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75 | 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, |
76 | as this indicates an incompatible change. Minor versions are usually |
76 | as this indicates an incompatible change. Minor versions are usually |
77 | 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 |
78 | not a problem. |
78 | not a problem. |
79 | |
79 | |
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80 | =item unsigned int ev_supported_backends () |
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81 | |
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82 | Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*> |
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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. |
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86 | |
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87 | =item unsigned int ev_recommended_backends () |
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88 | |
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89 | Return the set of all backends compiled into this binary of libev and also |
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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 |
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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. |
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95 | |
80 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
96 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
81 | |
97 | |
82 | 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 |
83 | 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 |
84 | and free memory (no surprises here). If it returns zero when memory |
100 | and free memory (no surprises here). If it returns zero when memory |
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119 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
135 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
120 | |
136 | |
121 | 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 |
122 | 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 |
123 | 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 |
124 | flags). |
140 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
125 | |
141 | |
126 | 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 |
127 | function. |
143 | function. |
128 | |
144 | |
129 | 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 |
130 | 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). |
131 | |
147 | |
132 | It supports the following flags: |
148 | It supports the following flags: |
133 | |
149 | |
134 | =over 4 |
150 | =over 4 |
135 | |
151 | |
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145 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
161 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
146 | 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 |
147 | 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 |
148 | around bugs. |
164 | around bugs. |
149 | |
165 | |
150 | =item C<EVMETHOD_SELECT> (portable select backend) |
166 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
151 | |
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 | |
152 | =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) |
153 | |
175 | |
154 | =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). |
155 | |
180 | |
156 | =item C<EVMETHOD_KQUEUE> (some bsds only) |
181 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
157 | |
182 | |
158 | =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). |
159 | |
187 | |
160 | =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 | |
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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 | |
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212 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
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213 | |
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214 | This is not implemented yet (and might never be). |
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215 | |
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216 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
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217 | |
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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 |
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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 | |
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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 |
161 | |
232 | |
162 | 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 |
163 | 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 |
164 | specified, any backend will do. |
235 | specified, most compiled-in backend will be tried, usually in reverse |
165 | |
236 | order of their flag values :) |
166 | =back |
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167 | |
237 | |
168 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
238 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
169 | |
239 | |
170 | 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 |
171 | 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 |
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188 | This function reinitialises the kernel state for backends that have |
258 | This function reinitialises the kernel state for backends that have |
189 | 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 |
190 | 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 |
191 | again makes little sense). |
261 | again makes little sense). |
192 | |
262 | |
193 | 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 |
194 | 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 |
195 | have to call it. |
265 | fork+exec, you don't have to call it. |
196 | |
266 | |
197 | 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 |
198 | 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 |
199 | quite nicely into a call to C<pthread_atfork>: |
269 | quite nicely into a call to C<pthread_atfork>: |
200 | |
270 | |
201 | pthread_atfork (0, 0, ev_default_fork); |
271 | pthread_atfork (0, 0, ev_default_fork); |
202 | |
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. |
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276 | |
203 | =item ev_loop_fork (loop) |
277 | =item ev_loop_fork (loop) |
204 | |
278 | |
205 | 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 |
206 | 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 |
207 | 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. |
208 | |
282 | |
209 | =item unsigned int ev_method (loop) |
283 | =item unsigned int ev_backend (loop) |
210 | |
284 | |
211 | 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 |
212 | use. |
286 | use. |
213 | |
287 | |
214 | =item ev_tstamp ev_now (loop) |
288 | =item ev_tstamp ev_now (loop) |
215 | |
289 | |
216 | 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 |
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322 | *) >>), 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 |
323 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
397 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
324 | |
398 | |
325 | 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 |
326 | 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 |
327 | reinitialise it or call its set method. |
401 | reinitialise it or call its set macro. |
328 | |
402 | |
329 | 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 |
330 | (watcher *)> macro. To see whether an event is outstanding (but the |
404 | (watcher *)> macro. To see whether an event is outstanding (but the |
331 | 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 |
332 | (watcher *)> macro. |
406 | (watcher *)> macro. |
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449 | 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 |
450 | to the same underlying file/socket etc. description (that is, they share |
524 | to the same underlying file/socket etc. description (that is, they share |
451 | the same underlying "file open"). |
525 | the same underlying "file open"). |
452 | |
526 | |
453 | 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 |
454 | (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 |
455 | EVMETHOD_POLL). |
529 | C<EVBACKEND_POLL>). |
456 | |
530 | |
457 | =over 4 |
531 | =over 4 |
458 | |
532 | |
459 | =item ev_io_init (ev_io *, callback, int fd, int events) |
533 | =item ev_io_init (ev_io *, callback, int fd, int events) |
460 | |
534 | |
461 | =item ev_io_set (ev_io *, int fd, int events) |
535 | =item ev_io_set (ev_io *, int fd, int events) |
462 | |
536 | |
463 | 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 |
464 | 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 | |
465 | EV_WRITE> to receive the given events. |
539 | EV_WRITE> to receive the given events. |
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540 | |
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541 | Please note that most of the more scalable backend mechanisms (for example |
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542 | epoll and solaris ports) can result in spurious readyness notifications |
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543 | for file descriptors, so you practically need to use non-blocking I/O (and |
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544 | treat callback invocation as hint only), or retest separately with a safe |
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545 | interface before doing I/O (XLib can do this), or force the use of either |
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546 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this |
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547 | problem. Also note that it is quite easy to have your callback invoked |
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548 | when the readyness condition is no longer valid even when employing |
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549 | typical ways of handling events, so its a good idea to use non-blocking |
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550 | I/O unconditionally. |
466 | |
551 | |
467 | =back |
552 | =back |
468 | |
553 | |
469 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
554 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
470 | |
555 | |