… | |
… | |
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_run (loop, 0); |
61 | ev_run (loop, 0); |
62 | |
62 | |
63 | // unloop was called, so exit |
63 | // break was called, so exit |
64 | return 0; |
64 | return 0; |
65 | } |
65 | } |
66 | |
66 | |
67 | =head1 ABOUT THIS DOCUMENT |
67 | =head1 ABOUT THIS DOCUMENT |
68 | |
68 | |
… | |
… | |
178 | you actually want to know. Also interesting is the combination of |
178 | you actually want to know. Also interesting is the combination of |
179 | C<ev_update_now> and C<ev_now>. |
179 | C<ev_update_now> and C<ev_now>. |
180 | |
180 | |
181 | =item ev_sleep (ev_tstamp interval) |
181 | =item ev_sleep (ev_tstamp interval) |
182 | |
182 | |
183 | Sleep for the given interval: The current thread will be blocked until |
183 | Sleep for the given interval: The current thread will be blocked |
184 | either it is interrupted or the given time interval has passed. Basically |
184 | until either it is interrupted or the given time interval has |
|
|
185 | passed (approximately - it might return a bit earlier even if not |
|
|
186 | interrupted). Returns immediately if C<< interval <= 0 >>. |
|
|
187 | |
185 | this is a sub-second-resolution C<sleep ()>. |
188 | Basically this is a sub-second-resolution C<sleep ()>. |
|
|
189 | |
|
|
190 | The range of the C<interval> is limited - libev only guarantees to work |
|
|
191 | with sleep times of up to one day (C<< interval <= 86400 >>). |
186 | |
192 | |
187 | =item int ev_version_major () |
193 | =item int ev_version_major () |
188 | |
194 | |
189 | =item int ev_version_minor () |
195 | =item int ev_version_minor () |
190 | |
196 | |
… | |
… | |
435 | example) that can't properly initialise their signal masks. |
441 | example) that can't properly initialise their signal masks. |
436 | |
442 | |
437 | =item C<EVFLAG_NOSIGMASK> |
443 | =item C<EVFLAG_NOSIGMASK> |
438 | |
444 | |
439 | When this flag is specified, then libev will avoid to modify the signal |
445 | When this flag is specified, then libev will avoid to modify the signal |
440 | mask. Specifically, this means you ahve to make sure signals are unblocked |
446 | mask. Specifically, this means you have to make sure signals are unblocked |
441 | when you want to receive them. |
447 | when you want to receive them. |
442 | |
448 | |
443 | This behaviour is useful when you want to do your own signal handling, or |
449 | This behaviour is useful when you want to do your own signal handling, or |
444 | want to handle signals only in specific threads and want to avoid libev |
450 | want to handle signals only in specific threads and want to avoid libev |
445 | unblocking the signals. |
451 | unblocking the signals. |
|
|
452 | |
|
|
453 | It's also required by POSIX in a threaded program, as libev calls |
|
|
454 | C<sigprocmask>, whose behaviour is officially unspecified. |
446 | |
455 | |
447 | This flag's behaviour will become the default in future versions of libev. |
456 | This flag's behaviour will become the default in future versions of libev. |
448 | |
457 | |
449 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
458 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
450 | |
459 | |
… | |
… | |
480 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
489 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
481 | |
490 | |
482 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
491 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
483 | kernels). |
492 | kernels). |
484 | |
493 | |
485 | For few fds, this backend is a bit little slower than poll and select, |
494 | For few fds, this backend is a bit little slower than poll and select, but |
486 | but it scales phenomenally better. While poll and select usually scale |
495 | it scales phenomenally better. While poll and select usually scale like |
487 | like O(total_fds) where n is the total number of fds (or the highest fd), |
496 | O(total_fds) where total_fds is the total number of fds (or the highest |
488 | epoll scales either O(1) or O(active_fds). |
497 | fd), epoll scales either O(1) or O(active_fds). |
489 | |
498 | |
490 | The epoll mechanism deserves honorable mention as the most misdesigned |
499 | The epoll mechanism deserves honorable mention as the most misdesigned |
491 | of the more advanced event mechanisms: mere annoyances include silently |
500 | of the more advanced event mechanisms: mere annoyances include silently |
492 | dropping file descriptors, requiring a system call per change per file |
501 | dropping file descriptors, requiring a system call per change per file |
493 | descriptor (and unnecessary guessing of parameters), problems with dup, |
502 | descriptor (and unnecessary guessing of parameters), problems with dup, |
… | |
… | |
496 | 0.1ms) and so on. The biggest issue is fork races, however - if a program |
505 | 0.1ms) and so on. The biggest issue is fork races, however - if a program |
497 | forks then I<both> parent and child process have to recreate the epoll |
506 | forks then I<both> parent and child process have to recreate the epoll |
498 | set, which can take considerable time (one syscall per file descriptor) |
507 | set, which can take considerable time (one syscall per file descriptor) |
499 | and is of course hard to detect. |
508 | and is of course hard to detect. |
500 | |
509 | |
501 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, but |
510 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, |
502 | of course I<doesn't>, and epoll just loves to report events for totally |
511 | but of course I<doesn't>, and epoll just loves to report events for |
503 | I<different> file descriptors (even already closed ones, so one cannot |
512 | totally I<different> file descriptors (even already closed ones, so |
504 | even remove them from the set) than registered in the set (especially |
513 | one cannot even remove them from the set) than registered in the set |
505 | on SMP systems). Libev tries to counter these spurious notifications by |
514 | (especially on SMP systems). Libev tries to counter these spurious |
506 | employing an additional generation counter and comparing that against the |
515 | notifications by employing an additional generation counter and comparing |
507 | events to filter out spurious ones, recreating the set when required. Last |
516 | that against the events to filter out spurious ones, recreating the set |
|
|
517 | when required. Epoll also erroneously rounds down timeouts, but gives you |
|
|
518 | no way to know when and by how much, so sometimes you have to busy-wait |
|
|
519 | because epoll returns immediately despite a nonzero timeout. And last |
508 | not least, it also refuses to work with some file descriptors which work |
520 | not least, it also refuses to work with some file descriptors which work |
509 | perfectly fine with C<select> (files, many character devices...). |
521 | perfectly fine with C<select> (files, many character devices...). |
510 | |
522 | |
511 | Epoll is truly the train wreck analog among event poll mechanisms, |
523 | Epoll is truly the train wreck among event poll mechanisms, a frankenpoll, |
512 | a frankenpoll, cobbled together in a hurry, no thought to design or |
524 | cobbled together in a hurry, no thought to design or interaction with |
513 | interaction with others. |
525 | others. Oh, the pain, will it ever stop... |
514 | |
526 | |
515 | While stopping, setting and starting an I/O watcher in the same iteration |
527 | While stopping, setting and starting an I/O watcher in the same iteration |
516 | will result in some caching, there is still a system call per such |
528 | will result in some caching, there is still a system call per such |
517 | incident (because the same I<file descriptor> could point to a different |
529 | incident (because the same I<file descriptor> could point to a different |
518 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
530 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
… | |
… | |
596 | among the OS-specific backends (I vastly prefer correctness over speed |
608 | among the OS-specific backends (I vastly prefer correctness over speed |
597 | hacks). |
609 | hacks). |
598 | |
610 | |
599 | On the negative side, the interface is I<bizarre> - so bizarre that |
611 | On the negative side, the interface is I<bizarre> - so bizarre that |
600 | even sun itself gets it wrong in their code examples: The event polling |
612 | even sun itself gets it wrong in their code examples: The event polling |
601 | function sometimes returning events to the caller even though an error |
613 | function sometimes returns events to the caller even though an error |
602 | occurred, but with no indication whether it has done so or not (yes, it's |
614 | occurred, but with no indication whether it has done so or not (yes, it's |
603 | even documented that way) - deadly for edge-triggered interfaces where |
615 | even documented that way) - deadly for edge-triggered interfaces where you |
604 | you absolutely have to know whether an event occurred or not because you |
616 | absolutely have to know whether an event occurred or not because you have |
605 | have to re-arm the watcher. |
617 | to re-arm the watcher. |
606 | |
618 | |
607 | Fortunately libev seems to be able to work around these idiocies. |
619 | Fortunately libev seems to be able to work around these idiocies. |
608 | |
620 | |
609 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
621 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
610 | C<EVBACKEND_POLL>. |
622 | C<EVBACKEND_POLL>. |
… | |
… | |
822 | This is useful if you are waiting for some external event in conjunction |
834 | This is useful if you are waiting for some external event in conjunction |
823 | with something not expressible using other libev watchers (i.e. "roll your |
835 | with something not expressible using other libev watchers (i.e. "roll your |
824 | own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
836 | own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
825 | usually a better approach for this kind of thing. |
837 | usually a better approach for this kind of thing. |
826 | |
838 | |
827 | Here are the gory details of what C<ev_run> does: |
839 | Here are the gory details of what C<ev_run> does (this is for your |
|
|
840 | understanding, not a guarantee that things will work exactly like this in |
|
|
841 | future versions): |
828 | |
842 | |
829 | - Increment loop depth. |
843 | - Increment loop depth. |
830 | - Reset the ev_break status. |
844 | - Reset the ev_break status. |
831 | - Before the first iteration, call any pending watchers. |
845 | - Before the first iteration, call any pending watchers. |
832 | LOOP: |
846 | LOOP: |
… | |
… | |
865 | anymore. |
879 | anymore. |
866 | |
880 | |
867 | ... queue jobs here, make sure they register event watchers as long |
881 | ... queue jobs here, make sure they register event watchers as long |
868 | ... as they still have work to do (even an idle watcher will do..) |
882 | ... as they still have work to do (even an idle watcher will do..) |
869 | ev_run (my_loop, 0); |
883 | ev_run (my_loop, 0); |
870 | ... jobs done or somebody called unloop. yeah! |
884 | ... jobs done or somebody called break. yeah! |
871 | |
885 | |
872 | =item ev_break (loop, how) |
886 | =item ev_break (loop, how) |
873 | |
887 | |
874 | Can be used to make a call to C<ev_run> return early (but only after it |
888 | Can be used to make a call to C<ev_run> return early (but only after it |
875 | has processed all outstanding events). The C<how> argument must be either |
889 | has processed all outstanding events). The C<how> argument must be either |
… | |
… | |
938 | overhead for the actual polling but can deliver many events at once. |
952 | overhead for the actual polling but can deliver many events at once. |
939 | |
953 | |
940 | By setting a higher I<io collect interval> you allow libev to spend more |
954 | By setting a higher I<io collect interval> you allow libev to spend more |
941 | time collecting I/O events, so you can handle more events per iteration, |
955 | time collecting I/O events, so you can handle more events per iteration, |
942 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
956 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
943 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
957 | C<ev_timer>) will not be affected. Setting this to a non-null value will |
944 | introduce an additional C<ev_sleep ()> call into most loop iterations. The |
958 | introduce an additional C<ev_sleep ()> call into most loop iterations. The |
945 | sleep time ensures that libev will not poll for I/O events more often then |
959 | sleep time ensures that libev will not poll for I/O events more often then |
946 | once per this interval, on average. |
960 | once per this interval, on average (as long as the host time resolution is |
|
|
961 | good enough). |
947 | |
962 | |
948 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
963 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
949 | to spend more time collecting timeouts, at the expense of increased |
964 | to spend more time collecting timeouts, at the expense of increased |
950 | latency/jitter/inexactness (the watcher callback will be called |
965 | latency/jitter/inexactness (the watcher callback will be called |
951 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
966 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
… | |
… | |
1371 | |
1386 | |
1372 | =over 4 |
1387 | =over 4 |
1373 | |
1388 | |
1374 | =item initialiased |
1389 | =item initialiased |
1375 | |
1390 | |
1376 | Before a watcher can be registered with the event looop it has to be |
1391 | Before a watcher can be registered with the event loop it has to be |
1377 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1392 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1378 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1393 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1379 | |
1394 | |
1380 | In this state it is simply some block of memory that is suitable for use |
1395 | In this state it is simply some block of memory that is suitable for |
1381 | in an event loop. It can be moved around, freed, reused etc. at will. |
1396 | use in an event loop. It can be moved around, freed, reused etc. at |
|
|
1397 | will - as long as you either keep the memory contents intact, or call |
|
|
1398 | C<ev_TYPE_init> again. |
1382 | |
1399 | |
1383 | =item started/running/active |
1400 | =item started/running/active |
1384 | |
1401 | |
1385 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
1402 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
1386 | property of the event loop, and is actively waiting for events. While in |
1403 | property of the event loop, and is actively waiting for events. While in |
… | |
… | |
1414 | latter will clear any pending state the watcher might be in, regardless |
1431 | latter will clear any pending state the watcher might be in, regardless |
1415 | of whether it was active or not, so stopping a watcher explicitly before |
1432 | of whether it was active or not, so stopping a watcher explicitly before |
1416 | freeing it is often a good idea. |
1433 | freeing it is often a good idea. |
1417 | |
1434 | |
1418 | While stopped (and not pending) the watcher is essentially in the |
1435 | While stopped (and not pending) the watcher is essentially in the |
1419 | initialised state, that is it can be reused, moved, modified in any way |
1436 | initialised state, that is, it can be reused, moved, modified in any way |
1420 | you wish. |
1437 | you wish (but when you trash the memory block, you need to C<ev_TYPE_init> |
|
|
1438 | it again). |
1421 | |
1439 | |
1422 | =back |
1440 | =back |
1423 | |
1441 | |
1424 | =head2 WATCHER PRIORITY MODELS |
1442 | =head2 WATCHER PRIORITY MODELS |
1425 | |
1443 | |
… | |
… | |
2005 | keep up with the timer (because it takes longer than those 10 seconds to |
2023 | keep up with the timer (because it takes longer than those 10 seconds to |
2006 | do stuff) the timer will not fire more than once per event loop iteration. |
2024 | do stuff) the timer will not fire more than once per event loop iteration. |
2007 | |
2025 | |
2008 | =item ev_timer_again (loop, ev_timer *) |
2026 | =item ev_timer_again (loop, ev_timer *) |
2009 | |
2027 | |
2010 | This will act as if the timer timed out and restart it again if it is |
2028 | This will act as if the timer timed out and restarts it again if it is |
2011 | repeating. The exact semantics are: |
2029 | repeating. The exact semantics are: |
2012 | |
2030 | |
2013 | If the timer is pending, its pending status is cleared. |
2031 | If the timer is pending, its pending status is cleared. |
2014 | |
2032 | |
2015 | If the timer is started but non-repeating, stop it (as if it timed out). |
2033 | If the timer is started but non-repeating, stop it (as if it timed out). |
… | |
… | |
2145 | |
2163 | |
2146 | Another way to think about it (for the mathematically inclined) is that |
2164 | Another way to think about it (for the mathematically inclined) is that |
2147 | C<ev_periodic> will try to run the callback in this mode at the next possible |
2165 | C<ev_periodic> will try to run the callback in this mode at the next possible |
2148 | time where C<time = offset (mod interval)>, regardless of any time jumps. |
2166 | time where C<time = offset (mod interval)>, regardless of any time jumps. |
2149 | |
2167 | |
2150 | For numerical stability it is preferable that the C<offset> value is near |
2168 | The C<interval> I<MUST> be positive, and for numerical stability, the |
2151 | C<ev_now ()> (the current time), but there is no range requirement for |
2169 | interval value should be higher than C<1/8192> (which is around 100 |
2152 | this value, and in fact is often specified as zero. |
2170 | microseconds) and C<offset> should be higher than C<0> and should have |
|
|
2171 | at most a similar magnitude as the current time (say, within a factor of |
|
|
2172 | ten). Typical values for offset are, in fact, C<0> or something between |
|
|
2173 | C<0> and C<interval>, which is also the recommended range. |
2153 | |
2174 | |
2154 | Note also that there is an upper limit to how often a timer can fire (CPU |
2175 | Note also that there is an upper limit to how often a timer can fire (CPU |
2155 | speed for example), so if C<interval> is very small then timing stability |
2176 | speed for example), so if C<interval> is very small then timing stability |
2156 | will of course deteriorate. Libev itself tries to be exact to be about one |
2177 | will of course deteriorate. Libev itself tries to be exact to be about one |
2157 | millisecond (if the OS supports it and the machine is fast enough). |
2178 | millisecond (if the OS supports it and the machine is fast enough). |
… | |
… | |
2300 | =head3 The special problem of inheritance over fork/execve/pthread_create |
2321 | =head3 The special problem of inheritance over fork/execve/pthread_create |
2301 | |
2322 | |
2302 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2323 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2303 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2324 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2304 | stopping it again), that is, libev might or might not block the signal, |
2325 | stopping it again), that is, libev might or might not block the signal, |
2305 | and might or might not set or restore the installed signal handler. |
2326 | and might or might not set or restore the installed signal handler (but |
|
|
2327 | see C<EVFLAG_NOSIGMASK>). |
2306 | |
2328 | |
2307 | While this does not matter for the signal disposition (libev never |
2329 | While this does not matter for the signal disposition (libev never |
2308 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
2330 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
2309 | C<execve>), this matters for the signal mask: many programs do not expect |
2331 | C<execve>), this matters for the signal mask: many programs do not expect |
2310 | certain signals to be blocked. |
2332 | certain signals to be blocked. |
… | |
… | |
3181 | atexit (program_exits); |
3203 | atexit (program_exits); |
3182 | |
3204 | |
3183 | |
3205 | |
3184 | =head2 C<ev_async> - how to wake up an event loop |
3206 | =head2 C<ev_async> - how to wake up an event loop |
3185 | |
3207 | |
3186 | In general, you cannot use an C<ev_run> from multiple threads or other |
3208 | In general, you cannot use an C<ev_loop> from multiple threads or other |
3187 | asynchronous sources such as signal handlers (as opposed to multiple event |
3209 | asynchronous sources such as signal handlers (as opposed to multiple event |
3188 | loops - those are of course safe to use in different threads). |
3210 | loops - those are of course safe to use in different threads). |
3189 | |
3211 | |
3190 | Sometimes, however, you need to wake up an event loop you do not control, |
3212 | Sometimes, however, you need to wake up an event loop you do not control, |
3191 | for example because it belongs to another thread. This is what C<ev_async> |
3213 | for example because it belongs to another thread. This is what C<ev_async> |
… | |
… | |
3198 | C<ev_async_sent> calls). In fact, you could use signal watchers as a kind |
3220 | C<ev_async_sent> calls). In fact, you could use signal watchers as a kind |
3199 | of "global async watchers" by using a watcher on an otherwise unused |
3221 | of "global async watchers" by using a watcher on an otherwise unused |
3200 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3222 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3201 | even without knowing which loop owns the signal. |
3223 | even without knowing which loop owns the signal. |
3202 | |
3224 | |
3203 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
|
|
3204 | just the default loop. |
|
|
3205 | |
|
|
3206 | =head3 Queueing |
3225 | =head3 Queueing |
3207 | |
3226 | |
3208 | C<ev_async> does not support queueing of data in any way. The reason |
3227 | C<ev_async> does not support queueing of data in any way. The reason |
3209 | is that the author does not know of a simple (or any) algorithm for a |
3228 | is that the author does not know of a simple (or any) algorithm for a |
3210 | multiple-writer-single-reader queue that works in all cases and doesn't |
3229 | multiple-writer-single-reader queue that works in all cases and doesn't |
… | |
… | |
3301 | trust me. |
3320 | trust me. |
3302 | |
3321 | |
3303 | =item ev_async_send (loop, ev_async *) |
3322 | =item ev_async_send (loop, ev_async *) |
3304 | |
3323 | |
3305 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
3324 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
3306 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
3325 | an C<EV_ASYNC> event on the watcher into the event loop, and instantly |
|
|
3326 | returns. |
|
|
3327 | |
3307 | C<ev_feed_event>, this call is safe to do from other threads, signal or |
3328 | Unlike C<ev_feed_event>, this call is safe to do from other threads, |
3308 | similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding |
3329 | signal or similar contexts (see the discussion of C<EV_ATOMIC_T> in the |
3309 | section below on what exactly this means). |
3330 | embedding section below on what exactly this means). |
3310 | |
3331 | |
3311 | Note that, as with other watchers in libev, multiple events might get |
3332 | Note that, as with other watchers in libev, multiple events might get |
3312 | compressed into a single callback invocation (another way to look at this |
3333 | compressed into a single callback invocation (another way to look at |
3313 | is that C<ev_async> watchers are level-triggered, set on C<ev_async_send>, |
3334 | this is that C<ev_async> watchers are level-triggered: they are set on |
3314 | reset when the event loop detects that). |
3335 | C<ev_async_send>, reset when the event loop detects that). |
3315 | |
3336 | |
3316 | This call incurs the overhead of a system call only once per event loop |
3337 | This call incurs the overhead of at most one extra system call per event |
3317 | iteration, so while the overhead might be noticeable, it doesn't apply to |
3338 | loop iteration, if the event loop is blocked, and no syscall at all if |
3318 | repeated calls to C<ev_async_send> for the same event loop. |
3339 | the event loop (or your program) is processing events. That means that |
|
|
3340 | repeated calls are basically free (there is no need to avoid calls for |
|
|
3341 | performance reasons) and that the overhead becomes smaller (typically |
|
|
3342 | zero) under load. |
3319 | |
3343 | |
3320 | =item bool = ev_async_pending (ev_async *) |
3344 | =item bool = ev_async_pending (ev_async *) |
3321 | |
3345 | |
3322 | Returns a non-zero value when C<ev_async_send> has been called on the |
3346 | Returns a non-zero value when C<ev_async_send> has been called on the |
3323 | watcher but the event has not yet been processed (or even noted) by the |
3347 | watcher but the event has not yet been processed (or even noted) by the |
… | |
… | |
3504 | exit_main_loop = exit_nested_loop = 1; |
3528 | exit_main_loop = exit_nested_loop = 1; |
3505 | |
3529 | |
3506 | =head2 THREAD LOCKING EXAMPLE |
3530 | =head2 THREAD LOCKING EXAMPLE |
3507 | |
3531 | |
3508 | Here is a fictitious example of how to run an event loop in a different |
3532 | Here is a fictitious example of how to run an event loop in a different |
3509 | thread than where callbacks are being invoked and watchers are |
3533 | thread from where callbacks are being invoked and watchers are |
3510 | created/added/removed. |
3534 | created/added/removed. |
3511 | |
3535 | |
3512 | For a real-world example, see the C<EV::Loop::Async> perl module, |
3536 | For a real-world example, see the C<EV::Loop::Async> perl module, |
3513 | which uses exactly this technique (which is suited for many high-level |
3537 | which uses exactly this technique (which is suited for many high-level |
3514 | languages). |
3538 | languages). |
… | |
… | |
3540 | // now associate this with the loop |
3564 | // now associate this with the loop |
3541 | ev_set_userdata (EV_A_ u); |
3565 | ev_set_userdata (EV_A_ u); |
3542 | ev_set_invoke_pending_cb (EV_A_ l_invoke); |
3566 | ev_set_invoke_pending_cb (EV_A_ l_invoke); |
3543 | ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
3567 | ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
3544 | |
3568 | |
3545 | // then create the thread running ev_loop |
3569 | // then create the thread running ev_run |
3546 | pthread_create (&u->tid, 0, l_run, EV_A); |
3570 | pthread_create (&u->tid, 0, l_run, EV_A); |
3547 | } |
3571 | } |
3548 | |
3572 | |
3549 | The callback for the C<ev_async> watcher does nothing: the watcher is used |
3573 | The callback for the C<ev_async> watcher does nothing: the watcher is used |
3550 | solely to wake up the event loop so it takes notice of any new watchers |
3574 | solely to wake up the event loop so it takes notice of any new watchers |
… | |
… | |
4195 | F<event.h> that are not directly supported by the libev core alone. |
4219 | F<event.h> that are not directly supported by the libev core alone. |
4196 | |
4220 | |
4197 | In standalone mode, libev will still try to automatically deduce the |
4221 | In standalone mode, libev will still try to automatically deduce the |
4198 | configuration, but has to be more conservative. |
4222 | configuration, but has to be more conservative. |
4199 | |
4223 | |
|
|
4224 | =item EV_USE_FLOOR |
|
|
4225 | |
|
|
4226 | If defined to be C<1>, libev will use the C<floor ()> function for its |
|
|
4227 | periodic reschedule calculations, otherwise libev will fall back on a |
|
|
4228 | portable (slower) implementation. If you enable this, you usually have to |
|
|
4229 | link against libm or something equivalent. Enabling this when the C<floor> |
|
|
4230 | function is not available will fail, so the safe default is to not enable |
|
|
4231 | this. |
|
|
4232 | |
4200 | =item EV_USE_MONOTONIC |
4233 | =item EV_USE_MONOTONIC |
4201 | |
4234 | |
4202 | If defined to be C<1>, libev will try to detect the availability of the |
4235 | If defined to be C<1>, libev will try to detect the availability of the |
4203 | monotonic clock option at both compile time and runtime. Otherwise no |
4236 | monotonic clock option at both compile time and runtime. Otherwise no |
4204 | use of the monotonic clock option will be attempted. If you enable this, |
4237 | use of the monotonic clock option will be attempted. If you enable this, |
… | |
… | |
4336 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4369 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4337 | |
4370 | |
4338 | =item EV_ATOMIC_T |
4371 | =item EV_ATOMIC_T |
4339 | |
4372 | |
4340 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4373 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4341 | access is atomic with respect to other threads or signal contexts. No such |
4374 | access is atomic and serialised with respect to other threads or signal |
4342 | type is easily found in the C language, so you can provide your own type |
4375 | contexts. No such type is easily found in the C language, so you can |
4343 | that you know is safe for your purposes. It is used both for signal handler "locking" |
4376 | provide your own type that you know is safe for your purposes. It is used |
4344 | as well as for signal and thread safety in C<ev_async> watchers. |
4377 | both for signal handler "locking" as well as for signal and thread safety |
|
|
4378 | in C<ev_async> watchers. |
4345 | |
4379 | |
4346 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4380 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4347 | (from F<signal.h>), which is usually good enough on most platforms. |
4381 | (from F<signal.h>), which is usually good enough on most platforms. |
4348 | |
4382 | |
4349 | =item EV_H (h) |
4383 | =item EV_H (h) |
… | |
… | |
4871 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4905 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4872 | model. Libev still offers limited functionality on this platform in |
4906 | model. Libev still offers limited functionality on this platform in |
4873 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4907 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4874 | descriptors. This only applies when using Win32 natively, not when using |
4908 | descriptors. This only applies when using Win32 natively, not when using |
4875 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
4909 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
4876 | as every compielr comes with a slightly differently broken/incompatible |
4910 | as every compiler comes with a slightly differently broken/incompatible |
4877 | environment. |
4911 | environment. |
4878 | |
4912 | |
4879 | Lifting these limitations would basically require the full |
4913 | Lifting these limitations would basically require the full |
4880 | re-implementation of the I/O system. If you are into this kind of thing, |
4914 | re-implementation of the I/O system. If you are into this kind of thing, |
4881 | then note that glib does exactly that for you in a very portable way (note |
4915 | then note that glib does exactly that for you in a very portable way (note |
… | |
… | |
5014 | |
5048 | |
5015 | The type C<double> is used to represent timestamps. It is required to |
5049 | The type C<double> is used to represent timestamps. It is required to |
5016 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
5050 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
5017 | good enough for at least into the year 4000 with millisecond accuracy |
5051 | good enough for at least into the year 4000 with millisecond accuracy |
5018 | (the design goal for libev). This requirement is overfulfilled by |
5052 | (the design goal for libev). This requirement is overfulfilled by |
5019 | implementations using IEEE 754, which is basically all existing ones. With |
5053 | implementations using IEEE 754, which is basically all existing ones. |
|
|
5054 | |
5020 | IEEE 754 doubles, you get microsecond accuracy until at least 2200. |
5055 | With IEEE 754 doubles, you get microsecond accuracy until at least the |
|
|
5056 | year 2255 (and millisecond accuray till the year 287396 - by then, libev |
|
|
5057 | is either obsolete or somebody patched it to use C<long double> or |
|
|
5058 | something like that, just kidding). |
5021 | |
5059 | |
5022 | =back |
5060 | =back |
5023 | |
5061 | |
5024 | If you know of other additional requirements drop me a note. |
5062 | If you know of other additional requirements drop me a note. |
5025 | |
5063 | |
… | |
… | |
5087 | =item Processing ev_async_send: O(number_of_async_watchers) |
5125 | =item Processing ev_async_send: O(number_of_async_watchers) |
5088 | |
5126 | |
5089 | =item Processing signals: O(max_signal_number) |
5127 | =item Processing signals: O(max_signal_number) |
5090 | |
5128 | |
5091 | Sending involves a system call I<iff> there were no other C<ev_async_send> |
5129 | Sending involves a system call I<iff> there were no other C<ev_async_send> |
5092 | calls in the current loop iteration. Checking for async and signal events |
5130 | calls in the current loop iteration and the loop is currently |
|
|
5131 | blocked. Checking for async and signal events involves iterating over all |
5093 | involves iterating over all running async watchers or all signal numbers. |
5132 | running async watchers or all signal numbers. |
5094 | |
5133 | |
5095 | =back |
5134 | =back |
5096 | |
5135 | |
5097 | |
5136 | |
5098 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
5137 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
… | |
… | |
5215 | The physical time that is observed. It is apparently strictly monotonic :) |
5254 | The physical time that is observed. It is apparently strictly monotonic :) |
5216 | |
5255 | |
5217 | =item wall-clock time |
5256 | =item wall-clock time |
5218 | |
5257 | |
5219 | The time and date as shown on clocks. Unlike real time, it can actually |
5258 | The time and date as shown on clocks. Unlike real time, it can actually |
5220 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
5259 | be wrong and jump forwards and backwards, e.g. when you adjust your |
5221 | clock. |
5260 | clock. |
5222 | |
5261 | |
5223 | =item watcher |
5262 | =item watcher |
5224 | |
5263 | |
5225 | A data structure that describes interest in certain events. Watchers need |
5264 | A data structure that describes interest in certain events. Watchers need |
… | |
… | |
5228 | =back |
5267 | =back |
5229 | |
5268 | |
5230 | =head1 AUTHOR |
5269 | =head1 AUTHOR |
5231 | |
5270 | |
5232 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
5271 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
5233 | Magnusson and Emanuele Giaquinta. |
5272 | Magnusson and Emanuele Giaquinta, and minor corrections by many others. |
5234 | |
5273 | |