… | |
… | |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
8 | |
8 | |
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9 | =head1 EXAMPLE PROGRAM |
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10 | |
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11 | #include <ev.h> |
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12 | |
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13 | ev_io stdin_watcher; |
|
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14 | ev_timer timeout_watcher; |
|
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15 | |
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16 | /* called when data readable on stdin */ |
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17 | static void |
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18 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
|
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19 | { |
|
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20 | /* puts ("stdin ready"); */ |
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21 | ev_io_stop (EV_A_ w); /* just a syntax example */ |
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22 | ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
|
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23 | } |
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24 | |
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25 | static void |
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26 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
|
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27 | { |
|
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28 | /* puts ("timeout"); */ |
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29 | ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
|
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30 | } |
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31 | |
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32 | int |
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33 | main (void) |
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34 | { |
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35 | struct ev_loop *loop = ev_default_loop (0); |
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36 | |
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37 | /* initialise an io watcher, then start it */ |
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38 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
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39 | ev_io_start (loop, &stdin_watcher); |
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40 | |
|
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41 | /* simple non-repeating 5.5 second timeout */ |
|
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42 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
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43 | ev_timer_start (loop, &timeout_watcher); |
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44 | |
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45 | /* loop till timeout or data ready */ |
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46 | ev_loop (loop, 0); |
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47 | |
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48 | return 0; |
|
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49 | } |
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50 | |
9 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
|
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52 | |
|
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53 | The newest version of this document is also available as a html-formatted |
|
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54 | web page you might find easier to navigate when reading it for the first |
|
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55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
10 | |
56 | |
11 | Libev is an event loop: you register interest in certain events (such as a |
57 | Libev is an event loop: you register interest in certain events (such as a |
12 | file descriptor being readable or a timeout occuring), and it will manage |
58 | file descriptor being readable or a timeout occuring), and it will manage |
13 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
14 | |
60 | |
… | |
… | |
21 | details of the event, and then hand it over to libev by I<starting> the |
67 | details of the event, and then hand it over to libev by I<starting> the |
22 | watcher. |
68 | watcher. |
23 | |
69 | |
24 | =head1 FEATURES |
70 | =head1 FEATURES |
25 | |
71 | |
26 | Libev supports select, poll, the linux-specific epoll and the bsd-specific |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
27 | kqueue mechanisms for file descriptor events, relative timers, absolute |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
28 | timers with customised rescheduling, signal events, process status change |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
29 | events (related to SIGCHLD), and event watchers dealing with the event |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
30 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
76 | with customised rescheduling (C<ev_periodic>), synchronous signals |
|
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77 | (C<ev_signal>), process status change events (C<ev_child>), and event |
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78 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
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79 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
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80 | file watchers (C<ev_stat>) and even limited support for fork events |
|
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81 | (C<ev_fork>). |
|
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82 | |
|
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83 | It also is quite fast (see this |
31 | fast (see this L<benchmark|http://libev.schmorp.de/bench.html> comparing |
84 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
32 | it to libevent for example). |
85 | for example). |
33 | |
86 | |
34 | =head1 CONVENTIONS |
87 | =head1 CONVENTIONS |
35 | |
88 | |
36 | Libev is very configurable. In this manual the default configuration |
89 | Libev is very configurable. In this manual the default configuration will |
37 | will be described, which supports multiple event loops. For more info |
90 | be described, which supports multiple event loops. For more info about |
38 | about various configuration options please have a look at the file |
91 | various configuration options please have a look at B<EMBED> section in |
39 | F<README.embed> in the libev distribution. If libev was configured without |
92 | this manual. If libev was configured without support for multiple event |
40 | support for multiple event loops, then all functions taking an initial |
93 | loops, then all functions taking an initial argument of name C<loop> |
41 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
94 | (which is always of type C<struct ev_loop *>) will not have this argument. |
42 | will not have this argument. |
|
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43 | |
95 | |
44 | =head1 TIME REPRESENTATION |
96 | =head1 TIME REPRESENTATION |
45 | |
97 | |
46 | Libev represents time as a single floating point number, representing the |
98 | Libev represents time as a single floating point number, representing the |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
100 | 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 |
101 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
50 | to the C<double> type in C, and when you need to do any calculations on |
102 | to the C<double> type in C, and when you need to do any calculations on |
51 | it, you should treat it as such. |
103 | it, you should treat it as such. |
52 | |
104 | |
53 | |
|
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54 | =head1 GLOBAL FUNCTIONS |
105 | =head1 GLOBAL FUNCTIONS |
55 | |
106 | |
56 | These functions can be called anytime, even before initialising the |
107 | These functions can be called anytime, even before initialising the |
57 | library in any way. |
108 | library in any way. |
58 | |
109 | |
… | |
… | |
77 | Usually, it's a good idea to terminate if the major versions mismatch, |
128 | Usually, it's a good idea to terminate if the major versions mismatch, |
78 | as this indicates an incompatible change. Minor versions are usually |
129 | as this indicates an incompatible change. Minor versions are usually |
79 | compatible to older versions, so a larger minor version alone is usually |
130 | compatible to older versions, so a larger minor version alone is usually |
80 | not a problem. |
131 | not a problem. |
81 | |
132 | |
82 | Example: make sure we haven't accidentally been linked against the wrong |
133 | Example: Make sure we haven't accidentally been linked against the wrong |
83 | version: |
134 | version. |
84 | |
135 | |
85 | assert (("libev version mismatch", |
136 | assert (("libev version mismatch", |
86 | ev_version_major () == EV_VERSION_MAJOR |
137 | ev_version_major () == EV_VERSION_MAJOR |
87 | && ev_version_minor () >= EV_VERSION_MINOR)); |
138 | && ev_version_minor () >= EV_VERSION_MINOR)); |
88 | |
139 | |
… | |
… | |
118 | |
169 | |
119 | See the description of C<ev_embed> watchers for more info. |
170 | See the description of C<ev_embed> watchers for more info. |
120 | |
171 | |
121 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
172 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
122 | |
173 | |
123 | Sets the allocation function to use (the prototype is similar to the |
174 | Sets the allocation function to use (the prototype is similar - the |
124 | realloc C function, the semantics are identical). It is used to allocate |
175 | semantics is identical - to the realloc C function). It is used to |
125 | and free memory (no surprises here). If it returns zero when memory |
176 | allocate and free memory (no surprises here). If it returns zero when |
126 | needs to be allocated, the library might abort or take some potentially |
177 | memory needs to be allocated, the library might abort or take some |
127 | destructive action. The default is your system realloc function. |
178 | potentially destructive action. The default is your system realloc |
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179 | function. |
128 | |
180 | |
129 | You could override this function in high-availability programs to, say, |
181 | You could override this function in high-availability programs to, say, |
130 | free some memory if it cannot allocate memory, to use a special allocator, |
182 | free some memory if it cannot allocate memory, to use a special allocator, |
131 | or even to sleep a while and retry until some memory is available. |
183 | or even to sleep a while and retry until some memory is available. |
132 | |
184 | |
133 | Example: replace the libev allocator with one that waits a bit and then |
185 | Example: Replace the libev allocator with one that waits a bit and then |
134 | retries: better than mine). |
186 | retries). |
135 | |
187 | |
136 | static void * |
188 | static void * |
137 | persistent_realloc (void *ptr, long size) |
189 | persistent_realloc (void *ptr, size_t size) |
138 | { |
190 | { |
139 | for (;;) |
191 | for (;;) |
140 | { |
192 | { |
141 | void *newptr = realloc (ptr, size); |
193 | void *newptr = realloc (ptr, size); |
142 | |
194 | |
… | |
… | |
158 | callback is set, then libev will expect it to remedy the sitution, no |
210 | callback is set, then libev will expect it to remedy the sitution, no |
159 | matter what, when it returns. That is, libev will generally retry the |
211 | matter what, when it returns. That is, libev will generally retry the |
160 | requested operation, or, if the condition doesn't go away, do bad stuff |
212 | requested operation, or, if the condition doesn't go away, do bad stuff |
161 | (such as abort). |
213 | (such as abort). |
162 | |
214 | |
163 | Example: do the same thing as libev does internally: |
215 | Example: This is basically the same thing that libev does internally, too. |
164 | |
216 | |
165 | static void |
217 | static void |
166 | fatal_error (const char *msg) |
218 | fatal_error (const char *msg) |
167 | { |
219 | { |
168 | perror (msg); |
220 | perror (msg); |
… | |
… | |
218 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
270 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
219 | override the flags completely if it is found in the environment. This is |
271 | override the flags completely if it is found in the environment. This is |
220 | useful to try out specific backends to test their performance, or to work |
272 | useful to try out specific backends to test their performance, or to work |
221 | around bugs. |
273 | around bugs. |
222 | |
274 | |
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275 | =item C<EVFLAG_FORKCHECK> |
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276 | |
|
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277 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
|
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278 | a fork, you can also make libev check for a fork in each iteration by |
|
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279 | enabling this flag. |
|
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280 | |
|
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281 | This works by calling C<getpid ()> on every iteration of the loop, |
|
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282 | and thus this might slow down your event loop if you do a lot of loop |
|
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283 | iterations and little real work, but is usually not noticeable (on my |
|
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284 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
|
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285 | without a syscall and thus I<very> fast, but my Linux system also has |
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286 | C<pthread_atfork> which is even faster). |
|
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287 | |
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288 | The big advantage of this flag is that you can forget about fork (and |
|
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289 | forget about forgetting to tell libev about forking) when you use this |
|
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290 | flag. |
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291 | |
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292 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
|
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293 | environment variable. |
|
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294 | |
223 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
295 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
224 | |
296 | |
225 | This is your standard select(2) backend. Not I<completely> standard, as |
297 | This is your standard select(2) backend. Not I<completely> standard, as |
226 | libev tries to roll its own fd_set with no limits on the number of fds, |
298 | libev tries to roll its own fd_set with no limits on the number of fds, |
227 | but if that fails, expect a fairly low limit on the number of fds when |
299 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
314 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
386 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
315 | always distinct from the default loop. Unlike the default loop, it cannot |
387 | always distinct from the default loop. Unlike the default loop, it cannot |
316 | handle signal and child watchers, and attempts to do so will be greeted by |
388 | handle signal and child watchers, and attempts to do so will be greeted by |
317 | undefined behaviour (or a failed assertion if assertions are enabled). |
389 | undefined behaviour (or a failed assertion if assertions are enabled). |
318 | |
390 | |
319 | Example: try to create a event loop that uses epoll and nothing else. |
391 | Example: Try to create a event loop that uses epoll and nothing else. |
320 | |
392 | |
321 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
393 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
322 | if (!epoller) |
394 | if (!epoller) |
323 | fatal ("no epoll found here, maybe it hides under your chair"); |
395 | fatal ("no epoll found here, maybe it hides under your chair"); |
324 | |
396 | |
… | |
… | |
361 | =item ev_loop_fork (loop) |
433 | =item ev_loop_fork (loop) |
362 | |
434 | |
363 | Like C<ev_default_fork>, but acts on an event loop created by |
435 | Like C<ev_default_fork>, but acts on an event loop created by |
364 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
436 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
365 | after fork, and how you do this is entirely your own problem. |
437 | after fork, and how you do this is entirely your own problem. |
|
|
438 | |
|
|
439 | =item unsigned int ev_loop_count (loop) |
|
|
440 | |
|
|
441 | Returns the count of loop iterations for the loop, which is identical to |
|
|
442 | the number of times libev did poll for new events. It starts at C<0> and |
|
|
443 | happily wraps around with enough iterations. |
|
|
444 | |
|
|
445 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
446 | "ticks" the number of loop iterations), as it roughly corresponds with |
|
|
447 | C<ev_prepare> and C<ev_check> calls. |
366 | |
448 | |
367 | =item unsigned int ev_backend (loop) |
449 | =item unsigned int ev_backend (loop) |
368 | |
450 | |
369 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
451 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
370 | use. |
452 | use. |
… | |
… | |
423 | Signals and child watchers are implemented as I/O watchers, and will |
505 | Signals and child watchers are implemented as I/O watchers, and will |
424 | be handled here by queueing them when their watcher gets executed. |
506 | be handled here by queueing them when their watcher gets executed. |
425 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
507 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
426 | were used, return, otherwise continue with step *. |
508 | were used, return, otherwise continue with step *. |
427 | |
509 | |
428 | Example: queue some jobs and then loop until no events are outsanding |
510 | Example: Queue some jobs and then loop until no events are outsanding |
429 | anymore. |
511 | anymore. |
430 | |
512 | |
431 | ... queue jobs here, make sure they register event watchers as long |
513 | ... 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..) |
514 | ... as they still have work to do (even an idle watcher will do..) |
433 | ev_loop (my_loop, 0); |
515 | ev_loop (my_loop, 0); |
… | |
… | |
453 | visible to the libev user and should not keep C<ev_loop> from exiting if |
535 | visible to the libev user and should not keep C<ev_loop> from exiting if |
454 | no event watchers registered by it are active. It is also an excellent |
536 | no event watchers registered by it are active. It is also an excellent |
455 | way to do this for generic recurring timers or from within third-party |
537 | way to do this for generic recurring timers or from within third-party |
456 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
538 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
457 | |
539 | |
458 | Example: create a signal watcher, but keep it from keeping C<ev_loop> |
540 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
459 | running when nothing else is active. |
541 | running when nothing else is active. |
460 | |
542 | |
461 | struct dv_signal exitsig; |
543 | struct ev_signal exitsig; |
462 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
544 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
463 | ev_signal_start (myloop, &exitsig); |
545 | ev_signal_start (loop, &exitsig); |
464 | evf_unref (myloop); |
546 | evf_unref (loop); |
465 | |
547 | |
466 | Example: for some weird reason, unregister the above signal handler again. |
548 | Example: For some weird reason, unregister the above signal handler again. |
467 | |
549 | |
468 | ev_ref (myloop); |
550 | ev_ref (loop); |
469 | ev_signal_stop (myloop, &exitsig); |
551 | ev_signal_stop (loop, &exitsig); |
470 | |
552 | |
471 | =back |
553 | =back |
|
|
554 | |
472 | |
555 | |
473 | =head1 ANATOMY OF A WATCHER |
556 | =head1 ANATOMY OF A WATCHER |
474 | |
557 | |
475 | A watcher is a structure that you create and register to record your |
558 | A watcher is a structure that you create and register to record your |
476 | interest in some event. For instance, if you want to wait for STDIN to |
559 | interest in some event. For instance, if you want to wait for STDIN to |
… | |
… | |
543 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
626 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
544 | |
627 | |
545 | =item C<EV_CHILD> |
628 | =item C<EV_CHILD> |
546 | |
629 | |
547 | The pid specified in the C<ev_child> watcher has received a status change. |
630 | The pid specified in the C<ev_child> watcher has received a status change. |
|
|
631 | |
|
|
632 | =item C<EV_STAT> |
|
|
633 | |
|
|
634 | The path specified in the C<ev_stat> watcher changed its attributes somehow. |
548 | |
635 | |
549 | =item C<EV_IDLE> |
636 | =item C<EV_IDLE> |
550 | |
637 | |
551 | The C<ev_idle> watcher has determined that you have nothing better to do. |
638 | The C<ev_idle> watcher has determined that you have nothing better to do. |
552 | |
639 | |
… | |
… | |
560 | received events. Callbacks of both watcher types can start and stop as |
647 | received events. Callbacks of both watcher types can start and stop as |
561 | many watchers as they want, and all of them will be taken into account |
648 | many watchers as they want, and all of them will be taken into account |
562 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
649 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
563 | C<ev_loop> from blocking). |
650 | C<ev_loop> from blocking). |
564 | |
651 | |
|
|
652 | =item C<EV_EMBED> |
|
|
653 | |
|
|
654 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
|
|
655 | |
|
|
656 | =item C<EV_FORK> |
|
|
657 | |
|
|
658 | The event loop has been resumed in the child process after fork (see |
|
|
659 | C<ev_fork>). |
|
|
660 | |
565 | =item C<EV_ERROR> |
661 | =item C<EV_ERROR> |
566 | |
662 | |
567 | An unspecified error has occured, the watcher has been stopped. This might |
663 | An unspecified error has occured, the watcher has been stopped. This might |
568 | happen because the watcher could not be properly started because libev |
664 | happen because the watcher could not be properly started because libev |
569 | ran out of memory, a file descriptor was found to be closed or any other |
665 | ran out of memory, a file descriptor was found to be closed or any other |
… | |
… | |
576 | with the error from read() or write(). This will not work in multithreaded |
672 | with the error from read() or write(). This will not work in multithreaded |
577 | programs, though, so beware. |
673 | programs, though, so beware. |
578 | |
674 | |
579 | =back |
675 | =back |
580 | |
676 | |
581 | =head2 SUMMARY OF GENERIC WATCHER FUNCTIONS |
677 | =head2 GENERIC WATCHER FUNCTIONS |
582 | |
678 | |
583 | In the following description, C<TYPE> stands for the watcher type, |
679 | In the following description, C<TYPE> stands for the watcher type, |
584 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
680 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
585 | |
681 | |
586 | =over 4 |
682 | =over 4 |
… | |
… | |
595 | which rolls both calls into one. |
691 | which rolls both calls into one. |
596 | |
692 | |
597 | You can reinitialise a watcher at any time as long as it has been stopped |
693 | You can reinitialise a watcher at any time as long as it has been stopped |
598 | (or never started) and there are no pending events outstanding. |
694 | (or never started) and there are no pending events outstanding. |
599 | |
695 | |
600 | The callbakc is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
696 | The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
601 | int revents)>. |
697 | int revents)>. |
602 | |
698 | |
603 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
699 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
604 | |
700 | |
605 | This macro initialises the type-specific parts of a watcher. You need to |
701 | This macro initialises the type-specific parts of a watcher. You need to |
… | |
… | |
640 | =item bool ev_is_pending (ev_TYPE *watcher) |
736 | =item bool ev_is_pending (ev_TYPE *watcher) |
641 | |
737 | |
642 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
738 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
643 | events but its callback has not yet been invoked). As long as a watcher |
739 | events but its callback has not yet been invoked). As long as a watcher |
644 | is pending (but not active) you must not call an init function on it (but |
740 | is pending (but not active) you must not call an init function on it (but |
645 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
741 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
646 | libev (e.g. you cnanot C<free ()> it). |
742 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
|
|
743 | it). |
647 | |
744 | |
648 | =item callback = ev_cb (ev_TYPE *watcher) |
745 | =item callback ev_cb (ev_TYPE *watcher) |
649 | |
746 | |
650 | Returns the callback currently set on the watcher. |
747 | Returns the callback currently set on the watcher. |
651 | |
748 | |
652 | =item ev_cb_set (ev_TYPE *watcher, callback) |
749 | =item ev_cb_set (ev_TYPE *watcher, callback) |
653 | |
750 | |
654 | Change the callback. You can change the callback at virtually any time |
751 | Change the callback. You can change the callback at virtually any time |
655 | (modulo threads). |
752 | (modulo threads). |
|
|
753 | |
|
|
754 | =item ev_set_priority (ev_TYPE *watcher, priority) |
|
|
755 | |
|
|
756 | =item int ev_priority (ev_TYPE *watcher) |
|
|
757 | |
|
|
758 | Set and query the priority of the watcher. The priority is a small |
|
|
759 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
|
|
760 | (default: C<-2>). Pending watchers with higher priority will be invoked |
|
|
761 | before watchers with lower priority, but priority will not keep watchers |
|
|
762 | from being executed (except for C<ev_idle> watchers). |
|
|
763 | |
|
|
764 | This means that priorities are I<only> used for ordering callback |
|
|
765 | invocation after new events have been received. This is useful, for |
|
|
766 | example, to reduce latency after idling, or more often, to bind two |
|
|
767 | watchers on the same event and make sure one is called first. |
|
|
768 | |
|
|
769 | If you need to suppress invocation when higher priority events are pending |
|
|
770 | you need to look at C<ev_idle> watchers, which provide this functionality. |
|
|
771 | |
|
|
772 | You I<must not> change the priority of a watcher as long as it is active or |
|
|
773 | pending. |
|
|
774 | |
|
|
775 | The default priority used by watchers when no priority has been set is |
|
|
776 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
777 | |
|
|
778 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
|
|
779 | fine, as long as you do not mind that the priority value you query might |
|
|
780 | or might not have been adjusted to be within valid range. |
656 | |
781 | |
657 | =back |
782 | =back |
658 | |
783 | |
659 | |
784 | |
660 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
785 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
681 | { |
806 | { |
682 | struct my_io *w = (struct my_io *)w_; |
807 | struct my_io *w = (struct my_io *)w_; |
683 | ... |
808 | ... |
684 | } |
809 | } |
685 | |
810 | |
686 | More interesting and less C-conformant ways of catsing your callback type |
811 | More interesting and less C-conformant ways of casting your callback type |
687 | have been omitted.... |
812 | instead have been omitted. |
|
|
813 | |
|
|
814 | Another common scenario is having some data structure with multiple |
|
|
815 | watchers: |
|
|
816 | |
|
|
817 | struct my_biggy |
|
|
818 | { |
|
|
819 | int some_data; |
|
|
820 | ev_timer t1; |
|
|
821 | ev_timer t2; |
|
|
822 | } |
|
|
823 | |
|
|
824 | In this case getting the pointer to C<my_biggy> is a bit more complicated, |
|
|
825 | you need to use C<offsetof>: |
|
|
826 | |
|
|
827 | #include <stddef.h> |
|
|
828 | |
|
|
829 | static void |
|
|
830 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
831 | { |
|
|
832 | struct my_biggy big = (struct my_biggy * |
|
|
833 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
834 | } |
|
|
835 | |
|
|
836 | static void |
|
|
837 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
838 | { |
|
|
839 | struct my_biggy big = (struct my_biggy * |
|
|
840 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
841 | } |
688 | |
842 | |
689 | |
843 | |
690 | =head1 WATCHER TYPES |
844 | =head1 WATCHER TYPES |
691 | |
845 | |
692 | This section describes each watcher in detail, but will not repeat |
846 | This section describes each watcher in detail, but will not repeat |
693 | information given in the last section. |
847 | information given in the last section. Any initialisation/set macros, |
|
|
848 | functions and members specific to the watcher type are explained. |
694 | |
849 | |
|
|
850 | Members are additionally marked with either I<[read-only]>, meaning that, |
|
|
851 | while the watcher is active, you can look at the member and expect some |
|
|
852 | sensible content, but you must not modify it (you can modify it while the |
|
|
853 | watcher is stopped to your hearts content), or I<[read-write]>, which |
|
|
854 | means you can expect it to have some sensible content while the watcher |
|
|
855 | is active, but you can also modify it. Modifying it may not do something |
|
|
856 | sensible or take immediate effect (or do anything at all), but libev will |
|
|
857 | not crash or malfunction in any way. |
695 | |
858 | |
|
|
859 | |
696 | =head2 C<ev_io> - is this file descriptor readable or writable |
860 | =head2 C<ev_io> - is this file descriptor readable or writable? |
697 | |
861 | |
698 | I/O watchers check whether a file descriptor is readable or writable |
862 | I/O watchers check whether a file descriptor is readable or writable |
699 | in each iteration of the event loop (This behaviour is called |
863 | in each iteration of the event loop, or, more precisely, when reading |
700 | level-triggering because you keep receiving events as long as the |
864 | would not block the process and writing would at least be able to write |
701 | condition persists. Remember you can stop the watcher if you don't want to |
865 | some data. This behaviour is called level-triggering because you keep |
702 | act on the event and neither want to receive future events). |
866 | receiving events as long as the condition persists. Remember you can stop |
|
|
867 | the watcher if you don't want to act on the event and neither want to |
|
|
868 | receive future events. |
703 | |
869 | |
704 | In general you can register as many read and/or write event watchers per |
870 | In general you can register as many read and/or write event watchers per |
705 | fd as you want (as long as you don't confuse yourself). Setting all file |
871 | fd as you want (as long as you don't confuse yourself). Setting all file |
706 | descriptors to non-blocking mode is also usually a good idea (but not |
872 | descriptors to non-blocking mode is also usually a good idea (but not |
707 | required if you know what you are doing). |
873 | required if you know what you are doing). |
708 | |
874 | |
709 | You have to be careful with dup'ed file descriptors, though. Some backends |
875 | You have to be careful with dup'ed file descriptors, though. Some backends |
710 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
876 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
711 | descriptors correctly if you register interest in two or more fds pointing |
877 | descriptors correctly if you register interest in two or more fds pointing |
712 | to the same underlying file/socket etc. description (that is, they share |
878 | to the same underlying file/socket/etc. description (that is, they share |
713 | the same underlying "file open"). |
879 | the same underlying "file open"). |
714 | |
880 | |
715 | If you must do this, then force the use of a known-to-be-good backend |
881 | If you must do this, then force the use of a known-to-be-good backend |
716 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
882 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
717 | C<EVBACKEND_POLL>). |
883 | C<EVBACKEND_POLL>). |
718 | |
884 | |
|
|
885 | Another thing you have to watch out for is that it is quite easy to |
|
|
886 | receive "spurious" readyness notifications, that is your callback might |
|
|
887 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
|
|
888 | because there is no data. Not only are some backends known to create a |
|
|
889 | lot of those (for example solaris ports), it is very easy to get into |
|
|
890 | this situation even with a relatively standard program structure. Thus |
|
|
891 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
|
|
892 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
|
|
893 | |
|
|
894 | If you cannot run the fd in non-blocking mode (for example you should not |
|
|
895 | play around with an Xlib connection), then you have to seperately re-test |
|
|
896 | whether a file descriptor is really ready with a known-to-be good interface |
|
|
897 | such as poll (fortunately in our Xlib example, Xlib already does this on |
|
|
898 | its own, so its quite safe to use). |
|
|
899 | |
719 | =over 4 |
900 | =over 4 |
720 | |
901 | |
721 | =item ev_io_init (ev_io *, callback, int fd, int events) |
902 | =item ev_io_init (ev_io *, callback, int fd, int events) |
722 | |
903 | |
723 | =item ev_io_set (ev_io *, int fd, int events) |
904 | =item ev_io_set (ev_io *, int fd, int events) |
724 | |
905 | |
725 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
906 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
726 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
907 | rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or |
727 | EV_WRITE> to receive the given events. |
908 | C<EV_READ | EV_WRITE> to receive the given events. |
728 | |
909 | |
729 | Please note that most of the more scalable backend mechanisms (for example |
910 | =item int fd [read-only] |
730 | epoll and solaris ports) can result in spurious readyness notifications |
911 | |
731 | for file descriptors, so you practically need to use non-blocking I/O (and |
912 | The file descriptor being watched. |
732 | treat callback invocation as hint only), or retest separately with a safe |
913 | |
733 | interface before doing I/O (XLib can do this), or force the use of either |
914 | =item int events [read-only] |
734 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this |
915 | |
735 | problem. Also note that it is quite easy to have your callback invoked |
916 | The events being watched. |
736 | when the readyness condition is no longer valid even when employing |
|
|
737 | typical ways of handling events, so its a good idea to use non-blocking |
|
|
738 | I/O unconditionally. |
|
|
739 | |
917 | |
740 | =back |
918 | =back |
741 | |
919 | |
742 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
920 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
743 | readable, but only once. Since it is likely line-buffered, you could |
921 | readable, but only once. Since it is likely line-buffered, you could |
744 | attempt to read a whole line in the callback: |
922 | attempt to read a whole line in the callback. |
745 | |
923 | |
746 | static void |
924 | static void |
747 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
925 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
748 | { |
926 | { |
749 | ev_io_stop (loop, w); |
927 | ev_io_stop (loop, w); |
… | |
… | |
756 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
934 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
757 | ev_io_start (loop, &stdin_readable); |
935 | ev_io_start (loop, &stdin_readable); |
758 | ev_loop (loop, 0); |
936 | ev_loop (loop, 0); |
759 | |
937 | |
760 | |
938 | |
761 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
939 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
762 | |
940 | |
763 | Timer watchers are simple relative timers that generate an event after a |
941 | Timer watchers are simple relative timers that generate an event after a |
764 | given time, and optionally repeating in regular intervals after that. |
942 | given time, and optionally repeating in regular intervals after that. |
765 | |
943 | |
766 | The timers are based on real time, that is, if you register an event that |
944 | The timers are based on real time, that is, if you register an event that |
… | |
… | |
801 | =item ev_timer_again (loop) |
979 | =item ev_timer_again (loop) |
802 | |
980 | |
803 | This will act as if the timer timed out and restart it again if it is |
981 | This will act as if the timer timed out and restart it again if it is |
804 | repeating. The exact semantics are: |
982 | repeating. The exact semantics are: |
805 | |
983 | |
|
|
984 | If the timer is pending, its pending status is cleared. |
|
|
985 | |
806 | If the timer is started but nonrepeating, stop it. |
986 | If the timer is started but nonrepeating, stop it (as if it timed out). |
807 | |
987 | |
808 | If the timer is repeating, either start it if necessary (with the repeat |
988 | If the timer is repeating, either start it if necessary (with the |
809 | value), or reset the running timer to the repeat value. |
989 | C<repeat> value), or reset the running timer to the C<repeat> value. |
810 | |
990 | |
811 | This sounds a bit complicated, but here is a useful and typical |
991 | This sounds a bit complicated, but here is a useful and typical |
812 | example: Imagine you have a tcp connection and you want a so-called idle |
992 | example: Imagine you have a tcp connection and you want a so-called idle |
813 | timeout, that is, you want to be called when there have been, say, 60 |
993 | timeout, that is, you want to be called when there have been, say, 60 |
814 | seconds of inactivity on the socket. The easiest way to do this is to |
994 | seconds of inactivity on the socket. The easiest way to do this is to |
815 | configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each |
995 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
816 | time you successfully read or write some data. If you go into an idle |
996 | C<ev_timer_again> each time you successfully read or write some data. If |
817 | state where you do not expect data to travel on the socket, you can stop |
997 | you go into an idle state where you do not expect data to travel on the |
818 | the timer, and again will automatically restart it if need be. |
998 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
|
|
999 | automatically restart it if need be. |
|
|
1000 | |
|
|
1001 | That means you can ignore the C<after> value and C<ev_timer_start> |
|
|
1002 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
|
|
1003 | |
|
|
1004 | ev_timer_init (timer, callback, 0., 5.); |
|
|
1005 | ev_timer_again (loop, timer); |
|
|
1006 | ... |
|
|
1007 | timer->again = 17.; |
|
|
1008 | ev_timer_again (loop, timer); |
|
|
1009 | ... |
|
|
1010 | timer->again = 10.; |
|
|
1011 | ev_timer_again (loop, timer); |
|
|
1012 | |
|
|
1013 | This is more slightly efficient then stopping/starting the timer each time |
|
|
1014 | you want to modify its timeout value. |
|
|
1015 | |
|
|
1016 | =item ev_tstamp repeat [read-write] |
|
|
1017 | |
|
|
1018 | The current C<repeat> value. Will be used each time the watcher times out |
|
|
1019 | or C<ev_timer_again> is called and determines the next timeout (if any), |
|
|
1020 | which is also when any modifications are taken into account. |
819 | |
1021 | |
820 | =back |
1022 | =back |
821 | |
1023 | |
822 | Example: create a timer that fires after 60 seconds. |
1024 | Example: Create a timer that fires after 60 seconds. |
823 | |
1025 | |
824 | static void |
1026 | static void |
825 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1027 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
826 | { |
1028 | { |
827 | .. one minute over, w is actually stopped right here |
1029 | .. one minute over, w is actually stopped right here |
… | |
… | |
829 | |
1031 | |
830 | struct ev_timer mytimer; |
1032 | struct ev_timer mytimer; |
831 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1033 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
832 | ev_timer_start (loop, &mytimer); |
1034 | ev_timer_start (loop, &mytimer); |
833 | |
1035 | |
834 | Example: create a timeout timer that times out after 10 seconds of |
1036 | Example: Create a timeout timer that times out after 10 seconds of |
835 | inactivity. |
1037 | inactivity. |
836 | |
1038 | |
837 | static void |
1039 | static void |
838 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1040 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
839 | { |
1041 | { |
… | |
… | |
848 | // and in some piece of code that gets executed on any "activity": |
1050 | // and in some piece of code that gets executed on any "activity": |
849 | // reset the timeout to start ticking again at 10 seconds |
1051 | // reset the timeout to start ticking again at 10 seconds |
850 | ev_timer_again (&mytimer); |
1052 | ev_timer_again (&mytimer); |
851 | |
1053 | |
852 | |
1054 | |
853 | =head2 C<ev_periodic> - to cron or not to cron |
1055 | =head2 C<ev_periodic> - to cron or not to cron? |
854 | |
1056 | |
855 | Periodic watchers are also timers of a kind, but they are very versatile |
1057 | Periodic watchers are also timers of a kind, but they are very versatile |
856 | (and unfortunately a bit complex). |
1058 | (and unfortunately a bit complex). |
857 | |
1059 | |
858 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
1060 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
… | |
… | |
950 | Simply stops and restarts the periodic watcher again. This is only useful |
1152 | Simply stops and restarts the periodic watcher again. This is only useful |
951 | when you changed some parameters or the reschedule callback would return |
1153 | when you changed some parameters or the reschedule callback would return |
952 | a different time than the last time it was called (e.g. in a crond like |
1154 | a different time than the last time it was called (e.g. in a crond like |
953 | program when the crontabs have changed). |
1155 | program when the crontabs have changed). |
954 | |
1156 | |
|
|
1157 | =item ev_tstamp interval [read-write] |
|
|
1158 | |
|
|
1159 | The current interval value. Can be modified any time, but changes only |
|
|
1160 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
|
|
1161 | called. |
|
|
1162 | |
|
|
1163 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
|
|
1164 | |
|
|
1165 | The current reschedule callback, or C<0>, if this functionality is |
|
|
1166 | switched off. Can be changed any time, but changes only take effect when |
|
|
1167 | the periodic timer fires or C<ev_periodic_again> is being called. |
|
|
1168 | |
955 | =back |
1169 | =back |
956 | |
1170 | |
957 | Example: call a callback every hour, or, more precisely, whenever the |
1171 | Example: Call a callback every hour, or, more precisely, whenever the |
958 | system clock is divisible by 3600. The callback invocation times have |
1172 | system clock is divisible by 3600. The callback invocation times have |
959 | potentially a lot of jittering, but good long-term stability. |
1173 | potentially a lot of jittering, but good long-term stability. |
960 | |
1174 | |
961 | static void |
1175 | static void |
962 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1176 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
… | |
… | |
966 | |
1180 | |
967 | struct ev_periodic hourly_tick; |
1181 | struct ev_periodic hourly_tick; |
968 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1182 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
969 | ev_periodic_start (loop, &hourly_tick); |
1183 | ev_periodic_start (loop, &hourly_tick); |
970 | |
1184 | |
971 | Example: the same as above, but use a reschedule callback to do it: |
1185 | Example: The same as above, but use a reschedule callback to do it: |
972 | |
1186 | |
973 | #include <math.h> |
1187 | #include <math.h> |
974 | |
1188 | |
975 | static ev_tstamp |
1189 | static ev_tstamp |
976 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1190 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
978 | return fmod (now, 3600.) + 3600.; |
1192 | return fmod (now, 3600.) + 3600.; |
979 | } |
1193 | } |
980 | |
1194 | |
981 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1195 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
982 | |
1196 | |
983 | Example: call a callback every hour, starting now: |
1197 | Example: Call a callback every hour, starting now: |
984 | |
1198 | |
985 | struct ev_periodic hourly_tick; |
1199 | struct ev_periodic hourly_tick; |
986 | ev_periodic_init (&hourly_tick, clock_cb, |
1200 | ev_periodic_init (&hourly_tick, clock_cb, |
987 | fmod (ev_now (loop), 3600.), 3600., 0); |
1201 | fmod (ev_now (loop), 3600.), 3600., 0); |
988 | ev_periodic_start (loop, &hourly_tick); |
1202 | ev_periodic_start (loop, &hourly_tick); |
989 | |
1203 | |
990 | |
1204 | |
991 | =head2 C<ev_signal> - signal me when a signal gets signalled |
1205 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
992 | |
1206 | |
993 | Signal watchers will trigger an event when the process receives a specific |
1207 | Signal watchers will trigger an event when the process receives a specific |
994 | signal one or more times. Even though signals are very asynchronous, libev |
1208 | signal one or more times. Even though signals are very asynchronous, libev |
995 | will try it's best to deliver signals synchronously, i.e. as part of the |
1209 | will try it's best to deliver signals synchronously, i.e. as part of the |
996 | normal event processing, like any other event. |
1210 | normal event processing, like any other event. |
… | |
… | |
1009 | =item ev_signal_set (ev_signal *, int signum) |
1223 | =item ev_signal_set (ev_signal *, int signum) |
1010 | |
1224 | |
1011 | Configures the watcher to trigger on the given signal number (usually one |
1225 | Configures the watcher to trigger on the given signal number (usually one |
1012 | of the C<SIGxxx> constants). |
1226 | of the C<SIGxxx> constants). |
1013 | |
1227 | |
|
|
1228 | =item int signum [read-only] |
|
|
1229 | |
|
|
1230 | The signal the watcher watches out for. |
|
|
1231 | |
1014 | =back |
1232 | =back |
1015 | |
1233 | |
1016 | |
1234 | |
1017 | =head2 C<ev_child> - wait for pid status changes |
1235 | =head2 C<ev_child> - watch out for process status changes |
1018 | |
1236 | |
1019 | Child watchers trigger when your process receives a SIGCHLD in response to |
1237 | Child watchers trigger when your process receives a SIGCHLD in response to |
1020 | some child status changes (most typically when a child of yours dies). |
1238 | some child status changes (most typically when a child of yours dies). |
1021 | |
1239 | |
1022 | =over 4 |
1240 | =over 4 |
… | |
… | |
1030 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1248 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1031 | the status word (use the macros from C<sys/wait.h> and see your systems |
1249 | the status word (use the macros from C<sys/wait.h> and see your systems |
1032 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1250 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1033 | process causing the status change. |
1251 | process causing the status change. |
1034 | |
1252 | |
|
|
1253 | =item int pid [read-only] |
|
|
1254 | |
|
|
1255 | The process id this watcher watches out for, or C<0>, meaning any process id. |
|
|
1256 | |
|
|
1257 | =item int rpid [read-write] |
|
|
1258 | |
|
|
1259 | The process id that detected a status change. |
|
|
1260 | |
|
|
1261 | =item int rstatus [read-write] |
|
|
1262 | |
|
|
1263 | The process exit/trace status caused by C<rpid> (see your systems |
|
|
1264 | C<waitpid> and C<sys/wait.h> documentation for details). |
|
|
1265 | |
1035 | =back |
1266 | =back |
1036 | |
1267 | |
1037 | Example: try to exit cleanly on SIGINT and SIGTERM. |
1268 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1038 | |
1269 | |
1039 | static void |
1270 | static void |
1040 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1271 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1041 | { |
1272 | { |
1042 | ev_unloop (loop, EVUNLOOP_ALL); |
1273 | ev_unloop (loop, EVUNLOOP_ALL); |
… | |
… | |
1045 | struct ev_signal signal_watcher; |
1276 | struct ev_signal signal_watcher; |
1046 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1277 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1047 | ev_signal_start (loop, &sigint_cb); |
1278 | ev_signal_start (loop, &sigint_cb); |
1048 | |
1279 | |
1049 | |
1280 | |
|
|
1281 | =head2 C<ev_stat> - did the file attributes just change? |
|
|
1282 | |
|
|
1283 | This watches a filesystem path for attribute changes. That is, it calls |
|
|
1284 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
|
|
1285 | compared to the last time, invoking the callback if it did. |
|
|
1286 | |
|
|
1287 | The path does not need to exist: changing from "path exists" to "path does |
|
|
1288 | not exist" is a status change like any other. The condition "path does |
|
|
1289 | not exist" is signified by the C<st_nlink> field being zero (which is |
|
|
1290 | otherwise always forced to be at least one) and all the other fields of |
|
|
1291 | the stat buffer having unspecified contents. |
|
|
1292 | |
|
|
1293 | The path I<should> be absolute and I<must not> end in a slash. If it is |
|
|
1294 | relative and your working directory changes, the behaviour is undefined. |
|
|
1295 | |
|
|
1296 | Since there is no standard to do this, the portable implementation simply |
|
|
1297 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
|
|
1298 | can specify a recommended polling interval for this case. If you specify |
|
|
1299 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
|
|
1300 | unspecified default> value will be used (which you can expect to be around |
|
|
1301 | five seconds, although this might change dynamically). Libev will also |
|
|
1302 | impose a minimum interval which is currently around C<0.1>, but thats |
|
|
1303 | usually overkill. |
|
|
1304 | |
|
|
1305 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
1306 | as even with OS-supported change notifications, this can be |
|
|
1307 | resource-intensive. |
|
|
1308 | |
|
|
1309 | At the time of this writing, only the Linux inotify interface is |
|
|
1310 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1311 | reader). Inotify will be used to give hints only and should not change the |
|
|
1312 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
|
|
1313 | to fall back to regular polling again even with inotify, but changes are |
|
|
1314 | usually detected immediately, and if the file exists there will be no |
|
|
1315 | polling. |
|
|
1316 | |
|
|
1317 | =over 4 |
|
|
1318 | |
|
|
1319 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
|
|
1320 | |
|
|
1321 | =item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval) |
|
|
1322 | |
|
|
1323 | Configures the watcher to wait for status changes of the given |
|
|
1324 | C<path>. The C<interval> is a hint on how quickly a change is expected to |
|
|
1325 | be detected and should normally be specified as C<0> to let libev choose |
|
|
1326 | a suitable value. The memory pointed to by C<path> must point to the same |
|
|
1327 | path for as long as the watcher is active. |
|
|
1328 | |
|
|
1329 | The callback will be receive C<EV_STAT> when a change was detected, |
|
|
1330 | relative to the attributes at the time the watcher was started (or the |
|
|
1331 | last change was detected). |
|
|
1332 | |
|
|
1333 | =item ev_stat_stat (ev_stat *) |
|
|
1334 | |
|
|
1335 | Updates the stat buffer immediately with new values. If you change the |
|
|
1336 | watched path in your callback, you could call this fucntion to avoid |
|
|
1337 | detecting this change (while introducing a race condition). Can also be |
|
|
1338 | useful simply to find out the new values. |
|
|
1339 | |
|
|
1340 | =item ev_statdata attr [read-only] |
|
|
1341 | |
|
|
1342 | The most-recently detected attributes of the file. Although the type is of |
|
|
1343 | C<ev_statdata>, this is usually the (or one of the) C<struct stat> types |
|
|
1344 | suitable for your system. If the C<st_nlink> member is C<0>, then there |
|
|
1345 | was some error while C<stat>ing the file. |
|
|
1346 | |
|
|
1347 | =item ev_statdata prev [read-only] |
|
|
1348 | |
|
|
1349 | The previous attributes of the file. The callback gets invoked whenever |
|
|
1350 | C<prev> != C<attr>. |
|
|
1351 | |
|
|
1352 | =item ev_tstamp interval [read-only] |
|
|
1353 | |
|
|
1354 | The specified interval. |
|
|
1355 | |
|
|
1356 | =item const char *path [read-only] |
|
|
1357 | |
|
|
1358 | The filesystem path that is being watched. |
|
|
1359 | |
|
|
1360 | =back |
|
|
1361 | |
|
|
1362 | Example: Watch C</etc/passwd> for attribute changes. |
|
|
1363 | |
|
|
1364 | static void |
|
|
1365 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1366 | { |
|
|
1367 | /* /etc/passwd changed in some way */ |
|
|
1368 | if (w->attr.st_nlink) |
|
|
1369 | { |
|
|
1370 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
|
|
1371 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
|
|
1372 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
|
|
1373 | } |
|
|
1374 | else |
|
|
1375 | /* you shalt not abuse printf for puts */ |
|
|
1376 | puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1377 | "if this is windows, they already arrived\n"); |
|
|
1378 | } |
|
|
1379 | |
|
|
1380 | ... |
|
|
1381 | ev_stat passwd; |
|
|
1382 | |
|
|
1383 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
|
|
1384 | ev_stat_start (loop, &passwd); |
|
|
1385 | |
|
|
1386 | |
1050 | =head2 C<ev_idle> - when you've got nothing better to do |
1387 | =head2 C<ev_idle> - when you've got nothing better to do... |
1051 | |
1388 | |
1052 | Idle watchers trigger events when there are no other events are pending |
1389 | Idle watchers trigger events when no other events of the same or higher |
1053 | (prepare, check and other idle watchers do not count). That is, as long |
1390 | priority are pending (prepare, check and other idle watchers do not |
1054 | as your process is busy handling sockets or timeouts (or even signals, |
1391 | count). |
1055 | imagine) it will not be triggered. But when your process is idle all idle |
1392 | |
1056 | watchers are being called again and again, once per event loop iteration - |
1393 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1394 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1395 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1396 | are pending), the idle watchers are being called once per event loop |
1057 | until stopped, that is, or your process receives more events and becomes |
1397 | iteration - until stopped, that is, or your process receives more events |
1058 | busy. |
1398 | and becomes busy again with higher priority stuff. |
1059 | |
1399 | |
1060 | The most noteworthy effect is that as long as any idle watchers are |
1400 | The most noteworthy effect is that as long as any idle watchers are |
1061 | active, the process will not block when waiting for new events. |
1401 | active, the process will not block when waiting for new events. |
1062 | |
1402 | |
1063 | Apart from keeping your process non-blocking (which is a useful |
1403 | Apart from keeping your process non-blocking (which is a useful |
… | |
… | |
1073 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1413 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1074 | believe me. |
1414 | believe me. |
1075 | |
1415 | |
1076 | =back |
1416 | =back |
1077 | |
1417 | |
1078 | Example: dynamically allocate an C<ev_idle>, start it, and in the |
1418 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1079 | callback, free it. Alos, use no error checking, as usual. |
1419 | callback, free it. Also, use no error checking, as usual. |
1080 | |
1420 | |
1081 | static void |
1421 | static void |
1082 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1422 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1083 | { |
1423 | { |
1084 | free (w); |
1424 | free (w); |
… | |
… | |
1089 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1429 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1090 | ev_idle_init (idle_watcher, idle_cb); |
1430 | ev_idle_init (idle_watcher, idle_cb); |
1091 | ev_idle_start (loop, idle_cb); |
1431 | ev_idle_start (loop, idle_cb); |
1092 | |
1432 | |
1093 | |
1433 | |
1094 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
1434 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
1095 | |
1435 | |
1096 | Prepare and check watchers are usually (but not always) used in tandem: |
1436 | Prepare and check watchers are usually (but not always) used in tandem: |
1097 | prepare watchers get invoked before the process blocks and check watchers |
1437 | prepare watchers get invoked before the process blocks and check watchers |
1098 | afterwards. |
1438 | afterwards. |
1099 | |
1439 | |
|
|
1440 | You I<must not> call C<ev_loop> or similar functions that enter |
|
|
1441 | the current event loop from either C<ev_prepare> or C<ev_check> |
|
|
1442 | watchers. Other loops than the current one are fine, however. The |
|
|
1443 | rationale behind this is that you do not need to check for recursion in |
|
|
1444 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
|
|
1445 | C<ev_check> so if you have one watcher of each kind they will always be |
|
|
1446 | called in pairs bracketing the blocking call. |
|
|
1447 | |
1100 | Their main purpose is to integrate other event mechanisms into libev and |
1448 | Their main purpose is to integrate other event mechanisms into libev and |
1101 | their use is somewhat advanced. This could be used, for example, to track |
1449 | their use is somewhat advanced. This could be used, for example, to track |
1102 | variable changes, implement your own watchers, integrate net-snmp or a |
1450 | variable changes, implement your own watchers, integrate net-snmp or a |
1103 | coroutine library and lots more. |
1451 | coroutine library and lots more. They are also occasionally useful if |
|
|
1452 | you cache some data and want to flush it before blocking (for example, |
|
|
1453 | in X programs you might want to do an C<XFlush ()> in an C<ev_prepare> |
|
|
1454 | watcher). |
1104 | |
1455 | |
1105 | This is done by examining in each prepare call which file descriptors need |
1456 | This is done by examining in each prepare call which file descriptors need |
1106 | to be watched by the other library, registering C<ev_io> watchers for |
1457 | to be watched by the other library, registering C<ev_io> watchers for |
1107 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1458 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1108 | provide just this functionality). Then, in the check watcher you check for |
1459 | provide just this functionality). Then, in the check watcher you check for |
… | |
… | |
1130 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1481 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1131 | macros, but using them is utterly, utterly and completely pointless. |
1482 | macros, but using them is utterly, utterly and completely pointless. |
1132 | |
1483 | |
1133 | =back |
1484 | =back |
1134 | |
1485 | |
1135 | Example: *TODO*. |
1486 | Example: To include a library such as adns, you would add IO watchers |
|
|
1487 | and a timeout watcher in a prepare handler, as required by libadns, and |
|
|
1488 | in a check watcher, destroy them and call into libadns. What follows is |
|
|
1489 | pseudo-code only of course: |
1136 | |
1490 | |
|
|
1491 | static ev_io iow [nfd]; |
|
|
1492 | static ev_timer tw; |
1137 | |
1493 | |
|
|
1494 | static void |
|
|
1495 | io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1496 | { |
|
|
1497 | // set the relevant poll flags |
|
|
1498 | // could also call adns_processreadable etc. here |
|
|
1499 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1500 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1501 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1502 | } |
|
|
1503 | |
|
|
1504 | // create io watchers for each fd and a timer before blocking |
|
|
1505 | static void |
|
|
1506 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1507 | { |
|
|
1508 | int timeout = 3600000; |
|
|
1509 | struct pollfd fds [nfd]; |
|
|
1510 | // actual code will need to loop here and realloc etc. |
|
|
1511 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
|
|
1512 | |
|
|
1513 | /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1514 | ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1515 | ev_timer_start (loop, &tw); |
|
|
1516 | |
|
|
1517 | // create on ev_io per pollfd |
|
|
1518 | for (int i = 0; i < nfd; ++i) |
|
|
1519 | { |
|
|
1520 | ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1521 | ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1522 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
1523 | |
|
|
1524 | fds [i].revents = 0; |
|
|
1525 | iow [i].data = fds + i; |
|
|
1526 | ev_io_start (loop, iow + i); |
|
|
1527 | } |
|
|
1528 | } |
|
|
1529 | |
|
|
1530 | // stop all watchers after blocking |
|
|
1531 | static void |
|
|
1532 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1533 | { |
|
|
1534 | ev_timer_stop (loop, &tw); |
|
|
1535 | |
|
|
1536 | for (int i = 0; i < nfd; ++i) |
|
|
1537 | ev_io_stop (loop, iow + i); |
|
|
1538 | |
|
|
1539 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1540 | } |
|
|
1541 | |
|
|
1542 | |
1138 | =head2 C<ev_embed> - when one backend isn't enough |
1543 | =head2 C<ev_embed> - when one backend isn't enough... |
1139 | |
1544 | |
1140 | This is a rather advanced watcher type that lets you embed one event loop |
1545 | This is a rather advanced watcher type that lets you embed one event loop |
1141 | into another (currently only C<ev_io> events are supported in the embedded |
1546 | into another (currently only C<ev_io> events are supported in the embedded |
1142 | loop, other types of watchers might be handled in a delayed or incorrect |
1547 | loop, other types of watchers might be handled in a delayed or incorrect |
1143 | fashion and must not be used). |
1548 | fashion and must not be used). |
… | |
… | |
1221 | |
1626 | |
1222 | Make a single, non-blocking sweep over the embedded loop. This works |
1627 | Make a single, non-blocking sweep over the embedded loop. This works |
1223 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1628 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1224 | apropriate way for embedded loops. |
1629 | apropriate way for embedded loops. |
1225 | |
1630 | |
|
|
1631 | =item struct ev_loop *loop [read-only] |
|
|
1632 | |
|
|
1633 | The embedded event loop. |
|
|
1634 | |
|
|
1635 | =back |
|
|
1636 | |
|
|
1637 | |
|
|
1638 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
|
|
1639 | |
|
|
1640 | Fork watchers are called when a C<fork ()> was detected (usually because |
|
|
1641 | whoever is a good citizen cared to tell libev about it by calling |
|
|
1642 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
|
|
1643 | event loop blocks next and before C<ev_check> watchers are being called, |
|
|
1644 | and only in the child after the fork. If whoever good citizen calling |
|
|
1645 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
|
|
1646 | handlers will be invoked, too, of course. |
|
|
1647 | |
|
|
1648 | =over 4 |
|
|
1649 | |
|
|
1650 | =item ev_fork_init (ev_signal *, callback) |
|
|
1651 | |
|
|
1652 | Initialises and configures the fork watcher - it has no parameters of any |
|
|
1653 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
|
|
1654 | believe me. |
|
|
1655 | |
1226 | =back |
1656 | =back |
1227 | |
1657 | |
1228 | |
1658 | |
1229 | =head1 OTHER FUNCTIONS |
1659 | =head1 OTHER FUNCTIONS |
1230 | |
1660 | |
… | |
… | |
1318 | |
1748 | |
1319 | To use it, |
1749 | To use it, |
1320 | |
1750 | |
1321 | #include <ev++.h> |
1751 | #include <ev++.h> |
1322 | |
1752 | |
1323 | (it is not installed by default). This automatically includes F<ev.h> |
1753 | This automatically includes F<ev.h> and puts all of its definitions (many |
1324 | and puts all of its definitions (many of them macros) into the global |
1754 | of them macros) into the global namespace. All C++ specific things are |
1325 | namespace. All C++ specific things are put into the C<ev> namespace. |
1755 | put into the C<ev> namespace. It should support all the same embedding |
|
|
1756 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1326 | |
1757 | |
1327 | It should support all the same embedding options as F<ev.h>, most notably |
1758 | Care has been taken to keep the overhead low. The only data member the C++ |
1328 | C<EV_MULTIPLICITY>. |
1759 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
1760 | that the watcher is associated with (or no additional members at all if |
|
|
1761 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
1762 | |
|
|
1763 | Currently, functions, and static and non-static member functions can be |
|
|
1764 | used as callbacks. Other types should be easy to add as long as they only |
|
|
1765 | need one additional pointer for context. If you need support for other |
|
|
1766 | types of functors please contact the author (preferably after implementing |
|
|
1767 | it). |
1329 | |
1768 | |
1330 | Here is a list of things available in the C<ev> namespace: |
1769 | Here is a list of things available in the C<ev> namespace: |
1331 | |
1770 | |
1332 | =over 4 |
1771 | =over 4 |
1333 | |
1772 | |
… | |
… | |
1349 | |
1788 | |
1350 | All of those classes have these methods: |
1789 | All of those classes have these methods: |
1351 | |
1790 | |
1352 | =over 4 |
1791 | =over 4 |
1353 | |
1792 | |
1354 | =item ev::TYPE::TYPE (object *, object::method *) |
1793 | =item ev::TYPE::TYPE () |
1355 | |
1794 | |
1356 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
1795 | =item ev::TYPE::TYPE (struct ev_loop *) |
1357 | |
1796 | |
1358 | =item ev::TYPE::~TYPE |
1797 | =item ev::TYPE::~TYPE |
1359 | |
1798 | |
1360 | The constructor takes a pointer to an object and a method pointer to |
1799 | The constructor (optionally) takes an event loop to associate the watcher |
1361 | the event handler callback to call in this class. The constructor calls |
1800 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1362 | C<ev_init> for you, which means you have to call the C<set> method |
1801 | |
1363 | before starting it. If you do not specify a loop then the constructor |
1802 | The constructor calls C<ev_init> for you, which means you have to call the |
1364 | automatically associates the default loop with this watcher. |
1803 | C<set> method before starting it. |
|
|
1804 | |
|
|
1805 | It will not set a callback, however: You have to call the templated C<set> |
|
|
1806 | method to set a callback before you can start the watcher. |
|
|
1807 | |
|
|
1808 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
1809 | not allow explicit template arguments for constructors). |
1365 | |
1810 | |
1366 | The destructor automatically stops the watcher if it is active. |
1811 | The destructor automatically stops the watcher if it is active. |
|
|
1812 | |
|
|
1813 | =item w->set<class, &class::method> (object *) |
|
|
1814 | |
|
|
1815 | This method sets the callback method to call. The method has to have a |
|
|
1816 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
1817 | first argument and the C<revents> as second. The object must be given as |
|
|
1818 | parameter and is stored in the C<data> member of the watcher. |
|
|
1819 | |
|
|
1820 | This method synthesizes efficient thunking code to call your method from |
|
|
1821 | the C callback that libev requires. If your compiler can inline your |
|
|
1822 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
1823 | your compiler is good :), then the method will be fully inlined into the |
|
|
1824 | thunking function, making it as fast as a direct C callback. |
|
|
1825 | |
|
|
1826 | Example: simple class declaration and watcher initialisation |
|
|
1827 | |
|
|
1828 | struct myclass |
|
|
1829 | { |
|
|
1830 | void io_cb (ev::io &w, int revents) { } |
|
|
1831 | } |
|
|
1832 | |
|
|
1833 | myclass obj; |
|
|
1834 | ev::io iow; |
|
|
1835 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
1836 | |
|
|
1837 | =item w->set (void (*function)(watcher &w, int), void *data = 0) |
|
|
1838 | |
|
|
1839 | Also sets a callback, but uses a static method or plain function as |
|
|
1840 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
1841 | C<data> member and is free for you to use. |
|
|
1842 | |
|
|
1843 | See the method-C<set> above for more details. |
1367 | |
1844 | |
1368 | =item w->set (struct ev_loop *) |
1845 | =item w->set (struct ev_loop *) |
1369 | |
1846 | |
1370 | Associates a different C<struct ev_loop> with this watcher. You can only |
1847 | Associates a different C<struct ev_loop> with this watcher. You can only |
1371 | do this when the watcher is inactive (and not pending either). |
1848 | do this when the watcher is inactive (and not pending either). |
1372 | |
1849 | |
1373 | =item w->set ([args]) |
1850 | =item w->set ([args]) |
1374 | |
1851 | |
1375 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1852 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1376 | called at least once. Unlike the C counterpart, an active watcher gets |
1853 | called at least once. Unlike the C counterpart, an active watcher gets |
1377 | automatically stopped and restarted. |
1854 | automatically stopped and restarted when reconfiguring it with this |
|
|
1855 | method. |
1378 | |
1856 | |
1379 | =item w->start () |
1857 | =item w->start () |
1380 | |
1858 | |
1381 | Starts the watcher. Note that there is no C<loop> argument as the |
1859 | Starts the watcher. Note that there is no C<loop> argument, as the |
1382 | constructor already takes the loop. |
1860 | constructor already stores the event loop. |
1383 | |
1861 | |
1384 | =item w->stop () |
1862 | =item w->stop () |
1385 | |
1863 | |
1386 | Stops the watcher if it is active. Again, no C<loop> argument. |
1864 | Stops the watcher if it is active. Again, no C<loop> argument. |
1387 | |
1865 | |
… | |
… | |
1392 | |
1870 | |
1393 | =item w->sweep () C<ev::embed> only |
1871 | =item w->sweep () C<ev::embed> only |
1394 | |
1872 | |
1395 | Invokes C<ev_embed_sweep>. |
1873 | Invokes C<ev_embed_sweep>. |
1396 | |
1874 | |
|
|
1875 | =item w->update () C<ev::stat> only |
|
|
1876 | |
|
|
1877 | Invokes C<ev_stat_stat>. |
|
|
1878 | |
1397 | =back |
1879 | =back |
1398 | |
1880 | |
1399 | =back |
1881 | =back |
1400 | |
1882 | |
1401 | Example: Define a class with an IO and idle watcher, start one of them in |
1883 | Example: Define a class with an IO and idle watcher, start one of them in |
… | |
… | |
1408 | |
1890 | |
1409 | myclass (); |
1891 | myclass (); |
1410 | } |
1892 | } |
1411 | |
1893 | |
1412 | myclass::myclass (int fd) |
1894 | myclass::myclass (int fd) |
1413 | : io (this, &myclass::io_cb), |
|
|
1414 | idle (this, &myclass::idle_cb) |
|
|
1415 | { |
1895 | { |
|
|
1896 | io .set <myclass, &myclass::io_cb > (this); |
|
|
1897 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
1898 | |
1416 | io.start (fd, ev::READ); |
1899 | io.start (fd, ev::READ); |
1417 | } |
1900 | } |
|
|
1901 | |
|
|
1902 | |
|
|
1903 | =head1 MACRO MAGIC |
|
|
1904 | |
|
|
1905 | Libev can be compiled with a variety of options, the most fundemantal is |
|
|
1906 | C<EV_MULTIPLICITY>. This option determines whether (most) functions and |
|
|
1907 | callbacks have an initial C<struct ev_loop *> argument. |
|
|
1908 | |
|
|
1909 | To make it easier to write programs that cope with either variant, the |
|
|
1910 | following macros are defined: |
|
|
1911 | |
|
|
1912 | =over 4 |
|
|
1913 | |
|
|
1914 | =item C<EV_A>, C<EV_A_> |
|
|
1915 | |
|
|
1916 | This provides the loop I<argument> for functions, if one is required ("ev |
|
|
1917 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
|
|
1918 | C<EV_A_> is used when other arguments are following. Example: |
|
|
1919 | |
|
|
1920 | ev_unref (EV_A); |
|
|
1921 | ev_timer_add (EV_A_ watcher); |
|
|
1922 | ev_loop (EV_A_ 0); |
|
|
1923 | |
|
|
1924 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
|
|
1925 | which is often provided by the following macro. |
|
|
1926 | |
|
|
1927 | =item C<EV_P>, C<EV_P_> |
|
|
1928 | |
|
|
1929 | This provides the loop I<parameter> for functions, if one is required ("ev |
|
|
1930 | loop parameter"). The C<EV_P> form is used when this is the sole parameter, |
|
|
1931 | C<EV_P_> is used when other parameters are following. Example: |
|
|
1932 | |
|
|
1933 | // this is how ev_unref is being declared |
|
|
1934 | static void ev_unref (EV_P); |
|
|
1935 | |
|
|
1936 | // this is how you can declare your typical callback |
|
|
1937 | static void cb (EV_P_ ev_timer *w, int revents) |
|
|
1938 | |
|
|
1939 | It declares a parameter C<loop> of type C<struct ev_loop *>, quite |
|
|
1940 | suitable for use with C<EV_A>. |
|
|
1941 | |
|
|
1942 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
|
|
1943 | |
|
|
1944 | Similar to the other two macros, this gives you the value of the default |
|
|
1945 | loop, if multiple loops are supported ("ev loop default"). |
|
|
1946 | |
|
|
1947 | =back |
|
|
1948 | |
|
|
1949 | Example: Declare and initialise a check watcher, utilising the above |
|
|
1950 | macros so it will work regardless of whether multiple loops are supported |
|
|
1951 | or not. |
|
|
1952 | |
|
|
1953 | static void |
|
|
1954 | check_cb (EV_P_ ev_timer *w, int revents) |
|
|
1955 | { |
|
|
1956 | ev_check_stop (EV_A_ w); |
|
|
1957 | } |
|
|
1958 | |
|
|
1959 | ev_check check; |
|
|
1960 | ev_check_init (&check, check_cb); |
|
|
1961 | ev_check_start (EV_DEFAULT_ &check); |
|
|
1962 | ev_loop (EV_DEFAULT_ 0); |
1418 | |
1963 | |
1419 | =head1 EMBEDDING |
1964 | =head1 EMBEDDING |
1420 | |
1965 | |
1421 | Libev can (and often is) directly embedded into host |
1966 | Libev can (and often is) directly embedded into host |
1422 | applications. Examples of applications that embed it include the Deliantra |
1967 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
1462 | ev_vars.h |
2007 | ev_vars.h |
1463 | ev_wrap.h |
2008 | ev_wrap.h |
1464 | |
2009 | |
1465 | ev_win32.c required on win32 platforms only |
2010 | ev_win32.c required on win32 platforms only |
1466 | |
2011 | |
1467 | ev_select.c only when select backend is enabled (which is is by default) |
2012 | ev_select.c only when select backend is enabled (which is enabled by default) |
1468 | ev_poll.c only when poll backend is enabled (disabled by default) |
2013 | ev_poll.c only when poll backend is enabled (disabled by default) |
1469 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2014 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1470 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2015 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1471 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
2016 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1472 | |
2017 | |
1473 | F<ev.c> includes the backend files directly when enabled, so you only need |
2018 | F<ev.c> includes the backend files directly when enabled, so you only need |
1474 | to compile a single file. |
2019 | to compile this single file. |
1475 | |
2020 | |
1476 | =head3 LIBEVENT COMPATIBILITY API |
2021 | =head3 LIBEVENT COMPATIBILITY API |
1477 | |
2022 | |
1478 | To include the libevent compatibility API, also include: |
2023 | To include the libevent compatibility API, also include: |
1479 | |
2024 | |
… | |
… | |
1492 | |
2037 | |
1493 | =head3 AUTOCONF SUPPORT |
2038 | =head3 AUTOCONF SUPPORT |
1494 | |
2039 | |
1495 | Instead of using C<EV_STANDALONE=1> and providing your config in |
2040 | Instead of using C<EV_STANDALONE=1> and providing your config in |
1496 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
2041 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
1497 | F<configure.ac> and leave C<EV_STANDALONE> off. F<ev.c> will then include |
2042 | F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then |
1498 | F<config.h> and configure itself accordingly. |
2043 | include F<config.h> and configure itself accordingly. |
1499 | |
2044 | |
1500 | For this of course you need the m4 file: |
2045 | For this of course you need the m4 file: |
1501 | |
2046 | |
1502 | libev.m4 |
2047 | libev.m4 |
1503 | |
2048 | |
… | |
… | |
1583 | otherwise another method will be used as fallback. This is the preferred |
2128 | otherwise another method will be used as fallback. This is the preferred |
1584 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
2129 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
1585 | supports some types of fds correctly (the only platform we found that |
2130 | supports some types of fds correctly (the only platform we found that |
1586 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
2131 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
1587 | not be used unless explicitly requested. The best way to use it is to find |
2132 | not be used unless explicitly requested. The best way to use it is to find |
1588 | out wether kqueue supports your type of fd properly and use an embedded |
2133 | out whether kqueue supports your type of fd properly and use an embedded |
1589 | kqueue loop. |
2134 | kqueue loop. |
1590 | |
2135 | |
1591 | =item EV_USE_PORT |
2136 | =item EV_USE_PORT |
1592 | |
2137 | |
1593 | If defined to be C<1>, libev will compile in support for the Solaris |
2138 | If defined to be C<1>, libev will compile in support for the Solaris |
… | |
… | |
1596 | backend for Solaris 10 systems. |
2141 | backend for Solaris 10 systems. |
1597 | |
2142 | |
1598 | =item EV_USE_DEVPOLL |
2143 | =item EV_USE_DEVPOLL |
1599 | |
2144 | |
1600 | reserved for future expansion, works like the USE symbols above. |
2145 | reserved for future expansion, works like the USE symbols above. |
|
|
2146 | |
|
|
2147 | =item EV_USE_INOTIFY |
|
|
2148 | |
|
|
2149 | If defined to be C<1>, libev will compile in support for the Linux inotify |
|
|
2150 | interface to speed up C<ev_stat> watchers. Its actual availability will |
|
|
2151 | be detected at runtime. |
1601 | |
2152 | |
1602 | =item EV_H |
2153 | =item EV_H |
1603 | |
2154 | |
1604 | The name of the F<ev.h> header file used to include it. The default if |
2155 | The name of the F<ev.h> header file used to include it. The default if |
1605 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2156 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
… | |
… | |
1629 | will have the C<struct ev_loop *> as first argument, and you can create |
2180 | will have the C<struct ev_loop *> as first argument, and you can create |
1630 | additional independent event loops. Otherwise there will be no support |
2181 | additional independent event loops. Otherwise there will be no support |
1631 | for multiple event loops and there is no first event loop pointer |
2182 | for multiple event loops and there is no first event loop pointer |
1632 | argument. Instead, all functions act on the single default loop. |
2183 | argument. Instead, all functions act on the single default loop. |
1633 | |
2184 | |
|
|
2185 | =item EV_MINPRI |
|
|
2186 | |
|
|
2187 | =item EV_MAXPRI |
|
|
2188 | |
|
|
2189 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2190 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2191 | provide for more priorities by overriding those symbols (usually defined |
|
|
2192 | to be C<-2> and C<2>, respectively). |
|
|
2193 | |
|
|
2194 | When doing priority-based operations, libev usually has to linearly search |
|
|
2195 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2196 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2197 | fine. |
|
|
2198 | |
|
|
2199 | If your embedding app does not need any priorities, defining these both to |
|
|
2200 | C<0> will save some memory and cpu. |
|
|
2201 | |
1634 | =item EV_PERIODICS |
2202 | =item EV_PERIODIC_ENABLE |
1635 | |
2203 | |
1636 | If undefined or defined to be C<1>, then periodic timers are supported, |
2204 | If undefined or defined to be C<1>, then periodic timers are supported. If |
1637 | otherwise not. This saves a few kb of code. |
2205 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2206 | code. |
|
|
2207 | |
|
|
2208 | =item EV_IDLE_ENABLE |
|
|
2209 | |
|
|
2210 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
2211 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2212 | code. |
|
|
2213 | |
|
|
2214 | =item EV_EMBED_ENABLE |
|
|
2215 | |
|
|
2216 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
2217 | defined to be C<0>, then they are not. |
|
|
2218 | |
|
|
2219 | =item EV_STAT_ENABLE |
|
|
2220 | |
|
|
2221 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
2222 | defined to be C<0>, then they are not. |
|
|
2223 | |
|
|
2224 | =item EV_FORK_ENABLE |
|
|
2225 | |
|
|
2226 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
2227 | defined to be C<0>, then they are not. |
|
|
2228 | |
|
|
2229 | =item EV_MINIMAL |
|
|
2230 | |
|
|
2231 | If you need to shave off some kilobytes of code at the expense of some |
|
|
2232 | speed, define this symbol to C<1>. Currently only used for gcc to override |
|
|
2233 | some inlining decisions, saves roughly 30% codesize of amd64. |
|
|
2234 | |
|
|
2235 | =item EV_PID_HASHSIZE |
|
|
2236 | |
|
|
2237 | C<ev_child> watchers use a small hash table to distribute workload by |
|
|
2238 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
|
|
2239 | than enough. If you need to manage thousands of children you might want to |
|
|
2240 | increase this value (I<must> be a power of two). |
|
|
2241 | |
|
|
2242 | =item EV_INOTIFY_HASHSIZE |
|
|
2243 | |
|
|
2244 | C<ev_staz> watchers use a small hash table to distribute workload by |
|
|
2245 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
|
|
2246 | usually more than enough. If you need to manage thousands of C<ev_stat> |
|
|
2247 | watchers you might want to increase this value (I<must> be a power of |
|
|
2248 | two). |
1638 | |
2249 | |
1639 | =item EV_COMMON |
2250 | =item EV_COMMON |
1640 | |
2251 | |
1641 | By default, all watchers have a C<void *data> member. By redefining |
2252 | By default, all watchers have a C<void *data> member. By redefining |
1642 | this macro to a something else you can include more and other types of |
2253 | this macro to a something else you can include more and other types of |
… | |
… | |
1647 | |
2258 | |
1648 | #define EV_COMMON \ |
2259 | #define EV_COMMON \ |
1649 | SV *self; /* contains this struct */ \ |
2260 | SV *self; /* contains this struct */ \ |
1650 | SV *cb_sv, *fh /* note no trailing ";" */ |
2261 | SV *cb_sv, *fh /* note no trailing ";" */ |
1651 | |
2262 | |
1652 | =item EV_CB_DECLARE(type) |
2263 | =item EV_CB_DECLARE (type) |
1653 | |
2264 | |
1654 | =item EV_CB_INVOKE(watcher,revents) |
2265 | =item EV_CB_INVOKE (watcher, revents) |
1655 | |
2266 | |
1656 | =item ev_set_cb(ev,cb) |
2267 | =item ev_set_cb (ev, cb) |
1657 | |
2268 | |
1658 | Can be used to change the callback member declaration in each watcher, |
2269 | Can be used to change the callback member declaration in each watcher, |
1659 | and the way callbacks are invoked and set. Must expand to a struct member |
2270 | and the way callbacks are invoked and set. Must expand to a struct member |
1660 | definition and a statement, respectively. See the F<ev.v> header file for |
2271 | definition and a statement, respectively. See the F<ev.v> header file for |
1661 | their default definitions. One possible use for overriding these is to |
2272 | their default definitions. One possible use for overriding these is to |
1662 | avoid the ev_loop pointer as first argument in all cases, or to use method |
2273 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
1663 | calls instead of plain function calls in C++. |
2274 | method calls instead of plain function calls in C++. |
1664 | |
2275 | |
1665 | =head2 EXAMPLES |
2276 | =head2 EXAMPLES |
1666 | |
2277 | |
1667 | For a real-world example of a program the includes libev |
2278 | For a real-world example of a program the includes libev |
1668 | verbatim, you can have a look at the EV perl module |
2279 | verbatim, you can have a look at the EV perl module |
… | |
… | |
1671 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2282 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
1672 | will be compiled. It is pretty complex because it provides its own header |
2283 | will be compiled. It is pretty complex because it provides its own header |
1673 | file. |
2284 | file. |
1674 | |
2285 | |
1675 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2286 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
1676 | that everybody includes and which overrides some autoconf choices: |
2287 | that everybody includes and which overrides some configure choices: |
1677 | |
2288 | |
|
|
2289 | #define EV_MINIMAL 1 |
1678 | #define EV_USE_POLL 0 |
2290 | #define EV_USE_POLL 0 |
1679 | #define EV_MULTIPLICITY 0 |
2291 | #define EV_MULTIPLICITY 0 |
1680 | #define EV_PERIODICS 0 |
2292 | #define EV_PERIODIC_ENABLE 0 |
|
|
2293 | #define EV_STAT_ENABLE 0 |
|
|
2294 | #define EV_FORK_ENABLE 0 |
1681 | #define EV_CONFIG_H <config.h> |
2295 | #define EV_CONFIG_H <config.h> |
|
|
2296 | #define EV_MINPRI 0 |
|
|
2297 | #define EV_MAXPRI 0 |
1682 | |
2298 | |
1683 | #include "ev++.h" |
2299 | #include "ev++.h" |
1684 | |
2300 | |
1685 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2301 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
1686 | |
2302 | |
1687 | #include "ev_cpp.h" |
2303 | #include "ev_cpp.h" |
1688 | #include "ev.c" |
2304 | #include "ev.c" |
1689 | |
2305 | |
|
|
2306 | |
|
|
2307 | =head1 COMPLEXITIES |
|
|
2308 | |
|
|
2309 | In this section the complexities of (many of) the algorithms used inside |
|
|
2310 | libev will be explained. For complexity discussions about backends see the |
|
|
2311 | documentation for C<ev_default_init>. |
|
|
2312 | |
|
|
2313 | All of the following are about amortised time: If an array needs to be |
|
|
2314 | extended, libev needs to realloc and move the whole array, but this |
|
|
2315 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2316 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2317 | it is much faster and asymptotically approaches constant time. |
|
|
2318 | |
|
|
2319 | =over 4 |
|
|
2320 | |
|
|
2321 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
|
|
2322 | |
|
|
2323 | This means that, when you have a watcher that triggers in one hour and |
|
|
2324 | there are 100 watchers that would trigger before that then inserting will |
|
|
2325 | have to skip those 100 watchers. |
|
|
2326 | |
|
|
2327 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
|
|
2328 | |
|
|
2329 | That means that for changing a timer costs less than removing/adding them |
|
|
2330 | as only the relative motion in the event queue has to be paid for. |
|
|
2331 | |
|
|
2332 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
|
|
2333 | |
|
|
2334 | These just add the watcher into an array or at the head of a list. |
|
|
2335 | =item Stopping check/prepare/idle watchers: O(1) |
|
|
2336 | |
|
|
2337 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
|
|
2338 | |
|
|
2339 | These watchers are stored in lists then need to be walked to find the |
|
|
2340 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2341 | have many watchers waiting for the same fd or signal). |
|
|
2342 | |
|
|
2343 | =item Finding the next timer per loop iteration: O(1) |
|
|
2344 | |
|
|
2345 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
|
|
2346 | |
|
|
2347 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2348 | libev to recalculate its status (and possibly tell the kernel). |
|
|
2349 | |
|
|
2350 | =item Activating one watcher: O(1) |
|
|
2351 | |
|
|
2352 | =item Priority handling: O(number_of_priorities) |
|
|
2353 | |
|
|
2354 | Priorities are implemented by allocating some space for each |
|
|
2355 | priority. When doing priority-based operations, libev usually has to |
|
|
2356 | linearly search all the priorities. |
|
|
2357 | |
|
|
2358 | =back |
|
|
2359 | |
|
|
2360 | |
1690 | =head1 AUTHOR |
2361 | =head1 AUTHOR |
1691 | |
2362 | |
1692 | Marc Lehmann <libev@schmorp.de>. |
2363 | Marc Lehmann <libev@schmorp.de>. |
1693 | |
2364 | |