… | |
… | |
26 | puts ("stdin ready"); |
26 | puts ("stdin ready"); |
27 | // for one-shot events, one must manually stop the watcher |
27 | // for one-shot events, one must manually stop the watcher |
28 | // with its corresponding stop function. |
28 | // with its corresponding stop function. |
29 | ev_io_stop (EV_A_ w); |
29 | ev_io_stop (EV_A_ w); |
30 | |
30 | |
31 | // this causes all nested ev_loop's to stop iterating |
31 | // this causes all nested ev_run's to stop iterating |
32 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
32 | ev_break (EV_A_ EVBREAK_ALL); |
33 | } |
33 | } |
34 | |
34 | |
35 | // another callback, this time for a time-out |
35 | // another callback, this time for a time-out |
36 | static void |
36 | static void |
37 | timeout_cb (EV_P_ ev_timer *w, int revents) |
37 | timeout_cb (EV_P_ ev_timer *w, int revents) |
38 | { |
38 | { |
39 | puts ("timeout"); |
39 | puts ("timeout"); |
40 | // this causes the innermost ev_loop to stop iterating |
40 | // this causes the innermost ev_run to stop iterating |
41 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
41 | ev_break (EV_A_ EVBREAK_ONE); |
42 | } |
42 | } |
43 | |
43 | |
44 | int |
44 | int |
45 | main (void) |
45 | main (void) |
46 | { |
46 | { |
47 | // use the default event loop unless you have special needs |
47 | // use the default event loop unless you have special needs |
48 | struct ev_loop *loop = ev_default_loop (0); |
48 | struct ev_loop *loop = EV_DEFAULT; |
49 | |
49 | |
50 | // initialise an io watcher, then start it |
50 | // initialise an io watcher, then start it |
51 | // this one will watch for stdin to become readable |
51 | // this one will watch for stdin to become readable |
52 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
52 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
53 | ev_io_start (loop, &stdin_watcher); |
53 | ev_io_start (loop, &stdin_watcher); |
… | |
… | |
56 | // simple non-repeating 5.5 second timeout |
56 | // simple non-repeating 5.5 second timeout |
57 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
57 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
58 | ev_timer_start (loop, &timeout_watcher); |
58 | ev_timer_start (loop, &timeout_watcher); |
59 | |
59 | |
60 | // now wait for events to arrive |
60 | // now wait for events to arrive |
61 | ev_loop (loop, 0); |
61 | ev_run (loop, 0); |
62 | |
62 | |
63 | // unloop was called, so exit |
63 | // unloop was called, so exit |
64 | return 0; |
64 | return 0; |
65 | } |
65 | } |
66 | |
66 | |
… | |
… | |
75 | While this document tries to be as complete as possible in documenting |
75 | While this document tries to be as complete as possible in documenting |
76 | libev, its usage and the rationale behind its design, it is not a tutorial |
76 | libev, its usage and the rationale behind its design, it is not a tutorial |
77 | on event-based programming, nor will it introduce event-based programming |
77 | on event-based programming, nor will it introduce event-based programming |
78 | with libev. |
78 | with libev. |
79 | |
79 | |
80 | Familarity with event based programming techniques in general is assumed |
80 | Familiarity with event based programming techniques in general is assumed |
81 | throughout this document. |
81 | throughout this document. |
82 | |
82 | |
83 | =head1 ABOUT LIBEV |
83 | =head1 ABOUT LIBEV |
84 | |
84 | |
85 | Libev is an event loop: you register interest in certain events (such as a |
85 | Libev is an event loop: you register interest in certain events (such as a |
… | |
… | |
124 | this argument. |
124 | this argument. |
125 | |
125 | |
126 | =head2 TIME REPRESENTATION |
126 | =head2 TIME REPRESENTATION |
127 | |
127 | |
128 | Libev represents time as a single floating point number, representing |
128 | Libev represents time as a single floating point number, representing |
129 | the (fractional) number of seconds since the (POSIX) epoch (somewhere |
129 | the (fractional) number of seconds since the (POSIX) epoch (in practice |
130 | near the beginning of 1970, details are complicated, don't ask). This |
130 | somewhere near the beginning of 1970, details are complicated, don't |
131 | type is called C<ev_tstamp>, which is what you should use too. It usually |
131 | ask). This type is called C<ev_tstamp>, which is what you should use |
132 | aliases to the C<double> type in C. When you need to do any calculations |
132 | too. It usually aliases to the C<double> type in C. When you need to do |
133 | on it, you should treat it as some floating point value. Unlike the name |
133 | any calculations on it, you should treat it as some floating point value. |
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134 | |
134 | component C<stamp> might indicate, it is also used for time differences |
135 | Unlike the name component C<stamp> might indicate, it is also used for |
135 | throughout libev. |
136 | time differences (e.g. delays) throughout libev. |
136 | |
137 | |
137 | =head1 ERROR HANDLING |
138 | =head1 ERROR HANDLING |
138 | |
139 | |
139 | Libev knows three classes of errors: operating system errors, usage errors |
140 | Libev knows three classes of errors: operating system errors, usage errors |
140 | and internal errors (bugs). |
141 | and internal errors (bugs). |
… | |
… | |
164 | |
165 | |
165 | =item ev_tstamp ev_time () |
166 | =item ev_tstamp ev_time () |
166 | |
167 | |
167 | Returns the current time as libev would use it. Please note that the |
168 | Returns the current time as libev would use it. Please note that the |
168 | C<ev_now> function is usually faster and also often returns the timestamp |
169 | C<ev_now> function is usually faster and also often returns the timestamp |
169 | you actually want to know. |
170 | you actually want to know. Also interesting is the combination of |
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171 | C<ev_update_now> and C<ev_now>. |
170 | |
172 | |
171 | =item ev_sleep (ev_tstamp interval) |
173 | =item ev_sleep (ev_tstamp interval) |
172 | |
174 | |
173 | Sleep for the given interval: The current thread will be blocked until |
175 | Sleep for the given interval: The current thread will be blocked until |
174 | either it is interrupted or the given time interval has passed. Basically |
176 | either it is interrupted or the given time interval has passed. Basically |
… | |
… | |
191 | as this indicates an incompatible change. Minor versions are usually |
193 | as this indicates an incompatible change. Minor versions are usually |
192 | compatible to older versions, so a larger minor version alone is usually |
194 | compatible to older versions, so a larger minor version alone is usually |
193 | not a problem. |
195 | not a problem. |
194 | |
196 | |
195 | Example: Make sure we haven't accidentally been linked against the wrong |
197 | Example: Make sure we haven't accidentally been linked against the wrong |
196 | version. |
198 | version (note, however, that this will not detect other ABI mismatches, |
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199 | such as LFS or reentrancy). |
197 | |
200 | |
198 | assert (("libev version mismatch", |
201 | assert (("libev version mismatch", |
199 | ev_version_major () == EV_VERSION_MAJOR |
202 | ev_version_major () == EV_VERSION_MAJOR |
200 | && ev_version_minor () >= EV_VERSION_MINOR)); |
203 | && ev_version_minor () >= EV_VERSION_MINOR)); |
201 | |
204 | |
… | |
… | |
212 | assert (("sorry, no epoll, no sex", |
215 | assert (("sorry, no epoll, no sex", |
213 | ev_supported_backends () & EVBACKEND_EPOLL)); |
216 | ev_supported_backends () & EVBACKEND_EPOLL)); |
214 | |
217 | |
215 | =item unsigned int ev_recommended_backends () |
218 | =item unsigned int ev_recommended_backends () |
216 | |
219 | |
217 | Return the set of all backends compiled into this binary of libev and also |
220 | Return the set of all backends compiled into this binary of libev and |
218 | recommended for this platform. This set is often smaller than the one |
221 | also recommended for this platform, meaning it will work for most file |
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222 | descriptor types. This set is often smaller than the one returned by |
219 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
223 | C<ev_supported_backends>, as for example kqueue is broken on most BSDs |
220 | most BSDs and will not be auto-detected unless you explicitly request it |
224 | and will not be auto-detected unless you explicitly request it (assuming |
221 | (assuming you know what you are doing). This is the set of backends that |
225 | you know what you are doing). This is the set of backends that libev will |
222 | libev will probe for if you specify no backends explicitly. |
226 | probe for if you specify no backends explicitly. |
223 | |
227 | |
224 | =item unsigned int ev_embeddable_backends () |
228 | =item unsigned int ev_embeddable_backends () |
225 | |
229 | |
226 | Returns the set of backends that are embeddable in other event loops. This |
230 | Returns the set of backends that are embeddable in other event loops. This |
227 | is the theoretical, all-platform, value. To find which backends |
231 | value is platform-specific but can include backends not available on the |
228 | might be supported on the current system, you would need to look at |
232 | current system. To find which embeddable backends might be supported on |
229 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
233 | the current system, you would need to look at C<ev_embeddable_backends () |
230 | recommended ones. |
234 | & ev_supported_backends ()>, likewise for recommended ones. |
231 | |
235 | |
232 | See the description of C<ev_embed> watchers for more info. |
236 | See the description of C<ev_embed> watchers for more info. |
233 | |
237 | |
234 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT] |
238 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT] |
235 | |
239 | |
… | |
… | |
289 | ... |
293 | ... |
290 | ev_set_syserr_cb (fatal_error); |
294 | ev_set_syserr_cb (fatal_error); |
291 | |
295 | |
292 | =back |
296 | =back |
293 | |
297 | |
294 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
298 | =head1 FUNCTIONS CONTROLLING EVENT LOOPS |
295 | |
299 | |
296 | An event loop is described by a C<struct ev_loop *> (the C<struct> |
300 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
297 | is I<not> optional in this case, as there is also an C<ev_loop> |
301 | I<not> optional in this case unless libev 3 compatibility is disabled, as |
298 | I<function>). |
302 | libev 3 had an C<ev_loop> function colliding with the struct name). |
299 | |
303 | |
300 | The library knows two types of such loops, the I<default> loop, which |
304 | The library knows two types of such loops, the I<default> loop, which |
301 | supports signals and child events, and dynamically created loops which do |
305 | supports signals and child events, and dynamically created event loops |
302 | not. |
306 | which do not. |
303 | |
307 | |
304 | =over 4 |
308 | =over 4 |
305 | |
309 | |
306 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
310 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
307 | |
311 | |
308 | This will initialise the default event loop if it hasn't been initialised |
312 | This returns the "default" event loop object, which is what you should |
309 | yet and return it. If the default loop could not be initialised, returns |
313 | normally use when you just need "the event loop". Event loop objects and |
310 | false. If it already was initialised it simply returns it (and ignores the |
314 | the C<flags> parameter are described in more detail in the entry for |
311 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
315 | C<ev_loop_new>. |
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316 | |
|
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317 | If the default loop is already initialised then this function simply |
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318 | returns it (and ignores the flags. If that is troubling you, check |
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319 | C<ev_backend ()> afterwards). Otherwise it will create it with the given |
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320 | flags, which should almost always be C<0>, unless the caller is also the |
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321 | one calling C<ev_run> or otherwise qualifies as "the main program". |
312 | |
322 | |
313 | If you don't know what event loop to use, use the one returned from this |
323 | If you don't know what event loop to use, use the one returned from this |
314 | function. |
324 | function (or via the C<EV_DEFAULT> macro). |
315 | |
325 | |
316 | Note that this function is I<not> thread-safe, so if you want to use it |
326 | Note that this function is I<not> thread-safe, so if you want to use it |
317 | from multiple threads, you have to lock (note also that this is unlikely, |
327 | from multiple threads, you have to employ some kind of mutex (note also |
318 | as loops cannot be shared easily between threads anyway). |
328 | that this case is unlikely, as loops cannot be shared easily between |
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329 | threads anyway). |
319 | |
330 | |
320 | The default loop is the only loop that can handle C<ev_signal> and |
331 | The default loop is the only loop that can handle C<ev_child> watchers, |
321 | C<ev_child> watchers, and to do this, it always registers a handler |
332 | and to do this, it always registers a handler for C<SIGCHLD>. If this is |
322 | for C<SIGCHLD>. If this is a problem for your application you can either |
333 | a problem for your application you can either create a dynamic loop with |
323 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
334 | C<ev_loop_new> which doesn't do that, or you can simply overwrite the |
324 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
335 | C<SIGCHLD> signal handler I<after> calling C<ev_default_init>. |
325 | C<ev_default_init>. |
336 | |
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337 | Example: This is the most typical usage. |
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338 | |
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339 | if (!ev_default_loop (0)) |
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340 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
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341 | |
|
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342 | Example: Restrict libev to the select and poll backends, and do not allow |
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343 | environment settings to be taken into account: |
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344 | |
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345 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
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346 | |
|
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347 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
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348 | |
|
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349 | This will create and initialise a new event loop object. If the loop |
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350 | could not be initialised, returns false. |
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351 | |
|
|
352 | Note that this function I<is> thread-safe, and one common way to use |
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353 | libev with threads is indeed to create one loop per thread, and using the |
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354 | default loop in the "main" or "initial" thread. |
326 | |
355 | |
327 | The flags argument can be used to specify special behaviour or specific |
356 | The flags argument can be used to specify special behaviour or specific |
328 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
357 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
329 | |
358 | |
330 | The following flags are supported: |
359 | The following flags are supported: |
… | |
… | |
345 | useful to try out specific backends to test their performance, or to work |
374 | useful to try out specific backends to test their performance, or to work |
346 | around bugs. |
375 | around bugs. |
347 | |
376 | |
348 | =item C<EVFLAG_FORKCHECK> |
377 | =item C<EVFLAG_FORKCHECK> |
349 | |
378 | |
350 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
379 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
351 | a fork, you can also make libev check for a fork in each iteration by |
380 | make libev check for a fork in each iteration by enabling this flag. |
352 | enabling this flag. |
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353 | |
381 | |
354 | This works by calling C<getpid ()> on every iteration of the loop, |
382 | This works by calling C<getpid ()> on every iteration of the loop, |
355 | and thus this might slow down your event loop if you do a lot of loop |
383 | and thus this might slow down your event loop if you do a lot of loop |
356 | iterations and little real work, but is usually not noticeable (on my |
384 | iterations and little real work, but is usually not noticeable (on my |
357 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
385 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
… | |
… | |
439 | of course I<doesn't>, and epoll just loves to report events for totally |
467 | of course I<doesn't>, and epoll just loves to report events for totally |
440 | I<different> file descriptors (even already closed ones, so one cannot |
468 | I<different> file descriptors (even already closed ones, so one cannot |
441 | even remove them from the set) than registered in the set (especially |
469 | even remove them from the set) than registered in the set (especially |
442 | on SMP systems). Libev tries to counter these spurious notifications by |
470 | on SMP systems). Libev tries to counter these spurious notifications by |
443 | employing an additional generation counter and comparing that against the |
471 | employing an additional generation counter and comparing that against the |
444 | events to filter out spurious ones, recreating the set when required. |
472 | events to filter out spurious ones, recreating the set when required. Last |
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473 | not least, it also refuses to work with some file descriptors which work |
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474 | perfectly fine with C<select> (files, many character devices...). |
445 | |
475 | |
446 | While stopping, setting and starting an I/O watcher in the same iteration |
476 | While stopping, setting and starting an I/O watcher in the same iteration |
447 | will result in some caching, there is still a system call per such |
477 | will result in some caching, there is still a system call per such |
448 | incident (because the same I<file descriptor> could point to a different |
478 | incident (because the same I<file descriptor> could point to a different |
449 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
479 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
… | |
… | |
547 | If one or more of the backend flags are or'ed into the flags value, |
577 | If one or more of the backend flags are or'ed into the flags value, |
548 | then only these backends will be tried (in the reverse order as listed |
578 | then only these backends will be tried (in the reverse order as listed |
549 | here). If none are specified, all backends in C<ev_recommended_backends |
579 | here). If none are specified, all backends in C<ev_recommended_backends |
550 | ()> will be tried. |
580 | ()> will be tried. |
551 | |
581 | |
552 | Example: This is the most typical usage. |
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|
553 | |
|
|
554 | if (!ev_default_loop (0)) |
|
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555 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
556 | |
|
|
557 | Example: Restrict libev to the select and poll backends, and do not allow |
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558 | environment settings to be taken into account: |
|
|
559 | |
|
|
560 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
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561 | |
|
|
562 | Example: Use whatever libev has to offer, but make sure that kqueue is |
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563 | used if available (warning, breaks stuff, best use only with your own |
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564 | private event loop and only if you know the OS supports your types of |
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565 | fds): |
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566 | |
|
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567 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
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568 | |
|
|
569 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
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|
570 | |
|
|
571 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
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572 | always distinct from the default loop. Unlike the default loop, it cannot |
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573 | handle signal and child watchers, and attempts to do so will be greeted by |
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574 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
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575 | |
|
|
576 | Note that this function I<is> thread-safe, and the recommended way to use |
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|
577 | libev with threads is indeed to create one loop per thread, and using the |
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578 | default loop in the "main" or "initial" thread. |
|
|
579 | |
|
|
580 | Example: Try to create a event loop that uses epoll and nothing else. |
582 | Example: Try to create a event loop that uses epoll and nothing else. |
581 | |
583 | |
582 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
584 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
583 | if (!epoller) |
585 | if (!epoller) |
584 | fatal ("no epoll found here, maybe it hides under your chair"); |
586 | fatal ("no epoll found here, maybe it hides under your chair"); |
585 | |
587 | |
|
|
588 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
589 | used if available. |
|
|
590 | |
|
|
591 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
592 | |
586 | =item ev_default_destroy () |
593 | =item ev_loop_destroy (loop) |
587 | |
594 | |
588 | Destroys the default loop again (frees all memory and kernel state |
595 | Destroys an event loop object (frees all memory and kernel state |
589 | etc.). None of the active event watchers will be stopped in the normal |
596 | etc.). None of the active event watchers will be stopped in the normal |
590 | sense, so e.g. C<ev_is_active> might still return true. It is your |
597 | sense, so e.g. C<ev_is_active> might still return true. It is your |
591 | responsibility to either stop all watchers cleanly yourself I<before> |
598 | responsibility to either stop all watchers cleanly yourself I<before> |
592 | calling this function, or cope with the fact afterwards (which is usually |
599 | calling this function, or cope with the fact afterwards (which is usually |
593 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
600 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
… | |
… | |
595 | |
602 | |
596 | Note that certain global state, such as signal state (and installed signal |
603 | Note that certain global state, such as signal state (and installed signal |
597 | handlers), will not be freed by this function, and related watchers (such |
604 | handlers), will not be freed by this function, and related watchers (such |
598 | as signal and child watchers) would need to be stopped manually. |
605 | as signal and child watchers) would need to be stopped manually. |
599 | |
606 | |
600 | In general it is not advisable to call this function except in the |
607 | This function is normally used on loop objects allocated by |
601 | rare occasion where you really need to free e.g. the signal handling |
608 | C<ev_loop_new>, but it can also be used on the default loop returned by |
|
|
609 | C<ev_default_loop>, in which case it is not thread-safe. |
|
|
610 | |
|
|
611 | Note that it is not advisable to call this function on the default loop |
|
|
612 | except in the rare occasion where you really need to free it's resources. |
602 | pipe fds. If you need dynamically allocated loops it is better to use |
613 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
603 | C<ev_loop_new> and C<ev_loop_destroy>. |
614 | and C<ev_loop_destroy>. |
604 | |
615 | |
605 | =item ev_loop_destroy (loop) |
616 | =item ev_loop_fork (loop) |
606 | |
617 | |
607 | Like C<ev_default_destroy>, but destroys an event loop created by an |
|
|
608 | earlier call to C<ev_loop_new>. |
|
|
609 | |
|
|
610 | =item ev_default_fork () |
|
|
611 | |
|
|
612 | This function sets a flag that causes subsequent C<ev_loop> iterations |
618 | This function sets a flag that causes subsequent C<ev_run> iterations to |
613 | to reinitialise the kernel state for backends that have one. Despite the |
619 | reinitialise the kernel state for backends that have one. Despite the |
614 | name, you can call it anytime, but it makes most sense after forking, in |
620 | name, you can call it anytime, but it makes most sense after forking, in |
615 | the child process (or both child and parent, but that again makes little |
621 | the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the |
616 | sense). You I<must> call it in the child before using any of the libev |
622 | child before resuming or calling C<ev_run>. |
617 | functions, and it will only take effect at the next C<ev_loop> iteration. |
623 | |
|
|
624 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
|
|
625 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
|
|
626 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
|
|
627 | during fork. |
618 | |
628 | |
619 | On the other hand, you only need to call this function in the child |
629 | On the other hand, you only need to call this function in the child |
620 | process if and only if you want to use the event library in the child. If |
630 | process if and only if you want to use the event loop in the child. If |
621 | you just fork+exec, you don't have to call it at all. |
631 | you just fork+exec or create a new loop in the child, you don't have to |
|
|
632 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
|
|
633 | difference, but libev will usually detect this case on its own and do a |
|
|
634 | costly reset of the backend). |
622 | |
635 | |
623 | The function itself is quite fast and it's usually not a problem to call |
636 | The function itself is quite fast and it's usually not a problem to call |
624 | it just in case after a fork. To make this easy, the function will fit in |
637 | it just in case after a fork. |
625 | quite nicely into a call to C<pthread_atfork>: |
|
|
626 | |
638 | |
|
|
639 | Example: Automate calling C<ev_loop_fork> on the default loop when |
|
|
640 | using pthreads. |
|
|
641 | |
|
|
642 | static void |
|
|
643 | post_fork_child (void) |
|
|
644 | { |
|
|
645 | ev_loop_fork (EV_DEFAULT); |
|
|
646 | } |
|
|
647 | |
|
|
648 | ... |
627 | pthread_atfork (0, 0, ev_default_fork); |
649 | pthread_atfork (0, 0, post_fork_child); |
628 | |
|
|
629 | =item ev_loop_fork (loop) |
|
|
630 | |
|
|
631 | Like C<ev_default_fork>, but acts on an event loop created by |
|
|
632 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
|
|
633 | after fork that you want to re-use in the child, and how you do this is |
|
|
634 | entirely your own problem. |
|
|
635 | |
650 | |
636 | =item int ev_is_default_loop (loop) |
651 | =item int ev_is_default_loop (loop) |
637 | |
652 | |
638 | Returns true when the given loop is, in fact, the default loop, and false |
653 | Returns true when the given loop is, in fact, the default loop, and false |
639 | otherwise. |
654 | otherwise. |
640 | |
655 | |
641 | =item unsigned int ev_loop_count (loop) |
656 | =item unsigned int ev_iteration (loop) |
642 | |
657 | |
643 | Returns the count of loop iterations for the loop, which is identical to |
658 | Returns the current iteration count for the event loop, which is identical |
644 | the number of times libev did poll for new events. It starts at C<0> and |
659 | to the number of times libev did poll for new events. It starts at C<0> |
645 | happily wraps around with enough iterations. |
660 | and happily wraps around with enough iterations. |
646 | |
661 | |
647 | This value can sometimes be useful as a generation counter of sorts (it |
662 | This value can sometimes be useful as a generation counter of sorts (it |
648 | "ticks" the number of loop iterations), as it roughly corresponds with |
663 | "ticks" the number of loop iterations), as it roughly corresponds with |
649 | C<ev_prepare> and C<ev_check> calls. |
664 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
|
|
665 | prepare and check phases. |
650 | |
666 | |
651 | =item unsigned int ev_loop_depth (loop) |
667 | =item unsigned int ev_depth (loop) |
652 | |
668 | |
653 | Returns the number of times C<ev_loop> was entered minus the number of |
669 | Returns the number of times C<ev_run> was entered minus the number of |
654 | times C<ev_loop> was exited, in other words, the recursion depth. |
670 | times C<ev_run> was exited, in other words, the recursion depth. |
655 | |
671 | |
656 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
672 | Outside C<ev_run>, this number is zero. In a callback, this number is |
657 | C<1>, unless C<ev_loop> was invoked recursively (or from another thread), |
673 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
658 | in which case it is higher. |
674 | in which case it is higher. |
659 | |
675 | |
660 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
676 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread |
661 | etc.), doesn't count as exit. |
677 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
|
|
678 | ungentleman-like behaviour unless it's really convenient. |
662 | |
679 | |
663 | =item unsigned int ev_backend (loop) |
680 | =item unsigned int ev_backend (loop) |
664 | |
681 | |
665 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
682 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
666 | use. |
683 | use. |
… | |
… | |
675 | |
692 | |
676 | =item ev_now_update (loop) |
693 | =item ev_now_update (loop) |
677 | |
694 | |
678 | Establishes the current time by querying the kernel, updating the time |
695 | Establishes the current time by querying the kernel, updating the time |
679 | returned by C<ev_now ()> in the progress. This is a costly operation and |
696 | returned by C<ev_now ()> in the progress. This is a costly operation and |
680 | is usually done automatically within C<ev_loop ()>. |
697 | is usually done automatically within C<ev_run ()>. |
681 | |
698 | |
682 | This function is rarely useful, but when some event callback runs for a |
699 | This function is rarely useful, but when some event callback runs for a |
683 | very long time without entering the event loop, updating libev's idea of |
700 | very long time without entering the event loop, updating libev's idea of |
684 | the current time is a good idea. |
701 | the current time is a good idea. |
685 | |
702 | |
… | |
… | |
687 | |
704 | |
688 | =item ev_suspend (loop) |
705 | =item ev_suspend (loop) |
689 | |
706 | |
690 | =item ev_resume (loop) |
707 | =item ev_resume (loop) |
691 | |
708 | |
692 | These two functions suspend and resume a loop, for use when the loop is |
709 | These two functions suspend and resume an event loop, for use when the |
693 | not used for a while and timeouts should not be processed. |
710 | loop is not used for a while and timeouts should not be processed. |
694 | |
711 | |
695 | A typical use case would be an interactive program such as a game: When |
712 | A typical use case would be an interactive program such as a game: When |
696 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
713 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
697 | would be best to handle timeouts as if no time had actually passed while |
714 | would be best to handle timeouts as if no time had actually passed while |
698 | the program was suspended. This can be achieved by calling C<ev_suspend> |
715 | the program was suspended. This can be achieved by calling C<ev_suspend> |
… | |
… | |
700 | C<ev_resume> directly afterwards to resume timer processing. |
717 | C<ev_resume> directly afterwards to resume timer processing. |
701 | |
718 | |
702 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
719 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
703 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
720 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
704 | will be rescheduled (that is, they will lose any events that would have |
721 | will be rescheduled (that is, they will lose any events that would have |
705 | occured while suspended). |
722 | occurred while suspended). |
706 | |
723 | |
707 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
724 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
708 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
725 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
709 | without a previous call to C<ev_suspend>. |
726 | without a previous call to C<ev_suspend>. |
710 | |
727 | |
711 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
728 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
712 | event loop time (see C<ev_now_update>). |
729 | event loop time (see C<ev_now_update>). |
713 | |
730 | |
714 | =item ev_loop (loop, int flags) |
731 | =item ev_run (loop, int flags) |
715 | |
732 | |
716 | Finally, this is it, the event handler. This function usually is called |
733 | Finally, this is it, the event handler. This function usually is called |
717 | after you have initialised all your watchers and you want to start |
734 | after you have initialised all your watchers and you want to start |
718 | handling events. |
735 | handling events. It will ask the operating system for any new events, call |
|
|
736 | the watcher callbacks, an then repeat the whole process indefinitely: This |
|
|
737 | is why event loops are called I<loops>. |
719 | |
738 | |
720 | If the flags argument is specified as C<0>, it will not return until |
739 | If the flags argument is specified as C<0>, it will keep handling events |
721 | either no event watchers are active anymore or C<ev_unloop> was called. |
740 | until either no event watchers are active anymore or C<ev_break> was |
|
|
741 | called. |
722 | |
742 | |
723 | Please note that an explicit C<ev_unloop> is usually better than |
743 | Please note that an explicit C<ev_break> is usually better than |
724 | relying on all watchers to be stopped when deciding when a program has |
744 | relying on all watchers to be stopped when deciding when a program has |
725 | finished (especially in interactive programs), but having a program |
745 | finished (especially in interactive programs), but having a program |
726 | that automatically loops as long as it has to and no longer by virtue |
746 | that automatically loops as long as it has to and no longer by virtue |
727 | of relying on its watchers stopping correctly, that is truly a thing of |
747 | of relying on its watchers stopping correctly, that is truly a thing of |
728 | beauty. |
748 | beauty. |
729 | |
749 | |
730 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
750 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
731 | those events and any already outstanding ones, but will not block your |
751 | those events and any already outstanding ones, but will not wait and |
732 | process in case there are no events and will return after one iteration of |
752 | block your process in case there are no events and will return after one |
733 | the loop. |
753 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
754 | events while doing lengthy calculations, to keep the program responsive. |
734 | |
755 | |
735 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
756 | A flags value of C<EVRUN_ONCE> will look for new events (waiting if |
736 | necessary) and will handle those and any already outstanding ones. It |
757 | necessary) and will handle those and any already outstanding ones. It |
737 | will block your process until at least one new event arrives (which could |
758 | will block your process until at least one new event arrives (which could |
738 | be an event internal to libev itself, so there is no guarantee that a |
759 | be an event internal to libev itself, so there is no guarantee that a |
739 | user-registered callback will be called), and will return after one |
760 | user-registered callback will be called), and will return after one |
740 | iteration of the loop. |
761 | iteration of the loop. |
741 | |
762 | |
742 | This is useful if you are waiting for some external event in conjunction |
763 | This is useful if you are waiting for some external event in conjunction |
743 | with something not expressible using other libev watchers (i.e. "roll your |
764 | with something not expressible using other libev watchers (i.e. "roll your |
744 | own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
765 | own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
745 | usually a better approach for this kind of thing. |
766 | usually a better approach for this kind of thing. |
746 | |
767 | |
747 | Here are the gory details of what C<ev_loop> does: |
768 | Here are the gory details of what C<ev_run> does: |
748 | |
769 | |
|
|
770 | - Increment loop depth. |
|
|
771 | - Reset the ev_break status. |
749 | - Before the first iteration, call any pending watchers. |
772 | - Before the first iteration, call any pending watchers. |
|
|
773 | LOOP: |
750 | * If EVFLAG_FORKCHECK was used, check for a fork. |
774 | - If EVFLAG_FORKCHECK was used, check for a fork. |
751 | - If a fork was detected (by any means), queue and call all fork watchers. |
775 | - If a fork was detected (by any means), queue and call all fork watchers. |
752 | - Queue and call all prepare watchers. |
776 | - Queue and call all prepare watchers. |
|
|
777 | - If ev_break was called, goto FINISH. |
753 | - If we have been forked, detach and recreate the kernel state |
778 | - If we have been forked, detach and recreate the kernel state |
754 | as to not disturb the other process. |
779 | as to not disturb the other process. |
755 | - Update the kernel state with all outstanding changes. |
780 | - Update the kernel state with all outstanding changes. |
756 | - Update the "event loop time" (ev_now ()). |
781 | - Update the "event loop time" (ev_now ()). |
757 | - Calculate for how long to sleep or block, if at all |
782 | - Calculate for how long to sleep or block, if at all |
758 | (active idle watchers, EVLOOP_NONBLOCK or not having |
783 | (active idle watchers, EVRUN_NOWAIT or not having |
759 | any active watchers at all will result in not sleeping). |
784 | any active watchers at all will result in not sleeping). |
760 | - Sleep if the I/O and timer collect interval say so. |
785 | - Sleep if the I/O and timer collect interval say so. |
|
|
786 | - Increment loop iteration counter. |
761 | - Block the process, waiting for any events. |
787 | - Block the process, waiting for any events. |
762 | - Queue all outstanding I/O (fd) events. |
788 | - Queue all outstanding I/O (fd) events. |
763 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
789 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
764 | - Queue all expired timers. |
790 | - Queue all expired timers. |
765 | - Queue all expired periodics. |
791 | - Queue all expired periodics. |
766 | - Unless any events are pending now, queue all idle watchers. |
792 | - Queue all idle watchers with priority higher than that of pending events. |
767 | - Queue all check watchers. |
793 | - Queue all check watchers. |
768 | - Call all queued watchers in reverse order (i.e. check watchers first). |
794 | - Call all queued watchers in reverse order (i.e. check watchers first). |
769 | Signals and child watchers are implemented as I/O watchers, and will |
795 | Signals and child watchers are implemented as I/O watchers, and will |
770 | be handled here by queueing them when their watcher gets executed. |
796 | be handled here by queueing them when their watcher gets executed. |
771 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
797 | - If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
772 | were used, or there are no active watchers, return, otherwise |
798 | were used, or there are no active watchers, goto FINISH, otherwise |
773 | continue with step *. |
799 | continue with step LOOP. |
|
|
800 | FINISH: |
|
|
801 | - Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
802 | - Decrement the loop depth. |
|
|
803 | - Return. |
774 | |
804 | |
775 | Example: Queue some jobs and then loop until no events are outstanding |
805 | Example: Queue some jobs and then loop until no events are outstanding |
776 | anymore. |
806 | anymore. |
777 | |
807 | |
778 | ... queue jobs here, make sure they register event watchers as long |
808 | ... queue jobs here, make sure they register event watchers as long |
779 | ... as they still have work to do (even an idle watcher will do..) |
809 | ... as they still have work to do (even an idle watcher will do..) |
780 | ev_loop (my_loop, 0); |
810 | ev_run (my_loop, 0); |
781 | ... jobs done or somebody called unloop. yeah! |
811 | ... jobs done or somebody called unloop. yeah! |
782 | |
812 | |
783 | =item ev_unloop (loop, how) |
813 | =item ev_break (loop, how) |
784 | |
814 | |
785 | Can be used to make a call to C<ev_loop> return early (but only after it |
815 | Can be used to make a call to C<ev_run> return early (but only after it |
786 | has processed all outstanding events). The C<how> argument must be either |
816 | has processed all outstanding events). The C<how> argument must be either |
787 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
817 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
788 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
818 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
789 | |
819 | |
790 | This "unloop state" will be cleared when entering C<ev_loop> again. |
820 | This "unloop state" will be cleared when entering C<ev_run> again. |
791 | |
821 | |
792 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
822 | It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO## |
793 | |
823 | |
794 | =item ev_ref (loop) |
824 | =item ev_ref (loop) |
795 | |
825 | |
796 | =item ev_unref (loop) |
826 | =item ev_unref (loop) |
797 | |
827 | |
798 | Ref/unref can be used to add or remove a reference count on the event |
828 | Ref/unref can be used to add or remove a reference count on the event |
799 | loop: Every watcher keeps one reference, and as long as the reference |
829 | loop: Every watcher keeps one reference, and as long as the reference |
800 | count is nonzero, C<ev_loop> will not return on its own. |
830 | count is nonzero, C<ev_run> will not return on its own. |
801 | |
831 | |
802 | This is useful when you have a watcher that you never intend to |
832 | This is useful when you have a watcher that you never intend to |
803 | unregister, but that nevertheless should not keep C<ev_loop> from |
833 | unregister, but that nevertheless should not keep C<ev_run> from |
804 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
834 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
805 | before stopping it. |
835 | before stopping it. |
806 | |
836 | |
807 | As an example, libev itself uses this for its internal signal pipe: It |
837 | As an example, libev itself uses this for its internal signal pipe: It |
808 | is not visible to the libev user and should not keep C<ev_loop> from |
838 | is not visible to the libev user and should not keep C<ev_run> from |
809 | exiting if no event watchers registered by it are active. It is also an |
839 | exiting if no event watchers registered by it are active. It is also an |
810 | excellent way to do this for generic recurring timers or from within |
840 | excellent way to do this for generic recurring timers or from within |
811 | third-party libraries. Just remember to I<unref after start> and I<ref |
841 | third-party libraries. Just remember to I<unref after start> and I<ref |
812 | before stop> (but only if the watcher wasn't active before, or was active |
842 | before stop> (but only if the watcher wasn't active before, or was active |
813 | before, respectively. Note also that libev might stop watchers itself |
843 | before, respectively. Note also that libev might stop watchers itself |
814 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
844 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
815 | in the callback). |
845 | in the callback). |
816 | |
846 | |
817 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
847 | Example: Create a signal watcher, but keep it from keeping C<ev_run> |
818 | running when nothing else is active. |
848 | running when nothing else is active. |
819 | |
849 | |
820 | ev_signal exitsig; |
850 | ev_signal exitsig; |
821 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
851 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
822 | ev_signal_start (loop, &exitsig); |
852 | ev_signal_start (loop, &exitsig); |
… | |
… | |
867 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
897 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
868 | as this approaches the timing granularity of most systems. Note that if |
898 | as this approaches the timing granularity of most systems. Note that if |
869 | you do transactions with the outside world and you can't increase the |
899 | you do transactions with the outside world and you can't increase the |
870 | parallelity, then this setting will limit your transaction rate (if you |
900 | parallelity, then this setting will limit your transaction rate (if you |
871 | need to poll once per transaction and the I/O collect interval is 0.01, |
901 | need to poll once per transaction and the I/O collect interval is 0.01, |
872 | then you can't do more than 100 transations per second). |
902 | then you can't do more than 100 transactions per second). |
873 | |
903 | |
874 | Setting the I<timeout collect interval> can improve the opportunity for |
904 | Setting the I<timeout collect interval> can improve the opportunity for |
875 | saving power, as the program will "bundle" timer callback invocations that |
905 | saving power, as the program will "bundle" timer callback invocations that |
876 | are "near" in time together, by delaying some, thus reducing the number of |
906 | are "near" in time together, by delaying some, thus reducing the number of |
877 | times the process sleeps and wakes up again. Another useful technique to |
907 | times the process sleeps and wakes up again. Another useful technique to |
… | |
… | |
885 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
915 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
886 | |
916 | |
887 | =item ev_invoke_pending (loop) |
917 | =item ev_invoke_pending (loop) |
888 | |
918 | |
889 | This call will simply invoke all pending watchers while resetting their |
919 | This call will simply invoke all pending watchers while resetting their |
890 | pending state. Normally, C<ev_loop> does this automatically when required, |
920 | pending state. Normally, C<ev_run> does this automatically when required, |
891 | but when overriding the invoke callback this call comes handy. |
921 | but when overriding the invoke callback this call comes handy. This |
|
|
922 | function can be invoked from a watcher - this can be useful for example |
|
|
923 | when you want to do some lengthy calculation and want to pass further |
|
|
924 | event handling to another thread (you still have to make sure only one |
|
|
925 | thread executes within C<ev_invoke_pending> or C<ev_run> of course). |
892 | |
926 | |
893 | =item int ev_pending_count (loop) |
927 | =item int ev_pending_count (loop) |
894 | |
928 | |
895 | Returns the number of pending watchers - zero indicates that no watchers |
929 | Returns the number of pending watchers - zero indicates that no watchers |
896 | are pending. |
930 | are pending. |
897 | |
931 | |
898 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
932 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
899 | |
933 | |
900 | This overrides the invoke pending functionality of the loop: Instead of |
934 | This overrides the invoke pending functionality of the loop: Instead of |
901 | invoking all pending watchers when there are any, C<ev_loop> will call |
935 | invoking all pending watchers when there are any, C<ev_run> will call |
902 | this callback instead. This is useful, for example, when you want to |
936 | this callback instead. This is useful, for example, when you want to |
903 | invoke the actual watchers inside another context (another thread etc.). |
937 | invoke the actual watchers inside another context (another thread etc.). |
904 | |
938 | |
905 | If you want to reset the callback, use C<ev_invoke_pending> as new |
939 | If you want to reset the callback, use C<ev_invoke_pending> as new |
906 | callback. |
940 | callback. |
… | |
… | |
909 | |
943 | |
910 | Sometimes you want to share the same loop between multiple threads. This |
944 | Sometimes you want to share the same loop between multiple threads. This |
911 | can be done relatively simply by putting mutex_lock/unlock calls around |
945 | can be done relatively simply by putting mutex_lock/unlock calls around |
912 | each call to a libev function. |
946 | each call to a libev function. |
913 | |
947 | |
914 | However, C<ev_loop> can run an indefinite time, so it is not feasible to |
948 | However, C<ev_run> can run an indefinite time, so it is not feasible |
915 | wait for it to return. One way around this is to wake up the loop via |
949 | to wait for it to return. One way around this is to wake up the event |
916 | C<ev_unloop> and C<av_async_send>, another way is to set these I<release> |
950 | loop via C<ev_break> and C<av_async_send>, another way is to set these |
917 | and I<acquire> callbacks on the loop. |
951 | I<release> and I<acquire> callbacks on the loop. |
918 | |
952 | |
919 | When set, then C<release> will be called just before the thread is |
953 | When set, then C<release> will be called just before the thread is |
920 | suspended waiting for new events, and C<acquire> is called just |
954 | suspended waiting for new events, and C<acquire> is called just |
921 | afterwards. |
955 | afterwards. |
922 | |
956 | |
… | |
… | |
925 | |
959 | |
926 | While event loop modifications are allowed between invocations of |
960 | While event loop modifications are allowed between invocations of |
927 | C<release> and C<acquire> (that's their only purpose after all), no |
961 | C<release> and C<acquire> (that's their only purpose after all), no |
928 | modifications done will affect the event loop, i.e. adding watchers will |
962 | modifications done will affect the event loop, i.e. adding watchers will |
929 | have no effect on the set of file descriptors being watched, or the time |
963 | have no effect on the set of file descriptors being watched, or the time |
930 | waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it |
964 | waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it |
931 | to take note of any changes you made. |
965 | to take note of any changes you made. |
932 | |
966 | |
933 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
967 | In theory, threads executing C<ev_run> will be async-cancel safe between |
934 | invocations of C<release> and C<acquire>. |
968 | invocations of C<release> and C<acquire>. |
935 | |
969 | |
936 | See also the locking example in the C<THREADS> section later in this |
970 | See also the locking example in the C<THREADS> section later in this |
937 | document. |
971 | document. |
938 | |
972 | |
… | |
… | |
947 | These two functions can be used to associate arbitrary data with a loop, |
981 | These two functions can be used to associate arbitrary data with a loop, |
948 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
982 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
949 | C<acquire> callbacks described above, but of course can be (ab-)used for |
983 | C<acquire> callbacks described above, but of course can be (ab-)used for |
950 | any other purpose as well. |
984 | any other purpose as well. |
951 | |
985 | |
952 | =item ev_loop_verify (loop) |
986 | =item ev_verify (loop) |
953 | |
987 | |
954 | This function only does something when C<EV_VERIFY> support has been |
988 | This function only does something when C<EV_VERIFY> support has been |
955 | compiled in, which is the default for non-minimal builds. It tries to go |
989 | compiled in, which is the default for non-minimal builds. It tries to go |
956 | through all internal structures and checks them for validity. If anything |
990 | through all internal structures and checks them for validity. If anything |
957 | is found to be inconsistent, it will print an error message to standard |
991 | is found to be inconsistent, it will print an error message to standard |
… | |
… | |
968 | |
1002 | |
969 | In the following description, uppercase C<TYPE> in names stands for the |
1003 | In the following description, uppercase C<TYPE> in names stands for the |
970 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
1004 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
971 | watchers and C<ev_io_start> for I/O watchers. |
1005 | watchers and C<ev_io_start> for I/O watchers. |
972 | |
1006 | |
973 | A watcher is a structure that you create and register to record your |
1007 | A watcher is an opaque structure that you allocate and register to record |
974 | interest in some event. For instance, if you want to wait for STDIN to |
1008 | your interest in some event. To make a concrete example, imagine you want |
975 | become readable, you would create an C<ev_io> watcher for that: |
1009 | to wait for STDIN to become readable, you would create an C<ev_io> watcher |
|
|
1010 | for that: |
976 | |
1011 | |
977 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
1012 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
978 | { |
1013 | { |
979 | ev_io_stop (w); |
1014 | ev_io_stop (w); |
980 | ev_unloop (loop, EVUNLOOP_ALL); |
1015 | ev_break (loop, EVBREAK_ALL); |
981 | } |
1016 | } |
982 | |
1017 | |
983 | struct ev_loop *loop = ev_default_loop (0); |
1018 | struct ev_loop *loop = ev_default_loop (0); |
984 | |
1019 | |
985 | ev_io stdin_watcher; |
1020 | ev_io stdin_watcher; |
986 | |
1021 | |
987 | ev_init (&stdin_watcher, my_cb); |
1022 | ev_init (&stdin_watcher, my_cb); |
988 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1023 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
989 | ev_io_start (loop, &stdin_watcher); |
1024 | ev_io_start (loop, &stdin_watcher); |
990 | |
1025 | |
991 | ev_loop (loop, 0); |
1026 | ev_run (loop, 0); |
992 | |
1027 | |
993 | As you can see, you are responsible for allocating the memory for your |
1028 | As you can see, you are responsible for allocating the memory for your |
994 | watcher structures (and it is I<usually> a bad idea to do this on the |
1029 | watcher structures (and it is I<usually> a bad idea to do this on the |
995 | stack). |
1030 | stack). |
996 | |
1031 | |
997 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
1032 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
998 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
1033 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
999 | |
1034 | |
1000 | Each watcher structure must be initialised by a call to C<ev_init |
1035 | Each watcher structure must be initialised by a call to C<ev_init (watcher |
1001 | (watcher *, callback)>, which expects a callback to be provided. This |
1036 | *, callback)>, which expects a callback to be provided. This callback is |
1002 | callback gets invoked each time the event occurs (or, in the case of I/O |
1037 | invoked each time the event occurs (or, in the case of I/O watchers, each |
1003 | watchers, each time the event loop detects that the file descriptor given |
1038 | time the event loop detects that the file descriptor given is readable |
1004 | is readable and/or writable). |
1039 | and/or writable). |
1005 | |
1040 | |
1006 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
1041 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
1007 | macro to configure it, with arguments specific to the watcher type. There |
1042 | macro to configure it, with arguments specific to the watcher type. There |
1008 | is also a macro to combine initialisation and setting in one call: C<< |
1043 | is also a macro to combine initialisation and setting in one call: C<< |
1009 | ev_TYPE_init (watcher *, callback, ...) >>. |
1044 | ev_TYPE_init (watcher *, callback, ...) >>. |
… | |
… | |
1032 | =item C<EV_WRITE> |
1067 | =item C<EV_WRITE> |
1033 | |
1068 | |
1034 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1069 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1035 | writable. |
1070 | writable. |
1036 | |
1071 | |
1037 | =item C<EV_TIMEOUT> |
1072 | =item C<EV_TIMER> |
1038 | |
1073 | |
1039 | The C<ev_timer> watcher has timed out. |
1074 | The C<ev_timer> watcher has timed out. |
1040 | |
1075 | |
1041 | =item C<EV_PERIODIC> |
1076 | =item C<EV_PERIODIC> |
1042 | |
1077 | |
… | |
… | |
1060 | |
1095 | |
1061 | =item C<EV_PREPARE> |
1096 | =item C<EV_PREPARE> |
1062 | |
1097 | |
1063 | =item C<EV_CHECK> |
1098 | =item C<EV_CHECK> |
1064 | |
1099 | |
1065 | All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts |
1100 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
1066 | to gather new events, and all C<ev_check> watchers are invoked just after |
1101 | to gather new events, and all C<ev_check> watchers are invoked just after |
1067 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
1102 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
1068 | received events. Callbacks of both watcher types can start and stop as |
1103 | received events. Callbacks of both watcher types can start and stop as |
1069 | many watchers as they want, and all of them will be taken into account |
1104 | many watchers as they want, and all of them will be taken into account |
1070 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1105 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1071 | C<ev_loop> from blocking). |
1106 | C<ev_run> from blocking). |
1072 | |
1107 | |
1073 | =item C<EV_EMBED> |
1108 | =item C<EV_EMBED> |
1074 | |
1109 | |
1075 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1110 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1076 | |
1111 | |
… | |
… | |
1104 | example it might indicate that a fd is readable or writable, and if your |
1139 | example it might indicate that a fd is readable or writable, and if your |
1105 | callbacks is well-written it can just attempt the operation and cope with |
1140 | callbacks is well-written it can just attempt the operation and cope with |
1106 | the error from read() or write(). This will not work in multi-threaded |
1141 | the error from read() or write(). This will not work in multi-threaded |
1107 | programs, though, as the fd could already be closed and reused for another |
1142 | programs, though, as the fd could already be closed and reused for another |
1108 | thing, so beware. |
1143 | thing, so beware. |
|
|
1144 | |
|
|
1145 | =back |
|
|
1146 | |
|
|
1147 | =head2 WATCHER STATES |
|
|
1148 | |
|
|
1149 | There are various watcher states mentioned throughout this manual - |
|
|
1150 | active, pending and so on. In this section these states and the rules to |
|
|
1151 | transition between them will be described in more detail - and while these |
|
|
1152 | rules might look complicated, they usually do "the right thing". |
|
|
1153 | |
|
|
1154 | =over 4 |
|
|
1155 | |
|
|
1156 | =item initialiased |
|
|
1157 | |
|
|
1158 | Before a watcher can be registered with the event looop it has to be |
|
|
1159 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1160 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
|
|
1161 | |
|
|
1162 | In this state it is simply some block of memory that is suitable for use |
|
|
1163 | in an event loop. It can be moved around, freed, reused etc. at will. |
|
|
1164 | |
|
|
1165 | =item started/running/active |
|
|
1166 | |
|
|
1167 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
|
|
1168 | property of the event loop, and is actively waiting for events. While in |
|
|
1169 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1170 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1171 | and call libev functions on it that are documented to work on active watchers. |
|
|
1172 | |
|
|
1173 | =item pending |
|
|
1174 | |
|
|
1175 | If a watcher is active and libev determines that an event it is interested |
|
|
1176 | in has occurred (such as a timer expiring), it will become pending. It will |
|
|
1177 | stay in this pending state until either it is stopped or its callback is |
|
|
1178 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1179 | callback. |
|
|
1180 | |
|
|
1181 | The watcher might or might not be active while it is pending (for example, |
|
|
1182 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1183 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1184 | but it is still property of the event loop at this time, so cannot be |
|
|
1185 | moved, freed or reused. And if it is active the rules described in the |
|
|
1186 | previous item still apply. |
|
|
1187 | |
|
|
1188 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1189 | via C<ev_feed_event>), in which case it becomes pending without being |
|
|
1190 | active. |
|
|
1191 | |
|
|
1192 | =item stopped |
|
|
1193 | |
|
|
1194 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1195 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
|
|
1196 | latter will clear any pending state the watcher might be in, regardless |
|
|
1197 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1198 | freeing it is often a good idea. |
|
|
1199 | |
|
|
1200 | While stopped (and not pending) the watcher is essentially in the |
|
|
1201 | initialised state, that is it can be reused, moved, modified in any way |
|
|
1202 | you wish. |
1109 | |
1203 | |
1110 | =back |
1204 | =back |
1111 | |
1205 | |
1112 | =head2 GENERIC WATCHER FUNCTIONS |
1206 | =head2 GENERIC WATCHER FUNCTIONS |
1113 | |
1207 | |
… | |
… | |
1375 | |
1469 | |
1376 | For example, to emulate how many other event libraries handle priorities, |
1470 | For example, to emulate how many other event libraries handle priorities, |
1377 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1471 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1378 | the normal watcher callback, you just start the idle watcher. The real |
1472 | the normal watcher callback, you just start the idle watcher. The real |
1379 | processing is done in the idle watcher callback. This causes libev to |
1473 | processing is done in the idle watcher callback. This causes libev to |
1380 | continously poll and process kernel event data for the watcher, but when |
1474 | continuously poll and process kernel event data for the watcher, but when |
1381 | the lock-out case is known to be rare (which in turn is rare :), this is |
1475 | the lock-out case is known to be rare (which in turn is rare :), this is |
1382 | workable. |
1476 | workable. |
1383 | |
1477 | |
1384 | Usually, however, the lock-out model implemented that way will perform |
1478 | Usually, however, the lock-out model implemented that way will perform |
1385 | miserably under the type of load it was designed to handle. In that case, |
1479 | miserably under the type of load it was designed to handle. In that case, |
… | |
… | |
1399 | { |
1493 | { |
1400 | // stop the I/O watcher, we received the event, but |
1494 | // stop the I/O watcher, we received the event, but |
1401 | // are not yet ready to handle it. |
1495 | // are not yet ready to handle it. |
1402 | ev_io_stop (EV_A_ w); |
1496 | ev_io_stop (EV_A_ w); |
1403 | |
1497 | |
1404 | // start the idle watcher to ahndle the actual event. |
1498 | // start the idle watcher to handle the actual event. |
1405 | // it will not be executed as long as other watchers |
1499 | // it will not be executed as long as other watchers |
1406 | // with the default priority are receiving events. |
1500 | // with the default priority are receiving events. |
1407 | ev_idle_start (EV_A_ &idle); |
1501 | ev_idle_start (EV_A_ &idle); |
1408 | } |
1502 | } |
1409 | |
1503 | |
… | |
… | |
1463 | |
1557 | |
1464 | If you cannot use non-blocking mode, then force the use of a |
1558 | If you cannot use non-blocking mode, then force the use of a |
1465 | known-to-be-good backend (at the time of this writing, this includes only |
1559 | known-to-be-good backend (at the time of this writing, this includes only |
1466 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1560 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1467 | descriptors for which non-blocking operation makes no sense (such as |
1561 | descriptors for which non-blocking operation makes no sense (such as |
1468 | files) - libev doesn't guarentee any specific behaviour in that case. |
1562 | files) - libev doesn't guarantee any specific behaviour in that case. |
1469 | |
1563 | |
1470 | Another thing you have to watch out for is that it is quite easy to |
1564 | Another thing you have to watch out for is that it is quite easy to |
1471 | receive "spurious" readiness notifications, that is your callback might |
1565 | receive "spurious" readiness notifications, that is your callback might |
1472 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1566 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1473 | because there is no data. Not only are some backends known to create a |
1567 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1538 | |
1632 | |
1539 | So when you encounter spurious, unexplained daemon exits, make sure you |
1633 | So when you encounter spurious, unexplained daemon exits, make sure you |
1540 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1634 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1541 | somewhere, as that would have given you a big clue). |
1635 | somewhere, as that would have given you a big clue). |
1542 | |
1636 | |
|
|
1637 | =head3 The special problem of accept()ing when you can't |
|
|
1638 | |
|
|
1639 | Many implementations of the POSIX C<accept> function (for example, |
|
|
1640 | found in post-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1641 | connection from the pending queue in all error cases. |
|
|
1642 | |
|
|
1643 | For example, larger servers often run out of file descriptors (because |
|
|
1644 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
|
|
1645 | rejecting the connection, leading to libev signalling readiness on |
|
|
1646 | the next iteration again (the connection still exists after all), and |
|
|
1647 | typically causing the program to loop at 100% CPU usage. |
|
|
1648 | |
|
|
1649 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1650 | operating systems, there is usually little the app can do to remedy the |
|
|
1651 | situation, and no known thread-safe method of removing the connection to |
|
|
1652 | cope with overload is known (to me). |
|
|
1653 | |
|
|
1654 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1655 | - when the program encounters an overload, it will just loop until the |
|
|
1656 | situation is over. While this is a form of busy waiting, no OS offers an |
|
|
1657 | event-based way to handle this situation, so it's the best one can do. |
|
|
1658 | |
|
|
1659 | A better way to handle the situation is to log any errors other than |
|
|
1660 | C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such |
|
|
1661 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1662 | what could be wrong ("raise the ulimit!"). For extra points one could stop |
|
|
1663 | the C<ev_io> watcher on the listening fd "for a while", which reduces CPU |
|
|
1664 | usage. |
|
|
1665 | |
|
|
1666 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1667 | descriptor for overload situations (e.g. by opening F</dev/null>), and |
|
|
1668 | when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>, |
|
|
1669 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1670 | clients under typical overload conditions. |
|
|
1671 | |
|
|
1672 | The last way to handle it is to simply log the error and C<exit>, as |
|
|
1673 | is often done with C<malloc> failures, but this results in an easy |
|
|
1674 | opportunity for a DoS attack. |
1543 | |
1675 | |
1544 | =head3 Watcher-Specific Functions |
1676 | =head3 Watcher-Specific Functions |
1545 | |
1677 | |
1546 | =over 4 |
1678 | =over 4 |
1547 | |
1679 | |
… | |
… | |
1579 | ... |
1711 | ... |
1580 | struct ev_loop *loop = ev_default_init (0); |
1712 | struct ev_loop *loop = ev_default_init (0); |
1581 | ev_io stdin_readable; |
1713 | ev_io stdin_readable; |
1582 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1714 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1583 | ev_io_start (loop, &stdin_readable); |
1715 | ev_io_start (loop, &stdin_readable); |
1584 | ev_loop (loop, 0); |
1716 | ev_run (loop, 0); |
1585 | |
1717 | |
1586 | |
1718 | |
1587 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1719 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1588 | |
1720 | |
1589 | Timer watchers are simple relative timers that generate an event after a |
1721 | Timer watchers are simple relative timers that generate an event after a |
… | |
… | |
1598 | The callback is guaranteed to be invoked only I<after> its timeout has |
1730 | The callback is guaranteed to be invoked only I<after> its timeout has |
1599 | passed (not I<at>, so on systems with very low-resolution clocks this |
1731 | passed (not I<at>, so on systems with very low-resolution clocks this |
1600 | might introduce a small delay). If multiple timers become ready during the |
1732 | might introduce a small delay). If multiple timers become ready during the |
1601 | same loop iteration then the ones with earlier time-out values are invoked |
1733 | same loop iteration then the ones with earlier time-out values are invoked |
1602 | before ones of the same priority with later time-out values (but this is |
1734 | before ones of the same priority with later time-out values (but this is |
1603 | no longer true when a callback calls C<ev_loop> recursively). |
1735 | no longer true when a callback calls C<ev_run> recursively). |
1604 | |
1736 | |
1605 | =head3 Be smart about timeouts |
1737 | =head3 Be smart about timeouts |
1606 | |
1738 | |
1607 | Many real-world problems involve some kind of timeout, usually for error |
1739 | Many real-world problems involve some kind of timeout, usually for error |
1608 | recovery. A typical example is an HTTP request - if the other side hangs, |
1740 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
1694 | ev_tstamp timeout = last_activity + 60.; |
1826 | ev_tstamp timeout = last_activity + 60.; |
1695 | |
1827 | |
1696 | // if last_activity + 60. is older than now, we did time out |
1828 | // if last_activity + 60. is older than now, we did time out |
1697 | if (timeout < now) |
1829 | if (timeout < now) |
1698 | { |
1830 | { |
1699 | // timeout occured, take action |
1831 | // timeout occurred, take action |
1700 | } |
1832 | } |
1701 | else |
1833 | else |
1702 | { |
1834 | { |
1703 | // callback was invoked, but there was some activity, re-arm |
1835 | // callback was invoked, but there was some activity, re-arm |
1704 | // the watcher to fire in last_activity + 60, which is |
1836 | // the watcher to fire in last_activity + 60, which is |
… | |
… | |
1726 | to the current time (meaning we just have some activity :), then call the |
1858 | to the current time (meaning we just have some activity :), then call the |
1727 | callback, which will "do the right thing" and start the timer: |
1859 | callback, which will "do the right thing" and start the timer: |
1728 | |
1860 | |
1729 | ev_init (timer, callback); |
1861 | ev_init (timer, callback); |
1730 | last_activity = ev_now (loop); |
1862 | last_activity = ev_now (loop); |
1731 | callback (loop, timer, EV_TIMEOUT); |
1863 | callback (loop, timer, EV_TIMER); |
1732 | |
1864 | |
1733 | And when there is some activity, simply store the current time in |
1865 | And when there is some activity, simply store the current time in |
1734 | C<last_activity>, no libev calls at all: |
1866 | C<last_activity>, no libev calls at all: |
1735 | |
1867 | |
1736 | last_actiivty = ev_now (loop); |
1868 | last_activity = ev_now (loop); |
1737 | |
1869 | |
1738 | This technique is slightly more complex, but in most cases where the |
1870 | This technique is slightly more complex, but in most cases where the |
1739 | time-out is unlikely to be triggered, much more efficient. |
1871 | time-out is unlikely to be triggered, much more efficient. |
1740 | |
1872 | |
1741 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
1873 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
… | |
… | |
1779 | |
1911 | |
1780 | =head3 The special problem of time updates |
1912 | =head3 The special problem of time updates |
1781 | |
1913 | |
1782 | Establishing the current time is a costly operation (it usually takes at |
1914 | Establishing the current time is a costly operation (it usually takes at |
1783 | least two system calls): EV therefore updates its idea of the current |
1915 | least two system calls): EV therefore updates its idea of the current |
1784 | time only before and after C<ev_loop> collects new events, which causes a |
1916 | time only before and after C<ev_run> collects new events, which causes a |
1785 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1917 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1786 | lots of events in one iteration. |
1918 | lots of events in one iteration. |
1787 | |
1919 | |
1788 | The relative timeouts are calculated relative to the C<ev_now ()> |
1920 | The relative timeouts are calculated relative to the C<ev_now ()> |
1789 | time. This is usually the right thing as this timestamp refers to the time |
1921 | time. This is usually the right thing as this timestamp refers to the time |
… | |
… | |
1906 | } |
2038 | } |
1907 | |
2039 | |
1908 | ev_timer mytimer; |
2040 | ev_timer mytimer; |
1909 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2041 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1910 | ev_timer_again (&mytimer); /* start timer */ |
2042 | ev_timer_again (&mytimer); /* start timer */ |
1911 | ev_loop (loop, 0); |
2043 | ev_run (loop, 0); |
1912 | |
2044 | |
1913 | // and in some piece of code that gets executed on any "activity": |
2045 | // and in some piece of code that gets executed on any "activity": |
1914 | // reset the timeout to start ticking again at 10 seconds |
2046 | // reset the timeout to start ticking again at 10 seconds |
1915 | ev_timer_again (&mytimer); |
2047 | ev_timer_again (&mytimer); |
1916 | |
2048 | |
… | |
… | |
1942 | |
2074 | |
1943 | As with timers, the callback is guaranteed to be invoked only when the |
2075 | As with timers, the callback is guaranteed to be invoked only when the |
1944 | point in time where it is supposed to trigger has passed. If multiple |
2076 | point in time where it is supposed to trigger has passed. If multiple |
1945 | timers become ready during the same loop iteration then the ones with |
2077 | timers become ready during the same loop iteration then the ones with |
1946 | earlier time-out values are invoked before ones with later time-out values |
2078 | earlier time-out values are invoked before ones with later time-out values |
1947 | (but this is no longer true when a callback calls C<ev_loop> recursively). |
2079 | (but this is no longer true when a callback calls C<ev_run> recursively). |
1948 | |
2080 | |
1949 | =head3 Watcher-Specific Functions and Data Members |
2081 | =head3 Watcher-Specific Functions and Data Members |
1950 | |
2082 | |
1951 | =over 4 |
2083 | =over 4 |
1952 | |
2084 | |
… | |
… | |
2080 | Example: Call a callback every hour, or, more precisely, whenever the |
2212 | Example: Call a callback every hour, or, more precisely, whenever the |
2081 | system time is divisible by 3600. The callback invocation times have |
2213 | system time is divisible by 3600. The callback invocation times have |
2082 | potentially a lot of jitter, but good long-term stability. |
2214 | potentially a lot of jitter, but good long-term stability. |
2083 | |
2215 | |
2084 | static void |
2216 | static void |
2085 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2217 | clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
2086 | { |
2218 | { |
2087 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2219 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2088 | } |
2220 | } |
2089 | |
2221 | |
2090 | ev_periodic hourly_tick; |
2222 | ev_periodic hourly_tick; |
… | |
… | |
2190 | Example: Try to exit cleanly on SIGINT. |
2322 | Example: Try to exit cleanly on SIGINT. |
2191 | |
2323 | |
2192 | static void |
2324 | static void |
2193 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2325 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2194 | { |
2326 | { |
2195 | ev_unloop (loop, EVUNLOOP_ALL); |
2327 | ev_break (loop, EVBREAK_ALL); |
2196 | } |
2328 | } |
2197 | |
2329 | |
2198 | ev_signal signal_watcher; |
2330 | ev_signal signal_watcher; |
2199 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2331 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2200 | ev_signal_start (loop, &signal_watcher); |
2332 | ev_signal_start (loop, &signal_watcher); |
… | |
… | |
2586 | |
2718 | |
2587 | Prepare and check watchers are usually (but not always) used in pairs: |
2719 | Prepare and check watchers are usually (but not always) used in pairs: |
2588 | prepare watchers get invoked before the process blocks and check watchers |
2720 | prepare watchers get invoked before the process blocks and check watchers |
2589 | afterwards. |
2721 | afterwards. |
2590 | |
2722 | |
2591 | You I<must not> call C<ev_loop> or similar functions that enter |
2723 | You I<must not> call C<ev_run> or similar functions that enter |
2592 | the current event loop from either C<ev_prepare> or C<ev_check> |
2724 | the current event loop from either C<ev_prepare> or C<ev_check> |
2593 | watchers. Other loops than the current one are fine, however. The |
2725 | watchers. Other loops than the current one are fine, however. The |
2594 | rationale behind this is that you do not need to check for recursion in |
2726 | rationale behind this is that you do not need to check for recursion in |
2595 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2727 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2596 | C<ev_check> so if you have one watcher of each kind they will always be |
2728 | C<ev_check> so if you have one watcher of each kind they will always be |
… | |
… | |
2764 | |
2896 | |
2765 | if (timeout >= 0) |
2897 | if (timeout >= 0) |
2766 | // create/start timer |
2898 | // create/start timer |
2767 | |
2899 | |
2768 | // poll |
2900 | // poll |
2769 | ev_loop (EV_A_ 0); |
2901 | ev_run (EV_A_ 0); |
2770 | |
2902 | |
2771 | // stop timer again |
2903 | // stop timer again |
2772 | if (timeout >= 0) |
2904 | if (timeout >= 0) |
2773 | ev_timer_stop (EV_A_ &to); |
2905 | ev_timer_stop (EV_A_ &to); |
2774 | |
2906 | |
… | |
… | |
2852 | if you do not want that, you need to temporarily stop the embed watcher). |
2984 | if you do not want that, you need to temporarily stop the embed watcher). |
2853 | |
2985 | |
2854 | =item ev_embed_sweep (loop, ev_embed *) |
2986 | =item ev_embed_sweep (loop, ev_embed *) |
2855 | |
2987 | |
2856 | Make a single, non-blocking sweep over the embedded loop. This works |
2988 | Make a single, non-blocking sweep over the embedded loop. This works |
2857 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
2989 | similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most |
2858 | appropriate way for embedded loops. |
2990 | appropriate way for embedded loops. |
2859 | |
2991 | |
2860 | =item struct ev_loop *other [read-only] |
2992 | =item struct ev_loop *other [read-only] |
2861 | |
2993 | |
2862 | The embedded event loop. |
2994 | The embedded event loop. |
… | |
… | |
2922 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3054 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2923 | handlers will be invoked, too, of course. |
3055 | handlers will be invoked, too, of course. |
2924 | |
3056 | |
2925 | =head3 The special problem of life after fork - how is it possible? |
3057 | =head3 The special problem of life after fork - how is it possible? |
2926 | |
3058 | |
2927 | Most uses of C<fork()> consist of forking, then some simple calls to ste |
3059 | Most uses of C<fork()> consist of forking, then some simple calls to set |
2928 | up/change the process environment, followed by a call to C<exec()>. This |
3060 | up/change the process environment, followed by a call to C<exec()>. This |
2929 | sequence should be handled by libev without any problems. |
3061 | sequence should be handled by libev without any problems. |
2930 | |
3062 | |
2931 | This changes when the application actually wants to do event handling |
3063 | This changes when the application actually wants to do event handling |
2932 | in the child, or both parent in child, in effect "continuing" after the |
3064 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
2948 | disadvantage of having to use multiple event loops (which do not support |
3080 | disadvantage of having to use multiple event loops (which do not support |
2949 | signal watchers). |
3081 | signal watchers). |
2950 | |
3082 | |
2951 | When this is not possible, or you want to use the default loop for |
3083 | When this is not possible, or you want to use the default loop for |
2952 | other reasons, then in the process that wants to start "fresh", call |
3084 | other reasons, then in the process that wants to start "fresh", call |
2953 | C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying |
3085 | C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>. |
2954 | the default loop will "orphan" (not stop) all registered watchers, so you |
3086 | Destroying the default loop will "orphan" (not stop) all registered |
2955 | have to be careful not to execute code that modifies those watchers. Note |
3087 | watchers, so you have to be careful not to execute code that modifies |
2956 | also that in that case, you have to re-register any signal watchers. |
3088 | those watchers. Note also that in that case, you have to re-register any |
|
|
3089 | signal watchers. |
2957 | |
3090 | |
2958 | =head3 Watcher-Specific Functions and Data Members |
3091 | =head3 Watcher-Specific Functions and Data Members |
2959 | |
3092 | |
2960 | =over 4 |
3093 | =over 4 |
2961 | |
3094 | |
… | |
… | |
2966 | believe me. |
3099 | believe me. |
2967 | |
3100 | |
2968 | =back |
3101 | =back |
2969 | |
3102 | |
2970 | |
3103 | |
2971 | =head2 C<ev_async> - how to wake up another event loop |
3104 | =head2 C<ev_async> - how to wake up an event loop |
2972 | |
3105 | |
2973 | In general, you cannot use an C<ev_loop> from multiple threads or other |
3106 | In general, you cannot use an C<ev_run> from multiple threads or other |
2974 | asynchronous sources such as signal handlers (as opposed to multiple event |
3107 | asynchronous sources such as signal handlers (as opposed to multiple event |
2975 | loops - those are of course safe to use in different threads). |
3108 | loops - those are of course safe to use in different threads). |
2976 | |
3109 | |
2977 | Sometimes, however, you need to wake up another event loop you do not |
3110 | Sometimes, however, you need to wake up an event loop you do not control, |
2978 | control, for example because it belongs to another thread. This is what |
3111 | for example because it belongs to another thread. This is what C<ev_async> |
2979 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
3112 | watchers do: as long as the C<ev_async> watcher is active, you can signal |
2980 | can signal it by calling C<ev_async_send>, which is thread- and signal |
3113 | it by calling C<ev_async_send>, which is thread- and signal safe. |
2981 | safe. |
|
|
2982 | |
3114 | |
2983 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3115 | This functionality is very similar to C<ev_signal> watchers, as signals, |
2984 | too, are asynchronous in nature, and signals, too, will be compressed |
3116 | too, are asynchronous in nature, and signals, too, will be compressed |
2985 | (i.e. the number of callback invocations may be less than the number of |
3117 | (i.e. the number of callback invocations may be less than the number of |
2986 | C<ev_async_sent> calls). |
3118 | C<ev_async_sent> calls). |
… | |
… | |
3141 | |
3273 | |
3142 | If C<timeout> is less than 0, then no timeout watcher will be |
3274 | If C<timeout> is less than 0, then no timeout watcher will be |
3143 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3275 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3144 | repeat = 0) will be started. C<0> is a valid timeout. |
3276 | repeat = 0) will be started. C<0> is a valid timeout. |
3145 | |
3277 | |
3146 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
3278 | The callback has the type C<void (*cb)(int revents, void *arg)> and is |
3147 | passed an C<revents> set like normal event callbacks (a combination of |
3279 | passed an C<revents> set like normal event callbacks (a combination of |
3148 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
3280 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg> |
3149 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3281 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3150 | a timeout and an io event at the same time - you probably should give io |
3282 | a timeout and an io event at the same time - you probably should give io |
3151 | events precedence. |
3283 | events precedence. |
3152 | |
3284 | |
3153 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3285 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3154 | |
3286 | |
3155 | static void stdin_ready (int revents, void *arg) |
3287 | static void stdin_ready (int revents, void *arg) |
3156 | { |
3288 | { |
3157 | if (revents & EV_READ) |
3289 | if (revents & EV_READ) |
3158 | /* stdin might have data for us, joy! */; |
3290 | /* stdin might have data for us, joy! */; |
3159 | else if (revents & EV_TIMEOUT) |
3291 | else if (revents & EV_TIMER) |
3160 | /* doh, nothing entered */; |
3292 | /* doh, nothing entered */; |
3161 | } |
3293 | } |
3162 | |
3294 | |
3163 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3295 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3164 | |
3296 | |
… | |
… | |
3298 | myclass obj; |
3430 | myclass obj; |
3299 | ev::io iow; |
3431 | ev::io iow; |
3300 | iow.set <myclass, &myclass::io_cb> (&obj); |
3432 | iow.set <myclass, &myclass::io_cb> (&obj); |
3301 | |
3433 | |
3302 | =item w->set (object *) |
3434 | =item w->set (object *) |
3303 | |
|
|
3304 | This is an B<experimental> feature that might go away in a future version. |
|
|
3305 | |
3435 | |
3306 | This is a variation of a method callback - leaving out the method to call |
3436 | This is a variation of a method callback - leaving out the method to call |
3307 | will default the method to C<operator ()>, which makes it possible to use |
3437 | will default the method to C<operator ()>, which makes it possible to use |
3308 | functor objects without having to manually specify the C<operator ()> all |
3438 | functor objects without having to manually specify the C<operator ()> all |
3309 | the time. Incidentally, you can then also leave out the template argument |
3439 | the time. Incidentally, you can then also leave out the template argument |
… | |
… | |
3349 | Associates a different C<struct ev_loop> with this watcher. You can only |
3479 | Associates a different C<struct ev_loop> with this watcher. You can only |
3350 | do this when the watcher is inactive (and not pending either). |
3480 | do this when the watcher is inactive (and not pending either). |
3351 | |
3481 | |
3352 | =item w->set ([arguments]) |
3482 | =item w->set ([arguments]) |
3353 | |
3483 | |
3354 | Basically the same as C<ev_TYPE_set>, with the same arguments. Must be |
3484 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
3355 | called at least once. Unlike the C counterpart, an active watcher gets |
3485 | method or a suitable start method must be called at least once. Unlike the |
3356 | automatically stopped and restarted when reconfiguring it with this |
3486 | C counterpart, an active watcher gets automatically stopped and restarted |
3357 | method. |
3487 | when reconfiguring it with this method. |
3358 | |
3488 | |
3359 | =item w->start () |
3489 | =item w->start () |
3360 | |
3490 | |
3361 | Starts the watcher. Note that there is no C<loop> argument, as the |
3491 | Starts the watcher. Note that there is no C<loop> argument, as the |
3362 | constructor already stores the event loop. |
3492 | constructor already stores the event loop. |
3363 | |
3493 | |
|
|
3494 | =item w->start ([arguments]) |
|
|
3495 | |
|
|
3496 | Instead of calling C<set> and C<start> methods separately, it is often |
|
|
3497 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
3498 | the configure C<set> method of the watcher. |
|
|
3499 | |
3364 | =item w->stop () |
3500 | =item w->stop () |
3365 | |
3501 | |
3366 | Stops the watcher if it is active. Again, no C<loop> argument. |
3502 | Stops the watcher if it is active. Again, no C<loop> argument. |
3367 | |
3503 | |
3368 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
3504 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
… | |
… | |
3380 | |
3516 | |
3381 | =back |
3517 | =back |
3382 | |
3518 | |
3383 | =back |
3519 | =back |
3384 | |
3520 | |
3385 | Example: Define a class with an IO and idle watcher, start one of them in |
3521 | Example: Define a class with two I/O and idle watchers, start the I/O |
3386 | the constructor. |
3522 | watchers in the constructor. |
3387 | |
3523 | |
3388 | class myclass |
3524 | class myclass |
3389 | { |
3525 | { |
3390 | ev::io io ; void io_cb (ev::io &w, int revents); |
3526 | ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
3527 | ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
3391 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3528 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3392 | |
3529 | |
3393 | myclass (int fd) |
3530 | myclass (int fd) |
3394 | { |
3531 | { |
3395 | io .set <myclass, &myclass::io_cb > (this); |
3532 | io .set <myclass, &myclass::io_cb > (this); |
|
|
3533 | io2 .set <myclass, &myclass::io2_cb > (this); |
3396 | idle.set <myclass, &myclass::idle_cb> (this); |
3534 | idle.set <myclass, &myclass::idle_cb> (this); |
3397 | |
3535 | |
3398 | io.start (fd, ev::READ); |
3536 | io.set (fd, ev::WRITE); // configure the watcher |
|
|
3537 | io.start (); // start it whenever convenient |
|
|
3538 | |
|
|
3539 | io2.start (fd, ev::READ); // set + start in one call |
3399 | } |
3540 | } |
3400 | }; |
3541 | }; |
3401 | |
3542 | |
3402 | |
3543 | |
3403 | =head1 OTHER LANGUAGE BINDINGS |
3544 | =head1 OTHER LANGUAGE BINDINGS |
… | |
… | |
3477 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3618 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3478 | C<EV_A_> is used when other arguments are following. Example: |
3619 | C<EV_A_> is used when other arguments are following. Example: |
3479 | |
3620 | |
3480 | ev_unref (EV_A); |
3621 | ev_unref (EV_A); |
3481 | ev_timer_add (EV_A_ watcher); |
3622 | ev_timer_add (EV_A_ watcher); |
3482 | ev_loop (EV_A_ 0); |
3623 | ev_run (EV_A_ 0); |
3483 | |
3624 | |
3484 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3625 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3485 | which is often provided by the following macro. |
3626 | which is often provided by the following macro. |
3486 | |
3627 | |
3487 | =item C<EV_P>, C<EV_P_> |
3628 | =item C<EV_P>, C<EV_P_> |
… | |
… | |
3527 | } |
3668 | } |
3528 | |
3669 | |
3529 | ev_check check; |
3670 | ev_check check; |
3530 | ev_check_init (&check, check_cb); |
3671 | ev_check_init (&check, check_cb); |
3531 | ev_check_start (EV_DEFAULT_ &check); |
3672 | ev_check_start (EV_DEFAULT_ &check); |
3532 | ev_loop (EV_DEFAULT_ 0); |
3673 | ev_run (EV_DEFAULT_ 0); |
3533 | |
3674 | |
3534 | =head1 EMBEDDING |
3675 | =head1 EMBEDDING |
3535 | |
3676 | |
3536 | Libev can (and often is) directly embedded into host |
3677 | Libev can (and often is) directly embedded into host |
3537 | applications. Examples of applications that embed it include the Deliantra |
3678 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3622 | define before including (or compiling) any of its files. The default in |
3763 | define before including (or compiling) any of its files. The default in |
3623 | the absence of autoconf is documented for every option. |
3764 | the absence of autoconf is documented for every option. |
3624 | |
3765 | |
3625 | Symbols marked with "(h)" do not change the ABI, and can have different |
3766 | Symbols marked with "(h)" do not change the ABI, and can have different |
3626 | values when compiling libev vs. including F<ev.h>, so it is permissible |
3767 | values when compiling libev vs. including F<ev.h>, so it is permissible |
3627 | to redefine them before including F<ev.h> without breakign compatibility |
3768 | to redefine them before including F<ev.h> without breaking compatibility |
3628 | to a compiled library. All other symbols change the ABI, which means all |
3769 | to a compiled library. All other symbols change the ABI, which means all |
3629 | users of libev and the libev code itself must be compiled with compatible |
3770 | users of libev and the libev code itself must be compiled with compatible |
3630 | settings. |
3771 | settings. |
3631 | |
3772 | |
3632 | =over 4 |
3773 | =over 4 |
|
|
3774 | |
|
|
3775 | =item EV_COMPAT3 (h) |
|
|
3776 | |
|
|
3777 | Backwards compatibility is a major concern for libev. This is why this |
|
|
3778 | release of libev comes with wrappers for the functions and symbols that |
|
|
3779 | have been renamed between libev version 3 and 4. |
|
|
3780 | |
|
|
3781 | You can disable these wrappers (to test compatibility with future |
|
|
3782 | versions) by defining C<EV_COMPAT3> to C<0> when compiling your |
|
|
3783 | sources. This has the additional advantage that you can drop the C<struct> |
|
|
3784 | from C<struct ev_loop> declarations, as libev will provide an C<ev_loop> |
|
|
3785 | typedef in that case. |
|
|
3786 | |
|
|
3787 | In some future version, the default for C<EV_COMPAT3> will become C<0>, |
|
|
3788 | and in some even more future version the compatibility code will be |
|
|
3789 | removed completely. |
3633 | |
3790 | |
3634 | =item EV_STANDALONE (h) |
3791 | =item EV_STANDALONE (h) |
3635 | |
3792 | |
3636 | Must always be C<1> if you do not use autoconf configuration, which |
3793 | Must always be C<1> if you do not use autoconf configuration, which |
3637 | keeps libev from including F<config.h>, and it also defines dummy |
3794 | keeps libev from including F<config.h>, and it also defines dummy |
… | |
… | |
3838 | fine. |
3995 | fine. |
3839 | |
3996 | |
3840 | If your embedding application does not need any priorities, defining these |
3997 | If your embedding application does not need any priorities, defining these |
3841 | both to C<0> will save some memory and CPU. |
3998 | both to C<0> will save some memory and CPU. |
3842 | |
3999 | |
3843 | =item EV_PERIODIC_ENABLE |
4000 | =item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, |
|
|
4001 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
|
|
4002 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3844 | |
4003 | |
3845 | If undefined or defined to be C<1>, then periodic timers are supported. If |
4004 | If undefined or defined to be C<1> (and the platform supports it), then |
3846 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
4005 | the respective watcher type is supported. If defined to be C<0>, then it |
3847 | code. |
4006 | is not. Disabling watcher types mainly saves code size. |
3848 | |
4007 | |
3849 | =item EV_IDLE_ENABLE |
4008 | =item EV_FEATURES |
3850 | |
|
|
3851 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3852 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3853 | code. |
|
|
3854 | |
|
|
3855 | =item EV_EMBED_ENABLE |
|
|
3856 | |
|
|
3857 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3858 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3859 | watcher types, which therefore must not be disabled. |
|
|
3860 | |
|
|
3861 | =item EV_STAT_ENABLE |
|
|
3862 | |
|
|
3863 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3864 | defined to be C<0>, then they are not. |
|
|
3865 | |
|
|
3866 | =item EV_FORK_ENABLE |
|
|
3867 | |
|
|
3868 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3869 | defined to be C<0>, then they are not. |
|
|
3870 | |
|
|
3871 | =item EV_SIGNAL_ENABLE |
|
|
3872 | |
|
|
3873 | If undefined or defined to be C<1>, then signal watchers are supported. If |
|
|
3874 | defined to be C<0>, then they are not. |
|
|
3875 | |
|
|
3876 | =item EV_ASYNC_ENABLE |
|
|
3877 | |
|
|
3878 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3879 | defined to be C<0>, then they are not. |
|
|
3880 | |
|
|
3881 | =item EV_CHILD_ENABLE |
|
|
3882 | |
|
|
3883 | If undefined or defined to be C<1> (and C<_WIN32> is not defined), then |
|
|
3884 | child watchers are supported. If defined to be C<0>, then they are not. |
|
|
3885 | |
|
|
3886 | =item EV_MINIMAL |
|
|
3887 | |
4009 | |
3888 | If you need to shave off some kilobytes of code at the expense of some |
4010 | If you need to shave off some kilobytes of code at the expense of some |
3889 | speed (but with the full API), define this symbol to C<1>. Currently this |
4011 | speed (but with the full API), you can define this symbol to request |
3890 | is used to override some inlining decisions, saves roughly 30% code size |
4012 | certain subsets of functionality. The default is to enable all features |
3891 | on amd64. It also selects a much smaller 2-heap for timer management over |
4013 | that can be enabled on the platform. |
3892 | the default 4-heap. |
|
|
3893 | |
4014 | |
3894 | You can save even more by disabling watcher types you do not need |
4015 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
3895 | and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert> |
4016 | with some broad features you want) and then selectively re-enable |
3896 | (C<-DNDEBUG>) will usually reduce code size a lot. Disabling inotify, |
4017 | additional parts you want, for example if you want everything minimal, |
3897 | eventfd and signalfd will further help, and disabling backends one doesn't |
4018 | but multiple event loop support, async and child watchers and the poll |
3898 | need (e.g. poll, epoll, kqueue, ports) will help further. |
4019 | backend, use this: |
3899 | |
4020 | |
3900 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
4021 | #define EV_FEATURES 0 |
3901 | provide a bare-bones event library. See C<ev.h> for details on what parts |
|
|
3902 | of the API are still available, and do not complain if this subset changes |
|
|
3903 | over time. |
|
|
3904 | |
|
|
3905 | This example set of settings reduces the compiled size of libev from 24Kb |
|
|
3906 | to 8Kb on my GNU/Linux amd64 system (and leaves little in - there is also |
|
|
3907 | an effect on the amount of memory used). With an intelligent-enough linker |
|
|
3908 | further unused functions might be left out as well automatically. |
|
|
3909 | |
|
|
3910 | // tuning and API changes |
|
|
3911 | #define EV_MINIMAL 2 |
|
|
3912 | #define EV_MULTIPLICITY 0 |
4022 | #define EV_MULTIPLICITY 1 |
3913 | #define EV_MINPRI 0 |
|
|
3914 | #define EV_MAXPRI 0 |
|
|
3915 | |
|
|
3916 | // OS-specific backends |
|
|
3917 | #define EV_USE_INOTIFY 0 |
|
|
3918 | #define EV_USE_EVENTFD 0 |
|
|
3919 | #define EV_USE_SIGNALFD 0 |
|
|
3920 | #define EV_USE_REALTIME 0 |
|
|
3921 | #define EV_USE_MONOTONIC 0 |
|
|
3922 | #define EV_USE_CLOCK_SYSCALL 0 |
|
|
3923 | |
|
|
3924 | // disable all backends except select |
|
|
3925 | #define EV_USE_POLL 0 |
4023 | #define EV_USE_POLL 1 |
3926 | #define EV_USE_PORT 0 |
|
|
3927 | #define EV_USE_KQUEUE 0 |
|
|
3928 | #define EV_USE_EPOLL 0 |
|
|
3929 | |
|
|
3930 | // disable all watcher types that cna be disabled |
|
|
3931 | #define EV_STAT_ENABLE 0 |
|
|
3932 | #define EV_PERIODIC_ENABLE 0 |
|
|
3933 | #define EV_IDLE_ENABLE 0 |
|
|
3934 | #define EV_FORK_ENABLE 0 |
|
|
3935 | #define EV_SIGNAL_ENABLE 0 |
|
|
3936 | #define EV_CHILD_ENABLE 0 |
4024 | #define EV_CHILD_ENABLE 1 |
3937 | #define EV_ASYNC_ENABLE 0 |
4025 | #define EV_ASYNC_ENABLE 1 |
3938 | #define EV_EMBED_ENABLE 0 |
4026 | |
|
|
4027 | The actual value is a bitset, it can be a combination of the following |
|
|
4028 | values: |
|
|
4029 | |
|
|
4030 | =over 4 |
|
|
4031 | |
|
|
4032 | =item C<1> - faster/larger code |
|
|
4033 | |
|
|
4034 | Use larger code to speed up some operations. |
|
|
4035 | |
|
|
4036 | Currently this is used to override some inlining decisions (enlarging the |
|
|
4037 | code size by roughly 30% on amd64). |
|
|
4038 | |
|
|
4039 | When optimising for size, use of compiler flags such as C<-Os> with |
|
|
4040 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
|
|
4041 | assertions. |
|
|
4042 | |
|
|
4043 | =item C<2> - faster/larger data structures |
|
|
4044 | |
|
|
4045 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
|
|
4046 | hash table sizes and so on. This will usually further increase code size |
|
|
4047 | and can additionally have an effect on the size of data structures at |
|
|
4048 | runtime. |
|
|
4049 | |
|
|
4050 | =item C<4> - full API configuration |
|
|
4051 | |
|
|
4052 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
|
|
4053 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
|
|
4054 | |
|
|
4055 | =item C<8> - full API |
|
|
4056 | |
|
|
4057 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
|
|
4058 | details on which parts of the API are still available without this |
|
|
4059 | feature, and do not complain if this subset changes over time. |
|
|
4060 | |
|
|
4061 | =item C<16> - enable all optional watcher types |
|
|
4062 | |
|
|
4063 | Enables all optional watcher types. If you want to selectively enable |
|
|
4064 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
4065 | embed, async, child...) you can enable them manually by defining |
|
|
4066 | C<EV_watchertype_ENABLE> to C<1> instead. |
|
|
4067 | |
|
|
4068 | =item C<32> - enable all backends |
|
|
4069 | |
|
|
4070 | This enables all backends - without this feature, you need to enable at |
|
|
4071 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
|
|
4072 | |
|
|
4073 | =item C<64> - enable OS-specific "helper" APIs |
|
|
4074 | |
|
|
4075 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
4076 | default. |
|
|
4077 | |
|
|
4078 | =back |
|
|
4079 | |
|
|
4080 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
|
|
4081 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
4082 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
4083 | watchers, timers and monotonic clock support. |
|
|
4084 | |
|
|
4085 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
4086 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
|
|
4087 | your program might be left out as well - a binary starting a timer and an |
|
|
4088 | I/O watcher then might come out at only 5Kb. |
3939 | |
4089 | |
3940 | =item EV_AVOID_STDIO |
4090 | =item EV_AVOID_STDIO |
3941 | |
4091 | |
3942 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
4092 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
3943 | functions (printf, scanf, perror etc.). This will increase the codesize |
4093 | functions (printf, scanf, perror etc.). This will increase the code size |
3944 | somewhat, but if your program doesn't otherwise depend on stdio and your |
4094 | somewhat, but if your program doesn't otherwise depend on stdio and your |
3945 | libc allows it, this avoids linking in the stdio library which is quite |
4095 | libc allows it, this avoids linking in the stdio library which is quite |
3946 | big. |
4096 | big. |
3947 | |
4097 | |
3948 | Note that error messages might become less precise when this option is |
4098 | Note that error messages might become less precise when this option is |
… | |
… | |
3952 | |
4102 | |
3953 | The highest supported signal number, +1 (or, the number of |
4103 | The highest supported signal number, +1 (or, the number of |
3954 | signals): Normally, libev tries to deduce the maximum number of signals |
4104 | signals): Normally, libev tries to deduce the maximum number of signals |
3955 | automatically, but sometimes this fails, in which case it can be |
4105 | automatically, but sometimes this fails, in which case it can be |
3956 | specified. Also, using a lower number than detected (C<32> should be |
4106 | specified. Also, using a lower number than detected (C<32> should be |
3957 | good for about any system in existance) can save some memory, as libev |
4107 | good for about any system in existence) can save some memory, as libev |
3958 | statically allocates some 12-24 bytes per signal number. |
4108 | statically allocates some 12-24 bytes per signal number. |
3959 | |
4109 | |
3960 | =item EV_PID_HASHSIZE |
4110 | =item EV_PID_HASHSIZE |
3961 | |
4111 | |
3962 | C<ev_child> watchers use a small hash table to distribute workload by |
4112 | C<ev_child> watchers use a small hash table to distribute workload by |
3963 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
4113 | pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled), |
3964 | than enough. If you need to manage thousands of children you might want to |
4114 | usually more than enough. If you need to manage thousands of children you |
3965 | increase this value (I<must> be a power of two). |
4115 | might want to increase this value (I<must> be a power of two). |
3966 | |
4116 | |
3967 | =item EV_INOTIFY_HASHSIZE |
4117 | =item EV_INOTIFY_HASHSIZE |
3968 | |
4118 | |
3969 | C<ev_stat> watchers use a small hash table to distribute workload by |
4119 | C<ev_stat> watchers use a small hash table to distribute workload by |
3970 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
4120 | inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES> |
3971 | usually more than enough. If you need to manage thousands of C<ev_stat> |
4121 | disabled), usually more than enough. If you need to manage thousands of |
3972 | watchers you might want to increase this value (I<must> be a power of |
4122 | C<ev_stat> watchers you might want to increase this value (I<must> be a |
3973 | two). |
4123 | power of two). |
3974 | |
4124 | |
3975 | =item EV_USE_4HEAP |
4125 | =item EV_USE_4HEAP |
3976 | |
4126 | |
3977 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4127 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3978 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
4128 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3979 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
4129 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3980 | faster performance with many (thousands) of watchers. |
4130 | faster performance with many (thousands) of watchers. |
3981 | |
4131 | |
3982 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4132 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3983 | (disabled). |
4133 | will be C<0>. |
3984 | |
4134 | |
3985 | =item EV_HEAP_CACHE_AT |
4135 | =item EV_HEAP_CACHE_AT |
3986 | |
4136 | |
3987 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4137 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3988 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
4138 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3989 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
4139 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3990 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
4140 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3991 | but avoids random read accesses on heap changes. This improves performance |
4141 | but avoids random read accesses on heap changes. This improves performance |
3992 | noticeably with many (hundreds) of watchers. |
4142 | noticeably with many (hundreds) of watchers. |
3993 | |
4143 | |
3994 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4144 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3995 | (disabled). |
4145 | will be C<0>. |
3996 | |
4146 | |
3997 | =item EV_VERIFY |
4147 | =item EV_VERIFY |
3998 | |
4148 | |
3999 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4149 | Controls how much internal verification (see C<ev_verify ()>) will |
4000 | be done: If set to C<0>, no internal verification code will be compiled |
4150 | be done: If set to C<0>, no internal verification code will be compiled |
4001 | in. If set to C<1>, then verification code will be compiled in, but not |
4151 | in. If set to C<1>, then verification code will be compiled in, but not |
4002 | called. If set to C<2>, then the internal verification code will be |
4152 | called. If set to C<2>, then the internal verification code will be |
4003 | called once per loop, which can slow down libev. If set to C<3>, then the |
4153 | called once per loop, which can slow down libev. If set to C<3>, then the |
4004 | verification code will be called very frequently, which will slow down |
4154 | verification code will be called very frequently, which will slow down |
4005 | libev considerably. |
4155 | libev considerably. |
4006 | |
4156 | |
4007 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
4157 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
4008 | C<0>. |
4158 | will be C<0>. |
4009 | |
4159 | |
4010 | =item EV_COMMON |
4160 | =item EV_COMMON |
4011 | |
4161 | |
4012 | By default, all watchers have a C<void *data> member. By redefining |
4162 | By default, all watchers have a C<void *data> member. By redefining |
4013 | this macro to a something else you can include more and other types of |
4163 | this macro to something else you can include more and other types of |
4014 | members. You have to define it each time you include one of the files, |
4164 | members. You have to define it each time you include one of the files, |
4015 | though, and it must be identical each time. |
4165 | though, and it must be identical each time. |
4016 | |
4166 | |
4017 | For example, the perl EV module uses something like this: |
4167 | For example, the perl EV module uses something like this: |
4018 | |
4168 | |
… | |
… | |
4071 | file. |
4221 | file. |
4072 | |
4222 | |
4073 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4223 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4074 | that everybody includes and which overrides some configure choices: |
4224 | that everybody includes and which overrides some configure choices: |
4075 | |
4225 | |
4076 | #define EV_MINIMAL 1 |
4226 | #define EV_FEATURES 8 |
4077 | #define EV_USE_POLL 0 |
4227 | #define EV_USE_SELECT 1 |
4078 | #define EV_MULTIPLICITY 0 |
|
|
4079 | #define EV_PERIODIC_ENABLE 0 |
4228 | #define EV_PREPARE_ENABLE 1 |
|
|
4229 | #define EV_IDLE_ENABLE 1 |
4080 | #define EV_STAT_ENABLE 0 |
4230 | #define EV_SIGNAL_ENABLE 1 |
4081 | #define EV_FORK_ENABLE 0 |
4231 | #define EV_CHILD_ENABLE 1 |
|
|
4232 | #define EV_USE_STDEXCEPT 0 |
4082 | #define EV_CONFIG_H <config.h> |
4233 | #define EV_CONFIG_H <config.h> |
4083 | #define EV_MINPRI 0 |
|
|
4084 | #define EV_MAXPRI 0 |
|
|
4085 | |
4234 | |
4086 | #include "ev++.h" |
4235 | #include "ev++.h" |
4087 | |
4236 | |
4088 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4237 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4089 | |
4238 | |
… | |
… | |
4220 | userdata *u = ev_userdata (EV_A); |
4369 | userdata *u = ev_userdata (EV_A); |
4221 | pthread_mutex_lock (&u->lock); |
4370 | pthread_mutex_lock (&u->lock); |
4222 | } |
4371 | } |
4223 | |
4372 | |
4224 | The event loop thread first acquires the mutex, and then jumps straight |
4373 | The event loop thread first acquires the mutex, and then jumps straight |
4225 | into C<ev_loop>: |
4374 | into C<ev_run>: |
4226 | |
4375 | |
4227 | void * |
4376 | void * |
4228 | l_run (void *thr_arg) |
4377 | l_run (void *thr_arg) |
4229 | { |
4378 | { |
4230 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4379 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4231 | |
4380 | |
4232 | l_acquire (EV_A); |
4381 | l_acquire (EV_A); |
4233 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4382 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4234 | ev_loop (EV_A_ 0); |
4383 | ev_run (EV_A_ 0); |
4235 | l_release (EV_A); |
4384 | l_release (EV_A); |
4236 | |
4385 | |
4237 | return 0; |
4386 | return 0; |
4238 | } |
4387 | } |
4239 | |
4388 | |
… | |
… | |
4291 | |
4440 | |
4292 | =head3 COROUTINES |
4441 | =head3 COROUTINES |
4293 | |
4442 | |
4294 | Libev is very accommodating to coroutines ("cooperative threads"): |
4443 | Libev is very accommodating to coroutines ("cooperative threads"): |
4295 | libev fully supports nesting calls to its functions from different |
4444 | libev fully supports nesting calls to its functions from different |
4296 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4445 | coroutines (e.g. you can call C<ev_run> on the same loop from two |
4297 | different coroutines, and switch freely between both coroutines running |
4446 | different coroutines, and switch freely between both coroutines running |
4298 | the loop, as long as you don't confuse yourself). The only exception is |
4447 | the loop, as long as you don't confuse yourself). The only exception is |
4299 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4448 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4300 | |
4449 | |
4301 | Care has been taken to ensure that libev does not keep local state inside |
4450 | Care has been taken to ensure that libev does not keep local state inside |
4302 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4451 | C<ev_run>, and other calls do not usually allow for coroutine switches as |
4303 | they do not call any callbacks. |
4452 | they do not call any callbacks. |
4304 | |
4453 | |
4305 | =head2 COMPILER WARNINGS |
4454 | =head2 COMPILER WARNINGS |
4306 | |
4455 | |
4307 | Depending on your compiler and compiler settings, you might get no or a |
4456 | Depending on your compiler and compiler settings, you might get no or a |
… | |
… | |
4318 | maintainable. |
4467 | maintainable. |
4319 | |
4468 | |
4320 | And of course, some compiler warnings are just plain stupid, or simply |
4469 | And of course, some compiler warnings are just plain stupid, or simply |
4321 | wrong (because they don't actually warn about the condition their message |
4470 | wrong (because they don't actually warn about the condition their message |
4322 | seems to warn about). For example, certain older gcc versions had some |
4471 | seems to warn about). For example, certain older gcc versions had some |
4323 | warnings that resulted an extreme number of false positives. These have |
4472 | warnings that resulted in an extreme number of false positives. These have |
4324 | been fixed, but some people still insist on making code warn-free with |
4473 | been fixed, but some people still insist on making code warn-free with |
4325 | such buggy versions. |
4474 | such buggy versions. |
4326 | |
4475 | |
4327 | While libev is written to generate as few warnings as possible, |
4476 | While libev is written to generate as few warnings as possible, |
4328 | "warn-free" code is not a goal, and it is recommended not to build libev |
4477 | "warn-free" code is not a goal, and it is recommended not to build libev |
… | |
… | |
4364 | I suggest using suppression lists. |
4513 | I suggest using suppression lists. |
4365 | |
4514 | |
4366 | |
4515 | |
4367 | =head1 PORTABILITY NOTES |
4516 | =head1 PORTABILITY NOTES |
4368 | |
4517 | |
|
|
4518 | =head2 GNU/LINUX 32 BIT LIMITATIONS |
|
|
4519 | |
|
|
4520 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
4521 | interfaces but I<disables> them by default. |
|
|
4522 | |
|
|
4523 | That means that libev compiled in the default environment doesn't support |
|
|
4524 | files larger than 2GiB or so, which mainly affects C<ev_stat> watchers. |
|
|
4525 | |
|
|
4526 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
4527 | by enabling the large file API, which makes them incompatible with the |
|
|
4528 | standard libev compiled for their system. |
|
|
4529 | |
|
|
4530 | Likewise, libev cannot enable the large file API itself as this would |
|
|
4531 | suddenly make it incompatible to the default compile time environment, |
|
|
4532 | i.e. all programs not using special compile switches. |
|
|
4533 | |
|
|
4534 | =head2 OS/X AND DARWIN BUGS |
|
|
4535 | |
|
|
4536 | The whole thing is a bug if you ask me - basically any system interface |
|
|
4537 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
4538 | OpenGL drivers. |
|
|
4539 | |
|
|
4540 | =head3 C<kqueue> is buggy |
|
|
4541 | |
|
|
4542 | The kqueue syscall is broken in all known versions - most versions support |
|
|
4543 | only sockets, many support pipes. |
|
|
4544 | |
|
|
4545 | Libev tries to work around this by not using C<kqueue> by default on this |
|
|
4546 | rotten platform, but of course you can still ask for it when creating a |
|
|
4547 | loop - embedding a socket-only kqueue loop into a select-based one is |
|
|
4548 | probably going to work well. |
|
|
4549 | |
|
|
4550 | =head3 C<poll> is buggy |
|
|
4551 | |
|
|
4552 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
|
|
4553 | implementation by something calling C<kqueue> internally around the 10.5.6 |
|
|
4554 | release, so now C<kqueue> I<and> C<poll> are broken. |
|
|
4555 | |
|
|
4556 | Libev tries to work around this by not using C<poll> by default on |
|
|
4557 | this rotten platform, but of course you can still ask for it when creating |
|
|
4558 | a loop. |
|
|
4559 | |
|
|
4560 | =head3 C<select> is buggy |
|
|
4561 | |
|
|
4562 | All that's left is C<select>, and of course Apple found a way to fuck this |
|
|
4563 | one up as well: On OS/X, C<select> actively limits the number of file |
|
|
4564 | descriptors you can pass in to 1024 - your program suddenly crashes when |
|
|
4565 | you use more. |
|
|
4566 | |
|
|
4567 | There is an undocumented "workaround" for this - defining |
|
|
4568 | C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should> |
|
|
4569 | work on OS/X. |
|
|
4570 | |
|
|
4571 | =head2 SOLARIS PROBLEMS AND WORKAROUNDS |
|
|
4572 | |
|
|
4573 | =head3 C<errno> reentrancy |
|
|
4574 | |
|
|
4575 | The default compile environment on Solaris is unfortunately so |
|
|
4576 | thread-unsafe that you can't even use components/libraries compiled |
|
|
4577 | without C<-D_REENTRANT> in a threaded program, which, of course, isn't |
|
|
4578 | defined by default. A valid, if stupid, implementation choice. |
|
|
4579 | |
|
|
4580 | If you want to use libev in threaded environments you have to make sure |
|
|
4581 | it's compiled with C<_REENTRANT> defined. |
|
|
4582 | |
|
|
4583 | =head3 Event port backend |
|
|
4584 | |
|
|
4585 | The scalable event interface for Solaris is called "event |
|
|
4586 | ports". Unfortunately, this mechanism is very buggy in all major |
|
|
4587 | releases. If you run into high CPU usage, your program freezes or you get |
|
|
4588 | a large number of spurious wakeups, make sure you have all the relevant |
|
|
4589 | and latest kernel patches applied. No, I don't know which ones, but there |
|
|
4590 | are multiple ones to apply, and afterwards, event ports actually work |
|
|
4591 | great. |
|
|
4592 | |
|
|
4593 | If you can't get it to work, you can try running the program by setting |
|
|
4594 | the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and |
|
|
4595 | C<select> backends. |
|
|
4596 | |
|
|
4597 | =head2 AIX POLL BUG |
|
|
4598 | |
|
|
4599 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
|
|
4600 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
4601 | compiled in), which normally isn't a big problem as C<select> works fine |
|
|
4602 | with large bitsets on AIX, and AIX is dead anyway. |
|
|
4603 | |
4369 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4604 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
|
|
4605 | |
|
|
4606 | =head3 General issues |
4370 | |
4607 | |
4371 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4608 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4372 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4609 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4373 | model. Libev still offers limited functionality on this platform in |
4610 | model. Libev still offers limited functionality on this platform in |
4374 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4611 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4375 | descriptors. This only applies when using Win32 natively, not when using |
4612 | descriptors. This only applies when using Win32 natively, not when using |
4376 | e.g. cygwin. |
4613 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
4614 | as every compielr comes with a slightly differently broken/incompatible |
|
|
4615 | environment. |
4377 | |
4616 | |
4378 | Lifting these limitations would basically require the full |
4617 | Lifting these limitations would basically require the full |
4379 | re-implementation of the I/O system. If you are into these kinds of |
4618 | re-implementation of the I/O system. If you are into this kind of thing, |
4380 | things, then note that glib does exactly that for you in a very portable |
4619 | then note that glib does exactly that for you in a very portable way (note |
4381 | way (note also that glib is the slowest event library known to man). |
4620 | also that glib is the slowest event library known to man). |
4382 | |
4621 | |
4383 | There is no supported compilation method available on windows except |
4622 | There is no supported compilation method available on windows except |
4384 | embedding it into other applications. |
4623 | embedding it into other applications. |
4385 | |
4624 | |
4386 | Sensible signal handling is officially unsupported by Microsoft - libev |
4625 | Sensible signal handling is officially unsupported by Microsoft - libev |
… | |
… | |
4414 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4653 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4415 | |
4654 | |
4416 | #include "evwrap.h" |
4655 | #include "evwrap.h" |
4417 | #include "ev.c" |
4656 | #include "ev.c" |
4418 | |
4657 | |
4419 | =over 4 |
|
|
4420 | |
|
|
4421 | =item The winsocket select function |
4658 | =head3 The winsocket C<select> function |
4422 | |
4659 | |
4423 | The winsocket C<select> function doesn't follow POSIX in that it |
4660 | The winsocket C<select> function doesn't follow POSIX in that it |
4424 | requires socket I<handles> and not socket I<file descriptors> (it is |
4661 | requires socket I<handles> and not socket I<file descriptors> (it is |
4425 | also extremely buggy). This makes select very inefficient, and also |
4662 | also extremely buggy). This makes select very inefficient, and also |
4426 | requires a mapping from file descriptors to socket handles (the Microsoft |
4663 | requires a mapping from file descriptors to socket handles (the Microsoft |
… | |
… | |
4435 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4672 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4436 | |
4673 | |
4437 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4674 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4438 | complexity in the O(n²) range when using win32. |
4675 | complexity in the O(n²) range when using win32. |
4439 | |
4676 | |
4440 | =item Limited number of file descriptors |
4677 | =head3 Limited number of file descriptors |
4441 | |
4678 | |
4442 | Windows has numerous arbitrary (and low) limits on things. |
4679 | Windows has numerous arbitrary (and low) limits on things. |
4443 | |
4680 | |
4444 | Early versions of winsocket's select only supported waiting for a maximum |
4681 | Early versions of winsocket's select only supported waiting for a maximum |
4445 | of C<64> handles (probably owning to the fact that all windows kernels |
4682 | of C<64> handles (probably owning to the fact that all windows kernels |
… | |
… | |
4460 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4697 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4461 | (depending on windows version and/or the phase of the moon). To get more, |
4698 | (depending on windows version and/or the phase of the moon). To get more, |
4462 | you need to wrap all I/O functions and provide your own fd management, but |
4699 | you need to wrap all I/O functions and provide your own fd management, but |
4463 | the cost of calling select (O(n²)) will likely make this unworkable. |
4700 | the cost of calling select (O(n²)) will likely make this unworkable. |
4464 | |
4701 | |
4465 | =back |
|
|
4466 | |
|
|
4467 | =head2 PORTABILITY REQUIREMENTS |
4702 | =head2 PORTABILITY REQUIREMENTS |
4468 | |
4703 | |
4469 | In addition to a working ISO-C implementation and of course the |
4704 | In addition to a working ISO-C implementation and of course the |
4470 | backend-specific APIs, libev relies on a few additional extensions: |
4705 | backend-specific APIs, libev relies on a few additional extensions: |
4471 | |
4706 | |
… | |
… | |
4509 | watchers. |
4744 | watchers. |
4510 | |
4745 | |
4511 | =item C<double> must hold a time value in seconds with enough accuracy |
4746 | =item C<double> must hold a time value in seconds with enough accuracy |
4512 | |
4747 | |
4513 | The type C<double> is used to represent timestamps. It is required to |
4748 | The type C<double> is used to represent timestamps. It is required to |
4514 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4749 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
4515 | enough for at least into the year 4000. This requirement is fulfilled by |
4750 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
4751 | (the design goal for libev). This requirement is overfulfilled by |
4516 | implementations implementing IEEE 754, which is basically all existing |
4752 | implementations using IEEE 754, which is basically all existing ones. With |
4517 | ones. With IEEE 754 doubles, you get microsecond accuracy until at least |
4753 | IEEE 754 doubles, you get microsecond accuracy until at least 2200. |
4518 | 2200. |
|
|
4519 | |
4754 | |
4520 | =back |
4755 | =back |
4521 | |
4756 | |
4522 | If you know of other additional requirements drop me a note. |
4757 | If you know of other additional requirements drop me a note. |
4523 | |
4758 | |
… | |
… | |
4591 | involves iterating over all running async watchers or all signal numbers. |
4826 | involves iterating over all running async watchers or all signal numbers. |
4592 | |
4827 | |
4593 | =back |
4828 | =back |
4594 | |
4829 | |
4595 | |
4830 | |
|
|
4831 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
|
|
4832 | |
|
|
4833 | The major version 4 introduced some minor incompatible changes to the API. |
|
|
4834 | |
|
|
4835 | At the moment, the C<ev.h> header file tries to implement superficial |
|
|
4836 | compatibility, so most programs should still compile. Those might be |
|
|
4837 | removed in later versions of libev, so better update early than late. |
|
|
4838 | |
|
|
4839 | =over 4 |
|
|
4840 | |
|
|
4841 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
|
|
4842 | |
|
|
4843 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
|
|
4844 | |
|
|
4845 | ev_loop_destroy (EV_DEFAULT); |
|
|
4846 | ev_loop_fork (EV_DEFAULT); |
|
|
4847 | |
|
|
4848 | =item function/symbol renames |
|
|
4849 | |
|
|
4850 | A number of functions and symbols have been renamed: |
|
|
4851 | |
|
|
4852 | ev_loop => ev_run |
|
|
4853 | EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
4854 | EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
4855 | |
|
|
4856 | ev_unloop => ev_break |
|
|
4857 | EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
4858 | EVUNLOOP_ONE => EVBREAK_ONE |
|
|
4859 | EVUNLOOP_ALL => EVBREAK_ALL |
|
|
4860 | |
|
|
4861 | EV_TIMEOUT => EV_TIMER |
|
|
4862 | |
|
|
4863 | ev_loop_count => ev_iteration |
|
|
4864 | ev_loop_depth => ev_depth |
|
|
4865 | ev_loop_verify => ev_verify |
|
|
4866 | |
|
|
4867 | Most functions working on C<struct ev_loop> objects don't have an |
|
|
4868 | C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and |
|
|
4869 | associated constants have been renamed to not collide with the C<struct |
|
|
4870 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
|
|
4871 | as all other watcher types. Note that C<ev_loop_fork> is still called |
|
|
4872 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
|
|
4873 | typedef. |
|
|
4874 | |
|
|
4875 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
4876 | |
|
|
4877 | The backward compatibility mechanism can be controlled by |
|
|
4878 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
4879 | section. |
|
|
4880 | |
|
|
4881 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
4882 | |
|
|
4883 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
4884 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
4885 | and work, but the library code will of course be larger. |
|
|
4886 | |
|
|
4887 | =back |
|
|
4888 | |
|
|
4889 | |
4596 | =head1 GLOSSARY |
4890 | =head1 GLOSSARY |
4597 | |
4891 | |
4598 | =over 4 |
4892 | =over 4 |
4599 | |
4893 | |
4600 | =item active |
4894 | =item active |
4601 | |
4895 | |
4602 | A watcher is active as long as it has been started (has been attached to |
4896 | A watcher is active as long as it has been started and not yet stopped. |
4603 | an event loop) but not yet stopped (disassociated from the event loop). |
4897 | See L<WATCHER STATES> for details. |
4604 | |
4898 | |
4605 | =item application |
4899 | =item application |
4606 | |
4900 | |
4607 | In this document, an application is whatever is using libev. |
4901 | In this document, an application is whatever is using libev. |
|
|
4902 | |
|
|
4903 | =item backend |
|
|
4904 | |
|
|
4905 | The part of the code dealing with the operating system interfaces. |
4608 | |
4906 | |
4609 | =item callback |
4907 | =item callback |
4610 | |
4908 | |
4611 | The address of a function that is called when some event has been |
4909 | The address of a function that is called when some event has been |
4612 | detected. Callbacks are being passed the event loop, the watcher that |
4910 | detected. Callbacks are being passed the event loop, the watcher that |
4613 | received the event, and the actual event bitset. |
4911 | received the event, and the actual event bitset. |
4614 | |
4912 | |
4615 | =item callback invocation |
4913 | =item callback/watcher invocation |
4616 | |
4914 | |
4617 | The act of calling the callback associated with a watcher. |
4915 | The act of calling the callback associated with a watcher. |
4618 | |
4916 | |
4619 | =item event |
4917 | =item event |
4620 | |
4918 | |
4621 | A change of state of some external event, such as data now being available |
4919 | A change of state of some external event, such as data now being available |
4622 | for reading on a file descriptor, time having passed or simply not having |
4920 | for reading on a file descriptor, time having passed or simply not having |
4623 | any other events happening anymore. |
4921 | any other events happening anymore. |
4624 | |
4922 | |
4625 | In libev, events are represented as single bits (such as C<EV_READ> or |
4923 | In libev, events are represented as single bits (such as C<EV_READ> or |
4626 | C<EV_TIMEOUT>). |
4924 | C<EV_TIMER>). |
4627 | |
4925 | |
4628 | =item event library |
4926 | =item event library |
4629 | |
4927 | |
4630 | A software package implementing an event model and loop. |
4928 | A software package implementing an event model and loop. |
4631 | |
4929 | |
… | |
… | |
4639 | The model used to describe how an event loop handles and processes |
4937 | The model used to describe how an event loop handles and processes |
4640 | watchers and events. |
4938 | watchers and events. |
4641 | |
4939 | |
4642 | =item pending |
4940 | =item pending |
4643 | |
4941 | |
4644 | A watcher is pending as soon as the corresponding event has been detected, |
4942 | A watcher is pending as soon as the corresponding event has been |
4645 | and stops being pending as soon as the watcher will be invoked or its |
4943 | detected. See L<WATCHER STATES> for details. |
4646 | pending status is explicitly cleared by the application. |
|
|
4647 | |
|
|
4648 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4649 | its pending status. |
|
|
4650 | |
4944 | |
4651 | =item real time |
4945 | =item real time |
4652 | |
4946 | |
4653 | The physical time that is observed. It is apparently strictly monotonic :) |
4947 | The physical time that is observed. It is apparently strictly monotonic :) |
4654 | |
4948 | |
… | |
… | |
4661 | =item watcher |
4955 | =item watcher |
4662 | |
4956 | |
4663 | A data structure that describes interest in certain events. Watchers need |
4957 | A data structure that describes interest in certain events. Watchers need |
4664 | to be started (attached to an event loop) before they can receive events. |
4958 | to be started (attached to an event loop) before they can receive events. |
4665 | |
4959 | |
4666 | =item watcher invocation |
|
|
4667 | |
|
|
4668 | The act of calling the callback associated with a watcher. |
|
|
4669 | |
|
|
4670 | =back |
4960 | =back |
4671 | |
4961 | |
4672 | =head1 AUTHOR |
4962 | =head1 AUTHOR |
4673 | |
4963 | |
4674 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
4964 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |