… | |
… | |
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 |
|
|
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. |
95 | |
110 | |
96 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
111 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
97 | |
112 | |
98 | Sets the allocation function to use (the prototype is similar to the |
113 | 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 |
114 | realloc C function, the semantics are identical). It is used to allocate |
… | |
… | |
102 | destructive action. The default is your system realloc function. |
117 | destructive action. The default is your system realloc function. |
103 | |
118 | |
104 | You could override this function in high-availability programs to, say, |
119 | 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, |
120 | 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. |
121 | or even to sleep a while and retry until some memory is available. |
|
|
122 | |
|
|
123 | Example: replace the libev allocator with one that waits a bit and then |
|
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124 | retries: better than mine). |
|
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125 | |
|
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126 | static void * |
|
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127 | persistent_realloc (void *ptr, long size) |
|
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128 | { |
|
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129 | for (;;) |
|
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130 | { |
|
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131 | void *newptr = realloc (ptr, size); |
|
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132 | |
|
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133 | if (newptr) |
|
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134 | return newptr; |
|
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135 | |
|
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136 | sleep (60); |
|
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137 | } |
|
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138 | } |
|
|
139 | |
|
|
140 | ... |
|
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141 | ev_set_allocator (persistent_realloc); |
107 | |
142 | |
108 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
143 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
109 | |
144 | |
110 | Set the callback function to call on a retryable syscall error (such |
145 | 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 |
146 | 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 |
148 | 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 |
149 | 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 |
150 | requested operation, or, if the condition doesn't go away, do bad stuff |
116 | (such as abort). |
151 | (such as abort). |
117 | |
152 | |
|
|
153 | Example: do the same thing as libev does internally: |
|
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154 | |
|
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155 | static void |
|
|
156 | fatal_error (const char *msg) |
|
|
157 | { |
|
|
158 | perror (msg); |
|
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159 | abort (); |
|
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160 | } |
|
|
161 | |
|
|
162 | ... |
|
|
163 | ev_set_syserr_cb (fatal_error); |
|
|
164 | |
118 | =back |
165 | =back |
119 | |
166 | |
120 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
167 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
121 | |
168 | |
122 | An event loop is described by a C<struct ev_loop *>. The library knows two |
169 | An event loop is described by a C<struct ev_loop *>. The library knows two |
… | |
… | |
141 | |
188 | |
142 | If you don't know what event loop to use, use the one returned from this |
189 | If you don't know what event loop to use, use the one returned from this |
143 | function. |
190 | function. |
144 | |
191 | |
145 | The flags argument can be used to specify special behaviour or specific |
192 | 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). |
193 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
147 | |
194 | |
148 | It supports the following flags: |
195 | The following flags are supported: |
149 | |
196 | |
150 | =over 4 |
197 | =over 4 |
151 | |
198 | |
152 | =item C<EVFLAG_AUTO> |
199 | =item C<EVFLAG_AUTO> |
153 | |
200 | |
… | |
… | |
198 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
245 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
199 | |
246 | |
200 | Kqueue deserves special mention, as at the time of this writing, it |
247 | Kqueue deserves special mention, as at the time of this writing, it |
201 | was broken on all BSDs except NetBSD (usually it doesn't work with |
248 | was broken on all BSDs except NetBSD (usually it doesn't work with |
202 | anything but sockets and pipes, except on Darwin, where of course its |
249 | anything but sockets and pipes, except on Darwin, where of course its |
203 | completely useless). For this reason its not being "autodetected" unless |
250 | completely useless). For this reason its not being "autodetected" |
204 | you explicitly specify the flags (i.e. you don't use EVFLAG_AUTO). |
251 | unless you explicitly specify it explicitly in the flags (i.e. using |
|
|
252 | C<EVBACKEND_KQUEUE>). |
205 | |
253 | |
206 | It scales in the same way as the epoll backend, but the interface to the |
254 | It scales in the same way as the epoll backend, but the interface to the |
207 | kernel is more efficient (which says nothing about its actual speed, of |
255 | kernel is more efficient (which says nothing about its actual speed, of |
208 | course). While starting and stopping an I/O watcher does not cause an |
256 | course). While starting and stopping an I/O watcher does not cause an |
209 | extra syscall as with epoll, it still adds up to four event changes per |
257 | extra syscall as with epoll, it still adds up to four event changes per |
… | |
… | |
233 | If one or more of these are ored into the flags value, then only these |
281 | If one or more of these are ored into the flags value, then only these |
234 | backends will be tried (in the reverse order as given here). If none are |
282 | backends will be tried (in the reverse order as given here). If none are |
235 | specified, most compiled-in backend will be tried, usually in reverse |
283 | specified, most compiled-in backend will be tried, usually in reverse |
236 | order of their flag values :) |
284 | order of their flag values :) |
237 | |
285 | |
|
|
286 | The most typical usage is like this: |
|
|
287 | |
|
|
288 | if (!ev_default_loop (0)) |
|
|
289 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
290 | |
|
|
291 | Restrict libev to the select and poll backends, and do not allow |
|
|
292 | environment settings to be taken into account: |
|
|
293 | |
|
|
294 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
295 | |
|
|
296 | Use whatever libev has to offer, but make sure that kqueue is used if |
|
|
297 | available (warning, breaks stuff, best use only with your own private |
|
|
298 | event loop and only if you know the OS supports your types of fds): |
|
|
299 | |
|
|
300 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
301 | |
238 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
302 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
239 | |
303 | |
240 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
304 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
241 | always distinct from the default loop. Unlike the default loop, it cannot |
305 | always distinct from the default loop. Unlike the default loop, it cannot |
242 | handle signal and child watchers, and attempts to do so will be greeted by |
306 | handle signal and child watchers, and attempts to do so will be greeted by |
243 | undefined behaviour (or a failed assertion if assertions are enabled). |
307 | undefined behaviour (or a failed assertion if assertions are enabled). |
244 | |
308 | |
|
|
309 | Example: try to create a event loop that uses epoll and nothing else. |
|
|
310 | |
|
|
311 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
|
|
312 | if (!epoller) |
|
|
313 | fatal ("no epoll found here, maybe it hides under your chair"); |
|
|
314 | |
245 | =item ev_default_destroy () |
315 | =item ev_default_destroy () |
246 | |
316 | |
247 | Destroys the default loop again (frees all memory and kernel state |
317 | Destroys the default loop again (frees all memory and kernel state |
248 | etc.). This stops all registered event watchers (by not touching them in |
318 | etc.). This stops all registered event watchers (by not touching them in |
249 | any way whatsoever, although you cannot rely on this :). |
319 | any way whatsoever, although you cannot rely on this :). |
… | |
… | |
286 | use. |
356 | use. |
287 | |
357 | |
288 | =item ev_tstamp ev_now (loop) |
358 | =item ev_tstamp ev_now (loop) |
289 | |
359 | |
290 | Returns the current "event loop time", which is the time the event loop |
360 | Returns the current "event loop time", which is the time the event loop |
291 | got events and started processing them. This timestamp does not change |
361 | received events and started processing them. This timestamp does not |
292 | as long as callbacks are being processed, and this is also the base time |
362 | change as long as callbacks are being processed, and this is also the base |
293 | used for relative timers. You can treat it as the timestamp of the event |
363 | time used for relative timers. You can treat it as the timestamp of the |
294 | occuring (or more correctly, the mainloop finding out about it). |
364 | event occuring (or more correctly, libev finding out about it). |
295 | |
365 | |
296 | =item ev_loop (loop, int flags) |
366 | =item ev_loop (loop, int flags) |
297 | |
367 | |
298 | Finally, this is it, the event handler. This function usually is called |
368 | Finally, this is it, the event handler. This function usually is called |
299 | after you initialised all your watchers and you want to start handling |
369 | after you initialised all your watchers and you want to start handling |
300 | events. |
370 | events. |
301 | |
371 | |
302 | If the flags argument is specified as 0, it will not return until either |
372 | If the flags argument is specified as C<0>, it will not return until |
303 | no event watchers are active anymore or C<ev_unloop> was called. |
373 | either no event watchers are active anymore or C<ev_unloop> was called. |
|
|
374 | |
|
|
375 | Please note that an explicit C<ev_unloop> is usually better than |
|
|
376 | relying on all watchers to be stopped when deciding when a program has |
|
|
377 | finished (especially in interactive programs), but having a program that |
|
|
378 | automatically loops as long as it has to and no longer by virtue of |
|
|
379 | relying on its watchers stopping correctly is a thing of beauty. |
304 | |
380 | |
305 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
381 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
306 | those events and any outstanding ones, but will not block your process in |
382 | those events and any outstanding ones, but will not block your process in |
307 | case there are no events and will return after one iteration of the loop. |
383 | case there are no events and will return after one iteration of the loop. |
308 | |
384 | |
309 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
385 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
310 | neccessary) and will handle those and any outstanding ones. It will block |
386 | neccessary) and will handle those and any outstanding ones. It will block |
311 | your process until at least one new event arrives, and will return after |
387 | your process until at least one new event arrives, and will return after |
312 | one iteration of the loop. |
388 | one iteration of the loop. This is useful if you are waiting for some |
|
|
389 | external event in conjunction with something not expressible using other |
|
|
390 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
|
|
391 | usually a better approach for this kind of thing. |
313 | |
392 | |
314 | This flags value could be used to implement alternative looping |
|
|
315 | constructs, but the C<prepare> and C<check> watchers provide a better and |
|
|
316 | more generic mechanism. |
|
|
317 | |
|
|
318 | Here are the gory details of what ev_loop does: |
393 | Here are the gory details of what C<ev_loop> does: |
319 | |
394 | |
320 | 1. If there are no active watchers (reference count is zero), return. |
395 | * If there are no active watchers (reference count is zero), return. |
321 | 2. Queue and immediately call all prepare watchers. |
396 | - Queue prepare watchers and then call all outstanding watchers. |
322 | 3. If we have been forked, recreate the kernel state. |
397 | - If we have been forked, recreate the kernel state. |
323 | 4. Update the kernel state with all outstanding changes. |
398 | - Update the kernel state with all outstanding changes. |
324 | 5. Update the "event loop time". |
399 | - Update the "event loop time". |
325 | 6. Calculate for how long to block. |
400 | - Calculate for how long to block. |
326 | 7. Block the process, waiting for events. |
401 | - Block the process, waiting for any events. |
|
|
402 | - Queue all outstanding I/O (fd) events. |
327 | 8. Update the "event loop time" and do time jump handling. |
403 | - Update the "event loop time" and do time jump handling. |
328 | 9. Queue all outstanding timers. |
404 | - Queue all outstanding timers. |
329 | 10. Queue all outstanding periodics. |
405 | - Queue all outstanding periodics. |
330 | 11. If no events are pending now, queue all idle watchers. |
406 | - If no events are pending now, queue all idle watchers. |
331 | 12. Queue all check watchers. |
407 | - Queue all check watchers. |
332 | 13. Call all queued watchers in reverse order (i.e. check watchers first). |
408 | - Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
409 | Signals and child watchers are implemented as I/O watchers, and will |
|
|
410 | be handled here by queueing them when their watcher gets executed. |
333 | 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
411 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
334 | was used, return, otherwise continue with step #1. |
412 | were used, return, otherwise continue with step *. |
|
|
413 | |
|
|
414 | Example: queue some jobs and then loop until no events are outsanding |
|
|
415 | anymore. |
|
|
416 | |
|
|
417 | ... queue jobs here, make sure they register event watchers as long |
|
|
418 | ... as they still have work to do (even an idle watcher will do..) |
|
|
419 | ev_loop (my_loop, 0); |
|
|
420 | ... jobs done. yeah! |
335 | |
421 | |
336 | =item ev_unloop (loop, how) |
422 | =item ev_unloop (loop, how) |
337 | |
423 | |
338 | Can be used to make a call to C<ev_loop> return early (but only after it |
424 | Can be used to make a call to C<ev_loop> return early (but only after it |
339 | has processed all outstanding events). The C<how> argument must be either |
425 | has processed all outstanding events). The C<how> argument must be either |
… | |
… | |
353 | visible to the libev user and should not keep C<ev_loop> from exiting if |
439 | visible to the libev user and should not keep C<ev_loop> from exiting if |
354 | no event watchers registered by it are active. It is also an excellent |
440 | no event watchers registered by it are active. It is also an excellent |
355 | way to do this for generic recurring timers or from within third-party |
441 | way to do this for generic recurring timers or from within third-party |
356 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
442 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
357 | |
443 | |
|
|
444 | Example: create a signal watcher, but keep it from keeping C<ev_loop> |
|
|
445 | running when nothing else is active. |
|
|
446 | |
|
|
447 | struct dv_signal exitsig; |
|
|
448 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
|
|
449 | ev_signal_start (myloop, &exitsig); |
|
|
450 | evf_unref (myloop); |
|
|
451 | |
|
|
452 | Example: for some weird reason, unregister the above signal handler again. |
|
|
453 | |
|
|
454 | ev_ref (myloop); |
|
|
455 | ev_signal_stop (myloop, &exitsig); |
|
|
456 | |
358 | =back |
457 | =back |
359 | |
458 | |
360 | =head1 ANATOMY OF A WATCHER |
459 | =head1 ANATOMY OF A WATCHER |
361 | |
460 | |
362 | A watcher is a structure that you create and register to record your |
461 | A watcher is a structure that you create and register to record your |
… | |
… | |
502 | |
601 | |
503 | =head1 WATCHER TYPES |
602 | =head1 WATCHER TYPES |
504 | |
603 | |
505 | This section describes each watcher in detail, but will not repeat |
604 | This section describes each watcher in detail, but will not repeat |
506 | information given in the last section. |
605 | information given in the last section. |
|
|
606 | |
507 | |
607 | |
508 | =head2 C<ev_io> - is this file descriptor readable or writable |
608 | =head2 C<ev_io> - is this file descriptor readable or writable |
509 | |
609 | |
510 | I/O watchers check whether a file descriptor is readable or writable |
610 | I/O watchers check whether a file descriptor is readable or writable |
511 | in each iteration of the event loop (This behaviour is called |
611 | in each iteration of the event loop (This behaviour is called |
… | |
… | |
549 | typical ways of handling events, so its a good idea to use non-blocking |
649 | typical ways of handling events, so its a good idea to use non-blocking |
550 | I/O unconditionally. |
650 | I/O unconditionally. |
551 | |
651 | |
552 | =back |
652 | =back |
553 | |
653 | |
|
|
654 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
|
|
655 | readable, but only once. Since it is likely line-buffered, you could |
|
|
656 | attempt to read a whole line in the callback: |
|
|
657 | |
|
|
658 | static void |
|
|
659 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
660 | { |
|
|
661 | ev_io_stop (loop, w); |
|
|
662 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
|
|
663 | } |
|
|
664 | |
|
|
665 | ... |
|
|
666 | struct ev_loop *loop = ev_default_init (0); |
|
|
667 | struct ev_io stdin_readable; |
|
|
668 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
|
|
669 | ev_io_start (loop, &stdin_readable); |
|
|
670 | ev_loop (loop, 0); |
|
|
671 | |
|
|
672 | |
554 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
673 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
555 | |
674 | |
556 | Timer watchers are simple relative timers that generate an event after a |
675 | Timer watchers are simple relative timers that generate an event after a |
557 | given time, and optionally repeating in regular intervals after that. |
676 | given time, and optionally repeating in regular intervals after that. |
558 | |
677 | |
… | |
… | |
610 | state where you do not expect data to travel on the socket, you can stop |
729 | state where you do not expect data to travel on the socket, you can stop |
611 | the timer, and again will automatically restart it if need be. |
730 | the timer, and again will automatically restart it if need be. |
612 | |
731 | |
613 | =back |
732 | =back |
614 | |
733 | |
|
|
734 | Example: create a timer that fires after 60 seconds. |
|
|
735 | |
|
|
736 | static void |
|
|
737 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
738 | { |
|
|
739 | .. one minute over, w is actually stopped right here |
|
|
740 | } |
|
|
741 | |
|
|
742 | struct ev_timer mytimer; |
|
|
743 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
|
|
744 | ev_timer_start (loop, &mytimer); |
|
|
745 | |
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|
746 | Example: create a timeout timer that times out after 10 seconds of |
|
|
747 | inactivity. |
|
|
748 | |
|
|
749 | static void |
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|
750 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
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|
751 | { |
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|
752 | .. ten seconds without any activity |
|
|
753 | } |
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|
754 | |
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|
755 | struct ev_timer mytimer; |
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|
756 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
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757 | ev_timer_again (&mytimer); /* start timer */ |
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758 | ev_loop (loop, 0); |
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|
759 | |
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|
760 | // and in some piece of code that gets executed on any "activity": |
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|
761 | // reset the timeout to start ticking again at 10 seconds |
|
|
762 | ev_timer_again (&mytimer); |
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|
763 | |
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|
764 | |
615 | =head2 C<ev_periodic> - to cron or not to cron |
765 | =head2 C<ev_periodic> - to cron or not to cron |
616 | |
766 | |
617 | Periodic watchers are also timers of a kind, but they are very versatile |
767 | Periodic watchers are also timers of a kind, but they are very versatile |
618 | (and unfortunately a bit complex). |
768 | (and unfortunately a bit complex). |
619 | |
769 | |
… | |
… | |
714 | a different time than the last time it was called (e.g. in a crond like |
864 | a different time than the last time it was called (e.g. in a crond like |
715 | program when the crontabs have changed). |
865 | program when the crontabs have changed). |
716 | |
866 | |
717 | =back |
867 | =back |
718 | |
868 | |
|
|
869 | Example: call a callback every hour, or, more precisely, whenever the |
|
|
870 | system clock is divisible by 3600. The callback invocation times have |
|
|
871 | potentially a lot of jittering, but good long-term stability. |
|
|
872 | |
|
|
873 | static void |
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|
874 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
875 | { |
|
|
876 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
|
|
877 | } |
|
|
878 | |
|
|
879 | struct ev_periodic hourly_tick; |
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|
880 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
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|
881 | ev_periodic_start (loop, &hourly_tick); |
|
|
882 | |
|
|
883 | Example: the same as above, but use a reschedule callback to do it: |
|
|
884 | |
|
|
885 | #include <math.h> |
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|
886 | |
|
|
887 | static ev_tstamp |
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|
888 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
|
|
889 | { |
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890 | return fmod (now, 3600.) + 3600.; |
|
|
891 | } |
|
|
892 | |
|
|
893 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
|
|
894 | |
|
|
895 | Example: call a callback every hour, starting now: |
|
|
896 | |
|
|
897 | struct ev_periodic hourly_tick; |
|
|
898 | ev_periodic_init (&hourly_tick, clock_cb, |
|
|
899 | fmod (ev_now (loop), 3600.), 3600., 0); |
|
|
900 | ev_periodic_start (loop, &hourly_tick); |
|
|
901 | |
|
|
902 | |
719 | =head2 C<ev_signal> - signal me when a signal gets signalled |
903 | =head2 C<ev_signal> - signal me when a signal gets signalled |
720 | |
904 | |
721 | Signal watchers will trigger an event when the process receives a specific |
905 | Signal watchers will trigger an event when the process receives a specific |
722 | signal one or more times. Even though signals are very asynchronous, libev |
906 | signal one or more times. Even though signals are very asynchronous, libev |
723 | will try it's best to deliver signals synchronously, i.e. as part of the |
907 | will try it's best to deliver signals synchronously, i.e. as part of the |
… | |
… | |
758 | the status word (use the macros from C<sys/wait.h> and see your systems |
942 | the status word (use the macros from C<sys/wait.h> and see your systems |
759 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
943 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
760 | process causing the status change. |
944 | process causing the status change. |
761 | |
945 | |
762 | =back |
946 | =back |
|
|
947 | |
|
|
948 | Example: try to exit cleanly on SIGINT and SIGTERM. |
|
|
949 | |
|
|
950 | static void |
|
|
951 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
952 | { |
|
|
953 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
954 | } |
|
|
955 | |
|
|
956 | struct ev_signal signal_watcher; |
|
|
957 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
958 | ev_signal_start (loop, &sigint_cb); |
|
|
959 | |
763 | |
960 | |
764 | =head2 C<ev_idle> - when you've got nothing better to do |
961 | =head2 C<ev_idle> - when you've got nothing better to do |
765 | |
962 | |
766 | Idle watchers trigger events when there are no other events are pending |
963 | Idle watchers trigger events when there are no other events are pending |
767 | (prepare, check and other idle watchers do not count). That is, as long |
964 | (prepare, check and other idle watchers do not count). That is, as long |
… | |
… | |
786 | Initialises and configures the idle watcher - it has no parameters of any |
983 | Initialises and configures the idle watcher - it has no parameters of any |
787 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
984 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
788 | believe me. |
985 | believe me. |
789 | |
986 | |
790 | =back |
987 | =back |
|
|
988 | |
|
|
989 | Example: dynamically allocate an C<ev_idle>, start it, and in the |
|
|
990 | callback, free it. Alos, use no error checking, as usual. |
|
|
991 | |
|
|
992 | static void |
|
|
993 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
|
|
994 | { |
|
|
995 | free (w); |
|
|
996 | // now do something you wanted to do when the program has |
|
|
997 | // no longer asnything immediate to do. |
|
|
998 | } |
|
|
999 | |
|
|
1000 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
|
|
1001 | ev_idle_init (idle_watcher, idle_cb); |
|
|
1002 | ev_idle_start (loop, idle_cb); |
|
|
1003 | |
791 | |
1004 | |
792 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
1005 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
793 | |
1006 | |
794 | Prepare and check watchers are usually (but not always) used in tandem: |
1007 | Prepare and check watchers are usually (but not always) used in tandem: |
795 | prepare watchers get invoked before the process blocks and check watchers |
1008 | prepare watchers get invoked before the process blocks and check watchers |
… | |
… | |
827 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1040 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
828 | macros, but using them is utterly, utterly and completely pointless. |
1041 | macros, but using them is utterly, utterly and completely pointless. |
829 | |
1042 | |
830 | =back |
1043 | =back |
831 | |
1044 | |
|
|
1045 | Example: *TODO*. |
|
|
1046 | |
|
|
1047 | |
832 | =head1 OTHER FUNCTIONS |
1048 | =head1 OTHER FUNCTIONS |
833 | |
1049 | |
834 | There are some other functions of possible interest. Described. Here. Now. |
1050 | There are some other functions of possible interest. Described. Here. Now. |
835 | |
1051 | |
836 | =over 4 |
1052 | =over 4 |
… | |
… | |
882 | |
1098 | |
883 | Feed an event as if the given signal occured (loop must be the default loop!). |
1099 | Feed an event as if the given signal occured (loop must be the default loop!). |
884 | |
1100 | |
885 | =back |
1101 | =back |
886 | |
1102 | |
|
|
1103 | |
887 | =head1 LIBEVENT EMULATION |
1104 | =head1 LIBEVENT EMULATION |
888 | |
1105 | |
889 | Libev offers a compatibility emulation layer for libevent. It cannot |
1106 | Libev offers a compatibility emulation layer for libevent. It cannot |
890 | emulate the internals of libevent, so here are some usage hints: |
1107 | emulate the internals of libevent, so here are some usage hints: |
891 | |
1108 | |