… | |
… | |
486 | 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 |
487 | usually a better approach for this kind of thing. |
487 | usually a better approach for this kind of thing. |
488 | |
488 | |
489 | Here are the gory details of what C<ev_loop> does: |
489 | Here are the gory details of what C<ev_loop> does: |
490 | |
490 | |
|
|
491 | - Before the first iteration, call any pending watchers. |
491 | * If there are no active watchers (reference count is zero), return. |
492 | * If there are no active watchers (reference count is zero), return. |
492 | - Queue prepare watchers and then call all outstanding watchers. |
493 | - Queue all prepare watchers and then call all outstanding watchers. |
493 | - If we have been forked, recreate the kernel state. |
494 | - If we have been forked, recreate the kernel state. |
494 | - Update the kernel state with all outstanding changes. |
495 | - Update the kernel state with all outstanding changes. |
495 | - Update the "event loop time". |
496 | - Update the "event loop time". |
496 | - Calculate for how long to block. |
497 | - Calculate for how long to block. |
497 | - Block the process, waiting for any events. |
498 | - Block the process, waiting for any events. |
… | |
… | |
1481 | 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 |
1482 | 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 |
1483 | loop from blocking if lower-priority coroutines are active, thus mapping |
1484 | loop from blocking if lower-priority coroutines are active, thus mapping |
1484 | low-priority coroutines to idle/background tasks). |
1485 | low-priority coroutines to idle/background tasks). |
1485 | |
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 | |
1486 | =over 4 |
1497 | =over 4 |
1487 | |
1498 | |
1488 | =item ev_prepare_init (ev_prepare *, callback) |
1499 | =item ev_prepare_init (ev_prepare *, callback) |
1489 | |
1500 | |
1490 | =item ev_check_init (ev_check *, callback) |
1501 | =item ev_check_init (ev_check *, callback) |
… | |
… | |
1493 | 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> |
1494 | macros, but using them is utterly, utterly and completely pointless. |
1505 | macros, but using them is utterly, utterly and completely pointless. |
1495 | |
1506 | |
1496 | =back |
1507 | =back |
1497 | |
1508 | |
1498 | 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 |
1499 | 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, |
1500 | 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 |
1501 | 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. |
1502 | |
1521 | |
1503 | static ev_io iow [nfd]; |
1522 | static ev_io iow [nfd]; |
1504 | static ev_timer tw; |
1523 | static ev_timer tw; |
1505 | |
1524 | |
1506 | static void |
1525 | static void |
1507 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1526 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1508 | { |
1527 | { |
1509 | // set the relevant poll flags |
|
|
1510 | // could also call adns_processreadable etc. here |
|
|
1511 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1512 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1513 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1514 | } |
1528 | } |
1515 | |
1529 | |
1516 | // create io watchers for each fd and a timer before blocking |
1530 | // create io watchers for each fd and a timer before blocking |
1517 | static void |
1531 | static void |
1518 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1532 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
… | |
… | |
1524 | |
1538 | |
1525 | /* 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 */ |
1526 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1540 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1527 | ev_timer_start (loop, &tw); |
1541 | ev_timer_start (loop, &tw); |
1528 | |
1542 | |
1529 | // create on ev_io per pollfd |
1543 | // create one ev_io per pollfd |
1530 | for (int i = 0; i < nfd; ++i) |
1544 | for (int i = 0; i < nfd; ++i) |
1531 | { |
1545 | { |
1532 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1546 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1533 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1547 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1534 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1548 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1535 | |
1549 | |
1536 | fds [i].revents = 0; |
1550 | fds [i].revents = 0; |
1537 | iow [i].data = fds + i; |
|
|
1538 | ev_io_start (loop, iow + i); |
1551 | ev_io_start (loop, iow + i); |
1539 | } |
1552 | } |
1540 | } |
1553 | } |
1541 | |
1554 | |
1542 | // stop all watchers after blocking |
1555 | // stop all watchers after blocking |
… | |
… | |
1544 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1557 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1545 | { |
1558 | { |
1546 | ev_timer_stop (loop, &tw); |
1559 | ev_timer_stop (loop, &tw); |
1547 | |
1560 | |
1548 | 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 |
1549 | ev_io_stop (loop, iow + i); |
1571 | ev_io_stop (loop, iow + i); |
|
|
1572 | } |
1550 | |
1573 | |
1551 | 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; |
1552 | } |
1634 | } |
1553 | |
1635 | |
1554 | |
1636 | |
1555 | =head2 C<ev_embed> - when one backend isn't enough... |
1637 | =head2 C<ev_embed> - when one backend isn't enough... |
1556 | |
1638 | |
… | |
… | |
1844 | |
1926 | |
1845 | myclass obj; |
1927 | myclass obj; |
1846 | ev::io iow; |
1928 | ev::io iow; |
1847 | iow.set <myclass, &myclass::io_cb> (&obj); |
1929 | iow.set <myclass, &myclass::io_cb> (&obj); |
1848 | |
1930 | |
1849 | =item w->set (void (*function)(watcher &w, int), void *data = 0) |
1931 | =item w->set<function> (void *data = 0) |
1850 | |
1932 | |
1851 | Also sets a callback, but uses a static method or plain function as |
1933 | Also sets a callback, but uses a static method or plain function as |
1852 | callback. The optional C<data> argument will be stored in the watcher's |
1934 | callback. The optional C<data> argument will be stored in the watcher's |
1853 | C<data> member and is free for you to use. |
1935 | C<data> member and is free for you to use. |
1854 | |
1936 | |
|
|
1937 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
1938 | |
1855 | See the method-C<set> above for more details. |
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> (); |
1856 | |
1945 | |
1857 | =item w->set (struct ev_loop *) |
1946 | =item w->set (struct ev_loop *) |
1858 | |
1947 | |
1859 | 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 |
1860 | do this when the watcher is inactive (and not pending either). |
1949 | do this when the watcher is inactive (and not pending either). |