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Comparing libev/ev.3 (file contents):
Revision 1.42 by root, Fri Dec 7 20:19:16 2007 UTC vs.
Revision 1.45 by root, Sat Dec 8 22:11:14 2007 UTC

… …
127.\} 127.\}
128.rm #[ #] #H #V #F C 128.rm #[ #] #H #V #F C
129.\" ======================================================================== 129.\" ========================================================================
130.\" 130.\"
131.IX Title ""<STANDARD INPUT>" 1" 131.IX Title ""<STANDARD INPUT>" 1"
132.TH "<STANDARD INPUT>" 1 "2007-12-07" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH "<STANDARD INPUT>" 1 "2007-12-08" "perl v5.8.8" "User Contributed Perl Documentation"
133.SH "NAME" 133.SH "NAME"
134libev \- a high performance full\-featured event loop written in C 134libev \- a high performance full\-featured event loop written in C
135.SH "SYNOPSIS" 135.SH "SYNOPSIS"
136.IX Header "SYNOPSIS" 136.IX Header "SYNOPSIS"
137.Vb 1 137.Vb 1
… …
634libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is 634libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is
635usually a better approach for this kind of thing. 635usually a better approach for this kind of thing.
636.Sp 636.Sp
637Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: 637Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does:
638.Sp 638.Sp
639.Vb 18 639.Vb 19
640\& - Before the first iteration, call any pending watchers.
640\& * If there are no active watchers (reference count is zero), return. 641\& * If there are no active watchers (reference count is zero), return.
641\& - Queue prepare watchers and then call all outstanding watchers. 642\& - Queue all prepare watchers and then call all outstanding watchers.
642\& - If we have been forked, recreate the kernel state. 643\& - If we have been forked, recreate the kernel state.
643\& - Update the kernel state with all outstanding changes. 644\& - Update the kernel state with all outstanding changes.
644\& - Update the "event loop time". 645\& - Update the "event loop time".
645\& - Calculate for how long to block. 646\& - Calculate for how long to block.
646\& - Block the process, waiting for any events. 647\& - Block the process, waiting for any events.
… …
889.IP "bool ev_is_pending (ev_TYPE *watcher)" 4 890.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
890.IX Item "bool ev_is_pending (ev_TYPE *watcher)" 891.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
891Returns a true value iff the watcher is pending, (i.e. it has outstanding 892Returns a true value iff the watcher is pending, (i.e. it has outstanding
892events but its callback has not yet been invoked). As long as a watcher 893events but its callback has not yet been invoked). As long as a watcher
893is pending (but not active) you must not call an init function on it (but 894is pending (but not active) you must not call an init function on it (but
894\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to 895\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must
895libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). 896make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR
897it).
896.IP "callback ev_cb (ev_TYPE *watcher)" 4 898.IP "callback ev_cb (ev_TYPE *watcher)" 4
897.IX Item "callback ev_cb (ev_TYPE *watcher)" 899.IX Item "callback ev_cb (ev_TYPE *watcher)"
898Returns the callback currently set on the watcher. 900Returns the callback currently set on the watcher.
899.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 901.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
900.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 902.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
… …
918watchers on the same event and make sure one is called first. 920watchers on the same event and make sure one is called first.
919.Sp 921.Sp
920If you need to suppress invocation when higher priority events are pending 922If you need to suppress invocation when higher priority events are pending
921you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. 923you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality.
922.Sp 924.Sp
925You \fImust not\fR change the priority of a watcher as long as it is active or
926pending.
927.Sp
923The default priority used by watchers when no priority has been set is 928The default priority used by watchers when no priority has been set is
924always \f(CW0\fR, which is supposed to not be too high and not be too low :). 929always \f(CW0\fR, which is supposed to not be too high and not be too low :).
925.Sp 930.Sp
926Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is 931Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is
927fine, as long as you do not mind that the priority value you query might 932fine, as long as you do not mind that the priority value you query might
928or might not have been adjusted to be within valid range. 933or might not have been adjusted to be within valid range.
934.IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4
935.IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)"
936Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither
937\&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback
938can deal with that fact.
939.IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4
940.IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)"
941If the watcher is pending, this function returns clears its pending status
942and returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the
943watcher isn't pending it does nothing and returns \f(CW0\fR.
929.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 944.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
930.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 945.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
931Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change 946Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change
932and read at any time, libev will completely ignore it. This can be used 947and read at any time, libev will completely ignore it. This can be used
933to associate arbitrary data with your watcher. If you need more data and 948to associate arbitrary data with your watcher. If you need more data and
… …
1620are ready to run (it's actually more complicated: it only runs coroutines 1635are ready to run (it's actually more complicated: it only runs coroutines
1621with priority higher than or equal to the event loop and one coroutine 1636with priority higher than or equal to the event loop and one coroutine
1622of lower priority, but only once, using idle watchers to keep the event 1637of lower priority, but only once, using idle watchers to keep the event
1623loop from blocking if lower-priority coroutines are active, thus mapping 1638loop from blocking if lower-priority coroutines are active, thus mapping
1624low-priority coroutines to idle/background tasks). 1639low-priority coroutines to idle/background tasks).
1640.PP
1641It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR)
1642priority, to ensure that they are being run before any other watchers
1643after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers,
1644too) should not activate (\*(L"feed\*(R") events into libev. While libev fully
1645supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers did
1646their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other event
1647loops those other event loops might be in an unusable state until their
1648\&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with
1649others).
1625.IP "ev_prepare_init (ev_prepare *, callback)" 4 1650.IP "ev_prepare_init (ev_prepare *, callback)" 4
1626.IX Item "ev_prepare_init (ev_prepare *, callback)" 1651.IX Item "ev_prepare_init (ev_prepare *, callback)"
1627.PD 0 1652.PD 0
1628.IP "ev_check_init (ev_check *, callback)" 4 1653.IP "ev_check_init (ev_check *, callback)" 4
1629.IX Item "ev_check_init (ev_check *, callback)" 1654.IX Item "ev_check_init (ev_check *, callback)"
1630.PD 1655.PD
1631Initialises and configures the prepare or check watcher \- they have no 1656Initialises and configures the prepare or check watcher \- they have no
1632parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR 1657parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR
1633macros, but using them is utterly, utterly and completely pointless. 1658macros, but using them is utterly, utterly and completely pointless.
1634.PP 1659.PP
1635Example: To include a library such as adns, you would add \s-1IO\s0 watchers 1660There are a number of principal ways to embed other event loops or modules
1636and a timeout watcher in a prepare handler, as required by libadns, and 1661into libev. Here are some ideas on how to include libadns into libev
1662(there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could
1663use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR
1664embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0
1665into the Glib event loop).
1666.PP
1667Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler,
1637in a check watcher, destroy them and call into libadns. What follows is 1668and in a check watcher, destroy them and call into libadns. What follows
1638pseudo-code only of course: 1669is pseudo-code only of course. This requires you to either use a low
1670priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as
1671the callbacks for the IO/timeout watchers might not have been called yet.
1639.PP 1672.PP
1640.Vb 2 1673.Vb 2
1641\& static ev_io iow [nfd]; 1674\& static ev_io iow [nfd];
1642\& static ev_timer tw; 1675\& static ev_timer tw;
1643.Ve 1676.Ve
1644.PP 1677.PP
1645.Vb 9 1678.Vb 4
1646\& static void 1679\& static void
1647\& io_cb (ev_loop *loop, ev_io *w, int revents) 1680\& io_cb (ev_loop *loop, ev_io *w, int revents)
1648\& { 1681\& {
1649\& // set the relevant poll flags
1650\& // could also call adns_processreadable etc. here
1651\& struct pollfd *fd = (struct pollfd *)w->data;
1652\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1653\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1654\& } 1682\& }
1655.Ve 1683.Ve
1656.PP 1684.PP
1657.Vb 8 1685.Vb 8
1658\& // create io watchers for each fd and a timer before blocking 1686\& // create io watchers for each fd and a timer before blocking
… …
1670\& ev_timer_init (&tw, 0, timeout * 1e-3); 1698\& ev_timer_init (&tw, 0, timeout * 1e-3);
1671\& ev_timer_start (loop, &tw); 1699\& ev_timer_start (loop, &tw);
1672.Ve 1700.Ve
1673.PP 1701.PP
1674.Vb 6 1702.Vb 6
1675\& // create on ev_io per pollfd 1703\& // create one ev_io per pollfd
1676\& for (int i = 0; i < nfd; ++i) 1704\& for (int i = 0; i < nfd; ++i)
1677\& { 1705\& {
1678\& ev_io_init (iow + i, io_cb, fds [i].fd, 1706\& ev_io_init (iow + i, io_cb, fds [i].fd,
1679\& ((fds [i].events & POLLIN ? EV_READ : 0) 1707\& ((fds [i].events & POLLIN ? EV_READ : 0)
1680\& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); 1708\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1681.Ve 1709.Ve
1682.PP 1710.PP
1683.Vb 5 1711.Vb 4
1684\& fds [i].revents = 0; 1712\& fds [i].revents = 0;
1685\& iow [i].data = fds + i;
1686\& ev_io_start (loop, iow + i); 1713\& ev_io_start (loop, iow + i);
1687\& } 1714\& }
1688\& } 1715\& }
1689.Ve 1716.Ve
1690.PP 1717.PP
… …
1694\& adns_check_cb (ev_loop *loop, ev_check *w, int revents) 1721\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1695\& { 1722\& {
1696\& ev_timer_stop (loop, &tw); 1723\& ev_timer_stop (loop, &tw);
1697.Ve 1724.Ve
1698.PP 1725.PP
1699.Vb 2 1726.Vb 8
1700\& for (int i = 0; i < nfd; ++i) 1727\& for (int i = 0; i < nfd; ++i)
1728\& {
1729\& // set the relevant poll flags
1730\& // could also call adns_processreadable etc. here
1731\& struct pollfd *fd = fds + i;
1732\& int revents = ev_clear_pending (iow + i);
1733\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1734\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1735.Ve
1736.PP
1737.Vb 3
1738\& // now stop the watcher
1701\& ev_io_stop (loop, iow + i); 1739\& ev_io_stop (loop, iow + i);
1740\& }
1702.Ve 1741.Ve
1703.PP 1742.PP
1704.Vb 2 1743.Vb 2
1705\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); 1744\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1745\& }
1746.Ve
1747.PP
1748Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR
1749in the prepare watcher and would dispose of the check watcher.
1750.PP
1751Method 3: If the module to be embedded supports explicit event
1752notification (adns does), you can also make use of the actual watcher
1753callbacks, and only destroy/create the watchers in the prepare watcher.
1754.PP
1755.Vb 5
1756\& static void
1757\& timer_cb (EV_P_ ev_timer *w, int revents)
1758\& {
1759\& adns_state ads = (adns_state)w->data;
1760\& update_now (EV_A);
1761.Ve
1762.PP
1763.Vb 2
1764\& adns_processtimeouts (ads, &tv_now);
1765\& }
1766.Ve
1767.PP
1768.Vb 5
1769\& static void
1770\& io_cb (EV_P_ ev_io *w, int revents)
1771\& {
1772\& adns_state ads = (adns_state)w->data;
1773\& update_now (EV_A);
1774.Ve
1775.PP
1776.Vb 3
1777\& if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1778\& if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1779\& }
1780.Ve
1781.PP
1782.Vb 1
1783\& // do not ever call adns_afterpoll
1784.Ve
1785.PP
1786Method 4: Do not use a prepare or check watcher because the module you
1787want to embed is too inflexible to support it. Instead, youc na override
1788their poll function. The drawback with this solution is that the main
1789loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does
1790this.
1791.PP
1792.Vb 4
1793\& static gint
1794\& event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1795\& {
1796\& int got_events = 0;
1797.Ve
1798.PP
1799.Vb 2
1800\& for (n = 0; n < nfds; ++n)
1801\& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1802.Ve
1803.PP
1804.Vb 2
1805\& if (timeout >= 0)
1806\& // create/start timer
1807.Ve
1808.PP
1809.Vb 2
1810\& // poll
1811\& ev_loop (EV_A_ 0);
1812.Ve
1813.PP
1814.Vb 3
1815\& // stop timer again
1816\& if (timeout >= 0)
1817\& ev_timer_stop (EV_A_ &to);
1818.Ve
1819.PP
1820.Vb 3
1821\& // stop io watchers again - their callbacks should have set
1822\& for (n = 0; n < nfds; ++n)
1823\& ev_io_stop (EV_A_ iow [n]);
1824.Ve
1825.PP
1826.Vb 2
1827\& return got_events;
1706\& } 1828\& }
1707.Ve 1829.Ve
1708.ie n .Sh """ev_embed"" \- when one backend isn't enough..." 1830.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1709.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." 1831.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
1710.IX Subsection "ev_embed - when one backend isn't enough..." 1832.IX Subsection "ev_embed - when one backend isn't enough..."
… …
1978.Vb 3 2100.Vb 3
1979\& myclass obj; 2101\& myclass obj;
1980\& ev::io iow; 2102\& ev::io iow;
1981\& iow.set <myclass, &myclass::io_cb> (&obj); 2103\& iow.set <myclass, &myclass::io_cb> (&obj);
1982.Ve 2104.Ve
1983.IP "w\->set (void (*function)(watcher &w, int), void *data = 0)" 4 2105.IP "w\->set<function> (void *data = 0)" 4
1984.IX Item "w->set (void (*function)(watcher &w, int), void *data = 0)" 2106.IX Item "w->set<function> (void *data = 0)"
1985Also sets a callback, but uses a static method or plain function as 2107Also sets a callback, but uses a static method or plain function as
1986callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's 2108callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's
1987\&\f(CW\*(C`data\*(C'\fR member and is free for you to use. 2109\&\f(CW\*(C`data\*(C'\fR member and is free for you to use.
1988.Sp 2110.Sp
2111The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR.
2112.Sp
1989See the method\-\f(CW\*(C`set\*(C'\fR above for more details. 2113See the method\-\f(CW\*(C`set\*(C'\fR above for more details.
2114.Sp
2115Example:
2116.Sp
2117.Vb 2
2118\& static void io_cb (ev::io &w, int revents) { }
2119\& iow.set <io_cb> ();
2120.Ve
1990.IP "w\->set (struct ev_loop *)" 4 2121.IP "w\->set (struct ev_loop *)" 4
1991.IX Item "w->set (struct ev_loop *)" 2122.IX Item "w->set (struct ev_loop *)"
1992Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only 2123Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
1993do this when the watcher is inactive (and not pending either). 2124do this when the watcher is inactive (and not pending either).
1994.IP "w\->set ([args])" 4 2125.IP "w\->set ([args])" 4

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