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Revision 1.37 by root, Fri Dec 7 16:49:49 2007 UTC vs.
Revision 1.49 by root, Wed Dec 12 04:53:58 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 "2007-12-12" "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
… …
255.IX Item "int ev_version_major ()" 259.IX Item "int ev_version_major ()"
256.PD 0 260.PD 0
257.IP "int ev_version_minor ()" 4 261.IP "int ev_version_minor ()" 4
258.IX Item "int ev_version_minor ()" 262.IX Item "int ev_version_minor ()"
259.PD 263.PD
260You can find out the major and minor version numbers of the library 264You can find out the major and minor \s-1ABI\s0 version numbers of the library
261you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and 265you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and
262\&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global 266\&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global
263symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the 267symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the
264version of the library your program was compiled against. 268version of the library your program was compiled against.
265.Sp 269.Sp
270These version numbers refer to the \s-1ABI\s0 version of the library, not the
271release version.
272.Sp
266Usually, it's a good idea to terminate if the major versions mismatch, 273Usually, it's a good idea to terminate if the major versions mismatch,
267as this indicates an incompatible change. Minor versions are usually 274as this indicates an incompatible change. Minor versions are usually
268compatible to older versions, so a larger minor version alone is usually 275compatible to older versions, so a larger minor version alone is usually
269not a problem. 276not a problem.
270.Sp 277.Sp
271Example: Make sure we haven't accidentally been linked against the wrong 278Example: Make sure we haven't accidentally been linked against the wrong
272version. 279version.
… …
630libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is 637libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is
631usually a better approach for this kind of thing. 638usually a better approach for this kind of thing.
632.Sp 639.Sp
633Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: 640Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does:
634.Sp 641.Sp
635.Vb 18 642.Vb 19
643\& - Before the first iteration, call any pending watchers.
636\& * If there are no active watchers (reference count is zero), return. 644\& * If there are no active watchers (reference count is zero), return.
637\& - Queue prepare watchers and then call all outstanding watchers. 645\& - Queue all prepare watchers and then call all outstanding watchers.
638\& - If we have been forked, recreate the kernel state. 646\& - If we have been forked, recreate the kernel state.
639\& - Update the kernel state with all outstanding changes. 647\& - Update the kernel state with all outstanding changes.
640\& - Update the "event loop time". 648\& - Update the "event loop time".
641\& - Calculate for how long to block. 649\& - Calculate for how long to block.
642\& - Block the process, waiting for any events. 650\& - Block the process, waiting for any events.
… …
885.IP "bool ev_is_pending (ev_TYPE *watcher)" 4 893.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
886.IX Item "bool ev_is_pending (ev_TYPE *watcher)" 894.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
887Returns a true value iff the watcher is pending, (i.e. it has outstanding 895Returns a true value iff the watcher is pending, (i.e. it has outstanding
888events but its callback has not yet been invoked). As long as a watcher 896events but its callback has not yet been invoked). As long as a watcher
889is pending (but not active) you must not call an init function on it (but 897is pending (but not active) you must not call an init function on it (but
890\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to 898\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must
891libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). 899make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR
900it).
892.IP "callback ev_cb (ev_TYPE *watcher)" 4 901.IP "callback ev_cb (ev_TYPE *watcher)" 4
893.IX Item "callback ev_cb (ev_TYPE *watcher)" 902.IX Item "callback ev_cb (ev_TYPE *watcher)"
894Returns the callback currently set on the watcher. 903Returns the callback currently set on the watcher.
895.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 904.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
896.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 905.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
… …
914watchers on the same event and make sure one is called first. 923watchers on the same event and make sure one is called first.
915.Sp 924.Sp
916If you need to suppress invocation when higher priority events are pending 925If you need to suppress invocation when higher priority events are pending
917you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. 926you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality.
918.Sp 927.Sp
928You \fImust not\fR change the priority of a watcher as long as it is active or
929pending.
930.Sp
919The default priority used by watchers when no priority has been set is 931The default priority used by watchers when no priority has been set is
920always \f(CW0\fR, which is supposed to not be too high and not be too low :). 932always \f(CW0\fR, which is supposed to not be too high and not be too low :).
921.Sp 933.Sp
922Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is 934Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is
923fine, as long as you do not mind that the priority value you query might 935fine, as long as you do not mind that the priority value you query might
924or might not have been adjusted to be within valid range. 936or might not have been adjusted to be within valid range.
937.IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4
938.IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)"
939Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither
940\&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback
941can deal with that fact.
942.IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4
943.IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)"
944If the watcher is pending, this function returns clears its pending status
945and returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the
946watcher isn't pending it does nothing and returns \f(CW0\fR.
925.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 947.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
926.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 948.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
927Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change 949Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change
928and read at any time, libev will completely ignore it. This can be used 950and read at any time, libev will completely ignore it. This can be used
929to associate arbitrary data with your watcher. If you need more data and 951to associate arbitrary data with your watcher. If you need more data and
… …
1040it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning 1062it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning
1041\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. 1063\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
1042.PP 1064.PP
1043If you cannot run the fd in non-blocking mode (for example you should not 1065If you cannot run the fd in non-blocking mode (for example you should not
1044play around with an Xlib connection), then you have to seperately re-test 1066play around with an Xlib connection), then you have to seperately re-test
1045wether a file descriptor is really ready with a known-to-be good interface 1067whether a file descriptor is really ready with a known-to-be good interface
1046such as poll (fortunately in our Xlib example, Xlib already does this on 1068such as poll (fortunately in our Xlib example, Xlib already does this on
1047its own, so its quite safe to use). 1069its own, so its quite safe to use).
1070.PP
1071\fIThe special problem of disappearing file descriptors\fR
1072.IX Subsection "The special problem of disappearing file descriptors"
1073.PP
1074Some backends (e.g kqueue, epoll) need to be told about closing a file
1075descriptor (either by calling \f(CW\*(C`close\*(C'\fR explicitly or by any other means,
1076such as \f(CW\*(C`dup\*(C'\fR). The reason is that you register interest in some file
1077descriptor, but when it goes away, the operating system will silently drop
1078this interest. If another file descriptor with the same number then is
1079registered with libev, there is no efficient way to see that this is, in
1080fact, a different file descriptor.
1081.PP
1082To avoid having to explicitly tell libev about such cases, libev follows
1083the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev
1084will assume that this is potentially a new file descriptor, otherwise
1085it is assumed that the file descriptor stays the same. That means that
1086you \fIhave\fR to call \f(CW\*(C`ev_io_set\*(C'\fR (or \f(CW\*(C`ev_io_init\*(C'\fR) when you change the
1087descriptor even if the file descriptor number itself did not change.
1088.PP
1089This is how one would do it normally anyway, the important point is that
1090the libev application should not optimise around libev but should leave
1091optimisations to libev.
1048.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 1092.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
1049.IX Item "ev_io_init (ev_io *, callback, int fd, int events)" 1093.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
1050.PD 0 1094.PD 0
1051.IP "ev_io_set (ev_io *, int fd, int events)" 4 1095.IP "ev_io_set (ev_io *, int fd, int events)" 4
1052.IX Item "ev_io_set (ev_io *, int fd, int events)" 1096.IX Item "ev_io_set (ev_io *, int fd, int events)"
… …
1216but on wallclock time (absolute time). You can tell a periodic watcher 1260but on wallclock time (absolute time). You can tell a periodic watcher
1217to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a 1261to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a
1218periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () 1262periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now ()
1219+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will 1263+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will
1220take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger 1264take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger
1221roughly 10 seconds later and of course not if you reset your system time 1265roughly 10 seconds later).
1222again).
1223.PP 1266.PP
1224They can also be used to implement vastly more complex timers, such as 1267They can also be used to implement vastly more complex timers, such as
1225triggering an event on eahc midnight, local time. 1268triggering an event on each midnight, local time or other, complicated,
1269rules.
1226.PP 1270.PP
1227As with timers, the callback is guarenteed to be invoked only when the 1271As with timers, the callback is guarenteed to be invoked only when the
1228time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready 1272time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready
1229during the same loop iteration then order of execution is undefined. 1273during the same loop iteration then order of execution is undefined.
1230.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 1274.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4
… …
1234.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 1278.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)"
1235.PD 1279.PD
1236Lots of arguments, lets sort it out... There are basically three modes of 1280Lots of arguments, lets sort it out... There are basically three modes of
1237operation, and we will explain them from simplest to complex: 1281operation, and we will explain them from simplest to complex:
1238.RS 4 1282.RS 4
1239.IP "* absolute timer (interval = reschedule_cb = 0)" 4 1283.IP "* absolute timer (at = time, interval = reschedule_cb = 0)" 4
1240.IX Item "absolute timer (interval = reschedule_cb = 0)" 1284.IX Item "absolute timer (at = time, interval = reschedule_cb = 0)"
1241In this configuration the watcher triggers an event at the wallclock time 1285In this configuration the watcher triggers an event at the wallclock time
1242\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, 1286\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs,
1243that is, if it is to be run at January 1st 2011 then it will run when the 1287that is, if it is to be run at January 1st 2011 then it will run when the
1244system time reaches or surpasses this time. 1288system time reaches or surpasses this time.
1245.IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4 1289.IP "* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" 4
1246.IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)" 1290.IX Item "non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)"
1247In this mode the watcher will always be scheduled to time out at the next 1291In this mode the watcher will always be scheduled to time out at the next
1248\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless 1292\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative)
1249of any time jumps. 1293and then repeat, regardless of any time jumps.
1250.Sp 1294.Sp
1251This can be used to create timers that do not drift with respect to system 1295This can be used to create timers that do not drift with respect to system
1252time: 1296time:
1253.Sp 1297.Sp
1254.Vb 1 1298.Vb 1
… …
1261by 3600. 1305by 3600.
1262.Sp 1306.Sp
1263Another way to think about it (for the mathematically inclined) is that 1307Another way to think about it (for the mathematically inclined) is that
1264\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible 1308\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible
1265time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. 1309time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps.
1310.Sp
1311For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near
1312\&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for
1313this value.
1266.IP "* manual reschedule mode (reschedule_cb = callback)" 4 1314.IP "* manual reschedule mode (at and interval ignored, reschedule_cb = callback)" 4
1267.IX Item "manual reschedule mode (reschedule_cb = callback)" 1315.IX Item "manual reschedule mode (at and interval ignored, reschedule_cb = callback)"
1268In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being 1316In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being
1269ignored. Instead, each time the periodic watcher gets scheduled, the 1317ignored. Instead, each time the periodic watcher gets scheduled, the
1270reschedule callback will be called with the watcher as first, and the 1318reschedule callback will be called with the watcher as first, and the
1271current time as second argument. 1319current time as second argument.
1272.Sp 1320.Sp
1273\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, 1321\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher,
1274ever, or make any event loop modifications\fR. If you need to stop it, 1322ever, or make any event loop modifications\fR. If you need to stop it,
1275return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by 1323return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by
1276starting a prepare watcher). 1324starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal).
1277.Sp 1325.Sp
1278Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, 1326Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
1279ev_tstamp now)\*(C'\fR, e.g.: 1327ev_tstamp now)\*(C'\fR, e.g.:
1280.Sp 1328.Sp
1281.Vb 4 1329.Vb 4
… …
1305.IX Item "ev_periodic_again (loop, ev_periodic *)" 1353.IX Item "ev_periodic_again (loop, ev_periodic *)"
1306Simply stops and restarts the periodic watcher again. This is only useful 1354Simply stops and restarts the periodic watcher again. This is only useful
1307when you changed some parameters or the reschedule callback would return 1355when you changed some parameters or the reschedule callback would return
1308a different time than the last time it was called (e.g. in a crond like 1356a different time than the last time it was called (e.g. in a crond like
1309program when the crontabs have changed). 1357program when the crontabs have changed).
1358.IP "ev_tstamp offset [read\-write]" 4
1359.IX Item "ev_tstamp offset [read-write]"
1360When repeating, this contains the offset value, otherwise this is the
1361absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR).
1362.Sp
1363Can be modified any time, but changes only take effect when the periodic
1364timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1310.IP "ev_tstamp interval [read\-write]" 4 1365.IP "ev_tstamp interval [read\-write]" 4
1311.IX Item "ev_tstamp interval [read-write]" 1366.IX Item "ev_tstamp interval [read-write]"
1312The current interval value. Can be modified any time, but changes only 1367The current interval value. Can be modified any time, but changes only
1313take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being 1368take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being
1314called. 1369called.
… …
1616are ready to run (it's actually more complicated: it only runs coroutines 1671are ready to run (it's actually more complicated: it only runs coroutines
1617with priority higher than or equal to the event loop and one coroutine 1672with priority higher than or equal to the event loop and one coroutine
1618of lower priority, but only once, using idle watchers to keep the event 1673of lower priority, but only once, using idle watchers to keep the event
1619loop from blocking if lower-priority coroutines are active, thus mapping 1674loop from blocking if lower-priority coroutines are active, thus mapping
1620low-priority coroutines to idle/background tasks). 1675low-priority coroutines to idle/background tasks).
1676.PP
1677It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR)
1678priority, to ensure that they are being run before any other watchers
1679after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers,
1680too) should not activate (\*(L"feed\*(R") events into libev. While libev fully
1681supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers did
1682their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other event
1683loops those other event loops might be in an unusable state until their
1684\&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with
1685others).
1621.IP "ev_prepare_init (ev_prepare *, callback)" 4 1686.IP "ev_prepare_init (ev_prepare *, callback)" 4
1622.IX Item "ev_prepare_init (ev_prepare *, callback)" 1687.IX Item "ev_prepare_init (ev_prepare *, callback)"
1623.PD 0 1688.PD 0
1624.IP "ev_check_init (ev_check *, callback)" 4 1689.IP "ev_check_init (ev_check *, callback)" 4
1625.IX Item "ev_check_init (ev_check *, callback)" 1690.IX Item "ev_check_init (ev_check *, callback)"
1626.PD 1691.PD
1627Initialises and configures the prepare or check watcher \- they have no 1692Initialises and configures the prepare or check watcher \- they have no
1628parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR 1693parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR
1629macros, but using them is utterly, utterly and completely pointless. 1694macros, but using them is utterly, utterly and completely pointless.
1630.PP 1695.PP
1631Example: To include a library such as adns, you would add \s-1IO\s0 watchers 1696There are a number of principal ways to embed other event loops or modules
1632and a timeout watcher in a prepare handler, as required by libadns, and 1697into libev. Here are some ideas on how to include libadns into libev
1698(there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could
1699use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR
1700embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0
1701into the Glib event loop).
1702.PP
1703Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler,
1633in a check watcher, destroy them and call into libadns. What follows is 1704and in a check watcher, destroy them and call into libadns. What follows
1634pseudo-code only of course: 1705is pseudo-code only of course. This requires you to either use a low
1706priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as
1707the callbacks for the IO/timeout watchers might not have been called yet.
1635.PP 1708.PP
1636.Vb 2 1709.Vb 2
1637\& static ev_io iow [nfd]; 1710\& static ev_io iow [nfd];
1638\& static ev_timer tw; 1711\& static ev_timer tw;
1639.Ve 1712.Ve
1640.PP 1713.PP
1641.Vb 9 1714.Vb 4
1642\& static void 1715\& static void
1643\& io_cb (ev_loop *loop, ev_io *w, int revents) 1716\& io_cb (ev_loop *loop, ev_io *w, int revents)
1644\& { 1717\& {
1645\& // set the relevant poll flags
1646\& // could also call adns_processreadable etc. here
1647\& struct pollfd *fd = (struct pollfd *)w->data;
1648\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1649\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1650\& } 1718\& }
1651.Ve 1719.Ve
1652.PP 1720.PP
1653.Vb 8 1721.Vb 8
1654\& // create io watchers for each fd and a timer before blocking 1722\& // create io watchers for each fd and a timer before blocking
… …
1666\& ev_timer_init (&tw, 0, timeout * 1e-3); 1734\& ev_timer_init (&tw, 0, timeout * 1e-3);
1667\& ev_timer_start (loop, &tw); 1735\& ev_timer_start (loop, &tw);
1668.Ve 1736.Ve
1669.PP 1737.PP
1670.Vb 6 1738.Vb 6
1671\& // create on ev_io per pollfd 1739\& // create one ev_io per pollfd
1672\& for (int i = 0; i < nfd; ++i) 1740\& for (int i = 0; i < nfd; ++i)
1673\& { 1741\& {
1674\& ev_io_init (iow + i, io_cb, fds [i].fd, 1742\& ev_io_init (iow + i, io_cb, fds [i].fd,
1675\& ((fds [i].events & POLLIN ? EV_READ : 0) 1743\& ((fds [i].events & POLLIN ? EV_READ : 0)
1676\& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); 1744\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1677.Ve 1745.Ve
1678.PP 1746.PP
1679.Vb 5 1747.Vb 4
1680\& fds [i].revents = 0; 1748\& fds [i].revents = 0;
1681\& iow [i].data = fds + i;
1682\& ev_io_start (loop, iow + i); 1749\& ev_io_start (loop, iow + i);
1683\& } 1750\& }
1684\& } 1751\& }
1685.Ve 1752.Ve
1686.PP 1753.PP
… …
1690\& adns_check_cb (ev_loop *loop, ev_check *w, int revents) 1757\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1691\& { 1758\& {
1692\& ev_timer_stop (loop, &tw); 1759\& ev_timer_stop (loop, &tw);
1693.Ve 1760.Ve
1694.PP 1761.PP
1695.Vb 2 1762.Vb 8
1696\& for (int i = 0; i < nfd; ++i) 1763\& for (int i = 0; i < nfd; ++i)
1764\& {
1765\& // set the relevant poll flags
1766\& // could also call adns_processreadable etc. here
1767\& struct pollfd *fd = fds + i;
1768\& int revents = ev_clear_pending (iow + i);
1769\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1770\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1771.Ve
1772.PP
1773.Vb 3
1774\& // now stop the watcher
1697\& ev_io_stop (loop, iow + i); 1775\& ev_io_stop (loop, iow + i);
1776\& }
1698.Ve 1777.Ve
1699.PP 1778.PP
1700.Vb 2 1779.Vb 2
1701\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); 1780\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1781\& }
1782.Ve
1783.PP
1784Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR
1785in the prepare watcher and would dispose of the check watcher.
1786.PP
1787Method 3: If the module to be embedded supports explicit event
1788notification (adns does), you can also make use of the actual watcher
1789callbacks, and only destroy/create the watchers in the prepare watcher.
1790.PP
1791.Vb 5
1792\& static void
1793\& timer_cb (EV_P_ ev_timer *w, int revents)
1794\& {
1795\& adns_state ads = (adns_state)w->data;
1796\& update_now (EV_A);
1797.Ve
1798.PP
1799.Vb 2
1800\& adns_processtimeouts (ads, &tv_now);
1801\& }
1802.Ve
1803.PP
1804.Vb 5
1805\& static void
1806\& io_cb (EV_P_ ev_io *w, int revents)
1807\& {
1808\& adns_state ads = (adns_state)w->data;
1809\& update_now (EV_A);
1810.Ve
1811.PP
1812.Vb 3
1813\& if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1814\& if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1815\& }
1816.Ve
1817.PP
1818.Vb 1
1819\& // do not ever call adns_afterpoll
1820.Ve
1821.PP
1822Method 4: Do not use a prepare or check watcher because the module you
1823want to embed is too inflexible to support it. Instead, youc na override
1824their poll function. The drawback with this solution is that the main
1825loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does
1826this.
1827.PP
1828.Vb 4
1829\& static gint
1830\& event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1831\& {
1832\& int got_events = 0;
1833.Ve
1834.PP
1835.Vb 2
1836\& for (n = 0; n < nfds; ++n)
1837\& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1838.Ve
1839.PP
1840.Vb 2
1841\& if (timeout >= 0)
1842\& // create/start timer
1843.Ve
1844.PP
1845.Vb 2
1846\& // poll
1847\& ev_loop (EV_A_ 0);
1848.Ve
1849.PP
1850.Vb 3
1851\& // stop timer again
1852\& if (timeout >= 0)
1853\& ev_timer_stop (EV_A_ &to);
1854.Ve
1855.PP
1856.Vb 3
1857\& // stop io watchers again - their callbacks should have set
1858\& for (n = 0; n < nfds; ++n)
1859\& ev_io_stop (EV_A_ iow [n]);
1860.Ve
1861.PP
1862.Vb 2
1863\& return got_events;
1702\& } 1864\& }
1703.Ve 1865.Ve
1704.ie n .Sh """ev_embed"" \- when one backend isn't enough..." 1866.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1705.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." 1867.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
1706.IX Subsection "ev_embed - when one backend isn't enough..." 1868.IX Subsection "ev_embed - when one backend isn't enough..."
… …
1890.PP 2052.PP
1891.Vb 1 2053.Vb 1
1892\& #include <ev++.h> 2054\& #include <ev++.h>
1893.Ve 2055.Ve
1894.PP 2056.PP
1895(it is not installed by default). This automatically includes \fIev.h\fR 2057This automatically includes \fIev.h\fR and puts all of its definitions (many
1896and puts all of its definitions (many of them macros) into the global 2058of them macros) into the global namespace. All \*(C+ specific things are
1897namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace. 2059put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding
2060options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
1898.PP 2061.PP
1899It should support all the same embedding options as \fIev.h\fR, most notably 2062Care has been taken to keep the overhead low. The only data member the \*(C+
1900\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. 2063classes add (compared to plain C\-style watchers) is the event loop pointer
2064that the watcher is associated with (or no additional members at all if
2065you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev).
2066.PP
2067Currently, functions, and static and non-static member functions can be
2068used as callbacks. Other types should be easy to add as long as they only
2069need one additional pointer for context. If you need support for other
2070types of functors please contact the author (preferably after implementing
2071it).
1901.PP 2072.PP
1902Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: 2073Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
1903.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 2074.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
1904.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 2075.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
1905.IX Item "ev::READ, ev::WRITE etc." 2076.IX Item "ev::READ, ev::WRITE etc."
… …
1917which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro 2088which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
1918defines by many implementations. 2089defines by many implementations.
1919.Sp 2090.Sp
1920All of those classes have these methods: 2091All of those classes have these methods:
1921.RS 4 2092.RS 4
1922.IP "ev::TYPE::TYPE (object *, object::method *)" 4 2093.IP "ev::TYPE::TYPE ()" 4
1923.IX Item "ev::TYPE::TYPE (object *, object::method *)" 2094.IX Item "ev::TYPE::TYPE ()"
1924.PD 0 2095.PD 0
1925.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 2096.IP "ev::TYPE::TYPE (struct ev_loop *)" 4
1926.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 2097.IX Item "ev::TYPE::TYPE (struct ev_loop *)"
1927.IP "ev::TYPE::~TYPE" 4 2098.IP "ev::TYPE::~TYPE" 4
1928.IX Item "ev::TYPE::~TYPE" 2099.IX Item "ev::TYPE::~TYPE"
1929.PD 2100.PD
1930The constructor takes a pointer to an object and a method pointer to 2101The constructor (optionally) takes an event loop to associate the watcher
1931the event handler callback to call in this class. The constructor calls 2102with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR.
1932\&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method 2103.Sp
1933before starting it. If you do not specify a loop then the constructor 2104The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the
1934automatically associates the default loop with this watcher. 2105\&\f(CW\*(C`set\*(C'\fR method before starting it.
2106.Sp
2107It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR
2108method to set a callback before you can start the watcher.
2109.Sp
2110(The reason why you have to use a method is a limitation in \*(C+ which does
2111not allow explicit template arguments for constructors).
1935.Sp 2112.Sp
1936The destructor automatically stops the watcher if it is active. 2113The destructor automatically stops the watcher if it is active.
2114.IP "w\->set<class, &class::method> (object *)" 4
2115.IX Item "w->set<class, &class::method> (object *)"
2116This method sets the callback method to call. The method has to have a
2117signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as
2118first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as
2119parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher.
2120.Sp
2121This method synthesizes efficient thunking code to call your method from
2122the C callback that libev requires. If your compiler can inline your
2123callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and
2124your compiler is good :), then the method will be fully inlined into the
2125thunking function, making it as fast as a direct C callback.
2126.Sp
2127Example: simple class declaration and watcher initialisation
2128.Sp
2129.Vb 4
2130\& struct myclass
2131\& {
2132\& void io_cb (ev::io &w, int revents) { }
2133\& }
2134.Ve
2135.Sp
2136.Vb 3
2137\& myclass obj;
2138\& ev::io iow;
2139\& iow.set <myclass, &myclass::io_cb> (&obj);
2140.Ve
2141.IP "w\->set<function> (void *data = 0)" 4
2142.IX Item "w->set<function> (void *data = 0)"
2143Also sets a callback, but uses a static method or plain function as
2144callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's
2145\&\f(CW\*(C`data\*(C'\fR member and is free for you to use.
2146.Sp
2147The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR.
2148.Sp
2149See the method\-\f(CW\*(C`set\*(C'\fR above for more details.
2150.Sp
2151Example:
2152.Sp
2153.Vb 2
2154\& static void io_cb (ev::io &w, int revents) { }
2155\& iow.set <io_cb> ();
2156.Ve
1937.IP "w\->set (struct ev_loop *)" 4 2157.IP "w\->set (struct ev_loop *)" 4
1938.IX Item "w->set (struct ev_loop *)" 2158.IX Item "w->set (struct ev_loop *)"
1939Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only 2159Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
1940do this when the watcher is inactive (and not pending either). 2160do this when the watcher is inactive (and not pending either).
1941.IP "w\->set ([args])" 4 2161.IP "w\->set ([args])" 4
1942.IX Item "w->set ([args])" 2162.IX Item "w->set ([args])"
1943Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be 2163Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be
1944called at least once. Unlike the C counterpart, an active watcher gets 2164called at least once. Unlike the C counterpart, an active watcher gets
1945automatically stopped and restarted. 2165automatically stopped and restarted when reconfiguring it with this
2166method.
1946.IP "w\->start ()" 4 2167.IP "w\->start ()" 4
1947.IX Item "w->start ()" 2168.IX Item "w->start ()"
1948Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the 2169Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
1949constructor already takes the loop. 2170constructor already stores the event loop.
1950.IP "w\->stop ()" 4 2171.IP "w\->stop ()" 4
1951.IX Item "w->stop ()" 2172.IX Item "w->stop ()"
1952Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. 2173Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
1953.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4 2174.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4
1954.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4 2175.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4
… …
1980.Vb 2 2201.Vb 2
1981\& myclass (); 2202\& myclass ();
1982\& } 2203\& }
1983.Ve 2204.Ve
1984.PP 2205.PP
1985.Vb 6 2206.Vb 4
1986\& myclass::myclass (int fd) 2207\& myclass::myclass (int fd)
1987\& : io (this, &myclass::io_cb),
1988\& idle (this, &myclass::idle_cb)
1989\& { 2208\& {
2209\& io .set <myclass, &myclass::io_cb > (this);
2210\& idle.set <myclass, &myclass::idle_cb> (this);
2211.Ve
2212.PP
2213.Vb 2
1990\& io.start (fd, ev::READ); 2214\& io.start (fd, ev::READ);
1991\& } 2215\& }
1992.Ve 2216.Ve
1993.SH "MACRO MAGIC" 2217.SH "MACRO MAGIC"
1994.IX Header "MACRO MAGIC" 2218.IX Header "MACRO MAGIC"
1995Libev can be compiled with a variety of options, the most fundemantal is 2219Libev can be compiled with a variety of options, the most fundemantal is
1996\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines wether (most) functions and 2220\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) functions and
1997callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. 2221callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
1998.PP 2222.PP
1999To make it easier to write programs that cope with either variant, the 2223To make it easier to write programs that cope with either variant, the
2000following macros are defined: 2224following macros are defined:
2001.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 2225.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
… …
2037.IX Item "EV_DEFAULT, EV_DEFAULT_" 2261.IX Item "EV_DEFAULT, EV_DEFAULT_"
2038Similar to the other two macros, this gives you the value of the default 2262Similar to the other two macros, this gives you the value of the default
2039loop, if multiple loops are supported (\*(L"ev loop default\*(R"). 2263loop, if multiple loops are supported (\*(L"ev loop default\*(R").
2040.PP 2264.PP
2041Example: Declare and initialise a check watcher, utilising the above 2265Example: Declare and initialise a check watcher, utilising the above
2042macros so it will work regardless of wether multiple loops are supported 2266macros so it will work regardless of whether multiple loops are supported
2043or not. 2267or not.
2044.PP 2268.PP
2045.Vb 5 2269.Vb 5
2046\& static void 2270\& static void
2047\& check_cb (EV_P_ ev_timer *w, int revents) 2271\& check_cb (EV_P_ ev_timer *w, int revents)
… …
2274If undefined or defined to \f(CW1\fR, then all event-loop-specific functions 2498If undefined or defined to \f(CW1\fR, then all event-loop-specific functions
2275will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create 2499will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create
2276additional independent event loops. Otherwise there will be no support 2500additional independent event loops. Otherwise there will be no support
2277for multiple event loops and there is no first event loop pointer 2501for multiple event loops and there is no first event loop pointer
2278argument. Instead, all functions act on the single default loop. 2502argument. Instead, all functions act on the single default loop.
2503.IP "\s-1EV_MINPRI\s0" 4
2504.IX Item "EV_MINPRI"
2505.PD 0
2506.IP "\s-1EV_MAXPRI\s0" 4
2507.IX Item "EV_MAXPRI"
2508.PD
2509The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to
2510\&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can
2511provide for more priorities by overriding those symbols (usually defined
2512to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively).
2513.Sp
2514When doing priority-based operations, libev usually has to linearly search
2515all the priorities, so having many of them (hundreds) uses a lot of space
2516and time, so using the defaults of five priorities (\-2 .. +2) is usually
2517fine.
2518.Sp
2519If your embedding app does not need any priorities, defining these both to
2520\&\f(CW0\fR will save some memory and cpu.
2279.IP "\s-1EV_PERIODIC_ENABLE\s0" 4 2521.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
2280.IX Item "EV_PERIODIC_ENABLE" 2522.IX Item "EV_PERIODIC_ENABLE"
2281If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If 2523If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
2282defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of 2524defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2283code. 2525code.
… …
2382.SH "COMPLEXITIES" 2624.SH "COMPLEXITIES"
2383.IX Header "COMPLEXITIES" 2625.IX Header "COMPLEXITIES"
2384In this section the complexities of (many of) the algorithms used inside 2626In this section the complexities of (many of) the algorithms used inside
2385libev will be explained. For complexity discussions about backends see the 2627libev will be explained. For complexity discussions about backends see the
2386documentation for \f(CW\*(C`ev_default_init\*(C'\fR. 2628documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
2629.Sp
2630All of the following are about amortised time: If an array needs to be
2631extended, libev needs to realloc and move the whole array, but this
2632happens asymptotically never with higher number of elements, so O(1) might
2633mean it might do a lengthy realloc operation in rare cases, but on average
2634it is much faster and asymptotically approaches constant time.
2387.RS 4 2635.RS 4
2388.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 2636.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
2389.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 2637.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
2390.PD 0 2638This means that, when you have a watcher that triggers in one hour and
2639there are 100 watchers that would trigger before that then inserting will
2640have to skip those 100 watchers.
2391.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4 2641.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
2392.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 2642.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2643That means that for changing a timer costs less than removing/adding them
2644as only the relative motion in the event queue has to be paid for.
2393.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 2645.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
2394.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" 2646.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2395.IP "Stopping check/prepare/idle watchers: O(1)" 4 2647These just add the watcher into an array or at the head of a list.
2396.IX Item "Stopping check/prepare/idle watchers: O(1)" 2648=item Stopping check/prepare/idle watchers: O(1)
2397.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 2649.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
2398.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" 2650.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
2651These watchers are stored in lists then need to be walked to find the
2652correct watcher to remove. The lists are usually short (you don't usually
2653have many watchers waiting for the same fd or signal).
2399.IP "Finding the next timer per loop iteration: O(1)" 4 2654.IP "Finding the next timer per loop iteration: O(1)" 4
2400.IX Item "Finding the next timer per loop iteration: O(1)" 2655.IX Item "Finding the next timer per loop iteration: O(1)"
2656.PD 0
2401.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 2657.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
2402.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 2658.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
2659.PD
2660A change means an I/O watcher gets started or stopped, which requires
2661libev to recalculate its status (and possibly tell the kernel).
2403.IP "Activating one watcher: O(1)" 4 2662.IP "Activating one watcher: O(1)" 4
2404.IX Item "Activating one watcher: O(1)" 2663.IX Item "Activating one watcher: O(1)"
2664.PD 0
2665.IP "Priority handling: O(number_of_priorities)" 4
2666.IX Item "Priority handling: O(number_of_priorities)"
2667.PD
2668Priorities are implemented by allocating some space for each
2669priority. When doing priority-based operations, libev usually has to
2670linearly search all the priorities.
2405.RE 2671.RE
2406.RS 4 2672.RS 4
2407.PD
2408.SH "AUTHOR" 2673.SH "AUTHOR"
2409.IX Header "AUTHOR" 2674.IX Header "AUTHOR"
2410Marc Lehmann <libev@schmorp.de>. 2675Marc Lehmann <libev@schmorp.de>.

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