… | |
… | |
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 |
… | |
… | |
118 | Libev is very configurable. In this manual the default (and most common) |
126 | Libev is very configurable. In this manual the default (and most common) |
119 | configuration will be described, which supports multiple event loops. For |
127 | configuration will be described, which supports multiple event loops. For |
120 | more info about various configuration options please have a look at |
128 | more info about various configuration options please have a look at |
121 | B<EMBED> section in this manual. If libev was configured without support |
129 | B<EMBED> section in this manual. If libev was configured without support |
122 | for multiple event loops, then all functions taking an initial argument of |
130 | for multiple event loops, then all functions taking an initial argument of |
123 | name C<loop> (which is always of type C<ev_loop *>) will not have |
131 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
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)) [NOT REENTRANT] |
235 | |
247 | |
… | |
… | |
289 | ... |
301 | ... |
290 | ev_set_syserr_cb (fatal_error); |
302 | ev_set_syserr_cb (fatal_error); |
291 | |
303 | |
292 | =back |
304 | =back |
293 | |
305 | |
294 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
306 | =head1 FUNCTIONS CONTROLLING EVENT LOOPS |
295 | |
307 | |
296 | An event loop is described by a C<struct ev_loop *> (the C<struct> |
308 | 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> |
309 | I<not> optional in this case unless libev 3 compatibility is disabled, as |
298 | I<function>). |
310 | libev 3 had an C<ev_loop> function colliding with the struct name). |
299 | |
311 | |
300 | The library knows two types of such loops, the I<default> loop, which |
312 | The library knows two types of such loops, the I<default> loop, which |
301 | supports signals and child events, and dynamically created loops which do |
313 | supports child process events, and dynamically created event loops which |
302 | not. |
314 | do not. |
303 | |
315 | |
304 | =over 4 |
316 | =over 4 |
305 | |
317 | |
306 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
318 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
307 | |
319 | |
308 | This will initialise the default event loop if it hasn't been initialised |
320 | This returns the "default" event loop object, which is what you should |
309 | yet and return it. If the default loop could not be initialised, returns |
321 | normally use when you just need "the event loop". Event loop objects and |
310 | false. If it already was initialised it simply returns it (and ignores the |
322 | the C<flags> parameter are described in more detail in the entry for |
311 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
323 | C<ev_loop_new>. |
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324 | |
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325 | If the default loop is already initialised then this function simply |
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326 | returns it (and ignores the flags. If that is troubling you, check |
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327 | C<ev_backend ()> afterwards). Otherwise it will create it with the given |
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328 | flags, which should almost always be C<0>, unless the caller is also the |
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329 | one calling C<ev_run> or otherwise qualifies as "the main program". |
312 | |
330 | |
313 | If you don't know what event loop to use, use the one returned from this |
331 | If you don't know what event loop to use, use the one returned from this |
314 | function. |
332 | function (or via the C<EV_DEFAULT> macro). |
315 | |
333 | |
316 | Note that this function is I<not> thread-safe, so if you want to use it |
334 | Note that this function is I<not> thread-safe, so if you want to use it |
317 | from multiple threads, you have to lock (note also that this is unlikely, |
335 | from multiple threads, you have to employ some kind of mutex (note also |
318 | as loops cannot be shared easily between threads anyway). |
336 | that this case is unlikely, as loops cannot be shared easily between |
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337 | threads anyway). |
319 | |
338 | |
320 | The default loop is the only loop that can handle C<ev_signal> and |
339 | The default loop is the only loop that can handle C<ev_child> watchers, |
321 | C<ev_child> watchers, and to do this, it always registers a handler |
340 | and to do this, it always registers a handler for C<SIGCHLD>. If this is |
322 | for C<SIGCHLD>. If this is a problem for your application you can either |
341 | a problem for your application you can either create a dynamic loop with |
323 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
342 | C<ev_loop_new> which doesn't do that, or you can simply overwrite the |
324 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
343 | C<SIGCHLD> signal handler I<after> calling C<ev_default_init>. |
325 | C<ev_default_init>. |
344 | |
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345 | Example: This is the most typical usage. |
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346 | |
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347 | if (!ev_default_loop (0)) |
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348 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
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349 | |
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350 | Example: Restrict libev to the select and poll backends, and do not allow |
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351 | environment settings to be taken into account: |
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352 | |
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353 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
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354 | |
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355 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
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356 | |
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357 | This will create and initialise a new event loop object. If the loop |
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358 | could not be initialised, returns false. |
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359 | |
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360 | Note that this function I<is> thread-safe, and one common way to use |
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361 | libev with threads is indeed to create one loop per thread, and using the |
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362 | default loop in the "main" or "initial" thread. |
326 | |
363 | |
327 | The flags argument can be used to specify special behaviour or specific |
364 | The flags argument can be used to specify special behaviour or specific |
328 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
365 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
329 | |
366 | |
330 | The following flags are supported: |
367 | The following flags are supported: |
… | |
… | |
345 | useful to try out specific backends to test their performance, or to work |
382 | useful to try out specific backends to test their performance, or to work |
346 | around bugs. |
383 | around bugs. |
347 | |
384 | |
348 | =item C<EVFLAG_FORKCHECK> |
385 | =item C<EVFLAG_FORKCHECK> |
349 | |
386 | |
350 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
387 | 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 |
388 | make libev check for a fork in each iteration by enabling this flag. |
352 | enabling this flag. |
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353 | |
389 | |
354 | This works by calling C<getpid ()> on every iteration of the loop, |
390 | 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 |
391 | 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 |
392 | 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 |
393 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
… | |
… | |
370 | When this flag is specified, then libev will not attempt to use the |
406 | When this flag is specified, then libev will not attempt to use the |
371 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
407 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
372 | testing, this flag can be useful to conserve inotify file descriptors, as |
408 | testing, this flag can be useful to conserve inotify file descriptors, as |
373 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
409 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
374 | |
410 | |
375 | =item C<EVFLAG_NOSIGNALFD> |
411 | =item C<EVFLAG_SIGNALFD> |
376 | |
412 | |
377 | When this flag is specified, then libev will not attempt to use the |
413 | When this flag is specified, then libev will attempt to use the |
378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This is |
414 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API |
379 | probably only useful to work around any bugs in libev. Consequently, this |
415 | delivers signals synchronously, which makes it both faster and might make |
380 | flag might go away once the signalfd functionality is considered stable, |
416 | 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. |
417 | handling with threads, as long as you properly block signals in your |
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418 | threads that are not interested in handling them. |
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419 | |
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420 | Signalfd will not be used by default as this changes your signal mask, and |
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421 | there are a lot of shoddy libraries and programs (glib's threadpool for |
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422 | example) that can't properly initialise their signal masks. |
382 | |
423 | |
383 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
424 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
384 | |
425 | |
385 | This is your standard select(2) backend. Not I<completely> standard, as |
426 | 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, |
427 | libev tries to roll its own fd_set with no limits on the number of fds, |
… | |
… | |
410 | |
451 | |
411 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
452 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
412 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
453 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
413 | |
454 | |
414 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
455 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
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456 | |
|
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457 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
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458 | kernels). |
415 | |
459 | |
416 | For few fds, this backend is a bit little slower than poll and select, |
460 | For few fds, this backend is a bit little slower than poll and select, |
417 | but it scales phenomenally better. While poll and select usually scale |
461 | but it scales phenomenally better. While poll and select usually scale |
418 | like O(total_fds) where n is the total number of fds (or the highest fd), |
462 | like O(total_fds) where n is the total number of fds (or the highest fd), |
419 | epoll scales either O(1) or O(active_fds). |
463 | epoll scales either O(1) or O(active_fds). |
… | |
… | |
431 | of course I<doesn't>, and epoll just loves to report events for totally |
475 | of course I<doesn't>, and epoll just loves to report events for totally |
432 | I<different> file descriptors (even already closed ones, so one cannot |
476 | I<different> file descriptors (even already closed ones, so one cannot |
433 | even remove them from the set) than registered in the set (especially |
477 | even remove them from the set) than registered in the set (especially |
434 | on SMP systems). Libev tries to counter these spurious notifications by |
478 | on SMP systems). Libev tries to counter these spurious notifications by |
435 | employing an additional generation counter and comparing that against the |
479 | employing an additional generation counter and comparing that against the |
436 | events to filter out spurious ones, recreating the set when required. |
480 | events to filter out spurious ones, recreating the set when required. Last |
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481 | not least, it also refuses to work with some file descriptors which work |
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482 | perfectly fine with C<select> (files, many character devices...). |
437 | |
483 | |
438 | While stopping, setting and starting an I/O watcher in the same iteration |
484 | While stopping, setting and starting an I/O watcher in the same iteration |
439 | will result in some caching, there is still a system call per such |
485 | will result in some caching, there is still a system call per such |
440 | incident (because the same I<file descriptor> could point to a different |
486 | incident (because the same I<file descriptor> could point to a different |
441 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
487 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
… | |
… | |
539 | If one or more of the backend flags are or'ed into the flags value, |
585 | If one or more of the backend flags are or'ed into the flags value, |
540 | then only these backends will be tried (in the reverse order as listed |
586 | then only these backends will be tried (in the reverse order as listed |
541 | here). If none are specified, all backends in C<ev_recommended_backends |
587 | here). If none are specified, all backends in C<ev_recommended_backends |
542 | ()> will be tried. |
588 | ()> will be tried. |
543 | |
589 | |
544 | Example: This is the most typical usage. |
|
|
545 | |
|
|
546 | if (!ev_default_loop (0)) |
|
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547 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
548 | |
|
|
549 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
550 | environment settings to be taken into account: |
|
|
551 | |
|
|
552 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
553 | |
|
|
554 | Example: Use whatever libev has to offer, but make sure that kqueue is |
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555 | used if available (warning, breaks stuff, best use only with your own |
|
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556 | private event loop and only if you know the OS supports your types of |
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557 | fds): |
|
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558 | |
|
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559 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
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560 | |
|
|
561 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
|
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562 | |
|
|
563 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
|
|
564 | always distinct from the default loop. Unlike the default loop, it cannot |
|
|
565 | handle signal and child watchers, and attempts to do so will be greeted by |
|
|
566 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
567 | |
|
|
568 | Note that this function I<is> thread-safe, and the recommended way to use |
|
|
569 | libev with threads is indeed to create one loop per thread, and using the |
|
|
570 | default loop in the "main" or "initial" thread. |
|
|
571 | |
|
|
572 | Example: Try to create a event loop that uses epoll and nothing else. |
590 | Example: Try to create a event loop that uses epoll and nothing else. |
573 | |
591 | |
574 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
592 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
575 | if (!epoller) |
593 | if (!epoller) |
576 | fatal ("no epoll found here, maybe it hides under your chair"); |
594 | fatal ("no epoll found here, maybe it hides under your chair"); |
577 | |
595 | |
|
|
596 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
597 | used if available. |
|
|
598 | |
|
|
599 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
600 | |
578 | =item ev_default_destroy () |
601 | =item ev_loop_destroy (loop) |
579 | |
602 | |
580 | Destroys the default loop again (frees all memory and kernel state |
603 | Destroys an event loop object (frees all memory and kernel state |
581 | etc.). None of the active event watchers will be stopped in the normal |
604 | etc.). None of the active event watchers will be stopped in the normal |
582 | sense, so e.g. C<ev_is_active> might still return true. It is your |
605 | sense, so e.g. C<ev_is_active> might still return true. It is your |
583 | responsibility to either stop all watchers cleanly yourself I<before> |
606 | responsibility to either stop all watchers cleanly yourself I<before> |
584 | calling this function, or cope with the fact afterwards (which is usually |
607 | calling this function, or cope with the fact afterwards (which is usually |
585 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
608 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
… | |
… | |
587 | |
610 | |
588 | Note that certain global state, such as signal state (and installed signal |
611 | Note that certain global state, such as signal state (and installed signal |
589 | handlers), will not be freed by this function, and related watchers (such |
612 | handlers), will not be freed by this function, and related watchers (such |
590 | as signal and child watchers) would need to be stopped manually. |
613 | as signal and child watchers) would need to be stopped manually. |
591 | |
614 | |
592 | In general it is not advisable to call this function except in the |
615 | This function is normally used on loop objects allocated by |
593 | rare occasion where you really need to free e.g. the signal handling |
616 | C<ev_loop_new>, but it can also be used on the default loop returned by |
|
|
617 | C<ev_default_loop>, in which case it is not thread-safe. |
|
|
618 | |
|
|
619 | Note that it is not advisable to call this function on the default loop |
|
|
620 | except in the rare occasion where you really need to free it's resources. |
594 | pipe fds. If you need dynamically allocated loops it is better to use |
621 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
595 | C<ev_loop_new> and C<ev_loop_destroy>). |
622 | and C<ev_loop_destroy>. |
596 | |
623 | |
597 | =item ev_loop_destroy (loop) |
624 | =item ev_loop_fork (loop) |
598 | |
625 | |
599 | Like C<ev_default_destroy>, but destroys an event loop created by an |
|
|
600 | earlier call to C<ev_loop_new>. |
|
|
601 | |
|
|
602 | =item ev_default_fork () |
|
|
603 | |
|
|
604 | This function sets a flag that causes subsequent C<ev_loop> iterations |
626 | This function sets a flag that causes subsequent C<ev_run> iterations to |
605 | to reinitialise the kernel state for backends that have one. Despite the |
627 | reinitialise the kernel state for backends that have one. Despite the |
606 | name, you can call it anytime, but it makes most sense after forking, in |
628 | name, you can call it anytime, but it makes most sense after forking, in |
607 | the child process (or both child and parent, but that again makes little |
629 | the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the |
608 | sense). You I<must> call it in the child before using any of the libev |
630 | child before resuming or calling C<ev_run>. |
609 | functions, and it will only take effect at the next C<ev_loop> iteration. |
631 | |
|
|
632 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
|
|
633 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
|
|
634 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
|
|
635 | during fork. |
610 | |
636 | |
611 | On the other hand, you only need to call this function in the child |
637 | On the other hand, you only need to call this function in the child |
612 | process if and only if you want to use the event library in the child. If |
638 | process if and only if you want to use the event loop in the child. If |
613 | you just fork+exec, you don't have to call it at all. |
639 | you just fork+exec or create a new loop in the child, you don't have to |
|
|
640 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
|
|
641 | difference, but libev will usually detect this case on its own and do a |
|
|
642 | costly reset of the backend). |
614 | |
643 | |
615 | The function itself is quite fast and it's usually not a problem to call |
644 | The function itself is quite fast and it's usually not a problem to call |
616 | it just in case after a fork. To make this easy, the function will fit in |
645 | it just in case after a fork. |
617 | quite nicely into a call to C<pthread_atfork>: |
|
|
618 | |
646 | |
|
|
647 | Example: Automate calling C<ev_loop_fork> on the default loop when |
|
|
648 | using pthreads. |
|
|
649 | |
|
|
650 | static void |
|
|
651 | post_fork_child (void) |
|
|
652 | { |
|
|
653 | ev_loop_fork (EV_DEFAULT); |
|
|
654 | } |
|
|
655 | |
|
|
656 | ... |
619 | pthread_atfork (0, 0, ev_default_fork); |
657 | pthread_atfork (0, 0, post_fork_child); |
620 | |
|
|
621 | =item ev_loop_fork (loop) |
|
|
622 | |
|
|
623 | Like C<ev_default_fork>, but acts on an event loop created by |
|
|
624 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
|
|
625 | after fork that you want to re-use in the child, and how you do this is |
|
|
626 | entirely your own problem. |
|
|
627 | |
658 | |
628 | =item int ev_is_default_loop (loop) |
659 | =item int ev_is_default_loop (loop) |
629 | |
660 | |
630 | Returns true when the given loop is, in fact, the default loop, and false |
661 | Returns true when the given loop is, in fact, the default loop, and false |
631 | otherwise. |
662 | otherwise. |
632 | |
663 | |
633 | =item unsigned int ev_loop_count (loop) |
664 | =item unsigned int ev_iteration (loop) |
634 | |
665 | |
635 | Returns the count of loop iterations for the loop, which is identical to |
666 | Returns the current iteration count for the event loop, which is identical |
636 | the number of times libev did poll for new events. It starts at C<0> and |
667 | to the number of times libev did poll for new events. It starts at C<0> |
637 | happily wraps around with enough iterations. |
668 | and happily wraps around with enough iterations. |
638 | |
669 | |
639 | This value can sometimes be useful as a generation counter of sorts (it |
670 | This value can sometimes be useful as a generation counter of sorts (it |
640 | "ticks" the number of loop iterations), as it roughly corresponds with |
671 | "ticks" the number of loop iterations), as it roughly corresponds with |
641 | C<ev_prepare> and C<ev_check> calls. |
672 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
|
|
673 | prepare and check phases. |
642 | |
674 | |
643 | =item unsigned int ev_loop_depth (loop) |
675 | =item unsigned int ev_depth (loop) |
644 | |
676 | |
645 | Returns the number of times C<ev_loop> was entered minus the number of |
677 | Returns the number of times C<ev_run> was entered minus the number of |
646 | times C<ev_loop> was exited, in other words, the recursion depth. |
678 | times C<ev_run> was exited, in other words, the recursion depth. |
647 | |
679 | |
648 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
680 | Outside C<ev_run>, this number is zero. In a callback, this number is |
649 | C<1>, unless C<ev_loop> was invoked recursively (or from another thread), |
681 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
650 | in which case it is higher. |
682 | in which case it is higher. |
651 | |
683 | |
652 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
684 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread |
653 | etc.), doesn't count as exit. |
685 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
|
|
686 | ungentleman-like behaviour unless it's really convenient. |
654 | |
687 | |
655 | =item unsigned int ev_backend (loop) |
688 | =item unsigned int ev_backend (loop) |
656 | |
689 | |
657 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
690 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
658 | use. |
691 | use. |
… | |
… | |
667 | |
700 | |
668 | =item ev_now_update (loop) |
701 | =item ev_now_update (loop) |
669 | |
702 | |
670 | Establishes the current time by querying the kernel, updating the time |
703 | Establishes the current time by querying the kernel, updating the time |
671 | returned by C<ev_now ()> in the progress. This is a costly operation and |
704 | returned by C<ev_now ()> in the progress. This is a costly operation and |
672 | is usually done automatically within C<ev_loop ()>. |
705 | is usually done automatically within C<ev_run ()>. |
673 | |
706 | |
674 | This function is rarely useful, but when some event callback runs for a |
707 | This function is rarely useful, but when some event callback runs for a |
675 | very long time without entering the event loop, updating libev's idea of |
708 | very long time without entering the event loop, updating libev's idea of |
676 | the current time is a good idea. |
709 | the current time is a good idea. |
677 | |
710 | |
… | |
… | |
679 | |
712 | |
680 | =item ev_suspend (loop) |
713 | =item ev_suspend (loop) |
681 | |
714 | |
682 | =item ev_resume (loop) |
715 | =item ev_resume (loop) |
683 | |
716 | |
684 | These two functions suspend and resume a loop, for use when the loop is |
717 | These two functions suspend and resume an event loop, for use when the |
685 | not used for a while and timeouts should not be processed. |
718 | loop is not used for a while and timeouts should not be processed. |
686 | |
719 | |
687 | A typical use case would be an interactive program such as a game: When |
720 | A typical use case would be an interactive program such as a game: When |
688 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
721 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
689 | would be best to handle timeouts as if no time had actually passed while |
722 | would be best to handle timeouts as if no time had actually passed while |
690 | the program was suspended. This can be achieved by calling C<ev_suspend> |
723 | the program was suspended. This can be achieved by calling C<ev_suspend> |
… | |
… | |
692 | C<ev_resume> directly afterwards to resume timer processing. |
725 | C<ev_resume> directly afterwards to resume timer processing. |
693 | |
726 | |
694 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
727 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
695 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
728 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
696 | will be rescheduled (that is, they will lose any events that would have |
729 | will be rescheduled (that is, they will lose any events that would have |
697 | occured while suspended). |
730 | occurred while suspended). |
698 | |
731 | |
699 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
732 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
700 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
733 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
701 | without a previous call to C<ev_suspend>. |
734 | without a previous call to C<ev_suspend>. |
702 | |
735 | |
703 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
736 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
704 | event loop time (see C<ev_now_update>). |
737 | event loop time (see C<ev_now_update>). |
705 | |
738 | |
706 | =item ev_loop (loop, int flags) |
739 | =item ev_run (loop, int flags) |
707 | |
740 | |
708 | Finally, this is it, the event handler. This function usually is called |
741 | Finally, this is it, the event handler. This function usually is called |
709 | after you initialised all your watchers and you want to start handling |
742 | after you have initialised all your watchers and you want to start |
710 | events. |
743 | handling events. It will ask the operating system for any new events, call |
|
|
744 | the watcher callbacks, an then repeat the whole process indefinitely: This |
|
|
745 | is why event loops are called I<loops>. |
711 | |
746 | |
712 | If the flags argument is specified as C<0>, it will not return until |
747 | If the flags argument is specified as C<0>, it will keep handling events |
713 | either no event watchers are active anymore or C<ev_unloop> was called. |
748 | until either no event watchers are active anymore or C<ev_break> was |
|
|
749 | called. |
714 | |
750 | |
715 | Please note that an explicit C<ev_unloop> is usually better than |
751 | Please note that an explicit C<ev_break> is usually better than |
716 | relying on all watchers to be stopped when deciding when a program has |
752 | relying on all watchers to be stopped when deciding when a program has |
717 | finished (especially in interactive programs), but having a program |
753 | finished (especially in interactive programs), but having a program |
718 | that automatically loops as long as it has to and no longer by virtue |
754 | that automatically loops as long as it has to and no longer by virtue |
719 | of relying on its watchers stopping correctly, that is truly a thing of |
755 | of relying on its watchers stopping correctly, that is truly a thing of |
720 | beauty. |
756 | beauty. |
721 | |
757 | |
722 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
758 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
723 | those events and any already outstanding ones, but will not block your |
759 | those events and any already outstanding ones, but will not wait and |
724 | process in case there are no events and will return after one iteration of |
760 | block your process in case there are no events and will return after one |
725 | the loop. |
761 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
762 | events while doing lengthy calculations, to keep the program responsive. |
726 | |
763 | |
727 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
764 | A flags value of C<EVRUN_ONCE> will look for new events (waiting if |
728 | necessary) and will handle those and any already outstanding ones. It |
765 | necessary) and will handle those and any already outstanding ones. It |
729 | will block your process until at least one new event arrives (which could |
766 | will block your process until at least one new event arrives (which could |
730 | be an event internal to libev itself, so there is no guarantee that a |
767 | be an event internal to libev itself, so there is no guarantee that a |
731 | user-registered callback will be called), and will return after one |
768 | user-registered callback will be called), and will return after one |
732 | iteration of the loop. |
769 | iteration of the loop. |
733 | |
770 | |
734 | This is useful if you are waiting for some external event in conjunction |
771 | This is useful if you are waiting for some external event in conjunction |
735 | with something not expressible using other libev watchers (i.e. "roll your |
772 | with something not expressible using other libev watchers (i.e. "roll your |
736 | own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
773 | own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
737 | usually a better approach for this kind of thing. |
774 | usually a better approach for this kind of thing. |
738 | |
775 | |
739 | Here are the gory details of what C<ev_loop> does: |
776 | Here are the gory details of what C<ev_run> does: |
740 | |
777 | |
|
|
778 | - Increment loop depth. |
|
|
779 | - Reset the ev_break status. |
741 | - Before the first iteration, call any pending watchers. |
780 | - Before the first iteration, call any pending watchers. |
|
|
781 | LOOP: |
742 | * If EVFLAG_FORKCHECK was used, check for a fork. |
782 | - If EVFLAG_FORKCHECK was used, check for a fork. |
743 | - If a fork was detected (by any means), queue and call all fork watchers. |
783 | - If a fork was detected (by any means), queue and call all fork watchers. |
744 | - Queue and call all prepare watchers. |
784 | - Queue and call all prepare watchers. |
|
|
785 | - If ev_break was called, goto FINISH. |
745 | - If we have been forked, detach and recreate the kernel state |
786 | - If we have been forked, detach and recreate the kernel state |
746 | as to not disturb the other process. |
787 | as to not disturb the other process. |
747 | - Update the kernel state with all outstanding changes. |
788 | - Update the kernel state with all outstanding changes. |
748 | - Update the "event loop time" (ev_now ()). |
789 | - Update the "event loop time" (ev_now ()). |
749 | - Calculate for how long to sleep or block, if at all |
790 | - Calculate for how long to sleep or block, if at all |
750 | (active idle watchers, EVLOOP_NONBLOCK or not having |
791 | (active idle watchers, EVRUN_NOWAIT or not having |
751 | any active watchers at all will result in not sleeping). |
792 | any active watchers at all will result in not sleeping). |
752 | - Sleep if the I/O and timer collect interval say so. |
793 | - Sleep if the I/O and timer collect interval say so. |
|
|
794 | - Increment loop iteration counter. |
753 | - Block the process, waiting for any events. |
795 | - Block the process, waiting for any events. |
754 | - Queue all outstanding I/O (fd) events. |
796 | - Queue all outstanding I/O (fd) events. |
755 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
797 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
756 | - Queue all expired timers. |
798 | - Queue all expired timers. |
757 | - Queue all expired periodics. |
799 | - Queue all expired periodics. |
758 | - Unless any events are pending now, queue all idle watchers. |
800 | - Queue all idle watchers with priority higher than that of pending events. |
759 | - Queue all check watchers. |
801 | - Queue all check watchers. |
760 | - Call all queued watchers in reverse order (i.e. check watchers first). |
802 | - Call all queued watchers in reverse order (i.e. check watchers first). |
761 | Signals and child watchers are implemented as I/O watchers, and will |
803 | Signals and child watchers are implemented as I/O watchers, and will |
762 | be handled here by queueing them when their watcher gets executed. |
804 | be handled here by queueing them when their watcher gets executed. |
763 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
805 | - If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
764 | were used, or there are no active watchers, return, otherwise |
806 | were used, or there are no active watchers, goto FINISH, otherwise |
765 | continue with step *. |
807 | continue with step LOOP. |
|
|
808 | FINISH: |
|
|
809 | - Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
810 | - Decrement the loop depth. |
|
|
811 | - Return. |
766 | |
812 | |
767 | Example: Queue some jobs and then loop until no events are outstanding |
813 | Example: Queue some jobs and then loop until no events are outstanding |
768 | anymore. |
814 | anymore. |
769 | |
815 | |
770 | ... queue jobs here, make sure they register event watchers as long |
816 | ... queue jobs here, make sure they register event watchers as long |
771 | ... as they still have work to do (even an idle watcher will do..) |
817 | ... as they still have work to do (even an idle watcher will do..) |
772 | ev_loop (my_loop, 0); |
818 | ev_run (my_loop, 0); |
773 | ... jobs done or somebody called unloop. yeah! |
819 | ... jobs done or somebody called unloop. yeah! |
774 | |
820 | |
775 | =item ev_unloop (loop, how) |
821 | =item ev_break (loop, how) |
776 | |
822 | |
777 | Can be used to make a call to C<ev_loop> return early (but only after it |
823 | Can be used to make a call to C<ev_run> return early (but only after it |
778 | has processed all outstanding events). The C<how> argument must be either |
824 | has processed all outstanding events). The C<how> argument must be either |
779 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
825 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
780 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
826 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
781 | |
827 | |
782 | This "unloop state" will be cleared when entering C<ev_loop> again. |
828 | This "unloop state" will be cleared when entering C<ev_run> again. |
783 | |
829 | |
784 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
830 | It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO## |
785 | |
831 | |
786 | =item ev_ref (loop) |
832 | =item ev_ref (loop) |
787 | |
833 | |
788 | =item ev_unref (loop) |
834 | =item ev_unref (loop) |
789 | |
835 | |
790 | Ref/unref can be used to add or remove a reference count on the event |
836 | Ref/unref can be used to add or remove a reference count on the event |
791 | loop: Every watcher keeps one reference, and as long as the reference |
837 | loop: Every watcher keeps one reference, and as long as the reference |
792 | count is nonzero, C<ev_loop> will not return on its own. |
838 | count is nonzero, C<ev_run> will not return on its own. |
793 | |
839 | |
794 | If you have a watcher you never unregister that should not keep C<ev_loop> |
840 | This is useful when you have a watcher that you never intend to |
795 | from returning, call ev_unref() after starting, and ev_ref() before |
841 | unregister, but that nevertheless should not keep C<ev_run> from |
|
|
842 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
796 | stopping it. |
843 | before stopping it. |
797 | |
844 | |
798 | As an example, libev itself uses this for its internal signal pipe: It |
845 | As an example, libev itself uses this for its internal signal pipe: It |
799 | is not visible to the libev user and should not keep C<ev_loop> from |
846 | is not visible to the libev user and should not keep C<ev_run> from |
800 | exiting if no event watchers registered by it are active. It is also an |
847 | exiting if no event watchers registered by it are active. It is also an |
801 | excellent way to do this for generic recurring timers or from within |
848 | excellent way to do this for generic recurring timers or from within |
802 | third-party libraries. Just remember to I<unref after start> and I<ref |
849 | third-party libraries. Just remember to I<unref after start> and I<ref |
803 | before stop> (but only if the watcher wasn't active before, or was active |
850 | before stop> (but only if the watcher wasn't active before, or was active |
804 | before, respectively. Note also that libev might stop watchers itself |
851 | before, respectively. Note also that libev might stop watchers itself |
805 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
852 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
806 | in the callback). |
853 | in the callback). |
807 | |
854 | |
808 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
855 | Example: Create a signal watcher, but keep it from keeping C<ev_run> |
809 | running when nothing else is active. |
856 | running when nothing else is active. |
810 | |
857 | |
811 | ev_signal exitsig; |
858 | ev_signal exitsig; |
812 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
859 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
813 | ev_signal_start (loop, &exitsig); |
860 | ev_signal_start (loop, &exitsig); |
… | |
… | |
858 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
905 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
859 | as this approaches the timing granularity of most systems. Note that if |
906 | as this approaches the timing granularity of most systems. Note that if |
860 | you do transactions with the outside world and you can't increase the |
907 | you do transactions with the outside world and you can't increase the |
861 | parallelity, then this setting will limit your transaction rate (if you |
908 | parallelity, then this setting will limit your transaction rate (if you |
862 | need to poll once per transaction and the I/O collect interval is 0.01, |
909 | need to poll once per transaction and the I/O collect interval is 0.01, |
863 | then you can't do more than 100 transations per second). |
910 | then you can't do more than 100 transactions per second). |
864 | |
911 | |
865 | Setting the I<timeout collect interval> can improve the opportunity for |
912 | Setting the I<timeout collect interval> can improve the opportunity for |
866 | saving power, as the program will "bundle" timer callback invocations that |
913 | saving power, as the program will "bundle" timer callback invocations that |
867 | are "near" in time together, by delaying some, thus reducing the number of |
914 | are "near" in time together, by delaying some, thus reducing the number of |
868 | times the process sleeps and wakes up again. Another useful technique to |
915 | times the process sleeps and wakes up again. Another useful technique to |
… | |
… | |
876 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
923 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
877 | |
924 | |
878 | =item ev_invoke_pending (loop) |
925 | =item ev_invoke_pending (loop) |
879 | |
926 | |
880 | This call will simply invoke all pending watchers while resetting their |
927 | This call will simply invoke all pending watchers while resetting their |
881 | pending state. Normally, C<ev_loop> does this automatically when required, |
928 | pending state. Normally, C<ev_run> does this automatically when required, |
882 | but when overriding the invoke callback this call comes handy. |
929 | but when overriding the invoke callback this call comes handy. This |
|
|
930 | function can be invoked from a watcher - this can be useful for example |
|
|
931 | when you want to do some lengthy calculation and want to pass further |
|
|
932 | event handling to another thread (you still have to make sure only one |
|
|
933 | thread executes within C<ev_invoke_pending> or C<ev_run> of course). |
883 | |
934 | |
884 | =item int ev_pending_count (loop) |
935 | =item int ev_pending_count (loop) |
885 | |
936 | |
886 | Returns the number of pending watchers - zero indicates that no watchers |
937 | Returns the number of pending watchers - zero indicates that no watchers |
887 | are pending. |
938 | are pending. |
888 | |
939 | |
889 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
940 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
890 | |
941 | |
891 | This overrides the invoke pending functionality of the loop: Instead of |
942 | This overrides the invoke pending functionality of the loop: Instead of |
892 | invoking all pending watchers when there are any, C<ev_loop> will call |
943 | invoking all pending watchers when there are any, C<ev_run> will call |
893 | this callback instead. This is useful, for example, when you want to |
944 | this callback instead. This is useful, for example, when you want to |
894 | invoke the actual watchers inside another context (another thread etc.). |
945 | invoke the actual watchers inside another context (another thread etc.). |
895 | |
946 | |
896 | If you want to reset the callback, use C<ev_invoke_pending> as new |
947 | If you want to reset the callback, use C<ev_invoke_pending> as new |
897 | callback. |
948 | callback. |
… | |
… | |
900 | |
951 | |
901 | Sometimes you want to share the same loop between multiple threads. This |
952 | Sometimes you want to share the same loop between multiple threads. This |
902 | can be done relatively simply by putting mutex_lock/unlock calls around |
953 | can be done relatively simply by putting mutex_lock/unlock calls around |
903 | each call to a libev function. |
954 | each call to a libev function. |
904 | |
955 | |
905 | However, C<ev_loop> can run an indefinite time, so it is not feasible to |
956 | However, C<ev_run> can run an indefinite time, so it is not feasible |
906 | wait for it to return. One way around this is to wake up the loop via |
957 | to wait for it to return. One way around this is to wake up the event |
907 | C<ev_unloop> and C<av_async_send>, another way is to set these I<release> |
958 | loop via C<ev_break> and C<av_async_send>, another way is to set these |
908 | and I<acquire> callbacks on the loop. |
959 | I<release> and I<acquire> callbacks on the loop. |
909 | |
960 | |
910 | When set, then C<release> will be called just before the thread is |
961 | When set, then C<release> will be called just before the thread is |
911 | suspended waiting for new events, and C<acquire> is called just |
962 | suspended waiting for new events, and C<acquire> is called just |
912 | afterwards. |
963 | afterwards. |
913 | |
964 | |
… | |
… | |
916 | |
967 | |
917 | While event loop modifications are allowed between invocations of |
968 | While event loop modifications are allowed between invocations of |
918 | C<release> and C<acquire> (that's their only purpose after all), no |
969 | C<release> and C<acquire> (that's their only purpose after all), no |
919 | modifications done will affect the event loop, i.e. adding watchers will |
970 | modifications done will affect the event loop, i.e. adding watchers will |
920 | have no effect on the set of file descriptors being watched, or the time |
971 | have no effect on the set of file descriptors being watched, or the time |
921 | waited. USe an C<ev_async> watcher to wake up C<ev_loop> when you want it |
972 | waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it |
922 | to take note of any changes you made. |
973 | to take note of any changes you made. |
923 | |
974 | |
924 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
975 | In theory, threads executing C<ev_run> will be async-cancel safe between |
925 | invocations of C<release> and C<acquire>. |
976 | invocations of C<release> and C<acquire>. |
926 | |
977 | |
927 | See also the locking example in the C<THREADS> section later in this |
978 | See also the locking example in the C<THREADS> section later in this |
928 | document. |
979 | document. |
929 | |
980 | |
… | |
… | |
938 | These two functions can be used to associate arbitrary data with a loop, |
989 | These two functions can be used to associate arbitrary data with a loop, |
939 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
990 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
940 | C<acquire> callbacks described above, but of course can be (ab-)used for |
991 | C<acquire> callbacks described above, but of course can be (ab-)used for |
941 | any other purpose as well. |
992 | any other purpose as well. |
942 | |
993 | |
943 | =item ev_loop_verify (loop) |
994 | =item ev_verify (loop) |
944 | |
995 | |
945 | This function only does something when C<EV_VERIFY> support has been |
996 | This function only does something when C<EV_VERIFY> support has been |
946 | compiled in, which is the default for non-minimal builds. It tries to go |
997 | compiled in, which is the default for non-minimal builds. It tries to go |
947 | through all internal structures and checks them for validity. If anything |
998 | through all internal structures and checks them for validity. If anything |
948 | is found to be inconsistent, it will print an error message to standard |
999 | is found to be inconsistent, it will print an error message to standard |
… | |
… | |
959 | |
1010 | |
960 | In the following description, uppercase C<TYPE> in names stands for the |
1011 | In the following description, uppercase C<TYPE> in names stands for the |
961 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
1012 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
962 | watchers and C<ev_io_start> for I/O watchers. |
1013 | watchers and C<ev_io_start> for I/O watchers. |
963 | |
1014 | |
964 | A watcher is a structure that you create and register to record your |
1015 | A watcher is an opaque structure that you allocate and register to record |
965 | interest in some event. For instance, if you want to wait for STDIN to |
1016 | your interest in some event. To make a concrete example, imagine you want |
966 | become readable, you would create an C<ev_io> watcher for that: |
1017 | to wait for STDIN to become readable, you would create an C<ev_io> watcher |
|
|
1018 | for that: |
967 | |
1019 | |
968 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
1020 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
969 | { |
1021 | { |
970 | ev_io_stop (w); |
1022 | ev_io_stop (w); |
971 | ev_unloop (loop, EVUNLOOP_ALL); |
1023 | ev_break (loop, EVBREAK_ALL); |
972 | } |
1024 | } |
973 | |
1025 | |
974 | struct ev_loop *loop = ev_default_loop (0); |
1026 | struct ev_loop *loop = ev_default_loop (0); |
975 | |
1027 | |
976 | ev_io stdin_watcher; |
1028 | ev_io stdin_watcher; |
977 | |
1029 | |
978 | ev_init (&stdin_watcher, my_cb); |
1030 | ev_init (&stdin_watcher, my_cb); |
979 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1031 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
980 | ev_io_start (loop, &stdin_watcher); |
1032 | ev_io_start (loop, &stdin_watcher); |
981 | |
1033 | |
982 | ev_loop (loop, 0); |
1034 | ev_run (loop, 0); |
983 | |
1035 | |
984 | As you can see, you are responsible for allocating the memory for your |
1036 | As you can see, you are responsible for allocating the memory for your |
985 | watcher structures (and it is I<usually> a bad idea to do this on the |
1037 | watcher structures (and it is I<usually> a bad idea to do this on the |
986 | stack). |
1038 | stack). |
987 | |
1039 | |
988 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
1040 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
989 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
1041 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
990 | |
1042 | |
991 | Each watcher structure must be initialised by a call to C<ev_init |
1043 | Each watcher structure must be initialised by a call to C<ev_init (watcher |
992 | (watcher *, callback)>, which expects a callback to be provided. This |
1044 | *, callback)>, which expects a callback to be provided. This callback is |
993 | callback gets invoked each time the event occurs (or, in the case of I/O |
1045 | invoked each time the event occurs (or, in the case of I/O watchers, each |
994 | watchers, each time the event loop detects that the file descriptor given |
1046 | time the event loop detects that the file descriptor given is readable |
995 | is readable and/or writable). |
1047 | and/or writable). |
996 | |
1048 | |
997 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
1049 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
998 | macro to configure it, with arguments specific to the watcher type. There |
1050 | macro to configure it, with arguments specific to the watcher type. There |
999 | is also a macro to combine initialisation and setting in one call: C<< |
1051 | is also a macro to combine initialisation and setting in one call: C<< |
1000 | ev_TYPE_init (watcher *, callback, ...) >>. |
1052 | ev_TYPE_init (watcher *, callback, ...) >>. |
… | |
… | |
1023 | =item C<EV_WRITE> |
1075 | =item C<EV_WRITE> |
1024 | |
1076 | |
1025 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1077 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1026 | writable. |
1078 | writable. |
1027 | |
1079 | |
1028 | =item C<EV_TIMEOUT> |
1080 | =item C<EV_TIMER> |
1029 | |
1081 | |
1030 | The C<ev_timer> watcher has timed out. |
1082 | The C<ev_timer> watcher has timed out. |
1031 | |
1083 | |
1032 | =item C<EV_PERIODIC> |
1084 | =item C<EV_PERIODIC> |
1033 | |
1085 | |
… | |
… | |
1051 | |
1103 | |
1052 | =item C<EV_PREPARE> |
1104 | =item C<EV_PREPARE> |
1053 | |
1105 | |
1054 | =item C<EV_CHECK> |
1106 | =item C<EV_CHECK> |
1055 | |
1107 | |
1056 | All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts |
1108 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
1057 | to gather new events, and all C<ev_check> watchers are invoked just after |
1109 | to gather new events, and all C<ev_check> watchers are invoked just after |
1058 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
1110 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
1059 | received events. Callbacks of both watcher types can start and stop as |
1111 | received events. Callbacks of both watcher types can start and stop as |
1060 | many watchers as they want, and all of them will be taken into account |
1112 | many watchers as they want, and all of them will be taken into account |
1061 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1113 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1062 | C<ev_loop> from blocking). |
1114 | C<ev_run> from blocking). |
1063 | |
1115 | |
1064 | =item C<EV_EMBED> |
1116 | =item C<EV_EMBED> |
1065 | |
1117 | |
1066 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1118 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1067 | |
1119 | |
1068 | =item C<EV_FORK> |
1120 | =item C<EV_FORK> |
1069 | |
1121 | |
1070 | The event loop has been resumed in the child process after fork (see |
1122 | The event loop has been resumed in the child process after fork (see |
1071 | C<ev_fork>). |
1123 | C<ev_fork>). |
|
|
1124 | |
|
|
1125 | =item C<EV_CLEANUP> |
|
|
1126 | |
|
|
1127 | The event loop is about to be destroyed (see C<ev_cleanup>). |
1072 | |
1128 | |
1073 | =item C<EV_ASYNC> |
1129 | =item C<EV_ASYNC> |
1074 | |
1130 | |
1075 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1131 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1076 | |
1132 | |
… | |
… | |
1123 | |
1179 | |
1124 | ev_io w; |
1180 | ev_io w; |
1125 | ev_init (&w, my_cb); |
1181 | ev_init (&w, my_cb); |
1126 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1182 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1127 | |
1183 | |
1128 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
1184 | =item C<ev_TYPE_set> (ev_TYPE *watcher, [args]) |
1129 | |
1185 | |
1130 | This macro initialises the type-specific parts of a watcher. You need to |
1186 | This macro initialises the type-specific parts of a watcher. You need to |
1131 | call C<ev_init> at least once before you call this macro, but you can |
1187 | call C<ev_init> at least once before you call this macro, but you can |
1132 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1188 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1133 | macro on a watcher that is active (it can be pending, however, which is a |
1189 | macro on a watcher that is active (it can be pending, however, which is a |
… | |
… | |
1146 | |
1202 | |
1147 | Example: Initialise and set an C<ev_io> watcher in one step. |
1203 | Example: Initialise and set an C<ev_io> watcher in one step. |
1148 | |
1204 | |
1149 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1205 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1150 | |
1206 | |
1151 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
1207 | =item C<ev_TYPE_start> (loop, ev_TYPE *watcher) |
1152 | |
1208 | |
1153 | Starts (activates) the given watcher. Only active watchers will receive |
1209 | Starts (activates) the given watcher. Only active watchers will receive |
1154 | events. If the watcher is already active nothing will happen. |
1210 | events. If the watcher is already active nothing will happen. |
1155 | |
1211 | |
1156 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1212 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1157 | whole section. |
1213 | whole section. |
1158 | |
1214 | |
1159 | ev_io_start (EV_DEFAULT_UC, &w); |
1215 | ev_io_start (EV_DEFAULT_UC, &w); |
1160 | |
1216 | |
1161 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1217 | =item C<ev_TYPE_stop> (loop, ev_TYPE *watcher) |
1162 | |
1218 | |
1163 | Stops the given watcher if active, and clears the pending status (whether |
1219 | Stops the given watcher if active, and clears the pending status (whether |
1164 | the watcher was active or not). |
1220 | the watcher was active or not). |
1165 | |
1221 | |
1166 | It is possible that stopped watchers are pending - for example, |
1222 | It is possible that stopped watchers are pending - for example, |
… | |
… | |
1191 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1247 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1192 | |
1248 | |
1193 | Change the callback. You can change the callback at virtually any time |
1249 | Change the callback. You can change the callback at virtually any time |
1194 | (modulo threads). |
1250 | (modulo threads). |
1195 | |
1251 | |
1196 | =item ev_set_priority (ev_TYPE *watcher, priority) |
1252 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1197 | |
1253 | |
1198 | =item int ev_priority (ev_TYPE *watcher) |
1254 | =item int ev_priority (ev_TYPE *watcher) |
1199 | |
1255 | |
1200 | Set and query the priority of the watcher. The priority is a small |
1256 | Set and query the priority of the watcher. The priority is a small |
1201 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1257 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
… | |
… | |
1233 | watcher isn't pending it does nothing and returns C<0>. |
1289 | watcher isn't pending it does nothing and returns C<0>. |
1234 | |
1290 | |
1235 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1291 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1236 | callback to be invoked, which can be accomplished with this function. |
1292 | callback to be invoked, which can be accomplished with this function. |
1237 | |
1293 | |
|
|
1294 | =item ev_feed_event (loop, ev_TYPE *watcher, int revents) |
|
|
1295 | |
|
|
1296 | Feeds the given event set into the event loop, as if the specified event |
|
|
1297 | had happened for the specified watcher (which must be a pointer to an |
|
|
1298 | initialised but not necessarily started event watcher). Obviously you must |
|
|
1299 | not free the watcher as long as it has pending events. |
|
|
1300 | |
|
|
1301 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1302 | C<ev_clear_pending> will clear the pending event, even if the watcher was |
|
|
1303 | not started in the first place. |
|
|
1304 | |
|
|
1305 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
|
|
1306 | functions that do not need a watcher. |
|
|
1307 | |
1238 | =back |
1308 | =back |
1239 | |
|
|
1240 | |
1309 | |
1241 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1310 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1242 | |
1311 | |
1243 | Each watcher has, by default, a member C<void *data> that you can change |
1312 | Each watcher has, by default, a member C<void *data> that you can change |
1244 | and read at any time: libev will completely ignore it. This can be used |
1313 | and read at any time: libev will completely ignore it. This can be used |
… | |
… | |
1300 | t2_cb (EV_P_ ev_timer *w, int revents) |
1369 | t2_cb (EV_P_ ev_timer *w, int revents) |
1301 | { |
1370 | { |
1302 | struct my_biggy big = (struct my_biggy *) |
1371 | struct my_biggy big = (struct my_biggy *) |
1303 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1372 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1304 | } |
1373 | } |
|
|
1374 | |
|
|
1375 | =head2 WATCHER STATES |
|
|
1376 | |
|
|
1377 | There are various watcher states mentioned throughout this manual - |
|
|
1378 | active, pending and so on. In this section these states and the rules to |
|
|
1379 | transition between them will be described in more detail - and while these |
|
|
1380 | rules might look complicated, they usually do "the right thing". |
|
|
1381 | |
|
|
1382 | =over 4 |
|
|
1383 | |
|
|
1384 | =item initialiased |
|
|
1385 | |
|
|
1386 | Before a watcher can be registered with the event looop it has to be |
|
|
1387 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1388 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
|
|
1389 | |
|
|
1390 | In this state it is simply some block of memory that is suitable for use |
|
|
1391 | in an event loop. It can be moved around, freed, reused etc. at will. |
|
|
1392 | |
|
|
1393 | =item started/running/active |
|
|
1394 | |
|
|
1395 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
|
|
1396 | property of the event loop, and is actively waiting for events. While in |
|
|
1397 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1398 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1399 | and call libev functions on it that are documented to work on active watchers. |
|
|
1400 | |
|
|
1401 | =item pending |
|
|
1402 | |
|
|
1403 | If a watcher is active and libev determines that an event it is interested |
|
|
1404 | in has occurred (such as a timer expiring), it will become pending. It will |
|
|
1405 | stay in this pending state until either it is stopped or its callback is |
|
|
1406 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1407 | callback. |
|
|
1408 | |
|
|
1409 | The watcher might or might not be active while it is pending (for example, |
|
|
1410 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1411 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1412 | but it is still property of the event loop at this time, so cannot be |
|
|
1413 | moved, freed or reused. And if it is active the rules described in the |
|
|
1414 | previous item still apply. |
|
|
1415 | |
|
|
1416 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1417 | via C<ev_feed_event>), in which case it becomes pending without being |
|
|
1418 | active. |
|
|
1419 | |
|
|
1420 | =item stopped |
|
|
1421 | |
|
|
1422 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1423 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
|
|
1424 | latter will clear any pending state the watcher might be in, regardless |
|
|
1425 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1426 | freeing it is often a good idea. |
|
|
1427 | |
|
|
1428 | While stopped (and not pending) the watcher is essentially in the |
|
|
1429 | initialised state, that is it can be reused, moved, modified in any way |
|
|
1430 | you wish. |
|
|
1431 | |
|
|
1432 | =back |
1305 | |
1433 | |
1306 | =head2 WATCHER PRIORITY MODELS |
1434 | =head2 WATCHER PRIORITY MODELS |
1307 | |
1435 | |
1308 | Many event loops support I<watcher priorities>, which are usually small |
1436 | Many event loops support I<watcher priorities>, which are usually small |
1309 | integers that influence the ordering of event callback invocation |
1437 | integers that influence the ordering of event callback invocation |
… | |
… | |
1352 | |
1480 | |
1353 | For example, to emulate how many other event libraries handle priorities, |
1481 | For example, to emulate how many other event libraries handle priorities, |
1354 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1482 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1355 | the normal watcher callback, you just start the idle watcher. The real |
1483 | the normal watcher callback, you just start the idle watcher. The real |
1356 | processing is done in the idle watcher callback. This causes libev to |
1484 | processing is done in the idle watcher callback. This causes libev to |
1357 | continously poll and process kernel event data for the watcher, but when |
1485 | continuously poll and process kernel event data for the watcher, but when |
1358 | the lock-out case is known to be rare (which in turn is rare :), this is |
1486 | the lock-out case is known to be rare (which in turn is rare :), this is |
1359 | workable. |
1487 | workable. |
1360 | |
1488 | |
1361 | Usually, however, the lock-out model implemented that way will perform |
1489 | Usually, however, the lock-out model implemented that way will perform |
1362 | miserably under the type of load it was designed to handle. In that case, |
1490 | miserably under the type of load it was designed to handle. In that case, |
… | |
… | |
1376 | { |
1504 | { |
1377 | // stop the I/O watcher, we received the event, but |
1505 | // stop the I/O watcher, we received the event, but |
1378 | // are not yet ready to handle it. |
1506 | // are not yet ready to handle it. |
1379 | ev_io_stop (EV_A_ w); |
1507 | ev_io_stop (EV_A_ w); |
1380 | |
1508 | |
1381 | // start the idle watcher to ahndle the actual event. |
1509 | // start the idle watcher to handle the actual event. |
1382 | // it will not be executed as long as other watchers |
1510 | // it will not be executed as long as other watchers |
1383 | // with the default priority are receiving events. |
1511 | // with the default priority are receiving events. |
1384 | ev_idle_start (EV_A_ &idle); |
1512 | ev_idle_start (EV_A_ &idle); |
1385 | } |
1513 | } |
1386 | |
1514 | |
… | |
… | |
1440 | |
1568 | |
1441 | If you cannot use non-blocking mode, then force the use of a |
1569 | If you cannot use non-blocking mode, then force the use of a |
1442 | known-to-be-good backend (at the time of this writing, this includes only |
1570 | known-to-be-good backend (at the time of this writing, this includes only |
1443 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1571 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1444 | descriptors for which non-blocking operation makes no sense (such as |
1572 | descriptors for which non-blocking operation makes no sense (such as |
1445 | files) - libev doesn't guarentee any specific behaviour in that case. |
1573 | files) - libev doesn't guarantee any specific behaviour in that case. |
1446 | |
1574 | |
1447 | Another thing you have to watch out for is that it is quite easy to |
1575 | Another thing you have to watch out for is that it is quite easy to |
1448 | receive "spurious" readiness notifications, that is your callback might |
1576 | receive "spurious" readiness notifications, that is your callback might |
1449 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1577 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1450 | because there is no data. Not only are some backends known to create a |
1578 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1515 | |
1643 | |
1516 | So when you encounter spurious, unexplained daemon exits, make sure you |
1644 | So when you encounter spurious, unexplained daemon exits, make sure you |
1517 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1645 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1518 | somewhere, as that would have given you a big clue). |
1646 | somewhere, as that would have given you a big clue). |
1519 | |
1647 | |
|
|
1648 | =head3 The special problem of accept()ing when you can't |
|
|
1649 | |
|
|
1650 | Many implementations of the POSIX C<accept> function (for example, |
|
|
1651 | found in post-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1652 | connection from the pending queue in all error cases. |
|
|
1653 | |
|
|
1654 | For example, larger servers often run out of file descriptors (because |
|
|
1655 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
|
|
1656 | rejecting the connection, leading to libev signalling readiness on |
|
|
1657 | the next iteration again (the connection still exists after all), and |
|
|
1658 | typically causing the program to loop at 100% CPU usage. |
|
|
1659 | |
|
|
1660 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1661 | operating systems, there is usually little the app can do to remedy the |
|
|
1662 | situation, and no known thread-safe method of removing the connection to |
|
|
1663 | cope with overload is known (to me). |
|
|
1664 | |
|
|
1665 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1666 | - when the program encounters an overload, it will just loop until the |
|
|
1667 | situation is over. While this is a form of busy waiting, no OS offers an |
|
|
1668 | event-based way to handle this situation, so it's the best one can do. |
|
|
1669 | |
|
|
1670 | A better way to handle the situation is to log any errors other than |
|
|
1671 | C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such |
|
|
1672 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1673 | what could be wrong ("raise the ulimit!"). For extra points one could stop |
|
|
1674 | the C<ev_io> watcher on the listening fd "for a while", which reduces CPU |
|
|
1675 | usage. |
|
|
1676 | |
|
|
1677 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1678 | descriptor for overload situations (e.g. by opening F</dev/null>), and |
|
|
1679 | when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>, |
|
|
1680 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1681 | clients under typical overload conditions. |
|
|
1682 | |
|
|
1683 | The last way to handle it is to simply log the error and C<exit>, as |
|
|
1684 | is often done with C<malloc> failures, but this results in an easy |
|
|
1685 | opportunity for a DoS attack. |
1520 | |
1686 | |
1521 | =head3 Watcher-Specific Functions |
1687 | =head3 Watcher-Specific Functions |
1522 | |
1688 | |
1523 | =over 4 |
1689 | =over 4 |
1524 | |
1690 | |
… | |
… | |
1556 | ... |
1722 | ... |
1557 | struct ev_loop *loop = ev_default_init (0); |
1723 | struct ev_loop *loop = ev_default_init (0); |
1558 | ev_io stdin_readable; |
1724 | ev_io stdin_readable; |
1559 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1725 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1560 | ev_io_start (loop, &stdin_readable); |
1726 | ev_io_start (loop, &stdin_readable); |
1561 | ev_loop (loop, 0); |
1727 | ev_run (loop, 0); |
1562 | |
1728 | |
1563 | |
1729 | |
1564 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1730 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1565 | |
1731 | |
1566 | Timer watchers are simple relative timers that generate an event after a |
1732 | Timer watchers are simple relative timers that generate an event after a |
… | |
… | |
1575 | The callback is guaranteed to be invoked only I<after> its timeout has |
1741 | The callback is guaranteed to be invoked only I<after> its timeout has |
1576 | passed (not I<at>, so on systems with very low-resolution clocks this |
1742 | passed (not I<at>, so on systems with very low-resolution clocks this |
1577 | might introduce a small delay). If multiple timers become ready during the |
1743 | might introduce a small delay). If multiple timers become ready during the |
1578 | same loop iteration then the ones with earlier time-out values are invoked |
1744 | same loop iteration then the ones with earlier time-out values are invoked |
1579 | before ones of the same priority with later time-out values (but this is |
1745 | before ones of the same priority with later time-out values (but this is |
1580 | no longer true when a callback calls C<ev_loop> recursively). |
1746 | no longer true when a callback calls C<ev_run> recursively). |
1581 | |
1747 | |
1582 | =head3 Be smart about timeouts |
1748 | =head3 Be smart about timeouts |
1583 | |
1749 | |
1584 | Many real-world problems involve some kind of timeout, usually for error |
1750 | Many real-world problems involve some kind of timeout, usually for error |
1585 | recovery. A typical example is an HTTP request - if the other side hangs, |
1751 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
1671 | ev_tstamp timeout = last_activity + 60.; |
1837 | ev_tstamp timeout = last_activity + 60.; |
1672 | |
1838 | |
1673 | // if last_activity + 60. is older than now, we did time out |
1839 | // if last_activity + 60. is older than now, we did time out |
1674 | if (timeout < now) |
1840 | if (timeout < now) |
1675 | { |
1841 | { |
1676 | // timeout occured, take action |
1842 | // timeout occurred, take action |
1677 | } |
1843 | } |
1678 | else |
1844 | else |
1679 | { |
1845 | { |
1680 | // callback was invoked, but there was some activity, re-arm |
1846 | // callback was invoked, but there was some activity, re-arm |
1681 | // the watcher to fire in last_activity + 60, which is |
1847 | // the watcher to fire in last_activity + 60, which is |
… | |
… | |
1703 | to the current time (meaning we just have some activity :), then call the |
1869 | to the current time (meaning we just have some activity :), then call the |
1704 | callback, which will "do the right thing" and start the timer: |
1870 | callback, which will "do the right thing" and start the timer: |
1705 | |
1871 | |
1706 | ev_init (timer, callback); |
1872 | ev_init (timer, callback); |
1707 | last_activity = ev_now (loop); |
1873 | last_activity = ev_now (loop); |
1708 | callback (loop, timer, EV_TIMEOUT); |
1874 | callback (loop, timer, EV_TIMER); |
1709 | |
1875 | |
1710 | And when there is some activity, simply store the current time in |
1876 | And when there is some activity, simply store the current time in |
1711 | C<last_activity>, no libev calls at all: |
1877 | C<last_activity>, no libev calls at all: |
1712 | |
1878 | |
1713 | last_actiivty = ev_now (loop); |
1879 | last_activity = ev_now (loop); |
1714 | |
1880 | |
1715 | This technique is slightly more complex, but in most cases where the |
1881 | This technique is slightly more complex, but in most cases where the |
1716 | time-out is unlikely to be triggered, much more efficient. |
1882 | time-out is unlikely to be triggered, much more efficient. |
1717 | |
1883 | |
1718 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
1884 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
… | |
… | |
1756 | |
1922 | |
1757 | =head3 The special problem of time updates |
1923 | =head3 The special problem of time updates |
1758 | |
1924 | |
1759 | Establishing the current time is a costly operation (it usually takes at |
1925 | Establishing the current time is a costly operation (it usually takes at |
1760 | least two system calls): EV therefore updates its idea of the current |
1926 | least two system calls): EV therefore updates its idea of the current |
1761 | time only before and after C<ev_loop> collects new events, which causes a |
1927 | time only before and after C<ev_run> collects new events, which causes a |
1762 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1928 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1763 | lots of events in one iteration. |
1929 | lots of events in one iteration. |
1764 | |
1930 | |
1765 | The relative timeouts are calculated relative to the C<ev_now ()> |
1931 | The relative timeouts are calculated relative to the C<ev_now ()> |
1766 | time. This is usually the right thing as this timestamp refers to the time |
1932 | time. This is usually the right thing as this timestamp refers to the time |
… | |
… | |
1837 | C<repeat> value), or reset the running timer to the C<repeat> value. |
2003 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1838 | |
2004 | |
1839 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
2005 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1840 | usage example. |
2006 | usage example. |
1841 | |
2007 | |
1842 | =item ev_timer_remaining (loop, ev_timer *) |
2008 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
1843 | |
2009 | |
1844 | Returns the remaining time until a timer fires. If the timer is active, |
2010 | Returns the remaining time until a timer fires. If the timer is active, |
1845 | then this time is relative to the current event loop time, otherwise it's |
2011 | then this time is relative to the current event loop time, otherwise it's |
1846 | the timeout value currently configured. |
2012 | the timeout value currently configured. |
1847 | |
2013 | |
1848 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
2014 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
1849 | C<5>. When the timer is started and one second passes, C<ev_timer_remain> |
2015 | C<5>. When the timer is started and one second passes, C<ev_timer_remaining> |
1850 | will return C<4>. When the timer expires and is restarted, it will return |
2016 | will return C<4>. When the timer expires and is restarted, it will return |
1851 | roughly C<7> (likely slightly less as callback invocation takes some time, |
2017 | roughly C<7> (likely slightly less as callback invocation takes some time, |
1852 | too), and so on. |
2018 | too), and so on. |
1853 | |
2019 | |
1854 | =item ev_tstamp repeat [read-write] |
2020 | =item ev_tstamp repeat [read-write] |
… | |
… | |
1883 | } |
2049 | } |
1884 | |
2050 | |
1885 | ev_timer mytimer; |
2051 | ev_timer mytimer; |
1886 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2052 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1887 | ev_timer_again (&mytimer); /* start timer */ |
2053 | ev_timer_again (&mytimer); /* start timer */ |
1888 | ev_loop (loop, 0); |
2054 | ev_run (loop, 0); |
1889 | |
2055 | |
1890 | // and in some piece of code that gets executed on any "activity": |
2056 | // and in some piece of code that gets executed on any "activity": |
1891 | // reset the timeout to start ticking again at 10 seconds |
2057 | // reset the timeout to start ticking again at 10 seconds |
1892 | ev_timer_again (&mytimer); |
2058 | ev_timer_again (&mytimer); |
1893 | |
2059 | |
… | |
… | |
1919 | |
2085 | |
1920 | As with timers, the callback is guaranteed to be invoked only when the |
2086 | As with timers, the callback is guaranteed to be invoked only when the |
1921 | point in time where it is supposed to trigger has passed. If multiple |
2087 | point in time where it is supposed to trigger has passed. If multiple |
1922 | timers become ready during the same loop iteration then the ones with |
2088 | timers become ready during the same loop iteration then the ones with |
1923 | earlier time-out values are invoked before ones with later time-out values |
2089 | earlier time-out values are invoked before ones with later time-out values |
1924 | (but this is no longer true when a callback calls C<ev_loop> recursively). |
2090 | (but this is no longer true when a callback calls C<ev_run> recursively). |
1925 | |
2091 | |
1926 | =head3 Watcher-Specific Functions and Data Members |
2092 | =head3 Watcher-Specific Functions and Data Members |
1927 | |
2093 | |
1928 | =over 4 |
2094 | =over 4 |
1929 | |
2095 | |
… | |
… | |
2057 | Example: Call a callback every hour, or, more precisely, whenever the |
2223 | Example: Call a callback every hour, or, more precisely, whenever the |
2058 | system time is divisible by 3600. The callback invocation times have |
2224 | system time is divisible by 3600. The callback invocation times have |
2059 | potentially a lot of jitter, but good long-term stability. |
2225 | potentially a lot of jitter, but good long-term stability. |
2060 | |
2226 | |
2061 | static void |
2227 | static void |
2062 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2228 | clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
2063 | { |
2229 | { |
2064 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2230 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2065 | } |
2231 | } |
2066 | |
2232 | |
2067 | ev_periodic hourly_tick; |
2233 | ev_periodic hourly_tick; |
… | |
… | |
2114 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2280 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2115 | not be unduly interrupted. If you have a problem with system calls getting |
2281 | not be unduly interrupted. If you have a problem with system calls getting |
2116 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2282 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2117 | and unblock them in an C<ev_prepare> watcher. |
2283 | and unblock them in an C<ev_prepare> watcher. |
2118 | |
2284 | |
2119 | =head3 The special problem of inheritance over execve |
2285 | =head3 The special problem of inheritance over fork/execve/pthread_create |
2120 | |
2286 | |
2121 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2287 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2122 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2288 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2123 | stopping it again), that is, libev might or might not block the signal, |
2289 | stopping it again), that is, libev might or might not block the signal, |
2124 | and might or might not set or restore the installed signal handler. |
2290 | and might or might not set or restore the installed signal handler. |
… | |
… | |
2130 | |
2296 | |
2131 | This means that before calling C<exec> (from the child) you should reset |
2297 | This means that before calling C<exec> (from the child) you should reset |
2132 | the signal mask to whatever "default" you expect (all clear is a good |
2298 | the signal mask to whatever "default" you expect (all clear is a good |
2133 | choice usually). |
2299 | choice usually). |
2134 | |
2300 | |
2135 | In current versions of libev, you can ensure that the signal mask is not |
2301 | The simplest way to ensure that the signal mask is reset in the child is |
2136 | blocking any signals (except temporarily, so thread users watch out) by |
2302 | to install a fork handler with C<pthread_atfork> that resets it. That will |
2137 | specifying the C<EVFLAG_NOSIGNALFD> when creating the event loop. This is |
2303 | catch fork calls done by libraries (such as the libc) as well. |
2138 | not guaranteed for future versions, however. |
2304 | |
|
|
2305 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2306 | unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces |
|
|
2307 | the window of opportunity for problems, it will not go away, as libev |
|
|
2308 | I<has> to modify the signal mask, at least temporarily. |
|
|
2309 | |
|
|
2310 | So I can't stress this enough: I<If you do not reset your signal mask when |
|
|
2311 | you expect it to be empty, you have a race condition in your code>. This |
|
|
2312 | is not a libev-specific thing, this is true for most event libraries. |
2139 | |
2313 | |
2140 | =head3 Watcher-Specific Functions and Data Members |
2314 | =head3 Watcher-Specific Functions and Data Members |
2141 | |
2315 | |
2142 | =over 4 |
2316 | =over 4 |
2143 | |
2317 | |
… | |
… | |
2159 | Example: Try to exit cleanly on SIGINT. |
2333 | Example: Try to exit cleanly on SIGINT. |
2160 | |
2334 | |
2161 | static void |
2335 | static void |
2162 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2336 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2163 | { |
2337 | { |
2164 | ev_unloop (loop, EVUNLOOP_ALL); |
2338 | ev_break (loop, EVBREAK_ALL); |
2165 | } |
2339 | } |
2166 | |
2340 | |
2167 | ev_signal signal_watcher; |
2341 | ev_signal signal_watcher; |
2168 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2342 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2169 | ev_signal_start (loop, &signal_watcher); |
2343 | ev_signal_start (loop, &signal_watcher); |
… | |
… | |
2555 | |
2729 | |
2556 | Prepare and check watchers are usually (but not always) used in pairs: |
2730 | Prepare and check watchers are usually (but not always) used in pairs: |
2557 | prepare watchers get invoked before the process blocks and check watchers |
2731 | prepare watchers get invoked before the process blocks and check watchers |
2558 | afterwards. |
2732 | afterwards. |
2559 | |
2733 | |
2560 | You I<must not> call C<ev_loop> or similar functions that enter |
2734 | You I<must not> call C<ev_run> or similar functions that enter |
2561 | the current event loop from either C<ev_prepare> or C<ev_check> |
2735 | the current event loop from either C<ev_prepare> or C<ev_check> |
2562 | watchers. Other loops than the current one are fine, however. The |
2736 | watchers. Other loops than the current one are fine, however. The |
2563 | rationale behind this is that you do not need to check for recursion in |
2737 | rationale behind this is that you do not need to check for recursion in |
2564 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2738 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2565 | C<ev_check> so if you have one watcher of each kind they will always be |
2739 | C<ev_check> so if you have one watcher of each kind they will always be |
… | |
… | |
2733 | |
2907 | |
2734 | if (timeout >= 0) |
2908 | if (timeout >= 0) |
2735 | // create/start timer |
2909 | // create/start timer |
2736 | |
2910 | |
2737 | // poll |
2911 | // poll |
2738 | ev_loop (EV_A_ 0); |
2912 | ev_run (EV_A_ 0); |
2739 | |
2913 | |
2740 | // stop timer again |
2914 | // stop timer again |
2741 | if (timeout >= 0) |
2915 | if (timeout >= 0) |
2742 | ev_timer_stop (EV_A_ &to); |
2916 | ev_timer_stop (EV_A_ &to); |
2743 | |
2917 | |
… | |
… | |
2821 | if you do not want that, you need to temporarily stop the embed watcher). |
2995 | if you do not want that, you need to temporarily stop the embed watcher). |
2822 | |
2996 | |
2823 | =item ev_embed_sweep (loop, ev_embed *) |
2997 | =item ev_embed_sweep (loop, ev_embed *) |
2824 | |
2998 | |
2825 | Make a single, non-blocking sweep over the embedded loop. This works |
2999 | Make a single, non-blocking sweep over the embedded loop. This works |
2826 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
3000 | similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most |
2827 | appropriate way for embedded loops. |
3001 | appropriate way for embedded loops. |
2828 | |
3002 | |
2829 | =item struct ev_loop *other [read-only] |
3003 | =item struct ev_loop *other [read-only] |
2830 | |
3004 | |
2831 | The embedded event loop. |
3005 | The embedded event loop. |
… | |
… | |
2891 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3065 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2892 | handlers will be invoked, too, of course. |
3066 | handlers will be invoked, too, of course. |
2893 | |
3067 | |
2894 | =head3 The special problem of life after fork - how is it possible? |
3068 | =head3 The special problem of life after fork - how is it possible? |
2895 | |
3069 | |
2896 | Most uses of C<fork()> consist of forking, then some simple calls to ste |
3070 | Most uses of C<fork()> consist of forking, then some simple calls to set |
2897 | up/change the process environment, followed by a call to C<exec()>. This |
3071 | up/change the process environment, followed by a call to C<exec()>. This |
2898 | sequence should be handled by libev without any problems. |
3072 | sequence should be handled by libev without any problems. |
2899 | |
3073 | |
2900 | This changes when the application actually wants to do event handling |
3074 | This changes when the application actually wants to do event handling |
2901 | in the child, or both parent in child, in effect "continuing" after the |
3075 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
2917 | disadvantage of having to use multiple event loops (which do not support |
3091 | disadvantage of having to use multiple event loops (which do not support |
2918 | signal watchers). |
3092 | signal watchers). |
2919 | |
3093 | |
2920 | When this is not possible, or you want to use the default loop for |
3094 | When this is not possible, or you want to use the default loop for |
2921 | other reasons, then in the process that wants to start "fresh", call |
3095 | other reasons, then in the process that wants to start "fresh", call |
2922 | C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying |
3096 | C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>. |
2923 | the default loop will "orphan" (not stop) all registered watchers, so you |
3097 | Destroying the default loop will "orphan" (not stop) all registered |
2924 | have to be careful not to execute code that modifies those watchers. Note |
3098 | watchers, so you have to be careful not to execute code that modifies |
2925 | also that in that case, you have to re-register any signal watchers. |
3099 | those watchers. Note also that in that case, you have to re-register any |
|
|
3100 | signal watchers. |
2926 | |
3101 | |
2927 | =head3 Watcher-Specific Functions and Data Members |
3102 | =head3 Watcher-Specific Functions and Data Members |
2928 | |
3103 | |
2929 | =over 4 |
3104 | =over 4 |
2930 | |
3105 | |
2931 | =item ev_fork_init (ev_signal *, callback) |
3106 | =item ev_fork_init (ev_fork *, callback) |
2932 | |
3107 | |
2933 | Initialises and configures the fork watcher - it has no parameters of any |
3108 | Initialises and configures the fork watcher - it has no parameters of any |
2934 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
3109 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
2935 | believe me. |
3110 | really. |
2936 | |
3111 | |
2937 | =back |
3112 | =back |
2938 | |
3113 | |
2939 | |
3114 | |
|
|
3115 | =head2 C<ev_cleanup> - even the best things end |
|
|
3116 | |
|
|
3117 | Cleanup watchers are called just before the event loop is being destroyed |
|
|
3118 | by a call to C<ev_loop_destroy>. |
|
|
3119 | |
|
|
3120 | While there is no guarantee that the event loop gets destroyed, cleanup |
|
|
3121 | watchers provide a convenient method to install cleanup hooks for your |
|
|
3122 | program, worker threads and so on - you just to make sure to destroy the |
|
|
3123 | loop when you want them to be invoked. |
|
|
3124 | |
|
|
3125 | Cleanup watchers are invoked in the same way as any other watcher. Unlike |
|
|
3126 | all other watchers, they do not keep a reference to the event loop (which |
|
|
3127 | makes a lot of sense if you think about it). Like all other watchers, you |
|
|
3128 | can call libev functions in the callback, except C<ev_cleanup_start>. |
|
|
3129 | |
|
|
3130 | =head3 Watcher-Specific Functions and Data Members |
|
|
3131 | |
|
|
3132 | =over 4 |
|
|
3133 | |
|
|
3134 | =item ev_cleanup_init (ev_cleanup *, callback) |
|
|
3135 | |
|
|
3136 | Initialises and configures the cleanup watcher - it has no parameters of |
|
|
3137 | any kind. There is a C<ev_cleanup_set> macro, but using it is utterly |
|
|
3138 | pointless, I assure you. |
|
|
3139 | |
|
|
3140 | =back |
|
|
3141 | |
|
|
3142 | Example: Register an atexit handler to destroy the default loop, so any |
|
|
3143 | cleanup functions are called. |
|
|
3144 | |
|
|
3145 | static void |
|
|
3146 | program_exits (void) |
|
|
3147 | { |
|
|
3148 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
3149 | } |
|
|
3150 | |
|
|
3151 | ... |
|
|
3152 | atexit (program_exits); |
|
|
3153 | |
|
|
3154 | |
2940 | =head2 C<ev_async> - how to wake up another event loop |
3155 | =head2 C<ev_async> - how to wake up an event loop |
2941 | |
3156 | |
2942 | In general, you cannot use an C<ev_loop> from multiple threads or other |
3157 | In general, you cannot use an C<ev_run> from multiple threads or other |
2943 | asynchronous sources such as signal handlers (as opposed to multiple event |
3158 | asynchronous sources such as signal handlers (as opposed to multiple event |
2944 | loops - those are of course safe to use in different threads). |
3159 | loops - those are of course safe to use in different threads). |
2945 | |
3160 | |
2946 | Sometimes, however, you need to wake up another event loop you do not |
3161 | Sometimes, however, you need to wake up an event loop you do not control, |
2947 | control, for example because it belongs to another thread. This is what |
3162 | for example because it belongs to another thread. This is what C<ev_async> |
2948 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
3163 | watchers do: as long as the C<ev_async> watcher is active, you can signal |
2949 | can signal it by calling C<ev_async_send>, which is thread- and signal |
3164 | it by calling C<ev_async_send>, which is thread- and signal safe. |
2950 | safe. |
|
|
2951 | |
3165 | |
2952 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3166 | This functionality is very similar to C<ev_signal> watchers, as signals, |
2953 | too, are asynchronous in nature, and signals, too, will be compressed |
3167 | too, are asynchronous in nature, and signals, too, will be compressed |
2954 | (i.e. the number of callback invocations may be less than the number of |
3168 | (i.e. the number of callback invocations may be less than the number of |
2955 | C<ev_async_sent> calls). |
3169 | C<ev_async_sent> calls). |
… | |
… | |
2960 | =head3 Queueing |
3174 | =head3 Queueing |
2961 | |
3175 | |
2962 | C<ev_async> does not support queueing of data in any way. The reason |
3176 | C<ev_async> does not support queueing of data in any way. The reason |
2963 | is that the author does not know of a simple (or any) algorithm for a |
3177 | is that the author does not know of a simple (or any) algorithm for a |
2964 | multiple-writer-single-reader queue that works in all cases and doesn't |
3178 | multiple-writer-single-reader queue that works in all cases and doesn't |
2965 | need elaborate support such as pthreads. |
3179 | need elaborate support such as pthreads or unportable memory access |
|
|
3180 | semantics. |
2966 | |
3181 | |
2967 | That means that if you want to queue data, you have to provide your own |
3182 | That means that if you want to queue data, you have to provide your own |
2968 | queue. But at least I can tell you how to implement locking around your |
3183 | queue. But at least I can tell you how to implement locking around your |
2969 | queue: |
3184 | queue: |
2970 | |
3185 | |
… | |
… | |
3109 | |
3324 | |
3110 | If C<timeout> is less than 0, then no timeout watcher will be |
3325 | If C<timeout> is less than 0, then no timeout watcher will be |
3111 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3326 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3112 | repeat = 0) will be started. C<0> is a valid timeout. |
3327 | repeat = 0) will be started. C<0> is a valid timeout. |
3113 | |
3328 | |
3114 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
3329 | The callback has the type C<void (*cb)(int revents, void *arg)> and is |
3115 | passed an C<revents> set like normal event callbacks (a combination of |
3330 | passed an C<revents> set like normal event callbacks (a combination of |
3116 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
3331 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg> |
3117 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3332 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3118 | a timeout and an io event at the same time - you probably should give io |
3333 | a timeout and an io event at the same time - you probably should give io |
3119 | events precedence. |
3334 | events precedence. |
3120 | |
3335 | |
3121 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3336 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3122 | |
3337 | |
3123 | static void stdin_ready (int revents, void *arg) |
3338 | static void stdin_ready (int revents, void *arg) |
3124 | { |
3339 | { |
3125 | if (revents & EV_READ) |
3340 | if (revents & EV_READ) |
3126 | /* stdin might have data for us, joy! */; |
3341 | /* stdin might have data for us, joy! */; |
3127 | else if (revents & EV_TIMEOUT) |
3342 | else if (revents & EV_TIMER) |
3128 | /* doh, nothing entered */; |
3343 | /* doh, nothing entered */; |
3129 | } |
3344 | } |
3130 | |
3345 | |
3131 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3346 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3132 | |
3347 | |
3133 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
|
|
3134 | |
|
|
3135 | Feeds the given event set into the event loop, as if the specified event |
|
|
3136 | had happened for the specified watcher (which must be a pointer to an |
|
|
3137 | initialised but not necessarily started event watcher). |
|
|
3138 | |
|
|
3139 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
3348 | =item ev_feed_fd_event (loop, int fd, int revents) |
3140 | |
3349 | |
3141 | Feed an event on the given fd, as if a file descriptor backend detected |
3350 | Feed an event on the given fd, as if a file descriptor backend detected |
3142 | the given events it. |
3351 | the given events it. |
3143 | |
3352 | |
3144 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
3353 | =item ev_feed_signal_event (loop, int signum) |
3145 | |
3354 | |
3146 | Feed an event as if the given signal occurred (C<loop> must be the default |
3355 | Feed an event as if the given signal occurred (C<loop> must be the default |
3147 | loop!). |
3356 | loop!). |
3148 | |
3357 | |
3149 | =back |
3358 | =back |
… | |
… | |
3229 | |
3438 | |
3230 | =over 4 |
3439 | =over 4 |
3231 | |
3440 | |
3232 | =item ev::TYPE::TYPE () |
3441 | =item ev::TYPE::TYPE () |
3233 | |
3442 | |
3234 | =item ev::TYPE::TYPE (struct ev_loop *) |
3443 | =item ev::TYPE::TYPE (loop) |
3235 | |
3444 | |
3236 | =item ev::TYPE::~TYPE |
3445 | =item ev::TYPE::~TYPE |
3237 | |
3446 | |
3238 | The constructor (optionally) takes an event loop to associate the watcher |
3447 | The constructor (optionally) takes an event loop to associate the watcher |
3239 | with. If it is omitted, it will use C<EV_DEFAULT>. |
3448 | with. If it is omitted, it will use C<EV_DEFAULT>. |
… | |
… | |
3272 | myclass obj; |
3481 | myclass obj; |
3273 | ev::io iow; |
3482 | ev::io iow; |
3274 | iow.set <myclass, &myclass::io_cb> (&obj); |
3483 | iow.set <myclass, &myclass::io_cb> (&obj); |
3275 | |
3484 | |
3276 | =item w->set (object *) |
3485 | =item w->set (object *) |
3277 | |
|
|
3278 | This is an B<experimental> feature that might go away in a future version. |
|
|
3279 | |
3486 | |
3280 | This is a variation of a method callback - leaving out the method to call |
3487 | This is a variation of a method callback - leaving out the method to call |
3281 | will default the method to C<operator ()>, which makes it possible to use |
3488 | will default the method to C<operator ()>, which makes it possible to use |
3282 | functor objects without having to manually specify the C<operator ()> all |
3489 | functor objects without having to manually specify the C<operator ()> all |
3283 | the time. Incidentally, you can then also leave out the template argument |
3490 | the time. Incidentally, you can then also leave out the template argument |
… | |
… | |
3316 | Example: Use a plain function as callback. |
3523 | Example: Use a plain function as callback. |
3317 | |
3524 | |
3318 | static void io_cb (ev::io &w, int revents) { } |
3525 | static void io_cb (ev::io &w, int revents) { } |
3319 | iow.set <io_cb> (); |
3526 | iow.set <io_cb> (); |
3320 | |
3527 | |
3321 | =item w->set (struct ev_loop *) |
3528 | =item w->set (loop) |
3322 | |
3529 | |
3323 | Associates a different C<struct ev_loop> with this watcher. You can only |
3530 | Associates a different C<struct ev_loop> with this watcher. You can only |
3324 | do this when the watcher is inactive (and not pending either). |
3531 | do this when the watcher is inactive (and not pending either). |
3325 | |
3532 | |
3326 | =item w->set ([arguments]) |
3533 | =item w->set ([arguments]) |
3327 | |
3534 | |
3328 | Basically the same as C<ev_TYPE_set>, with the same arguments. Must be |
3535 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
3329 | called at least once. Unlike the C counterpart, an active watcher gets |
3536 | method or a suitable start method must be called at least once. Unlike the |
3330 | automatically stopped and restarted when reconfiguring it with this |
3537 | C counterpart, an active watcher gets automatically stopped and restarted |
3331 | method. |
3538 | when reconfiguring it with this method. |
3332 | |
3539 | |
3333 | =item w->start () |
3540 | =item w->start () |
3334 | |
3541 | |
3335 | Starts the watcher. Note that there is no C<loop> argument, as the |
3542 | Starts the watcher. Note that there is no C<loop> argument, as the |
3336 | constructor already stores the event loop. |
3543 | constructor already stores the event loop. |
3337 | |
3544 | |
|
|
3545 | =item w->start ([arguments]) |
|
|
3546 | |
|
|
3547 | Instead of calling C<set> and C<start> methods separately, it is often |
|
|
3548 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
3549 | the configure C<set> method of the watcher. |
|
|
3550 | |
3338 | =item w->stop () |
3551 | =item w->stop () |
3339 | |
3552 | |
3340 | Stops the watcher if it is active. Again, no C<loop> argument. |
3553 | Stops the watcher if it is active. Again, no C<loop> argument. |
3341 | |
3554 | |
3342 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
3555 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
… | |
… | |
3354 | |
3567 | |
3355 | =back |
3568 | =back |
3356 | |
3569 | |
3357 | =back |
3570 | =back |
3358 | |
3571 | |
3359 | Example: Define a class with an IO and idle watcher, start one of them in |
3572 | Example: Define a class with two I/O and idle watchers, start the I/O |
3360 | the constructor. |
3573 | watchers in the constructor. |
3361 | |
3574 | |
3362 | class myclass |
3575 | class myclass |
3363 | { |
3576 | { |
3364 | ev::io io ; void io_cb (ev::io &w, int revents); |
3577 | ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
3578 | ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
3365 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3579 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3366 | |
3580 | |
3367 | myclass (int fd) |
3581 | myclass (int fd) |
3368 | { |
3582 | { |
3369 | io .set <myclass, &myclass::io_cb > (this); |
3583 | io .set <myclass, &myclass::io_cb > (this); |
|
|
3584 | io2 .set <myclass, &myclass::io2_cb > (this); |
3370 | idle.set <myclass, &myclass::idle_cb> (this); |
3585 | idle.set <myclass, &myclass::idle_cb> (this); |
3371 | |
3586 | |
3372 | io.start (fd, ev::READ); |
3587 | io.set (fd, ev::WRITE); // configure the watcher |
|
|
3588 | io.start (); // start it whenever convenient |
|
|
3589 | |
|
|
3590 | io2.start (fd, ev::READ); // set + start in one call |
3373 | } |
3591 | } |
3374 | }; |
3592 | }; |
3375 | |
3593 | |
3376 | |
3594 | |
3377 | =head1 OTHER LANGUAGE BINDINGS |
3595 | =head1 OTHER LANGUAGE BINDINGS |
… | |
… | |
3425 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3643 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3426 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3644 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3427 | |
3645 | |
3428 | =item Lua |
3646 | =item Lua |
3429 | |
3647 | |
3430 | Brian Maher has written a partial interface to libev |
3648 | Brian Maher has written a partial interface to libev for lua (at the |
3431 | for lua (only C<ev_io> and C<ev_timer>), to be found at |
3649 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
3432 | L<http://github.com/brimworks/lua-ev>. |
3650 | L<http://github.com/brimworks/lua-ev>. |
3433 | |
3651 | |
3434 | =back |
3652 | =back |
3435 | |
3653 | |
3436 | |
3654 | |
… | |
… | |
3451 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3669 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3452 | C<EV_A_> is used when other arguments are following. Example: |
3670 | C<EV_A_> is used when other arguments are following. Example: |
3453 | |
3671 | |
3454 | ev_unref (EV_A); |
3672 | ev_unref (EV_A); |
3455 | ev_timer_add (EV_A_ watcher); |
3673 | ev_timer_add (EV_A_ watcher); |
3456 | ev_loop (EV_A_ 0); |
3674 | ev_run (EV_A_ 0); |
3457 | |
3675 | |
3458 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3676 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3459 | which is often provided by the following macro. |
3677 | which is often provided by the following macro. |
3460 | |
3678 | |
3461 | =item C<EV_P>, C<EV_P_> |
3679 | =item C<EV_P>, C<EV_P_> |
… | |
… | |
3501 | } |
3719 | } |
3502 | |
3720 | |
3503 | ev_check check; |
3721 | ev_check check; |
3504 | ev_check_init (&check, check_cb); |
3722 | ev_check_init (&check, check_cb); |
3505 | ev_check_start (EV_DEFAULT_ &check); |
3723 | ev_check_start (EV_DEFAULT_ &check); |
3506 | ev_loop (EV_DEFAULT_ 0); |
3724 | ev_run (EV_DEFAULT_ 0); |
3507 | |
3725 | |
3508 | =head1 EMBEDDING |
3726 | =head1 EMBEDDING |
3509 | |
3727 | |
3510 | Libev can (and often is) directly embedded into host |
3728 | Libev can (and often is) directly embedded into host |
3511 | applications. Examples of applications that embed it include the Deliantra |
3729 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3591 | libev.m4 |
3809 | libev.m4 |
3592 | |
3810 | |
3593 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3811 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3594 | |
3812 | |
3595 | Libev can be configured via a variety of preprocessor symbols you have to |
3813 | Libev can be configured via a variety of preprocessor symbols you have to |
3596 | define before including any of its files. The default in the absence of |
3814 | define before including (or compiling) any of its files. The default in |
3597 | autoconf is documented for every option. |
3815 | the absence of autoconf is documented for every option. |
|
|
3816 | |
|
|
3817 | Symbols marked with "(h)" do not change the ABI, and can have different |
|
|
3818 | values when compiling libev vs. including F<ev.h>, so it is permissible |
|
|
3819 | to redefine them before including F<ev.h> without breaking compatibility |
|
|
3820 | to a compiled library. All other symbols change the ABI, which means all |
|
|
3821 | users of libev and the libev code itself must be compiled with compatible |
|
|
3822 | settings. |
3598 | |
3823 | |
3599 | =over 4 |
3824 | =over 4 |
3600 | |
3825 | |
|
|
3826 | =item EV_COMPAT3 (h) |
|
|
3827 | |
|
|
3828 | Backwards compatibility is a major concern for libev. This is why this |
|
|
3829 | release of libev comes with wrappers for the functions and symbols that |
|
|
3830 | have been renamed between libev version 3 and 4. |
|
|
3831 | |
|
|
3832 | You can disable these wrappers (to test compatibility with future |
|
|
3833 | versions) by defining C<EV_COMPAT3> to C<0> when compiling your |
|
|
3834 | sources. This has the additional advantage that you can drop the C<struct> |
|
|
3835 | from C<struct ev_loop> declarations, as libev will provide an C<ev_loop> |
|
|
3836 | typedef in that case. |
|
|
3837 | |
|
|
3838 | In some future version, the default for C<EV_COMPAT3> will become C<0>, |
|
|
3839 | and in some even more future version the compatibility code will be |
|
|
3840 | removed completely. |
|
|
3841 | |
3601 | =item EV_STANDALONE |
3842 | =item EV_STANDALONE (h) |
3602 | |
3843 | |
3603 | Must always be C<1> if you do not use autoconf configuration, which |
3844 | Must always be C<1> if you do not use autoconf configuration, which |
3604 | keeps libev from including F<config.h>, and it also defines dummy |
3845 | keeps libev from including F<config.h>, and it also defines dummy |
3605 | implementations for some libevent functions (such as logging, which is not |
3846 | implementations for some libevent functions (such as logging, which is not |
3606 | supported). It will also not define any of the structs usually found in |
3847 | supported). It will also not define any of the structs usually found in |
… | |
… | |
3756 | as well as for signal and thread safety in C<ev_async> watchers. |
3997 | as well as for signal and thread safety in C<ev_async> watchers. |
3757 | |
3998 | |
3758 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3999 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3759 | (from F<signal.h>), which is usually good enough on most platforms. |
4000 | (from F<signal.h>), which is usually good enough on most platforms. |
3760 | |
4001 | |
3761 | =item EV_H |
4002 | =item EV_H (h) |
3762 | |
4003 | |
3763 | The name of the F<ev.h> header file used to include it. The default if |
4004 | The name of the F<ev.h> header file used to include it. The default if |
3764 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
4005 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3765 | used to virtually rename the F<ev.h> header file in case of conflicts. |
4006 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3766 | |
4007 | |
3767 | =item EV_CONFIG_H |
4008 | =item EV_CONFIG_H (h) |
3768 | |
4009 | |
3769 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
4010 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3770 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
4011 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3771 | C<EV_H>, above. |
4012 | C<EV_H>, above. |
3772 | |
4013 | |
3773 | =item EV_EVENT_H |
4014 | =item EV_EVENT_H (h) |
3774 | |
4015 | |
3775 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
4016 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3776 | of how the F<event.h> header can be found, the default is C<"event.h">. |
4017 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3777 | |
4018 | |
3778 | =item EV_PROTOTYPES |
4019 | =item EV_PROTOTYPES (h) |
3779 | |
4020 | |
3780 | If defined to be C<0>, then F<ev.h> will not define any function |
4021 | If defined to be C<0>, then F<ev.h> will not define any function |
3781 | prototypes, but still define all the structs and other symbols. This is |
4022 | prototypes, but still define all the structs and other symbols. This is |
3782 | occasionally useful if you want to provide your own wrapper functions |
4023 | occasionally useful if you want to provide your own wrapper functions |
3783 | around libev functions. |
4024 | around libev functions. |
… | |
… | |
3805 | fine. |
4046 | fine. |
3806 | |
4047 | |
3807 | If your embedding application does not need any priorities, defining these |
4048 | If your embedding application does not need any priorities, defining these |
3808 | both to C<0> will save some memory and CPU. |
4049 | both to C<0> will save some memory and CPU. |
3809 | |
4050 | |
3810 | =item EV_PERIODIC_ENABLE |
4051 | =item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, |
|
|
4052 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
|
|
4053 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3811 | |
4054 | |
3812 | If undefined or defined to be C<1>, then periodic timers are supported. If |
4055 | If undefined or defined to be C<1> (and the platform supports it), then |
3813 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
4056 | the respective watcher type is supported. If defined to be C<0>, then it |
3814 | code. |
4057 | is not. Disabling watcher types mainly saves code size. |
3815 | |
4058 | |
3816 | =item EV_IDLE_ENABLE |
4059 | =item EV_FEATURES |
3817 | |
|
|
3818 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3819 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3820 | code. |
|
|
3821 | |
|
|
3822 | =item EV_EMBED_ENABLE |
|
|
3823 | |
|
|
3824 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3825 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3826 | watcher types, which therefore must not be disabled. |
|
|
3827 | |
|
|
3828 | =item EV_STAT_ENABLE |
|
|
3829 | |
|
|
3830 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3831 | defined to be C<0>, then they are not. |
|
|
3832 | |
|
|
3833 | =item EV_FORK_ENABLE |
|
|
3834 | |
|
|
3835 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3836 | defined to be C<0>, then they are not. |
|
|
3837 | |
|
|
3838 | =item EV_ASYNC_ENABLE |
|
|
3839 | |
|
|
3840 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3841 | defined to be C<0>, then they are not. |
|
|
3842 | |
|
|
3843 | =item EV_MINIMAL |
|
|
3844 | |
4060 | |
3845 | If you need to shave off some kilobytes of code at the expense of some |
4061 | If you need to shave off some kilobytes of code at the expense of some |
3846 | speed (but with the full API), define this symbol to C<1>. Currently this |
4062 | speed (but with the full API), you can define this symbol to request |
3847 | is used to override some inlining decisions, saves roughly 30% code size |
4063 | certain subsets of functionality. The default is to enable all features |
3848 | on amd64. It also selects a much smaller 2-heap for timer management over |
4064 | that can be enabled on the platform. |
3849 | the default 4-heap. |
|
|
3850 | |
4065 | |
3851 | You can save even more by disabling watcher types you do not need |
4066 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
3852 | and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert> |
4067 | with some broad features you want) and then selectively re-enable |
3853 | (C<-DNDEBUG>) will usually reduce code size a lot. |
4068 | additional parts you want, for example if you want everything minimal, |
|
|
4069 | but multiple event loop support, async and child watchers and the poll |
|
|
4070 | backend, use this: |
3854 | |
4071 | |
3855 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
4072 | #define EV_FEATURES 0 |
3856 | provide a bare-bones event library. See C<ev.h> for details on what parts |
4073 | #define EV_MULTIPLICITY 1 |
3857 | of the API are still available, and do not complain if this subset changes |
4074 | #define EV_USE_POLL 1 |
3858 | over time. |
4075 | #define EV_CHILD_ENABLE 1 |
|
|
4076 | #define EV_ASYNC_ENABLE 1 |
|
|
4077 | |
|
|
4078 | The actual value is a bitset, it can be a combination of the following |
|
|
4079 | values: |
|
|
4080 | |
|
|
4081 | =over 4 |
|
|
4082 | |
|
|
4083 | =item C<1> - faster/larger code |
|
|
4084 | |
|
|
4085 | Use larger code to speed up some operations. |
|
|
4086 | |
|
|
4087 | Currently this is used to override some inlining decisions (enlarging the |
|
|
4088 | code size by roughly 30% on amd64). |
|
|
4089 | |
|
|
4090 | When optimising for size, use of compiler flags such as C<-Os> with |
|
|
4091 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
|
|
4092 | assertions. |
|
|
4093 | |
|
|
4094 | =item C<2> - faster/larger data structures |
|
|
4095 | |
|
|
4096 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
|
|
4097 | hash table sizes and so on. This will usually further increase code size |
|
|
4098 | and can additionally have an effect on the size of data structures at |
|
|
4099 | runtime. |
|
|
4100 | |
|
|
4101 | =item C<4> - full API configuration |
|
|
4102 | |
|
|
4103 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
|
|
4104 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
|
|
4105 | |
|
|
4106 | =item C<8> - full API |
|
|
4107 | |
|
|
4108 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
|
|
4109 | details on which parts of the API are still available without this |
|
|
4110 | feature, and do not complain if this subset changes over time. |
|
|
4111 | |
|
|
4112 | =item C<16> - enable all optional watcher types |
|
|
4113 | |
|
|
4114 | Enables all optional watcher types. If you want to selectively enable |
|
|
4115 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
4116 | embed, async, child...) you can enable them manually by defining |
|
|
4117 | C<EV_watchertype_ENABLE> to C<1> instead. |
|
|
4118 | |
|
|
4119 | =item C<32> - enable all backends |
|
|
4120 | |
|
|
4121 | This enables all backends - without this feature, you need to enable at |
|
|
4122 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
|
|
4123 | |
|
|
4124 | =item C<64> - enable OS-specific "helper" APIs |
|
|
4125 | |
|
|
4126 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
4127 | default. |
|
|
4128 | |
|
|
4129 | =back |
|
|
4130 | |
|
|
4131 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
|
|
4132 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
4133 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
4134 | watchers, timers and monotonic clock support. |
|
|
4135 | |
|
|
4136 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
4137 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
|
|
4138 | your program might be left out as well - a binary starting a timer and an |
|
|
4139 | I/O watcher then might come out at only 5Kb. |
|
|
4140 | |
|
|
4141 | =item EV_AVOID_STDIO |
|
|
4142 | |
|
|
4143 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
|
|
4144 | functions (printf, scanf, perror etc.). This will increase the code size |
|
|
4145 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
4146 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
4147 | big. |
|
|
4148 | |
|
|
4149 | Note that error messages might become less precise when this option is |
|
|
4150 | enabled. |
3859 | |
4151 | |
3860 | =item EV_NSIG |
4152 | =item EV_NSIG |
3861 | |
4153 | |
3862 | The highest supported signal number, +1 (or, the number of |
4154 | The highest supported signal number, +1 (or, the number of |
3863 | signals): Normally, libev tries to deduce the maximum number of signals |
4155 | signals): Normally, libev tries to deduce the maximum number of signals |
3864 | automatically, but sometimes this fails, in which case it can be |
4156 | automatically, but sometimes this fails, in which case it can be |
3865 | specified. Also, using a lower number than detected (C<32> should be |
4157 | specified. Also, using a lower number than detected (C<32> should be |
3866 | good for about any system in existance) can save some memory, as libev |
4158 | good for about any system in existence) can save some memory, as libev |
3867 | statically allocates some 12-24 bytes per signal number. |
4159 | statically allocates some 12-24 bytes per signal number. |
3868 | |
4160 | |
3869 | =item EV_PID_HASHSIZE |
4161 | =item EV_PID_HASHSIZE |
3870 | |
4162 | |
3871 | C<ev_child> watchers use a small hash table to distribute workload by |
4163 | C<ev_child> watchers use a small hash table to distribute workload by |
3872 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
4164 | pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled), |
3873 | than enough. If you need to manage thousands of children you might want to |
4165 | usually more than enough. If you need to manage thousands of children you |
3874 | increase this value (I<must> be a power of two). |
4166 | might want to increase this value (I<must> be a power of two). |
3875 | |
4167 | |
3876 | =item EV_INOTIFY_HASHSIZE |
4168 | =item EV_INOTIFY_HASHSIZE |
3877 | |
4169 | |
3878 | C<ev_stat> watchers use a small hash table to distribute workload by |
4170 | C<ev_stat> watchers use a small hash table to distribute workload by |
3879 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
4171 | inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES> |
3880 | usually more than enough. If you need to manage thousands of C<ev_stat> |
4172 | disabled), usually more than enough. If you need to manage thousands of |
3881 | watchers you might want to increase this value (I<must> be a power of |
4173 | C<ev_stat> watchers you might want to increase this value (I<must> be a |
3882 | two). |
4174 | power of two). |
3883 | |
4175 | |
3884 | =item EV_USE_4HEAP |
4176 | =item EV_USE_4HEAP |
3885 | |
4177 | |
3886 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4178 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3887 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
4179 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3888 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
4180 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3889 | faster performance with many (thousands) of watchers. |
4181 | faster performance with many (thousands) of watchers. |
3890 | |
4182 | |
3891 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4183 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3892 | (disabled). |
4184 | will be C<0>. |
3893 | |
4185 | |
3894 | =item EV_HEAP_CACHE_AT |
4186 | =item EV_HEAP_CACHE_AT |
3895 | |
4187 | |
3896 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4188 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3897 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
4189 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3898 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
4190 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3899 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
4191 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3900 | but avoids random read accesses on heap changes. This improves performance |
4192 | but avoids random read accesses on heap changes. This improves performance |
3901 | noticeably with many (hundreds) of watchers. |
4193 | noticeably with many (hundreds) of watchers. |
3902 | |
4194 | |
3903 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4195 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3904 | (disabled). |
4196 | will be C<0>. |
3905 | |
4197 | |
3906 | =item EV_VERIFY |
4198 | =item EV_VERIFY |
3907 | |
4199 | |
3908 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4200 | Controls how much internal verification (see C<ev_verify ()>) will |
3909 | be done: If set to C<0>, no internal verification code will be compiled |
4201 | be done: If set to C<0>, no internal verification code will be compiled |
3910 | in. If set to C<1>, then verification code will be compiled in, but not |
4202 | in. If set to C<1>, then verification code will be compiled in, but not |
3911 | called. If set to C<2>, then the internal verification code will be |
4203 | called. If set to C<2>, then the internal verification code will be |
3912 | called once per loop, which can slow down libev. If set to C<3>, then the |
4204 | called once per loop, which can slow down libev. If set to C<3>, then the |
3913 | verification code will be called very frequently, which will slow down |
4205 | verification code will be called very frequently, which will slow down |
3914 | libev considerably. |
4206 | libev considerably. |
3915 | |
4207 | |
3916 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
4208 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3917 | C<0>. |
4209 | will be C<0>. |
3918 | |
4210 | |
3919 | =item EV_COMMON |
4211 | =item EV_COMMON |
3920 | |
4212 | |
3921 | By default, all watchers have a C<void *data> member. By redefining |
4213 | By default, all watchers have a C<void *data> member. By redefining |
3922 | this macro to a something else you can include more and other types of |
4214 | this macro to something else you can include more and other types of |
3923 | members. You have to define it each time you include one of the files, |
4215 | members. You have to define it each time you include one of the files, |
3924 | though, and it must be identical each time. |
4216 | though, and it must be identical each time. |
3925 | |
4217 | |
3926 | For example, the perl EV module uses something like this: |
4218 | For example, the perl EV module uses something like this: |
3927 | |
4219 | |
… | |
… | |
3980 | file. |
4272 | file. |
3981 | |
4273 | |
3982 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4274 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
3983 | that everybody includes and which overrides some configure choices: |
4275 | that everybody includes and which overrides some configure choices: |
3984 | |
4276 | |
3985 | #define EV_MINIMAL 1 |
4277 | #define EV_FEATURES 8 |
3986 | #define EV_USE_POLL 0 |
4278 | #define EV_USE_SELECT 1 |
3987 | #define EV_MULTIPLICITY 0 |
|
|
3988 | #define EV_PERIODIC_ENABLE 0 |
4279 | #define EV_PREPARE_ENABLE 1 |
|
|
4280 | #define EV_IDLE_ENABLE 1 |
3989 | #define EV_STAT_ENABLE 0 |
4281 | #define EV_SIGNAL_ENABLE 1 |
3990 | #define EV_FORK_ENABLE 0 |
4282 | #define EV_CHILD_ENABLE 1 |
|
|
4283 | #define EV_USE_STDEXCEPT 0 |
3991 | #define EV_CONFIG_H <config.h> |
4284 | #define EV_CONFIG_H <config.h> |
3992 | #define EV_MINPRI 0 |
|
|
3993 | #define EV_MAXPRI 0 |
|
|
3994 | |
4285 | |
3995 | #include "ev++.h" |
4286 | #include "ev++.h" |
3996 | |
4287 | |
3997 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4288 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
3998 | |
4289 | |
… | |
… | |
4129 | userdata *u = ev_userdata (EV_A); |
4420 | userdata *u = ev_userdata (EV_A); |
4130 | pthread_mutex_lock (&u->lock); |
4421 | pthread_mutex_lock (&u->lock); |
4131 | } |
4422 | } |
4132 | |
4423 | |
4133 | The event loop thread first acquires the mutex, and then jumps straight |
4424 | The event loop thread first acquires the mutex, and then jumps straight |
4134 | into C<ev_loop>: |
4425 | into C<ev_run>: |
4135 | |
4426 | |
4136 | void * |
4427 | void * |
4137 | l_run (void *thr_arg) |
4428 | l_run (void *thr_arg) |
4138 | { |
4429 | { |
4139 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4430 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4140 | |
4431 | |
4141 | l_acquire (EV_A); |
4432 | l_acquire (EV_A); |
4142 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4433 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4143 | ev_loop (EV_A_ 0); |
4434 | ev_run (EV_A_ 0); |
4144 | l_release (EV_A); |
4435 | l_release (EV_A); |
4145 | |
4436 | |
4146 | return 0; |
4437 | return 0; |
4147 | } |
4438 | } |
4148 | |
4439 | |
… | |
… | |
4200 | |
4491 | |
4201 | =head3 COROUTINES |
4492 | =head3 COROUTINES |
4202 | |
4493 | |
4203 | Libev is very accommodating to coroutines ("cooperative threads"): |
4494 | Libev is very accommodating to coroutines ("cooperative threads"): |
4204 | libev fully supports nesting calls to its functions from different |
4495 | libev fully supports nesting calls to its functions from different |
4205 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4496 | coroutines (e.g. you can call C<ev_run> on the same loop from two |
4206 | different coroutines, and switch freely between both coroutines running |
4497 | different coroutines, and switch freely between both coroutines running |
4207 | the loop, as long as you don't confuse yourself). The only exception is |
4498 | the loop, as long as you don't confuse yourself). The only exception is |
4208 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4499 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4209 | |
4500 | |
4210 | Care has been taken to ensure that libev does not keep local state inside |
4501 | Care has been taken to ensure that libev does not keep local state inside |
4211 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4502 | C<ev_run>, and other calls do not usually allow for coroutine switches as |
4212 | they do not call any callbacks. |
4503 | they do not call any callbacks. |
4213 | |
4504 | |
4214 | =head2 COMPILER WARNINGS |
4505 | =head2 COMPILER WARNINGS |
4215 | |
4506 | |
4216 | Depending on your compiler and compiler settings, you might get no or a |
4507 | Depending on your compiler and compiler settings, you might get no or a |
… | |
… | |
4227 | maintainable. |
4518 | maintainable. |
4228 | |
4519 | |
4229 | And of course, some compiler warnings are just plain stupid, or simply |
4520 | And of course, some compiler warnings are just plain stupid, or simply |
4230 | wrong (because they don't actually warn about the condition their message |
4521 | wrong (because they don't actually warn about the condition their message |
4231 | seems to warn about). For example, certain older gcc versions had some |
4522 | seems to warn about). For example, certain older gcc versions had some |
4232 | warnings that resulted an extreme number of false positives. These have |
4523 | warnings that resulted in an extreme number of false positives. These have |
4233 | been fixed, but some people still insist on making code warn-free with |
4524 | been fixed, but some people still insist on making code warn-free with |
4234 | such buggy versions. |
4525 | such buggy versions. |
4235 | |
4526 | |
4236 | While libev is written to generate as few warnings as possible, |
4527 | While libev is written to generate as few warnings as possible, |
4237 | "warn-free" code is not a goal, and it is recommended not to build libev |
4528 | "warn-free" code is not a goal, and it is recommended not to build libev |
… | |
… | |
4273 | I suggest using suppression lists. |
4564 | I suggest using suppression lists. |
4274 | |
4565 | |
4275 | |
4566 | |
4276 | =head1 PORTABILITY NOTES |
4567 | =head1 PORTABILITY NOTES |
4277 | |
4568 | |
|
|
4569 | =head2 GNU/LINUX 32 BIT LIMITATIONS |
|
|
4570 | |
|
|
4571 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
4572 | interfaces but I<disables> them by default. |
|
|
4573 | |
|
|
4574 | That means that libev compiled in the default environment doesn't support |
|
|
4575 | files larger than 2GiB or so, which mainly affects C<ev_stat> watchers. |
|
|
4576 | |
|
|
4577 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
4578 | by enabling the large file API, which makes them incompatible with the |
|
|
4579 | standard libev compiled for their system. |
|
|
4580 | |
|
|
4581 | Likewise, libev cannot enable the large file API itself as this would |
|
|
4582 | suddenly make it incompatible to the default compile time environment, |
|
|
4583 | i.e. all programs not using special compile switches. |
|
|
4584 | |
|
|
4585 | =head2 OS/X AND DARWIN BUGS |
|
|
4586 | |
|
|
4587 | The whole thing is a bug if you ask me - basically any system interface |
|
|
4588 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
4589 | OpenGL drivers. |
|
|
4590 | |
|
|
4591 | =head3 C<kqueue> is buggy |
|
|
4592 | |
|
|
4593 | The kqueue syscall is broken in all known versions - most versions support |
|
|
4594 | only sockets, many support pipes. |
|
|
4595 | |
|
|
4596 | Libev tries to work around this by not using C<kqueue> by default on this |
|
|
4597 | rotten platform, but of course you can still ask for it when creating a |
|
|
4598 | loop - embedding a socket-only kqueue loop into a select-based one is |
|
|
4599 | probably going to work well. |
|
|
4600 | |
|
|
4601 | =head3 C<poll> is buggy |
|
|
4602 | |
|
|
4603 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
|
|
4604 | implementation by something calling C<kqueue> internally around the 10.5.6 |
|
|
4605 | release, so now C<kqueue> I<and> C<poll> are broken. |
|
|
4606 | |
|
|
4607 | Libev tries to work around this by not using C<poll> by default on |
|
|
4608 | this rotten platform, but of course you can still ask for it when creating |
|
|
4609 | a loop. |
|
|
4610 | |
|
|
4611 | =head3 C<select> is buggy |
|
|
4612 | |
|
|
4613 | All that's left is C<select>, and of course Apple found a way to fuck this |
|
|
4614 | one up as well: On OS/X, C<select> actively limits the number of file |
|
|
4615 | descriptors you can pass in to 1024 - your program suddenly crashes when |
|
|
4616 | you use more. |
|
|
4617 | |
|
|
4618 | There is an undocumented "workaround" for this - defining |
|
|
4619 | C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should> |
|
|
4620 | work on OS/X. |
|
|
4621 | |
|
|
4622 | =head2 SOLARIS PROBLEMS AND WORKAROUNDS |
|
|
4623 | |
|
|
4624 | =head3 C<errno> reentrancy |
|
|
4625 | |
|
|
4626 | The default compile environment on Solaris is unfortunately so |
|
|
4627 | thread-unsafe that you can't even use components/libraries compiled |
|
|
4628 | without C<-D_REENTRANT> in a threaded program, which, of course, isn't |
|
|
4629 | defined by default. A valid, if stupid, implementation choice. |
|
|
4630 | |
|
|
4631 | If you want to use libev in threaded environments you have to make sure |
|
|
4632 | it's compiled with C<_REENTRANT> defined. |
|
|
4633 | |
|
|
4634 | =head3 Event port backend |
|
|
4635 | |
|
|
4636 | The scalable event interface for Solaris is called "event |
|
|
4637 | ports". Unfortunately, this mechanism is very buggy in all major |
|
|
4638 | releases. If you run into high CPU usage, your program freezes or you get |
|
|
4639 | a large number of spurious wakeups, make sure you have all the relevant |
|
|
4640 | and latest kernel patches applied. No, I don't know which ones, but there |
|
|
4641 | are multiple ones to apply, and afterwards, event ports actually work |
|
|
4642 | great. |
|
|
4643 | |
|
|
4644 | If you can't get it to work, you can try running the program by setting |
|
|
4645 | the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and |
|
|
4646 | C<select> backends. |
|
|
4647 | |
|
|
4648 | =head2 AIX POLL BUG |
|
|
4649 | |
|
|
4650 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
|
|
4651 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
4652 | compiled in), which normally isn't a big problem as C<select> works fine |
|
|
4653 | with large bitsets on AIX, and AIX is dead anyway. |
|
|
4654 | |
4278 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4655 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
|
|
4656 | |
|
|
4657 | =head3 General issues |
4279 | |
4658 | |
4280 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4659 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4281 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4660 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4282 | model. Libev still offers limited functionality on this platform in |
4661 | model. Libev still offers limited functionality on this platform in |
4283 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4662 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4284 | descriptors. This only applies when using Win32 natively, not when using |
4663 | descriptors. This only applies when using Win32 natively, not when using |
4285 | e.g. cygwin. |
4664 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
4665 | as every compielr comes with a slightly differently broken/incompatible |
|
|
4666 | environment. |
4286 | |
4667 | |
4287 | Lifting these limitations would basically require the full |
4668 | Lifting these limitations would basically require the full |
4288 | re-implementation of the I/O system. If you are into these kinds of |
4669 | re-implementation of the I/O system. If you are into this kind of thing, |
4289 | things, then note that glib does exactly that for you in a very portable |
4670 | then note that glib does exactly that for you in a very portable way (note |
4290 | way (note also that glib is the slowest event library known to man). |
4671 | also that glib is the slowest event library known to man). |
4291 | |
4672 | |
4292 | There is no supported compilation method available on windows except |
4673 | There is no supported compilation method available on windows except |
4293 | embedding it into other applications. |
4674 | embedding it into other applications. |
4294 | |
4675 | |
4295 | Sensible signal handling is officially unsupported by Microsoft - libev |
4676 | Sensible signal handling is officially unsupported by Microsoft - libev |
… | |
… | |
4323 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4704 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4324 | |
4705 | |
4325 | #include "evwrap.h" |
4706 | #include "evwrap.h" |
4326 | #include "ev.c" |
4707 | #include "ev.c" |
4327 | |
4708 | |
4328 | =over 4 |
|
|
4329 | |
|
|
4330 | =item The winsocket select function |
4709 | =head3 The winsocket C<select> function |
4331 | |
4710 | |
4332 | The winsocket C<select> function doesn't follow POSIX in that it |
4711 | The winsocket C<select> function doesn't follow POSIX in that it |
4333 | requires socket I<handles> and not socket I<file descriptors> (it is |
4712 | requires socket I<handles> and not socket I<file descriptors> (it is |
4334 | also extremely buggy). This makes select very inefficient, and also |
4713 | also extremely buggy). This makes select very inefficient, and also |
4335 | requires a mapping from file descriptors to socket handles (the Microsoft |
4714 | requires a mapping from file descriptors to socket handles (the Microsoft |
… | |
… | |
4344 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4723 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4345 | |
4724 | |
4346 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4725 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4347 | complexity in the O(n²) range when using win32. |
4726 | complexity in the O(n²) range when using win32. |
4348 | |
4727 | |
4349 | =item Limited number of file descriptors |
4728 | =head3 Limited number of file descriptors |
4350 | |
4729 | |
4351 | Windows has numerous arbitrary (and low) limits on things. |
4730 | Windows has numerous arbitrary (and low) limits on things. |
4352 | |
4731 | |
4353 | Early versions of winsocket's select only supported waiting for a maximum |
4732 | Early versions of winsocket's select only supported waiting for a maximum |
4354 | of C<64> handles (probably owning to the fact that all windows kernels |
4733 | of C<64> handles (probably owning to the fact that all windows kernels |
… | |
… | |
4369 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4748 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4370 | (depending on windows version and/or the phase of the moon). To get more, |
4749 | (depending on windows version and/or the phase of the moon). To get more, |
4371 | you need to wrap all I/O functions and provide your own fd management, but |
4750 | you need to wrap all I/O functions and provide your own fd management, but |
4372 | the cost of calling select (O(n²)) will likely make this unworkable. |
4751 | the cost of calling select (O(n²)) will likely make this unworkable. |
4373 | |
4752 | |
4374 | =back |
|
|
4375 | |
|
|
4376 | =head2 PORTABILITY REQUIREMENTS |
4753 | =head2 PORTABILITY REQUIREMENTS |
4377 | |
4754 | |
4378 | In addition to a working ISO-C implementation and of course the |
4755 | In addition to a working ISO-C implementation and of course the |
4379 | backend-specific APIs, libev relies on a few additional extensions: |
4756 | backend-specific APIs, libev relies on a few additional extensions: |
4380 | |
4757 | |
… | |
… | |
4386 | Libev assumes not only that all watcher pointers have the same internal |
4763 | Libev assumes not only that all watcher pointers have the same internal |
4387 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
4764 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
4388 | assumes that the same (machine) code can be used to call any watcher |
4765 | assumes that the same (machine) code can be used to call any watcher |
4389 | callback: The watcher callbacks have different type signatures, but libev |
4766 | callback: The watcher callbacks have different type signatures, but libev |
4390 | calls them using an C<ev_watcher *> internally. |
4767 | calls them using an C<ev_watcher *> internally. |
|
|
4768 | |
|
|
4769 | =item pointer accesses must be thread-atomic |
|
|
4770 | |
|
|
4771 | Accessing a pointer value must be atomic, it must both be readable and |
|
|
4772 | writable in one piece - this is the case on all current architectures. |
4391 | |
4773 | |
4392 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
4774 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
4393 | |
4775 | |
4394 | The type C<sig_atomic_t volatile> (or whatever is defined as |
4776 | The type C<sig_atomic_t volatile> (or whatever is defined as |
4395 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
4777 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
… | |
… | |
4418 | watchers. |
4800 | watchers. |
4419 | |
4801 | |
4420 | =item C<double> must hold a time value in seconds with enough accuracy |
4802 | =item C<double> must hold a time value in seconds with enough accuracy |
4421 | |
4803 | |
4422 | The type C<double> is used to represent timestamps. It is required to |
4804 | The type C<double> is used to represent timestamps. It is required to |
4423 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4805 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
4424 | enough for at least into the year 4000. This requirement is fulfilled by |
4806 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
4807 | (the design goal for libev). This requirement is overfulfilled by |
4425 | implementations implementing IEEE 754, which is basically all existing |
4808 | implementations using IEEE 754, which is basically all existing ones. With |
4426 | ones. With IEEE 754 doubles, you get microsecond accuracy until at least |
4809 | IEEE 754 doubles, you get microsecond accuracy until at least 2200. |
4427 | 2200. |
|
|
4428 | |
4810 | |
4429 | =back |
4811 | =back |
4430 | |
4812 | |
4431 | If you know of other additional requirements drop me a note. |
4813 | If you know of other additional requirements drop me a note. |
4432 | |
4814 | |
… | |
… | |
4500 | involves iterating over all running async watchers or all signal numbers. |
4882 | involves iterating over all running async watchers or all signal numbers. |
4501 | |
4883 | |
4502 | =back |
4884 | =back |
4503 | |
4885 | |
4504 | |
4886 | |
|
|
4887 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
|
|
4888 | |
|
|
4889 | The major version 4 introduced some incompatible changes to the API. |
|
|
4890 | |
|
|
4891 | At the moment, the C<ev.h> header file provides compatibility definitions |
|
|
4892 | for all changes, so most programs should still compile. The compatibility |
|
|
4893 | layer might be removed in later versions of libev, so better update to the |
|
|
4894 | new API early than late. |
|
|
4895 | |
|
|
4896 | =over 4 |
|
|
4897 | |
|
|
4898 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
4899 | |
|
|
4900 | The backward compatibility mechanism can be controlled by |
|
|
4901 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
4902 | section. |
|
|
4903 | |
|
|
4904 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
|
|
4905 | |
|
|
4906 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
|
|
4907 | |
|
|
4908 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
4909 | ev_loop_fork (EV_DEFAULT); |
|
|
4910 | |
|
|
4911 | =item function/symbol renames |
|
|
4912 | |
|
|
4913 | A number of functions and symbols have been renamed: |
|
|
4914 | |
|
|
4915 | ev_loop => ev_run |
|
|
4916 | EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
4917 | EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
4918 | |
|
|
4919 | ev_unloop => ev_break |
|
|
4920 | EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
4921 | EVUNLOOP_ONE => EVBREAK_ONE |
|
|
4922 | EVUNLOOP_ALL => EVBREAK_ALL |
|
|
4923 | |
|
|
4924 | EV_TIMEOUT => EV_TIMER |
|
|
4925 | |
|
|
4926 | ev_loop_count => ev_iteration |
|
|
4927 | ev_loop_depth => ev_depth |
|
|
4928 | ev_loop_verify => ev_verify |
|
|
4929 | |
|
|
4930 | Most functions working on C<struct ev_loop> objects don't have an |
|
|
4931 | C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and |
|
|
4932 | associated constants have been renamed to not collide with the C<struct |
|
|
4933 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
|
|
4934 | as all other watcher types. Note that C<ev_loop_fork> is still called |
|
|
4935 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
|
|
4936 | typedef. |
|
|
4937 | |
|
|
4938 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
4939 | |
|
|
4940 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
4941 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
4942 | and work, but the library code will of course be larger. |
|
|
4943 | |
|
|
4944 | =back |
|
|
4945 | |
|
|
4946 | |
4505 | =head1 GLOSSARY |
4947 | =head1 GLOSSARY |
4506 | |
4948 | |
4507 | =over 4 |
4949 | =over 4 |
4508 | |
4950 | |
4509 | =item active |
4951 | =item active |
4510 | |
4952 | |
4511 | A watcher is active as long as it has been started (has been attached to |
4953 | A watcher is active as long as it has been started and not yet stopped. |
4512 | an event loop) but not yet stopped (disassociated from the event loop). |
4954 | See L<WATCHER STATES> for details. |
4513 | |
4955 | |
4514 | =item application |
4956 | =item application |
4515 | |
4957 | |
4516 | In this document, an application is whatever is using libev. |
4958 | In this document, an application is whatever is using libev. |
|
|
4959 | |
|
|
4960 | =item backend |
|
|
4961 | |
|
|
4962 | The part of the code dealing with the operating system interfaces. |
4517 | |
4963 | |
4518 | =item callback |
4964 | =item callback |
4519 | |
4965 | |
4520 | The address of a function that is called when some event has been |
4966 | The address of a function that is called when some event has been |
4521 | detected. Callbacks are being passed the event loop, the watcher that |
4967 | detected. Callbacks are being passed the event loop, the watcher that |
4522 | received the event, and the actual event bitset. |
4968 | received the event, and the actual event bitset. |
4523 | |
4969 | |
4524 | =item callback invocation |
4970 | =item callback/watcher invocation |
4525 | |
4971 | |
4526 | The act of calling the callback associated with a watcher. |
4972 | The act of calling the callback associated with a watcher. |
4527 | |
4973 | |
4528 | =item event |
4974 | =item event |
4529 | |
4975 | |
4530 | A change of state of some external event, such as data now being available |
4976 | A change of state of some external event, such as data now being available |
4531 | for reading on a file descriptor, time having passed or simply not having |
4977 | for reading on a file descriptor, time having passed or simply not having |
4532 | any other events happening anymore. |
4978 | any other events happening anymore. |
4533 | |
4979 | |
4534 | In libev, events are represented as single bits (such as C<EV_READ> or |
4980 | In libev, events are represented as single bits (such as C<EV_READ> or |
4535 | C<EV_TIMEOUT>). |
4981 | C<EV_TIMER>). |
4536 | |
4982 | |
4537 | =item event library |
4983 | =item event library |
4538 | |
4984 | |
4539 | A software package implementing an event model and loop. |
4985 | A software package implementing an event model and loop. |
4540 | |
4986 | |
… | |
… | |
4548 | The model used to describe how an event loop handles and processes |
4994 | The model used to describe how an event loop handles and processes |
4549 | watchers and events. |
4995 | watchers and events. |
4550 | |
4996 | |
4551 | =item pending |
4997 | =item pending |
4552 | |
4998 | |
4553 | A watcher is pending as soon as the corresponding event has been detected, |
4999 | A watcher is pending as soon as the corresponding event has been |
4554 | and stops being pending as soon as the watcher will be invoked or its |
5000 | detected. See L<WATCHER STATES> for details. |
4555 | pending status is explicitly cleared by the application. |
|
|
4556 | |
|
|
4557 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4558 | its pending status. |
|
|
4559 | |
5001 | |
4560 | =item real time |
5002 | =item real time |
4561 | |
5003 | |
4562 | The physical time that is observed. It is apparently strictly monotonic :) |
5004 | The physical time that is observed. It is apparently strictly monotonic :) |
4563 | |
5005 | |
… | |
… | |
4570 | =item watcher |
5012 | =item watcher |
4571 | |
5013 | |
4572 | A data structure that describes interest in certain events. Watchers need |
5014 | A data structure that describes interest in certain events. Watchers need |
4573 | to be started (attached to an event loop) before they can receive events. |
5015 | to be started (attached to an event loop) before they can receive events. |
4574 | |
5016 | |
4575 | =item watcher invocation |
|
|
4576 | |
|
|
4577 | The act of calling the callback associated with a watcher. |
|
|
4578 | |
|
|
4579 | =back |
5017 | =back |
4580 | |
5018 | |
4581 | =head1 AUTHOR |
5019 | =head1 AUTHOR |
4582 | |
5020 | |
4583 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
5021 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
|
|
5022 | Magnusson and Emanuele Giaquinta. |
4584 | |
5023 | |