… | |
… | |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
8 | |
8 | |
9 | =head1 EXAMPLE PROGRAM |
9 | =head2 EXAMPLE PROGRAM |
10 | |
10 | |
11 | #include <ev.h> |
11 | #include <ev.h> |
12 | |
12 | |
13 | ev_io stdin_watcher; |
13 | ev_io stdin_watcher; |
14 | ev_timer timeout_watcher; |
14 | ev_timer timeout_watcher; |
… | |
… | |
65 | You register interest in certain events by registering so-called I<event |
65 | You register interest in certain events by registering so-called I<event |
66 | watchers>, which are relatively small C structures you initialise with the |
66 | watchers>, which are relatively small C structures you initialise with the |
67 | details of the event, and then hand it over to libev by I<starting> the |
67 | details of the event, and then hand it over to libev by I<starting> the |
68 | watcher. |
68 | watcher. |
69 | |
69 | |
70 | =head1 FEATURES |
70 | =head2 FEATURES |
71 | |
71 | |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
… | |
… | |
82 | |
82 | |
83 | It also is quite fast (see this |
83 | It also is quite fast (see this |
84 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
84 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
85 | for example). |
85 | for example). |
86 | |
86 | |
87 | =head1 CONVENTIONS |
87 | =head2 CONVENTIONS |
88 | |
88 | |
89 | Libev is very configurable. In this manual the default configuration will |
89 | Libev is very configurable. In this manual the default configuration will |
90 | be described, which supports multiple event loops. For more info about |
90 | be described, which supports multiple event loops. For more info about |
91 | various configuration options please have a look at B<EMBED> section in |
91 | various configuration options please have a look at B<EMBED> section in |
92 | this manual. If libev was configured without support for multiple event |
92 | this manual. If libev was configured without support for multiple event |
93 | loops, then all functions taking an initial argument of name C<loop> |
93 | loops, then all functions taking an initial argument of name C<loop> |
94 | (which is always of type C<struct ev_loop *>) will not have this argument. |
94 | (which is always of type C<struct ev_loop *>) will not have this argument. |
95 | |
95 | |
96 | =head1 TIME REPRESENTATION |
96 | =head2 TIME REPRESENTATION |
97 | |
97 | |
98 | Libev represents time as a single floating point number, representing the |
98 | Libev represents time as a single floating point number, representing the |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
100 | the beginning of 1970, details are complicated, don't ask). This type is |
100 | the beginning of 1970, details are complicated, don't ask). This type is |
101 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
101 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
… | |
… | |
306 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
306 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
307 | |
307 | |
308 | This is your standard select(2) backend. Not I<completely> standard, as |
308 | This is your standard select(2) backend. Not I<completely> standard, as |
309 | libev tries to roll its own fd_set with no limits on the number of fds, |
309 | libev tries to roll its own fd_set with no limits on the number of fds, |
310 | but if that fails, expect a fairly low limit on the number of fds when |
310 | but if that fails, expect a fairly low limit on the number of fds when |
311 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
311 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
312 | the fastest backend for a low number of fds. |
312 | usually the fastest backend for a low number of (low-numbered :) fds. |
|
|
313 | |
|
|
314 | To get good performance out of this backend you need a high amount of |
|
|
315 | parallelity (most of the file descriptors should be busy). If you are |
|
|
316 | writing a server, you should C<accept ()> in a loop to accept as many |
|
|
317 | connections as possible during one iteration. You might also want to have |
|
|
318 | a look at C<ev_set_io_collect_interval ()> to increase the amount of |
|
|
319 | readyness notifications you get per iteration. |
313 | |
320 | |
314 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
321 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
315 | |
322 | |
316 | And this is your standard poll(2) backend. It's more complicated than |
323 | And this is your standard poll(2) backend. It's more complicated |
317 | select, but handles sparse fds better and has no artificial limit on the |
324 | than select, but handles sparse fds better and has no artificial |
318 | number of fds you can use (except it will slow down considerably with a |
325 | limit on the number of fds you can use (except it will slow down |
319 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
326 | considerably with a lot of inactive fds). It scales similarly to select, |
|
|
327 | i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for |
|
|
328 | performance tips. |
320 | |
329 | |
321 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
330 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
322 | |
331 | |
323 | For few fds, this backend is a bit little slower than poll and select, |
332 | For few fds, this backend is a bit little slower than poll and select, |
324 | but it scales phenomenally better. While poll and select usually scale |
333 | but it scales phenomenally better. While poll and select usually scale |
325 | like O(total_fds) where n is the total number of fds (or the highest fd), |
334 | like O(total_fds) where n is the total number of fds (or the highest fd), |
326 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
335 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
327 | of shortcomings, such as silently dropping events in some hard-to-detect |
336 | of shortcomings, such as silently dropping events in some hard-to-detect |
328 | cases and rewiring a syscall per fd change, no fork support and bad |
337 | cases and rewiring a syscall per fd change, no fork support and bad |
329 | support for dup: |
338 | support for dup. |
330 | |
339 | |
331 | While stopping, setting and starting an I/O watcher in the same iteration |
340 | While stopping, setting and starting an I/O watcher in the same iteration |
332 | will result in some caching, there is still a syscall per such incident |
341 | will result in some caching, there is still a syscall per such incident |
333 | (because the fd could point to a different file description now), so its |
342 | (because the fd could point to a different file description now), so its |
334 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
343 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
335 | very well if you register events for both fds. |
344 | very well if you register events for both fds. |
336 | |
345 | |
337 | Please note that epoll sometimes generates spurious notifications, so you |
346 | Please note that epoll sometimes generates spurious notifications, so you |
338 | need to use non-blocking I/O or other means to avoid blocking when no data |
347 | need to use non-blocking I/O or other means to avoid blocking when no data |
339 | (or space) is available. |
348 | (or space) is available. |
|
|
349 | |
|
|
350 | Best performance from this backend is achieved by not unregistering all |
|
|
351 | watchers for a file descriptor until it has been closed, if possible, i.e. |
|
|
352 | keep at least one watcher active per fd at all times. |
|
|
353 | |
|
|
354 | While nominally embeddeble in other event loops, this feature is broken in |
|
|
355 | all kernel versions tested so far. |
340 | |
356 | |
341 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
357 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
342 | |
358 | |
343 | Kqueue deserves special mention, as at the time of this writing, it |
359 | Kqueue deserves special mention, as at the time of this writing, it |
344 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
360 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
… | |
… | |
357 | course). While stopping, setting and starting an I/O watcher does never |
373 | course). While stopping, setting and starting an I/O watcher does never |
358 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
374 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
359 | two event changes per incident, support for C<fork ()> is very bad and it |
375 | two event changes per incident, support for C<fork ()> is very bad and it |
360 | drops fds silently in similarly hard-to-detect cases. |
376 | drops fds silently in similarly hard-to-detect cases. |
361 | |
377 | |
|
|
378 | This backend usually performs well under most conditions. |
|
|
379 | |
|
|
380 | While nominally embeddable in other event loops, this doesn't work |
|
|
381 | everywhere, so you might need to test for this. And since it is broken |
|
|
382 | almost everywhere, you should only use it when you have a lot of sockets |
|
|
383 | (for which it usually works), by embedding it into another event loop |
|
|
384 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for |
|
|
385 | sockets. |
|
|
386 | |
362 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
387 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
363 | |
388 | |
364 | This is not implemented yet (and might never be). |
389 | This is not implemented yet (and might never be, unless you send me an |
|
|
390 | implementation). According to reports, C</dev/poll> only supports sockets |
|
|
391 | and is not embeddable, which would limit the usefulness of this backend |
|
|
392 | immensely. |
365 | |
393 | |
366 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
394 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
367 | |
395 | |
368 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
396 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
369 | it's really slow, but it still scales very well (O(active_fds)). |
397 | it's really slow, but it still scales very well (O(active_fds)). |
370 | |
398 | |
371 | Please note that solaris event ports can deliver a lot of spurious |
399 | Please note that solaris event ports can deliver a lot of spurious |
372 | notifications, so you need to use non-blocking I/O or other means to avoid |
400 | notifications, so you need to use non-blocking I/O or other means to avoid |
373 | blocking when no data (or space) is available. |
401 | blocking when no data (or space) is available. |
374 | |
402 | |
|
|
403 | While this backend scales well, it requires one system call per active |
|
|
404 | file descriptor per loop iteration. For small and medium numbers of file |
|
|
405 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
|
|
406 | might perform better. |
|
|
407 | |
375 | =item C<EVBACKEND_ALL> |
408 | =item C<EVBACKEND_ALL> |
376 | |
409 | |
377 | Try all backends (even potentially broken ones that wouldn't be tried |
410 | Try all backends (even potentially broken ones that wouldn't be tried |
378 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
411 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
379 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
412 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
|
|
413 | |
|
|
414 | It is definitely not recommended to use this flag. |
380 | |
415 | |
381 | =back |
416 | =back |
382 | |
417 | |
383 | If one or more of these are ored into the flags value, then only these |
418 | If one or more of these are ored into the flags value, then only these |
384 | backends will be tried (in the reverse order as given here). If none are |
419 | backends will be tried (in the reverse order as given here). If none are |
… | |
… | |
516 | usually a better approach for this kind of thing. |
551 | usually a better approach for this kind of thing. |
517 | |
552 | |
518 | Here are the gory details of what C<ev_loop> does: |
553 | Here are the gory details of what C<ev_loop> does: |
519 | |
554 | |
520 | - Before the first iteration, call any pending watchers. |
555 | - Before the first iteration, call any pending watchers. |
521 | * If there are no active watchers (reference count is zero), return. |
556 | * If EVFLAG_FORKCHECK was used, check for a fork. |
522 | - Queue all prepare watchers and then call all outstanding watchers. |
557 | - If a fork was detected, queue and call all fork watchers. |
|
|
558 | - Queue and call all prepare watchers. |
523 | - If we have been forked, recreate the kernel state. |
559 | - If we have been forked, recreate the kernel state. |
524 | - Update the kernel state with all outstanding changes. |
560 | - Update the kernel state with all outstanding changes. |
525 | - Update the "event loop time". |
561 | - Update the "event loop time". |
526 | - Calculate for how long to block. |
562 | - Calculate for how long to sleep or block, if at all |
|
|
563 | (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
564 | any active watchers at all will result in not sleeping). |
|
|
565 | - Sleep if the I/O and timer collect interval say so. |
527 | - Block the process, waiting for any events. |
566 | - Block the process, waiting for any events. |
528 | - Queue all outstanding I/O (fd) events. |
567 | - Queue all outstanding I/O (fd) events. |
529 | - Update the "event loop time" and do time jump handling. |
568 | - Update the "event loop time" and do time jump handling. |
530 | - Queue all outstanding timers. |
569 | - Queue all outstanding timers. |
531 | - Queue all outstanding periodics. |
570 | - Queue all outstanding periodics. |
532 | - If no events are pending now, queue all idle watchers. |
571 | - If no events are pending now, queue all idle watchers. |
533 | - Queue all check watchers. |
572 | - Queue all check watchers. |
534 | - Call all queued watchers in reverse order (i.e. check watchers first). |
573 | - Call all queued watchers in reverse order (i.e. check watchers first). |
535 | Signals and child watchers are implemented as I/O watchers, and will |
574 | Signals and child watchers are implemented as I/O watchers, and will |
536 | be handled here by queueing them when their watcher gets executed. |
575 | be handled here by queueing them when their watcher gets executed. |
537 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
576 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
538 | were used, return, otherwise continue with step *. |
577 | were used, or there are no active watchers, return, otherwise |
|
|
578 | continue with step *. |
539 | |
579 | |
540 | Example: Queue some jobs and then loop until no events are outsanding |
580 | Example: Queue some jobs and then loop until no events are outstanding |
541 | anymore. |
581 | anymore. |
542 | |
582 | |
543 | ... queue jobs here, make sure they register event watchers as long |
583 | ... queue jobs here, make sure they register event watchers as long |
544 | ... as they still have work to do (even an idle watcher will do..) |
584 | ... as they still have work to do (even an idle watcher will do..) |
545 | ev_loop (my_loop, 0); |
585 | ev_loop (my_loop, 0); |
… | |
… | |
549 | |
589 | |
550 | Can be used to make a call to C<ev_loop> return early (but only after it |
590 | Can be used to make a call to C<ev_loop> return early (but only after it |
551 | has processed all outstanding events). The C<how> argument must be either |
591 | has processed all outstanding events). The C<how> argument must be either |
552 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
592 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
553 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
593 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
|
|
594 | |
|
|
595 | This "unloop state" will be cleared when entering C<ev_loop> again. |
554 | |
596 | |
555 | =item ev_ref (loop) |
597 | =item ev_ref (loop) |
556 | |
598 | |
557 | =item ev_unref (loop) |
599 | =item ev_unref (loop) |
558 | |
600 | |
… | |
… | |
948 | In general you can register as many read and/or write event watchers per |
990 | In general you can register as many read and/or write event watchers per |
949 | fd as you want (as long as you don't confuse yourself). Setting all file |
991 | fd as you want (as long as you don't confuse yourself). Setting all file |
950 | descriptors to non-blocking mode is also usually a good idea (but not |
992 | descriptors to non-blocking mode is also usually a good idea (but not |
951 | required if you know what you are doing). |
993 | required if you know what you are doing). |
952 | |
994 | |
953 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
954 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
955 | descriptors correctly if you register interest in two or more fds pointing |
|
|
956 | to the same underlying file/socket/etc. description (that is, they share |
|
|
957 | the same underlying "file open"). |
|
|
958 | |
|
|
959 | If you must do this, then force the use of a known-to-be-good backend |
995 | If you must do this, then force the use of a known-to-be-good backend |
960 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
996 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
961 | C<EVBACKEND_POLL>). |
997 | C<EVBACKEND_POLL>). |
962 | |
998 | |
963 | Another thing you have to watch out for is that it is quite easy to |
999 | Another thing you have to watch out for is that it is quite easy to |
… | |
… | |
997 | optimisations to libev. |
1033 | optimisations to libev. |
998 | |
1034 | |
999 | =head3 The special problem of dup'ed file descriptors |
1035 | =head3 The special problem of dup'ed file descriptors |
1000 | |
1036 | |
1001 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1037 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1002 | but only events for the underlying file descriptions. That menas when you |
1038 | but only events for the underlying file descriptions. That means when you |
1003 | have C<dup ()>'ed file descriptors and register events for them, only one |
1039 | have C<dup ()>'ed file descriptors or weirder constellations, and register |
1004 | file descriptor might actually receive events. |
1040 | events for them, only one file descriptor might actually receive events. |
1005 | |
1041 | |
1006 | There is no workaorund possible except not registering events |
1042 | There is no workaround possible except not registering events |
1007 | for potentially C<dup ()>'ed file descriptors or to resort to |
1043 | for potentially C<dup ()>'ed file descriptors, or to resort to |
1008 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1044 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1009 | |
1045 | |
1010 | =head3 The special problem of fork |
1046 | =head3 The special problem of fork |
1011 | |
1047 | |
1012 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
1048 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
… | |
… | |
1038 | =item int events [read-only] |
1074 | =item int events [read-only] |
1039 | |
1075 | |
1040 | The events being watched. |
1076 | The events being watched. |
1041 | |
1077 | |
1042 | =back |
1078 | =back |
|
|
1079 | |
|
|
1080 | =head3 Examples |
1043 | |
1081 | |
1044 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1082 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1045 | readable, but only once. Since it is likely line-buffered, you could |
1083 | readable, but only once. Since it is likely line-buffered, you could |
1046 | attempt to read a whole line in the callback. |
1084 | attempt to read a whole line in the callback. |
1047 | |
1085 | |
… | |
… | |
1145 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1183 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1146 | which is also when any modifications are taken into account. |
1184 | which is also when any modifications are taken into account. |
1147 | |
1185 | |
1148 | =back |
1186 | =back |
1149 | |
1187 | |
|
|
1188 | =head3 Examples |
|
|
1189 | |
1150 | Example: Create a timer that fires after 60 seconds. |
1190 | Example: Create a timer that fires after 60 seconds. |
1151 | |
1191 | |
1152 | static void |
1192 | static void |
1153 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1193 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1154 | { |
1194 | { |
… | |
… | |
1311 | When active, contains the absolute time that the watcher is supposed to |
1351 | When active, contains the absolute time that the watcher is supposed to |
1312 | trigger next. |
1352 | trigger next. |
1313 | |
1353 | |
1314 | =back |
1354 | =back |
1315 | |
1355 | |
|
|
1356 | =head3 Examples |
|
|
1357 | |
1316 | Example: Call a callback every hour, or, more precisely, whenever the |
1358 | Example: Call a callback every hour, or, more precisely, whenever the |
1317 | system clock is divisible by 3600. The callback invocation times have |
1359 | system clock is divisible by 3600. The callback invocation times have |
1318 | potentially a lot of jittering, but good long-term stability. |
1360 | potentially a lot of jittering, but good long-term stability. |
1319 | |
1361 | |
1320 | static void |
1362 | static void |
… | |
… | |
1411 | |
1453 | |
1412 | The process exit/trace status caused by C<rpid> (see your systems |
1454 | The process exit/trace status caused by C<rpid> (see your systems |
1413 | C<waitpid> and C<sys/wait.h> documentation for details). |
1455 | C<waitpid> and C<sys/wait.h> documentation for details). |
1414 | |
1456 | |
1415 | =back |
1457 | =back |
|
|
1458 | |
|
|
1459 | =head3 Examples |
1416 | |
1460 | |
1417 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1461 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1418 | |
1462 | |
1419 | static void |
1463 | static void |
1420 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1464 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
… | |
… | |
1461 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1505 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1462 | to fall back to regular polling again even with inotify, but changes are |
1506 | to fall back to regular polling again even with inotify, but changes are |
1463 | usually detected immediately, and if the file exists there will be no |
1507 | usually detected immediately, and if the file exists there will be no |
1464 | polling. |
1508 | polling. |
1465 | |
1509 | |
|
|
1510 | =head3 Inotify |
|
|
1511 | |
|
|
1512 | When C<inotify (7)> support has been compiled into libev (generally only |
|
|
1513 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1514 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1515 | when the first C<ev_stat> watcher is being started. |
|
|
1516 | |
|
|
1517 | Inotify presense does not change the semantics of C<ev_stat> watchers |
|
|
1518 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1519 | making regular C<stat> calls. Even in the presense of inotify support |
|
|
1520 | there are many cases where libev has to resort to regular C<stat> polling. |
|
|
1521 | |
|
|
1522 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1523 | implement this functionality, due to the requirement of having a file |
|
|
1524 | descriptor open on the object at all times). |
|
|
1525 | |
|
|
1526 | =head3 The special problem of stat time resolution |
|
|
1527 | |
|
|
1528 | The C<stat ()> syscall only supports full-second resolution portably, and |
|
|
1529 | even on systems where the resolution is higher, many filesystems still |
|
|
1530 | only support whole seconds. |
|
|
1531 | |
|
|
1532 | That means that, if the time is the only thing that changes, you might |
|
|
1533 | miss updates: on the first update, C<ev_stat> detects a change and calls |
|
|
1534 | your callback, which does something. When there is another update within |
|
|
1535 | the same second, C<ev_stat> will be unable to detect it. |
|
|
1536 | |
|
|
1537 | The solution to this is to delay acting on a change for a second (or till |
|
|
1538 | the next second boundary), using a roughly one-second delay C<ev_timer> |
|
|
1539 | (C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01> |
|
|
1540 | is added to work around small timing inconsistencies of some operating |
|
|
1541 | systems. |
|
|
1542 | |
1466 | =head3 Watcher-Specific Functions and Data Members |
1543 | =head3 Watcher-Specific Functions and Data Members |
1467 | |
1544 | |
1468 | =over 4 |
1545 | =over 4 |
1469 | |
1546 | |
1470 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1547 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
… | |
… | |
1507 | =item const char *path [read-only] |
1584 | =item const char *path [read-only] |
1508 | |
1585 | |
1509 | The filesystem path that is being watched. |
1586 | The filesystem path that is being watched. |
1510 | |
1587 | |
1511 | =back |
1588 | =back |
|
|
1589 | |
|
|
1590 | =head3 Examples |
1512 | |
1591 | |
1513 | Example: Watch C</etc/passwd> for attribute changes. |
1592 | Example: Watch C</etc/passwd> for attribute changes. |
1514 | |
1593 | |
1515 | static void |
1594 | static void |
1516 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1595 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
… | |
… | |
1529 | } |
1608 | } |
1530 | |
1609 | |
1531 | ... |
1610 | ... |
1532 | ev_stat passwd; |
1611 | ev_stat passwd; |
1533 | |
1612 | |
1534 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1613 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1535 | ev_stat_start (loop, &passwd); |
1614 | ev_stat_start (loop, &passwd); |
|
|
1615 | |
|
|
1616 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1617 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1618 | one might do the work both on C<ev_stat> callback invocation I<and> on |
|
|
1619 | C<ev_timer> callback invocation). |
|
|
1620 | |
|
|
1621 | static ev_stat passwd; |
|
|
1622 | static ev_timer timer; |
|
|
1623 | |
|
|
1624 | static void |
|
|
1625 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1626 | { |
|
|
1627 | ev_timer_stop (EV_A_ w); |
|
|
1628 | |
|
|
1629 | /* now it's one second after the most recent passwd change */ |
|
|
1630 | } |
|
|
1631 | |
|
|
1632 | static void |
|
|
1633 | stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1634 | { |
|
|
1635 | /* reset the one-second timer */ |
|
|
1636 | ev_timer_again (EV_A_ &timer); |
|
|
1637 | } |
|
|
1638 | |
|
|
1639 | ... |
|
|
1640 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
|
|
1641 | ev_stat_start (loop, &passwd); |
|
|
1642 | ev_timer_init (&timer, timer_cb, 0., 1.01); |
1536 | |
1643 | |
1537 | |
1644 | |
1538 | =head2 C<ev_idle> - when you've got nothing better to do... |
1645 | =head2 C<ev_idle> - when you've got nothing better to do... |
1539 | |
1646 | |
1540 | Idle watchers trigger events when no other events of the same or higher |
1647 | Idle watchers trigger events when no other events of the same or higher |
… | |
… | |
1565 | Initialises and configures the idle watcher - it has no parameters of any |
1672 | Initialises and configures the idle watcher - it has no parameters of any |
1566 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1673 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1567 | believe me. |
1674 | believe me. |
1568 | |
1675 | |
1569 | =back |
1676 | =back |
|
|
1677 | |
|
|
1678 | =head3 Examples |
1570 | |
1679 | |
1571 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1680 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1572 | callback, free it. Also, use no error checking, as usual. |
1681 | callback, free it. Also, use no error checking, as usual. |
1573 | |
1682 | |
1574 | static void |
1683 | static void |
… | |
… | |
1646 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1755 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1647 | macros, but using them is utterly, utterly and completely pointless. |
1756 | macros, but using them is utterly, utterly and completely pointless. |
1648 | |
1757 | |
1649 | =back |
1758 | =back |
1650 | |
1759 | |
|
|
1760 | =head3 Examples |
|
|
1761 | |
1651 | There are a number of principal ways to embed other event loops or modules |
1762 | There are a number of principal ways to embed other event loops or modules |
1652 | into libev. Here are some ideas on how to include libadns into libev |
1763 | into libev. Here are some ideas on how to include libadns into libev |
1653 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1764 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1654 | use for an actually working example. Another Perl module named C<EV::Glib> |
1765 | use for an actually working example. Another Perl module named C<EV::Glib> |
1655 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
1766 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
… | |
… | |
1823 | portable one. |
1934 | portable one. |
1824 | |
1935 | |
1825 | So when you want to use this feature you will always have to be prepared |
1936 | So when you want to use this feature you will always have to be prepared |
1826 | that you cannot get an embeddable loop. The recommended way to get around |
1937 | that you cannot get an embeddable loop. The recommended way to get around |
1827 | this is to have a separate variables for your embeddable loop, try to |
1938 | this is to have a separate variables for your embeddable loop, try to |
1828 | create it, and if that fails, use the normal loop for everything: |
1939 | create it, and if that fails, use the normal loop for everything. |
|
|
1940 | |
|
|
1941 | =head3 Watcher-Specific Functions and Data Members |
|
|
1942 | |
|
|
1943 | =over 4 |
|
|
1944 | |
|
|
1945 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1946 | |
|
|
1947 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1948 | |
|
|
1949 | Configures the watcher to embed the given loop, which must be |
|
|
1950 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1951 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1952 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1953 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1954 | |
|
|
1955 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1956 | |
|
|
1957 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1958 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1959 | apropriate way for embedded loops. |
|
|
1960 | |
|
|
1961 | =item struct ev_loop *other [read-only] |
|
|
1962 | |
|
|
1963 | The embedded event loop. |
|
|
1964 | |
|
|
1965 | =back |
|
|
1966 | |
|
|
1967 | =head3 Examples |
|
|
1968 | |
|
|
1969 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
1970 | event loop. If that is not possible, use the default loop. The default |
|
|
1971 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
|
|
1972 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
|
|
1973 | used). |
1829 | |
1974 | |
1830 | struct ev_loop *loop_hi = ev_default_init (0); |
1975 | struct ev_loop *loop_hi = ev_default_init (0); |
1831 | struct ev_loop *loop_lo = 0; |
1976 | struct ev_loop *loop_lo = 0; |
1832 | struct ev_embed embed; |
1977 | struct ev_embed embed; |
1833 | |
1978 | |
… | |
… | |
1844 | ev_embed_start (loop_hi, &embed); |
1989 | ev_embed_start (loop_hi, &embed); |
1845 | } |
1990 | } |
1846 | else |
1991 | else |
1847 | loop_lo = loop_hi; |
1992 | loop_lo = loop_hi; |
1848 | |
1993 | |
1849 | =head3 Watcher-Specific Functions and Data Members |
1994 | Example: Check if kqueue is available but not recommended and create |
|
|
1995 | a kqueue backend for use with sockets (which usually work with any |
|
|
1996 | kqueue implementation). Store the kqueue/socket-only event loop in |
|
|
1997 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
1850 | |
1998 | |
1851 | =over 4 |
1999 | struct ev_loop *loop = ev_default_init (0); |
|
|
2000 | struct ev_loop *loop_socket = 0; |
|
|
2001 | struct ev_embed embed; |
|
|
2002 | |
|
|
2003 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2004 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2005 | { |
|
|
2006 | ev_embed_init (&embed, 0, loop_socket); |
|
|
2007 | ev_embed_start (loop, &embed); |
|
|
2008 | } |
1852 | |
2009 | |
1853 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
2010 | if (!loop_socket) |
|
|
2011 | loop_socket = loop; |
1854 | |
2012 | |
1855 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
2013 | // now use loop_socket for all sockets, and loop for everything else |
1856 | |
|
|
1857 | Configures the watcher to embed the given loop, which must be |
|
|
1858 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1859 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1860 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1861 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1862 | |
|
|
1863 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1864 | |
|
|
1865 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1866 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1867 | apropriate way for embedded loops. |
|
|
1868 | |
|
|
1869 | =item struct ev_loop *other [read-only] |
|
|
1870 | |
|
|
1871 | The embedded event loop. |
|
|
1872 | |
|
|
1873 | =back |
|
|
1874 | |
2014 | |
1875 | |
2015 | |
1876 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2016 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
1877 | |
2017 | |
1878 | Fork watchers are called when a C<fork ()> was detected (usually because |
2018 | Fork watchers are called when a C<fork ()> was detected (usually because |
… | |
… | |
2357 | wants osf handles on win32 (this is the case when the select to |
2497 | wants osf handles on win32 (this is the case when the select to |
2358 | be used is the winsock select). This means that it will call |
2498 | be used is the winsock select). This means that it will call |
2359 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2499 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2360 | it is assumed that all these functions actually work on fds, even |
2500 | it is assumed that all these functions actually work on fds, even |
2361 | on win32. Should not be defined on non-win32 platforms. |
2501 | on win32. Should not be defined on non-win32 platforms. |
|
|
2502 | |
|
|
2503 | =item EV_FD_TO_WIN32_HANDLE |
|
|
2504 | |
|
|
2505 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
|
|
2506 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2507 | default), then libev will call C<_get_osfhandle>, which is usually |
|
|
2508 | correct. In some cases, programs use their own file descriptor management, |
|
|
2509 | in which case they can provide this function to map fds to socket handles. |
2362 | |
2510 | |
2363 | =item EV_USE_POLL |
2511 | =item EV_USE_POLL |
2364 | |
2512 | |
2365 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2513 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2366 | backend. Otherwise it will be enabled on non-win32 platforms. It |
2514 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
2403 | be detected at runtime. |
2551 | be detected at runtime. |
2404 | |
2552 | |
2405 | =item EV_H |
2553 | =item EV_H |
2406 | |
2554 | |
2407 | The name of the F<ev.h> header file used to include it. The default if |
2555 | The name of the F<ev.h> header file used to include it. The default if |
2408 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2556 | undefined is C<"ev.h"> in F<event.h> and F<ev.c>. This can be used to |
2409 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2557 | virtually rename the F<ev.h> header file in case of conflicts. |
2410 | |
2558 | |
2411 | =item EV_CONFIG_H |
2559 | =item EV_CONFIG_H |
2412 | |
2560 | |
2413 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2561 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2414 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2562 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2415 | C<EV_H>, above. |
2563 | C<EV_H>, above. |
2416 | |
2564 | |
2417 | =item EV_EVENT_H |
2565 | =item EV_EVENT_H |
2418 | |
2566 | |
2419 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2567 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2420 | of how the F<event.h> header can be found. |
2568 | of how the F<event.h> header can be found, the dfeault is C<"event.h">. |
2421 | |
2569 | |
2422 | =item EV_PROTOTYPES |
2570 | =item EV_PROTOTYPES |
2423 | |
2571 | |
2424 | If defined to be C<0>, then F<ev.h> will not define any function |
2572 | If defined to be C<0>, then F<ev.h> will not define any function |
2425 | prototypes, but still define all the structs and other symbols. This is |
2573 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2491 | than enough. If you need to manage thousands of children you might want to |
2639 | than enough. If you need to manage thousands of children you might want to |
2492 | increase this value (I<must> be a power of two). |
2640 | increase this value (I<must> be a power of two). |
2493 | |
2641 | |
2494 | =item EV_INOTIFY_HASHSIZE |
2642 | =item EV_INOTIFY_HASHSIZE |
2495 | |
2643 | |
2496 | C<ev_staz> watchers use a small hash table to distribute workload by |
2644 | C<ev_stat> watchers use a small hash table to distribute workload by |
2497 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2645 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2498 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2646 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2499 | watchers you might want to increase this value (I<must> be a power of |
2647 | watchers you might want to increase this value (I<must> be a power of |
2500 | two). |
2648 | two). |
2501 | |
2649 | |
… | |
… | |
2597 | |
2745 | |
2598 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2746 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2599 | |
2747 | |
2600 | This means that, when you have a watcher that triggers in one hour and |
2748 | This means that, when you have a watcher that triggers in one hour and |
2601 | there are 100 watchers that would trigger before that then inserting will |
2749 | there are 100 watchers that would trigger before that then inserting will |
2602 | have to skip those 100 watchers. |
2750 | have to skip roughly seven (C<ld 100>) of these watchers. |
2603 | |
2751 | |
2604 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2752 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
2605 | |
2753 | |
2606 | That means that for changing a timer costs less than removing/adding them |
2754 | That means that changing a timer costs less than removing/adding them |
2607 | as only the relative motion in the event queue has to be paid for. |
2755 | as only the relative motion in the event queue has to be paid for. |
2608 | |
2756 | |
2609 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2757 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2610 | |
2758 | |
2611 | These just add the watcher into an array or at the head of a list. |
2759 | These just add the watcher into an array or at the head of a list. |
|
|
2760 | |
2612 | =item Stopping check/prepare/idle watchers: O(1) |
2761 | =item Stopping check/prepare/idle watchers: O(1) |
2613 | |
2762 | |
2614 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2763 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2615 | |
2764 | |
2616 | These watchers are stored in lists then need to be walked to find the |
2765 | These watchers are stored in lists then need to be walked to find the |
2617 | correct watcher to remove. The lists are usually short (you don't usually |
2766 | correct watcher to remove. The lists are usually short (you don't usually |
2618 | have many watchers waiting for the same fd or signal). |
2767 | have many watchers waiting for the same fd or signal). |
2619 | |
2768 | |
2620 | =item Finding the next timer per loop iteration: O(1) |
2769 | =item Finding the next timer in each loop iteration: O(1) |
|
|
2770 | |
|
|
2771 | By virtue of using a binary heap, the next timer is always found at the |
|
|
2772 | beginning of the storage array. |
2621 | |
2773 | |
2622 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2774 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2623 | |
2775 | |
2624 | A change means an I/O watcher gets started or stopped, which requires |
2776 | A change means an I/O watcher gets started or stopped, which requires |
2625 | libev to recalculate its status (and possibly tell the kernel). |
2777 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
2778 | on backend and wether C<ev_io_set> was used). |
2626 | |
2779 | |
2627 | =item Activating one watcher: O(1) |
2780 | =item Activating one watcher (putting it into the pending state): O(1) |
2628 | |
2781 | |
2629 | =item Priority handling: O(number_of_priorities) |
2782 | =item Priority handling: O(number_of_priorities) |
2630 | |
2783 | |
2631 | Priorities are implemented by allocating some space for each |
2784 | Priorities are implemented by allocating some space for each |
2632 | priority. When doing priority-based operations, libev usually has to |
2785 | priority. When doing priority-based operations, libev usually has to |
2633 | linearly search all the priorities. |
2786 | linearly search all the priorities, but starting/stopping and activating |
|
|
2787 | watchers becomes O(1) w.r.t. prioritiy handling. |
2634 | |
2788 | |
2635 | =back |
2789 | =back |
2636 | |
2790 | |
2637 | |
2791 | |
|
|
2792 | =head1 Win32 platform limitations and workarounds |
|
|
2793 | |
|
|
2794 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
|
|
2795 | requires, and its I/O model is fundamentally incompatible with the POSIX |
|
|
2796 | model. Libev still offers limited functionality on this platform in |
|
|
2797 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
|
|
2798 | descriptors. This only applies when using Win32 natively, not when using |
|
|
2799 | e.g. cygwin. |
|
|
2800 | |
|
|
2801 | There is no supported compilation method available on windows except |
|
|
2802 | embedding it into other applications. |
|
|
2803 | |
|
|
2804 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
2805 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
2806 | recommended (and not reasonable). If your program needs to use more than |
|
|
2807 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
2808 | implementation for windows, as libev offers the POSIX model, which cannot |
|
|
2809 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
2810 | |
|
|
2811 | =over 4 |
|
|
2812 | |
|
|
2813 | =item The winsocket select function |
|
|
2814 | |
|
|
2815 | The winsocket C<select> function doesn't follow POSIX in that it requires |
|
|
2816 | socket I<handles> and not socket I<file descriptors>. This makes select |
|
|
2817 | very inefficient, and also requires a mapping from file descriptors |
|
|
2818 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
|
|
2819 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
|
|
2820 | symbols for more info. |
|
|
2821 | |
|
|
2822 | The configuration for a "naked" win32 using the microsoft runtime |
|
|
2823 | libraries and raw winsocket select is: |
|
|
2824 | |
|
|
2825 | #define EV_USE_SELECT 1 |
|
|
2826 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
2827 | |
|
|
2828 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
2829 | complexity in the O(n²) range when using win32. |
|
|
2830 | |
|
|
2831 | =item Limited number of file descriptors |
|
|
2832 | |
|
|
2833 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
2834 | of winsocket's select only supported waiting for a max. of C<64> handles |
|
|
2835 | (probably owning to the fact that all windows kernels can only wait for |
|
|
2836 | C<64> things at the same time internally; microsoft recommends spawning a |
|
|
2837 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
2838 | |
|
|
2839 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
|
|
2840 | to some high number (e.g. C<2048>) before compiling the winsocket select |
|
|
2841 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
2842 | select emulation on windows). |
|
|
2843 | |
|
|
2844 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
2845 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
|
|
2846 | or something like this inside microsoft). You can increase this by calling |
|
|
2847 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
|
|
2848 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
2849 | libraries. |
|
|
2850 | |
|
|
2851 | This might get you to about C<512> or C<2048> sockets (depending on |
|
|
2852 | windows version and/or the phase of the moon). To get more, you need to |
|
|
2853 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
2854 | calling select (O(n²)) will likely make this unworkable. |
|
|
2855 | |
|
|
2856 | =back |
|
|
2857 | |
|
|
2858 | |
2638 | =head1 AUTHOR |
2859 | =head1 AUTHOR |
2639 | |
2860 | |
2640 | Marc Lehmann <libev@schmorp.de>. |
2861 | Marc Lehmann <libev@schmorp.de>. |
2641 | |
2862 | |