… | |
… | |
45 | |
45 | |
46 | Libev represents time as a single floating point number, representing the |
46 | Libev represents time as a single floating point number, representing the |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
49 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
49 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
50 | to the double type in C. |
50 | to the C<double> type in C, and when you need to do any calculations on |
|
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51 | it, you should treat it as such. |
|
|
52 | |
51 | |
53 | |
52 | =head1 GLOBAL FUNCTIONS |
54 | =head1 GLOBAL FUNCTIONS |
53 | |
55 | |
54 | These functions can be called anytime, even before initialising the |
56 | These functions can be called anytime, even before initialising the |
55 | library in any way. |
57 | library in any way. |
… | |
… | |
75 | Usually, it's a good idea to terminate if the major versions mismatch, |
77 | Usually, it's a good idea to terminate if the major versions mismatch, |
76 | as this indicates an incompatible change. Minor versions are usually |
78 | as this indicates an incompatible change. Minor versions are usually |
77 | compatible to older versions, so a larger minor version alone is usually |
79 | compatible to older versions, so a larger minor version alone is usually |
78 | not a problem. |
80 | not a problem. |
79 | |
81 | |
|
|
82 | Example: make sure we haven't accidentally been linked against the wrong |
|
|
83 | version: |
|
|
84 | |
|
|
85 | assert (("libev version mismatch", |
|
|
86 | ev_version_major () == EV_VERSION_MAJOR |
|
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87 | && ev_version_minor () >= EV_VERSION_MINOR)); |
|
|
88 | |
80 | =item unsigned int ev_supported_backends () |
89 | =item unsigned int ev_supported_backends () |
81 | |
90 | |
82 | Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*> |
91 | Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*> |
83 | value) compiled into this binary of libev (independent of their |
92 | value) compiled into this binary of libev (independent of their |
84 | availability on the system you are running on). See C<ev_default_loop> for |
93 | availability on the system you are running on). See C<ev_default_loop> for |
85 | a description of the set values. |
94 | a description of the set values. |
|
|
95 | |
|
|
96 | Example: make sure we have the epoll method, because yeah this is cool and |
|
|
97 | a must have and can we have a torrent of it please!!!11 |
|
|
98 | |
|
|
99 | assert (("sorry, no epoll, no sex", |
|
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100 | ev_supported_backends () & EVBACKEND_EPOLL)); |
86 | |
101 | |
87 | =item unsigned int ev_recommended_backends () |
102 | =item unsigned int ev_recommended_backends () |
88 | |
103 | |
89 | Return the set of all backends compiled into this binary of libev and also |
104 | 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 |
105 | recommended for this platform. This set is often smaller than the one |
91 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
106 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
92 | most BSDs and will not be autodetected unless you explicitly request it |
107 | 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 |
108 | (assuming you know what you are doing). This is the set of backends that |
94 | C<EVFLAG_AUTO> will probe for. |
109 | libev will probe for if you specify no backends explicitly. |
|
|
110 | |
|
|
111 | =item unsigned int ev_embeddable_backends () |
|
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112 | |
|
|
113 | Returns the set of backends that are embeddable in other event loops. This |
|
|
114 | is the theoretical, all-platform, value. To find which backends |
|
|
115 | might be supported on the current system, you would need to look at |
|
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116 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
|
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117 | recommended ones. |
|
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118 | |
|
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119 | See the description of C<ev_embed> watchers for more info. |
95 | |
120 | |
96 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
121 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
97 | |
122 | |
98 | Sets the allocation function to use (the prototype is similar to the |
123 | Sets the allocation function to use (the prototype is similar to the |
99 | realloc C function, the semantics are identical). It is used to allocate |
124 | realloc C function, the semantics are identical). It is used to allocate |
… | |
… | |
102 | destructive action. The default is your system realloc function. |
127 | destructive action. The default is your system realloc function. |
103 | |
128 | |
104 | You could override this function in high-availability programs to, say, |
129 | You could override this function in high-availability programs to, say, |
105 | free some memory if it cannot allocate memory, to use a special allocator, |
130 | free some memory if it cannot allocate memory, to use a special allocator, |
106 | or even to sleep a while and retry until some memory is available. |
131 | or even to sleep a while and retry until some memory is available. |
|
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132 | |
|
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133 | Example: replace the libev allocator with one that waits a bit and then |
|
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134 | retries: better than mine). |
|
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135 | |
|
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136 | static void * |
|
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137 | persistent_realloc (void *ptr, long size) |
|
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138 | { |
|
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139 | for (;;) |
|
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140 | { |
|
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141 | void *newptr = realloc (ptr, size); |
|
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142 | |
|
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143 | if (newptr) |
|
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144 | return newptr; |
|
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145 | |
|
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146 | sleep (60); |
|
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147 | } |
|
|
148 | } |
|
|
149 | |
|
|
150 | ... |
|
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151 | ev_set_allocator (persistent_realloc); |
107 | |
152 | |
108 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
153 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
109 | |
154 | |
110 | Set the callback function to call on a retryable syscall error (such |
155 | Set the callback function to call on a retryable syscall error (such |
111 | as failed select, poll, epoll_wait). The message is a printable string |
156 | as failed select, poll, epoll_wait). The message is a printable string |
… | |
… | |
113 | callback is set, then libev will expect it to remedy the sitution, no |
158 | callback is set, then libev will expect it to remedy the sitution, no |
114 | matter what, when it returns. That is, libev will generally retry the |
159 | matter what, when it returns. That is, libev will generally retry the |
115 | requested operation, or, if the condition doesn't go away, do bad stuff |
160 | requested operation, or, if the condition doesn't go away, do bad stuff |
116 | (such as abort). |
161 | (such as abort). |
117 | |
162 | |
|
|
163 | Example: do the same thing as libev does internally: |
|
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164 | |
|
|
165 | static void |
|
|
166 | fatal_error (const char *msg) |
|
|
167 | { |
|
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168 | perror (msg); |
|
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169 | abort (); |
|
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170 | } |
|
|
171 | |
|
|
172 | ... |
|
|
173 | ev_set_syserr_cb (fatal_error); |
|
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174 | |
118 | =back |
175 | =back |
119 | |
176 | |
120 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
177 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
121 | |
178 | |
122 | An event loop is described by a C<struct ev_loop *>. The library knows two |
179 | An event loop is described by a C<struct ev_loop *>. The library knows two |
… | |
… | |
141 | |
198 | |
142 | If you don't know what event loop to use, use the one returned from this |
199 | If you don't know what event loop to use, use the one returned from this |
143 | function. |
200 | function. |
144 | |
201 | |
145 | The flags argument can be used to specify special behaviour or specific |
202 | The flags argument can be used to specify special behaviour or specific |
146 | backends to use, and is usually specified as C<0> (or EVFLAG_AUTO). |
203 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
147 | |
204 | |
148 | It supports the following flags: |
205 | The following flags are supported: |
149 | |
206 | |
150 | =over 4 |
207 | =over 4 |
151 | |
208 | |
152 | =item C<EVFLAG_AUTO> |
209 | =item C<EVFLAG_AUTO> |
153 | |
210 | |
… | |
… | |
189 | result in some caching, there is still a syscall per such incident |
246 | result in some caching, there is still a syscall per such incident |
190 | (because the fd could point to a different file description now), so its |
247 | (because the fd could point to a different file description now), so its |
191 | best to avoid that. Also, dup()ed file descriptors might not work very |
248 | best to avoid that. Also, dup()ed file descriptors might not work very |
192 | well if you register events for both fds. |
249 | well if you register events for both fds. |
193 | |
250 | |
|
|
251 | Please note that epoll sometimes generates spurious notifications, so you |
|
|
252 | need to use non-blocking I/O or other means to avoid blocking when no data |
|
|
253 | (or space) is available. |
|
|
254 | |
194 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
255 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
195 | |
256 | |
196 | Kqueue deserves special mention, as at the time of this writing, it |
257 | Kqueue deserves special mention, as at the time of this writing, it |
197 | was broken on all BSDs except NetBSD (usually it doesn't work with |
258 | was broken on all BSDs except NetBSD (usually it doesn't work with |
198 | anything but sockets and pipes, except on Darwin, where of course its |
259 | anything but sockets and pipes, except on Darwin, where of course its |
199 | completely useless). For this reason its not being "autodetected" unless |
260 | completely useless). For this reason its not being "autodetected" |
200 | you explicitly specify the flags (i.e. you don't use EVFLAG_AUTO). |
261 | unless you explicitly specify it explicitly in the flags (i.e. using |
|
|
262 | C<EVBACKEND_KQUEUE>). |
201 | |
263 | |
202 | It scales in the same way as the epoll backend, but the interface to the |
264 | It scales in the same way as the epoll backend, but the interface to the |
203 | kernel is more efficient (which says nothing about its actual speed, of |
265 | kernel is more efficient (which says nothing about its actual speed, of |
204 | course). While starting and stopping an I/O watcher does not cause an |
266 | course). While starting and stopping an I/O watcher does not cause an |
205 | extra syscall as with epoll, it still adds up to four event changes per |
267 | extra syscall as with epoll, it still adds up to four event changes per |
… | |
… | |
212 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
274 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
213 | |
275 | |
214 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
276 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
215 | it's really slow, but it still scales very well (O(active_fds)). |
277 | it's really slow, but it still scales very well (O(active_fds)). |
216 | |
278 | |
|
|
279 | Please note that solaris ports can result in a lot of spurious |
|
|
280 | notifications, so you need to use non-blocking I/O or other means to avoid |
|
|
281 | blocking when no data (or space) is available. |
|
|
282 | |
217 | =item C<EVBACKEND_ALL> |
283 | =item C<EVBACKEND_ALL> |
218 | |
284 | |
219 | Try all backends (even potentially broken ones that wouldn't be tried |
285 | Try all backends (even potentially broken ones that wouldn't be tried |
220 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
286 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
221 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
287 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
… | |
… | |
225 | If one or more of these are ored into the flags value, then only these |
291 | If one or more of these are ored into the flags value, then only these |
226 | backends will be tried (in the reverse order as given here). If none are |
292 | backends will be tried (in the reverse order as given here). If none are |
227 | specified, most compiled-in backend will be tried, usually in reverse |
293 | specified, most compiled-in backend will be tried, usually in reverse |
228 | order of their flag values :) |
294 | order of their flag values :) |
229 | |
295 | |
|
|
296 | The most typical usage is like this: |
|
|
297 | |
|
|
298 | if (!ev_default_loop (0)) |
|
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299 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
300 | |
|
|
301 | Restrict libev to the select and poll backends, and do not allow |
|
|
302 | environment settings to be taken into account: |
|
|
303 | |
|
|
304 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
305 | |
|
|
306 | Use whatever libev has to offer, but make sure that kqueue is used if |
|
|
307 | available (warning, breaks stuff, best use only with your own private |
|
|
308 | event loop and only if you know the OS supports your types of fds): |
|
|
309 | |
|
|
310 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
311 | |
230 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
312 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
231 | |
313 | |
232 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
314 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
233 | always distinct from the default loop. Unlike the default loop, it cannot |
315 | always distinct from the default loop. Unlike the default loop, it cannot |
234 | handle signal and child watchers, and attempts to do so will be greeted by |
316 | handle signal and child watchers, and attempts to do so will be greeted by |
235 | undefined behaviour (or a failed assertion if assertions are enabled). |
317 | undefined behaviour (or a failed assertion if assertions are enabled). |
236 | |
318 | |
|
|
319 | Example: try to create a event loop that uses epoll and nothing else. |
|
|
320 | |
|
|
321 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
|
|
322 | if (!epoller) |
|
|
323 | fatal ("no epoll found here, maybe it hides under your chair"); |
|
|
324 | |
237 | =item ev_default_destroy () |
325 | =item ev_default_destroy () |
238 | |
326 | |
239 | Destroys the default loop again (frees all memory and kernel state |
327 | Destroys the default loop again (frees all memory and kernel state |
240 | etc.). This stops all registered event watchers (by not touching them in |
328 | etc.). None of the active event watchers will be stopped in the normal |
241 | any way whatsoever, although you cannot rely on this :). |
329 | sense, so e.g. C<ev_is_active> might still return true. It is your |
|
|
330 | responsibility to either stop all watchers cleanly yoursef I<before> |
|
|
331 | calling this function, or cope with the fact afterwards (which is usually |
|
|
332 | the easiest thing, youc na just ignore the watchers and/or C<free ()> them |
|
|
333 | for example). |
242 | |
334 | |
243 | =item ev_loop_destroy (loop) |
335 | =item ev_loop_destroy (loop) |
244 | |
336 | |
245 | Like C<ev_default_destroy>, but destroys an event loop created by an |
337 | Like C<ev_default_destroy>, but destroys an event loop created by an |
246 | earlier call to C<ev_loop_new>. |
338 | earlier call to C<ev_loop_new>. |
… | |
… | |
278 | use. |
370 | use. |
279 | |
371 | |
280 | =item ev_tstamp ev_now (loop) |
372 | =item ev_tstamp ev_now (loop) |
281 | |
373 | |
282 | Returns the current "event loop time", which is the time the event loop |
374 | Returns the current "event loop time", which is the time the event loop |
283 | got events and started processing them. This timestamp does not change |
375 | received events and started processing them. This timestamp does not |
284 | as long as callbacks are being processed, and this is also the base time |
376 | change as long as callbacks are being processed, and this is also the base |
285 | used for relative timers. You can treat it as the timestamp of the event |
377 | time used for relative timers. You can treat it as the timestamp of the |
286 | occuring (or more correctly, the mainloop finding out about it). |
378 | event occuring (or more correctly, libev finding out about it). |
287 | |
379 | |
288 | =item ev_loop (loop, int flags) |
380 | =item ev_loop (loop, int flags) |
289 | |
381 | |
290 | Finally, this is it, the event handler. This function usually is called |
382 | Finally, this is it, the event handler. This function usually is called |
291 | after you initialised all your watchers and you want to start handling |
383 | after you initialised all your watchers and you want to start handling |
292 | events. |
384 | events. |
293 | |
385 | |
294 | If the flags argument is specified as 0, it will not return until either |
386 | If the flags argument is specified as C<0>, it will not return until |
295 | no event watchers are active anymore or C<ev_unloop> was called. |
387 | either no event watchers are active anymore or C<ev_unloop> was called. |
|
|
388 | |
|
|
389 | Please note that an explicit C<ev_unloop> is usually better than |
|
|
390 | relying on all watchers to be stopped when deciding when a program has |
|
|
391 | finished (especially in interactive programs), but having a program that |
|
|
392 | automatically loops as long as it has to and no longer by virtue of |
|
|
393 | relying on its watchers stopping correctly is a thing of beauty. |
296 | |
394 | |
297 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
395 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
298 | those events and any outstanding ones, but will not block your process in |
396 | those events and any outstanding ones, but will not block your process in |
299 | case there are no events and will return after one iteration of the loop. |
397 | case there are no events and will return after one iteration of the loop. |
300 | |
398 | |
301 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
399 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
302 | neccessary) and will handle those and any outstanding ones. It will block |
400 | neccessary) and will handle those and any outstanding ones. It will block |
303 | your process until at least one new event arrives, and will return after |
401 | your process until at least one new event arrives, and will return after |
304 | one iteration of the loop. |
402 | one iteration of the loop. This is useful if you are waiting for some |
|
|
403 | external event in conjunction with something not expressible using other |
|
|
404 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
|
|
405 | usually a better approach for this kind of thing. |
305 | |
406 | |
306 | This flags value could be used to implement alternative looping |
|
|
307 | constructs, but the C<prepare> and C<check> watchers provide a better and |
|
|
308 | more generic mechanism. |
|
|
309 | |
|
|
310 | Here are the gory details of what ev_loop does: |
407 | Here are the gory details of what C<ev_loop> does: |
311 | |
408 | |
312 | 1. If there are no active watchers (reference count is zero), return. |
409 | * If there are no active watchers (reference count is zero), return. |
313 | 2. Queue and immediately call all prepare watchers. |
410 | - Queue prepare watchers and then call all outstanding watchers. |
314 | 3. If we have been forked, recreate the kernel state. |
411 | - If we have been forked, recreate the kernel state. |
315 | 4. Update the kernel state with all outstanding changes. |
412 | - Update the kernel state with all outstanding changes. |
316 | 5. Update the "event loop time". |
413 | - Update the "event loop time". |
317 | 6. Calculate for how long to block. |
414 | - Calculate for how long to block. |
318 | 7. Block the process, waiting for events. |
415 | - Block the process, waiting for any events. |
|
|
416 | - Queue all outstanding I/O (fd) events. |
319 | 8. Update the "event loop time" and do time jump handling. |
417 | - Update the "event loop time" and do time jump handling. |
320 | 9. Queue all outstanding timers. |
418 | - Queue all outstanding timers. |
321 | 10. Queue all outstanding periodics. |
419 | - Queue all outstanding periodics. |
322 | 11. If no events are pending now, queue all idle watchers. |
420 | - If no events are pending now, queue all idle watchers. |
323 | 12. Queue all check watchers. |
421 | - Queue all check watchers. |
324 | 13. Call all queued watchers in reverse order (i.e. check watchers first). |
422 | - Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
423 | Signals and child watchers are implemented as I/O watchers, and will |
|
|
424 | be handled here by queueing them when their watcher gets executed. |
325 | 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
425 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
326 | was used, return, otherwise continue with step #1. |
426 | were used, return, otherwise continue with step *. |
|
|
427 | |
|
|
428 | Example: queue some jobs and then loop until no events are outsanding |
|
|
429 | anymore. |
|
|
430 | |
|
|
431 | ... queue jobs here, make sure they register event watchers as long |
|
|
432 | ... as they still have work to do (even an idle watcher will do..) |
|
|
433 | ev_loop (my_loop, 0); |
|
|
434 | ... jobs done. yeah! |
327 | |
435 | |
328 | =item ev_unloop (loop, how) |
436 | =item ev_unloop (loop, how) |
329 | |
437 | |
330 | Can be used to make a call to C<ev_loop> return early (but only after it |
438 | Can be used to make a call to C<ev_loop> return early (but only after it |
331 | has processed all outstanding events). The C<how> argument must be either |
439 | has processed all outstanding events). The C<how> argument must be either |
… | |
… | |
345 | visible to the libev user and should not keep C<ev_loop> from exiting if |
453 | visible to the libev user and should not keep C<ev_loop> from exiting if |
346 | no event watchers registered by it are active. It is also an excellent |
454 | no event watchers registered by it are active. It is also an excellent |
347 | way to do this for generic recurring timers or from within third-party |
455 | way to do this for generic recurring timers or from within third-party |
348 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
456 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
349 | |
457 | |
|
|
458 | Example: create a signal watcher, but keep it from keeping C<ev_loop> |
|
|
459 | running when nothing else is active. |
|
|
460 | |
|
|
461 | struct dv_signal exitsig; |
|
|
462 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
|
|
463 | ev_signal_start (myloop, &exitsig); |
|
|
464 | evf_unref (myloop); |
|
|
465 | |
|
|
466 | Example: for some weird reason, unregister the above signal handler again. |
|
|
467 | |
|
|
468 | ev_ref (myloop); |
|
|
469 | ev_signal_stop (myloop, &exitsig); |
|
|
470 | |
350 | =back |
471 | =back |
|
|
472 | |
351 | |
473 | |
352 | =head1 ANATOMY OF A WATCHER |
474 | =head1 ANATOMY OF A WATCHER |
353 | |
475 | |
354 | A watcher is a structure that you create and register to record your |
476 | A watcher is a structure that you create and register to record your |
355 | interest in some event. For instance, if you want to wait for STDIN to |
477 | interest in some event. For instance, if you want to wait for STDIN to |
… | |
… | |
388 | *) >>), and you can stop watching for events at any time by calling the |
510 | *) >>), and you can stop watching for events at any time by calling the |
389 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
511 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
390 | |
512 | |
391 | As long as your watcher is active (has been started but not stopped) you |
513 | As long as your watcher is active (has been started but not stopped) you |
392 | must not touch the values stored in it. Most specifically you must never |
514 | must not touch the values stored in it. Most specifically you must never |
393 | reinitialise it or call its set macro. |
515 | reinitialise it or call its C<set> macro. |
394 | |
|
|
395 | You can check whether an event is active by calling the C<ev_is_active |
|
|
396 | (watcher *)> macro. To see whether an event is outstanding (but the |
|
|
397 | callback for it has not been called yet) you can use the C<ev_is_pending |
|
|
398 | (watcher *)> macro. |
|
|
399 | |
516 | |
400 | Each and every callback receives the event loop pointer as first, the |
517 | Each and every callback receives the event loop pointer as first, the |
401 | registered watcher structure as second, and a bitset of received events as |
518 | registered watcher structure as second, and a bitset of received events as |
402 | third argument. |
519 | third argument. |
403 | |
520 | |
… | |
… | |
427 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
544 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
428 | |
545 | |
429 | =item C<EV_CHILD> |
546 | =item C<EV_CHILD> |
430 | |
547 | |
431 | The pid specified in the C<ev_child> watcher has received a status change. |
548 | The pid specified in the C<ev_child> watcher has received a status change. |
|
|
549 | |
|
|
550 | =item C<EV_STAT> |
|
|
551 | |
|
|
552 | The path specified in the C<ev_stat> watcher changed its attributes somehow. |
432 | |
553 | |
433 | =item C<EV_IDLE> |
554 | =item C<EV_IDLE> |
434 | |
555 | |
435 | The C<ev_idle> watcher has determined that you have nothing better to do. |
556 | The C<ev_idle> watcher has determined that you have nothing better to do. |
436 | |
557 | |
… | |
… | |
460 | with the error from read() or write(). This will not work in multithreaded |
581 | with the error from read() or write(). This will not work in multithreaded |
461 | programs, though, so beware. |
582 | programs, though, so beware. |
462 | |
583 | |
463 | =back |
584 | =back |
464 | |
585 | |
|
|
586 | =head2 GENERIC WATCHER FUNCTIONS |
|
|
587 | |
|
|
588 | In the following description, C<TYPE> stands for the watcher type, |
|
|
589 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
|
|
590 | |
|
|
591 | =over 4 |
|
|
592 | |
|
|
593 | =item C<ev_init> (ev_TYPE *watcher, callback) |
|
|
594 | |
|
|
595 | This macro initialises the generic portion of a watcher. The contents |
|
|
596 | of the watcher object can be arbitrary (so C<malloc> will do). Only |
|
|
597 | the generic parts of the watcher are initialised, you I<need> to call |
|
|
598 | the type-specific C<ev_TYPE_set> macro afterwards to initialise the |
|
|
599 | type-specific parts. For each type there is also a C<ev_TYPE_init> macro |
|
|
600 | which rolls both calls into one. |
|
|
601 | |
|
|
602 | You can reinitialise a watcher at any time as long as it has been stopped |
|
|
603 | (or never started) and there are no pending events outstanding. |
|
|
604 | |
|
|
605 | The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
|
|
606 | int revents)>. |
|
|
607 | |
|
|
608 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
|
|
609 | |
|
|
610 | This macro initialises the type-specific parts of a watcher. You need to |
|
|
611 | call C<ev_init> at least once before you call this macro, but you can |
|
|
612 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
|
|
613 | macro on a watcher that is active (it can be pending, however, which is a |
|
|
614 | difference to the C<ev_init> macro). |
|
|
615 | |
|
|
616 | Although some watcher types do not have type-specific arguments |
|
|
617 | (e.g. C<ev_prepare>) you still need to call its C<set> macro. |
|
|
618 | |
|
|
619 | =item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args]) |
|
|
620 | |
|
|
621 | This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro |
|
|
622 | calls into a single call. This is the most convinient method to initialise |
|
|
623 | a watcher. The same limitations apply, of course. |
|
|
624 | |
|
|
625 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
|
|
626 | |
|
|
627 | Starts (activates) the given watcher. Only active watchers will receive |
|
|
628 | events. If the watcher is already active nothing will happen. |
|
|
629 | |
|
|
630 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
|
|
631 | |
|
|
632 | Stops the given watcher again (if active) and clears the pending |
|
|
633 | status. It is possible that stopped watchers are pending (for example, |
|
|
634 | non-repeating timers are being stopped when they become pending), but |
|
|
635 | C<ev_TYPE_stop> ensures that the watcher is neither active nor pending. If |
|
|
636 | you want to free or reuse the memory used by the watcher it is therefore a |
|
|
637 | good idea to always call its C<ev_TYPE_stop> function. |
|
|
638 | |
|
|
639 | =item bool ev_is_active (ev_TYPE *watcher) |
|
|
640 | |
|
|
641 | Returns a true value iff the watcher is active (i.e. it has been started |
|
|
642 | and not yet been stopped). As long as a watcher is active you must not modify |
|
|
643 | it. |
|
|
644 | |
|
|
645 | =item bool ev_is_pending (ev_TYPE *watcher) |
|
|
646 | |
|
|
647 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
|
|
648 | events but its callback has not yet been invoked). As long as a watcher |
|
|
649 | is pending (but not active) you must not call an init function on it (but |
|
|
650 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
|
|
651 | libev (e.g. you cnanot C<free ()> it). |
|
|
652 | |
|
|
653 | =item callback = ev_cb (ev_TYPE *watcher) |
|
|
654 | |
|
|
655 | Returns the callback currently set on the watcher. |
|
|
656 | |
|
|
657 | =item ev_cb_set (ev_TYPE *watcher, callback) |
|
|
658 | |
|
|
659 | Change the callback. You can change the callback at virtually any time |
|
|
660 | (modulo threads). |
|
|
661 | |
|
|
662 | =back |
|
|
663 | |
|
|
664 | |
465 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
665 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
466 | |
666 | |
467 | Each watcher has, by default, a member C<void *data> that you can change |
667 | Each watcher has, by default, a member C<void *data> that you can change |
468 | and read at any time, libev will completely ignore it. This can be used |
668 | and read at any time, libev will completely ignore it. This can be used |
469 | to associate arbitrary data with your watcher. If you need more data and |
669 | to associate arbitrary data with your watcher. If you need more data and |
… | |
… | |
493 | |
693 | |
494 | |
694 | |
495 | =head1 WATCHER TYPES |
695 | =head1 WATCHER TYPES |
496 | |
696 | |
497 | This section describes each watcher in detail, but will not repeat |
697 | This section describes each watcher in detail, but will not repeat |
498 | information given in the last section. |
698 | information given in the last section. Any initialisation/set macros, |
|
|
699 | functions and members specific to the watcher type are explained. |
499 | |
700 | |
|
|
701 | Members are additionally marked with either I<[read-only]>, meaning that, |
|
|
702 | while the watcher is active, you can look at the member and expect some |
|
|
703 | sensible content, but you must not modify it (you can modify it while the |
|
|
704 | watcher is stopped to your hearts content), or I<[read-write]>, which |
|
|
705 | means you can expect it to have some sensible content while the watcher |
|
|
706 | is active, but you can also modify it. Modifying it may not do something |
|
|
707 | sensible or take immediate effect (or do anything at all), but libev will |
|
|
708 | not crash or malfunction in any way. |
|
|
709 | |
|
|
710 | |
500 | =head2 C<ev_io> - is this file descriptor readable or writable |
711 | =head2 C<ev_io> - is this file descriptor readable or writable? |
501 | |
712 | |
502 | I/O watchers check whether a file descriptor is readable or writable |
713 | I/O watchers check whether a file descriptor is readable or writable |
503 | in each iteration of the event loop (This behaviour is called |
714 | in each iteration of the event loop, or, more precisely, when reading |
504 | level-triggering because you keep receiving events as long as the |
715 | would not block the process and writing would at least be able to write |
505 | condition persists. Remember you can stop the watcher if you don't want to |
716 | some data. This behaviour is called level-triggering because you keep |
506 | act on the event and neither want to receive future events). |
717 | receiving events as long as the condition persists. Remember you can stop |
|
|
718 | the watcher if you don't want to act on the event and neither want to |
|
|
719 | receive future events. |
507 | |
720 | |
508 | In general you can register as many read and/or write event watchers per |
721 | In general you can register as many read and/or write event watchers per |
509 | fd as you want (as long as you don't confuse yourself). Setting all file |
722 | fd as you want (as long as you don't confuse yourself). Setting all file |
510 | descriptors to non-blocking mode is also usually a good idea (but not |
723 | descriptors to non-blocking mode is also usually a good idea (but not |
511 | required if you know what you are doing). |
724 | required if you know what you are doing). |
512 | |
725 | |
513 | You have to be careful with dup'ed file descriptors, though. Some backends |
726 | You have to be careful with dup'ed file descriptors, though. Some backends |
514 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
727 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
515 | descriptors correctly if you register interest in two or more fds pointing |
728 | descriptors correctly if you register interest in two or more fds pointing |
516 | to the same underlying file/socket etc. description (that is, they share |
729 | to the same underlying file/socket/etc. description (that is, they share |
517 | the same underlying "file open"). |
730 | the same underlying "file open"). |
518 | |
731 | |
519 | If you must do this, then force the use of a known-to-be-good backend |
732 | If you must do this, then force the use of a known-to-be-good backend |
520 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
733 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
521 | C<EVBACKEND_POLL>). |
734 | C<EVBACKEND_POLL>). |
522 | |
735 | |
|
|
736 | Another thing you have to watch out for is that it is quite easy to |
|
|
737 | receive "spurious" readyness notifications, that is your callback might |
|
|
738 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
|
|
739 | because there is no data. Not only are some backends known to create a |
|
|
740 | lot of those (for example solaris ports), it is very easy to get into |
|
|
741 | this situation even with a relatively standard program structure. Thus |
|
|
742 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
|
|
743 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
|
|
744 | |
|
|
745 | If you cannot run the fd in non-blocking mode (for example you should not |
|
|
746 | play around with an Xlib connection), then you have to seperately re-test |
|
|
747 | wether a file descriptor is really ready with a known-to-be good interface |
|
|
748 | such as poll (fortunately in our Xlib example, Xlib already does this on |
|
|
749 | its own, so its quite safe to use). |
|
|
750 | |
523 | =over 4 |
751 | =over 4 |
524 | |
752 | |
525 | =item ev_io_init (ev_io *, callback, int fd, int events) |
753 | =item ev_io_init (ev_io *, callback, int fd, int events) |
526 | |
754 | |
527 | =item ev_io_set (ev_io *, int fd, int events) |
755 | =item ev_io_set (ev_io *, int fd, int events) |
528 | |
756 | |
529 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
757 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
530 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
758 | rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or |
531 | EV_WRITE> to receive the given events. |
759 | C<EV_READ | EV_WRITE> to receive the given events. |
|
|
760 | |
|
|
761 | =item int fd [read-only] |
|
|
762 | |
|
|
763 | The file descriptor being watched. |
|
|
764 | |
|
|
765 | =item int events [read-only] |
|
|
766 | |
|
|
767 | The events being watched. |
532 | |
768 | |
533 | =back |
769 | =back |
534 | |
770 | |
|
|
771 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
|
|
772 | readable, but only once. Since it is likely line-buffered, you could |
|
|
773 | attempt to read a whole line in the callback: |
|
|
774 | |
|
|
775 | static void |
|
|
776 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
777 | { |
|
|
778 | ev_io_stop (loop, w); |
|
|
779 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
|
|
780 | } |
|
|
781 | |
|
|
782 | ... |
|
|
783 | struct ev_loop *loop = ev_default_init (0); |
|
|
784 | struct ev_io stdin_readable; |
|
|
785 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
|
|
786 | ev_io_start (loop, &stdin_readable); |
|
|
787 | ev_loop (loop, 0); |
|
|
788 | |
|
|
789 | |
535 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
790 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
536 | |
791 | |
537 | Timer watchers are simple relative timers that generate an event after a |
792 | Timer watchers are simple relative timers that generate an event after a |
538 | given time, and optionally repeating in regular intervals after that. |
793 | given time, and optionally repeating in regular intervals after that. |
539 | |
794 | |
540 | The timers are based on real time, that is, if you register an event that |
795 | The timers are based on real time, that is, if you register an event that |
… | |
… | |
581 | |
836 | |
582 | If the timer is repeating, either start it if necessary (with the repeat |
837 | If the timer is repeating, either start it if necessary (with the repeat |
583 | value), or reset the running timer to the repeat value. |
838 | value), or reset the running timer to the repeat value. |
584 | |
839 | |
585 | This sounds a bit complicated, but here is a useful and typical |
840 | This sounds a bit complicated, but here is a useful and typical |
586 | example: Imagine you have a tcp connection and you want a so-called idle |
841 | example: Imagine you have a tcp connection and you want a so-called |
587 | timeout, that is, you want to be called when there have been, say, 60 |
842 | idle timeout, that is, you want to be called when there have been, |
588 | seconds of inactivity on the socket. The easiest way to do this is to |
843 | say, 60 seconds of inactivity on the socket. The easiest way to do |
589 | configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each |
844 | this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling |
590 | time you successfully read or write some data. If you go into an idle |
845 | C<ev_timer_again> each time you successfully read or write some data. If |
591 | state where you do not expect data to travel on the socket, you can stop |
846 | you go into an idle state where you do not expect data to travel on the |
592 | the timer, and again will automatically restart it if need be. |
847 | socket, you can stop the timer, and again will automatically restart it if |
|
|
848 | need be. |
|
|
849 | |
|
|
850 | You can also ignore the C<after> value and C<ev_timer_start> altogether |
|
|
851 | and only ever use the C<repeat> value: |
|
|
852 | |
|
|
853 | ev_timer_init (timer, callback, 0., 5.); |
|
|
854 | ev_timer_again (loop, timer); |
|
|
855 | ... |
|
|
856 | timer->again = 17.; |
|
|
857 | ev_timer_again (loop, timer); |
|
|
858 | ... |
|
|
859 | timer->again = 10.; |
|
|
860 | ev_timer_again (loop, timer); |
|
|
861 | |
|
|
862 | This is more efficient then stopping/starting the timer eahc time you want |
|
|
863 | to modify its timeout value. |
|
|
864 | |
|
|
865 | =item ev_tstamp repeat [read-write] |
|
|
866 | |
|
|
867 | The current C<repeat> value. Will be used each time the watcher times out |
|
|
868 | or C<ev_timer_again> is called and determines the next timeout (if any), |
|
|
869 | which is also when any modifications are taken into account. |
593 | |
870 | |
594 | =back |
871 | =back |
595 | |
872 | |
|
|
873 | Example: create a timer that fires after 60 seconds. |
|
|
874 | |
|
|
875 | static void |
|
|
876 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
877 | { |
|
|
878 | .. one minute over, w is actually stopped right here |
|
|
879 | } |
|
|
880 | |
|
|
881 | struct ev_timer mytimer; |
|
|
882 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
|
|
883 | ev_timer_start (loop, &mytimer); |
|
|
884 | |
|
|
885 | Example: create a timeout timer that times out after 10 seconds of |
|
|
886 | inactivity. |
|
|
887 | |
|
|
888 | static void |
|
|
889 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
890 | { |
|
|
891 | .. ten seconds without any activity |
|
|
892 | } |
|
|
893 | |
|
|
894 | struct ev_timer mytimer; |
|
|
895 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
|
|
896 | ev_timer_again (&mytimer); /* start timer */ |
|
|
897 | ev_loop (loop, 0); |
|
|
898 | |
|
|
899 | // and in some piece of code that gets executed on any "activity": |
|
|
900 | // reset the timeout to start ticking again at 10 seconds |
|
|
901 | ev_timer_again (&mytimer); |
|
|
902 | |
|
|
903 | |
596 | =head2 C<ev_periodic> - to cron or not to cron |
904 | =head2 C<ev_periodic> - to cron or not to cron? |
597 | |
905 | |
598 | Periodic watchers are also timers of a kind, but they are very versatile |
906 | Periodic watchers are also timers of a kind, but they are very versatile |
599 | (and unfortunately a bit complex). |
907 | (and unfortunately a bit complex). |
600 | |
908 | |
601 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
909 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
602 | but on wallclock time (absolute time). You can tell a periodic watcher |
910 | but on wallclock time (absolute time). You can tell a periodic watcher |
603 | to trigger "at" some specific point in time. For example, if you tell a |
911 | to trigger "at" some specific point in time. For example, if you tell a |
604 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
912 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
605 | + 10.>) and then reset your system clock to the last year, then it will |
913 | + 10.>) and then reset your system clock to the last year, then it will |
606 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
914 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
607 | roughly 10 seconds later and of course not if you reset your system time |
915 | roughly 10 seconds later and of course not if you reset your system time |
608 | again). |
916 | again). |
609 | |
917 | |
… | |
… | |
693 | Simply stops and restarts the periodic watcher again. This is only useful |
1001 | Simply stops and restarts the periodic watcher again. This is only useful |
694 | when you changed some parameters or the reschedule callback would return |
1002 | when you changed some parameters or the reschedule callback would return |
695 | a different time than the last time it was called (e.g. in a crond like |
1003 | a different time than the last time it was called (e.g. in a crond like |
696 | program when the crontabs have changed). |
1004 | program when the crontabs have changed). |
697 | |
1005 | |
|
|
1006 | =item ev_tstamp interval [read-write] |
|
|
1007 | |
|
|
1008 | The current interval value. Can be modified any time, but changes only |
|
|
1009 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
|
|
1010 | called. |
|
|
1011 | |
|
|
1012 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
|
|
1013 | |
|
|
1014 | The current reschedule callback, or C<0>, if this functionality is |
|
|
1015 | switched off. Can be changed any time, but changes only take effect when |
|
|
1016 | the periodic timer fires or C<ev_periodic_again> is being called. |
|
|
1017 | |
698 | =back |
1018 | =back |
699 | |
1019 | |
|
|
1020 | Example: call a callback every hour, or, more precisely, whenever the |
|
|
1021 | system clock is divisible by 3600. The callback invocation times have |
|
|
1022 | potentially a lot of jittering, but good long-term stability. |
|
|
1023 | |
|
|
1024 | static void |
|
|
1025 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
1026 | { |
|
|
1027 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
|
|
1028 | } |
|
|
1029 | |
|
|
1030 | struct ev_periodic hourly_tick; |
|
|
1031 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
|
|
1032 | ev_periodic_start (loop, &hourly_tick); |
|
|
1033 | |
|
|
1034 | Example: the same as above, but use a reschedule callback to do it: |
|
|
1035 | |
|
|
1036 | #include <math.h> |
|
|
1037 | |
|
|
1038 | static ev_tstamp |
|
|
1039 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
|
|
1040 | { |
|
|
1041 | return fmod (now, 3600.) + 3600.; |
|
|
1042 | } |
|
|
1043 | |
|
|
1044 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
|
|
1045 | |
|
|
1046 | Example: call a callback every hour, starting now: |
|
|
1047 | |
|
|
1048 | struct ev_periodic hourly_tick; |
|
|
1049 | ev_periodic_init (&hourly_tick, clock_cb, |
|
|
1050 | fmod (ev_now (loop), 3600.), 3600., 0); |
|
|
1051 | ev_periodic_start (loop, &hourly_tick); |
|
|
1052 | |
|
|
1053 | |
700 | =head2 C<ev_signal> - signal me when a signal gets signalled |
1054 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
701 | |
1055 | |
702 | Signal watchers will trigger an event when the process receives a specific |
1056 | Signal watchers will trigger an event when the process receives a specific |
703 | signal one or more times. Even though signals are very asynchronous, libev |
1057 | signal one or more times. Even though signals are very asynchronous, libev |
704 | will try it's best to deliver signals synchronously, i.e. as part of the |
1058 | will try it's best to deliver signals synchronously, i.e. as part of the |
705 | normal event processing, like any other event. |
1059 | normal event processing, like any other event. |
… | |
… | |
718 | =item ev_signal_set (ev_signal *, int signum) |
1072 | =item ev_signal_set (ev_signal *, int signum) |
719 | |
1073 | |
720 | Configures the watcher to trigger on the given signal number (usually one |
1074 | Configures the watcher to trigger on the given signal number (usually one |
721 | of the C<SIGxxx> constants). |
1075 | of the C<SIGxxx> constants). |
722 | |
1076 | |
|
|
1077 | =item int signum [read-only] |
|
|
1078 | |
|
|
1079 | The signal the watcher watches out for. |
|
|
1080 | |
723 | =back |
1081 | =back |
724 | |
1082 | |
|
|
1083 | |
725 | =head2 C<ev_child> - wait for pid status changes |
1084 | =head2 C<ev_child> - watch out for process status changes |
726 | |
1085 | |
727 | Child watchers trigger when your process receives a SIGCHLD in response to |
1086 | Child watchers trigger when your process receives a SIGCHLD in response to |
728 | some child status changes (most typically when a child of yours dies). |
1087 | some child status changes (most typically when a child of yours dies). |
729 | |
1088 | |
730 | =over 4 |
1089 | =over 4 |
… | |
… | |
738 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1097 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
739 | the status word (use the macros from C<sys/wait.h> and see your systems |
1098 | the status word (use the macros from C<sys/wait.h> and see your systems |
740 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1099 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
741 | process causing the status change. |
1100 | process causing the status change. |
742 | |
1101 | |
|
|
1102 | =item int pid [read-only] |
|
|
1103 | |
|
|
1104 | The process id this watcher watches out for, or C<0>, meaning any process id. |
|
|
1105 | |
|
|
1106 | =item int rpid [read-write] |
|
|
1107 | |
|
|
1108 | The process id that detected a status change. |
|
|
1109 | |
|
|
1110 | =item int rstatus [read-write] |
|
|
1111 | |
|
|
1112 | The process exit/trace status caused by C<rpid> (see your systems |
|
|
1113 | C<waitpid> and C<sys/wait.h> documentation for details). |
|
|
1114 | |
743 | =back |
1115 | =back |
744 | |
1116 | |
|
|
1117 | Example: try to exit cleanly on SIGINT and SIGTERM. |
|
|
1118 | |
|
|
1119 | static void |
|
|
1120 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1121 | { |
|
|
1122 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1123 | } |
|
|
1124 | |
|
|
1125 | struct ev_signal signal_watcher; |
|
|
1126 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1127 | ev_signal_start (loop, &sigint_cb); |
|
|
1128 | |
|
|
1129 | |
|
|
1130 | =head2 C<ev_stat> - did the file attributes just change? |
|
|
1131 | |
|
|
1132 | This watches a filesystem path for attribute changes. That is, it calls |
|
|
1133 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
|
|
1134 | compared to the last time, invoking the callback if it did. |
|
|
1135 | |
|
|
1136 | The path does not need to exist: changing from "path exists" to "path does |
|
|
1137 | not exist" is a status change like any other. The condition "path does |
|
|
1138 | not exist" is signified by the C<st_nlink> field being zero (which is |
|
|
1139 | otherwise always forced to be at least one) and all the other fields of |
|
|
1140 | the stat buffer having unspecified contents. |
|
|
1141 | |
|
|
1142 | Since there is no standard to do this, the portable implementation simply |
|
|
1143 | calls C<stat (2)> regulalry on the path to see if it changed somehow. You |
|
|
1144 | can specify a recommended polling interval for this case. If you specify |
|
|
1145 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
|
|
1146 | unspecified default> value will be used (which you can expect to be around |
|
|
1147 | five seconds, although this might change dynamically). Libev will also |
|
|
1148 | impose a minimum interval which is currently around C<0.1>, but thats |
|
|
1149 | usually overkill. |
|
|
1150 | |
|
|
1151 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
1152 | as even with OS-supported change notifications, this can be |
|
|
1153 | resource-intensive. |
|
|
1154 | |
|
|
1155 | At the time of this writing, no specific OS backends are implemented, but |
|
|
1156 | if demand increases, at least a kqueue and inotify backend will be added. |
|
|
1157 | |
|
|
1158 | =over 4 |
|
|
1159 | |
|
|
1160 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
|
|
1161 | |
|
|
1162 | =item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval) |
|
|
1163 | |
|
|
1164 | Configures the watcher to wait for status changes of the given |
|
|
1165 | C<path>. The C<interval> is a hint on how quickly a change is expected to |
|
|
1166 | be detected and should normally be specified as C<0> to let libev choose |
|
|
1167 | a suitable value. The memory pointed to by C<path> must point to the same |
|
|
1168 | path for as long as the watcher is active. |
|
|
1169 | |
|
|
1170 | The callback will be receive C<EV_STAT> when a change was detected, |
|
|
1171 | relative to the attributes at the time the watcher was started (or the |
|
|
1172 | last change was detected). |
|
|
1173 | |
|
|
1174 | =item ev_stat_stat (ev_stat *) |
|
|
1175 | |
|
|
1176 | Updates the stat buffer immediately with new values. If you change the |
|
|
1177 | watched path in your callback, you could call this fucntion to avoid |
|
|
1178 | detecting this change (while introducing a race condition). Can also be |
|
|
1179 | useful simply to find out the new values. |
|
|
1180 | |
|
|
1181 | =item ev_statdata attr [read-only] |
|
|
1182 | |
|
|
1183 | The most-recently detected attributes of the file. Although the type is of |
|
|
1184 | C<ev_statdata>, this is usually the (or one of the) C<struct stat> types |
|
|
1185 | suitable for your system. If the C<st_nlink> member is C<0>, then there |
|
|
1186 | was some error while C<stat>ing the file. |
|
|
1187 | |
|
|
1188 | =item ev_statdata prev [read-only] |
|
|
1189 | |
|
|
1190 | The previous attributes of the file. The callback gets invoked whenever |
|
|
1191 | C<prev> != C<attr>. |
|
|
1192 | |
|
|
1193 | =item ev_tstamp interval [read-only] |
|
|
1194 | |
|
|
1195 | The specified interval. |
|
|
1196 | |
|
|
1197 | =item const char *path [read-only] |
|
|
1198 | |
|
|
1199 | The filesystem path that is being watched. |
|
|
1200 | |
|
|
1201 | =back |
|
|
1202 | |
|
|
1203 | Example: Watch C</etc/passwd> for attribute changes. |
|
|
1204 | |
|
|
1205 | static void |
|
|
1206 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1207 | { |
|
|
1208 | /* /etc/passwd changed in some way */ |
|
|
1209 | if (w->attr.st_nlink) |
|
|
1210 | { |
|
|
1211 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
|
|
1212 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
|
|
1213 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
|
|
1214 | } |
|
|
1215 | else |
|
|
1216 | /* you shalt not abuse printf for puts */ |
|
|
1217 | puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1218 | "if this is windows, they already arrived\n"); |
|
|
1219 | } |
|
|
1220 | |
|
|
1221 | ... |
|
|
1222 | ev_stat passwd; |
|
|
1223 | |
|
|
1224 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
|
|
1225 | ev_stat_start (loop, &passwd); |
|
|
1226 | |
|
|
1227 | |
745 | =head2 C<ev_idle> - when you've got nothing better to do |
1228 | =head2 C<ev_idle> - when you've got nothing better to do... |
746 | |
1229 | |
747 | Idle watchers trigger events when there are no other events are pending |
1230 | Idle watchers trigger events when there are no other events are pending |
748 | (prepare, check and other idle watchers do not count). That is, as long |
1231 | (prepare, check and other idle watchers do not count). That is, as long |
749 | as your process is busy handling sockets or timeouts (or even signals, |
1232 | as your process is busy handling sockets or timeouts (or even signals, |
750 | imagine) it will not be triggered. But when your process is idle all idle |
1233 | imagine) it will not be triggered. But when your process is idle all idle |
… | |
… | |
768 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1251 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
769 | believe me. |
1252 | believe me. |
770 | |
1253 | |
771 | =back |
1254 | =back |
772 | |
1255 | |
|
|
1256 | Example: dynamically allocate an C<ev_idle>, start it, and in the |
|
|
1257 | callback, free it. Alos, use no error checking, as usual. |
|
|
1258 | |
|
|
1259 | static void |
|
|
1260 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
|
|
1261 | { |
|
|
1262 | free (w); |
|
|
1263 | // now do something you wanted to do when the program has |
|
|
1264 | // no longer asnything immediate to do. |
|
|
1265 | } |
|
|
1266 | |
|
|
1267 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
|
|
1268 | ev_idle_init (idle_watcher, idle_cb); |
|
|
1269 | ev_idle_start (loop, idle_cb); |
|
|
1270 | |
|
|
1271 | |
773 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
1272 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
774 | |
1273 | |
775 | Prepare and check watchers are usually (but not always) used in tandem: |
1274 | Prepare and check watchers are usually (but not always) used in tandem: |
776 | prepare watchers get invoked before the process blocks and check watchers |
1275 | prepare watchers get invoked before the process blocks and check watchers |
777 | afterwards. |
1276 | afterwards. |
778 | |
1277 | |
|
|
1278 | You I<must not> call C<ev_loop> or similar functions that enter |
|
|
1279 | the current event loop from either C<ev_prepare> or C<ev_check> |
|
|
1280 | watchers. Other loops than the current one are fine, however. The |
|
|
1281 | rationale behind this is that you do not need to check for recursion in |
|
|
1282 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
|
|
1283 | C<ev_check> so if you have one watcher of each kind they will always be |
|
|
1284 | called in pairs bracketing the blocking call. |
|
|
1285 | |
779 | Their main purpose is to integrate other event mechanisms into libev. This |
1286 | Their main purpose is to integrate other event mechanisms into libev and |
780 | could be used, for example, to track variable changes, implement your own |
1287 | their use is somewhat advanced. This could be used, for example, to track |
781 | watchers, integrate net-snmp or a coroutine library and lots more. |
1288 | variable changes, implement your own watchers, integrate net-snmp or a |
|
|
1289 | coroutine library and lots more. They are also occasionally useful if |
|
|
1290 | you cache some data and want to flush it before blocking (for example, |
|
|
1291 | in X programs you might want to do an C<XFlush ()> in an C<ev_prepare> |
|
|
1292 | watcher). |
782 | |
1293 | |
783 | This is done by examining in each prepare call which file descriptors need |
1294 | This is done by examining in each prepare call which file descriptors need |
784 | to be watched by the other library, registering C<ev_io> watchers for |
1295 | to be watched by the other library, registering C<ev_io> watchers for |
785 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1296 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
786 | provide just this functionality). Then, in the check watcher you check for |
1297 | provide just this functionality). Then, in the check watcher you check for |
… | |
… | |
808 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1319 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
809 | macros, but using them is utterly, utterly and completely pointless. |
1320 | macros, but using them is utterly, utterly and completely pointless. |
810 | |
1321 | |
811 | =back |
1322 | =back |
812 | |
1323 | |
|
|
1324 | Example: To include a library such as adns, you would add IO watchers |
|
|
1325 | and a timeout watcher in a prepare handler, as required by libadns, and |
|
|
1326 | in a check watcher, destroy them and call into libadns. What follows is |
|
|
1327 | pseudo-code only of course: |
|
|
1328 | |
|
|
1329 | static ev_io iow [nfd]; |
|
|
1330 | static ev_timer tw; |
|
|
1331 | |
|
|
1332 | static void |
|
|
1333 | io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1334 | { |
|
|
1335 | // set the relevant poll flags |
|
|
1336 | // could also call adns_processreadable etc. here |
|
|
1337 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1338 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1339 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1340 | } |
|
|
1341 | |
|
|
1342 | // create io watchers for each fd and a timer before blocking |
|
|
1343 | static void |
|
|
1344 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1345 | { |
|
|
1346 | int timeout = 3600000;truct pollfd fds [nfd]; |
|
|
1347 | // actual code will need to loop here and realloc etc. |
|
|
1348 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
|
|
1349 | |
|
|
1350 | /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1351 | ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1352 | ev_timer_start (loop, &tw); |
|
|
1353 | |
|
|
1354 | // create on ev_io per pollfd |
|
|
1355 | for (int i = 0; i < nfd; ++i) |
|
|
1356 | { |
|
|
1357 | ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1358 | ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1359 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
1360 | |
|
|
1361 | fds [i].revents = 0; |
|
|
1362 | iow [i].data = fds + i; |
|
|
1363 | ev_io_start (loop, iow + i); |
|
|
1364 | } |
|
|
1365 | } |
|
|
1366 | |
|
|
1367 | // stop all watchers after blocking |
|
|
1368 | static void |
|
|
1369 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1370 | { |
|
|
1371 | ev_timer_stop (loop, &tw); |
|
|
1372 | |
|
|
1373 | for (int i = 0; i < nfd; ++i) |
|
|
1374 | ev_io_stop (loop, iow + i); |
|
|
1375 | |
|
|
1376 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1377 | } |
|
|
1378 | |
|
|
1379 | |
|
|
1380 | =head2 C<ev_embed> - when one backend isn't enough... |
|
|
1381 | |
|
|
1382 | This is a rather advanced watcher type that lets you embed one event loop |
|
|
1383 | into another (currently only C<ev_io> events are supported in the embedded |
|
|
1384 | loop, other types of watchers might be handled in a delayed or incorrect |
|
|
1385 | fashion and must not be used). |
|
|
1386 | |
|
|
1387 | There are primarily two reasons you would want that: work around bugs and |
|
|
1388 | prioritise I/O. |
|
|
1389 | |
|
|
1390 | As an example for a bug workaround, the kqueue backend might only support |
|
|
1391 | sockets on some platform, so it is unusable as generic backend, but you |
|
|
1392 | still want to make use of it because you have many sockets and it scales |
|
|
1393 | so nicely. In this case, you would create a kqueue-based loop and embed it |
|
|
1394 | into your default loop (which might use e.g. poll). Overall operation will |
|
|
1395 | be a bit slower because first libev has to poll and then call kevent, but |
|
|
1396 | at least you can use both at what they are best. |
|
|
1397 | |
|
|
1398 | As for prioritising I/O: rarely you have the case where some fds have |
|
|
1399 | to be watched and handled very quickly (with low latency), and even |
|
|
1400 | priorities and idle watchers might have too much overhead. In this case |
|
|
1401 | you would put all the high priority stuff in one loop and all the rest in |
|
|
1402 | a second one, and embed the second one in the first. |
|
|
1403 | |
|
|
1404 | As long as the watcher is active, the callback will be invoked every time |
|
|
1405 | there might be events pending in the embedded loop. The callback must then |
|
|
1406 | call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke |
|
|
1407 | their callbacks (you could also start an idle watcher to give the embedded |
|
|
1408 | loop strictly lower priority for example). You can also set the callback |
|
|
1409 | to C<0>, in which case the embed watcher will automatically execute the |
|
|
1410 | embedded loop sweep. |
|
|
1411 | |
|
|
1412 | As long as the watcher is started it will automatically handle events. The |
|
|
1413 | callback will be invoked whenever some events have been handled. You can |
|
|
1414 | set the callback to C<0> to avoid having to specify one if you are not |
|
|
1415 | interested in that. |
|
|
1416 | |
|
|
1417 | Also, there have not currently been made special provisions for forking: |
|
|
1418 | when you fork, you not only have to call C<ev_loop_fork> on both loops, |
|
|
1419 | but you will also have to stop and restart any C<ev_embed> watchers |
|
|
1420 | yourself. |
|
|
1421 | |
|
|
1422 | Unfortunately, not all backends are embeddable, only the ones returned by |
|
|
1423 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
|
|
1424 | portable one. |
|
|
1425 | |
|
|
1426 | So when you want to use this feature you will always have to be prepared |
|
|
1427 | that you cannot get an embeddable loop. The recommended way to get around |
|
|
1428 | this is to have a separate variables for your embeddable loop, try to |
|
|
1429 | create it, and if that fails, use the normal loop for everything: |
|
|
1430 | |
|
|
1431 | struct ev_loop *loop_hi = ev_default_init (0); |
|
|
1432 | struct ev_loop *loop_lo = 0; |
|
|
1433 | struct ev_embed embed; |
|
|
1434 | |
|
|
1435 | // see if there is a chance of getting one that works |
|
|
1436 | // (remember that a flags value of 0 means autodetection) |
|
|
1437 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
1438 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
1439 | : 0; |
|
|
1440 | |
|
|
1441 | // if we got one, then embed it, otherwise default to loop_hi |
|
|
1442 | if (loop_lo) |
|
|
1443 | { |
|
|
1444 | ev_embed_init (&embed, 0, loop_lo); |
|
|
1445 | ev_embed_start (loop_hi, &embed); |
|
|
1446 | } |
|
|
1447 | else |
|
|
1448 | loop_lo = loop_hi; |
|
|
1449 | |
|
|
1450 | =over 4 |
|
|
1451 | |
|
|
1452 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1453 | |
|
|
1454 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1455 | |
|
|
1456 | Configures the watcher to embed the given loop, which must be |
|
|
1457 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1458 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1459 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1460 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1461 | |
|
|
1462 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1463 | |
|
|
1464 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1465 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1466 | apropriate way for embedded loops. |
|
|
1467 | |
|
|
1468 | =item struct ev_loop *loop [read-only] |
|
|
1469 | |
|
|
1470 | The embedded event loop. |
|
|
1471 | |
|
|
1472 | =back |
|
|
1473 | |
|
|
1474 | |
813 | =head1 OTHER FUNCTIONS |
1475 | =head1 OTHER FUNCTIONS |
814 | |
1476 | |
815 | There are some other functions of possible interest. Described. Here. Now. |
1477 | There are some other functions of possible interest. Described. Here. Now. |
816 | |
1478 | |
817 | =over 4 |
1479 | =over 4 |
… | |
… | |
846 | /* stdin might have data for us, joy! */; |
1508 | /* stdin might have data for us, joy! */; |
847 | } |
1509 | } |
848 | |
1510 | |
849 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
1511 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
850 | |
1512 | |
851 | =item ev_feed_event (loop, watcher, int events) |
1513 | =item ev_feed_event (ev_loop *, watcher *, int revents) |
852 | |
1514 | |
853 | Feeds the given event set into the event loop, as if the specified event |
1515 | Feeds the given event set into the event loop, as if the specified event |
854 | had happened for the specified watcher (which must be a pointer to an |
1516 | had happened for the specified watcher (which must be a pointer to an |
855 | initialised but not necessarily started event watcher). |
1517 | initialised but not necessarily started event watcher). |
856 | |
1518 | |
857 | =item ev_feed_fd_event (loop, int fd, int revents) |
1519 | =item ev_feed_fd_event (ev_loop *, int fd, int revents) |
858 | |
1520 | |
859 | Feed an event on the given fd, as if a file descriptor backend detected |
1521 | Feed an event on the given fd, as if a file descriptor backend detected |
860 | the given events it. |
1522 | the given events it. |
861 | |
1523 | |
862 | =item ev_feed_signal_event (loop, int signum) |
1524 | =item ev_feed_signal_event (ev_loop *loop, int signum) |
863 | |
1525 | |
864 | Feed an event as if the given signal occured (loop must be the default loop!). |
1526 | Feed an event as if the given signal occured (C<loop> must be the default |
|
|
1527 | loop!). |
865 | |
1528 | |
866 | =back |
1529 | =back |
|
|
1530 | |
867 | |
1531 | |
868 | =head1 LIBEVENT EMULATION |
1532 | =head1 LIBEVENT EMULATION |
869 | |
1533 | |
870 | Libev offers a compatibility emulation layer for libevent. It cannot |
1534 | Libev offers a compatibility emulation layer for libevent. It cannot |
871 | emulate the internals of libevent, so here are some usage hints: |
1535 | emulate the internals of libevent, so here are some usage hints: |
… | |
… | |
892 | |
1556 | |
893 | =back |
1557 | =back |
894 | |
1558 | |
895 | =head1 C++ SUPPORT |
1559 | =head1 C++ SUPPORT |
896 | |
1560 | |
897 | TBD. |
1561 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
|
|
1562 | you to use some convinience methods to start/stop watchers and also change |
|
|
1563 | the callback model to a model using method callbacks on objects. |
|
|
1564 | |
|
|
1565 | To use it, |
|
|
1566 | |
|
|
1567 | #include <ev++.h> |
|
|
1568 | |
|
|
1569 | (it is not installed by default). This automatically includes F<ev.h> |
|
|
1570 | and puts all of its definitions (many of them macros) into the global |
|
|
1571 | namespace. All C++ specific things are put into the C<ev> namespace. |
|
|
1572 | |
|
|
1573 | It should support all the same embedding options as F<ev.h>, most notably |
|
|
1574 | C<EV_MULTIPLICITY>. |
|
|
1575 | |
|
|
1576 | Here is a list of things available in the C<ev> namespace: |
|
|
1577 | |
|
|
1578 | =over 4 |
|
|
1579 | |
|
|
1580 | =item C<ev::READ>, C<ev::WRITE> etc. |
|
|
1581 | |
|
|
1582 | These are just enum values with the same values as the C<EV_READ> etc. |
|
|
1583 | macros from F<ev.h>. |
|
|
1584 | |
|
|
1585 | =item C<ev::tstamp>, C<ev::now> |
|
|
1586 | |
|
|
1587 | Aliases to the same types/functions as with the C<ev_> prefix. |
|
|
1588 | |
|
|
1589 | =item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc. |
|
|
1590 | |
|
|
1591 | For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of |
|
|
1592 | the same name in the C<ev> namespace, with the exception of C<ev_signal> |
|
|
1593 | which is called C<ev::sig> to avoid clashes with the C<signal> macro |
|
|
1594 | defines by many implementations. |
|
|
1595 | |
|
|
1596 | All of those classes have these methods: |
|
|
1597 | |
|
|
1598 | =over 4 |
|
|
1599 | |
|
|
1600 | =item ev::TYPE::TYPE (object *, object::method *) |
|
|
1601 | |
|
|
1602 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
|
|
1603 | |
|
|
1604 | =item ev::TYPE::~TYPE |
|
|
1605 | |
|
|
1606 | The constructor takes a pointer to an object and a method pointer to |
|
|
1607 | the event handler callback to call in this class. The constructor calls |
|
|
1608 | C<ev_init> for you, which means you have to call the C<set> method |
|
|
1609 | before starting it. If you do not specify a loop then the constructor |
|
|
1610 | automatically associates the default loop with this watcher. |
|
|
1611 | |
|
|
1612 | The destructor automatically stops the watcher if it is active. |
|
|
1613 | |
|
|
1614 | =item w->set (struct ev_loop *) |
|
|
1615 | |
|
|
1616 | Associates a different C<struct ev_loop> with this watcher. You can only |
|
|
1617 | do this when the watcher is inactive (and not pending either). |
|
|
1618 | |
|
|
1619 | =item w->set ([args]) |
|
|
1620 | |
|
|
1621 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
|
|
1622 | called at least once. Unlike the C counterpart, an active watcher gets |
|
|
1623 | automatically stopped and restarted. |
|
|
1624 | |
|
|
1625 | =item w->start () |
|
|
1626 | |
|
|
1627 | Starts the watcher. Note that there is no C<loop> argument as the |
|
|
1628 | constructor already takes the loop. |
|
|
1629 | |
|
|
1630 | =item w->stop () |
|
|
1631 | |
|
|
1632 | Stops the watcher if it is active. Again, no C<loop> argument. |
|
|
1633 | |
|
|
1634 | =item w->again () C<ev::timer>, C<ev::periodic> only |
|
|
1635 | |
|
|
1636 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
|
|
1637 | C<ev_TYPE_again> function. |
|
|
1638 | |
|
|
1639 | =item w->sweep () C<ev::embed> only |
|
|
1640 | |
|
|
1641 | Invokes C<ev_embed_sweep>. |
|
|
1642 | |
|
|
1643 | =back |
|
|
1644 | |
|
|
1645 | =back |
|
|
1646 | |
|
|
1647 | Example: Define a class with an IO and idle watcher, start one of them in |
|
|
1648 | the constructor. |
|
|
1649 | |
|
|
1650 | class myclass |
|
|
1651 | { |
|
|
1652 | ev_io io; void io_cb (ev::io &w, int revents); |
|
|
1653 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
|
|
1654 | |
|
|
1655 | myclass (); |
|
|
1656 | } |
|
|
1657 | |
|
|
1658 | myclass::myclass (int fd) |
|
|
1659 | : io (this, &myclass::io_cb), |
|
|
1660 | idle (this, &myclass::idle_cb) |
|
|
1661 | { |
|
|
1662 | io.start (fd, ev::READ); |
|
|
1663 | } |
|
|
1664 | |
|
|
1665 | =head1 EMBEDDING |
|
|
1666 | |
|
|
1667 | Libev can (and often is) directly embedded into host |
|
|
1668 | applications. Examples of applications that embed it include the Deliantra |
|
|
1669 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
|
|
1670 | and rxvt-unicode. |
|
|
1671 | |
|
|
1672 | The goal is to enable you to just copy the neecssary files into your |
|
|
1673 | source directory without having to change even a single line in them, so |
|
|
1674 | you can easily upgrade by simply copying (or having a checked-out copy of |
|
|
1675 | libev somewhere in your source tree). |
|
|
1676 | |
|
|
1677 | =head2 FILESETS |
|
|
1678 | |
|
|
1679 | Depending on what features you need you need to include one or more sets of files |
|
|
1680 | in your app. |
|
|
1681 | |
|
|
1682 | =head3 CORE EVENT LOOP |
|
|
1683 | |
|
|
1684 | To include only the libev core (all the C<ev_*> functions), with manual |
|
|
1685 | configuration (no autoconf): |
|
|
1686 | |
|
|
1687 | #define EV_STANDALONE 1 |
|
|
1688 | #include "ev.c" |
|
|
1689 | |
|
|
1690 | This will automatically include F<ev.h>, too, and should be done in a |
|
|
1691 | single C source file only to provide the function implementations. To use |
|
|
1692 | it, do the same for F<ev.h> in all files wishing to use this API (best |
|
|
1693 | done by writing a wrapper around F<ev.h> that you can include instead and |
|
|
1694 | where you can put other configuration options): |
|
|
1695 | |
|
|
1696 | #define EV_STANDALONE 1 |
|
|
1697 | #include "ev.h" |
|
|
1698 | |
|
|
1699 | Both header files and implementation files can be compiled with a C++ |
|
|
1700 | compiler (at least, thats a stated goal, and breakage will be treated |
|
|
1701 | as a bug). |
|
|
1702 | |
|
|
1703 | You need the following files in your source tree, or in a directory |
|
|
1704 | in your include path (e.g. in libev/ when using -Ilibev): |
|
|
1705 | |
|
|
1706 | ev.h |
|
|
1707 | ev.c |
|
|
1708 | ev_vars.h |
|
|
1709 | ev_wrap.h |
|
|
1710 | |
|
|
1711 | ev_win32.c required on win32 platforms only |
|
|
1712 | |
|
|
1713 | ev_select.c only when select backend is enabled (which is by default) |
|
|
1714 | ev_poll.c only when poll backend is enabled (disabled by default) |
|
|
1715 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
|
|
1716 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
|
|
1717 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
|
|
1718 | |
|
|
1719 | F<ev.c> includes the backend files directly when enabled, so you only need |
|
|
1720 | to compile this single file. |
|
|
1721 | |
|
|
1722 | =head3 LIBEVENT COMPATIBILITY API |
|
|
1723 | |
|
|
1724 | To include the libevent compatibility API, also include: |
|
|
1725 | |
|
|
1726 | #include "event.c" |
|
|
1727 | |
|
|
1728 | in the file including F<ev.c>, and: |
|
|
1729 | |
|
|
1730 | #include "event.h" |
|
|
1731 | |
|
|
1732 | in the files that want to use the libevent API. This also includes F<ev.h>. |
|
|
1733 | |
|
|
1734 | You need the following additional files for this: |
|
|
1735 | |
|
|
1736 | event.h |
|
|
1737 | event.c |
|
|
1738 | |
|
|
1739 | =head3 AUTOCONF SUPPORT |
|
|
1740 | |
|
|
1741 | Instead of using C<EV_STANDALONE=1> and providing your config in |
|
|
1742 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
|
|
1743 | F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then |
|
|
1744 | include F<config.h> and configure itself accordingly. |
|
|
1745 | |
|
|
1746 | For this of course you need the m4 file: |
|
|
1747 | |
|
|
1748 | libev.m4 |
|
|
1749 | |
|
|
1750 | =head2 PREPROCESSOR SYMBOLS/MACROS |
|
|
1751 | |
|
|
1752 | Libev can be configured via a variety of preprocessor symbols you have to define |
|
|
1753 | before including any of its files. The default is not to build for multiplicity |
|
|
1754 | and only include the select backend. |
|
|
1755 | |
|
|
1756 | =over 4 |
|
|
1757 | |
|
|
1758 | =item EV_STANDALONE |
|
|
1759 | |
|
|
1760 | Must always be C<1> if you do not use autoconf configuration, which |
|
|
1761 | keeps libev from including F<config.h>, and it also defines dummy |
|
|
1762 | implementations for some libevent functions (such as logging, which is not |
|
|
1763 | supported). It will also not define any of the structs usually found in |
|
|
1764 | F<event.h> that are not directly supported by the libev core alone. |
|
|
1765 | |
|
|
1766 | =item EV_USE_MONOTONIC |
|
|
1767 | |
|
|
1768 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
1769 | monotonic clock option at both compiletime and runtime. Otherwise no use |
|
|
1770 | of the monotonic clock option will be attempted. If you enable this, you |
|
|
1771 | usually have to link against librt or something similar. Enabling it when |
|
|
1772 | the functionality isn't available is safe, though, althoguh you have |
|
|
1773 | to make sure you link against any libraries where the C<clock_gettime> |
|
|
1774 | function is hiding in (often F<-lrt>). |
|
|
1775 | |
|
|
1776 | =item EV_USE_REALTIME |
|
|
1777 | |
|
|
1778 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
1779 | realtime clock option at compiletime (and assume its availability at |
|
|
1780 | runtime if successful). Otherwise no use of the realtime clock option will |
|
|
1781 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
|
|
1782 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
|
|
1783 | in the description of C<EV_USE_MONOTONIC>, though. |
|
|
1784 | |
|
|
1785 | =item EV_USE_SELECT |
|
|
1786 | |
|
|
1787 | If undefined or defined to be C<1>, libev will compile in support for the |
|
|
1788 | C<select>(2) backend. No attempt at autodetection will be done: if no |
|
|
1789 | other method takes over, select will be it. Otherwise the select backend |
|
|
1790 | will not be compiled in. |
|
|
1791 | |
|
|
1792 | =item EV_SELECT_USE_FD_SET |
|
|
1793 | |
|
|
1794 | If defined to C<1>, then the select backend will use the system C<fd_set> |
|
|
1795 | structure. This is useful if libev doesn't compile due to a missing |
|
|
1796 | C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on |
|
|
1797 | exotic systems. This usually limits the range of file descriptors to some |
|
|
1798 | low limit such as 1024 or might have other limitations (winsocket only |
|
|
1799 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
|
|
1800 | influence the size of the C<fd_set> used. |
|
|
1801 | |
|
|
1802 | =item EV_SELECT_IS_WINSOCKET |
|
|
1803 | |
|
|
1804 | When defined to C<1>, the select backend will assume that |
|
|
1805 | select/socket/connect etc. don't understand file descriptors but |
|
|
1806 | wants osf handles on win32 (this is the case when the select to |
|
|
1807 | be used is the winsock select). This means that it will call |
|
|
1808 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
|
|
1809 | it is assumed that all these functions actually work on fds, even |
|
|
1810 | on win32. Should not be defined on non-win32 platforms. |
|
|
1811 | |
|
|
1812 | =item EV_USE_POLL |
|
|
1813 | |
|
|
1814 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
|
|
1815 | backend. Otherwise it will be enabled on non-win32 platforms. It |
|
|
1816 | takes precedence over select. |
|
|
1817 | |
|
|
1818 | =item EV_USE_EPOLL |
|
|
1819 | |
|
|
1820 | If defined to be C<1>, libev will compile in support for the Linux |
|
|
1821 | C<epoll>(7) backend. Its availability will be detected at runtime, |
|
|
1822 | otherwise another method will be used as fallback. This is the |
|
|
1823 | preferred backend for GNU/Linux systems. |
|
|
1824 | |
|
|
1825 | =item EV_USE_KQUEUE |
|
|
1826 | |
|
|
1827 | If defined to be C<1>, libev will compile in support for the BSD style |
|
|
1828 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
|
|
1829 | otherwise another method will be used as fallback. This is the preferred |
|
|
1830 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
|
|
1831 | supports some types of fds correctly (the only platform we found that |
|
|
1832 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
|
|
1833 | not be used unless explicitly requested. The best way to use it is to find |
|
|
1834 | out whether kqueue supports your type of fd properly and use an embedded |
|
|
1835 | kqueue loop. |
|
|
1836 | |
|
|
1837 | =item EV_USE_PORT |
|
|
1838 | |
|
|
1839 | If defined to be C<1>, libev will compile in support for the Solaris |
|
|
1840 | 10 port style backend. Its availability will be detected at runtime, |
|
|
1841 | otherwise another method will be used as fallback. This is the preferred |
|
|
1842 | backend for Solaris 10 systems. |
|
|
1843 | |
|
|
1844 | =item EV_USE_DEVPOLL |
|
|
1845 | |
|
|
1846 | reserved for future expansion, works like the USE symbols above. |
|
|
1847 | |
|
|
1848 | =item EV_H |
|
|
1849 | |
|
|
1850 | The name of the F<ev.h> header file used to include it. The default if |
|
|
1851 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
|
|
1852 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
|
|
1853 | |
|
|
1854 | =item EV_CONFIG_H |
|
|
1855 | |
|
|
1856 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
|
|
1857 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
|
|
1858 | C<EV_H>, above. |
|
|
1859 | |
|
|
1860 | =item EV_EVENT_H |
|
|
1861 | |
|
|
1862 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
|
|
1863 | of how the F<event.h> header can be found. |
|
|
1864 | |
|
|
1865 | =item EV_PROTOTYPES |
|
|
1866 | |
|
|
1867 | If defined to be C<0>, then F<ev.h> will not define any function |
|
|
1868 | prototypes, but still define all the structs and other symbols. This is |
|
|
1869 | occasionally useful if you want to provide your own wrapper functions |
|
|
1870 | around libev functions. |
|
|
1871 | |
|
|
1872 | =item EV_MULTIPLICITY |
|
|
1873 | |
|
|
1874 | If undefined or defined to C<1>, then all event-loop-specific functions |
|
|
1875 | will have the C<struct ev_loop *> as first argument, and you can create |
|
|
1876 | additional independent event loops. Otherwise there will be no support |
|
|
1877 | for multiple event loops and there is no first event loop pointer |
|
|
1878 | argument. Instead, all functions act on the single default loop. |
|
|
1879 | |
|
|
1880 | =item EV_PERIODIC_ENABLE |
|
|
1881 | |
|
|
1882 | If undefined or defined to be C<1>, then periodic timers are supported. If |
|
|
1883 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
1884 | code. |
|
|
1885 | |
|
|
1886 | =item EV_EMBED_ENABLE |
|
|
1887 | |
|
|
1888 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
1889 | defined to be C<0>, then they are not. |
|
|
1890 | |
|
|
1891 | =item EV_STAT_ENABLE |
|
|
1892 | |
|
|
1893 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
1894 | defined to be C<0>, then they are not. |
|
|
1895 | |
|
|
1896 | =item EV_MINIMAL |
|
|
1897 | |
|
|
1898 | If you need to shave off some kilobytes of code at the expense of some |
|
|
1899 | speed, define this symbol to C<1>. Currently only used for gcc to override |
|
|
1900 | some inlining decisions, saves roughly 30% codesize of amd64. |
|
|
1901 | |
|
|
1902 | =item EV_COMMON |
|
|
1903 | |
|
|
1904 | By default, all watchers have a C<void *data> member. By redefining |
|
|
1905 | this macro to a something else you can include more and other types of |
|
|
1906 | members. You have to define it each time you include one of the files, |
|
|
1907 | though, and it must be identical each time. |
|
|
1908 | |
|
|
1909 | For example, the perl EV module uses something like this: |
|
|
1910 | |
|
|
1911 | #define EV_COMMON \ |
|
|
1912 | SV *self; /* contains this struct */ \ |
|
|
1913 | SV *cb_sv, *fh /* note no trailing ";" */ |
|
|
1914 | |
|
|
1915 | =item EV_CB_DECLARE (type) |
|
|
1916 | |
|
|
1917 | =item EV_CB_INVOKE (watcher, revents) |
|
|
1918 | |
|
|
1919 | =item ev_set_cb (ev, cb) |
|
|
1920 | |
|
|
1921 | Can be used to change the callback member declaration in each watcher, |
|
|
1922 | and the way callbacks are invoked and set. Must expand to a struct member |
|
|
1923 | definition and a statement, respectively. See the F<ev.v> header file for |
|
|
1924 | their default definitions. One possible use for overriding these is to |
|
|
1925 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
|
|
1926 | method calls instead of plain function calls in C++. |
|
|
1927 | |
|
|
1928 | =head2 EXAMPLES |
|
|
1929 | |
|
|
1930 | For a real-world example of a program the includes libev |
|
|
1931 | verbatim, you can have a look at the EV perl module |
|
|
1932 | (L<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
|
|
1933 | the F<libev/> subdirectory and includes them in the F<EV/EVAPI.h> (public |
|
|
1934 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
|
|
1935 | will be compiled. It is pretty complex because it provides its own header |
|
|
1936 | file. |
|
|
1937 | |
|
|
1938 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
|
|
1939 | that everybody includes and which overrides some autoconf choices: |
|
|
1940 | |
|
|
1941 | #define EV_USE_POLL 0 |
|
|
1942 | #define EV_MULTIPLICITY 0 |
|
|
1943 | #define EV_PERIODICS 0 |
|
|
1944 | #define EV_CONFIG_H <config.h> |
|
|
1945 | |
|
|
1946 | #include "ev++.h" |
|
|
1947 | |
|
|
1948 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
|
|
1949 | |
|
|
1950 | #include "ev_cpp.h" |
|
|
1951 | #include "ev.c" |
|
|
1952 | |
|
|
1953 | |
|
|
1954 | =head1 COMPLEXITIES |
|
|
1955 | |
|
|
1956 | In this section the complexities of (many of) the algorithms used inside |
|
|
1957 | libev will be explained. For complexity discussions about backends see the |
|
|
1958 | documentation for C<ev_default_init>. |
|
|
1959 | |
|
|
1960 | =over 4 |
|
|
1961 | |
|
|
1962 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
|
|
1963 | |
|
|
1964 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
|
|
1965 | |
|
|
1966 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
|
|
1967 | |
|
|
1968 | =item Stopping check/prepare/idle watchers: O(1) |
|
|
1969 | |
|
|
1970 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16)) |
|
|
1971 | |
|
|
1972 | =item Finding the next timer per loop iteration: O(1) |
|
|
1973 | |
|
|
1974 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
|
|
1975 | |
|
|
1976 | =item Activating one watcher: O(1) |
|
|
1977 | |
|
|
1978 | =back |
|
|
1979 | |
898 | |
1980 | |
899 | =head1 AUTHOR |
1981 | =head1 AUTHOR |
900 | |
1982 | |
901 | Marc Lehmann <libev@schmorp.de>. |
1983 | Marc Lehmann <libev@schmorp.de>. |
902 | |
1984 | |