… | |
… | |
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 | Its 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: |
… | |
… | |
345 | useful to try out specific backends to test their performance, or to work |
395 | useful to try out specific backends to test their performance, or to work |
346 | around bugs. |
396 | around bugs. |
347 | |
397 | |
348 | =item C<EVFLAG_FORKCHECK> |
398 | =item C<EVFLAG_FORKCHECK> |
349 | |
399 | |
350 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
400 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
351 | a fork, you can also make libev check for a fork in each iteration by |
401 | make libev check for a fork in each iteration by enabling this flag. |
352 | enabling this flag. |
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353 | |
402 | |
354 | This works by calling C<getpid ()> on every iteration of the loop, |
403 | This works by calling C<getpid ()> on every iteration of the loop, |
355 | and thus this might slow down your event loop if you do a lot of loop |
404 | and thus this might slow down your event loop if you do a lot of loop |
356 | iterations and little real work, but is usually not noticeable (on my |
405 | iterations and little real work, but is usually not noticeable (on my |
357 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
406 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
… | |
… | |
366 | environment variable. |
415 | environment variable. |
367 | |
416 | |
368 | =item C<EVFLAG_NOINOTIFY> |
417 | =item C<EVFLAG_NOINOTIFY> |
369 | |
418 | |
370 | 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 |
371 | 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 |
372 | 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 |
373 | 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. |
374 | |
423 | |
375 | =item C<EVFLAG_NOSIGFD> |
424 | =item C<EVFLAG_SIGNALFD> |
376 | |
425 | |
377 | When this flag is specified, then libev will not attempt to use the |
426 | When this flag is specified, then libev will attempt to use the |
378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This is |
427 | I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API |
379 | probably only useful to work around any bugs in libev. Consequently, this |
428 | delivers signals synchronously, which makes it both faster and might make |
380 | flag might go away once the signalfd functionality is considered stable, |
429 | it possible to get the queued signal data. It can also simplify signal |
381 | so it's useful mostly in environment variables and not in program code. |
430 | handling with threads, as long as you properly block signals in your |
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431 | threads that are not interested in handling them. |
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432 | |
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433 | Signalfd will not be used by default as this changes your signal mask, and |
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434 | there are a lot of shoddy libraries and programs (glib's threadpool for |
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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. |
382 | |
448 | |
383 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
449 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
384 | |
450 | |
385 | 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 |
386 | 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, |
… | |
… | |
422 | epoll scales either O(1) or O(active_fds). |
488 | epoll scales either O(1) or O(active_fds). |
423 | |
489 | |
424 | The epoll mechanism deserves honorable mention as the most misdesigned |
490 | The epoll mechanism deserves honorable mention as the most misdesigned |
425 | of the more advanced event mechanisms: mere annoyances include silently |
491 | of the more advanced event mechanisms: mere annoyances include silently |
426 | dropping file descriptors, requiring a system call per change per file |
492 | dropping file descriptors, requiring a system call per change per file |
427 | 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 |
428 | 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 |
429 | 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 |
430 | take considerable time (one syscall per file descriptor) and is of course |
498 | set, which can take considerable time (one syscall per file descriptor) |
431 | hard to detect. |
499 | and is of course hard to detect. |
432 | |
500 | |
433 | 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 |
434 | 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 |
435 | I<different> file descriptors (even already closed ones, so one cannot |
503 | I<different> file descriptors (even already closed ones, so one cannot |
436 | 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 |
437 | on SMP systems). Libev tries to counter these spurious notifications by |
505 | on SMP systems). Libev tries to counter these spurious notifications by |
438 | employing an additional generation counter and comparing that against the |
506 | employing an additional generation counter and comparing that against the |
439 | events to filter out spurious ones, recreating the set when required. |
507 | events to filter out spurious ones, recreating the set when required. Last |
|
|
508 | not least, it also refuses to work with some file descriptors which work |
|
|
509 | perfectly fine with C<select> (files, many character devices...). |
|
|
510 | |
|
|
511 | Epoll is truly the train wreck analog among event poll mechanisms, |
|
|
512 | a frankenpoll, cobbled together in a hurry, no thought to design or |
|
|
513 | interaction with others. |
440 | |
514 | |
441 | While stopping, setting and starting an I/O watcher in the same iteration |
515 | While stopping, setting and starting an I/O watcher in the same iteration |
442 | will result in some caching, there is still a system call per such |
516 | will result in some caching, there is still a system call per such |
443 | incident (because the same I<file descriptor> could point to a different |
517 | incident (because the same I<file descriptor> could point to a different |
444 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
518 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
… | |
… | |
510 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
584 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
511 | |
585 | |
512 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
586 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
513 | it's really slow, but it still scales very well (O(active_fds)). |
587 | it's really slow, but it still scales very well (O(active_fds)). |
514 | |
588 | |
515 | Please note that Solaris event ports can deliver a lot of spurious |
|
|
516 | notifications, so you need to use non-blocking I/O or other means to avoid |
|
|
517 | blocking when no data (or space) is available. |
|
|
518 | |
|
|
519 | While this backend scales well, it requires one system call per active |
589 | While this backend scales well, it requires one system call per active |
520 | file descriptor per loop iteration. For small and medium numbers of file |
590 | file descriptor per loop iteration. For small and medium numbers of file |
521 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
591 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
522 | might perform better. |
592 | might perform better. |
523 | |
593 | |
524 | On the positive side, with the exception of the spurious readiness |
594 | On the positive side, this backend actually performed fully to |
525 | notifications, this backend actually performed fully to specification |
|
|
526 | in all tests and is fully embeddable, which is a rare feat among the |
595 | specification in all tests and is fully embeddable, which is a rare feat |
527 | OS-specific backends (I vastly prefer correctness over speed hacks). |
596 | among the OS-specific backends (I vastly prefer correctness over speed |
|
|
597 | hacks). |
|
|
598 | |
|
|
599 | On the negative side, the interface is I<bizarre> - so bizarre that |
|
|
600 | even sun itself gets it wrong in their code examples: The event polling |
|
|
601 | function sometimes returning events to the caller even though an error |
|
|
602 | occurred, but with no indication whether it has done so or not (yes, it's |
|
|
603 | even documented that way) - deadly for edge-triggered interfaces where |
|
|
604 | you absolutely have to know whether an event occurred or not because you |
|
|
605 | have to re-arm the watcher. |
|
|
606 | |
|
|
607 | Fortunately libev seems to be able to work around these idiocies. |
528 | |
608 | |
529 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
609 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
530 | C<EVBACKEND_POLL>. |
610 | C<EVBACKEND_POLL>. |
531 | |
611 | |
532 | =item C<EVBACKEND_ALL> |
612 | =item C<EVBACKEND_ALL> |
533 | |
613 | |
534 | Try all backends (even potentially broken ones that wouldn't be tried |
614 | Try all backends (even potentially broken ones that wouldn't be tried |
535 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
615 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
536 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
616 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
537 | |
617 | |
538 | It is definitely not recommended to use this flag. |
618 | It is definitely not recommended to use this flag, use whatever |
|
|
619 | C<ev_recommended_backends ()> returns, or simply do not specify a backend |
|
|
620 | at all. |
|
|
621 | |
|
|
622 | =item C<EVBACKEND_MASK> |
|
|
623 | |
|
|
624 | Not a backend at all, but a mask to select all backend bits from a |
|
|
625 | C<flags> value, in case you want to mask out any backends from a flags |
|
|
626 | value (e.g. when modifying the C<LIBEV_FLAGS> environment variable). |
539 | |
627 | |
540 | =back |
628 | =back |
541 | |
629 | |
542 | If one or more of the backend flags are or'ed into the flags value, |
630 | If one or more of the backend flags are or'ed into the flags value, |
543 | then only these backends will be tried (in the reverse order as listed |
631 | then only these backends will be tried (in the reverse order as listed |
544 | here). If none are specified, all backends in C<ev_recommended_backends |
632 | here). If none are specified, all backends in C<ev_recommended_backends |
545 | ()> will be tried. |
633 | ()> will be tried. |
546 | |
634 | |
547 | Example: This is the most typical usage. |
|
|
548 | |
|
|
549 | if (!ev_default_loop (0)) |
|
|
550 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
551 | |
|
|
552 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
553 | environment settings to be taken into account: |
|
|
554 | |
|
|
555 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
556 | |
|
|
557 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
558 | used if available (warning, breaks stuff, best use only with your own |
|
|
559 | private event loop and only if you know the OS supports your types of |
|
|
560 | fds): |
|
|
561 | |
|
|
562 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
563 | |
|
|
564 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
|
|
565 | |
|
|
566 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
|
|
567 | always distinct from the default loop. Unlike the default loop, it cannot |
|
|
568 | handle signal and child watchers, and attempts to do so will be greeted by |
|
|
569 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
570 | |
|
|
571 | Note that this function I<is> thread-safe, and the recommended way to use |
|
|
572 | libev with threads is indeed to create one loop per thread, and using the |
|
|
573 | default loop in the "main" or "initial" thread. |
|
|
574 | |
|
|
575 | Example: Try to create a event loop that uses epoll and nothing else. |
635 | Example: Try to create a event loop that uses epoll and nothing else. |
576 | |
636 | |
577 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
637 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
578 | if (!epoller) |
638 | if (!epoller) |
579 | fatal ("no epoll found here, maybe it hides under your chair"); |
639 | fatal ("no epoll found here, maybe it hides under your chair"); |
580 | |
640 | |
|
|
641 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
642 | used if available. |
|
|
643 | |
|
|
644 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
645 | |
581 | =item ev_default_destroy () |
646 | =item ev_loop_destroy (loop) |
582 | |
647 | |
583 | Destroys the default loop again (frees all memory and kernel state |
648 | Destroys an event loop object (frees all memory and kernel state |
584 | etc.). None of the active event watchers will be stopped in the normal |
649 | etc.). None of the active event watchers will be stopped in the normal |
585 | sense, so e.g. C<ev_is_active> might still return true. It is your |
650 | sense, so e.g. C<ev_is_active> might still return true. It is your |
586 | responsibility to either stop all watchers cleanly yourself I<before> |
651 | responsibility to either stop all watchers cleanly yourself I<before> |
587 | calling this function, or cope with the fact afterwards (which is usually |
652 | calling this function, or cope with the fact afterwards (which is usually |
588 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
653 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
… | |
… | |
590 | |
655 | |
591 | Note that certain global state, such as signal state (and installed signal |
656 | Note that certain global state, such as signal state (and installed signal |
592 | handlers), will not be freed by this function, and related watchers (such |
657 | handlers), will not be freed by this function, and related watchers (such |
593 | as signal and child watchers) would need to be stopped manually. |
658 | as signal and child watchers) would need to be stopped manually. |
594 | |
659 | |
595 | In general it is not advisable to call this function except in the |
660 | This function is normally used on loop objects allocated by |
596 | rare occasion where you really need to free e.g. the signal handling |
661 | C<ev_loop_new>, but it can also be used on the default loop returned by |
|
|
662 | C<ev_default_loop>, in which case it is not thread-safe. |
|
|
663 | |
|
|
664 | Note that it is not advisable to call this function on the default loop |
|
|
665 | except in the rare occasion where you really need to free its resources. |
597 | pipe fds. If you need dynamically allocated loops it is better to use |
666 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
598 | C<ev_loop_new> and C<ev_loop_destroy>. |
667 | and C<ev_loop_destroy>. |
599 | |
668 | |
600 | =item ev_loop_destroy (loop) |
669 | =item ev_loop_fork (loop) |
601 | |
670 | |
602 | Like C<ev_default_destroy>, but destroys an event loop created by an |
|
|
603 | earlier call to C<ev_loop_new>. |
|
|
604 | |
|
|
605 | =item ev_default_fork () |
|
|
606 | |
|
|
607 | This function sets a flag that causes subsequent C<ev_loop> iterations |
671 | This function sets a flag that causes subsequent C<ev_run> iterations to |
608 | to reinitialise the kernel state for backends that have one. Despite the |
672 | reinitialise the kernel state for backends that have one. Despite the |
609 | name, you can call it anytime, but it makes most sense after forking, in |
673 | name, you can call it anytime, but it makes most sense after forking, in |
610 | the child process (or both child and parent, but that again makes little |
674 | the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the |
611 | sense). You I<must> call it in the child before using any of the libev |
675 | child before resuming or calling C<ev_run>. |
612 | functions, and it will only take effect at the next C<ev_loop> iteration. |
676 | |
|
|
677 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
|
|
678 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
|
|
679 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
|
|
680 | during fork. |
613 | |
681 | |
614 | On the other hand, you only need to call this function in the child |
682 | On the other hand, you only need to call this function in the child |
615 | process if and only if you want to use the event library in the child. If |
683 | process if and only if you want to use the event loop in the child. If |
616 | you just fork+exec, you don't have to call it at all. |
684 | you just fork+exec or create a new loop in the child, you don't have to |
|
|
685 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
|
|
686 | difference, but libev will usually detect this case on its own and do a |
|
|
687 | costly reset of the backend). |
617 | |
688 | |
618 | The function itself is quite fast and it's usually not a problem to call |
689 | The function itself is quite fast and it's usually not a problem to call |
619 | it just in case after a fork. To make this easy, the function will fit in |
690 | it just in case after a fork. |
620 | quite nicely into a call to C<pthread_atfork>: |
|
|
621 | |
691 | |
|
|
692 | Example: Automate calling C<ev_loop_fork> on the default loop when |
|
|
693 | using pthreads. |
|
|
694 | |
|
|
695 | static void |
|
|
696 | post_fork_child (void) |
|
|
697 | { |
|
|
698 | ev_loop_fork (EV_DEFAULT); |
|
|
699 | } |
|
|
700 | |
|
|
701 | ... |
622 | pthread_atfork (0, 0, ev_default_fork); |
702 | pthread_atfork (0, 0, post_fork_child); |
623 | |
|
|
624 | =item ev_loop_fork (loop) |
|
|
625 | |
|
|
626 | Like C<ev_default_fork>, but acts on an event loop created by |
|
|
627 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
|
|
628 | after fork that you want to re-use in the child, and how you do this is |
|
|
629 | entirely your own problem. |
|
|
630 | |
703 | |
631 | =item int ev_is_default_loop (loop) |
704 | =item int ev_is_default_loop (loop) |
632 | |
705 | |
633 | Returns true when the given loop is, in fact, the default loop, and false |
706 | Returns true when the given loop is, in fact, the default loop, and false |
634 | otherwise. |
707 | otherwise. |
635 | |
708 | |
636 | =item unsigned int ev_loop_count (loop) |
709 | =item unsigned int ev_iteration (loop) |
637 | |
710 | |
638 | Returns the count of loop iterations for the loop, which is identical to |
711 | Returns the current iteration count for the event loop, which is identical |
639 | the number of times libev did poll for new events. It starts at C<0> and |
712 | to the number of times libev did poll for new events. It starts at C<0> |
640 | happily wraps around with enough iterations. |
713 | and happily wraps around with enough iterations. |
641 | |
714 | |
642 | This value can sometimes be useful as a generation counter of sorts (it |
715 | This value can sometimes be useful as a generation counter of sorts (it |
643 | "ticks" the number of loop iterations), as it roughly corresponds with |
716 | "ticks" the number of loop iterations), as it roughly corresponds with |
644 | C<ev_prepare> and C<ev_check> calls. |
717 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
|
|
718 | prepare and check phases. |
645 | |
719 | |
646 | =item unsigned int ev_loop_depth (loop) |
720 | =item unsigned int ev_depth (loop) |
647 | |
721 | |
648 | Returns the number of times C<ev_loop> was entered minus the number of |
722 | Returns the number of times C<ev_run> was entered minus the number of |
649 | times C<ev_loop> was exited, in other words, the recursion depth. |
723 | times C<ev_run> was exited normally, in other words, the recursion depth. |
650 | |
724 | |
651 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
725 | Outside C<ev_run>, this number is zero. In a callback, this number is |
652 | C<1>, unless C<ev_loop> was invoked recursively (or from another thread), |
726 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
653 | in which case it is higher. |
727 | in which case it is higher. |
654 | |
728 | |
655 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
729 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread, |
656 | etc.), doesn't count as exit. |
730 | throwing an exception etc.), doesn't count as "exit" - consider this |
|
|
731 | as a hint to avoid such ungentleman-like behaviour unless it's really |
|
|
732 | convenient, in which case it is fully supported. |
657 | |
733 | |
658 | =item unsigned int ev_backend (loop) |
734 | =item unsigned int ev_backend (loop) |
659 | |
735 | |
660 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
736 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
661 | use. |
737 | use. |
… | |
… | |
670 | |
746 | |
671 | =item ev_now_update (loop) |
747 | =item ev_now_update (loop) |
672 | |
748 | |
673 | Establishes the current time by querying the kernel, updating the time |
749 | Establishes the current time by querying the kernel, updating the time |
674 | returned by C<ev_now ()> in the progress. This is a costly operation and |
750 | returned by C<ev_now ()> in the progress. This is a costly operation and |
675 | is usually done automatically within C<ev_loop ()>. |
751 | is usually done automatically within C<ev_run ()>. |
676 | |
752 | |
677 | This function is rarely useful, but when some event callback runs for a |
753 | This function is rarely useful, but when some event callback runs for a |
678 | very long time without entering the event loop, updating libev's idea of |
754 | very long time without entering the event loop, updating libev's idea of |
679 | the current time is a good idea. |
755 | the current time is a good idea. |
680 | |
756 | |
… | |
… | |
682 | |
758 | |
683 | =item ev_suspend (loop) |
759 | =item ev_suspend (loop) |
684 | |
760 | |
685 | =item ev_resume (loop) |
761 | =item ev_resume (loop) |
686 | |
762 | |
687 | These two functions suspend and resume a loop, for use when the loop is |
763 | These two functions suspend and resume an event loop, for use when the |
688 | not used for a while and timeouts should not be processed. |
764 | loop is not used for a while and timeouts should not be processed. |
689 | |
765 | |
690 | A typical use case would be an interactive program such as a game: When |
766 | A typical use case would be an interactive program such as a game: When |
691 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
767 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
692 | would be best to handle timeouts as if no time had actually passed while |
768 | would be best to handle timeouts as if no time had actually passed while |
693 | the program was suspended. This can be achieved by calling C<ev_suspend> |
769 | the program was suspended. This can be achieved by calling C<ev_suspend> |
… | |
… | |
695 | C<ev_resume> directly afterwards to resume timer processing. |
771 | C<ev_resume> directly afterwards to resume timer processing. |
696 | |
772 | |
697 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
773 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
698 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
774 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
699 | will be rescheduled (that is, they will lose any events that would have |
775 | will be rescheduled (that is, they will lose any events that would have |
700 | occured while suspended). |
776 | occurred while suspended). |
701 | |
777 | |
702 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
778 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
703 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
779 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
704 | without a previous call to C<ev_suspend>. |
780 | without a previous call to C<ev_suspend>. |
705 | |
781 | |
706 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
782 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
707 | event loop time (see C<ev_now_update>). |
783 | event loop time (see C<ev_now_update>). |
708 | |
784 | |
709 | =item ev_loop (loop, int flags) |
785 | =item ev_run (loop, int flags) |
710 | |
786 | |
711 | Finally, this is it, the event handler. This function usually is called |
787 | Finally, this is it, the event handler. This function usually is called |
712 | after you have initialised all your watchers and you want to start |
788 | after you have initialised all your watchers and you want to start |
713 | handling events. |
789 | handling events. It will ask the operating system for any new events, call |
|
|
790 | the watcher callbacks, an then repeat the whole process indefinitely: This |
|
|
791 | is why event loops are called I<loops>. |
714 | |
792 | |
715 | If the flags argument is specified as C<0>, it will not return until |
793 | If the flags argument is specified as C<0>, it will keep handling events |
716 | either no event watchers are active anymore or C<ev_unloop> was called. |
794 | until either no event watchers are active anymore or C<ev_break> was |
|
|
795 | called. |
717 | |
796 | |
718 | Please note that an explicit C<ev_unloop> is usually better than |
797 | Please note that an explicit C<ev_break> is usually better than |
719 | relying on all watchers to be stopped when deciding when a program has |
798 | relying on all watchers to be stopped when deciding when a program has |
720 | finished (especially in interactive programs), but having a program |
799 | finished (especially in interactive programs), but having a program |
721 | that automatically loops as long as it has to and no longer by virtue |
800 | that automatically loops as long as it has to and no longer by virtue |
722 | of relying on its watchers stopping correctly, that is truly a thing of |
801 | of relying on its watchers stopping correctly, that is truly a thing of |
723 | beauty. |
802 | beauty. |
724 | |
803 | |
|
|
804 | This function is also I<mostly> exception-safe - you can break out of |
|
|
805 | a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++ |
|
|
806 | exception and so on. This does not decrement the C<ev_depth> value, nor |
|
|
807 | will it clear any outstanding C<EVBREAK_ONE> breaks. |
|
|
808 | |
725 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
809 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
726 | those events and any already outstanding ones, but will not block your |
810 | those events and any already outstanding ones, but will not wait and |
727 | process in case there are no events and will return after one iteration of |
811 | block your process in case there are no events and will return after one |
728 | the loop. |
812 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
813 | events while doing lengthy calculations, to keep the program responsive. |
729 | |
814 | |
730 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
815 | A flags value of C<EVRUN_ONCE> will look for new events (waiting if |
731 | necessary) and will handle those and any already outstanding ones. It |
816 | necessary) and will handle those and any already outstanding ones. It |
732 | will block your process until at least one new event arrives (which could |
817 | will block your process until at least one new event arrives (which could |
733 | be an event internal to libev itself, so there is no guarantee that a |
818 | be an event internal to libev itself, so there is no guarantee that a |
734 | user-registered callback will be called), and will return after one |
819 | user-registered callback will be called), and will return after one |
735 | iteration of the loop. |
820 | iteration of the loop. |
736 | |
821 | |
737 | This is useful if you are waiting for some external event in conjunction |
822 | This is useful if you are waiting for some external event in conjunction |
738 | with something not expressible using other libev watchers (i.e. "roll your |
823 | with something not expressible using other libev watchers (i.e. "roll your |
739 | own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
824 | own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
740 | usually a better approach for this kind of thing. |
825 | usually a better approach for this kind of thing. |
741 | |
826 | |
742 | Here are the gory details of what C<ev_loop> does: |
827 | Here are the gory details of what C<ev_run> does: |
743 | |
828 | |
|
|
829 | - Increment loop depth. |
|
|
830 | - Reset the ev_break status. |
744 | - Before the first iteration, call any pending watchers. |
831 | - Before the first iteration, call any pending watchers. |
|
|
832 | LOOP: |
745 | * If EVFLAG_FORKCHECK was used, check for a fork. |
833 | - If EVFLAG_FORKCHECK was used, check for a fork. |
746 | - If a fork was detected (by any means), queue and call all fork watchers. |
834 | - If a fork was detected (by any means), queue and call all fork watchers. |
747 | - Queue and call all prepare watchers. |
835 | - Queue and call all prepare watchers. |
|
|
836 | - If ev_break was called, goto FINISH. |
748 | - If we have been forked, detach and recreate the kernel state |
837 | - If we have been forked, detach and recreate the kernel state |
749 | as to not disturb the other process. |
838 | as to not disturb the other process. |
750 | - Update the kernel state with all outstanding changes. |
839 | - Update the kernel state with all outstanding changes. |
751 | - Update the "event loop time" (ev_now ()). |
840 | - Update the "event loop time" (ev_now ()). |
752 | - Calculate for how long to sleep or block, if at all |
841 | - Calculate for how long to sleep or block, if at all |
753 | (active idle watchers, EVLOOP_NONBLOCK or not having |
842 | (active idle watchers, EVRUN_NOWAIT or not having |
754 | any active watchers at all will result in not sleeping). |
843 | any active watchers at all will result in not sleeping). |
755 | - Sleep if the I/O and timer collect interval say so. |
844 | - Sleep if the I/O and timer collect interval say so. |
|
|
845 | - Increment loop iteration counter. |
756 | - Block the process, waiting for any events. |
846 | - Block the process, waiting for any events. |
757 | - Queue all outstanding I/O (fd) events. |
847 | - Queue all outstanding I/O (fd) events. |
758 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
848 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
759 | - Queue all expired timers. |
849 | - Queue all expired timers. |
760 | - Queue all expired periodics. |
850 | - Queue all expired periodics. |
761 | - Unless any events are pending now, queue all idle watchers. |
851 | - Queue all idle watchers with priority higher than that of pending events. |
762 | - Queue all check watchers. |
852 | - Queue all check watchers. |
763 | - Call all queued watchers in reverse order (i.e. check watchers first). |
853 | - Call all queued watchers in reverse order (i.e. check watchers first). |
764 | Signals and child watchers are implemented as I/O watchers, and will |
854 | Signals and child watchers are implemented as I/O watchers, and will |
765 | be handled here by queueing them when their watcher gets executed. |
855 | be handled here by queueing them when their watcher gets executed. |
766 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
856 | - If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
767 | were used, or there are no active watchers, return, otherwise |
857 | were used, or there are no active watchers, goto FINISH, otherwise |
768 | continue with step *. |
858 | continue with step LOOP. |
|
|
859 | FINISH: |
|
|
860 | - Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
861 | - Decrement the loop depth. |
|
|
862 | - Return. |
769 | |
863 | |
770 | Example: Queue some jobs and then loop until no events are outstanding |
864 | Example: Queue some jobs and then loop until no events are outstanding |
771 | anymore. |
865 | anymore. |
772 | |
866 | |
773 | ... queue jobs here, make sure they register event watchers as long |
867 | ... queue jobs here, make sure they register event watchers as long |
774 | ... as they still have work to do (even an idle watcher will do..) |
868 | ... as they still have work to do (even an idle watcher will do..) |
775 | ev_loop (my_loop, 0); |
869 | ev_run (my_loop, 0); |
776 | ... jobs done or somebody called unloop. yeah! |
870 | ... jobs done or somebody called unloop. yeah! |
777 | |
871 | |
778 | =item ev_unloop (loop, how) |
872 | =item ev_break (loop, how) |
779 | |
873 | |
780 | Can be used to make a call to C<ev_loop> return early (but only after it |
874 | Can be used to make a call to C<ev_run> return early (but only after it |
781 | has processed all outstanding events). The C<how> argument must be either |
875 | has processed all outstanding events). The C<how> argument must be either |
782 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
876 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
783 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
877 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
784 | |
878 | |
785 | This "unloop state" will be cleared when entering C<ev_loop> again. |
879 | This "break state" will be cleared on the next call to C<ev_run>. |
786 | |
880 | |
787 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
881 | It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in |
|
|
882 | which case it will have no effect. |
788 | |
883 | |
789 | =item ev_ref (loop) |
884 | =item ev_ref (loop) |
790 | |
885 | |
791 | =item ev_unref (loop) |
886 | =item ev_unref (loop) |
792 | |
887 | |
793 | Ref/unref can be used to add or remove a reference count on the event |
888 | Ref/unref can be used to add or remove a reference count on the event |
794 | loop: Every watcher keeps one reference, and as long as the reference |
889 | loop: Every watcher keeps one reference, and as long as the reference |
795 | count is nonzero, C<ev_loop> will not return on its own. |
890 | count is nonzero, C<ev_run> will not return on its own. |
796 | |
891 | |
797 | If you have a watcher you never unregister that should not keep C<ev_loop> |
892 | This is useful when you have a watcher that you never intend to |
798 | from returning, call ev_unref() after starting, and ev_ref() before |
893 | unregister, but that nevertheless should not keep C<ev_run> from |
|
|
894 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
799 | stopping it. |
895 | before stopping it. |
800 | |
896 | |
801 | As an example, libev itself uses this for its internal signal pipe: It |
897 | As an example, libev itself uses this for its internal signal pipe: It |
802 | is not visible to the libev user and should not keep C<ev_loop> from |
898 | is not visible to the libev user and should not keep C<ev_run> from |
803 | exiting if no event watchers registered by it are active. It is also an |
899 | exiting if no event watchers registered by it are active. It is also an |
804 | excellent way to do this for generic recurring timers or from within |
900 | excellent way to do this for generic recurring timers or from within |
805 | third-party libraries. Just remember to I<unref after start> and I<ref |
901 | third-party libraries. Just remember to I<unref after start> and I<ref |
806 | before stop> (but only if the watcher wasn't active before, or was active |
902 | before stop> (but only if the watcher wasn't active before, or was active |
807 | before, respectively. Note also that libev might stop watchers itself |
903 | before, respectively. Note also that libev might stop watchers itself |
808 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
904 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
809 | in the callback). |
905 | in the callback). |
810 | |
906 | |
811 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
907 | Example: Create a signal watcher, but keep it from keeping C<ev_run> |
812 | running when nothing else is active. |
908 | running when nothing else is active. |
813 | |
909 | |
814 | ev_signal exitsig; |
910 | ev_signal exitsig; |
815 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
911 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
816 | ev_signal_start (loop, &exitsig); |
912 | ev_signal_start (loop, &exitsig); |
817 | evf_unref (loop); |
913 | ev_unref (loop); |
818 | |
914 | |
819 | Example: For some weird reason, unregister the above signal handler again. |
915 | Example: For some weird reason, unregister the above signal handler again. |
820 | |
916 | |
821 | ev_ref (loop); |
917 | ev_ref (loop); |
822 | ev_signal_stop (loop, &exitsig); |
918 | ev_signal_stop (loop, &exitsig); |
… | |
… | |
861 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
957 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
862 | as this approaches the timing granularity of most systems. Note that if |
958 | as this approaches the timing granularity of most systems. Note that if |
863 | you do transactions with the outside world and you can't increase the |
959 | you do transactions with the outside world and you can't increase the |
864 | parallelity, then this setting will limit your transaction rate (if you |
960 | parallelity, then this setting will limit your transaction rate (if you |
865 | need to poll once per transaction and the I/O collect interval is 0.01, |
961 | need to poll once per transaction and the I/O collect interval is 0.01, |
866 | then you can't do more than 100 transations per second). |
962 | then you can't do more than 100 transactions per second). |
867 | |
963 | |
868 | Setting the I<timeout collect interval> can improve the opportunity for |
964 | Setting the I<timeout collect interval> can improve the opportunity for |
869 | saving power, as the program will "bundle" timer callback invocations that |
965 | saving power, as the program will "bundle" timer callback invocations that |
870 | are "near" in time together, by delaying some, thus reducing the number of |
966 | are "near" in time together, by delaying some, thus reducing the number of |
871 | times the process sleeps and wakes up again. Another useful technique to |
967 | times the process sleeps and wakes up again. Another useful technique to |
… | |
… | |
879 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
975 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
880 | |
976 | |
881 | =item ev_invoke_pending (loop) |
977 | =item ev_invoke_pending (loop) |
882 | |
978 | |
883 | This call will simply invoke all pending watchers while resetting their |
979 | This call will simply invoke all pending watchers while resetting their |
884 | pending state. Normally, C<ev_loop> does this automatically when required, |
980 | pending state. Normally, C<ev_run> does this automatically when required, |
885 | but when overriding the invoke callback this call comes handy. |
981 | but when overriding the invoke callback this call comes handy. This |
|
|
982 | function can be invoked from a watcher - this can be useful for example |
|
|
983 | when you want to do some lengthy calculation and want to pass further |
|
|
984 | event handling to another thread (you still have to make sure only one |
|
|
985 | thread executes within C<ev_invoke_pending> or C<ev_run> of course). |
886 | |
986 | |
887 | =item int ev_pending_count (loop) |
987 | =item int ev_pending_count (loop) |
888 | |
988 | |
889 | Returns the number of pending watchers - zero indicates that no watchers |
989 | Returns the number of pending watchers - zero indicates that no watchers |
890 | are pending. |
990 | are pending. |
891 | |
991 | |
892 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
992 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
893 | |
993 | |
894 | This overrides the invoke pending functionality of the loop: Instead of |
994 | This overrides the invoke pending functionality of the loop: Instead of |
895 | invoking all pending watchers when there are any, C<ev_loop> will call |
995 | invoking all pending watchers when there are any, C<ev_run> will call |
896 | this callback instead. This is useful, for example, when you want to |
996 | this callback instead. This is useful, for example, when you want to |
897 | invoke the actual watchers inside another context (another thread etc.). |
997 | invoke the actual watchers inside another context (another thread etc.). |
898 | |
998 | |
899 | If you want to reset the callback, use C<ev_invoke_pending> as new |
999 | If you want to reset the callback, use C<ev_invoke_pending> as new |
900 | callback. |
1000 | callback. |
… | |
… | |
903 | |
1003 | |
904 | Sometimes you want to share the same loop between multiple threads. This |
1004 | Sometimes you want to share the same loop between multiple threads. This |
905 | can be done relatively simply by putting mutex_lock/unlock calls around |
1005 | can be done relatively simply by putting mutex_lock/unlock calls around |
906 | each call to a libev function. |
1006 | each call to a libev function. |
907 | |
1007 | |
908 | However, C<ev_loop> can run an indefinite time, so it is not feasible to |
1008 | However, C<ev_run> can run an indefinite time, so it is not feasible |
909 | wait for it to return. One way around this is to wake up the loop via |
1009 | to wait for it to return. One way around this is to wake up the event |
910 | C<ev_unloop> and C<av_async_send>, another way is to set these I<release> |
1010 | loop via C<ev_break> and C<av_async_send>, another way is to set these |
911 | and I<acquire> callbacks on the loop. |
1011 | I<release> and I<acquire> callbacks on the loop. |
912 | |
1012 | |
913 | When set, then C<release> will be called just before the thread is |
1013 | When set, then C<release> will be called just before the thread is |
914 | suspended waiting for new events, and C<acquire> is called just |
1014 | suspended waiting for new events, and C<acquire> is called just |
915 | afterwards. |
1015 | afterwards. |
916 | |
1016 | |
… | |
… | |
919 | |
1019 | |
920 | While event loop modifications are allowed between invocations of |
1020 | While event loop modifications are allowed between invocations of |
921 | C<release> and C<acquire> (that's their only purpose after all), no |
1021 | C<release> and C<acquire> (that's their only purpose after all), no |
922 | modifications done will affect the event loop, i.e. adding watchers will |
1022 | modifications done will affect the event loop, i.e. adding watchers will |
923 | have no effect on the set of file descriptors being watched, or the time |
1023 | have no effect on the set of file descriptors being watched, or the time |
924 | waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it |
1024 | waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it |
925 | to take note of any changes you made. |
1025 | to take note of any changes you made. |
926 | |
1026 | |
927 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
1027 | In theory, threads executing C<ev_run> will be async-cancel safe between |
928 | invocations of C<release> and C<acquire>. |
1028 | invocations of C<release> and C<acquire>. |
929 | |
1029 | |
930 | See also the locking example in the C<THREADS> section later in this |
1030 | See also the locking example in the C<THREADS> section later in this |
931 | document. |
1031 | document. |
932 | |
1032 | |
933 | =item ev_set_userdata (loop, void *data) |
1033 | =item ev_set_userdata (loop, void *data) |
934 | |
1034 | |
935 | =item ev_userdata (loop) |
1035 | =item void *ev_userdata (loop) |
936 | |
1036 | |
937 | Set and retrieve a single C<void *> associated with a loop. When |
1037 | Set and retrieve a single C<void *> associated with a loop. When |
938 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
1038 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
939 | C<0.> |
1039 | C<0>. |
940 | |
1040 | |
941 | These two functions can be used to associate arbitrary data with a loop, |
1041 | These two functions can be used to associate arbitrary data with a loop, |
942 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
1042 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
943 | C<acquire> callbacks described above, but of course can be (ab-)used for |
1043 | C<acquire> callbacks described above, but of course can be (ab-)used for |
944 | any other purpose as well. |
1044 | any other purpose as well. |
945 | |
1045 | |
946 | =item ev_loop_verify (loop) |
1046 | =item ev_verify (loop) |
947 | |
1047 | |
948 | This function only does something when C<EV_VERIFY> support has been |
1048 | This function only does something when C<EV_VERIFY> support has been |
949 | compiled in, which is the default for non-minimal builds. It tries to go |
1049 | compiled in, which is the default for non-minimal builds. It tries to go |
950 | through all internal structures and checks them for validity. If anything |
1050 | through all internal structures and checks them for validity. If anything |
951 | is found to be inconsistent, it will print an error message to standard |
1051 | is found to be inconsistent, it will print an error message to standard |
… | |
… | |
962 | |
1062 | |
963 | In the following description, uppercase C<TYPE> in names stands for the |
1063 | In the following description, uppercase C<TYPE> in names stands for the |
964 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
1064 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
965 | watchers and C<ev_io_start> for I/O watchers. |
1065 | watchers and C<ev_io_start> for I/O watchers. |
966 | |
1066 | |
967 | A watcher is a structure that you create and register to record your |
1067 | A watcher is an opaque structure that you allocate and register to record |
968 | interest in some event. For instance, if you want to wait for STDIN to |
1068 | your interest in some event. To make a concrete example, imagine you want |
969 | become readable, you would create an C<ev_io> watcher for that: |
1069 | to wait for STDIN to become readable, you would create an C<ev_io> watcher |
|
|
1070 | for that: |
970 | |
1071 | |
971 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
1072 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
972 | { |
1073 | { |
973 | ev_io_stop (w); |
1074 | ev_io_stop (w); |
974 | ev_unloop (loop, EVUNLOOP_ALL); |
1075 | ev_break (loop, EVBREAK_ALL); |
975 | } |
1076 | } |
976 | |
1077 | |
977 | struct ev_loop *loop = ev_default_loop (0); |
1078 | struct ev_loop *loop = ev_default_loop (0); |
978 | |
1079 | |
979 | ev_io stdin_watcher; |
1080 | ev_io stdin_watcher; |
980 | |
1081 | |
981 | ev_init (&stdin_watcher, my_cb); |
1082 | ev_init (&stdin_watcher, my_cb); |
982 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1083 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
983 | ev_io_start (loop, &stdin_watcher); |
1084 | ev_io_start (loop, &stdin_watcher); |
984 | |
1085 | |
985 | ev_loop (loop, 0); |
1086 | ev_run (loop, 0); |
986 | |
1087 | |
987 | As you can see, you are responsible for allocating the memory for your |
1088 | As you can see, you are responsible for allocating the memory for your |
988 | watcher structures (and it is I<usually> a bad idea to do this on the |
1089 | watcher structures (and it is I<usually> a bad idea to do this on the |
989 | stack). |
1090 | stack). |
990 | |
1091 | |
991 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
1092 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
992 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
1093 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
993 | |
1094 | |
994 | Each watcher structure must be initialised by a call to C<ev_init |
1095 | Each watcher structure must be initialised by a call to C<ev_init (watcher |
995 | (watcher *, callback)>, which expects a callback to be provided. This |
1096 | *, callback)>, which expects a callback to be provided. This callback is |
996 | callback gets invoked each time the event occurs (or, in the case of I/O |
1097 | invoked each time the event occurs (or, in the case of I/O watchers, each |
997 | watchers, each time the event loop detects that the file descriptor given |
1098 | time the event loop detects that the file descriptor given is readable |
998 | is readable and/or writable). |
1099 | and/or writable). |
999 | |
1100 | |
1000 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
1101 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
1001 | macro to configure it, with arguments specific to the watcher type. There |
1102 | macro to configure it, with arguments specific to the watcher type. There |
1002 | is also a macro to combine initialisation and setting in one call: C<< |
1103 | is also a macro to combine initialisation and setting in one call: C<< |
1003 | ev_TYPE_init (watcher *, callback, ...) >>. |
1104 | ev_TYPE_init (watcher *, callback, ...) >>. |
… | |
… | |
1026 | =item C<EV_WRITE> |
1127 | =item C<EV_WRITE> |
1027 | |
1128 | |
1028 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1129 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1029 | writable. |
1130 | writable. |
1030 | |
1131 | |
1031 | =item C<EV_TIMEOUT> |
1132 | =item C<EV_TIMER> |
1032 | |
1133 | |
1033 | The C<ev_timer> watcher has timed out. |
1134 | The C<ev_timer> watcher has timed out. |
1034 | |
1135 | |
1035 | =item C<EV_PERIODIC> |
1136 | =item C<EV_PERIODIC> |
1036 | |
1137 | |
… | |
… | |
1054 | |
1155 | |
1055 | =item C<EV_PREPARE> |
1156 | =item C<EV_PREPARE> |
1056 | |
1157 | |
1057 | =item C<EV_CHECK> |
1158 | =item C<EV_CHECK> |
1058 | |
1159 | |
1059 | All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts |
1160 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
1060 | to gather new events, and all C<ev_check> watchers are invoked just after |
1161 | to gather new events, and all C<ev_check> watchers are invoked just after |
1061 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
1162 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
1062 | received events. Callbacks of both watcher types can start and stop as |
1163 | received events. Callbacks of both watcher types can start and stop as |
1063 | many watchers as they want, and all of them will be taken into account |
1164 | many watchers as they want, and all of them will be taken into account |
1064 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1165 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1065 | C<ev_loop> from blocking). |
1166 | C<ev_run> from blocking). |
1066 | |
1167 | |
1067 | =item C<EV_EMBED> |
1168 | =item C<EV_EMBED> |
1068 | |
1169 | |
1069 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1170 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1070 | |
1171 | |
1071 | =item C<EV_FORK> |
1172 | =item C<EV_FORK> |
1072 | |
1173 | |
1073 | The event loop has been resumed in the child process after fork (see |
1174 | The event loop has been resumed in the child process after fork (see |
1074 | C<ev_fork>). |
1175 | C<ev_fork>). |
|
|
1176 | |
|
|
1177 | =item C<EV_CLEANUP> |
|
|
1178 | |
|
|
1179 | The event loop is about to be destroyed (see C<ev_cleanup>). |
1075 | |
1180 | |
1076 | =item C<EV_ASYNC> |
1181 | =item C<EV_ASYNC> |
1077 | |
1182 | |
1078 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1183 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1079 | |
1184 | |
… | |
… | |
1251 | |
1356 | |
1252 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1357 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1253 | functions that do not need a watcher. |
1358 | functions that do not need a watcher. |
1254 | |
1359 | |
1255 | =back |
1360 | =back |
1256 | |
|
|
1257 | |
1361 | |
1258 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1362 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1259 | |
1363 | |
1260 | Each watcher has, by default, a member C<void *data> that you can change |
1364 | Each watcher has, by default, a member C<void *data> that you can change |
1261 | and read at any time: libev will completely ignore it. This can be used |
1365 | and read at any time: libev will completely ignore it. This can be used |
… | |
… | |
1317 | t2_cb (EV_P_ ev_timer *w, int revents) |
1421 | t2_cb (EV_P_ ev_timer *w, int revents) |
1318 | { |
1422 | { |
1319 | struct my_biggy big = (struct my_biggy *) |
1423 | struct my_biggy big = (struct my_biggy *) |
1320 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1424 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1321 | } |
1425 | } |
|
|
1426 | |
|
|
1427 | =head2 WATCHER STATES |
|
|
1428 | |
|
|
1429 | There are various watcher states mentioned throughout this manual - |
|
|
1430 | active, pending and so on. In this section these states and the rules to |
|
|
1431 | transition between them will be described in more detail - and while these |
|
|
1432 | rules might look complicated, they usually do "the right thing". |
|
|
1433 | |
|
|
1434 | =over 4 |
|
|
1435 | |
|
|
1436 | =item initialiased |
|
|
1437 | |
|
|
1438 | Before a watcher can be registered with the event looop it has to be |
|
|
1439 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1440 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
|
|
1441 | |
|
|
1442 | In this state it is simply some block of memory that is suitable for use |
|
|
1443 | in an event loop. It can be moved around, freed, reused etc. at will. |
|
|
1444 | |
|
|
1445 | =item started/running/active |
|
|
1446 | |
|
|
1447 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
|
|
1448 | property of the event loop, and is actively waiting for events. While in |
|
|
1449 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1450 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1451 | and call libev functions on it that are documented to work on active watchers. |
|
|
1452 | |
|
|
1453 | =item pending |
|
|
1454 | |
|
|
1455 | If a watcher is active and libev determines that an event it is interested |
|
|
1456 | in has occurred (such as a timer expiring), it will become pending. It will |
|
|
1457 | stay in this pending state until either it is stopped or its callback is |
|
|
1458 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1459 | callback. |
|
|
1460 | |
|
|
1461 | The watcher might or might not be active while it is pending (for example, |
|
|
1462 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1463 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1464 | but it is still property of the event loop at this time, so cannot be |
|
|
1465 | moved, freed or reused. And if it is active the rules described in the |
|
|
1466 | previous item still apply. |
|
|
1467 | |
|
|
1468 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1469 | via C<ev_feed_event>), in which case it becomes pending without being |
|
|
1470 | active. |
|
|
1471 | |
|
|
1472 | =item stopped |
|
|
1473 | |
|
|
1474 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1475 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
|
|
1476 | latter will clear any pending state the watcher might be in, regardless |
|
|
1477 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1478 | freeing it is often a good idea. |
|
|
1479 | |
|
|
1480 | While stopped (and not pending) the watcher is essentially in the |
|
|
1481 | initialised state, that is it can be reused, moved, modified in any way |
|
|
1482 | you wish. |
|
|
1483 | |
|
|
1484 | =back |
1322 | |
1485 | |
1323 | =head2 WATCHER PRIORITY MODELS |
1486 | =head2 WATCHER PRIORITY MODELS |
1324 | |
1487 | |
1325 | Many event loops support I<watcher priorities>, which are usually small |
1488 | Many event loops support I<watcher priorities>, which are usually small |
1326 | integers that influence the ordering of event callback invocation |
1489 | integers that influence the ordering of event callback invocation |
… | |
… | |
1369 | |
1532 | |
1370 | For example, to emulate how many other event libraries handle priorities, |
1533 | For example, to emulate how many other event libraries handle priorities, |
1371 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1534 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1372 | the normal watcher callback, you just start the idle watcher. The real |
1535 | the normal watcher callback, you just start the idle watcher. The real |
1373 | processing is done in the idle watcher callback. This causes libev to |
1536 | processing is done in the idle watcher callback. This causes libev to |
1374 | continously poll and process kernel event data for the watcher, but when |
1537 | continuously poll and process kernel event data for the watcher, but when |
1375 | the lock-out case is known to be rare (which in turn is rare :), this is |
1538 | the lock-out case is known to be rare (which in turn is rare :), this is |
1376 | workable. |
1539 | workable. |
1377 | |
1540 | |
1378 | Usually, however, the lock-out model implemented that way will perform |
1541 | Usually, however, the lock-out model implemented that way will perform |
1379 | miserably under the type of load it was designed to handle. In that case, |
1542 | miserably under the type of load it was designed to handle. In that case, |
… | |
… | |
1393 | { |
1556 | { |
1394 | // stop the I/O watcher, we received the event, but |
1557 | // stop the I/O watcher, we received the event, but |
1395 | // are not yet ready to handle it. |
1558 | // are not yet ready to handle it. |
1396 | ev_io_stop (EV_A_ w); |
1559 | ev_io_stop (EV_A_ w); |
1397 | |
1560 | |
1398 | // start the idle watcher to ahndle the actual event. |
1561 | // start the idle watcher to handle the actual event. |
1399 | // it will not be executed as long as other watchers |
1562 | // it will not be executed as long as other watchers |
1400 | // with the default priority are receiving events. |
1563 | // with the default priority are receiving events. |
1401 | ev_idle_start (EV_A_ &idle); |
1564 | ev_idle_start (EV_A_ &idle); |
1402 | } |
1565 | } |
1403 | |
1566 | |
… | |
… | |
1453 | In general you can register as many read and/or write event watchers per |
1616 | In general you can register as many read and/or write event watchers per |
1454 | fd as you want (as long as you don't confuse yourself). Setting all file |
1617 | fd as you want (as long as you don't confuse yourself). Setting all file |
1455 | descriptors to non-blocking mode is also usually a good idea (but not |
1618 | descriptors to non-blocking mode is also usually a good idea (but not |
1456 | required if you know what you are doing). |
1619 | required if you know what you are doing). |
1457 | |
1620 | |
1458 | If you cannot use non-blocking mode, then force the use of a |
|
|
1459 | known-to-be-good backend (at the time of this writing, this includes only |
|
|
1460 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
|
|
1461 | descriptors for which non-blocking operation makes no sense (such as |
|
|
1462 | files) - libev doesn't guarentee any specific behaviour in that case. |
|
|
1463 | |
|
|
1464 | Another thing you have to watch out for is that it is quite easy to |
1621 | Another thing you have to watch out for is that it is quite easy to |
1465 | receive "spurious" readiness notifications, that is your callback might |
1622 | receive "spurious" readiness notifications, that is, your callback might |
1466 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1623 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1467 | because there is no data. Not only are some backends known to create a |
1624 | because there is no data. It is very easy to get into this situation even |
1468 | lot of those (for example Solaris ports), it is very easy to get into |
1625 | with a relatively standard program structure. Thus it is best to always |
1469 | this situation even with a relatively standard program structure. Thus |
1626 | use non-blocking I/O: An extra C<read>(2) returning C<EAGAIN> is far |
1470 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
|
|
1471 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
1627 | preferable to a program hanging until some data arrives. |
1472 | |
1628 | |
1473 | If you cannot run the fd in non-blocking mode (for example you should |
1629 | If you cannot run the fd in non-blocking mode (for example you should |
1474 | not play around with an Xlib connection), then you have to separately |
1630 | not play around with an Xlib connection), then you have to separately |
1475 | re-test whether a file descriptor is really ready with a known-to-be good |
1631 | re-test whether a file descriptor is really ready with a known-to-be good |
1476 | interface such as poll (fortunately in our Xlib example, Xlib already |
1632 | interface such as poll (fortunately in the case of Xlib, it already does |
1477 | does this on its own, so its quite safe to use). Some people additionally |
1633 | this on its own, so its quite safe to use). Some people additionally |
1478 | use C<SIGALRM> and an interval timer, just to be sure you won't block |
1634 | use C<SIGALRM> and an interval timer, just to be sure you won't block |
1479 | indefinitely. |
1635 | indefinitely. |
1480 | |
1636 | |
1481 | But really, best use non-blocking mode. |
1637 | But really, best use non-blocking mode. |
1482 | |
1638 | |
… | |
… | |
1510 | |
1666 | |
1511 | There is no workaround possible except not registering events |
1667 | There is no workaround possible except not registering events |
1512 | for potentially C<dup ()>'ed file descriptors, or to resort to |
1668 | for potentially C<dup ()>'ed file descriptors, or to resort to |
1513 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1669 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1514 | |
1670 | |
|
|
1671 | =head3 The special problem of files |
|
|
1672 | |
|
|
1673 | Many people try to use C<select> (or libev) on file descriptors |
|
|
1674 | representing files, and expect it to become ready when their program |
|
|
1675 | doesn't block on disk accesses (which can take a long time on their own). |
|
|
1676 | |
|
|
1677 | However, this cannot ever work in the "expected" way - you get a readiness |
|
|
1678 | notification as soon as the kernel knows whether and how much data is |
|
|
1679 | there, and in the case of open files, that's always the case, so you |
|
|
1680 | always get a readiness notification instantly, and your read (or possibly |
|
|
1681 | write) will still block on the disk I/O. |
|
|
1682 | |
|
|
1683 | Another way to view it is that in the case of sockets, pipes, character |
|
|
1684 | devices and so on, there is another party (the sender) that delivers data |
|
|
1685 | on it's own, but in the case of files, there is no such thing: the disk |
|
|
1686 | will not send data on it's own, simply because it doesn't know what you |
|
|
1687 | wish to read - you would first have to request some data. |
|
|
1688 | |
|
|
1689 | Since files are typically not-so-well supported by advanced notification |
|
|
1690 | mechanism, libev tries hard to emulate POSIX behaviour with respect |
|
|
1691 | to files, even though you should not use it. The reason for this is |
|
|
1692 | convenience: sometimes you want to watch STDIN or STDOUT, which is |
|
|
1693 | usually a tty, often a pipe, but also sometimes files or special devices |
|
|
1694 | (for example, C<epoll> on Linux works with F</dev/random> but not with |
|
|
1695 | F</dev/urandom>), and even though the file might better be served with |
|
|
1696 | asynchronous I/O instead of with non-blocking I/O, it is still useful when |
|
|
1697 | it "just works" instead of freezing. |
|
|
1698 | |
|
|
1699 | So avoid file descriptors pointing to files when you know it (e.g. use |
|
|
1700 | libeio), but use them when it is convenient, e.g. for STDIN/STDOUT, or |
|
|
1701 | when you rarely read from a file instead of from a socket, and want to |
|
|
1702 | reuse the same code path. |
|
|
1703 | |
1515 | =head3 The special problem of fork |
1704 | =head3 The special problem of fork |
1516 | |
1705 | |
1517 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
1706 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
1518 | useless behaviour. Libev fully supports fork, but needs to be told about |
1707 | useless behaviour. Libev fully supports fork, but needs to be told about |
1519 | it in the child. |
1708 | it in the child if you want to continue to use it in the child. |
1520 | |
1709 | |
1521 | To support fork in your programs, you either have to call |
1710 | To support fork in your child processes, you have to call C<ev_loop_fork |
1522 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
1711 | ()> after a fork in the child, enable C<EVFLAG_FORKCHECK>, or resort to |
1523 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
1712 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1524 | C<EVBACKEND_POLL>. |
|
|
1525 | |
1713 | |
1526 | =head3 The special problem of SIGPIPE |
1714 | =head3 The special problem of SIGPIPE |
1527 | |
1715 | |
1528 | While not really specific to libev, it is easy to forget about C<SIGPIPE>: |
1716 | While not really specific to libev, it is easy to forget about C<SIGPIPE>: |
1529 | when writing to a pipe whose other end has been closed, your program gets |
1717 | when writing to a pipe whose other end has been closed, your program gets |
… | |
… | |
1532 | |
1720 | |
1533 | So when you encounter spurious, unexplained daemon exits, make sure you |
1721 | So when you encounter spurious, unexplained daemon exits, make sure you |
1534 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1722 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1535 | somewhere, as that would have given you a big clue). |
1723 | somewhere, as that would have given you a big clue). |
1536 | |
1724 | |
|
|
1725 | =head3 The special problem of accept()ing when you can't |
|
|
1726 | |
|
|
1727 | Many implementations of the POSIX C<accept> function (for example, |
|
|
1728 | found in post-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1729 | connection from the pending queue in all error cases. |
|
|
1730 | |
|
|
1731 | For example, larger servers often run out of file descriptors (because |
|
|
1732 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
|
|
1733 | rejecting the connection, leading to libev signalling readiness on |
|
|
1734 | the next iteration again (the connection still exists after all), and |
|
|
1735 | typically causing the program to loop at 100% CPU usage. |
|
|
1736 | |
|
|
1737 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1738 | operating systems, there is usually little the app can do to remedy the |
|
|
1739 | situation, and no known thread-safe method of removing the connection to |
|
|
1740 | cope with overload is known (to me). |
|
|
1741 | |
|
|
1742 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1743 | - when the program encounters an overload, it will just loop until the |
|
|
1744 | situation is over. While this is a form of busy waiting, no OS offers an |
|
|
1745 | event-based way to handle this situation, so it's the best one can do. |
|
|
1746 | |
|
|
1747 | A better way to handle the situation is to log any errors other than |
|
|
1748 | C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such |
|
|
1749 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1750 | what could be wrong ("raise the ulimit!"). For extra points one could stop |
|
|
1751 | the C<ev_io> watcher on the listening fd "for a while", which reduces CPU |
|
|
1752 | usage. |
|
|
1753 | |
|
|
1754 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1755 | descriptor for overload situations (e.g. by opening F</dev/null>), and |
|
|
1756 | when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>, |
|
|
1757 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1758 | clients under typical overload conditions. |
|
|
1759 | |
|
|
1760 | The last way to handle it is to simply log the error and C<exit>, as |
|
|
1761 | is often done with C<malloc> failures, but this results in an easy |
|
|
1762 | opportunity for a DoS attack. |
1537 | |
1763 | |
1538 | =head3 Watcher-Specific Functions |
1764 | =head3 Watcher-Specific Functions |
1539 | |
1765 | |
1540 | =over 4 |
1766 | =over 4 |
1541 | |
1767 | |
… | |
… | |
1573 | ... |
1799 | ... |
1574 | struct ev_loop *loop = ev_default_init (0); |
1800 | struct ev_loop *loop = ev_default_init (0); |
1575 | ev_io stdin_readable; |
1801 | ev_io stdin_readable; |
1576 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1802 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1577 | ev_io_start (loop, &stdin_readable); |
1803 | ev_io_start (loop, &stdin_readable); |
1578 | ev_loop (loop, 0); |
1804 | ev_run (loop, 0); |
1579 | |
1805 | |
1580 | |
1806 | |
1581 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1807 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1582 | |
1808 | |
1583 | Timer watchers are simple relative timers that generate an event after a |
1809 | Timer watchers are simple relative timers that generate an event after a |
… | |
… | |
1592 | The callback is guaranteed to be invoked only I<after> its timeout has |
1818 | The callback is guaranteed to be invoked only I<after> its timeout has |
1593 | passed (not I<at>, so on systems with very low-resolution clocks this |
1819 | passed (not I<at>, so on systems with very low-resolution clocks this |
1594 | might introduce a small delay). If multiple timers become ready during the |
1820 | might introduce a small delay). If multiple timers become ready during the |
1595 | same loop iteration then the ones with earlier time-out values are invoked |
1821 | same loop iteration then the ones with earlier time-out values are invoked |
1596 | before ones of the same priority with later time-out values (but this is |
1822 | before ones of the same priority with later time-out values (but this is |
1597 | no longer true when a callback calls C<ev_loop> recursively). |
1823 | no longer true when a callback calls C<ev_run> recursively). |
1598 | |
1824 | |
1599 | =head3 Be smart about timeouts |
1825 | =head3 Be smart about timeouts |
1600 | |
1826 | |
1601 | Many real-world problems involve some kind of timeout, usually for error |
1827 | Many real-world problems involve some kind of timeout, usually for error |
1602 | recovery. A typical example is an HTTP request - if the other side hangs, |
1828 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
1688 | ev_tstamp timeout = last_activity + 60.; |
1914 | ev_tstamp timeout = last_activity + 60.; |
1689 | |
1915 | |
1690 | // if last_activity + 60. is older than now, we did time out |
1916 | // if last_activity + 60. is older than now, we did time out |
1691 | if (timeout < now) |
1917 | if (timeout < now) |
1692 | { |
1918 | { |
1693 | // timeout occured, take action |
1919 | // timeout occurred, take action |
1694 | } |
1920 | } |
1695 | else |
1921 | else |
1696 | { |
1922 | { |
1697 | // callback was invoked, but there was some activity, re-arm |
1923 | // callback was invoked, but there was some activity, re-arm |
1698 | // the watcher to fire in last_activity + 60, which is |
1924 | // the watcher to fire in last_activity + 60, which is |
… | |
… | |
1720 | to the current time (meaning we just have some activity :), then call the |
1946 | to the current time (meaning we just have some activity :), then call the |
1721 | callback, which will "do the right thing" and start the timer: |
1947 | callback, which will "do the right thing" and start the timer: |
1722 | |
1948 | |
1723 | ev_init (timer, callback); |
1949 | ev_init (timer, callback); |
1724 | last_activity = ev_now (loop); |
1950 | last_activity = ev_now (loop); |
1725 | callback (loop, timer, EV_TIMEOUT); |
1951 | callback (loop, timer, EV_TIMER); |
1726 | |
1952 | |
1727 | And when there is some activity, simply store the current time in |
1953 | And when there is some activity, simply store the current time in |
1728 | C<last_activity>, no libev calls at all: |
1954 | C<last_activity>, no libev calls at all: |
1729 | |
1955 | |
1730 | last_actiivty = ev_now (loop); |
1956 | last_activity = ev_now (loop); |
1731 | |
1957 | |
1732 | This technique is slightly more complex, but in most cases where the |
1958 | This technique is slightly more complex, but in most cases where the |
1733 | time-out is unlikely to be triggered, much more efficient. |
1959 | time-out is unlikely to be triggered, much more efficient. |
1734 | |
1960 | |
1735 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
1961 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
… | |
… | |
1773 | |
1999 | |
1774 | =head3 The special problem of time updates |
2000 | =head3 The special problem of time updates |
1775 | |
2001 | |
1776 | Establishing the current time is a costly operation (it usually takes at |
2002 | Establishing the current time is a costly operation (it usually takes at |
1777 | least two system calls): EV therefore updates its idea of the current |
2003 | least two system calls): EV therefore updates its idea of the current |
1778 | time only before and after C<ev_loop> collects new events, which causes a |
2004 | time only before and after C<ev_run> collects new events, which causes a |
1779 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
2005 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1780 | lots of events in one iteration. |
2006 | lots of events in one iteration. |
1781 | |
2007 | |
1782 | The relative timeouts are calculated relative to the C<ev_now ()> |
2008 | The relative timeouts are calculated relative to the C<ev_now ()> |
1783 | time. This is usually the right thing as this timestamp refers to the time |
2009 | time. This is usually the right thing as this timestamp refers to the time |
… | |
… | |
1861 | Returns the remaining time until a timer fires. If the timer is active, |
2087 | Returns the remaining time until a timer fires. If the timer is active, |
1862 | then this time is relative to the current event loop time, otherwise it's |
2088 | then this time is relative to the current event loop time, otherwise it's |
1863 | the timeout value currently configured. |
2089 | the timeout value currently configured. |
1864 | |
2090 | |
1865 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
2091 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
1866 | C<5>. When the timer is started and one second passes, C<ev_timer_remain> |
2092 | C<5>. When the timer is started and one second passes, C<ev_timer_remaining> |
1867 | will return C<4>. When the timer expires and is restarted, it will return |
2093 | will return C<4>. When the timer expires and is restarted, it will return |
1868 | roughly C<7> (likely slightly less as callback invocation takes some time, |
2094 | roughly C<7> (likely slightly less as callback invocation takes some time, |
1869 | too), and so on. |
2095 | too), and so on. |
1870 | |
2096 | |
1871 | =item ev_tstamp repeat [read-write] |
2097 | =item ev_tstamp repeat [read-write] |
… | |
… | |
1900 | } |
2126 | } |
1901 | |
2127 | |
1902 | ev_timer mytimer; |
2128 | ev_timer mytimer; |
1903 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2129 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1904 | ev_timer_again (&mytimer); /* start timer */ |
2130 | ev_timer_again (&mytimer); /* start timer */ |
1905 | ev_loop (loop, 0); |
2131 | ev_run (loop, 0); |
1906 | |
2132 | |
1907 | // and in some piece of code that gets executed on any "activity": |
2133 | // and in some piece of code that gets executed on any "activity": |
1908 | // reset the timeout to start ticking again at 10 seconds |
2134 | // reset the timeout to start ticking again at 10 seconds |
1909 | ev_timer_again (&mytimer); |
2135 | ev_timer_again (&mytimer); |
1910 | |
2136 | |
… | |
… | |
1936 | |
2162 | |
1937 | As with timers, the callback is guaranteed to be invoked only when the |
2163 | As with timers, the callback is guaranteed to be invoked only when the |
1938 | point in time where it is supposed to trigger has passed. If multiple |
2164 | point in time where it is supposed to trigger has passed. If multiple |
1939 | timers become ready during the same loop iteration then the ones with |
2165 | timers become ready during the same loop iteration then the ones with |
1940 | earlier time-out values are invoked before ones with later time-out values |
2166 | earlier time-out values are invoked before ones with later time-out values |
1941 | (but this is no longer true when a callback calls C<ev_loop> recursively). |
2167 | (but this is no longer true when a callback calls C<ev_run> recursively). |
1942 | |
2168 | |
1943 | =head3 Watcher-Specific Functions and Data Members |
2169 | =head3 Watcher-Specific Functions and Data Members |
1944 | |
2170 | |
1945 | =over 4 |
2171 | =over 4 |
1946 | |
2172 | |
… | |
… | |
2074 | Example: Call a callback every hour, or, more precisely, whenever the |
2300 | Example: Call a callback every hour, or, more precisely, whenever the |
2075 | system time is divisible by 3600. The callback invocation times have |
2301 | system time is divisible by 3600. The callback invocation times have |
2076 | potentially a lot of jitter, but good long-term stability. |
2302 | potentially a lot of jitter, but good long-term stability. |
2077 | |
2303 | |
2078 | static void |
2304 | static void |
2079 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2305 | clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
2080 | { |
2306 | { |
2081 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2307 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2082 | } |
2308 | } |
2083 | |
2309 | |
2084 | ev_periodic hourly_tick; |
2310 | ev_periodic hourly_tick; |
… | |
… | |
2107 | |
2333 | |
2108 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2334 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2109 | |
2335 | |
2110 | Signal watchers will trigger an event when the process receives a specific |
2336 | Signal watchers will trigger an event when the process receives a specific |
2111 | signal one or more times. Even though signals are very asynchronous, libev |
2337 | signal one or more times. Even though signals are very asynchronous, libev |
2112 | will try it's best to deliver signals synchronously, i.e. as part of the |
2338 | will try its best to deliver signals synchronously, i.e. as part of the |
2113 | normal event processing, like any other event. |
2339 | normal event processing, like any other event. |
2114 | |
2340 | |
2115 | If you want signals to be delivered truly asynchronously, just use |
2341 | If you want signals to be delivered truly asynchronously, just use |
2116 | C<sigaction> as you would do without libev and forget about sharing |
2342 | C<sigaction> as you would do without libev and forget about sharing |
2117 | the signal. You can even use C<ev_async> from a signal handler to |
2343 | the signal. You can even use C<ev_async> from a signal handler to |
… | |
… | |
2131 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2357 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2132 | not be unduly interrupted. If you have a problem with system calls getting |
2358 | not be unduly interrupted. If you have a problem with system calls getting |
2133 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2359 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2134 | and unblock them in an C<ev_prepare> watcher. |
2360 | and unblock them in an C<ev_prepare> watcher. |
2135 | |
2361 | |
2136 | =head3 The special problem of inheritance over execve |
2362 | =head3 The special problem of inheritance over fork/execve/pthread_create |
2137 | |
2363 | |
2138 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2364 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2139 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2365 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2140 | stopping it again), that is, libev might or might not block the signal, |
2366 | stopping it again), that is, libev might or might not block the signal, |
2141 | and might or might not set or restore the installed signal handler. |
2367 | and might or might not set or restore the installed signal handler. |
… | |
… | |
2151 | |
2377 | |
2152 | The simplest way to ensure that the signal mask is reset in the child is |
2378 | The simplest way to ensure that the signal mask is reset in the child is |
2153 | to install a fork handler with C<pthread_atfork> that resets it. That will |
2379 | to install a fork handler with C<pthread_atfork> that resets it. That will |
2154 | catch fork calls done by libraries (such as the libc) as well. |
2380 | catch fork calls done by libraries (such as the libc) as well. |
2155 | |
2381 | |
2156 | In current versions of libev, you can also ensure that the signal mask is |
2382 | In current versions of libev, the signal will not be blocked indefinitely |
2157 | not blocking any signals (except temporarily, so thread users watch out) |
2383 | unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces |
2158 | by specifying the C<EVFLAG_NOSIGFD> when creating the event loop. This |
2384 | the window of opportunity for problems, it will not go away, as libev |
2159 | is not guaranteed for future versions, however. |
2385 | I<has> to modify the signal mask, at least temporarily. |
|
|
2386 | |
|
|
2387 | So I can't stress this enough: I<If you do not reset your signal mask when |
|
|
2388 | you expect it to be empty, you have a race condition in your code>. This |
|
|
2389 | is not a libev-specific thing, this is true for most event libraries. |
|
|
2390 | |
|
|
2391 | =head3 The special problem of threads signal handling |
|
|
2392 | |
|
|
2393 | POSIX threads has problematic signal handling semantics, specifically, |
|
|
2394 | a lot of functionality (sigfd, sigwait etc.) only really works if all |
|
|
2395 | threads in a process block signals, which is hard to achieve. |
|
|
2396 | |
|
|
2397 | When you want to use sigwait (or mix libev signal handling with your own |
|
|
2398 | for the same signals), you can tackle this problem by globally blocking |
|
|
2399 | all signals before creating any threads (or creating them with a fully set |
|
|
2400 | sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating |
|
|
2401 | loops. Then designate one thread as "signal receiver thread" which handles |
|
|
2402 | these signals. You can pass on any signals that libev might be interested |
|
|
2403 | in by calling C<ev_feed_signal>. |
2160 | |
2404 | |
2161 | =head3 Watcher-Specific Functions and Data Members |
2405 | =head3 Watcher-Specific Functions and Data Members |
2162 | |
2406 | |
2163 | =over 4 |
2407 | =over 4 |
2164 | |
2408 | |
… | |
… | |
2180 | Example: Try to exit cleanly on SIGINT. |
2424 | Example: Try to exit cleanly on SIGINT. |
2181 | |
2425 | |
2182 | static void |
2426 | static void |
2183 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2427 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2184 | { |
2428 | { |
2185 | ev_unloop (loop, EVUNLOOP_ALL); |
2429 | ev_break (loop, EVBREAK_ALL); |
2186 | } |
2430 | } |
2187 | |
2431 | |
2188 | ev_signal signal_watcher; |
2432 | ev_signal signal_watcher; |
2189 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2433 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2190 | ev_signal_start (loop, &signal_watcher); |
2434 | ev_signal_start (loop, &signal_watcher); |
… | |
… | |
2576 | |
2820 | |
2577 | Prepare and check watchers are usually (but not always) used in pairs: |
2821 | Prepare and check watchers are usually (but not always) used in pairs: |
2578 | prepare watchers get invoked before the process blocks and check watchers |
2822 | prepare watchers get invoked before the process blocks and check watchers |
2579 | afterwards. |
2823 | afterwards. |
2580 | |
2824 | |
2581 | You I<must not> call C<ev_loop> or similar functions that enter |
2825 | You I<must not> call C<ev_run> or similar functions that enter |
2582 | the current event loop from either C<ev_prepare> or C<ev_check> |
2826 | the current event loop from either C<ev_prepare> or C<ev_check> |
2583 | watchers. Other loops than the current one are fine, however. The |
2827 | watchers. Other loops than the current one are fine, however. The |
2584 | rationale behind this is that you do not need to check for recursion in |
2828 | rationale behind this is that you do not need to check for recursion in |
2585 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2829 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2586 | C<ev_check> so if you have one watcher of each kind they will always be |
2830 | C<ev_check> so if you have one watcher of each kind they will always be |
… | |
… | |
2754 | |
2998 | |
2755 | if (timeout >= 0) |
2999 | if (timeout >= 0) |
2756 | // create/start timer |
3000 | // create/start timer |
2757 | |
3001 | |
2758 | // poll |
3002 | // poll |
2759 | ev_loop (EV_A_ 0); |
3003 | ev_run (EV_A_ 0); |
2760 | |
3004 | |
2761 | // stop timer again |
3005 | // stop timer again |
2762 | if (timeout >= 0) |
3006 | if (timeout >= 0) |
2763 | ev_timer_stop (EV_A_ &to); |
3007 | ev_timer_stop (EV_A_ &to); |
2764 | |
3008 | |
… | |
… | |
2842 | if you do not want that, you need to temporarily stop the embed watcher). |
3086 | if you do not want that, you need to temporarily stop the embed watcher). |
2843 | |
3087 | |
2844 | =item ev_embed_sweep (loop, ev_embed *) |
3088 | =item ev_embed_sweep (loop, ev_embed *) |
2845 | |
3089 | |
2846 | Make a single, non-blocking sweep over the embedded loop. This works |
3090 | Make a single, non-blocking sweep over the embedded loop. This works |
2847 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
3091 | similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most |
2848 | appropriate way for embedded loops. |
3092 | appropriate way for embedded loops. |
2849 | |
3093 | |
2850 | =item struct ev_loop *other [read-only] |
3094 | =item struct ev_loop *other [read-only] |
2851 | |
3095 | |
2852 | The embedded event loop. |
3096 | The embedded event loop. |
… | |
… | |
2912 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3156 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2913 | handlers will be invoked, too, of course. |
3157 | handlers will be invoked, too, of course. |
2914 | |
3158 | |
2915 | =head3 The special problem of life after fork - how is it possible? |
3159 | =head3 The special problem of life after fork - how is it possible? |
2916 | |
3160 | |
2917 | Most uses of C<fork()> consist of forking, then some simple calls to ste |
3161 | Most uses of C<fork()> consist of forking, then some simple calls to set |
2918 | up/change the process environment, followed by a call to C<exec()>. This |
3162 | up/change the process environment, followed by a call to C<exec()>. This |
2919 | sequence should be handled by libev without any problems. |
3163 | sequence should be handled by libev without any problems. |
2920 | |
3164 | |
2921 | This changes when the application actually wants to do event handling |
3165 | This changes when the application actually wants to do event handling |
2922 | in the child, or both parent in child, in effect "continuing" after the |
3166 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
2938 | disadvantage of having to use multiple event loops (which do not support |
3182 | disadvantage of having to use multiple event loops (which do not support |
2939 | signal watchers). |
3183 | signal watchers). |
2940 | |
3184 | |
2941 | When this is not possible, or you want to use the default loop for |
3185 | When this is not possible, or you want to use the default loop for |
2942 | other reasons, then in the process that wants to start "fresh", call |
3186 | other reasons, then in the process that wants to start "fresh", call |
2943 | C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying |
3187 | C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>. |
2944 | the default loop will "orphan" (not stop) all registered watchers, so you |
3188 | Destroying the default loop will "orphan" (not stop) all registered |
2945 | have to be careful not to execute code that modifies those watchers. Note |
3189 | watchers, so you have to be careful not to execute code that modifies |
2946 | also that in that case, you have to re-register any signal watchers. |
3190 | those watchers. Note also that in that case, you have to re-register any |
|
|
3191 | signal watchers. |
2947 | |
3192 | |
2948 | =head3 Watcher-Specific Functions and Data Members |
3193 | =head3 Watcher-Specific Functions and Data Members |
2949 | |
3194 | |
2950 | =over 4 |
3195 | =over 4 |
2951 | |
3196 | |
2952 | =item ev_fork_init (ev_signal *, callback) |
3197 | =item ev_fork_init (ev_fork *, callback) |
2953 | |
3198 | |
2954 | Initialises and configures the fork watcher - it has no parameters of any |
3199 | Initialises and configures the fork watcher - it has no parameters of any |
2955 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
3200 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
2956 | believe me. |
3201 | really. |
2957 | |
3202 | |
2958 | =back |
3203 | =back |
2959 | |
3204 | |
2960 | |
3205 | |
|
|
3206 | =head2 C<ev_cleanup> - even the best things end |
|
|
3207 | |
|
|
3208 | Cleanup watchers are called just before the event loop is being destroyed |
|
|
3209 | by a call to C<ev_loop_destroy>. |
|
|
3210 | |
|
|
3211 | While there is no guarantee that the event loop gets destroyed, cleanup |
|
|
3212 | watchers provide a convenient method to install cleanup hooks for your |
|
|
3213 | program, worker threads and so on - you just to make sure to destroy the |
|
|
3214 | loop when you want them to be invoked. |
|
|
3215 | |
|
|
3216 | Cleanup watchers are invoked in the same way as any other watcher. Unlike |
|
|
3217 | all other watchers, they do not keep a reference to the event loop (which |
|
|
3218 | makes a lot of sense if you think about it). Like all other watchers, you |
|
|
3219 | can call libev functions in the callback, except C<ev_cleanup_start>. |
|
|
3220 | |
|
|
3221 | =head3 Watcher-Specific Functions and Data Members |
|
|
3222 | |
|
|
3223 | =over 4 |
|
|
3224 | |
|
|
3225 | =item ev_cleanup_init (ev_cleanup *, callback) |
|
|
3226 | |
|
|
3227 | Initialises and configures the cleanup watcher - it has no parameters of |
|
|
3228 | any kind. There is a C<ev_cleanup_set> macro, but using it is utterly |
|
|
3229 | pointless, I assure you. |
|
|
3230 | |
|
|
3231 | =back |
|
|
3232 | |
|
|
3233 | Example: Register an atexit handler to destroy the default loop, so any |
|
|
3234 | cleanup functions are called. |
|
|
3235 | |
|
|
3236 | static void |
|
|
3237 | program_exits (void) |
|
|
3238 | { |
|
|
3239 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
3240 | } |
|
|
3241 | |
|
|
3242 | ... |
|
|
3243 | atexit (program_exits); |
|
|
3244 | |
|
|
3245 | |
2961 | =head2 C<ev_async> - how to wake up another event loop |
3246 | =head2 C<ev_async> - how to wake up an event loop |
2962 | |
3247 | |
2963 | In general, you cannot use an C<ev_loop> from multiple threads or other |
3248 | In general, you cannot use an C<ev_run> from multiple threads or other |
2964 | asynchronous sources such as signal handlers (as opposed to multiple event |
3249 | asynchronous sources such as signal handlers (as opposed to multiple event |
2965 | loops - those are of course safe to use in different threads). |
3250 | loops - those are of course safe to use in different threads). |
2966 | |
3251 | |
2967 | Sometimes, however, you need to wake up another event loop you do not |
3252 | Sometimes, however, you need to wake up an event loop you do not control, |
2968 | control, for example because it belongs to another thread. This is what |
3253 | for example because it belongs to another thread. This is what C<ev_async> |
2969 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
3254 | watchers do: as long as the C<ev_async> watcher is active, you can signal |
2970 | can signal it by calling C<ev_async_send>, which is thread- and signal |
3255 | it by calling C<ev_async_send>, which is thread- and signal safe. |
2971 | safe. |
|
|
2972 | |
3256 | |
2973 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3257 | This functionality is very similar to C<ev_signal> watchers, as signals, |
2974 | too, are asynchronous in nature, and signals, too, will be compressed |
3258 | too, are asynchronous in nature, and signals, too, will be compressed |
2975 | (i.e. the number of callback invocations may be less than the number of |
3259 | (i.e. the number of callback invocations may be less than the number of |
2976 | C<ev_async_sent> calls). |
3260 | C<ev_async_sent> calls). In fact, you could use signal watchers as a kind |
|
|
3261 | of "global async watchers" by using a watcher on an otherwise unused |
|
|
3262 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
|
|
3263 | even without knowing which loop owns the signal. |
2977 | |
3264 | |
2978 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
3265 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
2979 | just the default loop. |
3266 | just the default loop. |
2980 | |
3267 | |
2981 | =head3 Queueing |
3268 | =head3 Queueing |
… | |
… | |
3131 | |
3418 | |
3132 | If C<timeout> is less than 0, then no timeout watcher will be |
3419 | If C<timeout> is less than 0, then no timeout watcher will be |
3133 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3420 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3134 | repeat = 0) will be started. C<0> is a valid timeout. |
3421 | repeat = 0) will be started. C<0> is a valid timeout. |
3135 | |
3422 | |
3136 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
3423 | The callback has the type C<void (*cb)(int revents, void *arg)> and is |
3137 | passed an C<revents> set like normal event callbacks (a combination of |
3424 | passed an C<revents> set like normal event callbacks (a combination of |
3138 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
3425 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg> |
3139 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3426 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3140 | a timeout and an io event at the same time - you probably should give io |
3427 | a timeout and an io event at the same time - you probably should give io |
3141 | events precedence. |
3428 | events precedence. |
3142 | |
3429 | |
3143 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3430 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3144 | |
3431 | |
3145 | static void stdin_ready (int revents, void *arg) |
3432 | static void stdin_ready (int revents, void *arg) |
3146 | { |
3433 | { |
3147 | if (revents & EV_READ) |
3434 | if (revents & EV_READ) |
3148 | /* stdin might have data for us, joy! */; |
3435 | /* stdin might have data for us, joy! */; |
3149 | else if (revents & EV_TIMEOUT) |
3436 | else if (revents & EV_TIMER) |
3150 | /* doh, nothing entered */; |
3437 | /* doh, nothing entered */; |
3151 | } |
3438 | } |
3152 | |
3439 | |
3153 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3440 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3154 | |
3441 | |
… | |
… | |
3157 | Feed an event on the given fd, as if a file descriptor backend detected |
3444 | Feed an event on the given fd, as if a file descriptor backend detected |
3158 | the given events it. |
3445 | the given events it. |
3159 | |
3446 | |
3160 | =item ev_feed_signal_event (loop, int signum) |
3447 | =item ev_feed_signal_event (loop, int signum) |
3161 | |
3448 | |
3162 | Feed an event as if the given signal occurred (C<loop> must be the default |
3449 | Feed an event as if the given signal occurred. See also C<ev_feed_signal>, |
3163 | loop!). |
3450 | which is async-safe. |
|
|
3451 | |
|
|
3452 | =back |
|
|
3453 | |
|
|
3454 | |
|
|
3455 | =head1 COMMON OR USEFUL IDIOMS (OR BOTH) |
|
|
3456 | |
|
|
3457 | This section explains some common idioms that are not immediately |
|
|
3458 | obvious. Note that examples are sprinkled over the whole manual, and this |
|
|
3459 | section only contains stuff that wouldn't fit anywhere else. |
|
|
3460 | |
|
|
3461 | =head2 MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS |
|
|
3462 | |
|
|
3463 | Often (especially in GUI toolkits) there are places where you have |
|
|
3464 | I<modal> interaction, which is most easily implemented by recursively |
|
|
3465 | invoking C<ev_run>. |
|
|
3466 | |
|
|
3467 | This brings the problem of exiting - a callback might want to finish the |
|
|
3468 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
|
|
3469 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
|
|
3470 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
|
|
3471 | other combination: In these cases, C<ev_break> will not work alone. |
|
|
3472 | |
|
|
3473 | The solution is to maintain "break this loop" variable for each C<ev_run> |
|
|
3474 | invocation, and use a loop around C<ev_run> until the condition is |
|
|
3475 | triggered, using C<EVRUN_ONCE>: |
|
|
3476 | |
|
|
3477 | // main loop |
|
|
3478 | int exit_main_loop = 0; |
|
|
3479 | |
|
|
3480 | while (!exit_main_loop) |
|
|
3481 | ev_run (EV_DEFAULT_ EVRUN_ONCE); |
|
|
3482 | |
|
|
3483 | // in a model watcher |
|
|
3484 | int exit_nested_loop = 0; |
|
|
3485 | |
|
|
3486 | while (!exit_nested_loop) |
|
|
3487 | ev_run (EV_A_ EVRUN_ONCE); |
|
|
3488 | |
|
|
3489 | To exit from any of these loops, just set the corresponding exit variable: |
|
|
3490 | |
|
|
3491 | // exit modal loop |
|
|
3492 | exit_nested_loop = 1; |
|
|
3493 | |
|
|
3494 | // exit main program, after modal loop is finished |
|
|
3495 | exit_main_loop = 1; |
|
|
3496 | |
|
|
3497 | // exit both |
|
|
3498 | exit_main_loop = exit_nested_loop = 1; |
|
|
3499 | |
|
|
3500 | =head2 THREAD LOCKING EXAMPLE |
|
|
3501 | |
|
|
3502 | Here is a fictitious example of how to run an event loop in a different |
|
|
3503 | thread than where callbacks are being invoked and watchers are |
|
|
3504 | created/added/removed. |
|
|
3505 | |
|
|
3506 | For a real-world example, see the C<EV::Loop::Async> perl module, |
|
|
3507 | which uses exactly this technique (which is suited for many high-level |
|
|
3508 | languages). |
|
|
3509 | |
|
|
3510 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
3511 | variable to wait for callback invocations, an async watcher to notify the |
|
|
3512 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
3513 | |
|
|
3514 | First, you need to associate some data with the event loop: |
|
|
3515 | |
|
|
3516 | typedef struct { |
|
|
3517 | mutex_t lock; /* global loop lock */ |
|
|
3518 | ev_async async_w; |
|
|
3519 | thread_t tid; |
|
|
3520 | cond_t invoke_cv; |
|
|
3521 | } userdata; |
|
|
3522 | |
|
|
3523 | void prepare_loop (EV_P) |
|
|
3524 | { |
|
|
3525 | // for simplicity, we use a static userdata struct. |
|
|
3526 | static userdata u; |
|
|
3527 | |
|
|
3528 | ev_async_init (&u->async_w, async_cb); |
|
|
3529 | ev_async_start (EV_A_ &u->async_w); |
|
|
3530 | |
|
|
3531 | pthread_mutex_init (&u->lock, 0); |
|
|
3532 | pthread_cond_init (&u->invoke_cv, 0); |
|
|
3533 | |
|
|
3534 | // now associate this with the loop |
|
|
3535 | ev_set_userdata (EV_A_ u); |
|
|
3536 | ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
3537 | ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
3538 | |
|
|
3539 | // then create the thread running ev_loop |
|
|
3540 | pthread_create (&u->tid, 0, l_run, EV_A); |
|
|
3541 | } |
|
|
3542 | |
|
|
3543 | The callback for the C<ev_async> watcher does nothing: the watcher is used |
|
|
3544 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
3545 | that might have been added: |
|
|
3546 | |
|
|
3547 | static void |
|
|
3548 | async_cb (EV_P_ ev_async *w, int revents) |
|
|
3549 | { |
|
|
3550 | // just used for the side effects |
|
|
3551 | } |
|
|
3552 | |
|
|
3553 | The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex |
|
|
3554 | protecting the loop data, respectively. |
|
|
3555 | |
|
|
3556 | static void |
|
|
3557 | l_release (EV_P) |
|
|
3558 | { |
|
|
3559 | userdata *u = ev_userdata (EV_A); |
|
|
3560 | pthread_mutex_unlock (&u->lock); |
|
|
3561 | } |
|
|
3562 | |
|
|
3563 | static void |
|
|
3564 | l_acquire (EV_P) |
|
|
3565 | { |
|
|
3566 | userdata *u = ev_userdata (EV_A); |
|
|
3567 | pthread_mutex_lock (&u->lock); |
|
|
3568 | } |
|
|
3569 | |
|
|
3570 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
3571 | into C<ev_run>: |
|
|
3572 | |
|
|
3573 | void * |
|
|
3574 | l_run (void *thr_arg) |
|
|
3575 | { |
|
|
3576 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
3577 | |
|
|
3578 | l_acquire (EV_A); |
|
|
3579 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
3580 | ev_run (EV_A_ 0); |
|
|
3581 | l_release (EV_A); |
|
|
3582 | |
|
|
3583 | return 0; |
|
|
3584 | } |
|
|
3585 | |
|
|
3586 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
|
|
3587 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
3588 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
|
|
3589 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
3590 | and b) skipping inter-thread-communication when there are no pending |
|
|
3591 | watchers is very beneficial): |
|
|
3592 | |
|
|
3593 | static void |
|
|
3594 | l_invoke (EV_P) |
|
|
3595 | { |
|
|
3596 | userdata *u = ev_userdata (EV_A); |
|
|
3597 | |
|
|
3598 | while (ev_pending_count (EV_A)) |
|
|
3599 | { |
|
|
3600 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
3601 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
|
|
3602 | } |
|
|
3603 | } |
|
|
3604 | |
|
|
3605 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
3606 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
|
|
3607 | thread to continue: |
|
|
3608 | |
|
|
3609 | static void |
|
|
3610 | real_invoke_pending (EV_P) |
|
|
3611 | { |
|
|
3612 | userdata *u = ev_userdata (EV_A); |
|
|
3613 | |
|
|
3614 | pthread_mutex_lock (&u->lock); |
|
|
3615 | ev_invoke_pending (EV_A); |
|
|
3616 | pthread_cond_signal (&u->invoke_cv); |
|
|
3617 | pthread_mutex_unlock (&u->lock); |
|
|
3618 | } |
|
|
3619 | |
|
|
3620 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
3621 | event loop, you will now have to lock: |
|
|
3622 | |
|
|
3623 | ev_timer timeout_watcher; |
|
|
3624 | userdata *u = ev_userdata (EV_A); |
|
|
3625 | |
|
|
3626 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
3627 | |
|
|
3628 | pthread_mutex_lock (&u->lock); |
|
|
3629 | ev_timer_start (EV_A_ &timeout_watcher); |
|
|
3630 | ev_async_send (EV_A_ &u->async_w); |
|
|
3631 | pthread_mutex_unlock (&u->lock); |
|
|
3632 | |
|
|
3633 | Note that sending the C<ev_async> watcher is required because otherwise |
|
|
3634 | an event loop currently blocking in the kernel will have no knowledge |
|
|
3635 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
3636 | watchers in the next event loop iteration. |
3164 | |
3637 | |
3165 | =back |
3638 | =back |
3166 | |
3639 | |
3167 | |
3640 | |
3168 | =head1 LIBEVENT EMULATION |
3641 | =head1 LIBEVENT EMULATION |
3169 | |
3642 | |
3170 | Libev offers a compatibility emulation layer for libevent. It cannot |
3643 | Libev offers a compatibility emulation layer for libevent. It cannot |
3171 | emulate the internals of libevent, so here are some usage hints: |
3644 | emulate the internals of libevent, so here are some usage hints: |
3172 | |
3645 | |
3173 | =over 4 |
3646 | =over 4 |
|
|
3647 | |
|
|
3648 | =item * Only the libevent-1.4.1-beta API is being emulated. |
|
|
3649 | |
|
|
3650 | This was the newest libevent version available when libev was implemented, |
|
|
3651 | and is still mostly unchanged in 2010. |
3174 | |
3652 | |
3175 | =item * Use it by including <event.h>, as usual. |
3653 | =item * Use it by including <event.h>, as usual. |
3176 | |
3654 | |
3177 | =item * The following members are fully supported: ev_base, ev_callback, |
3655 | =item * The following members are fully supported: ev_base, ev_callback, |
3178 | ev_arg, ev_fd, ev_res, ev_events. |
3656 | ev_arg, ev_fd, ev_res, ev_events. |
… | |
… | |
3184 | =item * Priorities are not currently supported. Initialising priorities |
3662 | =item * Priorities are not currently supported. Initialising priorities |
3185 | will fail and all watchers will have the same priority, even though there |
3663 | will fail and all watchers will have the same priority, even though there |
3186 | is an ev_pri field. |
3664 | is an ev_pri field. |
3187 | |
3665 | |
3188 | =item * In libevent, the last base created gets the signals, in libev, the |
3666 | =item * In libevent, the last base created gets the signals, in libev, the |
3189 | first base created (== the default loop) gets the signals. |
3667 | base that registered the signal gets the signals. |
3190 | |
3668 | |
3191 | =item * Other members are not supported. |
3669 | =item * Other members are not supported. |
3192 | |
3670 | |
3193 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
3671 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
3194 | to use the libev header file and library. |
3672 | to use the libev header file and library. |
… | |
… | |
3213 | Care has been taken to keep the overhead low. The only data member the C++ |
3691 | Care has been taken to keep the overhead low. The only data member the C++ |
3214 | classes add (compared to plain C-style watchers) is the event loop pointer |
3692 | classes add (compared to plain C-style watchers) is the event loop pointer |
3215 | that the watcher is associated with (or no additional members at all if |
3693 | that the watcher is associated with (or no additional members at all if |
3216 | you disable C<EV_MULTIPLICITY> when embedding libev). |
3694 | you disable C<EV_MULTIPLICITY> when embedding libev). |
3217 | |
3695 | |
3218 | Currently, functions, and static and non-static member functions can be |
3696 | Currently, functions, static and non-static member functions and classes |
3219 | used as callbacks. Other types should be easy to add as long as they only |
3697 | with C<operator ()> can be used as callbacks. Other types should be easy |
3220 | need one additional pointer for context. If you need support for other |
3698 | to add as long as they only need one additional pointer for context. If |
3221 | types of functors please contact the author (preferably after implementing |
3699 | you need support for other types of functors please contact the author |
3222 | it). |
3700 | (preferably after implementing it). |
3223 | |
3701 | |
3224 | Here is a list of things available in the C<ev> namespace: |
3702 | Here is a list of things available in the C<ev> namespace: |
3225 | |
3703 | |
3226 | =over 4 |
3704 | =over 4 |
3227 | |
3705 | |
… | |
… | |
3288 | myclass obj; |
3766 | myclass obj; |
3289 | ev::io iow; |
3767 | ev::io iow; |
3290 | iow.set <myclass, &myclass::io_cb> (&obj); |
3768 | iow.set <myclass, &myclass::io_cb> (&obj); |
3291 | |
3769 | |
3292 | =item w->set (object *) |
3770 | =item w->set (object *) |
3293 | |
|
|
3294 | This is an B<experimental> feature that might go away in a future version. |
|
|
3295 | |
3771 | |
3296 | This is a variation of a method callback - leaving out the method to call |
3772 | This is a variation of a method callback - leaving out the method to call |
3297 | will default the method to C<operator ()>, which makes it possible to use |
3773 | will default the method to C<operator ()>, which makes it possible to use |
3298 | functor objects without having to manually specify the C<operator ()> all |
3774 | functor objects without having to manually specify the C<operator ()> all |
3299 | the time. Incidentally, you can then also leave out the template argument |
3775 | the time. Incidentally, you can then also leave out the template argument |
… | |
… | |
3339 | Associates a different C<struct ev_loop> with this watcher. You can only |
3815 | Associates a different C<struct ev_loop> with this watcher. You can only |
3340 | do this when the watcher is inactive (and not pending either). |
3816 | do this when the watcher is inactive (and not pending either). |
3341 | |
3817 | |
3342 | =item w->set ([arguments]) |
3818 | =item w->set ([arguments]) |
3343 | |
3819 | |
3344 | Basically the same as C<ev_TYPE_set>, with the same arguments. Must be |
3820 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
3345 | called at least once. Unlike the C counterpart, an active watcher gets |
3821 | method or a suitable start method must be called at least once. Unlike the |
3346 | automatically stopped and restarted when reconfiguring it with this |
3822 | C counterpart, an active watcher gets automatically stopped and restarted |
3347 | method. |
3823 | when reconfiguring it with this method. |
3348 | |
3824 | |
3349 | =item w->start () |
3825 | =item w->start () |
3350 | |
3826 | |
3351 | Starts the watcher. Note that there is no C<loop> argument, as the |
3827 | Starts the watcher. Note that there is no C<loop> argument, as the |
3352 | constructor already stores the event loop. |
3828 | constructor already stores the event loop. |
3353 | |
3829 | |
|
|
3830 | =item w->start ([arguments]) |
|
|
3831 | |
|
|
3832 | Instead of calling C<set> and C<start> methods separately, it is often |
|
|
3833 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
3834 | the configure C<set> method of the watcher. |
|
|
3835 | |
3354 | =item w->stop () |
3836 | =item w->stop () |
3355 | |
3837 | |
3356 | Stops the watcher if it is active. Again, no C<loop> argument. |
3838 | Stops the watcher if it is active. Again, no C<loop> argument. |
3357 | |
3839 | |
3358 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
3840 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
… | |
… | |
3370 | |
3852 | |
3371 | =back |
3853 | =back |
3372 | |
3854 | |
3373 | =back |
3855 | =back |
3374 | |
3856 | |
3375 | Example: Define a class with an IO and idle watcher, start one of them in |
3857 | Example: Define a class with two I/O and idle watchers, start the I/O |
3376 | the constructor. |
3858 | watchers in the constructor. |
3377 | |
3859 | |
3378 | class myclass |
3860 | class myclass |
3379 | { |
3861 | { |
3380 | ev::io io ; void io_cb (ev::io &w, int revents); |
3862 | ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
3863 | ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
3381 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3864 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3382 | |
3865 | |
3383 | myclass (int fd) |
3866 | myclass (int fd) |
3384 | { |
3867 | { |
3385 | io .set <myclass, &myclass::io_cb > (this); |
3868 | io .set <myclass, &myclass::io_cb > (this); |
|
|
3869 | io2 .set <myclass, &myclass::io2_cb > (this); |
3386 | idle.set <myclass, &myclass::idle_cb> (this); |
3870 | idle.set <myclass, &myclass::idle_cb> (this); |
3387 | |
3871 | |
3388 | io.start (fd, ev::READ); |
3872 | io.set (fd, ev::WRITE); // configure the watcher |
|
|
3873 | io.start (); // start it whenever convenient |
|
|
3874 | |
|
|
3875 | io2.start (fd, ev::READ); // set + start in one call |
3389 | } |
3876 | } |
3390 | }; |
3877 | }; |
3391 | |
3878 | |
3392 | |
3879 | |
3393 | =head1 OTHER LANGUAGE BINDINGS |
3880 | =head1 OTHER LANGUAGE BINDINGS |
… | |
… | |
3441 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3928 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3442 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3929 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3443 | |
3930 | |
3444 | =item Lua |
3931 | =item Lua |
3445 | |
3932 | |
3446 | Brian Maher has written a partial interface to libev |
3933 | Brian Maher has written a partial interface to libev for lua (at the |
3447 | for lua (only C<ev_io> and C<ev_timer>), to be found at |
3934 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
3448 | L<http://github.com/brimworks/lua-ev>. |
3935 | L<http://github.com/brimworks/lua-ev>. |
3449 | |
3936 | |
3450 | =back |
3937 | =back |
3451 | |
3938 | |
3452 | |
3939 | |
… | |
… | |
3467 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3954 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3468 | C<EV_A_> is used when other arguments are following. Example: |
3955 | C<EV_A_> is used when other arguments are following. Example: |
3469 | |
3956 | |
3470 | ev_unref (EV_A); |
3957 | ev_unref (EV_A); |
3471 | ev_timer_add (EV_A_ watcher); |
3958 | ev_timer_add (EV_A_ watcher); |
3472 | ev_loop (EV_A_ 0); |
3959 | ev_run (EV_A_ 0); |
3473 | |
3960 | |
3474 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3961 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3475 | which is often provided by the following macro. |
3962 | which is often provided by the following macro. |
3476 | |
3963 | |
3477 | =item C<EV_P>, C<EV_P_> |
3964 | =item C<EV_P>, C<EV_P_> |
… | |
… | |
3517 | } |
4004 | } |
3518 | |
4005 | |
3519 | ev_check check; |
4006 | ev_check check; |
3520 | ev_check_init (&check, check_cb); |
4007 | ev_check_init (&check, check_cb); |
3521 | ev_check_start (EV_DEFAULT_ &check); |
4008 | ev_check_start (EV_DEFAULT_ &check); |
3522 | ev_loop (EV_DEFAULT_ 0); |
4009 | ev_run (EV_DEFAULT_ 0); |
3523 | |
4010 | |
3524 | =head1 EMBEDDING |
4011 | =head1 EMBEDDING |
3525 | |
4012 | |
3526 | Libev can (and often is) directly embedded into host |
4013 | Libev can (and often is) directly embedded into host |
3527 | applications. Examples of applications that embed it include the Deliantra |
4014 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3607 | libev.m4 |
4094 | libev.m4 |
3608 | |
4095 | |
3609 | =head2 PREPROCESSOR SYMBOLS/MACROS |
4096 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3610 | |
4097 | |
3611 | Libev can be configured via a variety of preprocessor symbols you have to |
4098 | Libev can be configured via a variety of preprocessor symbols you have to |
3612 | define before including any of its files. The default in the absence of |
4099 | define before including (or compiling) any of its files. The default in |
3613 | autoconf is documented for every option. |
4100 | the absence of autoconf is documented for every option. |
|
|
4101 | |
|
|
4102 | Symbols marked with "(h)" do not change the ABI, and can have different |
|
|
4103 | values when compiling libev vs. including F<ev.h>, so it is permissible |
|
|
4104 | to redefine them before including F<ev.h> without breaking compatibility |
|
|
4105 | to a compiled library. All other symbols change the ABI, which means all |
|
|
4106 | users of libev and the libev code itself must be compiled with compatible |
|
|
4107 | settings. |
3614 | |
4108 | |
3615 | =over 4 |
4109 | =over 4 |
3616 | |
4110 | |
|
|
4111 | =item EV_COMPAT3 (h) |
|
|
4112 | |
|
|
4113 | Backwards compatibility is a major concern for libev. This is why this |
|
|
4114 | release of libev comes with wrappers for the functions and symbols that |
|
|
4115 | have been renamed between libev version 3 and 4. |
|
|
4116 | |
|
|
4117 | You can disable these wrappers (to test compatibility with future |
|
|
4118 | versions) by defining C<EV_COMPAT3> to C<0> when compiling your |
|
|
4119 | sources. This has the additional advantage that you can drop the C<struct> |
|
|
4120 | from C<struct ev_loop> declarations, as libev will provide an C<ev_loop> |
|
|
4121 | typedef in that case. |
|
|
4122 | |
|
|
4123 | In some future version, the default for C<EV_COMPAT3> will become C<0>, |
|
|
4124 | and in some even more future version the compatibility code will be |
|
|
4125 | removed completely. |
|
|
4126 | |
3617 | =item EV_STANDALONE |
4127 | =item EV_STANDALONE (h) |
3618 | |
4128 | |
3619 | Must always be C<1> if you do not use autoconf configuration, which |
4129 | Must always be C<1> if you do not use autoconf configuration, which |
3620 | keeps libev from including F<config.h>, and it also defines dummy |
4130 | keeps libev from including F<config.h>, and it also defines dummy |
3621 | implementations for some libevent functions (such as logging, which is not |
4131 | implementations for some libevent functions (such as logging, which is not |
3622 | supported). It will also not define any of the structs usually found in |
4132 | supported). It will also not define any of the structs usually found in |
… | |
… | |
3772 | as well as for signal and thread safety in C<ev_async> watchers. |
4282 | as well as for signal and thread safety in C<ev_async> watchers. |
3773 | |
4283 | |
3774 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4284 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3775 | (from F<signal.h>), which is usually good enough on most platforms. |
4285 | (from F<signal.h>), which is usually good enough on most platforms. |
3776 | |
4286 | |
3777 | =item EV_H |
4287 | =item EV_H (h) |
3778 | |
4288 | |
3779 | The name of the F<ev.h> header file used to include it. The default if |
4289 | The name of the F<ev.h> header file used to include it. The default if |
3780 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
4290 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3781 | used to virtually rename the F<ev.h> header file in case of conflicts. |
4291 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3782 | |
4292 | |
3783 | =item EV_CONFIG_H |
4293 | =item EV_CONFIG_H (h) |
3784 | |
4294 | |
3785 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
4295 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3786 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
4296 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3787 | C<EV_H>, above. |
4297 | C<EV_H>, above. |
3788 | |
4298 | |
3789 | =item EV_EVENT_H |
4299 | =item EV_EVENT_H (h) |
3790 | |
4300 | |
3791 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
4301 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3792 | of how the F<event.h> header can be found, the default is C<"event.h">. |
4302 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3793 | |
4303 | |
3794 | =item EV_PROTOTYPES |
4304 | =item EV_PROTOTYPES (h) |
3795 | |
4305 | |
3796 | If defined to be C<0>, then F<ev.h> will not define any function |
4306 | If defined to be C<0>, then F<ev.h> will not define any function |
3797 | prototypes, but still define all the structs and other symbols. This is |
4307 | prototypes, but still define all the structs and other symbols. This is |
3798 | occasionally useful if you want to provide your own wrapper functions |
4308 | occasionally useful if you want to provide your own wrapper functions |
3799 | around libev functions. |
4309 | around libev functions. |
… | |
… | |
3821 | fine. |
4331 | fine. |
3822 | |
4332 | |
3823 | If your embedding application does not need any priorities, defining these |
4333 | If your embedding application does not need any priorities, defining these |
3824 | both to C<0> will save some memory and CPU. |
4334 | both to C<0> will save some memory and CPU. |
3825 | |
4335 | |
3826 | =item EV_PERIODIC_ENABLE |
4336 | =item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, |
|
|
4337 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
|
|
4338 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3827 | |
4339 | |
3828 | If undefined or defined to be C<1>, then periodic timers are supported. If |
4340 | If undefined or defined to be C<1> (and the platform supports it), then |
3829 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
4341 | the respective watcher type is supported. If defined to be C<0>, then it |
3830 | code. |
4342 | is not. Disabling watcher types mainly saves code size. |
3831 | |
4343 | |
3832 | =item EV_IDLE_ENABLE |
4344 | =item EV_FEATURES |
3833 | |
|
|
3834 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3835 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3836 | code. |
|
|
3837 | |
|
|
3838 | =item EV_EMBED_ENABLE |
|
|
3839 | |
|
|
3840 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3841 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3842 | watcher types, which therefore must not be disabled. |
|
|
3843 | |
|
|
3844 | =item EV_STAT_ENABLE |
|
|
3845 | |
|
|
3846 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3847 | defined to be C<0>, then they are not. |
|
|
3848 | |
|
|
3849 | =item EV_FORK_ENABLE |
|
|
3850 | |
|
|
3851 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3852 | defined to be C<0>, then they are not. |
|
|
3853 | |
|
|
3854 | =item EV_ASYNC_ENABLE |
|
|
3855 | |
|
|
3856 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3857 | defined to be C<0>, then they are not. |
|
|
3858 | |
|
|
3859 | =item EV_MINIMAL |
|
|
3860 | |
4345 | |
3861 | If you need to shave off some kilobytes of code at the expense of some |
4346 | If you need to shave off some kilobytes of code at the expense of some |
3862 | speed (but with the full API), define this symbol to C<1>. Currently this |
4347 | speed (but with the full API), you can define this symbol to request |
3863 | is used to override some inlining decisions, saves roughly 30% code size |
4348 | certain subsets of functionality. The default is to enable all features |
3864 | on amd64. It also selects a much smaller 2-heap for timer management over |
4349 | that can be enabled on the platform. |
3865 | the default 4-heap. |
|
|
3866 | |
4350 | |
3867 | You can save even more by disabling watcher types you do not need |
4351 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
3868 | and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert> |
4352 | with some broad features you want) and then selectively re-enable |
3869 | (C<-DNDEBUG>) will usually reduce code size a lot. |
4353 | additional parts you want, for example if you want everything minimal, |
|
|
4354 | but multiple event loop support, async and child watchers and the poll |
|
|
4355 | backend, use this: |
3870 | |
4356 | |
3871 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
4357 | #define EV_FEATURES 0 |
3872 | provide a bare-bones event library. See C<ev.h> for details on what parts |
4358 | #define EV_MULTIPLICITY 1 |
3873 | of the API are still available, and do not complain if this subset changes |
4359 | #define EV_USE_POLL 1 |
3874 | over time. |
4360 | #define EV_CHILD_ENABLE 1 |
|
|
4361 | #define EV_ASYNC_ENABLE 1 |
|
|
4362 | |
|
|
4363 | The actual value is a bitset, it can be a combination of the following |
|
|
4364 | values: |
|
|
4365 | |
|
|
4366 | =over 4 |
|
|
4367 | |
|
|
4368 | =item C<1> - faster/larger code |
|
|
4369 | |
|
|
4370 | Use larger code to speed up some operations. |
|
|
4371 | |
|
|
4372 | Currently this is used to override some inlining decisions (enlarging the |
|
|
4373 | code size by roughly 30% on amd64). |
|
|
4374 | |
|
|
4375 | When optimising for size, use of compiler flags such as C<-Os> with |
|
|
4376 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
|
|
4377 | assertions. |
|
|
4378 | |
|
|
4379 | =item C<2> - faster/larger data structures |
|
|
4380 | |
|
|
4381 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
|
|
4382 | hash table sizes and so on. This will usually further increase code size |
|
|
4383 | and can additionally have an effect on the size of data structures at |
|
|
4384 | runtime. |
|
|
4385 | |
|
|
4386 | =item C<4> - full API configuration |
|
|
4387 | |
|
|
4388 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
|
|
4389 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
|
|
4390 | |
|
|
4391 | =item C<8> - full API |
|
|
4392 | |
|
|
4393 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
|
|
4394 | details on which parts of the API are still available without this |
|
|
4395 | feature, and do not complain if this subset changes over time. |
|
|
4396 | |
|
|
4397 | =item C<16> - enable all optional watcher types |
|
|
4398 | |
|
|
4399 | Enables all optional watcher types. If you want to selectively enable |
|
|
4400 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
4401 | embed, async, child...) you can enable them manually by defining |
|
|
4402 | C<EV_watchertype_ENABLE> to C<1> instead. |
|
|
4403 | |
|
|
4404 | =item C<32> - enable all backends |
|
|
4405 | |
|
|
4406 | This enables all backends - without this feature, you need to enable at |
|
|
4407 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
|
|
4408 | |
|
|
4409 | =item C<64> - enable OS-specific "helper" APIs |
|
|
4410 | |
|
|
4411 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
4412 | default. |
|
|
4413 | |
|
|
4414 | =back |
|
|
4415 | |
|
|
4416 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
|
|
4417 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
4418 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
4419 | watchers, timers and monotonic clock support. |
|
|
4420 | |
|
|
4421 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
4422 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
|
|
4423 | your program might be left out as well - a binary starting a timer and an |
|
|
4424 | I/O watcher then might come out at only 5Kb. |
|
|
4425 | |
|
|
4426 | =item EV_AVOID_STDIO |
|
|
4427 | |
|
|
4428 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
|
|
4429 | functions (printf, scanf, perror etc.). This will increase the code size |
|
|
4430 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
4431 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
4432 | big. |
|
|
4433 | |
|
|
4434 | Note that error messages might become less precise when this option is |
|
|
4435 | enabled. |
3875 | |
4436 | |
3876 | =item EV_NSIG |
4437 | =item EV_NSIG |
3877 | |
4438 | |
3878 | The highest supported signal number, +1 (or, the number of |
4439 | The highest supported signal number, +1 (or, the number of |
3879 | signals): Normally, libev tries to deduce the maximum number of signals |
4440 | signals): Normally, libev tries to deduce the maximum number of signals |
3880 | automatically, but sometimes this fails, in which case it can be |
4441 | automatically, but sometimes this fails, in which case it can be |
3881 | specified. Also, using a lower number than detected (C<32> should be |
4442 | specified. Also, using a lower number than detected (C<32> should be |
3882 | good for about any system in existance) can save some memory, as libev |
4443 | good for about any system in existence) can save some memory, as libev |
3883 | statically allocates some 12-24 bytes per signal number. |
4444 | statically allocates some 12-24 bytes per signal number. |
3884 | |
4445 | |
3885 | =item EV_PID_HASHSIZE |
4446 | =item EV_PID_HASHSIZE |
3886 | |
4447 | |
3887 | C<ev_child> watchers use a small hash table to distribute workload by |
4448 | C<ev_child> watchers use a small hash table to distribute workload by |
3888 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
4449 | pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled), |
3889 | than enough. If you need to manage thousands of children you might want to |
4450 | usually more than enough. If you need to manage thousands of children you |
3890 | increase this value (I<must> be a power of two). |
4451 | might want to increase this value (I<must> be a power of two). |
3891 | |
4452 | |
3892 | =item EV_INOTIFY_HASHSIZE |
4453 | =item EV_INOTIFY_HASHSIZE |
3893 | |
4454 | |
3894 | C<ev_stat> watchers use a small hash table to distribute workload by |
4455 | C<ev_stat> watchers use a small hash table to distribute workload by |
3895 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
4456 | inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES> |
3896 | usually more than enough. If you need to manage thousands of C<ev_stat> |
4457 | disabled), usually more than enough. If you need to manage thousands of |
3897 | watchers you might want to increase this value (I<must> be a power of |
4458 | C<ev_stat> watchers you might want to increase this value (I<must> be a |
3898 | two). |
4459 | power of two). |
3899 | |
4460 | |
3900 | =item EV_USE_4HEAP |
4461 | =item EV_USE_4HEAP |
3901 | |
4462 | |
3902 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4463 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3903 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
4464 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3904 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
4465 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3905 | faster performance with many (thousands) of watchers. |
4466 | faster performance with many (thousands) of watchers. |
3906 | |
4467 | |
3907 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4468 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3908 | (disabled). |
4469 | will be C<0>. |
3909 | |
4470 | |
3910 | =item EV_HEAP_CACHE_AT |
4471 | =item EV_HEAP_CACHE_AT |
3911 | |
4472 | |
3912 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4473 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3913 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
4474 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3914 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
4475 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3915 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
4476 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3916 | but avoids random read accesses on heap changes. This improves performance |
4477 | but avoids random read accesses on heap changes. This improves performance |
3917 | noticeably with many (hundreds) of watchers. |
4478 | noticeably with many (hundreds) of watchers. |
3918 | |
4479 | |
3919 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4480 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3920 | (disabled). |
4481 | will be C<0>. |
3921 | |
4482 | |
3922 | =item EV_VERIFY |
4483 | =item EV_VERIFY |
3923 | |
4484 | |
3924 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4485 | Controls how much internal verification (see C<ev_verify ()>) will |
3925 | be done: If set to C<0>, no internal verification code will be compiled |
4486 | be done: If set to C<0>, no internal verification code will be compiled |
3926 | in. If set to C<1>, then verification code will be compiled in, but not |
4487 | in. If set to C<1>, then verification code will be compiled in, but not |
3927 | called. If set to C<2>, then the internal verification code will be |
4488 | called. If set to C<2>, then the internal verification code will be |
3928 | called once per loop, which can slow down libev. If set to C<3>, then the |
4489 | called once per loop, which can slow down libev. If set to C<3>, then the |
3929 | verification code will be called very frequently, which will slow down |
4490 | verification code will be called very frequently, which will slow down |
3930 | libev considerably. |
4491 | libev considerably. |
3931 | |
4492 | |
3932 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
4493 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3933 | C<0>. |
4494 | will be C<0>. |
3934 | |
4495 | |
3935 | =item EV_COMMON |
4496 | =item EV_COMMON |
3936 | |
4497 | |
3937 | By default, all watchers have a C<void *data> member. By redefining |
4498 | By default, all watchers have a C<void *data> member. By redefining |
3938 | this macro to a something else you can include more and other types of |
4499 | this macro to something else you can include more and other types of |
3939 | members. You have to define it each time you include one of the files, |
4500 | members. You have to define it each time you include one of the files, |
3940 | though, and it must be identical each time. |
4501 | though, and it must be identical each time. |
3941 | |
4502 | |
3942 | For example, the perl EV module uses something like this: |
4503 | For example, the perl EV module uses something like this: |
3943 | |
4504 | |
… | |
… | |
3996 | file. |
4557 | file. |
3997 | |
4558 | |
3998 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4559 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
3999 | that everybody includes and which overrides some configure choices: |
4560 | that everybody includes and which overrides some configure choices: |
4000 | |
4561 | |
4001 | #define EV_MINIMAL 1 |
4562 | #define EV_FEATURES 8 |
4002 | #define EV_USE_POLL 0 |
4563 | #define EV_USE_SELECT 1 |
4003 | #define EV_MULTIPLICITY 0 |
|
|
4004 | #define EV_PERIODIC_ENABLE 0 |
4564 | #define EV_PREPARE_ENABLE 1 |
|
|
4565 | #define EV_IDLE_ENABLE 1 |
4005 | #define EV_STAT_ENABLE 0 |
4566 | #define EV_SIGNAL_ENABLE 1 |
4006 | #define EV_FORK_ENABLE 0 |
4567 | #define EV_CHILD_ENABLE 1 |
|
|
4568 | #define EV_USE_STDEXCEPT 0 |
4007 | #define EV_CONFIG_H <config.h> |
4569 | #define EV_CONFIG_H <config.h> |
4008 | #define EV_MINPRI 0 |
|
|
4009 | #define EV_MAXPRI 0 |
|
|
4010 | |
4570 | |
4011 | #include "ev++.h" |
4571 | #include "ev++.h" |
4012 | |
4572 | |
4013 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4573 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4014 | |
4574 | |
… | |
… | |
4074 | default loop and triggering an C<ev_async> watcher from the default loop |
4634 | default loop and triggering an C<ev_async> watcher from the default loop |
4075 | watcher callback into the event loop interested in the signal. |
4635 | watcher callback into the event loop interested in the signal. |
4076 | |
4636 | |
4077 | =back |
4637 | =back |
4078 | |
4638 | |
4079 | =head4 THREAD LOCKING EXAMPLE |
4639 | See also L<THREAD LOCKING EXAMPLE>. |
4080 | |
|
|
4081 | Here is a fictitious example of how to run an event loop in a different |
|
|
4082 | thread than where callbacks are being invoked and watchers are |
|
|
4083 | created/added/removed. |
|
|
4084 | |
|
|
4085 | For a real-world example, see the C<EV::Loop::Async> perl module, |
|
|
4086 | which uses exactly this technique (which is suited for many high-level |
|
|
4087 | languages). |
|
|
4088 | |
|
|
4089 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
4090 | variable to wait for callback invocations, an async watcher to notify the |
|
|
4091 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
4092 | |
|
|
4093 | First, you need to associate some data with the event loop: |
|
|
4094 | |
|
|
4095 | typedef struct { |
|
|
4096 | mutex_t lock; /* global loop lock */ |
|
|
4097 | ev_async async_w; |
|
|
4098 | thread_t tid; |
|
|
4099 | cond_t invoke_cv; |
|
|
4100 | } userdata; |
|
|
4101 | |
|
|
4102 | void prepare_loop (EV_P) |
|
|
4103 | { |
|
|
4104 | // for simplicity, we use a static userdata struct. |
|
|
4105 | static userdata u; |
|
|
4106 | |
|
|
4107 | ev_async_init (&u->async_w, async_cb); |
|
|
4108 | ev_async_start (EV_A_ &u->async_w); |
|
|
4109 | |
|
|
4110 | pthread_mutex_init (&u->lock, 0); |
|
|
4111 | pthread_cond_init (&u->invoke_cv, 0); |
|
|
4112 | |
|
|
4113 | // now associate this with the loop |
|
|
4114 | ev_set_userdata (EV_A_ u); |
|
|
4115 | ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
4116 | ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
4117 | |
|
|
4118 | // then create the thread running ev_loop |
|
|
4119 | pthread_create (&u->tid, 0, l_run, EV_A); |
|
|
4120 | } |
|
|
4121 | |
|
|
4122 | The callback for the C<ev_async> watcher does nothing: the watcher is used |
|
|
4123 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
4124 | that might have been added: |
|
|
4125 | |
|
|
4126 | static void |
|
|
4127 | async_cb (EV_P_ ev_async *w, int revents) |
|
|
4128 | { |
|
|
4129 | // just used for the side effects |
|
|
4130 | } |
|
|
4131 | |
|
|
4132 | The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex |
|
|
4133 | protecting the loop data, respectively. |
|
|
4134 | |
|
|
4135 | static void |
|
|
4136 | l_release (EV_P) |
|
|
4137 | { |
|
|
4138 | userdata *u = ev_userdata (EV_A); |
|
|
4139 | pthread_mutex_unlock (&u->lock); |
|
|
4140 | } |
|
|
4141 | |
|
|
4142 | static void |
|
|
4143 | l_acquire (EV_P) |
|
|
4144 | { |
|
|
4145 | userdata *u = ev_userdata (EV_A); |
|
|
4146 | pthread_mutex_lock (&u->lock); |
|
|
4147 | } |
|
|
4148 | |
|
|
4149 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4150 | into C<ev_loop>: |
|
|
4151 | |
|
|
4152 | void * |
|
|
4153 | l_run (void *thr_arg) |
|
|
4154 | { |
|
|
4155 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4156 | |
|
|
4157 | l_acquire (EV_A); |
|
|
4158 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4159 | ev_loop (EV_A_ 0); |
|
|
4160 | l_release (EV_A); |
|
|
4161 | |
|
|
4162 | return 0; |
|
|
4163 | } |
|
|
4164 | |
|
|
4165 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
|
|
4166 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4167 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
|
|
4168 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4169 | and b) skipping inter-thread-communication when there are no pending |
|
|
4170 | watchers is very beneficial): |
|
|
4171 | |
|
|
4172 | static void |
|
|
4173 | l_invoke (EV_P) |
|
|
4174 | { |
|
|
4175 | userdata *u = ev_userdata (EV_A); |
|
|
4176 | |
|
|
4177 | while (ev_pending_count (EV_A)) |
|
|
4178 | { |
|
|
4179 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4180 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
|
|
4181 | } |
|
|
4182 | } |
|
|
4183 | |
|
|
4184 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4185 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
|
|
4186 | thread to continue: |
|
|
4187 | |
|
|
4188 | static void |
|
|
4189 | real_invoke_pending (EV_P) |
|
|
4190 | { |
|
|
4191 | userdata *u = ev_userdata (EV_A); |
|
|
4192 | |
|
|
4193 | pthread_mutex_lock (&u->lock); |
|
|
4194 | ev_invoke_pending (EV_A); |
|
|
4195 | pthread_cond_signal (&u->invoke_cv); |
|
|
4196 | pthread_mutex_unlock (&u->lock); |
|
|
4197 | } |
|
|
4198 | |
|
|
4199 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4200 | event loop, you will now have to lock: |
|
|
4201 | |
|
|
4202 | ev_timer timeout_watcher; |
|
|
4203 | userdata *u = ev_userdata (EV_A); |
|
|
4204 | |
|
|
4205 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4206 | |
|
|
4207 | pthread_mutex_lock (&u->lock); |
|
|
4208 | ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4209 | ev_async_send (EV_A_ &u->async_w); |
|
|
4210 | pthread_mutex_unlock (&u->lock); |
|
|
4211 | |
|
|
4212 | Note that sending the C<ev_async> watcher is required because otherwise |
|
|
4213 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4214 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4215 | watchers in the next event loop iteration. |
|
|
4216 | |
4640 | |
4217 | =head3 COROUTINES |
4641 | =head3 COROUTINES |
4218 | |
4642 | |
4219 | Libev is very accommodating to coroutines ("cooperative threads"): |
4643 | Libev is very accommodating to coroutines ("cooperative threads"): |
4220 | libev fully supports nesting calls to its functions from different |
4644 | libev fully supports nesting calls to its functions from different |
4221 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4645 | coroutines (e.g. you can call C<ev_run> on the same loop from two |
4222 | different coroutines, and switch freely between both coroutines running |
4646 | different coroutines, and switch freely between both coroutines running |
4223 | the loop, as long as you don't confuse yourself). The only exception is |
4647 | the loop, as long as you don't confuse yourself). The only exception is |
4224 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4648 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4225 | |
4649 | |
4226 | Care has been taken to ensure that libev does not keep local state inside |
4650 | Care has been taken to ensure that libev does not keep local state inside |
4227 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4651 | C<ev_run>, and other calls do not usually allow for coroutine switches as |
4228 | they do not call any callbacks. |
4652 | they do not call any callbacks. |
4229 | |
4653 | |
4230 | =head2 COMPILER WARNINGS |
4654 | =head2 COMPILER WARNINGS |
4231 | |
4655 | |
4232 | Depending on your compiler and compiler settings, you might get no or a |
4656 | Depending on your compiler and compiler settings, you might get no or a |
… | |
… | |
4243 | maintainable. |
4667 | maintainable. |
4244 | |
4668 | |
4245 | And of course, some compiler warnings are just plain stupid, or simply |
4669 | And of course, some compiler warnings are just plain stupid, or simply |
4246 | wrong (because they don't actually warn about the condition their message |
4670 | wrong (because they don't actually warn about the condition their message |
4247 | seems to warn about). For example, certain older gcc versions had some |
4671 | seems to warn about). For example, certain older gcc versions had some |
4248 | warnings that resulted an extreme number of false positives. These have |
4672 | warnings that resulted in an extreme number of false positives. These have |
4249 | been fixed, but some people still insist on making code warn-free with |
4673 | been fixed, but some people still insist on making code warn-free with |
4250 | such buggy versions. |
4674 | such buggy versions. |
4251 | |
4675 | |
4252 | While libev is written to generate as few warnings as possible, |
4676 | While libev is written to generate as few warnings as possible, |
4253 | "warn-free" code is not a goal, and it is recommended not to build libev |
4677 | "warn-free" code is not a goal, and it is recommended not to build libev |
… | |
… | |
4289 | I suggest using suppression lists. |
4713 | I suggest using suppression lists. |
4290 | |
4714 | |
4291 | |
4715 | |
4292 | =head1 PORTABILITY NOTES |
4716 | =head1 PORTABILITY NOTES |
4293 | |
4717 | |
|
|
4718 | =head2 GNU/LINUX 32 BIT LIMITATIONS |
|
|
4719 | |
|
|
4720 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
4721 | interfaces but I<disables> them by default. |
|
|
4722 | |
|
|
4723 | That means that libev compiled in the default environment doesn't support |
|
|
4724 | files larger than 2GiB or so, which mainly affects C<ev_stat> watchers. |
|
|
4725 | |
|
|
4726 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
4727 | by enabling the large file API, which makes them incompatible with the |
|
|
4728 | standard libev compiled for their system. |
|
|
4729 | |
|
|
4730 | Likewise, libev cannot enable the large file API itself as this would |
|
|
4731 | suddenly make it incompatible to the default compile time environment, |
|
|
4732 | i.e. all programs not using special compile switches. |
|
|
4733 | |
|
|
4734 | =head2 OS/X AND DARWIN BUGS |
|
|
4735 | |
|
|
4736 | The whole thing is a bug if you ask me - basically any system interface |
|
|
4737 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
4738 | OpenGL drivers. |
|
|
4739 | |
|
|
4740 | =head3 C<kqueue> is buggy |
|
|
4741 | |
|
|
4742 | The kqueue syscall is broken in all known versions - most versions support |
|
|
4743 | only sockets, many support pipes. |
|
|
4744 | |
|
|
4745 | Libev tries to work around this by not using C<kqueue> by default on this |
|
|
4746 | rotten platform, but of course you can still ask for it when creating a |
|
|
4747 | loop - embedding a socket-only kqueue loop into a select-based one is |
|
|
4748 | probably going to work well. |
|
|
4749 | |
|
|
4750 | =head3 C<poll> is buggy |
|
|
4751 | |
|
|
4752 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
|
|
4753 | implementation by something calling C<kqueue> internally around the 10.5.6 |
|
|
4754 | release, so now C<kqueue> I<and> C<poll> are broken. |
|
|
4755 | |
|
|
4756 | Libev tries to work around this by not using C<poll> by default on |
|
|
4757 | this rotten platform, but of course you can still ask for it when creating |
|
|
4758 | a loop. |
|
|
4759 | |
|
|
4760 | =head3 C<select> is buggy |
|
|
4761 | |
|
|
4762 | All that's left is C<select>, and of course Apple found a way to fuck this |
|
|
4763 | one up as well: On OS/X, C<select> actively limits the number of file |
|
|
4764 | descriptors you can pass in to 1024 - your program suddenly crashes when |
|
|
4765 | you use more. |
|
|
4766 | |
|
|
4767 | There is an undocumented "workaround" for this - defining |
|
|
4768 | C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should> |
|
|
4769 | work on OS/X. |
|
|
4770 | |
|
|
4771 | =head2 SOLARIS PROBLEMS AND WORKAROUNDS |
|
|
4772 | |
|
|
4773 | =head3 C<errno> reentrancy |
|
|
4774 | |
|
|
4775 | The default compile environment on Solaris is unfortunately so |
|
|
4776 | thread-unsafe that you can't even use components/libraries compiled |
|
|
4777 | without C<-D_REENTRANT> in a threaded program, which, of course, isn't |
|
|
4778 | defined by default. A valid, if stupid, implementation choice. |
|
|
4779 | |
|
|
4780 | If you want to use libev in threaded environments you have to make sure |
|
|
4781 | it's compiled with C<_REENTRANT> defined. |
|
|
4782 | |
|
|
4783 | =head3 Event port backend |
|
|
4784 | |
|
|
4785 | The scalable event interface for Solaris is called "event |
|
|
4786 | ports". Unfortunately, this mechanism is very buggy in all major |
|
|
4787 | releases. If you run into high CPU usage, your program freezes or you get |
|
|
4788 | a large number of spurious wakeups, make sure you have all the relevant |
|
|
4789 | and latest kernel patches applied. No, I don't know which ones, but there |
|
|
4790 | are multiple ones to apply, and afterwards, event ports actually work |
|
|
4791 | great. |
|
|
4792 | |
|
|
4793 | If you can't get it to work, you can try running the program by setting |
|
|
4794 | the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and |
|
|
4795 | C<select> backends. |
|
|
4796 | |
|
|
4797 | =head2 AIX POLL BUG |
|
|
4798 | |
|
|
4799 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
|
|
4800 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
4801 | compiled in), which normally isn't a big problem as C<select> works fine |
|
|
4802 | with large bitsets on AIX, and AIX is dead anyway. |
|
|
4803 | |
4294 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4804 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
|
|
4805 | |
|
|
4806 | =head3 General issues |
4295 | |
4807 | |
4296 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4808 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4297 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4809 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4298 | model. Libev still offers limited functionality on this platform in |
4810 | model. Libev still offers limited functionality on this platform in |
4299 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4811 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4300 | descriptors. This only applies when using Win32 natively, not when using |
4812 | descriptors. This only applies when using Win32 natively, not when using |
4301 | e.g. cygwin. |
4813 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
4814 | as every compielr comes with a slightly differently broken/incompatible |
|
|
4815 | environment. |
4302 | |
4816 | |
4303 | Lifting these limitations would basically require the full |
4817 | Lifting these limitations would basically require the full |
4304 | re-implementation of the I/O system. If you are into these kinds of |
4818 | re-implementation of the I/O system. If you are into this kind of thing, |
4305 | things, then note that glib does exactly that for you in a very portable |
4819 | then note that glib does exactly that for you in a very portable way (note |
4306 | way (note also that glib is the slowest event library known to man). |
4820 | also that glib is the slowest event library known to man). |
4307 | |
4821 | |
4308 | There is no supported compilation method available on windows except |
4822 | There is no supported compilation method available on windows except |
4309 | embedding it into other applications. |
4823 | embedding it into other applications. |
4310 | |
4824 | |
4311 | Sensible signal handling is officially unsupported by Microsoft - libev |
4825 | Sensible signal handling is officially unsupported by Microsoft - libev |
… | |
… | |
4339 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4853 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4340 | |
4854 | |
4341 | #include "evwrap.h" |
4855 | #include "evwrap.h" |
4342 | #include "ev.c" |
4856 | #include "ev.c" |
4343 | |
4857 | |
4344 | =over 4 |
|
|
4345 | |
|
|
4346 | =item The winsocket select function |
4858 | =head3 The winsocket C<select> function |
4347 | |
4859 | |
4348 | The winsocket C<select> function doesn't follow POSIX in that it |
4860 | The winsocket C<select> function doesn't follow POSIX in that it |
4349 | requires socket I<handles> and not socket I<file descriptors> (it is |
4861 | requires socket I<handles> and not socket I<file descriptors> (it is |
4350 | also extremely buggy). This makes select very inefficient, and also |
4862 | also extremely buggy). This makes select very inefficient, and also |
4351 | requires a mapping from file descriptors to socket handles (the Microsoft |
4863 | requires a mapping from file descriptors to socket handles (the Microsoft |
… | |
… | |
4360 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4872 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4361 | |
4873 | |
4362 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4874 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4363 | complexity in the O(n²) range when using win32. |
4875 | complexity in the O(n²) range when using win32. |
4364 | |
4876 | |
4365 | =item Limited number of file descriptors |
4877 | =head3 Limited number of file descriptors |
4366 | |
4878 | |
4367 | Windows has numerous arbitrary (and low) limits on things. |
4879 | Windows has numerous arbitrary (and low) limits on things. |
4368 | |
4880 | |
4369 | Early versions of winsocket's select only supported waiting for a maximum |
4881 | Early versions of winsocket's select only supported waiting for a maximum |
4370 | of C<64> handles (probably owning to the fact that all windows kernels |
4882 | of C<64> handles (probably owning to the fact that all windows kernels |
… | |
… | |
4385 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4897 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4386 | (depending on windows version and/or the phase of the moon). To get more, |
4898 | (depending on windows version and/or the phase of the moon). To get more, |
4387 | you need to wrap all I/O functions and provide your own fd management, but |
4899 | you need to wrap all I/O functions and provide your own fd management, but |
4388 | the cost of calling select (O(n²)) will likely make this unworkable. |
4900 | the cost of calling select (O(n²)) will likely make this unworkable. |
4389 | |
4901 | |
4390 | =back |
|
|
4391 | |
|
|
4392 | =head2 PORTABILITY REQUIREMENTS |
4902 | =head2 PORTABILITY REQUIREMENTS |
4393 | |
4903 | |
4394 | In addition to a working ISO-C implementation and of course the |
4904 | In addition to a working ISO-C implementation and of course the |
4395 | backend-specific APIs, libev relies on a few additional extensions: |
4905 | backend-specific APIs, libev relies on a few additional extensions: |
4396 | |
4906 | |
… | |
… | |
4402 | Libev assumes not only that all watcher pointers have the same internal |
4912 | Libev assumes not only that all watcher pointers have the same internal |
4403 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
4913 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
4404 | assumes that the same (machine) code can be used to call any watcher |
4914 | assumes that the same (machine) code can be used to call any watcher |
4405 | callback: The watcher callbacks have different type signatures, but libev |
4915 | callback: The watcher callbacks have different type signatures, but libev |
4406 | calls them using an C<ev_watcher *> internally. |
4916 | calls them using an C<ev_watcher *> internally. |
|
|
4917 | |
|
|
4918 | =item pointer accesses must be thread-atomic |
|
|
4919 | |
|
|
4920 | Accessing a pointer value must be atomic, it must both be readable and |
|
|
4921 | writable in one piece - this is the case on all current architectures. |
4407 | |
4922 | |
4408 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
4923 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
4409 | |
4924 | |
4410 | The type C<sig_atomic_t volatile> (or whatever is defined as |
4925 | The type C<sig_atomic_t volatile> (or whatever is defined as |
4411 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
4926 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
… | |
… | |
4434 | watchers. |
4949 | watchers. |
4435 | |
4950 | |
4436 | =item C<double> must hold a time value in seconds with enough accuracy |
4951 | =item C<double> must hold a time value in seconds with enough accuracy |
4437 | |
4952 | |
4438 | The type C<double> is used to represent timestamps. It is required to |
4953 | The type C<double> is used to represent timestamps. It is required to |
4439 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4954 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
4440 | enough for at least into the year 4000. This requirement is fulfilled by |
4955 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
4956 | (the design goal for libev). This requirement is overfulfilled by |
4441 | implementations implementing IEEE 754, which is basically all existing |
4957 | implementations using IEEE 754, which is basically all existing ones. With |
4442 | ones. With IEEE 754 doubles, you get microsecond accuracy until at least |
4958 | IEEE 754 doubles, you get microsecond accuracy until at least 2200. |
4443 | 2200. |
|
|
4444 | |
4959 | |
4445 | =back |
4960 | =back |
4446 | |
4961 | |
4447 | If you know of other additional requirements drop me a note. |
4962 | If you know of other additional requirements drop me a note. |
4448 | |
4963 | |
… | |
… | |
4516 | involves iterating over all running async watchers or all signal numbers. |
5031 | involves iterating over all running async watchers or all signal numbers. |
4517 | |
5032 | |
4518 | =back |
5033 | =back |
4519 | |
5034 | |
4520 | |
5035 | |
|
|
5036 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
|
|
5037 | |
|
|
5038 | The major version 4 introduced some incompatible changes to the API. |
|
|
5039 | |
|
|
5040 | At the moment, the C<ev.h> header file provides compatibility definitions |
|
|
5041 | for all changes, so most programs should still compile. The compatibility |
|
|
5042 | layer might be removed in later versions of libev, so better update to the |
|
|
5043 | new API early than late. |
|
|
5044 | |
|
|
5045 | =over 4 |
|
|
5046 | |
|
|
5047 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
5048 | |
|
|
5049 | The backward compatibility mechanism can be controlled by |
|
|
5050 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
5051 | section. |
|
|
5052 | |
|
|
5053 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
|
|
5054 | |
|
|
5055 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
|
|
5056 | |
|
|
5057 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
5058 | ev_loop_fork (EV_DEFAULT); |
|
|
5059 | |
|
|
5060 | =item function/symbol renames |
|
|
5061 | |
|
|
5062 | A number of functions and symbols have been renamed: |
|
|
5063 | |
|
|
5064 | ev_loop => ev_run |
|
|
5065 | EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
5066 | EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
5067 | |
|
|
5068 | ev_unloop => ev_break |
|
|
5069 | EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
5070 | EVUNLOOP_ONE => EVBREAK_ONE |
|
|
5071 | EVUNLOOP_ALL => EVBREAK_ALL |
|
|
5072 | |
|
|
5073 | EV_TIMEOUT => EV_TIMER |
|
|
5074 | |
|
|
5075 | ev_loop_count => ev_iteration |
|
|
5076 | ev_loop_depth => ev_depth |
|
|
5077 | ev_loop_verify => ev_verify |
|
|
5078 | |
|
|
5079 | Most functions working on C<struct ev_loop> objects don't have an |
|
|
5080 | C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and |
|
|
5081 | associated constants have been renamed to not collide with the C<struct |
|
|
5082 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
|
|
5083 | as all other watcher types. Note that C<ev_loop_fork> is still called |
|
|
5084 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
|
|
5085 | typedef. |
|
|
5086 | |
|
|
5087 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
5088 | |
|
|
5089 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
5090 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
5091 | and work, but the library code will of course be larger. |
|
|
5092 | |
|
|
5093 | =back |
|
|
5094 | |
|
|
5095 | |
4521 | =head1 GLOSSARY |
5096 | =head1 GLOSSARY |
4522 | |
5097 | |
4523 | =over 4 |
5098 | =over 4 |
4524 | |
5099 | |
4525 | =item active |
5100 | =item active |
4526 | |
5101 | |
4527 | A watcher is active as long as it has been started (has been attached to |
5102 | A watcher is active as long as it has been started and not yet stopped. |
4528 | an event loop) but not yet stopped (disassociated from the event loop). |
5103 | See L<WATCHER STATES> for details. |
4529 | |
5104 | |
4530 | =item application |
5105 | =item application |
4531 | |
5106 | |
4532 | In this document, an application is whatever is using libev. |
5107 | In this document, an application is whatever is using libev. |
|
|
5108 | |
|
|
5109 | =item backend |
|
|
5110 | |
|
|
5111 | The part of the code dealing with the operating system interfaces. |
4533 | |
5112 | |
4534 | =item callback |
5113 | =item callback |
4535 | |
5114 | |
4536 | The address of a function that is called when some event has been |
5115 | The address of a function that is called when some event has been |
4537 | detected. Callbacks are being passed the event loop, the watcher that |
5116 | detected. Callbacks are being passed the event loop, the watcher that |
4538 | received the event, and the actual event bitset. |
5117 | received the event, and the actual event bitset. |
4539 | |
5118 | |
4540 | =item callback invocation |
5119 | =item callback/watcher invocation |
4541 | |
5120 | |
4542 | The act of calling the callback associated with a watcher. |
5121 | The act of calling the callback associated with a watcher. |
4543 | |
5122 | |
4544 | =item event |
5123 | =item event |
4545 | |
5124 | |
4546 | A change of state of some external event, such as data now being available |
5125 | A change of state of some external event, such as data now being available |
4547 | for reading on a file descriptor, time having passed or simply not having |
5126 | for reading on a file descriptor, time having passed or simply not having |
4548 | any other events happening anymore. |
5127 | any other events happening anymore. |
4549 | |
5128 | |
4550 | In libev, events are represented as single bits (such as C<EV_READ> or |
5129 | In libev, events are represented as single bits (such as C<EV_READ> or |
4551 | C<EV_TIMEOUT>). |
5130 | C<EV_TIMER>). |
4552 | |
5131 | |
4553 | =item event library |
5132 | =item event library |
4554 | |
5133 | |
4555 | A software package implementing an event model and loop. |
5134 | A software package implementing an event model and loop. |
4556 | |
5135 | |
… | |
… | |
4564 | The model used to describe how an event loop handles and processes |
5143 | The model used to describe how an event loop handles and processes |
4565 | watchers and events. |
5144 | watchers and events. |
4566 | |
5145 | |
4567 | =item pending |
5146 | =item pending |
4568 | |
5147 | |
4569 | A watcher is pending as soon as the corresponding event has been detected, |
5148 | A watcher is pending as soon as the corresponding event has been |
4570 | and stops being pending as soon as the watcher will be invoked or its |
5149 | detected. See L<WATCHER STATES> for details. |
4571 | pending status is explicitly cleared by the application. |
|
|
4572 | |
|
|
4573 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4574 | its pending status. |
|
|
4575 | |
5150 | |
4576 | =item real time |
5151 | =item real time |
4577 | |
5152 | |
4578 | The physical time that is observed. It is apparently strictly monotonic :) |
5153 | The physical time that is observed. It is apparently strictly monotonic :) |
4579 | |
5154 | |
… | |
… | |
4586 | =item watcher |
5161 | =item watcher |
4587 | |
5162 | |
4588 | A data structure that describes interest in certain events. Watchers need |
5163 | A data structure that describes interest in certain events. Watchers need |
4589 | to be started (attached to an event loop) before they can receive events. |
5164 | to be started (attached to an event loop) before they can receive events. |
4590 | |
5165 | |
4591 | =item watcher invocation |
|
|
4592 | |
|
|
4593 | The act of calling the callback associated with a watcher. |
|
|
4594 | |
|
|
4595 | =back |
5166 | =back |
4596 | |
5167 | |
4597 | =head1 AUTHOR |
5168 | =head1 AUTHOR |
4598 | |
5169 | |
4599 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
5170 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
|
|
5171 | Magnusson and Emanuele Giaquinta. |
4600 | |
5172 | |