… | |
… | |
47 | |
47 | |
48 | return 0; |
48 | return 0; |
49 | } |
49 | } |
50 | |
50 | |
51 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
|
|
52 | |
|
|
53 | The newest version of this document is also available as a html-formatted |
|
|
54 | web page you might find easier to navigate when reading it for the first |
|
|
55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
52 | |
56 | |
53 | Libev is an event loop: you register interest in certain events (such as a |
57 | Libev is an event loop: you register interest in certain events (such as a |
54 | file descriptor being readable or a timeout occuring), and it will manage |
58 | file descriptor being readable or a timeout occuring), and it will manage |
55 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
56 | |
60 | |
… | |
… | |
482 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
486 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
483 | usually a better approach for this kind of thing. |
487 | usually a better approach for this kind of thing. |
484 | |
488 | |
485 | Here are the gory details of what C<ev_loop> does: |
489 | Here are the gory details of what C<ev_loop> does: |
486 | |
490 | |
|
|
491 | - Before the first iteration, call any pending watchers. |
487 | * If there are no active watchers (reference count is zero), return. |
492 | * If there are no active watchers (reference count is zero), return. |
488 | - Queue prepare watchers and then call all outstanding watchers. |
493 | - Queue all prepare watchers and then call all outstanding watchers. |
489 | - If we have been forked, recreate the kernel state. |
494 | - If we have been forked, recreate the kernel state. |
490 | - Update the kernel state with all outstanding changes. |
495 | - Update the kernel state with all outstanding changes. |
491 | - Update the "event loop time". |
496 | - Update the "event loop time". |
492 | - Calculate for how long to block. |
497 | - Calculate for how long to block. |
493 | - Block the process, waiting for any events. |
498 | - Block the process, waiting for any events. |
… | |
… | |
732 | =item bool ev_is_pending (ev_TYPE *watcher) |
737 | =item bool ev_is_pending (ev_TYPE *watcher) |
733 | |
738 | |
734 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
739 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
735 | events but its callback has not yet been invoked). As long as a watcher |
740 | events but its callback has not yet been invoked). As long as a watcher |
736 | is pending (but not active) you must not call an init function on it (but |
741 | is pending (but not active) you must not call an init function on it (but |
737 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
742 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
738 | libev (e.g. you cnanot C<free ()> it). |
743 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
|
|
744 | it). |
739 | |
745 | |
740 | =item callback ev_cb (ev_TYPE *watcher) |
746 | =item callback ev_cb (ev_TYPE *watcher) |
741 | |
747 | |
742 | Returns the callback currently set on the watcher. |
748 | Returns the callback currently set on the watcher. |
743 | |
749 | |
… | |
… | |
762 | watchers on the same event and make sure one is called first. |
768 | watchers on the same event and make sure one is called first. |
763 | |
769 | |
764 | If you need to suppress invocation when higher priority events are pending |
770 | If you need to suppress invocation when higher priority events are pending |
765 | you need to look at C<ev_idle> watchers, which provide this functionality. |
771 | you need to look at C<ev_idle> watchers, which provide this functionality. |
766 | |
772 | |
|
|
773 | You I<must not> change the priority of a watcher as long as it is active or |
|
|
774 | pending. |
|
|
775 | |
767 | The default priority used by watchers when no priority has been set is |
776 | The default priority used by watchers when no priority has been set is |
768 | always C<0>, which is supposed to not be too high and not be too low :). |
777 | always C<0>, which is supposed to not be too high and not be too low :). |
769 | |
778 | |
770 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
779 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
771 | fine, as long as you do not mind that the priority value you query might |
780 | fine, as long as you do not mind that the priority value you query might |
772 | or might not have been adjusted to be within valid range. |
781 | or might not have been adjusted to be within valid range. |
|
|
782 | |
|
|
783 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
|
|
784 | |
|
|
785 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
|
|
786 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
|
|
787 | can deal with that fact. |
|
|
788 | |
|
|
789 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
|
|
790 | |
|
|
791 | If the watcher is pending, this function returns clears its pending status |
|
|
792 | and returns its C<revents> bitset (as if its callback was invoked). If the |
|
|
793 | watcher isn't pending it does nothing and returns C<0>. |
773 | |
794 | |
774 | =back |
795 | =back |
775 | |
796 | |
776 | |
797 | |
777 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
798 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
883 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
904 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
884 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
905 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
885 | |
906 | |
886 | If you cannot run the fd in non-blocking mode (for example you should not |
907 | If you cannot run the fd in non-blocking mode (for example you should not |
887 | play around with an Xlib connection), then you have to seperately re-test |
908 | play around with an Xlib connection), then you have to seperately re-test |
888 | wether a file descriptor is really ready with a known-to-be good interface |
909 | whether a file descriptor is really ready with a known-to-be good interface |
889 | such as poll (fortunately in our Xlib example, Xlib already does this on |
910 | such as poll (fortunately in our Xlib example, Xlib already does this on |
890 | its own, so its quite safe to use). |
911 | its own, so its quite safe to use). |
891 | |
912 | |
892 | =over 4 |
913 | =over 4 |
893 | |
914 | |
… | |
… | |
1461 | with priority higher than or equal to the event loop and one coroutine |
1482 | with priority higher than or equal to the event loop and one coroutine |
1462 | of lower priority, but only once, using idle watchers to keep the event |
1483 | of lower priority, but only once, using idle watchers to keep the event |
1463 | loop from blocking if lower-priority coroutines are active, thus mapping |
1484 | loop from blocking if lower-priority coroutines are active, thus mapping |
1464 | low-priority coroutines to idle/background tasks). |
1485 | low-priority coroutines to idle/background tasks). |
1465 | |
1486 | |
|
|
1487 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
|
|
1488 | priority, to ensure that they are being run before any other watchers |
|
|
1489 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
|
|
1490 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1491 | supports this, they will be called before other C<ev_check> watchers did |
|
|
1492 | their job. As C<ev_check> watchers are often used to embed other event |
|
|
1493 | loops those other event loops might be in an unusable state until their |
|
|
1494 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
|
|
1495 | others). |
|
|
1496 | |
1466 | =over 4 |
1497 | =over 4 |
1467 | |
1498 | |
1468 | =item ev_prepare_init (ev_prepare *, callback) |
1499 | =item ev_prepare_init (ev_prepare *, callback) |
1469 | |
1500 | |
1470 | =item ev_check_init (ev_check *, callback) |
1501 | =item ev_check_init (ev_check *, callback) |
… | |
… | |
1473 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1504 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1474 | macros, but using them is utterly, utterly and completely pointless. |
1505 | macros, but using them is utterly, utterly and completely pointless. |
1475 | |
1506 | |
1476 | =back |
1507 | =back |
1477 | |
1508 | |
1478 | Example: To include a library such as adns, you would add IO watchers |
1509 | There are a number of principal ways to embed other event loops or modules |
1479 | and a timeout watcher in a prepare handler, as required by libadns, and |
1510 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1511 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1512 | use for an actually working example. Another Perl module named C<EV::Glib> |
|
|
1513 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
|
|
1514 | into the Glib event loop). |
|
|
1515 | |
|
|
1516 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
1480 | in a check watcher, destroy them and call into libadns. What follows is |
1517 | and in a check watcher, destroy them and call into libadns. What follows |
1481 | pseudo-code only of course: |
1518 | is pseudo-code only of course. This requires you to either use a low |
|
|
1519 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1520 | the callbacks for the IO/timeout watchers might not have been called yet. |
1482 | |
1521 | |
1483 | static ev_io iow [nfd]; |
1522 | static ev_io iow [nfd]; |
1484 | static ev_timer tw; |
1523 | static ev_timer tw; |
1485 | |
1524 | |
1486 | static void |
1525 | static void |
1487 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1526 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1488 | { |
1527 | { |
1489 | // set the relevant poll flags |
|
|
1490 | // could also call adns_processreadable etc. here |
|
|
1491 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1492 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1493 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1494 | } |
1528 | } |
1495 | |
1529 | |
1496 | // create io watchers for each fd and a timer before blocking |
1530 | // create io watchers for each fd and a timer before blocking |
1497 | static void |
1531 | static void |
1498 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1532 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
… | |
… | |
1504 | |
1538 | |
1505 | /* the callback is illegal, but won't be called as we stop during check */ |
1539 | /* the callback is illegal, but won't be called as we stop during check */ |
1506 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1540 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1507 | ev_timer_start (loop, &tw); |
1541 | ev_timer_start (loop, &tw); |
1508 | |
1542 | |
1509 | // create on ev_io per pollfd |
1543 | // create one ev_io per pollfd |
1510 | for (int i = 0; i < nfd; ++i) |
1544 | for (int i = 0; i < nfd; ++i) |
1511 | { |
1545 | { |
1512 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1546 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1513 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1547 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1514 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1548 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1515 | |
1549 | |
1516 | fds [i].revents = 0; |
1550 | fds [i].revents = 0; |
1517 | iow [i].data = fds + i; |
|
|
1518 | ev_io_start (loop, iow + i); |
1551 | ev_io_start (loop, iow + i); |
1519 | } |
1552 | } |
1520 | } |
1553 | } |
1521 | |
1554 | |
1522 | // stop all watchers after blocking |
1555 | // stop all watchers after blocking |
… | |
… | |
1524 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1557 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1525 | { |
1558 | { |
1526 | ev_timer_stop (loop, &tw); |
1559 | ev_timer_stop (loop, &tw); |
1527 | |
1560 | |
1528 | for (int i = 0; i < nfd; ++i) |
1561 | for (int i = 0; i < nfd; ++i) |
|
|
1562 | { |
|
|
1563 | // set the relevant poll flags |
|
|
1564 | // could also call adns_processreadable etc. here |
|
|
1565 | struct pollfd *fd = fds + i; |
|
|
1566 | int revents = ev_clear_pending (iow + i); |
|
|
1567 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1568 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1569 | |
|
|
1570 | // now stop the watcher |
1529 | ev_io_stop (loop, iow + i); |
1571 | ev_io_stop (loop, iow + i); |
|
|
1572 | } |
1530 | |
1573 | |
1531 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1574 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1575 | } |
|
|
1576 | |
|
|
1577 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1578 | in the prepare watcher and would dispose of the check watcher. |
|
|
1579 | |
|
|
1580 | Method 3: If the module to be embedded supports explicit event |
|
|
1581 | notification (adns does), you can also make use of the actual watcher |
|
|
1582 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1583 | |
|
|
1584 | static void |
|
|
1585 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1586 | { |
|
|
1587 | adns_state ads = (adns_state)w->data; |
|
|
1588 | update_now (EV_A); |
|
|
1589 | |
|
|
1590 | adns_processtimeouts (ads, &tv_now); |
|
|
1591 | } |
|
|
1592 | |
|
|
1593 | static void |
|
|
1594 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1595 | { |
|
|
1596 | adns_state ads = (adns_state)w->data; |
|
|
1597 | update_now (EV_A); |
|
|
1598 | |
|
|
1599 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1600 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1601 | } |
|
|
1602 | |
|
|
1603 | // do not ever call adns_afterpoll |
|
|
1604 | |
|
|
1605 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1606 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1607 | their poll function. The drawback with this solution is that the main |
|
|
1608 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1609 | this. |
|
|
1610 | |
|
|
1611 | static gint |
|
|
1612 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1613 | { |
|
|
1614 | int got_events = 0; |
|
|
1615 | |
|
|
1616 | for (n = 0; n < nfds; ++n) |
|
|
1617 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1618 | |
|
|
1619 | if (timeout >= 0) |
|
|
1620 | // create/start timer |
|
|
1621 | |
|
|
1622 | // poll |
|
|
1623 | ev_loop (EV_A_ 0); |
|
|
1624 | |
|
|
1625 | // stop timer again |
|
|
1626 | if (timeout >= 0) |
|
|
1627 | ev_timer_stop (EV_A_ &to); |
|
|
1628 | |
|
|
1629 | // stop io watchers again - their callbacks should have set |
|
|
1630 | for (n = 0; n < nfds; ++n) |
|
|
1631 | ev_io_stop (EV_A_ iow [n]); |
|
|
1632 | |
|
|
1633 | return got_events; |
1532 | } |
1634 | } |
1533 | |
1635 | |
1534 | |
1636 | |
1535 | =head2 C<ev_embed> - when one backend isn't enough... |
1637 | =head2 C<ev_embed> - when one backend isn't enough... |
1536 | |
1638 | |
… | |
… | |
1740 | |
1842 | |
1741 | To use it, |
1843 | To use it, |
1742 | |
1844 | |
1743 | #include <ev++.h> |
1845 | #include <ev++.h> |
1744 | |
1846 | |
1745 | (it is not installed by default). This automatically includes F<ev.h> |
1847 | This automatically includes F<ev.h> and puts all of its definitions (many |
1746 | and puts all of its definitions (many of them macros) into the global |
1848 | of them macros) into the global namespace. All C++ specific things are |
1747 | namespace. All C++ specific things are put into the C<ev> namespace. |
1849 | put into the C<ev> namespace. It should support all the same embedding |
|
|
1850 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1748 | |
1851 | |
1749 | It should support all the same embedding options as F<ev.h>, most notably |
1852 | Care has been taken to keep the overhead low. The only data member the C++ |
1750 | C<EV_MULTIPLICITY>. |
1853 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
1854 | that the watcher is associated with (or no additional members at all if |
|
|
1855 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
1856 | |
|
|
1857 | Currently, functions, and static and non-static member functions can be |
|
|
1858 | used as callbacks. Other types should be easy to add as long as they only |
|
|
1859 | need one additional pointer for context. If you need support for other |
|
|
1860 | types of functors please contact the author (preferably after implementing |
|
|
1861 | it). |
1751 | |
1862 | |
1752 | Here is a list of things available in the C<ev> namespace: |
1863 | Here is a list of things available in the C<ev> namespace: |
1753 | |
1864 | |
1754 | =over 4 |
1865 | =over 4 |
1755 | |
1866 | |
… | |
… | |
1771 | |
1882 | |
1772 | All of those classes have these methods: |
1883 | All of those classes have these methods: |
1773 | |
1884 | |
1774 | =over 4 |
1885 | =over 4 |
1775 | |
1886 | |
1776 | =item ev::TYPE::TYPE (object *, object::method *) |
1887 | =item ev::TYPE::TYPE () |
1777 | |
1888 | |
1778 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
1889 | =item ev::TYPE::TYPE (struct ev_loop *) |
1779 | |
1890 | |
1780 | =item ev::TYPE::~TYPE |
1891 | =item ev::TYPE::~TYPE |
1781 | |
1892 | |
1782 | The constructor takes a pointer to an object and a method pointer to |
1893 | The constructor (optionally) takes an event loop to associate the watcher |
1783 | the event handler callback to call in this class. The constructor calls |
1894 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1784 | C<ev_init> for you, which means you have to call the C<set> method |
1895 | |
1785 | before starting it. If you do not specify a loop then the constructor |
1896 | The constructor calls C<ev_init> for you, which means you have to call the |
1786 | automatically associates the default loop with this watcher. |
1897 | C<set> method before starting it. |
|
|
1898 | |
|
|
1899 | It will not set a callback, however: You have to call the templated C<set> |
|
|
1900 | method to set a callback before you can start the watcher. |
|
|
1901 | |
|
|
1902 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
1903 | not allow explicit template arguments for constructors). |
1787 | |
1904 | |
1788 | The destructor automatically stops the watcher if it is active. |
1905 | The destructor automatically stops the watcher if it is active. |
|
|
1906 | |
|
|
1907 | =item w->set<class, &class::method> (object *) |
|
|
1908 | |
|
|
1909 | This method sets the callback method to call. The method has to have a |
|
|
1910 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
1911 | first argument and the C<revents> as second. The object must be given as |
|
|
1912 | parameter and is stored in the C<data> member of the watcher. |
|
|
1913 | |
|
|
1914 | This method synthesizes efficient thunking code to call your method from |
|
|
1915 | the C callback that libev requires. If your compiler can inline your |
|
|
1916 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
1917 | your compiler is good :), then the method will be fully inlined into the |
|
|
1918 | thunking function, making it as fast as a direct C callback. |
|
|
1919 | |
|
|
1920 | Example: simple class declaration and watcher initialisation |
|
|
1921 | |
|
|
1922 | struct myclass |
|
|
1923 | { |
|
|
1924 | void io_cb (ev::io &w, int revents) { } |
|
|
1925 | } |
|
|
1926 | |
|
|
1927 | myclass obj; |
|
|
1928 | ev::io iow; |
|
|
1929 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
1930 | |
|
|
1931 | =item w->set<function> (void *data = 0) |
|
|
1932 | |
|
|
1933 | Also sets a callback, but uses a static method or plain function as |
|
|
1934 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
1935 | C<data> member and is free for you to use. |
|
|
1936 | |
|
|
1937 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
1938 | |
|
|
1939 | See the method-C<set> above for more details. |
|
|
1940 | |
|
|
1941 | Example: |
|
|
1942 | |
|
|
1943 | static void io_cb (ev::io &w, int revents) { } |
|
|
1944 | iow.set <io_cb> (); |
1789 | |
1945 | |
1790 | =item w->set (struct ev_loop *) |
1946 | =item w->set (struct ev_loop *) |
1791 | |
1947 | |
1792 | Associates a different C<struct ev_loop> with this watcher. You can only |
1948 | Associates a different C<struct ev_loop> with this watcher. You can only |
1793 | do this when the watcher is inactive (and not pending either). |
1949 | do this when the watcher is inactive (and not pending either). |
1794 | |
1950 | |
1795 | =item w->set ([args]) |
1951 | =item w->set ([args]) |
1796 | |
1952 | |
1797 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1953 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1798 | called at least once. Unlike the C counterpart, an active watcher gets |
1954 | called at least once. Unlike the C counterpart, an active watcher gets |
1799 | automatically stopped and restarted. |
1955 | automatically stopped and restarted when reconfiguring it with this |
|
|
1956 | method. |
1800 | |
1957 | |
1801 | =item w->start () |
1958 | =item w->start () |
1802 | |
1959 | |
1803 | Starts the watcher. Note that there is no C<loop> argument as the |
1960 | Starts the watcher. Note that there is no C<loop> argument, as the |
1804 | constructor already takes the loop. |
1961 | constructor already stores the event loop. |
1805 | |
1962 | |
1806 | =item w->stop () |
1963 | =item w->stop () |
1807 | |
1964 | |
1808 | Stops the watcher if it is active. Again, no C<loop> argument. |
1965 | Stops the watcher if it is active. Again, no C<loop> argument. |
1809 | |
1966 | |
… | |
… | |
1834 | |
1991 | |
1835 | myclass (); |
1992 | myclass (); |
1836 | } |
1993 | } |
1837 | |
1994 | |
1838 | myclass::myclass (int fd) |
1995 | myclass::myclass (int fd) |
1839 | : io (this, &myclass::io_cb), |
|
|
1840 | idle (this, &myclass::idle_cb) |
|
|
1841 | { |
1996 | { |
|
|
1997 | io .set <myclass, &myclass::io_cb > (this); |
|
|
1998 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
1999 | |
1842 | io.start (fd, ev::READ); |
2000 | io.start (fd, ev::READ); |
1843 | } |
2001 | } |
1844 | |
2002 | |
1845 | |
2003 | |
1846 | =head1 MACRO MAGIC |
2004 | =head1 MACRO MAGIC |
1847 | |
2005 | |
1848 | Libev can be compiled with a variety of options, the most fundemantal is |
2006 | Libev can be compiled with a variety of options, the most fundemantal is |
1849 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
2007 | C<EV_MULTIPLICITY>. This option determines whether (most) functions and |
1850 | callbacks have an initial C<struct ev_loop *> argument. |
2008 | callbacks have an initial C<struct ev_loop *> argument. |
1851 | |
2009 | |
1852 | To make it easier to write programs that cope with either variant, the |
2010 | To make it easier to write programs that cope with either variant, the |
1853 | following macros are defined: |
2011 | following macros are defined: |
1854 | |
2012 | |
… | |
… | |
1888 | loop, if multiple loops are supported ("ev loop default"). |
2046 | loop, if multiple loops are supported ("ev loop default"). |
1889 | |
2047 | |
1890 | =back |
2048 | =back |
1891 | |
2049 | |
1892 | Example: Declare and initialise a check watcher, utilising the above |
2050 | Example: Declare and initialise a check watcher, utilising the above |
1893 | macros so it will work regardless of wether multiple loops are supported |
2051 | macros so it will work regardless of whether multiple loops are supported |
1894 | or not. |
2052 | or not. |
1895 | |
2053 | |
1896 | static void |
2054 | static void |
1897 | check_cb (EV_P_ ev_timer *w, int revents) |
2055 | check_cb (EV_P_ ev_timer *w, int revents) |
1898 | { |
2056 | { |
… | |
… | |
2123 | will have the C<struct ev_loop *> as first argument, and you can create |
2281 | will have the C<struct ev_loop *> as first argument, and you can create |
2124 | additional independent event loops. Otherwise there will be no support |
2282 | additional independent event loops. Otherwise there will be no support |
2125 | for multiple event loops and there is no first event loop pointer |
2283 | for multiple event loops and there is no first event loop pointer |
2126 | argument. Instead, all functions act on the single default loop. |
2284 | argument. Instead, all functions act on the single default loop. |
2127 | |
2285 | |
|
|
2286 | =item EV_MINPRI |
|
|
2287 | |
|
|
2288 | =item EV_MAXPRI |
|
|
2289 | |
|
|
2290 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2291 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2292 | provide for more priorities by overriding those symbols (usually defined |
|
|
2293 | to be C<-2> and C<2>, respectively). |
|
|
2294 | |
|
|
2295 | When doing priority-based operations, libev usually has to linearly search |
|
|
2296 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2297 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2298 | fine. |
|
|
2299 | |
|
|
2300 | If your embedding app does not need any priorities, defining these both to |
|
|
2301 | C<0> will save some memory and cpu. |
|
|
2302 | |
2128 | =item EV_PERIODIC_ENABLE |
2303 | =item EV_PERIODIC_ENABLE |
2129 | |
2304 | |
2130 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2305 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2131 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2306 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2132 | code. |
2307 | code. |
… | |
… | |
2234 | |
2409 | |
2235 | In this section the complexities of (many of) the algorithms used inside |
2410 | In this section the complexities of (many of) the algorithms used inside |
2236 | libev will be explained. For complexity discussions about backends see the |
2411 | libev will be explained. For complexity discussions about backends see the |
2237 | documentation for C<ev_default_init>. |
2412 | documentation for C<ev_default_init>. |
2238 | |
2413 | |
|
|
2414 | All of the following are about amortised time: If an array needs to be |
|
|
2415 | extended, libev needs to realloc and move the whole array, but this |
|
|
2416 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2417 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2418 | it is much faster and asymptotically approaches constant time. |
|
|
2419 | |
2239 | =over 4 |
2420 | =over 4 |
2240 | |
2421 | |
2241 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2422 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2242 | |
2423 | |
|
|
2424 | This means that, when you have a watcher that triggers in one hour and |
|
|
2425 | there are 100 watchers that would trigger before that then inserting will |
|
|
2426 | have to skip those 100 watchers. |
|
|
2427 | |
2243 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2428 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2244 | |
2429 | |
|
|
2430 | That means that for changing a timer costs less than removing/adding them |
|
|
2431 | as only the relative motion in the event queue has to be paid for. |
|
|
2432 | |
2245 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2433 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2246 | |
2434 | |
|
|
2435 | These just add the watcher into an array or at the head of a list. |
2247 | =item Stopping check/prepare/idle watchers: O(1) |
2436 | =item Stopping check/prepare/idle watchers: O(1) |
2248 | |
2437 | |
2249 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2438 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2250 | |
2439 | |
|
|
2440 | These watchers are stored in lists then need to be walked to find the |
|
|
2441 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2442 | have many watchers waiting for the same fd or signal). |
|
|
2443 | |
2251 | =item Finding the next timer per loop iteration: O(1) |
2444 | =item Finding the next timer per loop iteration: O(1) |
2252 | |
2445 | |
2253 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2446 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2254 | |
2447 | |
|
|
2448 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2449 | libev to recalculate its status (and possibly tell the kernel). |
|
|
2450 | |
2255 | =item Activating one watcher: O(1) |
2451 | =item Activating one watcher: O(1) |
2256 | |
2452 | |
|
|
2453 | =item Priority handling: O(number_of_priorities) |
|
|
2454 | |
|
|
2455 | Priorities are implemented by allocating some space for each |
|
|
2456 | priority. When doing priority-based operations, libev usually has to |
|
|
2457 | linearly search all the priorities. |
|
|
2458 | |
2257 | =back |
2459 | =back |
2258 | |
2460 | |
2259 | |
2461 | |
2260 | =head1 AUTHOR |
2462 | =head1 AUTHOR |
2261 | |
2463 | |