… | |
… | |
403 | While this backend scales well, it requires one system call per active |
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 |
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 |
405 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
406 | might perform better. |
406 | might perform better. |
407 | |
407 | |
|
|
408 | On the positive side, ignoring the spurious readyness notifications, this |
|
|
409 | backend actually performed to specification in all tests and is fully |
|
|
410 | embeddable, which is a rare feat among the OS-specific backends. |
|
|
411 | |
408 | =item C<EVBACKEND_ALL> |
412 | =item C<EVBACKEND_ALL> |
409 | |
413 | |
410 | Try all backends (even potentially broken ones that wouldn't be tried |
414 | Try all backends (even potentially broken ones that wouldn't be tried |
411 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
415 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
412 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
416 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
… | |
… | |
414 | It is definitely not recommended to use this flag. |
418 | It is definitely not recommended to use this flag. |
415 | |
419 | |
416 | =back |
420 | =back |
417 | |
421 | |
418 | If one or more of these are ored into the flags value, then only these |
422 | If one or more of these are ored into the flags value, then only these |
419 | backends will be tried (in the reverse order as given here). If none are |
423 | backends will be tried (in the reverse order as listed here). If none are |
420 | specified, most compiled-in backend will be tried, usually in reverse |
424 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
421 | order of their flag values :) |
|
|
422 | |
425 | |
423 | The most typical usage is like this: |
426 | The most typical usage is like this: |
424 | |
427 | |
425 | if (!ev_default_loop (0)) |
428 | if (!ev_default_loop (0)) |
426 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
429 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
551 | usually a better approach for this kind of thing. |
554 | usually a better approach for this kind of thing. |
552 | |
555 | |
553 | Here are the gory details of what C<ev_loop> does: |
556 | Here are the gory details of what C<ev_loop> does: |
554 | |
557 | |
555 | - Before the first iteration, call any pending watchers. |
558 | - Before the first iteration, call any pending watchers. |
556 | * If there are no active watchers (reference count is zero), return. |
559 | * If EVFLAG_FORKCHECK was used, check for a fork. |
557 | - Queue all prepare watchers and then call all outstanding watchers. |
560 | - If a fork was detected, queue and call all fork watchers. |
|
|
561 | - Queue and call all prepare watchers. |
558 | - If we have been forked, recreate the kernel state. |
562 | - If we have been forked, recreate the kernel state. |
559 | - Update the kernel state with all outstanding changes. |
563 | - Update the kernel state with all outstanding changes. |
560 | - Update the "event loop time". |
564 | - Update the "event loop time". |
561 | - Calculate for how long to block. |
565 | - Calculate for how long to sleep or block, if at all |
|
|
566 | (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
567 | any active watchers at all will result in not sleeping). |
|
|
568 | - Sleep if the I/O and timer collect interval say so. |
562 | - Block the process, waiting for any events. |
569 | - Block the process, waiting for any events. |
563 | - Queue all outstanding I/O (fd) events. |
570 | - Queue all outstanding I/O (fd) events. |
564 | - Update the "event loop time" and do time jump handling. |
571 | - Update the "event loop time" and do time jump handling. |
565 | - Queue all outstanding timers. |
572 | - Queue all outstanding timers. |
566 | - Queue all outstanding periodics. |
573 | - Queue all outstanding periodics. |
567 | - If no events are pending now, queue all idle watchers. |
574 | - If no events are pending now, queue all idle watchers. |
568 | - Queue all check watchers. |
575 | - Queue all check watchers. |
569 | - Call all queued watchers in reverse order (i.e. check watchers first). |
576 | - Call all queued watchers in reverse order (i.e. check watchers first). |
570 | Signals and child watchers are implemented as I/O watchers, and will |
577 | Signals and child watchers are implemented as I/O watchers, and will |
571 | be handled here by queueing them when their watcher gets executed. |
578 | be handled here by queueing them when their watcher gets executed. |
572 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
579 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
573 | were used, return, otherwise continue with step *. |
580 | were used, or there are no active watchers, return, otherwise |
|
|
581 | continue with step *. |
574 | |
582 | |
575 | Example: Queue some jobs and then loop until no events are outsanding |
583 | Example: Queue some jobs and then loop until no events are outstanding |
576 | anymore. |
584 | anymore. |
577 | |
585 | |
578 | ... queue jobs here, make sure they register event watchers as long |
586 | ... queue jobs here, make sure they register event watchers as long |
579 | ... as they still have work to do (even an idle watcher will do..) |
587 | ... as they still have work to do (even an idle watcher will do..) |
580 | ev_loop (my_loop, 0); |
588 | ev_loop (my_loop, 0); |
… | |
… | |
584 | |
592 | |
585 | Can be used to make a call to C<ev_loop> return early (but only after it |
593 | Can be used to make a call to C<ev_loop> return early (but only after it |
586 | has processed all outstanding events). The C<how> argument must be either |
594 | has processed all outstanding events). The C<how> argument must be either |
587 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
595 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
588 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
596 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
|
|
597 | |
|
|
598 | This "unloop state" will be cleared when entering C<ev_loop> again. |
589 | |
599 | |
590 | =item ev_ref (loop) |
600 | =item ev_ref (loop) |
591 | |
601 | |
592 | =item ev_unref (loop) |
602 | =item ev_unref (loop) |
593 | |
603 | |
… | |
… | |
598 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
608 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
599 | example, libev itself uses this for its internal signal pipe: It is not |
609 | example, libev itself uses this for its internal signal pipe: It is not |
600 | visible to the libev user and should not keep C<ev_loop> from exiting if |
610 | visible to the libev user and should not keep C<ev_loop> from exiting if |
601 | no event watchers registered by it are active. It is also an excellent |
611 | no event watchers registered by it are active. It is also an excellent |
602 | way to do this for generic recurring timers or from within third-party |
612 | way to do this for generic recurring timers or from within third-party |
603 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
613 | libraries. Just remember to I<unref after start> and I<ref before stop> |
|
|
614 | (but only if the watcher wasn't active before, or was active before, |
|
|
615 | respectively). |
604 | |
616 | |
605 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
617 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
606 | running when nothing else is active. |
618 | running when nothing else is active. |
607 | |
619 | |
608 | struct ev_signal exitsig; |
620 | struct ev_signal exitsig; |
… | |
… | |
983 | In general you can register as many read and/or write event watchers per |
995 | In general you can register as many read and/or write event watchers per |
984 | fd as you want (as long as you don't confuse yourself). Setting all file |
996 | fd as you want (as long as you don't confuse yourself). Setting all file |
985 | descriptors to non-blocking mode is also usually a good idea (but not |
997 | descriptors to non-blocking mode is also usually a good idea (but not |
986 | required if you know what you are doing). |
998 | required if you know what you are doing). |
987 | |
999 | |
988 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
989 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
990 | descriptors correctly if you register interest in two or more fds pointing |
|
|
991 | to the same underlying file/socket/etc. description (that is, they share |
|
|
992 | the same underlying "file open"). |
|
|
993 | |
|
|
994 | If you must do this, then force the use of a known-to-be-good backend |
1000 | If you must do this, then force the use of a known-to-be-good backend |
995 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
1001 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
996 | C<EVBACKEND_POLL>). |
1002 | C<EVBACKEND_POLL>). |
997 | |
1003 | |
998 | Another thing you have to watch out for is that it is quite easy to |
1004 | Another thing you have to watch out for is that it is quite easy to |
… | |
… | |
1033 | |
1039 | |
1034 | =head3 The special problem of dup'ed file descriptors |
1040 | =head3 The special problem of dup'ed file descriptors |
1035 | |
1041 | |
1036 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1042 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1037 | but only events for the underlying file descriptions. That means when you |
1043 | but only events for the underlying file descriptions. That means when you |
1038 | have C<dup ()>'ed file descriptors and register events for them, only one |
1044 | have C<dup ()>'ed file descriptors or weirder constellations, and register |
1039 | file descriptor might actually receive events. |
1045 | events for them, only one file descriptor might actually receive events. |
1040 | |
1046 | |
1041 | There is no workaround possible except not registering events |
1047 | There is no workaround possible except not registering events |
1042 | for potentially C<dup ()>'ed file descriptors, or to resort to |
1048 | for potentially C<dup ()>'ed file descriptors, or to resort to |
1043 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1049 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1044 | |
1050 | |
… | |
… | |
1073 | =item int events [read-only] |
1079 | =item int events [read-only] |
1074 | |
1080 | |
1075 | The events being watched. |
1081 | The events being watched. |
1076 | |
1082 | |
1077 | =back |
1083 | =back |
|
|
1084 | |
|
|
1085 | =head3 Examples |
1078 | |
1086 | |
1079 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1087 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1080 | readable, but only once. Since it is likely line-buffered, you could |
1088 | readable, but only once. Since it is likely line-buffered, you could |
1081 | attempt to read a whole line in the callback. |
1089 | attempt to read a whole line in the callback. |
1082 | |
1090 | |
… | |
… | |
1180 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1188 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1181 | which is also when any modifications are taken into account. |
1189 | which is also when any modifications are taken into account. |
1182 | |
1190 | |
1183 | =back |
1191 | =back |
1184 | |
1192 | |
|
|
1193 | =head3 Examples |
|
|
1194 | |
1185 | Example: Create a timer that fires after 60 seconds. |
1195 | Example: Create a timer that fires after 60 seconds. |
1186 | |
1196 | |
1187 | static void |
1197 | static void |
1188 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1198 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1189 | { |
1199 | { |
… | |
… | |
1346 | When active, contains the absolute time that the watcher is supposed to |
1356 | When active, contains the absolute time that the watcher is supposed to |
1347 | trigger next. |
1357 | trigger next. |
1348 | |
1358 | |
1349 | =back |
1359 | =back |
1350 | |
1360 | |
|
|
1361 | =head3 Examples |
|
|
1362 | |
1351 | Example: Call a callback every hour, or, more precisely, whenever the |
1363 | Example: Call a callback every hour, or, more precisely, whenever the |
1352 | system clock is divisible by 3600. The callback invocation times have |
1364 | system clock is divisible by 3600. The callback invocation times have |
1353 | potentially a lot of jittering, but good long-term stability. |
1365 | potentially a lot of jittering, but good long-term stability. |
1354 | |
1366 | |
1355 | static void |
1367 | static void |
… | |
… | |
1446 | |
1458 | |
1447 | The process exit/trace status caused by C<rpid> (see your systems |
1459 | The process exit/trace status caused by C<rpid> (see your systems |
1448 | C<waitpid> and C<sys/wait.h> documentation for details). |
1460 | C<waitpid> and C<sys/wait.h> documentation for details). |
1449 | |
1461 | |
1450 | =back |
1462 | =back |
|
|
1463 | |
|
|
1464 | =head3 Examples |
1451 | |
1465 | |
1452 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1466 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1453 | |
1467 | |
1454 | static void |
1468 | static void |
1455 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1469 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
… | |
… | |
1496 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1510 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1497 | to fall back to regular polling again even with inotify, but changes are |
1511 | to fall back to regular polling again even with inotify, but changes are |
1498 | usually detected immediately, and if the file exists there will be no |
1512 | usually detected immediately, and if the file exists there will be no |
1499 | polling. |
1513 | polling. |
1500 | |
1514 | |
|
|
1515 | =head3 Inotify |
|
|
1516 | |
|
|
1517 | When C<inotify (7)> support has been compiled into libev (generally only |
|
|
1518 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1519 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1520 | when the first C<ev_stat> watcher is being started. |
|
|
1521 | |
|
|
1522 | Inotify presense does not change the semantics of C<ev_stat> watchers |
|
|
1523 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1524 | making regular C<stat> calls. Even in the presense of inotify support |
|
|
1525 | there are many cases where libev has to resort to regular C<stat> polling. |
|
|
1526 | |
|
|
1527 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1528 | implement this functionality, due to the requirement of having a file |
|
|
1529 | descriptor open on the object at all times). |
|
|
1530 | |
|
|
1531 | =head3 The special problem of stat time resolution |
|
|
1532 | |
|
|
1533 | The C<stat ()> syscall only supports full-second resolution portably, and |
|
|
1534 | even on systems where the resolution is higher, many filesystems still |
|
|
1535 | only support whole seconds. |
|
|
1536 | |
|
|
1537 | That means that, if the time is the only thing that changes, you might |
|
|
1538 | miss updates: on the first update, C<ev_stat> detects a change and calls |
|
|
1539 | your callback, which does something. When there is another update within |
|
|
1540 | the same second, C<ev_stat> will be unable to detect it. |
|
|
1541 | |
|
|
1542 | The solution to this is to delay acting on a change for a second (or till |
|
|
1543 | the next second boundary), using a roughly one-second delay C<ev_timer> |
|
|
1544 | (C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01> |
|
|
1545 | is added to work around small timing inconsistencies of some operating |
|
|
1546 | systems. |
|
|
1547 | |
1501 | =head3 Watcher-Specific Functions and Data Members |
1548 | =head3 Watcher-Specific Functions and Data Members |
1502 | |
1549 | |
1503 | =over 4 |
1550 | =over 4 |
1504 | |
1551 | |
1505 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1552 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
… | |
… | |
1542 | =item const char *path [read-only] |
1589 | =item const char *path [read-only] |
1543 | |
1590 | |
1544 | The filesystem path that is being watched. |
1591 | The filesystem path that is being watched. |
1545 | |
1592 | |
1546 | =back |
1593 | =back |
|
|
1594 | |
|
|
1595 | =head3 Examples |
1547 | |
1596 | |
1548 | Example: Watch C</etc/passwd> for attribute changes. |
1597 | Example: Watch C</etc/passwd> for attribute changes. |
1549 | |
1598 | |
1550 | static void |
1599 | static void |
1551 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1600 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
… | |
… | |
1564 | } |
1613 | } |
1565 | |
1614 | |
1566 | ... |
1615 | ... |
1567 | ev_stat passwd; |
1616 | ev_stat passwd; |
1568 | |
1617 | |
1569 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1618 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1570 | ev_stat_start (loop, &passwd); |
1619 | ev_stat_start (loop, &passwd); |
|
|
1620 | |
|
|
1621 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1622 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1623 | one might do the work both on C<ev_stat> callback invocation I<and> on |
|
|
1624 | C<ev_timer> callback invocation). |
|
|
1625 | |
|
|
1626 | static ev_stat passwd; |
|
|
1627 | static ev_timer timer; |
|
|
1628 | |
|
|
1629 | static void |
|
|
1630 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1631 | { |
|
|
1632 | ev_timer_stop (EV_A_ w); |
|
|
1633 | |
|
|
1634 | /* now it's one second after the most recent passwd change */ |
|
|
1635 | } |
|
|
1636 | |
|
|
1637 | static void |
|
|
1638 | stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1639 | { |
|
|
1640 | /* reset the one-second timer */ |
|
|
1641 | ev_timer_again (EV_A_ &timer); |
|
|
1642 | } |
|
|
1643 | |
|
|
1644 | ... |
|
|
1645 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
|
|
1646 | ev_stat_start (loop, &passwd); |
|
|
1647 | ev_timer_init (&timer, timer_cb, 0., 1.01); |
1571 | |
1648 | |
1572 | |
1649 | |
1573 | =head2 C<ev_idle> - when you've got nothing better to do... |
1650 | =head2 C<ev_idle> - when you've got nothing better to do... |
1574 | |
1651 | |
1575 | Idle watchers trigger events when no other events of the same or higher |
1652 | Idle watchers trigger events when no other events of the same or higher |
… | |
… | |
1600 | Initialises and configures the idle watcher - it has no parameters of any |
1677 | Initialises and configures the idle watcher - it has no parameters of any |
1601 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1678 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1602 | believe me. |
1679 | believe me. |
1603 | |
1680 | |
1604 | =back |
1681 | =back |
|
|
1682 | |
|
|
1683 | =head3 Examples |
1605 | |
1684 | |
1606 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1685 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1607 | callback, free it. Also, use no error checking, as usual. |
1686 | callback, free it. Also, use no error checking, as usual. |
1608 | |
1687 | |
1609 | static void |
1688 | static void |
… | |
… | |
1681 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1760 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1682 | macros, but using them is utterly, utterly and completely pointless. |
1761 | macros, but using them is utterly, utterly and completely pointless. |
1683 | |
1762 | |
1684 | =back |
1763 | =back |
1685 | |
1764 | |
|
|
1765 | =head3 Examples |
|
|
1766 | |
1686 | There are a number of principal ways to embed other event loops or modules |
1767 | There are a number of principal ways to embed other event loops or modules |
1687 | into libev. Here are some ideas on how to include libadns into libev |
1768 | into libev. Here are some ideas on how to include libadns into libev |
1688 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1769 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1689 | use for an actually working example. Another Perl module named C<EV::Glib> |
1770 | use for an actually working example. Another Perl module named C<EV::Glib> |
1690 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
1771 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
… | |
… | |
1858 | portable one. |
1939 | portable one. |
1859 | |
1940 | |
1860 | So when you want to use this feature you will always have to be prepared |
1941 | So when you want to use this feature you will always have to be prepared |
1861 | that you cannot get an embeddable loop. The recommended way to get around |
1942 | that you cannot get an embeddable loop. The recommended way to get around |
1862 | this is to have a separate variables for your embeddable loop, try to |
1943 | this is to have a separate variables for your embeddable loop, try to |
1863 | create it, and if that fails, use the normal loop for everything: |
1944 | create it, and if that fails, use the normal loop for everything. |
|
|
1945 | |
|
|
1946 | =head3 Watcher-Specific Functions and Data Members |
|
|
1947 | |
|
|
1948 | =over 4 |
|
|
1949 | |
|
|
1950 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1951 | |
|
|
1952 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1953 | |
|
|
1954 | Configures the watcher to embed the given loop, which must be |
|
|
1955 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1956 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1957 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1958 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1959 | |
|
|
1960 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1961 | |
|
|
1962 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1963 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1964 | apropriate way for embedded loops. |
|
|
1965 | |
|
|
1966 | =item struct ev_loop *other [read-only] |
|
|
1967 | |
|
|
1968 | The embedded event loop. |
|
|
1969 | |
|
|
1970 | =back |
|
|
1971 | |
|
|
1972 | =head3 Examples |
|
|
1973 | |
|
|
1974 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
1975 | event loop. If that is not possible, use the default loop. The default |
|
|
1976 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
|
|
1977 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
|
|
1978 | used). |
1864 | |
1979 | |
1865 | struct ev_loop *loop_hi = ev_default_init (0); |
1980 | struct ev_loop *loop_hi = ev_default_init (0); |
1866 | struct ev_loop *loop_lo = 0; |
1981 | struct ev_loop *loop_lo = 0; |
1867 | struct ev_embed embed; |
1982 | struct ev_embed embed; |
1868 | |
1983 | |
… | |
… | |
1879 | ev_embed_start (loop_hi, &embed); |
1994 | ev_embed_start (loop_hi, &embed); |
1880 | } |
1995 | } |
1881 | else |
1996 | else |
1882 | loop_lo = loop_hi; |
1997 | loop_lo = loop_hi; |
1883 | |
1998 | |
1884 | =head3 Watcher-Specific Functions and Data Members |
1999 | Example: Check if kqueue is available but not recommended and create |
|
|
2000 | a kqueue backend for use with sockets (which usually work with any |
|
|
2001 | kqueue implementation). Store the kqueue/socket-only event loop in |
|
|
2002 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
1885 | |
2003 | |
1886 | =over 4 |
2004 | struct ev_loop *loop = ev_default_init (0); |
|
|
2005 | struct ev_loop *loop_socket = 0; |
|
|
2006 | struct ev_embed embed; |
|
|
2007 | |
|
|
2008 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2009 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2010 | { |
|
|
2011 | ev_embed_init (&embed, 0, loop_socket); |
|
|
2012 | ev_embed_start (loop, &embed); |
|
|
2013 | } |
1887 | |
2014 | |
1888 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
2015 | if (!loop_socket) |
|
|
2016 | loop_socket = loop; |
1889 | |
2017 | |
1890 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
2018 | // now use loop_socket for all sockets, and loop for everything else |
1891 | |
|
|
1892 | Configures the watcher to embed the given loop, which must be |
|
|
1893 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1894 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1895 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1896 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1897 | |
|
|
1898 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1899 | |
|
|
1900 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1901 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1902 | apropriate way for embedded loops. |
|
|
1903 | |
|
|
1904 | =item struct ev_loop *other [read-only] |
|
|
1905 | |
|
|
1906 | The embedded event loop. |
|
|
1907 | |
|
|
1908 | =back |
|
|
1909 | |
2019 | |
1910 | |
2020 | |
1911 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2021 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
1912 | |
2022 | |
1913 | Fork watchers are called when a C<fork ()> was detected (usually because |
2023 | Fork watchers are called when a C<fork ()> was detected (usually because |
… | |
… | |
2392 | wants osf handles on win32 (this is the case when the select to |
2502 | wants osf handles on win32 (this is the case when the select to |
2393 | be used is the winsock select). This means that it will call |
2503 | be used is the winsock select). This means that it will call |
2394 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2504 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2395 | it is assumed that all these functions actually work on fds, even |
2505 | it is assumed that all these functions actually work on fds, even |
2396 | on win32. Should not be defined on non-win32 platforms. |
2506 | on win32. Should not be defined on non-win32 platforms. |
|
|
2507 | |
|
|
2508 | =item EV_FD_TO_WIN32_HANDLE |
|
|
2509 | |
|
|
2510 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
|
|
2511 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2512 | default), then libev will call C<_get_osfhandle>, which is usually |
|
|
2513 | correct. In some cases, programs use their own file descriptor management, |
|
|
2514 | in which case they can provide this function to map fds to socket handles. |
2397 | |
2515 | |
2398 | =item EV_USE_POLL |
2516 | =item EV_USE_POLL |
2399 | |
2517 | |
2400 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2518 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2401 | backend. Otherwise it will be enabled on non-win32 platforms. It |
2519 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
2438 | be detected at runtime. |
2556 | be detected at runtime. |
2439 | |
2557 | |
2440 | =item EV_H |
2558 | =item EV_H |
2441 | |
2559 | |
2442 | The name of the F<ev.h> header file used to include it. The default if |
2560 | The name of the F<ev.h> header file used to include it. The default if |
2443 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2561 | undefined is C<"ev.h"> in F<event.h> and F<ev.c>. This can be used to |
2444 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2562 | virtually rename the F<ev.h> header file in case of conflicts. |
2445 | |
2563 | |
2446 | =item EV_CONFIG_H |
2564 | =item EV_CONFIG_H |
2447 | |
2565 | |
2448 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2566 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2449 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2567 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2450 | C<EV_H>, above. |
2568 | C<EV_H>, above. |
2451 | |
2569 | |
2452 | =item EV_EVENT_H |
2570 | =item EV_EVENT_H |
2453 | |
2571 | |
2454 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2572 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2455 | of how the F<event.h> header can be found. |
2573 | of how the F<event.h> header can be found, the dfeault is C<"event.h">. |
2456 | |
2574 | |
2457 | =item EV_PROTOTYPES |
2575 | =item EV_PROTOTYPES |
2458 | |
2576 | |
2459 | If defined to be C<0>, then F<ev.h> will not define any function |
2577 | If defined to be C<0>, then F<ev.h> will not define any function |
2460 | prototypes, but still define all the structs and other symbols. This is |
2578 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2632 | |
2750 | |
2633 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2751 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2634 | |
2752 | |
2635 | This means that, when you have a watcher that triggers in one hour and |
2753 | This means that, when you have a watcher that triggers in one hour and |
2636 | there are 100 watchers that would trigger before that then inserting will |
2754 | there are 100 watchers that would trigger before that then inserting will |
2637 | have to skip those 100 watchers. |
2755 | have to skip roughly seven (C<ld 100>) of these watchers. |
2638 | |
2756 | |
2639 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2757 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
2640 | |
2758 | |
2641 | That means that for changing a timer costs less than removing/adding them |
2759 | That means that changing a timer costs less than removing/adding them |
2642 | as only the relative motion in the event queue has to be paid for. |
2760 | as only the relative motion in the event queue has to be paid for. |
2643 | |
2761 | |
2644 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2762 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2645 | |
2763 | |
2646 | These just add the watcher into an array or at the head of a list. |
2764 | These just add the watcher into an array or at the head of a list. |
|
|
2765 | |
2647 | =item Stopping check/prepare/idle watchers: O(1) |
2766 | =item Stopping check/prepare/idle watchers: O(1) |
2648 | |
2767 | |
2649 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2768 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2650 | |
2769 | |
2651 | These watchers are stored in lists then need to be walked to find the |
2770 | These watchers are stored in lists then need to be walked to find the |
2652 | correct watcher to remove. The lists are usually short (you don't usually |
2771 | correct watcher to remove. The lists are usually short (you don't usually |
2653 | have many watchers waiting for the same fd or signal). |
2772 | have many watchers waiting for the same fd or signal). |
2654 | |
2773 | |
2655 | =item Finding the next timer per loop iteration: O(1) |
2774 | =item Finding the next timer in each loop iteration: O(1) |
|
|
2775 | |
|
|
2776 | By virtue of using a binary heap, the next timer is always found at the |
|
|
2777 | beginning of the storage array. |
2656 | |
2778 | |
2657 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2779 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2658 | |
2780 | |
2659 | A change means an I/O watcher gets started or stopped, which requires |
2781 | A change means an I/O watcher gets started or stopped, which requires |
2660 | libev to recalculate its status (and possibly tell the kernel). |
2782 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
2783 | on backend and wether C<ev_io_set> was used). |
2661 | |
2784 | |
2662 | =item Activating one watcher: O(1) |
2785 | =item Activating one watcher (putting it into the pending state): O(1) |
2663 | |
2786 | |
2664 | =item Priority handling: O(number_of_priorities) |
2787 | =item Priority handling: O(number_of_priorities) |
2665 | |
2788 | |
2666 | Priorities are implemented by allocating some space for each |
2789 | Priorities are implemented by allocating some space for each |
2667 | priority. When doing priority-based operations, libev usually has to |
2790 | priority. When doing priority-based operations, libev usually has to |
2668 | linearly search all the priorities. |
2791 | linearly search all the priorities, but starting/stopping and activating |
|
|
2792 | watchers becomes O(1) w.r.t. prioritiy handling. |
2669 | |
2793 | |
2670 | =back |
2794 | =back |
2671 | |
2795 | |
2672 | |
2796 | |
|
|
2797 | =head1 Win32 platform limitations and workarounds |
|
|
2798 | |
|
|
2799 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
|
|
2800 | requires, and its I/O model is fundamentally incompatible with the POSIX |
|
|
2801 | model. Libev still offers limited functionality on this platform in |
|
|
2802 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
|
|
2803 | descriptors. This only applies when using Win32 natively, not when using |
|
|
2804 | e.g. cygwin. |
|
|
2805 | |
|
|
2806 | There is no supported compilation method available on windows except |
|
|
2807 | embedding it into other applications. |
|
|
2808 | |
|
|
2809 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
2810 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
2811 | recommended (and not reasonable). If your program needs to use more than |
|
|
2812 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
2813 | implementation for windows, as libev offers the POSIX model, which cannot |
|
|
2814 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
2815 | |
|
|
2816 | =over 4 |
|
|
2817 | |
|
|
2818 | =item The winsocket select function |
|
|
2819 | |
|
|
2820 | The winsocket C<select> function doesn't follow POSIX in that it requires |
|
|
2821 | socket I<handles> and not socket I<file descriptors>. This makes select |
|
|
2822 | very inefficient, and also requires a mapping from file descriptors |
|
|
2823 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
|
|
2824 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
|
|
2825 | symbols for more info. |
|
|
2826 | |
|
|
2827 | The configuration for a "naked" win32 using the microsoft runtime |
|
|
2828 | libraries and raw winsocket select is: |
|
|
2829 | |
|
|
2830 | #define EV_USE_SELECT 1 |
|
|
2831 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
2832 | |
|
|
2833 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
2834 | complexity in the O(n²) range when using win32. |
|
|
2835 | |
|
|
2836 | =item Limited number of file descriptors |
|
|
2837 | |
|
|
2838 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
2839 | of winsocket's select only supported waiting for a max. of C<64> handles |
|
|
2840 | (probably owning to the fact that all windows kernels can only wait for |
|
|
2841 | C<64> things at the same time internally; microsoft recommends spawning a |
|
|
2842 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
2843 | |
|
|
2844 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
|
|
2845 | to some high number (e.g. C<2048>) before compiling the winsocket select |
|
|
2846 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
2847 | select emulation on windows). |
|
|
2848 | |
|
|
2849 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
2850 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
|
|
2851 | or something like this inside microsoft). You can increase this by calling |
|
|
2852 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
|
|
2853 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
2854 | libraries. |
|
|
2855 | |
|
|
2856 | This might get you to about C<512> or C<2048> sockets (depending on |
|
|
2857 | windows version and/or the phase of the moon). To get more, you need to |
|
|
2858 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
2859 | calling select (O(n²)) will likely make this unworkable. |
|
|
2860 | |
|
|
2861 | =back |
|
|
2862 | |
|
|
2863 | |
2673 | =head1 AUTHOR |
2864 | =head1 AUTHOR |
2674 | |
2865 | |
2675 | Marc Lehmann <libev@schmorp.de>. |
2866 | Marc Lehmann <libev@schmorp.de>. |
2676 | |
2867 | |