681 | |
5079 | |
4682 | =item callback |
5080 | =item callback |
4683 | |
5081 | |
4684 | The address of a function that is called when some event has been |
5082 | The address of a function that is called when some event has been |
4685 | detected. Callbacks are being passed the event loop, the watcher that |
5083 | detected. Callbacks are being passed the event loop, the watcher that |
4686 | received the event, and the actual event bitset. |
5084 | received the event, and the actual event bitset. |
4687 | |
5085 | |
4688 | =item callback invocation |
5086 | =item callback/watcher invocation |
4689 | |
5087 | |
4690 | The act of calling the callback associated with a watcher. |
5088 | The act of calling the callback associated with a watcher. |
4691 | |
5089 | |
4692 | =item event |
5090 | =item event |
4693 | |
5091 | |
… | |
… | |
4712 | The model used to describe how an event loop handles and processes |
5110 | The model used to describe how an event loop handles and processes |
4713 | watchers and events. |
5111 | watchers and events. |
4714 | |
5112 | |
4715 | =item pending |
5113 | =item pending |
4716 | |
5114 | |
4717 | A watcher is pending as soon as the corresponding event has been detected, |
5115 | A watcher is pending as soon as the corresponding event has been |
4718 | and stops being pending as soon as the watcher will be invoked or its |
5116 | detected. See L<WATCHER STATES> for details. |
4719 | pending status is explicitly cleared by the application. |
|
|
4720 | |
|
|
4721 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4722 | its pending status. |
|
|
4723 | |
5117 | |
4724 | =item real time |
5118 | =item real time |
4725 | |
5119 | |
4726 | The physical time that is observed. It is apparently strictly monotonic :) |
5120 | The physical time that is observed. It is apparently strictly monotonic :) |
4727 | |
5121 | |
… | |
… | |
4734 | =item watcher |
5128 | =item watcher |
4735 | |
5129 | |
4736 | A data structure that describes interest in certain events. Watchers need |
5130 | A data structure that describes interest in certain events. Watchers need |
4737 | to be started (attached to an event loop) before they can receive events. |
5131 | to be started (attached to an event loop) before they can receive events. |
4738 | |
5132 | |
4739 | =item watcher invocation |
|
|
4740 | |
|
|
4741 | The act of calling the callback associated with a watcher. |
|
|
4742 | |
|
|
4743 | =back |
5133 | =back |
4744 | |
5134 | |
4745 | =head1 AUTHOR |
5135 | =head1 AUTHOR |
4746 | |
5136 | |
4747 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
5137 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
|
|
5138 | Magnusson and Emanuele Giaquinta. |
4748 | |
5139 | |