… | |
… | |
299 | } |
299 | } |
300 | |
300 | |
301 | ... |
301 | ... |
302 | ev_set_syserr_cb (fatal_error); |
302 | ev_set_syserr_cb (fatal_error); |
303 | |
303 | |
|
|
304 | =item ev_feed_signal (int signum) |
|
|
305 | |
|
|
306 | This function can be used to "simulate" a signal receive. It is completely |
|
|
307 | safe to call this function at any time, from any context, including signal |
|
|
308 | handlers or random threads. |
|
|
309 | |
|
|
310 | Its main use is to customise signal handling in your process, especially |
|
|
311 | in the presence of threads. For example, you could block signals |
|
|
312 | by default in all threads (and specifying C<EVFLAG_NOSIGMASK> when |
|
|
313 | creating any loops), and in one thread, use C<sigwait> or any other |
|
|
314 | mechanism to wait for signals, then "deliver" them to libev by calling |
|
|
315 | C<ev_feed_signal>. |
|
|
316 | |
304 | =back |
317 | =back |
305 | |
318 | |
306 | =head1 FUNCTIONS CONTROLLING EVENT LOOPS |
319 | =head1 FUNCTIONS CONTROLLING EVENT LOOPS |
307 | |
320 | |
308 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
321 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
… | |
… | |
418 | threads that are not interested in handling them. |
431 | threads that are not interested in handling them. |
419 | |
432 | |
420 | Signalfd will not be used by default as this changes your signal mask, and |
433 | Signalfd will not be used by default as this changes your signal mask, and |
421 | there are a lot of shoddy libraries and programs (glib's threadpool for |
434 | there are a lot of shoddy libraries and programs (glib's threadpool for |
422 | example) that can't properly initialise their signal masks. |
435 | example) that can't properly initialise their signal masks. |
|
|
436 | |
|
|
437 | =item C<EVFLAG_NOSIGMASK> |
|
|
438 | |
|
|
439 | 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 |
|
|
441 | when you want to receive them. |
|
|
442 | |
|
|
443 | 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 |
|
|
445 | unblocking the signals. |
|
|
446 | |
|
|
447 | It's also required by POSIX in a threaded program, as libev calls |
|
|
448 | C<sigprocmask>, whose behaviour is officially unspecified. |
|
|
449 | |
|
|
450 | This flag's behaviour will become the default in future versions of libev. |
423 | |
451 | |
424 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
452 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
425 | |
453 | |
426 | This is your standard select(2) backend. Not I<completely> standard, as |
454 | This is your standard select(2) backend. Not I<completely> standard, as |
427 | libev tries to roll its own fd_set with no limits on the number of fds, |
455 | libev tries to roll its own fd_set with no limits on the number of fds, |
… | |
… | |
481 | employing an additional generation counter and comparing that against the |
509 | employing an additional generation counter and comparing that against the |
482 | events to filter out spurious ones, recreating the set when required. Last |
510 | events to filter out spurious ones, recreating the set when required. Last |
483 | not least, it also refuses to work with some file descriptors which work |
511 | not least, it also refuses to work with some file descriptors which work |
484 | perfectly fine with C<select> (files, many character devices...). |
512 | perfectly fine with C<select> (files, many character devices...). |
485 | |
513 | |
486 | Epoll is truly the train wreck analog among event poll mechanisms. |
514 | Epoll is truly the train wreck analog among event poll mechanisms, |
|
|
515 | a frankenpoll, cobbled together in a hurry, no thought to design or |
|
|
516 | interaction with others. |
487 | |
517 | |
488 | While stopping, setting and starting an I/O watcher in the same iteration |
518 | While stopping, setting and starting an I/O watcher in the same iteration |
489 | will result in some caching, there is still a system call per such |
519 | will result in some caching, there is still a system call per such |
490 | incident (because the same I<file descriptor> could point to a different |
520 | incident (because the same I<file descriptor> could point to a different |
491 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
521 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
… | |
… | |
557 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
587 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
558 | |
588 | |
559 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
589 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
560 | it's really slow, but it still scales very well (O(active_fds)). |
590 | it's really slow, but it still scales very well (O(active_fds)). |
561 | |
591 | |
562 | Please note that Solaris event ports can deliver a lot of spurious |
|
|
563 | notifications, so you need to use non-blocking I/O or other means to avoid |
|
|
564 | blocking when no data (or space) is available. |
|
|
565 | |
|
|
566 | While this backend scales well, it requires one system call per active |
592 | While this backend scales well, it requires one system call per active |
567 | file descriptor per loop iteration. For small and medium numbers of file |
593 | file descriptor per loop iteration. For small and medium numbers of file |
568 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
594 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
569 | might perform better. |
595 | might perform better. |
570 | |
596 | |
571 | On the positive side, with the exception of the spurious readiness |
597 | On the positive side, this backend actually performed fully to |
572 | notifications, this backend actually performed fully to specification |
|
|
573 | in all tests and is fully embeddable, which is a rare feat among the |
598 | specification in all tests and is fully embeddable, which is a rare feat |
574 | OS-specific backends (I vastly prefer correctness over speed hacks). |
599 | among the OS-specific backends (I vastly prefer correctness over speed |
|
|
600 | hacks). |
|
|
601 | |
|
|
602 | On the negative side, the interface is I<bizarre> - so bizarre that |
|
|
603 | even sun itself gets it wrong in their code examples: The event polling |
|
|
604 | function sometimes returning events to the caller even though an error |
|
|
605 | occurred, but with no indication whether it has done so or not (yes, it's |
|
|
606 | even documented that way) - deadly for edge-triggered interfaces where |
|
|
607 | you absolutely have to know whether an event occurred or not because you |
|
|
608 | have to re-arm the watcher. |
|
|
609 | |
|
|
610 | Fortunately libev seems to be able to work around these idiocies. |
575 | |
611 | |
576 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
612 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
577 | C<EVBACKEND_POLL>. |
613 | C<EVBACKEND_POLL>. |
578 | |
614 | |
579 | =item C<EVBACKEND_ALL> |
615 | =item C<EVBACKEND_ALL> |
580 | |
616 | |
581 | Try all backends (even potentially broken ones that wouldn't be tried |
617 | Try all backends (even potentially broken ones that wouldn't be tried |
582 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
618 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
583 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
619 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
584 | |
620 | |
585 | It is definitely not recommended to use this flag. |
621 | It is definitely not recommended to use this flag, use whatever |
|
|
622 | C<ev_recommended_backends ()> returns, or simply do not specify a backend |
|
|
623 | at all. |
|
|
624 | |
|
|
625 | =item C<EVBACKEND_MASK> |
|
|
626 | |
|
|
627 | Not a backend at all, but a mask to select all backend bits from a |
|
|
628 | C<flags> value, in case you want to mask out any backends from a flags |
|
|
629 | value (e.g. when modifying the C<LIBEV_FLAGS> environment variable). |
586 | |
630 | |
587 | =back |
631 | =back |
588 | |
632 | |
589 | If one or more of the backend flags are or'ed into the flags value, |
633 | If one or more of the backend flags are or'ed into the flags value, |
590 | then only these backends will be tried (in the reverse order as listed |
634 | then only these backends will be tried (in the reverse order as listed |
… | |
… | |
867 | running when nothing else is active. |
911 | running when nothing else is active. |
868 | |
912 | |
869 | ev_signal exitsig; |
913 | ev_signal exitsig; |
870 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
914 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
871 | ev_signal_start (loop, &exitsig); |
915 | ev_signal_start (loop, &exitsig); |
872 | evf_unref (loop); |
916 | ev_unref (loop); |
873 | |
917 | |
874 | Example: For some weird reason, unregister the above signal handler again. |
918 | Example: For some weird reason, unregister the above signal handler again. |
875 | |
919 | |
876 | ev_ref (loop); |
920 | ev_ref (loop); |
877 | ev_signal_stop (loop, &exitsig); |
921 | ev_signal_stop (loop, &exitsig); |
… | |
… | |
1316 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1360 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1317 | functions that do not need a watcher. |
1361 | functions that do not need a watcher. |
1318 | |
1362 | |
1319 | =back |
1363 | =back |
1320 | |
1364 | |
1321 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1365 | See also the L<ASSOCIATING CUSTOM DATA WITH A WATCHER> and L<BUILDING YOUR |
1322 | |
1366 | OWN COMPOSITE WATCHERS> idioms. |
1323 | Each watcher has, by default, a member C<void *data> that you can change |
|
|
1324 | and read at any time: libev will completely ignore it. This can be used |
|
|
1325 | to associate arbitrary data with your watcher. If you need more data and |
|
|
1326 | don't want to allocate memory and store a pointer to it in that data |
|
|
1327 | member, you can also "subclass" the watcher type and provide your own |
|
|
1328 | data: |
|
|
1329 | |
|
|
1330 | struct my_io |
|
|
1331 | { |
|
|
1332 | ev_io io; |
|
|
1333 | int otherfd; |
|
|
1334 | void *somedata; |
|
|
1335 | struct whatever *mostinteresting; |
|
|
1336 | }; |
|
|
1337 | |
|
|
1338 | ... |
|
|
1339 | struct my_io w; |
|
|
1340 | ev_io_init (&w.io, my_cb, fd, EV_READ); |
|
|
1341 | |
|
|
1342 | And since your callback will be called with a pointer to the watcher, you |
|
|
1343 | can cast it back to your own type: |
|
|
1344 | |
|
|
1345 | static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
|
|
1346 | { |
|
|
1347 | struct my_io *w = (struct my_io *)w_; |
|
|
1348 | ... |
|
|
1349 | } |
|
|
1350 | |
|
|
1351 | More interesting and less C-conformant ways of casting your callback type |
|
|
1352 | instead have been omitted. |
|
|
1353 | |
|
|
1354 | Another common scenario is to use some data structure with multiple |
|
|
1355 | embedded watchers: |
|
|
1356 | |
|
|
1357 | struct my_biggy |
|
|
1358 | { |
|
|
1359 | int some_data; |
|
|
1360 | ev_timer t1; |
|
|
1361 | ev_timer t2; |
|
|
1362 | } |
|
|
1363 | |
|
|
1364 | In this case getting the pointer to C<my_biggy> is a bit more |
|
|
1365 | complicated: Either you store the address of your C<my_biggy> struct |
|
|
1366 | in the C<data> member of the watcher (for woozies), or you need to use |
|
|
1367 | some pointer arithmetic using C<offsetof> inside your watchers (for real |
|
|
1368 | programmers): |
|
|
1369 | |
|
|
1370 | #include <stddef.h> |
|
|
1371 | |
|
|
1372 | static void |
|
|
1373 | t1_cb (EV_P_ ev_timer *w, int revents) |
|
|
1374 | { |
|
|
1375 | struct my_biggy big = (struct my_biggy *) |
|
|
1376 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
1377 | } |
|
|
1378 | |
|
|
1379 | static void |
|
|
1380 | t2_cb (EV_P_ ev_timer *w, int revents) |
|
|
1381 | { |
|
|
1382 | struct my_biggy big = (struct my_biggy *) |
|
|
1383 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
1384 | } |
|
|
1385 | |
1367 | |
1386 | =head2 WATCHER STATES |
1368 | =head2 WATCHER STATES |
1387 | |
1369 | |
1388 | There are various watcher states mentioned throughout this manual - |
1370 | There are various watcher states mentioned throughout this manual - |
1389 | active, pending and so on. In this section these states and the rules to |
1371 | active, pending and so on. In this section these states and the rules to |
… | |
… | |
1575 | In general you can register as many read and/or write event watchers per |
1557 | In general you can register as many read and/or write event watchers per |
1576 | fd as you want (as long as you don't confuse yourself). Setting all file |
1558 | fd as you want (as long as you don't confuse yourself). Setting all file |
1577 | descriptors to non-blocking mode is also usually a good idea (but not |
1559 | descriptors to non-blocking mode is also usually a good idea (but not |
1578 | required if you know what you are doing). |
1560 | required if you know what you are doing). |
1579 | |
1561 | |
1580 | If you cannot use non-blocking mode, then force the use of a |
|
|
1581 | known-to-be-good backend (at the time of this writing, this includes only |
|
|
1582 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
|
|
1583 | descriptors for which non-blocking operation makes no sense (such as |
|
|
1584 | files) - libev doesn't guarantee any specific behaviour in that case. |
|
|
1585 | |
|
|
1586 | Another thing you have to watch out for is that it is quite easy to |
1562 | Another thing you have to watch out for is that it is quite easy to |
1587 | receive "spurious" readiness notifications, that is your callback might |
1563 | receive "spurious" readiness notifications, that is, your callback might |
1588 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1564 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1589 | because there is no data. Not only are some backends known to create a |
1565 | because there is no data. It is very easy to get into this situation even |
1590 | lot of those (for example Solaris ports), it is very easy to get into |
1566 | with a relatively standard program structure. Thus it is best to always |
1591 | this situation even with a relatively standard program structure. Thus |
1567 | use non-blocking I/O: An extra C<read>(2) returning C<EAGAIN> is far |
1592 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
|
|
1593 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
1568 | preferable to a program hanging until some data arrives. |
1594 | |
1569 | |
1595 | If you cannot run the fd in non-blocking mode (for example you should |
1570 | If you cannot run the fd in non-blocking mode (for example you should |
1596 | not play around with an Xlib connection), then you have to separately |
1571 | not play around with an Xlib connection), then you have to separately |
1597 | re-test whether a file descriptor is really ready with a known-to-be good |
1572 | re-test whether a file descriptor is really ready with a known-to-be good |
1598 | interface such as poll (fortunately in our Xlib example, Xlib already |
1573 | interface such as poll (fortunately in the case of Xlib, it already does |
1599 | does this on its own, so its quite safe to use). Some people additionally |
1574 | this on its own, so its quite safe to use). Some people additionally |
1600 | use C<SIGALRM> and an interval timer, just to be sure you won't block |
1575 | use C<SIGALRM> and an interval timer, just to be sure you won't block |
1601 | indefinitely. |
1576 | indefinitely. |
1602 | |
1577 | |
1603 | But really, best use non-blocking mode. |
1578 | But really, best use non-blocking mode. |
1604 | |
1579 | |
… | |
… | |
1632 | |
1607 | |
1633 | There is no workaround possible except not registering events |
1608 | There is no workaround possible except not registering events |
1634 | for potentially C<dup ()>'ed file descriptors, or to resort to |
1609 | for potentially C<dup ()>'ed file descriptors, or to resort to |
1635 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1610 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1636 | |
1611 | |
|
|
1612 | =head3 The special problem of files |
|
|
1613 | |
|
|
1614 | Many people try to use C<select> (or libev) on file descriptors |
|
|
1615 | representing files, and expect it to become ready when their program |
|
|
1616 | doesn't block on disk accesses (which can take a long time on their own). |
|
|
1617 | |
|
|
1618 | However, this cannot ever work in the "expected" way - you get a readiness |
|
|
1619 | notification as soon as the kernel knows whether and how much data is |
|
|
1620 | there, and in the case of open files, that's always the case, so you |
|
|
1621 | always get a readiness notification instantly, and your read (or possibly |
|
|
1622 | write) will still block on the disk I/O. |
|
|
1623 | |
|
|
1624 | Another way to view it is that in the case of sockets, pipes, character |
|
|
1625 | devices and so on, there is another party (the sender) that delivers data |
|
|
1626 | on its own, but in the case of files, there is no such thing: the disk |
|
|
1627 | will not send data on its own, simply because it doesn't know what you |
|
|
1628 | wish to read - you would first have to request some data. |
|
|
1629 | |
|
|
1630 | Since files are typically not-so-well supported by advanced notification |
|
|
1631 | mechanism, libev tries hard to emulate POSIX behaviour with respect |
|
|
1632 | to files, even though you should not use it. The reason for this is |
|
|
1633 | convenience: sometimes you want to watch STDIN or STDOUT, which is |
|
|
1634 | usually a tty, often a pipe, but also sometimes files or special devices |
|
|
1635 | (for example, C<epoll> on Linux works with F</dev/random> but not with |
|
|
1636 | F</dev/urandom>), and even though the file might better be served with |
|
|
1637 | asynchronous I/O instead of with non-blocking I/O, it is still useful when |
|
|
1638 | it "just works" instead of freezing. |
|
|
1639 | |
|
|
1640 | So avoid file descriptors pointing to files when you know it (e.g. use |
|
|
1641 | libeio), but use them when it is convenient, e.g. for STDIN/STDOUT, or |
|
|
1642 | when you rarely read from a file instead of from a socket, and want to |
|
|
1643 | reuse the same code path. |
|
|
1644 | |
1637 | =head3 The special problem of fork |
1645 | =head3 The special problem of fork |
1638 | |
1646 | |
1639 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
1647 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
1640 | useless behaviour. Libev fully supports fork, but needs to be told about |
1648 | useless behaviour. Libev fully supports fork, but needs to be told about |
1641 | it in the child. |
1649 | it in the child if you want to continue to use it in the child. |
1642 | |
1650 | |
1643 | To support fork in your programs, you either have to call |
1651 | To support fork in your child processes, you have to call C<ev_loop_fork |
1644 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
1652 | ()> after a fork in the child, enable C<EVFLAG_FORKCHECK>, or resort to |
1645 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
1653 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1646 | C<EVBACKEND_POLL>. |
|
|
1647 | |
1654 | |
1648 | =head3 The special problem of SIGPIPE |
1655 | =head3 The special problem of SIGPIPE |
1649 | |
1656 | |
1650 | While not really specific to libev, it is easy to forget about C<SIGPIPE>: |
1657 | While not really specific to libev, it is easy to forget about C<SIGPIPE>: |
1651 | when writing to a pipe whose other end has been closed, your program gets |
1658 | when writing to a pipe whose other end has been closed, your program gets |
… | |
… | |
2296 | =head3 The special problem of inheritance over fork/execve/pthread_create |
2303 | =head3 The special problem of inheritance over fork/execve/pthread_create |
2297 | |
2304 | |
2298 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2305 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2299 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2306 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2300 | stopping it again), that is, libev might or might not block the signal, |
2307 | stopping it again), that is, libev might or might not block the signal, |
2301 | and might or might not set or restore the installed signal handler. |
2308 | and might or might not set or restore the installed signal handler (but |
|
|
2309 | see C<EVFLAG_NOSIGMASK>). |
2302 | |
2310 | |
2303 | While this does not matter for the signal disposition (libev never |
2311 | While this does not matter for the signal disposition (libev never |
2304 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
2312 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
2305 | C<execve>), this matters for the signal mask: many programs do not expect |
2313 | C<execve>), this matters for the signal mask: many programs do not expect |
2306 | certain signals to be blocked. |
2314 | certain signals to be blocked. |
… | |
… | |
2319 | I<has> to modify the signal mask, at least temporarily. |
2327 | I<has> to modify the signal mask, at least temporarily. |
2320 | |
2328 | |
2321 | So I can't stress this enough: I<If you do not reset your signal mask when |
2329 | So I can't stress this enough: I<If you do not reset your signal mask when |
2322 | you expect it to be empty, you have a race condition in your code>. This |
2330 | you expect it to be empty, you have a race condition in your code>. This |
2323 | is not a libev-specific thing, this is true for most event libraries. |
2331 | is not a libev-specific thing, this is true for most event libraries. |
|
|
2332 | |
|
|
2333 | =head3 The special problem of threads signal handling |
|
|
2334 | |
|
|
2335 | POSIX threads has problematic signal handling semantics, specifically, |
|
|
2336 | a lot of functionality (sigfd, sigwait etc.) only really works if all |
|
|
2337 | threads in a process block signals, which is hard to achieve. |
|
|
2338 | |
|
|
2339 | When you want to use sigwait (or mix libev signal handling with your own |
|
|
2340 | for the same signals), you can tackle this problem by globally blocking |
|
|
2341 | all signals before creating any threads (or creating them with a fully set |
|
|
2342 | sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating |
|
|
2343 | loops. Then designate one thread as "signal receiver thread" which handles |
|
|
2344 | these signals. You can pass on any signals that libev might be interested |
|
|
2345 | in by calling C<ev_feed_signal>. |
2324 | |
2346 | |
2325 | =head3 Watcher-Specific Functions and Data Members |
2347 | =head3 Watcher-Specific Functions and Data Members |
2326 | |
2348 | |
2327 | =over 4 |
2349 | =over 4 |
2328 | |
2350 | |
… | |
… | |
3175 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3197 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3176 | |
3198 | |
3177 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3199 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3178 | too, are asynchronous in nature, and signals, too, will be compressed |
3200 | too, are asynchronous in nature, and signals, too, will be compressed |
3179 | (i.e. the number of callback invocations may be less than the number of |
3201 | (i.e. the number of callback invocations may be less than the number of |
3180 | C<ev_async_sent> calls). |
3202 | C<ev_async_sent> calls). In fact, you could use signal watchers as a kind |
|
|
3203 | of "global async watchers" by using a watcher on an otherwise unused |
|
|
3204 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
|
|
3205 | even without knowing which loop owns the signal. |
3181 | |
3206 | |
3182 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
3207 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
3183 | just the default loop. |
3208 | just the default loop. |
3184 | |
3209 | |
3185 | =head3 Queueing |
3210 | =head3 Queueing |
… | |
… | |
3361 | Feed an event on the given fd, as if a file descriptor backend detected |
3386 | Feed an event on the given fd, as if a file descriptor backend detected |
3362 | the given events it. |
3387 | the given events it. |
3363 | |
3388 | |
3364 | =item ev_feed_signal_event (loop, int signum) |
3389 | =item ev_feed_signal_event (loop, int signum) |
3365 | |
3390 | |
3366 | Feed an event as if the given signal occurred (C<loop> must be the default |
3391 | Feed an event as if the given signal occurred. See also C<ev_feed_signal>, |
3367 | loop!). |
3392 | which is async-safe. |
3368 | |
3393 | |
3369 | =back |
3394 | =back |
3370 | |
3395 | |
3371 | |
3396 | |
3372 | =head1 COMMON OR USEFUL IDIOMS (OR BOTH) |
3397 | =head1 COMMON OR USEFUL IDIOMS (OR BOTH) |
3373 | |
3398 | |
3374 | This section explains some common idioms that are not immediately |
3399 | This section explains some common idioms that are not immediately |
3375 | obvious. Note that examples are sprinkled over the whole manual, and this |
3400 | obvious. Note that examples are sprinkled over the whole manual, and this |
3376 | section only contains stuff that wouldn't fit anywhere else. |
3401 | section only contains stuff that wouldn't fit anywhere else. |
3377 | |
3402 | |
3378 | =over 4 |
3403 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
3379 | |
3404 | |
3380 | =item Model/nested event loop invocations and exit conditions. |
3405 | Each watcher has, by default, a C<void *data> member that you can read |
|
|
3406 | or modify at any time: libev will completely ignore it. This can be used |
|
|
3407 | to associate arbitrary data with your watcher. If you need more data and |
|
|
3408 | don't want to allocate memory separately and store a pointer to it in that |
|
|
3409 | data member, you can also "subclass" the watcher type and provide your own |
|
|
3410 | data: |
|
|
3411 | |
|
|
3412 | struct my_io |
|
|
3413 | { |
|
|
3414 | ev_io io; |
|
|
3415 | int otherfd; |
|
|
3416 | void *somedata; |
|
|
3417 | struct whatever *mostinteresting; |
|
|
3418 | }; |
|
|
3419 | |
|
|
3420 | ... |
|
|
3421 | struct my_io w; |
|
|
3422 | ev_io_init (&w.io, my_cb, fd, EV_READ); |
|
|
3423 | |
|
|
3424 | And since your callback will be called with a pointer to the watcher, you |
|
|
3425 | can cast it back to your own type: |
|
|
3426 | |
|
|
3427 | static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
|
|
3428 | { |
|
|
3429 | struct my_io *w = (struct my_io *)w_; |
|
|
3430 | ... |
|
|
3431 | } |
|
|
3432 | |
|
|
3433 | More interesting and less C-conformant ways of casting your callback |
|
|
3434 | function type instead have been omitted. |
|
|
3435 | |
|
|
3436 | =head2 BUILDING YOUR OWN COMPOSITE WATCHERS |
|
|
3437 | |
|
|
3438 | Another common scenario is to use some data structure with multiple |
|
|
3439 | embedded watchers, in effect creating your own watcher that combines |
|
|
3440 | multiple libev event sources into one "super-watcher": |
|
|
3441 | |
|
|
3442 | struct my_biggy |
|
|
3443 | { |
|
|
3444 | int some_data; |
|
|
3445 | ev_timer t1; |
|
|
3446 | ev_timer t2; |
|
|
3447 | } |
|
|
3448 | |
|
|
3449 | In this case getting the pointer to C<my_biggy> is a bit more |
|
|
3450 | complicated: Either you store the address of your C<my_biggy> struct in |
|
|
3451 | the C<data> member of the watcher (for woozies or C++ coders), or you need |
|
|
3452 | to use some pointer arithmetic using C<offsetof> inside your watchers (for |
|
|
3453 | real programmers): |
|
|
3454 | |
|
|
3455 | #include <stddef.h> |
|
|
3456 | |
|
|
3457 | static void |
|
|
3458 | t1_cb (EV_P_ ev_timer *w, int revents) |
|
|
3459 | { |
|
|
3460 | struct my_biggy big = (struct my_biggy *) |
|
|
3461 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
3462 | } |
|
|
3463 | |
|
|
3464 | static void |
|
|
3465 | t2_cb (EV_P_ ev_timer *w, int revents) |
|
|
3466 | { |
|
|
3467 | struct my_biggy big = (struct my_biggy *) |
|
|
3468 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
3469 | } |
|
|
3470 | |
|
|
3471 | =head2 MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS |
3381 | |
3472 | |
3382 | Often (especially in GUI toolkits) there are places where you have |
3473 | Often (especially in GUI toolkits) there are places where you have |
3383 | I<modal> interaction, which is most easily implemented by recursively |
3474 | I<modal> interaction, which is most easily implemented by recursively |
3384 | invoking C<ev_run>. |
3475 | invoking C<ev_run>. |
3385 | |
3476 | |
… | |
… | |
3414 | exit_main_loop = 1; |
3505 | exit_main_loop = 1; |
3415 | |
3506 | |
3416 | // exit both |
3507 | // exit both |
3417 | exit_main_loop = exit_nested_loop = 1; |
3508 | exit_main_loop = exit_nested_loop = 1; |
3418 | |
3509 | |
3419 | =back |
3510 | =head2 THREAD LOCKING EXAMPLE |
|
|
3511 | |
|
|
3512 | Here is a fictitious example of how to run an event loop in a different |
|
|
3513 | thread from where callbacks are being invoked and watchers are |
|
|
3514 | created/added/removed. |
|
|
3515 | |
|
|
3516 | For a real-world example, see the C<EV::Loop::Async> perl module, |
|
|
3517 | which uses exactly this technique (which is suited for many high-level |
|
|
3518 | languages). |
|
|
3519 | |
|
|
3520 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
3521 | variable to wait for callback invocations, an async watcher to notify the |
|
|
3522 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
3523 | |
|
|
3524 | First, you need to associate some data with the event loop: |
|
|
3525 | |
|
|
3526 | typedef struct { |
|
|
3527 | mutex_t lock; /* global loop lock */ |
|
|
3528 | ev_async async_w; |
|
|
3529 | thread_t tid; |
|
|
3530 | cond_t invoke_cv; |
|
|
3531 | } userdata; |
|
|
3532 | |
|
|
3533 | void prepare_loop (EV_P) |
|
|
3534 | { |
|
|
3535 | // for simplicity, we use a static userdata struct. |
|
|
3536 | static userdata u; |
|
|
3537 | |
|
|
3538 | ev_async_init (&u->async_w, async_cb); |
|
|
3539 | ev_async_start (EV_A_ &u->async_w); |
|
|
3540 | |
|
|
3541 | pthread_mutex_init (&u->lock, 0); |
|
|
3542 | pthread_cond_init (&u->invoke_cv, 0); |
|
|
3543 | |
|
|
3544 | // now associate this with the loop |
|
|
3545 | ev_set_userdata (EV_A_ u); |
|
|
3546 | ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
3547 | ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
3548 | |
|
|
3549 | // then create the thread running ev_loop |
|
|
3550 | pthread_create (&u->tid, 0, l_run, EV_A); |
|
|
3551 | } |
|
|
3552 | |
|
|
3553 | The callback for the C<ev_async> watcher does nothing: the watcher is used |
|
|
3554 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
3555 | that might have been added: |
|
|
3556 | |
|
|
3557 | static void |
|
|
3558 | async_cb (EV_P_ ev_async *w, int revents) |
|
|
3559 | { |
|
|
3560 | // just used for the side effects |
|
|
3561 | } |
|
|
3562 | |
|
|
3563 | The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex |
|
|
3564 | protecting the loop data, respectively. |
|
|
3565 | |
|
|
3566 | static void |
|
|
3567 | l_release (EV_P) |
|
|
3568 | { |
|
|
3569 | userdata *u = ev_userdata (EV_A); |
|
|
3570 | pthread_mutex_unlock (&u->lock); |
|
|
3571 | } |
|
|
3572 | |
|
|
3573 | static void |
|
|
3574 | l_acquire (EV_P) |
|
|
3575 | { |
|
|
3576 | userdata *u = ev_userdata (EV_A); |
|
|
3577 | pthread_mutex_lock (&u->lock); |
|
|
3578 | } |
|
|
3579 | |
|
|
3580 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
3581 | into C<ev_run>: |
|
|
3582 | |
|
|
3583 | void * |
|
|
3584 | l_run (void *thr_arg) |
|
|
3585 | { |
|
|
3586 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
3587 | |
|
|
3588 | l_acquire (EV_A); |
|
|
3589 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
3590 | ev_run (EV_A_ 0); |
|
|
3591 | l_release (EV_A); |
|
|
3592 | |
|
|
3593 | return 0; |
|
|
3594 | } |
|
|
3595 | |
|
|
3596 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
|
|
3597 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
3598 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
|
|
3599 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
3600 | and b) skipping inter-thread-communication when there are no pending |
|
|
3601 | watchers is very beneficial): |
|
|
3602 | |
|
|
3603 | static void |
|
|
3604 | l_invoke (EV_P) |
|
|
3605 | { |
|
|
3606 | userdata *u = ev_userdata (EV_A); |
|
|
3607 | |
|
|
3608 | while (ev_pending_count (EV_A)) |
|
|
3609 | { |
|
|
3610 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
3611 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
|
|
3612 | } |
|
|
3613 | } |
|
|
3614 | |
|
|
3615 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
3616 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
|
|
3617 | thread to continue: |
|
|
3618 | |
|
|
3619 | static void |
|
|
3620 | real_invoke_pending (EV_P) |
|
|
3621 | { |
|
|
3622 | userdata *u = ev_userdata (EV_A); |
|
|
3623 | |
|
|
3624 | pthread_mutex_lock (&u->lock); |
|
|
3625 | ev_invoke_pending (EV_A); |
|
|
3626 | pthread_cond_signal (&u->invoke_cv); |
|
|
3627 | pthread_mutex_unlock (&u->lock); |
|
|
3628 | } |
|
|
3629 | |
|
|
3630 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
3631 | event loop, you will now have to lock: |
|
|
3632 | |
|
|
3633 | ev_timer timeout_watcher; |
|
|
3634 | userdata *u = ev_userdata (EV_A); |
|
|
3635 | |
|
|
3636 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
3637 | |
|
|
3638 | pthread_mutex_lock (&u->lock); |
|
|
3639 | ev_timer_start (EV_A_ &timeout_watcher); |
|
|
3640 | ev_async_send (EV_A_ &u->async_w); |
|
|
3641 | pthread_mutex_unlock (&u->lock); |
|
|
3642 | |
|
|
3643 | Note that sending the C<ev_async> watcher is required because otherwise |
|
|
3644 | an event loop currently blocking in the kernel will have no knowledge |
|
|
3645 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
3646 | watchers in the next event loop iteration. |
|
|
3647 | |
|
|
3648 | =head2 THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS |
|
|
3649 | |
|
|
3650 | While the overhead of a callback that e.g. schedules a thread is small, it |
|
|
3651 | is still an overhead. If you embed libev, and your main usage is with some |
|
|
3652 | kind of threads or coroutines, you might want to customise libev so that |
|
|
3653 | doesn't need callbacks anymore. |
|
|
3654 | |
|
|
3655 | Imagine you have coroutines that you can switch to using a function |
|
|
3656 | C<switch_to (coro)>, that libev runs in a coroutine called C<libev_coro> |
|
|
3657 | and that due to some magic, the currently active coroutine is stored in a |
|
|
3658 | global called C<current_coro>. Then you can build your own "wait for libev |
|
|
3659 | event" primitive by changing C<EV_CB_DECLARE> and C<EV_CB_INVOKE> (note |
|
|
3660 | the differing C<;> conventions): |
|
|
3661 | |
|
|
3662 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
|
|
3663 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb) |
|
|
3664 | |
|
|
3665 | That means instead of having a C callback function, you store the |
|
|
3666 | coroutine to switch to in each watcher, and instead of having libev call |
|
|
3667 | your callback, you instead have it switch to that coroutine. |
|
|
3668 | |
|
|
3669 | A coroutine might now wait for an event with a function called |
|
|
3670 | C<wait_for_event>. (the watcher needs to be started, as always, but it doesn't |
|
|
3671 | matter when, or whether the watcher is active or not when this function is |
|
|
3672 | called): |
|
|
3673 | |
|
|
3674 | void |
|
|
3675 | wait_for_event (ev_watcher *w) |
|
|
3676 | { |
|
|
3677 | ev_cb_set (w) = current_coro; |
|
|
3678 | switch_to (libev_coro); |
|
|
3679 | } |
|
|
3680 | |
|
|
3681 | That basically suspends the coroutine inside C<wait_for_event> and |
|
|
3682 | continues the libev coroutine, which, when appropriate, switches back to |
|
|
3683 | this or any other coroutine. I am sure if you sue this your own :) |
|
|
3684 | |
|
|
3685 | You can do similar tricks if you have, say, threads with an event queue - |
|
|
3686 | instead of storing a coroutine, you store the queue object and instead of |
|
|
3687 | switching to a coroutine, you push the watcher onto the queue and notify |
|
|
3688 | any waiters. |
|
|
3689 | |
|
|
3690 | To embed libev, see L<EMBEDDING>, but in short, it's easiest to create two |
|
|
3691 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
|
|
3692 | |
|
|
3693 | // my_ev.h |
|
|
3694 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
|
|
3695 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
|
|
3696 | #include "../libev/ev.h" |
|
|
3697 | |
|
|
3698 | // my_ev.c |
|
|
3699 | #define EV_H "my_ev.h" |
|
|
3700 | #include "../libev/ev.c" |
|
|
3701 | |
|
|
3702 | And then use F<my_ev.h> when you would normally use F<ev.h>, and compile |
|
|
3703 | F<my_ev.c> into your project. When properly specifying include paths, you |
|
|
3704 | can even use F<ev.h> as header file name directly. |
3420 | |
3705 | |
3421 | |
3706 | |
3422 | =head1 LIBEVENT EMULATION |
3707 | =head1 LIBEVENT EMULATION |
3423 | |
3708 | |
3424 | Libev offers a compatibility emulation layer for libevent. It cannot |
3709 | Libev offers a compatibility emulation layer for libevent. It cannot |
… | |
… | |
3427 | =over 4 |
3712 | =over 4 |
3428 | |
3713 | |
3429 | =item * Only the libevent-1.4.1-beta API is being emulated. |
3714 | =item * Only the libevent-1.4.1-beta API is being emulated. |
3430 | |
3715 | |
3431 | This was the newest libevent version available when libev was implemented, |
3716 | This was the newest libevent version available when libev was implemented, |
3432 | and is still mostly uncanged in 2010. |
3717 | and is still mostly unchanged in 2010. |
3433 | |
3718 | |
3434 | =item * Use it by including <event.h>, as usual. |
3719 | =item * Use it by including <event.h>, as usual. |
3435 | |
3720 | |
3436 | =item * The following members are fully supported: ev_base, ev_callback, |
3721 | =item * The following members are fully supported: ev_base, ev_callback, |
3437 | ev_arg, ev_fd, ev_res, ev_events. |
3722 | ev_arg, ev_fd, ev_res, ev_events. |
… | |
… | |
4354 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4639 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4355 | |
4640 | |
4356 | #include "ev_cpp.h" |
4641 | #include "ev_cpp.h" |
4357 | #include "ev.c" |
4642 | #include "ev.c" |
4358 | |
4643 | |
4359 | =head1 INTERACTION WITH OTHER PROGRAMS OR LIBRARIES |
4644 | =head1 INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT |
4360 | |
4645 | |
4361 | =head2 THREADS AND COROUTINES |
4646 | =head2 THREADS AND COROUTINES |
4362 | |
4647 | |
4363 | =head3 THREADS |
4648 | =head3 THREADS |
4364 | |
4649 | |
… | |
… | |
4415 | default loop and triggering an C<ev_async> watcher from the default loop |
4700 | default loop and triggering an C<ev_async> watcher from the default loop |
4416 | watcher callback into the event loop interested in the signal. |
4701 | watcher callback into the event loop interested in the signal. |
4417 | |
4702 | |
4418 | =back |
4703 | =back |
4419 | |
4704 | |
4420 | =head4 THREAD LOCKING EXAMPLE |
4705 | See also L<THREAD LOCKING EXAMPLE>. |
4421 | |
|
|
4422 | Here is a fictitious example of how to run an event loop in a different |
|
|
4423 | thread than where callbacks are being invoked and watchers are |
|
|
4424 | created/added/removed. |
|
|
4425 | |
|
|
4426 | For a real-world example, see the C<EV::Loop::Async> perl module, |
|
|
4427 | which uses exactly this technique (which is suited for many high-level |
|
|
4428 | languages). |
|
|
4429 | |
|
|
4430 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
4431 | variable to wait for callback invocations, an async watcher to notify the |
|
|
4432 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
4433 | |
|
|
4434 | First, you need to associate some data with the event loop: |
|
|
4435 | |
|
|
4436 | typedef struct { |
|
|
4437 | mutex_t lock; /* global loop lock */ |
|
|
4438 | ev_async async_w; |
|
|
4439 | thread_t tid; |
|
|
4440 | cond_t invoke_cv; |
|
|
4441 | } userdata; |
|
|
4442 | |
|
|
4443 | void prepare_loop (EV_P) |
|
|
4444 | { |
|
|
4445 | // for simplicity, we use a static userdata struct. |
|
|
4446 | static userdata u; |
|
|
4447 | |
|
|
4448 | ev_async_init (&u->async_w, async_cb); |
|
|
4449 | ev_async_start (EV_A_ &u->async_w); |
|
|
4450 | |
|
|
4451 | pthread_mutex_init (&u->lock, 0); |
|
|
4452 | pthread_cond_init (&u->invoke_cv, 0); |
|
|
4453 | |
|
|
4454 | // now associate this with the loop |
|
|
4455 | ev_set_userdata (EV_A_ u); |
|
|
4456 | ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
4457 | ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
4458 | |
|
|
4459 | // then create the thread running ev_loop |
|
|
4460 | pthread_create (&u->tid, 0, l_run, EV_A); |
|
|
4461 | } |
|
|
4462 | |
|
|
4463 | The callback for the C<ev_async> watcher does nothing: the watcher is used |
|
|
4464 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
4465 | that might have been added: |
|
|
4466 | |
|
|
4467 | static void |
|
|
4468 | async_cb (EV_P_ ev_async *w, int revents) |
|
|
4469 | { |
|
|
4470 | // just used for the side effects |
|
|
4471 | } |
|
|
4472 | |
|
|
4473 | The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex |
|
|
4474 | protecting the loop data, respectively. |
|
|
4475 | |
|
|
4476 | static void |
|
|
4477 | l_release (EV_P) |
|
|
4478 | { |
|
|
4479 | userdata *u = ev_userdata (EV_A); |
|
|
4480 | pthread_mutex_unlock (&u->lock); |
|
|
4481 | } |
|
|
4482 | |
|
|
4483 | static void |
|
|
4484 | l_acquire (EV_P) |
|
|
4485 | { |
|
|
4486 | userdata *u = ev_userdata (EV_A); |
|
|
4487 | pthread_mutex_lock (&u->lock); |
|
|
4488 | } |
|
|
4489 | |
|
|
4490 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4491 | into C<ev_run>: |
|
|
4492 | |
|
|
4493 | void * |
|
|
4494 | l_run (void *thr_arg) |
|
|
4495 | { |
|
|
4496 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4497 | |
|
|
4498 | l_acquire (EV_A); |
|
|
4499 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4500 | ev_run (EV_A_ 0); |
|
|
4501 | l_release (EV_A); |
|
|
4502 | |
|
|
4503 | return 0; |
|
|
4504 | } |
|
|
4505 | |
|
|
4506 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
|
|
4507 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4508 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
|
|
4509 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4510 | and b) skipping inter-thread-communication when there are no pending |
|
|
4511 | watchers is very beneficial): |
|
|
4512 | |
|
|
4513 | static void |
|
|
4514 | l_invoke (EV_P) |
|
|
4515 | { |
|
|
4516 | userdata *u = ev_userdata (EV_A); |
|
|
4517 | |
|
|
4518 | while (ev_pending_count (EV_A)) |
|
|
4519 | { |
|
|
4520 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4521 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
|
|
4522 | } |
|
|
4523 | } |
|
|
4524 | |
|
|
4525 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4526 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
|
|
4527 | thread to continue: |
|
|
4528 | |
|
|
4529 | static void |
|
|
4530 | real_invoke_pending (EV_P) |
|
|
4531 | { |
|
|
4532 | userdata *u = ev_userdata (EV_A); |
|
|
4533 | |
|
|
4534 | pthread_mutex_lock (&u->lock); |
|
|
4535 | ev_invoke_pending (EV_A); |
|
|
4536 | pthread_cond_signal (&u->invoke_cv); |
|
|
4537 | pthread_mutex_unlock (&u->lock); |
|
|
4538 | } |
|
|
4539 | |
|
|
4540 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4541 | event loop, you will now have to lock: |
|
|
4542 | |
|
|
4543 | ev_timer timeout_watcher; |
|
|
4544 | userdata *u = ev_userdata (EV_A); |
|
|
4545 | |
|
|
4546 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4547 | |
|
|
4548 | pthread_mutex_lock (&u->lock); |
|
|
4549 | ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4550 | ev_async_send (EV_A_ &u->async_w); |
|
|
4551 | pthread_mutex_unlock (&u->lock); |
|
|
4552 | |
|
|
4553 | Note that sending the C<ev_async> watcher is required because otherwise |
|
|
4554 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4555 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4556 | watchers in the next event loop iteration. |
|
|
4557 | |
4706 | |
4558 | =head3 COROUTINES |
4707 | =head3 COROUTINES |
4559 | |
4708 | |
4560 | Libev is very accommodating to coroutines ("cooperative threads"): |
4709 | Libev is very accommodating to coroutines ("cooperative threads"): |
4561 | libev fully supports nesting calls to its functions from different |
4710 | libev fully supports nesting calls to its functions from different |