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Revision 1.29 by root, Tue Nov 27 20:38:07 2007 UTC vs.
Revision 1.51 by root, Wed Dec 12 17:55:30 2007 UTC

… …
127.\} 127.\}
128.rm #[ #] #H #V #F C 128.rm #[ #] #H #V #F C
129.\" ======================================================================== 129.\" ========================================================================
130.\" 130.\"
131.IX Title ""<STANDARD INPUT>" 1" 131.IX Title ""<STANDARD INPUT>" 1"
132.TH "<STANDARD INPUT>" 1 "2007-11-27" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH "<STANDARD INPUT>" 1 "2007-12-12" "perl v5.8.8" "User Contributed Perl Documentation"
133.SH "NAME" 133.SH "NAME"
134libev \- a high performance full\-featured event loop written in C 134libev \- a high performance full\-featured event loop written in C
135.SH "SYNOPSIS" 135.SH "SYNOPSIS"
136.IX Header "SYNOPSIS" 136.IX Header "SYNOPSIS"
137.Vb 1 137.Vb 1
… …
196\& return 0; 196\& return 0;
197\& } 197\& }
198.Ve 198.Ve
199.SH "DESCRIPTION" 199.SH "DESCRIPTION"
200.IX Header "DESCRIPTION" 200.IX Header "DESCRIPTION"
201The newest version of this document is also available as a html-formatted
202web page you might find easier to navigate when reading it for the first
203time: <http://cvs.schmorp.de/libev/ev.html>.
204.PP
201Libev is an event loop: you register interest in certain events (such as a 205Libev is an event loop: you register interest in certain events (such as a
202file descriptor being readable or a timeout occuring), and it will manage 206file descriptor being readable or a timeout occuring), and it will manage
203these event sources and provide your program with events. 207these event sources and provide your program with events.
204.PP 208.PP
205To do this, it must take more or less complete control over your process 209To do this, it must take more or less complete control over your process
… …
210watchers\fR, which are relatively small C structures you initialise with the 214watchers\fR, which are relatively small C structures you initialise with the
211details of the event, and then hand it over to libev by \fIstarting\fR the 215details of the event, and then hand it over to libev by \fIstarting\fR the
212watcher. 216watcher.
213.SH "FEATURES" 217.SH "FEATURES"
214.IX Header "FEATURES" 218.IX Header "FEATURES"
215Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the linux-specific \f(CW\*(C`epoll\*(C'\fR, the 219Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the
216bsd-specific \f(CW\*(C`kqueue\*(C'\fR and the solaris-specific event port mechanisms 220BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms
217for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), 221for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface
222(for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers
218absolute timers with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous 223with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals
219signals (\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and 224(\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event
220event watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, 225watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR,
221\&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as 226\&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as
222file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events 227file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events
223(\f(CW\*(C`ev_fork\*(C'\fR). 228(\f(CW\*(C`ev_fork\*(C'\fR).
224.PP 229.PP
225It also is quite fast (see this 230It also is quite fast (see this
… …
254.IX Item "int ev_version_major ()" 259.IX Item "int ev_version_major ()"
255.PD 0 260.PD 0
256.IP "int ev_version_minor ()" 4 261.IP "int ev_version_minor ()" 4
257.IX Item "int ev_version_minor ()" 262.IX Item "int ev_version_minor ()"
258.PD 263.PD
259You can find out the major and minor version numbers of the library 264You can find out the major and minor \s-1ABI\s0 version numbers of the library
260you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and 265you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and
261\&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global 266\&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global
262symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the 267symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the
263version of the library your program was compiled against. 268version of the library your program was compiled against.
264.Sp 269.Sp
270These version numbers refer to the \s-1ABI\s0 version of the library, not the
271release version.
272.Sp
265Usually, it's a good idea to terminate if the major versions mismatch, 273Usually, it's a good idea to terminate if the major versions mismatch,
266as this indicates an incompatible change. Minor versions are usually 274as this indicates an incompatible change. Minor versions are usually
267compatible to older versions, so a larger minor version alone is usually 275compatible to older versions, so a larger minor version alone is usually
268not a problem. 276not a problem.
269.Sp 277.Sp
270Example: Make sure we haven't accidentally been linked against the wrong 278Example: Make sure we haven't accidentally been linked against the wrong
271version. 279version.
… …
304might be supported on the current system, you would need to look at 312might be supported on the current system, you would need to look at
305\&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for 313\&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for
306recommended ones. 314recommended ones.
307.Sp 315.Sp
308See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. 316See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.
309.IP "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" 4 317.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4
310.IX Item "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" 318.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"
311Sets the allocation function to use (the prototype and semantics are 319Sets the allocation function to use (the prototype is similar \- the
312identical to the realloc C function). It is used to allocate and free 320semantics is identical \- to the realloc C function). It is used to
313memory (no surprises here). If it returns zero when memory needs to be 321allocate and free memory (no surprises here). If it returns zero when
314allocated, the library might abort or take some potentially destructive 322memory needs to be allocated, the library might abort or take some
315action. The default is your system realloc function. 323potentially destructive action. The default is your system realloc
324function.
316.Sp 325.Sp
317You could override this function in high-availability programs to, say, 326You could override this function in high-availability programs to, say,
318free some memory if it cannot allocate memory, to use a special allocator, 327free some memory if it cannot allocate memory, to use a special allocator,
319or even to sleep a while and retry until some memory is available. 328or even to sleep a while and retry until some memory is available.
320.Sp 329.Sp
… …
409or setgid) then libev will \fInot\fR look at the environment variable 418or setgid) then libev will \fInot\fR look at the environment variable
410\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will 419\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will
411override the flags completely if it is found in the environment. This is 420override the flags completely if it is found in the environment. This is
412useful to try out specific backends to test their performance, or to work 421useful to try out specific backends to test their performance, or to work
413around bugs. 422around bugs.
423.ie n .IP """EVFLAG_FORKCHECK""" 4
424.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4
425.IX Item "EVFLAG_FORKCHECK"
426Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after
427a fork, you can also make libev check for a fork in each iteration by
428enabling this flag.
429.Sp
430This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop,
431and thus this might slow down your event loop if you do a lot of loop
432iterations and little real work, but is usually not noticeable (on my
433Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence
434without a syscall and thus \fIvery\fR fast, but my Linux system also has
435\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster).
436.Sp
437The big advantage of this flag is that you can forget about fork (and
438forget about forgetting to tell libev about forking) when you use this
439flag.
440.Sp
441This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR
442environment variable.
414.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 443.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
415.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 444.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
416.IX Item "EVBACKEND_SELECT (value 1, portable select backend)" 445.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
417This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 446This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as
418libev tries to roll its own fd_set with no limits on the number of fds, 447libev tries to roll its own fd_set with no limits on the number of fds,
… …
559.IP "ev_loop_fork (loop)" 4 588.IP "ev_loop_fork (loop)" 4
560.IX Item "ev_loop_fork (loop)" 589.IX Item "ev_loop_fork (loop)"
561Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by 590Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by
562\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop 591\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop
563after fork, and how you do this is entirely your own problem. 592after fork, and how you do this is entirely your own problem.
593.IP "unsigned int ev_loop_count (loop)" 4
594.IX Item "unsigned int ev_loop_count (loop)"
595Returns the count of loop iterations for the loop, which is identical to
596the number of times libev did poll for new events. It starts at \f(CW0\fR and
597happily wraps around with enough iterations.
598.Sp
599This value can sometimes be useful as a generation counter of sorts (it
600\&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with
601\&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls.
564.IP "unsigned int ev_backend (loop)" 4 602.IP "unsigned int ev_backend (loop)" 4
565.IX Item "unsigned int ev_backend (loop)" 603.IX Item "unsigned int ev_backend (loop)"
566Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in 604Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
567use. 605use.
568.IP "ev_tstamp ev_now (loop)" 4 606.IP "ev_tstamp ev_now (loop)" 4
… …
599libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is 637libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is
600usually a better approach for this kind of thing. 638usually a better approach for this kind of thing.
601.Sp 639.Sp
602Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: 640Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does:
603.Sp 641.Sp
604.Vb 18 642.Vb 19
643\& - Before the first iteration, call any pending watchers.
605\& * If there are no active watchers (reference count is zero), return. 644\& * If there are no active watchers (reference count is zero), return.
606\& - Queue prepare watchers and then call all outstanding watchers. 645\& - Queue all prepare watchers and then call all outstanding watchers.
607\& - If we have been forked, recreate the kernel state. 646\& - If we have been forked, recreate the kernel state.
608\& - Update the kernel state with all outstanding changes. 647\& - Update the kernel state with all outstanding changes.
609\& - Update the "event loop time". 648\& - Update the "event loop time".
610\& - Calculate for how long to block. 649\& - Calculate for how long to block.
611\& - Block the process, waiting for any events. 650\& - Block the process, waiting for any events.
… …
854.IP "bool ev_is_pending (ev_TYPE *watcher)" 4 893.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
855.IX Item "bool ev_is_pending (ev_TYPE *watcher)" 894.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
856Returns a true value iff the watcher is pending, (i.e. it has outstanding 895Returns a true value iff the watcher is pending, (i.e. it has outstanding
857events but its callback has not yet been invoked). As long as a watcher 896events but its callback has not yet been invoked). As long as a watcher
858is pending (but not active) you must not call an init function on it (but 897is pending (but not active) you must not call an init function on it (but
859\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to 898\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must
860libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). 899make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR
900it).
861.IP "callback ev_cb (ev_TYPE *watcher)" 4 901.IP "callback ev_cb (ev_TYPE *watcher)" 4
862.IX Item "callback ev_cb (ev_TYPE *watcher)" 902.IX Item "callback ev_cb (ev_TYPE *watcher)"
863Returns the callback currently set on the watcher. 903Returns the callback currently set on the watcher.
864.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 904.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
865.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 905.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
866Change the callback. You can change the callback at virtually any time 906Change the callback. You can change the callback at virtually any time
867(modulo threads). 907(modulo threads).
908.IP "ev_set_priority (ev_TYPE *watcher, priority)" 4
909.IX Item "ev_set_priority (ev_TYPE *watcher, priority)"
910.PD 0
911.IP "int ev_priority (ev_TYPE *watcher)" 4
912.IX Item "int ev_priority (ev_TYPE *watcher)"
913.PD
914Set and query the priority of the watcher. The priority is a small
915integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR
916(default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked
917before watchers with lower priority, but priority will not keep watchers
918from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers).
919.Sp
920This means that priorities are \fIonly\fR used for ordering callback
921invocation after new events have been received. This is useful, for
922example, to reduce latency after idling, or more often, to bind two
923watchers on the same event and make sure one is called first.
924.Sp
925If you need to suppress invocation when higher priority events are pending
926you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality.
927.Sp
928You \fImust not\fR change the priority of a watcher as long as it is active or
929pending.
930.Sp
931The default priority used by watchers when no priority has been set is
932always \f(CW0\fR, which is supposed to not be too high and not be too low :).
933.Sp
934Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is
935fine, as long as you do not mind that the priority value you query might
936or might not have been adjusted to be within valid range.
937.IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4
938.IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)"
939Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither
940\&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback
941can deal with that fact.
942.IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4
943.IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)"
944If the watcher is pending, this function returns clears its pending status
945and returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the
946watcher isn't pending it does nothing and returns \f(CW0\fR.
868.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 947.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
869.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 948.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
870Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change 949Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change
871and read at any time, libev will completely ignore it. This can be used 950and read at any time, libev will completely ignore it. This can be used
872to associate arbitrary data with your watcher. If you need more data and 951to associate arbitrary data with your watcher. If you need more data and
… …
983it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning 1062it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning
984\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. 1063\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
985.PP 1064.PP
986If you cannot run the fd in non-blocking mode (for example you should not 1065If you cannot run the fd in non-blocking mode (for example you should not
987play around with an Xlib connection), then you have to seperately re-test 1066play around with an Xlib connection), then you have to seperately re-test
988wether a file descriptor is really ready with a known-to-be good interface 1067whether a file descriptor is really ready with a known-to-be good interface
989such as poll (fortunately in our Xlib example, Xlib already does this on 1068such as poll (fortunately in our Xlib example, Xlib already does this on
990its own, so its quite safe to use). 1069its own, so its quite safe to use).
1070.PP
1071\fIThe special problem of disappearing file descriptors\fR
1072.IX Subsection "The special problem of disappearing file descriptors"
1073.PP
1074Some backends (e.g kqueue, epoll) need to be told about closing a file
1075descriptor (either by calling \f(CW\*(C`close\*(C'\fR explicitly or by any other means,
1076such as \f(CW\*(C`dup\*(C'\fR). The reason is that you register interest in some file
1077descriptor, but when it goes away, the operating system will silently drop
1078this interest. If another file descriptor with the same number then is
1079registered with libev, there is no efficient way to see that this is, in
1080fact, a different file descriptor.
1081.PP
1082To avoid having to explicitly tell libev about such cases, libev follows
1083the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev
1084will assume that this is potentially a new file descriptor, otherwise
1085it is assumed that the file descriptor stays the same. That means that
1086you \fIhave\fR to call \f(CW\*(C`ev_io_set\*(C'\fR (or \f(CW\*(C`ev_io_init\*(C'\fR) when you change the
1087descriptor even if the file descriptor number itself did not change.
1088.PP
1089This is how one would do it normally anyway, the important point is that
1090the libev application should not optimise around libev but should leave
1091optimisations to libev.
1092.PP
1093\fIWatcher-Specific Functions\fR
1094.IX Subsection "Watcher-Specific Functions"
991.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 1095.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
992.IX Item "ev_io_init (ev_io *, callback, int fd, int events)" 1096.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
993.PD 0 1097.PD 0
994.IP "ev_io_set (ev_io *, int fd, int events)" 4 1098.IP "ev_io_set (ev_io *, int fd, int events)" 4
995.IX Item "ev_io_set (ev_io *, int fd, int events)" 1099.IX Item "ev_io_set (ev_io *, int fd, int events)"
… …
1048.Ve 1152.Ve
1049.PP 1153.PP
1050The callback is guarenteed to be invoked only when its timeout has passed, 1154The callback is guarenteed to be invoked only when its timeout has passed,
1051but if multiple timers become ready during the same loop iteration then 1155but if multiple timers become ready during the same loop iteration then
1052order of execution is undefined. 1156order of execution is undefined.
1157.PP
1158\fIWatcher-Specific Functions and Data Members\fR
1159.IX Subsection "Watcher-Specific Functions and Data Members"
1053.IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 1160.IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4
1054.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 1161.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)"
1055.PD 0 1162.PD 0
1056.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 1163.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4
1057.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 1164.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)"
… …
1069.IP "ev_timer_again (loop)" 4 1176.IP "ev_timer_again (loop)" 4
1070.IX Item "ev_timer_again (loop)" 1177.IX Item "ev_timer_again (loop)"
1071This will act as if the timer timed out and restart it again if it is 1178This will act as if the timer timed out and restart it again if it is
1072repeating. The exact semantics are: 1179repeating. The exact semantics are:
1073.Sp 1180.Sp
1181If the timer is pending, its pending status is cleared.
1182.Sp
1074If the timer is started but nonrepeating, stop it. 1183If the timer is started but nonrepeating, stop it (as if it timed out).
1075.Sp 1184.Sp
1076If the timer is repeating, either start it if necessary (with the repeat 1185If the timer is repeating, either start it if necessary (with the
1077value), or reset the running timer to the repeat value. 1186\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value.
1078.Sp 1187.Sp
1079This sounds a bit complicated, but here is a useful and typical 1188This sounds a bit complicated, but here is a useful and typical
1080example: Imagine you have a tcp connection and you want a so-called 1189example: Imagine you have a tcp connection and you want a so-called idle
1081idle timeout, that is, you want to be called when there have been, 1190timeout, that is, you want to be called when there have been, say, 60
1082say, 60 seconds of inactivity on the socket. The easiest way to do 1191seconds of inactivity on the socket. The easiest way to do this is to
1083this is to configure an \f(CW\*(C`ev_timer\*(C'\fR with \f(CW\*(C`after\*(C'\fR=\f(CW\*(C`repeat\*(C'\fR=\f(CW60\fR and calling 1192configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value of \f(CW60\fR and then call
1084\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If 1193\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If
1085you go into an idle state where you do not expect data to travel on the 1194you go into an idle state where you do not expect data to travel on the
1086socket, you can stop the timer, and again will automatically restart it if 1195socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will
1087need be. 1196automatically restart it if need be.
1088.Sp 1197.Sp
1089You can also ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR altogether 1198That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR
1090and only ever use the \f(CW\*(C`repeat\*(C'\fR value: 1199altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR:
1091.Sp 1200.Sp
1092.Vb 8 1201.Vb 8
1093\& ev_timer_init (timer, callback, 0., 5.); 1202\& ev_timer_init (timer, callback, 0., 5.);
1094\& ev_timer_again (loop, timer); 1203\& ev_timer_again (loop, timer);
1095\& ... 1204\& ...
… …
1098\& ... 1207\& ...
1099\& timer->again = 10.; 1208\& timer->again = 10.;
1100\& ev_timer_again (loop, timer); 1209\& ev_timer_again (loop, timer);
1101.Ve 1210.Ve
1102.Sp 1211.Sp
1103This is more efficient then stopping/starting the timer eahc time you want 1212This is more slightly efficient then stopping/starting the timer each time
1104to modify its timeout value. 1213you want to modify its timeout value.
1105.IP "ev_tstamp repeat [read\-write]" 4 1214.IP "ev_tstamp repeat [read\-write]" 4
1106.IX Item "ev_tstamp repeat [read-write]" 1215.IX Item "ev_tstamp repeat [read-write]"
1107The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out 1216The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out
1108or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), 1217or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any),
1109which is also when any modifications are taken into account. 1218which is also when any modifications are taken into account.
… …
1157but on wallclock time (absolute time). You can tell a periodic watcher 1266but on wallclock time (absolute time). You can tell a periodic watcher
1158to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a 1267to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a
1159periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () 1268periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now ()
1160+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will 1269+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will
1161take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger 1270take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger
1162roughly 10 seconds later and of course not if you reset your system time 1271roughly 10 seconds later).
1163again).
1164.PP 1272.PP
1165They can also be used to implement vastly more complex timers, such as 1273They can also be used to implement vastly more complex timers, such as
1166triggering an event on eahc midnight, local time. 1274triggering an event on each midnight, local time or other, complicated,
1275rules.
1167.PP 1276.PP
1168As with timers, the callback is guarenteed to be invoked only when the 1277As with timers, the callback is guarenteed to be invoked only when the
1169time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready 1278time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready
1170during the same loop iteration then order of execution is undefined. 1279during the same loop iteration then order of execution is undefined.
1280.PP
1281\fIWatcher-Specific Functions and Data Members\fR
1282.IX Subsection "Watcher-Specific Functions and Data Members"
1171.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 1283.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4
1172.IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 1284.IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)"
1173.PD 0 1285.PD 0
1174.IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 1286.IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4
1175.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 1287.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)"
1176.PD 1288.PD
1177Lots of arguments, lets sort it out... There are basically three modes of 1289Lots of arguments, lets sort it out... There are basically three modes of
1178operation, and we will explain them from simplest to complex: 1290operation, and we will explain them from simplest to complex:
1179.RS 4 1291.RS 4
1180.IP "* absolute timer (interval = reschedule_cb = 0)" 4 1292.IP "* absolute timer (at = time, interval = reschedule_cb = 0)" 4
1181.IX Item "absolute timer (interval = reschedule_cb = 0)" 1293.IX Item "absolute timer (at = time, interval = reschedule_cb = 0)"
1182In this configuration the watcher triggers an event at the wallclock time 1294In this configuration the watcher triggers an event at the wallclock time
1183\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, 1295\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs,
1184that is, if it is to be run at January 1st 2011 then it will run when the 1296that is, if it is to be run at January 1st 2011 then it will run when the
1185system time reaches or surpasses this time. 1297system time reaches or surpasses this time.
1186.IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4 1298.IP "* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" 4
1187.IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)" 1299.IX Item "non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)"
1188In this mode the watcher will always be scheduled to time out at the next 1300In this mode the watcher will always be scheduled to time out at the next
1189\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless 1301\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative)
1190of any time jumps. 1302and then repeat, regardless of any time jumps.
1191.Sp 1303.Sp
1192This can be used to create timers that do not drift with respect to system 1304This can be used to create timers that do not drift with respect to system
1193time: 1305time:
1194.Sp 1306.Sp
1195.Vb 1 1307.Vb 1
… …
1202by 3600. 1314by 3600.
1203.Sp 1315.Sp
1204Another way to think about it (for the mathematically inclined) is that 1316Another way to think about it (for the mathematically inclined) is that
1205\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible 1317\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible
1206time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. 1318time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps.
1319.Sp
1320For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near
1321\&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for
1322this value.
1207.IP "* manual reschedule mode (reschedule_cb = callback)" 4 1323.IP "* manual reschedule mode (at and interval ignored, reschedule_cb = callback)" 4
1208.IX Item "manual reschedule mode (reschedule_cb = callback)" 1324.IX Item "manual reschedule mode (at and interval ignored, reschedule_cb = callback)"
1209In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being 1325In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being
1210ignored. Instead, each time the periodic watcher gets scheduled, the 1326ignored. Instead, each time the periodic watcher gets scheduled, the
1211reschedule callback will be called with the watcher as first, and the 1327reschedule callback will be called with the watcher as first, and the
1212current time as second argument. 1328current time as second argument.
1213.Sp 1329.Sp
1214\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, 1330\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher,
1215ever, or make any event loop modifications\fR. If you need to stop it, 1331ever, or make any event loop modifications\fR. If you need to stop it,
1216return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by 1332return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by
1217starting a prepare watcher). 1333starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal).
1218.Sp 1334.Sp
1219Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, 1335Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
1220ev_tstamp now)\*(C'\fR, e.g.: 1336ev_tstamp now)\*(C'\fR, e.g.:
1221.Sp 1337.Sp
1222.Vb 4 1338.Vb 4
… …
1246.IX Item "ev_periodic_again (loop, ev_periodic *)" 1362.IX Item "ev_periodic_again (loop, ev_periodic *)"
1247Simply stops and restarts the periodic watcher again. This is only useful 1363Simply stops and restarts the periodic watcher again. This is only useful
1248when you changed some parameters or the reschedule callback would return 1364when you changed some parameters or the reschedule callback would return
1249a different time than the last time it was called (e.g. in a crond like 1365a different time than the last time it was called (e.g. in a crond like
1250program when the crontabs have changed). 1366program when the crontabs have changed).
1367.IP "ev_tstamp offset [read\-write]" 4
1368.IX Item "ev_tstamp offset [read-write]"
1369When repeating, this contains the offset value, otherwise this is the
1370absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR).
1371.Sp
1372Can be modified any time, but changes only take effect when the periodic
1373timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1251.IP "ev_tstamp interval [read\-write]" 4 1374.IP "ev_tstamp interval [read\-write]" 4
1252.IX Item "ev_tstamp interval [read-write]" 1375.IX Item "ev_tstamp interval [read-write]"
1253The current interval value. Can be modified any time, but changes only 1376The current interval value. Can be modified any time, but changes only
1254take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being 1377take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being
1255called. 1378called.
… …
1315first watcher gets started will libev actually register a signal watcher 1438first watcher gets started will libev actually register a signal watcher
1316with the kernel (thus it coexists with your own signal handlers as long 1439with the kernel (thus it coexists with your own signal handlers as long
1317as you don't register any with libev). Similarly, when the last signal 1440as you don't register any with libev). Similarly, when the last signal
1318watcher for a signal is stopped libev will reset the signal handler to 1441watcher for a signal is stopped libev will reset the signal handler to
1319\&\s-1SIG_DFL\s0 (regardless of what it was set to before). 1442\&\s-1SIG_DFL\s0 (regardless of what it was set to before).
1443.PP
1444\fIWatcher-Specific Functions and Data Members\fR
1445.IX Subsection "Watcher-Specific Functions and Data Members"
1320.IP "ev_signal_init (ev_signal *, callback, int signum)" 4 1446.IP "ev_signal_init (ev_signal *, callback, int signum)" 4
1321.IX Item "ev_signal_init (ev_signal *, callback, int signum)" 1447.IX Item "ev_signal_init (ev_signal *, callback, int signum)"
1322.PD 0 1448.PD 0
1323.IP "ev_signal_set (ev_signal *, int signum)" 4 1449.IP "ev_signal_set (ev_signal *, int signum)" 4
1324.IX Item "ev_signal_set (ev_signal *, int signum)" 1450.IX Item "ev_signal_set (ev_signal *, int signum)"
… …
1331.ie n .Sh """ev_child"" \- watch out for process status changes" 1457.ie n .Sh """ev_child"" \- watch out for process status changes"
1332.el .Sh "\f(CWev_child\fP \- watch out for process status changes" 1458.el .Sh "\f(CWev_child\fP \- watch out for process status changes"
1333.IX Subsection "ev_child - watch out for process status changes" 1459.IX Subsection "ev_child - watch out for process status changes"
1334Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to 1460Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to
1335some child status changes (most typically when a child of yours dies). 1461some child status changes (most typically when a child of yours dies).
1462.PP
1463\fIWatcher-Specific Functions and Data Members\fR
1464.IX Subsection "Watcher-Specific Functions and Data Members"
1336.IP "ev_child_init (ev_child *, callback, int pid)" 4 1465.IP "ev_child_init (ev_child *, callback, int pid)" 4
1337.IX Item "ev_child_init (ev_child *, callback, int pid)" 1466.IX Item "ev_child_init (ev_child *, callback, int pid)"
1338.PD 0 1467.PD 0
1339.IP "ev_child_set (ev_child *, int pid)" 4 1468.IP "ev_child_set (ev_child *, int pid)" 4
1340.IX Item "ev_child_set (ev_child *, int pid)" 1469.IX Item "ev_child_set (ev_child *, int pid)"
… …
1382not exist\*(R" is a status change like any other. The condition \*(L"path does 1511not exist\*(R" is a status change like any other. The condition \*(L"path does
1383not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is 1512not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is
1384otherwise always forced to be at least one) and all the other fields of 1513otherwise always forced to be at least one) and all the other fields of
1385the stat buffer having unspecified contents. 1514the stat buffer having unspecified contents.
1386.PP 1515.PP
1516The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is
1517relative and your working directory changes, the behaviour is undefined.
1518.PP
1387Since there is no standard to do this, the portable implementation simply 1519Since there is no standard to do this, the portable implementation simply
1388calls \f(CW\*(C`stat (2)\*(C'\fR regulalry on the path to see if it changed somehow. You 1520calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You
1389can specify a recommended polling interval for this case. If you specify 1521can specify a recommended polling interval for this case. If you specify
1390a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, 1522a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable,
1391unspecified default\fR value will be used (which you can expect to be around 1523unspecified default\fR value will be used (which you can expect to be around
1392five seconds, although this might change dynamically). Libev will also 1524five seconds, although this might change dynamically). Libev will also
1393impose a minimum interval which is currently around \f(CW0.1\fR, but thats 1525impose a minimum interval which is currently around \f(CW0.1\fR, but thats
… …
1395.PP 1527.PP
1396This watcher type is not meant for massive numbers of stat watchers, 1528This watcher type is not meant for massive numbers of stat watchers,
1397as even with OS-supported change notifications, this can be 1529as even with OS-supported change notifications, this can be
1398resource\-intensive. 1530resource\-intensive.
1399.PP 1531.PP
1400At the time of this writing, no specific \s-1OS\s0 backends are implemented, but 1532At the time of this writing, only the Linux inotify interface is
1401if demand increases, at least a kqueue and inotify backend will be added. 1533implemented (implementing kqueue support is left as an exercise for the
1534reader). Inotify will be used to give hints only and should not change the
1535semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs
1536to fall back to regular polling again even with inotify, but changes are
1537usually detected immediately, and if the file exists there will be no
1538polling.
1539.PP
1540\fIWatcher-Specific Functions and Data Members\fR
1541.IX Subsection "Watcher-Specific Functions and Data Members"
1402.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 1542.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
1403.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 1543.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
1404.PD 0 1544.PD 0
1405.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 1545.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4
1406.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 1546.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
… …
1467\& ev_stat_start (loop, &passwd); 1607\& ev_stat_start (loop, &passwd);
1468.Ve 1608.Ve
1469.ie n .Sh """ev_idle"" \- when you've got nothing better to do..." 1609.ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
1470.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." 1610.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
1471.IX Subsection "ev_idle - when you've got nothing better to do..." 1611.IX Subsection "ev_idle - when you've got nothing better to do..."
1472Idle watchers trigger events when there are no other events are pending 1612Idle watchers trigger events when no other events of the same or higher
1473(prepare, check and other idle watchers do not count). That is, as long 1613priority are pending (prepare, check and other idle watchers do not
1474as your process is busy handling sockets or timeouts (or even signals, 1614count).
1475imagine) it will not be triggered. But when your process is idle all idle 1615.PP
1476watchers are being called again and again, once per event loop iteration \- 1616That is, as long as your process is busy handling sockets or timeouts
1617(or even signals, imagine) of the same or higher priority it will not be
1618triggered. But when your process is idle (or only lower-priority watchers
1619are pending), the idle watchers are being called once per event loop
1477until stopped, that is, or your process receives more events and becomes 1620iteration \- until stopped, that is, or your process receives more events
1478busy. 1621and becomes busy again with higher priority stuff.
1479.PP 1622.PP
1480The most noteworthy effect is that as long as any idle watchers are 1623The most noteworthy effect is that as long as any idle watchers are
1481active, the process will not block when waiting for new events. 1624active, the process will not block when waiting for new events.
1482.PP 1625.PP
1483Apart from keeping your process non-blocking (which is a useful 1626Apart from keeping your process non-blocking (which is a useful
1484effect on its own sometimes), idle watchers are a good place to do 1627effect on its own sometimes), idle watchers are a good place to do
1485\&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the 1628\&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the
1486event loop has handled all outstanding events. 1629event loop has handled all outstanding events.
1630.PP
1631\fIWatcher-Specific Functions and Data Members\fR
1632.IX Subsection "Watcher-Specific Functions and Data Members"
1487.IP "ev_idle_init (ev_signal *, callback)" 4 1633.IP "ev_idle_init (ev_signal *, callback)" 4
1488.IX Item "ev_idle_init (ev_signal *, callback)" 1634.IX Item "ev_idle_init (ev_signal *, callback)"
1489Initialises and configures the idle watcher \- it has no parameters of any 1635Initialises and configures the idle watcher \- it has no parameters of any
1490kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, 1636kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,
1491believe me. 1637believe me.
… …
1546are ready to run (it's actually more complicated: it only runs coroutines 1692are ready to run (it's actually more complicated: it only runs coroutines
1547with priority higher than or equal to the event loop and one coroutine 1693with priority higher than or equal to the event loop and one coroutine
1548of lower priority, but only once, using idle watchers to keep the event 1694of lower priority, but only once, using idle watchers to keep the event
1549loop from blocking if lower-priority coroutines are active, thus mapping 1695loop from blocking if lower-priority coroutines are active, thus mapping
1550low-priority coroutines to idle/background tasks). 1696low-priority coroutines to idle/background tasks).
1697.PP
1698It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR)
1699priority, to ensure that they are being run before any other watchers
1700after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers,
1701too) should not activate (\*(L"feed\*(R") events into libev. While libev fully
1702supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers did
1703their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other event
1704loops those other event loops might be in an unusable state until their
1705\&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with
1706others).
1707.PP
1708\fIWatcher-Specific Functions and Data Members\fR
1709.IX Subsection "Watcher-Specific Functions and Data Members"
1551.IP "ev_prepare_init (ev_prepare *, callback)" 4 1710.IP "ev_prepare_init (ev_prepare *, callback)" 4
1552.IX Item "ev_prepare_init (ev_prepare *, callback)" 1711.IX Item "ev_prepare_init (ev_prepare *, callback)"
1553.PD 0 1712.PD 0
1554.IP "ev_check_init (ev_check *, callback)" 4 1713.IP "ev_check_init (ev_check *, callback)" 4
1555.IX Item "ev_check_init (ev_check *, callback)" 1714.IX Item "ev_check_init (ev_check *, callback)"
1556.PD 1715.PD
1557Initialises and configures the prepare or check watcher \- they have no 1716Initialises and configures the prepare or check watcher \- they have no
1558parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR 1717parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR
1559macros, but using them is utterly, utterly and completely pointless. 1718macros, but using them is utterly, utterly and completely pointless.
1560.PP 1719.PP
1561Example: To include a library such as adns, you would add \s-1IO\s0 watchers 1720There are a number of principal ways to embed other event loops or modules
1562and a timeout watcher in a prepare handler, as required by libadns, and 1721into libev. Here are some ideas on how to include libadns into libev
1722(there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could
1723use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR
1724embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0
1725into the Glib event loop).
1726.PP
1727Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler,
1563in a check watcher, destroy them and call into libadns. What follows is 1728and in a check watcher, destroy them and call into libadns. What follows
1564pseudo-code only of course: 1729is pseudo-code only of course. This requires you to either use a low
1730priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as
1731the callbacks for the IO/timeout watchers might not have been called yet.
1565.PP 1732.PP
1566.Vb 2 1733.Vb 2
1567\& static ev_io iow [nfd]; 1734\& static ev_io iow [nfd];
1568\& static ev_timer tw; 1735\& static ev_timer tw;
1569.Ve 1736.Ve
1570.PP 1737.PP
1571.Vb 9 1738.Vb 4
1572\& static void 1739\& static void
1573\& io_cb (ev_loop *loop, ev_io *w, int revents) 1740\& io_cb (ev_loop *loop, ev_io *w, int revents)
1574\& { 1741\& {
1575\& // set the relevant poll flags
1576\& // could also call adns_processreadable etc. here
1577\& struct pollfd *fd = (struct pollfd *)w->data;
1578\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1579\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1580\& } 1742\& }
1581.Ve 1743.Ve
1582.PP 1744.PP
1583.Vb 7 1745.Vb 8
1584\& // create io watchers for each fd and a timer before blocking 1746\& // create io watchers for each fd and a timer before blocking
1585\& static void 1747\& static void
1586\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) 1748\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1587\& { 1749\& {
1588\& int timeout = 3600000;truct pollfd fds [nfd]; 1750\& int timeout = 3600000;
1751\& struct pollfd fds [nfd];
1589\& // actual code will need to loop here and realloc etc. 1752\& // actual code will need to loop here and realloc etc.
1590\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); 1753\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1591.Ve 1754.Ve
1592.PP 1755.PP
1593.Vb 3 1756.Vb 3
… …
1595\& ev_timer_init (&tw, 0, timeout * 1e-3); 1758\& ev_timer_init (&tw, 0, timeout * 1e-3);
1596\& ev_timer_start (loop, &tw); 1759\& ev_timer_start (loop, &tw);
1597.Ve 1760.Ve
1598.PP 1761.PP
1599.Vb 6 1762.Vb 6
1600\& // create on ev_io per pollfd 1763\& // create one ev_io per pollfd
1601\& for (int i = 0; i < nfd; ++i) 1764\& for (int i = 0; i < nfd; ++i)
1602\& { 1765\& {
1603\& ev_io_init (iow + i, io_cb, fds [i].fd, 1766\& ev_io_init (iow + i, io_cb, fds [i].fd,
1604\& ((fds [i].events & POLLIN ? EV_READ : 0) 1767\& ((fds [i].events & POLLIN ? EV_READ : 0)
1605\& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); 1768\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1606.Ve 1769.Ve
1607.PP 1770.PP
1608.Vb 5 1771.Vb 4
1609\& fds [i].revents = 0; 1772\& fds [i].revents = 0;
1610\& iow [i].data = fds + i;
1611\& ev_io_start (loop, iow + i); 1773\& ev_io_start (loop, iow + i);
1612\& } 1774\& }
1613\& } 1775\& }
1614.Ve 1776.Ve
1615.PP 1777.PP
… …
1619\& adns_check_cb (ev_loop *loop, ev_check *w, int revents) 1781\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1620\& { 1782\& {
1621\& ev_timer_stop (loop, &tw); 1783\& ev_timer_stop (loop, &tw);
1622.Ve 1784.Ve
1623.PP 1785.PP
1624.Vb 2 1786.Vb 8
1625\& for (int i = 0; i < nfd; ++i) 1787\& for (int i = 0; i < nfd; ++i)
1788\& {
1789\& // set the relevant poll flags
1790\& // could also call adns_processreadable etc. here
1791\& struct pollfd *fd = fds + i;
1792\& int revents = ev_clear_pending (iow + i);
1793\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1794\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1795.Ve
1796.PP
1797.Vb 3
1798\& // now stop the watcher
1626\& ev_io_stop (loop, iow + i); 1799\& ev_io_stop (loop, iow + i);
1800\& }
1627.Ve 1801.Ve
1628.PP 1802.PP
1629.Vb 2 1803.Vb 2
1630\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); 1804\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1805\& }
1806.Ve
1807.PP
1808Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR
1809in the prepare watcher and would dispose of the check watcher.
1810.PP
1811Method 3: If the module to be embedded supports explicit event
1812notification (adns does), you can also make use of the actual watcher
1813callbacks, and only destroy/create the watchers in the prepare watcher.
1814.PP
1815.Vb 5
1816\& static void
1817\& timer_cb (EV_P_ ev_timer *w, int revents)
1818\& {
1819\& adns_state ads = (adns_state)w->data;
1820\& update_now (EV_A);
1821.Ve
1822.PP
1823.Vb 2
1824\& adns_processtimeouts (ads, &tv_now);
1825\& }
1826.Ve
1827.PP
1828.Vb 5
1829\& static void
1830\& io_cb (EV_P_ ev_io *w, int revents)
1831\& {
1832\& adns_state ads = (adns_state)w->data;
1833\& update_now (EV_A);
1834.Ve
1835.PP
1836.Vb 3
1837\& if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1838\& if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1839\& }
1840.Ve
1841.PP
1842.Vb 1
1843\& // do not ever call adns_afterpoll
1844.Ve
1845.PP
1846Method 4: Do not use a prepare or check watcher because the module you
1847want to embed is too inflexible to support it. Instead, youc na override
1848their poll function. The drawback with this solution is that the main
1849loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does
1850this.
1851.PP
1852.Vb 4
1853\& static gint
1854\& event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1855\& {
1856\& int got_events = 0;
1857.Ve
1858.PP
1859.Vb 2
1860\& for (n = 0; n < nfds; ++n)
1861\& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1862.Ve
1863.PP
1864.Vb 2
1865\& if (timeout >= 0)
1866\& // create/start timer
1867.Ve
1868.PP
1869.Vb 2
1870\& // poll
1871\& ev_loop (EV_A_ 0);
1872.Ve
1873.PP
1874.Vb 3
1875\& // stop timer again
1876\& if (timeout >= 0)
1877\& ev_timer_stop (EV_A_ &to);
1878.Ve
1879.PP
1880.Vb 3
1881\& // stop io watchers again - their callbacks should have set
1882\& for (n = 0; n < nfds; ++n)
1883\& ev_io_stop (EV_A_ iow [n]);
1884.Ve
1885.PP
1886.Vb 2
1887\& return got_events;
1631\& } 1888\& }
1632.Ve 1889.Ve
1633.ie n .Sh """ev_embed"" \- when one backend isn't enough..." 1890.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1634.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." 1891.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
1635.IX Subsection "ev_embed - when one backend isn't enough..." 1892.IX Subsection "ev_embed - when one backend isn't enough..."
… …
1704\& ev_embed_start (loop_hi, &embed); 1961\& ev_embed_start (loop_hi, &embed);
1705\& } 1962\& }
1706\& else 1963\& else
1707\& loop_lo = loop_hi; 1964\& loop_lo = loop_hi;
1708.Ve 1965.Ve
1966.PP
1967\fIWatcher-Specific Functions and Data Members\fR
1968.IX Subsection "Watcher-Specific Functions and Data Members"
1709.IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 1969.IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
1710.IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 1970.IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)"
1711.PD 0 1971.PD 0
1712.IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 1972.IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
1713.IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 1973.IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)"
… …
1733\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the 1993\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the
1734event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, 1994event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called,
1735and only in the child after the fork. If whoever good citizen calling 1995and only in the child after the fork. If whoever good citizen calling
1736\&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork 1996\&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork
1737handlers will be invoked, too, of course. 1997handlers will be invoked, too, of course.
1998.PP
1999\fIWatcher-Specific Functions and Data Members\fR
2000.IX Subsection "Watcher-Specific Functions and Data Members"
1738.IP "ev_fork_init (ev_signal *, callback)" 4 2001.IP "ev_fork_init (ev_signal *, callback)" 4
1739.IX Item "ev_fork_init (ev_signal *, callback)" 2002.IX Item "ev_fork_init (ev_signal *, callback)"
1740Initialises and configures the fork watcher \- it has no parameters of any 2003Initialises and configures the fork watcher \- it has no parameters of any
1741kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, 2004kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless,
1742believe me. 2005believe me.
… …
1819.PP 2082.PP
1820.Vb 1 2083.Vb 1
1821\& #include <ev++.h> 2084\& #include <ev++.h>
1822.Ve 2085.Ve
1823.PP 2086.PP
1824(it is not installed by default). This automatically includes \fIev.h\fR 2087This automatically includes \fIev.h\fR and puts all of its definitions (many
1825and puts all of its definitions (many of them macros) into the global 2088of them macros) into the global namespace. All \*(C+ specific things are
1826namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace. 2089put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding
2090options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
1827.PP 2091.PP
1828It should support all the same embedding options as \fIev.h\fR, most notably 2092Care has been taken to keep the overhead low. The only data member the \*(C+
1829\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. 2093classes add (compared to plain C\-style watchers) is the event loop pointer
2094that the watcher is associated with (or no additional members at all if
2095you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev).
2096.PP
2097Currently, functions, and static and non-static member functions can be
2098used as callbacks. Other types should be easy to add as long as they only
2099need one additional pointer for context. If you need support for other
2100types of functors please contact the author (preferably after implementing
2101it).
1830.PP 2102.PP
1831Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: 2103Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
1832.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 2104.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
1833.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 2105.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
1834.IX Item "ev::READ, ev::WRITE etc." 2106.IX Item "ev::READ, ev::WRITE etc."
… …
1846which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro 2118which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
1847defines by many implementations. 2119defines by many implementations.
1848.Sp 2120.Sp
1849All of those classes have these methods: 2121All of those classes have these methods:
1850.RS 4 2122.RS 4
1851.IP "ev::TYPE::TYPE (object *, object::method *)" 4 2123.IP "ev::TYPE::TYPE ()" 4
1852.IX Item "ev::TYPE::TYPE (object *, object::method *)" 2124.IX Item "ev::TYPE::TYPE ()"
1853.PD 0 2125.PD 0
1854.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 2126.IP "ev::TYPE::TYPE (struct ev_loop *)" 4
1855.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 2127.IX Item "ev::TYPE::TYPE (struct ev_loop *)"
1856.IP "ev::TYPE::~TYPE" 4 2128.IP "ev::TYPE::~TYPE" 4
1857.IX Item "ev::TYPE::~TYPE" 2129.IX Item "ev::TYPE::~TYPE"
1858.PD 2130.PD
1859The constructor takes a pointer to an object and a method pointer to 2131The constructor (optionally) takes an event loop to associate the watcher
1860the event handler callback to call in this class. The constructor calls 2132with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR.
1861\&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method 2133.Sp
1862before starting it. If you do not specify a loop then the constructor 2134The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the
1863automatically associates the default loop with this watcher. 2135\&\f(CW\*(C`set\*(C'\fR method before starting it.
2136.Sp
2137It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR
2138method to set a callback before you can start the watcher.
2139.Sp
2140(The reason why you have to use a method is a limitation in \*(C+ which does
2141not allow explicit template arguments for constructors).
1864.Sp 2142.Sp
1865The destructor automatically stops the watcher if it is active. 2143The destructor automatically stops the watcher if it is active.
2144.IP "w\->set<class, &class::method> (object *)" 4
2145.IX Item "w->set<class, &class::method> (object *)"
2146This method sets the callback method to call. The method has to have a
2147signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as
2148first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as
2149parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher.
2150.Sp
2151This method synthesizes efficient thunking code to call your method from
2152the C callback that libev requires. If your compiler can inline your
2153callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and
2154your compiler is good :), then the method will be fully inlined into the
2155thunking function, making it as fast as a direct C callback.
2156.Sp
2157Example: simple class declaration and watcher initialisation
2158.Sp
2159.Vb 4
2160\& struct myclass
2161\& {
2162\& void io_cb (ev::io &w, int revents) { }
2163\& }
2164.Ve
2165.Sp
2166.Vb 3
2167\& myclass obj;
2168\& ev::io iow;
2169\& iow.set <myclass, &myclass::io_cb> (&obj);
2170.Ve
2171.IP "w\->set<function> (void *data = 0)" 4
2172.IX Item "w->set<function> (void *data = 0)"
2173Also sets a callback, but uses a static method or plain function as
2174callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's
2175\&\f(CW\*(C`data\*(C'\fR member and is free for you to use.
2176.Sp
2177The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR.
2178.Sp
2179See the method\-\f(CW\*(C`set\*(C'\fR above for more details.
2180.Sp
2181Example:
2182.Sp
2183.Vb 2
2184\& static void io_cb (ev::io &w, int revents) { }
2185\& iow.set <io_cb> ();
2186.Ve
1866.IP "w\->set (struct ev_loop *)" 4 2187.IP "w\->set (struct ev_loop *)" 4
1867.IX Item "w->set (struct ev_loop *)" 2188.IX Item "w->set (struct ev_loop *)"
1868Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only 2189Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
1869do this when the watcher is inactive (and not pending either). 2190do this when the watcher is inactive (and not pending either).
1870.IP "w\->set ([args])" 4 2191.IP "w\->set ([args])" 4
1871.IX Item "w->set ([args])" 2192.IX Item "w->set ([args])"
1872Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be 2193Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be
1873called at least once. Unlike the C counterpart, an active watcher gets 2194called at least once. Unlike the C counterpart, an active watcher gets
1874automatically stopped and restarted. 2195automatically stopped and restarted when reconfiguring it with this
2196method.
1875.IP "w\->start ()" 4 2197.IP "w\->start ()" 4
1876.IX Item "w->start ()" 2198.IX Item "w->start ()"
1877Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the 2199Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
1878constructor already takes the loop. 2200constructor already stores the event loop.
1879.IP "w\->stop ()" 4 2201.IP "w\->stop ()" 4
1880.IX Item "w->stop ()" 2202.IX Item "w->stop ()"
1881Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. 2203Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
1882.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4 2204.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4
1883.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4 2205.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4
… …
1909.Vb 2 2231.Vb 2
1910\& myclass (); 2232\& myclass ();
1911\& } 2233\& }
1912.Ve 2234.Ve
1913.PP 2235.PP
1914.Vb 6 2236.Vb 4
1915\& myclass::myclass (int fd) 2237\& myclass::myclass (int fd)
1916\& : io (this, &myclass::io_cb),
1917\& idle (this, &myclass::idle_cb)
1918\& { 2238\& {
2239\& io .set <myclass, &myclass::io_cb > (this);
2240\& idle.set <myclass, &myclass::idle_cb> (this);
2241.Ve
2242.PP
2243.Vb 2
1919\& io.start (fd, ev::READ); 2244\& io.start (fd, ev::READ);
1920\& } 2245\& }
1921.Ve 2246.Ve
1922.SH "MACRO MAGIC" 2247.SH "MACRO MAGIC"
1923.IX Header "MACRO MAGIC" 2248.IX Header "MACRO MAGIC"
1924Libev can be compiled with a variety of options, the most fundemantal is 2249Libev can be compiled with a variety of options, the most fundemantal is
1925\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines wether (most) functions and 2250\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) functions and
1926callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. 2251callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
1927.PP 2252.PP
1928To make it easier to write programs that cope with either variant, the 2253To make it easier to write programs that cope with either variant, the
1929following macros are defined: 2254following macros are defined:
1930.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 2255.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
… …
1965.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 2290.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
1966.IX Item "EV_DEFAULT, EV_DEFAULT_" 2291.IX Item "EV_DEFAULT, EV_DEFAULT_"
1967Similar to the other two macros, this gives you the value of the default 2292Similar to the other two macros, this gives you the value of the default
1968loop, if multiple loops are supported (\*(L"ev loop default\*(R"). 2293loop, if multiple loops are supported (\*(L"ev loop default\*(R").
1969.PP 2294.PP
1970Example: Declare and initialise a check watcher, working regardless of 2295Example: Declare and initialise a check watcher, utilising the above
1971wether multiple loops are supported or not. 2296macros so it will work regardless of whether multiple loops are supported
2297or not.
1972.PP 2298.PP
1973.Vb 5 2299.Vb 5
1974\& static void 2300\& static void
1975\& check_cb (EV_P_ ev_timer *w, int revents) 2301\& check_cb (EV_P_ ev_timer *w, int revents)
1976\& { 2302\& {
… …
2039.Vb 1 2365.Vb 1
2040\& ev_win32.c required on win32 platforms only 2366\& ev_win32.c required on win32 platforms only
2041.Ve 2367.Ve
2042.PP 2368.PP
2043.Vb 5 2369.Vb 5
2044\& ev_select.c only when select backend is enabled (which is by default) 2370\& ev_select.c only when select backend is enabled (which is enabled by default)
2045\& ev_poll.c only when poll backend is enabled (disabled by default) 2371\& ev_poll.c only when poll backend is enabled (disabled by default)
2046\& ev_epoll.c only when the epoll backend is enabled (disabled by default) 2372\& ev_epoll.c only when the epoll backend is enabled (disabled by default)
2047\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) 2373\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2048\& ev_port.c only when the solaris port backend is enabled (disabled by default) 2374\& ev_port.c only when the solaris port backend is enabled (disabled by default)
2049.Ve 2375.Ve
… …
2170otherwise another method will be used as fallback. This is the preferred 2496otherwise another method will be used as fallback. This is the preferred
2171backend for Solaris 10 systems. 2497backend for Solaris 10 systems.
2172.IP "\s-1EV_USE_DEVPOLL\s0" 4 2498.IP "\s-1EV_USE_DEVPOLL\s0" 4
2173.IX Item "EV_USE_DEVPOLL" 2499.IX Item "EV_USE_DEVPOLL"
2174reserved for future expansion, works like the \s-1USE\s0 symbols above. 2500reserved for future expansion, works like the \s-1USE\s0 symbols above.
2501.IP "\s-1EV_USE_INOTIFY\s0" 4
2502.IX Item "EV_USE_INOTIFY"
2503If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify
2504interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will
2505be detected at runtime.
2175.IP "\s-1EV_H\s0" 4 2506.IP "\s-1EV_H\s0" 4
2176.IX Item "EV_H" 2507.IX Item "EV_H"
2177The name of the \fIev.h\fR header file used to include it. The default if 2508The name of the \fIev.h\fR header file used to include it. The default if
2178undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This 2509undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This
2179can be used to virtually rename the \fIev.h\fR header file in case of conflicts. 2510can be used to virtually rename the \fIev.h\fR header file in case of conflicts.
… …
2197If undefined or defined to \f(CW1\fR, then all event-loop-specific functions 2528If undefined or defined to \f(CW1\fR, then all event-loop-specific functions
2198will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create 2529will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create
2199additional independent event loops. Otherwise there will be no support 2530additional independent event loops. Otherwise there will be no support
2200for multiple event loops and there is no first event loop pointer 2531for multiple event loops and there is no first event loop pointer
2201argument. Instead, all functions act on the single default loop. 2532argument. Instead, all functions act on the single default loop.
2533.IP "\s-1EV_MINPRI\s0" 4
2534.IX Item "EV_MINPRI"
2535.PD 0
2536.IP "\s-1EV_MAXPRI\s0" 4
2537.IX Item "EV_MAXPRI"
2538.PD
2539The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to
2540\&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can
2541provide for more priorities by overriding those symbols (usually defined
2542to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively).
2543.Sp
2544When doing priority-based operations, libev usually has to linearly search
2545all the priorities, so having many of them (hundreds) uses a lot of space
2546and time, so using the defaults of five priorities (\-2 .. +2) is usually
2547fine.
2548.Sp
2549If your embedding app does not need any priorities, defining these both to
2550\&\f(CW0\fR will save some memory and cpu.
2202.IP "\s-1EV_PERIODIC_ENABLE\s0" 4 2551.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
2203.IX Item "EV_PERIODIC_ENABLE" 2552.IX Item "EV_PERIODIC_ENABLE"
2204If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If 2553If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
2554defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2555code.
2556.IP "\s-1EV_IDLE_ENABLE\s0" 4
2557.IX Item "EV_IDLE_ENABLE"
2558If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If
2205defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of 2559defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2206code. 2560code.
2207.IP "\s-1EV_EMBED_ENABLE\s0" 4 2561.IP "\s-1EV_EMBED_ENABLE\s0" 4
2208.IX Item "EV_EMBED_ENABLE" 2562.IX Item "EV_EMBED_ENABLE"
2209If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If 2563If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If
… …
2224.IP "\s-1EV_PID_HASHSIZE\s0" 4 2578.IP "\s-1EV_PID_HASHSIZE\s0" 4
2225.IX Item "EV_PID_HASHSIZE" 2579.IX Item "EV_PID_HASHSIZE"
2226\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by 2580\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by
2227pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more 2581pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more
2228than enough. If you need to manage thousands of children you might want to 2582than enough. If you need to manage thousands of children you might want to
2229increase this value. 2583increase this value (\fImust\fR be a power of two).
2584.IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4
2585.IX Item "EV_INOTIFY_HASHSIZE"
2586\&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by
2587inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR),
2588usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR
2589watchers you might want to increase this value (\fImust\fR be a power of
2590two).
2230.IP "\s-1EV_COMMON\s0" 4 2591.IP "\s-1EV_COMMON\s0" 4
2231.IX Item "EV_COMMON" 2592.IX Item "EV_COMMON"
2232By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining 2593By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
2233this macro to a something else you can include more and other types of 2594this macro to a something else you can include more and other types of
2234members. You have to define it each time you include one of the files, 2595members. You have to define it each time you include one of the files,
… …
2264interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file 2625interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file
2265will be compiled. It is pretty complex because it provides its own header 2626will be compiled. It is pretty complex because it provides its own header
2266file. 2627file.
2267.Sp 2628.Sp
2268The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file 2629The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
2269that everybody includes and which overrides some autoconf choices: 2630that everybody includes and which overrides some configure choices:
2270.Sp 2631.Sp
2271.Vb 4 2632.Vb 9
2633\& #define EV_MINIMAL 1
2272\& #define EV_USE_POLL 0 2634\& #define EV_USE_POLL 0
2273\& #define EV_MULTIPLICITY 0 2635\& #define EV_MULTIPLICITY 0
2274\& #define EV_PERIODICS 0 2636\& #define EV_PERIODIC_ENABLE 0
2637\& #define EV_STAT_ENABLE 0
2638\& #define EV_FORK_ENABLE 0
2275\& #define EV_CONFIG_H <config.h> 2639\& #define EV_CONFIG_H <config.h>
2640\& #define EV_MINPRI 0
2641\& #define EV_MAXPRI 0
2276.Ve 2642.Ve
2277.Sp 2643.Sp
2278.Vb 1 2644.Vb 1
2279\& #include "ev++.h" 2645\& #include "ev++.h"
2280.Ve 2646.Ve
… …
2288.SH "COMPLEXITIES" 2654.SH "COMPLEXITIES"
2289.IX Header "COMPLEXITIES" 2655.IX Header "COMPLEXITIES"
2290In this section the complexities of (many of) the algorithms used inside 2656In this section the complexities of (many of) the algorithms used inside
2291libev will be explained. For complexity discussions about backends see the 2657libev will be explained. For complexity discussions about backends see the
2292documentation for \f(CW\*(C`ev_default_init\*(C'\fR. 2658documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
2659.Sp
2660All of the following are about amortised time: If an array needs to be
2661extended, libev needs to realloc and move the whole array, but this
2662happens asymptotically never with higher number of elements, so O(1) might
2663mean it might do a lengthy realloc operation in rare cases, but on average
2664it is much faster and asymptotically approaches constant time.
2293.RS 4 2665.RS 4
2294.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 2666.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
2295.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 2667.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
2296.PD 0 2668This means that, when you have a watcher that triggers in one hour and
2669there are 100 watchers that would trigger before that then inserting will
2670have to skip those 100 watchers.
2297.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4 2671.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
2298.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 2672.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2673That means that for changing a timer costs less than removing/adding them
2674as only the relative motion in the event queue has to be paid for.
2299.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 2675.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
2300.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" 2676.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2301.IP "Stopping check/prepare/idle watchers: O(1)" 4 2677These just add the watcher into an array or at the head of a list.
2302.IX Item "Stopping check/prepare/idle watchers: O(1)" 2678=item Stopping check/prepare/idle watchers: O(1)
2303.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 4 2679.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
2304.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 2680.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
2681These watchers are stored in lists then need to be walked to find the
2682correct watcher to remove. The lists are usually short (you don't usually
2683have many watchers waiting for the same fd or signal).
2305.IP "Finding the next timer per loop iteration: O(1)" 4 2684.IP "Finding the next timer per loop iteration: O(1)" 4
2306.IX Item "Finding the next timer per loop iteration: O(1)" 2685.IX Item "Finding the next timer per loop iteration: O(1)"
2686.PD 0
2307.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 2687.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
2308.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 2688.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
2689.PD
2690A change means an I/O watcher gets started or stopped, which requires
2691libev to recalculate its status (and possibly tell the kernel).
2309.IP "Activating one watcher: O(1)" 4 2692.IP "Activating one watcher: O(1)" 4
2310.IX Item "Activating one watcher: O(1)" 2693.IX Item "Activating one watcher: O(1)"
2694.PD 0
2695.IP "Priority handling: O(number_of_priorities)" 4
2696.IX Item "Priority handling: O(number_of_priorities)"
2697.PD
2698Priorities are implemented by allocating some space for each
2699priority. When doing priority-based operations, libev usually has to
2700linearly search all the priorities.
2311.RE 2701.RE
2312.RS 4 2702.RS 4
2313.PD
2314.SH "AUTHOR" 2703.SH "AUTHOR"
2315.IX Header "AUTHOR" 2704.IX Header "AUTHOR"
2316Marc Lehmann <libev@schmorp.de>. 2705Marc Lehmann <libev@schmorp.de>.

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