… | |
… | |
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. |
82 | |
82 | |
83 | =head1 ABOUT LIBEV |
83 | =head1 ABOUT LIBEV |
84 | |
84 | |
85 | Libev is an event loop: you register interest in certain events (such as a |
85 | Libev is an event loop: you register interest in certain events (such as a |
… | |
… | |
98 | =head2 FEATURES |
98 | =head2 FEATURES |
99 | |
99 | |
100 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
100 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
101 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
101 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
102 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
102 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
103 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
103 | (for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner |
104 | with customised rescheduling (C<ev_periodic>), synchronous signals |
104 | inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative |
105 | (C<ev_signal>), process status change events (C<ev_child>), and event |
105 | timers (C<ev_timer>), absolute timers with customised rescheduling |
106 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
106 | (C<ev_periodic>), synchronous signals (C<ev_signal>), process status |
107 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
107 | change events (C<ev_child>), and event watchers dealing with the event |
108 | file watchers (C<ev_stat>) and even limited support for fork events |
108 | loop mechanism itself (C<ev_idle>, C<ev_embed>, C<ev_prepare> and |
109 | (C<ev_fork>). |
109 | C<ev_check> watchers) as well as file watchers (C<ev_stat>) and even |
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110 | limited support for fork events (C<ev_fork>). |
110 | |
111 | |
111 | It also is quite fast (see this |
112 | It also is quite fast (see this |
112 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
113 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
113 | for example). |
114 | for example). |
114 | |
115 | |
… | |
… | |
117 | Libev is very configurable. In this manual the default (and most common) |
118 | Libev is very configurable. In this manual the default (and most common) |
118 | configuration will be described, which supports multiple event loops. For |
119 | configuration will be described, which supports multiple event loops. For |
119 | more info about various configuration options please have a look at |
120 | more info about various configuration options please have a look at |
120 | B<EMBED> section in this manual. If libev was configured without support |
121 | B<EMBED> section in this manual. If libev was configured without support |
121 | for multiple event loops, then all functions taking an initial argument of |
122 | for multiple event loops, then all functions taking an initial argument of |
122 | name C<loop> (which is always of type C<ev_loop *>) will not have |
123 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
123 | this argument. |
124 | this argument. |
124 | |
125 | |
125 | =head2 TIME REPRESENTATION |
126 | =head2 TIME REPRESENTATION |
126 | |
127 | |
127 | Libev represents time as a single floating point number, representing |
128 | Libev represents time as a single floating point number, representing |
128 | the (fractional) number of seconds since the (POSIX) epoch (somewhere |
129 | the (fractional) number of seconds since the (POSIX) epoch (in practice |
129 | near the beginning of 1970, details are complicated, don't ask). This |
130 | somewhere near the beginning of 1970, details are complicated, don't |
130 | type is called C<ev_tstamp>, which is what you should use too. It usually |
131 | ask). This type is called C<ev_tstamp>, which is what you should use |
131 | aliases to the C<double> type in C. When you need to do any calculations |
132 | too. It usually aliases to the C<double> type in C. When you need to do |
132 | on it, you should treat it as some floating point value. Unlike the name |
133 | any calculations on it, you should treat it as some floating point value. |
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134 | |
133 | component C<stamp> might indicate, it is also used for time differences |
135 | Unlike the name component C<stamp> might indicate, it is also used for |
134 | throughout libev. |
136 | time differences (e.g. delays) throughout libev. |
135 | |
137 | |
136 | =head1 ERROR HANDLING |
138 | =head1 ERROR HANDLING |
137 | |
139 | |
138 | Libev knows three classes of errors: operating system errors, usage errors |
140 | Libev knows three classes of errors: operating system errors, usage errors |
139 | and internal errors (bugs). |
141 | and internal errors (bugs). |
… | |
… | |
163 | |
165 | |
164 | =item ev_tstamp ev_time () |
166 | =item ev_tstamp ev_time () |
165 | |
167 | |
166 | Returns the current time as libev would use it. Please note that the |
168 | Returns the current time as libev would use it. Please note that the |
167 | C<ev_now> function is usually faster and also often returns the timestamp |
169 | C<ev_now> function is usually faster and also often returns the timestamp |
168 | you actually want to know. |
170 | you actually want to know. Also interesting is the combination of |
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171 | C<ev_update_now> and C<ev_now>. |
169 | |
172 | |
170 | =item ev_sleep (ev_tstamp interval) |
173 | =item ev_sleep (ev_tstamp interval) |
171 | |
174 | |
172 | Sleep for the given interval: The current thread will be blocked until |
175 | Sleep for the given interval: The current thread will be blocked until |
173 | either it is interrupted or the given time interval has passed. Basically |
176 | either it is interrupted or the given time interval has passed. Basically |
… | |
… | |
190 | as this indicates an incompatible change. Minor versions are usually |
193 | as this indicates an incompatible change. Minor versions are usually |
191 | compatible to older versions, so a larger minor version alone is usually |
194 | compatible to older versions, so a larger minor version alone is usually |
192 | not a problem. |
195 | not a problem. |
193 | |
196 | |
194 | Example: Make sure we haven't accidentally been linked against the wrong |
197 | Example: Make sure we haven't accidentally been linked against the wrong |
195 | version. |
198 | version (note, however, that this will not detect other ABI mismatches, |
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199 | such as LFS or reentrancy). |
196 | |
200 | |
197 | assert (("libev version mismatch", |
201 | assert (("libev version mismatch", |
198 | ev_version_major () == EV_VERSION_MAJOR |
202 | ev_version_major () == EV_VERSION_MAJOR |
199 | && ev_version_minor () >= EV_VERSION_MINOR)); |
203 | && ev_version_minor () >= EV_VERSION_MINOR)); |
200 | |
204 | |
… | |
… | |
211 | assert (("sorry, no epoll, no sex", |
215 | assert (("sorry, no epoll, no sex", |
212 | ev_supported_backends () & EVBACKEND_EPOLL)); |
216 | ev_supported_backends () & EVBACKEND_EPOLL)); |
213 | |
217 | |
214 | =item unsigned int ev_recommended_backends () |
218 | =item unsigned int ev_recommended_backends () |
215 | |
219 | |
216 | Return the set of all backends compiled into this binary of libev and also |
220 | Return the set of all backends compiled into this binary of libev and |
217 | recommended for this platform. This set is often smaller than the one |
221 | also recommended for this platform, meaning it will work for most file |
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222 | descriptor types. This set is often smaller than the one returned by |
218 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
223 | C<ev_supported_backends>, as for example kqueue is broken on most BSDs |
219 | most BSDs and will not be auto-detected unless you explicitly request it |
224 | and will not be auto-detected unless you explicitly request it (assuming |
220 | (assuming you know what you are doing). This is the set of backends that |
225 | you know what you are doing). This is the set of backends that libev will |
221 | libev will probe for if you specify no backends explicitly. |
226 | probe for if you specify no backends explicitly. |
222 | |
227 | |
223 | =item unsigned int ev_embeddable_backends () |
228 | =item unsigned int ev_embeddable_backends () |
224 | |
229 | |
225 | Returns the set of backends that are embeddable in other event loops. This |
230 | Returns the set of backends that are embeddable in other event loops. This |
226 | is the theoretical, all-platform, value. To find which backends |
231 | value is platform-specific but can include backends not available on the |
227 | might be supported on the current system, you would need to look at |
232 | current system. To find which embeddable backends might be supported on |
228 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
233 | the current system, you would need to look at C<ev_embeddable_backends () |
229 | recommended ones. |
234 | & ev_supported_backends ()>, likewise for recommended ones. |
230 | |
235 | |
231 | See the description of C<ev_embed> watchers for more info. |
236 | See the description of C<ev_embed> watchers for more info. |
232 | |
237 | |
233 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT] |
238 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT] |
234 | |
239 | |
… | |
… | |
288 | ... |
293 | ... |
289 | ev_set_syserr_cb (fatal_error); |
294 | ev_set_syserr_cb (fatal_error); |
290 | |
295 | |
291 | =back |
296 | =back |
292 | |
297 | |
293 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
298 | =head1 FUNCTIONS CONTROLLING EVENT LOOPS |
294 | |
299 | |
295 | An event loop is described by a C<struct ev_loop *> (the C<struct> |
300 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
296 | is I<not> optional in this case, as there is also an C<ev_loop> |
301 | I<not> optional in this case unless libev 3 compatibility is disabled, as |
297 | I<function>). |
302 | libev 3 had an C<ev_loop> function colliding with the struct name). |
298 | |
303 | |
299 | The library knows two types of such loops, the I<default> loop, which |
304 | The library knows two types of such loops, the I<default> loop, which |
300 | supports signals and child events, and dynamically created loops which do |
305 | supports signals and child events, and dynamically created event loops |
301 | not. |
306 | which do not. |
302 | |
307 | |
303 | =over 4 |
308 | =over 4 |
304 | |
309 | |
305 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
310 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
306 | |
311 | |
307 | This will initialise the default event loop if it hasn't been initialised |
312 | This returns the "default" event loop object, which is what you should |
308 | yet and return it. If the default loop could not be initialised, returns |
313 | normally use when you just need "the event loop". Event loop objects and |
309 | false. If it already was initialised it simply returns it (and ignores the |
314 | the C<flags> parameter are described in more detail in the entry for |
310 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
315 | C<ev_loop_new>. |
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316 | |
|
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317 | If the default loop is already initialised then this function simply |
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318 | returns it (and ignores the flags. If that is troubling you, check |
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319 | C<ev_backend ()> afterwards). Otherwise it will create it with the given |
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320 | flags, which should almost always be C<0>, unless the caller is also the |
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321 | one calling C<ev_run> or otherwise qualifies as "the main program". |
311 | |
322 | |
312 | If you don't know what event loop to use, use the one returned from this |
323 | If you don't know what event loop to use, use the one returned from this |
313 | function. |
324 | function (or via the C<EV_DEFAULT> macro). |
314 | |
325 | |
315 | Note that this function is I<not> thread-safe, so if you want to use it |
326 | Note that this function is I<not> thread-safe, so if you want to use it |
316 | from multiple threads, you have to lock (note also that this is unlikely, |
327 | from multiple threads, you have to employ some kind of mutex (note also |
317 | as loops cannot be shared easily between threads anyway). |
328 | that this case is unlikely, as loops cannot be shared easily between |
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329 | threads anyway). |
318 | |
330 | |
319 | The default loop is the only loop that can handle C<ev_signal> and |
331 | The default loop is the only loop that can handle C<ev_child> watchers, |
320 | C<ev_child> watchers, and to do this, it always registers a handler |
332 | and to do this, it always registers a handler for C<SIGCHLD>. If this is |
321 | for C<SIGCHLD>. If this is a problem for your application you can either |
333 | a problem for your application you can either create a dynamic loop with |
322 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
334 | C<ev_loop_new> which doesn't do that, or you can simply overwrite the |
323 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
335 | C<SIGCHLD> signal handler I<after> calling C<ev_default_init>. |
324 | C<ev_default_init>. |
336 | |
|
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337 | Example: This is the most typical usage. |
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338 | |
|
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339 | if (!ev_default_loop (0)) |
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340 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
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341 | |
|
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342 | Example: Restrict libev to the select and poll backends, and do not allow |
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343 | environment settings to be taken into account: |
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344 | |
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345 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
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346 | |
|
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347 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
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348 | |
|
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349 | This will create and initialise a new event loop object. If the loop |
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350 | could not be initialised, returns false. |
|
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351 | |
|
|
352 | Note that this function I<is> thread-safe, and one common way to use |
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353 | libev with threads is indeed to create one loop per thread, and using the |
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354 | default loop in the "main" or "initial" thread. |
325 | |
355 | |
326 | The flags argument can be used to specify special behaviour or specific |
356 | The flags argument can be used to specify special behaviour or specific |
327 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
357 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
328 | |
358 | |
329 | The following flags are supported: |
359 | The following flags are supported: |
… | |
… | |
344 | useful to try out specific backends to test their performance, or to work |
374 | useful to try out specific backends to test their performance, or to work |
345 | around bugs. |
375 | around bugs. |
346 | |
376 | |
347 | =item C<EVFLAG_FORKCHECK> |
377 | =item C<EVFLAG_FORKCHECK> |
348 | |
378 | |
349 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
379 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
350 | a fork, you can also make libev check for a fork in each iteration by |
380 | make libev check for a fork in each iteration by enabling this flag. |
351 | enabling this flag. |
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|
352 | |
381 | |
353 | This works by calling C<getpid ()> on every iteration of the loop, |
382 | This works by calling C<getpid ()> on every iteration of the loop, |
354 | and thus this might slow down your event loop if you do a lot of loop |
383 | and thus this might slow down your event loop if you do a lot of loop |
355 | iterations and little real work, but is usually not noticeable (on my |
384 | iterations and little real work, but is usually not noticeable (on my |
356 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
385 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
… | |
… | |
362 | flag. |
391 | flag. |
363 | |
392 | |
364 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
393 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
365 | environment variable. |
394 | environment variable. |
366 | |
395 | |
|
|
396 | =item C<EVFLAG_NOINOTIFY> |
|
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397 | |
|
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398 | When this flag is specified, then libev will not attempt to use the |
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399 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
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400 | testing, this flag can be useful to conserve inotify file descriptors, as |
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401 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
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402 | |
|
|
403 | =item C<EVFLAG_SIGNALFD> |
|
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404 | |
|
|
405 | When this flag is specified, then libev will attempt to use the |
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406 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API |
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407 | delivers signals synchronously, which makes it both faster and might make |
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408 | it possible to get the queued signal data. It can also simplify signal |
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409 | handling with threads, as long as you properly block signals in your |
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410 | threads that are not interested in handling them. |
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411 | |
|
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412 | Signalfd will not be used by default as this changes your signal mask, and |
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413 | there are a lot of shoddy libraries and programs (glib's threadpool for |
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414 | example) that can't properly initialise their signal masks. |
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415 | |
367 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
416 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
368 | |
417 | |
369 | This is your standard select(2) backend. Not I<completely> standard, as |
418 | This is your standard select(2) backend. Not I<completely> standard, as |
370 | libev tries to roll its own fd_set with no limits on the number of fds, |
419 | libev tries to roll its own fd_set with no limits on the number of fds, |
371 | but if that fails, expect a fairly low limit on the number of fds when |
420 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
394 | |
443 | |
395 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
444 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
396 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
445 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
397 | |
446 | |
398 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
447 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
|
|
448 | |
|
|
449 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
|
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450 | kernels). |
399 | |
451 | |
400 | For few fds, this backend is a bit little slower than poll and select, |
452 | For few fds, this backend is a bit little slower than poll and select, |
401 | but it scales phenomenally better. While poll and select usually scale |
453 | but it scales phenomenally better. While poll and select usually scale |
402 | like O(total_fds) where n is the total number of fds (or the highest fd), |
454 | like O(total_fds) where n is the total number of fds (or the highest fd), |
403 | epoll scales either O(1) or O(active_fds). |
455 | epoll scales either O(1) or O(active_fds). |
… | |
… | |
415 | of course I<doesn't>, and epoll just loves to report events for totally |
467 | of course I<doesn't>, and epoll just loves to report events for totally |
416 | I<different> file descriptors (even already closed ones, so one cannot |
468 | I<different> file descriptors (even already closed ones, so one cannot |
417 | even remove them from the set) than registered in the set (especially |
469 | even remove them from the set) than registered in the set (especially |
418 | on SMP systems). Libev tries to counter these spurious notifications by |
470 | on SMP systems). Libev tries to counter these spurious notifications by |
419 | employing an additional generation counter and comparing that against the |
471 | employing an additional generation counter and comparing that against the |
420 | events to filter out spurious ones, recreating the set when required. |
472 | events to filter out spurious ones, recreating the set when required. Last |
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473 | not least, it also refuses to work with some file descriptors which work |
|
|
474 | perfectly fine with C<select> (files, many character devices...). |
421 | |
475 | |
422 | While stopping, setting and starting an I/O watcher in the same iteration |
476 | While stopping, setting and starting an I/O watcher in the same iteration |
423 | will result in some caching, there is still a system call per such |
477 | will result in some caching, there is still a system call per such |
424 | incident (because the same I<file descriptor> could point to a different |
478 | incident (because the same I<file descriptor> could point to a different |
425 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
479 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
… | |
… | |
518 | |
572 | |
519 | It is definitely not recommended to use this flag. |
573 | It is definitely not recommended to use this flag. |
520 | |
574 | |
521 | =back |
575 | =back |
522 | |
576 | |
523 | If one or more of these are or'ed into the flags value, then only these |
577 | If one or more of the backend flags are or'ed into the flags value, |
524 | backends will be tried (in the reverse order as listed here). If none are |
578 | then only these backends will be tried (in the reverse order as listed |
525 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
579 | here). If none are specified, all backends in C<ev_recommended_backends |
526 | |
580 | ()> will be tried. |
527 | Example: This is the most typical usage. |
|
|
528 | |
|
|
529 | if (!ev_default_loop (0)) |
|
|
530 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
531 | |
|
|
532 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
533 | environment settings to be taken into account: |
|
|
534 | |
|
|
535 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
536 | |
|
|
537 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
538 | used if available (warning, breaks stuff, best use only with your own |
|
|
539 | private event loop and only if you know the OS supports your types of |
|
|
540 | fds): |
|
|
541 | |
|
|
542 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
543 | |
|
|
544 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
|
|
545 | |
|
|
546 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
|
|
547 | always distinct from the default loop. Unlike the default loop, it cannot |
|
|
548 | handle signal and child watchers, and attempts to do so will be greeted by |
|
|
549 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
550 | |
|
|
551 | Note that this function I<is> thread-safe, and the recommended way to use |
|
|
552 | libev with threads is indeed to create one loop per thread, and using the |
|
|
553 | default loop in the "main" or "initial" thread. |
|
|
554 | |
581 | |
555 | Example: Try to create a event loop that uses epoll and nothing else. |
582 | Example: Try to create a event loop that uses epoll and nothing else. |
556 | |
583 | |
557 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
584 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
558 | if (!epoller) |
585 | if (!epoller) |
559 | fatal ("no epoll found here, maybe it hides under your chair"); |
586 | fatal ("no epoll found here, maybe it hides under your chair"); |
560 | |
587 | |
|
|
588 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
589 | used if available. |
|
|
590 | |
|
|
591 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
592 | |
561 | =item ev_default_destroy () |
593 | =item ev_loop_destroy (loop) |
562 | |
594 | |
563 | Destroys the default loop again (frees all memory and kernel state |
595 | Destroys an event loop object (frees all memory and kernel state |
564 | etc.). None of the active event watchers will be stopped in the normal |
596 | etc.). None of the active event watchers will be stopped in the normal |
565 | sense, so e.g. C<ev_is_active> might still return true. It is your |
597 | sense, so e.g. C<ev_is_active> might still return true. It is your |
566 | responsibility to either stop all watchers cleanly yourself I<before> |
598 | responsibility to either stop all watchers cleanly yourself I<before> |
567 | calling this function, or cope with the fact afterwards (which is usually |
599 | calling this function, or cope with the fact afterwards (which is usually |
568 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
600 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
… | |
… | |
570 | |
602 | |
571 | Note that certain global state, such as signal state (and installed signal |
603 | Note that certain global state, such as signal state (and installed signal |
572 | handlers), will not be freed by this function, and related watchers (such |
604 | handlers), will not be freed by this function, and related watchers (such |
573 | as signal and child watchers) would need to be stopped manually. |
605 | as signal and child watchers) would need to be stopped manually. |
574 | |
606 | |
575 | In general it is not advisable to call this function except in the |
607 | This function is normally used on loop objects allocated by |
576 | rare occasion where you really need to free e.g. the signal handling |
608 | C<ev_loop_new>, but it can also be used on the default loop returned by |
|
|
609 | C<ev_default_loop>, in which case it is not thread-safe. |
|
|
610 | |
|
|
611 | Note that it is not advisable to call this function on the default loop |
|
|
612 | except in the rare occasion where you really need to free it's resources. |
577 | pipe fds. If you need dynamically allocated loops it is better to use |
613 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
578 | C<ev_loop_new> and C<ev_loop_destroy>). |
614 | and C<ev_loop_destroy>. |
579 | |
615 | |
580 | =item ev_loop_destroy (loop) |
616 | =item ev_loop_fork (loop) |
581 | |
617 | |
582 | Like C<ev_default_destroy>, but destroys an event loop created by an |
|
|
583 | earlier call to C<ev_loop_new>. |
|
|
584 | |
|
|
585 | =item ev_default_fork () |
|
|
586 | |
|
|
587 | This function sets a flag that causes subsequent C<ev_loop> iterations |
618 | This function sets a flag that causes subsequent C<ev_run> iterations to |
588 | to reinitialise the kernel state for backends that have one. Despite the |
619 | reinitialise the kernel state for backends that have one. Despite the |
589 | name, you can call it anytime, but it makes most sense after forking, in |
620 | name, you can call it anytime, but it makes most sense after forking, in |
590 | the child process (or both child and parent, but that again makes little |
621 | the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the |
591 | sense). You I<must> call it in the child before using any of the libev |
622 | child before resuming or calling C<ev_run>. |
592 | functions, and it will only take effect at the next C<ev_loop> iteration. |
623 | |
|
|
624 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
|
|
625 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
|
|
626 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
|
|
627 | during fork. |
593 | |
628 | |
594 | On the other hand, you only need to call this function in the child |
629 | On the other hand, you only need to call this function in the child |
595 | process if and only if you want to use the event library in the child. If |
630 | process if and only if you want to use the event loop in the child. If |
596 | you just fork+exec, you don't have to call it at all. |
631 | you just fork+exec or create a new loop in the child, you don't have to |
|
|
632 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
|
|
633 | difference, but libev will usually detect this case on its own and do a |
|
|
634 | costly reset of the backend). |
597 | |
635 | |
598 | The function itself is quite fast and it's usually not a problem to call |
636 | The function itself is quite fast and it's usually not a problem to call |
599 | it just in case after a fork. To make this easy, the function will fit in |
637 | it just in case after a fork. |
600 | quite nicely into a call to C<pthread_atfork>: |
|
|
601 | |
638 | |
|
|
639 | Example: Automate calling C<ev_loop_fork> on the default loop when |
|
|
640 | using pthreads. |
|
|
641 | |
|
|
642 | static void |
|
|
643 | post_fork_child (void) |
|
|
644 | { |
|
|
645 | ev_loop_fork (EV_DEFAULT); |
|
|
646 | } |
|
|
647 | |
|
|
648 | ... |
602 | pthread_atfork (0, 0, ev_default_fork); |
649 | pthread_atfork (0, 0, post_fork_child); |
603 | |
|
|
604 | =item ev_loop_fork (loop) |
|
|
605 | |
|
|
606 | Like C<ev_default_fork>, but acts on an event loop created by |
|
|
607 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
|
|
608 | after fork that you want to re-use in the child, and how you do this is |
|
|
609 | entirely your own problem. |
|
|
610 | |
650 | |
611 | =item int ev_is_default_loop (loop) |
651 | =item int ev_is_default_loop (loop) |
612 | |
652 | |
613 | Returns true when the given loop is, in fact, the default loop, and false |
653 | Returns true when the given loop is, in fact, the default loop, and false |
614 | otherwise. |
654 | otherwise. |
615 | |
655 | |
616 | =item unsigned int ev_loop_count (loop) |
656 | =item unsigned int ev_iteration (loop) |
617 | |
657 | |
618 | Returns the count of loop iterations for the loop, which is identical to |
658 | Returns the current iteration count for the event loop, which is identical |
619 | the number of times libev did poll for new events. It starts at C<0> and |
659 | to the number of times libev did poll for new events. It starts at C<0> |
620 | happily wraps around with enough iterations. |
660 | and happily wraps around with enough iterations. |
621 | |
661 | |
622 | This value can sometimes be useful as a generation counter of sorts (it |
662 | This value can sometimes be useful as a generation counter of sorts (it |
623 | "ticks" the number of loop iterations), as it roughly corresponds with |
663 | "ticks" the number of loop iterations), as it roughly corresponds with |
624 | C<ev_prepare> and C<ev_check> calls. |
664 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
|
|
665 | prepare and check phases. |
|
|
666 | |
|
|
667 | =item unsigned int ev_depth (loop) |
|
|
668 | |
|
|
669 | Returns the number of times C<ev_run> was entered minus the number of |
|
|
670 | times C<ev_run> was exited, in other words, the recursion depth. |
|
|
671 | |
|
|
672 | Outside C<ev_run>, this number is zero. In a callback, this number is |
|
|
673 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
|
|
674 | in which case it is higher. |
|
|
675 | |
|
|
676 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread |
|
|
677 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
|
|
678 | ungentleman-like behaviour unless it's really convenient. |
625 | |
679 | |
626 | =item unsigned int ev_backend (loop) |
680 | =item unsigned int ev_backend (loop) |
627 | |
681 | |
628 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
682 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
629 | use. |
683 | use. |
… | |
… | |
638 | |
692 | |
639 | =item ev_now_update (loop) |
693 | =item ev_now_update (loop) |
640 | |
694 | |
641 | Establishes the current time by querying the kernel, updating the time |
695 | Establishes the current time by querying the kernel, updating the time |
642 | returned by C<ev_now ()> in the progress. This is a costly operation and |
696 | returned by C<ev_now ()> in the progress. This is a costly operation and |
643 | is usually done automatically within C<ev_loop ()>. |
697 | is usually done automatically within C<ev_run ()>. |
644 | |
698 | |
645 | This function is rarely useful, but when some event callback runs for a |
699 | This function is rarely useful, but when some event callback runs for a |
646 | very long time without entering the event loop, updating libev's idea of |
700 | very long time without entering the event loop, updating libev's idea of |
647 | the current time is a good idea. |
701 | the current time is a good idea. |
648 | |
702 | |
… | |
… | |
650 | |
704 | |
651 | =item ev_suspend (loop) |
705 | =item ev_suspend (loop) |
652 | |
706 | |
653 | =item ev_resume (loop) |
707 | =item ev_resume (loop) |
654 | |
708 | |
655 | These two functions suspend and resume a loop, for use when the loop is |
709 | These two functions suspend and resume an event loop, for use when the |
656 | not used for a while and timeouts should not be processed. |
710 | loop is not used for a while and timeouts should not be processed. |
657 | |
711 | |
658 | A typical use case would be an interactive program such as a game: When |
712 | A typical use case would be an interactive program such as a game: When |
659 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
713 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
660 | would be best to handle timeouts as if no time had actually passed while |
714 | would be best to handle timeouts as if no time had actually passed while |
661 | the program was suspended. This can be achieved by calling C<ev_suspend> |
715 | the program was suspended. This can be achieved by calling C<ev_suspend> |
… | |
… | |
663 | C<ev_resume> directly afterwards to resume timer processing. |
717 | C<ev_resume> directly afterwards to resume timer processing. |
664 | |
718 | |
665 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
719 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
666 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
720 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
667 | will be rescheduled (that is, they will lose any events that would have |
721 | will be rescheduled (that is, they will lose any events that would have |
668 | occured while suspended). |
722 | occurred while suspended). |
669 | |
723 | |
670 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
724 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
671 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
725 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
672 | without a previous call to C<ev_suspend>. |
726 | without a previous call to C<ev_suspend>. |
673 | |
727 | |
674 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
728 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
675 | event loop time (see C<ev_now_update>). |
729 | event loop time (see C<ev_now_update>). |
676 | |
730 | |
677 | =item ev_loop (loop, int flags) |
731 | =item ev_run (loop, int flags) |
678 | |
732 | |
679 | Finally, this is it, the event handler. This function usually is called |
733 | Finally, this is it, the event handler. This function usually is called |
680 | after you initialised all your watchers and you want to start handling |
734 | after you have initialised all your watchers and you want to start |
681 | events. |
735 | handling events. It will ask the operating system for any new events, call |
|
|
736 | the watcher callbacks, an then repeat the whole process indefinitely: This |
|
|
737 | is why event loops are called I<loops>. |
682 | |
738 | |
683 | If the flags argument is specified as C<0>, it will not return until |
739 | If the flags argument is specified as C<0>, it will keep handling events |
684 | either no event watchers are active anymore or C<ev_unloop> was called. |
740 | until either no event watchers are active anymore or C<ev_break> was |
|
|
741 | called. |
685 | |
742 | |
686 | Please note that an explicit C<ev_unloop> is usually better than |
743 | Please note that an explicit C<ev_break> is usually better than |
687 | relying on all watchers to be stopped when deciding when a program has |
744 | relying on all watchers to be stopped when deciding when a program has |
688 | finished (especially in interactive programs), but having a program |
745 | finished (especially in interactive programs), but having a program |
689 | that automatically loops as long as it has to and no longer by virtue |
746 | that automatically loops as long as it has to and no longer by virtue |
690 | of relying on its watchers stopping correctly, that is truly a thing of |
747 | of relying on its watchers stopping correctly, that is truly a thing of |
691 | beauty. |
748 | beauty. |
692 | |
749 | |
693 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
750 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
694 | those events and any already outstanding ones, but will not block your |
751 | those events and any already outstanding ones, but will not wait and |
695 | process in case there are no events and will return after one iteration of |
752 | block your process in case there are no events and will return after one |
696 | the loop. |
753 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
754 | events while doing lengthy calculations, to keep the program responsive. |
697 | |
755 | |
698 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
756 | A flags value of C<EVRUN_ONCE> will look for new events (waiting if |
699 | necessary) and will handle those and any already outstanding ones. It |
757 | necessary) and will handle those and any already outstanding ones. It |
700 | will block your process until at least one new event arrives (which could |
758 | will block your process until at least one new event arrives (which could |
701 | be an event internal to libev itself, so there is no guarantee that a |
759 | be an event internal to libev itself, so there is no guarantee that a |
702 | user-registered callback will be called), and will return after one |
760 | user-registered callback will be called), and will return after one |
703 | iteration of the loop. |
761 | iteration of the loop. |
704 | |
762 | |
705 | This is useful if you are waiting for some external event in conjunction |
763 | This is useful if you are waiting for some external event in conjunction |
706 | with something not expressible using other libev watchers (i.e. "roll your |
764 | with something not expressible using other libev watchers (i.e. "roll your |
707 | own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
765 | own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
708 | usually a better approach for this kind of thing. |
766 | usually a better approach for this kind of thing. |
709 | |
767 | |
710 | Here are the gory details of what C<ev_loop> does: |
768 | Here are the gory details of what C<ev_run> does: |
711 | |
769 | |
|
|
770 | - Increment loop depth. |
|
|
771 | - Reset the ev_break status. |
712 | - Before the first iteration, call any pending watchers. |
772 | - Before the first iteration, call any pending watchers. |
|
|
773 | LOOP: |
713 | * If EVFLAG_FORKCHECK was used, check for a fork. |
774 | - If EVFLAG_FORKCHECK was used, check for a fork. |
714 | - If a fork was detected (by any means), queue and call all fork watchers. |
775 | - If a fork was detected (by any means), queue and call all fork watchers. |
715 | - Queue and call all prepare watchers. |
776 | - Queue and call all prepare watchers. |
|
|
777 | - If ev_break was called, goto FINISH. |
716 | - If we have been forked, detach and recreate the kernel state |
778 | - If we have been forked, detach and recreate the kernel state |
717 | as to not disturb the other process. |
779 | as to not disturb the other process. |
718 | - Update the kernel state with all outstanding changes. |
780 | - Update the kernel state with all outstanding changes. |
719 | - Update the "event loop time" (ev_now ()). |
781 | - Update the "event loop time" (ev_now ()). |
720 | - Calculate for how long to sleep or block, if at all |
782 | - Calculate for how long to sleep or block, if at all |
721 | (active idle watchers, EVLOOP_NONBLOCK or not having |
783 | (active idle watchers, EVRUN_NOWAIT or not having |
722 | any active watchers at all will result in not sleeping). |
784 | any active watchers at all will result in not sleeping). |
723 | - Sleep if the I/O and timer collect interval say so. |
785 | - Sleep if the I/O and timer collect interval say so. |
|
|
786 | - Increment loop iteration counter. |
724 | - Block the process, waiting for any events. |
787 | - Block the process, waiting for any events. |
725 | - Queue all outstanding I/O (fd) events. |
788 | - Queue all outstanding I/O (fd) events. |
726 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
789 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
727 | - Queue all expired timers. |
790 | - Queue all expired timers. |
728 | - Queue all expired periodics. |
791 | - Queue all expired periodics. |
729 | - Unless any events are pending now, queue all idle watchers. |
792 | - Queue all idle watchers with priority higher than that of pending events. |
730 | - Queue all check watchers. |
793 | - Queue all check watchers. |
731 | - Call all queued watchers in reverse order (i.e. check watchers first). |
794 | - Call all queued watchers in reverse order (i.e. check watchers first). |
732 | Signals and child watchers are implemented as I/O watchers, and will |
795 | Signals and child watchers are implemented as I/O watchers, and will |
733 | be handled here by queueing them when their watcher gets executed. |
796 | be handled here by queueing them when their watcher gets executed. |
734 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
797 | - If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
735 | were used, or there are no active watchers, return, otherwise |
798 | were used, or there are no active watchers, goto FINISH, otherwise |
736 | continue with step *. |
799 | continue with step LOOP. |
|
|
800 | FINISH: |
|
|
801 | - Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
802 | - Decrement the loop depth. |
|
|
803 | - Return. |
737 | |
804 | |
738 | Example: Queue some jobs and then loop until no events are outstanding |
805 | Example: Queue some jobs and then loop until no events are outstanding |
739 | anymore. |
806 | anymore. |
740 | |
807 | |
741 | ... queue jobs here, make sure they register event watchers as long |
808 | ... queue jobs here, make sure they register event watchers as long |
742 | ... as they still have work to do (even an idle watcher will do..) |
809 | ... as they still have work to do (even an idle watcher will do..) |
743 | ev_loop (my_loop, 0); |
810 | ev_run (my_loop, 0); |
744 | ... jobs done or somebody called unloop. yeah! |
811 | ... jobs done or somebody called unloop. yeah! |
745 | |
812 | |
746 | =item ev_unloop (loop, how) |
813 | =item ev_break (loop, how) |
747 | |
814 | |
748 | Can be used to make a call to C<ev_loop> return early (but only after it |
815 | Can be used to make a call to C<ev_run> return early (but only after it |
749 | has processed all outstanding events). The C<how> argument must be either |
816 | has processed all outstanding events). The C<how> argument must be either |
750 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
817 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
751 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
818 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
752 | |
819 | |
753 | This "unloop state" will be cleared when entering C<ev_loop> again. |
820 | This "unloop state" will be cleared when entering C<ev_run> again. |
754 | |
821 | |
755 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
822 | It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO## |
756 | |
823 | |
757 | =item ev_ref (loop) |
824 | =item ev_ref (loop) |
758 | |
825 | |
759 | =item ev_unref (loop) |
826 | =item ev_unref (loop) |
760 | |
827 | |
761 | Ref/unref can be used to add or remove a reference count on the event |
828 | Ref/unref can be used to add or remove a reference count on the event |
762 | loop: Every watcher keeps one reference, and as long as the reference |
829 | loop: Every watcher keeps one reference, and as long as the reference |
763 | count is nonzero, C<ev_loop> will not return on its own. |
830 | count is nonzero, C<ev_run> will not return on its own. |
764 | |
831 | |
765 | If you have a watcher you never unregister that should not keep C<ev_loop> |
832 | This is useful when you have a watcher that you never intend to |
766 | from returning, call ev_unref() after starting, and ev_ref() before |
833 | unregister, but that nevertheless should not keep C<ev_run> from |
|
|
834 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
767 | stopping it. |
835 | before stopping it. |
768 | |
836 | |
769 | As an example, libev itself uses this for its internal signal pipe: It |
837 | As an example, libev itself uses this for its internal signal pipe: It |
770 | is not visible to the libev user and should not keep C<ev_loop> from |
838 | is not visible to the libev user and should not keep C<ev_run> from |
771 | exiting if no event watchers registered by it are active. It is also an |
839 | exiting if no event watchers registered by it are active. It is also an |
772 | excellent way to do this for generic recurring timers or from within |
840 | excellent way to do this for generic recurring timers or from within |
773 | third-party libraries. Just remember to I<unref after start> and I<ref |
841 | third-party libraries. Just remember to I<unref after start> and I<ref |
774 | before stop> (but only if the watcher wasn't active before, or was active |
842 | before stop> (but only if the watcher wasn't active before, or was active |
775 | before, respectively. Note also that libev might stop watchers itself |
843 | before, respectively. Note also that libev might stop watchers itself |
776 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
844 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
777 | in the callback). |
845 | in the callback). |
778 | |
846 | |
779 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
847 | Example: Create a signal watcher, but keep it from keeping C<ev_run> |
780 | running when nothing else is active. |
848 | running when nothing else is active. |
781 | |
849 | |
782 | ev_signal exitsig; |
850 | ev_signal exitsig; |
783 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
851 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
784 | ev_signal_start (loop, &exitsig); |
852 | ev_signal_start (loop, &exitsig); |
… | |
… | |
811 | |
879 | |
812 | By setting a higher I<io collect interval> you allow libev to spend more |
880 | By setting a higher I<io collect interval> you allow libev to spend more |
813 | time collecting I/O events, so you can handle more events per iteration, |
881 | time collecting I/O events, so you can handle more events per iteration, |
814 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
882 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
815 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
883 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
816 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
884 | introduce an additional C<ev_sleep ()> call into most loop iterations. The |
|
|
885 | sleep time ensures that libev will not poll for I/O events more often then |
|
|
886 | once per this interval, on average. |
817 | |
887 | |
818 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
888 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
819 | to spend more time collecting timeouts, at the expense of increased |
889 | to spend more time collecting timeouts, at the expense of increased |
820 | latency/jitter/inexactness (the watcher callback will be called |
890 | latency/jitter/inexactness (the watcher callback will be called |
821 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
891 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
… | |
… | |
823 | |
893 | |
824 | Many (busy) programs can usually benefit by setting the I/O collect |
894 | Many (busy) programs can usually benefit by setting the I/O collect |
825 | interval to a value near C<0.1> or so, which is often enough for |
895 | interval to a value near C<0.1> or so, which is often enough for |
826 | interactive servers (of course not for games), likewise for timeouts. It |
896 | interactive servers (of course not for games), likewise for timeouts. It |
827 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
897 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
828 | as this approaches the timing granularity of most systems. |
898 | as this approaches the timing granularity of most systems. Note that if |
|
|
899 | you do transactions with the outside world and you can't increase the |
|
|
900 | parallelity, then this setting will limit your transaction rate (if you |
|
|
901 | need to poll once per transaction and the I/O collect interval is 0.01, |
|
|
902 | then you can't do more than 100 transactions per second). |
829 | |
903 | |
830 | Setting the I<timeout collect interval> can improve the opportunity for |
904 | Setting the I<timeout collect interval> can improve the opportunity for |
831 | saving power, as the program will "bundle" timer callback invocations that |
905 | saving power, as the program will "bundle" timer callback invocations that |
832 | are "near" in time together, by delaying some, thus reducing the number of |
906 | are "near" in time together, by delaying some, thus reducing the number of |
833 | times the process sleeps and wakes up again. Another useful technique to |
907 | times the process sleeps and wakes up again. Another useful technique to |
834 | reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure |
908 | reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure |
835 | they fire on, say, one-second boundaries only. |
909 | they fire on, say, one-second boundaries only. |
836 | |
910 | |
|
|
911 | Example: we only need 0.1s timeout granularity, and we wish not to poll |
|
|
912 | more often than 100 times per second: |
|
|
913 | |
|
|
914 | ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1); |
|
|
915 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
|
|
916 | |
|
|
917 | =item ev_invoke_pending (loop) |
|
|
918 | |
|
|
919 | This call will simply invoke all pending watchers while resetting their |
|
|
920 | pending state. Normally, C<ev_run> does this automatically when required, |
|
|
921 | but when overriding the invoke callback this call comes handy. This |
|
|
922 | function can be invoked from a watcher - this can be useful for example |
|
|
923 | when you want to do some lengthy calculation and want to pass further |
|
|
924 | event handling to another thread (you still have to make sure only one |
|
|
925 | thread executes within C<ev_invoke_pending> or C<ev_run> of course). |
|
|
926 | |
|
|
927 | =item int ev_pending_count (loop) |
|
|
928 | |
|
|
929 | Returns the number of pending watchers - zero indicates that no watchers |
|
|
930 | are pending. |
|
|
931 | |
|
|
932 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
|
|
933 | |
|
|
934 | This overrides the invoke pending functionality of the loop: Instead of |
|
|
935 | invoking all pending watchers when there are any, C<ev_run> will call |
|
|
936 | this callback instead. This is useful, for example, when you want to |
|
|
937 | invoke the actual watchers inside another context (another thread etc.). |
|
|
938 | |
|
|
939 | If you want to reset the callback, use C<ev_invoke_pending> as new |
|
|
940 | callback. |
|
|
941 | |
|
|
942 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P)) |
|
|
943 | |
|
|
944 | Sometimes you want to share the same loop between multiple threads. This |
|
|
945 | can be done relatively simply by putting mutex_lock/unlock calls around |
|
|
946 | each call to a libev function. |
|
|
947 | |
|
|
948 | However, C<ev_run> can run an indefinite time, so it is not feasible |
|
|
949 | to wait for it to return. One way around this is to wake up the event |
|
|
950 | loop via C<ev_break> and C<av_async_send>, another way is to set these |
|
|
951 | I<release> and I<acquire> callbacks on the loop. |
|
|
952 | |
|
|
953 | When set, then C<release> will be called just before the thread is |
|
|
954 | suspended waiting for new events, and C<acquire> is called just |
|
|
955 | afterwards. |
|
|
956 | |
|
|
957 | Ideally, C<release> will just call your mutex_unlock function, and |
|
|
958 | C<acquire> will just call the mutex_lock function again. |
|
|
959 | |
|
|
960 | While event loop modifications are allowed between invocations of |
|
|
961 | C<release> and C<acquire> (that's their only purpose after all), no |
|
|
962 | modifications done will affect the event loop, i.e. adding watchers will |
|
|
963 | have no effect on the set of file descriptors being watched, or the time |
|
|
964 | waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it |
|
|
965 | to take note of any changes you made. |
|
|
966 | |
|
|
967 | In theory, threads executing C<ev_run> will be async-cancel safe between |
|
|
968 | invocations of C<release> and C<acquire>. |
|
|
969 | |
|
|
970 | See also the locking example in the C<THREADS> section later in this |
|
|
971 | document. |
|
|
972 | |
|
|
973 | =item ev_set_userdata (loop, void *data) |
|
|
974 | |
|
|
975 | =item ev_userdata (loop) |
|
|
976 | |
|
|
977 | Set and retrieve a single C<void *> associated with a loop. When |
|
|
978 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
|
|
979 | C<0.> |
|
|
980 | |
|
|
981 | These two functions can be used to associate arbitrary data with a loop, |
|
|
982 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
|
|
983 | C<acquire> callbacks described above, but of course can be (ab-)used for |
|
|
984 | any other purpose as well. |
|
|
985 | |
837 | =item ev_loop_verify (loop) |
986 | =item ev_verify (loop) |
838 | |
987 | |
839 | This function only does something when C<EV_VERIFY> support has been |
988 | This function only does something when C<EV_VERIFY> support has been |
840 | compiled in, which is the default for non-minimal builds. It tries to go |
989 | compiled in, which is the default for non-minimal builds. It tries to go |
841 | through all internal structures and checks them for validity. If anything |
990 | through all internal structures and checks them for validity. If anything |
842 | is found to be inconsistent, it will print an error message to standard |
991 | is found to be inconsistent, it will print an error message to standard |
… | |
… | |
853 | |
1002 | |
854 | In the following description, uppercase C<TYPE> in names stands for the |
1003 | In the following description, uppercase C<TYPE> in names stands for the |
855 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
1004 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
856 | watchers and C<ev_io_start> for I/O watchers. |
1005 | watchers and C<ev_io_start> for I/O watchers. |
857 | |
1006 | |
858 | A watcher is a structure that you create and register to record your |
1007 | A watcher is an opaque structure that you allocate and register to record |
859 | interest in some event. For instance, if you want to wait for STDIN to |
1008 | your interest in some event. To make a concrete example, imagine you want |
860 | become readable, you would create an C<ev_io> watcher for that: |
1009 | to wait for STDIN to become readable, you would create an C<ev_io> watcher |
|
|
1010 | for that: |
861 | |
1011 | |
862 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
1012 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
863 | { |
1013 | { |
864 | ev_io_stop (w); |
1014 | ev_io_stop (w); |
865 | ev_unloop (loop, EVUNLOOP_ALL); |
1015 | ev_break (loop, EVBREAK_ALL); |
866 | } |
1016 | } |
867 | |
1017 | |
868 | struct ev_loop *loop = ev_default_loop (0); |
1018 | struct ev_loop *loop = ev_default_loop (0); |
869 | |
1019 | |
870 | ev_io stdin_watcher; |
1020 | ev_io stdin_watcher; |
871 | |
1021 | |
872 | ev_init (&stdin_watcher, my_cb); |
1022 | ev_init (&stdin_watcher, my_cb); |
873 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1023 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
874 | ev_io_start (loop, &stdin_watcher); |
1024 | ev_io_start (loop, &stdin_watcher); |
875 | |
1025 | |
876 | ev_loop (loop, 0); |
1026 | ev_run (loop, 0); |
877 | |
1027 | |
878 | As you can see, you are responsible for allocating the memory for your |
1028 | As you can see, you are responsible for allocating the memory for your |
879 | watcher structures (and it is I<usually> a bad idea to do this on the |
1029 | watcher structures (and it is I<usually> a bad idea to do this on the |
880 | stack). |
1030 | stack). |
881 | |
1031 | |
882 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
1032 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
883 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
1033 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
884 | |
1034 | |
885 | Each watcher structure must be initialised by a call to C<ev_init |
1035 | Each watcher structure must be initialised by a call to C<ev_init (watcher |
886 | (watcher *, callback)>, which expects a callback to be provided. This |
1036 | *, callback)>, which expects a callback to be provided. This callback is |
887 | callback gets invoked each time the event occurs (or, in the case of I/O |
1037 | invoked each time the event occurs (or, in the case of I/O watchers, each |
888 | watchers, each time the event loop detects that the file descriptor given |
1038 | time the event loop detects that the file descriptor given is readable |
889 | is readable and/or writable). |
1039 | and/or writable). |
890 | |
1040 | |
891 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
1041 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
892 | macro to configure it, with arguments specific to the watcher type. There |
1042 | macro to configure it, with arguments specific to the watcher type. There |
893 | is also a macro to combine initialisation and setting in one call: C<< |
1043 | is also a macro to combine initialisation and setting in one call: C<< |
894 | ev_TYPE_init (watcher *, callback, ...) >>. |
1044 | ev_TYPE_init (watcher *, callback, ...) >>. |
… | |
… | |
917 | =item C<EV_WRITE> |
1067 | =item C<EV_WRITE> |
918 | |
1068 | |
919 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1069 | The file descriptor in the C<ev_io> watcher has become readable and/or |
920 | writable. |
1070 | writable. |
921 | |
1071 | |
922 | =item C<EV_TIMEOUT> |
1072 | =item C<EV_TIMER> |
923 | |
1073 | |
924 | The C<ev_timer> watcher has timed out. |
1074 | The C<ev_timer> watcher has timed out. |
925 | |
1075 | |
926 | =item C<EV_PERIODIC> |
1076 | =item C<EV_PERIODIC> |
927 | |
1077 | |
… | |
… | |
945 | |
1095 | |
946 | =item C<EV_PREPARE> |
1096 | =item C<EV_PREPARE> |
947 | |
1097 | |
948 | =item C<EV_CHECK> |
1098 | =item C<EV_CHECK> |
949 | |
1099 | |
950 | All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts |
1100 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
951 | to gather new events, and all C<ev_check> watchers are invoked just after |
1101 | to gather new events, and all C<ev_check> watchers are invoked just after |
952 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
1102 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
953 | received events. Callbacks of both watcher types can start and stop as |
1103 | received events. Callbacks of both watcher types can start and stop as |
954 | many watchers as they want, and all of them will be taken into account |
1104 | many watchers as they want, and all of them will be taken into account |
955 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1105 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
956 | C<ev_loop> from blocking). |
1106 | C<ev_run> from blocking). |
957 | |
1107 | |
958 | =item C<EV_EMBED> |
1108 | =item C<EV_EMBED> |
959 | |
1109 | |
960 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1110 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
961 | |
1111 | |
962 | =item C<EV_FORK> |
1112 | =item C<EV_FORK> |
963 | |
1113 | |
964 | The event loop has been resumed in the child process after fork (see |
1114 | The event loop has been resumed in the child process after fork (see |
965 | C<ev_fork>). |
1115 | C<ev_fork>). |
|
|
1116 | |
|
|
1117 | =item C<EV_CLEANUP> |
|
|
1118 | |
|
|
1119 | The event loop is abotu to be destroyed (see C<ev_cleanup>). |
966 | |
1120 | |
967 | =item C<EV_ASYNC> |
1121 | =item C<EV_ASYNC> |
968 | |
1122 | |
969 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1123 | The given async watcher has been asynchronously notified (see C<ev_async>). |
970 | |
1124 | |
… | |
… | |
992 | programs, though, as the fd could already be closed and reused for another |
1146 | programs, though, as the fd could already be closed and reused for another |
993 | thing, so beware. |
1147 | thing, so beware. |
994 | |
1148 | |
995 | =back |
1149 | =back |
996 | |
1150 | |
|
|
1151 | =head2 WATCHER STATES |
|
|
1152 | |
|
|
1153 | There are various watcher states mentioned throughout this manual - |
|
|
1154 | active, pending and so on. In this section these states and the rules to |
|
|
1155 | transition between them will be described in more detail - and while these |
|
|
1156 | rules might look complicated, they usually do "the right thing". |
|
|
1157 | |
|
|
1158 | =over 4 |
|
|
1159 | |
|
|
1160 | =item initialiased |
|
|
1161 | |
|
|
1162 | Before a watcher can be registered with the event looop it has to be |
|
|
1163 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1164 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
|
|
1165 | |
|
|
1166 | In this state it is simply some block of memory that is suitable for use |
|
|
1167 | in an event loop. It can be moved around, freed, reused etc. at will. |
|
|
1168 | |
|
|
1169 | =item started/running/active |
|
|
1170 | |
|
|
1171 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
|
|
1172 | property of the event loop, and is actively waiting for events. While in |
|
|
1173 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1174 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1175 | and call libev functions on it that are documented to work on active watchers. |
|
|
1176 | |
|
|
1177 | =item pending |
|
|
1178 | |
|
|
1179 | If a watcher is active and libev determines that an event it is interested |
|
|
1180 | in has occurred (such as a timer expiring), it will become pending. It will |
|
|
1181 | stay in this pending state until either it is stopped or its callback is |
|
|
1182 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1183 | callback. |
|
|
1184 | |
|
|
1185 | The watcher might or might not be active while it is pending (for example, |
|
|
1186 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1187 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1188 | but it is still property of the event loop at this time, so cannot be |
|
|
1189 | moved, freed or reused. And if it is active the rules described in the |
|
|
1190 | previous item still apply. |
|
|
1191 | |
|
|
1192 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1193 | via C<ev_feed_event>), in which case it becomes pending without being |
|
|
1194 | active. |
|
|
1195 | |
|
|
1196 | =item stopped |
|
|
1197 | |
|
|
1198 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1199 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
|
|
1200 | latter will clear any pending state the watcher might be in, regardless |
|
|
1201 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1202 | freeing it is often a good idea. |
|
|
1203 | |
|
|
1204 | While stopped (and not pending) the watcher is essentially in the |
|
|
1205 | initialised state, that is it can be reused, moved, modified in any way |
|
|
1206 | you wish. |
|
|
1207 | |
|
|
1208 | =back |
|
|
1209 | |
997 | =head2 GENERIC WATCHER FUNCTIONS |
1210 | =head2 GENERIC WATCHER FUNCTIONS |
998 | |
1211 | |
999 | =over 4 |
1212 | =over 4 |
1000 | |
1213 | |
1001 | =item C<ev_init> (ev_TYPE *watcher, callback) |
1214 | =item C<ev_init> (ev_TYPE *watcher, callback) |
… | |
… | |
1017 | |
1230 | |
1018 | ev_io w; |
1231 | ev_io w; |
1019 | ev_init (&w, my_cb); |
1232 | ev_init (&w, my_cb); |
1020 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1233 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1021 | |
1234 | |
1022 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
1235 | =item C<ev_TYPE_set> (ev_TYPE *watcher, [args]) |
1023 | |
1236 | |
1024 | This macro initialises the type-specific parts of a watcher. You need to |
1237 | This macro initialises the type-specific parts of a watcher. You need to |
1025 | call C<ev_init> at least once before you call this macro, but you can |
1238 | call C<ev_init> at least once before you call this macro, but you can |
1026 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1239 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1027 | macro on a watcher that is active (it can be pending, however, which is a |
1240 | macro on a watcher that is active (it can be pending, however, which is a |
… | |
… | |
1040 | |
1253 | |
1041 | Example: Initialise and set an C<ev_io> watcher in one step. |
1254 | Example: Initialise and set an C<ev_io> watcher in one step. |
1042 | |
1255 | |
1043 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1256 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1044 | |
1257 | |
1045 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
1258 | =item C<ev_TYPE_start> (loop, ev_TYPE *watcher) |
1046 | |
1259 | |
1047 | Starts (activates) the given watcher. Only active watchers will receive |
1260 | Starts (activates) the given watcher. Only active watchers will receive |
1048 | events. If the watcher is already active nothing will happen. |
1261 | events. If the watcher is already active nothing will happen. |
1049 | |
1262 | |
1050 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1263 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1051 | whole section. |
1264 | whole section. |
1052 | |
1265 | |
1053 | ev_io_start (EV_DEFAULT_UC, &w); |
1266 | ev_io_start (EV_DEFAULT_UC, &w); |
1054 | |
1267 | |
1055 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1268 | =item C<ev_TYPE_stop> (loop, ev_TYPE *watcher) |
1056 | |
1269 | |
1057 | Stops the given watcher if active, and clears the pending status (whether |
1270 | Stops the given watcher if active, and clears the pending status (whether |
1058 | the watcher was active or not). |
1271 | the watcher was active or not). |
1059 | |
1272 | |
1060 | It is possible that stopped watchers are pending - for example, |
1273 | It is possible that stopped watchers are pending - for example, |
… | |
… | |
1085 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1298 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1086 | |
1299 | |
1087 | Change the callback. You can change the callback at virtually any time |
1300 | Change the callback. You can change the callback at virtually any time |
1088 | (modulo threads). |
1301 | (modulo threads). |
1089 | |
1302 | |
1090 | =item ev_set_priority (ev_TYPE *watcher, priority) |
1303 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1091 | |
1304 | |
1092 | =item int ev_priority (ev_TYPE *watcher) |
1305 | =item int ev_priority (ev_TYPE *watcher) |
1093 | |
1306 | |
1094 | Set and query the priority of the watcher. The priority is a small |
1307 | Set and query the priority of the watcher. The priority is a small |
1095 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1308 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
… | |
… | |
1126 | returns its C<revents> bitset (as if its callback was invoked). If the |
1339 | returns its C<revents> bitset (as if its callback was invoked). If the |
1127 | watcher isn't pending it does nothing and returns C<0>. |
1340 | watcher isn't pending it does nothing and returns C<0>. |
1128 | |
1341 | |
1129 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1342 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1130 | callback to be invoked, which can be accomplished with this function. |
1343 | callback to be invoked, which can be accomplished with this function. |
|
|
1344 | |
|
|
1345 | =item ev_feed_event (loop, ev_TYPE *watcher, int revents) |
|
|
1346 | |
|
|
1347 | Feeds the given event set into the event loop, as if the specified event |
|
|
1348 | had happened for the specified watcher (which must be a pointer to an |
|
|
1349 | initialised but not necessarily started event watcher). Obviously you must |
|
|
1350 | not free the watcher as long as it has pending events. |
|
|
1351 | |
|
|
1352 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1353 | C<ev_clear_pending> will clear the pending event, even if the watcher was |
|
|
1354 | not started in the first place. |
|
|
1355 | |
|
|
1356 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
|
|
1357 | functions that do not need a watcher. |
1131 | |
1358 | |
1132 | =back |
1359 | =back |
1133 | |
1360 | |
1134 | |
1361 | |
1135 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1362 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
1184 | #include <stddef.h> |
1411 | #include <stddef.h> |
1185 | |
1412 | |
1186 | static void |
1413 | static void |
1187 | t1_cb (EV_P_ ev_timer *w, int revents) |
1414 | t1_cb (EV_P_ ev_timer *w, int revents) |
1188 | { |
1415 | { |
1189 | struct my_biggy big = (struct my_biggy * |
1416 | struct my_biggy big = (struct my_biggy *) |
1190 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1417 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1191 | } |
1418 | } |
1192 | |
1419 | |
1193 | static void |
1420 | static void |
1194 | t2_cb (EV_P_ ev_timer *w, int revents) |
1421 | t2_cb (EV_P_ ev_timer *w, int revents) |
1195 | { |
1422 | { |
1196 | struct my_biggy big = (struct my_biggy * |
1423 | struct my_biggy big = (struct my_biggy *) |
1197 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1424 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1198 | } |
1425 | } |
1199 | |
1426 | |
1200 | =head2 WATCHER PRIORITY MODELS |
1427 | =head2 WATCHER PRIORITY MODELS |
1201 | |
1428 | |
… | |
… | |
1246 | |
1473 | |
1247 | For example, to emulate how many other event libraries handle priorities, |
1474 | For example, to emulate how many other event libraries handle priorities, |
1248 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1475 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1249 | the normal watcher callback, you just start the idle watcher. The real |
1476 | the normal watcher callback, you just start the idle watcher. The real |
1250 | processing is done in the idle watcher callback. This causes libev to |
1477 | processing is done in the idle watcher callback. This causes libev to |
1251 | continously poll and process kernel event data for the watcher, but when |
1478 | continuously poll and process kernel event data for the watcher, but when |
1252 | the lock-out case is known to be rare (which in turn is rare :), this is |
1479 | the lock-out case is known to be rare (which in turn is rare :), this is |
1253 | workable. |
1480 | workable. |
1254 | |
1481 | |
1255 | Usually, however, the lock-out model implemented that way will perform |
1482 | Usually, however, the lock-out model implemented that way will perform |
1256 | miserably under the type of load it was designed to handle. In that case, |
1483 | miserably under the type of load it was designed to handle. In that case, |
… | |
… | |
1270 | { |
1497 | { |
1271 | // stop the I/O watcher, we received the event, but |
1498 | // stop the I/O watcher, we received the event, but |
1272 | // are not yet ready to handle it. |
1499 | // are not yet ready to handle it. |
1273 | ev_io_stop (EV_A_ w); |
1500 | ev_io_stop (EV_A_ w); |
1274 | |
1501 | |
1275 | // start the idle watcher to ahndle the actual event. |
1502 | // start the idle watcher to handle the actual event. |
1276 | // it will not be executed as long as other watchers |
1503 | // it will not be executed as long as other watchers |
1277 | // with the default priority are receiving events. |
1504 | // with the default priority are receiving events. |
1278 | ev_idle_start (EV_A_ &idle); |
1505 | ev_idle_start (EV_A_ &idle); |
1279 | } |
1506 | } |
1280 | |
1507 | |
1281 | static void |
1508 | static void |
1282 | idle-cb (EV_P_ ev_idle *w, int revents) |
1509 | idle_cb (EV_P_ ev_idle *w, int revents) |
1283 | { |
1510 | { |
1284 | // actual processing |
1511 | // actual processing |
1285 | read (STDIN_FILENO, ...); |
1512 | read (STDIN_FILENO, ...); |
1286 | |
1513 | |
1287 | // have to start the I/O watcher again, as |
1514 | // have to start the I/O watcher again, as |
… | |
… | |
1334 | |
1561 | |
1335 | If you cannot use non-blocking mode, then force the use of a |
1562 | If you cannot use non-blocking mode, then force the use of a |
1336 | known-to-be-good backend (at the time of this writing, this includes only |
1563 | known-to-be-good backend (at the time of this writing, this includes only |
1337 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1564 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1338 | descriptors for which non-blocking operation makes no sense (such as |
1565 | descriptors for which non-blocking operation makes no sense (such as |
1339 | files) - libev doesn't guarentee any specific behaviour in that case. |
1566 | files) - libev doesn't guarantee any specific behaviour in that case. |
1340 | |
1567 | |
1341 | Another thing you have to watch out for is that it is quite easy to |
1568 | Another thing you have to watch out for is that it is quite easy to |
1342 | receive "spurious" readiness notifications, that is your callback might |
1569 | receive "spurious" readiness notifications, that is your callback might |
1343 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1570 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1344 | because there is no data. Not only are some backends known to create a |
1571 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1409 | |
1636 | |
1410 | So when you encounter spurious, unexplained daemon exits, make sure you |
1637 | So when you encounter spurious, unexplained daemon exits, make sure you |
1411 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1638 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1412 | somewhere, as that would have given you a big clue). |
1639 | somewhere, as that would have given you a big clue). |
1413 | |
1640 | |
|
|
1641 | =head3 The special problem of accept()ing when you can't |
|
|
1642 | |
|
|
1643 | Many implementations of the POSIX C<accept> function (for example, |
|
|
1644 | found in post-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1645 | connection from the pending queue in all error cases. |
|
|
1646 | |
|
|
1647 | For example, larger servers often run out of file descriptors (because |
|
|
1648 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
|
|
1649 | rejecting the connection, leading to libev signalling readiness on |
|
|
1650 | the next iteration again (the connection still exists after all), and |
|
|
1651 | typically causing the program to loop at 100% CPU usage. |
|
|
1652 | |
|
|
1653 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1654 | operating systems, there is usually little the app can do to remedy the |
|
|
1655 | situation, and no known thread-safe method of removing the connection to |
|
|
1656 | cope with overload is known (to me). |
|
|
1657 | |
|
|
1658 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1659 | - when the program encounters an overload, it will just loop until the |
|
|
1660 | situation is over. While this is a form of busy waiting, no OS offers an |
|
|
1661 | event-based way to handle this situation, so it's the best one can do. |
|
|
1662 | |
|
|
1663 | A better way to handle the situation is to log any errors other than |
|
|
1664 | C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such |
|
|
1665 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1666 | what could be wrong ("raise the ulimit!"). For extra points one could stop |
|
|
1667 | the C<ev_io> watcher on the listening fd "for a while", which reduces CPU |
|
|
1668 | usage. |
|
|
1669 | |
|
|
1670 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1671 | descriptor for overload situations (e.g. by opening F</dev/null>), and |
|
|
1672 | when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>, |
|
|
1673 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1674 | clients under typical overload conditions. |
|
|
1675 | |
|
|
1676 | The last way to handle it is to simply log the error and C<exit>, as |
|
|
1677 | is often done with C<malloc> failures, but this results in an easy |
|
|
1678 | opportunity for a DoS attack. |
1414 | |
1679 | |
1415 | =head3 Watcher-Specific Functions |
1680 | =head3 Watcher-Specific Functions |
1416 | |
1681 | |
1417 | =over 4 |
1682 | =over 4 |
1418 | |
1683 | |
… | |
… | |
1450 | ... |
1715 | ... |
1451 | struct ev_loop *loop = ev_default_init (0); |
1716 | struct ev_loop *loop = ev_default_init (0); |
1452 | ev_io stdin_readable; |
1717 | ev_io stdin_readable; |
1453 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1718 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1454 | ev_io_start (loop, &stdin_readable); |
1719 | ev_io_start (loop, &stdin_readable); |
1455 | ev_loop (loop, 0); |
1720 | ev_run (loop, 0); |
1456 | |
1721 | |
1457 | |
1722 | |
1458 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1723 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1459 | |
1724 | |
1460 | Timer watchers are simple relative timers that generate an event after a |
1725 | Timer watchers are simple relative timers that generate an event after a |
… | |
… | |
1465 | year, it will still time out after (roughly) one hour. "Roughly" because |
1730 | year, it will still time out after (roughly) one hour. "Roughly" because |
1466 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1731 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1467 | monotonic clock option helps a lot here). |
1732 | monotonic clock option helps a lot here). |
1468 | |
1733 | |
1469 | The callback is guaranteed to be invoked only I<after> its timeout has |
1734 | The callback is guaranteed to be invoked only I<after> its timeout has |
1470 | passed. If multiple timers become ready during the same loop iteration |
1735 | passed (not I<at>, so on systems with very low-resolution clocks this |
1471 | then the ones with earlier time-out values are invoked before ones with |
1736 | might introduce a small delay). If multiple timers become ready during the |
1472 | later time-out values (but this is no longer true when a callback calls |
1737 | same loop iteration then the ones with earlier time-out values are invoked |
1473 | C<ev_loop> recursively). |
1738 | before ones of the same priority with later time-out values (but this is |
|
|
1739 | no longer true when a callback calls C<ev_run> recursively). |
1474 | |
1740 | |
1475 | =head3 Be smart about timeouts |
1741 | =head3 Be smart about timeouts |
1476 | |
1742 | |
1477 | Many real-world problems involve some kind of timeout, usually for error |
1743 | Many real-world problems involve some kind of timeout, usually for error |
1478 | recovery. A typical example is an HTTP request - if the other side hangs, |
1744 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
1522 | C<after> argument to C<ev_timer_set>, and only ever use the C<repeat> |
1788 | C<after> argument to C<ev_timer_set>, and only ever use the C<repeat> |
1523 | member and C<ev_timer_again>. |
1789 | member and C<ev_timer_again>. |
1524 | |
1790 | |
1525 | At start: |
1791 | At start: |
1526 | |
1792 | |
1527 | ev_timer_init (timer, callback); |
1793 | ev_init (timer, callback); |
1528 | timer->repeat = 60.; |
1794 | timer->repeat = 60.; |
1529 | ev_timer_again (loop, timer); |
1795 | ev_timer_again (loop, timer); |
1530 | |
1796 | |
1531 | Each time there is some activity: |
1797 | Each time there is some activity: |
1532 | |
1798 | |
… | |
… | |
1564 | ev_tstamp timeout = last_activity + 60.; |
1830 | ev_tstamp timeout = last_activity + 60.; |
1565 | |
1831 | |
1566 | // if last_activity + 60. is older than now, we did time out |
1832 | // if last_activity + 60. is older than now, we did time out |
1567 | if (timeout < now) |
1833 | if (timeout < now) |
1568 | { |
1834 | { |
1569 | // timeout occured, take action |
1835 | // timeout occurred, take action |
1570 | } |
1836 | } |
1571 | else |
1837 | else |
1572 | { |
1838 | { |
1573 | // callback was invoked, but there was some activity, re-arm |
1839 | // callback was invoked, but there was some activity, re-arm |
1574 | // the watcher to fire in last_activity + 60, which is |
1840 | // the watcher to fire in last_activity + 60, which is |
… | |
… | |
1594 | |
1860 | |
1595 | To start the timer, simply initialise the watcher and set C<last_activity> |
1861 | To start the timer, simply initialise the watcher and set C<last_activity> |
1596 | to the current time (meaning we just have some activity :), then call the |
1862 | to the current time (meaning we just have some activity :), then call the |
1597 | callback, which will "do the right thing" and start the timer: |
1863 | callback, which will "do the right thing" and start the timer: |
1598 | |
1864 | |
1599 | ev_timer_init (timer, callback); |
1865 | ev_init (timer, callback); |
1600 | last_activity = ev_now (loop); |
1866 | last_activity = ev_now (loop); |
1601 | callback (loop, timer, EV_TIMEOUT); |
1867 | callback (loop, timer, EV_TIMER); |
1602 | |
1868 | |
1603 | And when there is some activity, simply store the current time in |
1869 | And when there is some activity, simply store the current time in |
1604 | C<last_activity>, no libev calls at all: |
1870 | C<last_activity>, no libev calls at all: |
1605 | |
1871 | |
1606 | last_actiivty = ev_now (loop); |
1872 | last_activity = ev_now (loop); |
1607 | |
1873 | |
1608 | This technique is slightly more complex, but in most cases where the |
1874 | This technique is slightly more complex, but in most cases where the |
1609 | time-out is unlikely to be triggered, much more efficient. |
1875 | time-out is unlikely to be triggered, much more efficient. |
1610 | |
1876 | |
1611 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
1877 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
… | |
… | |
1649 | |
1915 | |
1650 | =head3 The special problem of time updates |
1916 | =head3 The special problem of time updates |
1651 | |
1917 | |
1652 | Establishing the current time is a costly operation (it usually takes at |
1918 | Establishing the current time is a costly operation (it usually takes at |
1653 | least two system calls): EV therefore updates its idea of the current |
1919 | least two system calls): EV therefore updates its idea of the current |
1654 | time only before and after C<ev_loop> collects new events, which causes a |
1920 | time only before and after C<ev_run> collects new events, which causes a |
1655 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1921 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1656 | lots of events in one iteration. |
1922 | lots of events in one iteration. |
1657 | |
1923 | |
1658 | The relative timeouts are calculated relative to the C<ev_now ()> |
1924 | The relative timeouts are calculated relative to the C<ev_now ()> |
1659 | time. This is usually the right thing as this timestamp refers to the time |
1925 | time. This is usually the right thing as this timestamp refers to the time |
… | |
… | |
1665 | |
1931 | |
1666 | If the event loop is suspended for a long time, you can also force an |
1932 | If the event loop is suspended for a long time, you can also force an |
1667 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1933 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1668 | ()>. |
1934 | ()>. |
1669 | |
1935 | |
|
|
1936 | =head3 The special problems of suspended animation |
|
|
1937 | |
|
|
1938 | When you leave the server world it is quite customary to hit machines that |
|
|
1939 | can suspend/hibernate - what happens to the clocks during such a suspend? |
|
|
1940 | |
|
|
1941 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
1942 | all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue |
|
|
1943 | to run until the system is suspended, but they will not advance while the |
|
|
1944 | system is suspended. That means, on resume, it will be as if the program |
|
|
1945 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
1946 | towards C<ev_timer> when a monotonic clock source is used. The real time |
|
|
1947 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
1948 | long suspend would be detected as a time jump by libev, and timers would |
|
|
1949 | be adjusted accordingly. |
|
|
1950 | |
|
|
1951 | I would not be surprised to see different behaviour in different between |
|
|
1952 | operating systems, OS versions or even different hardware. |
|
|
1953 | |
|
|
1954 | The other form of suspend (job control, or sending a SIGSTOP) will see a |
|
|
1955 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
1956 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
1957 | then you can expect C<ev_timer>s to expire as the full suspension time |
|
|
1958 | will be counted towards the timers. When no monotonic clock source is in |
|
|
1959 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
1960 | |
|
|
1961 | It might be beneficial for this latter case to call C<ev_suspend> |
|
|
1962 | and C<ev_resume> in code that handles C<SIGTSTP>, to at least get |
|
|
1963 | deterministic behaviour in this case (you can do nothing against |
|
|
1964 | C<SIGSTOP>). |
|
|
1965 | |
1670 | =head3 Watcher-Specific Functions and Data Members |
1966 | =head3 Watcher-Specific Functions and Data Members |
1671 | |
1967 | |
1672 | =over 4 |
1968 | =over 4 |
1673 | |
1969 | |
1674 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1970 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
1700 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1996 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1701 | |
1997 | |
1702 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1998 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1703 | usage example. |
1999 | usage example. |
1704 | |
2000 | |
|
|
2001 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
|
|
2002 | |
|
|
2003 | Returns the remaining time until a timer fires. If the timer is active, |
|
|
2004 | then this time is relative to the current event loop time, otherwise it's |
|
|
2005 | the timeout value currently configured. |
|
|
2006 | |
|
|
2007 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
|
|
2008 | C<5>. When the timer is started and one second passes, C<ev_timer_remaining> |
|
|
2009 | will return C<4>. When the timer expires and is restarted, it will return |
|
|
2010 | roughly C<7> (likely slightly less as callback invocation takes some time, |
|
|
2011 | too), and so on. |
|
|
2012 | |
1705 | =item ev_tstamp repeat [read-write] |
2013 | =item ev_tstamp repeat [read-write] |
1706 | |
2014 | |
1707 | The current C<repeat> value. Will be used each time the watcher times out |
2015 | The current C<repeat> value. Will be used each time the watcher times out |
1708 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
2016 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
1709 | which is also when any modifications are taken into account. |
2017 | which is also when any modifications are taken into account. |
… | |
… | |
1734 | } |
2042 | } |
1735 | |
2043 | |
1736 | ev_timer mytimer; |
2044 | ev_timer mytimer; |
1737 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2045 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1738 | ev_timer_again (&mytimer); /* start timer */ |
2046 | ev_timer_again (&mytimer); /* start timer */ |
1739 | ev_loop (loop, 0); |
2047 | ev_run (loop, 0); |
1740 | |
2048 | |
1741 | // and in some piece of code that gets executed on any "activity": |
2049 | // and in some piece of code that gets executed on any "activity": |
1742 | // reset the timeout to start ticking again at 10 seconds |
2050 | // reset the timeout to start ticking again at 10 seconds |
1743 | ev_timer_again (&mytimer); |
2051 | ev_timer_again (&mytimer); |
1744 | |
2052 | |
… | |
… | |
1770 | |
2078 | |
1771 | As with timers, the callback is guaranteed to be invoked only when the |
2079 | As with timers, the callback is guaranteed to be invoked only when the |
1772 | point in time where it is supposed to trigger has passed. If multiple |
2080 | point in time where it is supposed to trigger has passed. If multiple |
1773 | timers become ready during the same loop iteration then the ones with |
2081 | timers become ready during the same loop iteration then the ones with |
1774 | earlier time-out values are invoked before ones with later time-out values |
2082 | earlier time-out values are invoked before ones with later time-out values |
1775 | (but this is no longer true when a callback calls C<ev_loop> recursively). |
2083 | (but this is no longer true when a callback calls C<ev_run> recursively). |
1776 | |
2084 | |
1777 | =head3 Watcher-Specific Functions and Data Members |
2085 | =head3 Watcher-Specific Functions and Data Members |
1778 | |
2086 | |
1779 | =over 4 |
2087 | =over 4 |
1780 | |
2088 | |
… | |
… | |
1908 | Example: Call a callback every hour, or, more precisely, whenever the |
2216 | Example: Call a callback every hour, or, more precisely, whenever the |
1909 | system time is divisible by 3600. The callback invocation times have |
2217 | system time is divisible by 3600. The callback invocation times have |
1910 | potentially a lot of jitter, but good long-term stability. |
2218 | potentially a lot of jitter, but good long-term stability. |
1911 | |
2219 | |
1912 | static void |
2220 | static void |
1913 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2221 | clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
1914 | { |
2222 | { |
1915 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2223 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1916 | } |
2224 | } |
1917 | |
2225 | |
1918 | ev_periodic hourly_tick; |
2226 | ev_periodic hourly_tick; |
… | |
… | |
1944 | Signal watchers will trigger an event when the process receives a specific |
2252 | Signal watchers will trigger an event when the process receives a specific |
1945 | signal one or more times. Even though signals are very asynchronous, libev |
2253 | signal one or more times. Even though signals are very asynchronous, libev |
1946 | will try it's best to deliver signals synchronously, i.e. as part of the |
2254 | will try it's best to deliver signals synchronously, i.e. as part of the |
1947 | normal event processing, like any other event. |
2255 | normal event processing, like any other event. |
1948 | |
2256 | |
1949 | If you want signals asynchronously, just use C<sigaction> as you would |
2257 | If you want signals to be delivered truly asynchronously, just use |
1950 | do without libev and forget about sharing the signal. You can even use |
2258 | C<sigaction> as you would do without libev and forget about sharing |
1951 | C<ev_async> from a signal handler to synchronously wake up an event loop. |
2259 | the signal. You can even use C<ev_async> from a signal handler to |
|
|
2260 | synchronously wake up an event loop. |
1952 | |
2261 | |
1953 | You can configure as many watchers as you like per signal. Only when the |
2262 | You can configure as many watchers as you like for the same signal, but |
|
|
2263 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
|
|
2264 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
|
|
2265 | C<SIGINT> in both the default loop and another loop at the same time. At |
|
|
2266 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
|
|
2267 | |
1954 | first watcher gets started will libev actually register a signal handler |
2268 | When the first watcher gets started will libev actually register something |
1955 | with the kernel (thus it coexists with your own signal handlers as long as |
2269 | with the kernel (thus it coexists with your own signal handlers as long as |
1956 | you don't register any with libev for the same signal). Similarly, when |
2270 | you don't register any with libev for the same signal). |
1957 | the last signal watcher for a signal is stopped, libev will reset the |
|
|
1958 | signal handler to SIG_DFL (regardless of what it was set to before). |
|
|
1959 | |
2271 | |
1960 | If possible and supported, libev will install its handlers with |
2272 | If possible and supported, libev will install its handlers with |
1961 | C<SA_RESTART> behaviour enabled, so system calls should not be unduly |
2273 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
1962 | interrupted. If you have a problem with system calls getting interrupted by |
2274 | not be unduly interrupted. If you have a problem with system calls getting |
1963 | signals you can block all signals in an C<ev_check> watcher and unblock |
2275 | interrupted by signals you can block all signals in an C<ev_check> watcher |
1964 | them in an C<ev_prepare> watcher. |
2276 | and unblock them in an C<ev_prepare> watcher. |
|
|
2277 | |
|
|
2278 | =head3 The special problem of inheritance over fork/execve/pthread_create |
|
|
2279 | |
|
|
2280 | Both the signal mask (C<sigprocmask>) and the signal disposition |
|
|
2281 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
|
|
2282 | stopping it again), that is, libev might or might not block the signal, |
|
|
2283 | and might or might not set or restore the installed signal handler. |
|
|
2284 | |
|
|
2285 | While this does not matter for the signal disposition (libev never |
|
|
2286 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
|
|
2287 | C<execve>), this matters for the signal mask: many programs do not expect |
|
|
2288 | certain signals to be blocked. |
|
|
2289 | |
|
|
2290 | This means that before calling C<exec> (from the child) you should reset |
|
|
2291 | the signal mask to whatever "default" you expect (all clear is a good |
|
|
2292 | choice usually). |
|
|
2293 | |
|
|
2294 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2295 | to install a fork handler with C<pthread_atfork> that resets it. That will |
|
|
2296 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2297 | |
|
|
2298 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2299 | unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces |
|
|
2300 | the window of opportunity for problems, it will not go away, as libev |
|
|
2301 | I<has> to modify the signal mask, at least temporarily. |
|
|
2302 | |
|
|
2303 | So I can't stress this enough: I<If you do not reset your signal mask when |
|
|
2304 | you expect it to be empty, you have a race condition in your code>. This |
|
|
2305 | is not a libev-specific thing, this is true for most event libraries. |
1965 | |
2306 | |
1966 | =head3 Watcher-Specific Functions and Data Members |
2307 | =head3 Watcher-Specific Functions and Data Members |
1967 | |
2308 | |
1968 | =over 4 |
2309 | =over 4 |
1969 | |
2310 | |
… | |
… | |
1985 | Example: Try to exit cleanly on SIGINT. |
2326 | Example: Try to exit cleanly on SIGINT. |
1986 | |
2327 | |
1987 | static void |
2328 | static void |
1988 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2329 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
1989 | { |
2330 | { |
1990 | ev_unloop (loop, EVUNLOOP_ALL); |
2331 | ev_break (loop, EVBREAK_ALL); |
1991 | } |
2332 | } |
1992 | |
2333 | |
1993 | ev_signal signal_watcher; |
2334 | ev_signal signal_watcher; |
1994 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2335 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1995 | ev_signal_start (loop, &signal_watcher); |
2336 | ev_signal_start (loop, &signal_watcher); |
… | |
… | |
2001 | some child status changes (most typically when a child of yours dies or |
2342 | some child status changes (most typically when a child of yours dies or |
2002 | exits). It is permissible to install a child watcher I<after> the child |
2343 | exits). It is permissible to install a child watcher I<after> the child |
2003 | has been forked (which implies it might have already exited), as long |
2344 | has been forked (which implies it might have already exited), as long |
2004 | as the event loop isn't entered (or is continued from a watcher), i.e., |
2345 | as the event loop isn't entered (or is continued from a watcher), i.e., |
2005 | forking and then immediately registering a watcher for the child is fine, |
2346 | forking and then immediately registering a watcher for the child is fine, |
2006 | but forking and registering a watcher a few event loop iterations later is |
2347 | but forking and registering a watcher a few event loop iterations later or |
2007 | not. |
2348 | in the next callback invocation is not. |
2008 | |
2349 | |
2009 | Only the default event loop is capable of handling signals, and therefore |
2350 | Only the default event loop is capable of handling signals, and therefore |
2010 | you can only register child watchers in the default event loop. |
2351 | you can only register child watchers in the default event loop. |
2011 | |
2352 | |
|
|
2353 | Due to some design glitches inside libev, child watchers will always be |
|
|
2354 | handled at maximum priority (their priority is set to C<EV_MAXPRI> by |
|
|
2355 | libev) |
|
|
2356 | |
2012 | =head3 Process Interaction |
2357 | =head3 Process Interaction |
2013 | |
2358 | |
2014 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2359 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2015 | initialised. This is necessary to guarantee proper behaviour even if |
2360 | initialised. This is necessary to guarantee proper behaviour even if the |
2016 | the first child watcher is started after the child exits. The occurrence |
2361 | first child watcher is started after the child exits. The occurrence |
2017 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2362 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2018 | synchronously as part of the event loop processing. Libev always reaps all |
2363 | synchronously as part of the event loop processing. Libev always reaps all |
2019 | children, even ones not watched. |
2364 | children, even ones not watched. |
2020 | |
2365 | |
2021 | =head3 Overriding the Built-In Processing |
2366 | =head3 Overriding the Built-In Processing |
… | |
… | |
2031 | =head3 Stopping the Child Watcher |
2376 | =head3 Stopping the Child Watcher |
2032 | |
2377 | |
2033 | Currently, the child watcher never gets stopped, even when the |
2378 | Currently, the child watcher never gets stopped, even when the |
2034 | child terminates, so normally one needs to stop the watcher in the |
2379 | child terminates, so normally one needs to stop the watcher in the |
2035 | callback. Future versions of libev might stop the watcher automatically |
2380 | callback. Future versions of libev might stop the watcher automatically |
2036 | when a child exit is detected. |
2381 | when a child exit is detected (calling C<ev_child_stop> twice is not a |
|
|
2382 | problem). |
2037 | |
2383 | |
2038 | =head3 Watcher-Specific Functions and Data Members |
2384 | =head3 Watcher-Specific Functions and Data Members |
2039 | |
2385 | |
2040 | =over 4 |
2386 | =over 4 |
2041 | |
2387 | |
… | |
… | |
2367 | // no longer anything immediate to do. |
2713 | // no longer anything immediate to do. |
2368 | } |
2714 | } |
2369 | |
2715 | |
2370 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2716 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2371 | ev_idle_init (idle_watcher, idle_cb); |
2717 | ev_idle_init (idle_watcher, idle_cb); |
2372 | ev_idle_start (loop, idle_cb); |
2718 | ev_idle_start (loop, idle_watcher); |
2373 | |
2719 | |
2374 | |
2720 | |
2375 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2721 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2376 | |
2722 | |
2377 | Prepare and check watchers are usually (but not always) used in pairs: |
2723 | Prepare and check watchers are usually (but not always) used in pairs: |
2378 | prepare watchers get invoked before the process blocks and check watchers |
2724 | prepare watchers get invoked before the process blocks and check watchers |
2379 | afterwards. |
2725 | afterwards. |
2380 | |
2726 | |
2381 | You I<must not> call C<ev_loop> or similar functions that enter |
2727 | You I<must not> call C<ev_run> or similar functions that enter |
2382 | the current event loop from either C<ev_prepare> or C<ev_check> |
2728 | the current event loop from either C<ev_prepare> or C<ev_check> |
2383 | watchers. Other loops than the current one are fine, however. The |
2729 | watchers. Other loops than the current one are fine, however. The |
2384 | rationale behind this is that you do not need to check for recursion in |
2730 | rationale behind this is that you do not need to check for recursion in |
2385 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2731 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2386 | C<ev_check> so if you have one watcher of each kind they will always be |
2732 | C<ev_check> so if you have one watcher of each kind they will always be |
… | |
… | |
2470 | struct pollfd fds [nfd]; |
2816 | struct pollfd fds [nfd]; |
2471 | // actual code will need to loop here and realloc etc. |
2817 | // actual code will need to loop here and realloc etc. |
2472 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2818 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2473 | |
2819 | |
2474 | /* the callback is illegal, but won't be called as we stop during check */ |
2820 | /* the callback is illegal, but won't be called as we stop during check */ |
2475 | ev_timer_init (&tw, 0, timeout * 1e-3); |
2821 | ev_timer_init (&tw, 0, timeout * 1e-3, 0.); |
2476 | ev_timer_start (loop, &tw); |
2822 | ev_timer_start (loop, &tw); |
2477 | |
2823 | |
2478 | // create one ev_io per pollfd |
2824 | // create one ev_io per pollfd |
2479 | for (int i = 0; i < nfd; ++i) |
2825 | for (int i = 0; i < nfd; ++i) |
2480 | { |
2826 | { |
… | |
… | |
2554 | |
2900 | |
2555 | if (timeout >= 0) |
2901 | if (timeout >= 0) |
2556 | // create/start timer |
2902 | // create/start timer |
2557 | |
2903 | |
2558 | // poll |
2904 | // poll |
2559 | ev_loop (EV_A_ 0); |
2905 | ev_run (EV_A_ 0); |
2560 | |
2906 | |
2561 | // stop timer again |
2907 | // stop timer again |
2562 | if (timeout >= 0) |
2908 | if (timeout >= 0) |
2563 | ev_timer_stop (EV_A_ &to); |
2909 | ev_timer_stop (EV_A_ &to); |
2564 | |
2910 | |
… | |
… | |
2642 | if you do not want that, you need to temporarily stop the embed watcher). |
2988 | if you do not want that, you need to temporarily stop the embed watcher). |
2643 | |
2989 | |
2644 | =item ev_embed_sweep (loop, ev_embed *) |
2990 | =item ev_embed_sweep (loop, ev_embed *) |
2645 | |
2991 | |
2646 | Make a single, non-blocking sweep over the embedded loop. This works |
2992 | Make a single, non-blocking sweep over the embedded loop. This works |
2647 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
2993 | similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most |
2648 | appropriate way for embedded loops. |
2994 | appropriate way for embedded loops. |
2649 | |
2995 | |
2650 | =item struct ev_loop *other [read-only] |
2996 | =item struct ev_loop *other [read-only] |
2651 | |
2997 | |
2652 | The embedded event loop. |
2998 | The embedded event loop. |
… | |
… | |
2712 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3058 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2713 | handlers will be invoked, too, of course. |
3059 | handlers will be invoked, too, of course. |
2714 | |
3060 | |
2715 | =head3 The special problem of life after fork - how is it possible? |
3061 | =head3 The special problem of life after fork - how is it possible? |
2716 | |
3062 | |
2717 | Most uses of C<fork()> consist of forking, then some simple calls to ste |
3063 | Most uses of C<fork()> consist of forking, then some simple calls to set |
2718 | up/change the process environment, followed by a call to C<exec()>. This |
3064 | up/change the process environment, followed by a call to C<exec()>. This |
2719 | sequence should be handled by libev without any problems. |
3065 | sequence should be handled by libev without any problems. |
2720 | |
3066 | |
2721 | This changes when the application actually wants to do event handling |
3067 | This changes when the application actually wants to do event handling |
2722 | in the child, or both parent in child, in effect "continuing" after the |
3068 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
2738 | disadvantage of having to use multiple event loops (which do not support |
3084 | disadvantage of having to use multiple event loops (which do not support |
2739 | signal watchers). |
3085 | signal watchers). |
2740 | |
3086 | |
2741 | When this is not possible, or you want to use the default loop for |
3087 | When this is not possible, or you want to use the default loop for |
2742 | other reasons, then in the process that wants to start "fresh", call |
3088 | other reasons, then in the process that wants to start "fresh", call |
2743 | C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying |
3089 | C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>. |
2744 | the default loop will "orphan" (not stop) all registered watchers, so you |
3090 | Destroying the default loop will "orphan" (not stop) all registered |
2745 | have to be careful not to execute code that modifies those watchers. Note |
3091 | watchers, so you have to be careful not to execute code that modifies |
2746 | also that in that case, you have to re-register any signal watchers. |
3092 | those watchers. Note also that in that case, you have to re-register any |
|
|
3093 | signal watchers. |
2747 | |
3094 | |
2748 | =head3 Watcher-Specific Functions and Data Members |
3095 | =head3 Watcher-Specific Functions and Data Members |
2749 | |
3096 | |
2750 | =over 4 |
3097 | =over 4 |
2751 | |
3098 | |
2752 | =item ev_fork_init (ev_signal *, callback) |
3099 | =item ev_fork_init (ev_fork *, callback) |
2753 | |
3100 | |
2754 | Initialises and configures the fork watcher - it has no parameters of any |
3101 | Initialises and configures the fork watcher - it has no parameters of any |
2755 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
3102 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
2756 | believe me. |
3103 | believe me. |
2757 | |
3104 | |
2758 | =back |
3105 | =back |
2759 | |
3106 | |
2760 | |
3107 | |
|
|
3108 | =head2 C<ev_cleanup> - even the best things end |
|
|
3109 | |
|
|
3110 | Cleanup watchers are called just before the event loop they are registered |
|
|
3111 | with is being destroyed. |
|
|
3112 | |
|
|
3113 | While there is no guarantee that the event loop gets destroyed, cleanup |
|
|
3114 | watchers provide a convenient method to install cleanup watchers for your |
|
|
3115 | program, worker threads and so on - you just to make sure to destroy the |
|
|
3116 | loop when you want them to be invoked. |
|
|
3117 | |
|
|
3118 | =head3 Watcher-Specific Functions and Data Members |
|
|
3119 | |
|
|
3120 | =over 4 |
|
|
3121 | |
|
|
3122 | =item ev_cleanup_init (ev_cleanup *, callback) |
|
|
3123 | |
|
|
3124 | Initialises and configures the cleanup watcher - it has no parameters of |
|
|
3125 | any kind. There is a C<ev_cleanup_set> macro, but using it is utterly |
|
|
3126 | pointless, believe me. |
|
|
3127 | |
|
|
3128 | =back |
|
|
3129 | |
|
|
3130 | Example: Register an atexit handler to destroy the default loop, so any |
|
|
3131 | cleanup functions are called. |
|
|
3132 | |
|
|
3133 | static void |
|
|
3134 | program_exits (void) |
|
|
3135 | { |
|
|
3136 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
3137 | } |
|
|
3138 | |
|
|
3139 | ... |
|
|
3140 | atexit (program_exits); |
|
|
3141 | |
|
|
3142 | |
2761 | =head2 C<ev_async> - how to wake up another event loop |
3143 | =head2 C<ev_async> - how to wake up an event loop |
2762 | |
3144 | |
2763 | In general, you cannot use an C<ev_loop> from multiple threads or other |
3145 | In general, you cannot use an C<ev_run> from multiple threads or other |
2764 | asynchronous sources such as signal handlers (as opposed to multiple event |
3146 | asynchronous sources such as signal handlers (as opposed to multiple event |
2765 | loops - those are of course safe to use in different threads). |
3147 | loops - those are of course safe to use in different threads). |
2766 | |
3148 | |
2767 | Sometimes, however, you need to wake up another event loop you do not |
3149 | Sometimes, however, you need to wake up an event loop you do not control, |
2768 | control, for example because it belongs to another thread. This is what |
3150 | for example because it belongs to another thread. This is what C<ev_async> |
2769 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
3151 | watchers do: as long as the C<ev_async> watcher is active, you can signal |
2770 | can signal it by calling C<ev_async_send>, which is thread- and signal |
3152 | it by calling C<ev_async_send>, which is thread- and signal safe. |
2771 | safe. |
|
|
2772 | |
3153 | |
2773 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3154 | This functionality is very similar to C<ev_signal> watchers, as signals, |
2774 | too, are asynchronous in nature, and signals, too, will be compressed |
3155 | too, are asynchronous in nature, and signals, too, will be compressed |
2775 | (i.e. the number of callback invocations may be less than the number of |
3156 | (i.e. the number of callback invocations may be less than the number of |
2776 | C<ev_async_sent> calls). |
3157 | C<ev_async_sent> calls). |
… | |
… | |
2781 | =head3 Queueing |
3162 | =head3 Queueing |
2782 | |
3163 | |
2783 | C<ev_async> does not support queueing of data in any way. The reason |
3164 | C<ev_async> does not support queueing of data in any way. The reason |
2784 | is that the author does not know of a simple (or any) algorithm for a |
3165 | is that the author does not know of a simple (or any) algorithm for a |
2785 | multiple-writer-single-reader queue that works in all cases and doesn't |
3166 | multiple-writer-single-reader queue that works in all cases and doesn't |
2786 | need elaborate support such as pthreads. |
3167 | need elaborate support such as pthreads or unportable memory access |
|
|
3168 | semantics. |
2787 | |
3169 | |
2788 | That means that if you want to queue data, you have to provide your own |
3170 | That means that if you want to queue data, you have to provide your own |
2789 | queue. But at least I can tell you how to implement locking around your |
3171 | queue. But at least I can tell you how to implement locking around your |
2790 | queue: |
3172 | queue: |
2791 | |
3173 | |
… | |
… | |
2930 | |
3312 | |
2931 | If C<timeout> is less than 0, then no timeout watcher will be |
3313 | If C<timeout> is less than 0, then no timeout watcher will be |
2932 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3314 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
2933 | repeat = 0) will be started. C<0> is a valid timeout. |
3315 | repeat = 0) will be started. C<0> is a valid timeout. |
2934 | |
3316 | |
2935 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
3317 | The callback has the type C<void (*cb)(int revents, void *arg)> and is |
2936 | passed an C<revents> set like normal event callbacks (a combination of |
3318 | passed an C<revents> set like normal event callbacks (a combination of |
2937 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
3319 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg> |
2938 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3320 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
2939 | a timeout and an io event at the same time - you probably should give io |
3321 | a timeout and an io event at the same time - you probably should give io |
2940 | events precedence. |
3322 | events precedence. |
2941 | |
3323 | |
2942 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3324 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
2943 | |
3325 | |
2944 | static void stdin_ready (int revents, void *arg) |
3326 | static void stdin_ready (int revents, void *arg) |
2945 | { |
3327 | { |
2946 | if (revents & EV_READ) |
3328 | if (revents & EV_READ) |
2947 | /* stdin might have data for us, joy! */; |
3329 | /* stdin might have data for us, joy! */; |
2948 | else if (revents & EV_TIMEOUT) |
3330 | else if (revents & EV_TIMER) |
2949 | /* doh, nothing entered */; |
3331 | /* doh, nothing entered */; |
2950 | } |
3332 | } |
2951 | |
3333 | |
2952 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3334 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2953 | |
3335 | |
2954 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
|
|
2955 | |
|
|
2956 | Feeds the given event set into the event loop, as if the specified event |
|
|
2957 | had happened for the specified watcher (which must be a pointer to an |
|
|
2958 | initialised but not necessarily started event watcher). |
|
|
2959 | |
|
|
2960 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
3336 | =item ev_feed_fd_event (loop, int fd, int revents) |
2961 | |
3337 | |
2962 | Feed an event on the given fd, as if a file descriptor backend detected |
3338 | Feed an event on the given fd, as if a file descriptor backend detected |
2963 | the given events it. |
3339 | the given events it. |
2964 | |
3340 | |
2965 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
3341 | =item ev_feed_signal_event (loop, int signum) |
2966 | |
3342 | |
2967 | Feed an event as if the given signal occurred (C<loop> must be the default |
3343 | Feed an event as if the given signal occurred (C<loop> must be the default |
2968 | loop!). |
3344 | loop!). |
2969 | |
3345 | |
2970 | =back |
3346 | =back |
… | |
… | |
3050 | |
3426 | |
3051 | =over 4 |
3427 | =over 4 |
3052 | |
3428 | |
3053 | =item ev::TYPE::TYPE () |
3429 | =item ev::TYPE::TYPE () |
3054 | |
3430 | |
3055 | =item ev::TYPE::TYPE (struct ev_loop *) |
3431 | =item ev::TYPE::TYPE (loop) |
3056 | |
3432 | |
3057 | =item ev::TYPE::~TYPE |
3433 | =item ev::TYPE::~TYPE |
3058 | |
3434 | |
3059 | The constructor (optionally) takes an event loop to associate the watcher |
3435 | The constructor (optionally) takes an event loop to associate the watcher |
3060 | with. If it is omitted, it will use C<EV_DEFAULT>. |
3436 | with. If it is omitted, it will use C<EV_DEFAULT>. |
… | |
… | |
3093 | myclass obj; |
3469 | myclass obj; |
3094 | ev::io iow; |
3470 | ev::io iow; |
3095 | iow.set <myclass, &myclass::io_cb> (&obj); |
3471 | iow.set <myclass, &myclass::io_cb> (&obj); |
3096 | |
3472 | |
3097 | =item w->set (object *) |
3473 | =item w->set (object *) |
3098 | |
|
|
3099 | This is an B<experimental> feature that might go away in a future version. |
|
|
3100 | |
3474 | |
3101 | This is a variation of a method callback - leaving out the method to call |
3475 | This is a variation of a method callback - leaving out the method to call |
3102 | will default the method to C<operator ()>, which makes it possible to use |
3476 | will default the method to C<operator ()>, which makes it possible to use |
3103 | functor objects without having to manually specify the C<operator ()> all |
3477 | functor objects without having to manually specify the C<operator ()> all |
3104 | the time. Incidentally, you can then also leave out the template argument |
3478 | the time. Incidentally, you can then also leave out the template argument |
… | |
… | |
3137 | Example: Use a plain function as callback. |
3511 | Example: Use a plain function as callback. |
3138 | |
3512 | |
3139 | static void io_cb (ev::io &w, int revents) { } |
3513 | static void io_cb (ev::io &w, int revents) { } |
3140 | iow.set <io_cb> (); |
3514 | iow.set <io_cb> (); |
3141 | |
3515 | |
3142 | =item w->set (struct ev_loop *) |
3516 | =item w->set (loop) |
3143 | |
3517 | |
3144 | Associates a different C<struct ev_loop> with this watcher. You can only |
3518 | Associates a different C<struct ev_loop> with this watcher. You can only |
3145 | do this when the watcher is inactive (and not pending either). |
3519 | do this when the watcher is inactive (and not pending either). |
3146 | |
3520 | |
3147 | =item w->set ([arguments]) |
3521 | =item w->set ([arguments]) |
3148 | |
3522 | |
3149 | Basically the same as C<ev_TYPE_set>, with the same arguments. Must be |
3523 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
3150 | called at least once. Unlike the C counterpart, an active watcher gets |
3524 | method or a suitable start method must be called at least once. Unlike the |
3151 | automatically stopped and restarted when reconfiguring it with this |
3525 | C counterpart, an active watcher gets automatically stopped and restarted |
3152 | method. |
3526 | when reconfiguring it with this method. |
3153 | |
3527 | |
3154 | =item w->start () |
3528 | =item w->start () |
3155 | |
3529 | |
3156 | Starts the watcher. Note that there is no C<loop> argument, as the |
3530 | Starts the watcher. Note that there is no C<loop> argument, as the |
3157 | constructor already stores the event loop. |
3531 | constructor already stores the event loop. |
3158 | |
3532 | |
|
|
3533 | =item w->start ([arguments]) |
|
|
3534 | |
|
|
3535 | Instead of calling C<set> and C<start> methods separately, it is often |
|
|
3536 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
3537 | the configure C<set> method of the watcher. |
|
|
3538 | |
3159 | =item w->stop () |
3539 | =item w->stop () |
3160 | |
3540 | |
3161 | Stops the watcher if it is active. Again, no C<loop> argument. |
3541 | Stops the watcher if it is active. Again, no C<loop> argument. |
3162 | |
3542 | |
3163 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
3543 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
… | |
… | |
3175 | |
3555 | |
3176 | =back |
3556 | =back |
3177 | |
3557 | |
3178 | =back |
3558 | =back |
3179 | |
3559 | |
3180 | Example: Define a class with an IO and idle watcher, start one of them in |
3560 | Example: Define a class with two I/O and idle watchers, start the I/O |
3181 | the constructor. |
3561 | watchers in the constructor. |
3182 | |
3562 | |
3183 | class myclass |
3563 | class myclass |
3184 | { |
3564 | { |
3185 | ev::io io ; void io_cb (ev::io &w, int revents); |
3565 | ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
3566 | ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
3186 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3567 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3187 | |
3568 | |
3188 | myclass (int fd) |
3569 | myclass (int fd) |
3189 | { |
3570 | { |
3190 | io .set <myclass, &myclass::io_cb > (this); |
3571 | io .set <myclass, &myclass::io_cb > (this); |
|
|
3572 | io2 .set <myclass, &myclass::io2_cb > (this); |
3191 | idle.set <myclass, &myclass::idle_cb> (this); |
3573 | idle.set <myclass, &myclass::idle_cb> (this); |
3192 | |
3574 | |
3193 | io.start (fd, ev::READ); |
3575 | io.set (fd, ev::WRITE); // configure the watcher |
|
|
3576 | io.start (); // start it whenever convenient |
|
|
3577 | |
|
|
3578 | io2.start (fd, ev::READ); // set + start in one call |
3194 | } |
3579 | } |
3195 | }; |
3580 | }; |
3196 | |
3581 | |
3197 | |
3582 | |
3198 | =head1 OTHER LANGUAGE BINDINGS |
3583 | =head1 OTHER LANGUAGE BINDINGS |
… | |
… | |
3244 | =item Ocaml |
3629 | =item Ocaml |
3245 | |
3630 | |
3246 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3631 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3247 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3632 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3248 | |
3633 | |
|
|
3634 | =item Lua |
|
|
3635 | |
|
|
3636 | Brian Maher has written a partial interface to libev for lua (at the |
|
|
3637 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
|
|
3638 | L<http://github.com/brimworks/lua-ev>. |
|
|
3639 | |
3249 | =back |
3640 | =back |
3250 | |
3641 | |
3251 | |
3642 | |
3252 | =head1 MACRO MAGIC |
3643 | =head1 MACRO MAGIC |
3253 | |
3644 | |
… | |
… | |
3266 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3657 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3267 | C<EV_A_> is used when other arguments are following. Example: |
3658 | C<EV_A_> is used when other arguments are following. Example: |
3268 | |
3659 | |
3269 | ev_unref (EV_A); |
3660 | ev_unref (EV_A); |
3270 | ev_timer_add (EV_A_ watcher); |
3661 | ev_timer_add (EV_A_ watcher); |
3271 | ev_loop (EV_A_ 0); |
3662 | ev_run (EV_A_ 0); |
3272 | |
3663 | |
3273 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3664 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3274 | which is often provided by the following macro. |
3665 | which is often provided by the following macro. |
3275 | |
3666 | |
3276 | =item C<EV_P>, C<EV_P_> |
3667 | =item C<EV_P>, C<EV_P_> |
… | |
… | |
3316 | } |
3707 | } |
3317 | |
3708 | |
3318 | ev_check check; |
3709 | ev_check check; |
3319 | ev_check_init (&check, check_cb); |
3710 | ev_check_init (&check, check_cb); |
3320 | ev_check_start (EV_DEFAULT_ &check); |
3711 | ev_check_start (EV_DEFAULT_ &check); |
3321 | ev_loop (EV_DEFAULT_ 0); |
3712 | ev_run (EV_DEFAULT_ 0); |
3322 | |
3713 | |
3323 | =head1 EMBEDDING |
3714 | =head1 EMBEDDING |
3324 | |
3715 | |
3325 | Libev can (and often is) directly embedded into host |
3716 | Libev can (and often is) directly embedded into host |
3326 | applications. Examples of applications that embed it include the Deliantra |
3717 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3406 | libev.m4 |
3797 | libev.m4 |
3407 | |
3798 | |
3408 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3799 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3409 | |
3800 | |
3410 | Libev can be configured via a variety of preprocessor symbols you have to |
3801 | Libev can be configured via a variety of preprocessor symbols you have to |
3411 | define before including any of its files. The default in the absence of |
3802 | define before including (or compiling) any of its files. The default in |
3412 | autoconf is documented for every option. |
3803 | the absence of autoconf is documented for every option. |
|
|
3804 | |
|
|
3805 | Symbols marked with "(h)" do not change the ABI, and can have different |
|
|
3806 | values when compiling libev vs. including F<ev.h>, so it is permissible |
|
|
3807 | to redefine them before including F<ev.h> without breaking compatibility |
|
|
3808 | to a compiled library. All other symbols change the ABI, which means all |
|
|
3809 | users of libev and the libev code itself must be compiled with compatible |
|
|
3810 | settings. |
3413 | |
3811 | |
3414 | =over 4 |
3812 | =over 4 |
3415 | |
3813 | |
|
|
3814 | =item EV_COMPAT3 (h) |
|
|
3815 | |
|
|
3816 | Backwards compatibility is a major concern for libev. This is why this |
|
|
3817 | release of libev comes with wrappers for the functions and symbols that |
|
|
3818 | have been renamed between libev version 3 and 4. |
|
|
3819 | |
|
|
3820 | You can disable these wrappers (to test compatibility with future |
|
|
3821 | versions) by defining C<EV_COMPAT3> to C<0> when compiling your |
|
|
3822 | sources. This has the additional advantage that you can drop the C<struct> |
|
|
3823 | from C<struct ev_loop> declarations, as libev will provide an C<ev_loop> |
|
|
3824 | typedef in that case. |
|
|
3825 | |
|
|
3826 | In some future version, the default for C<EV_COMPAT3> will become C<0>, |
|
|
3827 | and in some even more future version the compatibility code will be |
|
|
3828 | removed completely. |
|
|
3829 | |
3416 | =item EV_STANDALONE |
3830 | =item EV_STANDALONE (h) |
3417 | |
3831 | |
3418 | Must always be C<1> if you do not use autoconf configuration, which |
3832 | Must always be C<1> if you do not use autoconf configuration, which |
3419 | keeps libev from including F<config.h>, and it also defines dummy |
3833 | keeps libev from including F<config.h>, and it also defines dummy |
3420 | implementations for some libevent functions (such as logging, which is not |
3834 | implementations for some libevent functions (such as logging, which is not |
3421 | supported). It will also not define any of the structs usually found in |
3835 | supported). It will also not define any of the structs usually found in |
3422 | F<event.h> that are not directly supported by the libev core alone. |
3836 | F<event.h> that are not directly supported by the libev core alone. |
3423 | |
3837 | |
3424 | In stanbdalone mode, libev will still try to automatically deduce the |
3838 | In standalone mode, libev will still try to automatically deduce the |
3425 | configuration, but has to be more conservative. |
3839 | configuration, but has to be more conservative. |
3426 | |
3840 | |
3427 | =item EV_USE_MONOTONIC |
3841 | =item EV_USE_MONOTONIC |
3428 | |
3842 | |
3429 | If defined to be C<1>, libev will try to detect the availability of the |
3843 | If defined to be C<1>, libev will try to detect the availability of the |
… | |
… | |
3494 | be used is the winsock select). This means that it will call |
3908 | be used is the winsock select). This means that it will call |
3495 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3909 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3496 | it is assumed that all these functions actually work on fds, even |
3910 | it is assumed that all these functions actually work on fds, even |
3497 | on win32. Should not be defined on non-win32 platforms. |
3911 | on win32. Should not be defined on non-win32 platforms. |
3498 | |
3912 | |
3499 | =item EV_FD_TO_WIN32_HANDLE |
3913 | =item EV_FD_TO_WIN32_HANDLE(fd) |
3500 | |
3914 | |
3501 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3915 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3502 | file descriptors to socket handles. When not defining this symbol (the |
3916 | file descriptors to socket handles. When not defining this symbol (the |
3503 | default), then libev will call C<_get_osfhandle>, which is usually |
3917 | default), then libev will call C<_get_osfhandle>, which is usually |
3504 | correct. In some cases, programs use their own file descriptor management, |
3918 | correct. In some cases, programs use their own file descriptor management, |
3505 | in which case they can provide this function to map fds to socket handles. |
3919 | in which case they can provide this function to map fds to socket handles. |
|
|
3920 | |
|
|
3921 | =item EV_WIN32_HANDLE_TO_FD(handle) |
|
|
3922 | |
|
|
3923 | If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors |
|
|
3924 | using the standard C<_open_osfhandle> function. For programs implementing |
|
|
3925 | their own fd to handle mapping, overwriting this function makes it easier |
|
|
3926 | to do so. This can be done by defining this macro to an appropriate value. |
|
|
3927 | |
|
|
3928 | =item EV_WIN32_CLOSE_FD(fd) |
|
|
3929 | |
|
|
3930 | If programs implement their own fd to handle mapping on win32, then this |
|
|
3931 | macro can be used to override the C<close> function, useful to unregister |
|
|
3932 | file descriptors again. Note that the replacement function has to close |
|
|
3933 | the underlying OS handle. |
3506 | |
3934 | |
3507 | =item EV_USE_POLL |
3935 | =item EV_USE_POLL |
3508 | |
3936 | |
3509 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3937 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3510 | backend. Otherwise it will be enabled on non-win32 platforms. It |
3938 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
3557 | as well as for signal and thread safety in C<ev_async> watchers. |
3985 | as well as for signal and thread safety in C<ev_async> watchers. |
3558 | |
3986 | |
3559 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3987 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3560 | (from F<signal.h>), which is usually good enough on most platforms. |
3988 | (from F<signal.h>), which is usually good enough on most platforms. |
3561 | |
3989 | |
3562 | =item EV_H |
3990 | =item EV_H (h) |
3563 | |
3991 | |
3564 | The name of the F<ev.h> header file used to include it. The default if |
3992 | The name of the F<ev.h> header file used to include it. The default if |
3565 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3993 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3566 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3994 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3567 | |
3995 | |
3568 | =item EV_CONFIG_H |
3996 | =item EV_CONFIG_H (h) |
3569 | |
3997 | |
3570 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3998 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3571 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3999 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3572 | C<EV_H>, above. |
4000 | C<EV_H>, above. |
3573 | |
4001 | |
3574 | =item EV_EVENT_H |
4002 | =item EV_EVENT_H (h) |
3575 | |
4003 | |
3576 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
4004 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3577 | of how the F<event.h> header can be found, the default is C<"event.h">. |
4005 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3578 | |
4006 | |
3579 | =item EV_PROTOTYPES |
4007 | =item EV_PROTOTYPES (h) |
3580 | |
4008 | |
3581 | If defined to be C<0>, then F<ev.h> will not define any function |
4009 | If defined to be C<0>, then F<ev.h> will not define any function |
3582 | prototypes, but still define all the structs and other symbols. This is |
4010 | prototypes, but still define all the structs and other symbols. This is |
3583 | occasionally useful if you want to provide your own wrapper functions |
4011 | occasionally useful if you want to provide your own wrapper functions |
3584 | around libev functions. |
4012 | around libev functions. |
… | |
… | |
3606 | fine. |
4034 | fine. |
3607 | |
4035 | |
3608 | If your embedding application does not need any priorities, defining these |
4036 | If your embedding application does not need any priorities, defining these |
3609 | both to C<0> will save some memory and CPU. |
4037 | both to C<0> will save some memory and CPU. |
3610 | |
4038 | |
3611 | =item EV_PERIODIC_ENABLE |
4039 | =item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, |
|
|
4040 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
|
|
4041 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3612 | |
4042 | |
3613 | If undefined or defined to be C<1>, then periodic timers are supported. If |
4043 | If undefined or defined to be C<1> (and the platform supports it), then |
3614 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
4044 | the respective watcher type is supported. If defined to be C<0>, then it |
3615 | code. |
4045 | is not. Disabling watcher types mainly saves code size. |
3616 | |
4046 | |
3617 | =item EV_IDLE_ENABLE |
4047 | =item EV_FEATURES |
3618 | |
|
|
3619 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3620 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3621 | code. |
|
|
3622 | |
|
|
3623 | =item EV_EMBED_ENABLE |
|
|
3624 | |
|
|
3625 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3626 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3627 | watcher types, which therefore must not be disabled. |
|
|
3628 | |
|
|
3629 | =item EV_STAT_ENABLE |
|
|
3630 | |
|
|
3631 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3632 | defined to be C<0>, then they are not. |
|
|
3633 | |
|
|
3634 | =item EV_FORK_ENABLE |
|
|
3635 | |
|
|
3636 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3637 | defined to be C<0>, then they are not. |
|
|
3638 | |
|
|
3639 | =item EV_ASYNC_ENABLE |
|
|
3640 | |
|
|
3641 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3642 | defined to be C<0>, then they are not. |
|
|
3643 | |
|
|
3644 | =item EV_MINIMAL |
|
|
3645 | |
4048 | |
3646 | If you need to shave off some kilobytes of code at the expense of some |
4049 | If you need to shave off some kilobytes of code at the expense of some |
3647 | speed, define this symbol to C<1>. Currently this is used to override some |
4050 | speed (but with the full API), you can define this symbol to request |
3648 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
4051 | certain subsets of functionality. The default is to enable all features |
3649 | much smaller 2-heap for timer management over the default 4-heap. |
4052 | that can be enabled on the platform. |
|
|
4053 | |
|
|
4054 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
|
|
4055 | with some broad features you want) and then selectively re-enable |
|
|
4056 | additional parts you want, for example if you want everything minimal, |
|
|
4057 | but multiple event loop support, async and child watchers and the poll |
|
|
4058 | backend, use this: |
|
|
4059 | |
|
|
4060 | #define EV_FEATURES 0 |
|
|
4061 | #define EV_MULTIPLICITY 1 |
|
|
4062 | #define EV_USE_POLL 1 |
|
|
4063 | #define EV_CHILD_ENABLE 1 |
|
|
4064 | #define EV_ASYNC_ENABLE 1 |
|
|
4065 | |
|
|
4066 | The actual value is a bitset, it can be a combination of the following |
|
|
4067 | values: |
|
|
4068 | |
|
|
4069 | =over 4 |
|
|
4070 | |
|
|
4071 | =item C<1> - faster/larger code |
|
|
4072 | |
|
|
4073 | Use larger code to speed up some operations. |
|
|
4074 | |
|
|
4075 | Currently this is used to override some inlining decisions (enlarging the |
|
|
4076 | code size by roughly 30% on amd64). |
|
|
4077 | |
|
|
4078 | When optimising for size, use of compiler flags such as C<-Os> with |
|
|
4079 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
|
|
4080 | assertions. |
|
|
4081 | |
|
|
4082 | =item C<2> - faster/larger data structures |
|
|
4083 | |
|
|
4084 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
|
|
4085 | hash table sizes and so on. This will usually further increase code size |
|
|
4086 | and can additionally have an effect on the size of data structures at |
|
|
4087 | runtime. |
|
|
4088 | |
|
|
4089 | =item C<4> - full API configuration |
|
|
4090 | |
|
|
4091 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
|
|
4092 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
|
|
4093 | |
|
|
4094 | =item C<8> - full API |
|
|
4095 | |
|
|
4096 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
|
|
4097 | details on which parts of the API are still available without this |
|
|
4098 | feature, and do not complain if this subset changes over time. |
|
|
4099 | |
|
|
4100 | =item C<16> - enable all optional watcher types |
|
|
4101 | |
|
|
4102 | Enables all optional watcher types. If you want to selectively enable |
|
|
4103 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
4104 | embed, async, child...) you can enable them manually by defining |
|
|
4105 | C<EV_watchertype_ENABLE> to C<1> instead. |
|
|
4106 | |
|
|
4107 | =item C<32> - enable all backends |
|
|
4108 | |
|
|
4109 | This enables all backends - without this feature, you need to enable at |
|
|
4110 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
|
|
4111 | |
|
|
4112 | =item C<64> - enable OS-specific "helper" APIs |
|
|
4113 | |
|
|
4114 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
4115 | default. |
|
|
4116 | |
|
|
4117 | =back |
|
|
4118 | |
|
|
4119 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
|
|
4120 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
4121 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
4122 | watchers, timers and monotonic clock support. |
|
|
4123 | |
|
|
4124 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
4125 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
|
|
4126 | your program might be left out as well - a binary starting a timer and an |
|
|
4127 | I/O watcher then might come out at only 5Kb. |
|
|
4128 | |
|
|
4129 | =item EV_AVOID_STDIO |
|
|
4130 | |
|
|
4131 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
|
|
4132 | functions (printf, scanf, perror etc.). This will increase the code size |
|
|
4133 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
4134 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
4135 | big. |
|
|
4136 | |
|
|
4137 | Note that error messages might become less precise when this option is |
|
|
4138 | enabled. |
|
|
4139 | |
|
|
4140 | =item EV_NSIG |
|
|
4141 | |
|
|
4142 | The highest supported signal number, +1 (or, the number of |
|
|
4143 | signals): Normally, libev tries to deduce the maximum number of signals |
|
|
4144 | automatically, but sometimes this fails, in which case it can be |
|
|
4145 | specified. Also, using a lower number than detected (C<32> should be |
|
|
4146 | good for about any system in existence) can save some memory, as libev |
|
|
4147 | statically allocates some 12-24 bytes per signal number. |
3650 | |
4148 | |
3651 | =item EV_PID_HASHSIZE |
4149 | =item EV_PID_HASHSIZE |
3652 | |
4150 | |
3653 | C<ev_child> watchers use a small hash table to distribute workload by |
4151 | C<ev_child> watchers use a small hash table to distribute workload by |
3654 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
4152 | pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled), |
3655 | than enough. If you need to manage thousands of children you might want to |
4153 | usually more than enough. If you need to manage thousands of children you |
3656 | increase this value (I<must> be a power of two). |
4154 | might want to increase this value (I<must> be a power of two). |
3657 | |
4155 | |
3658 | =item EV_INOTIFY_HASHSIZE |
4156 | =item EV_INOTIFY_HASHSIZE |
3659 | |
4157 | |
3660 | C<ev_stat> watchers use a small hash table to distribute workload by |
4158 | C<ev_stat> watchers use a small hash table to distribute workload by |
3661 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
4159 | inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES> |
3662 | usually more than enough. If you need to manage thousands of C<ev_stat> |
4160 | disabled), usually more than enough. If you need to manage thousands of |
3663 | watchers you might want to increase this value (I<must> be a power of |
4161 | C<ev_stat> watchers you might want to increase this value (I<must> be a |
3664 | two). |
4162 | power of two). |
3665 | |
4163 | |
3666 | =item EV_USE_4HEAP |
4164 | =item EV_USE_4HEAP |
3667 | |
4165 | |
3668 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4166 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3669 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
4167 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3670 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
4168 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3671 | faster performance with many (thousands) of watchers. |
4169 | faster performance with many (thousands) of watchers. |
3672 | |
4170 | |
3673 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4171 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3674 | (disabled). |
4172 | will be C<0>. |
3675 | |
4173 | |
3676 | =item EV_HEAP_CACHE_AT |
4174 | =item EV_HEAP_CACHE_AT |
3677 | |
4175 | |
3678 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4176 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3679 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
4177 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3680 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
4178 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3681 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
4179 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3682 | but avoids random read accesses on heap changes. This improves performance |
4180 | but avoids random read accesses on heap changes. This improves performance |
3683 | noticeably with many (hundreds) of watchers. |
4181 | noticeably with many (hundreds) of watchers. |
3684 | |
4182 | |
3685 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4183 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3686 | (disabled). |
4184 | will be C<0>. |
3687 | |
4185 | |
3688 | =item EV_VERIFY |
4186 | =item EV_VERIFY |
3689 | |
4187 | |
3690 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4188 | Controls how much internal verification (see C<ev_verify ()>) will |
3691 | be done: If set to C<0>, no internal verification code will be compiled |
4189 | be done: If set to C<0>, no internal verification code will be compiled |
3692 | in. If set to C<1>, then verification code will be compiled in, but not |
4190 | in. If set to C<1>, then verification code will be compiled in, but not |
3693 | called. If set to C<2>, then the internal verification code will be |
4191 | called. If set to C<2>, then the internal verification code will be |
3694 | called once per loop, which can slow down libev. If set to C<3>, then the |
4192 | called once per loop, which can slow down libev. If set to C<3>, then the |
3695 | verification code will be called very frequently, which will slow down |
4193 | verification code will be called very frequently, which will slow down |
3696 | libev considerably. |
4194 | libev considerably. |
3697 | |
4195 | |
3698 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
4196 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3699 | C<0>. |
4197 | will be C<0>. |
3700 | |
4198 | |
3701 | =item EV_COMMON |
4199 | =item EV_COMMON |
3702 | |
4200 | |
3703 | By default, all watchers have a C<void *data> member. By redefining |
4201 | By default, all watchers have a C<void *data> member. By redefining |
3704 | this macro to a something else you can include more and other types of |
4202 | this macro to something else you can include more and other types of |
3705 | members. You have to define it each time you include one of the files, |
4203 | members. You have to define it each time you include one of the files, |
3706 | though, and it must be identical each time. |
4204 | though, and it must be identical each time. |
3707 | |
4205 | |
3708 | For example, the perl EV module uses something like this: |
4206 | For example, the perl EV module uses something like this: |
3709 | |
4207 | |
… | |
… | |
3762 | file. |
4260 | file. |
3763 | |
4261 | |
3764 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4262 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
3765 | that everybody includes and which overrides some configure choices: |
4263 | that everybody includes and which overrides some configure choices: |
3766 | |
4264 | |
3767 | #define EV_MINIMAL 1 |
4265 | #define EV_FEATURES 8 |
3768 | #define EV_USE_POLL 0 |
4266 | #define EV_USE_SELECT 1 |
3769 | #define EV_MULTIPLICITY 0 |
|
|
3770 | #define EV_PERIODIC_ENABLE 0 |
4267 | #define EV_PREPARE_ENABLE 1 |
|
|
4268 | #define EV_IDLE_ENABLE 1 |
3771 | #define EV_STAT_ENABLE 0 |
4269 | #define EV_SIGNAL_ENABLE 1 |
3772 | #define EV_FORK_ENABLE 0 |
4270 | #define EV_CHILD_ENABLE 1 |
|
|
4271 | #define EV_USE_STDEXCEPT 0 |
3773 | #define EV_CONFIG_H <config.h> |
4272 | #define EV_CONFIG_H <config.h> |
3774 | #define EV_MINPRI 0 |
|
|
3775 | #define EV_MAXPRI 0 |
|
|
3776 | |
4273 | |
3777 | #include "ev++.h" |
4274 | #include "ev++.h" |
3778 | |
4275 | |
3779 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4276 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
3780 | |
4277 | |
… | |
… | |
3840 | default loop and triggering an C<ev_async> watcher from the default loop |
4337 | default loop and triggering an C<ev_async> watcher from the default loop |
3841 | watcher callback into the event loop interested in the signal. |
4338 | watcher callback into the event loop interested in the signal. |
3842 | |
4339 | |
3843 | =back |
4340 | =back |
3844 | |
4341 | |
|
|
4342 | =head4 THREAD LOCKING EXAMPLE |
|
|
4343 | |
|
|
4344 | Here is a fictitious example of how to run an event loop in a different |
|
|
4345 | thread than where callbacks are being invoked and watchers are |
|
|
4346 | created/added/removed. |
|
|
4347 | |
|
|
4348 | For a real-world example, see the C<EV::Loop::Async> perl module, |
|
|
4349 | which uses exactly this technique (which is suited for many high-level |
|
|
4350 | languages). |
|
|
4351 | |
|
|
4352 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
4353 | variable to wait for callback invocations, an async watcher to notify the |
|
|
4354 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
4355 | |
|
|
4356 | First, you need to associate some data with the event loop: |
|
|
4357 | |
|
|
4358 | typedef struct { |
|
|
4359 | mutex_t lock; /* global loop lock */ |
|
|
4360 | ev_async async_w; |
|
|
4361 | thread_t tid; |
|
|
4362 | cond_t invoke_cv; |
|
|
4363 | } userdata; |
|
|
4364 | |
|
|
4365 | void prepare_loop (EV_P) |
|
|
4366 | { |
|
|
4367 | // for simplicity, we use a static userdata struct. |
|
|
4368 | static userdata u; |
|
|
4369 | |
|
|
4370 | ev_async_init (&u->async_w, async_cb); |
|
|
4371 | ev_async_start (EV_A_ &u->async_w); |
|
|
4372 | |
|
|
4373 | pthread_mutex_init (&u->lock, 0); |
|
|
4374 | pthread_cond_init (&u->invoke_cv, 0); |
|
|
4375 | |
|
|
4376 | // now associate this with the loop |
|
|
4377 | ev_set_userdata (EV_A_ u); |
|
|
4378 | ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
4379 | ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
4380 | |
|
|
4381 | // then create the thread running ev_loop |
|
|
4382 | pthread_create (&u->tid, 0, l_run, EV_A); |
|
|
4383 | } |
|
|
4384 | |
|
|
4385 | The callback for the C<ev_async> watcher does nothing: the watcher is used |
|
|
4386 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
4387 | that might have been added: |
|
|
4388 | |
|
|
4389 | static void |
|
|
4390 | async_cb (EV_P_ ev_async *w, int revents) |
|
|
4391 | { |
|
|
4392 | // just used for the side effects |
|
|
4393 | } |
|
|
4394 | |
|
|
4395 | The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex |
|
|
4396 | protecting the loop data, respectively. |
|
|
4397 | |
|
|
4398 | static void |
|
|
4399 | l_release (EV_P) |
|
|
4400 | { |
|
|
4401 | userdata *u = ev_userdata (EV_A); |
|
|
4402 | pthread_mutex_unlock (&u->lock); |
|
|
4403 | } |
|
|
4404 | |
|
|
4405 | static void |
|
|
4406 | l_acquire (EV_P) |
|
|
4407 | { |
|
|
4408 | userdata *u = ev_userdata (EV_A); |
|
|
4409 | pthread_mutex_lock (&u->lock); |
|
|
4410 | } |
|
|
4411 | |
|
|
4412 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4413 | into C<ev_run>: |
|
|
4414 | |
|
|
4415 | void * |
|
|
4416 | l_run (void *thr_arg) |
|
|
4417 | { |
|
|
4418 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4419 | |
|
|
4420 | l_acquire (EV_A); |
|
|
4421 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4422 | ev_run (EV_A_ 0); |
|
|
4423 | l_release (EV_A); |
|
|
4424 | |
|
|
4425 | return 0; |
|
|
4426 | } |
|
|
4427 | |
|
|
4428 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
|
|
4429 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4430 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
|
|
4431 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4432 | and b) skipping inter-thread-communication when there are no pending |
|
|
4433 | watchers is very beneficial): |
|
|
4434 | |
|
|
4435 | static void |
|
|
4436 | l_invoke (EV_P) |
|
|
4437 | { |
|
|
4438 | userdata *u = ev_userdata (EV_A); |
|
|
4439 | |
|
|
4440 | while (ev_pending_count (EV_A)) |
|
|
4441 | { |
|
|
4442 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4443 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
|
|
4444 | } |
|
|
4445 | } |
|
|
4446 | |
|
|
4447 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4448 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
|
|
4449 | thread to continue: |
|
|
4450 | |
|
|
4451 | static void |
|
|
4452 | real_invoke_pending (EV_P) |
|
|
4453 | { |
|
|
4454 | userdata *u = ev_userdata (EV_A); |
|
|
4455 | |
|
|
4456 | pthread_mutex_lock (&u->lock); |
|
|
4457 | ev_invoke_pending (EV_A); |
|
|
4458 | pthread_cond_signal (&u->invoke_cv); |
|
|
4459 | pthread_mutex_unlock (&u->lock); |
|
|
4460 | } |
|
|
4461 | |
|
|
4462 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4463 | event loop, you will now have to lock: |
|
|
4464 | |
|
|
4465 | ev_timer timeout_watcher; |
|
|
4466 | userdata *u = ev_userdata (EV_A); |
|
|
4467 | |
|
|
4468 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4469 | |
|
|
4470 | pthread_mutex_lock (&u->lock); |
|
|
4471 | ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4472 | ev_async_send (EV_A_ &u->async_w); |
|
|
4473 | pthread_mutex_unlock (&u->lock); |
|
|
4474 | |
|
|
4475 | Note that sending the C<ev_async> watcher is required because otherwise |
|
|
4476 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4477 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4478 | watchers in the next event loop iteration. |
|
|
4479 | |
3845 | =head3 COROUTINES |
4480 | =head3 COROUTINES |
3846 | |
4481 | |
3847 | Libev is very accommodating to coroutines ("cooperative threads"): |
4482 | Libev is very accommodating to coroutines ("cooperative threads"): |
3848 | libev fully supports nesting calls to its functions from different |
4483 | libev fully supports nesting calls to its functions from different |
3849 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4484 | coroutines (e.g. you can call C<ev_run> on the same loop from two |
3850 | different coroutines, and switch freely between both coroutines running the |
4485 | different coroutines, and switch freely between both coroutines running |
3851 | loop, as long as you don't confuse yourself). The only exception is that |
4486 | the loop, as long as you don't confuse yourself). The only exception is |
3852 | you must not do this from C<ev_periodic> reschedule callbacks. |
4487 | that you must not do this from C<ev_periodic> reschedule callbacks. |
3853 | |
4488 | |
3854 | Care has been taken to ensure that libev does not keep local state inside |
4489 | Care has been taken to ensure that libev does not keep local state inside |
3855 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4490 | C<ev_run>, and other calls do not usually allow for coroutine switches as |
3856 | they do not call any callbacks. |
4491 | they do not call any callbacks. |
3857 | |
4492 | |
3858 | =head2 COMPILER WARNINGS |
4493 | =head2 COMPILER WARNINGS |
3859 | |
4494 | |
3860 | Depending on your compiler and compiler settings, you might get no or a |
4495 | Depending on your compiler and compiler settings, you might get no or a |
… | |
… | |
3871 | maintainable. |
4506 | maintainable. |
3872 | |
4507 | |
3873 | And of course, some compiler warnings are just plain stupid, or simply |
4508 | And of course, some compiler warnings are just plain stupid, or simply |
3874 | wrong (because they don't actually warn about the condition their message |
4509 | wrong (because they don't actually warn about the condition their message |
3875 | seems to warn about). For example, certain older gcc versions had some |
4510 | seems to warn about). For example, certain older gcc versions had some |
3876 | warnings that resulted an extreme number of false positives. These have |
4511 | warnings that resulted in an extreme number of false positives. These have |
3877 | been fixed, but some people still insist on making code warn-free with |
4512 | been fixed, but some people still insist on making code warn-free with |
3878 | such buggy versions. |
4513 | such buggy versions. |
3879 | |
4514 | |
3880 | While libev is written to generate as few warnings as possible, |
4515 | While libev is written to generate as few warnings as possible, |
3881 | "warn-free" code is not a goal, and it is recommended not to build libev |
4516 | "warn-free" code is not a goal, and it is recommended not to build libev |
… | |
… | |
3917 | I suggest using suppression lists. |
4552 | I suggest using suppression lists. |
3918 | |
4553 | |
3919 | |
4554 | |
3920 | =head1 PORTABILITY NOTES |
4555 | =head1 PORTABILITY NOTES |
3921 | |
4556 | |
|
|
4557 | =head2 GNU/LINUX 32 BIT LIMITATIONS |
|
|
4558 | |
|
|
4559 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
4560 | interfaces but I<disables> them by default. |
|
|
4561 | |
|
|
4562 | That means that libev compiled in the default environment doesn't support |
|
|
4563 | files larger than 2GiB or so, which mainly affects C<ev_stat> watchers. |
|
|
4564 | |
|
|
4565 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
4566 | by enabling the large file API, which makes them incompatible with the |
|
|
4567 | standard libev compiled for their system. |
|
|
4568 | |
|
|
4569 | Likewise, libev cannot enable the large file API itself as this would |
|
|
4570 | suddenly make it incompatible to the default compile time environment, |
|
|
4571 | i.e. all programs not using special compile switches. |
|
|
4572 | |
|
|
4573 | =head2 OS/X AND DARWIN BUGS |
|
|
4574 | |
|
|
4575 | The whole thing is a bug if you ask me - basically any system interface |
|
|
4576 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
4577 | OpenGL drivers. |
|
|
4578 | |
|
|
4579 | =head3 C<kqueue> is buggy |
|
|
4580 | |
|
|
4581 | The kqueue syscall is broken in all known versions - most versions support |
|
|
4582 | only sockets, many support pipes. |
|
|
4583 | |
|
|
4584 | Libev tries to work around this by not using C<kqueue> by default on this |
|
|
4585 | rotten platform, but of course you can still ask for it when creating a |
|
|
4586 | loop - embedding a socket-only kqueue loop into a select-based one is |
|
|
4587 | probably going to work well. |
|
|
4588 | |
|
|
4589 | =head3 C<poll> is buggy |
|
|
4590 | |
|
|
4591 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
|
|
4592 | implementation by something calling C<kqueue> internally around the 10.5.6 |
|
|
4593 | release, so now C<kqueue> I<and> C<poll> are broken. |
|
|
4594 | |
|
|
4595 | Libev tries to work around this by not using C<poll> by default on |
|
|
4596 | this rotten platform, but of course you can still ask for it when creating |
|
|
4597 | a loop. |
|
|
4598 | |
|
|
4599 | =head3 C<select> is buggy |
|
|
4600 | |
|
|
4601 | All that's left is C<select>, and of course Apple found a way to fuck this |
|
|
4602 | one up as well: On OS/X, C<select> actively limits the number of file |
|
|
4603 | descriptors you can pass in to 1024 - your program suddenly crashes when |
|
|
4604 | you use more. |
|
|
4605 | |
|
|
4606 | There is an undocumented "workaround" for this - defining |
|
|
4607 | C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should> |
|
|
4608 | work on OS/X. |
|
|
4609 | |
|
|
4610 | =head2 SOLARIS PROBLEMS AND WORKAROUNDS |
|
|
4611 | |
|
|
4612 | =head3 C<errno> reentrancy |
|
|
4613 | |
|
|
4614 | The default compile environment on Solaris is unfortunately so |
|
|
4615 | thread-unsafe that you can't even use components/libraries compiled |
|
|
4616 | without C<-D_REENTRANT> in a threaded program, which, of course, isn't |
|
|
4617 | defined by default. A valid, if stupid, implementation choice. |
|
|
4618 | |
|
|
4619 | If you want to use libev in threaded environments you have to make sure |
|
|
4620 | it's compiled with C<_REENTRANT> defined. |
|
|
4621 | |
|
|
4622 | =head3 Event port backend |
|
|
4623 | |
|
|
4624 | The scalable event interface for Solaris is called "event |
|
|
4625 | ports". Unfortunately, this mechanism is very buggy in all major |
|
|
4626 | releases. If you run into high CPU usage, your program freezes or you get |
|
|
4627 | a large number of spurious wakeups, make sure you have all the relevant |
|
|
4628 | and latest kernel patches applied. No, I don't know which ones, but there |
|
|
4629 | are multiple ones to apply, and afterwards, event ports actually work |
|
|
4630 | great. |
|
|
4631 | |
|
|
4632 | If you can't get it to work, you can try running the program by setting |
|
|
4633 | the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and |
|
|
4634 | C<select> backends. |
|
|
4635 | |
|
|
4636 | =head2 AIX POLL BUG |
|
|
4637 | |
|
|
4638 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
|
|
4639 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
4640 | compiled in), which normally isn't a big problem as C<select> works fine |
|
|
4641 | with large bitsets on AIX, and AIX is dead anyway. |
|
|
4642 | |
3922 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4643 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
|
|
4644 | |
|
|
4645 | =head3 General issues |
3923 | |
4646 | |
3924 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4647 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
3925 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4648 | requires, and its I/O model is fundamentally incompatible with the POSIX |
3926 | model. Libev still offers limited functionality on this platform in |
4649 | model. Libev still offers limited functionality on this platform in |
3927 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4650 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
3928 | descriptors. This only applies when using Win32 natively, not when using |
4651 | descriptors. This only applies when using Win32 natively, not when using |
3929 | e.g. cygwin. |
4652 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
4653 | as every compielr comes with a slightly differently broken/incompatible |
|
|
4654 | environment. |
3930 | |
4655 | |
3931 | Lifting these limitations would basically require the full |
4656 | Lifting these limitations would basically require the full |
3932 | re-implementation of the I/O system. If you are into these kinds of |
4657 | re-implementation of the I/O system. If you are into this kind of thing, |
3933 | things, then note that glib does exactly that for you in a very portable |
4658 | then note that glib does exactly that for you in a very portable way (note |
3934 | way (note also that glib is the slowest event library known to man). |
4659 | also that glib is the slowest event library known to man). |
3935 | |
4660 | |
3936 | There is no supported compilation method available on windows except |
4661 | There is no supported compilation method available on windows except |
3937 | embedding it into other applications. |
4662 | embedding it into other applications. |
|
|
4663 | |
|
|
4664 | Sensible signal handling is officially unsupported by Microsoft - libev |
|
|
4665 | tries its best, but under most conditions, signals will simply not work. |
3938 | |
4666 | |
3939 | Not a libev limitation but worth mentioning: windows apparently doesn't |
4667 | Not a libev limitation but worth mentioning: windows apparently doesn't |
3940 | accept large writes: instead of resulting in a partial write, windows will |
4668 | accept large writes: instead of resulting in a partial write, windows will |
3941 | either accept everything or return C<ENOBUFS> if the buffer is too large, |
4669 | either accept everything or return C<ENOBUFS> if the buffer is too large, |
3942 | so make sure you only write small amounts into your sockets (less than a |
4670 | so make sure you only write small amounts into your sockets (less than a |
… | |
… | |
3947 | the abysmal performance of winsockets, using a large number of sockets |
4675 | the abysmal performance of winsockets, using a large number of sockets |
3948 | is not recommended (and not reasonable). If your program needs to use |
4676 | is not recommended (and not reasonable). If your program needs to use |
3949 | more than a hundred or so sockets, then likely it needs to use a totally |
4677 | more than a hundred or so sockets, then likely it needs to use a totally |
3950 | different implementation for windows, as libev offers the POSIX readiness |
4678 | different implementation for windows, as libev offers the POSIX readiness |
3951 | notification model, which cannot be implemented efficiently on windows |
4679 | notification model, which cannot be implemented efficiently on windows |
3952 | (Microsoft monopoly games). |
4680 | (due to Microsoft monopoly games). |
3953 | |
4681 | |
3954 | A typical way to use libev under windows is to embed it (see the embedding |
4682 | A typical way to use libev under windows is to embed it (see the embedding |
3955 | section for details) and use the following F<evwrap.h> header file instead |
4683 | section for details) and use the following F<evwrap.h> header file instead |
3956 | of F<ev.h>: |
4684 | of F<ev.h>: |
3957 | |
4685 | |
… | |
… | |
3964 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4692 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
3965 | |
4693 | |
3966 | #include "evwrap.h" |
4694 | #include "evwrap.h" |
3967 | #include "ev.c" |
4695 | #include "ev.c" |
3968 | |
4696 | |
3969 | =over 4 |
|
|
3970 | |
|
|
3971 | =item The winsocket select function |
4697 | =head3 The winsocket C<select> function |
3972 | |
4698 | |
3973 | The winsocket C<select> function doesn't follow POSIX in that it |
4699 | The winsocket C<select> function doesn't follow POSIX in that it |
3974 | requires socket I<handles> and not socket I<file descriptors> (it is |
4700 | requires socket I<handles> and not socket I<file descriptors> (it is |
3975 | also extremely buggy). This makes select very inefficient, and also |
4701 | also extremely buggy). This makes select very inefficient, and also |
3976 | requires a mapping from file descriptors to socket handles (the Microsoft |
4702 | requires a mapping from file descriptors to socket handles (the Microsoft |
… | |
… | |
3985 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4711 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
3986 | |
4712 | |
3987 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4713 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
3988 | complexity in the O(n²) range when using win32. |
4714 | complexity in the O(n²) range when using win32. |
3989 | |
4715 | |
3990 | =item Limited number of file descriptors |
4716 | =head3 Limited number of file descriptors |
3991 | |
4717 | |
3992 | Windows has numerous arbitrary (and low) limits on things. |
4718 | Windows has numerous arbitrary (and low) limits on things. |
3993 | |
4719 | |
3994 | Early versions of winsocket's select only supported waiting for a maximum |
4720 | Early versions of winsocket's select only supported waiting for a maximum |
3995 | of C<64> handles (probably owning to the fact that all windows kernels |
4721 | of C<64> handles (probably owning to the fact that all windows kernels |
3996 | can only wait for C<64> things at the same time internally; Microsoft |
4722 | can only wait for C<64> things at the same time internally; Microsoft |
3997 | recommends spawning a chain of threads and wait for 63 handles and the |
4723 | recommends spawning a chain of threads and wait for 63 handles and the |
3998 | previous thread in each. Great). |
4724 | previous thread in each. Sounds great!). |
3999 | |
4725 | |
4000 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
4726 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
4001 | to some high number (e.g. C<2048>) before compiling the winsocket select |
4727 | to some high number (e.g. C<2048>) before compiling the winsocket select |
4002 | call (which might be in libev or elsewhere, for example, perl does its own |
4728 | call (which might be in libev or elsewhere, for example, perl and many |
4003 | select emulation on windows). |
4729 | other interpreters do their own select emulation on windows). |
4004 | |
4730 | |
4005 | Another limit is the number of file descriptors in the Microsoft runtime |
4731 | Another limit is the number of file descriptors in the Microsoft runtime |
4006 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
4732 | libraries, which by default is C<64> (there must be a hidden I<64> |
4007 | or something like this inside Microsoft). You can increase this by calling |
4733 | fetish or something like this inside Microsoft). You can increase this |
4008 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
4734 | by calling C<_setmaxstdio>, which can increase this limit to C<2048> |
4009 | arbitrary limit), but is broken in many versions of the Microsoft runtime |
4735 | (another arbitrary limit), but is broken in many versions of the Microsoft |
4010 | libraries. |
|
|
4011 | |
|
|
4012 | This might get you to about C<512> or C<2048> sockets (depending on |
4736 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4013 | windows version and/or the phase of the moon). To get more, you need to |
4737 | (depending on windows version and/or the phase of the moon). To get more, |
4014 | wrap all I/O functions and provide your own fd management, but the cost of |
4738 | you need to wrap all I/O functions and provide your own fd management, but |
4015 | calling select (O(n²)) will likely make this unworkable. |
4739 | the cost of calling select (O(n²)) will likely make this unworkable. |
4016 | |
|
|
4017 | =back |
|
|
4018 | |
4740 | |
4019 | =head2 PORTABILITY REQUIREMENTS |
4741 | =head2 PORTABILITY REQUIREMENTS |
4020 | |
4742 | |
4021 | In addition to a working ISO-C implementation and of course the |
4743 | In addition to a working ISO-C implementation and of course the |
4022 | backend-specific APIs, libev relies on a few additional extensions: |
4744 | backend-specific APIs, libev relies on a few additional extensions: |
… | |
… | |
4061 | watchers. |
4783 | watchers. |
4062 | |
4784 | |
4063 | =item C<double> must hold a time value in seconds with enough accuracy |
4785 | =item C<double> must hold a time value in seconds with enough accuracy |
4064 | |
4786 | |
4065 | The type C<double> is used to represent timestamps. It is required to |
4787 | The type C<double> is used to represent timestamps. It is required to |
4066 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4788 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
4067 | enough for at least into the year 4000. This requirement is fulfilled by |
4789 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
4790 | (the design goal for libev). This requirement is overfulfilled by |
4068 | implementations implementing IEEE 754 (basically all existing ones). |
4791 | implementations using IEEE 754, which is basically all existing ones. With |
|
|
4792 | IEEE 754 doubles, you get microsecond accuracy until at least 2200. |
4069 | |
4793 | |
4070 | =back |
4794 | =back |
4071 | |
4795 | |
4072 | If you know of other additional requirements drop me a note. |
4796 | If you know of other additional requirements drop me a note. |
4073 | |
4797 | |
… | |
… | |
4141 | involves iterating over all running async watchers or all signal numbers. |
4865 | involves iterating over all running async watchers or all signal numbers. |
4142 | |
4866 | |
4143 | =back |
4867 | =back |
4144 | |
4868 | |
4145 | |
4869 | |
|
|
4870 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
|
|
4871 | |
|
|
4872 | The major version 4 introduced some minor incompatible changes to the API. |
|
|
4873 | |
|
|
4874 | At the moment, the C<ev.h> header file tries to implement superficial |
|
|
4875 | compatibility, so most programs should still compile. Those might be |
|
|
4876 | removed in later versions of libev, so better update early than late. |
|
|
4877 | |
|
|
4878 | =over 4 |
|
|
4879 | |
|
|
4880 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
|
|
4881 | |
|
|
4882 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
|
|
4883 | |
|
|
4884 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
4885 | ev_loop_fork (EV_DEFAULT); |
|
|
4886 | |
|
|
4887 | =item function/symbol renames |
|
|
4888 | |
|
|
4889 | A number of functions and symbols have been renamed: |
|
|
4890 | |
|
|
4891 | ev_loop => ev_run |
|
|
4892 | EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
4893 | EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
4894 | |
|
|
4895 | ev_unloop => ev_break |
|
|
4896 | EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
4897 | EVUNLOOP_ONE => EVBREAK_ONE |
|
|
4898 | EVUNLOOP_ALL => EVBREAK_ALL |
|
|
4899 | |
|
|
4900 | EV_TIMEOUT => EV_TIMER |
|
|
4901 | |
|
|
4902 | ev_loop_count => ev_iteration |
|
|
4903 | ev_loop_depth => ev_depth |
|
|
4904 | ev_loop_verify => ev_verify |
|
|
4905 | |
|
|
4906 | Most functions working on C<struct ev_loop> objects don't have an |
|
|
4907 | C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and |
|
|
4908 | associated constants have been renamed to not collide with the C<struct |
|
|
4909 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
|
|
4910 | as all other watcher types. Note that C<ev_loop_fork> is still called |
|
|
4911 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
|
|
4912 | typedef. |
|
|
4913 | |
|
|
4914 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
4915 | |
|
|
4916 | The backward compatibility mechanism can be controlled by |
|
|
4917 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
4918 | section. |
|
|
4919 | |
|
|
4920 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
4921 | |
|
|
4922 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
4923 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
4924 | and work, but the library code will of course be larger. |
|
|
4925 | |
|
|
4926 | =back |
|
|
4927 | |
|
|
4928 | |
4146 | =head1 GLOSSARY |
4929 | =head1 GLOSSARY |
4147 | |
4930 | |
4148 | =over 4 |
4931 | =over 4 |
4149 | |
4932 | |
4150 | =item active |
4933 | =item active |
4151 | |
4934 | |
4152 | A watcher is active as long as it has been started (has been attached to |
4935 | A watcher is active as long as it has been started and not yet stopped. |
4153 | an event loop) but not yet stopped (disassociated from the event loop). |
4936 | See L<WATCHER STATES> for details. |
4154 | |
4937 | |
4155 | =item application |
4938 | =item application |
4156 | |
4939 | |
4157 | In this document, an application is whatever is using libev. |
4940 | In this document, an application is whatever is using libev. |
|
|
4941 | |
|
|
4942 | =item backend |
|
|
4943 | |
|
|
4944 | The part of the code dealing with the operating system interfaces. |
4158 | |
4945 | |
4159 | =item callback |
4946 | =item callback |
4160 | |
4947 | |
4161 | The address of a function that is called when some event has been |
4948 | The address of a function that is called when some event has been |
4162 | detected. Callbacks are being passed the event loop, the watcher that |
4949 | detected. Callbacks are being passed the event loop, the watcher that |
4163 | received the event, and the actual event bitset. |
4950 | received the event, and the actual event bitset. |
4164 | |
4951 | |
4165 | =item callback invocation |
4952 | =item callback/watcher invocation |
4166 | |
4953 | |
4167 | The act of calling the callback associated with a watcher. |
4954 | The act of calling the callback associated with a watcher. |
4168 | |
4955 | |
4169 | =item event |
4956 | =item event |
4170 | |
4957 | |
4171 | A change of state of some external event, such as data now being available |
4958 | A change of state of some external event, such as data now being available |
4172 | for reading on a file descriptor, time having passed or simply not having |
4959 | for reading on a file descriptor, time having passed or simply not having |
4173 | any other events happening anymore. |
4960 | any other events happening anymore. |
4174 | |
4961 | |
4175 | In libev, events are represented as single bits (such as C<EV_READ> or |
4962 | In libev, events are represented as single bits (such as C<EV_READ> or |
4176 | C<EV_TIMEOUT>). |
4963 | C<EV_TIMER>). |
4177 | |
4964 | |
4178 | =item event library |
4965 | =item event library |
4179 | |
4966 | |
4180 | A software package implementing an event model and loop. |
4967 | A software package implementing an event model and loop. |
4181 | |
4968 | |
… | |
… | |
4189 | The model used to describe how an event loop handles and processes |
4976 | The model used to describe how an event loop handles and processes |
4190 | watchers and events. |
4977 | watchers and events. |
4191 | |
4978 | |
4192 | =item pending |
4979 | =item pending |
4193 | |
4980 | |
4194 | A watcher is pending as soon as the corresponding event has been detected, |
4981 | A watcher is pending as soon as the corresponding event has been |
4195 | and stops being pending as soon as the watcher will be invoked or its |
4982 | detected. See L<WATCHER STATES> for details. |
4196 | pending status is explicitly cleared by the application. |
|
|
4197 | |
|
|
4198 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4199 | its pending status. |
|
|
4200 | |
4983 | |
4201 | =item real time |
4984 | =item real time |
4202 | |
4985 | |
4203 | The physical time that is observed. It is apparently strictly monotonic :) |
4986 | The physical time that is observed. It is apparently strictly monotonic :) |
4204 | |
4987 | |
… | |
… | |
4211 | =item watcher |
4994 | =item watcher |
4212 | |
4995 | |
4213 | A data structure that describes interest in certain events. Watchers need |
4996 | A data structure that describes interest in certain events. Watchers need |
4214 | to be started (attached to an event loop) before they can receive events. |
4997 | to be started (attached to an event loop) before they can receive events. |
4215 | |
4998 | |
4216 | =item watcher invocation |
|
|
4217 | |
|
|
4218 | The act of calling the callback associated with a watcher. |
|
|
4219 | |
|
|
4220 | =back |
4999 | =back |
4221 | |
5000 | |
4222 | =head1 AUTHOR |
5001 | =head1 AUTHOR |
4223 | |
5002 | |
4224 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
5003 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |