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Revision 1.30 by root, Wed Nov 28 11:27:29 2007 UTC vs.
Revision 1.53 by root, Wed Dec 19 01:59:29 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 "2007-11-28" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH EV 1 "2007-12-19" "perl v5.8.8" "User Contributed Perl Documentation"
133.SH "NAME" 133.SH "NAME"
134libev \- a high performance full\-featured event loop written in C 134libev \- a high performance full\-featured event loop written in C
135.SH "SYNOPSIS" 135.SH "SYNOPSIS"
136.IX Header "SYNOPSIS" 136.IX Header "SYNOPSIS"
137.Vb 1 137.Vb 1
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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
… …
238Libev represents time as a single floating point number, representing the 243Libev represents time as a single floating point number, representing the
239(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
240the 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
241called \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
242to 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
243it, 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.
244.SH "GLOBAL FUNCTIONS" 251.SH "GLOBAL FUNCTIONS"
245.IX Header "GLOBAL FUNCTIONS" 252.IX Header "GLOBAL FUNCTIONS"
246These functions can be called anytime, even before initialising the 253These functions can be called anytime, even before initialising the
247library in any way. 254library in any way.
248.IP "ev_tstamp ev_time ()" 4 255.IP "ev_tstamp ev_time ()" 4
… …
254.IX Item "int ev_version_major ()" 261.IX Item "int ev_version_major ()"
255.PD 0 262.PD 0
256.IP "int ev_version_minor ()" 4 263.IP "int ev_version_minor ()" 4
257.IX Item "int ev_version_minor ()" 264.IX Item "int ev_version_minor ()"
258.PD 265.PD
259You 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
260you 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
261\&\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
262symbols \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
263version of the library your program was compiled against. 270version of the library your program was compiled against.
264.Sp 271.Sp
272These version numbers refer to the \s-1ABI\s0 version of the library, not the
273release version.
274.Sp
265Usually, 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,
266as this indicates an incompatible change. Minor versions are usually 276as this indicates an incompatible change. Minor versions are usually
267compatible to older versions, so a larger minor version alone is usually 277compatible to older versions, so a larger minor version alone is usually
268not a problem. 278not a problem.
269.Sp 279.Sp
270Example: Make sure we haven't accidentally been linked against the wrong 280Example: Make sure we haven't accidentally been linked against the wrong
271version. 281version.
… …
304might be supported on the current system, you would need to look at 314might 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 315\&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for
306recommended ones. 316recommended ones.
307.Sp 317.Sp
308See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. 318See 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))" 4 319.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4
310.IX Item "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" 320.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"
311Sets the allocation function to use (the prototype and semantics are 321Sets the allocation function to use (the prototype is similar \- the
312identical to the realloc C function). It is used to allocate and free 322semantics is identical \- to the realloc C function). It is used to
313memory (no surprises here). If it returns zero when memory needs to be 323allocate and free memory (no surprises here). If it returns zero when
314allocated, the library might abort or take some potentially destructive 324memory needs to be allocated, the library might abort or take some
315action. The default is your system realloc function. 325potentially destructive action. The default is your system realloc
326function.
316.Sp 327.Sp
317You could override this function in high-availability programs to, say, 328You could override this function in high-availability programs to, say,
318free some memory if it cannot allocate memory, to use a special allocator, 329free 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. 330or even to sleep a while and retry until some memory is available.
320.Sp 331.Sp
… …
409or setgid) then libev will \fInot\fR look at the environment variable 420or 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 421\&\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 422override 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 423useful to try out specific backends to test their performance, or to work
413around bugs. 424around bugs.
425.ie n .IP """EVFLAG_FORKCHECK""" 4
426.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4
427.IX Item "EVFLAG_FORKCHECK"
428Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after
429a fork, you can also make libev check for a fork in each iteration by
430enabling this flag.
431.Sp
432This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop,
433and thus this might slow down your event loop if you do a lot of loop
434iterations and little real work, but is usually not noticeable (on my
435Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence
436without a syscall and thus \fIvery\fR fast, but my Linux system also has
437\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster).
438.Sp
439The big advantage of this flag is that you can forget about fork (and
440forget about forgetting to tell libev about forking) when you use this
441flag.
442.Sp
443This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR
444environment variable.
414.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 445.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
415.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 446.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
416.IX Item "EVBACKEND_SELECT (value 1, portable select backend)" 447.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
417This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 448This 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, 449libev tries to roll its own fd_set with no limits on the number of fds,
… …
526Destroys the default loop again (frees all memory and kernel state 557Destroys the default loop again (frees all memory and kernel state
527etc.). 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
528sense, 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
529responsibility to either stop all watchers cleanly yoursef \fIbefore\fR 560responsibility to either stop all watchers cleanly yoursef \fIbefore\fR
530calling this function, or cope with the fact afterwards (which is usually 561calling this function, or cope with the fact afterwards (which is usually
531the 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
532for 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).
533.IP "ev_loop_destroy (loop)" 4 573.IP "ev_loop_destroy (loop)" 4
534.IX Item "ev_loop_destroy (loop)" 574.IX Item "ev_loop_destroy (loop)"
535Like \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
536earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. 576earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR.
537.IP "ev_default_fork ()" 4 577.IP "ev_default_fork ()" 4
… …
559.IP "ev_loop_fork (loop)" 4 599.IP "ev_loop_fork (loop)" 4
560.IX Item "ev_loop_fork (loop)" 600.IX Item "ev_loop_fork (loop)"
561Like \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
562\&\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
563after 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.
564.IP "unsigned int ev_backend (loop)" 4 613.IP "unsigned int ev_backend (loop)" 4
565.IX Item "unsigned int ev_backend (loop)" 614.IX Item "unsigned int ev_backend (loop)"
566Returns 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
567use. 616use.
568.IP "ev_tstamp ev_now (loop)" 4 617.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 648libev 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. 649usually a better approach for this kind of thing.
601.Sp 650.Sp
602Here 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:
603.Sp 652.Sp
604.Vb 18 653.Vb 19
654\& - Before the first iteration, call any pending watchers.
605\& * If there are no active watchers (reference count is zero), return. 655\& * If there are no active watchers (reference count is zero), return.
606\& - Queue prepare watchers and then call all outstanding watchers. 656\& - Queue all prepare watchers and then call all outstanding watchers.
607\& - If we have been forked, recreate the kernel state. 657\& - If we have been forked, recreate the kernel state.
608\& - Update the kernel state with all outstanding changes. 658\& - Update the kernel state with all outstanding changes.
609\& - Update the "event loop time". 659\& - Update the "event loop time".
610\& - Calculate for how long to block. 660\& - Calculate for how long to block.
611\& - Block the process, waiting for any events. 661\& - Block the process, waiting for any events.
… …
854.IP "bool ev_is_pending (ev_TYPE *watcher)" 4 904.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
855.IX Item "bool ev_is_pending (ev_TYPE *watcher)" 905.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
856Returns 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
857events 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
858is 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
859\&\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
860libev (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).
861.IP "callback ev_cb (ev_TYPE *watcher)" 4 912.IP "callback ev_cb (ev_TYPE *watcher)" 4
862.IX Item "callback ev_cb (ev_TYPE *watcher)" 913.IX Item "callback ev_cb (ev_TYPE *watcher)"
863Returns the callback currently set on the watcher. 914Returns the callback currently set on the watcher.
864.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 915.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
865.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 916.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
866Change the callback. You can change the callback at virtually any time 917Change the callback. You can change the callback at virtually any time
867(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.
868.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"
869.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 959.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 960Each 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 961and 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 962to 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 1073it 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. 1074\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
985.PP 1075.PP
986If 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
987play 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
988wether 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
989such 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
990its 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"
991.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
992.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)"
993.PD 0 1108.PD 0
994.IP "ev_io_set (ev_io *, int fd, int events)" 4 1109.IP "ev_io_set (ev_io *, int fd, int events)" 4
995.IX Item "ev_io_set (ev_io *, int fd, int events)" 1110.IX Item "ev_io_set (ev_io *, int fd, int events)"
… …
1048.Ve 1163.Ve
1049.PP 1164.PP
1050The 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,
1051but if multiple timers become ready during the same loop iteration then 1166but if multiple timers become ready during the same loop iteration then
1052order 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"
1053.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
1054.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)"
1055.PD 0 1173.PD 0
1056.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
1057.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)"
… …
1069.IP "ev_timer_again (loop)" 4 1187.IP "ev_timer_again (loop)" 4
1070.IX Item "ev_timer_again (loop)" 1188.IX Item "ev_timer_again (loop)"
1071This will act as if the timer timed out and restart it again if it is 1189This will act as if the timer timed out and restart it again if it is
1072repeating. The exact semantics are: 1190repeating. The exact semantics are:
1073.Sp 1191.Sp
1192If the timer is pending, its pending status is cleared.
1193.Sp
1074If the timer is started but nonrepeating, stop it. 1194If the timer is started but nonrepeating, stop it (as if it timed out).
1075.Sp 1195.Sp
1076If the timer is repeating, either start it if necessary (with the repeat 1196If the timer is repeating, either start it if necessary (with the
1077value), or reset the running timer to the repeat value. 1197\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value.
1078.Sp 1198.Sp
1079This sounds a bit complicated, but here is a useful and typical 1199This sounds a bit complicated, but here is a useful and typical
1080example: Imagine you have a tcp connection and you want a so-called 1200example: 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, 1201timeout, 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 1202seconds 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 1203configure 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 1204\&\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 1205you 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 1206socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will
1087need be. 1207automatically restart it if need be.
1088.Sp 1208.Sp
1089You can also ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR altogether 1209That 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: 1210altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR:
1091.Sp 1211.Sp
1092.Vb 8 1212.Vb 8
1093\& ev_timer_init (timer, callback, 0., 5.); 1213\& ev_timer_init (timer, callback, 0., 5.);
1094\& ev_timer_again (loop, timer); 1214\& ev_timer_again (loop, timer);
1095\& ... 1215\& ...
… …
1098\& ... 1218\& ...
1099\& timer->again = 10.; 1219\& timer->again = 10.;
1100\& ev_timer_again (loop, timer); 1220\& ev_timer_again (loop, timer);
1101.Ve 1221.Ve
1102.Sp 1222.Sp
1103This is more efficient then stopping/starting the timer eahc time you want 1223This is more slightly efficient then stopping/starting the timer each time
1104to modify its timeout value. 1224you want to modify its timeout value.
1105.IP "ev_tstamp repeat [read\-write]" 4 1225.IP "ev_tstamp repeat [read\-write]" 4
1106.IX Item "ev_tstamp repeat [read-write]" 1226.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 1227The 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), 1228or \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. 1229which is also when any modifications are taken into account.
… …
1157but on wallclock time (absolute time). You can tell a periodic watcher 1277but 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 1278to 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 () 1279periodic 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 1280+ 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 1281take 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 1282roughly 10 seconds later).
1163again).
1164.PP 1283.PP
1165They 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
1166triggering an event on eahc midnight, local time. 1285triggering an event on each midnight, local time or other, complicated,
1286rules.
1167.PP 1287.PP
1168As 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
1169time (\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
1170during 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"
1171.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
1172.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)"
1173.PD 0 1296.PD 0
1174.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
1175.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)"
1176.PD 1299.PD
1177Lots 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
1178operation, and we will explain them from simplest to complex: 1301operation, and we will explain them from simplest to complex:
1179.RS 4 1302.RS 4
1180.IP "* absolute timer (interval = reschedule_cb = 0)" 4 1303.IP "* absolute timer (at = time, interval = reschedule_cb = 0)" 4
1181.IX Item "absolute timer (interval = reschedule_cb = 0)" 1304.IX Item "absolute timer (at = time, interval = reschedule_cb = 0)"
1182In this configuration the watcher triggers an event at the wallclock time 1305In 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, 1306\&\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 1307that is, if it is to be run at January 1st 2011 then it will run when the
1185system time reaches or surpasses this time. 1308system time reaches or surpasses this time.
1186.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
1187.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)"
1188In 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
1189\&\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)
1190of any time jumps. 1313and then repeat, regardless of any time jumps.
1191.Sp 1314.Sp
1192This 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
1193time: 1316time:
1194.Sp 1317.Sp
1195.Vb 1 1318.Vb 1
… …
1202by 3600. 1325by 3600.
1203.Sp 1326.Sp
1204Another way to think about it (for the mathematically inclined) is that 1327Another 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 1328\&\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. 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.
1207.IP "* manual reschedule mode (reschedule_cb = callback)" 4 1334.IP "* manual reschedule mode (at and interval ignored, reschedule_cb = callback)" 4
1208.IX Item "manual reschedule mode (reschedule_cb = callback)" 1335.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 1336In 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 1337ignored. Instead, each time the periodic watcher gets scheduled, the
1211reschedule callback will be called with the watcher as first, and the 1338reschedule callback will be called with the watcher as first, and the
1212current time as second argument. 1339current time as second argument.
1213.Sp 1340.Sp
1214\&\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,
1215ever, 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,
1216return \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
1217starting a prepare watcher). 1344starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal).
1218.Sp 1345.Sp
1219Its 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,
1220ev_tstamp now)\*(C'\fR, e.g.: 1347ev_tstamp now)\*(C'\fR, e.g.:
1221.Sp 1348.Sp
1222.Vb 4 1349.Vb 4
… …
1246.IX Item "ev_periodic_again (loop, ev_periodic *)" 1373.IX Item "ev_periodic_again (loop, ev_periodic *)"
1247Simply stops and restarts the periodic watcher again. This is only useful 1374Simply stops and restarts the periodic watcher again. This is only useful
1248when you changed some parameters or the reschedule callback would return 1375when 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 1376a different time than the last time it was called (e.g. in a crond like
1250program 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.
1251.IP "ev_tstamp interval [read\-write]" 4 1385.IP "ev_tstamp interval [read\-write]" 4
1252.IX Item "ev_tstamp interval [read-write]" 1386.IX Item "ev_tstamp interval [read-write]"
1253The current interval value. Can be modified any time, but changes only 1387The 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 1388take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being
1255called. 1389called.
1256.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
1257.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]"
1258The current reschedule callback, or \f(CW0\fR, if this functionality is 1392The current reschedule callback, or \f(CW0\fR, if this functionality is
1259switched 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
1260the 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.
1261.PP 1399.PP
1262Example: Call a callback every hour, or, more precisely, whenever the 1400Example: Call a callback every hour, or, more precisely, whenever the
1263system clock is divisible by 3600. The callback invocation times have 1401system clock is divisible by 3600. The callback invocation times have
1264potentially a lot of jittering, but good long-term stability. 1402potentially a lot of jittering, but good long-term stability.
1265.PP 1403.PP
… …
1315first watcher gets started will libev actually register a signal watcher 1453first watcher gets started will libev actually register a signal watcher
1316with 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
1317as 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
1318watcher 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
1319\&\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"
1320.IP "ev_signal_init (ev_signal *, callback, int signum)" 4 1461.IP "ev_signal_init (ev_signal *, callback, int signum)" 4
1321.IX Item "ev_signal_init (ev_signal *, callback, int signum)" 1462.IX Item "ev_signal_init (ev_signal *, callback, int signum)"
1322.PD 0 1463.PD 0
1323.IP "ev_signal_set (ev_signal *, int signum)" 4 1464.IP "ev_signal_set (ev_signal *, int signum)" 4
1324.IX Item "ev_signal_set (ev_signal *, int signum)" 1465.IX Item "ev_signal_set (ev_signal *, int signum)"
… …
1331.ie n .Sh """ev_child"" \- watch out for process status changes" 1472.ie n .Sh """ev_child"" \- watch out for process status changes"
1332.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"
1333.IX Subsection "ev_child - watch out for process status changes" 1474.IX Subsection "ev_child - watch out for process status changes"
1334Child 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
1335some 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"
1336.IP "ev_child_init (ev_child *, callback, int pid)" 4 1480.IP "ev_child_init (ev_child *, callback, int pid)" 4
1337.IX Item "ev_child_init (ev_child *, callback, int pid)" 1481.IX Item "ev_child_init (ev_child *, callback, int pid)"
1338.PD 0 1482.PD 0
1339.IP "ev_child_set (ev_child *, int pid)" 4 1483.IP "ev_child_set (ev_child *, int pid)" 4
1340.IX Item "ev_child_set (ev_child *, int pid)" 1484.IX Item "ev_child_set (ev_child *, int pid)"
… …
1382not exist\*(R" is a status change like any other. The condition \*(L"path does 1526not 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 1527not 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 1528otherwise always forced to be at least one) and all the other fields of
1385the stat buffer having unspecified contents. 1529the stat buffer having unspecified contents.
1386.PP 1530.PP
1531The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is
1532relative and your working directory changes, the behaviour is undefined.
1533.PP
1387Since there is no standard to do this, the portable implementation simply 1534Since there is no standard to do this, the portable implementation simply
1388calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You 1535calls \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 1536can specify a recommended polling interval for this case. If you specify
1390a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, 1537a 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 1538unspecified default\fR value will be used (which you can expect to be around
… …
1402reader). 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
1403semantics 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
1404to 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
1405usually detected immediately, and if the file exists there will be no 1552usually detected immediately, and if the file exists there will be no
1406polling. 1553polling.
1554.PP
1555\fIWatcher-Specific Functions and Data Members\fR
1556.IX Subsection "Watcher-Specific Functions and Data Members"
1407.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
1408.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)"
1409.PD 0 1559.PD 0
1410.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
1411.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)"
… …
1472\& ev_stat_start (loop, &passwd); 1622\& ev_stat_start (loop, &passwd);
1473.Ve 1623.Ve
1474.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..."
1475.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..."
1476.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..."
1477Idle watchers trigger events when there are no other events are pending 1627Idle watchers trigger events when no other events of the same or higher
1478(prepare, check and other idle watchers do not count). That is, as long 1628priority are pending (prepare, check and other idle watchers do not
1479as your process is busy handling sockets or timeouts (or even signals, 1629count).
1480imagine) it will not be triggered. But when your process is idle all idle 1630.PP
1481watchers 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
1482until stopped, that is, or your process receives more events and becomes 1635iteration \- until stopped, that is, or your process receives more events
1483busy. 1636and becomes busy again with higher priority stuff.
1484.PP 1637.PP
1485The 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
1486active, the process will not block when waiting for new events. 1639active, the process will not block when waiting for new events.
1487.PP 1640.PP
1488Apart from keeping your process non-blocking (which is a useful 1641Apart from keeping your process non-blocking (which is a useful
1489effect 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
1490\&\*(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
1491event 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"
1492.IP "ev_idle_init (ev_signal *, callback)" 4 1648.IP "ev_idle_init (ev_signal *, callback)" 4
1493.IX Item "ev_idle_init (ev_signal *, callback)" 1649.IX Item "ev_idle_init (ev_signal *, callback)"
1494Initialises and configures the idle watcher \- it has no parameters of any 1650Initialises and configures the idle watcher \- it has no parameters of any
1495kind. 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,
1496believe me. 1652believe me.
… …
1551are 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
1552with 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
1553of 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
1554loop from blocking if lower-priority coroutines are active, thus mapping 1710loop from blocking if lower-priority coroutines are active, thus mapping
1555low-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"
1556.IP "ev_prepare_init (ev_prepare *, callback)" 4 1725.IP "ev_prepare_init (ev_prepare *, callback)" 4
1557.IX Item "ev_prepare_init (ev_prepare *, callback)" 1726.IX Item "ev_prepare_init (ev_prepare *, callback)"
1558.PD 0 1727.PD 0
1559.IP "ev_check_init (ev_check *, callback)" 4 1728.IP "ev_check_init (ev_check *, callback)" 4
1560.IX Item "ev_check_init (ev_check *, callback)" 1729.IX Item "ev_check_init (ev_check *, callback)"
1561.PD 1730.PD
1562Initialises and configures the prepare or check watcher \- they have no 1731Initialises and configures the prepare or check watcher \- they have no
1563parameters 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
1564macros, but using them is utterly, utterly and completely pointless. 1733macros, but using them is utterly, utterly and completely pointless.
1565.PP 1734.PP
1566Example: 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
1567and 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,
1568in 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
1569pseudo-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.
1570.PP 1747.PP
1571.Vb 2 1748.Vb 2
1572\& static ev_io iow [nfd]; 1749\& static ev_io iow [nfd];
1573\& static ev_timer tw; 1750\& static ev_timer tw;
1574.Ve 1751.Ve
1575.PP 1752.PP
1576.Vb 9 1753.Vb 4
1577\& static void 1754\& static void
1578\& io_cb (ev_loop *loop, ev_io *w, int revents) 1755\& io_cb (ev_loop *loop, ev_io *w, int revents)
1579\& { 1756\& {
1580\& // set the relevant poll flags
1581\& // could also call adns_processreadable etc. here
1582\& struct pollfd *fd = (struct pollfd *)w->data;
1583\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1584\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1585\& } 1757\& }
1586.Ve 1758.Ve
1587.PP 1759.PP
1588.Vb 7 1760.Vb 8
1589\& // create io watchers for each fd and a timer before blocking 1761\& // create io watchers for each fd and a timer before blocking
1590\& static void 1762\& static void
1591\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) 1763\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1592\& { 1764\& {
1593\& int timeout = 3600000;truct pollfd fds [nfd]; 1765\& int timeout = 3600000;
1766\& struct pollfd fds [nfd];
1594\& // actual code will need to loop here and realloc etc. 1767\& // actual code will need to loop here and realloc etc.
1595\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); 1768\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1596.Ve 1769.Ve
1597.PP 1770.PP
1598.Vb 3 1771.Vb 3
… …
1600\& ev_timer_init (&tw, 0, timeout * 1e-3); 1773\& ev_timer_init (&tw, 0, timeout * 1e-3);
1601\& ev_timer_start (loop, &tw); 1774\& ev_timer_start (loop, &tw);
1602.Ve 1775.Ve
1603.PP 1776.PP
1604.Vb 6 1777.Vb 6
1605\& // create on ev_io per pollfd 1778\& // create one ev_io per pollfd
1606\& for (int i = 0; i < nfd; ++i) 1779\& for (int i = 0; i < nfd; ++i)
1607\& { 1780\& {
1608\& ev_io_init (iow + i, io_cb, fds [i].fd, 1781\& ev_io_init (iow + i, io_cb, fds [i].fd,
1609\& ((fds [i].events & POLLIN ? EV_READ : 0) 1782\& ((fds [i].events & POLLIN ? EV_READ : 0)
1610\& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); 1783\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1611.Ve 1784.Ve
1612.PP 1785.PP
1613.Vb 5 1786.Vb 4
1614\& fds [i].revents = 0; 1787\& fds [i].revents = 0;
1615\& iow [i].data = fds + i;
1616\& ev_io_start (loop, iow + i); 1788\& ev_io_start (loop, iow + i);
1617\& } 1789\& }
1618\& } 1790\& }
1619.Ve 1791.Ve
1620.PP 1792.PP
… …
1624\& adns_check_cb (ev_loop *loop, ev_check *w, int revents) 1796\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1625\& { 1797\& {
1626\& ev_timer_stop (loop, &tw); 1798\& ev_timer_stop (loop, &tw);
1627.Ve 1799.Ve
1628.PP 1800.PP
1629.Vb 2 1801.Vb 8
1630\& 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
1631\& ev_io_stop (loop, iow + i); 1814\& ev_io_stop (loop, iow + i);
1815\& }
1632.Ve 1816.Ve
1633.PP 1817.PP
1634.Vb 2 1818.Vb 2
1635\& 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;
1636\& } 1903\& }
1637.Ve 1904.Ve
1638.ie n .Sh """ev_embed"" \- when one backend isn't enough..." 1905.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1639.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..."
1640.IX Subsection "ev_embed - when one backend isn't enough..." 1907.IX Subsection "ev_embed - when one backend isn't enough..."
… …
1709\& ev_embed_start (loop_hi, &embed); 1976\& ev_embed_start (loop_hi, &embed);
1710\& } 1977\& }
1711\& else 1978\& else
1712\& loop_lo = loop_hi; 1979\& loop_lo = loop_hi;
1713.Ve 1980.Ve
1981.PP
1982\fIWatcher-Specific Functions and Data Members\fR
1983.IX Subsection "Watcher-Specific Functions and Data Members"
1714.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
1715.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)"
1716.PD 0 1986.PD 0
1717.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
1718.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)"
… …
1738\&\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
1739event 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,
1740and 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
1741\&\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
1742handlers 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"
1743.IP "ev_fork_init (ev_signal *, callback)" 4 2016.IP "ev_fork_init (ev_signal *, callback)" 4
1744.IX Item "ev_fork_init (ev_signal *, callback)" 2017.IX Item "ev_fork_init (ev_signal *, callback)"
1745Initialises and configures the fork watcher \- it has no parameters of any 2018Initialises and configures the fork watcher \- it has no parameters of any
1746kind. 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,
1747believe me. 2020believe me.
… …
1824.PP 2097.PP
1825.Vb 1 2098.Vb 1
1826\& #include <ev++.h> 2099\& #include <ev++.h>
1827.Ve 2100.Ve
1828.PP 2101.PP
1829(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
1830and puts all of its definitions (many of them macros) into the global 2103of them macros) into the global namespace. All \*(C+ specific things are
1831namespace. 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.
1832.PP 2106.PP
1833It 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+
1834\&\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).
1835.PP 2117.PP
1836Here 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:
1837.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
1838.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
1839.IX Item "ev::READ, ev::WRITE etc." 2121.IX Item "ev::READ, ev::WRITE etc."
… …
1851which 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
1852defines by many implementations. 2134defines by many implementations.
1853.Sp 2135.Sp
1854All of those classes have these methods: 2136All of those classes have these methods:
1855.RS 4 2137.RS 4
1856.IP "ev::TYPE::TYPE (object *, object::method *)" 4 2138.IP "ev::TYPE::TYPE ()" 4
1857.IX Item "ev::TYPE::TYPE (object *, object::method *)" 2139.IX Item "ev::TYPE::TYPE ()"
1858.PD 0 2140.PD 0
1859.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 2141.IP "ev::TYPE::TYPE (struct ev_loop *)" 4
1860.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 2142.IX Item "ev::TYPE::TYPE (struct ev_loop *)"
1861.IP "ev::TYPE::~TYPE" 4 2143.IP "ev::TYPE::~TYPE" 4
1862.IX Item "ev::TYPE::~TYPE" 2144.IX Item "ev::TYPE::~TYPE"
1863.PD 2145.PD
1864The constructor takes a pointer to an object and a method pointer to 2146The constructor (optionally) takes an event loop to associate the watcher
1865the 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.
1866\&\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
1867before 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
1868automatically 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).
1869.Sp 2157.Sp
1870The 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
1871.IP "w\->set (struct ev_loop *)" 4 2202.IP "w\->set (struct ev_loop *)" 4
1872.IX Item "w->set (struct ev_loop *)" 2203.IX Item "w->set (struct ev_loop *)"
1873Associates 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
1874do this when the watcher is inactive (and not pending either). 2205do this when the watcher is inactive (and not pending either).
1875.IP "w\->set ([args])" 4 2206.IP "w\->set ([args])" 4
1876.IX Item "w->set ([args])" 2207.IX Item "w->set ([args])"
1877Basically 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
1878called at least once. Unlike the C counterpart, an active watcher gets 2209called at least once. Unlike the C counterpart, an active watcher gets
1879automatically stopped and restarted. 2210automatically stopped and restarted when reconfiguring it with this
2211method.
1880.IP "w\->start ()" 4 2212.IP "w\->start ()" 4
1881.IX Item "w->start ()" 2213.IX Item "w->start ()"
1882Starts 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
1883constructor already takes the loop. 2215constructor already stores the event loop.
1884.IP "w\->stop ()" 4 2216.IP "w\->stop ()" 4
1885.IX Item "w->stop ()" 2217.IX Item "w->stop ()"
1886Stops 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.
1887.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
1888.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
1889.IX Item "w->again () ev::timer, ev::periodic only" 2221.IX Item "w->again () (ev::timer, ev::periodic only)"
1890For \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
1891\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. 2223\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function.
1892.ie n .IP "w\->sweep () ""ev::embed"" only" 4 2224.ie n .IP "w\->sweep () (""ev::embed"" only)" 4
1893.el .IP "w\->sweep () \f(CWev::embed\fR only" 4 2225.el .IP "w\->sweep () (\f(CWev::embed\fR only)" 4
1894.IX Item "w->sweep () ev::embed only" 2226.IX Item "w->sweep () (ev::embed only)"
1895Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. 2227Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR.
1896.ie n .IP "w\->update () ""ev::stat"" only" 4 2228.ie n .IP "w\->update () (""ev::stat"" only)" 4
1897.el .IP "w\->update () \f(CWev::stat\fR only" 4 2229.el .IP "w\->update () (\f(CWev::stat\fR only)" 4
1898.IX Item "w->update () ev::stat only" 2230.IX Item "w->update () (ev::stat only)"
1899Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. 2231Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR.
1900.RE 2232.RE
1901.RS 4 2233.RS 4
1902.RE 2234.RE
1903.PP 2235.PP
… …
1914.Vb 2 2246.Vb 2
1915\& myclass (); 2247\& myclass ();
1916\& } 2248\& }
1917.Ve 2249.Ve
1918.PP 2250.PP
1919.Vb 6 2251.Vb 4
1920\& myclass::myclass (int fd) 2252\& myclass::myclass (int fd)
1921\& : io (this, &myclass::io_cb),
1922\& idle (this, &myclass::idle_cb)
1923\& { 2253\& {
2254\& io .set <myclass, &myclass::io_cb > (this);
2255\& idle.set <myclass, &myclass::idle_cb> (this);
2256.Ve
2257.PP
2258.Vb 2
1924\& io.start (fd, ev::READ); 2259\& io.start (fd, ev::READ);
1925\& } 2260\& }
1926.Ve 2261.Ve
1927.SH "MACRO MAGIC" 2262.SH "MACRO MAGIC"
1928.IX Header "MACRO MAGIC" 2263.IX Header "MACRO MAGIC"
1929Libev can be compiled with a variety of options, the most fundemantal is 2264Libev can be compiled with a variety of options, the most fundamantal
1930\&\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)
1931callbacks 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.
1932.PP 2267.PP
1933To 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
1934following macros are defined: 2269following macros are defined:
1935.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 2270.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
1936.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 2271.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4
… …
1970.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 2305.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
1971.IX Item "EV_DEFAULT, EV_DEFAULT_" 2306.IX Item "EV_DEFAULT, EV_DEFAULT_"
1972Similar 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
1973loop, if multiple loops are supported (\*(L"ev loop default\*(R"). 2308loop, if multiple loops are supported (\*(L"ev loop default\*(R").
1974.PP 2309.PP
1975Example: Declare and initialise a check watcher, working regardless of 2310Example: Declare and initialise a check watcher, utilising the above
1976wether multiple loops are supported or not. 2311macros so it will work regardless of whether multiple loops are supported
2312or not.
1977.PP 2313.PP
1978.Vb 5 2314.Vb 5
1979\& static void 2315\& static void
1980\& check_cb (EV_P_ ev_timer *w, int revents) 2316\& check_cb (EV_P_ ev_timer *w, int revents)
1981\& { 2317\& {
… …
2044.Vb 1 2380.Vb 1
2045\& ev_win32.c required on win32 platforms only 2381\& ev_win32.c required on win32 platforms only
2046.Ve 2382.Ve
2047.PP 2383.PP
2048.Vb 5 2384.Vb 5
2049\& 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)
2050\& 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)
2051\& 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)
2052\& 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)
2053\& 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)
2054.Ve 2390.Ve
… …
2207If 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
2208will 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
2209additional independent event loops. Otherwise there will be no support 2545additional independent event loops. Otherwise there will be no support
2210for multiple event loops and there is no first event loop pointer 2546for multiple event loops and there is no first event loop pointer
2211argument. 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.
2212.IP "\s-1EV_PERIODIC_ENABLE\s0" 4 2566.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
2213.IX Item "EV_PERIODIC_ENABLE" 2567.IX Item "EV_PERIODIC_ENABLE"
2214If 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
2215defined 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
2216code. 2575code.
2217.IP "\s-1EV_EMBED_ENABLE\s0" 4 2576.IP "\s-1EV_EMBED_ENABLE\s0" 4
2218.IX Item "EV_EMBED_ENABLE" 2577.IX Item "EV_EMBED_ENABLE"
2219If 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
… …
2270and the way callbacks are invoked and set. Must expand to a struct member 2629and the way callbacks are invoked and set. Must expand to a struct member
2271definition and a statement, respectively. See the \fIev.v\fR header file for 2630definition and a statement, respectively. See the \fIev.v\fR header file for
2272their default definitions. One possible use for overriding these is to 2631their default definitions. One possible use for overriding these is to
2273avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use 2632avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
2274method calls instead of plain function calls in \*(C+. 2633method calls instead of plain function calls in \*(C+.
2634.Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0"
2635.IX Subsection "EXPORTED API SYMBOLS"
2636If you need to re-export the \s-1API\s0 (e.g. via a dll) and you need a list of
2637exported symbols, you can use the provided \fISymbol.*\fR files which list
2638all public symbols, one per line:
2639.Sp
2640.Vb 2
2641\& Symbols.ev for libev proper
2642\& Symbols.event for the libevent emulation
2643.Ve
2644.Sp
2645This can also be used to rename all public symbols to avoid clashes with
2646multiple versions of libev linked together (which is obviously bad in
2647itself, but sometimes it is inconvinient to avoid this).
2648.Sp
2649A sed comamnd like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to
2650include before including \fIev.h\fR:
2651.Sp
2652.Vb 1
2653\& <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
2654.Ve
2655.Sp
2656This would create a file \fIwrap.h\fR which essentially looks like this:
2657.Sp
2658.Vb 4
2659\& #define ev_backend myprefix_ev_backend
2660\& #define ev_check_start myprefix_ev_check_start
2661\& #define ev_check_stop myprefix_ev_check_stop
2662\& ...
2663.Ve
2275.Sh "\s-1EXAMPLES\s0" 2664.Sh "\s-1EXAMPLES\s0"
2276.IX Subsection "EXAMPLES" 2665.IX Subsection "EXAMPLES"
2277For a real-world example of a program the includes libev 2666For a real-world example of a program the includes libev
2278verbatim, you can have a look at the \s-1EV\s0 perl module 2667verbatim, you can have a look at the \s-1EV\s0 perl module
2279(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in 2668(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in
… …
2281interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file 2670interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file
2282will be compiled. It is pretty complex because it provides its own header 2671will be compiled. It is pretty complex because it provides its own header
2283file. 2672file.
2284.Sp 2673.Sp
2285The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file 2674The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
2286that everybody includes and which overrides some autoconf choices: 2675that everybody includes and which overrides some configure choices:
2287.Sp 2676.Sp
2288.Vb 4 2677.Vb 9
2678\& #define EV_MINIMAL 1
2289\& #define EV_USE_POLL 0 2679\& #define EV_USE_POLL 0
2290\& #define EV_MULTIPLICITY 0 2680\& #define EV_MULTIPLICITY 0
2291\& #define EV_PERIODICS 0 2681\& #define EV_PERIODIC_ENABLE 0
2682\& #define EV_STAT_ENABLE 0
2683\& #define EV_FORK_ENABLE 0
2292\& #define EV_CONFIG_H <config.h> 2684\& #define EV_CONFIG_H <config.h>
2685\& #define EV_MINPRI 0
2686\& #define EV_MAXPRI 0
2293.Ve 2687.Ve
2294.Sp 2688.Sp
2295.Vb 1 2689.Vb 1
2296\& #include "ev++.h" 2690\& #include "ev++.h"
2297.Ve 2691.Ve
… …
2305.SH "COMPLEXITIES" 2699.SH "COMPLEXITIES"
2306.IX Header "COMPLEXITIES" 2700.IX Header "COMPLEXITIES"
2307In this section the complexities of (many of) the algorithms used inside 2701In this section the complexities of (many of) the algorithms used inside
2308libev will be explained. For complexity discussions about backends see the 2702libev will be explained. For complexity discussions about backends see the
2309documentation for \f(CW\*(C`ev_default_init\*(C'\fR. 2703documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
2704.Sp
2705All of the following are about amortised time: If an array needs to be
2706extended, libev needs to realloc and move the whole array, but this
2707happens asymptotically never with higher number of elements, so O(1) might
2708mean it might do a lengthy realloc operation in rare cases, but on average
2709it is much faster and asymptotically approaches constant time.
2310.RS 4 2710.RS 4
2311.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 2711.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
2312.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 2712.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
2313.PD 0 2713This means that, when you have a watcher that triggers in one hour and
2714there are 100 watchers that would trigger before that then inserting will
2715have to skip those 100 watchers.
2314.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4 2716.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
2315.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 2717.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2718That means that for changing a timer costs less than removing/adding them
2719as only the relative motion in the event queue has to be paid for.
2316.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 2720.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
2317.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" 2721.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2318.IP "Stopping check/prepare/idle watchers: O(1)" 4 2722These just add the watcher into an array or at the head of a list.
2319.IX Item "Stopping check/prepare/idle watchers: O(1)" 2723=item Stopping check/prepare/idle watchers: O(1)
2320.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 2724.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
2321.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" 2725.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
2726These watchers are stored in lists then need to be walked to find the
2727correct watcher to remove. The lists are usually short (you don't usually
2728have many watchers waiting for the same fd or signal).
2322.IP "Finding the next timer per loop iteration: O(1)" 4 2729.IP "Finding the next timer per loop iteration: O(1)" 4
2323.IX Item "Finding the next timer per loop iteration: O(1)" 2730.IX Item "Finding the next timer per loop iteration: O(1)"
2731.PD 0
2324.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 2732.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
2325.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 2733.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
2734.PD
2735A change means an I/O watcher gets started or stopped, which requires
2736libev to recalculate its status (and possibly tell the kernel).
2326.IP "Activating one watcher: O(1)" 4 2737.IP "Activating one watcher: O(1)" 4
2327.IX Item "Activating one watcher: O(1)" 2738.IX Item "Activating one watcher: O(1)"
2739.PD 0
2740.IP "Priority handling: O(number_of_priorities)" 4
2741.IX Item "Priority handling: O(number_of_priorities)"
2742.PD
2743Priorities are implemented by allocating some space for each
2744priority. When doing priority-based operations, libev usually has to
2745linearly search all the priorities.
2328.RE 2746.RE
2329.RS 4 2747.RS 4
2330.PD
2331.SH "AUTHOR" 2748.SH "AUTHOR"
2332.IX Header "AUTHOR" 2749.IX Header "AUTHOR"
2333Marc Lehmann <libev@schmorp.de>. 2750Marc Lehmann <libev@schmorp.de>.

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