| … | |
… | |
| 1493 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1493 | 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. |
1494 | macros, but using them is utterly, utterly and completely pointless. |
| 1495 | |
1495 | |
| 1496 | =back |
1496 | =back |
| 1497 | |
1497 | |
| 1498 | Example: To include a library such as adns, you would add IO watchers |
1498 | 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 |
1499 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1500 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1501 | use for an actually working example. Another Perl module named C<EV::Glib> |
|
|
1502 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
|
|
1503 | into the Glib event loop). |
|
|
1504 | |
|
|
1505 | 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 |
1506 | and in a check watcher, destroy them and call into libadns. What follows |
| 1501 | pseudo-code only of course: |
1507 | is pseudo-code only of course. This requires you to either use a low |
|
|
1508 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1509 | the callbacks for the IO/timeout watchers might not have been called yet. |
| 1502 | |
1510 | |
| 1503 | static ev_io iow [nfd]; |
1511 | static ev_io iow [nfd]; |
| 1504 | static ev_timer tw; |
1512 | static ev_timer tw; |
| 1505 | |
1513 | |
| 1506 | static void |
1514 | static void |
| 1507 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1515 | io_cb (ev_loop *loop, ev_io *w, int revents) |
| 1508 | { |
1516 | { |
| 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 | } |
1517 | } |
| 1515 | |
1518 | |
| 1516 | // create io watchers for each fd and a timer before blocking |
1519 | // create io watchers for each fd and a timer before blocking |
| 1517 | static void |
1520 | static void |
| 1518 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1521 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
| … | |
… | |
| 1524 | |
1527 | |
| 1525 | /* the callback is illegal, but won't be called as we stop during check */ |
1528 | /* the callback is illegal, but won't be called as we stop during check */ |
| 1526 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1529 | ev_timer_init (&tw, 0, timeout * 1e-3); |
| 1527 | ev_timer_start (loop, &tw); |
1530 | ev_timer_start (loop, &tw); |
| 1528 | |
1531 | |
| 1529 | // create on ev_io per pollfd |
1532 | // create one ev_io per pollfd |
| 1530 | for (int i = 0; i < nfd; ++i) |
1533 | for (int i = 0; i < nfd; ++i) |
| 1531 | { |
1534 | { |
| 1532 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1535 | ev_io_init (iow + i, io_cb, fds [i].fd, |
| 1533 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1536 | ((fds [i].events & POLLIN ? EV_READ : 0) |
| 1534 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1537 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
| 1535 | |
1538 | |
| 1536 | fds [i].revents = 0; |
1539 | fds [i].revents = 0; |
| 1537 | iow [i].data = fds + i; |
|
|
| 1538 | ev_io_start (loop, iow + i); |
1540 | ev_io_start (loop, iow + i); |
| 1539 | } |
1541 | } |
| 1540 | } |
1542 | } |
| 1541 | |
1543 | |
| 1542 | // stop all watchers after blocking |
1544 | // stop all watchers after blocking |
| … | |
… | |
| 1544 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1546 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
| 1545 | { |
1547 | { |
| 1546 | ev_timer_stop (loop, &tw); |
1548 | ev_timer_stop (loop, &tw); |
| 1547 | |
1549 | |
| 1548 | for (int i = 0; i < nfd; ++i) |
1550 | for (int i = 0; i < nfd; ++i) |
|
|
1551 | { |
|
|
1552 | // set the relevant poll flags |
|
|
1553 | // could also call adns_processreadable etc. here |
|
|
1554 | struct pollfd *fd = fds + i; |
|
|
1555 | int revents = ev_clear_pending (iow + i); |
|
|
1556 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1557 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1558 | |
|
|
1559 | // now stop the watcher |
| 1549 | ev_io_stop (loop, iow + i); |
1560 | ev_io_stop (loop, iow + i); |
|
|
1561 | } |
| 1550 | |
1562 | |
| 1551 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1563 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1564 | } |
|
|
1565 | |
|
|
1566 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1567 | in the prepare watcher and would dispose of the check watcher. |
|
|
1568 | |
|
|
1569 | Method 3: If the module to be embedded supports explicit event |
|
|
1570 | notification (adns does), you can also make use of the actual watcher |
|
|
1571 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1572 | |
|
|
1573 | static void |
|
|
1574 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1575 | { |
|
|
1576 | adns_state ads = (adns_state)w->data; |
|
|
1577 | update_now (EV_A); |
|
|
1578 | |
|
|
1579 | adns_processtimeouts (ads, &tv_now); |
|
|
1580 | } |
|
|
1581 | |
|
|
1582 | static void |
|
|
1583 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1584 | { |
|
|
1585 | adns_state ads = (adns_state)w->data; |
|
|
1586 | update_now (EV_A); |
|
|
1587 | |
|
|
1588 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1589 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1590 | } |
|
|
1591 | |
|
|
1592 | // do not ever call adns_afterpoll |
|
|
1593 | |
|
|
1594 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1595 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1596 | their poll function. The drawback with this solution is that the main |
|
|
1597 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1598 | this. |
|
|
1599 | |
|
|
1600 | static gint |
|
|
1601 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1602 | { |
|
|
1603 | int got_events = 0; |
|
|
1604 | |
|
|
1605 | for (n = 0; n < nfds; ++n) |
|
|
1606 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1607 | |
|
|
1608 | if (timeout >= 0) |
|
|
1609 | // create/start timer |
|
|
1610 | |
|
|
1611 | // poll |
|
|
1612 | ev_loop (EV_A_ 0); |
|
|
1613 | |
|
|
1614 | // stop timer again |
|
|
1615 | if (timeout >= 0) |
|
|
1616 | ev_timer_stop (EV_A_ &to); |
|
|
1617 | |
|
|
1618 | // stop io watchers again - their callbacks should have set |
|
|
1619 | for (n = 0; n < nfds; ++n) |
|
|
1620 | ev_io_stop (EV_A_ iow [n]); |
|
|
1621 | |
|
|
1622 | return got_events; |
| 1552 | } |
1623 | } |
| 1553 | |
1624 | |
| 1554 | |
1625 | |
| 1555 | =head2 C<ev_embed> - when one backend isn't enough... |
1626 | =head2 C<ev_embed> - when one backend isn't enough... |
| 1556 | |
1627 | |
