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Revision 1.41 by root, Fri Dec 7 20:13:09 2007 UTC vs.
Revision 1.46 by root, Sun Dec 9 19:42:57 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 "2007-12-09" "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
… …
1220but on wallclock time (absolute time). You can tell a periodic watcher 1235but on wallclock time (absolute time). You can tell a periodic watcher
1221to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a 1236to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a
1222periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () 1237periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now ()
1223+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will 1238+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will
1224take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger 1239take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger
1225roughly 10 seconds later and of course not if you reset your system time 1240roughly 10 seconds later).
1226again).
1227.PP 1241.PP
1228They can also be used to implement vastly more complex timers, such as 1242They can also be used to implement vastly more complex timers, such as
1229triggering an event on eahc midnight, local time. 1243triggering an event on each midnight, local time or other, complicated,
1244rules.
1230.PP 1245.PP
1231As with timers, the callback is guarenteed to be invoked only when the 1246As with timers, the callback is guarenteed to be invoked only when the
1232time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready 1247time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready
1233during the same loop iteration then order of execution is undefined. 1248during the same loop iteration then order of execution is undefined.
1234.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 1249.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4
… …
1238.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 1253.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)"
1239.PD 1254.PD
1240Lots of arguments, lets sort it out... There are basically three modes of 1255Lots of arguments, lets sort it out... There are basically three modes of
1241operation, and we will explain them from simplest to complex: 1256operation, and we will explain them from simplest to complex:
1242.RS 4 1257.RS 4
1243.IP "* absolute timer (interval = reschedule_cb = 0)" 4 1258.IP "* absolute timer (at = time, interval = reschedule_cb = 0)" 4
1244.IX Item "absolute timer (interval = reschedule_cb = 0)" 1259.IX Item "absolute timer (at = time, interval = reschedule_cb = 0)"
1245In this configuration the watcher triggers an event at the wallclock time 1260In this configuration the watcher triggers an event at the wallclock time
1246\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, 1261\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs,
1247that is, if it is to be run at January 1st 2011 then it will run when the 1262that is, if it is to be run at January 1st 2011 then it will run when the
1248system time reaches or surpasses this time. 1263system time reaches or surpasses this time.
1249.IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4 1264.IP "* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" 4
1250.IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)" 1265.IX Item "non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)"
1251In this mode the watcher will always be scheduled to time out at the next 1266In this mode the watcher will always be scheduled to time out at the next
1252\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless 1267\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative)
1253of any time jumps. 1268and then repeat, regardless of any time jumps.
1254.Sp 1269.Sp
1255This can be used to create timers that do not drift with respect to system 1270This can be used to create timers that do not drift with respect to system
1256time: 1271time:
1257.Sp 1272.Sp
1258.Vb 1 1273.Vb 1
… …
1265by 3600. 1280by 3600.
1266.Sp 1281.Sp
1267Another way to think about it (for the mathematically inclined) is that 1282Another way to think about it (for the mathematically inclined) is that
1268\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible 1283\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible
1269time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. 1284time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps.
1285.Sp
1286For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near
1287\&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for
1288this value.
1270.IP "* manual reschedule mode (reschedule_cb = callback)" 4 1289.IP "* manual reschedule mode (at and interval ignored, reschedule_cb = callback)" 4
1271.IX Item "manual reschedule mode (reschedule_cb = callback)" 1290.IX Item "manual reschedule mode (at and interval ignored, reschedule_cb = callback)"
1272In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being 1291In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being
1273ignored. Instead, each time the periodic watcher gets scheduled, the 1292ignored. Instead, each time the periodic watcher gets scheduled, the
1274reschedule callback will be called with the watcher as first, and the 1293reschedule callback will be called with the watcher as first, and the
1275current time as second argument. 1294current time as second argument.
1276.Sp 1295.Sp
1277\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, 1296\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher,
1278ever, or make any event loop modifications\fR. If you need to stop it, 1297ever, or make any event loop modifications\fR. If you need to stop it,
1279return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by 1298return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by
1280starting a prepare watcher). 1299starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal).
1281.Sp 1300.Sp
1282Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, 1301Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
1283ev_tstamp now)\*(C'\fR, e.g.: 1302ev_tstamp now)\*(C'\fR, e.g.:
1284.Sp 1303.Sp
1285.Vb 4 1304.Vb 4
… …
1309.IX Item "ev_periodic_again (loop, ev_periodic *)" 1328.IX Item "ev_periodic_again (loop, ev_periodic *)"
1310Simply stops and restarts the periodic watcher again. This is only useful 1329Simply stops and restarts the periodic watcher again. This is only useful
1311when you changed some parameters or the reschedule callback would return 1330when you changed some parameters or the reschedule callback would return
1312a different time than the last time it was called (e.g. in a crond like 1331a different time than the last time it was called (e.g. in a crond like
1313program when the crontabs have changed). 1332program when the crontabs have changed).
1333.IP "ev_tstamp offset [read\-write]" 4
1334.IX Item "ev_tstamp offset [read-write]"
1335When repeating, this contains the offset value, otherwise this is the
1336absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR).
1337.Sp
1338Can be modified any time, but changes only take effect when the periodic
1339timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1314.IP "ev_tstamp interval [read\-write]" 4 1340.IP "ev_tstamp interval [read\-write]" 4
1315.IX Item "ev_tstamp interval [read-write]" 1341.IX Item "ev_tstamp interval [read-write]"
1316The current interval value. Can be modified any time, but changes only 1342The current interval value. Can be modified any time, but changes only
1317take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being 1343take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being
1318called. 1344called.
… …
1620are ready to run (it's actually more complicated: it only runs coroutines 1646are 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 1647with 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 1648of lower priority, but only once, using idle watchers to keep the event
1623loop from blocking if lower-priority coroutines are active, thus mapping 1649loop from blocking if lower-priority coroutines are active, thus mapping
1624low-priority coroutines to idle/background tasks). 1650low-priority coroutines to idle/background tasks).
1651.PP
1652It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR)
1653priority, to ensure that they are being run before any other watchers
1654after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers,
1655too) should not activate (\*(L"feed\*(R") events into libev. While libev fully
1656supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers did
1657their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other event
1658loops those other event loops might be in an unusable state until their
1659\&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with
1660others).
1625.IP "ev_prepare_init (ev_prepare *, callback)" 4 1661.IP "ev_prepare_init (ev_prepare *, callback)" 4
1626.IX Item "ev_prepare_init (ev_prepare *, callback)" 1662.IX Item "ev_prepare_init (ev_prepare *, callback)"
1627.PD 0 1663.PD 0
1628.IP "ev_check_init (ev_check *, callback)" 4 1664.IP "ev_check_init (ev_check *, callback)" 4
1629.IX Item "ev_check_init (ev_check *, callback)" 1665.IX Item "ev_check_init (ev_check *, callback)"
1630.PD 1666.PD
1631Initialises and configures the prepare or check watcher \- they have no 1667Initialises 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 1668parameters 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. 1669macros, but using them is utterly, utterly and completely pointless.
1634.PP 1670.PP
1635Example: To include a library such as adns, you would add \s-1IO\s0 watchers 1671There 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 1672into libev. Here are some ideas on how to include libadns into libev
1673(there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could
1674use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR
1675embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0
1676into the Glib event loop).
1677.PP
1678Method 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 1679and in a check watcher, destroy them and call into libadns. What follows
1638pseudo-code only of course: 1680is pseudo-code only of course. This requires you to either use a low
1681priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as
1682the callbacks for the IO/timeout watchers might not have been called yet.
1639.PP 1683.PP
1640.Vb 2 1684.Vb 2
1641\& static ev_io iow [nfd]; 1685\& static ev_io iow [nfd];
1642\& static ev_timer tw; 1686\& static ev_timer tw;
1643.Ve 1687.Ve
1644.PP 1688.PP
1645.Vb 9 1689.Vb 4
1646\& static void 1690\& static void
1647\& io_cb (ev_loop *loop, ev_io *w, int revents) 1691\& io_cb (ev_loop *loop, ev_io *w, int revents)
1648\& { 1692\& {
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\& } 1693\& }
1655.Ve 1694.Ve
1656.PP 1695.PP
1657.Vb 8 1696.Vb 8
1658\& // create io watchers for each fd and a timer before blocking 1697\& // create io watchers for each fd and a timer before blocking
… …
1670\& ev_timer_init (&tw, 0, timeout * 1e-3); 1709\& ev_timer_init (&tw, 0, timeout * 1e-3);
1671\& ev_timer_start (loop, &tw); 1710\& ev_timer_start (loop, &tw);
1672.Ve 1711.Ve
1673.PP 1712.PP
1674.Vb 6 1713.Vb 6
1675\& // create on ev_io per pollfd 1714\& // create one ev_io per pollfd
1676\& for (int i = 0; i < nfd; ++i) 1715\& for (int i = 0; i < nfd; ++i)
1677\& { 1716\& {
1678\& ev_io_init (iow + i, io_cb, fds [i].fd, 1717\& ev_io_init (iow + i, io_cb, fds [i].fd,
1679\& ((fds [i].events & POLLIN ? EV_READ : 0) 1718\& ((fds [i].events & POLLIN ? EV_READ : 0)
1680\& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); 1719\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1681.Ve 1720.Ve
1682.PP 1721.PP
1683.Vb 5 1722.Vb 4
1684\& fds [i].revents = 0; 1723\& fds [i].revents = 0;
1685\& iow [i].data = fds + i;
1686\& ev_io_start (loop, iow + i); 1724\& ev_io_start (loop, iow + i);
1687\& } 1725\& }
1688\& } 1726\& }
1689.Ve 1727.Ve
1690.PP 1728.PP
… …
1694\& adns_check_cb (ev_loop *loop, ev_check *w, int revents) 1732\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1695\& { 1733\& {
1696\& ev_timer_stop (loop, &tw); 1734\& ev_timer_stop (loop, &tw);
1697.Ve 1735.Ve
1698.PP 1736.PP
1699.Vb 2 1737.Vb 8
1700\& for (int i = 0; i < nfd; ++i) 1738\& for (int i = 0; i < nfd; ++i)
1739\& {
1740\& // set the relevant poll flags
1741\& // could also call adns_processreadable etc. here
1742\& struct pollfd *fd = fds + i;
1743\& int revents = ev_clear_pending (iow + i);
1744\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1745\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1746.Ve
1747.PP
1748.Vb 3
1749\& // now stop the watcher
1701\& ev_io_stop (loop, iow + i); 1750\& ev_io_stop (loop, iow + i);
1751\& }
1702.Ve 1752.Ve
1703.PP 1753.PP
1704.Vb 2 1754.Vb 2
1705\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); 1755\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1756\& }
1757.Ve
1758.PP
1759Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR
1760in the prepare watcher and would dispose of the check watcher.
1761.PP
1762Method 3: If the module to be embedded supports explicit event
1763notification (adns does), you can also make use of the actual watcher
1764callbacks, and only destroy/create the watchers in the prepare watcher.
1765.PP
1766.Vb 5
1767\& static void
1768\& timer_cb (EV_P_ ev_timer *w, int revents)
1769\& {
1770\& adns_state ads = (adns_state)w->data;
1771\& update_now (EV_A);
1772.Ve
1773.PP
1774.Vb 2
1775\& adns_processtimeouts (ads, &tv_now);
1776\& }
1777.Ve
1778.PP
1779.Vb 5
1780\& static void
1781\& io_cb (EV_P_ ev_io *w, int revents)
1782\& {
1783\& adns_state ads = (adns_state)w->data;
1784\& update_now (EV_A);
1785.Ve
1786.PP
1787.Vb 3
1788\& if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1789\& if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1790\& }
1791.Ve
1792.PP
1793.Vb 1
1794\& // do not ever call adns_afterpoll
1795.Ve
1796.PP
1797Method 4: Do not use a prepare or check watcher because the module you
1798want to embed is too inflexible to support it. Instead, youc na override
1799their poll function. The drawback with this solution is that the main
1800loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does
1801this.
1802.PP
1803.Vb 4
1804\& static gint
1805\& event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1806\& {
1807\& int got_events = 0;
1808.Ve
1809.PP
1810.Vb 2
1811\& for (n = 0; n < nfds; ++n)
1812\& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1813.Ve
1814.PP
1815.Vb 2
1816\& if (timeout >= 0)
1817\& // create/start timer
1818.Ve
1819.PP
1820.Vb 2
1821\& // poll
1822\& ev_loop (EV_A_ 0);
1823.Ve
1824.PP
1825.Vb 3
1826\& // stop timer again
1827\& if (timeout >= 0)
1828\& ev_timer_stop (EV_A_ &to);
1829.Ve
1830.PP
1831.Vb 3
1832\& // stop io watchers again - their callbacks should have set
1833\& for (n = 0; n < nfds; ++n)
1834\& ev_io_stop (EV_A_ iow [n]);
1835.Ve
1836.PP
1837.Vb 2
1838\& return got_events;
1706\& } 1839\& }
1707.Ve 1840.Ve
1708.ie n .Sh """ev_embed"" \- when one backend isn't enough..." 1841.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1709.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." 1842.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
1710.IX Subsection "ev_embed - when one backend isn't enough..." 1843.IX Subsection "ev_embed - when one backend isn't enough..."
… …
1899This automatically includes \fIev.h\fR and puts all of its definitions (many 2032This automatically includes \fIev.h\fR and puts all of its definitions (many
1900of them macros) into the global namespace. All \*(C+ specific things are 2033of them macros) into the global namespace. All \*(C+ specific things are
1901put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding 2034put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding
1902options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. 2035options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
1903.PP 2036.PP
1904Care has been taken to keep the overhead low. The only data member added 2037Care has been taken to keep the overhead low. The only data member the \*(C+
1905to the C\-style watchers is the event loop the watcher is associated with 2038classes add (compared to plain C\-style watchers) is the event loop pointer
1906(or no additional members at all if you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when 2039that the watcher is associated with (or no additional members at all if
1907embedding libev). 2040you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev).
1908.PP 2041.PP
1909Currently, functions and static and non-static member functions can be 2042Currently, functions, and static and non-static member functions can be
1910used as callbacks. Other types should be easy to add as long as they only 2043used as callbacks. Other types should be easy to add as long as they only
1911need one additional pointer for context. If you need support for other 2044need one additional pointer for context. If you need support for other
1912types of functors please contact the author (preferably after implementing 2045types of functors please contact the author (preferably after implementing
1913it). 2046it).
1914.PP 2047.PP
… …
1978.Vb 3 2111.Vb 3
1979\& myclass obj; 2112\& myclass obj;
1980\& ev::io iow; 2113\& ev::io iow;
1981\& iow.set <myclass, &myclass::io_cb> (&obj); 2114\& iow.set <myclass, &myclass::io_cb> (&obj);
1982.Ve 2115.Ve
1983.IP "w\->set (void (*function)(watcher &w, int), void *data = 0)" 4 2116.IP "w\->set<function> (void *data = 0)" 4
1984.IX Item "w->set (void (*function)(watcher &w, int), void *data = 0)" 2117.IX Item "w->set<function> (void *data = 0)"
1985Also sets a callback, but uses a static method or plain function as 2118Also 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 2119callback. 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. 2120\&\f(CW\*(C`data\*(C'\fR member and is free for you to use.
1988.Sp 2121.Sp
2122The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR.
2123.Sp
1989See the method\-\f(CW\*(C`set\*(C'\fR above for more details. 2124See the method\-\f(CW\*(C`set\*(C'\fR above for more details.
2125.Sp
2126Example:
2127.Sp
2128.Vb 2
2129\& static void io_cb (ev::io &w, int revents) { }
2130\& iow.set <io_cb> ();
2131.Ve
1990.IP "w\->set (struct ev_loop *)" 4 2132.IP "w\->set (struct ev_loop *)" 4
1991.IX Item "w->set (struct ev_loop *)" 2133.IX Item "w->set (struct ev_loop *)"
1992Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only 2134Associates 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). 2135do this when the watcher is inactive (and not pending either).
1994.IP "w\->set ([args])" 4 2136.IP "w\->set ([args])" 4

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