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Revision 1.33 by root, Wed Nov 28 18:29:29 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 "2007-11-28" "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
… …
196\& return 0; 196\& return 0;
197\& } 197\& }
198.Ve 198.Ve
199.SH "DESCRIPTION" 199.SH "DESCRIPTION"
200.IX Header "DESCRIPTION" 200.IX Header "DESCRIPTION"
201The newest version of this document is also available as a html-formatted
202web page you might find easier to navigate when reading it for the first
203time: <http://cvs.schmorp.de/libev/ev.html>.
204.PP
201Libev is an event loop: you register interest in certain events (such as a 205Libev is an event loop: you register interest in certain events (such as a
202file descriptor being readable or a timeout occuring), and it will manage 206file descriptor being readable or a timeout occuring), and it will manage
203these event sources and provide your program with events. 207these event sources and provide your program with events.
204.PP 208.PP
205To do this, it must take more or less complete control over your process 209To do this, it must take more or less complete control over your process
… …
411or setgid) then libev will \fInot\fR look at the environment variable 415or setgid) then libev will \fInot\fR look at the environment variable
412\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will 416\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will
413override the flags completely if it is found in the environment. This is 417override the flags completely if it is found in the environment. This is
414useful to try out specific backends to test their performance, or to work 418useful to try out specific backends to test their performance, or to work
415around bugs. 419around bugs.
420.ie n .IP """EVFLAG_FORKCHECK""" 4
421.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4
422.IX Item "EVFLAG_FORKCHECK"
423Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after
424a fork, you can also make libev check for a fork in each iteration by
425enabling this flag.
426.Sp
427This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop,
428and thus this might slow down your event loop if you do a lot of loop
429iterations and little real work, but is usually not noticeable (on my
430Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence
431without a syscall and thus \fIvery\fR fast, but my Linux system also has
432\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster).
433.Sp
434The big advantage of this flag is that you can forget about fork (and
435forget about forgetting to tell libev about forking) when you use this
436flag.
437.Sp
438This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR
439environment variable.
416.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 440.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
417.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 441.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
418.IX Item "EVBACKEND_SELECT (value 1, portable select backend)" 442.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
419This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 443This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as
420libev tries to roll its own fd_set with no limits on the number of fds, 444libev tries to roll its own fd_set with no limits on the number of fds,
… …
561.IP "ev_loop_fork (loop)" 4 585.IP "ev_loop_fork (loop)" 4
562.IX Item "ev_loop_fork (loop)" 586.IX Item "ev_loop_fork (loop)"
563Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by 587Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by
564\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop 588\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop
565after fork, and how you do this is entirely your own problem. 589after fork, and how you do this is entirely your own problem.
590.IP "unsigned int ev_loop_count (loop)" 4
591.IX Item "unsigned int ev_loop_count (loop)"
592Returns the count of loop iterations for the loop, which is identical to
593the number of times libev did poll for new events. It starts at \f(CW0\fR and
594happily wraps around with enough iterations.
595.Sp
596This value can sometimes be useful as a generation counter of sorts (it
597\&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with
598\&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls.
566.IP "unsigned int ev_backend (loop)" 4 599.IP "unsigned int ev_backend (loop)" 4
567.IX Item "unsigned int ev_backend (loop)" 600.IX Item "unsigned int ev_backend (loop)"
568Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in 601Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
569use. 602use.
570.IP "ev_tstamp ev_now (loop)" 4 603.IP "ev_tstamp ev_now (loop)" 4
… …
601libev 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
602usually a better approach for this kind of thing. 635usually a better approach for this kind of thing.
603.Sp 636.Sp
604Here 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:
605.Sp 638.Sp
606.Vb 18 639.Vb 19
640\& - Before the first iteration, call any pending watchers.
607\& * If there are no active watchers (reference count is zero), return. 641\& * If there are no active watchers (reference count is zero), return.
608\& - Queue prepare watchers and then call all outstanding watchers. 642\& - Queue all prepare watchers and then call all outstanding watchers.
609\& - If we have been forked, recreate the kernel state. 643\& - If we have been forked, recreate the kernel state.
610\& - Update the kernel state with all outstanding changes. 644\& - Update the kernel state with all outstanding changes.
611\& - Update the "event loop time". 645\& - Update the "event loop time".
612\& - Calculate for how long to block. 646\& - Calculate for how long to block.
613\& - Block the process, waiting for any events. 647\& - Block the process, waiting for any events.
… …
856.IP "bool ev_is_pending (ev_TYPE *watcher)" 4 890.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
857.IX Item "bool ev_is_pending (ev_TYPE *watcher)" 891.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
858Returns 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
859events 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
860is 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
861\&\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
862libev (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).
863.IP "callback ev_cb (ev_TYPE *watcher)" 4 898.IP "callback ev_cb (ev_TYPE *watcher)" 4
864.IX Item "callback ev_cb (ev_TYPE *watcher)" 899.IX Item "callback ev_cb (ev_TYPE *watcher)"
865Returns the callback currently set on the watcher. 900Returns the callback currently set on the watcher.
866.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 901.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
867.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 902.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
868Change the callback. You can change the callback at virtually any time 903Change the callback. You can change the callback at virtually any time
869(modulo threads). 904(modulo threads).
905.IP "ev_set_priority (ev_TYPE *watcher, priority)" 4
906.IX Item "ev_set_priority (ev_TYPE *watcher, priority)"
907.PD 0
908.IP "int ev_priority (ev_TYPE *watcher)" 4
909.IX Item "int ev_priority (ev_TYPE *watcher)"
910.PD
911Set and query the priority of the watcher. The priority is a small
912integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR
913(default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked
914before watchers with lower priority, but priority will not keep watchers
915from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers).
916.Sp
917This means that priorities are \fIonly\fR used for ordering callback
918invocation after new events have been received. This is useful, for
919example, to reduce latency after idling, or more often, to bind two
920watchers on the same event and make sure one is called first.
921.Sp
922If you need to suppress invocation when higher priority events are pending
923you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality.
924.Sp
925You \fImust not\fR change the priority of a watcher as long as it is active or
926pending.
927.Sp
928The default priority used by watchers when no priority has been set is
929always \f(CW0\fR, which is supposed to not be too high and not be too low :).
930.Sp
931Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is
932fine, as long as you do not mind that the priority value you query might
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.
870.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"
871.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 945.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
872Each 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
873and 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
874to 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
… …
985it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning 1059it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning
986\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. 1060\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
987.PP 1061.PP
988If you cannot run the fd in non-blocking mode (for example you should not 1062If you cannot run the fd in non-blocking mode (for example you should not
989play around with an Xlib connection), then you have to seperately re-test 1063play around with an Xlib connection), then you have to seperately re-test
990wether a file descriptor is really ready with a known-to-be good interface 1064whether a file descriptor is really ready with a known-to-be good interface
991such as poll (fortunately in our Xlib example, Xlib already does this on 1065such as poll (fortunately in our Xlib example, Xlib already does this on
992its own, so its quite safe to use). 1066its own, so its quite safe to use).
993.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 1067.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
994.IX Item "ev_io_init (ev_io *, callback, int fd, int events)" 1068.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
995.PD 0 1069.PD 0
… …
1071.IP "ev_timer_again (loop)" 4 1145.IP "ev_timer_again (loop)" 4
1072.IX Item "ev_timer_again (loop)" 1146.IX Item "ev_timer_again (loop)"
1073This will act as if the timer timed out and restart it again if it is 1147This will act as if the timer timed out and restart it again if it is
1074repeating. The exact semantics are: 1148repeating. The exact semantics are:
1075.Sp 1149.Sp
1150If the timer is pending, its pending status is cleared.
1151.Sp
1076If the timer is started but nonrepeating, stop it. 1152If the timer is started but nonrepeating, stop it (as if it timed out).
1077.Sp 1153.Sp
1078If the timer is repeating, either start it if necessary (with the repeat 1154If the timer is repeating, either start it if necessary (with the
1079value), or reset the running timer to the repeat value. 1155\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value.
1080.Sp 1156.Sp
1081This sounds a bit complicated, but here is a useful and typical 1157This sounds a bit complicated, but here is a useful and typical
1082example: Imagine you have a tcp connection and you want a so-called 1158example: Imagine you have a tcp connection and you want a so-called idle
1083idle timeout, that is, you want to be called when there have been, 1159timeout, that is, you want to be called when there have been, say, 60
1084say, 60 seconds of inactivity on the socket. The easiest way to do 1160seconds of inactivity on the socket. The easiest way to do this is to
1085this is to configure an \f(CW\*(C`ev_timer\*(C'\fR with \f(CW\*(C`after\*(C'\fR=\f(CW\*(C`repeat\*(C'\fR=\f(CW60\fR and calling 1161configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value of \f(CW60\fR and then call
1086\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If 1162\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If
1087you go into an idle state where you do not expect data to travel on the 1163you go into an idle state where you do not expect data to travel on the
1088socket, you can stop the timer, and again will automatically restart it if 1164socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will
1089need be. 1165automatically restart it if need be.
1090.Sp 1166.Sp
1091You can also ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR altogether 1167That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR
1092and only ever use the \f(CW\*(C`repeat\*(C'\fR value: 1168altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR:
1093.Sp 1169.Sp
1094.Vb 8 1170.Vb 8
1095\& ev_timer_init (timer, callback, 0., 5.); 1171\& ev_timer_init (timer, callback, 0., 5.);
1096\& ev_timer_again (loop, timer); 1172\& ev_timer_again (loop, timer);
1097\& ... 1173\& ...
… …
1100\& ... 1176\& ...
1101\& timer->again = 10.; 1177\& timer->again = 10.;
1102\& ev_timer_again (loop, timer); 1178\& ev_timer_again (loop, timer);
1103.Ve 1179.Ve
1104.Sp 1180.Sp
1105This is more efficient then stopping/starting the timer eahc time you want 1181This is more slightly efficient then stopping/starting the timer each time
1106to modify its timeout value. 1182you want to modify its timeout value.
1107.IP "ev_tstamp repeat [read\-write]" 4 1183.IP "ev_tstamp repeat [read\-write]" 4
1108.IX Item "ev_tstamp repeat [read-write]" 1184.IX Item "ev_tstamp repeat [read-write]"
1109The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out 1185The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out
1110or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), 1186or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any),
1111which is also when any modifications are taken into account. 1187which is also when any modifications are taken into account.
… …
1477\& ev_stat_start (loop, &passwd); 1553\& ev_stat_start (loop, &passwd);
1478.Ve 1554.Ve
1479.ie n .Sh """ev_idle"" \- when you've got nothing better to do..." 1555.ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
1480.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." 1556.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
1481.IX Subsection "ev_idle - when you've got nothing better to do..." 1557.IX Subsection "ev_idle - when you've got nothing better to do..."
1482Idle watchers trigger events when there are no other events are pending 1558Idle watchers trigger events when no other events of the same or higher
1483(prepare, check and other idle watchers do not count). That is, as long 1559priority are pending (prepare, check and other idle watchers do not
1484as your process is busy handling sockets or timeouts (or even signals, 1560count).
1485imagine) it will not be triggered. But when your process is idle all idle 1561.PP
1486watchers are being called again and again, once per event loop iteration \- 1562That is, as long as your process is busy handling sockets or timeouts
1563(or even signals, imagine) of the same or higher priority it will not be
1564triggered. But when your process is idle (or only lower-priority watchers
1565are pending), the idle watchers are being called once per event loop
1487until stopped, that is, or your process receives more events and becomes 1566iteration \- until stopped, that is, or your process receives more events
1488busy. 1567and becomes busy again with higher priority stuff.
1489.PP 1568.PP
1490The most noteworthy effect is that as long as any idle watchers are 1569The most noteworthy effect is that as long as any idle watchers are
1491active, the process will not block when waiting for new events. 1570active, the process will not block when waiting for new events.
1492.PP 1571.PP
1493Apart from keeping your process non-blocking (which is a useful 1572Apart from keeping your process non-blocking (which is a useful
… …
1556are 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
1557with 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
1558of 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
1559loop from blocking if lower-priority coroutines are active, thus mapping 1638loop from blocking if lower-priority coroutines are active, thus mapping
1560low-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).
1561.IP "ev_prepare_init (ev_prepare *, callback)" 4 1650.IP "ev_prepare_init (ev_prepare *, callback)" 4
1562.IX Item "ev_prepare_init (ev_prepare *, callback)" 1651.IX Item "ev_prepare_init (ev_prepare *, callback)"
1563.PD 0 1652.PD 0
1564.IP "ev_check_init (ev_check *, callback)" 4 1653.IP "ev_check_init (ev_check *, callback)" 4
1565.IX Item "ev_check_init (ev_check *, callback)" 1654.IX Item "ev_check_init (ev_check *, callback)"
1566.PD 1655.PD
1567Initialises and configures the prepare or check watcher \- they have no 1656Initialises and configures the prepare or check watcher \- they have no
1568parameters 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
1569macros, but using them is utterly, utterly and completely pointless. 1658macros, but using them is utterly, utterly and completely pointless.
1570.PP 1659.PP
1571Example: 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
1572and 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,
1573in 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
1574pseudo-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.
1575.PP 1672.PP
1576.Vb 2 1673.Vb 2
1577\& static ev_io iow [nfd]; 1674\& static ev_io iow [nfd];
1578\& static ev_timer tw; 1675\& static ev_timer tw;
1579.Ve 1676.Ve
1580.PP 1677.PP
1581.Vb 9 1678.Vb 4
1582\& static void 1679\& static void
1583\& io_cb (ev_loop *loop, ev_io *w, int revents) 1680\& io_cb (ev_loop *loop, ev_io *w, int revents)
1584\& { 1681\& {
1585\& // set the relevant poll flags
1586\& // could also call adns_processreadable etc. here
1587\& struct pollfd *fd = (struct pollfd *)w->data;
1588\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1589\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1590\& } 1682\& }
1591.Ve 1683.Ve
1592.PP 1684.PP
1593.Vb 7 1685.Vb 8
1594\& // create io watchers for each fd and a timer before blocking 1686\& // create io watchers for each fd and a timer before blocking
1595\& static void 1687\& static void
1596\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) 1688\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1597\& { 1689\& {
1598\& int timeout = 3600000;truct pollfd fds [nfd]; 1690\& int timeout = 3600000;
1691\& struct pollfd fds [nfd];
1599\& // actual code will need to loop here and realloc etc. 1692\& // actual code will need to loop here and realloc etc.
1600\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); 1693\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1601.Ve 1694.Ve
1602.PP 1695.PP
1603.Vb 3 1696.Vb 3
… …
1605\& ev_timer_init (&tw, 0, timeout * 1e-3); 1698\& ev_timer_init (&tw, 0, timeout * 1e-3);
1606\& ev_timer_start (loop, &tw); 1699\& ev_timer_start (loop, &tw);
1607.Ve 1700.Ve
1608.PP 1701.PP
1609.Vb 6 1702.Vb 6
1610\& // create on ev_io per pollfd 1703\& // create one ev_io per pollfd
1611\& for (int i = 0; i < nfd; ++i) 1704\& for (int i = 0; i < nfd; ++i)
1612\& { 1705\& {
1613\& ev_io_init (iow + i, io_cb, fds [i].fd, 1706\& ev_io_init (iow + i, io_cb, fds [i].fd,
1614\& ((fds [i].events & POLLIN ? EV_READ : 0) 1707\& ((fds [i].events & POLLIN ? EV_READ : 0)
1615\& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); 1708\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1616.Ve 1709.Ve
1617.PP 1710.PP
1618.Vb 5 1711.Vb 4
1619\& fds [i].revents = 0; 1712\& fds [i].revents = 0;
1620\& iow [i].data = fds + i;
1621\& ev_io_start (loop, iow + i); 1713\& ev_io_start (loop, iow + i);
1622\& } 1714\& }
1623\& } 1715\& }
1624.Ve 1716.Ve
1625.PP 1717.PP
… …
1629\& adns_check_cb (ev_loop *loop, ev_check *w, int revents) 1721\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1630\& { 1722\& {
1631\& ev_timer_stop (loop, &tw); 1723\& ev_timer_stop (loop, &tw);
1632.Ve 1724.Ve
1633.PP 1725.PP
1634.Vb 2 1726.Vb 8
1635\& 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
1636\& ev_io_stop (loop, iow + i); 1739\& ev_io_stop (loop, iow + i);
1740\& }
1637.Ve 1741.Ve
1638.PP 1742.PP
1639.Vb 2 1743.Vb 2
1640\& 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;
1641\& } 1828\& }
1642.Ve 1829.Ve
1643.ie n .Sh """ev_embed"" \- when one backend isn't enough..." 1830.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1644.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..."
1645.IX Subsection "ev_embed - when one backend isn't enough..." 1832.IX Subsection "ev_embed - when one backend isn't enough..."
… …
1829.PP 2016.PP
1830.Vb 1 2017.Vb 1
1831\& #include <ev++.h> 2018\& #include <ev++.h>
1832.Ve 2019.Ve
1833.PP 2020.PP
1834(it is not installed by default). This automatically includes \fIev.h\fR 2021This automatically includes \fIev.h\fR and puts all of its definitions (many
1835and puts all of its definitions (many of them macros) into the global 2022of them macros) into the global namespace. All \*(C+ specific things are
1836namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace. 2023put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding
2024options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
1837.PP 2025.PP
1838It should support all the same embedding options as \fIev.h\fR, most notably 2026Care has been taken to keep the overhead low. The only data member the \*(C+
1839\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. 2027classes add (compared to plain C\-style watchers) is the event loop pointer
2028that the watcher is associated with (or no additional members at all if
2029you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev).
2030.PP
2031Currently, functions, and static and non-static member functions can be
2032used as callbacks. Other types should be easy to add as long as they only
2033need one additional pointer for context. If you need support for other
2034types of functors please contact the author (preferably after implementing
2035it).
1840.PP 2036.PP
1841Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: 2037Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
1842.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 2038.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
1843.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 2039.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
1844.IX Item "ev::READ, ev::WRITE etc." 2040.IX Item "ev::READ, ev::WRITE etc."
… …
1856which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro 2052which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
1857defines by many implementations. 2053defines by many implementations.
1858.Sp 2054.Sp
1859All of those classes have these methods: 2055All of those classes have these methods:
1860.RS 4 2056.RS 4
1861.IP "ev::TYPE::TYPE (object *, object::method *)" 4 2057.IP "ev::TYPE::TYPE ()" 4
1862.IX Item "ev::TYPE::TYPE (object *, object::method *)" 2058.IX Item "ev::TYPE::TYPE ()"
1863.PD 0 2059.PD 0
1864.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 2060.IP "ev::TYPE::TYPE (struct ev_loop *)" 4
1865.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 2061.IX Item "ev::TYPE::TYPE (struct ev_loop *)"
1866.IP "ev::TYPE::~TYPE" 4 2062.IP "ev::TYPE::~TYPE" 4
1867.IX Item "ev::TYPE::~TYPE" 2063.IX Item "ev::TYPE::~TYPE"
1868.PD 2064.PD
1869The constructor takes a pointer to an object and a method pointer to 2065The constructor (optionally) takes an event loop to associate the watcher
1870the event handler callback to call in this class. The constructor calls 2066with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR.
1871\&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method 2067.Sp
1872before starting it. If you do not specify a loop then the constructor 2068The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the
1873automatically associates the default loop with this watcher. 2069\&\f(CW\*(C`set\*(C'\fR method before starting it.
2070.Sp
2071It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR
2072method to set a callback before you can start the watcher.
2073.Sp
2074(The reason why you have to use a method is a limitation in \*(C+ which does
2075not allow explicit template arguments for constructors).
1874.Sp 2076.Sp
1875The destructor automatically stops the watcher if it is active. 2077The destructor automatically stops the watcher if it is active.
2078.IP "w\->set<class, &class::method> (object *)" 4
2079.IX Item "w->set<class, &class::method> (object *)"
2080This method sets the callback method to call. The method has to have a
2081signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as
2082first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as
2083parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher.
2084.Sp
2085This method synthesizes efficient thunking code to call your method from
2086the C callback that libev requires. If your compiler can inline your
2087callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and
2088your compiler is good :), then the method will be fully inlined into the
2089thunking function, making it as fast as a direct C callback.
2090.Sp
2091Example: simple class declaration and watcher initialisation
2092.Sp
2093.Vb 4
2094\& struct myclass
2095\& {
2096\& void io_cb (ev::io &w, int revents) { }
2097\& }
2098.Ve
2099.Sp
2100.Vb 3
2101\& myclass obj;
2102\& ev::io iow;
2103\& iow.set <myclass, &myclass::io_cb> (&obj);
2104.Ve
2105.IP "w\->set<function> (void *data = 0)" 4
2106.IX Item "w->set<function> (void *data = 0)"
2107Also sets a callback, but uses a static method or plain function as
2108callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's
2109\&\f(CW\*(C`data\*(C'\fR member and is free for you to use.
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
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
1876.IP "w\->set (struct ev_loop *)" 4 2121.IP "w\->set (struct ev_loop *)" 4
1877.IX Item "w->set (struct ev_loop *)" 2122.IX Item "w->set (struct ev_loop *)"
1878Associates 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
1879do this when the watcher is inactive (and not pending either). 2124do this when the watcher is inactive (and not pending either).
1880.IP "w\->set ([args])" 4 2125.IP "w\->set ([args])" 4
1881.IX Item "w->set ([args])" 2126.IX Item "w->set ([args])"
1882Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be 2127Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be
1883called at least once. Unlike the C counterpart, an active watcher gets 2128called at least once. Unlike the C counterpart, an active watcher gets
1884automatically stopped and restarted. 2129automatically stopped and restarted when reconfiguring it with this
2130method.
1885.IP "w\->start ()" 4 2131.IP "w\->start ()" 4
1886.IX Item "w->start ()" 2132.IX Item "w->start ()"
1887Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the 2133Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
1888constructor already takes the loop. 2134constructor already stores the event loop.
1889.IP "w\->stop ()" 4 2135.IP "w\->stop ()" 4
1890.IX Item "w->stop ()" 2136.IX Item "w->stop ()"
1891Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. 2137Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
1892.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4 2138.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4
1893.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4 2139.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4
… …
1919.Vb 2 2165.Vb 2
1920\& myclass (); 2166\& myclass ();
1921\& } 2167\& }
1922.Ve 2168.Ve
1923.PP 2169.PP
1924.Vb 6 2170.Vb 4
1925\& myclass::myclass (int fd) 2171\& myclass::myclass (int fd)
1926\& : io (this, &myclass::io_cb),
1927\& idle (this, &myclass::idle_cb)
1928\& { 2172\& {
2173\& io .set <myclass, &myclass::io_cb > (this);
2174\& idle.set <myclass, &myclass::idle_cb> (this);
2175.Ve
2176.PP
2177.Vb 2
1929\& io.start (fd, ev::READ); 2178\& io.start (fd, ev::READ);
1930\& } 2179\& }
1931.Ve 2180.Ve
1932.SH "MACRO MAGIC" 2181.SH "MACRO MAGIC"
1933.IX Header "MACRO MAGIC" 2182.IX Header "MACRO MAGIC"
1934Libev can be compiled with a variety of options, the most fundemantal is 2183Libev can be compiled with a variety of options, the most fundemantal is
1935\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines wether (most) functions and 2184\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) functions and
1936callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. 2185callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
1937.PP 2186.PP
1938To make it easier to write programs that cope with either variant, the 2187To make it easier to write programs that cope with either variant, the
1939following macros are defined: 2188following macros are defined:
1940.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 2189.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
… …
1975.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 2224.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
1976.IX Item "EV_DEFAULT, EV_DEFAULT_" 2225.IX Item "EV_DEFAULT, EV_DEFAULT_"
1977Similar to the other two macros, this gives you the value of the default 2226Similar to the other two macros, this gives you the value of the default
1978loop, if multiple loops are supported (\*(L"ev loop default\*(R"). 2227loop, if multiple loops are supported (\*(L"ev loop default\*(R").
1979.PP 2228.PP
1980Example: Declare and initialise a check watcher, working regardless of 2229Example: Declare and initialise a check watcher, utilising the above
1981wether multiple loops are supported or not. 2230macros so it will work regardless of whether multiple loops are supported
2231or not.
1982.PP 2232.PP
1983.Vb 5 2233.Vb 5
1984\& static void 2234\& static void
1985\& check_cb (EV_P_ ev_timer *w, int revents) 2235\& check_cb (EV_P_ ev_timer *w, int revents)
1986\& { 2236\& {
… …
2049.Vb 1 2299.Vb 1
2050\& ev_win32.c required on win32 platforms only 2300\& ev_win32.c required on win32 platforms only
2051.Ve 2301.Ve
2052.PP 2302.PP
2053.Vb 5 2303.Vb 5
2054\& ev_select.c only when select backend is enabled (which is by default) 2304\& ev_select.c only when select backend is enabled (which is enabled by default)
2055\& ev_poll.c only when poll backend is enabled (disabled by default) 2305\& ev_poll.c only when poll backend is enabled (disabled by default)
2056\& ev_epoll.c only when the epoll backend is enabled (disabled by default) 2306\& ev_epoll.c only when the epoll backend is enabled (disabled by default)
2057\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) 2307\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2058\& ev_port.c only when the solaris port backend is enabled (disabled by default) 2308\& ev_port.c only when the solaris port backend is enabled (disabled by default)
2059.Ve 2309.Ve
… …
2212If undefined or defined to \f(CW1\fR, then all event-loop-specific functions 2462If undefined or defined to \f(CW1\fR, then all event-loop-specific functions
2213will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create 2463will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create
2214additional independent event loops. Otherwise there will be no support 2464additional independent event loops. Otherwise there will be no support
2215for multiple event loops and there is no first event loop pointer 2465for multiple event loops and there is no first event loop pointer
2216argument. Instead, all functions act on the single default loop. 2466argument. Instead, all functions act on the single default loop.
2467.IP "\s-1EV_MINPRI\s0" 4
2468.IX Item "EV_MINPRI"
2469.PD 0
2470.IP "\s-1EV_MAXPRI\s0" 4
2471.IX Item "EV_MAXPRI"
2472.PD
2473The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to
2474\&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can
2475provide for more priorities by overriding those symbols (usually defined
2476to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively).
2477.Sp
2478When doing priority-based operations, libev usually has to linearly search
2479all the priorities, so having many of them (hundreds) uses a lot of space
2480and time, so using the defaults of five priorities (\-2 .. +2) is usually
2481fine.
2482.Sp
2483If your embedding app does not need any priorities, defining these both to
2484\&\f(CW0\fR will save some memory and cpu.
2217.IP "\s-1EV_PERIODIC_ENABLE\s0" 4 2485.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
2218.IX Item "EV_PERIODIC_ENABLE" 2486.IX Item "EV_PERIODIC_ENABLE"
2219If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If 2487If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
2488defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2489code.
2490.IP "\s-1EV_IDLE_ENABLE\s0" 4
2491.IX Item "EV_IDLE_ENABLE"
2492If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If
2220defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of 2493defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2221code. 2494code.
2222.IP "\s-1EV_EMBED_ENABLE\s0" 4 2495.IP "\s-1EV_EMBED_ENABLE\s0" 4
2223.IX Item "EV_EMBED_ENABLE" 2496.IX Item "EV_EMBED_ENABLE"
2224If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If 2497If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If
… …
2286interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file 2559interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file
2287will be compiled. It is pretty complex because it provides its own header 2560will be compiled. It is pretty complex because it provides its own header
2288file. 2561file.
2289.Sp 2562.Sp
2290The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file 2563The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
2291that everybody includes and which overrides some autoconf choices: 2564that everybody includes and which overrides some configure choices:
2292.Sp 2565.Sp
2293.Vb 4 2566.Vb 9
2567\& #define EV_MINIMAL 1
2294\& #define EV_USE_POLL 0 2568\& #define EV_USE_POLL 0
2295\& #define EV_MULTIPLICITY 0 2569\& #define EV_MULTIPLICITY 0
2296\& #define EV_PERIODICS 0 2570\& #define EV_PERIODIC_ENABLE 0
2571\& #define EV_STAT_ENABLE 0
2572\& #define EV_FORK_ENABLE 0
2297\& #define EV_CONFIG_H <config.h> 2573\& #define EV_CONFIG_H <config.h>
2574\& #define EV_MINPRI 0
2575\& #define EV_MAXPRI 0
2298.Ve 2576.Ve
2299.Sp 2577.Sp
2300.Vb 1 2578.Vb 1
2301\& #include "ev++.h" 2579\& #include "ev++.h"
2302.Ve 2580.Ve
… …
2310.SH "COMPLEXITIES" 2588.SH "COMPLEXITIES"
2311.IX Header "COMPLEXITIES" 2589.IX Header "COMPLEXITIES"
2312In this section the complexities of (many of) the algorithms used inside 2590In this section the complexities of (many of) the algorithms used inside
2313libev will be explained. For complexity discussions about backends see the 2591libev will be explained. For complexity discussions about backends see the
2314documentation for \f(CW\*(C`ev_default_init\*(C'\fR. 2592documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
2593.Sp
2594All of the following are about amortised time: If an array needs to be
2595extended, libev needs to realloc and move the whole array, but this
2596happens asymptotically never with higher number of elements, so O(1) might
2597mean it might do a lengthy realloc operation in rare cases, but on average
2598it is much faster and asymptotically approaches constant time.
2315.RS 4 2599.RS 4
2316.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 2600.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
2317.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 2601.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
2318.PD 0 2602This means that, when you have a watcher that triggers in one hour and
2603there are 100 watchers that would trigger before that then inserting will
2604have to skip those 100 watchers.
2319.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4 2605.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
2320.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 2606.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2607That means that for changing a timer costs less than removing/adding them
2608as only the relative motion in the event queue has to be paid for.
2321.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 2609.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
2322.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" 2610.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2323.IP "Stopping check/prepare/idle watchers: O(1)" 4 2611These just add the watcher into an array or at the head of a list.
2324.IX Item "Stopping check/prepare/idle watchers: O(1)" 2612=item Stopping check/prepare/idle watchers: O(1)
2325.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 2613.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
2326.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" 2614.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
2615These watchers are stored in lists then need to be walked to find the
2616correct watcher to remove. The lists are usually short (you don't usually
2617have many watchers waiting for the same fd or signal).
2327.IP "Finding the next timer per loop iteration: O(1)" 4 2618.IP "Finding the next timer per loop iteration: O(1)" 4
2328.IX Item "Finding the next timer per loop iteration: O(1)" 2619.IX Item "Finding the next timer per loop iteration: O(1)"
2620.PD 0
2329.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 2621.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
2330.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 2622.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
2623.PD
2624A change means an I/O watcher gets started or stopped, which requires
2625libev to recalculate its status (and possibly tell the kernel).
2331.IP "Activating one watcher: O(1)" 4 2626.IP "Activating one watcher: O(1)" 4
2332.IX Item "Activating one watcher: O(1)" 2627.IX Item "Activating one watcher: O(1)"
2628.PD 0
2629.IP "Priority handling: O(number_of_priorities)" 4
2630.IX Item "Priority handling: O(number_of_priorities)"
2631.PD
2632Priorities are implemented by allocating some space for each
2633priority. When doing priority-based operations, libev usually has to
2634linearly search all the priorities.
2333.RE 2635.RE
2334.RS 4 2636.RS 4
2335.PD
2336.SH "AUTHOR" 2637.SH "AUTHOR"
2337.IX Header "AUTHOR" 2638.IX Header "AUTHOR"
2338Marc Lehmann <libev@schmorp.de>. 2639Marc Lehmann <libev@schmorp.de>.

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