… | |
… | |
56 | |
56 | |
57 | =over 4 |
57 | =over 4 |
58 | |
58 | |
59 | =item ev_tstamp ev_time () |
59 | =item ev_tstamp ev_time () |
60 | |
60 | |
61 | Returns the current time as libev would use it. |
61 | Returns the current time as libev would use it. Please note that the |
|
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62 | C<ev_now> function is usually faster and also often returns the timestamp |
|
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63 | you actually want to know. |
62 | |
64 | |
63 | =item int ev_version_major () |
65 | =item int ev_version_major () |
64 | |
66 | |
65 | =item int ev_version_minor () |
67 | =item int ev_version_minor () |
66 | |
68 | |
… | |
… | |
72 | |
74 | |
73 | Usually, it's a good idea to terminate if the major versions mismatch, |
75 | Usually, it's a good idea to terminate if the major versions mismatch, |
74 | as this indicates an incompatible change. Minor versions are usually |
76 | as this indicates an incompatible change. Minor versions are usually |
75 | compatible to older versions, so a larger minor version alone is usually |
77 | compatible to older versions, so a larger minor version alone is usually |
76 | not a problem. |
78 | not a problem. |
|
|
79 | |
|
|
80 | =item unsigned int ev_supported_backends () |
|
|
81 | |
|
|
82 | Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*> |
|
|
83 | value) compiled into this binary of libev (independent of their |
|
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84 | availability on the system you are running on). See C<ev_default_loop> for |
|
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85 | a description of the set values. |
|
|
86 | |
|
|
87 | =item unsigned int ev_recommended_backends () |
|
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88 | |
|
|
89 | Return the set of all backends compiled into this binary of libev and also |
|
|
90 | recommended for this platform. This set is often smaller than the one |
|
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91 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
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92 | most BSDs and will not be autodetected unless you explicitly request it |
|
|
93 | (assuming you know what you are doing). This is the set of backends that |
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94 | C<EVFLAG_AUTO> will probe for. |
77 | |
95 | |
78 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
96 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
79 | |
97 | |
80 | Sets the allocation function to use (the prototype is similar to the |
98 | Sets the allocation function to use (the prototype is similar to the |
81 | realloc C function, the semantics are identical). It is used to allocate |
99 | realloc C function, the semantics are identical). It is used to allocate |
… | |
… | |
117 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
135 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
118 | |
136 | |
119 | This will initialise the default event loop if it hasn't been initialised |
137 | This will initialise the default event loop if it hasn't been initialised |
120 | yet and return it. If the default loop could not be initialised, returns |
138 | yet and return it. If the default loop could not be initialised, returns |
121 | false. If it already was initialised it simply returns it (and ignores the |
139 | false. If it already was initialised it simply returns it (and ignores the |
122 | flags). |
140 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
123 | |
141 | |
124 | If you don't know what event loop to use, use the one returned from this |
142 | If you don't know what event loop to use, use the one returned from this |
125 | function. |
143 | function. |
126 | |
144 | |
127 | The flags argument can be used to specify special behaviour or specific |
145 | The flags argument can be used to specify special behaviour or specific |
128 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO). |
146 | backends to use, and is usually specified as C<0> (or EVFLAG_AUTO). |
129 | |
147 | |
130 | It supports the following flags: |
148 | It supports the following flags: |
131 | |
149 | |
132 | =over 4 |
150 | =over 4 |
133 | |
151 | |
… | |
… | |
143 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
161 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
144 | override the flags completely if it is found in the environment. This is |
162 | override the flags completely if it is found in the environment. This is |
145 | useful to try out specific backends to test their performance, or to work |
163 | useful to try out specific backends to test their performance, or to work |
146 | around bugs. |
164 | around bugs. |
147 | |
165 | |
148 | =item C<EVMETHOD_SELECT> (portable select backend) |
166 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
149 | |
167 | |
|
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168 | This is your standard select(2) backend. Not I<completely> standard, as |
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169 | libev tries to roll its own fd_set with no limits on the number of fds, |
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170 | but if that fails, expect a fairly low limit on the number of fds when |
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171 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
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172 | the fastest backend for a low number of fds. |
|
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173 | |
150 | =item C<EVMETHOD_POLL> (poll backend, available everywhere except on windows) |
174 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
151 | |
175 | |
152 | =item C<EVMETHOD_EPOLL> (linux only) |
176 | And this is your standard poll(2) backend. It's more complicated than |
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177 | select, but handles sparse fds better and has no artificial limit on the |
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178 | number of fds you can use (except it will slow down considerably with a |
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179 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
153 | |
180 | |
154 | =item C<EVMETHOD_KQUEUE> (some bsds only) |
181 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
155 | |
182 | |
156 | =item C<EVMETHOD_DEVPOLL> (solaris 8 only) |
183 | For few fds, this backend is a bit little slower than poll and select, |
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184 | but it scales phenomenally better. While poll and select usually scale like |
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185 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
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186 | either O(1) or O(active_fds). |
157 | |
187 | |
158 | =item C<EVMETHOD_PORT> (solaris 10 only) |
188 | While stopping and starting an I/O watcher in the same iteration will |
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189 | result in some caching, there is still a syscall per such incident |
|
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190 | (because the fd could point to a different file description now), so its |
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191 | best to avoid that. Also, dup()ed file descriptors might not work very |
|
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192 | well if you register events for both fds. |
|
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193 | |
|
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194 | Please note that epoll sometimes generates spurious notifications, so you |
|
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195 | need to use non-blocking I/O or other means to avoid blocking when no data |
|
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196 | (or space) is available. |
|
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197 | |
|
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198 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
|
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199 | |
|
|
200 | Kqueue deserves special mention, as at the time of this writing, it |
|
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201 | was broken on all BSDs except NetBSD (usually it doesn't work with |
|
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202 | anything but sockets and pipes, except on Darwin, where of course its |
|
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203 | completely useless). For this reason its not being "autodetected" unless |
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204 | you explicitly specify the flags (i.e. you don't use EVFLAG_AUTO). |
|
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205 | |
|
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206 | It scales in the same way as the epoll backend, but the interface to the |
|
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207 | kernel is more efficient (which says nothing about its actual speed, of |
|
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208 | course). While starting and stopping an I/O watcher does not cause an |
|
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209 | extra syscall as with epoll, it still adds up to four event changes per |
|
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210 | incident, so its best to avoid that. |
|
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211 | |
|
|
212 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
|
|
213 | |
|
|
214 | This is not implemented yet (and might never be). |
|
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215 | |
|
|
216 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
|
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217 | |
|
|
218 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
|
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219 | it's really slow, but it still scales very well (O(active_fds)). |
|
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220 | |
|
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221 | Please note that solaris ports can result in a lot of spurious |
|
|
222 | notifications, so you need to use non-blocking I/O or other means to avoid |
|
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223 | blocking when no data (or space) is available. |
|
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224 | |
|
|
225 | =item C<EVBACKEND_ALL> |
|
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226 | |
|
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227 | Try all backends (even potentially broken ones that wouldn't be tried |
|
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228 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
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229 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
|
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230 | |
|
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231 | =back |
159 | |
232 | |
160 | If one or more of these are ored into the flags value, then only these |
233 | If one or more of these are ored into the flags value, then only these |
161 | backends will be tried (in the reverse order as given here). If one are |
234 | backends will be tried (in the reverse order as given here). If none are |
162 | specified, any backend will do. |
235 | specified, most compiled-in backend will be tried, usually in reverse |
163 | |
236 | order of their flag values :) |
164 | =back |
|
|
165 | |
237 | |
166 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
238 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
167 | |
239 | |
168 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
240 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
169 | always distinct from the default loop. Unlike the default loop, it cannot |
241 | always distinct from the default loop. Unlike the default loop, it cannot |
… | |
… | |
186 | This function reinitialises the kernel state for backends that have |
258 | This function reinitialises the kernel state for backends that have |
187 | one. Despite the name, you can call it anytime, but it makes most sense |
259 | one. Despite the name, you can call it anytime, but it makes most sense |
188 | after forking, in either the parent or child process (or both, but that |
260 | after forking, in either the parent or child process (or both, but that |
189 | again makes little sense). |
261 | again makes little sense). |
190 | |
262 | |
191 | You I<must> call this function after forking if and only if you want to |
263 | You I<must> call this function in the child process after forking if and |
192 | use the event library in both processes. If you just fork+exec, you don't |
264 | only if you want to use the event library in both processes. If you just |
193 | have to call it. |
265 | fork+exec, you don't have to call it. |
194 | |
266 | |
195 | The function itself is quite fast and it's usually not a problem to call |
267 | The function itself is quite fast and it's usually not a problem to call |
196 | it just in case after a fork. To make this easy, the function will fit in |
268 | it just in case after a fork. To make this easy, the function will fit in |
197 | quite nicely into a call to C<pthread_atfork>: |
269 | quite nicely into a call to C<pthread_atfork>: |
198 | |
270 | |
199 | pthread_atfork (0, 0, ev_default_fork); |
271 | pthread_atfork (0, 0, ev_default_fork); |
200 | |
272 | |
|
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273 | At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use |
|
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274 | without calling this function, so if you force one of those backends you |
|
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275 | do not need to care. |
|
|
276 | |
201 | =item ev_loop_fork (loop) |
277 | =item ev_loop_fork (loop) |
202 | |
278 | |
203 | Like C<ev_default_fork>, but acts on an event loop created by |
279 | Like C<ev_default_fork>, but acts on an event loop created by |
204 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
280 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
205 | after fork, and how you do this is entirely your own problem. |
281 | after fork, and how you do this is entirely your own problem. |
206 | |
282 | |
207 | =item unsigned int ev_method (loop) |
283 | =item unsigned int ev_backend (loop) |
208 | |
284 | |
209 | Returns one of the C<EVMETHOD_*> flags indicating the event backend in |
285 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
210 | use. |
286 | use. |
211 | |
287 | |
212 | =item ev_tstamp ev_now (loop) |
288 | =item ev_tstamp ev_now (loop) |
213 | |
289 | |
214 | Returns the current "event loop time", which is the time the event loop |
290 | Returns the current "event loop time", which is the time the event loop |
… | |
… | |
237 | |
313 | |
238 | This flags value could be used to implement alternative looping |
314 | This flags value could be used to implement alternative looping |
239 | constructs, but the C<prepare> and C<check> watchers provide a better and |
315 | constructs, but the C<prepare> and C<check> watchers provide a better and |
240 | more generic mechanism. |
316 | more generic mechanism. |
241 | |
317 | |
|
|
318 | Here are the gory details of what ev_loop does: |
|
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319 | |
|
|
320 | 1. If there are no active watchers (reference count is zero), return. |
|
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321 | 2. Queue and immediately call all prepare watchers. |
|
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322 | 3. If we have been forked, recreate the kernel state. |
|
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323 | 4. Update the kernel state with all outstanding changes. |
|
|
324 | 5. Update the "event loop time". |
|
|
325 | 6. Calculate for how long to block. |
|
|
326 | 7. Block the process, waiting for events. |
|
|
327 | 8. Update the "event loop time" and do time jump handling. |
|
|
328 | 9. Queue all outstanding timers. |
|
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329 | 10. Queue all outstanding periodics. |
|
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330 | 11. If no events are pending now, queue all idle watchers. |
|
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331 | 12. Queue all check watchers. |
|
|
332 | 13. Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
333 | 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
|
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334 | was used, return, otherwise continue with step #1. |
|
|
335 | |
242 | =item ev_unloop (loop, how) |
336 | =item ev_unloop (loop, how) |
243 | |
337 | |
244 | Can be used to make a call to C<ev_loop> return early (but only after it |
338 | Can be used to make a call to C<ev_loop> return early (but only after it |
245 | has processed all outstanding events). The C<how> argument must be either |
339 | has processed all outstanding events). The C<how> argument must be either |
246 | C<EVUNLOOP_ONCE>, which will make the innermost C<ev_loop> call return, or |
340 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
247 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
341 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
248 | |
342 | |
249 | =item ev_ref (loop) |
343 | =item ev_ref (loop) |
250 | |
344 | |
251 | =item ev_unref (loop) |
345 | =item ev_unref (loop) |
… | |
… | |
302 | *) >>), and you can stop watching for events at any time by calling the |
396 | *) >>), and you can stop watching for events at any time by calling the |
303 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
397 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
304 | |
398 | |
305 | As long as your watcher is active (has been started but not stopped) you |
399 | As long as your watcher is active (has been started but not stopped) you |
306 | must not touch the values stored in it. Most specifically you must never |
400 | must not touch the values stored in it. Most specifically you must never |
307 | reinitialise it or call its set method. |
401 | reinitialise it or call its set macro. |
308 | |
402 | |
309 | You can check whether an event is active by calling the C<ev_is_active |
403 | You can check whether an event is active by calling the C<ev_is_active |
310 | (watcher *)> macro. To see whether an event is outstanding (but the |
404 | (watcher *)> macro. To see whether an event is outstanding (but the |
311 | callback for it has not been called yet) you can use the C<ev_is_pending |
405 | callback for it has not been called yet) you can use the C<ev_is_pending |
312 | (watcher *)> macro. |
406 | (watcher *)> macro. |
… | |
… | |
425 | required if you know what you are doing). |
519 | required if you know what you are doing). |
426 | |
520 | |
427 | You have to be careful with dup'ed file descriptors, though. Some backends |
521 | You have to be careful with dup'ed file descriptors, though. Some backends |
428 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
522 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
429 | descriptors correctly if you register interest in two or more fds pointing |
523 | descriptors correctly if you register interest in two or more fds pointing |
430 | to the same file/socket etc. description (that is, they share the same |
524 | to the same underlying file/socket etc. description (that is, they share |
431 | underlying "file open"). |
525 | the same underlying "file open"). |
432 | |
526 | |
433 | If you must do this, then force the use of a known-to-be-good backend |
527 | If you must do this, then force the use of a known-to-be-good backend |
434 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
528 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
435 | EVMETHOD_POLL). |
529 | C<EVBACKEND_POLL>). |
436 | |
530 | |
437 | =over 4 |
531 | =over 4 |
438 | |
532 | |
439 | =item ev_io_init (ev_io *, callback, int fd, int events) |
533 | =item ev_io_init (ev_io *, callback, int fd, int events) |
440 | |
534 | |
… | |
… | |
442 | |
536 | |
443 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
537 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
444 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
538 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
445 | EV_WRITE> to receive the given events. |
539 | EV_WRITE> to receive the given events. |
446 | |
540 | |
|
|
541 | Please note that most of the more scalable backend mechanisms (for example |
|
|
542 | epoll and solaris ports) can result in spurious readyness notifications |
|
|
543 | for file descriptors, so you practically need to use non-blocking I/O (and |
|
|
544 | treat callback invocation as hint only), or retest separately with a safe |
|
|
545 | interface before doing I/O (XLib can do this), or force the use of either |
|
|
546 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this |
|
|
547 | problem. Also note that it is quite easy to have your callback invoked |
|
|
548 | when the readyness condition is no longer valid even when employing |
|
|
549 | typical ways of handling events, so its a good idea to use non-blocking |
|
|
550 | I/O unconditionally. |
|
|
551 | |
447 | =back |
552 | =back |
448 | |
553 | |
449 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
554 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
450 | |
555 | |
451 | Timer watchers are simple relative timers that generate an event after a |
556 | Timer watchers are simple relative timers that generate an event after a |
452 | given time, and optionally repeating in regular intervals after that. |
557 | given time, and optionally repeating in regular intervals after that. |
453 | |
558 | |
454 | The timers are based on real time, that is, if you register an event that |
559 | The timers are based on real time, that is, if you register an event that |
455 | times out after an hour and you reset your system clock to last years |
560 | times out after an hour and you reset your system clock to last years |
456 | time, it will still time out after (roughly) and hour. "Roughly" because |
561 | time, it will still time out after (roughly) and hour. "Roughly" because |
457 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
562 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
458 | monotonic clock option helps a lot here). |
563 | monotonic clock option helps a lot here). |
459 | |
564 | |
460 | The relative timeouts are calculated relative to the C<ev_now ()> |
565 | The relative timeouts are calculated relative to the C<ev_now ()> |
461 | time. This is usually the right thing as this timestamp refers to the time |
566 | time. This is usually the right thing as this timestamp refers to the time |
462 | of the event triggering whatever timeout you are modifying/starting. If |
567 | of the event triggering whatever timeout you are modifying/starting. If |
463 | you suspect event processing to be delayed and you *need* to base the timeout |
568 | you suspect event processing to be delayed and you I<need> to base the timeout |
464 | on the current time, use something like this to adjust for this: |
569 | on the current time, use something like this to adjust for this: |
465 | |
570 | |
466 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
571 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
|
|
572 | |
|
|
573 | The callback is guarenteed to be invoked only when its timeout has passed, |
|
|
574 | but if multiple timers become ready during the same loop iteration then |
|
|
575 | order of execution is undefined. |
467 | |
576 | |
468 | =over 4 |
577 | =over 4 |
469 | |
578 | |
470 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
579 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
471 | |
580 | |
… | |
… | |
518 | again). |
627 | again). |
519 | |
628 | |
520 | They can also be used to implement vastly more complex timers, such as |
629 | They can also be used to implement vastly more complex timers, such as |
521 | triggering an event on eahc midnight, local time. |
630 | triggering an event on eahc midnight, local time. |
522 | |
631 | |
|
|
632 | As with timers, the callback is guarenteed to be invoked only when the |
|
|
633 | time (C<at>) has been passed, but if multiple periodic timers become ready |
|
|
634 | during the same loop iteration then order of execution is undefined. |
|
|
635 | |
523 | =over 4 |
636 | =over 4 |
524 | |
637 | |
525 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
638 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
526 | |
639 | |
527 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
640 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
528 | |
641 | |
529 | Lots of arguments, lets sort it out... There are basically three modes of |
642 | Lots of arguments, lets sort it out... There are basically three modes of |
530 | operation, and we will explain them from simplest to complex: |
643 | operation, and we will explain them from simplest to complex: |
531 | |
|
|
532 | |
644 | |
533 | =over 4 |
645 | =over 4 |
534 | |
646 | |
535 | =item * absolute timer (interval = reschedule_cb = 0) |
647 | =item * absolute timer (interval = reschedule_cb = 0) |
536 | |
648 | |
… | |
… | |
772 | |
884 | |
773 | =back |
885 | =back |
774 | |
886 | |
775 | =head1 LIBEVENT EMULATION |
887 | =head1 LIBEVENT EMULATION |
776 | |
888 | |
|
|
889 | Libev offers a compatibility emulation layer for libevent. It cannot |
|
|
890 | emulate the internals of libevent, so here are some usage hints: |
|
|
891 | |
|
|
892 | =over 4 |
|
|
893 | |
|
|
894 | =item * Use it by including <event.h>, as usual. |
|
|
895 | |
|
|
896 | =item * The following members are fully supported: ev_base, ev_callback, |
|
|
897 | ev_arg, ev_fd, ev_res, ev_events. |
|
|
898 | |
|
|
899 | =item * Avoid using ev_flags and the EVLIST_*-macros, while it is |
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|
900 | maintained by libev, it does not work exactly the same way as in libevent (consider |
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|
901 | it a private API). |
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|
902 | |
|
|
903 | =item * Priorities are not currently supported. Initialising priorities |
|
|
904 | will fail and all watchers will have the same priority, even though there |
|
|
905 | is an ev_pri field. |
|
|
906 | |
|
|
907 | =item * Other members are not supported. |
|
|
908 | |
|
|
909 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
|
|
910 | to use the libev header file and library. |
|
|
911 | |
|
|
912 | =back |
|
|
913 | |
|
|
914 | =head1 C++ SUPPORT |
|
|
915 | |
777 | TBD. |
916 | TBD. |
778 | |
917 | |
779 | =head1 C++ SUPPORT |
|
|
780 | |
|
|
781 | TBD. |
|
|
782 | |
|
|
783 | =head1 AUTHOR |
918 | =head1 AUTHOR |
784 | |
919 | |
785 | Marc Lehmann <libev@schmorp.de>. |
920 | Marc Lehmann <libev@schmorp.de>. |
786 | |
921 | |