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Revision 1.35 by root, Thu Nov 29 17:28:13 2007 UTC vs.
Revision 1.52 by root, Wed Dec 19 00:56:39 2007 UTC

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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 "2007-11-29" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH EV 1 "2007-12-18" "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
… …
239Libev represents time as a single floating point number, representing the 243Libev represents time as a single floating point number, representing the
240(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
241the 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
242called \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
243to 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
244it, 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.
245.SH "GLOBAL FUNCTIONS" 251.SH "GLOBAL FUNCTIONS"
246.IX Header "GLOBAL FUNCTIONS" 252.IX Header "GLOBAL FUNCTIONS"
247These functions can be called anytime, even before initialising the 253These functions can be called anytime, even before initialising the
248library in any way. 254library in any way.
249.IP "ev_tstamp ev_time ()" 4 255.IP "ev_tstamp ev_time ()" 4
… …
255.IX Item "int ev_version_major ()" 261.IX Item "int ev_version_major ()"
256.PD 0 262.PD 0
257.IP "int ev_version_minor ()" 4 263.IP "int ev_version_minor ()" 4
258.IX Item "int ev_version_minor ()" 264.IX Item "int ev_version_minor ()"
259.PD 265.PD
260You 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
261you 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
262\&\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
263symbols \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
264version of the library your program was compiled against. 270version of the library your program was compiled against.
265.Sp 271.Sp
272These version numbers refer to the \s-1ABI\s0 version of the library, not the
273release version.
274.Sp
266Usually, 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,
267as this indicates an incompatible change. Minor versions are usually 276as this indicates an incompatible change. Minor versions are usually
268compatible to older versions, so a larger minor version alone is usually 277compatible to older versions, so a larger minor version alone is usually
269not a problem. 278not a problem.
270.Sp 279.Sp
271Example: Make sure we haven't accidentally been linked against the wrong 280Example: Make sure we haven't accidentally been linked against the wrong
272version. 281version.
… …
420a fork, you can also make libev check for a fork in each iteration by 429a fork, you can also make libev check for a fork in each iteration by
421enabling this flag. 430enabling this flag.
422.Sp 431.Sp
423This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, 432This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop,
424and thus this might slow down your event loop if you do a lot of loop 433and thus this might slow down your event loop if you do a lot of loop
425iterations and little real work, but is usually not noticable (on my 434iterations and little real work, but is usually not noticeable (on my
426Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence 435Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence
427without a syscall and thus \fIvery\fR fast, but my Linux system also has 436without a syscall and thus \fIvery\fR fast, but my Linux system also has
428\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). 437\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster).
429.Sp 438.Sp
430The big advantage of this flag is that you can forget about fork (and 439The big advantage of this flag is that you can forget about fork (and
… …
548Destroys the default loop again (frees all memory and kernel state 557Destroys the default loop again (frees all memory and kernel state
549etc.). 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
550sense, 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
551responsibility to either stop all watchers cleanly yoursef \fIbefore\fR 560responsibility to either stop all watchers cleanly yoursef \fIbefore\fR
552calling this function, or cope with the fact afterwards (which is usually 561calling this function, or cope with the fact afterwards (which is usually
553the 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
554for 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).
555.IP "ev_loop_destroy (loop)" 4 573.IP "ev_loop_destroy (loop)" 4
556.IX Item "ev_loop_destroy (loop)" 574.IX Item "ev_loop_destroy (loop)"
557Like \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
558earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. 576earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR.
559.IP "ev_default_fork ()" 4 577.IP "ev_default_fork ()" 4
… …
581.IP "ev_loop_fork (loop)" 4 599.IP "ev_loop_fork (loop)" 4
582.IX Item "ev_loop_fork (loop)" 600.IX Item "ev_loop_fork (loop)"
583Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by 601Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by
584\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop 602\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop
585after fork, and how you do this is entirely your own problem. 603after fork, and how you do this is entirely your own problem.
604.IP "unsigned int ev_loop_count (loop)" 4
605.IX Item "unsigned int ev_loop_count (loop)"
606Returns the count of loop iterations for the loop, which is identical to
607the number of times libev did poll for new events. It starts at \f(CW0\fR and
608happily wraps around with enough iterations.
609.Sp
610This value can sometimes be useful as a generation counter of sorts (it
611\&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with
612\&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls.
586.IP "unsigned int ev_backend (loop)" 4 613.IP "unsigned int ev_backend (loop)" 4
587.IX Item "unsigned int ev_backend (loop)" 614.IX Item "unsigned int ev_backend (loop)"
588Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in 615Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
589use. 616use.
590.IP "ev_tstamp ev_now (loop)" 4 617.IP "ev_tstamp ev_now (loop)" 4
… …
621libev 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
622usually a better approach for this kind of thing. 649usually a better approach for this kind of thing.
623.Sp 650.Sp
624Here 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:
625.Sp 652.Sp
626.Vb 18 653.Vb 19
654\& - Before the first iteration, call any pending watchers.
627\& * If there are no active watchers (reference count is zero), return. 655\& * If there are no active watchers (reference count is zero), return.
628\& - Queue prepare watchers and then call all outstanding watchers. 656\& - Queue all prepare watchers and then call all outstanding watchers.
629\& - If we have been forked, recreate the kernel state. 657\& - If we have been forked, recreate the kernel state.
630\& - Update the kernel state with all outstanding changes. 658\& - Update the kernel state with all outstanding changes.
631\& - Update the "event loop time". 659\& - Update the "event loop time".
632\& - Calculate for how long to block. 660\& - Calculate for how long to block.
633\& - Block the process, waiting for any events. 661\& - Block the process, waiting for any events.
… …
876.IP "bool ev_is_pending (ev_TYPE *watcher)" 4 904.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
877.IX Item "bool ev_is_pending (ev_TYPE *watcher)" 905.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
878Returns 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
879events 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
880is 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
881\&\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
882libev (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).
883.IP "callback ev_cb (ev_TYPE *watcher)" 4 912.IP "callback ev_cb (ev_TYPE *watcher)" 4
884.IX Item "callback ev_cb (ev_TYPE *watcher)" 913.IX Item "callback ev_cb (ev_TYPE *watcher)"
885Returns the callback currently set on the watcher. 914Returns the callback currently set on the watcher.
886.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 915.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
887.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 916.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
888Change the callback. You can change the callback at virtually any time 917Change the callback. You can change the callback at virtually any time
889(modulo threads). 918(modulo threads).
919.IP "ev_set_priority (ev_TYPE *watcher, priority)" 4
920.IX Item "ev_set_priority (ev_TYPE *watcher, priority)"
921.PD 0
922.IP "int ev_priority (ev_TYPE *watcher)" 4
923.IX Item "int ev_priority (ev_TYPE *watcher)"
924.PD
925Set and query the priority of the watcher. The priority is a small
926integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR
927(default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked
928before watchers with lower priority, but priority will not keep watchers
929from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers).
930.Sp
931This means that priorities are \fIonly\fR used for ordering callback
932invocation after new events have been received. This is useful, for
933example, to reduce latency after idling, or more often, to bind two
934watchers on the same event and make sure one is called first.
935.Sp
936If you need to suppress invocation when higher priority events are pending
937you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality.
938.Sp
939You \fImust not\fR change the priority of a watcher as long as it is active or
940pending.
941.Sp
942The default priority used by watchers when no priority has been set is
943always \f(CW0\fR, which is supposed to not be too high and not be too low :).
944.Sp
945Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is
946fine, as long as you do not mind that the priority value you query might
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.
890.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"
891.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 959.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
892Each 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
893and 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
894to 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
… …
1005it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning 1073it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning
1006\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. 1074\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
1007.PP 1075.PP
1008If 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
1009play 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
1010wether 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
1011such 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
1012its 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"
1013.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
1014.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)"
1015.PD 0 1108.PD 0
1016.IP "ev_io_set (ev_io *, int fd, int events)" 4 1109.IP "ev_io_set (ev_io *, int fd, int events)" 4
1017.IX Item "ev_io_set (ev_io *, int fd, int events)" 1110.IX Item "ev_io_set (ev_io *, int fd, int events)"
… …
1070.Ve 1163.Ve
1071.PP 1164.PP
1072The 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,
1073but if multiple timers become ready during the same loop iteration then 1166but if multiple timers become ready during the same loop iteration then
1074order 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"
1075.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
1076.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)"
1077.PD 0 1173.PD 0
1078.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
1079.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)"
… …
1181but on wallclock time (absolute time). You can tell a periodic watcher 1277but on wallclock time (absolute time). You can tell a periodic watcher
1182to 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
1183periodic 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 ()
1184+ 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
1185take 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
1186roughly 10 seconds later and of course not if you reset your system time 1282roughly 10 seconds later).
1187again).
1188.PP 1283.PP
1189They 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
1190triggering an event on eahc midnight, local time. 1285triggering an event on each midnight, local time or other, complicated,
1286rules.
1191.PP 1287.PP
1192As 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
1193time (\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
1194during 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"
1195.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
1196.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)"
1197.PD 0 1296.PD 0
1198.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
1199.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)"
1200.PD 1299.PD
1201Lots 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
1202operation, and we will explain them from simplest to complex: 1301operation, and we will explain them from simplest to complex:
1203.RS 4 1302.RS 4
1204.IP "* absolute timer (interval = reschedule_cb = 0)" 4 1303.IP "* absolute timer (at = time, interval = reschedule_cb = 0)" 4
1205.IX Item "absolute timer (interval = reschedule_cb = 0)" 1304.IX Item "absolute timer (at = time, interval = reschedule_cb = 0)"
1206In this configuration the watcher triggers an event at the wallclock time 1305In this configuration the watcher triggers an event at the wallclock time
1207\&\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,
1208that 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
1209system time reaches or surpasses this time. 1308system time reaches or surpasses this time.
1210.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
1211.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)"
1212In 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
1213\&\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)
1214of any time jumps. 1313and then repeat, regardless of any time jumps.
1215.Sp 1314.Sp
1216This 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
1217time: 1316time:
1218.Sp 1317.Sp
1219.Vb 1 1318.Vb 1
… …
1226by 3600. 1325by 3600.
1227.Sp 1326.Sp
1228Another way to think about it (for the mathematically inclined) is that 1327Another way to think about it (for the mathematically inclined) is that
1229\&\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
1230time 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.
1231.IP "* manual reschedule mode (reschedule_cb = callback)" 4 1334.IP "* manual reschedule mode (at and interval ignored, reschedule_cb = callback)" 4
1232.IX Item "manual reschedule mode (reschedule_cb = callback)" 1335.IX Item "manual reschedule mode (at and interval ignored, reschedule_cb = callback)"
1233In 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
1234ignored. Instead, each time the periodic watcher gets scheduled, the 1337ignored. Instead, each time the periodic watcher gets scheduled, the
1235reschedule callback will be called with the watcher as first, and the 1338reschedule callback will be called with the watcher as first, and the
1236current time as second argument. 1339current time as second argument.
1237.Sp 1340.Sp
1238\&\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,
1239ever, 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,
1240return \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
1241starting a prepare watcher). 1344starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal).
1242.Sp 1345.Sp
1243Its 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,
1244ev_tstamp now)\*(C'\fR, e.g.: 1347ev_tstamp now)\*(C'\fR, e.g.:
1245.Sp 1348.Sp
1246.Vb 4 1349.Vb 4
… …
1270.IX Item "ev_periodic_again (loop, ev_periodic *)" 1373.IX Item "ev_periodic_again (loop, ev_periodic *)"
1271Simply stops and restarts the periodic watcher again. This is only useful 1374Simply stops and restarts the periodic watcher again. This is only useful
1272when you changed some parameters or the reschedule callback would return 1375when you changed some parameters or the reschedule callback would return
1273a 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
1274program 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.
1275.IP "ev_tstamp interval [read\-write]" 4 1385.IP "ev_tstamp interval [read\-write]" 4
1276.IX Item "ev_tstamp interval [read-write]" 1386.IX Item "ev_tstamp interval [read-write]"
1277The current interval value. Can be modified any time, but changes only 1387The current interval value. Can be modified any time, but changes only
1278take 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
1279called. 1389called.
1280.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
1281.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]"
1282The current reschedule callback, or \f(CW0\fR, if this functionality is 1392The current reschedule callback, or \f(CW0\fR, if this functionality is
1283switched 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
1284the 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.
1285.PP 1399.PP
1286Example: Call a callback every hour, or, more precisely, whenever the 1400Example: Call a callback every hour, or, more precisely, whenever the
1287system clock is divisible by 3600. The callback invocation times have 1401system clock is divisible by 3600. The callback invocation times have
1288potentially a lot of jittering, but good long-term stability. 1402potentially a lot of jittering, but good long-term stability.
1289.PP 1403.PP
… …
1339first watcher gets started will libev actually register a signal watcher 1453first watcher gets started will libev actually register a signal watcher
1340with 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
1341as 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
1342watcher 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
1343\&\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"
1344.IP "ev_signal_init (ev_signal *, callback, int signum)" 4 1461.IP "ev_signal_init (ev_signal *, callback, int signum)" 4
1345.IX Item "ev_signal_init (ev_signal *, callback, int signum)" 1462.IX Item "ev_signal_init (ev_signal *, callback, int signum)"
1346.PD 0 1463.PD 0
1347.IP "ev_signal_set (ev_signal *, int signum)" 4 1464.IP "ev_signal_set (ev_signal *, int signum)" 4
1348.IX Item "ev_signal_set (ev_signal *, int signum)" 1465.IX Item "ev_signal_set (ev_signal *, int signum)"
… …
1355.ie n .Sh """ev_child"" \- watch out for process status changes" 1472.ie n .Sh """ev_child"" \- watch out for process status changes"
1356.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"
1357.IX Subsection "ev_child - watch out for process status changes" 1474.IX Subsection "ev_child - watch out for process status changes"
1358Child 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
1359some 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"
1360.IP "ev_child_init (ev_child *, callback, int pid)" 4 1480.IP "ev_child_init (ev_child *, callback, int pid)" 4
1361.IX Item "ev_child_init (ev_child *, callback, int pid)" 1481.IX Item "ev_child_init (ev_child *, callback, int pid)"
1362.PD 0 1482.PD 0
1363.IP "ev_child_set (ev_child *, int pid)" 4 1483.IP "ev_child_set (ev_child *, int pid)" 4
1364.IX Item "ev_child_set (ev_child *, int pid)" 1484.IX Item "ev_child_set (ev_child *, int pid)"
… …
1429reader). 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
1430semantics 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
1431to 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
1432usually detected immediately, and if the file exists there will be no 1552usually detected immediately, and if the file exists there will be no
1433polling. 1553polling.
1554.PP
1555\fIWatcher-Specific Functions and Data Members\fR
1556.IX Subsection "Watcher-Specific Functions and Data Members"
1434.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
1435.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)"
1436.PD 0 1559.PD 0
1437.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
1438.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)"
… …
1499\& ev_stat_start (loop, &passwd); 1622\& ev_stat_start (loop, &passwd);
1500.Ve 1623.Ve
1501.ie n .Sh """ev_idle"" \- when you've got nothing better to do..." 1624.ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
1502.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." 1625.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
1503.IX Subsection "ev_idle - when you've got nothing better to do..." 1626.IX Subsection "ev_idle - when you've got nothing better to do..."
1504Idle watchers trigger events when there are no other events are pending 1627Idle watchers trigger events when no other events of the same or higher
1505(prepare, check and other idle watchers do not count). That is, as long 1628priority are pending (prepare, check and other idle watchers do not
1506as your process is busy handling sockets or timeouts (or even signals, 1629count).
1507imagine) it will not be triggered. But when your process is idle all idle 1630.PP
1508watchers are being called again and again, once per event loop iteration \- 1631That is, as long as your process is busy handling sockets or timeouts
1632(or even signals, imagine) of the same or higher priority it will not be
1633triggered. But when your process is idle (or only lower-priority watchers
1634are pending), the idle watchers are being called once per event loop
1509until stopped, that is, or your process receives more events and becomes 1635iteration \- until stopped, that is, or your process receives more events
1510busy. 1636and becomes busy again with higher priority stuff.
1511.PP 1637.PP
1512The most noteworthy effect is that as long as any idle watchers are 1638The most noteworthy effect is that as long as any idle watchers are
1513active, the process will not block when waiting for new events. 1639active, the process will not block when waiting for new events.
1514.PP 1640.PP
1515Apart from keeping your process non-blocking (which is a useful 1641Apart from keeping your process non-blocking (which is a useful
1516effect 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
1517\&\*(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
1518event 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"
1519.IP "ev_idle_init (ev_signal *, callback)" 4 1648.IP "ev_idle_init (ev_signal *, callback)" 4
1520.IX Item "ev_idle_init (ev_signal *, callback)" 1649.IX Item "ev_idle_init (ev_signal *, callback)"
1521Initialises and configures the idle watcher \- it has no parameters of any 1650Initialises and configures the idle watcher \- it has no parameters of any
1522kind. 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,
1523believe me. 1652believe me.
… …
1578are 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
1579with 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
1580of 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
1581loop from blocking if lower-priority coroutines are active, thus mapping 1710loop from blocking if lower-priority coroutines are active, thus mapping
1582low-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"
1583.IP "ev_prepare_init (ev_prepare *, callback)" 4 1725.IP "ev_prepare_init (ev_prepare *, callback)" 4
1584.IX Item "ev_prepare_init (ev_prepare *, callback)" 1726.IX Item "ev_prepare_init (ev_prepare *, callback)"
1585.PD 0 1727.PD 0
1586.IP "ev_check_init (ev_check *, callback)" 4 1728.IP "ev_check_init (ev_check *, callback)" 4
1587.IX Item "ev_check_init (ev_check *, callback)" 1729.IX Item "ev_check_init (ev_check *, callback)"
1588.PD 1730.PD
1589Initialises and configures the prepare or check watcher \- they have no 1731Initialises and configures the prepare or check watcher \- they have no
1590parameters 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
1591macros, but using them is utterly, utterly and completely pointless. 1733macros, but using them is utterly, utterly and completely pointless.
1592.PP 1734.PP
1593Example: 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
1594and 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,
1595in 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
1596pseudo-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.
1597.PP 1747.PP
1598.Vb 2 1748.Vb 2
1599\& static ev_io iow [nfd]; 1749\& static ev_io iow [nfd];
1600\& static ev_timer tw; 1750\& static ev_timer tw;
1601.Ve 1751.Ve
1602.PP 1752.PP
1603.Vb 9 1753.Vb 4
1604\& static void 1754\& static void
1605\& io_cb (ev_loop *loop, ev_io *w, int revents) 1755\& io_cb (ev_loop *loop, ev_io *w, int revents)
1606\& { 1756\& {
1607\& // set the relevant poll flags
1608\& // could also call adns_processreadable etc. here
1609\& struct pollfd *fd = (struct pollfd *)w->data;
1610\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1611\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1612\& } 1757\& }
1613.Ve 1758.Ve
1614.PP 1759.PP
1615.Vb 7 1760.Vb 8
1616\& // create io watchers for each fd and a timer before blocking 1761\& // create io watchers for each fd and a timer before blocking
1617\& static void 1762\& static void
1618\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) 1763\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1619\& { 1764\& {
1620\& int timeout = 3600000;truct pollfd fds [nfd]; 1765\& int timeout = 3600000;
1766\& struct pollfd fds [nfd];
1621\& // actual code will need to loop here and realloc etc. 1767\& // actual code will need to loop here and realloc etc.
1622\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); 1768\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1623.Ve 1769.Ve
1624.PP 1770.PP
1625.Vb 3 1771.Vb 3
… …
1627\& ev_timer_init (&tw, 0, timeout * 1e-3); 1773\& ev_timer_init (&tw, 0, timeout * 1e-3);
1628\& ev_timer_start (loop, &tw); 1774\& ev_timer_start (loop, &tw);
1629.Ve 1775.Ve
1630.PP 1776.PP
1631.Vb 6 1777.Vb 6
1632\& // create on ev_io per pollfd 1778\& // create one ev_io per pollfd
1633\& for (int i = 0; i < nfd; ++i) 1779\& for (int i = 0; i < nfd; ++i)
1634\& { 1780\& {
1635\& ev_io_init (iow + i, io_cb, fds [i].fd, 1781\& ev_io_init (iow + i, io_cb, fds [i].fd,
1636\& ((fds [i].events & POLLIN ? EV_READ : 0) 1782\& ((fds [i].events & POLLIN ? EV_READ : 0)
1637\& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); 1783\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1638.Ve 1784.Ve
1639.PP 1785.PP
1640.Vb 5 1786.Vb 4
1641\& fds [i].revents = 0; 1787\& fds [i].revents = 0;
1642\& iow [i].data = fds + i;
1643\& ev_io_start (loop, iow + i); 1788\& ev_io_start (loop, iow + i);
1644\& } 1789\& }
1645\& } 1790\& }
1646.Ve 1791.Ve
1647.PP 1792.PP
… …
1651\& adns_check_cb (ev_loop *loop, ev_check *w, int revents) 1796\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1652\& { 1797\& {
1653\& ev_timer_stop (loop, &tw); 1798\& ev_timer_stop (loop, &tw);
1654.Ve 1799.Ve
1655.PP 1800.PP
1656.Vb 2 1801.Vb 8
1657\& 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
1658\& ev_io_stop (loop, iow + i); 1814\& ev_io_stop (loop, iow + i);
1815\& }
1659.Ve 1816.Ve
1660.PP 1817.PP
1661.Vb 2 1818.Vb 2
1662\& 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;
1663\& } 1903\& }
1664.Ve 1904.Ve
1665.ie n .Sh """ev_embed"" \- when one backend isn't enough..." 1905.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1666.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..."
1667.IX Subsection "ev_embed - when one backend isn't enough..." 1907.IX Subsection "ev_embed - when one backend isn't enough..."
… …
1736\& ev_embed_start (loop_hi, &embed); 1976\& ev_embed_start (loop_hi, &embed);
1737\& } 1977\& }
1738\& else 1978\& else
1739\& loop_lo = loop_hi; 1979\& loop_lo = loop_hi;
1740.Ve 1980.Ve
1981.PP
1982\fIWatcher-Specific Functions and Data Members\fR
1983.IX Subsection "Watcher-Specific Functions and Data Members"
1741.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
1742.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)"
1743.PD 0 1986.PD 0
1744.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
1745.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)"
… …
1765\&\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
1766event 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,
1767and 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
1768\&\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
1769handlers 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"
1770.IP "ev_fork_init (ev_signal *, callback)" 4 2016.IP "ev_fork_init (ev_signal *, callback)" 4
1771.IX Item "ev_fork_init (ev_signal *, callback)" 2017.IX Item "ev_fork_init (ev_signal *, callback)"
1772Initialises and configures the fork watcher \- it has no parameters of any 2018Initialises and configures the fork watcher \- it has no parameters of any
1773kind. 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,
1774believe me. 2020believe me.
… …
1851.PP 2097.PP
1852.Vb 1 2098.Vb 1
1853\& #include <ev++.h> 2099\& #include <ev++.h>
1854.Ve 2100.Ve
1855.PP 2101.PP
1856(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
1857and puts all of its definitions (many of them macros) into the global 2103of them macros) into the global namespace. All \*(C+ specific things are
1858namespace. 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.
1859.PP 2106.PP
1860It 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+
1861\&\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).
1862.PP 2117.PP
1863Here 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:
1864.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
1865.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
1866.IX Item "ev::READ, ev::WRITE etc." 2121.IX Item "ev::READ, ev::WRITE etc."
… …
1878which 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
1879defines by many implementations. 2134defines by many implementations.
1880.Sp 2135.Sp
1881All of those classes have these methods: 2136All of those classes have these methods:
1882.RS 4 2137.RS 4
1883.IP "ev::TYPE::TYPE (object *, object::method *)" 4 2138.IP "ev::TYPE::TYPE ()" 4
1884.IX Item "ev::TYPE::TYPE (object *, object::method *)" 2139.IX Item "ev::TYPE::TYPE ()"
1885.PD 0 2140.PD 0
1886.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 2141.IP "ev::TYPE::TYPE (struct ev_loop *)" 4
1887.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 2142.IX Item "ev::TYPE::TYPE (struct ev_loop *)"
1888.IP "ev::TYPE::~TYPE" 4 2143.IP "ev::TYPE::~TYPE" 4
1889.IX Item "ev::TYPE::~TYPE" 2144.IX Item "ev::TYPE::~TYPE"
1890.PD 2145.PD
1891The constructor takes a pointer to an object and a method pointer to 2146The constructor (optionally) takes an event loop to associate the watcher
1892the 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.
1893\&\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
1894before 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
1895automatically 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).
1896.Sp 2157.Sp
1897The 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
1898.IP "w\->set (struct ev_loop *)" 4 2202.IP "w\->set (struct ev_loop *)" 4
1899.IX Item "w->set (struct ev_loop *)" 2203.IX Item "w->set (struct ev_loop *)"
1900Associates 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
1901do this when the watcher is inactive (and not pending either). 2205do this when the watcher is inactive (and not pending either).
1902.IP "w\->set ([args])" 4 2206.IP "w\->set ([args])" 4
1903.IX Item "w->set ([args])" 2207.IX Item "w->set ([args])"
1904Basically 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
1905called at least once. Unlike the C counterpart, an active watcher gets 2209called at least once. Unlike the C counterpart, an active watcher gets
1906automatically stopped and restarted. 2210automatically stopped and restarted when reconfiguring it with this
2211method.
1907.IP "w\->start ()" 4 2212.IP "w\->start ()" 4
1908.IX Item "w->start ()" 2213.IX Item "w->start ()"
1909Starts 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
1910constructor already takes the loop. 2215constructor already stores the event loop.
1911.IP "w\->stop ()" 4 2216.IP "w\->stop ()" 4
1912.IX Item "w->stop ()" 2217.IX Item "w->stop ()"
1913Stops 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.
1914.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
1915.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
1916.IX Item "w->again () ev::timer, ev::periodic only" 2221.IX Item "w->again () (ev::timer, ev::periodic only)"
1917For \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
1918\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. 2223\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function.
1919.ie n .IP "w\->sweep () ""ev::embed"" only" 4 2224.ie n .IP "w\->sweep () (""ev::embed"" only)" 4
1920.el .IP "w\->sweep () \f(CWev::embed\fR only" 4 2225.el .IP "w\->sweep () (\f(CWev::embed\fR only)" 4
1921.IX Item "w->sweep () ev::embed only" 2226.IX Item "w->sweep () (ev::embed only)"
1922Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. 2227Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR.
1923.ie n .IP "w\->update () ""ev::stat"" only" 4 2228.ie n .IP "w\->update () (""ev::stat"" only)" 4
1924.el .IP "w\->update () \f(CWev::stat\fR only" 4 2229.el .IP "w\->update () (\f(CWev::stat\fR only)" 4
1925.IX Item "w->update () ev::stat only" 2230.IX Item "w->update () (ev::stat only)"
1926Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. 2231Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR.
1927.RE 2232.RE
1928.RS 4 2233.RS 4
1929.RE 2234.RE
1930.PP 2235.PP
… …
1941.Vb 2 2246.Vb 2
1942\& myclass (); 2247\& myclass ();
1943\& } 2248\& }
1944.Ve 2249.Ve
1945.PP 2250.PP
1946.Vb 6 2251.Vb 4
1947\& myclass::myclass (int fd) 2252\& myclass::myclass (int fd)
1948\& : io (this, &myclass::io_cb),
1949\& idle (this, &myclass::idle_cb)
1950\& { 2253\& {
2254\& io .set <myclass, &myclass::io_cb > (this);
2255\& idle.set <myclass, &myclass::idle_cb> (this);
2256.Ve
2257.PP
2258.Vb 2
1951\& io.start (fd, ev::READ); 2259\& io.start (fd, ev::READ);
1952\& } 2260\& }
1953.Ve 2261.Ve
1954.SH "MACRO MAGIC" 2262.SH "MACRO MAGIC"
1955.IX Header "MACRO MAGIC" 2263.IX Header "MACRO MAGIC"
1956Libev can be compiled with a variety of options, the most fundemantal is 2264Libev can be compiled with a variety of options, the most fundamantal
1957\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines wether (most) functions and 2265of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most)
1958callbacks 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.
1959.PP 2267.PP
1960To 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
1961following macros are defined: 2269following macros are defined:
1962.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 2270.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
1963.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 2271.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4
… …
1997.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 2305.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
1998.IX Item "EV_DEFAULT, EV_DEFAULT_" 2306.IX Item "EV_DEFAULT, EV_DEFAULT_"
1999Similar to the other two macros, this gives you the value of the default 2307Similar to the other two macros, this gives you the value of the default
2000loop, if multiple loops are supported (\*(L"ev loop default\*(R"). 2308loop, if multiple loops are supported (\*(L"ev loop default\*(R").
2001.PP 2309.PP
2002Example: Declare and initialise a check watcher, working regardless of 2310Example: Declare and initialise a check watcher, utilising the above
2003wether multiple loops are supported or not. 2311macros so it will work regardless of whether multiple loops are supported
2312or not.
2004.PP 2313.PP
2005.Vb 5 2314.Vb 5
2006\& static void 2315\& static void
2007\& check_cb (EV_P_ ev_timer *w, int revents) 2316\& check_cb (EV_P_ ev_timer *w, int revents)
2008\& { 2317\& {
… …
2071.Vb 1 2380.Vb 1
2072\& ev_win32.c required on win32 platforms only 2381\& ev_win32.c required on win32 platforms only
2073.Ve 2382.Ve
2074.PP 2383.PP
2075.Vb 5 2384.Vb 5
2076\& ev_select.c only when select backend is enabled (which is by default) 2385\& ev_select.c only when select backend is enabled (which is enabled by default)
2077\& ev_poll.c only when poll backend is enabled (disabled by default) 2386\& ev_poll.c only when poll backend is enabled (disabled by default)
2078\& ev_epoll.c only when the epoll backend is enabled (disabled by default) 2387\& ev_epoll.c only when the epoll backend is enabled (disabled by default)
2079\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) 2388\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2080\& ev_port.c only when the solaris port backend is enabled (disabled by default) 2389\& ev_port.c only when the solaris port backend is enabled (disabled by default)
2081.Ve 2390.Ve
… …
2234If undefined or defined to \f(CW1\fR, then all event-loop-specific functions 2543If undefined or defined to \f(CW1\fR, then all event-loop-specific functions
2235will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create 2544will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create
2236additional independent event loops. Otherwise there will be no support 2545additional independent event loops. Otherwise there will be no support
2237for multiple event loops and there is no first event loop pointer 2546for multiple event loops and there is no first event loop pointer
2238argument. Instead, all functions act on the single default loop. 2547argument. Instead, all functions act on the single default loop.
2548.IP "\s-1EV_MINPRI\s0" 4
2549.IX Item "EV_MINPRI"
2550.PD 0
2551.IP "\s-1EV_MAXPRI\s0" 4
2552.IX Item "EV_MAXPRI"
2553.PD
2554The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to
2555\&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can
2556provide for more priorities by overriding those symbols (usually defined
2557to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively).
2558.Sp
2559When doing priority-based operations, libev usually has to linearly search
2560all the priorities, so having many of them (hundreds) uses a lot of space
2561and time, so using the defaults of five priorities (\-2 .. +2) is usually
2562fine.
2563.Sp
2564If your embedding app does not need any priorities, defining these both to
2565\&\f(CW0\fR will save some memory and cpu.
2239.IP "\s-1EV_PERIODIC_ENABLE\s0" 4 2566.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
2240.IX Item "EV_PERIODIC_ENABLE" 2567.IX Item "EV_PERIODIC_ENABLE"
2241If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If 2568If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
2569defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2570code.
2571.IP "\s-1EV_IDLE_ENABLE\s0" 4
2572.IX Item "EV_IDLE_ENABLE"
2573If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If
2242defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of 2574defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2243code. 2575code.
2244.IP "\s-1EV_EMBED_ENABLE\s0" 4 2576.IP "\s-1EV_EMBED_ENABLE\s0" 4
2245.IX Item "EV_EMBED_ENABLE" 2577.IX Item "EV_EMBED_ENABLE"
2246If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If 2578If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If
… …
2308interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file 2640interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file
2309will be compiled. It is pretty complex because it provides its own header 2641will be compiled. It is pretty complex because it provides its own header
2310file. 2642file.
2311.Sp 2643.Sp
2312The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file 2644The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
2313that everybody includes and which overrides some autoconf choices: 2645that everybody includes and which overrides some configure choices:
2314.Sp 2646.Sp
2315.Vb 4 2647.Vb 9
2648\& #define EV_MINIMAL 1
2316\& #define EV_USE_POLL 0 2649\& #define EV_USE_POLL 0
2317\& #define EV_MULTIPLICITY 0 2650\& #define EV_MULTIPLICITY 0
2318\& #define EV_PERIODICS 0 2651\& #define EV_PERIODIC_ENABLE 0
2652\& #define EV_STAT_ENABLE 0
2653\& #define EV_FORK_ENABLE 0
2319\& #define EV_CONFIG_H <config.h> 2654\& #define EV_CONFIG_H <config.h>
2655\& #define EV_MINPRI 0
2656\& #define EV_MAXPRI 0
2320.Ve 2657.Ve
2321.Sp 2658.Sp
2322.Vb 1 2659.Vb 1
2323\& #include "ev++.h" 2660\& #include "ev++.h"
2324.Ve 2661.Ve
… …
2332.SH "COMPLEXITIES" 2669.SH "COMPLEXITIES"
2333.IX Header "COMPLEXITIES" 2670.IX Header "COMPLEXITIES"
2334In this section the complexities of (many of) the algorithms used inside 2671In this section the complexities of (many of) the algorithms used inside
2335libev will be explained. For complexity discussions about backends see the 2672libev will be explained. For complexity discussions about backends see the
2336documentation for \f(CW\*(C`ev_default_init\*(C'\fR. 2673documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
2674.Sp
2675All of the following are about amortised time: If an array needs to be
2676extended, libev needs to realloc and move the whole array, but this
2677happens asymptotically never with higher number of elements, so O(1) might
2678mean it might do a lengthy realloc operation in rare cases, but on average
2679it is much faster and asymptotically approaches constant time.
2337.RS 4 2680.RS 4
2338.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 2681.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
2339.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 2682.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
2340.PD 0 2683This means that, when you have a watcher that triggers in one hour and
2684there are 100 watchers that would trigger before that then inserting will
2685have to skip those 100 watchers.
2341.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4 2686.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
2342.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 2687.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2688That means that for changing a timer costs less than removing/adding them
2689as only the relative motion in the event queue has to be paid for.
2343.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 2690.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
2344.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" 2691.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2345.IP "Stopping check/prepare/idle watchers: O(1)" 4 2692These just add the watcher into an array or at the head of a list.
2346.IX Item "Stopping check/prepare/idle watchers: O(1)" 2693=item Stopping check/prepare/idle watchers: O(1)
2347.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 2694.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
2348.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" 2695.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
2696These watchers are stored in lists then need to be walked to find the
2697correct watcher to remove. The lists are usually short (you don't usually
2698have many watchers waiting for the same fd or signal).
2349.IP "Finding the next timer per loop iteration: O(1)" 4 2699.IP "Finding the next timer per loop iteration: O(1)" 4
2350.IX Item "Finding the next timer per loop iteration: O(1)" 2700.IX Item "Finding the next timer per loop iteration: O(1)"
2701.PD 0
2351.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 2702.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
2352.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 2703.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
2704.PD
2705A change means an I/O watcher gets started or stopped, which requires
2706libev to recalculate its status (and possibly tell the kernel).
2353.IP "Activating one watcher: O(1)" 4 2707.IP "Activating one watcher: O(1)" 4
2354.IX Item "Activating one watcher: O(1)" 2708.IX Item "Activating one watcher: O(1)"
2709.PD 0
2710.IP "Priority handling: O(number_of_priorities)" 4
2711.IX Item "Priority handling: O(number_of_priorities)"
2712.PD
2713Priorities are implemented by allocating some space for each
2714priority. When doing priority-based operations, libev usually has to
2715linearly search all the priorities.
2355.RE 2716.RE
2356.RS 4 2717.RS 4
2357.PD
2358.SH "AUTHOR" 2718.SH "AUTHOR"
2359.IX Header "AUTHOR" 2719.IX Header "AUTHOR"
2360Marc Lehmann <libev@schmorp.de>. 2720Marc Lehmann <libev@schmorp.de>.

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