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Revision 1.40 by root, Fri Dec 7 19:23:48 2007 UTC vs.
Revision 1.53 by root, Wed Dec 19 01:59:29 2007 UTC

… …
126. ds Ae AE 126. ds Ae AE
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 "EV 1"
132.TH "<STANDARD INPUT>" 1 "2007-12-07" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH EV 1 "2007-12-19" "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
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243Libev represents time as a single floating point number, representing the 243Libev represents time as a single floating point number, representing the
244(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near 244(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near
245the beginning of 1970, details are complicated, don't ask). This type is 245the beginning of 1970, details are complicated, don't ask). This type is
246called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases 246called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases
247to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on 247to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on
248it, you should treat it as such. 248it, you should treat it as some floatingpoint value. Unlike the name
249component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences
250throughout libev.
249.SH "GLOBAL FUNCTIONS" 251.SH "GLOBAL FUNCTIONS"
250.IX Header "GLOBAL FUNCTIONS" 252.IX Header "GLOBAL FUNCTIONS"
251These functions can be called anytime, even before initialising the 253These functions can be called anytime, even before initialising the
252library in any way. 254library in any way.
253.IP "ev_tstamp ev_time ()" 4 255.IP "ev_tstamp ev_time ()" 4
… …
259.IX Item "int ev_version_major ()" 261.IX Item "int ev_version_major ()"
260.PD 0 262.PD 0
261.IP "int ev_version_minor ()" 4 263.IP "int ev_version_minor ()" 4
262.IX Item "int ev_version_minor ()" 264.IX Item "int ev_version_minor ()"
263.PD 265.PD
264You can find out the major and minor version numbers of the library 266You can find out the major and minor \s-1ABI\s0 version numbers of the library
265you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and 267you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and
266\&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global 268\&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global
267symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the 269symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the
268version of the library your program was compiled against. 270version of the library your program was compiled against.
269.Sp 271.Sp
272These version numbers refer to the \s-1ABI\s0 version of the library, not the
273release version.
274.Sp
270Usually, it's a good idea to terminate if the major versions mismatch, 275Usually, it's a good idea to terminate if the major versions mismatch,
271as this indicates an incompatible change. Minor versions are usually 276as this indicates an incompatible change. Minor versions are usually
272compatible to older versions, so a larger minor version alone is usually 277compatible to older versions, so a larger minor version alone is usually
273not a problem. 278not a problem.
274.Sp 279.Sp
275Example: Make sure we haven't accidentally been linked against the wrong 280Example: Make sure we haven't accidentally been linked against the wrong
276version. 281version.
… …
552Destroys the default loop again (frees all memory and kernel state 557Destroys the default loop again (frees all memory and kernel state
553etc.). None of the active event watchers will be stopped in the normal 558etc.). None of the active event watchers will be stopped in the normal
554sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your 559sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your
555responsibility to either stop all watchers cleanly yoursef \fIbefore\fR 560responsibility to either stop all watchers cleanly yoursef \fIbefore\fR
556calling this function, or cope with the fact afterwards (which is usually 561calling this function, or cope with the fact afterwards (which is usually
557the easiest thing, youc na just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them 562the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them
558for example). 563for example).
564.Sp
565Not that certain global state, such as signal state, will not be freed by
566this function, and related watchers (such as signal and child watchers)
567would need to be stopped manually.
568.Sp
569In general it is not advisable to call this function except in the
570rare occasion where you really need to free e.g. the signal handling
571pipe fds. If you need dynamically allocated loops it is better to use
572\&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR).
559.IP "ev_loop_destroy (loop)" 4 573.IP "ev_loop_destroy (loop)" 4
560.IX Item "ev_loop_destroy (loop)" 574.IX Item "ev_loop_destroy (loop)"
561Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an 575Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an
562earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. 576earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR.
563.IP "ev_default_fork ()" 4 577.IP "ev_default_fork ()" 4
… …
634libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is 648libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is
635usually a better approach for this kind of thing. 649usually a better approach for this kind of thing.
636.Sp 650.Sp
637Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: 651Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does:
638.Sp 652.Sp
639.Vb 18 653.Vb 19
654\& - Before the first iteration, call any pending watchers.
640\& * If there are no active watchers (reference count is zero), return. 655\& * If there are no active watchers (reference count is zero), return.
641\& - Queue prepare watchers and then call all outstanding watchers. 656\& - Queue all prepare watchers and then call all outstanding watchers.
642\& - If we have been forked, recreate the kernel state. 657\& - If we have been forked, recreate the kernel state.
643\& - Update the kernel state with all outstanding changes. 658\& - Update the kernel state with all outstanding changes.
644\& - Update the "event loop time". 659\& - Update the "event loop time".
645\& - Calculate for how long to block. 660\& - Calculate for how long to block.
646\& - Block the process, waiting for any events. 661\& - Block the process, waiting for any events.
… …
889.IP "bool ev_is_pending (ev_TYPE *watcher)" 4 904.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
890.IX Item "bool ev_is_pending (ev_TYPE *watcher)" 905.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
891Returns a true value iff the watcher is pending, (i.e. it has outstanding 906Returns a true value iff the watcher is pending, (i.e. it has outstanding
892events but its callback has not yet been invoked). As long as a watcher 907events but its callback has not yet been invoked). As long as a watcher
893is pending (but not active) you must not call an init function on it (but 908is pending (but not active) you must not call an init function on it (but
894\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to 909\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must
895libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). 910make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR
911it).
896.IP "callback ev_cb (ev_TYPE *watcher)" 4 912.IP "callback ev_cb (ev_TYPE *watcher)" 4
897.IX Item "callback ev_cb (ev_TYPE *watcher)" 913.IX Item "callback ev_cb (ev_TYPE *watcher)"
898Returns the callback currently set on the watcher. 914Returns the callback currently set on the watcher.
899.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 915.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
900.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 916.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
… …
918watchers on the same event and make sure one is called first. 934watchers on the same event and make sure one is called first.
919.Sp 935.Sp
920If you need to suppress invocation when higher priority events are pending 936If you need to suppress invocation when higher priority events are pending
921you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. 937you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality.
922.Sp 938.Sp
939You \fImust not\fR change the priority of a watcher as long as it is active or
940pending.
941.Sp
923The default priority used by watchers when no priority has been set is 942The default priority used by watchers when no priority has been set is
924always \f(CW0\fR, which is supposed to not be too high and not be too low :). 943always \f(CW0\fR, which is supposed to not be too high and not be too low :).
925.Sp 944.Sp
926Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is 945Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is
927fine, as long as you do not mind that the priority value you query might 946fine, as long as you do not mind that the priority value you query might
928or might not have been adjusted to be within valid range. 947or might not have been adjusted to be within valid range.
948.IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4
949.IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)"
950Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither
951\&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback
952can deal with that fact.
953.IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4
954.IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)"
955If the watcher is pending, this function returns clears its pending status
956and returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the
957watcher isn't pending it does nothing and returns \f(CW0\fR.
929.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 958.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
930.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 959.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
931Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change 960Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change
932and read at any time, libev will completely ignore it. This can be used 961and read at any time, libev will completely ignore it. This can be used
933to associate arbitrary data with your watcher. If you need more data and 962to associate arbitrary data with your watcher. If you need more data and
… …
1047If you cannot run the fd in non-blocking mode (for example you should not 1076If you cannot run the fd in non-blocking mode (for example you should not
1048play around with an Xlib connection), then you have to seperately re-test 1077play around with an Xlib connection), then you have to seperately re-test
1049whether a file descriptor is really ready with a known-to-be good interface 1078whether a file descriptor is really ready with a known-to-be good interface
1050such as poll (fortunately in our Xlib example, Xlib already does this on 1079such as poll (fortunately in our Xlib example, Xlib already does this on
1051its own, so its quite safe to use). 1080its own, so its quite safe to use).
1081.PP
1082\fIThe special problem of disappearing file descriptors\fR
1083.IX Subsection "The special problem of disappearing file descriptors"
1084.PP
1085Some backends (e.g kqueue, epoll) need to be told about closing a file
1086descriptor (either by calling \f(CW\*(C`close\*(C'\fR explicitly or by any other means,
1087such as \f(CW\*(C`dup\*(C'\fR). The reason is that you register interest in some file
1088descriptor, but when it goes away, the operating system will silently drop
1089this interest. If another file descriptor with the same number then is
1090registered with libev, there is no efficient way to see that this is, in
1091fact, a different file descriptor.
1092.PP
1093To avoid having to explicitly tell libev about such cases, libev follows
1094the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev
1095will assume that this is potentially a new file descriptor, otherwise
1096it is assumed that the file descriptor stays the same. That means that
1097you \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
1098descriptor even if the file descriptor number itself did not change.
1099.PP
1100This is how one would do it normally anyway, the important point is that
1101the libev application should not optimise around libev but should leave
1102optimisations to libev.
1103.PP
1104\fIWatcher-Specific Functions\fR
1105.IX Subsection "Watcher-Specific Functions"
1052.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 1106.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
1053.IX Item "ev_io_init (ev_io *, callback, int fd, int events)" 1107.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
1054.PD 0 1108.PD 0
1055.IP "ev_io_set (ev_io *, int fd, int events)" 4 1109.IP "ev_io_set (ev_io *, int fd, int events)" 4
1056.IX Item "ev_io_set (ev_io *, int fd, int events)" 1110.IX Item "ev_io_set (ev_io *, int fd, int events)"
… …
1109.Ve 1163.Ve
1110.PP 1164.PP
1111The callback is guarenteed to be invoked only when its timeout has passed, 1165The callback is guarenteed to be invoked only when its timeout has passed,
1112but if multiple timers become ready during the same loop iteration then 1166but if multiple timers become ready during the same loop iteration then
1113order of execution is undefined. 1167order of execution is undefined.
1168.PP
1169\fIWatcher-Specific Functions and Data Members\fR
1170.IX Subsection "Watcher-Specific Functions and Data Members"
1114.IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 1171.IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4
1115.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 1172.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)"
1116.PD 0 1173.PD 0
1117.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 1174.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4
1118.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 1175.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)"
… …
1220but on wallclock time (absolute time). You can tell a periodic watcher 1277but on wallclock time (absolute time). You can tell a periodic watcher
1221to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a 1278to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a
1222periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () 1279periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now ()
1223+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will 1280+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will
1224take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger 1281take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger
1225roughly 10 seconds later and of course not if you reset your system time 1282roughly 10 seconds later).
1226again).
1227.PP 1283.PP
1228They can also be used to implement vastly more complex timers, such as 1284They can also be used to implement vastly more complex timers, such as
1229triggering an event on eahc midnight, local time. 1285triggering an event on each midnight, local time or other, complicated,
1286rules.
1230.PP 1287.PP
1231As with timers, the callback is guarenteed to be invoked only when the 1288As with timers, the callback is guarenteed to be invoked only when the
1232time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready 1289time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready
1233during the same loop iteration then order of execution is undefined. 1290during the same loop iteration then order of execution is undefined.
1291.PP
1292\fIWatcher-Specific Functions and Data Members\fR
1293.IX Subsection "Watcher-Specific Functions and Data Members"
1234.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 1294.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4
1235.IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 1295.IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)"
1236.PD 0 1296.PD 0
1237.IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 1297.IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4
1238.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 1298.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)"
1239.PD 1299.PD
1240Lots of arguments, lets sort it out... There are basically three modes of 1300Lots of arguments, lets sort it out... There are basically three modes of
1241operation, and we will explain them from simplest to complex: 1301operation, and we will explain them from simplest to complex:
1242.RS 4 1302.RS 4
1243.IP "* absolute timer (interval = reschedule_cb = 0)" 4 1303.IP "* absolute timer (at = time, interval = reschedule_cb = 0)" 4
1244.IX Item "absolute timer (interval = reschedule_cb = 0)" 1304.IX Item "absolute timer (at = time, interval = reschedule_cb = 0)"
1245In this configuration the watcher triggers an event at the wallclock time 1305In this configuration the watcher triggers an event at the wallclock time
1246\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, 1306\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs,
1247that is, if it is to be run at January 1st 2011 then it will run when the 1307that is, if it is to be run at January 1st 2011 then it will run when the
1248system time reaches or surpasses this time. 1308system time reaches or surpasses this time.
1249.IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4 1309.IP "* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" 4
1250.IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)" 1310.IX Item "non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)"
1251In this mode the watcher will always be scheduled to time out at the next 1311In this mode the watcher will always be scheduled to time out at the next
1252\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless 1312\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative)
1253of any time jumps. 1313and then repeat, regardless of any time jumps.
1254.Sp 1314.Sp
1255This can be used to create timers that do not drift with respect to system 1315This can be used to create timers that do not drift with respect to system
1256time: 1316time:
1257.Sp 1317.Sp
1258.Vb 1 1318.Vb 1
… …
1265by 3600. 1325by 3600.
1266.Sp 1326.Sp
1267Another way to think about it (for the mathematically inclined) is that 1327Another way to think about it (for the mathematically inclined) is that
1268\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible 1328\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible
1269time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. 1329time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps.
1330.Sp
1331For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near
1332\&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for
1333this value.
1270.IP "* manual reschedule mode (reschedule_cb = callback)" 4 1334.IP "* manual reschedule mode (at and interval ignored, reschedule_cb = callback)" 4
1271.IX Item "manual reschedule mode (reschedule_cb = callback)" 1335.IX Item "manual reschedule mode (at and interval ignored, reschedule_cb = callback)"
1272In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being 1336In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being
1273ignored. Instead, each time the periodic watcher gets scheduled, the 1337ignored. Instead, each time the periodic watcher gets scheduled, the
1274reschedule callback will be called with the watcher as first, and the 1338reschedule callback will be called with the watcher as first, and the
1275current time as second argument. 1339current time as second argument.
1276.Sp 1340.Sp
1277\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, 1341\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher,
1278ever, or make any event loop modifications\fR. If you need to stop it, 1342ever, or make any event loop modifications\fR. If you need to stop it,
1279return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by 1343return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by
1280starting a prepare watcher). 1344starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal).
1281.Sp 1345.Sp
1282Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, 1346Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
1283ev_tstamp now)\*(C'\fR, e.g.: 1347ev_tstamp now)\*(C'\fR, e.g.:
1284.Sp 1348.Sp
1285.Vb 4 1349.Vb 4
… …
1309.IX Item "ev_periodic_again (loop, ev_periodic *)" 1373.IX Item "ev_periodic_again (loop, ev_periodic *)"
1310Simply stops and restarts the periodic watcher again. This is only useful 1374Simply stops and restarts the periodic watcher again. This is only useful
1311when you changed some parameters or the reschedule callback would return 1375when you changed some parameters or the reschedule callback would return
1312a different time than the last time it was called (e.g. in a crond like 1376a different time than the last time it was called (e.g. in a crond like
1313program when the crontabs have changed). 1377program when the crontabs have changed).
1378.IP "ev_tstamp offset [read\-write]" 4
1379.IX Item "ev_tstamp offset [read-write]"
1380When repeating, this contains the offset value, otherwise this is the
1381absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR).
1382.Sp
1383Can be modified any time, but changes only take effect when the periodic
1384timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1314.IP "ev_tstamp interval [read\-write]" 4 1385.IP "ev_tstamp interval [read\-write]" 4
1315.IX Item "ev_tstamp interval [read-write]" 1386.IX Item "ev_tstamp interval [read-write]"
1316The current interval value. Can be modified any time, but changes only 1387The current interval value. Can be modified any time, but changes only
1317take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being 1388take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being
1318called. 1389called.
1319.IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4 1390.IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4
1320.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" 1391.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]"
1321The current reschedule callback, or \f(CW0\fR, if this functionality is 1392The current reschedule callback, or \f(CW0\fR, if this functionality is
1322switched off. Can be changed any time, but changes only take effect when 1393switched off. Can be changed any time, but changes only take effect when
1323the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. 1394the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1395.IP "ev_tstamp at [read\-only]" 4
1396.IX Item "ev_tstamp at [read-only]"
1397When active, contains the absolute time that the watcher is supposed to
1398trigger next.
1324.PP 1399.PP
1325Example: Call a callback every hour, or, more precisely, whenever the 1400Example: Call a callback every hour, or, more precisely, whenever the
1326system clock is divisible by 3600. The callback invocation times have 1401system clock is divisible by 3600. The callback invocation times have
1327potentially a lot of jittering, but good long-term stability. 1402potentially a lot of jittering, but good long-term stability.
1328.PP 1403.PP
… …
1378first watcher gets started will libev actually register a signal watcher 1453first watcher gets started will libev actually register a signal watcher
1379with the kernel (thus it coexists with your own signal handlers as long 1454with the kernel (thus it coexists with your own signal handlers as long
1380as you don't register any with libev). Similarly, when the last signal 1455as you don't register any with libev). Similarly, when the last signal
1381watcher for a signal is stopped libev will reset the signal handler to 1456watcher for a signal is stopped libev will reset the signal handler to
1382\&\s-1SIG_DFL\s0 (regardless of what it was set to before). 1457\&\s-1SIG_DFL\s0 (regardless of what it was set to before).
1458.PP
1459\fIWatcher-Specific Functions and Data Members\fR
1460.IX Subsection "Watcher-Specific Functions and Data Members"
1383.IP "ev_signal_init (ev_signal *, callback, int signum)" 4 1461.IP "ev_signal_init (ev_signal *, callback, int signum)" 4
1384.IX Item "ev_signal_init (ev_signal *, callback, int signum)" 1462.IX Item "ev_signal_init (ev_signal *, callback, int signum)"
1385.PD 0 1463.PD 0
1386.IP "ev_signal_set (ev_signal *, int signum)" 4 1464.IP "ev_signal_set (ev_signal *, int signum)" 4
1387.IX Item "ev_signal_set (ev_signal *, int signum)" 1465.IX Item "ev_signal_set (ev_signal *, int signum)"
… …
1394.ie n .Sh """ev_child"" \- watch out for process status changes" 1472.ie n .Sh """ev_child"" \- watch out for process status changes"
1395.el .Sh "\f(CWev_child\fP \- watch out for process status changes" 1473.el .Sh "\f(CWev_child\fP \- watch out for process status changes"
1396.IX Subsection "ev_child - watch out for process status changes" 1474.IX Subsection "ev_child - watch out for process status changes"
1397Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to 1475Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to
1398some child status changes (most typically when a child of yours dies). 1476some child status changes (most typically when a child of yours dies).
1477.PP
1478\fIWatcher-Specific Functions and Data Members\fR
1479.IX Subsection "Watcher-Specific Functions and Data Members"
1399.IP "ev_child_init (ev_child *, callback, int pid)" 4 1480.IP "ev_child_init (ev_child *, callback, int pid)" 4
1400.IX Item "ev_child_init (ev_child *, callback, int pid)" 1481.IX Item "ev_child_init (ev_child *, callback, int pid)"
1401.PD 0 1482.PD 0
1402.IP "ev_child_set (ev_child *, int pid)" 4 1483.IP "ev_child_set (ev_child *, int pid)" 4
1403.IX Item "ev_child_set (ev_child *, int pid)" 1484.IX Item "ev_child_set (ev_child *, int pid)"
… …
1468reader). Inotify will be used to give hints only and should not change the 1549reader). Inotify will be used to give hints only and should not change the
1469semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs 1550semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs
1470to fall back to regular polling again even with inotify, but changes are 1551to fall back to regular polling again even with inotify, but changes are
1471usually detected immediately, and if the file exists there will be no 1552usually detected immediately, and if the file exists there will be no
1472polling. 1553polling.
1554.PP
1555\fIWatcher-Specific Functions and Data Members\fR
1556.IX Subsection "Watcher-Specific Functions and Data Members"
1473.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 1557.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
1474.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 1558.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
1475.PD 0 1559.PD 0
1476.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 1560.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4
1477.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 1561.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
… …
1556.PP 1640.PP
1557Apart from keeping your process non-blocking (which is a useful 1641Apart from keeping your process non-blocking (which is a useful
1558effect on its own sometimes), idle watchers are a good place to do 1642effect on its own sometimes), idle watchers are a good place to do
1559\&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the 1643\&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the
1560event loop has handled all outstanding events. 1644event loop has handled all outstanding events.
1645.PP
1646\fIWatcher-Specific Functions and Data Members\fR
1647.IX Subsection "Watcher-Specific Functions and Data Members"
1561.IP "ev_idle_init (ev_signal *, callback)" 4 1648.IP "ev_idle_init (ev_signal *, callback)" 4
1562.IX Item "ev_idle_init (ev_signal *, callback)" 1649.IX Item "ev_idle_init (ev_signal *, callback)"
1563Initialises and configures the idle watcher \- it has no parameters of any 1650Initialises and configures the idle watcher \- it has no parameters of any
1564kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, 1651kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,
1565believe me. 1652believe me.
… …
1620are ready to run (it's actually more complicated: it only runs coroutines 1707are ready to run (it's actually more complicated: it only runs coroutines
1621with priority higher than or equal to the event loop and one coroutine 1708with priority higher than or equal to the event loop and one coroutine
1622of lower priority, but only once, using idle watchers to keep the event 1709of lower priority, but only once, using idle watchers to keep the event
1623loop from blocking if lower-priority coroutines are active, thus mapping 1710loop from blocking if lower-priority coroutines are active, thus mapping
1624low-priority coroutines to idle/background tasks). 1711low-priority coroutines to idle/background tasks).
1712.PP
1713It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR)
1714priority, to ensure that they are being run before any other watchers
1715after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers,
1716too) should not activate (\*(L"feed\*(R") events into libev. While libev fully
1717supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers did
1718their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other event
1719loops those other event loops might be in an unusable state until their
1720\&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with
1721others).
1722.PP
1723\fIWatcher-Specific Functions and Data Members\fR
1724.IX Subsection "Watcher-Specific Functions and Data Members"
1625.IP "ev_prepare_init (ev_prepare *, callback)" 4 1725.IP "ev_prepare_init (ev_prepare *, callback)" 4
1626.IX Item "ev_prepare_init (ev_prepare *, callback)" 1726.IX Item "ev_prepare_init (ev_prepare *, callback)"
1627.PD 0 1727.PD 0
1628.IP "ev_check_init (ev_check *, callback)" 4 1728.IP "ev_check_init (ev_check *, callback)" 4
1629.IX Item "ev_check_init (ev_check *, callback)" 1729.IX Item "ev_check_init (ev_check *, callback)"
1630.PD 1730.PD
1631Initialises and configures the prepare or check watcher \- they have no 1731Initialises and configures the prepare or check watcher \- they have no
1632parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR 1732parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR
1633macros, but using them is utterly, utterly and completely pointless. 1733macros, but using them is utterly, utterly and completely pointless.
1634.PP 1734.PP
1635Example: To include a library such as adns, you would add \s-1IO\s0 watchers 1735There are a number of principal ways to embed other event loops or modules
1636and a timeout watcher in a prepare handler, as required by libadns, and 1736into libev. Here are some ideas on how to include libadns into libev
1737(there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could
1738use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR
1739embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0
1740into the Glib event loop).
1741.PP
1742Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler,
1637in a check watcher, destroy them and call into libadns. What follows is 1743and in a check watcher, destroy them and call into libadns. What follows
1638pseudo-code only of course: 1744is pseudo-code only of course. This requires you to either use a low
1745priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as
1746the callbacks for the IO/timeout watchers might not have been called yet.
1639.PP 1747.PP
1640.Vb 2 1748.Vb 2
1641\& static ev_io iow [nfd]; 1749\& static ev_io iow [nfd];
1642\& static ev_timer tw; 1750\& static ev_timer tw;
1643.Ve 1751.Ve
1644.PP 1752.PP
1645.Vb 9 1753.Vb 4
1646\& static void 1754\& static void
1647\& io_cb (ev_loop *loop, ev_io *w, int revents) 1755\& io_cb (ev_loop *loop, ev_io *w, int revents)
1648\& { 1756\& {
1649\& // set the relevant poll flags
1650\& // could also call adns_processreadable etc. here
1651\& struct pollfd *fd = (struct pollfd *)w->data;
1652\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1653\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1654\& } 1757\& }
1655.Ve 1758.Ve
1656.PP 1759.PP
1657.Vb 8 1760.Vb 8
1658\& // create io watchers for each fd and a timer before blocking 1761\& // create io watchers for each fd and a timer before blocking
… …
1670\& ev_timer_init (&tw, 0, timeout * 1e-3); 1773\& ev_timer_init (&tw, 0, timeout * 1e-3);
1671\& ev_timer_start (loop, &tw); 1774\& ev_timer_start (loop, &tw);
1672.Ve 1775.Ve
1673.PP 1776.PP
1674.Vb 6 1777.Vb 6
1675\& // create on ev_io per pollfd 1778\& // create one ev_io per pollfd
1676\& for (int i = 0; i < nfd; ++i) 1779\& for (int i = 0; i < nfd; ++i)
1677\& { 1780\& {
1678\& ev_io_init (iow + i, io_cb, fds [i].fd, 1781\& ev_io_init (iow + i, io_cb, fds [i].fd,
1679\& ((fds [i].events & POLLIN ? EV_READ : 0) 1782\& ((fds [i].events & POLLIN ? EV_READ : 0)
1680\& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); 1783\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1681.Ve 1784.Ve
1682.PP 1785.PP
1683.Vb 5 1786.Vb 4
1684\& fds [i].revents = 0; 1787\& fds [i].revents = 0;
1685\& iow [i].data = fds + i;
1686\& ev_io_start (loop, iow + i); 1788\& ev_io_start (loop, iow + i);
1687\& } 1789\& }
1688\& } 1790\& }
1689.Ve 1791.Ve
1690.PP 1792.PP
… …
1694\& adns_check_cb (ev_loop *loop, ev_check *w, int revents) 1796\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1695\& { 1797\& {
1696\& ev_timer_stop (loop, &tw); 1798\& ev_timer_stop (loop, &tw);
1697.Ve 1799.Ve
1698.PP 1800.PP
1699.Vb 2 1801.Vb 8
1700\& for (int i = 0; i < nfd; ++i) 1802\& for (int i = 0; i < nfd; ++i)
1803\& {
1804\& // set the relevant poll flags
1805\& // could also call adns_processreadable etc. here
1806\& struct pollfd *fd = fds + i;
1807\& int revents = ev_clear_pending (iow + i);
1808\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1809\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1810.Ve
1811.PP
1812.Vb 3
1813\& // now stop the watcher
1701\& ev_io_stop (loop, iow + i); 1814\& ev_io_stop (loop, iow + i);
1815\& }
1702.Ve 1816.Ve
1703.PP 1817.PP
1704.Vb 2 1818.Vb 2
1705\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); 1819\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1820\& }
1821.Ve
1822.PP
1823Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR
1824in the prepare watcher and would dispose of the check watcher.
1825.PP
1826Method 3: If the module to be embedded supports explicit event
1827notification (adns does), you can also make use of the actual watcher
1828callbacks, and only destroy/create the watchers in the prepare watcher.
1829.PP
1830.Vb 5
1831\& static void
1832\& timer_cb (EV_P_ ev_timer *w, int revents)
1833\& {
1834\& adns_state ads = (adns_state)w->data;
1835\& update_now (EV_A);
1836.Ve
1837.PP
1838.Vb 2
1839\& adns_processtimeouts (ads, &tv_now);
1840\& }
1841.Ve
1842.PP
1843.Vb 5
1844\& static void
1845\& io_cb (EV_P_ ev_io *w, int revents)
1846\& {
1847\& adns_state ads = (adns_state)w->data;
1848\& update_now (EV_A);
1849.Ve
1850.PP
1851.Vb 3
1852\& if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1853\& if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1854\& }
1855.Ve
1856.PP
1857.Vb 1
1858\& // do not ever call adns_afterpoll
1859.Ve
1860.PP
1861Method 4: Do not use a prepare or check watcher because the module you
1862want to embed is too inflexible to support it. Instead, youc na override
1863their poll function. The drawback with this solution is that the main
1864loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does
1865this.
1866.PP
1867.Vb 4
1868\& static gint
1869\& event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1870\& {
1871\& int got_events = 0;
1872.Ve
1873.PP
1874.Vb 2
1875\& for (n = 0; n < nfds; ++n)
1876\& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1877.Ve
1878.PP
1879.Vb 2
1880\& if (timeout >= 0)
1881\& // create/start timer
1882.Ve
1883.PP
1884.Vb 2
1885\& // poll
1886\& ev_loop (EV_A_ 0);
1887.Ve
1888.PP
1889.Vb 3
1890\& // stop timer again
1891\& if (timeout >= 0)
1892\& ev_timer_stop (EV_A_ &to);
1893.Ve
1894.PP
1895.Vb 3
1896\& // stop io watchers again - their callbacks should have set
1897\& for (n = 0; n < nfds; ++n)
1898\& ev_io_stop (EV_A_ iow [n]);
1899.Ve
1900.PP
1901.Vb 2
1902\& return got_events;
1706\& } 1903\& }
1707.Ve 1904.Ve
1708.ie n .Sh """ev_embed"" \- when one backend isn't enough..." 1905.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1709.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." 1906.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
1710.IX Subsection "ev_embed - when one backend isn't enough..." 1907.IX Subsection "ev_embed - when one backend isn't enough..."
… …
1779\& ev_embed_start (loop_hi, &embed); 1976\& ev_embed_start (loop_hi, &embed);
1780\& } 1977\& }
1781\& else 1978\& else
1782\& loop_lo = loop_hi; 1979\& loop_lo = loop_hi;
1783.Ve 1980.Ve
1981.PP
1982\fIWatcher-Specific Functions and Data Members\fR
1983.IX Subsection "Watcher-Specific Functions and Data Members"
1784.IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 1984.IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
1785.IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 1985.IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)"
1786.PD 0 1986.PD 0
1787.IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 1987.IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
1788.IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 1988.IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)"
… …
1808\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the 2008\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the
1809event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, 2009event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called,
1810and only in the child after the fork. If whoever good citizen calling 2010and only in the child after the fork. If whoever good citizen calling
1811\&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork 2011\&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork
1812handlers will be invoked, too, of course. 2012handlers will be invoked, too, of course.
2013.PP
2014\fIWatcher-Specific Functions and Data Members\fR
2015.IX Subsection "Watcher-Specific Functions and Data Members"
1813.IP "ev_fork_init (ev_signal *, callback)" 4 2016.IP "ev_fork_init (ev_signal *, callback)" 4
1814.IX Item "ev_fork_init (ev_signal *, callback)" 2017.IX Item "ev_fork_init (ev_signal *, callback)"
1815Initialises and configures the fork watcher \- it has no parameters of any 2018Initialises and configures the fork watcher \- it has no parameters of any
1816kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, 2019kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless,
1817believe me. 2020believe me.
… …
1894.PP 2097.PP
1895.Vb 1 2098.Vb 1
1896\& #include <ev++.h> 2099\& #include <ev++.h>
1897.Ve 2100.Ve
1898.PP 2101.PP
1899(it is not installed by default). This automatically includes \fIev.h\fR 2102This automatically includes \fIev.h\fR and puts all of its definitions (many
1900and puts all of its definitions (many of them macros) into the global 2103of them macros) into the global namespace. All \*(C+ specific things are
1901namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace. 2104put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding
2105options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
1902.PP 2106.PP
1903It should support all the same embedding options as \fIev.h\fR, most notably 2107Care has been taken to keep the overhead low. The only data member the \*(C+
1904\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. 2108classes add (compared to plain C\-style watchers) is the event loop pointer
2109that the watcher is associated with (or no additional members at all if
2110you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev).
2111.PP
2112Currently, functions, and static and non-static member functions can be
2113used as callbacks. Other types should be easy to add as long as they only
2114need one additional pointer for context. If you need support for other
2115types of functors please contact the author (preferably after implementing
2116it).
1905.PP 2117.PP
1906Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: 2118Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
1907.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 2119.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
1908.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 2120.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
1909.IX Item "ev::READ, ev::WRITE etc." 2121.IX Item "ev::READ, ev::WRITE etc."
… …
1921which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro 2133which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
1922defines by many implementations. 2134defines by many implementations.
1923.Sp 2135.Sp
1924All of those classes have these methods: 2136All of those classes have these methods:
1925.RS 4 2137.RS 4
1926.IP "ev::TYPE::TYPE (object *, object::method *)" 4 2138.IP "ev::TYPE::TYPE ()" 4
1927.IX Item "ev::TYPE::TYPE (object *, object::method *)" 2139.IX Item "ev::TYPE::TYPE ()"
1928.PD 0 2140.PD 0
1929.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 2141.IP "ev::TYPE::TYPE (struct ev_loop *)" 4
1930.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 2142.IX Item "ev::TYPE::TYPE (struct ev_loop *)"
1931.IP "ev::TYPE::~TYPE" 4 2143.IP "ev::TYPE::~TYPE" 4
1932.IX Item "ev::TYPE::~TYPE" 2144.IX Item "ev::TYPE::~TYPE"
1933.PD 2145.PD
1934The constructor takes a pointer to an object and a method pointer to 2146The constructor (optionally) takes an event loop to associate the watcher
1935the event handler callback to call in this class. The constructor calls 2147with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR.
1936\&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method 2148.Sp
1937before starting it. If you do not specify a loop then the constructor 2149The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the
1938automatically associates the default loop with this watcher. 2150\&\f(CW\*(C`set\*(C'\fR method before starting it.
2151.Sp
2152It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR
2153method to set a callback before you can start the watcher.
2154.Sp
2155(The reason why you have to use a method is a limitation in \*(C+ which does
2156not allow explicit template arguments for constructors).
1939.Sp 2157.Sp
1940The destructor automatically stops the watcher if it is active. 2158The destructor automatically stops the watcher if it is active.
2159.IP "w\->set<class, &class::method> (object *)" 4
2160.IX Item "w->set<class, &class::method> (object *)"
2161This method sets the callback method to call. The method has to have a
2162signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as
2163first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as
2164parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher.
2165.Sp
2166This method synthesizes efficient thunking code to call your method from
2167the C callback that libev requires. If your compiler can inline your
2168callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and
2169your compiler is good :), then the method will be fully inlined into the
2170thunking function, making it as fast as a direct C callback.
2171.Sp
2172Example: simple class declaration and watcher initialisation
2173.Sp
2174.Vb 4
2175\& struct myclass
2176\& {
2177\& void io_cb (ev::io &w, int revents) { }
2178\& }
2179.Ve
2180.Sp
2181.Vb 3
2182\& myclass obj;
2183\& ev::io iow;
2184\& iow.set <myclass, &myclass::io_cb> (&obj);
2185.Ve
2186.IP "w\->set<function> (void *data = 0)" 4
2187.IX Item "w->set<function> (void *data = 0)"
2188Also sets a callback, but uses a static method or plain function as
2189callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's
2190\&\f(CW\*(C`data\*(C'\fR member and is free for you to use.
2191.Sp
2192The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR.
2193.Sp
2194See the method\-\f(CW\*(C`set\*(C'\fR above for more details.
2195.Sp
2196Example:
2197.Sp
2198.Vb 2
2199\& static void io_cb (ev::io &w, int revents) { }
2200\& iow.set <io_cb> ();
2201.Ve
1941.IP "w\->set (struct ev_loop *)" 4 2202.IP "w\->set (struct ev_loop *)" 4
1942.IX Item "w->set (struct ev_loop *)" 2203.IX Item "w->set (struct ev_loop *)"
1943Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only 2204Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
1944do this when the watcher is inactive (and not pending either). 2205do this when the watcher is inactive (and not pending either).
1945.IP "w\->set ([args])" 4 2206.IP "w\->set ([args])" 4
1946.IX Item "w->set ([args])" 2207.IX Item "w->set ([args])"
1947Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be 2208Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be
1948called at least once. Unlike the C counterpart, an active watcher gets 2209called at least once. Unlike the C counterpart, an active watcher gets
1949automatically stopped and restarted. 2210automatically stopped and restarted when reconfiguring it with this
2211method.
1950.IP "w\->start ()" 4 2212.IP "w\->start ()" 4
1951.IX Item "w->start ()" 2213.IX Item "w->start ()"
1952Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the 2214Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
1953constructor already takes the loop. 2215constructor already stores the event loop.
1954.IP "w\->stop ()" 4 2216.IP "w\->stop ()" 4
1955.IX Item "w->stop ()" 2217.IX Item "w->stop ()"
1956Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. 2218Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
1957.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4 2219.ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4
1958.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4 2220.el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4
1959.IX Item "w->again () ev::timer, ev::periodic only" 2221.IX Item "w->again () (ev::timer, ev::periodic only)"
1960For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding 2222For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding
1961\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. 2223\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function.
1962.ie n .IP "w\->sweep () ""ev::embed"" only" 4 2224.ie n .IP "w\->sweep () (""ev::embed"" only)" 4
1963.el .IP "w\->sweep () \f(CWev::embed\fR only" 4 2225.el .IP "w\->sweep () (\f(CWev::embed\fR only)" 4
1964.IX Item "w->sweep () ev::embed only" 2226.IX Item "w->sweep () (ev::embed only)"
1965Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. 2227Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR.
1966.ie n .IP "w\->update () ""ev::stat"" only" 4 2228.ie n .IP "w\->update () (""ev::stat"" only)" 4
1967.el .IP "w\->update () \f(CWev::stat\fR only" 4 2229.el .IP "w\->update () (\f(CWev::stat\fR only)" 4
1968.IX Item "w->update () ev::stat only" 2230.IX Item "w->update () (ev::stat only)"
1969Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. 2231Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR.
1970.RE 2232.RE
1971.RS 4 2233.RS 4
1972.RE 2234.RE
1973.PP 2235.PP
… …
1984.Vb 2 2246.Vb 2
1985\& myclass (); 2247\& myclass ();
1986\& } 2248\& }
1987.Ve 2249.Ve
1988.PP 2250.PP
1989.Vb 6 2251.Vb 4
1990\& myclass::myclass (int fd) 2252\& myclass::myclass (int fd)
1991\& : io (this, &myclass::io_cb),
1992\& idle (this, &myclass::idle_cb)
1993\& { 2253\& {
2254\& io .set <myclass, &myclass::io_cb > (this);
2255\& idle.set <myclass, &myclass::idle_cb> (this);
2256.Ve
2257.PP
2258.Vb 2
1994\& io.start (fd, ev::READ); 2259\& io.start (fd, ev::READ);
1995\& } 2260\& }
1996.Ve 2261.Ve
1997.SH "MACRO MAGIC" 2262.SH "MACRO MAGIC"
1998.IX Header "MACRO MAGIC" 2263.IX Header "MACRO MAGIC"
1999Libev can be compiled with a variety of options, the most fundemantal is 2264Libev can be compiled with a variety of options, the most fundamantal
2000\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) functions and 2265of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most)
2001callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. 2266functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
2002.PP 2267.PP
2003To make it easier to write programs that cope with either variant, the 2268To make it easier to write programs that cope with either variant, the
2004following macros are defined: 2269following macros are defined:
2005.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 2270.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
2006.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 2271.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4
… …
2364and the way callbacks are invoked and set. Must expand to a struct member 2629and the way callbacks are invoked and set. Must expand to a struct member
2365definition and a statement, respectively. See the \fIev.v\fR header file for 2630definition and a statement, respectively. See the \fIev.v\fR header file for
2366their default definitions. One possible use for overriding these is to 2631their default definitions. One possible use for overriding these is to
2367avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use 2632avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
2368method calls instead of plain function calls in \*(C+. 2633method calls instead of plain function calls in \*(C+.
2634.Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0"
2635.IX Subsection "EXPORTED API SYMBOLS"
2636If you need to re-export the \s-1API\s0 (e.g. via a dll) and you need a list of
2637exported symbols, you can use the provided \fISymbol.*\fR files which list
2638all public symbols, one per line:
2639.Sp
2640.Vb 2
2641\& Symbols.ev for libev proper
2642\& Symbols.event for the libevent emulation
2643.Ve
2644.Sp
2645This can also be used to rename all public symbols to avoid clashes with
2646multiple versions of libev linked together (which is obviously bad in
2647itself, but sometimes it is inconvinient to avoid this).
2648.Sp
2649A sed comamnd like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to
2650include before including \fIev.h\fR:
2651.Sp
2652.Vb 1
2653\& <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
2654.Ve
2655.Sp
2656This would create a file \fIwrap.h\fR which essentially looks like this:
2657.Sp
2658.Vb 4
2659\& #define ev_backend myprefix_ev_backend
2660\& #define ev_check_start myprefix_ev_check_start
2661\& #define ev_check_stop myprefix_ev_check_stop
2662\& ...
2663.Ve
2369.Sh "\s-1EXAMPLES\s0" 2664.Sh "\s-1EXAMPLES\s0"
2370.IX Subsection "EXAMPLES" 2665.IX Subsection "EXAMPLES"
2371For a real-world example of a program the includes libev 2666For a real-world example of a program the includes libev
2372verbatim, you can have a look at the \s-1EV\s0 perl module 2667verbatim, you can have a look at the \s-1EV\s0 perl module
2373(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in 2668(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in

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