… | |
… | |
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, |
… | |
… | |
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) |
415 | |
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). |
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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). |
420 | |
464 | |
421 | The epoll mechanism deserves honorable mention as the most misdesigned |
465 | The epoll mechanism deserves honorable mention as the most misdesigned |
422 | of the more advanced event mechanisms: mere annoyances include silently |
466 | of the more advanced event mechanisms: mere annoyances include silently |
423 | dropping file descriptors, requiring a system call per change per file |
467 | dropping file descriptors, requiring a system call per change per file |
424 | descriptor (and unnecessary guessing of parameters), problems with dup and |
468 | descriptor (and unnecessary guessing of parameters), problems with dup, |
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469 | returning before the timeout value requiring additional iterations and so |
425 | so on. The biggest issue is fork races, however - if a program forks then |
470 | on. The biggest issue is fork races, however - if a program forks then |
426 | I<both> parent and child process have to recreate the epoll set, which can |
471 | I<both> parent and child process have to recreate the epoll set, which can |
427 | take considerable time (one syscall per file descriptor) and is of course |
472 | take considerable time (one syscall per file descriptor) and is of course |
428 | hard to detect. |
473 | hard to detect. |
429 | |
474 | |
430 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, but |
475 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, but |
431 | of course I<doesn't>, and epoll just loves to report events for totally |
476 | 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 |
477 | I<different> file descriptors (even already closed ones, so one cannot |
433 | even remove them from the set) than registered in the set (especially |
478 | even remove them from the set) than registered in the set (especially |
434 | on SMP systems). Libev tries to counter these spurious notifications by |
479 | on SMP systems). Libev tries to counter these spurious notifications by |
435 | employing an additional generation counter and comparing that against the |
480 | employing an additional generation counter and comparing that against the |
436 | events to filter out spurious ones, recreating the set when required. |
481 | events to filter out spurious ones, recreating the set when required. Last |
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482 | not least, it also refuses to work with some file descriptors which work |
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483 | perfectly fine with C<select> (files, many character devices...). |
437 | |
484 | |
438 | While stopping, setting and starting an I/O watcher in the same iteration |
485 | 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 |
486 | 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 |
487 | 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 |
488 | 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, |
586 | 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 |
587 | 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 |
588 | here). If none are specified, all backends in C<ev_recommended_backends |
542 | ()> will be tried. |
589 | ()> will be tried. |
543 | |
590 | |
544 | Example: This is the most typical usage. |
|
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545 | |
|
|
546 | if (!ev_default_loop (0)) |
|
|
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 |
|
|
555 | used if available (warning, breaks stuff, best use only with your own |
|
|
556 | private event loop and only if you know the OS supports your types of |
|
|
557 | fds): |
|
|
558 | |
|
|
559 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
560 | |
|
|
561 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
|
|
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. |
591 | Example: Try to create a event loop that uses epoll and nothing else. |
573 | |
592 | |
574 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
593 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
575 | if (!epoller) |
594 | if (!epoller) |
576 | fatal ("no epoll found here, maybe it hides under your chair"); |
595 | fatal ("no epoll found here, maybe it hides under your chair"); |
577 | |
596 | |
|
|
597 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
598 | used if available. |
|
|
599 | |
|
|
600 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
601 | |
578 | =item ev_default_destroy () |
602 | =item ev_loop_destroy (loop) |
579 | |
603 | |
580 | Destroys the default loop again (frees all memory and kernel state |
604 | 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 |
605 | 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 |
606 | 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> |
607 | responsibility to either stop all watchers cleanly yourself I<before> |
584 | calling this function, or cope with the fact afterwards (which is usually |
608 | 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 |
609 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
… | |
… | |
587 | |
611 | |
588 | Note that certain global state, such as signal state (and installed signal |
612 | 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 |
613 | handlers), will not be freed by this function, and related watchers (such |
590 | as signal and child watchers) would need to be stopped manually. |
614 | as signal and child watchers) would need to be stopped manually. |
591 | |
615 | |
592 | In general it is not advisable to call this function except in the |
616 | This function is normally used on loop objects allocated by |
593 | rare occasion where you really need to free e.g. the signal handling |
617 | C<ev_loop_new>, but it can also be used on the default loop returned by |
|
|
618 | C<ev_default_loop>, in which case it is not thread-safe. |
|
|
619 | |
|
|
620 | Note that it is not advisable to call this function on the default loop |
|
|
621 | 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 |
622 | 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>). |
623 | and C<ev_loop_destroy>. |
596 | |
624 | |
597 | =item ev_loop_destroy (loop) |
625 | =item ev_loop_fork (loop) |
598 | |
626 | |
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 |
627 | 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 |
628 | 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 |
629 | 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 |
630 | 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 |
631 | child before resuming or calling C<ev_run>. |
609 | functions, and it will only take effect at the next C<ev_loop> iteration. |
632 | |
|
|
633 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
|
|
634 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
|
|
635 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
|
|
636 | during fork. |
610 | |
637 | |
611 | On the other hand, you only need to call this function in the child |
638 | 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 |
639 | 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. |
640 | you just fork+exec or create a new loop in the child, you don't have to |
|
|
641 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
|
|
642 | difference, but libev will usually detect this case on its own and do a |
|
|
643 | costly reset of the backend). |
614 | |
644 | |
615 | The function itself is quite fast and it's usually not a problem to call |
645 | 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 |
646 | it just in case after a fork. |
617 | quite nicely into a call to C<pthread_atfork>: |
|
|
618 | |
647 | |
|
|
648 | Example: Automate calling C<ev_loop_fork> on the default loop when |
|
|
649 | using pthreads. |
|
|
650 | |
|
|
651 | static void |
|
|
652 | post_fork_child (void) |
|
|
653 | { |
|
|
654 | ev_loop_fork (EV_DEFAULT); |
|
|
655 | } |
|
|
656 | |
|
|
657 | ... |
619 | pthread_atfork (0, 0, ev_default_fork); |
658 | 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 | |
659 | |
628 | =item int ev_is_default_loop (loop) |
660 | =item int ev_is_default_loop (loop) |
629 | |
661 | |
630 | Returns true when the given loop is, in fact, the default loop, and false |
662 | Returns true when the given loop is, in fact, the default loop, and false |
631 | otherwise. |
663 | otherwise. |
632 | |
664 | |
633 | =item unsigned int ev_loop_count (loop) |
665 | =item unsigned int ev_iteration (loop) |
634 | |
666 | |
635 | Returns the count of loop iterations for the loop, which is identical to |
667 | 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 |
668 | to the number of times libev did poll for new events. It starts at C<0> |
637 | happily wraps around with enough iterations. |
669 | and happily wraps around with enough iterations. |
638 | |
670 | |
639 | This value can sometimes be useful as a generation counter of sorts (it |
671 | 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 |
672 | "ticks" the number of loop iterations), as it roughly corresponds with |
641 | C<ev_prepare> and C<ev_check> calls. |
673 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
|
|
674 | prepare and check phases. |
642 | |
675 | |
643 | =item unsigned int ev_loop_depth (loop) |
676 | =item unsigned int ev_depth (loop) |
644 | |
677 | |
645 | Returns the number of times C<ev_loop> was entered minus the number of |
678 | 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. |
679 | times C<ev_run> was exited, in other words, the recursion depth. |
647 | |
680 | |
648 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
681 | 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), |
682 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
650 | in which case it is higher. |
683 | in which case it is higher. |
651 | |
684 | |
652 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
685 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread |
653 | etc.), doesn't count as exit. |
686 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
|
|
687 | ungentleman-like behaviour unless it's really convenient. |
654 | |
688 | |
655 | =item unsigned int ev_backend (loop) |
689 | =item unsigned int ev_backend (loop) |
656 | |
690 | |
657 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
691 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
658 | use. |
692 | use. |
… | |
… | |
667 | |
701 | |
668 | =item ev_now_update (loop) |
702 | =item ev_now_update (loop) |
669 | |
703 | |
670 | Establishes the current time by querying the kernel, updating the time |
704 | 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 |
705 | returned by C<ev_now ()> in the progress. This is a costly operation and |
672 | is usually done automatically within C<ev_loop ()>. |
706 | is usually done automatically within C<ev_run ()>. |
673 | |
707 | |
674 | This function is rarely useful, but when some event callback runs for a |
708 | 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 |
709 | very long time without entering the event loop, updating libev's idea of |
676 | the current time is a good idea. |
710 | the current time is a good idea. |
677 | |
711 | |
… | |
… | |
679 | |
713 | |
680 | =item ev_suspend (loop) |
714 | =item ev_suspend (loop) |
681 | |
715 | |
682 | =item ev_resume (loop) |
716 | =item ev_resume (loop) |
683 | |
717 | |
684 | These two functions suspend and resume a loop, for use when the loop is |
718 | 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. |
719 | loop is not used for a while and timeouts should not be processed. |
686 | |
720 | |
687 | A typical use case would be an interactive program such as a game: When |
721 | 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 |
722 | 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 |
723 | 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> |
724 | the program was suspended. This can be achieved by calling C<ev_suspend> |
… | |
… | |
692 | C<ev_resume> directly afterwards to resume timer processing. |
726 | C<ev_resume> directly afterwards to resume timer processing. |
693 | |
727 | |
694 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
728 | 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 |
729 | 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 |
730 | will be rescheduled (that is, they will lose any events that would have |
697 | occured while suspended). |
731 | occurred while suspended). |
698 | |
732 | |
699 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
733 | 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> |
734 | 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>. |
735 | without a previous call to C<ev_suspend>. |
702 | |
736 | |
703 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
737 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
704 | event loop time (see C<ev_now_update>). |
738 | event loop time (see C<ev_now_update>). |
705 | |
739 | |
706 | =item ev_loop (loop, int flags) |
740 | =item ev_run (loop, int flags) |
707 | |
741 | |
708 | Finally, this is it, the event handler. This function usually is called |
742 | 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 |
743 | after you have initialised all your watchers and you want to start |
710 | events. |
744 | handling events. It will ask the operating system for any new events, call |
|
|
745 | the watcher callbacks, an then repeat the whole process indefinitely: This |
|
|
746 | is why event loops are called I<loops>. |
711 | |
747 | |
712 | If the flags argument is specified as C<0>, it will not return until |
748 | 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. |
749 | until either no event watchers are active anymore or C<ev_break> was |
|
|
750 | called. |
714 | |
751 | |
715 | Please note that an explicit C<ev_unloop> is usually better than |
752 | 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 |
753 | relying on all watchers to be stopped when deciding when a program has |
717 | finished (especially in interactive programs), but having a program |
754 | finished (especially in interactive programs), but having a program |
718 | that automatically loops as long as it has to and no longer by virtue |
755 | 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 |
756 | of relying on its watchers stopping correctly, that is truly a thing of |
720 | beauty. |
757 | beauty. |
721 | |
758 | |
722 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
759 | 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 |
760 | 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 |
761 | block your process in case there are no events and will return after one |
725 | the loop. |
762 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
763 | events while doing lengthy calculations, to keep the program responsive. |
726 | |
764 | |
727 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
765 | 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 |
766 | 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 |
767 | 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 |
768 | 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 |
769 | user-registered callback will be called), and will return after one |
732 | iteration of the loop. |
770 | iteration of the loop. |
733 | |
771 | |
734 | This is useful if you are waiting for some external event in conjunction |
772 | 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 |
773 | 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 |
774 | 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. |
775 | usually a better approach for this kind of thing. |
738 | |
776 | |
739 | Here are the gory details of what C<ev_loop> does: |
777 | Here are the gory details of what C<ev_run> does: |
740 | |
778 | |
|
|
779 | - Increment loop depth. |
|
|
780 | - Reset the ev_break status. |
741 | - Before the first iteration, call any pending watchers. |
781 | - Before the first iteration, call any pending watchers. |
|
|
782 | LOOP: |
742 | * If EVFLAG_FORKCHECK was used, check for a fork. |
783 | - If EVFLAG_FORKCHECK was used, check for a fork. |
743 | - If a fork was detected (by any means), queue and call all fork watchers. |
784 | - If a fork was detected (by any means), queue and call all fork watchers. |
744 | - Queue and call all prepare watchers. |
785 | - Queue and call all prepare watchers. |
|
|
786 | - If ev_break was called, goto FINISH. |
745 | - If we have been forked, detach and recreate the kernel state |
787 | - If we have been forked, detach and recreate the kernel state |
746 | as to not disturb the other process. |
788 | as to not disturb the other process. |
747 | - Update the kernel state with all outstanding changes. |
789 | - Update the kernel state with all outstanding changes. |
748 | - Update the "event loop time" (ev_now ()). |
790 | - Update the "event loop time" (ev_now ()). |
749 | - Calculate for how long to sleep or block, if at all |
791 | - Calculate for how long to sleep or block, if at all |
750 | (active idle watchers, EVLOOP_NONBLOCK or not having |
792 | (active idle watchers, EVRUN_NOWAIT or not having |
751 | any active watchers at all will result in not sleeping). |
793 | any active watchers at all will result in not sleeping). |
752 | - Sleep if the I/O and timer collect interval say so. |
794 | - Sleep if the I/O and timer collect interval say so. |
|
|
795 | - Increment loop iteration counter. |
753 | - Block the process, waiting for any events. |
796 | - Block the process, waiting for any events. |
754 | - Queue all outstanding I/O (fd) events. |
797 | - Queue all outstanding I/O (fd) events. |
755 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
798 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
756 | - Queue all expired timers. |
799 | - Queue all expired timers. |
757 | - Queue all expired periodics. |
800 | - Queue all expired periodics. |
758 | - Unless any events are pending now, queue all idle watchers. |
801 | - Queue all idle watchers with priority higher than that of pending events. |
759 | - Queue all check watchers. |
802 | - Queue all check watchers. |
760 | - Call all queued watchers in reverse order (i.e. check watchers first). |
803 | - 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 |
804 | Signals and child watchers are implemented as I/O watchers, and will |
762 | be handled here by queueing them when their watcher gets executed. |
805 | be handled here by queueing them when their watcher gets executed. |
763 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
806 | - If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
764 | were used, or there are no active watchers, return, otherwise |
807 | were used, or there are no active watchers, goto FINISH, otherwise |
765 | continue with step *. |
808 | continue with step LOOP. |
|
|
809 | FINISH: |
|
|
810 | - Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
811 | - Decrement the loop depth. |
|
|
812 | - Return. |
766 | |
813 | |
767 | Example: Queue some jobs and then loop until no events are outstanding |
814 | Example: Queue some jobs and then loop until no events are outstanding |
768 | anymore. |
815 | anymore. |
769 | |
816 | |
770 | ... queue jobs here, make sure they register event watchers as long |
817 | ... 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..) |
818 | ... as they still have work to do (even an idle watcher will do..) |
772 | ev_loop (my_loop, 0); |
819 | ev_run (my_loop, 0); |
773 | ... jobs done or somebody called unloop. yeah! |
820 | ... jobs done or somebody called unloop. yeah! |
774 | |
821 | |
775 | =item ev_unloop (loop, how) |
822 | =item ev_break (loop, how) |
776 | |
823 | |
777 | Can be used to make a call to C<ev_loop> return early (but only after it |
824 | 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 |
825 | 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 |
826 | 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. |
827 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
781 | |
828 | |
782 | This "unloop state" will be cleared when entering C<ev_loop> again. |
829 | This "break state" will be cleared when entering C<ev_run> again. |
783 | |
830 | |
784 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
831 | It is safe to call C<ev_break> from outside any C<ev_run> calls, too. |
785 | |
832 | |
786 | =item ev_ref (loop) |
833 | =item ev_ref (loop) |
787 | |
834 | |
788 | =item ev_unref (loop) |
835 | =item ev_unref (loop) |
789 | |
836 | |
790 | Ref/unref can be used to add or remove a reference count on the event |
837 | 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 |
838 | 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. |
839 | count is nonzero, C<ev_run> will not return on its own. |
793 | |
840 | |
794 | If you have a watcher you never unregister that should not keep C<ev_loop> |
841 | 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 |
842 | unregister, but that nevertheless should not keep C<ev_run> from |
|
|
843 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
796 | stopping it. |
844 | before stopping it. |
797 | |
845 | |
798 | As an example, libev itself uses this for its internal signal pipe: It |
846 | 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 |
847 | 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 |
848 | 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 |
849 | 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 |
850 | 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 |
851 | 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 |
852 | 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> |
853 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
806 | in the callback). |
854 | in the callback). |
807 | |
855 | |
808 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
856 | Example: Create a signal watcher, but keep it from keeping C<ev_run> |
809 | running when nothing else is active. |
857 | running when nothing else is active. |
810 | |
858 | |
811 | ev_signal exitsig; |
859 | ev_signal exitsig; |
812 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
860 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
813 | ev_signal_start (loop, &exitsig); |
861 | ev_signal_start (loop, &exitsig); |
… | |
… | |
858 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
906 | 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 |
907 | 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 |
908 | 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 |
909 | 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, |
910 | 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). |
911 | then you can't do more than 100 transactions per second). |
864 | |
912 | |
865 | Setting the I<timeout collect interval> can improve the opportunity for |
913 | Setting the I<timeout collect interval> can improve the opportunity for |
866 | saving power, as the program will "bundle" timer callback invocations that |
914 | 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 |
915 | 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 |
916 | times the process sleeps and wakes up again. Another useful technique to |
… | |
… | |
876 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
924 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
877 | |
925 | |
878 | =item ev_invoke_pending (loop) |
926 | =item ev_invoke_pending (loop) |
879 | |
927 | |
880 | This call will simply invoke all pending watchers while resetting their |
928 | This call will simply invoke all pending watchers while resetting their |
881 | pending state. Normally, C<ev_loop> does this automatically when required, |
929 | pending state. Normally, C<ev_run> does this automatically when required, |
882 | but when overriding the invoke callback this call comes handy. |
930 | but when overriding the invoke callback this call comes handy. This |
|
|
931 | function can be invoked from a watcher - this can be useful for example |
|
|
932 | when you want to do some lengthy calculation and want to pass further |
|
|
933 | event handling to another thread (you still have to make sure only one |
|
|
934 | thread executes within C<ev_invoke_pending> or C<ev_run> of course). |
883 | |
935 | |
884 | =item int ev_pending_count (loop) |
936 | =item int ev_pending_count (loop) |
885 | |
937 | |
886 | Returns the number of pending watchers - zero indicates that no watchers |
938 | Returns the number of pending watchers - zero indicates that no watchers |
887 | are pending. |
939 | are pending. |
888 | |
940 | |
889 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
941 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
890 | |
942 | |
891 | This overrides the invoke pending functionality of the loop: Instead of |
943 | 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 |
944 | 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 |
945 | this callback instead. This is useful, for example, when you want to |
894 | invoke the actual watchers inside another context (another thread etc.). |
946 | invoke the actual watchers inside another context (another thread etc.). |
895 | |
947 | |
896 | If you want to reset the callback, use C<ev_invoke_pending> as new |
948 | If you want to reset the callback, use C<ev_invoke_pending> as new |
897 | callback. |
949 | callback. |
… | |
… | |
900 | |
952 | |
901 | Sometimes you want to share the same loop between multiple threads. This |
953 | 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 |
954 | can be done relatively simply by putting mutex_lock/unlock calls around |
903 | each call to a libev function. |
955 | each call to a libev function. |
904 | |
956 | |
905 | However, C<ev_loop> can run an indefinite time, so it is not feasible to |
957 | 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 |
958 | 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> |
959 | loop via C<ev_break> and C<av_async_send>, another way is to set these |
908 | and I<acquire> callbacks on the loop. |
960 | I<release> and I<acquire> callbacks on the loop. |
909 | |
961 | |
910 | When set, then C<release> will be called just before the thread is |
962 | 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 |
963 | suspended waiting for new events, and C<acquire> is called just |
912 | afterwards. |
964 | afterwards. |
913 | |
965 | |
… | |
… | |
916 | |
968 | |
917 | While event loop modifications are allowed between invocations of |
969 | While event loop modifications are allowed between invocations of |
918 | C<release> and C<acquire> (that's their only purpose after all), no |
970 | 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 |
971 | 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 |
972 | 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 |
973 | 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. |
974 | to take note of any changes you made. |
923 | |
975 | |
924 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
976 | In theory, threads executing C<ev_run> will be async-cancel safe between |
925 | invocations of C<release> and C<acquire>. |
977 | invocations of C<release> and C<acquire>. |
926 | |
978 | |
927 | See also the locking example in the C<THREADS> section later in this |
979 | See also the locking example in the C<THREADS> section later in this |
928 | document. |
980 | document. |
929 | |
981 | |
… | |
… | |
938 | These two functions can be used to associate arbitrary data with a loop, |
990 | 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 |
991 | 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 |
992 | C<acquire> callbacks described above, but of course can be (ab-)used for |
941 | any other purpose as well. |
993 | any other purpose as well. |
942 | |
994 | |
943 | =item ev_loop_verify (loop) |
995 | =item ev_verify (loop) |
944 | |
996 | |
945 | This function only does something when C<EV_VERIFY> support has been |
997 | 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 |
998 | 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 |
999 | 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 |
1000 | is found to be inconsistent, it will print an error message to standard |
… | |
… | |
959 | |
1011 | |
960 | In the following description, uppercase C<TYPE> in names stands for the |
1012 | 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 |
1013 | 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. |
1014 | watchers and C<ev_io_start> for I/O watchers. |
963 | |
1015 | |
964 | A watcher is a structure that you create and register to record your |
1016 | 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 |
1017 | 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: |
1018 | to wait for STDIN to become readable, you would create an C<ev_io> watcher |
|
|
1019 | for that: |
967 | |
1020 | |
968 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
1021 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
969 | { |
1022 | { |
970 | ev_io_stop (w); |
1023 | ev_io_stop (w); |
971 | ev_unloop (loop, EVUNLOOP_ALL); |
1024 | ev_break (loop, EVBREAK_ALL); |
972 | } |
1025 | } |
973 | |
1026 | |
974 | struct ev_loop *loop = ev_default_loop (0); |
1027 | struct ev_loop *loop = ev_default_loop (0); |
975 | |
1028 | |
976 | ev_io stdin_watcher; |
1029 | ev_io stdin_watcher; |
977 | |
1030 | |
978 | ev_init (&stdin_watcher, my_cb); |
1031 | ev_init (&stdin_watcher, my_cb); |
979 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1032 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
980 | ev_io_start (loop, &stdin_watcher); |
1033 | ev_io_start (loop, &stdin_watcher); |
981 | |
1034 | |
982 | ev_loop (loop, 0); |
1035 | ev_run (loop, 0); |
983 | |
1036 | |
984 | As you can see, you are responsible for allocating the memory for your |
1037 | 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 |
1038 | watcher structures (and it is I<usually> a bad idea to do this on the |
986 | stack). |
1039 | stack). |
987 | |
1040 | |
988 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
1041 | 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). |
1042 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
990 | |
1043 | |
991 | Each watcher structure must be initialised by a call to C<ev_init |
1044 | 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 |
1045 | *, 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 |
1046 | 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 |
1047 | time the event loop detects that the file descriptor given is readable |
995 | is readable and/or writable). |
1048 | and/or writable). |
996 | |
1049 | |
997 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
1050 | 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 |
1051 | 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<< |
1052 | is also a macro to combine initialisation and setting in one call: C<< |
1000 | ev_TYPE_init (watcher *, callback, ...) >>. |
1053 | ev_TYPE_init (watcher *, callback, ...) >>. |
… | |
… | |
1023 | =item C<EV_WRITE> |
1076 | =item C<EV_WRITE> |
1024 | |
1077 | |
1025 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1078 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1026 | writable. |
1079 | writable. |
1027 | |
1080 | |
1028 | =item C<EV_TIMEOUT> |
1081 | =item C<EV_TIMER> |
1029 | |
1082 | |
1030 | The C<ev_timer> watcher has timed out. |
1083 | The C<ev_timer> watcher has timed out. |
1031 | |
1084 | |
1032 | =item C<EV_PERIODIC> |
1085 | =item C<EV_PERIODIC> |
1033 | |
1086 | |
… | |
… | |
1051 | |
1104 | |
1052 | =item C<EV_PREPARE> |
1105 | =item C<EV_PREPARE> |
1053 | |
1106 | |
1054 | =item C<EV_CHECK> |
1107 | =item C<EV_CHECK> |
1055 | |
1108 | |
1056 | All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts |
1109 | 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 |
1110 | 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 |
1111 | 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 |
1112 | 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 |
1113 | 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 |
1114 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1062 | C<ev_loop> from blocking). |
1115 | C<ev_run> from blocking). |
1063 | |
1116 | |
1064 | =item C<EV_EMBED> |
1117 | =item C<EV_EMBED> |
1065 | |
1118 | |
1066 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1119 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1067 | |
1120 | |
1068 | =item C<EV_FORK> |
1121 | =item C<EV_FORK> |
1069 | |
1122 | |
1070 | The event loop has been resumed in the child process after fork (see |
1123 | The event loop has been resumed in the child process after fork (see |
1071 | C<ev_fork>). |
1124 | C<ev_fork>). |
|
|
1125 | |
|
|
1126 | =item C<EV_CLEANUP> |
|
|
1127 | |
|
|
1128 | The event loop is about to be destroyed (see C<ev_cleanup>). |
1072 | |
1129 | |
1073 | =item C<EV_ASYNC> |
1130 | =item C<EV_ASYNC> |
1074 | |
1131 | |
1075 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1132 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1076 | |
1133 | |
… | |
… | |
1123 | |
1180 | |
1124 | ev_io w; |
1181 | ev_io w; |
1125 | ev_init (&w, my_cb); |
1182 | ev_init (&w, my_cb); |
1126 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1183 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1127 | |
1184 | |
1128 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
1185 | =item C<ev_TYPE_set> (ev_TYPE *watcher, [args]) |
1129 | |
1186 | |
1130 | This macro initialises the type-specific parts of a watcher. You need to |
1187 | 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 |
1188 | 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 |
1189 | 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 |
1190 | macro on a watcher that is active (it can be pending, however, which is a |
… | |
… | |
1146 | |
1203 | |
1147 | Example: Initialise and set an C<ev_io> watcher in one step. |
1204 | Example: Initialise and set an C<ev_io> watcher in one step. |
1148 | |
1205 | |
1149 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1206 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1150 | |
1207 | |
1151 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
1208 | =item C<ev_TYPE_start> (loop, ev_TYPE *watcher) |
1152 | |
1209 | |
1153 | Starts (activates) the given watcher. Only active watchers will receive |
1210 | Starts (activates) the given watcher. Only active watchers will receive |
1154 | events. If the watcher is already active nothing will happen. |
1211 | events. If the watcher is already active nothing will happen. |
1155 | |
1212 | |
1156 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1213 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1157 | whole section. |
1214 | whole section. |
1158 | |
1215 | |
1159 | ev_io_start (EV_DEFAULT_UC, &w); |
1216 | ev_io_start (EV_DEFAULT_UC, &w); |
1160 | |
1217 | |
1161 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1218 | =item C<ev_TYPE_stop> (loop, ev_TYPE *watcher) |
1162 | |
1219 | |
1163 | Stops the given watcher if active, and clears the pending status (whether |
1220 | Stops the given watcher if active, and clears the pending status (whether |
1164 | the watcher was active or not). |
1221 | the watcher was active or not). |
1165 | |
1222 | |
1166 | It is possible that stopped watchers are pending - for example, |
1223 | It is possible that stopped watchers are pending - for example, |
… | |
… | |
1191 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1248 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1192 | |
1249 | |
1193 | Change the callback. You can change the callback at virtually any time |
1250 | Change the callback. You can change the callback at virtually any time |
1194 | (modulo threads). |
1251 | (modulo threads). |
1195 | |
1252 | |
1196 | =item ev_set_priority (ev_TYPE *watcher, priority) |
1253 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1197 | |
1254 | |
1198 | =item int ev_priority (ev_TYPE *watcher) |
1255 | =item int ev_priority (ev_TYPE *watcher) |
1199 | |
1256 | |
1200 | Set and query the priority of the watcher. The priority is a small |
1257 | 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> |
1258 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
… | |
… | |
1233 | watcher isn't pending it does nothing and returns C<0>. |
1290 | watcher isn't pending it does nothing and returns C<0>. |
1234 | |
1291 | |
1235 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1292 | 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. |
1293 | callback to be invoked, which can be accomplished with this function. |
1237 | |
1294 | |
|
|
1295 | =item ev_feed_event (loop, ev_TYPE *watcher, int revents) |
|
|
1296 | |
|
|
1297 | Feeds the given event set into the event loop, as if the specified event |
|
|
1298 | had happened for the specified watcher (which must be a pointer to an |
|
|
1299 | initialised but not necessarily started event watcher). Obviously you must |
|
|
1300 | not free the watcher as long as it has pending events. |
|
|
1301 | |
|
|
1302 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1303 | C<ev_clear_pending> will clear the pending event, even if the watcher was |
|
|
1304 | not started in the first place. |
|
|
1305 | |
|
|
1306 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
|
|
1307 | functions that do not need a watcher. |
|
|
1308 | |
1238 | =back |
1309 | =back |
1239 | |
|
|
1240 | |
1310 | |
1241 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1311 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1242 | |
1312 | |
1243 | Each watcher has, by default, a member C<void *data> that you can change |
1313 | 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 |
1314 | and read at any time: libev will completely ignore it. This can be used |
… | |
… | |
1300 | t2_cb (EV_P_ ev_timer *w, int revents) |
1370 | t2_cb (EV_P_ ev_timer *w, int revents) |
1301 | { |
1371 | { |
1302 | struct my_biggy big = (struct my_biggy *) |
1372 | struct my_biggy big = (struct my_biggy *) |
1303 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1373 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1304 | } |
1374 | } |
|
|
1375 | |
|
|
1376 | =head2 WATCHER STATES |
|
|
1377 | |
|
|
1378 | There are various watcher states mentioned throughout this manual - |
|
|
1379 | active, pending and so on. In this section these states and the rules to |
|
|
1380 | transition between them will be described in more detail - and while these |
|
|
1381 | rules might look complicated, they usually do "the right thing". |
|
|
1382 | |
|
|
1383 | =over 4 |
|
|
1384 | |
|
|
1385 | =item initialiased |
|
|
1386 | |
|
|
1387 | Before a watcher can be registered with the event looop it has to be |
|
|
1388 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1389 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
|
|
1390 | |
|
|
1391 | In this state it is simply some block of memory that is suitable for use |
|
|
1392 | in an event loop. It can be moved around, freed, reused etc. at will. |
|
|
1393 | |
|
|
1394 | =item started/running/active |
|
|
1395 | |
|
|
1396 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
|
|
1397 | property of the event loop, and is actively waiting for events. While in |
|
|
1398 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1399 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1400 | and call libev functions on it that are documented to work on active watchers. |
|
|
1401 | |
|
|
1402 | =item pending |
|
|
1403 | |
|
|
1404 | If a watcher is active and libev determines that an event it is interested |
|
|
1405 | in has occurred (such as a timer expiring), it will become pending. It will |
|
|
1406 | stay in this pending state until either it is stopped or its callback is |
|
|
1407 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1408 | callback. |
|
|
1409 | |
|
|
1410 | The watcher might or might not be active while it is pending (for example, |
|
|
1411 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1412 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1413 | but it is still property of the event loop at this time, so cannot be |
|
|
1414 | moved, freed or reused. And if it is active the rules described in the |
|
|
1415 | previous item still apply. |
|
|
1416 | |
|
|
1417 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1418 | via C<ev_feed_event>), in which case it becomes pending without being |
|
|
1419 | active. |
|
|
1420 | |
|
|
1421 | =item stopped |
|
|
1422 | |
|
|
1423 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1424 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
|
|
1425 | latter will clear any pending state the watcher might be in, regardless |
|
|
1426 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1427 | freeing it is often a good idea. |
|
|
1428 | |
|
|
1429 | While stopped (and not pending) the watcher is essentially in the |
|
|
1430 | initialised state, that is it can be reused, moved, modified in any way |
|
|
1431 | you wish. |
|
|
1432 | |
|
|
1433 | =back |
1305 | |
1434 | |
1306 | =head2 WATCHER PRIORITY MODELS |
1435 | =head2 WATCHER PRIORITY MODELS |
1307 | |
1436 | |
1308 | Many event loops support I<watcher priorities>, which are usually small |
1437 | Many event loops support I<watcher priorities>, which are usually small |
1309 | integers that influence the ordering of event callback invocation |
1438 | integers that influence the ordering of event callback invocation |
… | |
… | |
1352 | |
1481 | |
1353 | For example, to emulate how many other event libraries handle priorities, |
1482 | 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 |
1483 | 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 |
1484 | 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 |
1485 | 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 |
1486 | 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 |
1487 | the lock-out case is known to be rare (which in turn is rare :), this is |
1359 | workable. |
1488 | workable. |
1360 | |
1489 | |
1361 | Usually, however, the lock-out model implemented that way will perform |
1490 | 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, |
1491 | miserably under the type of load it was designed to handle. In that case, |
… | |
… | |
1376 | { |
1505 | { |
1377 | // stop the I/O watcher, we received the event, but |
1506 | // stop the I/O watcher, we received the event, but |
1378 | // are not yet ready to handle it. |
1507 | // are not yet ready to handle it. |
1379 | ev_io_stop (EV_A_ w); |
1508 | ev_io_stop (EV_A_ w); |
1380 | |
1509 | |
1381 | // start the idle watcher to ahndle the actual event. |
1510 | // start the idle watcher to handle the actual event. |
1382 | // it will not be executed as long as other watchers |
1511 | // it will not be executed as long as other watchers |
1383 | // with the default priority are receiving events. |
1512 | // with the default priority are receiving events. |
1384 | ev_idle_start (EV_A_ &idle); |
1513 | ev_idle_start (EV_A_ &idle); |
1385 | } |
1514 | } |
1386 | |
1515 | |
… | |
… | |
1440 | |
1569 | |
1441 | If you cannot use non-blocking mode, then force the use of a |
1570 | 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 |
1571 | 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 |
1572 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1444 | descriptors for which non-blocking operation makes no sense (such as |
1573 | descriptors for which non-blocking operation makes no sense (such as |
1445 | files) - libev doesn't guarentee any specific behaviour in that case. |
1574 | files) - libev doesn't guarantee any specific behaviour in that case. |
1446 | |
1575 | |
1447 | Another thing you have to watch out for is that it is quite easy to |
1576 | 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 |
1577 | 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 |
1578 | 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 |
1579 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1515 | |
1644 | |
1516 | So when you encounter spurious, unexplained daemon exits, make sure you |
1645 | 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 |
1646 | 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). |
1647 | somewhere, as that would have given you a big clue). |
1519 | |
1648 | |
|
|
1649 | =head3 The special problem of accept()ing when you can't |
|
|
1650 | |
|
|
1651 | Many implementations of the POSIX C<accept> function (for example, |
|
|
1652 | found in post-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1653 | connection from the pending queue in all error cases. |
|
|
1654 | |
|
|
1655 | For example, larger servers often run out of file descriptors (because |
|
|
1656 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
|
|
1657 | rejecting the connection, leading to libev signalling readiness on |
|
|
1658 | the next iteration again (the connection still exists after all), and |
|
|
1659 | typically causing the program to loop at 100% CPU usage. |
|
|
1660 | |
|
|
1661 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1662 | operating systems, there is usually little the app can do to remedy the |
|
|
1663 | situation, and no known thread-safe method of removing the connection to |
|
|
1664 | cope with overload is known (to me). |
|
|
1665 | |
|
|
1666 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1667 | - when the program encounters an overload, it will just loop until the |
|
|
1668 | situation is over. While this is a form of busy waiting, no OS offers an |
|
|
1669 | event-based way to handle this situation, so it's the best one can do. |
|
|
1670 | |
|
|
1671 | A better way to handle the situation is to log any errors other than |
|
|
1672 | C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such |
|
|
1673 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1674 | what could be wrong ("raise the ulimit!"). For extra points one could stop |
|
|
1675 | the C<ev_io> watcher on the listening fd "for a while", which reduces CPU |
|
|
1676 | usage. |
|
|
1677 | |
|
|
1678 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1679 | descriptor for overload situations (e.g. by opening F</dev/null>), and |
|
|
1680 | when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>, |
|
|
1681 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1682 | clients under typical overload conditions. |
|
|
1683 | |
|
|
1684 | The last way to handle it is to simply log the error and C<exit>, as |
|
|
1685 | is often done with C<malloc> failures, but this results in an easy |
|
|
1686 | opportunity for a DoS attack. |
1520 | |
1687 | |
1521 | =head3 Watcher-Specific Functions |
1688 | =head3 Watcher-Specific Functions |
1522 | |
1689 | |
1523 | =over 4 |
1690 | =over 4 |
1524 | |
1691 | |
… | |
… | |
1556 | ... |
1723 | ... |
1557 | struct ev_loop *loop = ev_default_init (0); |
1724 | struct ev_loop *loop = ev_default_init (0); |
1558 | ev_io stdin_readable; |
1725 | ev_io stdin_readable; |
1559 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1726 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1560 | ev_io_start (loop, &stdin_readable); |
1727 | ev_io_start (loop, &stdin_readable); |
1561 | ev_loop (loop, 0); |
1728 | ev_run (loop, 0); |
1562 | |
1729 | |
1563 | |
1730 | |
1564 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1731 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1565 | |
1732 | |
1566 | Timer watchers are simple relative timers that generate an event after a |
1733 | 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 |
1742 | 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 |
1743 | 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 |
1744 | 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 |
1745 | 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 |
1746 | 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). |
1747 | no longer true when a callback calls C<ev_run> recursively). |
1581 | |
1748 | |
1582 | =head3 Be smart about timeouts |
1749 | =head3 Be smart about timeouts |
1583 | |
1750 | |
1584 | Many real-world problems involve some kind of timeout, usually for error |
1751 | 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, |
1752 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
1671 | ev_tstamp timeout = last_activity + 60.; |
1838 | ev_tstamp timeout = last_activity + 60.; |
1672 | |
1839 | |
1673 | // if last_activity + 60. is older than now, we did time out |
1840 | // if last_activity + 60. is older than now, we did time out |
1674 | if (timeout < now) |
1841 | if (timeout < now) |
1675 | { |
1842 | { |
1676 | // timeout occured, take action |
1843 | // timeout occurred, take action |
1677 | } |
1844 | } |
1678 | else |
1845 | else |
1679 | { |
1846 | { |
1680 | // callback was invoked, but there was some activity, re-arm |
1847 | // callback was invoked, but there was some activity, re-arm |
1681 | // the watcher to fire in last_activity + 60, which is |
1848 | // the watcher to fire in last_activity + 60, which is |
… | |
… | |
1703 | to the current time (meaning we just have some activity :), then call the |
1870 | 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: |
1871 | callback, which will "do the right thing" and start the timer: |
1705 | |
1872 | |
1706 | ev_init (timer, callback); |
1873 | ev_init (timer, callback); |
1707 | last_activity = ev_now (loop); |
1874 | last_activity = ev_now (loop); |
1708 | callback (loop, timer, EV_TIMEOUT); |
1875 | callback (loop, timer, EV_TIMER); |
1709 | |
1876 | |
1710 | And when there is some activity, simply store the current time in |
1877 | And when there is some activity, simply store the current time in |
1711 | C<last_activity>, no libev calls at all: |
1878 | C<last_activity>, no libev calls at all: |
1712 | |
1879 | |
1713 | last_actiivty = ev_now (loop); |
1880 | last_activity = ev_now (loop); |
1714 | |
1881 | |
1715 | This technique is slightly more complex, but in most cases where the |
1882 | This technique is slightly more complex, but in most cases where the |
1716 | time-out is unlikely to be triggered, much more efficient. |
1883 | time-out is unlikely to be triggered, much more efficient. |
1717 | |
1884 | |
1718 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
1885 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
… | |
… | |
1756 | |
1923 | |
1757 | =head3 The special problem of time updates |
1924 | =head3 The special problem of time updates |
1758 | |
1925 | |
1759 | Establishing the current time is a costly operation (it usually takes at |
1926 | 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 |
1927 | 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 |
1928 | 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 |
1929 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1763 | lots of events in one iteration. |
1930 | lots of events in one iteration. |
1764 | |
1931 | |
1765 | The relative timeouts are calculated relative to the C<ev_now ()> |
1932 | 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 |
1933 | 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. |
2004 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1838 | |
2005 | |
1839 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
2006 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1840 | usage example. |
2007 | usage example. |
1841 | |
2008 | |
1842 | =item ev_timer_remaining (loop, ev_timer *) |
2009 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
1843 | |
2010 | |
1844 | Returns the remaining time until a timer fires. If the timer is active, |
2011 | 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 |
2012 | then this time is relative to the current event loop time, otherwise it's |
1846 | the timeout value currently configured. |
2013 | the timeout value currently configured. |
1847 | |
2014 | |
1848 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
2015 | 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> |
2016 | 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 |
2017 | 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, |
2018 | roughly C<7> (likely slightly less as callback invocation takes some time, |
1852 | too), and so on. |
2019 | too), and so on. |
1853 | |
2020 | |
1854 | =item ev_tstamp repeat [read-write] |
2021 | =item ev_tstamp repeat [read-write] |
… | |
… | |
1883 | } |
2050 | } |
1884 | |
2051 | |
1885 | ev_timer mytimer; |
2052 | ev_timer mytimer; |
1886 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2053 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1887 | ev_timer_again (&mytimer); /* start timer */ |
2054 | ev_timer_again (&mytimer); /* start timer */ |
1888 | ev_loop (loop, 0); |
2055 | ev_run (loop, 0); |
1889 | |
2056 | |
1890 | // and in some piece of code that gets executed on any "activity": |
2057 | // and in some piece of code that gets executed on any "activity": |
1891 | // reset the timeout to start ticking again at 10 seconds |
2058 | // reset the timeout to start ticking again at 10 seconds |
1892 | ev_timer_again (&mytimer); |
2059 | ev_timer_again (&mytimer); |
1893 | |
2060 | |
… | |
… | |
1919 | |
2086 | |
1920 | As with timers, the callback is guaranteed to be invoked only when the |
2087 | 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 |
2088 | 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 |
2089 | 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 |
2090 | 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). |
2091 | (but this is no longer true when a callback calls C<ev_run> recursively). |
1925 | |
2092 | |
1926 | =head3 Watcher-Specific Functions and Data Members |
2093 | =head3 Watcher-Specific Functions and Data Members |
1927 | |
2094 | |
1928 | =over 4 |
2095 | =over 4 |
1929 | |
2096 | |
… | |
… | |
2057 | Example: Call a callback every hour, or, more precisely, whenever the |
2224 | Example: Call a callback every hour, or, more precisely, whenever the |
2058 | system time is divisible by 3600. The callback invocation times have |
2225 | system time is divisible by 3600. The callback invocation times have |
2059 | potentially a lot of jitter, but good long-term stability. |
2226 | potentially a lot of jitter, but good long-term stability. |
2060 | |
2227 | |
2061 | static void |
2228 | static void |
2062 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2229 | clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
2063 | { |
2230 | { |
2064 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2231 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2065 | } |
2232 | } |
2066 | |
2233 | |
2067 | ev_periodic hourly_tick; |
2234 | ev_periodic hourly_tick; |
… | |
… | |
2108 | |
2275 | |
2109 | When the first watcher gets started will libev actually register something |
2276 | When the first watcher gets started will libev actually register something |
2110 | with the kernel (thus it coexists with your own signal handlers as long as |
2277 | with the kernel (thus it coexists with your own signal handlers as long as |
2111 | you don't register any with libev for the same signal). |
2278 | you don't register any with libev for the same signal). |
2112 | |
2279 | |
2113 | Both the signal mask state (C<sigprocmask>) and the signal handler state |
|
|
2114 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
|
|
2115 | sotpping it again), that is, libev might or might not block the signal, |
|
|
2116 | and might or might not set or restore the installed signal handler. |
|
|
2117 | |
|
|
2118 | If possible and supported, libev will install its handlers with |
2280 | If possible and supported, libev will install its handlers with |
2119 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2281 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2120 | not be unduly interrupted. If you have a problem with system calls getting |
2282 | not be unduly interrupted. If you have a problem with system calls getting |
2121 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2283 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2122 | and unblock them in an C<ev_prepare> watcher. |
2284 | and unblock them in an C<ev_prepare> watcher. |
2123 | |
2285 | |
|
|
2286 | =head3 The special problem of inheritance over fork/execve/pthread_create |
|
|
2287 | |
|
|
2288 | Both the signal mask (C<sigprocmask>) and the signal disposition |
|
|
2289 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
|
|
2290 | stopping it again), that is, libev might or might not block the signal, |
|
|
2291 | and might or might not set or restore the installed signal handler. |
|
|
2292 | |
|
|
2293 | While this does not matter for the signal disposition (libev never |
|
|
2294 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
|
|
2295 | C<execve>), this matters for the signal mask: many programs do not expect |
|
|
2296 | certain signals to be blocked. |
|
|
2297 | |
|
|
2298 | This means that before calling C<exec> (from the child) you should reset |
|
|
2299 | the signal mask to whatever "default" you expect (all clear is a good |
|
|
2300 | choice usually). |
|
|
2301 | |
|
|
2302 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2303 | to install a fork handler with C<pthread_atfork> that resets it. That will |
|
|
2304 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2305 | |
|
|
2306 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2307 | unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces |
|
|
2308 | the window of opportunity for problems, it will not go away, as libev |
|
|
2309 | I<has> to modify the signal mask, at least temporarily. |
|
|
2310 | |
|
|
2311 | So I can't stress this enough: I<If you do not reset your signal mask when |
|
|
2312 | you expect it to be empty, you have a race condition in your code>. This |
|
|
2313 | is not a libev-specific thing, this is true for most event libraries. |
|
|
2314 | |
2124 | =head3 Watcher-Specific Functions and Data Members |
2315 | =head3 Watcher-Specific Functions and Data Members |
2125 | |
2316 | |
2126 | =over 4 |
2317 | =over 4 |
2127 | |
2318 | |
2128 | =item ev_signal_init (ev_signal *, callback, int signum) |
2319 | =item ev_signal_init (ev_signal *, callback, int signum) |
… | |
… | |
2143 | Example: Try to exit cleanly on SIGINT. |
2334 | Example: Try to exit cleanly on SIGINT. |
2144 | |
2335 | |
2145 | static void |
2336 | static void |
2146 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2337 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2147 | { |
2338 | { |
2148 | ev_unloop (loop, EVUNLOOP_ALL); |
2339 | ev_break (loop, EVBREAK_ALL); |
2149 | } |
2340 | } |
2150 | |
2341 | |
2151 | ev_signal signal_watcher; |
2342 | ev_signal signal_watcher; |
2152 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2343 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2153 | ev_signal_start (loop, &signal_watcher); |
2344 | ev_signal_start (loop, &signal_watcher); |
… | |
… | |
2539 | |
2730 | |
2540 | Prepare and check watchers are usually (but not always) used in pairs: |
2731 | Prepare and check watchers are usually (but not always) used in pairs: |
2541 | prepare watchers get invoked before the process blocks and check watchers |
2732 | prepare watchers get invoked before the process blocks and check watchers |
2542 | afterwards. |
2733 | afterwards. |
2543 | |
2734 | |
2544 | You I<must not> call C<ev_loop> or similar functions that enter |
2735 | You I<must not> call C<ev_run> or similar functions that enter |
2545 | the current event loop from either C<ev_prepare> or C<ev_check> |
2736 | the current event loop from either C<ev_prepare> or C<ev_check> |
2546 | watchers. Other loops than the current one are fine, however. The |
2737 | watchers. Other loops than the current one are fine, however. The |
2547 | rationale behind this is that you do not need to check for recursion in |
2738 | rationale behind this is that you do not need to check for recursion in |
2548 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2739 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2549 | C<ev_check> so if you have one watcher of each kind they will always be |
2740 | C<ev_check> so if you have one watcher of each kind they will always be |
… | |
… | |
2717 | |
2908 | |
2718 | if (timeout >= 0) |
2909 | if (timeout >= 0) |
2719 | // create/start timer |
2910 | // create/start timer |
2720 | |
2911 | |
2721 | // poll |
2912 | // poll |
2722 | ev_loop (EV_A_ 0); |
2913 | ev_run (EV_A_ 0); |
2723 | |
2914 | |
2724 | // stop timer again |
2915 | // stop timer again |
2725 | if (timeout >= 0) |
2916 | if (timeout >= 0) |
2726 | ev_timer_stop (EV_A_ &to); |
2917 | ev_timer_stop (EV_A_ &to); |
2727 | |
2918 | |
… | |
… | |
2805 | if you do not want that, you need to temporarily stop the embed watcher). |
2996 | if you do not want that, you need to temporarily stop the embed watcher). |
2806 | |
2997 | |
2807 | =item ev_embed_sweep (loop, ev_embed *) |
2998 | =item ev_embed_sweep (loop, ev_embed *) |
2808 | |
2999 | |
2809 | Make a single, non-blocking sweep over the embedded loop. This works |
3000 | Make a single, non-blocking sweep over the embedded loop. This works |
2810 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
3001 | similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most |
2811 | appropriate way for embedded loops. |
3002 | appropriate way for embedded loops. |
2812 | |
3003 | |
2813 | =item struct ev_loop *other [read-only] |
3004 | =item struct ev_loop *other [read-only] |
2814 | |
3005 | |
2815 | The embedded event loop. |
3006 | The embedded event loop. |
… | |
… | |
2875 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3066 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2876 | handlers will be invoked, too, of course. |
3067 | handlers will be invoked, too, of course. |
2877 | |
3068 | |
2878 | =head3 The special problem of life after fork - how is it possible? |
3069 | =head3 The special problem of life after fork - how is it possible? |
2879 | |
3070 | |
2880 | Most uses of C<fork()> consist of forking, then some simple calls to ste |
3071 | Most uses of C<fork()> consist of forking, then some simple calls to set |
2881 | up/change the process environment, followed by a call to C<exec()>. This |
3072 | up/change the process environment, followed by a call to C<exec()>. This |
2882 | sequence should be handled by libev without any problems. |
3073 | sequence should be handled by libev without any problems. |
2883 | |
3074 | |
2884 | This changes when the application actually wants to do event handling |
3075 | This changes when the application actually wants to do event handling |
2885 | in the child, or both parent in child, in effect "continuing" after the |
3076 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
2901 | disadvantage of having to use multiple event loops (which do not support |
3092 | disadvantage of having to use multiple event loops (which do not support |
2902 | signal watchers). |
3093 | signal watchers). |
2903 | |
3094 | |
2904 | When this is not possible, or you want to use the default loop for |
3095 | When this is not possible, or you want to use the default loop for |
2905 | other reasons, then in the process that wants to start "fresh", call |
3096 | other reasons, then in the process that wants to start "fresh", call |
2906 | C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying |
3097 | C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>. |
2907 | the default loop will "orphan" (not stop) all registered watchers, so you |
3098 | Destroying the default loop will "orphan" (not stop) all registered |
2908 | have to be careful not to execute code that modifies those watchers. Note |
3099 | watchers, so you have to be careful not to execute code that modifies |
2909 | also that in that case, you have to re-register any signal watchers. |
3100 | those watchers. Note also that in that case, you have to re-register any |
|
|
3101 | signal watchers. |
2910 | |
3102 | |
2911 | =head3 Watcher-Specific Functions and Data Members |
3103 | =head3 Watcher-Specific Functions and Data Members |
2912 | |
3104 | |
2913 | =over 4 |
3105 | =over 4 |
2914 | |
3106 | |
2915 | =item ev_fork_init (ev_signal *, callback) |
3107 | =item ev_fork_init (ev_fork *, callback) |
2916 | |
3108 | |
2917 | Initialises and configures the fork watcher - it has no parameters of any |
3109 | Initialises and configures the fork watcher - it has no parameters of any |
2918 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
3110 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
2919 | believe me. |
3111 | really. |
2920 | |
3112 | |
2921 | =back |
3113 | =back |
2922 | |
3114 | |
2923 | |
3115 | |
|
|
3116 | =head2 C<ev_cleanup> - even the best things end |
|
|
3117 | |
|
|
3118 | Cleanup watchers are called just before the event loop is being destroyed |
|
|
3119 | by a call to C<ev_loop_destroy>. |
|
|
3120 | |
|
|
3121 | While there is no guarantee that the event loop gets destroyed, cleanup |
|
|
3122 | watchers provide a convenient method to install cleanup hooks for your |
|
|
3123 | program, worker threads and so on - you just to make sure to destroy the |
|
|
3124 | loop when you want them to be invoked. |
|
|
3125 | |
|
|
3126 | Cleanup watchers are invoked in the same way as any other watcher. Unlike |
|
|
3127 | all other watchers, they do not keep a reference to the event loop (which |
|
|
3128 | makes a lot of sense if you think about it). Like all other watchers, you |
|
|
3129 | can call libev functions in the callback, except C<ev_cleanup_start>. |
|
|
3130 | |
|
|
3131 | =head3 Watcher-Specific Functions and Data Members |
|
|
3132 | |
|
|
3133 | =over 4 |
|
|
3134 | |
|
|
3135 | =item ev_cleanup_init (ev_cleanup *, callback) |
|
|
3136 | |
|
|
3137 | Initialises and configures the cleanup watcher - it has no parameters of |
|
|
3138 | any kind. There is a C<ev_cleanup_set> macro, but using it is utterly |
|
|
3139 | pointless, I assure you. |
|
|
3140 | |
|
|
3141 | =back |
|
|
3142 | |
|
|
3143 | Example: Register an atexit handler to destroy the default loop, so any |
|
|
3144 | cleanup functions are called. |
|
|
3145 | |
|
|
3146 | static void |
|
|
3147 | program_exits (void) |
|
|
3148 | { |
|
|
3149 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
3150 | } |
|
|
3151 | |
|
|
3152 | ... |
|
|
3153 | atexit (program_exits); |
|
|
3154 | |
|
|
3155 | |
2924 | =head2 C<ev_async> - how to wake up another event loop |
3156 | =head2 C<ev_async> - how to wake up an event loop |
2925 | |
3157 | |
2926 | In general, you cannot use an C<ev_loop> from multiple threads or other |
3158 | In general, you cannot use an C<ev_run> from multiple threads or other |
2927 | asynchronous sources such as signal handlers (as opposed to multiple event |
3159 | asynchronous sources such as signal handlers (as opposed to multiple event |
2928 | loops - those are of course safe to use in different threads). |
3160 | loops - those are of course safe to use in different threads). |
2929 | |
3161 | |
2930 | Sometimes, however, you need to wake up another event loop you do not |
3162 | Sometimes, however, you need to wake up an event loop you do not control, |
2931 | control, for example because it belongs to another thread. This is what |
3163 | for example because it belongs to another thread. This is what C<ev_async> |
2932 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
3164 | watchers do: as long as the C<ev_async> watcher is active, you can signal |
2933 | can signal it by calling C<ev_async_send>, which is thread- and signal |
3165 | it by calling C<ev_async_send>, which is thread- and signal safe. |
2934 | safe. |
|
|
2935 | |
3166 | |
2936 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3167 | This functionality is very similar to C<ev_signal> watchers, as signals, |
2937 | too, are asynchronous in nature, and signals, too, will be compressed |
3168 | too, are asynchronous in nature, and signals, too, will be compressed |
2938 | (i.e. the number of callback invocations may be less than the number of |
3169 | (i.e. the number of callback invocations may be less than the number of |
2939 | C<ev_async_sent> calls). |
3170 | C<ev_async_sent> calls). |
… | |
… | |
2944 | =head3 Queueing |
3175 | =head3 Queueing |
2945 | |
3176 | |
2946 | C<ev_async> does not support queueing of data in any way. The reason |
3177 | C<ev_async> does not support queueing of data in any way. The reason |
2947 | is that the author does not know of a simple (or any) algorithm for a |
3178 | is that the author does not know of a simple (or any) algorithm for a |
2948 | multiple-writer-single-reader queue that works in all cases and doesn't |
3179 | multiple-writer-single-reader queue that works in all cases and doesn't |
2949 | need elaborate support such as pthreads. |
3180 | need elaborate support such as pthreads or unportable memory access |
|
|
3181 | semantics. |
2950 | |
3182 | |
2951 | That means that if you want to queue data, you have to provide your own |
3183 | That means that if you want to queue data, you have to provide your own |
2952 | queue. But at least I can tell you how to implement locking around your |
3184 | queue. But at least I can tell you how to implement locking around your |
2953 | queue: |
3185 | queue: |
2954 | |
3186 | |
… | |
… | |
3093 | |
3325 | |
3094 | If C<timeout> is less than 0, then no timeout watcher will be |
3326 | If C<timeout> is less than 0, then no timeout watcher will be |
3095 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3327 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3096 | repeat = 0) will be started. C<0> is a valid timeout. |
3328 | repeat = 0) will be started. C<0> is a valid timeout. |
3097 | |
3329 | |
3098 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
3330 | The callback has the type C<void (*cb)(int revents, void *arg)> and is |
3099 | passed an C<revents> set like normal event callbacks (a combination of |
3331 | passed an C<revents> set like normal event callbacks (a combination of |
3100 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
3332 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg> |
3101 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3333 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3102 | a timeout and an io event at the same time - you probably should give io |
3334 | a timeout and an io event at the same time - you probably should give io |
3103 | events precedence. |
3335 | events precedence. |
3104 | |
3336 | |
3105 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3337 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3106 | |
3338 | |
3107 | static void stdin_ready (int revents, void *arg) |
3339 | static void stdin_ready (int revents, void *arg) |
3108 | { |
3340 | { |
3109 | if (revents & EV_READ) |
3341 | if (revents & EV_READ) |
3110 | /* stdin might have data for us, joy! */; |
3342 | /* stdin might have data for us, joy! */; |
3111 | else if (revents & EV_TIMEOUT) |
3343 | else if (revents & EV_TIMER) |
3112 | /* doh, nothing entered */; |
3344 | /* doh, nothing entered */; |
3113 | } |
3345 | } |
3114 | |
3346 | |
3115 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3347 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3116 | |
3348 | |
3117 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
|
|
3118 | |
|
|
3119 | Feeds the given event set into the event loop, as if the specified event |
|
|
3120 | had happened for the specified watcher (which must be a pointer to an |
|
|
3121 | initialised but not necessarily started event watcher). |
|
|
3122 | |
|
|
3123 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
3349 | =item ev_feed_fd_event (loop, int fd, int revents) |
3124 | |
3350 | |
3125 | Feed an event on the given fd, as if a file descriptor backend detected |
3351 | Feed an event on the given fd, as if a file descriptor backend detected |
3126 | the given events it. |
3352 | the given events it. |
3127 | |
3353 | |
3128 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
3354 | =item ev_feed_signal_event (loop, int signum) |
3129 | |
3355 | |
3130 | Feed an event as if the given signal occurred (C<loop> must be the default |
3356 | Feed an event as if the given signal occurred (C<loop> must be the default |
3131 | loop!). |
3357 | loop!). |
3132 | |
3358 | |
3133 | =back |
3359 | =back |
… | |
… | |
3213 | |
3439 | |
3214 | =over 4 |
3440 | =over 4 |
3215 | |
3441 | |
3216 | =item ev::TYPE::TYPE () |
3442 | =item ev::TYPE::TYPE () |
3217 | |
3443 | |
3218 | =item ev::TYPE::TYPE (struct ev_loop *) |
3444 | =item ev::TYPE::TYPE (loop) |
3219 | |
3445 | |
3220 | =item ev::TYPE::~TYPE |
3446 | =item ev::TYPE::~TYPE |
3221 | |
3447 | |
3222 | The constructor (optionally) takes an event loop to associate the watcher |
3448 | The constructor (optionally) takes an event loop to associate the watcher |
3223 | with. If it is omitted, it will use C<EV_DEFAULT>. |
3449 | with. If it is omitted, it will use C<EV_DEFAULT>. |
… | |
… | |
3256 | myclass obj; |
3482 | myclass obj; |
3257 | ev::io iow; |
3483 | ev::io iow; |
3258 | iow.set <myclass, &myclass::io_cb> (&obj); |
3484 | iow.set <myclass, &myclass::io_cb> (&obj); |
3259 | |
3485 | |
3260 | =item w->set (object *) |
3486 | =item w->set (object *) |
3261 | |
|
|
3262 | This is an B<experimental> feature that might go away in a future version. |
|
|
3263 | |
3487 | |
3264 | This is a variation of a method callback - leaving out the method to call |
3488 | This is a variation of a method callback - leaving out the method to call |
3265 | will default the method to C<operator ()>, which makes it possible to use |
3489 | will default the method to C<operator ()>, which makes it possible to use |
3266 | functor objects without having to manually specify the C<operator ()> all |
3490 | functor objects without having to manually specify the C<operator ()> all |
3267 | the time. Incidentally, you can then also leave out the template argument |
3491 | the time. Incidentally, you can then also leave out the template argument |
… | |
… | |
3300 | Example: Use a plain function as callback. |
3524 | Example: Use a plain function as callback. |
3301 | |
3525 | |
3302 | static void io_cb (ev::io &w, int revents) { } |
3526 | static void io_cb (ev::io &w, int revents) { } |
3303 | iow.set <io_cb> (); |
3527 | iow.set <io_cb> (); |
3304 | |
3528 | |
3305 | =item w->set (struct ev_loop *) |
3529 | =item w->set (loop) |
3306 | |
3530 | |
3307 | Associates a different C<struct ev_loop> with this watcher. You can only |
3531 | Associates a different C<struct ev_loop> with this watcher. You can only |
3308 | do this when the watcher is inactive (and not pending either). |
3532 | do this when the watcher is inactive (and not pending either). |
3309 | |
3533 | |
3310 | =item w->set ([arguments]) |
3534 | =item w->set ([arguments]) |
3311 | |
3535 | |
3312 | Basically the same as C<ev_TYPE_set>, with the same arguments. Must be |
3536 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
3313 | called at least once. Unlike the C counterpart, an active watcher gets |
3537 | method or a suitable start method must be called at least once. Unlike the |
3314 | automatically stopped and restarted when reconfiguring it with this |
3538 | C counterpart, an active watcher gets automatically stopped and restarted |
3315 | method. |
3539 | when reconfiguring it with this method. |
3316 | |
3540 | |
3317 | =item w->start () |
3541 | =item w->start () |
3318 | |
3542 | |
3319 | Starts the watcher. Note that there is no C<loop> argument, as the |
3543 | Starts the watcher. Note that there is no C<loop> argument, as the |
3320 | constructor already stores the event loop. |
3544 | constructor already stores the event loop. |
3321 | |
3545 | |
|
|
3546 | =item w->start ([arguments]) |
|
|
3547 | |
|
|
3548 | Instead of calling C<set> and C<start> methods separately, it is often |
|
|
3549 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
3550 | the configure C<set> method of the watcher. |
|
|
3551 | |
3322 | =item w->stop () |
3552 | =item w->stop () |
3323 | |
3553 | |
3324 | Stops the watcher if it is active. Again, no C<loop> argument. |
3554 | Stops the watcher if it is active. Again, no C<loop> argument. |
3325 | |
3555 | |
3326 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
3556 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
… | |
… | |
3338 | |
3568 | |
3339 | =back |
3569 | =back |
3340 | |
3570 | |
3341 | =back |
3571 | =back |
3342 | |
3572 | |
3343 | Example: Define a class with an IO and idle watcher, start one of them in |
3573 | Example: Define a class with two I/O and idle watchers, start the I/O |
3344 | the constructor. |
3574 | watchers in the constructor. |
3345 | |
3575 | |
3346 | class myclass |
3576 | class myclass |
3347 | { |
3577 | { |
3348 | ev::io io ; void io_cb (ev::io &w, int revents); |
3578 | ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
3579 | ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
3349 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3580 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3350 | |
3581 | |
3351 | myclass (int fd) |
3582 | myclass (int fd) |
3352 | { |
3583 | { |
3353 | io .set <myclass, &myclass::io_cb > (this); |
3584 | io .set <myclass, &myclass::io_cb > (this); |
|
|
3585 | io2 .set <myclass, &myclass::io2_cb > (this); |
3354 | idle.set <myclass, &myclass::idle_cb> (this); |
3586 | idle.set <myclass, &myclass::idle_cb> (this); |
3355 | |
3587 | |
3356 | io.start (fd, ev::READ); |
3588 | io.set (fd, ev::WRITE); // configure the watcher |
|
|
3589 | io.start (); // start it whenever convenient |
|
|
3590 | |
|
|
3591 | io2.start (fd, ev::READ); // set + start in one call |
3357 | } |
3592 | } |
3358 | }; |
3593 | }; |
3359 | |
3594 | |
3360 | |
3595 | |
3361 | =head1 OTHER LANGUAGE BINDINGS |
3596 | =head1 OTHER LANGUAGE BINDINGS |
… | |
… | |
3409 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3644 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3410 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3645 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3411 | |
3646 | |
3412 | =item Lua |
3647 | =item Lua |
3413 | |
3648 | |
3414 | Brian Maher has written a partial interface to libev |
3649 | Brian Maher has written a partial interface to libev for lua (at the |
3415 | for lua (only C<ev_io> and C<ev_timer>), to be found at |
3650 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
3416 | L<http://github.com/brimworks/lua-ev>. |
3651 | L<http://github.com/brimworks/lua-ev>. |
3417 | |
3652 | |
3418 | =back |
3653 | =back |
3419 | |
3654 | |
3420 | |
3655 | |
… | |
… | |
3435 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3670 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3436 | C<EV_A_> is used when other arguments are following. Example: |
3671 | C<EV_A_> is used when other arguments are following. Example: |
3437 | |
3672 | |
3438 | ev_unref (EV_A); |
3673 | ev_unref (EV_A); |
3439 | ev_timer_add (EV_A_ watcher); |
3674 | ev_timer_add (EV_A_ watcher); |
3440 | ev_loop (EV_A_ 0); |
3675 | ev_run (EV_A_ 0); |
3441 | |
3676 | |
3442 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3677 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3443 | which is often provided by the following macro. |
3678 | which is often provided by the following macro. |
3444 | |
3679 | |
3445 | =item C<EV_P>, C<EV_P_> |
3680 | =item C<EV_P>, C<EV_P_> |
… | |
… | |
3485 | } |
3720 | } |
3486 | |
3721 | |
3487 | ev_check check; |
3722 | ev_check check; |
3488 | ev_check_init (&check, check_cb); |
3723 | ev_check_init (&check, check_cb); |
3489 | ev_check_start (EV_DEFAULT_ &check); |
3724 | ev_check_start (EV_DEFAULT_ &check); |
3490 | ev_loop (EV_DEFAULT_ 0); |
3725 | ev_run (EV_DEFAULT_ 0); |
3491 | |
3726 | |
3492 | =head1 EMBEDDING |
3727 | =head1 EMBEDDING |
3493 | |
3728 | |
3494 | Libev can (and often is) directly embedded into host |
3729 | Libev can (and often is) directly embedded into host |
3495 | applications. Examples of applications that embed it include the Deliantra |
3730 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3575 | libev.m4 |
3810 | libev.m4 |
3576 | |
3811 | |
3577 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3812 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3578 | |
3813 | |
3579 | Libev can be configured via a variety of preprocessor symbols you have to |
3814 | Libev can be configured via a variety of preprocessor symbols you have to |
3580 | define before including any of its files. The default in the absence of |
3815 | define before including (or compiling) any of its files. The default in |
3581 | autoconf is documented for every option. |
3816 | the absence of autoconf is documented for every option. |
|
|
3817 | |
|
|
3818 | Symbols marked with "(h)" do not change the ABI, and can have different |
|
|
3819 | values when compiling libev vs. including F<ev.h>, so it is permissible |
|
|
3820 | to redefine them before including F<ev.h> without breaking compatibility |
|
|
3821 | to a compiled library. All other symbols change the ABI, which means all |
|
|
3822 | users of libev and the libev code itself must be compiled with compatible |
|
|
3823 | settings. |
3582 | |
3824 | |
3583 | =over 4 |
3825 | =over 4 |
3584 | |
3826 | |
|
|
3827 | =item EV_COMPAT3 (h) |
|
|
3828 | |
|
|
3829 | Backwards compatibility is a major concern for libev. This is why this |
|
|
3830 | release of libev comes with wrappers for the functions and symbols that |
|
|
3831 | have been renamed between libev version 3 and 4. |
|
|
3832 | |
|
|
3833 | You can disable these wrappers (to test compatibility with future |
|
|
3834 | versions) by defining C<EV_COMPAT3> to C<0> when compiling your |
|
|
3835 | sources. This has the additional advantage that you can drop the C<struct> |
|
|
3836 | from C<struct ev_loop> declarations, as libev will provide an C<ev_loop> |
|
|
3837 | typedef in that case. |
|
|
3838 | |
|
|
3839 | In some future version, the default for C<EV_COMPAT3> will become C<0>, |
|
|
3840 | and in some even more future version the compatibility code will be |
|
|
3841 | removed completely. |
|
|
3842 | |
3585 | =item EV_STANDALONE |
3843 | =item EV_STANDALONE (h) |
3586 | |
3844 | |
3587 | Must always be C<1> if you do not use autoconf configuration, which |
3845 | Must always be C<1> if you do not use autoconf configuration, which |
3588 | keeps libev from including F<config.h>, and it also defines dummy |
3846 | keeps libev from including F<config.h>, and it also defines dummy |
3589 | implementations for some libevent functions (such as logging, which is not |
3847 | implementations for some libevent functions (such as logging, which is not |
3590 | supported). It will also not define any of the structs usually found in |
3848 | supported). It will also not define any of the structs usually found in |
… | |
… | |
3740 | as well as for signal and thread safety in C<ev_async> watchers. |
3998 | as well as for signal and thread safety in C<ev_async> watchers. |
3741 | |
3999 | |
3742 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4000 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3743 | (from F<signal.h>), which is usually good enough on most platforms. |
4001 | (from F<signal.h>), which is usually good enough on most platforms. |
3744 | |
4002 | |
3745 | =item EV_H |
4003 | =item EV_H (h) |
3746 | |
4004 | |
3747 | The name of the F<ev.h> header file used to include it. The default if |
4005 | The name of the F<ev.h> header file used to include it. The default if |
3748 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
4006 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3749 | used to virtually rename the F<ev.h> header file in case of conflicts. |
4007 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3750 | |
4008 | |
3751 | =item EV_CONFIG_H |
4009 | =item EV_CONFIG_H (h) |
3752 | |
4010 | |
3753 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
4011 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3754 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
4012 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3755 | C<EV_H>, above. |
4013 | C<EV_H>, above. |
3756 | |
4014 | |
3757 | =item EV_EVENT_H |
4015 | =item EV_EVENT_H (h) |
3758 | |
4016 | |
3759 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
4017 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3760 | of how the F<event.h> header can be found, the default is C<"event.h">. |
4018 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3761 | |
4019 | |
3762 | =item EV_PROTOTYPES |
4020 | =item EV_PROTOTYPES (h) |
3763 | |
4021 | |
3764 | If defined to be C<0>, then F<ev.h> will not define any function |
4022 | If defined to be C<0>, then F<ev.h> will not define any function |
3765 | prototypes, but still define all the structs and other symbols. This is |
4023 | prototypes, but still define all the structs and other symbols. This is |
3766 | occasionally useful if you want to provide your own wrapper functions |
4024 | occasionally useful if you want to provide your own wrapper functions |
3767 | around libev functions. |
4025 | around libev functions. |
… | |
… | |
3789 | fine. |
4047 | fine. |
3790 | |
4048 | |
3791 | If your embedding application does not need any priorities, defining these |
4049 | If your embedding application does not need any priorities, defining these |
3792 | both to C<0> will save some memory and CPU. |
4050 | both to C<0> will save some memory and CPU. |
3793 | |
4051 | |
3794 | =item EV_PERIODIC_ENABLE |
4052 | =item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, |
|
|
4053 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
|
|
4054 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3795 | |
4055 | |
3796 | If undefined or defined to be C<1>, then periodic timers are supported. If |
4056 | If undefined or defined to be C<1> (and the platform supports it), then |
3797 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
4057 | the respective watcher type is supported. If defined to be C<0>, then it |
3798 | code. |
4058 | is not. Disabling watcher types mainly saves code size. |
3799 | |
4059 | |
3800 | =item EV_IDLE_ENABLE |
4060 | =item EV_FEATURES |
3801 | |
|
|
3802 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3803 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3804 | code. |
|
|
3805 | |
|
|
3806 | =item EV_EMBED_ENABLE |
|
|
3807 | |
|
|
3808 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3809 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3810 | watcher types, which therefore must not be disabled. |
|
|
3811 | |
|
|
3812 | =item EV_STAT_ENABLE |
|
|
3813 | |
|
|
3814 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3815 | defined to be C<0>, then they are not. |
|
|
3816 | |
|
|
3817 | =item EV_FORK_ENABLE |
|
|
3818 | |
|
|
3819 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3820 | defined to be C<0>, then they are not. |
|
|
3821 | |
|
|
3822 | =item EV_ASYNC_ENABLE |
|
|
3823 | |
|
|
3824 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3825 | defined to be C<0>, then they are not. |
|
|
3826 | |
|
|
3827 | =item EV_MINIMAL |
|
|
3828 | |
4061 | |
3829 | If you need to shave off some kilobytes of code at the expense of some |
4062 | If you need to shave off some kilobytes of code at the expense of some |
3830 | speed (but with the full API), define this symbol to C<1>. Currently this |
4063 | speed (but with the full API), you can define this symbol to request |
3831 | is used to override some inlining decisions, saves roughly 30% code size |
4064 | certain subsets of functionality. The default is to enable all features |
3832 | on amd64. It also selects a much smaller 2-heap for timer management over |
4065 | that can be enabled on the platform. |
3833 | the default 4-heap. |
|
|
3834 | |
4066 | |
3835 | You can save even more by disabling watcher types you do not need |
4067 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
3836 | and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert> |
4068 | with some broad features you want) and then selectively re-enable |
3837 | (C<-DNDEBUG>) will usually reduce code size a lot. |
4069 | additional parts you want, for example if you want everything minimal, |
|
|
4070 | but multiple event loop support, async and child watchers and the poll |
|
|
4071 | backend, use this: |
3838 | |
4072 | |
3839 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
4073 | #define EV_FEATURES 0 |
3840 | provide a bare-bones event library. See C<ev.h> for details on what parts |
4074 | #define EV_MULTIPLICITY 1 |
3841 | of the API are still available, and do not complain if this subset changes |
4075 | #define EV_USE_POLL 1 |
3842 | over time. |
4076 | #define EV_CHILD_ENABLE 1 |
|
|
4077 | #define EV_ASYNC_ENABLE 1 |
|
|
4078 | |
|
|
4079 | The actual value is a bitset, it can be a combination of the following |
|
|
4080 | values: |
|
|
4081 | |
|
|
4082 | =over 4 |
|
|
4083 | |
|
|
4084 | =item C<1> - faster/larger code |
|
|
4085 | |
|
|
4086 | Use larger code to speed up some operations. |
|
|
4087 | |
|
|
4088 | Currently this is used to override some inlining decisions (enlarging the |
|
|
4089 | code size by roughly 30% on amd64). |
|
|
4090 | |
|
|
4091 | When optimising for size, use of compiler flags such as C<-Os> with |
|
|
4092 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
|
|
4093 | assertions. |
|
|
4094 | |
|
|
4095 | =item C<2> - faster/larger data structures |
|
|
4096 | |
|
|
4097 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
|
|
4098 | hash table sizes and so on. This will usually further increase code size |
|
|
4099 | and can additionally have an effect on the size of data structures at |
|
|
4100 | runtime. |
|
|
4101 | |
|
|
4102 | =item C<4> - full API configuration |
|
|
4103 | |
|
|
4104 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
|
|
4105 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
|
|
4106 | |
|
|
4107 | =item C<8> - full API |
|
|
4108 | |
|
|
4109 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
|
|
4110 | details on which parts of the API are still available without this |
|
|
4111 | feature, and do not complain if this subset changes over time. |
|
|
4112 | |
|
|
4113 | =item C<16> - enable all optional watcher types |
|
|
4114 | |
|
|
4115 | Enables all optional watcher types. If you want to selectively enable |
|
|
4116 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
4117 | embed, async, child...) you can enable them manually by defining |
|
|
4118 | C<EV_watchertype_ENABLE> to C<1> instead. |
|
|
4119 | |
|
|
4120 | =item C<32> - enable all backends |
|
|
4121 | |
|
|
4122 | This enables all backends - without this feature, you need to enable at |
|
|
4123 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
|
|
4124 | |
|
|
4125 | =item C<64> - enable OS-specific "helper" APIs |
|
|
4126 | |
|
|
4127 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
4128 | default. |
|
|
4129 | |
|
|
4130 | =back |
|
|
4131 | |
|
|
4132 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
|
|
4133 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
4134 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
4135 | watchers, timers and monotonic clock support. |
|
|
4136 | |
|
|
4137 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
4138 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
|
|
4139 | your program might be left out as well - a binary starting a timer and an |
|
|
4140 | I/O watcher then might come out at only 5Kb. |
|
|
4141 | |
|
|
4142 | =item EV_AVOID_STDIO |
|
|
4143 | |
|
|
4144 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
|
|
4145 | functions (printf, scanf, perror etc.). This will increase the code size |
|
|
4146 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
4147 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
4148 | big. |
|
|
4149 | |
|
|
4150 | Note that error messages might become less precise when this option is |
|
|
4151 | enabled. |
3843 | |
4152 | |
3844 | =item EV_NSIG |
4153 | =item EV_NSIG |
3845 | |
4154 | |
3846 | The highest supported signal number, +1 (or, the number of |
4155 | The highest supported signal number, +1 (or, the number of |
3847 | signals): Normally, libev tries to deduce the maximum number of signals |
4156 | signals): Normally, libev tries to deduce the maximum number of signals |
3848 | automatically, but sometimes this fails, in which case it can be |
4157 | automatically, but sometimes this fails, in which case it can be |
3849 | specified. Also, using a lower number than detected (C<32> should be |
4158 | specified. Also, using a lower number than detected (C<32> should be |
3850 | good for about any system in existance) can save some memory, as libev |
4159 | good for about any system in existence) can save some memory, as libev |
3851 | statically allocates some 12-24 bytes per signal number. |
4160 | statically allocates some 12-24 bytes per signal number. |
3852 | |
4161 | |
3853 | =item EV_PID_HASHSIZE |
4162 | =item EV_PID_HASHSIZE |
3854 | |
4163 | |
3855 | C<ev_child> watchers use a small hash table to distribute workload by |
4164 | C<ev_child> watchers use a small hash table to distribute workload by |
3856 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
4165 | pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled), |
3857 | than enough. If you need to manage thousands of children you might want to |
4166 | usually more than enough. If you need to manage thousands of children you |
3858 | increase this value (I<must> be a power of two). |
4167 | might want to increase this value (I<must> be a power of two). |
3859 | |
4168 | |
3860 | =item EV_INOTIFY_HASHSIZE |
4169 | =item EV_INOTIFY_HASHSIZE |
3861 | |
4170 | |
3862 | C<ev_stat> watchers use a small hash table to distribute workload by |
4171 | C<ev_stat> watchers use a small hash table to distribute workload by |
3863 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
4172 | inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES> |
3864 | usually more than enough. If you need to manage thousands of C<ev_stat> |
4173 | disabled), usually more than enough. If you need to manage thousands of |
3865 | watchers you might want to increase this value (I<must> be a power of |
4174 | C<ev_stat> watchers you might want to increase this value (I<must> be a |
3866 | two). |
4175 | power of two). |
3867 | |
4176 | |
3868 | =item EV_USE_4HEAP |
4177 | =item EV_USE_4HEAP |
3869 | |
4178 | |
3870 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4179 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3871 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
4180 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3872 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
4181 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3873 | faster performance with many (thousands) of watchers. |
4182 | faster performance with many (thousands) of watchers. |
3874 | |
4183 | |
3875 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4184 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3876 | (disabled). |
4185 | will be C<0>. |
3877 | |
4186 | |
3878 | =item EV_HEAP_CACHE_AT |
4187 | =item EV_HEAP_CACHE_AT |
3879 | |
4188 | |
3880 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4189 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3881 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
4190 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3882 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
4191 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3883 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
4192 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3884 | but avoids random read accesses on heap changes. This improves performance |
4193 | but avoids random read accesses on heap changes. This improves performance |
3885 | noticeably with many (hundreds) of watchers. |
4194 | noticeably with many (hundreds) of watchers. |
3886 | |
4195 | |
3887 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4196 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3888 | (disabled). |
4197 | will be C<0>. |
3889 | |
4198 | |
3890 | =item EV_VERIFY |
4199 | =item EV_VERIFY |
3891 | |
4200 | |
3892 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4201 | Controls how much internal verification (see C<ev_verify ()>) will |
3893 | be done: If set to C<0>, no internal verification code will be compiled |
4202 | be done: If set to C<0>, no internal verification code will be compiled |
3894 | in. If set to C<1>, then verification code will be compiled in, but not |
4203 | in. If set to C<1>, then verification code will be compiled in, but not |
3895 | called. If set to C<2>, then the internal verification code will be |
4204 | called. If set to C<2>, then the internal verification code will be |
3896 | called once per loop, which can slow down libev. If set to C<3>, then the |
4205 | called once per loop, which can slow down libev. If set to C<3>, then the |
3897 | verification code will be called very frequently, which will slow down |
4206 | verification code will be called very frequently, which will slow down |
3898 | libev considerably. |
4207 | libev considerably. |
3899 | |
4208 | |
3900 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
4209 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3901 | C<0>. |
4210 | will be C<0>. |
3902 | |
4211 | |
3903 | =item EV_COMMON |
4212 | =item EV_COMMON |
3904 | |
4213 | |
3905 | By default, all watchers have a C<void *data> member. By redefining |
4214 | By default, all watchers have a C<void *data> member. By redefining |
3906 | this macro to a something else you can include more and other types of |
4215 | this macro to something else you can include more and other types of |
3907 | members. You have to define it each time you include one of the files, |
4216 | members. You have to define it each time you include one of the files, |
3908 | though, and it must be identical each time. |
4217 | though, and it must be identical each time. |
3909 | |
4218 | |
3910 | For example, the perl EV module uses something like this: |
4219 | For example, the perl EV module uses something like this: |
3911 | |
4220 | |
… | |
… | |
3964 | file. |
4273 | file. |
3965 | |
4274 | |
3966 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4275 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
3967 | that everybody includes and which overrides some configure choices: |
4276 | that everybody includes and which overrides some configure choices: |
3968 | |
4277 | |
3969 | #define EV_MINIMAL 1 |
4278 | #define EV_FEATURES 8 |
3970 | #define EV_USE_POLL 0 |
4279 | #define EV_USE_SELECT 1 |
3971 | #define EV_MULTIPLICITY 0 |
|
|
3972 | #define EV_PERIODIC_ENABLE 0 |
4280 | #define EV_PREPARE_ENABLE 1 |
|
|
4281 | #define EV_IDLE_ENABLE 1 |
3973 | #define EV_STAT_ENABLE 0 |
4282 | #define EV_SIGNAL_ENABLE 1 |
3974 | #define EV_FORK_ENABLE 0 |
4283 | #define EV_CHILD_ENABLE 1 |
|
|
4284 | #define EV_USE_STDEXCEPT 0 |
3975 | #define EV_CONFIG_H <config.h> |
4285 | #define EV_CONFIG_H <config.h> |
3976 | #define EV_MINPRI 0 |
|
|
3977 | #define EV_MAXPRI 0 |
|
|
3978 | |
4286 | |
3979 | #include "ev++.h" |
4287 | #include "ev++.h" |
3980 | |
4288 | |
3981 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4289 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
3982 | |
4290 | |
… | |
… | |
4113 | userdata *u = ev_userdata (EV_A); |
4421 | userdata *u = ev_userdata (EV_A); |
4114 | pthread_mutex_lock (&u->lock); |
4422 | pthread_mutex_lock (&u->lock); |
4115 | } |
4423 | } |
4116 | |
4424 | |
4117 | The event loop thread first acquires the mutex, and then jumps straight |
4425 | The event loop thread first acquires the mutex, and then jumps straight |
4118 | into C<ev_loop>: |
4426 | into C<ev_run>: |
4119 | |
4427 | |
4120 | void * |
4428 | void * |
4121 | l_run (void *thr_arg) |
4429 | l_run (void *thr_arg) |
4122 | { |
4430 | { |
4123 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4431 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4124 | |
4432 | |
4125 | l_acquire (EV_A); |
4433 | l_acquire (EV_A); |
4126 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4434 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4127 | ev_loop (EV_A_ 0); |
4435 | ev_run (EV_A_ 0); |
4128 | l_release (EV_A); |
4436 | l_release (EV_A); |
4129 | |
4437 | |
4130 | return 0; |
4438 | return 0; |
4131 | } |
4439 | } |
4132 | |
4440 | |
… | |
… | |
4184 | |
4492 | |
4185 | =head3 COROUTINES |
4493 | =head3 COROUTINES |
4186 | |
4494 | |
4187 | Libev is very accommodating to coroutines ("cooperative threads"): |
4495 | Libev is very accommodating to coroutines ("cooperative threads"): |
4188 | libev fully supports nesting calls to its functions from different |
4496 | libev fully supports nesting calls to its functions from different |
4189 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4497 | coroutines (e.g. you can call C<ev_run> on the same loop from two |
4190 | different coroutines, and switch freely between both coroutines running |
4498 | different coroutines, and switch freely between both coroutines running |
4191 | the loop, as long as you don't confuse yourself). The only exception is |
4499 | the loop, as long as you don't confuse yourself). The only exception is |
4192 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4500 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4193 | |
4501 | |
4194 | Care has been taken to ensure that libev does not keep local state inside |
4502 | Care has been taken to ensure that libev does not keep local state inside |
4195 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4503 | C<ev_run>, and other calls do not usually allow for coroutine switches as |
4196 | they do not call any callbacks. |
4504 | they do not call any callbacks. |
4197 | |
4505 | |
4198 | =head2 COMPILER WARNINGS |
4506 | =head2 COMPILER WARNINGS |
4199 | |
4507 | |
4200 | Depending on your compiler and compiler settings, you might get no or a |
4508 | Depending on your compiler and compiler settings, you might get no or a |
… | |
… | |
4211 | maintainable. |
4519 | maintainable. |
4212 | |
4520 | |
4213 | And of course, some compiler warnings are just plain stupid, or simply |
4521 | And of course, some compiler warnings are just plain stupid, or simply |
4214 | wrong (because they don't actually warn about the condition their message |
4522 | wrong (because they don't actually warn about the condition their message |
4215 | seems to warn about). For example, certain older gcc versions had some |
4523 | seems to warn about). For example, certain older gcc versions had some |
4216 | warnings that resulted an extreme number of false positives. These have |
4524 | warnings that resulted in an extreme number of false positives. These have |
4217 | been fixed, but some people still insist on making code warn-free with |
4525 | been fixed, but some people still insist on making code warn-free with |
4218 | such buggy versions. |
4526 | such buggy versions. |
4219 | |
4527 | |
4220 | While libev is written to generate as few warnings as possible, |
4528 | While libev is written to generate as few warnings as possible, |
4221 | "warn-free" code is not a goal, and it is recommended not to build libev |
4529 | "warn-free" code is not a goal, and it is recommended not to build libev |
… | |
… | |
4257 | I suggest using suppression lists. |
4565 | I suggest using suppression lists. |
4258 | |
4566 | |
4259 | |
4567 | |
4260 | =head1 PORTABILITY NOTES |
4568 | =head1 PORTABILITY NOTES |
4261 | |
4569 | |
|
|
4570 | =head2 GNU/LINUX 32 BIT LIMITATIONS |
|
|
4571 | |
|
|
4572 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
4573 | interfaces but I<disables> them by default. |
|
|
4574 | |
|
|
4575 | That means that libev compiled in the default environment doesn't support |
|
|
4576 | files larger than 2GiB or so, which mainly affects C<ev_stat> watchers. |
|
|
4577 | |
|
|
4578 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
4579 | by enabling the large file API, which makes them incompatible with the |
|
|
4580 | standard libev compiled for their system. |
|
|
4581 | |
|
|
4582 | Likewise, libev cannot enable the large file API itself as this would |
|
|
4583 | suddenly make it incompatible to the default compile time environment, |
|
|
4584 | i.e. all programs not using special compile switches. |
|
|
4585 | |
|
|
4586 | =head2 OS/X AND DARWIN BUGS |
|
|
4587 | |
|
|
4588 | The whole thing is a bug if you ask me - basically any system interface |
|
|
4589 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
4590 | OpenGL drivers. |
|
|
4591 | |
|
|
4592 | =head3 C<kqueue> is buggy |
|
|
4593 | |
|
|
4594 | The kqueue syscall is broken in all known versions - most versions support |
|
|
4595 | only sockets, many support pipes. |
|
|
4596 | |
|
|
4597 | Libev tries to work around this by not using C<kqueue> by default on this |
|
|
4598 | rotten platform, but of course you can still ask for it when creating a |
|
|
4599 | loop - embedding a socket-only kqueue loop into a select-based one is |
|
|
4600 | probably going to work well. |
|
|
4601 | |
|
|
4602 | =head3 C<poll> is buggy |
|
|
4603 | |
|
|
4604 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
|
|
4605 | implementation by something calling C<kqueue> internally around the 10.5.6 |
|
|
4606 | release, so now C<kqueue> I<and> C<poll> are broken. |
|
|
4607 | |
|
|
4608 | Libev tries to work around this by not using C<poll> by default on |
|
|
4609 | this rotten platform, but of course you can still ask for it when creating |
|
|
4610 | a loop. |
|
|
4611 | |
|
|
4612 | =head3 C<select> is buggy |
|
|
4613 | |
|
|
4614 | All that's left is C<select>, and of course Apple found a way to fuck this |
|
|
4615 | one up as well: On OS/X, C<select> actively limits the number of file |
|
|
4616 | descriptors you can pass in to 1024 - your program suddenly crashes when |
|
|
4617 | you use more. |
|
|
4618 | |
|
|
4619 | There is an undocumented "workaround" for this - defining |
|
|
4620 | C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should> |
|
|
4621 | work on OS/X. |
|
|
4622 | |
|
|
4623 | =head2 SOLARIS PROBLEMS AND WORKAROUNDS |
|
|
4624 | |
|
|
4625 | =head3 C<errno> reentrancy |
|
|
4626 | |
|
|
4627 | The default compile environment on Solaris is unfortunately so |
|
|
4628 | thread-unsafe that you can't even use components/libraries compiled |
|
|
4629 | without C<-D_REENTRANT> in a threaded program, which, of course, isn't |
|
|
4630 | defined by default. A valid, if stupid, implementation choice. |
|
|
4631 | |
|
|
4632 | If you want to use libev in threaded environments you have to make sure |
|
|
4633 | it's compiled with C<_REENTRANT> defined. |
|
|
4634 | |
|
|
4635 | =head3 Event port backend |
|
|
4636 | |
|
|
4637 | The scalable event interface for Solaris is called "event |
|
|
4638 | ports". Unfortunately, this mechanism is very buggy in all major |
|
|
4639 | releases. If you run into high CPU usage, your program freezes or you get |
|
|
4640 | a large number of spurious wakeups, make sure you have all the relevant |
|
|
4641 | and latest kernel patches applied. No, I don't know which ones, but there |
|
|
4642 | are multiple ones to apply, and afterwards, event ports actually work |
|
|
4643 | great. |
|
|
4644 | |
|
|
4645 | If you can't get it to work, you can try running the program by setting |
|
|
4646 | the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and |
|
|
4647 | C<select> backends. |
|
|
4648 | |
|
|
4649 | =head2 AIX POLL BUG |
|
|
4650 | |
|
|
4651 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
|
|
4652 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
4653 | compiled in), which normally isn't a big problem as C<select> works fine |
|
|
4654 | with large bitsets on AIX, and AIX is dead anyway. |
|
|
4655 | |
4262 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4656 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
|
|
4657 | |
|
|
4658 | =head3 General issues |
4263 | |
4659 | |
4264 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4660 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4265 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4661 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4266 | model. Libev still offers limited functionality on this platform in |
4662 | model. Libev still offers limited functionality on this platform in |
4267 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4663 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4268 | descriptors. This only applies when using Win32 natively, not when using |
4664 | descriptors. This only applies when using Win32 natively, not when using |
4269 | e.g. cygwin. |
4665 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
4666 | as every compielr comes with a slightly differently broken/incompatible |
|
|
4667 | environment. |
4270 | |
4668 | |
4271 | Lifting these limitations would basically require the full |
4669 | Lifting these limitations would basically require the full |
4272 | re-implementation of the I/O system. If you are into these kinds of |
4670 | re-implementation of the I/O system. If you are into this kind of thing, |
4273 | things, then note that glib does exactly that for you in a very portable |
4671 | then note that glib does exactly that for you in a very portable way (note |
4274 | way (note also that glib is the slowest event library known to man). |
4672 | also that glib is the slowest event library known to man). |
4275 | |
4673 | |
4276 | There is no supported compilation method available on windows except |
4674 | There is no supported compilation method available on windows except |
4277 | embedding it into other applications. |
4675 | embedding it into other applications. |
4278 | |
4676 | |
4279 | Sensible signal handling is officially unsupported by Microsoft - libev |
4677 | Sensible signal handling is officially unsupported by Microsoft - libev |
… | |
… | |
4307 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4705 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4308 | |
4706 | |
4309 | #include "evwrap.h" |
4707 | #include "evwrap.h" |
4310 | #include "ev.c" |
4708 | #include "ev.c" |
4311 | |
4709 | |
4312 | =over 4 |
|
|
4313 | |
|
|
4314 | =item The winsocket select function |
4710 | =head3 The winsocket C<select> function |
4315 | |
4711 | |
4316 | The winsocket C<select> function doesn't follow POSIX in that it |
4712 | The winsocket C<select> function doesn't follow POSIX in that it |
4317 | requires socket I<handles> and not socket I<file descriptors> (it is |
4713 | requires socket I<handles> and not socket I<file descriptors> (it is |
4318 | also extremely buggy). This makes select very inefficient, and also |
4714 | also extremely buggy). This makes select very inefficient, and also |
4319 | requires a mapping from file descriptors to socket handles (the Microsoft |
4715 | requires a mapping from file descriptors to socket handles (the Microsoft |
… | |
… | |
4328 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4724 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4329 | |
4725 | |
4330 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4726 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4331 | complexity in the O(n²) range when using win32. |
4727 | complexity in the O(n²) range when using win32. |
4332 | |
4728 | |
4333 | =item Limited number of file descriptors |
4729 | =head3 Limited number of file descriptors |
4334 | |
4730 | |
4335 | Windows has numerous arbitrary (and low) limits on things. |
4731 | Windows has numerous arbitrary (and low) limits on things. |
4336 | |
4732 | |
4337 | Early versions of winsocket's select only supported waiting for a maximum |
4733 | Early versions of winsocket's select only supported waiting for a maximum |
4338 | of C<64> handles (probably owning to the fact that all windows kernels |
4734 | of C<64> handles (probably owning to the fact that all windows kernels |
… | |
… | |
4353 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4749 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4354 | (depending on windows version and/or the phase of the moon). To get more, |
4750 | (depending on windows version and/or the phase of the moon). To get more, |
4355 | you need to wrap all I/O functions and provide your own fd management, but |
4751 | you need to wrap all I/O functions and provide your own fd management, but |
4356 | the cost of calling select (O(n²)) will likely make this unworkable. |
4752 | the cost of calling select (O(n²)) will likely make this unworkable. |
4357 | |
4753 | |
4358 | =back |
|
|
4359 | |
|
|
4360 | =head2 PORTABILITY REQUIREMENTS |
4754 | =head2 PORTABILITY REQUIREMENTS |
4361 | |
4755 | |
4362 | In addition to a working ISO-C implementation and of course the |
4756 | In addition to a working ISO-C implementation and of course the |
4363 | backend-specific APIs, libev relies on a few additional extensions: |
4757 | backend-specific APIs, libev relies on a few additional extensions: |
4364 | |
4758 | |
… | |
… | |
4370 | Libev assumes not only that all watcher pointers have the same internal |
4764 | Libev assumes not only that all watcher pointers have the same internal |
4371 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
4765 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
4372 | assumes that the same (machine) code can be used to call any watcher |
4766 | assumes that the same (machine) code can be used to call any watcher |
4373 | callback: The watcher callbacks have different type signatures, but libev |
4767 | callback: The watcher callbacks have different type signatures, but libev |
4374 | calls them using an C<ev_watcher *> internally. |
4768 | calls them using an C<ev_watcher *> internally. |
|
|
4769 | |
|
|
4770 | =item pointer accesses must be thread-atomic |
|
|
4771 | |
|
|
4772 | Accessing a pointer value must be atomic, it must both be readable and |
|
|
4773 | writable in one piece - this is the case on all current architectures. |
4375 | |
4774 | |
4376 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
4775 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
4377 | |
4776 | |
4378 | The type C<sig_atomic_t volatile> (or whatever is defined as |
4777 | The type C<sig_atomic_t volatile> (or whatever is defined as |
4379 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
4778 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
… | |
… | |
4402 | watchers. |
4801 | watchers. |
4403 | |
4802 | |
4404 | =item C<double> must hold a time value in seconds with enough accuracy |
4803 | =item C<double> must hold a time value in seconds with enough accuracy |
4405 | |
4804 | |
4406 | The type C<double> is used to represent timestamps. It is required to |
4805 | The type C<double> is used to represent timestamps. It is required to |
4407 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4806 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
4408 | enough for at least into the year 4000. This requirement is fulfilled by |
4807 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
4808 | (the design goal for libev). This requirement is overfulfilled by |
4409 | implementations implementing IEEE 754, which is basically all existing |
4809 | implementations using IEEE 754, which is basically all existing ones. With |
4410 | ones. With IEEE 754 doubles, you get microsecond accuracy until at least |
4810 | IEEE 754 doubles, you get microsecond accuracy until at least 2200. |
4411 | 2200. |
|
|
4412 | |
4811 | |
4413 | =back |
4812 | =back |
4414 | |
4813 | |
4415 | If you know of other additional requirements drop me a note. |
4814 | If you know of other additional requirements drop me a note. |
4416 | |
4815 | |
… | |
… | |
4484 | involves iterating over all running async watchers or all signal numbers. |
4883 | involves iterating over all running async watchers or all signal numbers. |
4485 | |
4884 | |
4486 | =back |
4885 | =back |
4487 | |
4886 | |
4488 | |
4887 | |
|
|
4888 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
|
|
4889 | |
|
|
4890 | The major version 4 introduced some incompatible changes to the API. |
|
|
4891 | |
|
|
4892 | At the moment, the C<ev.h> header file provides compatibility definitions |
|
|
4893 | for all changes, so most programs should still compile. The compatibility |
|
|
4894 | layer might be removed in later versions of libev, so better update to the |
|
|
4895 | new API early than late. |
|
|
4896 | |
|
|
4897 | =over 4 |
|
|
4898 | |
|
|
4899 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
4900 | |
|
|
4901 | The backward compatibility mechanism can be controlled by |
|
|
4902 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
4903 | section. |
|
|
4904 | |
|
|
4905 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
|
|
4906 | |
|
|
4907 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
|
|
4908 | |
|
|
4909 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
4910 | ev_loop_fork (EV_DEFAULT); |
|
|
4911 | |
|
|
4912 | =item function/symbol renames |
|
|
4913 | |
|
|
4914 | A number of functions and symbols have been renamed: |
|
|
4915 | |
|
|
4916 | ev_loop => ev_run |
|
|
4917 | EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
4918 | EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
4919 | |
|
|
4920 | ev_unloop => ev_break |
|
|
4921 | EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
4922 | EVUNLOOP_ONE => EVBREAK_ONE |
|
|
4923 | EVUNLOOP_ALL => EVBREAK_ALL |
|
|
4924 | |
|
|
4925 | EV_TIMEOUT => EV_TIMER |
|
|
4926 | |
|
|
4927 | ev_loop_count => ev_iteration |
|
|
4928 | ev_loop_depth => ev_depth |
|
|
4929 | ev_loop_verify => ev_verify |
|
|
4930 | |
|
|
4931 | Most functions working on C<struct ev_loop> objects don't have an |
|
|
4932 | C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and |
|
|
4933 | associated constants have been renamed to not collide with the C<struct |
|
|
4934 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
|
|
4935 | as all other watcher types. Note that C<ev_loop_fork> is still called |
|
|
4936 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
|
|
4937 | typedef. |
|
|
4938 | |
|
|
4939 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
4940 | |
|
|
4941 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
4942 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
4943 | and work, but the library code will of course be larger. |
|
|
4944 | |
|
|
4945 | =back |
|
|
4946 | |
|
|
4947 | |
4489 | =head1 GLOSSARY |
4948 | =head1 GLOSSARY |
4490 | |
4949 | |
4491 | =over 4 |
4950 | =over 4 |
4492 | |
4951 | |
4493 | =item active |
4952 | =item active |
4494 | |
4953 | |
4495 | A watcher is active as long as it has been started (has been attached to |
4954 | A watcher is active as long as it has been started and not yet stopped. |
4496 | an event loop) but not yet stopped (disassociated from the event loop). |
4955 | See L<WATCHER STATES> for details. |
4497 | |
4956 | |
4498 | =item application |
4957 | =item application |
4499 | |
4958 | |
4500 | In this document, an application is whatever is using libev. |
4959 | In this document, an application is whatever is using libev. |
|
|
4960 | |
|
|
4961 | =item backend |
|
|
4962 | |
|
|
4963 | The part of the code dealing with the operating system interfaces. |
4501 | |
4964 | |
4502 | =item callback |
4965 | =item callback |
4503 | |
4966 | |
4504 | The address of a function that is called when some event has been |
4967 | The address of a function that is called when some event has been |
4505 | detected. Callbacks are being passed the event loop, the watcher that |
4968 | detected. Callbacks are being passed the event loop, the watcher that |
4506 | received the event, and the actual event bitset. |
4969 | received the event, and the actual event bitset. |
4507 | |
4970 | |
4508 | =item callback invocation |
4971 | =item callback/watcher invocation |
4509 | |
4972 | |
4510 | The act of calling the callback associated with a watcher. |
4973 | The act of calling the callback associated with a watcher. |
4511 | |
4974 | |
4512 | =item event |
4975 | =item event |
4513 | |
4976 | |
4514 | A change of state of some external event, such as data now being available |
4977 | A change of state of some external event, such as data now being available |
4515 | for reading on a file descriptor, time having passed or simply not having |
4978 | for reading on a file descriptor, time having passed or simply not having |
4516 | any other events happening anymore. |
4979 | any other events happening anymore. |
4517 | |
4980 | |
4518 | In libev, events are represented as single bits (such as C<EV_READ> or |
4981 | In libev, events are represented as single bits (such as C<EV_READ> or |
4519 | C<EV_TIMEOUT>). |
4982 | C<EV_TIMER>). |
4520 | |
4983 | |
4521 | =item event library |
4984 | =item event library |
4522 | |
4985 | |
4523 | A software package implementing an event model and loop. |
4986 | A software package implementing an event model and loop. |
4524 | |
4987 | |
… | |
… | |
4532 | The model used to describe how an event loop handles and processes |
4995 | The model used to describe how an event loop handles and processes |
4533 | watchers and events. |
4996 | watchers and events. |
4534 | |
4997 | |
4535 | =item pending |
4998 | =item pending |
4536 | |
4999 | |
4537 | A watcher is pending as soon as the corresponding event has been detected, |
5000 | A watcher is pending as soon as the corresponding event has been |
4538 | and stops being pending as soon as the watcher will be invoked or its |
5001 | detected. See L<WATCHER STATES> for details. |
4539 | pending status is explicitly cleared by the application. |
|
|
4540 | |
|
|
4541 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4542 | its pending status. |
|
|
4543 | |
5002 | |
4544 | =item real time |
5003 | =item real time |
4545 | |
5004 | |
4546 | The physical time that is observed. It is apparently strictly monotonic :) |
5005 | The physical time that is observed. It is apparently strictly monotonic :) |
4547 | |
5006 | |
… | |
… | |
4554 | =item watcher |
5013 | =item watcher |
4555 | |
5014 | |
4556 | A data structure that describes interest in certain events. Watchers need |
5015 | A data structure that describes interest in certain events. Watchers need |
4557 | to be started (attached to an event loop) before they can receive events. |
5016 | to be started (attached to an event loop) before they can receive events. |
4558 | |
5017 | |
4559 | =item watcher invocation |
|
|
4560 | |
|
|
4561 | The act of calling the callback associated with a watcher. |
|
|
4562 | |
|
|
4563 | =back |
5018 | =back |
4564 | |
5019 | |
4565 | =head1 AUTHOR |
5020 | =head1 AUTHOR |
4566 | |
5021 | |
4567 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
5022 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
|
|
5023 | Magnusson and Emanuele Giaquinta. |
4568 | |
5024 | |