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2 | |
2 | |
3 | libev - a high performance full-featured event loop written in C |
3 | libev - a high performance full-featured event loop written in C |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | /* this is the only header you need */ |
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8 | #include <ev.h> |
7 | #include <ev.h> |
9 | |
8 | |
10 | /* what follows is a fully working example program */ |
9 | =head1 EXAMPLE PROGRAM |
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10 | |
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11 | #include <ev.h> |
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12 | |
11 | ev_io stdin_watcher; |
13 | ev_io stdin_watcher; |
12 | ev_timer timeout_watcher; |
14 | ev_timer timeout_watcher; |
13 | |
15 | |
14 | /* called when data readable on stdin */ |
16 | /* called when data readable on stdin */ |
15 | static void |
17 | static void |
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45 | |
47 | |
46 | return 0; |
48 | return 0; |
47 | } |
49 | } |
48 | |
50 | |
49 | =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>. |
50 | |
56 | |
51 | 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 |
52 | 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 |
53 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
54 | |
60 | |
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61 | 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 |
62 | watcher. |
68 | watcher. |
63 | |
69 | |
64 | =head1 FEATURES |
70 | =head1 FEATURES |
65 | |
71 | |
66 | 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 |
67 | kqueue mechanisms for file descriptor events, relative timers, absolute |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
68 | timers with customised rescheduling, signal events, process status change |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
69 | events (related to SIGCHLD), and event watchers dealing with the event |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
70 | 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 |
71 | 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 |
72 | it to libevent for example). |
85 | for example). |
73 | |
86 | |
74 | =head1 CONVENTIONS |
87 | =head1 CONVENTIONS |
75 | |
88 | |
76 | Libev is very configurable. In this manual the default configuration |
89 | Libev is very configurable. In this manual the default configuration will |
77 | will be described, which supports multiple event loops. For more info |
90 | be described, which supports multiple event loops. For more info about |
78 | about various configuration options please have a look at the file |
91 | various configuration options please have a look at B<EMBED> section in |
79 | F<README.embed> in the libev distribution. If libev was configured without |
92 | this manual. If libev was configured without support for multiple event |
80 | support for multiple event loops, then all functions taking an initial |
93 | loops, then all functions taking an initial argument of name C<loop> |
81 | 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. |
82 | will not have this argument. |
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83 | |
95 | |
84 | =head1 TIME REPRESENTATION |
96 | =head1 TIME REPRESENTATION |
85 | |
97 | |
86 | Libev represents time as a single floating point number, representing the |
98 | Libev represents time as a single floating point number, representing the |
87 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
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105 | |
117 | |
106 | =item int ev_version_major () |
118 | =item int ev_version_major () |
107 | |
119 | |
108 | =item int ev_version_minor () |
120 | =item int ev_version_minor () |
109 | |
121 | |
110 | You can find out the major and minor version numbers of the library |
122 | You can find out the major and minor ABI version numbers of the library |
111 | you linked against by calling the functions C<ev_version_major> and |
123 | you linked against by calling the functions C<ev_version_major> and |
112 | C<ev_version_minor>. If you want, you can compare against the global |
124 | C<ev_version_minor>. If you want, you can compare against the global |
113 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
125 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
114 | version of the library your program was compiled against. |
126 | version of the library your program was compiled against. |
115 | |
127 | |
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128 | These version numbers refer to the ABI version of the library, not the |
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129 | release version. |
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130 | |
116 | Usually, it's a good idea to terminate if the major versions mismatch, |
131 | Usually, it's a good idea to terminate if the major versions mismatch, |
117 | as this indicates an incompatible change. Minor versions are usually |
132 | as this indicates an incompatible change. Minor versions are usually |
118 | compatible to older versions, so a larger minor version alone is usually |
133 | compatible to older versions, so a larger minor version alone is usually |
119 | not a problem. |
134 | not a problem. |
120 | |
135 | |
121 | Example: make sure we haven't accidentally been linked against the wrong |
136 | Example: Make sure we haven't accidentally been linked against the wrong |
122 | version: |
137 | version. |
123 | |
138 | |
124 | assert (("libev version mismatch", |
139 | assert (("libev version mismatch", |
125 | ev_version_major () == EV_VERSION_MAJOR |
140 | ev_version_major () == EV_VERSION_MAJOR |
126 | && ev_version_minor () >= EV_VERSION_MINOR)); |
141 | && ev_version_minor () >= EV_VERSION_MINOR)); |
127 | |
142 | |
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155 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
170 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
156 | recommended ones. |
171 | recommended ones. |
157 | |
172 | |
158 | See the description of C<ev_embed> watchers for more info. |
173 | See the description of C<ev_embed> watchers for more info. |
159 | |
174 | |
160 | =item ev_set_allocator (void *(*cb)(void *ptr, size_t size)) |
175 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
161 | |
176 | |
162 | Sets the allocation function to use (the prototype and semantics are |
177 | Sets the allocation function to use (the prototype is similar - the |
163 | identical to the realloc C function). It is used to allocate and free |
178 | semantics is identical - to the realloc C function). It is used to |
164 | memory (no surprises here). If it returns zero when memory needs to be |
179 | allocate and free memory (no surprises here). If it returns zero when |
165 | allocated, the library might abort or take some potentially destructive |
180 | memory needs to be allocated, the library might abort or take some |
166 | action. The default is your system realloc function. |
181 | potentially destructive action. The default is your system realloc |
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182 | function. |
167 | |
183 | |
168 | You could override this function in high-availability programs to, say, |
184 | You could override this function in high-availability programs to, say, |
169 | free some memory if it cannot allocate memory, to use a special allocator, |
185 | free some memory if it cannot allocate memory, to use a special allocator, |
170 | or even to sleep a while and retry until some memory is available. |
186 | or even to sleep a while and retry until some memory is available. |
171 | |
187 | |
172 | Example: replace the libev allocator with one that waits a bit and then |
188 | Example: Replace the libev allocator with one that waits a bit and then |
173 | retries: better than mine). |
189 | retries). |
174 | |
190 | |
175 | static void * |
191 | static void * |
176 | persistent_realloc (void *ptr, size_t size) |
192 | persistent_realloc (void *ptr, size_t size) |
177 | { |
193 | { |
178 | for (;;) |
194 | for (;;) |
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197 | callback is set, then libev will expect it to remedy the sitution, no |
213 | callback is set, then libev will expect it to remedy the sitution, no |
198 | matter what, when it returns. That is, libev will generally retry the |
214 | matter what, when it returns. That is, libev will generally retry the |
199 | requested operation, or, if the condition doesn't go away, do bad stuff |
215 | requested operation, or, if the condition doesn't go away, do bad stuff |
200 | (such as abort). |
216 | (such as abort). |
201 | |
217 | |
202 | Example: do the same thing as libev does internally: |
218 | Example: This is basically the same thing that libev does internally, too. |
203 | |
219 | |
204 | static void |
220 | static void |
205 | fatal_error (const char *msg) |
221 | fatal_error (const char *msg) |
206 | { |
222 | { |
207 | perror (msg); |
223 | perror (msg); |
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257 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
273 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
258 | override the flags completely if it is found in the environment. This is |
274 | override the flags completely if it is found in the environment. This is |
259 | useful to try out specific backends to test their performance, or to work |
275 | useful to try out specific backends to test their performance, or to work |
260 | around bugs. |
276 | around bugs. |
261 | |
277 | |
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278 | =item C<EVFLAG_FORKCHECK> |
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279 | |
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280 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
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281 | a fork, you can also make libev check for a fork in each iteration by |
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282 | enabling this flag. |
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283 | |
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284 | This works by calling C<getpid ()> on every iteration of the loop, |
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285 | and thus this might slow down your event loop if you do a lot of loop |
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286 | iterations and little real work, but is usually not noticeable (on my |
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287 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
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288 | without a syscall and thus I<very> fast, but my Linux system also has |
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289 | C<pthread_atfork> which is even faster). |
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290 | |
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291 | The big advantage of this flag is that you can forget about fork (and |
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292 | forget about forgetting to tell libev about forking) when you use this |
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293 | flag. |
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294 | |
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295 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
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296 | environment variable. |
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297 | |
262 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
298 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
263 | |
299 | |
264 | This is your standard select(2) backend. Not I<completely> standard, as |
300 | This is your standard select(2) backend. Not I<completely> standard, as |
265 | libev tries to roll its own fd_set with no limits on the number of fds, |
301 | libev tries to roll its own fd_set with no limits on the number of fds, |
266 | but if that fails, expect a fairly low limit on the number of fds when |
302 | but if that fails, expect a fairly low limit on the number of fds when |
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353 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
389 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
354 | always distinct from the default loop. Unlike the default loop, it cannot |
390 | always distinct from the default loop. Unlike the default loop, it cannot |
355 | handle signal and child watchers, and attempts to do so will be greeted by |
391 | handle signal and child watchers, and attempts to do so will be greeted by |
356 | undefined behaviour (or a failed assertion if assertions are enabled). |
392 | undefined behaviour (or a failed assertion if assertions are enabled). |
357 | |
393 | |
358 | Example: try to create a event loop that uses epoll and nothing else. |
394 | Example: Try to create a event loop that uses epoll and nothing else. |
359 | |
395 | |
360 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
396 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
361 | if (!epoller) |
397 | if (!epoller) |
362 | fatal ("no epoll found here, maybe it hides under your chair"); |
398 | fatal ("no epoll found here, maybe it hides under your chair"); |
363 | |
399 | |
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401 | |
437 | |
402 | Like C<ev_default_fork>, but acts on an event loop created by |
438 | Like C<ev_default_fork>, but acts on an event loop created by |
403 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
439 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
404 | after fork, and how you do this is entirely your own problem. |
440 | after fork, and how you do this is entirely your own problem. |
405 | |
441 | |
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442 | =item unsigned int ev_loop_count (loop) |
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443 | |
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444 | Returns the count of loop iterations for the loop, which is identical to |
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445 | the number of times libev did poll for new events. It starts at C<0> and |
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446 | happily wraps around with enough iterations. |
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447 | |
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448 | This value can sometimes be useful as a generation counter of sorts (it |
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449 | "ticks" the number of loop iterations), as it roughly corresponds with |
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450 | C<ev_prepare> and C<ev_check> calls. |
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451 | |
406 | =item unsigned int ev_backend (loop) |
452 | =item unsigned int ev_backend (loop) |
407 | |
453 | |
408 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
454 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
409 | use. |
455 | use. |
410 | |
456 | |
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443 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
489 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
444 | usually a better approach for this kind of thing. |
490 | usually a better approach for this kind of thing. |
445 | |
491 | |
446 | Here are the gory details of what C<ev_loop> does: |
492 | Here are the gory details of what C<ev_loop> does: |
447 | |
493 | |
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494 | - Before the first iteration, call any pending watchers. |
448 | * If there are no active watchers (reference count is zero), return. |
495 | * If there are no active watchers (reference count is zero), return. |
449 | - Queue prepare watchers and then call all outstanding watchers. |
496 | - Queue all prepare watchers and then call all outstanding watchers. |
450 | - If we have been forked, recreate the kernel state. |
497 | - If we have been forked, recreate the kernel state. |
451 | - Update the kernel state with all outstanding changes. |
498 | - Update the kernel state with all outstanding changes. |
452 | - Update the "event loop time". |
499 | - Update the "event loop time". |
453 | - Calculate for how long to block. |
500 | - Calculate for how long to block. |
454 | - Block the process, waiting for any events. |
501 | - Block the process, waiting for any events. |
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462 | Signals and child watchers are implemented as I/O watchers, and will |
509 | Signals and child watchers are implemented as I/O watchers, and will |
463 | be handled here by queueing them when their watcher gets executed. |
510 | be handled here by queueing them when their watcher gets executed. |
464 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
511 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
465 | were used, return, otherwise continue with step *. |
512 | were used, return, otherwise continue with step *. |
466 | |
513 | |
467 | Example: queue some jobs and then loop until no events are outsanding |
514 | Example: Queue some jobs and then loop until no events are outsanding |
468 | anymore. |
515 | anymore. |
469 | |
516 | |
470 | ... queue jobs here, make sure they register event watchers as long |
517 | ... queue jobs here, make sure they register event watchers as long |
471 | ... as they still have work to do (even an idle watcher will do..) |
518 | ... as they still have work to do (even an idle watcher will do..) |
472 | ev_loop (my_loop, 0); |
519 | ev_loop (my_loop, 0); |
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492 | visible to the libev user and should not keep C<ev_loop> from exiting if |
539 | visible to the libev user and should not keep C<ev_loop> from exiting if |
493 | no event watchers registered by it are active. It is also an excellent |
540 | no event watchers registered by it are active. It is also an excellent |
494 | way to do this for generic recurring timers or from within third-party |
541 | way to do this for generic recurring timers or from within third-party |
495 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
542 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
496 | |
543 | |
497 | Example: create a signal watcher, but keep it from keeping C<ev_loop> |
544 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
498 | running when nothing else is active. |
545 | running when nothing else is active. |
499 | |
546 | |
500 | struct dv_signal exitsig; |
547 | struct ev_signal exitsig; |
501 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
548 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
502 | ev_signal_start (myloop, &exitsig); |
549 | ev_signal_start (loop, &exitsig); |
503 | evf_unref (myloop); |
550 | evf_unref (loop); |
504 | |
551 | |
505 | Example: for some weird reason, unregister the above signal handler again. |
552 | Example: For some weird reason, unregister the above signal handler again. |
506 | |
553 | |
507 | ev_ref (myloop); |
554 | ev_ref (loop); |
508 | ev_signal_stop (myloop, &exitsig); |
555 | ev_signal_stop (loop, &exitsig); |
509 | |
556 | |
510 | =back |
557 | =back |
511 | |
558 | |
512 | |
559 | |
513 | =head1 ANATOMY OF A WATCHER |
560 | =head1 ANATOMY OF A WATCHER |
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693 | =item bool ev_is_pending (ev_TYPE *watcher) |
740 | =item bool ev_is_pending (ev_TYPE *watcher) |
694 | |
741 | |
695 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
742 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
696 | events but its callback has not yet been invoked). As long as a watcher |
743 | events but its callback has not yet been invoked). As long as a watcher |
697 | is pending (but not active) you must not call an init function on it (but |
744 | is pending (but not active) you must not call an init function on it (but |
698 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
745 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
699 | libev (e.g. you cnanot C<free ()> it). |
746 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
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747 | it). |
700 | |
748 | |
701 | =item callback = ev_cb (ev_TYPE *watcher) |
749 | =item callback ev_cb (ev_TYPE *watcher) |
702 | |
750 | |
703 | Returns the callback currently set on the watcher. |
751 | Returns the callback currently set on the watcher. |
704 | |
752 | |
705 | =item ev_cb_set (ev_TYPE *watcher, callback) |
753 | =item ev_cb_set (ev_TYPE *watcher, callback) |
706 | |
754 | |
707 | Change the callback. You can change the callback at virtually any time |
755 | Change the callback. You can change the callback at virtually any time |
708 | (modulo threads). |
756 | (modulo threads). |
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757 | |
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758 | =item ev_set_priority (ev_TYPE *watcher, priority) |
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759 | |
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760 | =item int ev_priority (ev_TYPE *watcher) |
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761 | |
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762 | Set and query the priority of the watcher. The priority is a small |
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763 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
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764 | (default: C<-2>). Pending watchers with higher priority will be invoked |
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765 | before watchers with lower priority, but priority will not keep watchers |
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766 | from being executed (except for C<ev_idle> watchers). |
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767 | |
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768 | This means that priorities are I<only> used for ordering callback |
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769 | invocation after new events have been received. This is useful, for |
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770 | example, to reduce latency after idling, or more often, to bind two |
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771 | watchers on the same event and make sure one is called first. |
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772 | |
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773 | If you need to suppress invocation when higher priority events are pending |
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774 | you need to look at C<ev_idle> watchers, which provide this functionality. |
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775 | |
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776 | You I<must not> change the priority of a watcher as long as it is active or |
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777 | pending. |
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778 | |
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779 | The default priority used by watchers when no priority has been set is |
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780 | always C<0>, which is supposed to not be too high and not be too low :). |
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781 | |
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782 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
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783 | fine, as long as you do not mind that the priority value you query might |
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784 | or might not have been adjusted to be within valid range. |
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785 | |
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786 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
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787 | |
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788 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
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789 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
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790 | can deal with that fact. |
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791 | |
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792 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
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793 | |
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794 | If the watcher is pending, this function returns clears its pending status |
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795 | and returns its C<revents> bitset (as if its callback was invoked). If the |
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796 | watcher isn't pending it does nothing and returns C<0>. |
709 | |
797 | |
710 | =back |
798 | =back |
711 | |
799 | |
712 | |
800 | |
713 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
801 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
734 | { |
822 | { |
735 | struct my_io *w = (struct my_io *)w_; |
823 | struct my_io *w = (struct my_io *)w_; |
736 | ... |
824 | ... |
737 | } |
825 | } |
738 | |
826 | |
739 | More interesting and less C-conformant ways of catsing your callback type |
827 | More interesting and less C-conformant ways of casting your callback type |
740 | have been omitted.... |
828 | instead have been omitted. |
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829 | |
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830 | Another common scenario is having some data structure with multiple |
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831 | watchers: |
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832 | |
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833 | struct my_biggy |
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834 | { |
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835 | int some_data; |
|
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836 | ev_timer t1; |
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837 | ev_timer t2; |
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838 | } |
|
|
839 | |
|
|
840 | In this case getting the pointer to C<my_biggy> is a bit more complicated, |
|
|
841 | you need to use C<offsetof>: |
|
|
842 | |
|
|
843 | #include <stddef.h> |
|
|
844 | |
|
|
845 | static void |
|
|
846 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
847 | { |
|
|
848 | struct my_biggy big = (struct my_biggy * |
|
|
849 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
850 | } |
|
|
851 | |
|
|
852 | static void |
|
|
853 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
854 | { |
|
|
855 | struct my_biggy big = (struct my_biggy * |
|
|
856 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
857 | } |
741 | |
858 | |
742 | |
859 | |
743 | =head1 WATCHER TYPES |
860 | =head1 WATCHER TYPES |
744 | |
861 | |
745 | This section describes each watcher in detail, but will not repeat |
862 | This section describes each watcher in detail, but will not repeat |
… | |
… | |
790 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
907 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
791 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
908 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
792 | |
909 | |
793 | If you cannot run the fd in non-blocking mode (for example you should not |
910 | If you cannot run the fd in non-blocking mode (for example you should not |
794 | play around with an Xlib connection), then you have to seperately re-test |
911 | play around with an Xlib connection), then you have to seperately re-test |
795 | wether a file descriptor is really ready with a known-to-be good interface |
912 | whether a file descriptor is really ready with a known-to-be good interface |
796 | such as poll (fortunately in our Xlib example, Xlib already does this on |
913 | such as poll (fortunately in our Xlib example, Xlib already does this on |
797 | its own, so its quite safe to use). |
914 | its own, so its quite safe to use). |
|
|
915 | |
|
|
916 | =head3 The special problem of disappearing file descriptors |
|
|
917 | |
|
|
918 | Some backends (e.g kqueue, epoll) need to be told about closing a file |
|
|
919 | descriptor (either by calling C<close> explicitly or by any other means, |
|
|
920 | such as C<dup>). The reason is that you register interest in some file |
|
|
921 | descriptor, but when it goes away, the operating system will silently drop |
|
|
922 | this interest. If another file descriptor with the same number then is |
|
|
923 | registered with libev, there is no efficient way to see that this is, in |
|
|
924 | fact, a different file descriptor. |
|
|
925 | |
|
|
926 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
927 | the following policy: Each time C<ev_io_set> is being called, libev |
|
|
928 | will assume that this is potentially a new file descriptor, otherwise |
|
|
929 | it is assumed that the file descriptor stays the same. That means that |
|
|
930 | you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the |
|
|
931 | descriptor even if the file descriptor number itself did not change. |
|
|
932 | |
|
|
933 | This is how one would do it normally anyway, the important point is that |
|
|
934 | the libev application should not optimise around libev but should leave |
|
|
935 | optimisations to libev. |
|
|
936 | |
|
|
937 | |
|
|
938 | =head3 Watcher-Specific Functions |
798 | |
939 | |
799 | =over 4 |
940 | =over 4 |
800 | |
941 | |
801 | =item ev_io_init (ev_io *, callback, int fd, int events) |
942 | =item ev_io_init (ev_io *, callback, int fd, int events) |
802 | |
943 | |
… | |
… | |
814 | |
955 | |
815 | The events being watched. |
956 | The events being watched. |
816 | |
957 | |
817 | =back |
958 | =back |
818 | |
959 | |
819 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
960 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
820 | readable, but only once. Since it is likely line-buffered, you could |
961 | readable, but only once. Since it is likely line-buffered, you could |
821 | attempt to read a whole line in the callback: |
962 | attempt to read a whole line in the callback. |
822 | |
963 | |
823 | static void |
964 | static void |
824 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
965 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
825 | { |
966 | { |
826 | ev_io_stop (loop, w); |
967 | ev_io_stop (loop, w); |
… | |
… | |
856 | |
997 | |
857 | The callback is guarenteed to be invoked only when its timeout has passed, |
998 | The callback is guarenteed to be invoked only when its timeout has passed, |
858 | but if multiple timers become ready during the same loop iteration then |
999 | but if multiple timers become ready during the same loop iteration then |
859 | order of execution is undefined. |
1000 | order of execution is undefined. |
860 | |
1001 | |
|
|
1002 | =head3 Watcher-Specific Functions and Data Members |
|
|
1003 | |
861 | =over 4 |
1004 | =over 4 |
862 | |
1005 | |
863 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1006 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
864 | |
1007 | |
865 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
1008 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
878 | =item ev_timer_again (loop) |
1021 | =item ev_timer_again (loop) |
879 | |
1022 | |
880 | This will act as if the timer timed out and restart it again if it is |
1023 | This will act as if the timer timed out and restart it again if it is |
881 | repeating. The exact semantics are: |
1024 | repeating. The exact semantics are: |
882 | |
1025 | |
|
|
1026 | If the timer is pending, its pending status is cleared. |
|
|
1027 | |
883 | If the timer is started but nonrepeating, stop it. |
1028 | If the timer is started but nonrepeating, stop it (as if it timed out). |
884 | |
1029 | |
885 | If the timer is repeating, either start it if necessary (with the repeat |
1030 | If the timer is repeating, either start it if necessary (with the |
886 | value), or reset the running timer to the repeat value. |
1031 | C<repeat> value), or reset the running timer to the C<repeat> value. |
887 | |
1032 | |
888 | This sounds a bit complicated, but here is a useful and typical |
1033 | This sounds a bit complicated, but here is a useful and typical |
889 | example: Imagine you have a tcp connection and you want a so-called |
1034 | example: Imagine you have a tcp connection and you want a so-called idle |
890 | idle timeout, that is, you want to be called when there have been, |
1035 | timeout, that is, you want to be called when there have been, say, 60 |
891 | say, 60 seconds of inactivity on the socket. The easiest way to do |
1036 | seconds of inactivity on the socket. The easiest way to do this is to |
892 | this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling |
1037 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
893 | C<ev_timer_again> each time you successfully read or write some data. If |
1038 | C<ev_timer_again> each time you successfully read or write some data. If |
894 | you go into an idle state where you do not expect data to travel on the |
1039 | you go into an idle state where you do not expect data to travel on the |
895 | socket, you can stop the timer, and again will automatically restart it if |
1040 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
896 | need be. |
1041 | automatically restart it if need be. |
897 | |
1042 | |
898 | You can also ignore the C<after> value and C<ev_timer_start> altogether |
1043 | That means you can ignore the C<after> value and C<ev_timer_start> |
899 | and only ever use the C<repeat> value: |
1044 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
900 | |
1045 | |
901 | ev_timer_init (timer, callback, 0., 5.); |
1046 | ev_timer_init (timer, callback, 0., 5.); |
902 | ev_timer_again (loop, timer); |
1047 | ev_timer_again (loop, timer); |
903 | ... |
1048 | ... |
904 | timer->again = 17.; |
1049 | timer->again = 17.; |
905 | ev_timer_again (loop, timer); |
1050 | ev_timer_again (loop, timer); |
906 | ... |
1051 | ... |
907 | timer->again = 10.; |
1052 | timer->again = 10.; |
908 | ev_timer_again (loop, timer); |
1053 | ev_timer_again (loop, timer); |
909 | |
1054 | |
910 | This is more efficient then stopping/starting the timer eahc time you want |
1055 | This is more slightly efficient then stopping/starting the timer each time |
911 | to modify its timeout value. |
1056 | you want to modify its timeout value. |
912 | |
1057 | |
913 | =item ev_tstamp repeat [read-write] |
1058 | =item ev_tstamp repeat [read-write] |
914 | |
1059 | |
915 | The current C<repeat> value. Will be used each time the watcher times out |
1060 | The current C<repeat> value. Will be used each time the watcher times out |
916 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1061 | or C<ev_timer_again> is called and determines the next timeout (if any), |
917 | which is also when any modifications are taken into account. |
1062 | which is also when any modifications are taken into account. |
918 | |
1063 | |
919 | =back |
1064 | =back |
920 | |
1065 | |
921 | Example: create a timer that fires after 60 seconds. |
1066 | Example: Create a timer that fires after 60 seconds. |
922 | |
1067 | |
923 | static void |
1068 | static void |
924 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1069 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
925 | { |
1070 | { |
926 | .. one minute over, w is actually stopped right here |
1071 | .. one minute over, w is actually stopped right here |
… | |
… | |
928 | |
1073 | |
929 | struct ev_timer mytimer; |
1074 | struct ev_timer mytimer; |
930 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1075 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
931 | ev_timer_start (loop, &mytimer); |
1076 | ev_timer_start (loop, &mytimer); |
932 | |
1077 | |
933 | Example: create a timeout timer that times out after 10 seconds of |
1078 | Example: Create a timeout timer that times out after 10 seconds of |
934 | inactivity. |
1079 | inactivity. |
935 | |
1080 | |
936 | static void |
1081 | static void |
937 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1082 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
938 | { |
1083 | { |
… | |
… | |
958 | but on wallclock time (absolute time). You can tell a periodic watcher |
1103 | but on wallclock time (absolute time). You can tell a periodic watcher |
959 | to trigger "at" some specific point in time. For example, if you tell a |
1104 | to trigger "at" some specific point in time. For example, if you tell a |
960 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1105 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
961 | + 10.>) and then reset your system clock to the last year, then it will |
1106 | + 10.>) and then reset your system clock to the last year, then it will |
962 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1107 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
963 | roughly 10 seconds later and of course not if you reset your system time |
1108 | roughly 10 seconds later). |
964 | again). |
|
|
965 | |
1109 | |
966 | They can also be used to implement vastly more complex timers, such as |
1110 | They can also be used to implement vastly more complex timers, such as |
967 | triggering an event on eahc midnight, local time. |
1111 | triggering an event on each midnight, local time or other, complicated, |
|
|
1112 | rules. |
968 | |
1113 | |
969 | As with timers, the callback is guarenteed to be invoked only when the |
1114 | As with timers, the callback is guarenteed to be invoked only when the |
970 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1115 | time (C<at>) has been passed, but if multiple periodic timers become ready |
971 | during the same loop iteration then order of execution is undefined. |
1116 | during the same loop iteration then order of execution is undefined. |
972 | |
1117 | |
|
|
1118 | =head3 Watcher-Specific Functions and Data Members |
|
|
1119 | |
973 | =over 4 |
1120 | =over 4 |
974 | |
1121 | |
975 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1122 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
976 | |
1123 | |
977 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1124 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
… | |
… | |
979 | Lots of arguments, lets sort it out... There are basically three modes of |
1126 | Lots of arguments, lets sort it out... There are basically three modes of |
980 | operation, and we will explain them from simplest to complex: |
1127 | operation, and we will explain them from simplest to complex: |
981 | |
1128 | |
982 | =over 4 |
1129 | =over 4 |
983 | |
1130 | |
984 | =item * absolute timer (interval = reschedule_cb = 0) |
1131 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
985 | |
1132 | |
986 | In this configuration the watcher triggers an event at the wallclock time |
1133 | In this configuration the watcher triggers an event at the wallclock time |
987 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1134 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
988 | that is, if it is to be run at January 1st 2011 then it will run when the |
1135 | that is, if it is to be run at January 1st 2011 then it will run when the |
989 | system time reaches or surpasses this time. |
1136 | system time reaches or surpasses this time. |
990 | |
1137 | |
991 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1138 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
992 | |
1139 | |
993 | In this mode the watcher will always be scheduled to time out at the next |
1140 | In this mode the watcher will always be scheduled to time out at the next |
994 | C<at + N * interval> time (for some integer N) and then repeat, regardless |
1141 | C<at + N * interval> time (for some integer N, which can also be negative) |
995 | of any time jumps. |
1142 | and then repeat, regardless of any time jumps. |
996 | |
1143 | |
997 | This can be used to create timers that do not drift with respect to system |
1144 | This can be used to create timers that do not drift with respect to system |
998 | time: |
1145 | time: |
999 | |
1146 | |
1000 | ev_periodic_set (&periodic, 0., 3600., 0); |
1147 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
1006 | |
1153 | |
1007 | Another way to think about it (for the mathematically inclined) is that |
1154 | Another way to think about it (for the mathematically inclined) is that |
1008 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1155 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1009 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1156 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1010 | |
1157 | |
|
|
1158 | For numerical stability it is preferable that the C<at> value is near |
|
|
1159 | C<ev_now ()> (the current time), but there is no range requirement for |
|
|
1160 | this value. |
|
|
1161 | |
1011 | =item * manual reschedule mode (reschedule_cb = callback) |
1162 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1012 | |
1163 | |
1013 | In this mode the values for C<interval> and C<at> are both being |
1164 | In this mode the values for C<interval> and C<at> are both being |
1014 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1165 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1015 | reschedule callback will be called with the watcher as first, and the |
1166 | reschedule callback will be called with the watcher as first, and the |
1016 | current time as second argument. |
1167 | current time as second argument. |
1017 | |
1168 | |
1018 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1169 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1019 | ever, or make any event loop modifications>. If you need to stop it, |
1170 | ever, or make any event loop modifications>. If you need to stop it, |
1020 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1171 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1021 | starting a prepare watcher). |
1172 | starting an C<ev_prepare> watcher, which is legal). |
1022 | |
1173 | |
1023 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1174 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1024 | ev_tstamp now)>, e.g.: |
1175 | ev_tstamp now)>, e.g.: |
1025 | |
1176 | |
1026 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1177 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
1049 | Simply stops and restarts the periodic watcher again. This is only useful |
1200 | Simply stops and restarts the periodic watcher again. This is only useful |
1050 | when you changed some parameters or the reschedule callback would return |
1201 | when you changed some parameters or the reschedule callback would return |
1051 | a different time than the last time it was called (e.g. in a crond like |
1202 | a different time than the last time it was called (e.g. in a crond like |
1052 | program when the crontabs have changed). |
1203 | program when the crontabs have changed). |
1053 | |
1204 | |
|
|
1205 | =item ev_tstamp offset [read-write] |
|
|
1206 | |
|
|
1207 | When repeating, this contains the offset value, otherwise this is the |
|
|
1208 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
|
|
1209 | |
|
|
1210 | Can be modified any time, but changes only take effect when the periodic |
|
|
1211 | timer fires or C<ev_periodic_again> is being called. |
|
|
1212 | |
1054 | =item ev_tstamp interval [read-write] |
1213 | =item ev_tstamp interval [read-write] |
1055 | |
1214 | |
1056 | The current interval value. Can be modified any time, but changes only |
1215 | The current interval value. Can be modified any time, but changes only |
1057 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1216 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1058 | called. |
1217 | called. |
… | |
… | |
1063 | switched off. Can be changed any time, but changes only take effect when |
1222 | switched off. Can be changed any time, but changes only take effect when |
1064 | the periodic timer fires or C<ev_periodic_again> is being called. |
1223 | the periodic timer fires or C<ev_periodic_again> is being called. |
1065 | |
1224 | |
1066 | =back |
1225 | =back |
1067 | |
1226 | |
1068 | Example: call a callback every hour, or, more precisely, whenever the |
1227 | Example: Call a callback every hour, or, more precisely, whenever the |
1069 | system clock is divisible by 3600. The callback invocation times have |
1228 | system clock is divisible by 3600. The callback invocation times have |
1070 | potentially a lot of jittering, but good long-term stability. |
1229 | potentially a lot of jittering, but good long-term stability. |
1071 | |
1230 | |
1072 | static void |
1231 | static void |
1073 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1232 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
… | |
… | |
1077 | |
1236 | |
1078 | struct ev_periodic hourly_tick; |
1237 | struct ev_periodic hourly_tick; |
1079 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1238 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1080 | ev_periodic_start (loop, &hourly_tick); |
1239 | ev_periodic_start (loop, &hourly_tick); |
1081 | |
1240 | |
1082 | Example: the same as above, but use a reschedule callback to do it: |
1241 | Example: The same as above, but use a reschedule callback to do it: |
1083 | |
1242 | |
1084 | #include <math.h> |
1243 | #include <math.h> |
1085 | |
1244 | |
1086 | static ev_tstamp |
1245 | static ev_tstamp |
1087 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1246 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
1089 | return fmod (now, 3600.) + 3600.; |
1248 | return fmod (now, 3600.) + 3600.; |
1090 | } |
1249 | } |
1091 | |
1250 | |
1092 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1251 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1093 | |
1252 | |
1094 | Example: call a callback every hour, starting now: |
1253 | Example: Call a callback every hour, starting now: |
1095 | |
1254 | |
1096 | struct ev_periodic hourly_tick; |
1255 | struct ev_periodic hourly_tick; |
1097 | ev_periodic_init (&hourly_tick, clock_cb, |
1256 | ev_periodic_init (&hourly_tick, clock_cb, |
1098 | fmod (ev_now (loop), 3600.), 3600., 0); |
1257 | fmod (ev_now (loop), 3600.), 3600., 0); |
1099 | ev_periodic_start (loop, &hourly_tick); |
1258 | ev_periodic_start (loop, &hourly_tick); |
… | |
… | |
1111 | with the kernel (thus it coexists with your own signal handlers as long |
1270 | with the kernel (thus it coexists with your own signal handlers as long |
1112 | as you don't register any with libev). Similarly, when the last signal |
1271 | as you don't register any with libev). Similarly, when the last signal |
1113 | watcher for a signal is stopped libev will reset the signal handler to |
1272 | watcher for a signal is stopped libev will reset the signal handler to |
1114 | SIG_DFL (regardless of what it was set to before). |
1273 | SIG_DFL (regardless of what it was set to before). |
1115 | |
1274 | |
|
|
1275 | =head3 Watcher-Specific Functions and Data Members |
|
|
1276 | |
1116 | =over 4 |
1277 | =over 4 |
1117 | |
1278 | |
1118 | =item ev_signal_init (ev_signal *, callback, int signum) |
1279 | =item ev_signal_init (ev_signal *, callback, int signum) |
1119 | |
1280 | |
1120 | =item ev_signal_set (ev_signal *, int signum) |
1281 | =item ev_signal_set (ev_signal *, int signum) |
… | |
… | |
1131 | |
1292 | |
1132 | =head2 C<ev_child> - watch out for process status changes |
1293 | =head2 C<ev_child> - watch out for process status changes |
1133 | |
1294 | |
1134 | Child watchers trigger when your process receives a SIGCHLD in response to |
1295 | Child watchers trigger when your process receives a SIGCHLD in response to |
1135 | some child status changes (most typically when a child of yours dies). |
1296 | some child status changes (most typically when a child of yours dies). |
|
|
1297 | |
|
|
1298 | =head3 Watcher-Specific Functions and Data Members |
1136 | |
1299 | |
1137 | =over 4 |
1300 | =over 4 |
1138 | |
1301 | |
1139 | =item ev_child_init (ev_child *, callback, int pid) |
1302 | =item ev_child_init (ev_child *, callback, int pid) |
1140 | |
1303 | |
… | |
… | |
1160 | The process exit/trace status caused by C<rpid> (see your systems |
1323 | The process exit/trace status caused by C<rpid> (see your systems |
1161 | C<waitpid> and C<sys/wait.h> documentation for details). |
1324 | C<waitpid> and C<sys/wait.h> documentation for details). |
1162 | |
1325 | |
1163 | =back |
1326 | =back |
1164 | |
1327 | |
1165 | Example: try to exit cleanly on SIGINT and SIGTERM. |
1328 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1166 | |
1329 | |
1167 | static void |
1330 | static void |
1168 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1331 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1169 | { |
1332 | { |
1170 | ev_unloop (loop, EVUNLOOP_ALL); |
1333 | ev_unloop (loop, EVUNLOOP_ALL); |
… | |
… | |
1185 | not exist" is a status change like any other. The condition "path does |
1348 | not exist" is a status change like any other. The condition "path does |
1186 | not exist" is signified by the C<st_nlink> field being zero (which is |
1349 | not exist" is signified by the C<st_nlink> field being zero (which is |
1187 | otherwise always forced to be at least one) and all the other fields of |
1350 | otherwise always forced to be at least one) and all the other fields of |
1188 | the stat buffer having unspecified contents. |
1351 | the stat buffer having unspecified contents. |
1189 | |
1352 | |
|
|
1353 | The path I<should> be absolute and I<must not> end in a slash. If it is |
|
|
1354 | relative and your working directory changes, the behaviour is undefined. |
|
|
1355 | |
1190 | Since there is no standard to do this, the portable implementation simply |
1356 | Since there is no standard to do this, the portable implementation simply |
1191 | calls C<stat (2)> regulalry on the path to see if it changed somehow. You |
1357 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
1192 | can specify a recommended polling interval for this case. If you specify |
1358 | can specify a recommended polling interval for this case. If you specify |
1193 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1359 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1194 | unspecified default> value will be used (which you can expect to be around |
1360 | unspecified default> value will be used (which you can expect to be around |
1195 | five seconds, although this might change dynamically). Libev will also |
1361 | five seconds, although this might change dynamically). Libev will also |
1196 | impose a minimum interval which is currently around C<0.1>, but thats |
1362 | impose a minimum interval which is currently around C<0.1>, but thats |
… | |
… | |
1198 | |
1364 | |
1199 | This watcher type is not meant for massive numbers of stat watchers, |
1365 | This watcher type is not meant for massive numbers of stat watchers, |
1200 | as even with OS-supported change notifications, this can be |
1366 | as even with OS-supported change notifications, this can be |
1201 | resource-intensive. |
1367 | resource-intensive. |
1202 | |
1368 | |
1203 | At the time of this writing, no specific OS backends are implemented, but |
1369 | At the time of this writing, only the Linux inotify interface is |
1204 | if demand increases, at least a kqueue and inotify backend will be added. |
1370 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1371 | reader). Inotify will be used to give hints only and should not change the |
|
|
1372 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
|
|
1373 | to fall back to regular polling again even with inotify, but changes are |
|
|
1374 | usually detected immediately, and if the file exists there will be no |
|
|
1375 | polling. |
|
|
1376 | |
|
|
1377 | =head3 Watcher-Specific Functions and Data Members |
1205 | |
1378 | |
1206 | =over 4 |
1379 | =over 4 |
1207 | |
1380 | |
1208 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1381 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1209 | |
1382 | |
… | |
… | |
1273 | ev_stat_start (loop, &passwd); |
1446 | ev_stat_start (loop, &passwd); |
1274 | |
1447 | |
1275 | |
1448 | |
1276 | =head2 C<ev_idle> - when you've got nothing better to do... |
1449 | =head2 C<ev_idle> - when you've got nothing better to do... |
1277 | |
1450 | |
1278 | Idle watchers trigger events when there are no other events are pending |
1451 | Idle watchers trigger events when no other events of the same or higher |
1279 | (prepare, check and other idle watchers do not count). That is, as long |
1452 | priority are pending (prepare, check and other idle watchers do not |
1280 | as your process is busy handling sockets or timeouts (or even signals, |
1453 | count). |
1281 | imagine) it will not be triggered. But when your process is idle all idle |
1454 | |
1282 | watchers are being called again and again, once per event loop iteration - |
1455 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1456 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1457 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1458 | are pending), the idle watchers are being called once per event loop |
1283 | until stopped, that is, or your process receives more events and becomes |
1459 | iteration - until stopped, that is, or your process receives more events |
1284 | busy. |
1460 | and becomes busy again with higher priority stuff. |
1285 | |
1461 | |
1286 | The most noteworthy effect is that as long as any idle watchers are |
1462 | The most noteworthy effect is that as long as any idle watchers are |
1287 | active, the process will not block when waiting for new events. |
1463 | active, the process will not block when waiting for new events. |
1288 | |
1464 | |
1289 | Apart from keeping your process non-blocking (which is a useful |
1465 | Apart from keeping your process non-blocking (which is a useful |
1290 | effect on its own sometimes), idle watchers are a good place to do |
1466 | effect on its own sometimes), idle watchers are a good place to do |
1291 | "pseudo-background processing", or delay processing stuff to after the |
1467 | "pseudo-background processing", or delay processing stuff to after the |
1292 | event loop has handled all outstanding events. |
1468 | event loop has handled all outstanding events. |
1293 | |
1469 | |
|
|
1470 | =head3 Watcher-Specific Functions and Data Members |
|
|
1471 | |
1294 | =over 4 |
1472 | =over 4 |
1295 | |
1473 | |
1296 | =item ev_idle_init (ev_signal *, callback) |
1474 | =item ev_idle_init (ev_signal *, callback) |
1297 | |
1475 | |
1298 | Initialises and configures the idle watcher - it has no parameters of any |
1476 | Initialises and configures the idle watcher - it has no parameters of any |
1299 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1477 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1300 | believe me. |
1478 | believe me. |
1301 | |
1479 | |
1302 | =back |
1480 | =back |
1303 | |
1481 | |
1304 | Example: dynamically allocate an C<ev_idle>, start it, and in the |
1482 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1305 | callback, free it. Alos, use no error checking, as usual. |
1483 | callback, free it. Also, use no error checking, as usual. |
1306 | |
1484 | |
1307 | static void |
1485 | static void |
1308 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1486 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1309 | { |
1487 | { |
1310 | free (w); |
1488 | free (w); |
… | |
… | |
1355 | with priority higher than or equal to the event loop and one coroutine |
1533 | with priority higher than or equal to the event loop and one coroutine |
1356 | of lower priority, but only once, using idle watchers to keep the event |
1534 | of lower priority, but only once, using idle watchers to keep the event |
1357 | loop from blocking if lower-priority coroutines are active, thus mapping |
1535 | loop from blocking if lower-priority coroutines are active, thus mapping |
1358 | low-priority coroutines to idle/background tasks). |
1536 | low-priority coroutines to idle/background tasks). |
1359 | |
1537 | |
|
|
1538 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
|
|
1539 | priority, to ensure that they are being run before any other watchers |
|
|
1540 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
|
|
1541 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1542 | supports this, they will be called before other C<ev_check> watchers did |
|
|
1543 | their job. As C<ev_check> watchers are often used to embed other event |
|
|
1544 | loops those other event loops might be in an unusable state until their |
|
|
1545 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
|
|
1546 | others). |
|
|
1547 | |
|
|
1548 | =head3 Watcher-Specific Functions and Data Members |
|
|
1549 | |
1360 | =over 4 |
1550 | =over 4 |
1361 | |
1551 | |
1362 | =item ev_prepare_init (ev_prepare *, callback) |
1552 | =item ev_prepare_init (ev_prepare *, callback) |
1363 | |
1553 | |
1364 | =item ev_check_init (ev_check *, callback) |
1554 | =item ev_check_init (ev_check *, callback) |
… | |
… | |
1367 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1557 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1368 | macros, but using them is utterly, utterly and completely pointless. |
1558 | macros, but using them is utterly, utterly and completely pointless. |
1369 | |
1559 | |
1370 | =back |
1560 | =back |
1371 | |
1561 | |
1372 | Example: To include a library such as adns, you would add IO watchers |
1562 | There are a number of principal ways to embed other event loops or modules |
1373 | and a timeout watcher in a prepare handler, as required by libadns, and |
1563 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1564 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1565 | use for an actually working example. Another Perl module named C<EV::Glib> |
|
|
1566 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
|
|
1567 | into the Glib event loop). |
|
|
1568 | |
|
|
1569 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
1374 | in a check watcher, destroy them and call into libadns. What follows is |
1570 | and in a check watcher, destroy them and call into libadns. What follows |
1375 | pseudo-code only of course: |
1571 | is pseudo-code only of course. This requires you to either use a low |
|
|
1572 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1573 | the callbacks for the IO/timeout watchers might not have been called yet. |
1376 | |
1574 | |
1377 | static ev_io iow [nfd]; |
1575 | static ev_io iow [nfd]; |
1378 | static ev_timer tw; |
1576 | static ev_timer tw; |
1379 | |
1577 | |
1380 | static void |
1578 | static void |
1381 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1579 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1382 | { |
1580 | { |
1383 | // set the relevant poll flags |
|
|
1384 | // could also call adns_processreadable etc. here |
|
|
1385 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1386 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1387 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1388 | } |
1581 | } |
1389 | |
1582 | |
1390 | // create io watchers for each fd and a timer before blocking |
1583 | // create io watchers for each fd and a timer before blocking |
1391 | static void |
1584 | static void |
1392 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1585 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1393 | { |
1586 | { |
1394 | int timeout = 3600000;truct pollfd fds [nfd]; |
1587 | int timeout = 3600000; |
|
|
1588 | struct pollfd fds [nfd]; |
1395 | // actual code will need to loop here and realloc etc. |
1589 | // actual code will need to loop here and realloc etc. |
1396 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1590 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1397 | |
1591 | |
1398 | /* the callback is illegal, but won't be called as we stop during check */ |
1592 | /* the callback is illegal, but won't be called as we stop during check */ |
1399 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1593 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1400 | ev_timer_start (loop, &tw); |
1594 | ev_timer_start (loop, &tw); |
1401 | |
1595 | |
1402 | // create on ev_io per pollfd |
1596 | // create one ev_io per pollfd |
1403 | for (int i = 0; i < nfd; ++i) |
1597 | for (int i = 0; i < nfd; ++i) |
1404 | { |
1598 | { |
1405 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1599 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1406 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1600 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1407 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1601 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1408 | |
1602 | |
1409 | fds [i].revents = 0; |
1603 | fds [i].revents = 0; |
1410 | iow [i].data = fds + i; |
|
|
1411 | ev_io_start (loop, iow + i); |
1604 | ev_io_start (loop, iow + i); |
1412 | } |
1605 | } |
1413 | } |
1606 | } |
1414 | |
1607 | |
1415 | // stop all watchers after blocking |
1608 | // stop all watchers after blocking |
… | |
… | |
1417 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1610 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1418 | { |
1611 | { |
1419 | ev_timer_stop (loop, &tw); |
1612 | ev_timer_stop (loop, &tw); |
1420 | |
1613 | |
1421 | for (int i = 0; i < nfd; ++i) |
1614 | for (int i = 0; i < nfd; ++i) |
|
|
1615 | { |
|
|
1616 | // set the relevant poll flags |
|
|
1617 | // could also call adns_processreadable etc. here |
|
|
1618 | struct pollfd *fd = fds + i; |
|
|
1619 | int revents = ev_clear_pending (iow + i); |
|
|
1620 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1621 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1622 | |
|
|
1623 | // now stop the watcher |
1422 | ev_io_stop (loop, iow + i); |
1624 | ev_io_stop (loop, iow + i); |
|
|
1625 | } |
1423 | |
1626 | |
1424 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1627 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1628 | } |
|
|
1629 | |
|
|
1630 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1631 | in the prepare watcher and would dispose of the check watcher. |
|
|
1632 | |
|
|
1633 | Method 3: If the module to be embedded supports explicit event |
|
|
1634 | notification (adns does), you can also make use of the actual watcher |
|
|
1635 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1636 | |
|
|
1637 | static void |
|
|
1638 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1639 | { |
|
|
1640 | adns_state ads = (adns_state)w->data; |
|
|
1641 | update_now (EV_A); |
|
|
1642 | |
|
|
1643 | adns_processtimeouts (ads, &tv_now); |
|
|
1644 | } |
|
|
1645 | |
|
|
1646 | static void |
|
|
1647 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1648 | { |
|
|
1649 | adns_state ads = (adns_state)w->data; |
|
|
1650 | update_now (EV_A); |
|
|
1651 | |
|
|
1652 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1653 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1654 | } |
|
|
1655 | |
|
|
1656 | // do not ever call adns_afterpoll |
|
|
1657 | |
|
|
1658 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1659 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1660 | their poll function. The drawback with this solution is that the main |
|
|
1661 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1662 | this. |
|
|
1663 | |
|
|
1664 | static gint |
|
|
1665 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1666 | { |
|
|
1667 | int got_events = 0; |
|
|
1668 | |
|
|
1669 | for (n = 0; n < nfds; ++n) |
|
|
1670 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1671 | |
|
|
1672 | if (timeout >= 0) |
|
|
1673 | // create/start timer |
|
|
1674 | |
|
|
1675 | // poll |
|
|
1676 | ev_loop (EV_A_ 0); |
|
|
1677 | |
|
|
1678 | // stop timer again |
|
|
1679 | if (timeout >= 0) |
|
|
1680 | ev_timer_stop (EV_A_ &to); |
|
|
1681 | |
|
|
1682 | // stop io watchers again - their callbacks should have set |
|
|
1683 | for (n = 0; n < nfds; ++n) |
|
|
1684 | ev_io_stop (EV_A_ iow [n]); |
|
|
1685 | |
|
|
1686 | return got_events; |
1425 | } |
1687 | } |
1426 | |
1688 | |
1427 | |
1689 | |
1428 | =head2 C<ev_embed> - when one backend isn't enough... |
1690 | =head2 C<ev_embed> - when one backend isn't enough... |
1429 | |
1691 | |
… | |
… | |
1493 | ev_embed_start (loop_hi, &embed); |
1755 | ev_embed_start (loop_hi, &embed); |
1494 | } |
1756 | } |
1495 | else |
1757 | else |
1496 | loop_lo = loop_hi; |
1758 | loop_lo = loop_hi; |
1497 | |
1759 | |
|
|
1760 | =head3 Watcher-Specific Functions and Data Members |
|
|
1761 | |
1498 | =over 4 |
1762 | =over 4 |
1499 | |
1763 | |
1500 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1764 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1501 | |
1765 | |
1502 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
1766 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
… | |
… | |
1528 | event loop blocks next and before C<ev_check> watchers are being called, |
1792 | event loop blocks next and before C<ev_check> watchers are being called, |
1529 | and only in the child after the fork. If whoever good citizen calling |
1793 | and only in the child after the fork. If whoever good citizen calling |
1530 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1794 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1531 | handlers will be invoked, too, of course. |
1795 | handlers will be invoked, too, of course. |
1532 | |
1796 | |
|
|
1797 | =head3 Watcher-Specific Functions and Data Members |
|
|
1798 | |
1533 | =over 4 |
1799 | =over 4 |
1534 | |
1800 | |
1535 | =item ev_fork_init (ev_signal *, callback) |
1801 | =item ev_fork_init (ev_signal *, callback) |
1536 | |
1802 | |
1537 | Initialises and configures the fork watcher - it has no parameters of any |
1803 | Initialises and configures the fork watcher - it has no parameters of any |
… | |
… | |
1633 | |
1899 | |
1634 | To use it, |
1900 | To use it, |
1635 | |
1901 | |
1636 | #include <ev++.h> |
1902 | #include <ev++.h> |
1637 | |
1903 | |
1638 | (it is not installed by default). This automatically includes F<ev.h> |
1904 | This automatically includes F<ev.h> and puts all of its definitions (many |
1639 | and puts all of its definitions (many of them macros) into the global |
1905 | of them macros) into the global namespace. All C++ specific things are |
1640 | namespace. All C++ specific things are put into the C<ev> namespace. |
1906 | put into the C<ev> namespace. It should support all the same embedding |
|
|
1907 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1641 | |
1908 | |
1642 | It should support all the same embedding options as F<ev.h>, most notably |
1909 | Care has been taken to keep the overhead low. The only data member the C++ |
1643 | C<EV_MULTIPLICITY>. |
1910 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
1911 | that the watcher is associated with (or no additional members at all if |
|
|
1912 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
1913 | |
|
|
1914 | Currently, functions, and static and non-static member functions can be |
|
|
1915 | used as callbacks. Other types should be easy to add as long as they only |
|
|
1916 | need one additional pointer for context. If you need support for other |
|
|
1917 | types of functors please contact the author (preferably after implementing |
|
|
1918 | it). |
1644 | |
1919 | |
1645 | Here is a list of things available in the C<ev> namespace: |
1920 | Here is a list of things available in the C<ev> namespace: |
1646 | |
1921 | |
1647 | =over 4 |
1922 | =over 4 |
1648 | |
1923 | |
… | |
… | |
1664 | |
1939 | |
1665 | All of those classes have these methods: |
1940 | All of those classes have these methods: |
1666 | |
1941 | |
1667 | =over 4 |
1942 | =over 4 |
1668 | |
1943 | |
1669 | =item ev::TYPE::TYPE (object *, object::method *) |
1944 | =item ev::TYPE::TYPE () |
1670 | |
1945 | |
1671 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
1946 | =item ev::TYPE::TYPE (struct ev_loop *) |
1672 | |
1947 | |
1673 | =item ev::TYPE::~TYPE |
1948 | =item ev::TYPE::~TYPE |
1674 | |
1949 | |
1675 | The constructor takes a pointer to an object and a method pointer to |
1950 | The constructor (optionally) takes an event loop to associate the watcher |
1676 | the event handler callback to call in this class. The constructor calls |
1951 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1677 | C<ev_init> for you, which means you have to call the C<set> method |
1952 | |
1678 | before starting it. If you do not specify a loop then the constructor |
1953 | The constructor calls C<ev_init> for you, which means you have to call the |
1679 | automatically associates the default loop with this watcher. |
1954 | C<set> method before starting it. |
|
|
1955 | |
|
|
1956 | It will not set a callback, however: You have to call the templated C<set> |
|
|
1957 | method to set a callback before you can start the watcher. |
|
|
1958 | |
|
|
1959 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
1960 | not allow explicit template arguments for constructors). |
1680 | |
1961 | |
1681 | The destructor automatically stops the watcher if it is active. |
1962 | The destructor automatically stops the watcher if it is active. |
|
|
1963 | |
|
|
1964 | =item w->set<class, &class::method> (object *) |
|
|
1965 | |
|
|
1966 | This method sets the callback method to call. The method has to have a |
|
|
1967 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
1968 | first argument and the C<revents> as second. The object must be given as |
|
|
1969 | parameter and is stored in the C<data> member of the watcher. |
|
|
1970 | |
|
|
1971 | This method synthesizes efficient thunking code to call your method from |
|
|
1972 | the C callback that libev requires. If your compiler can inline your |
|
|
1973 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
1974 | your compiler is good :), then the method will be fully inlined into the |
|
|
1975 | thunking function, making it as fast as a direct C callback. |
|
|
1976 | |
|
|
1977 | Example: simple class declaration and watcher initialisation |
|
|
1978 | |
|
|
1979 | struct myclass |
|
|
1980 | { |
|
|
1981 | void io_cb (ev::io &w, int revents) { } |
|
|
1982 | } |
|
|
1983 | |
|
|
1984 | myclass obj; |
|
|
1985 | ev::io iow; |
|
|
1986 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
1987 | |
|
|
1988 | =item w->set<function> (void *data = 0) |
|
|
1989 | |
|
|
1990 | Also sets a callback, but uses a static method or plain function as |
|
|
1991 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
1992 | C<data> member and is free for you to use. |
|
|
1993 | |
|
|
1994 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
1995 | |
|
|
1996 | See the method-C<set> above for more details. |
|
|
1997 | |
|
|
1998 | Example: |
|
|
1999 | |
|
|
2000 | static void io_cb (ev::io &w, int revents) { } |
|
|
2001 | iow.set <io_cb> (); |
1682 | |
2002 | |
1683 | =item w->set (struct ev_loop *) |
2003 | =item w->set (struct ev_loop *) |
1684 | |
2004 | |
1685 | Associates a different C<struct ev_loop> with this watcher. You can only |
2005 | Associates a different C<struct ev_loop> with this watcher. You can only |
1686 | do this when the watcher is inactive (and not pending either). |
2006 | do this when the watcher is inactive (and not pending either). |
1687 | |
2007 | |
1688 | =item w->set ([args]) |
2008 | =item w->set ([args]) |
1689 | |
2009 | |
1690 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
2010 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1691 | called at least once. Unlike the C counterpart, an active watcher gets |
2011 | called at least once. Unlike the C counterpart, an active watcher gets |
1692 | automatically stopped and restarted. |
2012 | automatically stopped and restarted when reconfiguring it with this |
|
|
2013 | method. |
1693 | |
2014 | |
1694 | =item w->start () |
2015 | =item w->start () |
1695 | |
2016 | |
1696 | Starts the watcher. Note that there is no C<loop> argument as the |
2017 | Starts the watcher. Note that there is no C<loop> argument, as the |
1697 | constructor already takes the loop. |
2018 | constructor already stores the event loop. |
1698 | |
2019 | |
1699 | =item w->stop () |
2020 | =item w->stop () |
1700 | |
2021 | |
1701 | Stops the watcher if it is active. Again, no C<loop> argument. |
2022 | Stops the watcher if it is active. Again, no C<loop> argument. |
1702 | |
2023 | |
… | |
… | |
1727 | |
2048 | |
1728 | myclass (); |
2049 | myclass (); |
1729 | } |
2050 | } |
1730 | |
2051 | |
1731 | myclass::myclass (int fd) |
2052 | myclass::myclass (int fd) |
1732 | : io (this, &myclass::io_cb), |
|
|
1733 | idle (this, &myclass::idle_cb) |
|
|
1734 | { |
2053 | { |
|
|
2054 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2055 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2056 | |
1735 | io.start (fd, ev::READ); |
2057 | io.start (fd, ev::READ); |
1736 | } |
2058 | } |
1737 | |
2059 | |
1738 | |
2060 | |
1739 | =head1 MACRO MAGIC |
2061 | =head1 MACRO MAGIC |
1740 | |
2062 | |
1741 | Libev can be compiled with a variety of options, the most fundemantal is |
2063 | Libev can be compiled with a variety of options, the most fundemantal is |
1742 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
2064 | C<EV_MULTIPLICITY>. This option determines whether (most) functions and |
1743 | callbacks have an initial C<struct ev_loop *> argument. |
2065 | callbacks have an initial C<struct ev_loop *> argument. |
1744 | |
2066 | |
1745 | To make it easier to write programs that cope with either variant, the |
2067 | To make it easier to write programs that cope with either variant, the |
1746 | following macros are defined: |
2068 | following macros are defined: |
1747 | |
2069 | |
… | |
… | |
1780 | Similar to the other two macros, this gives you the value of the default |
2102 | Similar to the other two macros, this gives you the value of the default |
1781 | loop, if multiple loops are supported ("ev loop default"). |
2103 | loop, if multiple loops are supported ("ev loop default"). |
1782 | |
2104 | |
1783 | =back |
2105 | =back |
1784 | |
2106 | |
1785 | Example: Declare and initialise a check watcher, working regardless of |
2107 | Example: Declare and initialise a check watcher, utilising the above |
1786 | wether multiple loops are supported or not. |
2108 | macros so it will work regardless of whether multiple loops are supported |
|
|
2109 | or not. |
1787 | |
2110 | |
1788 | static void |
2111 | static void |
1789 | check_cb (EV_P_ ev_timer *w, int revents) |
2112 | check_cb (EV_P_ ev_timer *w, int revents) |
1790 | { |
2113 | { |
1791 | ev_check_stop (EV_A_ w); |
2114 | ev_check_stop (EV_A_ w); |
… | |
… | |
1793 | |
2116 | |
1794 | ev_check check; |
2117 | ev_check check; |
1795 | ev_check_init (&check, check_cb); |
2118 | ev_check_init (&check, check_cb); |
1796 | ev_check_start (EV_DEFAULT_ &check); |
2119 | ev_check_start (EV_DEFAULT_ &check); |
1797 | ev_loop (EV_DEFAULT_ 0); |
2120 | ev_loop (EV_DEFAULT_ 0); |
1798 | |
|
|
1799 | |
2121 | |
1800 | =head1 EMBEDDING |
2122 | =head1 EMBEDDING |
1801 | |
2123 | |
1802 | Libev can (and often is) directly embedded into host |
2124 | Libev can (and often is) directly embedded into host |
1803 | applications. Examples of applications that embed it include the Deliantra |
2125 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
1843 | ev_vars.h |
2165 | ev_vars.h |
1844 | ev_wrap.h |
2166 | ev_wrap.h |
1845 | |
2167 | |
1846 | ev_win32.c required on win32 platforms only |
2168 | ev_win32.c required on win32 platforms only |
1847 | |
2169 | |
1848 | ev_select.c only when select backend is enabled (which is by default) |
2170 | ev_select.c only when select backend is enabled (which is enabled by default) |
1849 | ev_poll.c only when poll backend is enabled (disabled by default) |
2171 | ev_poll.c only when poll backend is enabled (disabled by default) |
1850 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2172 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1851 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2173 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1852 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
2174 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1853 | |
2175 | |
… | |
… | |
1978 | |
2300 | |
1979 | =item EV_USE_DEVPOLL |
2301 | =item EV_USE_DEVPOLL |
1980 | |
2302 | |
1981 | reserved for future expansion, works like the USE symbols above. |
2303 | reserved for future expansion, works like the USE symbols above. |
1982 | |
2304 | |
|
|
2305 | =item EV_USE_INOTIFY |
|
|
2306 | |
|
|
2307 | If defined to be C<1>, libev will compile in support for the Linux inotify |
|
|
2308 | interface to speed up C<ev_stat> watchers. Its actual availability will |
|
|
2309 | be detected at runtime. |
|
|
2310 | |
1983 | =item EV_H |
2311 | =item EV_H |
1984 | |
2312 | |
1985 | The name of the F<ev.h> header file used to include it. The default if |
2313 | The name of the F<ev.h> header file used to include it. The default if |
1986 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2314 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
1987 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2315 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
… | |
… | |
2010 | will have the C<struct ev_loop *> as first argument, and you can create |
2338 | will have the C<struct ev_loop *> as first argument, and you can create |
2011 | additional independent event loops. Otherwise there will be no support |
2339 | additional independent event loops. Otherwise there will be no support |
2012 | for multiple event loops and there is no first event loop pointer |
2340 | for multiple event loops and there is no first event loop pointer |
2013 | argument. Instead, all functions act on the single default loop. |
2341 | argument. Instead, all functions act on the single default loop. |
2014 | |
2342 | |
|
|
2343 | =item EV_MINPRI |
|
|
2344 | |
|
|
2345 | =item EV_MAXPRI |
|
|
2346 | |
|
|
2347 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2348 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2349 | provide for more priorities by overriding those symbols (usually defined |
|
|
2350 | to be C<-2> and C<2>, respectively). |
|
|
2351 | |
|
|
2352 | When doing priority-based operations, libev usually has to linearly search |
|
|
2353 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2354 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2355 | fine. |
|
|
2356 | |
|
|
2357 | If your embedding app does not need any priorities, defining these both to |
|
|
2358 | C<0> will save some memory and cpu. |
|
|
2359 | |
2015 | =item EV_PERIODIC_ENABLE |
2360 | =item EV_PERIODIC_ENABLE |
2016 | |
2361 | |
2017 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2362 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2018 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2363 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2019 | code. |
2364 | code. |
2020 | |
2365 | |
|
|
2366 | =item EV_IDLE_ENABLE |
|
|
2367 | |
|
|
2368 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
2369 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2370 | code. |
|
|
2371 | |
2021 | =item EV_EMBED_ENABLE |
2372 | =item EV_EMBED_ENABLE |
2022 | |
2373 | |
2023 | If undefined or defined to be C<1>, then embed watchers are supported. If |
2374 | If undefined or defined to be C<1>, then embed watchers are supported. If |
2024 | defined to be C<0>, then they are not. |
2375 | defined to be C<0>, then they are not. |
2025 | |
2376 | |
… | |
… | |
2042 | =item EV_PID_HASHSIZE |
2393 | =item EV_PID_HASHSIZE |
2043 | |
2394 | |
2044 | C<ev_child> watchers use a small hash table to distribute workload by |
2395 | C<ev_child> watchers use a small hash table to distribute workload by |
2045 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
2396 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
2046 | than enough. If you need to manage thousands of children you might want to |
2397 | than enough. If you need to manage thousands of children you might want to |
2047 | increase this value. |
2398 | increase this value (I<must> be a power of two). |
|
|
2399 | |
|
|
2400 | =item EV_INOTIFY_HASHSIZE |
|
|
2401 | |
|
|
2402 | C<ev_staz> watchers use a small hash table to distribute workload by |
|
|
2403 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
|
|
2404 | usually more than enough. If you need to manage thousands of C<ev_stat> |
|
|
2405 | watchers you might want to increase this value (I<must> be a power of |
|
|
2406 | two). |
2048 | |
2407 | |
2049 | =item EV_COMMON |
2408 | =item EV_COMMON |
2050 | |
2409 | |
2051 | By default, all watchers have a C<void *data> member. By redefining |
2410 | By default, all watchers have a C<void *data> member. By redefining |
2052 | this macro to a something else you can include more and other types of |
2411 | this macro to a something else you can include more and other types of |
… | |
… | |
2081 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2440 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2082 | will be compiled. It is pretty complex because it provides its own header |
2441 | will be compiled. It is pretty complex because it provides its own header |
2083 | file. |
2442 | file. |
2084 | |
2443 | |
2085 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2444 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2086 | that everybody includes and which overrides some autoconf choices: |
2445 | that everybody includes and which overrides some configure choices: |
2087 | |
2446 | |
|
|
2447 | #define EV_MINIMAL 1 |
2088 | #define EV_USE_POLL 0 |
2448 | #define EV_USE_POLL 0 |
2089 | #define EV_MULTIPLICITY 0 |
2449 | #define EV_MULTIPLICITY 0 |
2090 | #define EV_PERIODICS 0 |
2450 | #define EV_PERIODIC_ENABLE 0 |
|
|
2451 | #define EV_STAT_ENABLE 0 |
|
|
2452 | #define EV_FORK_ENABLE 0 |
2091 | #define EV_CONFIG_H <config.h> |
2453 | #define EV_CONFIG_H <config.h> |
|
|
2454 | #define EV_MINPRI 0 |
|
|
2455 | #define EV_MAXPRI 0 |
2092 | |
2456 | |
2093 | #include "ev++.h" |
2457 | #include "ev++.h" |
2094 | |
2458 | |
2095 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2459 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2096 | |
2460 | |
… | |
… | |
2102 | |
2466 | |
2103 | In this section the complexities of (many of) the algorithms used inside |
2467 | In this section the complexities of (many of) the algorithms used inside |
2104 | libev will be explained. For complexity discussions about backends see the |
2468 | libev will be explained. For complexity discussions about backends see the |
2105 | documentation for C<ev_default_init>. |
2469 | documentation for C<ev_default_init>. |
2106 | |
2470 | |
|
|
2471 | All of the following are about amortised time: If an array needs to be |
|
|
2472 | extended, libev needs to realloc and move the whole array, but this |
|
|
2473 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2474 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2475 | it is much faster and asymptotically approaches constant time. |
|
|
2476 | |
2107 | =over 4 |
2477 | =over 4 |
2108 | |
2478 | |
2109 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2479 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2110 | |
2480 | |
|
|
2481 | This means that, when you have a watcher that triggers in one hour and |
|
|
2482 | there are 100 watchers that would trigger before that then inserting will |
|
|
2483 | have to skip those 100 watchers. |
|
|
2484 | |
2111 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2485 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2112 | |
2486 | |
|
|
2487 | That means that for changing a timer costs less than removing/adding them |
|
|
2488 | as only the relative motion in the event queue has to be paid for. |
|
|
2489 | |
2113 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2490 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2114 | |
2491 | |
|
|
2492 | These just add the watcher into an array or at the head of a list. |
2115 | =item Stopping check/prepare/idle watchers: O(1) |
2493 | =item Stopping check/prepare/idle watchers: O(1) |
2116 | |
2494 | |
2117 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16)) |
2495 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
|
|
2496 | |
|
|
2497 | These watchers are stored in lists then need to be walked to find the |
|
|
2498 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2499 | have many watchers waiting for the same fd or signal). |
2118 | |
2500 | |
2119 | =item Finding the next timer per loop iteration: O(1) |
2501 | =item Finding the next timer per loop iteration: O(1) |
2120 | |
2502 | |
2121 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2503 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2122 | |
2504 | |
|
|
2505 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2506 | libev to recalculate its status (and possibly tell the kernel). |
|
|
2507 | |
2123 | =item Activating one watcher: O(1) |
2508 | =item Activating one watcher: O(1) |
2124 | |
2509 | |
|
|
2510 | =item Priority handling: O(number_of_priorities) |
|
|
2511 | |
|
|
2512 | Priorities are implemented by allocating some space for each |
|
|
2513 | priority. When doing priority-based operations, libev usually has to |
|
|
2514 | linearly search all the priorities. |
|
|
2515 | |
2125 | =back |
2516 | =back |
2126 | |
2517 | |
2127 | |
2518 | |
2128 | =head1 AUTHOR |
2519 | =head1 AUTHOR |
2129 | |
2520 | |