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Revision 1.16 by root, Sat Nov 24 10:19:14 2007 UTC vs.
Revision 1.41 by root, Fri Dec 7 20:13:09 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 "2007-11-24" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH "<STANDARD INPUT>" 1 "2007-12-07" "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
138\& #include <ev.h> 138\& #include <ev.h>
139.Ve 139.Ve
140.SH "EXAMPLE PROGRAM"
141.IX Header "EXAMPLE PROGRAM"
142.Vb 1
143\& #include <ev.h>
144.Ve
145.PP
146.Vb 2
147\& ev_io stdin_watcher;
148\& ev_timer timeout_watcher;
149.Ve
150.PP
151.Vb 8
152\& /* called when data readable on stdin */
153\& static void
154\& stdin_cb (EV_P_ struct ev_io *w, int revents)
155\& {
156\& /* puts ("stdin ready"); */
157\& ev_io_stop (EV_A_ w); /* just a syntax example */
158\& ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
159\& }
160.Ve
161.PP
162.Vb 6
163\& static void
164\& timeout_cb (EV_P_ struct ev_timer *w, int revents)
165\& {
166\& /* puts ("timeout"); */
167\& ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
168\& }
169.Ve
170.PP
171.Vb 4
172\& int
173\& main (void)
174\& {
175\& struct ev_loop *loop = ev_default_loop (0);
176.Ve
177.PP
178.Vb 3
179\& /* initialise an io watcher, then start it */
180\& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
181\& ev_io_start (loop, &stdin_watcher);
182.Ve
183.PP
184.Vb 3
185\& /* simple non-repeating 5.5 second timeout */
186\& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
187\& ev_timer_start (loop, &timeout_watcher);
188.Ve
189.PP
190.Vb 2
191\& /* loop till timeout or data ready */
192\& ev_loop (loop, 0);
193.Ve
194.PP
195.Vb 2
196\& return 0;
197\& }
198.Ve
140.SH "DESCRIPTION" 199.SH "DESCRIPTION"
141.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
142Libev 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
143file descriptor being readable or a timeout occuring), and it will manage 206file descriptor being readable or a timeout occuring), and it will manage
144these event sources and provide your program with events. 207these event sources and provide your program with events.
145.PP 208.PP
146To 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
… …
151watchers\fR, which are relatively small C structures you initialise with the 214watchers\fR, which are relatively small C structures you initialise with the
152details 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
153watcher. 216watcher.
154.SH "FEATURES" 217.SH "FEATURES"
155.IX Header "FEATURES" 218.IX Header "FEATURES"
156Libev supports select, poll, the linux-specific epoll and the bsd-specific 219Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the
157kqueue mechanisms for file descriptor events, relative timers, absolute 220BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms
158timers with customised rescheduling, signal events, process status change 221for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface
159events (related to \s-1SIGCHLD\s0), and event watchers dealing with the event 222(for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers
160loop mechanism itself (idle, prepare and check watchers). It also is quite 223with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals
161fast (see this benchmark comparing 224(\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event
162it to libevent for example). 225watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR,
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
227file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events
228(\f(CW\*(C`ev_fork\*(C'\fR).
229.PP
230It also is quite fast (see this
231benchmark comparing it to libevent
232for example).
163.SH "CONVENTIONS" 233.SH "CONVENTIONS"
164.IX Header "CONVENTIONS" 234.IX Header "CONVENTIONS"
165Libev is very configurable. In this manual the default configuration 235Libev is very configurable. In this manual the default configuration will
166will be described, which supports multiple event loops. For more info 236be described, which supports multiple event loops. For more info about
167about various configuration options please have a look at the file 237various configuration options please have a look at \fB\s-1EMBED\s0\fR section in
168\&\fI\s-1README\s0.embed\fR in the libev distribution. If libev was configured without 238this manual. If libev was configured without support for multiple event
169support for multiple event loops, then all functions taking an initial 239loops, then all functions taking an initial argument of name \f(CW\*(C`loop\*(C'\fR
170argument of name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) 240(which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have this argument.
171will not have this argument.
172.SH "TIME REPRESENTATION" 241.SH "TIME REPRESENTATION"
173.IX Header "TIME REPRESENTATION" 242.IX Header "TIME REPRESENTATION"
174Libev represents time as a single floating point number, representing the 243Libev represents time as a single floating point number, representing the
175(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
176the 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
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201Usually, it's a good idea to terminate if the major versions mismatch, 270Usually, it's a good idea to terminate if the major versions mismatch,
202as this indicates an incompatible change. Minor versions are usually 271as this indicates an incompatible change. Minor versions are usually
203compatible to older versions, so a larger minor version alone is usually 272compatible to older versions, so a larger minor version alone is usually
204not a problem. 273not a problem.
205.Sp 274.Sp
206Example: make sure we haven't accidentally been linked against the wrong 275Example: Make sure we haven't accidentally been linked against the wrong
207version: 276version.
208.Sp 277.Sp
209.Vb 3 278.Vb 3
210\& assert (("libev version mismatch", 279\& assert (("libev version mismatch",
211\& ev_version_major () == EV_VERSION_MAJOR 280\& ev_version_major () == EV_VERSION_MAJOR
212\& && ev_version_minor () >= EV_VERSION_MINOR)); 281\& && ev_version_minor () >= EV_VERSION_MINOR));
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242recommended ones. 311recommended ones.
243.Sp 312.Sp
244See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. 313See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.
245.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 314.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4
246.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" 315.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"
247Sets the allocation function to use (the prototype is similar to the 316Sets the allocation function to use (the prototype is similar \- the
248realloc C function, the semantics are identical). It is used to allocate 317semantics is identical \- to the realloc C function). It is used to
249and free memory (no surprises here). If it returns zero when memory 318allocate and free memory (no surprises here). If it returns zero when
250needs to be allocated, the library might abort or take some potentially 319memory needs to be allocated, the library might abort or take some
251destructive action. The default is your system realloc function. 320potentially destructive action. The default is your system realloc
321function.
252.Sp 322.Sp
253You could override this function in high-availability programs to, say, 323You could override this function in high-availability programs to, say,
254free some memory if it cannot allocate memory, to use a special allocator, 324free some memory if it cannot allocate memory, to use a special allocator,
255or even to sleep a while and retry until some memory is available. 325or even to sleep a while and retry until some memory is available.
256.Sp 326.Sp
257Example: replace the libev allocator with one that waits a bit and then 327Example: Replace the libev allocator with one that waits a bit and then
258retries: better than mine). 328retries).
259.Sp 329.Sp
260.Vb 6 330.Vb 6
261\& static void * 331\& static void *
262\& persistent_realloc (void *ptr, long size) 332\& persistent_realloc (void *ptr, size_t size)
263\& { 333\& {
264\& for (;;) 334\& for (;;)
265\& { 335\& {
266\& void *newptr = realloc (ptr, size); 336\& void *newptr = realloc (ptr, size);
267.Ve 337.Ve
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289callback is set, then libev will expect it to remedy the sitution, no 359callback is set, then libev will expect it to remedy the sitution, no
290matter what, when it returns. That is, libev will generally retry the 360matter what, when it returns. That is, libev will generally retry the
291requested operation, or, if the condition doesn't go away, do bad stuff 361requested operation, or, if the condition doesn't go away, do bad stuff
292(such as abort). 362(such as abort).
293.Sp 363.Sp
294Example: do the same thing as libev does internally: 364Example: This is basically the same thing that libev does internally, too.
295.Sp 365.Sp
296.Vb 6 366.Vb 6
297\& static void 367\& static void
298\& fatal_error (const char *msg) 368\& fatal_error (const char *msg)
299\& { 369\& {
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345or setgid) then libev will \fInot\fR look at the environment variable 415or setgid) then libev will \fInot\fR look at the environment variable
346\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will 416\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will
347override the flags completely if it is found in the environment. This is 417override the flags completely if it is found in the environment. This is
348useful to try out specific backends to test their performance, or to work 418useful to try out specific backends to test their performance, or to work
349around bugs. 419around bugs.
420.ie n .IP """EVFLAG_FORKCHECK""" 4
421.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4
422.IX Item "EVFLAG_FORKCHECK"
423Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after
424a fork, you can also make libev check for a fork in each iteration by
425enabling this flag.
426.Sp
427This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop,
428and thus this might slow down your event loop if you do a lot of loop
429iterations and little real work, but is usually not noticeable (on my
430Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence
431without a syscall and thus \fIvery\fR fast, but my Linux system also has
432\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster).
433.Sp
434The big advantage of this flag is that you can forget about fork (and
435forget about forgetting to tell libev about forking) when you use this
436flag.
437.Sp
438This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR
439environment variable.
350.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 440.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
351.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 441.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
352.IX Item "EVBACKEND_SELECT (value 1, portable select backend)" 442.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
353This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 443This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as
354libev tries to roll its own fd_set with no limits on the number of fds, 444libev tries to roll its own fd_set with no limits on the number of fds,
… …
448Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is 538Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is
449always distinct from the default loop. Unlike the default loop, it cannot 539always distinct from the default loop. Unlike the default loop, it cannot
450handle signal and child watchers, and attempts to do so will be greeted by 540handle signal and child watchers, and attempts to do so will be greeted by
451undefined behaviour (or a failed assertion if assertions are enabled). 541undefined behaviour (or a failed assertion if assertions are enabled).
452.Sp 542.Sp
453Example: try to create a event loop that uses epoll and nothing else. 543Example: Try to create a event loop that uses epoll and nothing else.
454.Sp 544.Sp
455.Vb 3 545.Vb 3
456\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); 546\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
457\& if (!epoller) 547\& if (!epoller)
458\& fatal ("no epoll found here, maybe it hides under your chair"); 548\& fatal ("no epoll found here, maybe it hides under your chair");
… …
495.IP "ev_loop_fork (loop)" 4 585.IP "ev_loop_fork (loop)" 4
496.IX Item "ev_loop_fork (loop)" 586.IX Item "ev_loop_fork (loop)"
497Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by 587Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by
498\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop 588\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop
499after fork, and how you do this is entirely your own problem. 589after fork, and how you do this is entirely your own problem.
590.IP "unsigned int ev_loop_count (loop)" 4
591.IX Item "unsigned int ev_loop_count (loop)"
592Returns the count of loop iterations for the loop, which is identical to
593the number of times libev did poll for new events. It starts at \f(CW0\fR and
594happily wraps around with enough iterations.
595.Sp
596This value can sometimes be useful as a generation counter of sorts (it
597\&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with
598\&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls.
500.IP "unsigned int ev_backend (loop)" 4 599.IP "unsigned int ev_backend (loop)" 4
501.IX Item "unsigned int ev_backend (loop)" 600.IX Item "unsigned int ev_backend (loop)"
502Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in 601Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
503use. 602use.
504.IP "ev_tstamp ev_now (loop)" 4 603.IP "ev_tstamp ev_now (loop)" 4
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556\& be handled here by queueing them when their watcher gets executed. 655\& be handled here by queueing them when their watcher gets executed.
557\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK 656\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
558\& were used, return, otherwise continue with step *. 657\& were used, return, otherwise continue with step *.
559.Ve 658.Ve
560.Sp 659.Sp
561Example: queue some jobs and then loop until no events are outsanding 660Example: Queue some jobs and then loop until no events are outsanding
562anymore. 661anymore.
563.Sp 662.Sp
564.Vb 4 663.Vb 4
565\& ... queue jobs here, make sure they register event watchers as long 664\& ... queue jobs here, make sure they register event watchers as long
566\& ... as they still have work to do (even an idle watcher will do..) 665\& ... as they still have work to do (even an idle watcher will do..)
… …
588visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if 687visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if
589no event watchers registered by it are active. It is also an excellent 688no event watchers registered by it are active. It is also an excellent
590way to do this for generic recurring timers or from within third-party 689way to do this for generic recurring timers or from within third-party
591libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR. 690libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.
592.Sp 691.Sp
593Example: create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR 692Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR
594running when nothing else is active. 693running when nothing else is active.
595.Sp 694.Sp
596.Vb 4 695.Vb 4
597\& struct dv_signal exitsig; 696\& struct ev_signal exitsig;
598\& ev_signal_init (&exitsig, sig_cb, SIGINT); 697\& ev_signal_init (&exitsig, sig_cb, SIGINT);
599\& ev_signal_start (myloop, &exitsig); 698\& ev_signal_start (loop, &exitsig);
600\& evf_unref (myloop); 699\& evf_unref (loop);
601.Ve 700.Ve
602.Sp 701.Sp
603Example: for some weird reason, unregister the above signal handler again. 702Example: For some weird reason, unregister the above signal handler again.
604.Sp 703.Sp
605.Vb 2 704.Vb 2
606\& ev_ref (myloop); 705\& ev_ref (loop);
607\& ev_signal_stop (myloop, &exitsig); 706\& ev_signal_stop (loop, &exitsig);
608.Ve 707.Ve
609.SH "ANATOMY OF A WATCHER" 708.SH "ANATOMY OF A WATCHER"
610.IX Header "ANATOMY OF A WATCHER" 709.IX Header "ANATOMY OF A WATCHER"
611A watcher is a structure that you create and register to record your 710A watcher is a structure that you create and register to record your
612interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to 711interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to
… …
684The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread. 783The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread.
685.ie n .IP """EV_CHILD""" 4 784.ie n .IP """EV_CHILD""" 4
686.el .IP "\f(CWEV_CHILD\fR" 4 785.el .IP "\f(CWEV_CHILD\fR" 4
687.IX Item "EV_CHILD" 786.IX Item "EV_CHILD"
688The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change. 787The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change.
788.ie n .IP """EV_STAT""" 4
789.el .IP "\f(CWEV_STAT\fR" 4
790.IX Item "EV_STAT"
791The path specified in the \f(CW\*(C`ev_stat\*(C'\fR watcher changed its attributes somehow.
689.ie n .IP """EV_IDLE""" 4 792.ie n .IP """EV_IDLE""" 4
690.el .IP "\f(CWEV_IDLE\fR" 4 793.el .IP "\f(CWEV_IDLE\fR" 4
691.IX Item "EV_IDLE" 794.IX Item "EV_IDLE"
692The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do. 795The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do.
693.ie n .IP """EV_PREPARE""" 4 796.ie n .IP """EV_PREPARE""" 4
… …
703\&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any 806\&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any
704received events. Callbacks of both watcher types can start and stop as 807received events. Callbacks of both watcher types can start and stop as
705many watchers as they want, and all of them will be taken into account 808many watchers as they want, and all of them will be taken into account
706(for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep 809(for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep
707\&\f(CW\*(C`ev_loop\*(C'\fR from blocking). 810\&\f(CW\*(C`ev_loop\*(C'\fR from blocking).
811.ie n .IP """EV_EMBED""" 4
812.el .IP "\f(CWEV_EMBED\fR" 4
813.IX Item "EV_EMBED"
814The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention.
815.ie n .IP """EV_FORK""" 4
816.el .IP "\f(CWEV_FORK\fR" 4
817.IX Item "EV_FORK"
818The event loop has been resumed in the child process after fork (see
819\&\f(CW\*(C`ev_fork\*(C'\fR).
708.ie n .IP """EV_ERROR""" 4 820.ie n .IP """EV_ERROR""" 4
709.el .IP "\f(CWEV_ERROR\fR" 4 821.el .IP "\f(CWEV_ERROR\fR" 4
710.IX Item "EV_ERROR" 822.IX Item "EV_ERROR"
711An unspecified error has occured, the watcher has been stopped. This might 823An unspecified error has occured, the watcher has been stopped. This might
712happen because the watcher could not be properly started because libev 824happen because the watcher could not be properly started because libev
… …
717Libev will usually signal a few \*(L"dummy\*(R" events together with an error, 829Libev will usually signal a few \*(L"dummy\*(R" events together with an error,
718for example it might indicate that a fd is readable or writable, and if 830for example it might indicate that a fd is readable or writable, and if
719your callbacks is well-written it can just attempt the operation and cope 831your callbacks is well-written it can just attempt the operation and cope
720with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded 832with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded
721programs, though, so beware. 833programs, though, so beware.
722.Sh "\s-1SUMMARY\s0 \s-1OF\s0 \s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" 834.Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0"
723.IX Subsection "SUMMARY OF GENERIC WATCHER FUNCTIONS" 835.IX Subsection "GENERIC WATCHER FUNCTIONS"
724In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type, 836In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type,
725e.g. \f(CW\*(C`timer\*(C'\fR for \f(CW\*(C`ev_timer\*(C'\fR watchers and \f(CW\*(C`io\*(C'\fR for \f(CW\*(C`ev_io\*(C'\fR watchers. 837e.g. \f(CW\*(C`timer\*(C'\fR for \f(CW\*(C`ev_timer\*(C'\fR watchers and \f(CW\*(C`io\*(C'\fR for \f(CW\*(C`ev_io\*(C'\fR watchers.
726.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 838.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4
727.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 839.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4
728.IX Item "ev_init (ev_TYPE *watcher, callback)" 840.IX Item "ev_init (ev_TYPE *watcher, callback)"
… …
734which rolls both calls into one. 846which rolls both calls into one.
735.Sp 847.Sp
736You can reinitialise a watcher at any time as long as it has been stopped 848You can reinitialise a watcher at any time as long as it has been stopped
737(or never started) and there are no pending events outstanding. 849(or never started) and there are no pending events outstanding.
738.Sp 850.Sp
739The callbakc is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher, 851The callback is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher,
740int revents)\*(C'\fR. 852int revents)\*(C'\fR.
741.ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4 853.ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4
742.el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4 854.el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4
743.IX Item "ev_TYPE_set (ev_TYPE *, [args])" 855.IX Item "ev_TYPE_set (ev_TYPE *, [args])"
744This macro initialises the type-specific parts of a watcher. You need to 856This macro initialises the type-specific parts of a watcher. You need to
… …
779Returns a true value iff the watcher is pending, (i.e. it has outstanding 891Returns a true value iff the watcher is pending, (i.e. it has outstanding
780events but its callback has not yet been invoked). As long as a watcher 892events but its callback has not yet been invoked). As long as a watcher
781is pending (but not active) you must not call an init function on it (but 893is pending (but not active) you must not call an init function on it (but
782\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to 894\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to
783libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). 895libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it).
784.IP "callback = ev_cb (ev_TYPE *watcher)" 4 896.IP "callback ev_cb (ev_TYPE *watcher)" 4
785.IX Item "callback = ev_cb (ev_TYPE *watcher)" 897.IX Item "callback ev_cb (ev_TYPE *watcher)"
786Returns the callback currently set on the watcher. 898Returns the callback currently set on the watcher.
787.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 899.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
788.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 900.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
789Change the callback. You can change the callback at virtually any time 901Change the callback. You can change the callback at virtually any time
790(modulo threads). 902(modulo threads).
903.IP "ev_set_priority (ev_TYPE *watcher, priority)" 4
904.IX Item "ev_set_priority (ev_TYPE *watcher, priority)"
905.PD 0
906.IP "int ev_priority (ev_TYPE *watcher)" 4
907.IX Item "int ev_priority (ev_TYPE *watcher)"
908.PD
909Set and query the priority of the watcher. The priority is a small
910integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR
911(default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked
912before watchers with lower priority, but priority will not keep watchers
913from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers).
914.Sp
915This means that priorities are \fIonly\fR used for ordering callback
916invocation after new events have been received. This is useful, for
917example, to reduce latency after idling, or more often, to bind two
918watchers on the same event and make sure one is called first.
919.Sp
920If you need to suppress invocation when higher priority events are pending
921you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality.
922.Sp
923The default priority used by watchers when no priority has been set is
924always \f(CW0\fR, which is supposed to not be too high and not be too low :).
925.Sp
926Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is
927fine, as long as you do not mind that the priority value you query might
928or might not have been adjusted to be within valid range.
791.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 929.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
792.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 930.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
793Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change 931Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change
794and read at any time, libev will completely ignore it. This can be used 932and read at any time, libev will completely ignore it. This can be used
795to associate arbitrary data with your watcher. If you need more data and 933to associate arbitrary data with your watcher. If you need more data and
… …
816\& struct my_io *w = (struct my_io *)w_; 954\& struct my_io *w = (struct my_io *)w_;
817\& ... 955\& ...
818\& } 956\& }
819.Ve 957.Ve
820.PP 958.PP
821More interesting and less C\-conformant ways of catsing your callback type 959More interesting and less C\-conformant ways of casting your callback type
822have been omitted.... 960instead have been omitted.
961.PP
962Another common scenario is having some data structure with multiple
963watchers:
964.PP
965.Vb 6
966\& struct my_biggy
967\& {
968\& int some_data;
969\& ev_timer t1;
970\& ev_timer t2;
971\& }
972.Ve
973.PP
974In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated,
975you need to use \f(CW\*(C`offsetof\*(C'\fR:
976.PP
977.Vb 1
978\& #include <stddef.h>
979.Ve
980.PP
981.Vb 6
982\& static void
983\& t1_cb (EV_P_ struct ev_timer *w, int revents)
984\& {
985\& struct my_biggy big = (struct my_biggy *
986\& (((char *)w) - offsetof (struct my_biggy, t1));
987\& }
988.Ve
989.PP
990.Vb 6
991\& static void
992\& t2_cb (EV_P_ struct ev_timer *w, int revents)
993\& {
994\& struct my_biggy big = (struct my_biggy *
995\& (((char *)w) - offsetof (struct my_biggy, t2));
996\& }
997.Ve
823.SH "WATCHER TYPES" 998.SH "WATCHER TYPES"
824.IX Header "WATCHER TYPES" 999.IX Header "WATCHER TYPES"
825This section describes each watcher in detail, but will not repeat 1000This section describes each watcher in detail, but will not repeat
826information given in the last section. 1001information given in the last section. Any initialisation/set macros,
1002functions and members specific to the watcher type are explained.
1003.PP
1004Members are additionally marked with either \fI[read\-only]\fR, meaning that,
1005while the watcher is active, you can look at the member and expect some
1006sensible content, but you must not modify it (you can modify it while the
1007watcher is stopped to your hearts content), or \fI[read\-write]\fR, which
1008means you can expect it to have some sensible content while the watcher
1009is active, but you can also modify it. Modifying it may not do something
1010sensible or take immediate effect (or do anything at all), but libev will
1011not crash or malfunction in any way.
827.ie n .Sh """ev_io"" \- is this file descriptor readable or writable" 1012.ie n .Sh """ev_io"" \- is this file descriptor readable or writable?"
828.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable" 1013.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?"
829.IX Subsection "ev_io - is this file descriptor readable or writable" 1014.IX Subsection "ev_io - is this file descriptor readable or writable?"
830I/O watchers check whether a file descriptor is readable or writable 1015I/O watchers check whether a file descriptor is readable or writable
831in each iteration of the event loop (This behaviour is called 1016in each iteration of the event loop, or, more precisely, when reading
832level-triggering because you keep receiving events as long as the 1017would not block the process and writing would at least be able to write
833condition persists. Remember you can stop the watcher if you don't want to 1018some data. This behaviour is called level-triggering because you keep
834act on the event and neither want to receive future events). 1019receiving events as long as the condition persists. Remember you can stop
1020the watcher if you don't want to act on the event and neither want to
1021receive future events.
835.PP 1022.PP
836In general you can register as many read and/or write event watchers per 1023In general you can register as many read and/or write event watchers per
837fd as you want (as long as you don't confuse yourself). Setting all file 1024fd as you want (as long as you don't confuse yourself). Setting all file
838descriptors to non-blocking mode is also usually a good idea (but not 1025descriptors to non-blocking mode is also usually a good idea (but not
839required if you know what you are doing). 1026required if you know what you are doing).
840.PP 1027.PP
841You have to be careful with dup'ed file descriptors, though. Some backends 1028You have to be careful with dup'ed file descriptors, though. Some backends
842(the linux epoll backend is a notable example) cannot handle dup'ed file 1029(the linux epoll backend is a notable example) cannot handle dup'ed file
843descriptors correctly if you register interest in two or more fds pointing 1030descriptors correctly if you register interest in two or more fds pointing
844to the same underlying file/socket etc. description (that is, they share 1031to the same underlying file/socket/etc. description (that is, they share
845the same underlying \*(L"file open\*(R"). 1032the same underlying \*(L"file open\*(R").
846.PP 1033.PP
847If you must do this, then force the use of a known-to-be-good backend 1034If you must do this, then force the use of a known-to-be-good backend
848(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and 1035(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and
849\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). 1036\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR).
1037.PP
1038Another thing you have to watch out for is that it is quite easy to
1039receive \*(L"spurious\*(R" readyness notifications, that is your callback might
1040be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block
1041because there is no data. Not only are some backends known to create a
1042lot of those (for example solaris ports), it is very easy to get into
1043this situation even with a relatively standard program structure. Thus
1044it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning
1045\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
1046.PP
1047If you cannot run the fd in non-blocking mode (for example you should not
1048play around with an Xlib connection), then you have to seperately re-test
1049whether a file descriptor is really ready with a known-to-be good interface
1050such as poll (fortunately in our Xlib example, Xlib already does this on
1051its own, so its quite safe to use).
850.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 1052.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
851.IX Item "ev_io_init (ev_io *, callback, int fd, int events)" 1053.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
852.PD 0 1054.PD 0
853.IP "ev_io_set (ev_io *, int fd, int events)" 4 1055.IP "ev_io_set (ev_io *, int fd, int events)" 4
854.IX Item "ev_io_set (ev_io *, int fd, int events)" 1056.IX Item "ev_io_set (ev_io *, int fd, int events)"
855.PD 1057.PD
856Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The fd is the file descriptor to rceeive 1058Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to
857events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_READ | 1059rceeive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or
858EV_WRITE\*(C'\fR to receive the given events. 1060\&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events.
859.Sp 1061.IP "int fd [read\-only]" 4
860Please note that most of the more scalable backend mechanisms (for example 1062.IX Item "int fd [read-only]"
861epoll and solaris ports) can result in spurious readyness notifications 1063The file descriptor being watched.
862for file descriptors, so you practically need to use non-blocking I/O (and 1064.IP "int events [read\-only]" 4
863treat callback invocation as hint only), or retest separately with a safe 1065.IX Item "int events [read-only]"
864interface before doing I/O (XLib can do this), or force the use of either 1066The events being watched.
865\&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR, which don't suffer from this
866problem. Also note that it is quite easy to have your callback invoked
867when the readyness condition is no longer valid even when employing
868typical ways of handling events, so its a good idea to use non-blocking
869I/O unconditionally.
870.PP 1067.PP
871Example: call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well 1068Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well
872readable, but only once. Since it is likely line\-buffered, you could 1069readable, but only once. Since it is likely line\-buffered, you could
873attempt to read a whole line in the callback: 1070attempt to read a whole line in the callback.
874.PP 1071.PP
875.Vb 6 1072.Vb 6
876\& static void 1073\& static void
877\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1074\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
878\& { 1075\& {
… …
887\& struct ev_io stdin_readable; 1084\& struct ev_io stdin_readable;
888\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); 1085\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
889\& ev_io_start (loop, &stdin_readable); 1086\& ev_io_start (loop, &stdin_readable);
890\& ev_loop (loop, 0); 1087\& ev_loop (loop, 0);
891.Ve 1088.Ve
892.ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts" 1089.ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts"
893.el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts" 1090.el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts"
894.IX Subsection "ev_timer - relative and optionally recurring timeouts" 1091.IX Subsection "ev_timer - relative and optionally repeating timeouts"
895Timer watchers are simple relative timers that generate an event after a 1092Timer watchers are simple relative timers that generate an event after a
896given time, and optionally repeating in regular intervals after that. 1093given time, and optionally repeating in regular intervals after that.
897.PP 1094.PP
898The timers are based on real time, that is, if you register an event that 1095The timers are based on real time, that is, if you register an event that
899times out after an hour and you reset your system clock to last years 1096times out after an hour and you reset your system clock to last years
… …
933.IP "ev_timer_again (loop)" 4 1130.IP "ev_timer_again (loop)" 4
934.IX Item "ev_timer_again (loop)" 1131.IX Item "ev_timer_again (loop)"
935This will act as if the timer timed out and restart it again if it is 1132This will act as if the timer timed out and restart it again if it is
936repeating. The exact semantics are: 1133repeating. The exact semantics are:
937.Sp 1134.Sp
1135If the timer is pending, its pending status is cleared.
1136.Sp
938If the timer is started but nonrepeating, stop it. 1137If the timer is started but nonrepeating, stop it (as if it timed out).
939.Sp 1138.Sp
940If the timer is repeating, either start it if necessary (with the repeat 1139If the timer is repeating, either start it if necessary (with the
941value), or reset the running timer to the repeat value. 1140\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value.
942.Sp 1141.Sp
943This sounds a bit complicated, but here is a useful and typical 1142This sounds a bit complicated, but here is a useful and typical
944example: Imagine you have a tcp connection and you want a so-called idle 1143example: Imagine you have a tcp connection and you want a so-called idle
945timeout, that is, you want to be called when there have been, say, 60 1144timeout, that is, you want to be called when there have been, say, 60
946seconds of inactivity on the socket. The easiest way to do this is to 1145seconds of inactivity on the socket. The easiest way to do this is to
947configure an \f(CW\*(C`ev_timer\*(C'\fR with after=repeat=60 and calling ev_timer_again each 1146configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value of \f(CW60\fR and then call
948time you successfully read or write some data. If you go into an idle 1147\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If
949state where you do not expect data to travel on the socket, you can stop 1148you go into an idle state where you do not expect data to travel on the
950the timer, and again will automatically restart it if need be. 1149socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will
1150automatically restart it if need be.
1151.Sp
1152That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR
1153altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR:
1154.Sp
1155.Vb 8
1156\& ev_timer_init (timer, callback, 0., 5.);
1157\& ev_timer_again (loop, timer);
1158\& ...
1159\& timer->again = 17.;
1160\& ev_timer_again (loop, timer);
1161\& ...
1162\& timer->again = 10.;
1163\& ev_timer_again (loop, timer);
1164.Ve
1165.Sp
1166This is more slightly efficient then stopping/starting the timer each time
1167you want to modify its timeout value.
1168.IP "ev_tstamp repeat [read\-write]" 4
1169.IX Item "ev_tstamp repeat [read-write]"
1170The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out
1171or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any),
1172which is also when any modifications are taken into account.
951.PP 1173.PP
952Example: create a timer that fires after 60 seconds. 1174Example: Create a timer that fires after 60 seconds.
953.PP 1175.PP
954.Vb 5 1176.Vb 5
955\& static void 1177\& static void
956\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1178\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
957\& { 1179\& {
… …
963\& struct ev_timer mytimer; 1185\& struct ev_timer mytimer;
964\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); 1186\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
965\& ev_timer_start (loop, &mytimer); 1187\& ev_timer_start (loop, &mytimer);
966.Ve 1188.Ve
967.PP 1189.PP
968Example: create a timeout timer that times out after 10 seconds of 1190Example: Create a timeout timer that times out after 10 seconds of
969inactivity. 1191inactivity.
970.PP 1192.PP
971.Vb 5 1193.Vb 5
972\& static void 1194\& static void
973\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1195\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
… …
986.Vb 3 1208.Vb 3
987\& // and in some piece of code that gets executed on any "activity": 1209\& // and in some piece of code that gets executed on any "activity":
988\& // reset the timeout to start ticking again at 10 seconds 1210\& // reset the timeout to start ticking again at 10 seconds
989\& ev_timer_again (&mytimer); 1211\& ev_timer_again (&mytimer);
990.Ve 1212.Ve
991.ie n .Sh """ev_periodic"" \- to cron or not to cron" 1213.ie n .Sh """ev_periodic"" \- to cron or not to cron?"
992.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron" 1214.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?"
993.IX Subsection "ev_periodic - to cron or not to cron" 1215.IX Subsection "ev_periodic - to cron or not to cron?"
994Periodic watchers are also timers of a kind, but they are very versatile 1216Periodic watchers are also timers of a kind, but they are very versatile
995(and unfortunately a bit complex). 1217(and unfortunately a bit complex).
996.PP 1218.PP
997Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) 1219Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time)
998but on wallclock time (absolute time). You can tell a periodic watcher 1220but on wallclock time (absolute time). You can tell a periodic watcher
… …
1087.IX Item "ev_periodic_again (loop, ev_periodic *)" 1309.IX Item "ev_periodic_again (loop, ev_periodic *)"
1088Simply stops and restarts the periodic watcher again. This is only useful 1310Simply stops and restarts the periodic watcher again. This is only useful
1089when you changed some parameters or the reschedule callback would return 1311when you changed some parameters or the reschedule callback would return
1090a different time than the last time it was called (e.g. in a crond like 1312a different time than the last time it was called (e.g. in a crond like
1091program when the crontabs have changed). 1313program when the crontabs have changed).
1314.IP "ev_tstamp interval [read\-write]" 4
1315.IX Item "ev_tstamp interval [read-write]"
1316The current interval value. Can be modified any time, but changes only
1317take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being
1318called.
1319.IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4
1320.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]"
1321The current reschedule callback, or \f(CW0\fR, if this functionality is
1322switched off. Can be changed any time, but changes only take effect when
1323the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1092.PP 1324.PP
1093Example: call a callback every hour, or, more precisely, whenever the 1325Example: Call a callback every hour, or, more precisely, whenever the
1094system clock is divisible by 3600. The callback invocation times have 1326system clock is divisible by 3600. The callback invocation times have
1095potentially a lot of jittering, but good long-term stability. 1327potentially a lot of jittering, but good long-term stability.
1096.PP 1328.PP
1097.Vb 5 1329.Vb 5
1098\& static void 1330\& static void
… …
1106\& struct ev_periodic hourly_tick; 1338\& struct ev_periodic hourly_tick;
1107\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); 1339\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1108\& ev_periodic_start (loop, &hourly_tick); 1340\& ev_periodic_start (loop, &hourly_tick);
1109.Ve 1341.Ve
1110.PP 1342.PP
1111Example: the same as above, but use a reschedule callback to do it: 1343Example: The same as above, but use a reschedule callback to do it:
1112.PP 1344.PP
1113.Vb 1 1345.Vb 1
1114\& #include <math.h> 1346\& #include <math.h>
1115.Ve 1347.Ve
1116.PP 1348.PP
… …
1124.PP 1356.PP
1125.Vb 1 1357.Vb 1
1126\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); 1358\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1127.Ve 1359.Ve
1128.PP 1360.PP
1129Example: call a callback every hour, starting now: 1361Example: Call a callback every hour, starting now:
1130.PP 1362.PP
1131.Vb 4 1363.Vb 4
1132\& struct ev_periodic hourly_tick; 1364\& struct ev_periodic hourly_tick;
1133\& ev_periodic_init (&hourly_tick, clock_cb, 1365\& ev_periodic_init (&hourly_tick, clock_cb,
1134\& fmod (ev_now (loop), 3600.), 3600., 0); 1366\& fmod (ev_now (loop), 3600.), 3600., 0);
1135\& ev_periodic_start (loop, &hourly_tick); 1367\& ev_periodic_start (loop, &hourly_tick);
1136.Ve 1368.Ve
1137.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled" 1369.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!"
1138.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled" 1370.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!"
1139.IX Subsection "ev_signal - signal me when a signal gets signalled" 1371.IX Subsection "ev_signal - signal me when a signal gets signalled!"
1140Signal watchers will trigger an event when the process receives a specific 1372Signal watchers will trigger an event when the process receives a specific
1141signal one or more times. Even though signals are very asynchronous, libev 1373signal one or more times. Even though signals are very asynchronous, libev
1142will try it's best to deliver signals synchronously, i.e. as part of the 1374will try it's best to deliver signals synchronously, i.e. as part of the
1143normal event processing, like any other event. 1375normal event processing, like any other event.
1144.PP 1376.PP
… …
1154.IP "ev_signal_set (ev_signal *, int signum)" 4 1386.IP "ev_signal_set (ev_signal *, int signum)" 4
1155.IX Item "ev_signal_set (ev_signal *, int signum)" 1387.IX Item "ev_signal_set (ev_signal *, int signum)"
1156.PD 1388.PD
1157Configures the watcher to trigger on the given signal number (usually one 1389Configures the watcher to trigger on the given signal number (usually one
1158of the \f(CW\*(C`SIGxxx\*(C'\fR constants). 1390of the \f(CW\*(C`SIGxxx\*(C'\fR constants).
1391.IP "int signum [read\-only]" 4
1392.IX Item "int signum [read-only]"
1393The signal the watcher watches out for.
1159.ie n .Sh """ev_child"" \- wait for pid status changes" 1394.ie n .Sh """ev_child"" \- watch out for process status changes"
1160.el .Sh "\f(CWev_child\fP \- wait for pid status changes" 1395.el .Sh "\f(CWev_child\fP \- watch out for process status changes"
1161.IX Subsection "ev_child - wait for pid status changes" 1396.IX Subsection "ev_child - watch out for process status changes"
1162Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to 1397Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to
1163some child status changes (most typically when a child of yours dies). 1398some child status changes (most typically when a child of yours dies).
1164.IP "ev_child_init (ev_child *, callback, int pid)" 4 1399.IP "ev_child_init (ev_child *, callback, int pid)" 4
1165.IX Item "ev_child_init (ev_child *, callback, int pid)" 1400.IX Item "ev_child_init (ev_child *, callback, int pid)"
1166.PD 0 1401.PD 0
… …
1171\&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look 1406\&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look
1172at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see 1407at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see
1173the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems 1408the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems
1174\&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the 1409\&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the
1175process causing the status change. 1410process causing the status change.
1411.IP "int pid [read\-only]" 4
1412.IX Item "int pid [read-only]"
1413The process id this watcher watches out for, or \f(CW0\fR, meaning any process id.
1414.IP "int rpid [read\-write]" 4
1415.IX Item "int rpid [read-write]"
1416The process id that detected a status change.
1417.IP "int rstatus [read\-write]" 4
1418.IX Item "int rstatus [read-write]"
1419The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems
1420\&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details).
1176.PP 1421.PP
1177Example: try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. 1422Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.
1178.PP 1423.PP
1179.Vb 5 1424.Vb 5
1180\& static void 1425\& static void
1181\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) 1426\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1182\& { 1427\& {
… …
1187.Vb 3 1432.Vb 3
1188\& struct ev_signal signal_watcher; 1433\& struct ev_signal signal_watcher;
1189\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); 1434\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1190\& ev_signal_start (loop, &sigint_cb); 1435\& ev_signal_start (loop, &sigint_cb);
1191.Ve 1436.Ve
1437.ie n .Sh """ev_stat"" \- did the file attributes just change?"
1438.el .Sh "\f(CWev_stat\fP \- did the file attributes just change?"
1439.IX Subsection "ev_stat - did the file attributes just change?"
1440This watches a filesystem path for attribute changes. That is, it calls
1441\&\f(CW\*(C`stat\*(C'\fR regularly (or when the \s-1OS\s0 says it changed) and sees if it changed
1442compared to the last time, invoking the callback if it did.
1443.PP
1444The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does
1445not exist\*(R" is a status change like any other. The condition \*(L"path does
1446not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is
1447otherwise always forced to be at least one) and all the other fields of
1448the stat buffer having unspecified contents.
1449.PP
1450The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is
1451relative and your working directory changes, the behaviour is undefined.
1452.PP
1453Since there is no standard to do this, the portable implementation simply
1454calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You
1455can specify a recommended polling interval for this case. If you specify
1456a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable,
1457unspecified default\fR value will be used (which you can expect to be around
1458five seconds, although this might change dynamically). Libev will also
1459impose a minimum interval which is currently around \f(CW0.1\fR, but thats
1460usually overkill.
1461.PP
1462This watcher type is not meant for massive numbers of stat watchers,
1463as even with OS-supported change notifications, this can be
1464resource\-intensive.
1465.PP
1466At the time of this writing, only the Linux inotify interface is
1467implemented (implementing kqueue support is left as an exercise for the
1468reader). Inotify will be used to give hints only and should not change the
1469semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs
1470to fall back to regular polling again even with inotify, but changes are
1471usually detected immediately, and if the file exists there will be no
1472polling.
1473.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
1474.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
1475.PD 0
1476.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4
1477.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
1478.PD
1479Configures the watcher to wait for status changes of the given
1480\&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to
1481be detected and should normally be specified as \f(CW0\fR to let libev choose
1482a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same
1483path for as long as the watcher is active.
1484.Sp
1485The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected,
1486relative to the attributes at the time the watcher was started (or the
1487last change was detected).
1488.IP "ev_stat_stat (ev_stat *)" 4
1489.IX Item "ev_stat_stat (ev_stat *)"
1490Updates the stat buffer immediately with new values. If you change the
1491watched path in your callback, you could call this fucntion to avoid
1492detecting this change (while introducing a race condition). Can also be
1493useful simply to find out the new values.
1494.IP "ev_statdata attr [read\-only]" 4
1495.IX Item "ev_statdata attr [read-only]"
1496The most-recently detected attributes of the file. Although the type is of
1497\&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types
1498suitable for your system. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there
1499was some error while \f(CW\*(C`stat\*(C'\fRing the file.
1500.IP "ev_statdata prev [read\-only]" 4
1501.IX Item "ev_statdata prev [read-only]"
1502The previous attributes of the file. The callback gets invoked whenever
1503\&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR.
1504.IP "ev_tstamp interval [read\-only]" 4
1505.IX Item "ev_tstamp interval [read-only]"
1506The specified interval.
1507.IP "const char *path [read\-only]" 4
1508.IX Item "const char *path [read-only]"
1509The filesystem path that is being watched.
1510.PP
1511Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes.
1512.PP
1513.Vb 15
1514\& static void
1515\& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1516\& {
1517\& /* /etc/passwd changed in some way */
1518\& if (w->attr.st_nlink)
1519\& {
1520\& printf ("passwd current size %ld\en", (long)w->attr.st_size);
1521\& printf ("passwd current atime %ld\en", (long)w->attr.st_mtime);
1522\& printf ("passwd current mtime %ld\en", (long)w->attr.st_mtime);
1523\& }
1524\& else
1525\& /* you shalt not abuse printf for puts */
1526\& puts ("wow, /etc/passwd is not there, expect problems. "
1527\& "if this is windows, they already arrived\en");
1528\& }
1529.Ve
1530.PP
1531.Vb 2
1532\& ...
1533\& ev_stat passwd;
1534.Ve
1535.PP
1536.Vb 2
1537\& ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
1538\& ev_stat_start (loop, &passwd);
1539.Ve
1192.ie n .Sh """ev_idle"" \- when you've got nothing better to do" 1540.ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
1193.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do" 1541.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
1194.IX Subsection "ev_idle - when you've got nothing better to do" 1542.IX Subsection "ev_idle - when you've got nothing better to do..."
1195Idle watchers trigger events when there are no other events are pending 1543Idle watchers trigger events when no other events of the same or higher
1196(prepare, check and other idle watchers do not count). That is, as long 1544priority are pending (prepare, check and other idle watchers do not
1197as your process is busy handling sockets or timeouts (or even signals, 1545count).
1198imagine) it will not be triggered. But when your process is idle all idle 1546.PP
1199watchers are being called again and again, once per event loop iteration \- 1547That is, as long as your process is busy handling sockets or timeouts
1548(or even signals, imagine) of the same or higher priority it will not be
1549triggered. But when your process is idle (or only lower-priority watchers
1550are pending), the idle watchers are being called once per event loop
1200until stopped, that is, or your process receives more events and becomes 1551iteration \- until stopped, that is, or your process receives more events
1201busy. 1552and becomes busy again with higher priority stuff.
1202.PP 1553.PP
1203The most noteworthy effect is that as long as any idle watchers are 1554The most noteworthy effect is that as long as any idle watchers are
1204active, the process will not block when waiting for new events. 1555active, the process will not block when waiting for new events.
1205.PP 1556.PP
1206Apart from keeping your process non-blocking (which is a useful 1557Apart from keeping your process non-blocking (which is a useful
… …
1211.IX Item "ev_idle_init (ev_signal *, callback)" 1562.IX Item "ev_idle_init (ev_signal *, callback)"
1212Initialises and configures the idle watcher \- it has no parameters of any 1563Initialises and configures the idle watcher \- it has no parameters of any
1213kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, 1564kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,
1214believe me. 1565believe me.
1215.PP 1566.PP
1216Example: dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR, start it, and in the 1567Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the
1217callback, free it. Alos, use no error checking, as usual. 1568callback, free it. Also, use no error checking, as usual.
1218.PP 1569.PP
1219.Vb 7 1570.Vb 7
1220\& static void 1571\& static void
1221\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) 1572\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1222\& { 1573\& {
… …
1229.Vb 3 1580.Vb 3
1230\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); 1581\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1231\& ev_idle_init (idle_watcher, idle_cb); 1582\& ev_idle_init (idle_watcher, idle_cb);
1232\& ev_idle_start (loop, idle_cb); 1583\& ev_idle_start (loop, idle_cb);
1233.Ve 1584.Ve
1234.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop" 1585.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!"
1235.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop" 1586.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!"
1236.IX Subsection "ev_prepare and ev_check - customise your event loop" 1587.IX Subsection "ev_prepare and ev_check - customise your event loop!"
1237Prepare and check watchers are usually (but not always) used in tandem: 1588Prepare and check watchers are usually (but not always) used in tandem:
1238prepare watchers get invoked before the process blocks and check watchers 1589prepare watchers get invoked before the process blocks and check watchers
1239afterwards. 1590afterwards.
1240.PP 1591.PP
1592You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter
1593the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR
1594watchers. Other loops than the current one are fine, however. The
1595rationale behind this is that you do not need to check for recursion in
1596those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking,
1597\&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be
1598called in pairs bracketing the blocking call.
1599.PP
1241Their main purpose is to integrate other event mechanisms into libev and 1600Their main purpose is to integrate other event mechanisms into libev and
1242their use is somewhat advanced. This could be used, for example, to track 1601their use is somewhat advanced. This could be used, for example, to track
1243variable changes, implement your own watchers, integrate net-snmp or a 1602variable changes, implement your own watchers, integrate net-snmp or a
1244coroutine library and lots more. 1603coroutine library and lots more. They are also occasionally useful if
1604you cache some data and want to flush it before blocking (for example,
1605in X programs you might want to do an \f(CW\*(C`XFlush ()\*(C'\fR in an \f(CW\*(C`ev_prepare\*(C'\fR
1606watcher).
1245.PP 1607.PP
1246This is done by examining in each prepare call which file descriptors need 1608This is done by examining in each prepare call which file descriptors need
1247to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for 1609to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for
1248them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries 1610them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries
1249provide just this functionality). Then, in the check watcher you check for 1611provide just this functionality). Then, in the check watcher you check for
… …
1268.PD 1630.PD
1269Initialises and configures the prepare or check watcher \- they have no 1631Initialises and configures the prepare or check watcher \- they have no
1270parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR 1632parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR
1271macros, but using them is utterly, utterly and completely pointless. 1633macros, but using them is utterly, utterly and completely pointless.
1272.PP 1634.PP
1273Example: *TODO*. 1635Example: To include a library such as adns, you would add \s-1IO\s0 watchers
1636and a timeout watcher in a prepare handler, as required by libadns, and
1637in a check watcher, destroy them and call into libadns. What follows is
1638pseudo-code only of course:
1639.PP
1640.Vb 2
1641\& static ev_io iow [nfd];
1642\& static ev_timer tw;
1643.Ve
1644.PP
1645.Vb 9
1646\& static void
1647\& io_cb (ev_loop *loop, ev_io *w, int revents)
1648\& {
1649\& // set the relevant poll flags
1650\& // could also call adns_processreadable etc. here
1651\& struct pollfd *fd = (struct pollfd *)w->data;
1652\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1653\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1654\& }
1655.Ve
1656.PP
1657.Vb 8
1658\& // create io watchers for each fd and a timer before blocking
1659\& static void
1660\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1661\& {
1662\& int timeout = 3600000;
1663\& struct pollfd fds [nfd];
1664\& // actual code will need to loop here and realloc etc.
1665\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1666.Ve
1667.PP
1668.Vb 3
1669\& /* the callback is illegal, but won't be called as we stop during check */
1670\& ev_timer_init (&tw, 0, timeout * 1e-3);
1671\& ev_timer_start (loop, &tw);
1672.Ve
1673.PP
1674.Vb 6
1675\& // create on ev_io per pollfd
1676\& for (int i = 0; i < nfd; ++i)
1677\& {
1678\& ev_io_init (iow + i, io_cb, fds [i].fd,
1679\& ((fds [i].events & POLLIN ? EV_READ : 0)
1680\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1681.Ve
1682.PP
1683.Vb 5
1684\& fds [i].revents = 0;
1685\& iow [i].data = fds + i;
1686\& ev_io_start (loop, iow + i);
1687\& }
1688\& }
1689.Ve
1690.PP
1691.Vb 5
1692\& // stop all watchers after blocking
1693\& static void
1694\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1695\& {
1696\& ev_timer_stop (loop, &tw);
1697.Ve
1698.PP
1699.Vb 2
1700\& for (int i = 0; i < nfd; ++i)
1701\& ev_io_stop (loop, iow + i);
1702.Ve
1703.PP
1704.Vb 2
1705\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1706\& }
1707.Ve
1274.ie n .Sh """ev_embed"" \- when one backend isn't enough" 1708.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1275.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough" 1709.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
1276.IX Subsection "ev_embed - when one backend isn't enough" 1710.IX Subsection "ev_embed - when one backend isn't enough..."
1277This is a rather advanced watcher type that lets you embed one event loop 1711This is a rather advanced watcher type that lets you embed one event loop
1278into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded 1712into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded
1279loop, other types of watchers might be handled in a delayed or incorrect 1713loop, other types of watchers might be handled in a delayed or incorrect
1280fashion and must not be used). 1714fashion and must not be used).
1281.PP 1715.PP
… …
1361.IP "ev_embed_sweep (loop, ev_embed *)" 4 1795.IP "ev_embed_sweep (loop, ev_embed *)" 4
1362.IX Item "ev_embed_sweep (loop, ev_embed *)" 1796.IX Item "ev_embed_sweep (loop, ev_embed *)"
1363Make a single, non-blocking sweep over the embedded loop. This works 1797Make a single, non-blocking sweep over the embedded loop. This works
1364similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most 1798similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most
1365apropriate way for embedded loops. 1799apropriate way for embedded loops.
1800.IP "struct ev_loop *loop [read\-only]" 4
1801.IX Item "struct ev_loop *loop [read-only]"
1802The embedded event loop.
1803.ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork"
1804.el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork"
1805.IX Subsection "ev_fork - the audacity to resume the event loop after a fork"
1806Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because
1807whoever is a good citizen cared to tell libev about it by calling
1808\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the
1809event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called,
1810and only in the child after the fork. If whoever good citizen calling
1811\&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork
1812handlers will be invoked, too, of course.
1813.IP "ev_fork_init (ev_signal *, callback)" 4
1814.IX Item "ev_fork_init (ev_signal *, callback)"
1815Initialises and configures the fork watcher \- it has no parameters of any
1816kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless,
1817believe me.
1366.SH "OTHER FUNCTIONS" 1818.SH "OTHER FUNCTIONS"
1367.IX Header "OTHER FUNCTIONS" 1819.IX Header "OTHER FUNCTIONS"
1368There are some other functions of possible interest. Described. Here. Now. 1820There are some other functions of possible interest. Described. Here. Now.
1369.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 1821.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4
1370.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 1822.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)"
… …
1442.PP 1894.PP
1443.Vb 1 1895.Vb 1
1444\& #include <ev++.h> 1896\& #include <ev++.h>
1445.Ve 1897.Ve
1446.PP 1898.PP
1447(it is not installed by default). This automatically includes \fIev.h\fR 1899This automatically includes \fIev.h\fR and puts all of its definitions (many
1448and puts all of its definitions (many of them macros) into the global 1900of them macros) into the global namespace. All \*(C+ specific things are
1449namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace. 1901put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding
1902options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
1450.PP 1903.PP
1451It should support all the same embedding options as \fIev.h\fR, most notably 1904Care has been taken to keep the overhead low. The only data member added
1452\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. 1905to the C\-style watchers is the event loop the watcher is associated with
1906(or no additional members at all if you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when
1907embedding libev).
1908.PP
1909Currently, functions and static and non-static member functions can be
1910used as callbacks. Other types should be easy to add as long as they only
1911need one additional pointer for context. If you need support for other
1912types of functors please contact the author (preferably after implementing
1913it).
1453.PP 1914.PP
1454Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: 1915Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
1455.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 1916.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
1456.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 1917.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
1457.IX Item "ev::READ, ev::WRITE etc." 1918.IX Item "ev::READ, ev::WRITE etc."
… …
1469which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro 1930which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
1470defines by many implementations. 1931defines by many implementations.
1471.Sp 1932.Sp
1472All of those classes have these methods: 1933All of those classes have these methods:
1473.RS 4 1934.RS 4
1474.IP "ev::TYPE::TYPE (object *, object::method *)" 4 1935.IP "ev::TYPE::TYPE ()" 4
1475.IX Item "ev::TYPE::TYPE (object *, object::method *)" 1936.IX Item "ev::TYPE::TYPE ()"
1476.PD 0 1937.PD 0
1477.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 1938.IP "ev::TYPE::TYPE (struct ev_loop *)" 4
1478.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 1939.IX Item "ev::TYPE::TYPE (struct ev_loop *)"
1479.IP "ev::TYPE::~TYPE" 4 1940.IP "ev::TYPE::~TYPE" 4
1480.IX Item "ev::TYPE::~TYPE" 1941.IX Item "ev::TYPE::~TYPE"
1481.PD 1942.PD
1482The constructor takes a pointer to an object and a method pointer to 1943The constructor (optionally) takes an event loop to associate the watcher
1483the event handler callback to call in this class. The constructor calls 1944with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR.
1484\&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method 1945.Sp
1485before starting it. If you do not specify a loop then the constructor 1946The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the
1486automatically associates the default loop with this watcher. 1947\&\f(CW\*(C`set\*(C'\fR method before starting it.
1948.Sp
1949It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR
1950method to set a callback before you can start the watcher.
1951.Sp
1952(The reason why you have to use a method is a limitation in \*(C+ which does
1953not allow explicit template arguments for constructors).
1487.Sp 1954.Sp
1488The destructor automatically stops the watcher if it is active. 1955The destructor automatically stops the watcher if it is active.
1956.IP "w\->set<class, &class::method> (object *)" 4
1957.IX Item "w->set<class, &class::method> (object *)"
1958This method sets the callback method to call. The method has to have a
1959signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as
1960first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as
1961parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher.
1962.Sp
1963This method synthesizes efficient thunking code to call your method from
1964the C callback that libev requires. If your compiler can inline your
1965callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and
1966your compiler is good :), then the method will be fully inlined into the
1967thunking function, making it as fast as a direct C callback.
1968.Sp
1969Example: simple class declaration and watcher initialisation
1970.Sp
1971.Vb 4
1972\& struct myclass
1973\& {
1974\& void io_cb (ev::io &w, int revents) { }
1975\& }
1976.Ve
1977.Sp
1978.Vb 3
1979\& myclass obj;
1980\& ev::io iow;
1981\& iow.set <myclass, &myclass::io_cb> (&obj);
1982.Ve
1983.IP "w\->set (void (*function)(watcher &w, int), void *data = 0)" 4
1984.IX Item "w->set (void (*function)(watcher &w, int), void *data = 0)"
1985Also sets a callback, but uses a static method or plain function as
1986callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's
1987\&\f(CW\*(C`data\*(C'\fR member and is free for you to use.
1988.Sp
1989See the method\-\f(CW\*(C`set\*(C'\fR above for more details.
1489.IP "w\->set (struct ev_loop *)" 4 1990.IP "w\->set (struct ev_loop *)" 4
1490.IX Item "w->set (struct ev_loop *)" 1991.IX Item "w->set (struct ev_loop *)"
1491Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only 1992Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
1492do this when the watcher is inactive (and not pending either). 1993do this when the watcher is inactive (and not pending either).
1493.IP "w\->set ([args])" 4 1994.IP "w\->set ([args])" 4
1494.IX Item "w->set ([args])" 1995.IX Item "w->set ([args])"
1495Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be 1996Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be
1496called at least once. Unlike the C counterpart, an active watcher gets 1997called at least once. Unlike the C counterpart, an active watcher gets
1497automatically stopped and restarted. 1998automatically stopped and restarted when reconfiguring it with this
1999method.
1498.IP "w\->start ()" 4 2000.IP "w\->start ()" 4
1499.IX Item "w->start ()" 2001.IX Item "w->start ()"
1500Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the 2002Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
1501constructor already takes the loop. 2003constructor already stores the event loop.
1502.IP "w\->stop ()" 4 2004.IP "w\->stop ()" 4
1503.IX Item "w->stop ()" 2005.IX Item "w->stop ()"
1504Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. 2006Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
1505.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4 2007.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4
1506.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4 2008.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4
… …
1509\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. 2011\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function.
1510.ie n .IP "w\->sweep () ""ev::embed"" only" 4 2012.ie n .IP "w\->sweep () ""ev::embed"" only" 4
1511.el .IP "w\->sweep () \f(CWev::embed\fR only" 4 2013.el .IP "w\->sweep () \f(CWev::embed\fR only" 4
1512.IX Item "w->sweep () ev::embed only" 2014.IX Item "w->sweep () ev::embed only"
1513Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. 2015Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR.
2016.ie n .IP "w\->update () ""ev::stat"" only" 4
2017.el .IP "w\->update () \f(CWev::stat\fR only" 4
2018.IX Item "w->update () ev::stat only"
2019Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR.
1514.RE 2020.RE
1515.RS 4 2021.RS 4
1516.RE 2022.RE
1517.PP 2023.PP
1518Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in 2024Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in
… …
1528.Vb 2 2034.Vb 2
1529\& myclass (); 2035\& myclass ();
1530\& } 2036\& }
1531.Ve 2037.Ve
1532.PP 2038.PP
1533.Vb 6 2039.Vb 4
1534\& myclass::myclass (int fd) 2040\& myclass::myclass (int fd)
1535\& : io (this, &myclass::io_cb),
1536\& idle (this, &myclass::idle_cb)
1537\& { 2041\& {
2042\& io .set <myclass, &myclass::io_cb > (this);
2043\& idle.set <myclass, &myclass::idle_cb> (this);
2044.Ve
2045.PP
2046.Vb 2
1538\& io.start (fd, ev::READ); 2047\& io.start (fd, ev::READ);
1539\& } 2048\& }
2049.Ve
2050.SH "MACRO MAGIC"
2051.IX Header "MACRO MAGIC"
2052Libev can be compiled with a variety of options, the most fundemantal is
2053\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) functions and
2054callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
2055.PP
2056To make it easier to write programs that cope with either variant, the
2057following macros are defined:
2058.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
2059.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4
2060.IX Item "EV_A, EV_A_"
2061This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev
2062loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument,
2063\&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example:
2064.Sp
2065.Vb 3
2066\& ev_unref (EV_A);
2067\& ev_timer_add (EV_A_ watcher);
2068\& ev_loop (EV_A_ 0);
2069.Ve
2070.Sp
2071It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope,
2072which is often provided by the following macro.
2073.ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4
2074.el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4
2075.IX Item "EV_P, EV_P_"
2076This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev
2077loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter,
2078\&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example:
2079.Sp
2080.Vb 2
2081\& // this is how ev_unref is being declared
2082\& static void ev_unref (EV_P);
2083.Ve
2084.Sp
2085.Vb 2
2086\& // this is how you can declare your typical callback
2087\& static void cb (EV_P_ ev_timer *w, int revents)
2088.Ve
2089.Sp
2090It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite
2091suitable for use with \f(CW\*(C`EV_A\*(C'\fR.
2092.ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4
2093.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
2094.IX Item "EV_DEFAULT, EV_DEFAULT_"
2095Similar to the other two macros, this gives you the value of the default
2096loop, if multiple loops are supported (\*(L"ev loop default\*(R").
2097.PP
2098Example: Declare and initialise a check watcher, utilising the above
2099macros so it will work regardless of whether multiple loops are supported
2100or not.
2101.PP
2102.Vb 5
2103\& static void
2104\& check_cb (EV_P_ ev_timer *w, int revents)
2105\& {
2106\& ev_check_stop (EV_A_ w);
2107\& }
2108.Ve
2109.PP
2110.Vb 4
2111\& ev_check check;
2112\& ev_check_init (&check, check_cb);
2113\& ev_check_start (EV_DEFAULT_ &check);
2114\& ev_loop (EV_DEFAULT_ 0);
1540.Ve 2115.Ve
1541.SH "EMBEDDING" 2116.SH "EMBEDDING"
1542.IX Header "EMBEDDING" 2117.IX Header "EMBEDDING"
1543Libev can (and often is) directly embedded into host 2118Libev can (and often is) directly embedded into host
1544applications. Examples of applications that embed it include the Deliantra 2119applications. Examples of applications that embed it include the Deliantra
… …
1593.Vb 1 2168.Vb 1
1594\& ev_win32.c required on win32 platforms only 2169\& ev_win32.c required on win32 platforms only
1595.Ve 2170.Ve
1596.PP 2171.PP
1597.Vb 5 2172.Vb 5
1598\& ev_select.c only when select backend is enabled (which is is by default) 2173\& ev_select.c only when select backend is enabled (which is enabled by default)
1599\& ev_poll.c only when poll backend is enabled (disabled by default) 2174\& ev_poll.c only when poll backend is enabled (disabled by default)
1600\& ev_epoll.c only when the epoll backend is enabled (disabled by default) 2175\& ev_epoll.c only when the epoll backend is enabled (disabled by default)
1601\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) 2176\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1602\& ev_port.c only when the solaris port backend is enabled (disabled by default) 2177\& ev_port.c only when the solaris port backend is enabled (disabled by default)
1603.Ve 2178.Ve
1604.PP 2179.PP
1605\&\fIev.c\fR includes the backend files directly when enabled, so you only need 2180\&\fIev.c\fR includes the backend files directly when enabled, so you only need
1606to compile a single file. 2181to compile this single file.
1607.PP 2182.PP
1608\fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR 2183\fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR
1609.IX Subsection "LIBEVENT COMPATIBILITY API" 2184.IX Subsection "LIBEVENT COMPATIBILITY API"
1610.PP 2185.PP
1611To include the libevent compatibility \s-1API\s0, also include: 2186To include the libevent compatibility \s-1API\s0, also include:
… …
1632\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR 2207\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR
1633.IX Subsection "AUTOCONF SUPPORT" 2208.IX Subsection "AUTOCONF SUPPORT"
1634.PP 2209.PP
1635Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in 2210Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in
1636whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your 2211whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your
1637\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR off. \fIev.c\fR will then include 2212\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then
1638\&\fIconfig.h\fR and configure itself accordingly. 2213include \fIconfig.h\fR and configure itself accordingly.
1639.PP 2214.PP
1640For this of course you need the m4 file: 2215For this of course you need the m4 file:
1641.PP 2216.PP
1642.Vb 1 2217.Vb 1
1643\& libev.m4 2218\& libev.m4
… …
1724otherwise another method will be used as fallback. This is the preferred 2299otherwise another method will be used as fallback. This is the preferred
1725backend for Solaris 10 systems. 2300backend for Solaris 10 systems.
1726.IP "\s-1EV_USE_DEVPOLL\s0" 4 2301.IP "\s-1EV_USE_DEVPOLL\s0" 4
1727.IX Item "EV_USE_DEVPOLL" 2302.IX Item "EV_USE_DEVPOLL"
1728reserved for future expansion, works like the \s-1USE\s0 symbols above. 2303reserved for future expansion, works like the \s-1USE\s0 symbols above.
2304.IP "\s-1EV_USE_INOTIFY\s0" 4
2305.IX Item "EV_USE_INOTIFY"
2306If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify
2307interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will
2308be detected at runtime.
1729.IP "\s-1EV_H\s0" 4 2309.IP "\s-1EV_H\s0" 4
1730.IX Item "EV_H" 2310.IX Item "EV_H"
1731The name of the \fIev.h\fR header file used to include it. The default if 2311The name of the \fIev.h\fR header file used to include it. The default if
1732undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This 2312undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This
1733can be used to virtually rename the \fIev.h\fR header file in case of conflicts. 2313can be used to virtually rename the \fIev.h\fR header file in case of conflicts.
… …
1751If undefined or defined to \f(CW1\fR, then all event-loop-specific functions 2331If undefined or defined to \f(CW1\fR, then all event-loop-specific functions
1752will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create 2332will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create
1753additional independent event loops. Otherwise there will be no support 2333additional independent event loops. Otherwise there will be no support
1754for multiple event loops and there is no first event loop pointer 2334for multiple event loops and there is no first event loop pointer
1755argument. Instead, all functions act on the single default loop. 2335argument. Instead, all functions act on the single default loop.
2336.IP "\s-1EV_MINPRI\s0" 4
2337.IX Item "EV_MINPRI"
2338.PD 0
2339.IP "\s-1EV_MAXPRI\s0" 4
2340.IX Item "EV_MAXPRI"
2341.PD
2342The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to
2343\&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can
2344provide for more priorities by overriding those symbols (usually defined
2345to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively).
2346.Sp
2347When doing priority-based operations, libev usually has to linearly search
2348all the priorities, so having many of them (hundreds) uses a lot of space
2349and time, so using the defaults of five priorities (\-2 .. +2) is usually
2350fine.
2351.Sp
2352If your embedding app does not need any priorities, defining these both to
2353\&\f(CW0\fR will save some memory and cpu.
1756.IP "\s-1EV_PERIODICS\s0" 4 2354.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
1757.IX Item "EV_PERIODICS" 2355.IX Item "EV_PERIODIC_ENABLE"
1758If undefined or defined to be \f(CW1\fR, then periodic timers are supported, 2356If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
1759otherwise not. This saves a few kb of code. 2357defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2358code.
2359.IP "\s-1EV_IDLE_ENABLE\s0" 4
2360.IX Item "EV_IDLE_ENABLE"
2361If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If
2362defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2363code.
2364.IP "\s-1EV_EMBED_ENABLE\s0" 4
2365.IX Item "EV_EMBED_ENABLE"
2366If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If
2367defined to be \f(CW0\fR, then they are not.
2368.IP "\s-1EV_STAT_ENABLE\s0" 4
2369.IX Item "EV_STAT_ENABLE"
2370If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If
2371defined to be \f(CW0\fR, then they are not.
2372.IP "\s-1EV_FORK_ENABLE\s0" 4
2373.IX Item "EV_FORK_ENABLE"
2374If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If
2375defined to be \f(CW0\fR, then they are not.
2376.IP "\s-1EV_MINIMAL\s0" 4
2377.IX Item "EV_MINIMAL"
2378If you need to shave off some kilobytes of code at the expense of some
2379speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override
2380some inlining decisions, saves roughly 30% codesize of amd64.
2381.IP "\s-1EV_PID_HASHSIZE\s0" 4
2382.IX Item "EV_PID_HASHSIZE"
2383\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by
2384pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more
2385than enough. If you need to manage thousands of children you might want to
2386increase this value (\fImust\fR be a power of two).
2387.IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4
2388.IX Item "EV_INOTIFY_HASHSIZE"
2389\&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by
2390inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR),
2391usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR
2392watchers you might want to increase this value (\fImust\fR be a power of
2393two).
1760.IP "\s-1EV_COMMON\s0" 4 2394.IP "\s-1EV_COMMON\s0" 4
1761.IX Item "EV_COMMON" 2395.IX Item "EV_COMMON"
1762By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining 2396By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
1763this macro to a something else you can include more and other types of 2397this macro to a something else you can include more and other types of
1764members. You have to define it each time you include one of the files, 2398members. You have to define it each time you include one of the files,
… …
1769.Vb 3 2403.Vb 3
1770\& #define EV_COMMON \e 2404\& #define EV_COMMON \e
1771\& SV *self; /* contains this struct */ \e 2405\& SV *self; /* contains this struct */ \e
1772\& SV *cb_sv, *fh /* note no trailing ";" */ 2406\& SV *cb_sv, *fh /* note no trailing ";" */
1773.Ve 2407.Ve
1774.IP "\s-1EV_CB_DECLARE\s0(type)" 4 2408.IP "\s-1EV_CB_DECLARE\s0 (type)" 4
1775.IX Item "EV_CB_DECLARE(type)" 2409.IX Item "EV_CB_DECLARE (type)"
1776.PD 0 2410.PD 0
1777.IP "\s-1EV_CB_INVOKE\s0(watcher,revents)" 4 2411.IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4
1778.IX Item "EV_CB_INVOKE(watcher,revents)" 2412.IX Item "EV_CB_INVOKE (watcher, revents)"
1779.IP "ev_set_cb(ev,cb)" 4 2413.IP "ev_set_cb (ev, cb)" 4
1780.IX Item "ev_set_cb(ev,cb)" 2414.IX Item "ev_set_cb (ev, cb)"
1781.PD 2415.PD
1782Can be used to change the callback member declaration in each watcher, 2416Can be used to change the callback member declaration in each watcher,
1783and the way callbacks are invoked and set. Must expand to a struct member 2417and the way callbacks are invoked and set. Must expand to a struct member
1784definition and a statement, respectively. See the \fIev.v\fR header file for 2418definition and a statement, respectively. See the \fIev.v\fR header file for
1785their default definitions. One possible use for overriding these is to 2419their default definitions. One possible use for overriding these is to
1786avoid the ev_loop pointer as first argument in all cases, or to use method 2420avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
1787calls instead of plain function calls in \*(C+. 2421method calls instead of plain function calls in \*(C+.
1788.Sh "\s-1EXAMPLES\s0" 2422.Sh "\s-1EXAMPLES\s0"
1789.IX Subsection "EXAMPLES" 2423.IX Subsection "EXAMPLES"
1790For a real-world example of a program the includes libev 2424For a real-world example of a program the includes libev
1791verbatim, you can have a look at the \s-1EV\s0 perl module 2425verbatim, you can have a look at the \s-1EV\s0 perl module
1792(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in 2426(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in
… …
1794interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file 2428interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file
1795will be compiled. It is pretty complex because it provides its own header 2429will be compiled. It is pretty complex because it provides its own header
1796file. 2430file.
1797.Sp 2431.Sp
1798The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file 2432The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
1799that everybody includes and which overrides some autoconf choices: 2433that everybody includes and which overrides some configure choices:
1800.Sp 2434.Sp
1801.Vb 4 2435.Vb 9
2436\& #define EV_MINIMAL 1
1802\& #define EV_USE_POLL 0 2437\& #define EV_USE_POLL 0
1803\& #define EV_MULTIPLICITY 0 2438\& #define EV_MULTIPLICITY 0
1804\& #define EV_PERIODICS 0 2439\& #define EV_PERIODIC_ENABLE 0
2440\& #define EV_STAT_ENABLE 0
2441\& #define EV_FORK_ENABLE 0
1805\& #define EV_CONFIG_H <config.h> 2442\& #define EV_CONFIG_H <config.h>
2443\& #define EV_MINPRI 0
2444\& #define EV_MAXPRI 0
1806.Ve 2445.Ve
1807.Sp 2446.Sp
1808.Vb 1 2447.Vb 1
1809\& #include "ev++.h" 2448\& #include "ev++.h"
1810.Ve 2449.Ve
… …
1813.Sp 2452.Sp
1814.Vb 2 2453.Vb 2
1815\& #include "ev_cpp.h" 2454\& #include "ev_cpp.h"
1816\& #include "ev.c" 2455\& #include "ev.c"
1817.Ve 2456.Ve
2457.SH "COMPLEXITIES"
2458.IX Header "COMPLEXITIES"
2459In this section the complexities of (many of) the algorithms used inside
2460libev will be explained. For complexity discussions about backends see the
2461documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
2462.Sp
2463All of the following are about amortised time: If an array needs to be
2464extended, libev needs to realloc and move the whole array, but this
2465happens asymptotically never with higher number of elements, so O(1) might
2466mean it might do a lengthy realloc operation in rare cases, but on average
2467it is much faster and asymptotically approaches constant time.
2468.RS 4
2469.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
2470.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
2471This means that, when you have a watcher that triggers in one hour and
2472there are 100 watchers that would trigger before that then inserting will
2473have to skip those 100 watchers.
2474.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
2475.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2476That means that for changing a timer costs less than removing/adding them
2477as only the relative motion in the event queue has to be paid for.
2478.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
2479.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2480These just add the watcher into an array or at the head of a list.
2481=item Stopping check/prepare/idle watchers: O(1)
2482.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
2483.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
2484These watchers are stored in lists then need to be walked to find the
2485correct watcher to remove. The lists are usually short (you don't usually
2486have many watchers waiting for the same fd or signal).
2487.IP "Finding the next timer per loop iteration: O(1)" 4
2488.IX Item "Finding the next timer per loop iteration: O(1)"
2489.PD 0
2490.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
2491.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
2492.PD
2493A change means an I/O watcher gets started or stopped, which requires
2494libev to recalculate its status (and possibly tell the kernel).
2495.IP "Activating one watcher: O(1)" 4
2496.IX Item "Activating one watcher: O(1)"
2497.PD 0
2498.IP "Priority handling: O(number_of_priorities)" 4
2499.IX Item "Priority handling: O(number_of_priorities)"
2500.PD
2501Priorities are implemented by allocating some space for each
2502priority. When doing priority-based operations, libev usually has to
2503linearly search all the priorities.
2504.RE
2505.RS 4
1818.SH "AUTHOR" 2506.SH "AUTHOR"
1819.IX Header "AUTHOR" 2507.IX Header "AUTHOR"
1820Marc Lehmann <libev@schmorp.de>. 2508Marc Lehmann <libev@schmorp.de>.

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