… | |
… | |
8 | |
8 | |
9 | =head2 EXAMPLE PROGRAM |
9 | =head2 EXAMPLE PROGRAM |
10 | |
10 | |
11 | // a single header file is required |
11 | // a single header file is required |
12 | #include <ev.h> |
12 | #include <ev.h> |
|
|
13 | |
|
|
14 | #include <stdio.h> // for puts |
13 | |
15 | |
14 | // every watcher type has its own typedef'd struct |
16 | // every watcher type has its own typedef'd struct |
15 | // with the name ev_TYPE |
17 | // with the name ev_TYPE |
16 | ev_io stdin_watcher; |
18 | ev_io stdin_watcher; |
17 | ev_timer timeout_watcher; |
19 | ev_timer timeout_watcher; |
… | |
… | |
24 | puts ("stdin ready"); |
26 | puts ("stdin ready"); |
25 | // for one-shot events, one must manually stop the watcher |
27 | // for one-shot events, one must manually stop the watcher |
26 | // with its corresponding stop function. |
28 | // with its corresponding stop function. |
27 | ev_io_stop (EV_A_ w); |
29 | ev_io_stop (EV_A_ w); |
28 | |
30 | |
29 | // this causes all nested ev_loop's to stop iterating |
31 | // this causes all nested ev_run's to stop iterating |
30 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
32 | ev_break (EV_A_ EVBREAK_ALL); |
31 | } |
33 | } |
32 | |
34 | |
33 | // another callback, this time for a time-out |
35 | // another callback, this time for a time-out |
34 | static void |
36 | static void |
35 | timeout_cb (EV_P_ ev_timer *w, int revents) |
37 | timeout_cb (EV_P_ ev_timer *w, int revents) |
36 | { |
38 | { |
37 | puts ("timeout"); |
39 | puts ("timeout"); |
38 | // this causes the innermost ev_loop to stop iterating |
40 | // this causes the innermost ev_run to stop iterating |
39 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
41 | ev_break (EV_A_ EVBREAK_ONE); |
40 | } |
42 | } |
41 | |
43 | |
42 | int |
44 | int |
43 | main (void) |
45 | main (void) |
44 | { |
46 | { |
45 | // use the default event loop unless you have special needs |
47 | // use the default event loop unless you have special needs |
46 | ev_loop *loop = ev_default_loop (0); |
48 | struct ev_loop *loop = EV_DEFAULT; |
47 | |
49 | |
48 | // initialise an io watcher, then start it |
50 | // initialise an io watcher, then start it |
49 | // this one will watch for stdin to become readable |
51 | // this one will watch for stdin to become readable |
50 | 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); |
51 | ev_io_start (loop, &stdin_watcher); |
53 | ev_io_start (loop, &stdin_watcher); |
… | |
… | |
54 | // simple non-repeating 5.5 second timeout |
56 | // simple non-repeating 5.5 second timeout |
55 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
57 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
56 | ev_timer_start (loop, &timeout_watcher); |
58 | ev_timer_start (loop, &timeout_watcher); |
57 | |
59 | |
58 | // now wait for events to arrive |
60 | // now wait for events to arrive |
59 | ev_loop (loop, 0); |
61 | ev_run (loop, 0); |
60 | |
62 | |
61 | // unloop was called, so exit |
63 | // unloop was called, so exit |
62 | return 0; |
64 | return 0; |
63 | } |
65 | } |
64 | |
66 | |
65 | =head1 DESCRIPTION |
67 | =head1 ABOUT THIS DOCUMENT |
|
|
68 | |
|
|
69 | This document documents the libev software package. |
66 | |
70 | |
67 | The newest version of this document is also available as an html-formatted |
71 | The newest version of this document is also available as an html-formatted |
68 | web page you might find easier to navigate when reading it for the first |
72 | web page you might find easier to navigate when reading it for the first |
69 | time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
73 | time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
|
|
74 | |
|
|
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 |
|
|
77 | on event-based programming, nor will it introduce event-based programming |
|
|
78 | with libev. |
|
|
79 | |
|
|
80 | Familiarity with event based programming techniques in general is assumed |
|
|
81 | throughout this document. |
|
|
82 | |
|
|
83 | =head1 WHAT TO READ WHEN IN A HURRY |
|
|
84 | |
|
|
85 | This manual tries to be very detailed, but unfortunately, this also makes |
|
|
86 | it very long. If you just want to know the basics of libev, I suggest |
|
|
87 | reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and |
|
|
88 | look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and |
|
|
89 | C<ev_timer> sections in L<WATCHER TYPES>. |
|
|
90 | |
|
|
91 | =head1 ABOUT LIBEV |
70 | |
92 | |
71 | Libev is an event loop: you register interest in certain events (such as a |
93 | Libev is an event loop: you register interest in certain events (such as a |
72 | file descriptor being readable or a timeout occurring), and it will manage |
94 | file descriptor being readable or a timeout occurring), and it will manage |
73 | these event sources and provide your program with events. |
95 | these event sources and provide your program with events. |
74 | |
96 | |
… | |
… | |
84 | =head2 FEATURES |
106 | =head2 FEATURES |
85 | |
107 | |
86 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
108 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
87 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
109 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
88 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
110 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
89 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
111 | (for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner |
90 | with customised rescheduling (C<ev_periodic>), synchronous signals |
112 | inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative |
91 | (C<ev_signal>), process status change events (C<ev_child>), and event |
113 | timers (C<ev_timer>), absolute timers with customised rescheduling |
92 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
114 | (C<ev_periodic>), synchronous signals (C<ev_signal>), process status |
93 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
115 | change events (C<ev_child>), and event watchers dealing with the event |
94 | file watchers (C<ev_stat>) and even limited support for fork events |
116 | loop mechanism itself (C<ev_idle>, C<ev_embed>, C<ev_prepare> and |
95 | (C<ev_fork>). |
117 | C<ev_check> watchers) as well as file watchers (C<ev_stat>) and even |
|
|
118 | limited support for fork events (C<ev_fork>). |
96 | |
119 | |
97 | It also is quite fast (see this |
120 | It also is quite fast (see this |
98 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
121 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
99 | for example). |
122 | for example). |
100 | |
123 | |
… | |
… | |
103 | Libev is very configurable. In this manual the default (and most common) |
126 | Libev is very configurable. In this manual the default (and most common) |
104 | configuration will be described, which supports multiple event loops. For |
127 | configuration will be described, which supports multiple event loops. For |
105 | more info about various configuration options please have a look at |
128 | more info about various configuration options please have a look at |
106 | B<EMBED> section in this manual. If libev was configured without support |
129 | B<EMBED> section in this manual. If libev was configured without support |
107 | for multiple event loops, then all functions taking an initial argument of |
130 | for multiple event loops, then all functions taking an initial argument of |
108 | name C<loop> (which is always of type C<ev_loop *>) will not have |
131 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
109 | this argument. |
132 | this argument. |
110 | |
133 | |
111 | =head2 TIME REPRESENTATION |
134 | =head2 TIME REPRESENTATION |
112 | |
135 | |
113 | Libev represents time as a single floating point number, representing the |
136 | Libev represents time as a single floating point number, representing |
114 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
137 | the (fractional) number of seconds since the (POSIX) epoch (in practice |
115 | the beginning of 1970, details are complicated, don't ask). This type is |
138 | somewhere near the beginning of 1970, details are complicated, don't |
116 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
139 | ask). This type is called C<ev_tstamp>, which is what you should use |
117 | to the C<double> type in C, and when you need to do any calculations on |
140 | too. It usually aliases to the C<double> type in C. When you need to do |
118 | it, you should treat it as some floating point value. Unlike the name |
141 | any calculations on it, you should treat it as some floating point value. |
|
|
142 | |
119 | component C<stamp> might indicate, it is also used for time differences |
143 | Unlike the name component C<stamp> might indicate, it is also used for |
120 | throughout libev. |
144 | time differences (e.g. delays) throughout libev. |
121 | |
145 | |
122 | =head1 ERROR HANDLING |
146 | =head1 ERROR HANDLING |
123 | |
147 | |
124 | Libev knows three classes of errors: operating system errors, usage errors |
148 | Libev knows three classes of errors: operating system errors, usage errors |
125 | and internal errors (bugs). |
149 | and internal errors (bugs). |
… | |
… | |
149 | |
173 | |
150 | =item ev_tstamp ev_time () |
174 | =item ev_tstamp ev_time () |
151 | |
175 | |
152 | Returns the current time as libev would use it. Please note that the |
176 | Returns the current time as libev would use it. Please note that the |
153 | C<ev_now> function is usually faster and also often returns the timestamp |
177 | C<ev_now> function is usually faster and also often returns the timestamp |
154 | you actually want to know. |
178 | you actually want to know. Also interesting is the combination of |
|
|
179 | C<ev_update_now> and C<ev_now>. |
155 | |
180 | |
156 | =item ev_sleep (ev_tstamp interval) |
181 | =item ev_sleep (ev_tstamp interval) |
157 | |
182 | |
158 | Sleep for the given interval: The current thread will be blocked until |
183 | Sleep for the given interval: The current thread will be blocked until |
159 | either it is interrupted or the given time interval has passed. Basically |
184 | either it is interrupted or the given time interval has passed. Basically |
… | |
… | |
176 | as this indicates an incompatible change. Minor versions are usually |
201 | as this indicates an incompatible change. Minor versions are usually |
177 | compatible to older versions, so a larger minor version alone is usually |
202 | compatible to older versions, so a larger minor version alone is usually |
178 | not a problem. |
203 | not a problem. |
179 | |
204 | |
180 | Example: Make sure we haven't accidentally been linked against the wrong |
205 | Example: Make sure we haven't accidentally been linked against the wrong |
181 | version. |
206 | version (note, however, that this will not detect other ABI mismatches, |
|
|
207 | such as LFS or reentrancy). |
182 | |
208 | |
183 | assert (("libev version mismatch", |
209 | assert (("libev version mismatch", |
184 | ev_version_major () == EV_VERSION_MAJOR |
210 | ev_version_major () == EV_VERSION_MAJOR |
185 | && ev_version_minor () >= EV_VERSION_MINOR)); |
211 | && ev_version_minor () >= EV_VERSION_MINOR)); |
186 | |
212 | |
… | |
… | |
197 | assert (("sorry, no epoll, no sex", |
223 | assert (("sorry, no epoll, no sex", |
198 | ev_supported_backends () & EVBACKEND_EPOLL)); |
224 | ev_supported_backends () & EVBACKEND_EPOLL)); |
199 | |
225 | |
200 | =item unsigned int ev_recommended_backends () |
226 | =item unsigned int ev_recommended_backends () |
201 | |
227 | |
202 | Return the set of all backends compiled into this binary of libev and also |
228 | Return the set of all backends compiled into this binary of libev and |
203 | recommended for this platform. This set is often smaller than the one |
229 | also recommended for this platform, meaning it will work for most file |
|
|
230 | descriptor types. This set is often smaller than the one returned by |
204 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
231 | C<ev_supported_backends>, as for example kqueue is broken on most BSDs |
205 | most BSDs and will not be auto-detected unless you explicitly request it |
232 | and will not be auto-detected unless you explicitly request it (assuming |
206 | (assuming you know what you are doing). This is the set of backends that |
233 | you know what you are doing). This is the set of backends that libev will |
207 | libev will probe for if you specify no backends explicitly. |
234 | probe for if you specify no backends explicitly. |
208 | |
235 | |
209 | =item unsigned int ev_embeddable_backends () |
236 | =item unsigned int ev_embeddable_backends () |
210 | |
237 | |
211 | Returns the set of backends that are embeddable in other event loops. This |
238 | Returns the set of backends that are embeddable in other event loops. This |
212 | is the theoretical, all-platform, value. To find which backends |
239 | value is platform-specific but can include backends not available on the |
213 | might be supported on the current system, you would need to look at |
240 | current system. To find which embeddable backends might be supported on |
214 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
241 | the current system, you would need to look at C<ev_embeddable_backends () |
215 | recommended ones. |
242 | & ev_supported_backends ()>, likewise for recommended ones. |
216 | |
243 | |
217 | See the description of C<ev_embed> watchers for more info. |
244 | See the description of C<ev_embed> watchers for more info. |
218 | |
245 | |
219 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT] |
246 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
220 | |
247 | |
221 | Sets the allocation function to use (the prototype is similar - the |
248 | Sets the allocation function to use (the prototype is similar - the |
222 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
249 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
223 | used to allocate and free memory (no surprises here). If it returns zero |
250 | used to allocate and free memory (no surprises here). If it returns zero |
224 | when memory needs to be allocated (C<size != 0>), the library might abort |
251 | when memory needs to be allocated (C<size != 0>), the library might abort |
… | |
… | |
250 | } |
277 | } |
251 | |
278 | |
252 | ... |
279 | ... |
253 | ev_set_allocator (persistent_realloc); |
280 | ev_set_allocator (persistent_realloc); |
254 | |
281 | |
255 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT] |
282 | =item ev_set_syserr_cb (void (*cb)(const char *msg)) |
256 | |
283 | |
257 | Set the callback function to call on a retryable system call error (such |
284 | Set the callback function to call on a retryable system call error (such |
258 | as failed select, poll, epoll_wait). The message is a printable string |
285 | as failed select, poll, epoll_wait). The message is a printable string |
259 | indicating the system call or subsystem causing the problem. If this |
286 | indicating the system call or subsystem causing the problem. If this |
260 | callback is set, then libev will expect it to remedy the situation, no |
287 | callback is set, then libev will expect it to remedy the situation, no |
… | |
… | |
274 | ... |
301 | ... |
275 | ev_set_syserr_cb (fatal_error); |
302 | ev_set_syserr_cb (fatal_error); |
276 | |
303 | |
277 | =back |
304 | =back |
278 | |
305 | |
279 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
306 | =head1 FUNCTIONS CONTROLLING EVENT LOOPS |
280 | |
307 | |
281 | An event loop is described by a C<struct ev_loop *> (the C<struct> |
308 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
282 | is I<not> optional in this case, as there is also an C<ev_loop> |
309 | I<not> optional in this case unless libev 3 compatibility is disabled, as |
283 | I<function>). |
310 | libev 3 had an C<ev_loop> function colliding with the struct name). |
284 | |
311 | |
285 | The library knows two types of such loops, the I<default> loop, which |
312 | The library knows two types of such loops, the I<default> loop, which |
286 | supports signals and child events, and dynamically created loops which do |
313 | supports child process events, and dynamically created event loops which |
287 | not. |
314 | do not. |
288 | |
315 | |
289 | =over 4 |
316 | =over 4 |
290 | |
317 | |
291 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
318 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
292 | |
319 | |
293 | This will initialise the default event loop if it hasn't been initialised |
320 | This returns the "default" event loop object, which is what you should |
294 | yet and return it. If the default loop could not be initialised, returns |
321 | normally use when you just need "the event loop". Event loop objects and |
295 | false. If it already was initialised it simply returns it (and ignores the |
322 | the C<flags> parameter are described in more detail in the entry for |
296 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
323 | C<ev_loop_new>. |
|
|
324 | |
|
|
325 | If the default loop is already initialised then this function simply |
|
|
326 | returns it (and ignores the flags. If that is troubling you, check |
|
|
327 | C<ev_backend ()> afterwards). Otherwise it will create it with the given |
|
|
328 | flags, which should almost always be C<0>, unless the caller is also the |
|
|
329 | one calling C<ev_run> or otherwise qualifies as "the main program". |
297 | |
330 | |
298 | If you don't know what event loop to use, use the one returned from this |
331 | If you don't know what event loop to use, use the one returned from this |
299 | function. |
332 | function (or via the C<EV_DEFAULT> macro). |
300 | |
333 | |
301 | Note that this function is I<not> thread-safe, so if you want to use it |
334 | Note that this function is I<not> thread-safe, so if you want to use it |
302 | from multiple threads, you have to lock (note also that this is unlikely, |
335 | from multiple threads, you have to employ some kind of mutex (note also |
303 | as loops cannot be shared easily between threads anyway). |
336 | that this case is unlikely, as loops cannot be shared easily between |
|
|
337 | threads anyway). |
304 | |
338 | |
305 | The default loop is the only loop that can handle C<ev_signal> and |
339 | The default loop is the only loop that can handle C<ev_child> watchers, |
306 | C<ev_child> watchers, and to do this, it always registers a handler |
340 | and to do this, it always registers a handler for C<SIGCHLD>. If this is |
307 | for C<SIGCHLD>. If this is a problem for your application you can either |
341 | a problem for your application you can either create a dynamic loop with |
308 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
342 | C<ev_loop_new> which doesn't do that, or you can simply overwrite the |
309 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
343 | C<SIGCHLD> signal handler I<after> calling C<ev_default_init>. |
310 | C<ev_default_init>. |
344 | |
|
|
345 | Example: This is the most typical usage. |
|
|
346 | |
|
|
347 | if (!ev_default_loop (0)) |
|
|
348 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
349 | |
|
|
350 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
351 | environment settings to be taken into account: |
|
|
352 | |
|
|
353 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
354 | |
|
|
355 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
|
|
356 | |
|
|
357 | This will create and initialise a new event loop object. If the loop |
|
|
358 | could not be initialised, returns false. |
|
|
359 | |
|
|
360 | This function is thread-safe, and one common way to use libev with |
|
|
361 | threads is indeed to create one loop per thread, and using the default |
|
|
362 | loop in the "main" or "initial" thread. |
311 | |
363 | |
312 | The flags argument can be used to specify special behaviour or specific |
364 | The flags argument can be used to specify special behaviour or specific |
313 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
365 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
314 | |
366 | |
315 | The following flags are supported: |
367 | The following flags are supported: |
… | |
… | |
330 | useful to try out specific backends to test their performance, or to work |
382 | useful to try out specific backends to test their performance, or to work |
331 | around bugs. |
383 | around bugs. |
332 | |
384 | |
333 | =item C<EVFLAG_FORKCHECK> |
385 | =item C<EVFLAG_FORKCHECK> |
334 | |
386 | |
335 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
387 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
336 | a fork, you can also make libev check for a fork in each iteration by |
388 | make libev check for a fork in each iteration by enabling this flag. |
337 | enabling this flag. |
|
|
338 | |
389 | |
339 | This works by calling C<getpid ()> on every iteration of the loop, |
390 | This works by calling C<getpid ()> on every iteration of the loop, |
340 | and thus this might slow down your event loop if you do a lot of loop |
391 | and thus this might slow down your event loop if you do a lot of loop |
341 | iterations and little real work, but is usually not noticeable (on my |
392 | iterations and little real work, but is usually not noticeable (on my |
342 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
393 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
… | |
… | |
348 | flag. |
399 | flag. |
349 | |
400 | |
350 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
401 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
351 | environment variable. |
402 | environment variable. |
352 | |
403 | |
|
|
404 | =item C<EVFLAG_NOINOTIFY> |
|
|
405 | |
|
|
406 | When this flag is specified, then libev will not attempt to use the |
|
|
407 | I<inotify> API for its C<ev_stat> watchers. Apart from debugging and |
|
|
408 | testing, this flag can be useful to conserve inotify file descriptors, as |
|
|
409 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
|
|
410 | |
|
|
411 | =item C<EVFLAG_SIGNALFD> |
|
|
412 | |
|
|
413 | When this flag is specified, then libev will attempt to use the |
|
|
414 | I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API |
|
|
415 | delivers signals synchronously, which makes it both faster and might make |
|
|
416 | it possible to get the queued signal data. It can also simplify signal |
|
|
417 | handling with threads, as long as you properly block signals in your |
|
|
418 | threads that are not interested in handling them. |
|
|
419 | |
|
|
420 | Signalfd will not be used by default as this changes your signal mask, and |
|
|
421 | there are a lot of shoddy libraries and programs (glib's threadpool for |
|
|
422 | example) that can't properly initialise their signal masks. |
|
|
423 | |
353 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
424 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
354 | |
425 | |
355 | This is your standard select(2) backend. Not I<completely> standard, as |
426 | This is your standard select(2) backend. Not I<completely> standard, as |
356 | libev tries to roll its own fd_set with no limits on the number of fds, |
427 | libev tries to roll its own fd_set with no limits on the number of fds, |
357 | but if that fails, expect a fairly low limit on the number of fds when |
428 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
381 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
452 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
382 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
453 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
383 | |
454 | |
384 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
455 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
385 | |
456 | |
|
|
457 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
|
|
458 | kernels). |
|
|
459 | |
386 | For few fds, this backend is a bit little slower than poll and select, |
460 | For few fds, this backend is a bit little slower than poll and select, |
387 | but it scales phenomenally better. While poll and select usually scale |
461 | but it scales phenomenally better. While poll and select usually scale |
388 | like O(total_fds) where n is the total number of fds (or the highest fd), |
462 | like O(total_fds) where n is the total number of fds (or the highest fd), |
389 | epoll scales either O(1) or O(active_fds). |
463 | epoll scales either O(1) or O(active_fds). |
390 | |
464 | |
391 | The epoll mechanism deserves honorable mention as the most misdesigned |
465 | The epoll mechanism deserves honorable mention as the most misdesigned |
392 | of the more advanced event mechanisms: mere annoyances include silently |
466 | of the more advanced event mechanisms: mere annoyances include silently |
393 | dropping file descriptors, requiring a system call per change per file |
467 | dropping file descriptors, requiring a system call per change per file |
394 | descriptor (and unnecessary guessing of parameters), problems with dup and |
468 | descriptor (and unnecessary guessing of parameters), problems with dup, |
|
|
469 | returning before the timeout value, resulting in additional iterations |
|
|
470 | (and only giving 5ms accuracy while select on the same platform gives |
395 | so on. The biggest issue is fork races, however - if a program forks then |
471 | 0.1ms) and so on. The biggest issue is fork races, however - if a program |
396 | I<both> parent and child process have to recreate the epoll set, which can |
472 | forks then I<both> parent and child process have to recreate the epoll |
397 | take considerable time (one syscall per file descriptor) and is of course |
473 | set, which can take considerable time (one syscall per file descriptor) |
398 | hard to detect. |
474 | and is of course hard to detect. |
399 | |
475 | |
400 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, but |
476 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, but |
401 | of course I<doesn't>, and epoll just loves to report events for totally |
477 | of course I<doesn't>, and epoll just loves to report events for totally |
402 | I<different> file descriptors (even already closed ones, so one cannot |
478 | I<different> file descriptors (even already closed ones, so one cannot |
403 | even remove them from the set) than registered in the set (especially |
479 | even remove them from the set) than registered in the set (especially |
404 | on SMP systems). Libev tries to counter these spurious notifications by |
480 | on SMP systems). Libev tries to counter these spurious notifications by |
405 | employing an additional generation counter and comparing that against the |
481 | employing an additional generation counter and comparing that against the |
406 | events to filter out spurious ones, recreating the set when required. |
482 | events to filter out spurious ones, recreating the set when required. Last |
|
|
483 | not least, it also refuses to work with some file descriptors which work |
|
|
484 | perfectly fine with C<select> (files, many character devices...). |
|
|
485 | |
|
|
486 | Epoll is truly the train wreck analog among event poll mechanisms. |
407 | |
487 | |
408 | While stopping, setting and starting an I/O watcher in the same iteration |
488 | While stopping, setting and starting an I/O watcher in the same iteration |
409 | will result in some caching, there is still a system call per such |
489 | will result in some caching, there is still a system call per such |
410 | incident (because the same I<file descriptor> could point to a different |
490 | incident (because the same I<file descriptor> could point to a different |
411 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
491 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
… | |
… | |
418 | starting a watcher (without re-setting it) also usually doesn't cause |
498 | starting a watcher (without re-setting it) also usually doesn't cause |
419 | extra overhead. A fork can both result in spurious notifications as well |
499 | extra overhead. A fork can both result in spurious notifications as well |
420 | as in libev having to destroy and recreate the epoll object, which can |
500 | as in libev having to destroy and recreate the epoll object, which can |
421 | take considerable time and thus should be avoided. |
501 | take considerable time and thus should be avoided. |
422 | |
502 | |
423 | All this means that, in practise, C<EVBACKEND_SELECT> is as fast or faster |
503 | All this means that, in practice, C<EVBACKEND_SELECT> can be as fast or |
424 | then epoll for maybe up to a hundred file descriptors. So sad. |
504 | faster than epoll for maybe up to a hundred file descriptors, depending on |
|
|
505 | the usage. So sad. |
425 | |
506 | |
426 | While nominally embeddable in other event loops, this feature is broken in |
507 | While nominally embeddable in other event loops, this feature is broken in |
427 | all kernel versions tested so far. |
508 | all kernel versions tested so far. |
428 | |
509 | |
429 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
510 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
… | |
… | |
457 | |
538 | |
458 | While nominally embeddable in other event loops, this doesn't work |
539 | While nominally embeddable in other event loops, this doesn't work |
459 | everywhere, so you might need to test for this. And since it is broken |
540 | everywhere, so you might need to test for this. And since it is broken |
460 | almost everywhere, you should only use it when you have a lot of sockets |
541 | almost everywhere, you should only use it when you have a lot of sockets |
461 | (for which it usually works), by embedding it into another event loop |
542 | (for which it usually works), by embedding it into another event loop |
462 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and, did I mention it, |
543 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> (but C<poll> is of course |
463 | using it only for sockets. |
544 | also broken on OS X)) and, did I mention it, using it only for sockets. |
464 | |
545 | |
465 | This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with |
546 | This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with |
466 | C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with |
547 | C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with |
467 | C<NOTE_EOF>. |
548 | C<NOTE_EOF>. |
468 | |
549 | |
… | |
… | |
503 | |
584 | |
504 | It is definitely not recommended to use this flag. |
585 | It is definitely not recommended to use this flag. |
505 | |
586 | |
506 | =back |
587 | =back |
507 | |
588 | |
508 | If one or more of these are or'ed into the flags value, then only these |
589 | If one or more of the backend flags are or'ed into the flags value, |
509 | backends will be tried (in the reverse order as listed here). If none are |
590 | then only these backends will be tried (in the reverse order as listed |
510 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
591 | here). If none are specified, all backends in C<ev_recommended_backends |
511 | |
592 | ()> will be tried. |
512 | Example: This is the most typical usage. |
|
|
513 | |
|
|
514 | if (!ev_default_loop (0)) |
|
|
515 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
516 | |
|
|
517 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
518 | environment settings to be taken into account: |
|
|
519 | |
|
|
520 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
521 | |
|
|
522 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
523 | used if available (warning, breaks stuff, best use only with your own |
|
|
524 | private event loop and only if you know the OS supports your types of |
|
|
525 | fds): |
|
|
526 | |
|
|
527 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
528 | |
|
|
529 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
|
|
530 | |
|
|
531 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
|
|
532 | always distinct from the default loop. Unlike the default loop, it cannot |
|
|
533 | handle signal and child watchers, and attempts to do so will be greeted by |
|
|
534 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
535 | |
|
|
536 | Note that this function I<is> thread-safe, and the recommended way to use |
|
|
537 | libev with threads is indeed to create one loop per thread, and using the |
|
|
538 | default loop in the "main" or "initial" thread. |
|
|
539 | |
593 | |
540 | Example: Try to create a event loop that uses epoll and nothing else. |
594 | Example: Try to create a event loop that uses epoll and nothing else. |
541 | |
595 | |
542 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
596 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
543 | if (!epoller) |
597 | if (!epoller) |
544 | fatal ("no epoll found here, maybe it hides under your chair"); |
598 | fatal ("no epoll found here, maybe it hides under your chair"); |
545 | |
599 | |
|
|
600 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
601 | used if available. |
|
|
602 | |
|
|
603 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
604 | |
546 | =item ev_default_destroy () |
605 | =item ev_loop_destroy (loop) |
547 | |
606 | |
548 | Destroys the default loop again (frees all memory and kernel state |
607 | Destroys an event loop object (frees all memory and kernel state |
549 | etc.). None of the active event watchers will be stopped in the normal |
608 | etc.). None of the active event watchers will be stopped in the normal |
550 | sense, so e.g. C<ev_is_active> might still return true. It is your |
609 | sense, so e.g. C<ev_is_active> might still return true. It is your |
551 | responsibility to either stop all watchers cleanly yourself I<before> |
610 | responsibility to either stop all watchers cleanly yourself I<before> |
552 | calling this function, or cope with the fact afterwards (which is usually |
611 | calling this function, or cope with the fact afterwards (which is usually |
553 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
612 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
… | |
… | |
555 | |
614 | |
556 | Note that certain global state, such as signal state (and installed signal |
615 | Note that certain global state, such as signal state (and installed signal |
557 | handlers), will not be freed by this function, and related watchers (such |
616 | handlers), will not be freed by this function, and related watchers (such |
558 | as signal and child watchers) would need to be stopped manually. |
617 | as signal and child watchers) would need to be stopped manually. |
559 | |
618 | |
560 | In general it is not advisable to call this function except in the |
619 | This function is normally used on loop objects allocated by |
561 | rare occasion where you really need to free e.g. the signal handling |
620 | C<ev_loop_new>, but it can also be used on the default loop returned by |
|
|
621 | C<ev_default_loop>, in which case it is not thread-safe. |
|
|
622 | |
|
|
623 | Note that it is not advisable to call this function on the default loop |
|
|
624 | except in the rare occasion where you really need to free its resources. |
562 | pipe fds. If you need dynamically allocated loops it is better to use |
625 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
563 | C<ev_loop_new> and C<ev_loop_destroy>). |
626 | and C<ev_loop_destroy>. |
564 | |
627 | |
565 | =item ev_loop_destroy (loop) |
628 | =item ev_loop_fork (loop) |
566 | |
629 | |
567 | Like C<ev_default_destroy>, but destroys an event loop created by an |
|
|
568 | earlier call to C<ev_loop_new>. |
|
|
569 | |
|
|
570 | =item ev_default_fork () |
|
|
571 | |
|
|
572 | This function sets a flag that causes subsequent C<ev_loop> iterations |
630 | This function sets a flag that causes subsequent C<ev_run> iterations to |
573 | to reinitialise the kernel state for backends that have one. Despite the |
631 | reinitialise the kernel state for backends that have one. Despite the |
574 | name, you can call it anytime, but it makes most sense after forking, in |
632 | name, you can call it anytime, but it makes most sense after forking, in |
575 | the child process (or both child and parent, but that again makes little |
633 | the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the |
576 | sense). You I<must> call it in the child before using any of the libev |
634 | child before resuming or calling C<ev_run>. |
577 | functions, and it will only take effect at the next C<ev_loop> iteration. |
635 | |
|
|
636 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
|
|
637 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
|
|
638 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
|
|
639 | during fork. |
578 | |
640 | |
579 | On the other hand, you only need to call this function in the child |
641 | On the other hand, you only need to call this function in the child |
580 | process if and only if you want to use the event library in the child. If |
642 | process if and only if you want to use the event loop in the child. If |
581 | you just fork+exec, you don't have to call it at all. |
643 | you just fork+exec or create a new loop in the child, you don't have to |
|
|
644 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
|
|
645 | difference, but libev will usually detect this case on its own and do a |
|
|
646 | costly reset of the backend). |
582 | |
647 | |
583 | The function itself is quite fast and it's usually not a problem to call |
648 | The function itself is quite fast and it's usually not a problem to call |
584 | it just in case after a fork. To make this easy, the function will fit in |
649 | it just in case after a fork. |
585 | quite nicely into a call to C<pthread_atfork>: |
|
|
586 | |
650 | |
|
|
651 | Example: Automate calling C<ev_loop_fork> on the default loop when |
|
|
652 | using pthreads. |
|
|
653 | |
|
|
654 | static void |
|
|
655 | post_fork_child (void) |
|
|
656 | { |
|
|
657 | ev_loop_fork (EV_DEFAULT); |
|
|
658 | } |
|
|
659 | |
|
|
660 | ... |
587 | pthread_atfork (0, 0, ev_default_fork); |
661 | pthread_atfork (0, 0, post_fork_child); |
588 | |
|
|
589 | =item ev_loop_fork (loop) |
|
|
590 | |
|
|
591 | Like C<ev_default_fork>, but acts on an event loop created by |
|
|
592 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
|
|
593 | after fork that you want to re-use in the child, and how you do this is |
|
|
594 | entirely your own problem. |
|
|
595 | |
662 | |
596 | =item int ev_is_default_loop (loop) |
663 | =item int ev_is_default_loop (loop) |
597 | |
664 | |
598 | Returns true when the given loop is, in fact, the default loop, and false |
665 | Returns true when the given loop is, in fact, the default loop, and false |
599 | otherwise. |
666 | otherwise. |
600 | |
667 | |
601 | =item unsigned int ev_loop_count (loop) |
668 | =item unsigned int ev_iteration (loop) |
602 | |
669 | |
603 | Returns the count of loop iterations for the loop, which is identical to |
670 | Returns the current iteration count for the event loop, which is identical |
604 | the number of times libev did poll for new events. It starts at C<0> and |
671 | to the number of times libev did poll for new events. It starts at C<0> |
605 | happily wraps around with enough iterations. |
672 | and happily wraps around with enough iterations. |
606 | |
673 | |
607 | This value can sometimes be useful as a generation counter of sorts (it |
674 | This value can sometimes be useful as a generation counter of sorts (it |
608 | "ticks" the number of loop iterations), as it roughly corresponds with |
675 | "ticks" the number of loop iterations), as it roughly corresponds with |
609 | C<ev_prepare> and C<ev_check> calls. |
676 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
|
|
677 | prepare and check phases. |
|
|
678 | |
|
|
679 | =item unsigned int ev_depth (loop) |
|
|
680 | |
|
|
681 | Returns the number of times C<ev_run> was entered minus the number of |
|
|
682 | times C<ev_run> was exited normally, in other words, the recursion depth. |
|
|
683 | |
|
|
684 | Outside C<ev_run>, this number is zero. In a callback, this number is |
|
|
685 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
|
|
686 | in which case it is higher. |
|
|
687 | |
|
|
688 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread, |
|
|
689 | throwing an exception etc.), doesn't count as "exit" - consider this |
|
|
690 | as a hint to avoid such ungentleman-like behaviour unless it's really |
|
|
691 | convenient, in which case it is fully supported. |
610 | |
692 | |
611 | =item unsigned int ev_backend (loop) |
693 | =item unsigned int ev_backend (loop) |
612 | |
694 | |
613 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
695 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
614 | use. |
696 | use. |
… | |
… | |
623 | |
705 | |
624 | =item ev_now_update (loop) |
706 | =item ev_now_update (loop) |
625 | |
707 | |
626 | Establishes the current time by querying the kernel, updating the time |
708 | Establishes the current time by querying the kernel, updating the time |
627 | returned by C<ev_now ()> in the progress. This is a costly operation and |
709 | returned by C<ev_now ()> in the progress. This is a costly operation and |
628 | is usually done automatically within C<ev_loop ()>. |
710 | is usually done automatically within C<ev_run ()>. |
629 | |
711 | |
630 | This function is rarely useful, but when some event callback runs for a |
712 | This function is rarely useful, but when some event callback runs for a |
631 | very long time without entering the event loop, updating libev's idea of |
713 | very long time without entering the event loop, updating libev's idea of |
632 | the current time is a good idea. |
714 | the current time is a good idea. |
633 | |
715 | |
634 | See also "The special problem of time updates" in the C<ev_timer> section. |
716 | See also L<The special problem of time updates> in the C<ev_timer> section. |
635 | |
717 | |
|
|
718 | =item ev_suspend (loop) |
|
|
719 | |
|
|
720 | =item ev_resume (loop) |
|
|
721 | |
|
|
722 | These two functions suspend and resume an event loop, for use when the |
|
|
723 | loop is not used for a while and timeouts should not be processed. |
|
|
724 | |
|
|
725 | A typical use case would be an interactive program such as a game: When |
|
|
726 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
|
|
727 | would be best to handle timeouts as if no time had actually passed while |
|
|
728 | the program was suspended. This can be achieved by calling C<ev_suspend> |
|
|
729 | in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling |
|
|
730 | C<ev_resume> directly afterwards to resume timer processing. |
|
|
731 | |
|
|
732 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
|
|
733 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
|
|
734 | will be rescheduled (that is, they will lose any events that would have |
|
|
735 | occurred while suspended). |
|
|
736 | |
|
|
737 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
|
|
738 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
|
|
739 | without a previous call to C<ev_suspend>. |
|
|
740 | |
|
|
741 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
|
|
742 | event loop time (see C<ev_now_update>). |
|
|
743 | |
636 | =item ev_loop (loop, int flags) |
744 | =item ev_run (loop, int flags) |
637 | |
745 | |
638 | Finally, this is it, the event handler. This function usually is called |
746 | Finally, this is it, the event handler. This function usually is called |
639 | after you initialised all your watchers and you want to start handling |
747 | after you have initialised all your watchers and you want to start |
640 | events. |
748 | handling events. It will ask the operating system for any new events, call |
|
|
749 | the watcher callbacks, an then repeat the whole process indefinitely: This |
|
|
750 | is why event loops are called I<loops>. |
641 | |
751 | |
642 | If the flags argument is specified as C<0>, it will not return until |
752 | If the flags argument is specified as C<0>, it will keep handling events |
643 | either no event watchers are active anymore or C<ev_unloop> was called. |
753 | until either no event watchers are active anymore or C<ev_break> was |
|
|
754 | called. |
644 | |
755 | |
645 | Please note that an explicit C<ev_unloop> is usually better than |
756 | Please note that an explicit C<ev_break> is usually better than |
646 | relying on all watchers to be stopped when deciding when a program has |
757 | relying on all watchers to be stopped when deciding when a program has |
647 | finished (especially in interactive programs), but having a program |
758 | finished (especially in interactive programs), but having a program |
648 | that automatically loops as long as it has to and no longer by virtue |
759 | that automatically loops as long as it has to and no longer by virtue |
649 | of relying on its watchers stopping correctly, that is truly a thing of |
760 | of relying on its watchers stopping correctly, that is truly a thing of |
650 | beauty. |
761 | beauty. |
651 | |
762 | |
|
|
763 | This function is also I<mostly> exception-safe - you can break out of |
|
|
764 | a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++ |
|
|
765 | exception and so on. This does not decrement the C<ev_depth> value, nor |
|
|
766 | will it clear any outstanding C<EVBREAK_ONE> breaks. |
|
|
767 | |
652 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
768 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
653 | those events and any already outstanding ones, but will not block your |
769 | those events and any already outstanding ones, but will not wait and |
654 | process in case there are no events and will return after one iteration of |
770 | block your process in case there are no events and will return after one |
655 | the loop. |
771 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
772 | events while doing lengthy calculations, to keep the program responsive. |
656 | |
773 | |
657 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
774 | A flags value of C<EVRUN_ONCE> will look for new events (waiting if |
658 | necessary) and will handle those and any already outstanding ones. It |
775 | necessary) and will handle those and any already outstanding ones. It |
659 | will block your process until at least one new event arrives (which could |
776 | will block your process until at least one new event arrives (which could |
660 | be an event internal to libev itself, so there is no guarantee that a |
777 | be an event internal to libev itself, so there is no guarantee that a |
661 | user-registered callback will be called), and will return after one |
778 | user-registered callback will be called), and will return after one |
662 | iteration of the loop. |
779 | iteration of the loop. |
663 | |
780 | |
664 | This is useful if you are waiting for some external event in conjunction |
781 | This is useful if you are waiting for some external event in conjunction |
665 | with something not expressible using other libev watchers (i.e. "roll your |
782 | with something not expressible using other libev watchers (i.e. "roll your |
666 | own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
783 | own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
667 | usually a better approach for this kind of thing. |
784 | usually a better approach for this kind of thing. |
668 | |
785 | |
669 | Here are the gory details of what C<ev_loop> does: |
786 | Here are the gory details of what C<ev_run> does: |
670 | |
787 | |
|
|
788 | - Increment loop depth. |
|
|
789 | - Reset the ev_break status. |
671 | - Before the first iteration, call any pending watchers. |
790 | - Before the first iteration, call any pending watchers. |
|
|
791 | LOOP: |
672 | * If EVFLAG_FORKCHECK was used, check for a fork. |
792 | - If EVFLAG_FORKCHECK was used, check for a fork. |
673 | - If a fork was detected (by any means), queue and call all fork watchers. |
793 | - If a fork was detected (by any means), queue and call all fork watchers. |
674 | - Queue and call all prepare watchers. |
794 | - Queue and call all prepare watchers. |
|
|
795 | - If ev_break was called, goto FINISH. |
675 | - If we have been forked, detach and recreate the kernel state |
796 | - If we have been forked, detach and recreate the kernel state |
676 | as to not disturb the other process. |
797 | as to not disturb the other process. |
677 | - Update the kernel state with all outstanding changes. |
798 | - Update the kernel state with all outstanding changes. |
678 | - Update the "event loop time" (ev_now ()). |
799 | - Update the "event loop time" (ev_now ()). |
679 | - Calculate for how long to sleep or block, if at all |
800 | - Calculate for how long to sleep or block, if at all |
680 | (active idle watchers, EVLOOP_NONBLOCK or not having |
801 | (active idle watchers, EVRUN_NOWAIT or not having |
681 | any active watchers at all will result in not sleeping). |
802 | any active watchers at all will result in not sleeping). |
682 | - Sleep if the I/O and timer collect interval say so. |
803 | - Sleep if the I/O and timer collect interval say so. |
|
|
804 | - Increment loop iteration counter. |
683 | - Block the process, waiting for any events. |
805 | - Block the process, waiting for any events. |
684 | - Queue all outstanding I/O (fd) events. |
806 | - Queue all outstanding I/O (fd) events. |
685 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
807 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
686 | - Queue all expired timers. |
808 | - Queue all expired timers. |
687 | - Queue all expired periodics. |
809 | - Queue all expired periodics. |
688 | - Unless any events are pending now, queue all idle watchers. |
810 | - Queue all idle watchers with priority higher than that of pending events. |
689 | - Queue all check watchers. |
811 | - Queue all check watchers. |
690 | - Call all queued watchers in reverse order (i.e. check watchers first). |
812 | - Call all queued watchers in reverse order (i.e. check watchers first). |
691 | Signals and child watchers are implemented as I/O watchers, and will |
813 | Signals and child watchers are implemented as I/O watchers, and will |
692 | be handled here by queueing them when their watcher gets executed. |
814 | be handled here by queueing them when their watcher gets executed. |
693 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
815 | - If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
694 | were used, or there are no active watchers, return, otherwise |
816 | were used, or there are no active watchers, goto FINISH, otherwise |
695 | continue with step *. |
817 | continue with step LOOP. |
|
|
818 | FINISH: |
|
|
819 | - Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
820 | - Decrement the loop depth. |
|
|
821 | - Return. |
696 | |
822 | |
697 | Example: Queue some jobs and then loop until no events are outstanding |
823 | Example: Queue some jobs and then loop until no events are outstanding |
698 | anymore. |
824 | anymore. |
699 | |
825 | |
700 | ... queue jobs here, make sure they register event watchers as long |
826 | ... queue jobs here, make sure they register event watchers as long |
701 | ... as they still have work to do (even an idle watcher will do..) |
827 | ... as they still have work to do (even an idle watcher will do..) |
702 | ev_loop (my_loop, 0); |
828 | ev_run (my_loop, 0); |
703 | ... jobs done or somebody called unloop. yeah! |
829 | ... jobs done or somebody called unloop. yeah! |
704 | |
830 | |
705 | =item ev_unloop (loop, how) |
831 | =item ev_break (loop, how) |
706 | |
832 | |
707 | Can be used to make a call to C<ev_loop> return early (but only after it |
833 | Can be used to make a call to C<ev_run> return early (but only after it |
708 | has processed all outstanding events). The C<how> argument must be either |
834 | has processed all outstanding events). The C<how> argument must be either |
709 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
835 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
710 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
836 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
711 | |
837 | |
712 | This "unloop state" will be cleared when entering C<ev_loop> again. |
838 | This "break state" will be cleared on the next call to C<ev_run>. |
713 | |
839 | |
714 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
840 | It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in |
|
|
841 | which case it will have no effect. |
715 | |
842 | |
716 | =item ev_ref (loop) |
843 | =item ev_ref (loop) |
717 | |
844 | |
718 | =item ev_unref (loop) |
845 | =item ev_unref (loop) |
719 | |
846 | |
720 | Ref/unref can be used to add or remove a reference count on the event |
847 | Ref/unref can be used to add or remove a reference count on the event |
721 | loop: Every watcher keeps one reference, and as long as the reference |
848 | loop: Every watcher keeps one reference, and as long as the reference |
722 | count is nonzero, C<ev_loop> will not return on its own. |
849 | count is nonzero, C<ev_run> will not return on its own. |
723 | |
850 | |
724 | If you have a watcher you never unregister that should not keep C<ev_loop> |
851 | This is useful when you have a watcher that you never intend to |
725 | from returning, call ev_unref() after starting, and ev_ref() before |
852 | unregister, but that nevertheless should not keep C<ev_run> from |
|
|
853 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
726 | stopping it. |
854 | before stopping it. |
727 | |
855 | |
728 | As an example, libev itself uses this for its internal signal pipe: It is |
856 | As an example, libev itself uses this for its internal signal pipe: It |
729 | not visible to the libev user and should not keep C<ev_loop> from exiting |
857 | is not visible to the libev user and should not keep C<ev_run> from |
730 | if no event watchers registered by it are active. It is also an excellent |
858 | exiting if no event watchers registered by it are active. It is also an |
731 | way to do this for generic recurring timers or from within third-party |
859 | excellent way to do this for generic recurring timers or from within |
732 | libraries. Just remember to I<unref after start> and I<ref before stop> |
860 | third-party libraries. Just remember to I<unref after start> and I<ref |
733 | (but only if the watcher wasn't active before, or was active before, |
861 | before stop> (but only if the watcher wasn't active before, or was active |
734 | respectively). |
862 | before, respectively. Note also that libev might stop watchers itself |
|
|
863 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
|
|
864 | in the callback). |
735 | |
865 | |
736 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
866 | Example: Create a signal watcher, but keep it from keeping C<ev_run> |
737 | running when nothing else is active. |
867 | running when nothing else is active. |
738 | |
868 | |
739 | ev_signal exitsig; |
869 | ev_signal exitsig; |
740 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
870 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
741 | ev_signal_start (loop, &exitsig); |
871 | ev_signal_start (loop, &exitsig); |
… | |
… | |
768 | |
898 | |
769 | By setting a higher I<io collect interval> you allow libev to spend more |
899 | By setting a higher I<io collect interval> you allow libev to spend more |
770 | time collecting I/O events, so you can handle more events per iteration, |
900 | time collecting I/O events, so you can handle more events per iteration, |
771 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
901 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
772 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
902 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
773 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
903 | introduce an additional C<ev_sleep ()> call into most loop iterations. The |
|
|
904 | sleep time ensures that libev will not poll for I/O events more often then |
|
|
905 | once per this interval, on average. |
774 | |
906 | |
775 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
907 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
776 | to spend more time collecting timeouts, at the expense of increased |
908 | to spend more time collecting timeouts, at the expense of increased |
777 | latency/jitter/inexactness (the watcher callback will be called |
909 | latency/jitter/inexactness (the watcher callback will be called |
778 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
910 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
… | |
… | |
780 | |
912 | |
781 | Many (busy) programs can usually benefit by setting the I/O collect |
913 | Many (busy) programs can usually benefit by setting the I/O collect |
782 | interval to a value near C<0.1> or so, which is often enough for |
914 | interval to a value near C<0.1> or so, which is often enough for |
783 | interactive servers (of course not for games), likewise for timeouts. It |
915 | interactive servers (of course not for games), likewise for timeouts. It |
784 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
916 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
785 | as this approaches the timing granularity of most systems. |
917 | as this approaches the timing granularity of most systems. Note that if |
|
|
918 | you do transactions with the outside world and you can't increase the |
|
|
919 | parallelity, then this setting will limit your transaction rate (if you |
|
|
920 | need to poll once per transaction and the I/O collect interval is 0.01, |
|
|
921 | then you can't do more than 100 transactions per second). |
786 | |
922 | |
787 | Setting the I<timeout collect interval> can improve the opportunity for |
923 | Setting the I<timeout collect interval> can improve the opportunity for |
788 | saving power, as the program will "bundle" timer callback invocations that |
924 | saving power, as the program will "bundle" timer callback invocations that |
789 | are "near" in time together, by delaying some, thus reducing the number of |
925 | are "near" in time together, by delaying some, thus reducing the number of |
790 | times the process sleeps and wakes up again. Another useful technique to |
926 | times the process sleeps and wakes up again. Another useful technique to |
791 | reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure |
927 | reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure |
792 | they fire on, say, one-second boundaries only. |
928 | they fire on, say, one-second boundaries only. |
793 | |
929 | |
|
|
930 | Example: we only need 0.1s timeout granularity, and we wish not to poll |
|
|
931 | more often than 100 times per second: |
|
|
932 | |
|
|
933 | ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1); |
|
|
934 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
|
|
935 | |
|
|
936 | =item ev_invoke_pending (loop) |
|
|
937 | |
|
|
938 | This call will simply invoke all pending watchers while resetting their |
|
|
939 | pending state. Normally, C<ev_run> does this automatically when required, |
|
|
940 | but when overriding the invoke callback this call comes handy. This |
|
|
941 | function can be invoked from a watcher - this can be useful for example |
|
|
942 | when you want to do some lengthy calculation and want to pass further |
|
|
943 | event handling to another thread (you still have to make sure only one |
|
|
944 | thread executes within C<ev_invoke_pending> or C<ev_run> of course). |
|
|
945 | |
|
|
946 | =item int ev_pending_count (loop) |
|
|
947 | |
|
|
948 | Returns the number of pending watchers - zero indicates that no watchers |
|
|
949 | are pending. |
|
|
950 | |
|
|
951 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
|
|
952 | |
|
|
953 | This overrides the invoke pending functionality of the loop: Instead of |
|
|
954 | invoking all pending watchers when there are any, C<ev_run> will call |
|
|
955 | this callback instead. This is useful, for example, when you want to |
|
|
956 | invoke the actual watchers inside another context (another thread etc.). |
|
|
957 | |
|
|
958 | If you want to reset the callback, use C<ev_invoke_pending> as new |
|
|
959 | callback. |
|
|
960 | |
|
|
961 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P)) |
|
|
962 | |
|
|
963 | Sometimes you want to share the same loop between multiple threads. This |
|
|
964 | can be done relatively simply by putting mutex_lock/unlock calls around |
|
|
965 | each call to a libev function. |
|
|
966 | |
|
|
967 | However, C<ev_run> can run an indefinite time, so it is not feasible |
|
|
968 | to wait for it to return. One way around this is to wake up the event |
|
|
969 | loop via C<ev_break> and C<av_async_send>, another way is to set these |
|
|
970 | I<release> and I<acquire> callbacks on the loop. |
|
|
971 | |
|
|
972 | When set, then C<release> will be called just before the thread is |
|
|
973 | suspended waiting for new events, and C<acquire> is called just |
|
|
974 | afterwards. |
|
|
975 | |
|
|
976 | Ideally, C<release> will just call your mutex_unlock function, and |
|
|
977 | C<acquire> will just call the mutex_lock function again. |
|
|
978 | |
|
|
979 | While event loop modifications are allowed between invocations of |
|
|
980 | C<release> and C<acquire> (that's their only purpose after all), no |
|
|
981 | modifications done will affect the event loop, i.e. adding watchers will |
|
|
982 | have no effect on the set of file descriptors being watched, or the time |
|
|
983 | waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it |
|
|
984 | to take note of any changes you made. |
|
|
985 | |
|
|
986 | In theory, threads executing C<ev_run> will be async-cancel safe between |
|
|
987 | invocations of C<release> and C<acquire>. |
|
|
988 | |
|
|
989 | See also the locking example in the C<THREADS> section later in this |
|
|
990 | document. |
|
|
991 | |
|
|
992 | =item ev_set_userdata (loop, void *data) |
|
|
993 | |
|
|
994 | =item void *ev_userdata (loop) |
|
|
995 | |
|
|
996 | Set and retrieve a single C<void *> associated with a loop. When |
|
|
997 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
|
|
998 | C<0>. |
|
|
999 | |
|
|
1000 | These two functions can be used to associate arbitrary data with a loop, |
|
|
1001 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
|
|
1002 | C<acquire> callbacks described above, but of course can be (ab-)used for |
|
|
1003 | any other purpose as well. |
|
|
1004 | |
794 | =item ev_loop_verify (loop) |
1005 | =item ev_verify (loop) |
795 | |
1006 | |
796 | This function only does something when C<EV_VERIFY> support has been |
1007 | This function only does something when C<EV_VERIFY> support has been |
797 | compiled in, which is the default for non-minimal builds. It tries to go |
1008 | compiled in, which is the default for non-minimal builds. It tries to go |
798 | through all internal structures and checks them for validity. If anything |
1009 | through all internal structures and checks them for validity. If anything |
799 | is found to be inconsistent, it will print an error message to standard |
1010 | is found to be inconsistent, it will print an error message to standard |
… | |
… | |
810 | |
1021 | |
811 | In the following description, uppercase C<TYPE> in names stands for the |
1022 | In the following description, uppercase C<TYPE> in names stands for the |
812 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
1023 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
813 | watchers and C<ev_io_start> for I/O watchers. |
1024 | watchers and C<ev_io_start> for I/O watchers. |
814 | |
1025 | |
815 | A watcher is a structure that you create and register to record your |
1026 | A watcher is an opaque structure that you allocate and register to record |
816 | interest in some event. For instance, if you want to wait for STDIN to |
1027 | your interest in some event. To make a concrete example, imagine you want |
817 | become readable, you would create an C<ev_io> watcher for that: |
1028 | to wait for STDIN to become readable, you would create an C<ev_io> watcher |
|
|
1029 | for that: |
818 | |
1030 | |
819 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
1031 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
820 | { |
1032 | { |
821 | ev_io_stop (w); |
1033 | ev_io_stop (w); |
822 | ev_unloop (loop, EVUNLOOP_ALL); |
1034 | ev_break (loop, EVBREAK_ALL); |
823 | } |
1035 | } |
824 | |
1036 | |
825 | struct ev_loop *loop = ev_default_loop (0); |
1037 | struct ev_loop *loop = ev_default_loop (0); |
826 | |
1038 | |
827 | ev_io stdin_watcher; |
1039 | ev_io stdin_watcher; |
828 | |
1040 | |
829 | ev_init (&stdin_watcher, my_cb); |
1041 | ev_init (&stdin_watcher, my_cb); |
830 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1042 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
831 | ev_io_start (loop, &stdin_watcher); |
1043 | ev_io_start (loop, &stdin_watcher); |
832 | |
1044 | |
833 | ev_loop (loop, 0); |
1045 | ev_run (loop, 0); |
834 | |
1046 | |
835 | As you can see, you are responsible for allocating the memory for your |
1047 | As you can see, you are responsible for allocating the memory for your |
836 | watcher structures (and it is I<usually> a bad idea to do this on the |
1048 | watcher structures (and it is I<usually> a bad idea to do this on the |
837 | stack). |
1049 | stack). |
838 | |
1050 | |
839 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
1051 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
840 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
1052 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
841 | |
1053 | |
842 | Each watcher structure must be initialised by a call to C<ev_init |
1054 | Each watcher structure must be initialised by a call to C<ev_init (watcher |
843 | (watcher *, callback)>, which expects a callback to be provided. This |
1055 | *, callback)>, which expects a callback to be provided. This callback is |
844 | callback gets invoked each time the event occurs (or, in the case of I/O |
1056 | invoked each time the event occurs (or, in the case of I/O watchers, each |
845 | watchers, each time the event loop detects that the file descriptor given |
1057 | time the event loop detects that the file descriptor given is readable |
846 | is readable and/or writable). |
1058 | and/or writable). |
847 | |
1059 | |
848 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
1060 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
849 | macro to configure it, with arguments specific to the watcher type. There |
1061 | macro to configure it, with arguments specific to the watcher type. There |
850 | is also a macro to combine initialisation and setting in one call: C<< |
1062 | is also a macro to combine initialisation and setting in one call: C<< |
851 | ev_TYPE_init (watcher *, callback, ...) >>. |
1063 | ev_TYPE_init (watcher *, callback, ...) >>. |
… | |
… | |
874 | =item C<EV_WRITE> |
1086 | =item C<EV_WRITE> |
875 | |
1087 | |
876 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1088 | The file descriptor in the C<ev_io> watcher has become readable and/or |
877 | writable. |
1089 | writable. |
878 | |
1090 | |
879 | =item C<EV_TIMEOUT> |
1091 | =item C<EV_TIMER> |
880 | |
1092 | |
881 | The C<ev_timer> watcher has timed out. |
1093 | The C<ev_timer> watcher has timed out. |
882 | |
1094 | |
883 | =item C<EV_PERIODIC> |
1095 | =item C<EV_PERIODIC> |
884 | |
1096 | |
… | |
… | |
902 | |
1114 | |
903 | =item C<EV_PREPARE> |
1115 | =item C<EV_PREPARE> |
904 | |
1116 | |
905 | =item C<EV_CHECK> |
1117 | =item C<EV_CHECK> |
906 | |
1118 | |
907 | All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts |
1119 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
908 | to gather new events, and all C<ev_check> watchers are invoked just after |
1120 | to gather new events, and all C<ev_check> watchers are invoked just after |
909 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
1121 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
910 | received events. Callbacks of both watcher types can start and stop as |
1122 | received events. Callbacks of both watcher types can start and stop as |
911 | many watchers as they want, and all of them will be taken into account |
1123 | many watchers as they want, and all of them will be taken into account |
912 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1124 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
913 | C<ev_loop> from blocking). |
1125 | C<ev_run> from blocking). |
914 | |
1126 | |
915 | =item C<EV_EMBED> |
1127 | =item C<EV_EMBED> |
916 | |
1128 | |
917 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1129 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
918 | |
1130 | |
919 | =item C<EV_FORK> |
1131 | =item C<EV_FORK> |
920 | |
1132 | |
921 | The event loop has been resumed in the child process after fork (see |
1133 | The event loop has been resumed in the child process after fork (see |
922 | C<ev_fork>). |
1134 | C<ev_fork>). |
923 | |
1135 | |
|
|
1136 | =item C<EV_CLEANUP> |
|
|
1137 | |
|
|
1138 | The event loop is about to be destroyed (see C<ev_cleanup>). |
|
|
1139 | |
924 | =item C<EV_ASYNC> |
1140 | =item C<EV_ASYNC> |
925 | |
1141 | |
926 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1142 | The given async watcher has been asynchronously notified (see C<ev_async>). |
|
|
1143 | |
|
|
1144 | =item C<EV_CUSTOM> |
|
|
1145 | |
|
|
1146 | Not ever sent (or otherwise used) by libev itself, but can be freely used |
|
|
1147 | by libev users to signal watchers (e.g. via C<ev_feed_event>). |
927 | |
1148 | |
928 | =item C<EV_ERROR> |
1149 | =item C<EV_ERROR> |
929 | |
1150 | |
930 | An unspecified error has occurred, the watcher has been stopped. This might |
1151 | An unspecified error has occurred, the watcher has been stopped. This might |
931 | happen because the watcher could not be properly started because libev |
1152 | happen because the watcher could not be properly started because libev |
… | |
… | |
969 | |
1190 | |
970 | ev_io w; |
1191 | ev_io w; |
971 | ev_init (&w, my_cb); |
1192 | ev_init (&w, my_cb); |
972 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1193 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
973 | |
1194 | |
974 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
1195 | =item C<ev_TYPE_set> (ev_TYPE *watcher, [args]) |
975 | |
1196 | |
976 | This macro initialises the type-specific parts of a watcher. You need to |
1197 | This macro initialises the type-specific parts of a watcher. You need to |
977 | call C<ev_init> at least once before you call this macro, but you can |
1198 | call C<ev_init> at least once before you call this macro, but you can |
978 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1199 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
979 | macro on a watcher that is active (it can be pending, however, which is a |
1200 | macro on a watcher that is active (it can be pending, however, which is a |
… | |
… | |
992 | |
1213 | |
993 | Example: Initialise and set an C<ev_io> watcher in one step. |
1214 | Example: Initialise and set an C<ev_io> watcher in one step. |
994 | |
1215 | |
995 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1216 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
996 | |
1217 | |
997 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
1218 | =item C<ev_TYPE_start> (loop, ev_TYPE *watcher) |
998 | |
1219 | |
999 | Starts (activates) the given watcher. Only active watchers will receive |
1220 | Starts (activates) the given watcher. Only active watchers will receive |
1000 | events. If the watcher is already active nothing will happen. |
1221 | events. If the watcher is already active nothing will happen. |
1001 | |
1222 | |
1002 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1223 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1003 | whole section. |
1224 | whole section. |
1004 | |
1225 | |
1005 | ev_io_start (EV_DEFAULT_UC, &w); |
1226 | ev_io_start (EV_DEFAULT_UC, &w); |
1006 | |
1227 | |
1007 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1228 | =item C<ev_TYPE_stop> (loop, ev_TYPE *watcher) |
1008 | |
1229 | |
1009 | Stops the given watcher if active, and clears the pending status (whether |
1230 | Stops the given watcher if active, and clears the pending status (whether |
1010 | the watcher was active or not). |
1231 | the watcher was active or not). |
1011 | |
1232 | |
1012 | It is possible that stopped watchers are pending - for example, |
1233 | It is possible that stopped watchers are pending - for example, |
… | |
… | |
1037 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1258 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1038 | |
1259 | |
1039 | Change the callback. You can change the callback at virtually any time |
1260 | Change the callback. You can change the callback at virtually any time |
1040 | (modulo threads). |
1261 | (modulo threads). |
1041 | |
1262 | |
1042 | =item ev_set_priority (ev_TYPE *watcher, priority) |
1263 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1043 | |
1264 | |
1044 | =item int ev_priority (ev_TYPE *watcher) |
1265 | =item int ev_priority (ev_TYPE *watcher) |
1045 | |
1266 | |
1046 | Set and query the priority of the watcher. The priority is a small |
1267 | Set and query the priority of the watcher. The priority is a small |
1047 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1268 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1048 | (default: C<-2>). Pending watchers with higher priority will be invoked |
1269 | (default: C<-2>). Pending watchers with higher priority will be invoked |
1049 | before watchers with lower priority, but priority will not keep watchers |
1270 | before watchers with lower priority, but priority will not keep watchers |
1050 | from being executed (except for C<ev_idle> watchers). |
1271 | from being executed (except for C<ev_idle> watchers). |
1051 | |
1272 | |
1052 | This means that priorities are I<only> used for ordering callback |
|
|
1053 | invocation after new events have been received. This is useful, for |
|
|
1054 | example, to reduce latency after idling, or more often, to bind two |
|
|
1055 | watchers on the same event and make sure one is called first. |
|
|
1056 | |
|
|
1057 | If you need to suppress invocation when higher priority events are pending |
1273 | If you need to suppress invocation when higher priority events are pending |
1058 | you need to look at C<ev_idle> watchers, which provide this functionality. |
1274 | you need to look at C<ev_idle> watchers, which provide this functionality. |
1059 | |
1275 | |
1060 | You I<must not> change the priority of a watcher as long as it is active or |
1276 | You I<must not> change the priority of a watcher as long as it is active or |
1061 | pending. |
1277 | pending. |
1062 | |
|
|
1063 | The default priority used by watchers when no priority has been set is |
|
|
1064 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
1065 | |
1278 | |
1066 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
1279 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
1067 | fine, as long as you do not mind that the priority value you query might |
1280 | fine, as long as you do not mind that the priority value you query might |
1068 | or might not have been clamped to the valid range. |
1281 | or might not have been clamped to the valid range. |
|
|
1282 | |
|
|
1283 | The default priority used by watchers when no priority has been set is |
|
|
1284 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
1285 | |
|
|
1286 | See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
|
|
1287 | priorities. |
1069 | |
1288 | |
1070 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1289 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1071 | |
1290 | |
1072 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1291 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1073 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
1292 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
… | |
… | |
1081 | watcher isn't pending it does nothing and returns C<0>. |
1300 | watcher isn't pending it does nothing and returns C<0>. |
1082 | |
1301 | |
1083 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1302 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1084 | callback to be invoked, which can be accomplished with this function. |
1303 | callback to be invoked, which can be accomplished with this function. |
1085 | |
1304 | |
|
|
1305 | =item ev_feed_event (loop, ev_TYPE *watcher, int revents) |
|
|
1306 | |
|
|
1307 | Feeds the given event set into the event loop, as if the specified event |
|
|
1308 | had happened for the specified watcher (which must be a pointer to an |
|
|
1309 | initialised but not necessarily started event watcher). Obviously you must |
|
|
1310 | not free the watcher as long as it has pending events. |
|
|
1311 | |
|
|
1312 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1313 | C<ev_clear_pending> will clear the pending event, even if the watcher was |
|
|
1314 | not started in the first place. |
|
|
1315 | |
|
|
1316 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
|
|
1317 | functions that do not need a watcher. |
|
|
1318 | |
1086 | =back |
1319 | =back |
1087 | |
|
|
1088 | |
1320 | |
1089 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1321 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1090 | |
1322 | |
1091 | Each watcher has, by default, a member C<void *data> that you can change |
1323 | Each watcher has, by default, a member C<void *data> that you can change |
1092 | and read at any time: libev will completely ignore it. This can be used |
1324 | and read at any time: libev will completely ignore it. This can be used |
… | |
… | |
1138 | #include <stddef.h> |
1370 | #include <stddef.h> |
1139 | |
1371 | |
1140 | static void |
1372 | static void |
1141 | t1_cb (EV_P_ ev_timer *w, int revents) |
1373 | t1_cb (EV_P_ ev_timer *w, int revents) |
1142 | { |
1374 | { |
1143 | struct my_biggy big = (struct my_biggy * |
1375 | struct my_biggy big = (struct my_biggy *) |
1144 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1376 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1145 | } |
1377 | } |
1146 | |
1378 | |
1147 | static void |
1379 | static void |
1148 | t2_cb (EV_P_ ev_timer *w, int revents) |
1380 | t2_cb (EV_P_ ev_timer *w, int revents) |
1149 | { |
1381 | { |
1150 | struct my_biggy big = (struct my_biggy * |
1382 | struct my_biggy big = (struct my_biggy *) |
1151 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1383 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1152 | } |
1384 | } |
|
|
1385 | |
|
|
1386 | =head2 WATCHER STATES |
|
|
1387 | |
|
|
1388 | There are various watcher states mentioned throughout this manual - |
|
|
1389 | active, pending and so on. In this section these states and the rules to |
|
|
1390 | transition between them will be described in more detail - and while these |
|
|
1391 | rules might look complicated, they usually do "the right thing". |
|
|
1392 | |
|
|
1393 | =over 4 |
|
|
1394 | |
|
|
1395 | =item initialiased |
|
|
1396 | |
|
|
1397 | Before a watcher can be registered with the event looop it has to be |
|
|
1398 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1399 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
|
|
1400 | |
|
|
1401 | In this state it is simply some block of memory that is suitable for use |
|
|
1402 | in an event loop. It can be moved around, freed, reused etc. at will. |
|
|
1403 | |
|
|
1404 | =item started/running/active |
|
|
1405 | |
|
|
1406 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
|
|
1407 | property of the event loop, and is actively waiting for events. While in |
|
|
1408 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1409 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1410 | and call libev functions on it that are documented to work on active watchers. |
|
|
1411 | |
|
|
1412 | =item pending |
|
|
1413 | |
|
|
1414 | If a watcher is active and libev determines that an event it is interested |
|
|
1415 | in has occurred (such as a timer expiring), it will become pending. It will |
|
|
1416 | stay in this pending state until either it is stopped or its callback is |
|
|
1417 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1418 | callback. |
|
|
1419 | |
|
|
1420 | The watcher might or might not be active while it is pending (for example, |
|
|
1421 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1422 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1423 | but it is still property of the event loop at this time, so cannot be |
|
|
1424 | moved, freed or reused. And if it is active the rules described in the |
|
|
1425 | previous item still apply. |
|
|
1426 | |
|
|
1427 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1428 | via C<ev_feed_event>), in which case it becomes pending without being |
|
|
1429 | active. |
|
|
1430 | |
|
|
1431 | =item stopped |
|
|
1432 | |
|
|
1433 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1434 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
|
|
1435 | latter will clear any pending state the watcher might be in, regardless |
|
|
1436 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1437 | freeing it is often a good idea. |
|
|
1438 | |
|
|
1439 | While stopped (and not pending) the watcher is essentially in the |
|
|
1440 | initialised state, that is it can be reused, moved, modified in any way |
|
|
1441 | you wish. |
|
|
1442 | |
|
|
1443 | =back |
|
|
1444 | |
|
|
1445 | =head2 WATCHER PRIORITY MODELS |
|
|
1446 | |
|
|
1447 | Many event loops support I<watcher priorities>, which are usually small |
|
|
1448 | integers that influence the ordering of event callback invocation |
|
|
1449 | between watchers in some way, all else being equal. |
|
|
1450 | |
|
|
1451 | In libev, Watcher priorities can be set using C<ev_set_priority>. See its |
|
|
1452 | description for the more technical details such as the actual priority |
|
|
1453 | range. |
|
|
1454 | |
|
|
1455 | There are two common ways how these these priorities are being interpreted |
|
|
1456 | by event loops: |
|
|
1457 | |
|
|
1458 | In the more common lock-out model, higher priorities "lock out" invocation |
|
|
1459 | of lower priority watchers, which means as long as higher priority |
|
|
1460 | watchers receive events, lower priority watchers are not being invoked. |
|
|
1461 | |
|
|
1462 | The less common only-for-ordering model uses priorities solely to order |
|
|
1463 | callback invocation within a single event loop iteration: Higher priority |
|
|
1464 | watchers are invoked before lower priority ones, but they all get invoked |
|
|
1465 | before polling for new events. |
|
|
1466 | |
|
|
1467 | Libev uses the second (only-for-ordering) model for all its watchers |
|
|
1468 | except for idle watchers (which use the lock-out model). |
|
|
1469 | |
|
|
1470 | The rationale behind this is that implementing the lock-out model for |
|
|
1471 | watchers is not well supported by most kernel interfaces, and most event |
|
|
1472 | libraries will just poll for the same events again and again as long as |
|
|
1473 | their callbacks have not been executed, which is very inefficient in the |
|
|
1474 | common case of one high-priority watcher locking out a mass of lower |
|
|
1475 | priority ones. |
|
|
1476 | |
|
|
1477 | Static (ordering) priorities are most useful when you have two or more |
|
|
1478 | watchers handling the same resource: a typical usage example is having an |
|
|
1479 | C<ev_io> watcher to receive data, and an associated C<ev_timer> to handle |
|
|
1480 | timeouts. Under load, data might be received while the program handles |
|
|
1481 | other jobs, but since timers normally get invoked first, the timeout |
|
|
1482 | handler will be executed before checking for data. In that case, giving |
|
|
1483 | the timer a lower priority than the I/O watcher ensures that I/O will be |
|
|
1484 | handled first even under adverse conditions (which is usually, but not |
|
|
1485 | always, what you want). |
|
|
1486 | |
|
|
1487 | Since idle watchers use the "lock-out" model, meaning that idle watchers |
|
|
1488 | will only be executed when no same or higher priority watchers have |
|
|
1489 | received events, they can be used to implement the "lock-out" model when |
|
|
1490 | required. |
|
|
1491 | |
|
|
1492 | For example, to emulate how many other event libraries handle priorities, |
|
|
1493 | you can associate an C<ev_idle> watcher to each such watcher, and in |
|
|
1494 | the normal watcher callback, you just start the idle watcher. The real |
|
|
1495 | processing is done in the idle watcher callback. This causes libev to |
|
|
1496 | continuously poll and process kernel event data for the watcher, but when |
|
|
1497 | the lock-out case is known to be rare (which in turn is rare :), this is |
|
|
1498 | workable. |
|
|
1499 | |
|
|
1500 | Usually, however, the lock-out model implemented that way will perform |
|
|
1501 | miserably under the type of load it was designed to handle. In that case, |
|
|
1502 | it might be preferable to stop the real watcher before starting the |
|
|
1503 | idle watcher, so the kernel will not have to process the event in case |
|
|
1504 | the actual processing will be delayed for considerable time. |
|
|
1505 | |
|
|
1506 | Here is an example of an I/O watcher that should run at a strictly lower |
|
|
1507 | priority than the default, and which should only process data when no |
|
|
1508 | other events are pending: |
|
|
1509 | |
|
|
1510 | ev_idle idle; // actual processing watcher |
|
|
1511 | ev_io io; // actual event watcher |
|
|
1512 | |
|
|
1513 | static void |
|
|
1514 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1515 | { |
|
|
1516 | // stop the I/O watcher, we received the event, but |
|
|
1517 | // are not yet ready to handle it. |
|
|
1518 | ev_io_stop (EV_A_ w); |
|
|
1519 | |
|
|
1520 | // start the idle watcher to handle the actual event. |
|
|
1521 | // it will not be executed as long as other watchers |
|
|
1522 | // with the default priority are receiving events. |
|
|
1523 | ev_idle_start (EV_A_ &idle); |
|
|
1524 | } |
|
|
1525 | |
|
|
1526 | static void |
|
|
1527 | idle_cb (EV_P_ ev_idle *w, int revents) |
|
|
1528 | { |
|
|
1529 | // actual processing |
|
|
1530 | read (STDIN_FILENO, ...); |
|
|
1531 | |
|
|
1532 | // have to start the I/O watcher again, as |
|
|
1533 | // we have handled the event |
|
|
1534 | ev_io_start (EV_P_ &io); |
|
|
1535 | } |
|
|
1536 | |
|
|
1537 | // initialisation |
|
|
1538 | ev_idle_init (&idle, idle_cb); |
|
|
1539 | ev_io_init (&io, io_cb, STDIN_FILENO, EV_READ); |
|
|
1540 | ev_io_start (EV_DEFAULT_ &io); |
|
|
1541 | |
|
|
1542 | In the "real" world, it might also be beneficial to start a timer, so that |
|
|
1543 | low-priority connections can not be locked out forever under load. This |
|
|
1544 | enables your program to keep a lower latency for important connections |
|
|
1545 | during short periods of high load, while not completely locking out less |
|
|
1546 | important ones. |
1153 | |
1547 | |
1154 | |
1548 | |
1155 | =head1 WATCHER TYPES |
1549 | =head1 WATCHER TYPES |
1156 | |
1550 | |
1157 | This section describes each watcher in detail, but will not repeat |
1551 | This section describes each watcher in detail, but will not repeat |
… | |
… | |
1183 | descriptors to non-blocking mode is also usually a good idea (but not |
1577 | descriptors to non-blocking mode is also usually a good idea (but not |
1184 | required if you know what you are doing). |
1578 | required if you know what you are doing). |
1185 | |
1579 | |
1186 | If you cannot use non-blocking mode, then force the use of a |
1580 | If you cannot use non-blocking mode, then force the use of a |
1187 | known-to-be-good backend (at the time of this writing, this includes only |
1581 | known-to-be-good backend (at the time of this writing, this includes only |
1188 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). |
1582 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
|
|
1583 | descriptors for which non-blocking operation makes no sense (such as |
|
|
1584 | files) - libev doesn't guarantee any specific behaviour in that case. |
1189 | |
1585 | |
1190 | Another thing you have to watch out for is that it is quite easy to |
1586 | Another thing you have to watch out for is that it is quite easy to |
1191 | receive "spurious" readiness notifications, that is your callback might |
1587 | receive "spurious" readiness notifications, that is your callback might |
1192 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1588 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1193 | because there is no data. Not only are some backends known to create a |
1589 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1258 | |
1654 | |
1259 | So when you encounter spurious, unexplained daemon exits, make sure you |
1655 | So when you encounter spurious, unexplained daemon exits, make sure you |
1260 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1656 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1261 | somewhere, as that would have given you a big clue). |
1657 | somewhere, as that would have given you a big clue). |
1262 | |
1658 | |
|
|
1659 | =head3 The special problem of accept()ing when you can't |
|
|
1660 | |
|
|
1661 | Many implementations of the POSIX C<accept> function (for example, |
|
|
1662 | found in post-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1663 | connection from the pending queue in all error cases. |
|
|
1664 | |
|
|
1665 | For example, larger servers often run out of file descriptors (because |
|
|
1666 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
|
|
1667 | rejecting the connection, leading to libev signalling readiness on |
|
|
1668 | the next iteration again (the connection still exists after all), and |
|
|
1669 | typically causing the program to loop at 100% CPU usage. |
|
|
1670 | |
|
|
1671 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1672 | operating systems, there is usually little the app can do to remedy the |
|
|
1673 | situation, and no known thread-safe method of removing the connection to |
|
|
1674 | cope with overload is known (to me). |
|
|
1675 | |
|
|
1676 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1677 | - when the program encounters an overload, it will just loop until the |
|
|
1678 | situation is over. While this is a form of busy waiting, no OS offers an |
|
|
1679 | event-based way to handle this situation, so it's the best one can do. |
|
|
1680 | |
|
|
1681 | A better way to handle the situation is to log any errors other than |
|
|
1682 | C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such |
|
|
1683 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1684 | what could be wrong ("raise the ulimit!"). For extra points one could stop |
|
|
1685 | the C<ev_io> watcher on the listening fd "for a while", which reduces CPU |
|
|
1686 | usage. |
|
|
1687 | |
|
|
1688 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1689 | descriptor for overload situations (e.g. by opening F</dev/null>), and |
|
|
1690 | when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>, |
|
|
1691 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1692 | clients under typical overload conditions. |
|
|
1693 | |
|
|
1694 | The last way to handle it is to simply log the error and C<exit>, as |
|
|
1695 | is often done with C<malloc> failures, but this results in an easy |
|
|
1696 | opportunity for a DoS attack. |
1263 | |
1697 | |
1264 | =head3 Watcher-Specific Functions |
1698 | =head3 Watcher-Specific Functions |
1265 | |
1699 | |
1266 | =over 4 |
1700 | =over 4 |
1267 | |
1701 | |
… | |
… | |
1299 | ... |
1733 | ... |
1300 | struct ev_loop *loop = ev_default_init (0); |
1734 | struct ev_loop *loop = ev_default_init (0); |
1301 | ev_io stdin_readable; |
1735 | ev_io stdin_readable; |
1302 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1736 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1303 | ev_io_start (loop, &stdin_readable); |
1737 | ev_io_start (loop, &stdin_readable); |
1304 | ev_loop (loop, 0); |
1738 | ev_run (loop, 0); |
1305 | |
1739 | |
1306 | |
1740 | |
1307 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1741 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1308 | |
1742 | |
1309 | Timer watchers are simple relative timers that generate an event after a |
1743 | Timer watchers are simple relative timers that generate an event after a |
… | |
… | |
1314 | year, it will still time out after (roughly) one hour. "Roughly" because |
1748 | year, it will still time out after (roughly) one hour. "Roughly" because |
1315 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1749 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1316 | monotonic clock option helps a lot here). |
1750 | monotonic clock option helps a lot here). |
1317 | |
1751 | |
1318 | The callback is guaranteed to be invoked only I<after> its timeout has |
1752 | The callback is guaranteed to be invoked only I<after> its timeout has |
1319 | passed, but if multiple timers become ready during the same loop iteration |
1753 | passed (not I<at>, so on systems with very low-resolution clocks this |
1320 | then order of execution is undefined. |
1754 | might introduce a small delay). If multiple timers become ready during the |
|
|
1755 | same loop iteration then the ones with earlier time-out values are invoked |
|
|
1756 | before ones of the same priority with later time-out values (but this is |
|
|
1757 | no longer true when a callback calls C<ev_run> recursively). |
1321 | |
1758 | |
1322 | =head3 Be smart about timeouts |
1759 | =head3 Be smart about timeouts |
1323 | |
1760 | |
1324 | Many real-world problems involve some kind of timeout, usually for error |
1761 | Many real-world problems involve some kind of timeout, usually for error |
1325 | recovery. A typical example is an HTTP request - if the other side hangs, |
1762 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
1369 | C<after> argument to C<ev_timer_set>, and only ever use the C<repeat> |
1806 | C<after> argument to C<ev_timer_set>, and only ever use the C<repeat> |
1370 | member and C<ev_timer_again>. |
1807 | member and C<ev_timer_again>. |
1371 | |
1808 | |
1372 | At start: |
1809 | At start: |
1373 | |
1810 | |
1374 | ev_timer_init (timer, callback); |
1811 | ev_init (timer, callback); |
1375 | timer->repeat = 60.; |
1812 | timer->repeat = 60.; |
1376 | ev_timer_again (loop, timer); |
1813 | ev_timer_again (loop, timer); |
1377 | |
1814 | |
1378 | Each time there is some activity: |
1815 | Each time there is some activity: |
1379 | |
1816 | |
… | |
… | |
1411 | ev_tstamp timeout = last_activity + 60.; |
1848 | ev_tstamp timeout = last_activity + 60.; |
1412 | |
1849 | |
1413 | // if last_activity + 60. is older than now, we did time out |
1850 | // if last_activity + 60. is older than now, we did time out |
1414 | if (timeout < now) |
1851 | if (timeout < now) |
1415 | { |
1852 | { |
1416 | // timeout occured, take action |
1853 | // timeout occurred, take action |
1417 | } |
1854 | } |
1418 | else |
1855 | else |
1419 | { |
1856 | { |
1420 | // callback was invoked, but there was some activity, re-arm |
1857 | // callback was invoked, but there was some activity, re-arm |
1421 | // the watcher to fire in last_activity + 60, which is |
1858 | // the watcher to fire in last_activity + 60, which is |
1422 | // guaranteed to be in the future, so "again" is positive: |
1859 | // guaranteed to be in the future, so "again" is positive: |
1423 | w->again = timeout - now; |
1860 | w->repeat = timeout - now; |
1424 | ev_timer_again (EV_A_ w); |
1861 | ev_timer_again (EV_A_ w); |
1425 | } |
1862 | } |
1426 | } |
1863 | } |
1427 | |
1864 | |
1428 | To summarise the callback: first calculate the real timeout (defined |
1865 | To summarise the callback: first calculate the real timeout (defined |
… | |
… | |
1441 | |
1878 | |
1442 | To start the timer, simply initialise the watcher and set C<last_activity> |
1879 | To start the timer, simply initialise the watcher and set C<last_activity> |
1443 | to the current time (meaning we just have some activity :), then call the |
1880 | to the current time (meaning we just have some activity :), then call the |
1444 | callback, which will "do the right thing" and start the timer: |
1881 | callback, which will "do the right thing" and start the timer: |
1445 | |
1882 | |
1446 | ev_timer_init (timer, callback); |
1883 | ev_init (timer, callback); |
1447 | last_activity = ev_now (loop); |
1884 | last_activity = ev_now (loop); |
1448 | callback (loop, timer, EV_TIMEOUT); |
1885 | callback (loop, timer, EV_TIMER); |
1449 | |
1886 | |
1450 | And when there is some activity, simply store the current time in |
1887 | And when there is some activity, simply store the current time in |
1451 | C<last_activity>, no libev calls at all: |
1888 | C<last_activity>, no libev calls at all: |
1452 | |
1889 | |
1453 | last_actiivty = ev_now (loop); |
1890 | last_activity = ev_now (loop); |
1454 | |
1891 | |
1455 | This technique is slightly more complex, but in most cases where the |
1892 | This technique is slightly more complex, but in most cases where the |
1456 | time-out is unlikely to be triggered, much more efficient. |
1893 | time-out is unlikely to be triggered, much more efficient. |
1457 | |
1894 | |
1458 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
1895 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
… | |
… | |
1496 | |
1933 | |
1497 | =head3 The special problem of time updates |
1934 | =head3 The special problem of time updates |
1498 | |
1935 | |
1499 | Establishing the current time is a costly operation (it usually takes at |
1936 | Establishing the current time is a costly operation (it usually takes at |
1500 | least two system calls): EV therefore updates its idea of the current |
1937 | least two system calls): EV therefore updates its idea of the current |
1501 | time only before and after C<ev_loop> collects new events, which causes a |
1938 | time only before and after C<ev_run> collects new events, which causes a |
1502 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1939 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1503 | lots of events in one iteration. |
1940 | lots of events in one iteration. |
1504 | |
1941 | |
1505 | The relative timeouts are calculated relative to the C<ev_now ()> |
1942 | The relative timeouts are calculated relative to the C<ev_now ()> |
1506 | time. This is usually the right thing as this timestamp refers to the time |
1943 | time. This is usually the right thing as this timestamp refers to the time |
… | |
… | |
1512 | |
1949 | |
1513 | If the event loop is suspended for a long time, you can also force an |
1950 | If the event loop is suspended for a long time, you can also force an |
1514 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1951 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1515 | ()>. |
1952 | ()>. |
1516 | |
1953 | |
|
|
1954 | =head3 The special problems of suspended animation |
|
|
1955 | |
|
|
1956 | When you leave the server world it is quite customary to hit machines that |
|
|
1957 | can suspend/hibernate - what happens to the clocks during such a suspend? |
|
|
1958 | |
|
|
1959 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
1960 | all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue |
|
|
1961 | to run until the system is suspended, but they will not advance while the |
|
|
1962 | system is suspended. That means, on resume, it will be as if the program |
|
|
1963 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
1964 | towards C<ev_timer> when a monotonic clock source is used. The real time |
|
|
1965 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
1966 | long suspend would be detected as a time jump by libev, and timers would |
|
|
1967 | be adjusted accordingly. |
|
|
1968 | |
|
|
1969 | I would not be surprised to see different behaviour in different between |
|
|
1970 | operating systems, OS versions or even different hardware. |
|
|
1971 | |
|
|
1972 | The other form of suspend (job control, or sending a SIGSTOP) will see a |
|
|
1973 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
1974 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
1975 | then you can expect C<ev_timer>s to expire as the full suspension time |
|
|
1976 | will be counted towards the timers. When no monotonic clock source is in |
|
|
1977 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
1978 | |
|
|
1979 | It might be beneficial for this latter case to call C<ev_suspend> |
|
|
1980 | and C<ev_resume> in code that handles C<SIGTSTP>, to at least get |
|
|
1981 | deterministic behaviour in this case (you can do nothing against |
|
|
1982 | C<SIGSTOP>). |
|
|
1983 | |
1517 | =head3 Watcher-Specific Functions and Data Members |
1984 | =head3 Watcher-Specific Functions and Data Members |
1518 | |
1985 | |
1519 | =over 4 |
1986 | =over 4 |
1520 | |
1987 | |
1521 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1988 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
1544 | If the timer is started but non-repeating, stop it (as if it timed out). |
2011 | If the timer is started but non-repeating, stop it (as if it timed out). |
1545 | |
2012 | |
1546 | If the timer is repeating, either start it if necessary (with the |
2013 | If the timer is repeating, either start it if necessary (with the |
1547 | C<repeat> value), or reset the running timer to the C<repeat> value. |
2014 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1548 | |
2015 | |
1549 | This sounds a bit complicated, see "Be smart about timeouts", above, for a |
2016 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1550 | usage example. |
2017 | usage example. |
|
|
2018 | |
|
|
2019 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
|
|
2020 | |
|
|
2021 | Returns the remaining time until a timer fires. If the timer is active, |
|
|
2022 | then this time is relative to the current event loop time, otherwise it's |
|
|
2023 | the timeout value currently configured. |
|
|
2024 | |
|
|
2025 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
|
|
2026 | C<5>. When the timer is started and one second passes, C<ev_timer_remaining> |
|
|
2027 | will return C<4>. When the timer expires and is restarted, it will return |
|
|
2028 | roughly C<7> (likely slightly less as callback invocation takes some time, |
|
|
2029 | too), and so on. |
1551 | |
2030 | |
1552 | =item ev_tstamp repeat [read-write] |
2031 | =item ev_tstamp repeat [read-write] |
1553 | |
2032 | |
1554 | The current C<repeat> value. Will be used each time the watcher times out |
2033 | The current C<repeat> value. Will be used each time the watcher times out |
1555 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
2034 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
… | |
… | |
1581 | } |
2060 | } |
1582 | |
2061 | |
1583 | ev_timer mytimer; |
2062 | ev_timer mytimer; |
1584 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2063 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1585 | ev_timer_again (&mytimer); /* start timer */ |
2064 | ev_timer_again (&mytimer); /* start timer */ |
1586 | ev_loop (loop, 0); |
2065 | ev_run (loop, 0); |
1587 | |
2066 | |
1588 | // and in some piece of code that gets executed on any "activity": |
2067 | // and in some piece of code that gets executed on any "activity": |
1589 | // reset the timeout to start ticking again at 10 seconds |
2068 | // reset the timeout to start ticking again at 10 seconds |
1590 | ev_timer_again (&mytimer); |
2069 | ev_timer_again (&mytimer); |
1591 | |
2070 | |
… | |
… | |
1593 | =head2 C<ev_periodic> - to cron or not to cron? |
2072 | =head2 C<ev_periodic> - to cron or not to cron? |
1594 | |
2073 | |
1595 | Periodic watchers are also timers of a kind, but they are very versatile |
2074 | Periodic watchers are also timers of a kind, but they are very versatile |
1596 | (and unfortunately a bit complex). |
2075 | (and unfortunately a bit complex). |
1597 | |
2076 | |
1598 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
2077 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
1599 | but on wall clock time (absolute time). You can tell a periodic watcher |
2078 | relative time, the physical time that passes) but on wall clock time |
1600 | to trigger after some specific point in time. For example, if you tell a |
2079 | (absolute time, the thing you can read on your calender or clock). The |
1601 | periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now () |
2080 | difference is that wall clock time can run faster or slower than real |
1602 | + 10.>, that is, an absolute time not a delay) and then reset your system |
2081 | time, and time jumps are not uncommon (e.g. when you adjust your |
1603 | clock to January of the previous year, then it will take more than year |
2082 | wrist-watch). |
1604 | to trigger the event (unlike an C<ev_timer>, which would still trigger |
|
|
1605 | roughly 10 seconds later as it uses a relative timeout). |
|
|
1606 | |
2083 | |
|
|
2084 | You can tell a periodic watcher to trigger after some specific point |
|
|
2085 | in time: for example, if you tell a periodic watcher to trigger "in 10 |
|
|
2086 | seconds" (by specifying e.g. C<ev_now () + 10.>, that is, an absolute time |
|
|
2087 | not a delay) and then reset your system clock to January of the previous |
|
|
2088 | year, then it will take a year or more to trigger the event (unlike an |
|
|
2089 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
|
|
2090 | it, as it uses a relative timeout). |
|
|
2091 | |
1607 | C<ev_periodic>s can also be used to implement vastly more complex timers, |
2092 | C<ev_periodic> watchers can also be used to implement vastly more complex |
1608 | such as triggering an event on each "midnight, local time", or other |
2093 | timers, such as triggering an event on each "midnight, local time", or |
1609 | complicated rules. |
2094 | other complicated rules. This cannot be done with C<ev_timer> watchers, as |
|
|
2095 | those cannot react to time jumps. |
1610 | |
2096 | |
1611 | As with timers, the callback is guaranteed to be invoked only when the |
2097 | As with timers, the callback is guaranteed to be invoked only when the |
1612 | time (C<at>) has passed, but if multiple periodic timers become ready |
2098 | point in time where it is supposed to trigger has passed. If multiple |
1613 | during the same loop iteration, then order of execution is undefined. |
2099 | timers become ready during the same loop iteration then the ones with |
|
|
2100 | earlier time-out values are invoked before ones with later time-out values |
|
|
2101 | (but this is no longer true when a callback calls C<ev_run> recursively). |
1614 | |
2102 | |
1615 | =head3 Watcher-Specific Functions and Data Members |
2103 | =head3 Watcher-Specific Functions and Data Members |
1616 | |
2104 | |
1617 | =over 4 |
2105 | =over 4 |
1618 | |
2106 | |
1619 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
2107 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb) |
1620 | |
2108 | |
1621 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
2109 | =item ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb) |
1622 | |
2110 | |
1623 | Lots of arguments, lets sort it out... There are basically three modes of |
2111 | Lots of arguments, let's sort it out... There are basically three modes of |
1624 | operation, and we will explain them from simplest to most complex: |
2112 | operation, and we will explain them from simplest to most complex: |
1625 | |
2113 | |
1626 | =over 4 |
2114 | =over 4 |
1627 | |
2115 | |
1628 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
2116 | =item * absolute timer (offset = absolute time, interval = 0, reschedule_cb = 0) |
1629 | |
2117 | |
1630 | In this configuration the watcher triggers an event after the wall clock |
2118 | In this configuration the watcher triggers an event after the wall clock |
1631 | time C<at> has passed. It will not repeat and will not adjust when a time |
2119 | time C<offset> has passed. It will not repeat and will not adjust when a |
1632 | jump occurs, that is, if it is to be run at January 1st 2011 then it will |
2120 | time jump occurs, that is, if it is to be run at January 1st 2011 then it |
1633 | only run when the system clock reaches or surpasses this time. |
2121 | will be stopped and invoked when the system clock reaches or surpasses |
|
|
2122 | this point in time. |
1634 | |
2123 | |
1635 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
2124 | =item * repeating interval timer (offset = offset within interval, interval > 0, reschedule_cb = 0) |
1636 | |
2125 | |
1637 | In this mode the watcher will always be scheduled to time out at the next |
2126 | In this mode the watcher will always be scheduled to time out at the next |
1638 | C<at + N * interval> time (for some integer N, which can also be negative) |
2127 | C<offset + N * interval> time (for some integer N, which can also be |
1639 | and then repeat, regardless of any time jumps. |
2128 | negative) and then repeat, regardless of any time jumps. The C<offset> |
|
|
2129 | argument is merely an offset into the C<interval> periods. |
1640 | |
2130 | |
1641 | This can be used to create timers that do not drift with respect to the |
2131 | This can be used to create timers that do not drift with respect to the |
1642 | system clock, for example, here is a C<ev_periodic> that triggers each |
2132 | system clock, for example, here is an C<ev_periodic> that triggers each |
1643 | hour, on the hour: |
2133 | hour, on the hour (with respect to UTC): |
1644 | |
2134 | |
1645 | ev_periodic_set (&periodic, 0., 3600., 0); |
2135 | ev_periodic_set (&periodic, 0., 3600., 0); |
1646 | |
2136 | |
1647 | This doesn't mean there will always be 3600 seconds in between triggers, |
2137 | This doesn't mean there will always be 3600 seconds in between triggers, |
1648 | but only that the callback will be called when the system time shows a |
2138 | but only that the callback will be called when the system time shows a |
1649 | full hour (UTC), or more correctly, when the system time is evenly divisible |
2139 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1650 | by 3600. |
2140 | by 3600. |
1651 | |
2141 | |
1652 | Another way to think about it (for the mathematically inclined) is that |
2142 | Another way to think about it (for the mathematically inclined) is that |
1653 | C<ev_periodic> will try to run the callback in this mode at the next possible |
2143 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1654 | time where C<time = at (mod interval)>, regardless of any time jumps. |
2144 | time where C<time = offset (mod interval)>, regardless of any time jumps. |
1655 | |
2145 | |
1656 | For numerical stability it is preferable that the C<at> value is near |
2146 | For numerical stability it is preferable that the C<offset> value is near |
1657 | C<ev_now ()> (the current time), but there is no range requirement for |
2147 | C<ev_now ()> (the current time), but there is no range requirement for |
1658 | this value, and in fact is often specified as zero. |
2148 | this value, and in fact is often specified as zero. |
1659 | |
2149 | |
1660 | Note also that there is an upper limit to how often a timer can fire (CPU |
2150 | Note also that there is an upper limit to how often a timer can fire (CPU |
1661 | speed for example), so if C<interval> is very small then timing stability |
2151 | speed for example), so if C<interval> is very small then timing stability |
1662 | will of course deteriorate. Libev itself tries to be exact to be about one |
2152 | will of course deteriorate. Libev itself tries to be exact to be about one |
1663 | millisecond (if the OS supports it and the machine is fast enough). |
2153 | millisecond (if the OS supports it and the machine is fast enough). |
1664 | |
2154 | |
1665 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
2155 | =item * manual reschedule mode (offset ignored, interval ignored, reschedule_cb = callback) |
1666 | |
2156 | |
1667 | In this mode the values for C<interval> and C<at> are both being |
2157 | In this mode the values for C<interval> and C<offset> are both being |
1668 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2158 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1669 | reschedule callback will be called with the watcher as first, and the |
2159 | reschedule callback will be called with the watcher as first, and the |
1670 | current time as second argument. |
2160 | current time as second argument. |
1671 | |
2161 | |
1672 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
2162 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, ever, |
1673 | ever, or make ANY event loop modifications whatsoever>. |
2163 | or make ANY other event loop modifications whatsoever, unless explicitly |
|
|
2164 | allowed by documentation here>. |
1674 | |
2165 | |
1675 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
2166 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
1676 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
2167 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
1677 | only event loop modification you are allowed to do). |
2168 | only event loop modification you are allowed to do). |
1678 | |
2169 | |
… | |
… | |
1708 | a different time than the last time it was called (e.g. in a crond like |
2199 | a different time than the last time it was called (e.g. in a crond like |
1709 | program when the crontabs have changed). |
2200 | program when the crontabs have changed). |
1710 | |
2201 | |
1711 | =item ev_tstamp ev_periodic_at (ev_periodic *) |
2202 | =item ev_tstamp ev_periodic_at (ev_periodic *) |
1712 | |
2203 | |
1713 | When active, returns the absolute time that the watcher is supposed to |
2204 | When active, returns the absolute time that the watcher is supposed |
1714 | trigger next. |
2205 | to trigger next. This is not the same as the C<offset> argument to |
|
|
2206 | C<ev_periodic_set>, but indeed works even in interval and manual |
|
|
2207 | rescheduling modes. |
1715 | |
2208 | |
1716 | =item ev_tstamp offset [read-write] |
2209 | =item ev_tstamp offset [read-write] |
1717 | |
2210 | |
1718 | When repeating, this contains the offset value, otherwise this is the |
2211 | When repeating, this contains the offset value, otherwise this is the |
1719 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
2212 | absolute point in time (the C<offset> value passed to C<ev_periodic_set>, |
|
|
2213 | although libev might modify this value for better numerical stability). |
1720 | |
2214 | |
1721 | Can be modified any time, but changes only take effect when the periodic |
2215 | Can be modified any time, but changes only take effect when the periodic |
1722 | timer fires or C<ev_periodic_again> is being called. |
2216 | timer fires or C<ev_periodic_again> is being called. |
1723 | |
2217 | |
1724 | =item ev_tstamp interval [read-write] |
2218 | =item ev_tstamp interval [read-write] |
… | |
… | |
1740 | Example: Call a callback every hour, or, more precisely, whenever the |
2234 | Example: Call a callback every hour, or, more precisely, whenever the |
1741 | system time is divisible by 3600. The callback invocation times have |
2235 | system time is divisible by 3600. The callback invocation times have |
1742 | potentially a lot of jitter, but good long-term stability. |
2236 | potentially a lot of jitter, but good long-term stability. |
1743 | |
2237 | |
1744 | static void |
2238 | static void |
1745 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2239 | clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
1746 | { |
2240 | { |
1747 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2241 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1748 | } |
2242 | } |
1749 | |
2243 | |
1750 | ev_periodic hourly_tick; |
2244 | ev_periodic hourly_tick; |
… | |
… | |
1773 | |
2267 | |
1774 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2268 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
1775 | |
2269 | |
1776 | Signal watchers will trigger an event when the process receives a specific |
2270 | Signal watchers will trigger an event when the process receives a specific |
1777 | signal one or more times. Even though signals are very asynchronous, libev |
2271 | signal one or more times. Even though signals are very asynchronous, libev |
1778 | will try it's best to deliver signals synchronously, i.e. as part of the |
2272 | will try its best to deliver signals synchronously, i.e. as part of the |
1779 | normal event processing, like any other event. |
2273 | normal event processing, like any other event. |
1780 | |
2274 | |
1781 | If you want signals asynchronously, just use C<sigaction> as you would |
2275 | If you want signals to be delivered truly asynchronously, just use |
1782 | do without libev and forget about sharing the signal. You can even use |
2276 | C<sigaction> as you would do without libev and forget about sharing |
1783 | C<ev_async> from a signal handler to synchronously wake up an event loop. |
2277 | the signal. You can even use C<ev_async> from a signal handler to |
|
|
2278 | synchronously wake up an event loop. |
1784 | |
2279 | |
1785 | You can configure as many watchers as you like per signal. Only when the |
2280 | You can configure as many watchers as you like for the same signal, but |
|
|
2281 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
|
|
2282 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
|
|
2283 | C<SIGINT> in both the default loop and another loop at the same time. At |
|
|
2284 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
|
|
2285 | |
1786 | first watcher gets started will libev actually register a signal handler |
2286 | When the first watcher gets started will libev actually register something |
1787 | with the kernel (thus it coexists with your own signal handlers as long as |
2287 | with the kernel (thus it coexists with your own signal handlers as long as |
1788 | you don't register any with libev for the same signal). Similarly, when |
2288 | you don't register any with libev for the same signal). |
1789 | the last signal watcher for a signal is stopped, libev will reset the |
|
|
1790 | signal handler to SIG_DFL (regardless of what it was set to before). |
|
|
1791 | |
2289 | |
1792 | If possible and supported, libev will install its handlers with |
2290 | If possible and supported, libev will install its handlers with |
1793 | C<SA_RESTART> behaviour enabled, so system calls should not be unduly |
2291 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
1794 | interrupted. If you have a problem with system calls getting interrupted by |
2292 | not be unduly interrupted. If you have a problem with system calls getting |
1795 | signals you can block all signals in an C<ev_check> watcher and unblock |
2293 | interrupted by signals you can block all signals in an C<ev_check> watcher |
1796 | them in an C<ev_prepare> watcher. |
2294 | and unblock them in an C<ev_prepare> watcher. |
|
|
2295 | |
|
|
2296 | =head3 The special problem of inheritance over fork/execve/pthread_create |
|
|
2297 | |
|
|
2298 | Both the signal mask (C<sigprocmask>) and the signal disposition |
|
|
2299 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
|
|
2300 | stopping it again), that is, libev might or might not block the signal, |
|
|
2301 | and might or might not set or restore the installed signal handler. |
|
|
2302 | |
|
|
2303 | While this does not matter for the signal disposition (libev never |
|
|
2304 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
|
|
2305 | C<execve>), this matters for the signal mask: many programs do not expect |
|
|
2306 | certain signals to be blocked. |
|
|
2307 | |
|
|
2308 | This means that before calling C<exec> (from the child) you should reset |
|
|
2309 | the signal mask to whatever "default" you expect (all clear is a good |
|
|
2310 | choice usually). |
|
|
2311 | |
|
|
2312 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2313 | to install a fork handler with C<pthread_atfork> that resets it. That will |
|
|
2314 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2315 | |
|
|
2316 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2317 | unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces |
|
|
2318 | the window of opportunity for problems, it will not go away, as libev |
|
|
2319 | I<has> to modify the signal mask, at least temporarily. |
|
|
2320 | |
|
|
2321 | So I can't stress this enough: I<If you do not reset your signal mask when |
|
|
2322 | you expect it to be empty, you have a race condition in your code>. This |
|
|
2323 | is not a libev-specific thing, this is true for most event libraries. |
1797 | |
2324 | |
1798 | =head3 Watcher-Specific Functions and Data Members |
2325 | =head3 Watcher-Specific Functions and Data Members |
1799 | |
2326 | |
1800 | =over 4 |
2327 | =over 4 |
1801 | |
2328 | |
… | |
… | |
1817 | Example: Try to exit cleanly on SIGINT. |
2344 | Example: Try to exit cleanly on SIGINT. |
1818 | |
2345 | |
1819 | static void |
2346 | static void |
1820 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2347 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
1821 | { |
2348 | { |
1822 | ev_unloop (loop, EVUNLOOP_ALL); |
2349 | ev_break (loop, EVBREAK_ALL); |
1823 | } |
2350 | } |
1824 | |
2351 | |
1825 | ev_signal signal_watcher; |
2352 | ev_signal signal_watcher; |
1826 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2353 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1827 | ev_signal_start (loop, &signal_watcher); |
2354 | ev_signal_start (loop, &signal_watcher); |
… | |
… | |
1833 | some child status changes (most typically when a child of yours dies or |
2360 | some child status changes (most typically when a child of yours dies or |
1834 | exits). It is permissible to install a child watcher I<after> the child |
2361 | exits). It is permissible to install a child watcher I<after> the child |
1835 | has been forked (which implies it might have already exited), as long |
2362 | has been forked (which implies it might have already exited), as long |
1836 | as the event loop isn't entered (or is continued from a watcher), i.e., |
2363 | as the event loop isn't entered (or is continued from a watcher), i.e., |
1837 | forking and then immediately registering a watcher for the child is fine, |
2364 | forking and then immediately registering a watcher for the child is fine, |
1838 | but forking and registering a watcher a few event loop iterations later is |
2365 | but forking and registering a watcher a few event loop iterations later or |
1839 | not. |
2366 | in the next callback invocation is not. |
1840 | |
2367 | |
1841 | Only the default event loop is capable of handling signals, and therefore |
2368 | Only the default event loop is capable of handling signals, and therefore |
1842 | you can only register child watchers in the default event loop. |
2369 | you can only register child watchers in the default event loop. |
1843 | |
2370 | |
|
|
2371 | Due to some design glitches inside libev, child watchers will always be |
|
|
2372 | handled at maximum priority (their priority is set to C<EV_MAXPRI> by |
|
|
2373 | libev) |
|
|
2374 | |
1844 | =head3 Process Interaction |
2375 | =head3 Process Interaction |
1845 | |
2376 | |
1846 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2377 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
1847 | initialised. This is necessary to guarantee proper behaviour even if |
2378 | initialised. This is necessary to guarantee proper behaviour even if the |
1848 | the first child watcher is started after the child exits. The occurrence |
2379 | first child watcher is started after the child exits. The occurrence |
1849 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2380 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
1850 | synchronously as part of the event loop processing. Libev always reaps all |
2381 | synchronously as part of the event loop processing. Libev always reaps all |
1851 | children, even ones not watched. |
2382 | children, even ones not watched. |
1852 | |
2383 | |
1853 | =head3 Overriding the Built-In Processing |
2384 | =head3 Overriding the Built-In Processing |
… | |
… | |
1863 | =head3 Stopping the Child Watcher |
2394 | =head3 Stopping the Child Watcher |
1864 | |
2395 | |
1865 | Currently, the child watcher never gets stopped, even when the |
2396 | Currently, the child watcher never gets stopped, even when the |
1866 | child terminates, so normally one needs to stop the watcher in the |
2397 | child terminates, so normally one needs to stop the watcher in the |
1867 | callback. Future versions of libev might stop the watcher automatically |
2398 | callback. Future versions of libev might stop the watcher automatically |
1868 | when a child exit is detected. |
2399 | when a child exit is detected (calling C<ev_child_stop> twice is not a |
|
|
2400 | problem). |
1869 | |
2401 | |
1870 | =head3 Watcher-Specific Functions and Data Members |
2402 | =head3 Watcher-Specific Functions and Data Members |
1871 | |
2403 | |
1872 | =over 4 |
2404 | =over 4 |
1873 | |
2405 | |
… | |
… | |
2009 | the process. The exception are C<ev_stat> watchers - those call C<stat |
2541 | the process. The exception are C<ev_stat> watchers - those call C<stat |
2010 | ()>, which is a synchronous operation. |
2542 | ()>, which is a synchronous operation. |
2011 | |
2543 | |
2012 | For local paths, this usually doesn't matter: unless the system is very |
2544 | For local paths, this usually doesn't matter: unless the system is very |
2013 | busy or the intervals between stat's are large, a stat call will be fast, |
2545 | busy or the intervals between stat's are large, a stat call will be fast, |
2014 | as the path data is suually in memory already (except when starting the |
2546 | as the path data is usually in memory already (except when starting the |
2015 | watcher). |
2547 | watcher). |
2016 | |
2548 | |
2017 | For networked file systems, calling C<stat ()> can block an indefinite |
2549 | For networked file systems, calling C<stat ()> can block an indefinite |
2018 | time due to network issues, and even under good conditions, a stat call |
2550 | time due to network issues, and even under good conditions, a stat call |
2019 | often takes multiple milliseconds. |
2551 | often takes multiple milliseconds. |
… | |
… | |
2176 | |
2708 | |
2177 | =head3 Watcher-Specific Functions and Data Members |
2709 | =head3 Watcher-Specific Functions and Data Members |
2178 | |
2710 | |
2179 | =over 4 |
2711 | =over 4 |
2180 | |
2712 | |
2181 | =item ev_idle_init (ev_signal *, callback) |
2713 | =item ev_idle_init (ev_idle *, callback) |
2182 | |
2714 | |
2183 | Initialises and configures the idle watcher - it has no parameters of any |
2715 | Initialises and configures the idle watcher - it has no parameters of any |
2184 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
2716 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
2185 | believe me. |
2717 | believe me. |
2186 | |
2718 | |
… | |
… | |
2199 | // no longer anything immediate to do. |
2731 | // no longer anything immediate to do. |
2200 | } |
2732 | } |
2201 | |
2733 | |
2202 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2734 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2203 | ev_idle_init (idle_watcher, idle_cb); |
2735 | ev_idle_init (idle_watcher, idle_cb); |
2204 | ev_idle_start (loop, idle_cb); |
2736 | ev_idle_start (loop, idle_watcher); |
2205 | |
2737 | |
2206 | |
2738 | |
2207 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2739 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2208 | |
2740 | |
2209 | Prepare and check watchers are usually (but not always) used in pairs: |
2741 | Prepare and check watchers are usually (but not always) used in pairs: |
2210 | prepare watchers get invoked before the process blocks and check watchers |
2742 | prepare watchers get invoked before the process blocks and check watchers |
2211 | afterwards. |
2743 | afterwards. |
2212 | |
2744 | |
2213 | You I<must not> call C<ev_loop> or similar functions that enter |
2745 | You I<must not> call C<ev_run> or similar functions that enter |
2214 | the current event loop from either C<ev_prepare> or C<ev_check> |
2746 | the current event loop from either C<ev_prepare> or C<ev_check> |
2215 | watchers. Other loops than the current one are fine, however. The |
2747 | watchers. Other loops than the current one are fine, however. The |
2216 | rationale behind this is that you do not need to check for recursion in |
2748 | rationale behind this is that you do not need to check for recursion in |
2217 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2749 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2218 | C<ev_check> so if you have one watcher of each kind they will always be |
2750 | C<ev_check> so if you have one watcher of each kind they will always be |
… | |
… | |
2302 | struct pollfd fds [nfd]; |
2834 | struct pollfd fds [nfd]; |
2303 | // actual code will need to loop here and realloc etc. |
2835 | // actual code will need to loop here and realloc etc. |
2304 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2836 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2305 | |
2837 | |
2306 | /* the callback is illegal, but won't be called as we stop during check */ |
2838 | /* the callback is illegal, but won't be called as we stop during check */ |
2307 | ev_timer_init (&tw, 0, timeout * 1e-3); |
2839 | ev_timer_init (&tw, 0, timeout * 1e-3, 0.); |
2308 | ev_timer_start (loop, &tw); |
2840 | ev_timer_start (loop, &tw); |
2309 | |
2841 | |
2310 | // create one ev_io per pollfd |
2842 | // create one ev_io per pollfd |
2311 | for (int i = 0; i < nfd; ++i) |
2843 | for (int i = 0; i < nfd; ++i) |
2312 | { |
2844 | { |
… | |
… | |
2386 | |
2918 | |
2387 | if (timeout >= 0) |
2919 | if (timeout >= 0) |
2388 | // create/start timer |
2920 | // create/start timer |
2389 | |
2921 | |
2390 | // poll |
2922 | // poll |
2391 | ev_loop (EV_A_ 0); |
2923 | ev_run (EV_A_ 0); |
2392 | |
2924 | |
2393 | // stop timer again |
2925 | // stop timer again |
2394 | if (timeout >= 0) |
2926 | if (timeout >= 0) |
2395 | ev_timer_stop (EV_A_ &to); |
2927 | ev_timer_stop (EV_A_ &to); |
2396 | |
2928 | |
… | |
… | |
2425 | some fds have to be watched and handled very quickly (with low latency), |
2957 | some fds have to be watched and handled very quickly (with low latency), |
2426 | and even priorities and idle watchers might have too much overhead. In |
2958 | and even priorities and idle watchers might have too much overhead. In |
2427 | this case you would put all the high priority stuff in one loop and all |
2959 | this case you would put all the high priority stuff in one loop and all |
2428 | the rest in a second one, and embed the second one in the first. |
2960 | the rest in a second one, and embed the second one in the first. |
2429 | |
2961 | |
2430 | As long as the watcher is active, the callback will be invoked every time |
2962 | As long as the watcher is active, the callback will be invoked every |
2431 | there might be events pending in the embedded loop. The callback must then |
2963 | time there might be events pending in the embedded loop. The callback |
2432 | call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke |
2964 | must then call C<ev_embed_sweep (mainloop, watcher)> to make a single |
2433 | their callbacks (you could also start an idle watcher to give the embedded |
2965 | sweep and invoke their callbacks (the callback doesn't need to invoke the |
2434 | loop strictly lower priority for example). You can also set the callback |
2966 | C<ev_embed_sweep> function directly, it could also start an idle watcher |
2435 | to C<0>, in which case the embed watcher will automatically execute the |
2967 | to give the embedded loop strictly lower priority for example). |
2436 | embedded loop sweep. |
|
|
2437 | |
2968 | |
2438 | As long as the watcher is started it will automatically handle events. The |
2969 | You can also set the callback to C<0>, in which case the embed watcher |
2439 | callback will be invoked whenever some events have been handled. You can |
2970 | will automatically execute the embedded loop sweep whenever necessary. |
2440 | set the callback to C<0> to avoid having to specify one if you are not |
|
|
2441 | interested in that. |
|
|
2442 | |
2971 | |
2443 | Also, there have not currently been made special provisions for forking: |
2972 | Fork detection will be handled transparently while the C<ev_embed> watcher |
2444 | when you fork, you not only have to call C<ev_loop_fork> on both loops, |
2973 | is active, i.e., the embedded loop will automatically be forked when the |
2445 | but you will also have to stop and restart any C<ev_embed> watchers |
2974 | embedding loop forks. In other cases, the user is responsible for calling |
2446 | yourself - but you can use a fork watcher to handle this automatically, |
2975 | C<ev_loop_fork> on the embedded loop. |
2447 | and future versions of libev might do just that. |
|
|
2448 | |
2976 | |
2449 | Unfortunately, not all backends are embeddable: only the ones returned by |
2977 | Unfortunately, not all backends are embeddable: only the ones returned by |
2450 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2978 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2451 | portable one. |
2979 | portable one. |
2452 | |
2980 | |
… | |
… | |
2478 | if you do not want that, you need to temporarily stop the embed watcher). |
3006 | if you do not want that, you need to temporarily stop the embed watcher). |
2479 | |
3007 | |
2480 | =item ev_embed_sweep (loop, ev_embed *) |
3008 | =item ev_embed_sweep (loop, ev_embed *) |
2481 | |
3009 | |
2482 | Make a single, non-blocking sweep over the embedded loop. This works |
3010 | Make a single, non-blocking sweep over the embedded loop. This works |
2483 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
3011 | similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most |
2484 | appropriate way for embedded loops. |
3012 | appropriate way for embedded loops. |
2485 | |
3013 | |
2486 | =item struct ev_loop *other [read-only] |
3014 | =item struct ev_loop *other [read-only] |
2487 | |
3015 | |
2488 | The embedded event loop. |
3016 | The embedded event loop. |
… | |
… | |
2546 | event loop blocks next and before C<ev_check> watchers are being called, |
3074 | event loop blocks next and before C<ev_check> watchers are being called, |
2547 | and only in the child after the fork. If whoever good citizen calling |
3075 | and only in the child after the fork. If whoever good citizen calling |
2548 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3076 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2549 | handlers will be invoked, too, of course. |
3077 | handlers will be invoked, too, of course. |
2550 | |
3078 | |
|
|
3079 | =head3 The special problem of life after fork - how is it possible? |
|
|
3080 | |
|
|
3081 | Most uses of C<fork()> consist of forking, then some simple calls to set |
|
|
3082 | up/change the process environment, followed by a call to C<exec()>. This |
|
|
3083 | sequence should be handled by libev without any problems. |
|
|
3084 | |
|
|
3085 | This changes when the application actually wants to do event handling |
|
|
3086 | in the child, or both parent in child, in effect "continuing" after the |
|
|
3087 | fork. |
|
|
3088 | |
|
|
3089 | The default mode of operation (for libev, with application help to detect |
|
|
3090 | forks) is to duplicate all the state in the child, as would be expected |
|
|
3091 | when I<either> the parent I<or> the child process continues. |
|
|
3092 | |
|
|
3093 | When both processes want to continue using libev, then this is usually the |
|
|
3094 | wrong result. In that case, usually one process (typically the parent) is |
|
|
3095 | supposed to continue with all watchers in place as before, while the other |
|
|
3096 | process typically wants to start fresh, i.e. without any active watchers. |
|
|
3097 | |
|
|
3098 | The cleanest and most efficient way to achieve that with libev is to |
|
|
3099 | simply create a new event loop, which of course will be "empty", and |
|
|
3100 | use that for new watchers. This has the advantage of not touching more |
|
|
3101 | memory than necessary, and thus avoiding the copy-on-write, and the |
|
|
3102 | disadvantage of having to use multiple event loops (which do not support |
|
|
3103 | signal watchers). |
|
|
3104 | |
|
|
3105 | When this is not possible, or you want to use the default loop for |
|
|
3106 | other reasons, then in the process that wants to start "fresh", call |
|
|
3107 | C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>. |
|
|
3108 | Destroying the default loop will "orphan" (not stop) all registered |
|
|
3109 | watchers, so you have to be careful not to execute code that modifies |
|
|
3110 | those watchers. Note also that in that case, you have to re-register any |
|
|
3111 | signal watchers. |
|
|
3112 | |
2551 | =head3 Watcher-Specific Functions and Data Members |
3113 | =head3 Watcher-Specific Functions and Data Members |
2552 | |
3114 | |
2553 | =over 4 |
3115 | =over 4 |
2554 | |
3116 | |
2555 | =item ev_fork_init (ev_signal *, callback) |
3117 | =item ev_fork_init (ev_fork *, callback) |
2556 | |
3118 | |
2557 | Initialises and configures the fork watcher - it has no parameters of any |
3119 | Initialises and configures the fork watcher - it has no parameters of any |
2558 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
3120 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
2559 | believe me. |
3121 | really. |
2560 | |
3122 | |
2561 | =back |
3123 | =back |
2562 | |
3124 | |
2563 | |
3125 | |
|
|
3126 | =head2 C<ev_cleanup> - even the best things end |
|
|
3127 | |
|
|
3128 | Cleanup watchers are called just before the event loop is being destroyed |
|
|
3129 | by a call to C<ev_loop_destroy>. |
|
|
3130 | |
|
|
3131 | While there is no guarantee that the event loop gets destroyed, cleanup |
|
|
3132 | watchers provide a convenient method to install cleanup hooks for your |
|
|
3133 | program, worker threads and so on - you just to make sure to destroy the |
|
|
3134 | loop when you want them to be invoked. |
|
|
3135 | |
|
|
3136 | Cleanup watchers are invoked in the same way as any other watcher. Unlike |
|
|
3137 | all other watchers, they do not keep a reference to the event loop (which |
|
|
3138 | makes a lot of sense if you think about it). Like all other watchers, you |
|
|
3139 | can call libev functions in the callback, except C<ev_cleanup_start>. |
|
|
3140 | |
|
|
3141 | =head3 Watcher-Specific Functions and Data Members |
|
|
3142 | |
|
|
3143 | =over 4 |
|
|
3144 | |
|
|
3145 | =item ev_cleanup_init (ev_cleanup *, callback) |
|
|
3146 | |
|
|
3147 | Initialises and configures the cleanup watcher - it has no parameters of |
|
|
3148 | any kind. There is a C<ev_cleanup_set> macro, but using it is utterly |
|
|
3149 | pointless, I assure you. |
|
|
3150 | |
|
|
3151 | =back |
|
|
3152 | |
|
|
3153 | Example: Register an atexit handler to destroy the default loop, so any |
|
|
3154 | cleanup functions are called. |
|
|
3155 | |
|
|
3156 | static void |
|
|
3157 | program_exits (void) |
|
|
3158 | { |
|
|
3159 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
3160 | } |
|
|
3161 | |
|
|
3162 | ... |
|
|
3163 | atexit (program_exits); |
|
|
3164 | |
|
|
3165 | |
2564 | =head2 C<ev_async> - how to wake up another event loop |
3166 | =head2 C<ev_async> - how to wake up an event loop |
2565 | |
3167 | |
2566 | In general, you cannot use an C<ev_loop> from multiple threads or other |
3168 | In general, you cannot use an C<ev_run> from multiple threads or other |
2567 | asynchronous sources such as signal handlers (as opposed to multiple event |
3169 | asynchronous sources such as signal handlers (as opposed to multiple event |
2568 | loops - those are of course safe to use in different threads). |
3170 | loops - those are of course safe to use in different threads). |
2569 | |
3171 | |
2570 | Sometimes, however, you need to wake up another event loop you do not |
3172 | Sometimes, however, you need to wake up an event loop you do not control, |
2571 | control, for example because it belongs to another thread. This is what |
3173 | for example because it belongs to another thread. This is what C<ev_async> |
2572 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
3174 | watchers do: as long as the C<ev_async> watcher is active, you can signal |
2573 | can signal it by calling C<ev_async_send>, which is thread- and signal |
3175 | it by calling C<ev_async_send>, which is thread- and signal safe. |
2574 | safe. |
|
|
2575 | |
3176 | |
2576 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3177 | This functionality is very similar to C<ev_signal> watchers, as signals, |
2577 | too, are asynchronous in nature, and signals, too, will be compressed |
3178 | too, are asynchronous in nature, and signals, too, will be compressed |
2578 | (i.e. the number of callback invocations may be less than the number of |
3179 | (i.e. the number of callback invocations may be less than the number of |
2579 | C<ev_async_sent> calls). |
3180 | C<ev_async_sent> calls). |
… | |
… | |
2584 | =head3 Queueing |
3185 | =head3 Queueing |
2585 | |
3186 | |
2586 | C<ev_async> does not support queueing of data in any way. The reason |
3187 | C<ev_async> does not support queueing of data in any way. The reason |
2587 | is that the author does not know of a simple (or any) algorithm for a |
3188 | is that the author does not know of a simple (or any) algorithm for a |
2588 | multiple-writer-single-reader queue that works in all cases and doesn't |
3189 | multiple-writer-single-reader queue that works in all cases and doesn't |
2589 | need elaborate support such as pthreads. |
3190 | need elaborate support such as pthreads or unportable memory access |
|
|
3191 | semantics. |
2590 | |
3192 | |
2591 | That means that if you want to queue data, you have to provide your own |
3193 | That means that if you want to queue data, you have to provide your own |
2592 | queue. But at least I can tell you how to implement locking around your |
3194 | queue. But at least I can tell you how to implement locking around your |
2593 | queue: |
3195 | queue: |
2594 | |
3196 | |
… | |
… | |
2683 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
3285 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
2684 | C<ev_feed_event>, this call is safe to do from other threads, signal or |
3286 | C<ev_feed_event>, this call is safe to do from other threads, signal or |
2685 | similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding |
3287 | similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding |
2686 | section below on what exactly this means). |
3288 | section below on what exactly this means). |
2687 | |
3289 | |
|
|
3290 | Note that, as with other watchers in libev, multiple events might get |
|
|
3291 | compressed into a single callback invocation (another way to look at this |
|
|
3292 | is that C<ev_async> watchers are level-triggered, set on C<ev_async_send>, |
|
|
3293 | reset when the event loop detects that). |
|
|
3294 | |
2688 | This call incurs the overhead of a system call only once per loop iteration, |
3295 | This call incurs the overhead of a system call only once per event loop |
2689 | so while the overhead might be noticeable, it doesn't apply to repeated |
3296 | iteration, so while the overhead might be noticeable, it doesn't apply to |
2690 | calls to C<ev_async_send>. |
3297 | repeated calls to C<ev_async_send> for the same event loop. |
2691 | |
3298 | |
2692 | =item bool = ev_async_pending (ev_async *) |
3299 | =item bool = ev_async_pending (ev_async *) |
2693 | |
3300 | |
2694 | Returns a non-zero value when C<ev_async_send> has been called on the |
3301 | Returns a non-zero value when C<ev_async_send> has been called on the |
2695 | watcher but the event has not yet been processed (or even noted) by the |
3302 | watcher but the event has not yet been processed (or even noted) by the |
… | |
… | |
2698 | C<ev_async_send> sets a flag in the watcher and wakes up the loop. When |
3305 | C<ev_async_send> sets a flag in the watcher and wakes up the loop. When |
2699 | the loop iterates next and checks for the watcher to have become active, |
3306 | the loop iterates next and checks for the watcher to have become active, |
2700 | it will reset the flag again. C<ev_async_pending> can be used to very |
3307 | it will reset the flag again. C<ev_async_pending> can be used to very |
2701 | quickly check whether invoking the loop might be a good idea. |
3308 | quickly check whether invoking the loop might be a good idea. |
2702 | |
3309 | |
2703 | Not that this does I<not> check whether the watcher itself is pending, only |
3310 | Not that this does I<not> check whether the watcher itself is pending, |
2704 | whether it has been requested to make this watcher pending. |
3311 | only whether it has been requested to make this watcher pending: there |
|
|
3312 | is a time window between the event loop checking and resetting the async |
|
|
3313 | notification, and the callback being invoked. |
2705 | |
3314 | |
2706 | =back |
3315 | =back |
2707 | |
3316 | |
2708 | |
3317 | |
2709 | =head1 OTHER FUNCTIONS |
3318 | =head1 OTHER FUNCTIONS |
… | |
… | |
2726 | |
3335 | |
2727 | If C<timeout> is less than 0, then no timeout watcher will be |
3336 | If C<timeout> is less than 0, then no timeout watcher will be |
2728 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3337 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
2729 | repeat = 0) will be started. C<0> is a valid timeout. |
3338 | repeat = 0) will be started. C<0> is a valid timeout. |
2730 | |
3339 | |
2731 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
3340 | The callback has the type C<void (*cb)(int revents, void *arg)> and is |
2732 | passed an C<revents> set like normal event callbacks (a combination of |
3341 | passed an C<revents> set like normal event callbacks (a combination of |
2733 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
3342 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg> |
2734 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3343 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
2735 | a timeout and an io event at the same time - you probably should give io |
3344 | a timeout and an io event at the same time - you probably should give io |
2736 | events precedence. |
3345 | events precedence. |
2737 | |
3346 | |
2738 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3347 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
2739 | |
3348 | |
2740 | static void stdin_ready (int revents, void *arg) |
3349 | static void stdin_ready (int revents, void *arg) |
2741 | { |
3350 | { |
2742 | if (revents & EV_READ) |
3351 | if (revents & EV_READ) |
2743 | /* stdin might have data for us, joy! */; |
3352 | /* stdin might have data for us, joy! */; |
2744 | else if (revents & EV_TIMEOUT) |
3353 | else if (revents & EV_TIMER) |
2745 | /* doh, nothing entered */; |
3354 | /* doh, nothing entered */; |
2746 | } |
3355 | } |
2747 | |
3356 | |
2748 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3357 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2749 | |
3358 | |
2750 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
|
|
2751 | |
|
|
2752 | Feeds the given event set into the event loop, as if the specified event |
|
|
2753 | had happened for the specified watcher (which must be a pointer to an |
|
|
2754 | initialised but not necessarily started event watcher). |
|
|
2755 | |
|
|
2756 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
3359 | =item ev_feed_fd_event (loop, int fd, int revents) |
2757 | |
3360 | |
2758 | Feed an event on the given fd, as if a file descriptor backend detected |
3361 | Feed an event on the given fd, as if a file descriptor backend detected |
2759 | the given events it. |
3362 | the given events it. |
2760 | |
3363 | |
2761 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
3364 | =item ev_feed_signal_event (loop, int signum) |
2762 | |
3365 | |
2763 | Feed an event as if the given signal occurred (C<loop> must be the default |
3366 | Feed an event as if the given signal occurred (C<loop> must be the default |
2764 | loop!). |
3367 | loop!). |
2765 | |
3368 | |
2766 | =back |
3369 | =back |
2767 | |
3370 | |
2768 | |
3371 | |
|
|
3372 | =head1 COMMON OR USEFUL IDIOMS (OR BOTH) |
|
|
3373 | |
|
|
3374 | This section explains some common idioms that are not immediately |
|
|
3375 | obvious. Note that examples are sprinkled over the whole manual, and this |
|
|
3376 | section only contains stuff that wouldn't fit anywhere else. |
|
|
3377 | |
|
|
3378 | =over 4 |
|
|
3379 | |
|
|
3380 | =item Model/nested event loop invocations and exit conditions. |
|
|
3381 | |
|
|
3382 | Often (especially in GUI toolkits) there are places where you have |
|
|
3383 | I<modal> interaction, which is most easily implemented by recursively |
|
|
3384 | invoking C<ev_run>. |
|
|
3385 | |
|
|
3386 | This brings the problem of exiting - a callback might want to finish the |
|
|
3387 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
|
|
3388 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
|
|
3389 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
|
|
3390 | other combination: In these cases, C<ev_break> will not work alone. |
|
|
3391 | |
|
|
3392 | The solution is to maintain "break this loop" variable for each C<ev_run> |
|
|
3393 | invocation, and use a loop around C<ev_run> until the condition is |
|
|
3394 | triggered, using C<EVRUN_ONCE>: |
|
|
3395 | |
|
|
3396 | // main loop |
|
|
3397 | int exit_main_loop = 0; |
|
|
3398 | |
|
|
3399 | while (!exit_main_loop) |
|
|
3400 | ev_run (EV_DEFAULT_ EVRUN_ONCE); |
|
|
3401 | |
|
|
3402 | // in a model watcher |
|
|
3403 | int exit_nested_loop = 0; |
|
|
3404 | |
|
|
3405 | while (!exit_nested_loop) |
|
|
3406 | ev_run (EV_A_ EVRUN_ONCE); |
|
|
3407 | |
|
|
3408 | To exit from any of these loops, just set the corresponding exit variable: |
|
|
3409 | |
|
|
3410 | // exit modal loop |
|
|
3411 | exit_nested_loop = 1; |
|
|
3412 | |
|
|
3413 | // exit main program, after modal loop is finished |
|
|
3414 | exit_main_loop = 1; |
|
|
3415 | |
|
|
3416 | // exit both |
|
|
3417 | exit_main_loop = exit_nested_loop = 1; |
|
|
3418 | |
|
|
3419 | =back |
|
|
3420 | |
|
|
3421 | |
2769 | =head1 LIBEVENT EMULATION |
3422 | =head1 LIBEVENT EMULATION |
2770 | |
3423 | |
2771 | Libev offers a compatibility emulation layer for libevent. It cannot |
3424 | Libev offers a compatibility emulation layer for libevent. It cannot |
2772 | emulate the internals of libevent, so here are some usage hints: |
3425 | emulate the internals of libevent, so here are some usage hints: |
2773 | |
3426 | |
2774 | =over 4 |
3427 | =over 4 |
|
|
3428 | |
|
|
3429 | =item * Only the libevent-1.4.1-beta API is being emulated. |
|
|
3430 | |
|
|
3431 | This was the newest libevent version available when libev was implemented, |
|
|
3432 | and is still mostly uncanged in 2010. |
2775 | |
3433 | |
2776 | =item * Use it by including <event.h>, as usual. |
3434 | =item * Use it by including <event.h>, as usual. |
2777 | |
3435 | |
2778 | =item * The following members are fully supported: ev_base, ev_callback, |
3436 | =item * The following members are fully supported: ev_base, ev_callback, |
2779 | ev_arg, ev_fd, ev_res, ev_events. |
3437 | ev_arg, ev_fd, ev_res, ev_events. |
… | |
… | |
2785 | =item * Priorities are not currently supported. Initialising priorities |
3443 | =item * Priorities are not currently supported. Initialising priorities |
2786 | will fail and all watchers will have the same priority, even though there |
3444 | will fail and all watchers will have the same priority, even though there |
2787 | is an ev_pri field. |
3445 | is an ev_pri field. |
2788 | |
3446 | |
2789 | =item * In libevent, the last base created gets the signals, in libev, the |
3447 | =item * In libevent, the last base created gets the signals, in libev, the |
2790 | first base created (== the default loop) gets the signals. |
3448 | base that registered the signal gets the signals. |
2791 | |
3449 | |
2792 | =item * Other members are not supported. |
3450 | =item * Other members are not supported. |
2793 | |
3451 | |
2794 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
3452 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
2795 | to use the libev header file and library. |
3453 | to use the libev header file and library. |
… | |
… | |
2814 | Care has been taken to keep the overhead low. The only data member the C++ |
3472 | Care has been taken to keep the overhead low. The only data member the C++ |
2815 | classes add (compared to plain C-style watchers) is the event loop pointer |
3473 | classes add (compared to plain C-style watchers) is the event loop pointer |
2816 | that the watcher is associated with (or no additional members at all if |
3474 | that the watcher is associated with (or no additional members at all if |
2817 | you disable C<EV_MULTIPLICITY> when embedding libev). |
3475 | you disable C<EV_MULTIPLICITY> when embedding libev). |
2818 | |
3476 | |
2819 | Currently, functions, and static and non-static member functions can be |
3477 | Currently, functions, static and non-static member functions and classes |
2820 | used as callbacks. Other types should be easy to add as long as they only |
3478 | with C<operator ()> can be used as callbacks. Other types should be easy |
2821 | need one additional pointer for context. If you need support for other |
3479 | to add as long as they only need one additional pointer for context. If |
2822 | types of functors please contact the author (preferably after implementing |
3480 | you need support for other types of functors please contact the author |
2823 | it). |
3481 | (preferably after implementing it). |
2824 | |
3482 | |
2825 | Here is a list of things available in the C<ev> namespace: |
3483 | Here is a list of things available in the C<ev> namespace: |
2826 | |
3484 | |
2827 | =over 4 |
3485 | =over 4 |
2828 | |
3486 | |
… | |
… | |
2846 | |
3504 | |
2847 | =over 4 |
3505 | =over 4 |
2848 | |
3506 | |
2849 | =item ev::TYPE::TYPE () |
3507 | =item ev::TYPE::TYPE () |
2850 | |
3508 | |
2851 | =item ev::TYPE::TYPE (struct ev_loop *) |
3509 | =item ev::TYPE::TYPE (loop) |
2852 | |
3510 | |
2853 | =item ev::TYPE::~TYPE |
3511 | =item ev::TYPE::~TYPE |
2854 | |
3512 | |
2855 | The constructor (optionally) takes an event loop to associate the watcher |
3513 | The constructor (optionally) takes an event loop to associate the watcher |
2856 | with. If it is omitted, it will use C<EV_DEFAULT>. |
3514 | with. If it is omitted, it will use C<EV_DEFAULT>. |
… | |
… | |
2888 | |
3546 | |
2889 | myclass obj; |
3547 | myclass obj; |
2890 | ev::io iow; |
3548 | ev::io iow; |
2891 | iow.set <myclass, &myclass::io_cb> (&obj); |
3549 | iow.set <myclass, &myclass::io_cb> (&obj); |
2892 | |
3550 | |
|
|
3551 | =item w->set (object *) |
|
|
3552 | |
|
|
3553 | This is a variation of a method callback - leaving out the method to call |
|
|
3554 | will default the method to C<operator ()>, which makes it possible to use |
|
|
3555 | functor objects without having to manually specify the C<operator ()> all |
|
|
3556 | the time. Incidentally, you can then also leave out the template argument |
|
|
3557 | list. |
|
|
3558 | |
|
|
3559 | The C<operator ()> method prototype must be C<void operator ()(watcher &w, |
|
|
3560 | int revents)>. |
|
|
3561 | |
|
|
3562 | See the method-C<set> above for more details. |
|
|
3563 | |
|
|
3564 | Example: use a functor object as callback. |
|
|
3565 | |
|
|
3566 | struct myfunctor |
|
|
3567 | { |
|
|
3568 | void operator() (ev::io &w, int revents) |
|
|
3569 | { |
|
|
3570 | ... |
|
|
3571 | } |
|
|
3572 | } |
|
|
3573 | |
|
|
3574 | myfunctor f; |
|
|
3575 | |
|
|
3576 | ev::io w; |
|
|
3577 | w.set (&f); |
|
|
3578 | |
2893 | =item w->set<function> (void *data = 0) |
3579 | =item w->set<function> (void *data = 0) |
2894 | |
3580 | |
2895 | Also sets a callback, but uses a static method or plain function as |
3581 | Also sets a callback, but uses a static method or plain function as |
2896 | callback. The optional C<data> argument will be stored in the watcher's |
3582 | callback. The optional C<data> argument will be stored in the watcher's |
2897 | C<data> member and is free for you to use. |
3583 | C<data> member and is free for you to use. |
… | |
… | |
2903 | Example: Use a plain function as callback. |
3589 | Example: Use a plain function as callback. |
2904 | |
3590 | |
2905 | static void io_cb (ev::io &w, int revents) { } |
3591 | static void io_cb (ev::io &w, int revents) { } |
2906 | iow.set <io_cb> (); |
3592 | iow.set <io_cb> (); |
2907 | |
3593 | |
2908 | =item w->set (struct ev_loop *) |
3594 | =item w->set (loop) |
2909 | |
3595 | |
2910 | Associates a different C<struct ev_loop> with this watcher. You can only |
3596 | Associates a different C<struct ev_loop> with this watcher. You can only |
2911 | do this when the watcher is inactive (and not pending either). |
3597 | do this when the watcher is inactive (and not pending either). |
2912 | |
3598 | |
2913 | =item w->set ([arguments]) |
3599 | =item w->set ([arguments]) |
2914 | |
3600 | |
2915 | Basically the same as C<ev_TYPE_set>, with the same arguments. Must be |
3601 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
2916 | called at least once. Unlike the C counterpart, an active watcher gets |
3602 | method or a suitable start method must be called at least once. Unlike the |
2917 | automatically stopped and restarted when reconfiguring it with this |
3603 | C counterpart, an active watcher gets automatically stopped and restarted |
2918 | method. |
3604 | when reconfiguring it with this method. |
2919 | |
3605 | |
2920 | =item w->start () |
3606 | =item w->start () |
2921 | |
3607 | |
2922 | Starts the watcher. Note that there is no C<loop> argument, as the |
3608 | Starts the watcher. Note that there is no C<loop> argument, as the |
2923 | constructor already stores the event loop. |
3609 | constructor already stores the event loop. |
2924 | |
3610 | |
|
|
3611 | =item w->start ([arguments]) |
|
|
3612 | |
|
|
3613 | Instead of calling C<set> and C<start> methods separately, it is often |
|
|
3614 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
3615 | the configure C<set> method of the watcher. |
|
|
3616 | |
2925 | =item w->stop () |
3617 | =item w->stop () |
2926 | |
3618 | |
2927 | Stops the watcher if it is active. Again, no C<loop> argument. |
3619 | Stops the watcher if it is active. Again, no C<loop> argument. |
2928 | |
3620 | |
2929 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
3621 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
… | |
… | |
2941 | |
3633 | |
2942 | =back |
3634 | =back |
2943 | |
3635 | |
2944 | =back |
3636 | =back |
2945 | |
3637 | |
2946 | Example: Define a class with an IO and idle watcher, start one of them in |
3638 | Example: Define a class with two I/O and idle watchers, start the I/O |
2947 | the constructor. |
3639 | watchers in the constructor. |
2948 | |
3640 | |
2949 | class myclass |
3641 | class myclass |
2950 | { |
3642 | { |
2951 | ev::io io ; void io_cb (ev::io &w, int revents); |
3643 | ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
3644 | ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
2952 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3645 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
2953 | |
3646 | |
2954 | myclass (int fd) |
3647 | myclass (int fd) |
2955 | { |
3648 | { |
2956 | io .set <myclass, &myclass::io_cb > (this); |
3649 | io .set <myclass, &myclass::io_cb > (this); |
|
|
3650 | io2 .set <myclass, &myclass::io2_cb > (this); |
2957 | idle.set <myclass, &myclass::idle_cb> (this); |
3651 | idle.set <myclass, &myclass::idle_cb> (this); |
2958 | |
3652 | |
2959 | io.start (fd, ev::READ); |
3653 | io.set (fd, ev::WRITE); // configure the watcher |
|
|
3654 | io.start (); // start it whenever convenient |
|
|
3655 | |
|
|
3656 | io2.start (fd, ev::READ); // set + start in one call |
2960 | } |
3657 | } |
2961 | }; |
3658 | }; |
2962 | |
3659 | |
2963 | |
3660 | |
2964 | =head1 OTHER LANGUAGE BINDINGS |
3661 | =head1 OTHER LANGUAGE BINDINGS |
… | |
… | |
2983 | L<http://software.schmorp.de/pkg/EV>. |
3680 | L<http://software.schmorp.de/pkg/EV>. |
2984 | |
3681 | |
2985 | =item Python |
3682 | =item Python |
2986 | |
3683 | |
2987 | Python bindings can be found at L<http://code.google.com/p/pyev/>. It |
3684 | Python bindings can be found at L<http://code.google.com/p/pyev/>. It |
2988 | seems to be quite complete and well-documented. Note, however, that the |
3685 | seems to be quite complete and well-documented. |
2989 | patch they require for libev is outright dangerous as it breaks the ABI |
|
|
2990 | for everybody else, and therefore, should never be applied in an installed |
|
|
2991 | libev (if python requires an incompatible ABI then it needs to embed |
|
|
2992 | libev). |
|
|
2993 | |
3686 | |
2994 | =item Ruby |
3687 | =item Ruby |
2995 | |
3688 | |
2996 | Tony Arcieri has written a ruby extension that offers access to a subset |
3689 | Tony Arcieri has written a ruby extension that offers access to a subset |
2997 | of the libev API and adds file handle abstractions, asynchronous DNS and |
3690 | of the libev API and adds file handle abstractions, asynchronous DNS and |
2998 | more on top of it. It can be found via gem servers. Its homepage is at |
3691 | more on top of it. It can be found via gem servers. Its homepage is at |
2999 | L<http://rev.rubyforge.org/>. |
3692 | L<http://rev.rubyforge.org/>. |
3000 | |
3693 | |
|
|
3694 | Roger Pack reports that using the link order C<-lws2_32 -lmsvcrt-ruby-190> |
|
|
3695 | makes rev work even on mingw. |
|
|
3696 | |
|
|
3697 | =item Haskell |
|
|
3698 | |
|
|
3699 | A haskell binding to libev is available at |
|
|
3700 | L<http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>. |
|
|
3701 | |
3001 | =item D |
3702 | =item D |
3002 | |
3703 | |
3003 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
3704 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
3004 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
3705 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
3005 | |
3706 | |
3006 | =item Ocaml |
3707 | =item Ocaml |
3007 | |
3708 | |
3008 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3709 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3009 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3710 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
|
|
3711 | |
|
|
3712 | =item Lua |
|
|
3713 | |
|
|
3714 | Brian Maher has written a partial interface to libev for lua (at the |
|
|
3715 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
|
|
3716 | L<http://github.com/brimworks/lua-ev>. |
3010 | |
3717 | |
3011 | =back |
3718 | =back |
3012 | |
3719 | |
3013 | |
3720 | |
3014 | =head1 MACRO MAGIC |
3721 | =head1 MACRO MAGIC |
… | |
… | |
3028 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3735 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3029 | C<EV_A_> is used when other arguments are following. Example: |
3736 | C<EV_A_> is used when other arguments are following. Example: |
3030 | |
3737 | |
3031 | ev_unref (EV_A); |
3738 | ev_unref (EV_A); |
3032 | ev_timer_add (EV_A_ watcher); |
3739 | ev_timer_add (EV_A_ watcher); |
3033 | ev_loop (EV_A_ 0); |
3740 | ev_run (EV_A_ 0); |
3034 | |
3741 | |
3035 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3742 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3036 | which is often provided by the following macro. |
3743 | which is often provided by the following macro. |
3037 | |
3744 | |
3038 | =item C<EV_P>, C<EV_P_> |
3745 | =item C<EV_P>, C<EV_P_> |
… | |
… | |
3078 | } |
3785 | } |
3079 | |
3786 | |
3080 | ev_check check; |
3787 | ev_check check; |
3081 | ev_check_init (&check, check_cb); |
3788 | ev_check_init (&check, check_cb); |
3082 | ev_check_start (EV_DEFAULT_ &check); |
3789 | ev_check_start (EV_DEFAULT_ &check); |
3083 | ev_loop (EV_DEFAULT_ 0); |
3790 | ev_run (EV_DEFAULT_ 0); |
3084 | |
3791 | |
3085 | =head1 EMBEDDING |
3792 | =head1 EMBEDDING |
3086 | |
3793 | |
3087 | Libev can (and often is) directly embedded into host |
3794 | Libev can (and often is) directly embedded into host |
3088 | applications. Examples of applications that embed it include the Deliantra |
3795 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3168 | libev.m4 |
3875 | libev.m4 |
3169 | |
3876 | |
3170 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3877 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3171 | |
3878 | |
3172 | Libev can be configured via a variety of preprocessor symbols you have to |
3879 | Libev can be configured via a variety of preprocessor symbols you have to |
3173 | define before including any of its files. The default in the absence of |
3880 | define before including (or compiling) any of its files. The default in |
3174 | autoconf is documented for every option. |
3881 | the absence of autoconf is documented for every option. |
|
|
3882 | |
|
|
3883 | Symbols marked with "(h)" do not change the ABI, and can have different |
|
|
3884 | values when compiling libev vs. including F<ev.h>, so it is permissible |
|
|
3885 | to redefine them before including F<ev.h> without breaking compatibility |
|
|
3886 | to a compiled library. All other symbols change the ABI, which means all |
|
|
3887 | users of libev and the libev code itself must be compiled with compatible |
|
|
3888 | settings. |
3175 | |
3889 | |
3176 | =over 4 |
3890 | =over 4 |
3177 | |
3891 | |
|
|
3892 | =item EV_COMPAT3 (h) |
|
|
3893 | |
|
|
3894 | Backwards compatibility is a major concern for libev. This is why this |
|
|
3895 | release of libev comes with wrappers for the functions and symbols that |
|
|
3896 | have been renamed between libev version 3 and 4. |
|
|
3897 | |
|
|
3898 | You can disable these wrappers (to test compatibility with future |
|
|
3899 | versions) by defining C<EV_COMPAT3> to C<0> when compiling your |
|
|
3900 | sources. This has the additional advantage that you can drop the C<struct> |
|
|
3901 | from C<struct ev_loop> declarations, as libev will provide an C<ev_loop> |
|
|
3902 | typedef in that case. |
|
|
3903 | |
|
|
3904 | In some future version, the default for C<EV_COMPAT3> will become C<0>, |
|
|
3905 | and in some even more future version the compatibility code will be |
|
|
3906 | removed completely. |
|
|
3907 | |
3178 | =item EV_STANDALONE |
3908 | =item EV_STANDALONE (h) |
3179 | |
3909 | |
3180 | Must always be C<1> if you do not use autoconf configuration, which |
3910 | Must always be C<1> if you do not use autoconf configuration, which |
3181 | keeps libev from including F<config.h>, and it also defines dummy |
3911 | keeps libev from including F<config.h>, and it also defines dummy |
3182 | implementations for some libevent functions (such as logging, which is not |
3912 | implementations for some libevent functions (such as logging, which is not |
3183 | supported). It will also not define any of the structs usually found in |
3913 | supported). It will also not define any of the structs usually found in |
3184 | F<event.h> that are not directly supported by the libev core alone. |
3914 | F<event.h> that are not directly supported by the libev core alone. |
3185 | |
3915 | |
|
|
3916 | In standalone mode, libev will still try to automatically deduce the |
|
|
3917 | configuration, but has to be more conservative. |
|
|
3918 | |
3186 | =item EV_USE_MONOTONIC |
3919 | =item EV_USE_MONOTONIC |
3187 | |
3920 | |
3188 | If defined to be C<1>, libev will try to detect the availability of the |
3921 | If defined to be C<1>, libev will try to detect the availability of the |
3189 | monotonic clock option at both compile time and runtime. Otherwise no use |
3922 | monotonic clock option at both compile time and runtime. Otherwise no |
3190 | of the monotonic clock option will be attempted. If you enable this, you |
3923 | use of the monotonic clock option will be attempted. If you enable this, |
3191 | usually have to link against librt or something similar. Enabling it when |
3924 | you usually have to link against librt or something similar. Enabling it |
3192 | the functionality isn't available is safe, though, although you have |
3925 | when the functionality isn't available is safe, though, although you have |
3193 | to make sure you link against any libraries where the C<clock_gettime> |
3926 | to make sure you link against any libraries where the C<clock_gettime> |
3194 | function is hiding in (often F<-lrt>). |
3927 | function is hiding in (often F<-lrt>). See also C<EV_USE_CLOCK_SYSCALL>. |
3195 | |
3928 | |
3196 | =item EV_USE_REALTIME |
3929 | =item EV_USE_REALTIME |
3197 | |
3930 | |
3198 | If defined to be C<1>, libev will try to detect the availability of the |
3931 | If defined to be C<1>, libev will try to detect the availability of the |
3199 | real-time clock option at compile time (and assume its availability at |
3932 | real-time clock option at compile time (and assume its availability |
3200 | runtime if successful). Otherwise no use of the real-time clock option will |
3933 | at runtime if successful). Otherwise no use of the real-time clock |
3201 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
3934 | option will be attempted. This effectively replaces C<gettimeofday> |
3202 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
3935 | by C<clock_get (CLOCK_REALTIME, ...)> and will not normally affect |
3203 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
3936 | correctness. See the note about libraries in the description of |
|
|
3937 | C<EV_USE_MONOTONIC>, though. Defaults to the opposite value of |
|
|
3938 | C<EV_USE_CLOCK_SYSCALL>. |
|
|
3939 | |
|
|
3940 | =item EV_USE_CLOCK_SYSCALL |
|
|
3941 | |
|
|
3942 | If defined to be C<1>, libev will try to use a direct syscall instead |
|
|
3943 | of calling the system-provided C<clock_gettime> function. This option |
|
|
3944 | exists because on GNU/Linux, C<clock_gettime> is in C<librt>, but C<librt> |
|
|
3945 | unconditionally pulls in C<libpthread>, slowing down single-threaded |
|
|
3946 | programs needlessly. Using a direct syscall is slightly slower (in |
|
|
3947 | theory), because no optimised vdso implementation can be used, but avoids |
|
|
3948 | the pthread dependency. Defaults to C<1> on GNU/Linux with glibc 2.x or |
|
|
3949 | higher, as it simplifies linking (no need for C<-lrt>). |
3204 | |
3950 | |
3205 | =item EV_USE_NANOSLEEP |
3951 | =item EV_USE_NANOSLEEP |
3206 | |
3952 | |
3207 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
3953 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
3208 | and will use it for delays. Otherwise it will use C<select ()>. |
3954 | and will use it for delays. Otherwise it will use C<select ()>. |
… | |
… | |
3224 | |
3970 | |
3225 | =item EV_SELECT_USE_FD_SET |
3971 | =item EV_SELECT_USE_FD_SET |
3226 | |
3972 | |
3227 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3973 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3228 | structure. This is useful if libev doesn't compile due to a missing |
3974 | structure. This is useful if libev doesn't compile due to a missing |
3229 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on |
3975 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout |
3230 | exotic systems. This usually limits the range of file descriptors to some |
3976 | on exotic systems. This usually limits the range of file descriptors to |
3231 | low limit such as 1024 or might have other limitations (winsocket only |
3977 | some low limit such as 1024 or might have other limitations (winsocket |
3232 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
3978 | only allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, |
3233 | influence the size of the C<fd_set> used. |
3979 | configures the maximum size of the C<fd_set>. |
3234 | |
3980 | |
3235 | =item EV_SELECT_IS_WINSOCKET |
3981 | =item EV_SELECT_IS_WINSOCKET |
3236 | |
3982 | |
3237 | When defined to C<1>, the select backend will assume that |
3983 | When defined to C<1>, the select backend will assume that |
3238 | select/socket/connect etc. don't understand file descriptors but |
3984 | select/socket/connect etc. don't understand file descriptors but |
… | |
… | |
3240 | be used is the winsock select). This means that it will call |
3986 | be used is the winsock select). This means that it will call |
3241 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3987 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3242 | it is assumed that all these functions actually work on fds, even |
3988 | it is assumed that all these functions actually work on fds, even |
3243 | on win32. Should not be defined on non-win32 platforms. |
3989 | on win32. Should not be defined on non-win32 platforms. |
3244 | |
3990 | |
3245 | =item EV_FD_TO_WIN32_HANDLE |
3991 | =item EV_FD_TO_WIN32_HANDLE(fd) |
3246 | |
3992 | |
3247 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3993 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3248 | file descriptors to socket handles. When not defining this symbol (the |
3994 | file descriptors to socket handles. When not defining this symbol (the |
3249 | default), then libev will call C<_get_osfhandle>, which is usually |
3995 | default), then libev will call C<_get_osfhandle>, which is usually |
3250 | correct. In some cases, programs use their own file descriptor management, |
3996 | correct. In some cases, programs use their own file descriptor management, |
3251 | in which case they can provide this function to map fds to socket handles. |
3997 | in which case they can provide this function to map fds to socket handles. |
|
|
3998 | |
|
|
3999 | =item EV_WIN32_HANDLE_TO_FD(handle) |
|
|
4000 | |
|
|
4001 | If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors |
|
|
4002 | using the standard C<_open_osfhandle> function. For programs implementing |
|
|
4003 | their own fd to handle mapping, overwriting this function makes it easier |
|
|
4004 | to do so. This can be done by defining this macro to an appropriate value. |
|
|
4005 | |
|
|
4006 | =item EV_WIN32_CLOSE_FD(fd) |
|
|
4007 | |
|
|
4008 | If programs implement their own fd to handle mapping on win32, then this |
|
|
4009 | macro can be used to override the C<close> function, useful to unregister |
|
|
4010 | file descriptors again. Note that the replacement function has to close |
|
|
4011 | the underlying OS handle. |
3252 | |
4012 | |
3253 | =item EV_USE_POLL |
4013 | =item EV_USE_POLL |
3254 | |
4014 | |
3255 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4015 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3256 | backend. Otherwise it will be enabled on non-win32 platforms. It |
4016 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
3303 | as well as for signal and thread safety in C<ev_async> watchers. |
4063 | as well as for signal and thread safety in C<ev_async> watchers. |
3304 | |
4064 | |
3305 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4065 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3306 | (from F<signal.h>), which is usually good enough on most platforms. |
4066 | (from F<signal.h>), which is usually good enough on most platforms. |
3307 | |
4067 | |
3308 | =item EV_H |
4068 | =item EV_H (h) |
3309 | |
4069 | |
3310 | The name of the F<ev.h> header file used to include it. The default if |
4070 | The name of the F<ev.h> header file used to include it. The default if |
3311 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
4071 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3312 | used to virtually rename the F<ev.h> header file in case of conflicts. |
4072 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3313 | |
4073 | |
3314 | =item EV_CONFIG_H |
4074 | =item EV_CONFIG_H (h) |
3315 | |
4075 | |
3316 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
4076 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3317 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
4077 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3318 | C<EV_H>, above. |
4078 | C<EV_H>, above. |
3319 | |
4079 | |
3320 | =item EV_EVENT_H |
4080 | =item EV_EVENT_H (h) |
3321 | |
4081 | |
3322 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
4082 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3323 | of how the F<event.h> header can be found, the default is C<"event.h">. |
4083 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3324 | |
4084 | |
3325 | =item EV_PROTOTYPES |
4085 | =item EV_PROTOTYPES (h) |
3326 | |
4086 | |
3327 | If defined to be C<0>, then F<ev.h> will not define any function |
4087 | If defined to be C<0>, then F<ev.h> will not define any function |
3328 | prototypes, but still define all the structs and other symbols. This is |
4088 | prototypes, but still define all the structs and other symbols. This is |
3329 | occasionally useful if you want to provide your own wrapper functions |
4089 | occasionally useful if you want to provide your own wrapper functions |
3330 | around libev functions. |
4090 | around libev functions. |
… | |
… | |
3352 | fine. |
4112 | fine. |
3353 | |
4113 | |
3354 | If your embedding application does not need any priorities, defining these |
4114 | If your embedding application does not need any priorities, defining these |
3355 | both to C<0> will save some memory and CPU. |
4115 | both to C<0> will save some memory and CPU. |
3356 | |
4116 | |
3357 | =item EV_PERIODIC_ENABLE |
4117 | =item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, |
|
|
4118 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
|
|
4119 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3358 | |
4120 | |
3359 | If undefined or defined to be C<1>, then periodic timers are supported. If |
4121 | If undefined or defined to be C<1> (and the platform supports it), then |
3360 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
4122 | the respective watcher type is supported. If defined to be C<0>, then it |
3361 | code. |
4123 | is not. Disabling watcher types mainly saves code size. |
3362 | |
4124 | |
3363 | =item EV_IDLE_ENABLE |
4125 | =item EV_FEATURES |
3364 | |
|
|
3365 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3366 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3367 | code. |
|
|
3368 | |
|
|
3369 | =item EV_EMBED_ENABLE |
|
|
3370 | |
|
|
3371 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3372 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3373 | watcher types, which therefore must not be disabled. |
|
|
3374 | |
|
|
3375 | =item EV_STAT_ENABLE |
|
|
3376 | |
|
|
3377 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3378 | defined to be C<0>, then they are not. |
|
|
3379 | |
|
|
3380 | =item EV_FORK_ENABLE |
|
|
3381 | |
|
|
3382 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3383 | defined to be C<0>, then they are not. |
|
|
3384 | |
|
|
3385 | =item EV_ASYNC_ENABLE |
|
|
3386 | |
|
|
3387 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3388 | defined to be C<0>, then they are not. |
|
|
3389 | |
|
|
3390 | =item EV_MINIMAL |
|
|
3391 | |
4126 | |
3392 | If you need to shave off some kilobytes of code at the expense of some |
4127 | If you need to shave off some kilobytes of code at the expense of some |
3393 | speed, define this symbol to C<1>. Currently this is used to override some |
4128 | speed (but with the full API), you can define this symbol to request |
3394 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
4129 | certain subsets of functionality. The default is to enable all features |
3395 | much smaller 2-heap for timer management over the default 4-heap. |
4130 | that can be enabled on the platform. |
|
|
4131 | |
|
|
4132 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
|
|
4133 | with some broad features you want) and then selectively re-enable |
|
|
4134 | additional parts you want, for example if you want everything minimal, |
|
|
4135 | but multiple event loop support, async and child watchers and the poll |
|
|
4136 | backend, use this: |
|
|
4137 | |
|
|
4138 | #define EV_FEATURES 0 |
|
|
4139 | #define EV_MULTIPLICITY 1 |
|
|
4140 | #define EV_USE_POLL 1 |
|
|
4141 | #define EV_CHILD_ENABLE 1 |
|
|
4142 | #define EV_ASYNC_ENABLE 1 |
|
|
4143 | |
|
|
4144 | The actual value is a bitset, it can be a combination of the following |
|
|
4145 | values: |
|
|
4146 | |
|
|
4147 | =over 4 |
|
|
4148 | |
|
|
4149 | =item C<1> - faster/larger code |
|
|
4150 | |
|
|
4151 | Use larger code to speed up some operations. |
|
|
4152 | |
|
|
4153 | Currently this is used to override some inlining decisions (enlarging the |
|
|
4154 | code size by roughly 30% on amd64). |
|
|
4155 | |
|
|
4156 | When optimising for size, use of compiler flags such as C<-Os> with |
|
|
4157 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
|
|
4158 | assertions. |
|
|
4159 | |
|
|
4160 | =item C<2> - faster/larger data structures |
|
|
4161 | |
|
|
4162 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
|
|
4163 | hash table sizes and so on. This will usually further increase code size |
|
|
4164 | and can additionally have an effect on the size of data structures at |
|
|
4165 | runtime. |
|
|
4166 | |
|
|
4167 | =item C<4> - full API configuration |
|
|
4168 | |
|
|
4169 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
|
|
4170 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
|
|
4171 | |
|
|
4172 | =item C<8> - full API |
|
|
4173 | |
|
|
4174 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
|
|
4175 | details on which parts of the API are still available without this |
|
|
4176 | feature, and do not complain if this subset changes over time. |
|
|
4177 | |
|
|
4178 | =item C<16> - enable all optional watcher types |
|
|
4179 | |
|
|
4180 | Enables all optional watcher types. If you want to selectively enable |
|
|
4181 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
4182 | embed, async, child...) you can enable them manually by defining |
|
|
4183 | C<EV_watchertype_ENABLE> to C<1> instead. |
|
|
4184 | |
|
|
4185 | =item C<32> - enable all backends |
|
|
4186 | |
|
|
4187 | This enables all backends - without this feature, you need to enable at |
|
|
4188 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
|
|
4189 | |
|
|
4190 | =item C<64> - enable OS-specific "helper" APIs |
|
|
4191 | |
|
|
4192 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
4193 | default. |
|
|
4194 | |
|
|
4195 | =back |
|
|
4196 | |
|
|
4197 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
|
|
4198 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
4199 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
4200 | watchers, timers and monotonic clock support. |
|
|
4201 | |
|
|
4202 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
4203 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
|
|
4204 | your program might be left out as well - a binary starting a timer and an |
|
|
4205 | I/O watcher then might come out at only 5Kb. |
|
|
4206 | |
|
|
4207 | =item EV_AVOID_STDIO |
|
|
4208 | |
|
|
4209 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
|
|
4210 | functions (printf, scanf, perror etc.). This will increase the code size |
|
|
4211 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
4212 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
4213 | big. |
|
|
4214 | |
|
|
4215 | Note that error messages might become less precise when this option is |
|
|
4216 | enabled. |
|
|
4217 | |
|
|
4218 | =item EV_NSIG |
|
|
4219 | |
|
|
4220 | The highest supported signal number, +1 (or, the number of |
|
|
4221 | signals): Normally, libev tries to deduce the maximum number of signals |
|
|
4222 | automatically, but sometimes this fails, in which case it can be |
|
|
4223 | specified. Also, using a lower number than detected (C<32> should be |
|
|
4224 | good for about any system in existence) can save some memory, as libev |
|
|
4225 | statically allocates some 12-24 bytes per signal number. |
3396 | |
4226 | |
3397 | =item EV_PID_HASHSIZE |
4227 | =item EV_PID_HASHSIZE |
3398 | |
4228 | |
3399 | C<ev_child> watchers use a small hash table to distribute workload by |
4229 | C<ev_child> watchers use a small hash table to distribute workload by |
3400 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
4230 | pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled), |
3401 | than enough. If you need to manage thousands of children you might want to |
4231 | usually more than enough. If you need to manage thousands of children you |
3402 | increase this value (I<must> be a power of two). |
4232 | might want to increase this value (I<must> be a power of two). |
3403 | |
4233 | |
3404 | =item EV_INOTIFY_HASHSIZE |
4234 | =item EV_INOTIFY_HASHSIZE |
3405 | |
4235 | |
3406 | C<ev_stat> watchers use a small hash table to distribute workload by |
4236 | C<ev_stat> watchers use a small hash table to distribute workload by |
3407 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
4237 | inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES> |
3408 | usually more than enough. If you need to manage thousands of C<ev_stat> |
4238 | disabled), usually more than enough. If you need to manage thousands of |
3409 | watchers you might want to increase this value (I<must> be a power of |
4239 | C<ev_stat> watchers you might want to increase this value (I<must> be a |
3410 | two). |
4240 | power of two). |
3411 | |
4241 | |
3412 | =item EV_USE_4HEAP |
4242 | =item EV_USE_4HEAP |
3413 | |
4243 | |
3414 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4244 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3415 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
4245 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3416 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
4246 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3417 | faster performance with many (thousands) of watchers. |
4247 | faster performance with many (thousands) of watchers. |
3418 | |
4248 | |
3419 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4249 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3420 | (disabled). |
4250 | will be C<0>. |
3421 | |
4251 | |
3422 | =item EV_HEAP_CACHE_AT |
4252 | =item EV_HEAP_CACHE_AT |
3423 | |
4253 | |
3424 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4254 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3425 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
4255 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3426 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
4256 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3427 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
4257 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3428 | but avoids random read accesses on heap changes. This improves performance |
4258 | but avoids random read accesses on heap changes. This improves performance |
3429 | noticeably with many (hundreds) of watchers. |
4259 | noticeably with many (hundreds) of watchers. |
3430 | |
4260 | |
3431 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4261 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3432 | (disabled). |
4262 | will be C<0>. |
3433 | |
4263 | |
3434 | =item EV_VERIFY |
4264 | =item EV_VERIFY |
3435 | |
4265 | |
3436 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4266 | Controls how much internal verification (see C<ev_verify ()>) will |
3437 | be done: If set to C<0>, no internal verification code will be compiled |
4267 | be done: If set to C<0>, no internal verification code will be compiled |
3438 | in. If set to C<1>, then verification code will be compiled in, but not |
4268 | in. If set to C<1>, then verification code will be compiled in, but not |
3439 | called. If set to C<2>, then the internal verification code will be |
4269 | called. If set to C<2>, then the internal verification code will be |
3440 | called once per loop, which can slow down libev. If set to C<3>, then the |
4270 | called once per loop, which can slow down libev. If set to C<3>, then the |
3441 | verification code will be called very frequently, which will slow down |
4271 | verification code will be called very frequently, which will slow down |
3442 | libev considerably. |
4272 | libev considerably. |
3443 | |
4273 | |
3444 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
4274 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3445 | C<0>. |
4275 | will be C<0>. |
3446 | |
4276 | |
3447 | =item EV_COMMON |
4277 | =item EV_COMMON |
3448 | |
4278 | |
3449 | By default, all watchers have a C<void *data> member. By redefining |
4279 | By default, all watchers have a C<void *data> member. By redefining |
3450 | this macro to a something else you can include more and other types of |
4280 | this macro to something else you can include more and other types of |
3451 | members. You have to define it each time you include one of the files, |
4281 | members. You have to define it each time you include one of the files, |
3452 | though, and it must be identical each time. |
4282 | though, and it must be identical each time. |
3453 | |
4283 | |
3454 | For example, the perl EV module uses something like this: |
4284 | For example, the perl EV module uses something like this: |
3455 | |
4285 | |
… | |
… | |
3508 | file. |
4338 | file. |
3509 | |
4339 | |
3510 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4340 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
3511 | that everybody includes and which overrides some configure choices: |
4341 | that everybody includes and which overrides some configure choices: |
3512 | |
4342 | |
3513 | #define EV_MINIMAL 1 |
4343 | #define EV_FEATURES 8 |
3514 | #define EV_USE_POLL 0 |
4344 | #define EV_USE_SELECT 1 |
3515 | #define EV_MULTIPLICITY 0 |
|
|
3516 | #define EV_PERIODIC_ENABLE 0 |
4345 | #define EV_PREPARE_ENABLE 1 |
|
|
4346 | #define EV_IDLE_ENABLE 1 |
3517 | #define EV_STAT_ENABLE 0 |
4347 | #define EV_SIGNAL_ENABLE 1 |
3518 | #define EV_FORK_ENABLE 0 |
4348 | #define EV_CHILD_ENABLE 1 |
|
|
4349 | #define EV_USE_STDEXCEPT 0 |
3519 | #define EV_CONFIG_H <config.h> |
4350 | #define EV_CONFIG_H <config.h> |
3520 | #define EV_MINPRI 0 |
|
|
3521 | #define EV_MAXPRI 0 |
|
|
3522 | |
4351 | |
3523 | #include "ev++.h" |
4352 | #include "ev++.h" |
3524 | |
4353 | |
3525 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4354 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
3526 | |
4355 | |
… | |
… | |
3586 | default loop and triggering an C<ev_async> watcher from the default loop |
4415 | default loop and triggering an C<ev_async> watcher from the default loop |
3587 | watcher callback into the event loop interested in the signal. |
4416 | watcher callback into the event loop interested in the signal. |
3588 | |
4417 | |
3589 | =back |
4418 | =back |
3590 | |
4419 | |
|
|
4420 | =head4 THREAD LOCKING EXAMPLE |
|
|
4421 | |
|
|
4422 | Here is a fictitious example of how to run an event loop in a different |
|
|
4423 | thread than where callbacks are being invoked and watchers are |
|
|
4424 | created/added/removed. |
|
|
4425 | |
|
|
4426 | For a real-world example, see the C<EV::Loop::Async> perl module, |
|
|
4427 | which uses exactly this technique (which is suited for many high-level |
|
|
4428 | languages). |
|
|
4429 | |
|
|
4430 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
4431 | variable to wait for callback invocations, an async watcher to notify the |
|
|
4432 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
4433 | |
|
|
4434 | First, you need to associate some data with the event loop: |
|
|
4435 | |
|
|
4436 | typedef struct { |
|
|
4437 | mutex_t lock; /* global loop lock */ |
|
|
4438 | ev_async async_w; |
|
|
4439 | thread_t tid; |
|
|
4440 | cond_t invoke_cv; |
|
|
4441 | } userdata; |
|
|
4442 | |
|
|
4443 | void prepare_loop (EV_P) |
|
|
4444 | { |
|
|
4445 | // for simplicity, we use a static userdata struct. |
|
|
4446 | static userdata u; |
|
|
4447 | |
|
|
4448 | ev_async_init (&u->async_w, async_cb); |
|
|
4449 | ev_async_start (EV_A_ &u->async_w); |
|
|
4450 | |
|
|
4451 | pthread_mutex_init (&u->lock, 0); |
|
|
4452 | pthread_cond_init (&u->invoke_cv, 0); |
|
|
4453 | |
|
|
4454 | // now associate this with the loop |
|
|
4455 | ev_set_userdata (EV_A_ u); |
|
|
4456 | ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
4457 | ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
4458 | |
|
|
4459 | // then create the thread running ev_loop |
|
|
4460 | pthread_create (&u->tid, 0, l_run, EV_A); |
|
|
4461 | } |
|
|
4462 | |
|
|
4463 | The callback for the C<ev_async> watcher does nothing: the watcher is used |
|
|
4464 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
4465 | that might have been added: |
|
|
4466 | |
|
|
4467 | static void |
|
|
4468 | async_cb (EV_P_ ev_async *w, int revents) |
|
|
4469 | { |
|
|
4470 | // just used for the side effects |
|
|
4471 | } |
|
|
4472 | |
|
|
4473 | The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex |
|
|
4474 | protecting the loop data, respectively. |
|
|
4475 | |
|
|
4476 | static void |
|
|
4477 | l_release (EV_P) |
|
|
4478 | { |
|
|
4479 | userdata *u = ev_userdata (EV_A); |
|
|
4480 | pthread_mutex_unlock (&u->lock); |
|
|
4481 | } |
|
|
4482 | |
|
|
4483 | static void |
|
|
4484 | l_acquire (EV_P) |
|
|
4485 | { |
|
|
4486 | userdata *u = ev_userdata (EV_A); |
|
|
4487 | pthread_mutex_lock (&u->lock); |
|
|
4488 | } |
|
|
4489 | |
|
|
4490 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4491 | into C<ev_run>: |
|
|
4492 | |
|
|
4493 | void * |
|
|
4494 | l_run (void *thr_arg) |
|
|
4495 | { |
|
|
4496 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4497 | |
|
|
4498 | l_acquire (EV_A); |
|
|
4499 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4500 | ev_run (EV_A_ 0); |
|
|
4501 | l_release (EV_A); |
|
|
4502 | |
|
|
4503 | return 0; |
|
|
4504 | } |
|
|
4505 | |
|
|
4506 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
|
|
4507 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4508 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
|
|
4509 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4510 | and b) skipping inter-thread-communication when there are no pending |
|
|
4511 | watchers is very beneficial): |
|
|
4512 | |
|
|
4513 | static void |
|
|
4514 | l_invoke (EV_P) |
|
|
4515 | { |
|
|
4516 | userdata *u = ev_userdata (EV_A); |
|
|
4517 | |
|
|
4518 | while (ev_pending_count (EV_A)) |
|
|
4519 | { |
|
|
4520 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4521 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
|
|
4522 | } |
|
|
4523 | } |
|
|
4524 | |
|
|
4525 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4526 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
|
|
4527 | thread to continue: |
|
|
4528 | |
|
|
4529 | static void |
|
|
4530 | real_invoke_pending (EV_P) |
|
|
4531 | { |
|
|
4532 | userdata *u = ev_userdata (EV_A); |
|
|
4533 | |
|
|
4534 | pthread_mutex_lock (&u->lock); |
|
|
4535 | ev_invoke_pending (EV_A); |
|
|
4536 | pthread_cond_signal (&u->invoke_cv); |
|
|
4537 | pthread_mutex_unlock (&u->lock); |
|
|
4538 | } |
|
|
4539 | |
|
|
4540 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4541 | event loop, you will now have to lock: |
|
|
4542 | |
|
|
4543 | ev_timer timeout_watcher; |
|
|
4544 | userdata *u = ev_userdata (EV_A); |
|
|
4545 | |
|
|
4546 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4547 | |
|
|
4548 | pthread_mutex_lock (&u->lock); |
|
|
4549 | ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4550 | ev_async_send (EV_A_ &u->async_w); |
|
|
4551 | pthread_mutex_unlock (&u->lock); |
|
|
4552 | |
|
|
4553 | Note that sending the C<ev_async> watcher is required because otherwise |
|
|
4554 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4555 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4556 | watchers in the next event loop iteration. |
|
|
4557 | |
3591 | =head3 COROUTINES |
4558 | =head3 COROUTINES |
3592 | |
4559 | |
3593 | Libev is very accommodating to coroutines ("cooperative threads"): |
4560 | Libev is very accommodating to coroutines ("cooperative threads"): |
3594 | libev fully supports nesting calls to its functions from different |
4561 | libev fully supports nesting calls to its functions from different |
3595 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4562 | coroutines (e.g. you can call C<ev_run> on the same loop from two |
3596 | different coroutines, and switch freely between both coroutines running the |
4563 | different coroutines, and switch freely between both coroutines running |
3597 | loop, as long as you don't confuse yourself). The only exception is that |
4564 | the loop, as long as you don't confuse yourself). The only exception is |
3598 | you must not do this from C<ev_periodic> reschedule callbacks. |
4565 | that you must not do this from C<ev_periodic> reschedule callbacks. |
3599 | |
4566 | |
3600 | Care has been taken to ensure that libev does not keep local state inside |
4567 | Care has been taken to ensure that libev does not keep local state inside |
3601 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4568 | C<ev_run>, and other calls do not usually allow for coroutine switches as |
3602 | they do not call any callbacks. |
4569 | they do not call any callbacks. |
3603 | |
4570 | |
3604 | =head2 COMPILER WARNINGS |
4571 | =head2 COMPILER WARNINGS |
3605 | |
4572 | |
3606 | Depending on your compiler and compiler settings, you might get no or a |
4573 | Depending on your compiler and compiler settings, you might get no or a |
… | |
… | |
3617 | maintainable. |
4584 | maintainable. |
3618 | |
4585 | |
3619 | And of course, some compiler warnings are just plain stupid, or simply |
4586 | And of course, some compiler warnings are just plain stupid, or simply |
3620 | wrong (because they don't actually warn about the condition their message |
4587 | wrong (because they don't actually warn about the condition their message |
3621 | seems to warn about). For example, certain older gcc versions had some |
4588 | seems to warn about). For example, certain older gcc versions had some |
3622 | warnings that resulted an extreme number of false positives. These have |
4589 | warnings that resulted in an extreme number of false positives. These have |
3623 | been fixed, but some people still insist on making code warn-free with |
4590 | been fixed, but some people still insist on making code warn-free with |
3624 | such buggy versions. |
4591 | such buggy versions. |
3625 | |
4592 | |
3626 | While libev is written to generate as few warnings as possible, |
4593 | While libev is written to generate as few warnings as possible, |
3627 | "warn-free" code is not a goal, and it is recommended not to build libev |
4594 | "warn-free" code is not a goal, and it is recommended not to build libev |
… | |
… | |
3663 | I suggest using suppression lists. |
4630 | I suggest using suppression lists. |
3664 | |
4631 | |
3665 | |
4632 | |
3666 | =head1 PORTABILITY NOTES |
4633 | =head1 PORTABILITY NOTES |
3667 | |
4634 | |
|
|
4635 | =head2 GNU/LINUX 32 BIT LIMITATIONS |
|
|
4636 | |
|
|
4637 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
4638 | interfaces but I<disables> them by default. |
|
|
4639 | |
|
|
4640 | That means that libev compiled in the default environment doesn't support |
|
|
4641 | files larger than 2GiB or so, which mainly affects C<ev_stat> watchers. |
|
|
4642 | |
|
|
4643 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
4644 | by enabling the large file API, which makes them incompatible with the |
|
|
4645 | standard libev compiled for their system. |
|
|
4646 | |
|
|
4647 | Likewise, libev cannot enable the large file API itself as this would |
|
|
4648 | suddenly make it incompatible to the default compile time environment, |
|
|
4649 | i.e. all programs not using special compile switches. |
|
|
4650 | |
|
|
4651 | =head2 OS/X AND DARWIN BUGS |
|
|
4652 | |
|
|
4653 | The whole thing is a bug if you ask me - basically any system interface |
|
|
4654 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
4655 | OpenGL drivers. |
|
|
4656 | |
|
|
4657 | =head3 C<kqueue> is buggy |
|
|
4658 | |
|
|
4659 | The kqueue syscall is broken in all known versions - most versions support |
|
|
4660 | only sockets, many support pipes. |
|
|
4661 | |
|
|
4662 | Libev tries to work around this by not using C<kqueue> by default on this |
|
|
4663 | rotten platform, but of course you can still ask for it when creating a |
|
|
4664 | loop - embedding a socket-only kqueue loop into a select-based one is |
|
|
4665 | probably going to work well. |
|
|
4666 | |
|
|
4667 | =head3 C<poll> is buggy |
|
|
4668 | |
|
|
4669 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
|
|
4670 | implementation by something calling C<kqueue> internally around the 10.5.6 |
|
|
4671 | release, so now C<kqueue> I<and> C<poll> are broken. |
|
|
4672 | |
|
|
4673 | Libev tries to work around this by not using C<poll> by default on |
|
|
4674 | this rotten platform, but of course you can still ask for it when creating |
|
|
4675 | a loop. |
|
|
4676 | |
|
|
4677 | =head3 C<select> is buggy |
|
|
4678 | |
|
|
4679 | All that's left is C<select>, and of course Apple found a way to fuck this |
|
|
4680 | one up as well: On OS/X, C<select> actively limits the number of file |
|
|
4681 | descriptors you can pass in to 1024 - your program suddenly crashes when |
|
|
4682 | you use more. |
|
|
4683 | |
|
|
4684 | There is an undocumented "workaround" for this - defining |
|
|
4685 | C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should> |
|
|
4686 | work on OS/X. |
|
|
4687 | |
|
|
4688 | =head2 SOLARIS PROBLEMS AND WORKAROUNDS |
|
|
4689 | |
|
|
4690 | =head3 C<errno> reentrancy |
|
|
4691 | |
|
|
4692 | The default compile environment on Solaris is unfortunately so |
|
|
4693 | thread-unsafe that you can't even use components/libraries compiled |
|
|
4694 | without C<-D_REENTRANT> in a threaded program, which, of course, isn't |
|
|
4695 | defined by default. A valid, if stupid, implementation choice. |
|
|
4696 | |
|
|
4697 | If you want to use libev in threaded environments you have to make sure |
|
|
4698 | it's compiled with C<_REENTRANT> defined. |
|
|
4699 | |
|
|
4700 | =head3 Event port backend |
|
|
4701 | |
|
|
4702 | The scalable event interface for Solaris is called "event |
|
|
4703 | ports". Unfortunately, this mechanism is very buggy in all major |
|
|
4704 | releases. If you run into high CPU usage, your program freezes or you get |
|
|
4705 | a large number of spurious wakeups, make sure you have all the relevant |
|
|
4706 | and latest kernel patches applied. No, I don't know which ones, but there |
|
|
4707 | are multiple ones to apply, and afterwards, event ports actually work |
|
|
4708 | great. |
|
|
4709 | |
|
|
4710 | If you can't get it to work, you can try running the program by setting |
|
|
4711 | the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and |
|
|
4712 | C<select> backends. |
|
|
4713 | |
|
|
4714 | =head2 AIX POLL BUG |
|
|
4715 | |
|
|
4716 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
|
|
4717 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
4718 | compiled in), which normally isn't a big problem as C<select> works fine |
|
|
4719 | with large bitsets on AIX, and AIX is dead anyway. |
|
|
4720 | |
3668 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4721 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
|
|
4722 | |
|
|
4723 | =head3 General issues |
3669 | |
4724 | |
3670 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4725 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
3671 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4726 | requires, and its I/O model is fundamentally incompatible with the POSIX |
3672 | model. Libev still offers limited functionality on this platform in |
4727 | model. Libev still offers limited functionality on this platform in |
3673 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4728 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
3674 | descriptors. This only applies when using Win32 natively, not when using |
4729 | descriptors. This only applies when using Win32 natively, not when using |
3675 | e.g. cygwin. |
4730 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
4731 | as every compielr comes with a slightly differently broken/incompatible |
|
|
4732 | environment. |
3676 | |
4733 | |
3677 | Lifting these limitations would basically require the full |
4734 | Lifting these limitations would basically require the full |
3678 | re-implementation of the I/O system. If you are into these kinds of |
4735 | re-implementation of the I/O system. If you are into this kind of thing, |
3679 | things, then note that glib does exactly that for you in a very portable |
4736 | then note that glib does exactly that for you in a very portable way (note |
3680 | way (note also that glib is the slowest event library known to man). |
4737 | also that glib is the slowest event library known to man). |
3681 | |
4738 | |
3682 | There is no supported compilation method available on windows except |
4739 | There is no supported compilation method available on windows except |
3683 | embedding it into other applications. |
4740 | embedding it into other applications. |
|
|
4741 | |
|
|
4742 | Sensible signal handling is officially unsupported by Microsoft - libev |
|
|
4743 | tries its best, but under most conditions, signals will simply not work. |
3684 | |
4744 | |
3685 | Not a libev limitation but worth mentioning: windows apparently doesn't |
4745 | Not a libev limitation but worth mentioning: windows apparently doesn't |
3686 | accept large writes: instead of resulting in a partial write, windows will |
4746 | accept large writes: instead of resulting in a partial write, windows will |
3687 | either accept everything or return C<ENOBUFS> if the buffer is too large, |
4747 | either accept everything or return C<ENOBUFS> if the buffer is too large, |
3688 | so make sure you only write small amounts into your sockets (less than a |
4748 | so make sure you only write small amounts into your sockets (less than a |
… | |
… | |
3693 | the abysmal performance of winsockets, using a large number of sockets |
4753 | the abysmal performance of winsockets, using a large number of sockets |
3694 | is not recommended (and not reasonable). If your program needs to use |
4754 | is not recommended (and not reasonable). If your program needs to use |
3695 | more than a hundred or so sockets, then likely it needs to use a totally |
4755 | more than a hundred or so sockets, then likely it needs to use a totally |
3696 | different implementation for windows, as libev offers the POSIX readiness |
4756 | different implementation for windows, as libev offers the POSIX readiness |
3697 | notification model, which cannot be implemented efficiently on windows |
4757 | notification model, which cannot be implemented efficiently on windows |
3698 | (Microsoft monopoly games). |
4758 | (due to Microsoft monopoly games). |
3699 | |
4759 | |
3700 | A typical way to use libev under windows is to embed it (see the embedding |
4760 | A typical way to use libev under windows is to embed it (see the embedding |
3701 | section for details) and use the following F<evwrap.h> header file instead |
4761 | section for details) and use the following F<evwrap.h> header file instead |
3702 | of F<ev.h>: |
4762 | of F<ev.h>: |
3703 | |
4763 | |
… | |
… | |
3710 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4770 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
3711 | |
4771 | |
3712 | #include "evwrap.h" |
4772 | #include "evwrap.h" |
3713 | #include "ev.c" |
4773 | #include "ev.c" |
3714 | |
4774 | |
3715 | =over 4 |
|
|
3716 | |
|
|
3717 | =item The winsocket select function |
4775 | =head3 The winsocket C<select> function |
3718 | |
4776 | |
3719 | The winsocket C<select> function doesn't follow POSIX in that it |
4777 | The winsocket C<select> function doesn't follow POSIX in that it |
3720 | requires socket I<handles> and not socket I<file descriptors> (it is |
4778 | requires socket I<handles> and not socket I<file descriptors> (it is |
3721 | also extremely buggy). This makes select very inefficient, and also |
4779 | also extremely buggy). This makes select very inefficient, and also |
3722 | requires a mapping from file descriptors to socket handles (the Microsoft |
4780 | requires a mapping from file descriptors to socket handles (the Microsoft |
… | |
… | |
3731 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4789 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
3732 | |
4790 | |
3733 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4791 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
3734 | complexity in the O(n²) range when using win32. |
4792 | complexity in the O(n²) range when using win32. |
3735 | |
4793 | |
3736 | =item Limited number of file descriptors |
4794 | =head3 Limited number of file descriptors |
3737 | |
4795 | |
3738 | Windows has numerous arbitrary (and low) limits on things. |
4796 | Windows has numerous arbitrary (and low) limits on things. |
3739 | |
4797 | |
3740 | Early versions of winsocket's select only supported waiting for a maximum |
4798 | Early versions of winsocket's select only supported waiting for a maximum |
3741 | of C<64> handles (probably owning to the fact that all windows kernels |
4799 | of C<64> handles (probably owning to the fact that all windows kernels |
3742 | can only wait for C<64> things at the same time internally; Microsoft |
4800 | can only wait for C<64> things at the same time internally; Microsoft |
3743 | recommends spawning a chain of threads and wait for 63 handles and the |
4801 | recommends spawning a chain of threads and wait for 63 handles and the |
3744 | previous thread in each. Great). |
4802 | previous thread in each. Sounds great!). |
3745 | |
4803 | |
3746 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
4804 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
3747 | to some high number (e.g. C<2048>) before compiling the winsocket select |
4805 | to some high number (e.g. C<2048>) before compiling the winsocket select |
3748 | call (which might be in libev or elsewhere, for example, perl does its own |
4806 | call (which might be in libev or elsewhere, for example, perl and many |
3749 | select emulation on windows). |
4807 | other interpreters do their own select emulation on windows). |
3750 | |
4808 | |
3751 | Another limit is the number of file descriptors in the Microsoft runtime |
4809 | Another limit is the number of file descriptors in the Microsoft runtime |
3752 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
4810 | libraries, which by default is C<64> (there must be a hidden I<64> |
3753 | or something like this inside Microsoft). You can increase this by calling |
4811 | fetish or something like this inside Microsoft). You can increase this |
3754 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
4812 | by calling C<_setmaxstdio>, which can increase this limit to C<2048> |
3755 | arbitrary limit), but is broken in many versions of the Microsoft runtime |
4813 | (another arbitrary limit), but is broken in many versions of the Microsoft |
3756 | libraries. |
|
|
3757 | |
|
|
3758 | This might get you to about C<512> or C<2048> sockets (depending on |
4814 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
3759 | windows version and/or the phase of the moon). To get more, you need to |
4815 | (depending on windows version and/or the phase of the moon). To get more, |
3760 | wrap all I/O functions and provide your own fd management, but the cost of |
4816 | you need to wrap all I/O functions and provide your own fd management, but |
3761 | calling select (O(n²)) will likely make this unworkable. |
4817 | the cost of calling select (O(n²)) will likely make this unworkable. |
3762 | |
|
|
3763 | =back |
|
|
3764 | |
4818 | |
3765 | =head2 PORTABILITY REQUIREMENTS |
4819 | =head2 PORTABILITY REQUIREMENTS |
3766 | |
4820 | |
3767 | In addition to a working ISO-C implementation and of course the |
4821 | In addition to a working ISO-C implementation and of course the |
3768 | backend-specific APIs, libev relies on a few additional extensions: |
4822 | backend-specific APIs, libev relies on a few additional extensions: |
… | |
… | |
3775 | Libev assumes not only that all watcher pointers have the same internal |
4829 | Libev assumes not only that all watcher pointers have the same internal |
3776 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
4830 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
3777 | assumes that the same (machine) code can be used to call any watcher |
4831 | assumes that the same (machine) code can be used to call any watcher |
3778 | callback: The watcher callbacks have different type signatures, but libev |
4832 | callback: The watcher callbacks have different type signatures, but libev |
3779 | calls them using an C<ev_watcher *> internally. |
4833 | calls them using an C<ev_watcher *> internally. |
|
|
4834 | |
|
|
4835 | =item pointer accesses must be thread-atomic |
|
|
4836 | |
|
|
4837 | Accessing a pointer value must be atomic, it must both be readable and |
|
|
4838 | writable in one piece - this is the case on all current architectures. |
3780 | |
4839 | |
3781 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
4840 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
3782 | |
4841 | |
3783 | The type C<sig_atomic_t volatile> (or whatever is defined as |
4842 | The type C<sig_atomic_t volatile> (or whatever is defined as |
3784 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
4843 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
… | |
… | |
3807 | watchers. |
4866 | watchers. |
3808 | |
4867 | |
3809 | =item C<double> must hold a time value in seconds with enough accuracy |
4868 | =item C<double> must hold a time value in seconds with enough accuracy |
3810 | |
4869 | |
3811 | The type C<double> is used to represent timestamps. It is required to |
4870 | The type C<double> is used to represent timestamps. It is required to |
3812 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4871 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
3813 | enough for at least into the year 4000. This requirement is fulfilled by |
4872 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
4873 | (the design goal for libev). This requirement is overfulfilled by |
3814 | implementations implementing IEEE 754 (basically all existing ones). |
4874 | implementations using IEEE 754, which is basically all existing ones. With |
|
|
4875 | IEEE 754 doubles, you get microsecond accuracy until at least 2200. |
3815 | |
4876 | |
3816 | =back |
4877 | =back |
3817 | |
4878 | |
3818 | If you know of other additional requirements drop me a note. |
4879 | If you know of other additional requirements drop me a note. |
3819 | |
4880 | |
… | |
… | |
3887 | involves iterating over all running async watchers or all signal numbers. |
4948 | involves iterating over all running async watchers or all signal numbers. |
3888 | |
4949 | |
3889 | =back |
4950 | =back |
3890 | |
4951 | |
3891 | |
4952 | |
|
|
4953 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
|
|
4954 | |
|
|
4955 | The major version 4 introduced some incompatible changes to the API. |
|
|
4956 | |
|
|
4957 | At the moment, the C<ev.h> header file provides compatibility definitions |
|
|
4958 | for all changes, so most programs should still compile. The compatibility |
|
|
4959 | layer might be removed in later versions of libev, so better update to the |
|
|
4960 | new API early than late. |
|
|
4961 | |
|
|
4962 | =over 4 |
|
|
4963 | |
|
|
4964 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
4965 | |
|
|
4966 | The backward compatibility mechanism can be controlled by |
|
|
4967 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
4968 | section. |
|
|
4969 | |
|
|
4970 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
|
|
4971 | |
|
|
4972 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
|
|
4973 | |
|
|
4974 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
4975 | ev_loop_fork (EV_DEFAULT); |
|
|
4976 | |
|
|
4977 | =item function/symbol renames |
|
|
4978 | |
|
|
4979 | A number of functions and symbols have been renamed: |
|
|
4980 | |
|
|
4981 | ev_loop => ev_run |
|
|
4982 | EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
4983 | EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
4984 | |
|
|
4985 | ev_unloop => ev_break |
|
|
4986 | EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
4987 | EVUNLOOP_ONE => EVBREAK_ONE |
|
|
4988 | EVUNLOOP_ALL => EVBREAK_ALL |
|
|
4989 | |
|
|
4990 | EV_TIMEOUT => EV_TIMER |
|
|
4991 | |
|
|
4992 | ev_loop_count => ev_iteration |
|
|
4993 | ev_loop_depth => ev_depth |
|
|
4994 | ev_loop_verify => ev_verify |
|
|
4995 | |
|
|
4996 | Most functions working on C<struct ev_loop> objects don't have an |
|
|
4997 | C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and |
|
|
4998 | associated constants have been renamed to not collide with the C<struct |
|
|
4999 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
|
|
5000 | as all other watcher types. Note that C<ev_loop_fork> is still called |
|
|
5001 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
|
|
5002 | typedef. |
|
|
5003 | |
|
|
5004 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
5005 | |
|
|
5006 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
5007 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
5008 | and work, but the library code will of course be larger. |
|
|
5009 | |
|
|
5010 | =back |
|
|
5011 | |
|
|
5012 | |
|
|
5013 | =head1 GLOSSARY |
|
|
5014 | |
|
|
5015 | =over 4 |
|
|
5016 | |
|
|
5017 | =item active |
|
|
5018 | |
|
|
5019 | A watcher is active as long as it has been started and not yet stopped. |
|
|
5020 | See L<WATCHER STATES> for details. |
|
|
5021 | |
|
|
5022 | =item application |
|
|
5023 | |
|
|
5024 | In this document, an application is whatever is using libev. |
|
|
5025 | |
|
|
5026 | =item backend |
|
|
5027 | |
|
|
5028 | The part of the code dealing with the operating system interfaces. |
|
|
5029 | |
|
|
5030 | =item callback |
|
|
5031 | |
|
|
5032 | The address of a function that is called when some event has been |
|
|
5033 | detected. Callbacks are being passed the event loop, the watcher that |
|
|
5034 | received the event, and the actual event bitset. |
|
|
5035 | |
|
|
5036 | =item callback/watcher invocation |
|
|
5037 | |
|
|
5038 | The act of calling the callback associated with a watcher. |
|
|
5039 | |
|
|
5040 | =item event |
|
|
5041 | |
|
|
5042 | A change of state of some external event, such as data now being available |
|
|
5043 | for reading on a file descriptor, time having passed or simply not having |
|
|
5044 | any other events happening anymore. |
|
|
5045 | |
|
|
5046 | In libev, events are represented as single bits (such as C<EV_READ> or |
|
|
5047 | C<EV_TIMER>). |
|
|
5048 | |
|
|
5049 | =item event library |
|
|
5050 | |
|
|
5051 | A software package implementing an event model and loop. |
|
|
5052 | |
|
|
5053 | =item event loop |
|
|
5054 | |
|
|
5055 | An entity that handles and processes external events and converts them |
|
|
5056 | into callback invocations. |
|
|
5057 | |
|
|
5058 | =item event model |
|
|
5059 | |
|
|
5060 | The model used to describe how an event loop handles and processes |
|
|
5061 | watchers and events. |
|
|
5062 | |
|
|
5063 | =item pending |
|
|
5064 | |
|
|
5065 | A watcher is pending as soon as the corresponding event has been |
|
|
5066 | detected. See L<WATCHER STATES> for details. |
|
|
5067 | |
|
|
5068 | =item real time |
|
|
5069 | |
|
|
5070 | The physical time that is observed. It is apparently strictly monotonic :) |
|
|
5071 | |
|
|
5072 | =item wall-clock time |
|
|
5073 | |
|
|
5074 | The time and date as shown on clocks. Unlike real time, it can actually |
|
|
5075 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
|
|
5076 | clock. |
|
|
5077 | |
|
|
5078 | =item watcher |
|
|
5079 | |
|
|
5080 | A data structure that describes interest in certain events. Watchers need |
|
|
5081 | to be started (attached to an event loop) before they can receive events. |
|
|
5082 | |
|
|
5083 | =back |
|
|
5084 | |
3892 | =head1 AUTHOR |
5085 | =head1 AUTHOR |
3893 | |
5086 | |
3894 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
5087 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
|
|
5088 | Magnusson and Emanuele Giaquinta. |
3895 | |
5089 | |