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Revision 1.5 by root, Fri Nov 23 04:36:03 2007 UTC vs.
Revision 1.28 by root, Tue Nov 27 20:26:50 2007 UTC

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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 "2007-11-23" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH "<STANDARD INPUT>" 1 "2007-11-27" "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"
142Libev is an event loop: you register interest in certain events (such as a 201Libev 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 202file descriptor being readable or a timeout occuring), and it will manage
144these event sources and provide your program with events. 203these event sources and provide your program with events.
… …
151watchers\fR, which are relatively small C structures you initialise with the 210watchers\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 211details of the event, and then hand it over to libev by \fIstarting\fR the
153watcher. 212watcher.
154.SH "FEATURES" 213.SH "FEATURES"
155.IX Header "FEATURES" 214.IX Header "FEATURES"
156Libev supports select, poll, the linux-specific epoll and the bsd-specific 215Libev 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 216bsd-specific \f(CW\*(C`kqueue\*(C'\fR and the solaris-specific event port mechanisms
158timers with customised rescheduling, signal events, process status change 217for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR),
159events (related to \s-1SIGCHLD\s0), and event watchers dealing with the event 218absolute timers with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous
160loop mechanism itself (idle, prepare and check watchers). It also is quite 219signals (\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and
161fast (see this benchmark comparing 220event watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR,
162it to libevent for example). 221\&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as
222file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events
223(\f(CW\*(C`ev_fork\*(C'\fR).
224.PP
225It also is quite fast (see this
226benchmark comparing it to libevent
227for example).
163.SH "CONVENTIONS" 228.SH "CONVENTIONS"
164.IX Header "CONVENTIONS" 229.IX Header "CONVENTIONS"
165Libev is very configurable. In this manual the default configuration 230Libev is very configurable. In this manual the default configuration will
166will be described, which supports multiple event loops. For more info 231be described, which supports multiple event loops. For more info about
167about various configuration options please have a look at the file 232various 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 233this manual. If libev was configured without support for multiple event
169support for multiple event loops, then all functions taking an initial 234loops, 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) 235(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" 236.SH "TIME REPRESENTATION"
173.IX Header "TIME REPRESENTATION" 237.IX Header "TIME REPRESENTATION"
174Libev represents time as a single floating point number, representing the 238Libev represents time as a single floating point number, representing the
175(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near 239(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 240the beginning of 1970, details are complicated, don't ask). This type is
177called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases 241called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases
178to the double type in C. 242to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on
243it, you should treat it as such.
179.SH "GLOBAL FUNCTIONS" 244.SH "GLOBAL FUNCTIONS"
180.IX Header "GLOBAL FUNCTIONS" 245.IX Header "GLOBAL FUNCTIONS"
181These functions can be called anytime, even before initialising the 246These functions can be called anytime, even before initialising the
182library in any way. 247library in any way.
183.IP "ev_tstamp ev_time ()" 4 248.IP "ev_tstamp ev_time ()" 4
… …
199.Sp 264.Sp
200Usually, it's a good idea to terminate if the major versions mismatch, 265Usually, it's a good idea to terminate if the major versions mismatch,
201as this indicates an incompatible change. Minor versions are usually 266as this indicates an incompatible change. Minor versions are usually
202compatible to older versions, so a larger minor version alone is usually 267compatible to older versions, so a larger minor version alone is usually
203not a problem. 268not a problem.
269.Sp
270Example: Make sure we haven't accidentally been linked against the wrong
271version.
272.Sp
273.Vb 3
274\& assert (("libev version mismatch",
275\& ev_version_major () == EV_VERSION_MAJOR
276\& && ev_version_minor () >= EV_VERSION_MINOR));
277.Ve
278.IP "unsigned int ev_supported_backends ()" 4
279.IX Item "unsigned int ev_supported_backends ()"
280Return the set of all backends (i.e. their corresponding \f(CW\*(C`EV_BACKEND_*\*(C'\fR
281value) compiled into this binary of libev (independent of their
282availability on the system you are running on). See \f(CW\*(C`ev_default_loop\*(C'\fR for
283a description of the set values.
284.Sp
285Example: make sure we have the epoll method, because yeah this is cool and
286a must have and can we have a torrent of it please!!!11
287.Sp
288.Vb 2
289\& assert (("sorry, no epoll, no sex",
290\& ev_supported_backends () & EVBACKEND_EPOLL));
291.Ve
292.IP "unsigned int ev_recommended_backends ()" 4
293.IX Item "unsigned int ev_recommended_backends ()"
294Return the set of all backends compiled into this binary of libev and also
295recommended for this platform. This set is often smaller than the one
296returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on
297most BSDs and will not be autodetected unless you explicitly request it
298(assuming you know what you are doing). This is the set of backends that
299libev will probe for if you specify no backends explicitly.
300.IP "unsigned int ev_embeddable_backends ()" 4
301.IX Item "unsigned int ev_embeddable_backends ()"
302Returns the set of backends that are embeddable in other event loops. This
303is the theoretical, all\-platform, value. To find which backends
304might be supported on the current system, you would need to look at
305\&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for
306recommended ones.
307.Sp
308See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.
204.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 309.IP "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" 4
205.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" 310.IX Item "ev_set_allocator (void *(*cb)(void *ptr, size_t size))"
206Sets the allocation function to use (the prototype is similar to the 311Sets the allocation function to use (the prototype and semantics are
207realloc C function, the semantics are identical). It is used to allocate 312identical to the realloc C function). It is used to allocate and free
208and free memory (no surprises here). If it returns zero when memory 313memory (no surprises here). If it returns zero when memory needs to be
209needs to be allocated, the library might abort or take some potentially 314allocated, the library might abort or take some potentially destructive
210destructive action. The default is your system realloc function. 315action. The default is your system realloc function.
211.Sp 316.Sp
212You could override this function in high-availability programs to, say, 317You could override this function in high-availability programs to, say,
213free some memory if it cannot allocate memory, to use a special allocator, 318free some memory if it cannot allocate memory, to use a special allocator,
214or even to sleep a while and retry until some memory is available. 319or even to sleep a while and retry until some memory is available.
320.Sp
321Example: Replace the libev allocator with one that waits a bit and then
322retries).
323.Sp
324.Vb 6
325\& static void *
326\& persistent_realloc (void *ptr, size_t size)
327\& {
328\& for (;;)
329\& {
330\& void *newptr = realloc (ptr, size);
331.Ve
332.Sp
333.Vb 2
334\& if (newptr)
335\& return newptr;
336.Ve
337.Sp
338.Vb 3
339\& sleep (60);
340\& }
341\& }
342.Ve
343.Sp
344.Vb 2
345\& ...
346\& ev_set_allocator (persistent_realloc);
347.Ve
215.IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 348.IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4
216.IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" 349.IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));"
217Set the callback function to call on a retryable syscall error (such 350Set the callback function to call on a retryable syscall error (such
218as failed select, poll, epoll_wait). The message is a printable string 351as failed select, poll, epoll_wait). The message is a printable string
219indicating the system call or subsystem causing the problem. If this 352indicating the system call or subsystem causing the problem. If this
220callback is set, then libev will expect it to remedy the sitution, no 353callback is set, then libev will expect it to remedy the sitution, no
221matter what, when it returns. That is, libev will generally retry the 354matter what, when it returns. That is, libev will generally retry the
222requested operation, or, if the condition doesn't go away, do bad stuff 355requested operation, or, if the condition doesn't go away, do bad stuff
223(such as abort). 356(such as abort).
357.Sp
358Example: This is basically the same thing that libev does internally, too.
359.Sp
360.Vb 6
361\& static void
362\& fatal_error (const char *msg)
363\& {
364\& perror (msg);
365\& abort ();
366\& }
367.Ve
368.Sp
369.Vb 2
370\& ...
371\& ev_set_syserr_cb (fatal_error);
372.Ve
224.SH "FUNCTIONS CONTROLLING THE EVENT LOOP" 373.SH "FUNCTIONS CONTROLLING THE EVENT LOOP"
225.IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" 374.IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP"
226An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR. The library knows two 375An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR. The library knows two
227types of such loops, the \fIdefault\fR loop, which supports signals and child 376types of such loops, the \fIdefault\fR loop, which supports signals and child
228events, and dynamically created loops which do not. 377events, and dynamically created loops which do not.
… …
236.IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 385.IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4
237.IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" 386.IX Item "struct ev_loop *ev_default_loop (unsigned int flags)"
238This will initialise the default event loop if it hasn't been initialised 387This will initialise the default event loop if it hasn't been initialised
239yet and return it. If the default loop could not be initialised, returns 388yet and return it. If the default loop could not be initialised, returns
240false. If it already was initialised it simply returns it (and ignores the 389false. If it already was initialised it simply returns it (and ignores the
241flags). 390flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards).
242.Sp 391.Sp
243If you don't know what event loop to use, use the one returned from this 392If you don't know what event loop to use, use the one returned from this
244function. 393function.
245.Sp 394.Sp
246The flags argument can be used to specify special behaviour or specific 395The flags argument can be used to specify special behaviour or specific
247backends to use, and is usually specified as 0 (or \s-1EVFLAG_AUTO\s0). 396backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR).
248.Sp 397.Sp
249It supports the following flags: 398The following flags are supported:
250.RS 4 399.RS 4
251.ie n .IP """EVFLAG_AUTO""" 4 400.ie n .IP """EVFLAG_AUTO""" 4
252.el .IP "\f(CWEVFLAG_AUTO\fR" 4 401.el .IP "\f(CWEVFLAG_AUTO\fR" 4
253.IX Item "EVFLAG_AUTO" 402.IX Item "EVFLAG_AUTO"
254The default flags value. Use this if you have no clue (it's the right 403The default flags value. Use this if you have no clue (it's the right
… …
260or setgid) then libev will \fInot\fR look at the environment variable 409or setgid) then libev will \fInot\fR look at the environment variable
261\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will 410\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will
262override the flags completely if it is found in the environment. This is 411override the flags completely if it is found in the environment. This is
263useful to try out specific backends to test their performance, or to work 412useful to try out specific backends to test their performance, or to work
264around bugs. 413around bugs.
265.ie n .IP """EVMETHOD_SELECT"" (value 1, portable select backend)" 4 414.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
266.el .IP "\f(CWEVMETHOD_SELECT\fR (value 1, portable select backend)" 4 415.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
267.IX Item "EVMETHOD_SELECT (value 1, portable select backend)" 416.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
268This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 417This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as
269libev tries to roll its own fd_set with no limits on the number of fds, 418libev tries to roll its own fd_set with no limits on the number of fds,
270but if that fails, expect a fairly low limit on the number of fds when 419but if that fails, expect a fairly low limit on the number of fds when
271using this backend. It doesn't scale too well (O(highest_fd)), but its usually 420using this backend. It doesn't scale too well (O(highest_fd)), but its usually
272the fastest backend for a low number of fds. 421the fastest backend for a low number of fds.
273.ie n .IP """EVMETHOD_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 422.ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4
274.el .IP "\f(CWEVMETHOD_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 423.el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4
275.IX Item "EVMETHOD_POLL (value 2, poll backend, available everywhere except on windows)" 424.IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)"
276And this is your standard \fIpoll\fR\|(2) backend. It's more complicated than 425And this is your standard \fIpoll\fR\|(2) backend. It's more complicated than
277select, but handles sparse fds better and has no artificial limit on the 426select, but handles sparse fds better and has no artificial limit on the
278number of fds you can use (except it will slow down considerably with a 427number of fds you can use (except it will slow down considerably with a
279lot of inactive fds). It scales similarly to select, i.e. O(total_fds). 428lot of inactive fds). It scales similarly to select, i.e. O(total_fds).
280.ie n .IP """EVMETHOD_EPOLL"" (value 4, Linux)" 4 429.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4
281.el .IP "\f(CWEVMETHOD_EPOLL\fR (value 4, Linux)" 4 430.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4
282.IX Item "EVMETHOD_EPOLL (value 4, Linux)" 431.IX Item "EVBACKEND_EPOLL (value 4, Linux)"
283For few fds, this backend is a bit little slower than poll and select, 432For few fds, this backend is a bit little slower than poll and select,
284but it scales phenomenally better. While poll and select usually scale like 433but it scales phenomenally better. While poll and select usually scale like
285O(total_fds) where n is the total number of fds (or the highest fd), epoll scales 434O(total_fds) where n is the total number of fds (or the highest fd), epoll scales
286either O(1) or O(active_fds). 435either O(1) or O(active_fds).
287.Sp 436.Sp
288While stopping and starting an I/O watcher in the same iteration will 437While stopping and starting an I/O watcher in the same iteration will
289result in some caching, there is still a syscall per such incident 438result in some caching, there is still a syscall per such incident
290(because the fd could point to a different file description now), so its 439(because the fd could point to a different file description now), so its
291best to avoid that. Also, \fIdup()\fRed file descriptors might not work very 440best to avoid that. Also, \fIdup()\fRed file descriptors might not work very
292well if you register events for both fds. 441well if you register events for both fds.
442.Sp
443Please note that epoll sometimes generates spurious notifications, so you
444need to use non-blocking I/O or other means to avoid blocking when no data
445(or space) is available.
293.ie n .IP """EVMETHOD_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 446.ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4
294.el .IP "\f(CWEVMETHOD_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 447.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4
295.IX Item "EVMETHOD_KQUEUE (value 8, most BSD clones)" 448.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"
296Kqueue deserves special mention, as at the time of this writing, it 449Kqueue deserves special mention, as at the time of this writing, it
297was broken on all BSDs except NetBSD (usually it doesn't work with 450was broken on all BSDs except NetBSD (usually it doesn't work with
298anything but sockets and pipes, except on Darwin, where of course its 451anything but sockets and pipes, except on Darwin, where of course its
299completely useless). For this reason its not being \*(L"autodetected\*(R" unless 452completely useless). For this reason its not being \*(L"autodetected\*(R"
300you explicitly specify the flags (i.e. you don't use \s-1EVFLAG_AUTO\s0). 453unless you explicitly specify it explicitly in the flags (i.e. using
454\&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR).
301.Sp 455.Sp
302It scales in the same way as the epoll backend, but the interface to the 456It scales in the same way as the epoll backend, but the interface to the
303kernel is more efficient (which says nothing about its actual speed, of 457kernel is more efficient (which says nothing about its actual speed, of
304course). While starting and stopping an I/O watcher does not cause an 458course). While starting and stopping an I/O watcher does not cause an
305extra syscall as with epoll, it still adds up to four event changes per 459extra syscall as with epoll, it still adds up to four event changes per
306incident, so its best to avoid that. 460incident, so its best to avoid that.
307.ie n .IP """EVMETHOD_DEVPOLL"" (value 16, Solaris 8)" 4 461.ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4
308.el .IP "\f(CWEVMETHOD_DEVPOLL\fR (value 16, Solaris 8)" 4 462.el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4
309.IX Item "EVMETHOD_DEVPOLL (value 16, Solaris 8)" 463.IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)"
310This is not implemented yet (and might never be). 464This is not implemented yet (and might never be).
311.ie n .IP """EVMETHOD_PORT"" (value 32, Solaris 10)" 4 465.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4
312.el .IP "\f(CWEVMETHOD_PORT\fR (value 32, Solaris 10)" 4 466.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4
313.IX Item "EVMETHOD_PORT (value 32, Solaris 10)" 467.IX Item "EVBACKEND_PORT (value 32, Solaris 10)"
314This uses the Solaris 10 port mechanism. As with everything on Solaris, 468This uses the Solaris 10 port mechanism. As with everything on Solaris,
315it's really slow, but it still scales very well (O(active_fds)). 469it's really slow, but it still scales very well (O(active_fds)).
470.Sp
471Please note that solaris ports can result in a lot of spurious
472notifications, so you need to use non-blocking I/O or other means to avoid
473blocking when no data (or space) is available.
316.ie n .IP """EVMETHOD_ALL""" 4 474.ie n .IP """EVBACKEND_ALL""" 4
317.el .IP "\f(CWEVMETHOD_ALL\fR" 4 475.el .IP "\f(CWEVBACKEND_ALL\fR" 4
318.IX Item "EVMETHOD_ALL" 476.IX Item "EVBACKEND_ALL"
319Try all backends (even potentially broken ones that wouldn't be tried 477Try all backends (even potentially broken ones that wouldn't be tried
320with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as 478with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as
321\&\f(CW\*(C`EVMETHOD_ALL & ~EVMETHOD_KQUEUE\*(C'\fR. 479\&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR.
322.RE 480.RE
323.RS 4 481.RS 4
324.Sp 482.Sp
325If one or more of these are ored into the flags value, then only these 483If one or more of these are ored into the flags value, then only these
326backends will be tried (in the reverse order as given here). If none are 484backends will be tried (in the reverse order as given here). If none are
327specified, most compiled-in backend will be tried, usually in reverse 485specified, most compiled-in backend will be tried, usually in reverse
328order of their flag values :) 486order of their flag values :)
487.Sp
488The most typical usage is like this:
489.Sp
490.Vb 2
491\& if (!ev_default_loop (0))
492\& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
493.Ve
494.Sp
495Restrict libev to the select and poll backends, and do not allow
496environment settings to be taken into account:
497.Sp
498.Vb 1
499\& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
500.Ve
501.Sp
502Use whatever libev has to offer, but make sure that kqueue is used if
503available (warning, breaks stuff, best use only with your own private
504event loop and only if you know the \s-1OS\s0 supports your types of fds):
505.Sp
506.Vb 1
507\& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
508.Ve
329.RE 509.RE
330.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 510.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4
331.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" 511.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)"
332Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is 512Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is
333always distinct from the default loop. Unlike the default loop, it cannot 513always distinct from the default loop. Unlike the default loop, it cannot
334handle signal and child watchers, and attempts to do so will be greeted by 514handle signal and child watchers, and attempts to do so will be greeted by
335undefined behaviour (or a failed assertion if assertions are enabled). 515undefined behaviour (or a failed assertion if assertions are enabled).
516.Sp
517Example: Try to create a event loop that uses epoll and nothing else.
518.Sp
519.Vb 3
520\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
521\& if (!epoller)
522\& fatal ("no epoll found here, maybe it hides under your chair");
523.Ve
336.IP "ev_default_destroy ()" 4 524.IP "ev_default_destroy ()" 4
337.IX Item "ev_default_destroy ()" 525.IX Item "ev_default_destroy ()"
338Destroys the default loop again (frees all memory and kernel state 526Destroys the default loop again (frees all memory and kernel state
339etc.). This stops all registered event watchers (by not touching them in 527etc.). None of the active event watchers will be stopped in the normal
340any way whatsoever, although you cannot rely on this :). 528sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your
529responsibility to either stop all watchers cleanly yoursef \fIbefore\fR
530calling this function, or cope with the fact afterwards (which is usually
531the easiest thing, youc na just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them
532for example).
341.IP "ev_loop_destroy (loop)" 4 533.IP "ev_loop_destroy (loop)" 4
342.IX Item "ev_loop_destroy (loop)" 534.IX Item "ev_loop_destroy (loop)"
343Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an 535Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an
344earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. 536earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR.
345.IP "ev_default_fork ()" 4 537.IP "ev_default_fork ()" 4
… …
358quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: 550quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR:
359.Sp 551.Sp
360.Vb 1 552.Vb 1
361\& pthread_atfork (0, 0, ev_default_fork); 553\& pthread_atfork (0, 0, ev_default_fork);
362.Ve 554.Ve
555.Sp
556At the moment, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR are safe to use
557without calling this function, so if you force one of those backends you
558do not need to care.
363.IP "ev_loop_fork (loop)" 4 559.IP "ev_loop_fork (loop)" 4
364.IX Item "ev_loop_fork (loop)" 560.IX Item "ev_loop_fork (loop)"
365Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by 561Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by
366\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop 562\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop
367after fork, and how you do this is entirely your own problem. 563after fork, and how you do this is entirely your own problem.
368.IP "unsigned int ev_method (loop)" 4 564.IP "unsigned int ev_backend (loop)" 4
369.IX Item "unsigned int ev_method (loop)" 565.IX Item "unsigned int ev_backend (loop)"
370Returns one of the \f(CW\*(C`EVMETHOD_*\*(C'\fR flags indicating the event backend in 566Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
371use. 567use.
372.IP "ev_tstamp ev_now (loop)" 4 568.IP "ev_tstamp ev_now (loop)" 4
373.IX Item "ev_tstamp ev_now (loop)" 569.IX Item "ev_tstamp ev_now (loop)"
374Returns the current \*(L"event loop time\*(R", which is the time the event loop 570Returns the current \*(L"event loop time\*(R", which is the time the event loop
375got events and started processing them. This timestamp does not change 571received events and started processing them. This timestamp does not
376as long as callbacks are being processed, and this is also the base time 572change as long as callbacks are being processed, and this is also the base
377used for relative timers. You can treat it as the timestamp of the event 573time used for relative timers. You can treat it as the timestamp of the
378occuring (or more correctly, the mainloop finding out about it). 574event occuring (or more correctly, libev finding out about it).
379.IP "ev_loop (loop, int flags)" 4 575.IP "ev_loop (loop, int flags)" 4
380.IX Item "ev_loop (loop, int flags)" 576.IX Item "ev_loop (loop, int flags)"
381Finally, this is it, the event handler. This function usually is called 577Finally, this is it, the event handler. This function usually is called
382after you initialised all your watchers and you want to start handling 578after you initialised all your watchers and you want to start handling
383events. 579events.
384.Sp 580.Sp
385If the flags argument is specified as 0, it will not return until either 581If the flags argument is specified as \f(CW0\fR, it will not return until
386no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. 582either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called.
583.Sp
584Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than
585relying on all watchers to be stopped when deciding when a program has
586finished (especially in interactive programs), but having a program that
587automatically loops as long as it has to and no longer by virtue of
588relying on its watchers stopping correctly is a thing of beauty.
387.Sp 589.Sp
388A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle 590A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle
389those events and any outstanding ones, but will not block your process in 591those events and any outstanding ones, but will not block your process in
390case there are no events and will return after one iteration of the loop. 592case there are no events and will return after one iteration of the loop.
391.Sp 593.Sp
392A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if 594A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if
393neccessary) and will handle those and any outstanding ones. It will block 595neccessary) and will handle those and any outstanding ones. It will block
394your process until at least one new event arrives, and will return after 596your process until at least one new event arrives, and will return after
395one iteration of the loop. 597one iteration of the loop. This is useful if you are waiting for some
598external event in conjunction with something not expressible using other
599libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is
600usually a better approach for this kind of thing.
396.Sp 601.Sp
397This flags value could be used to implement alternative looping
398constructs, but the \f(CW\*(C`prepare\*(C'\fR and \f(CW\*(C`check\*(C'\fR watchers provide a better and
399more generic mechanism.
400.Sp
401Here are the gory details of what ev_loop does: 602Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does:
402.Sp 603.Sp
403.Vb 15 604.Vb 18
404\& 1. If there are no active watchers (reference count is zero), return. 605\& * If there are no active watchers (reference count is zero), return.
405\& 2. Queue and immediately call all prepare watchers. 606\& - Queue prepare watchers and then call all outstanding watchers.
406\& 3. If we have been forked, recreate the kernel state. 607\& - If we have been forked, recreate the kernel state.
407\& 4. Update the kernel state with all outstanding changes. 608\& - Update the kernel state with all outstanding changes.
408\& 5. Update the "event loop time". 609\& - Update the "event loop time".
409\& 6. Calculate for how long to block. 610\& - Calculate for how long to block.
410\& 7. Block the process, waiting for events. 611\& - Block the process, waiting for any events.
612\& - Queue all outstanding I/O (fd) events.
411\& 8. Update the "event loop time" and do time jump handling. 613\& - Update the "event loop time" and do time jump handling.
412\& 9. Queue all outstanding timers. 614\& - Queue all outstanding timers.
413\& 10. Queue all outstanding periodics. 615\& - Queue all outstanding periodics.
414\& 11. If no events are pending now, queue all idle watchers. 616\& - If no events are pending now, queue all idle watchers.
415\& 12. Queue all check watchers. 617\& - Queue all check watchers.
416\& 13. Call all queued watchers in reverse order (i.e. check watchers first). 618\& - Call all queued watchers in reverse order (i.e. check watchers first).
619\& Signals and child watchers are implemented as I/O watchers, and will
620\& be handled here by queueing them when their watcher gets executed.
417\& 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK 621\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
418\& was used, return, otherwise continue with step #1. 622\& were used, return, otherwise continue with step *.
623.Ve
624.Sp
625Example: Queue some jobs and then loop until no events are outsanding
626anymore.
627.Sp
628.Vb 4
629\& ... queue jobs here, make sure they register event watchers as long
630\& ... as they still have work to do (even an idle watcher will do..)
631\& ev_loop (my_loop, 0);
632\& ... jobs done. yeah!
419.Ve 633.Ve
420.IP "ev_unloop (loop, how)" 4 634.IP "ev_unloop (loop, how)" 4
421.IX Item "ev_unloop (loop, how)" 635.IX Item "ev_unloop (loop, how)"
422Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it 636Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it
423has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either 637has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either
… …
437example, libev itself uses this for its internal signal pipe: It is not 651example, libev itself uses this for its internal signal pipe: It is not
438visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if 652visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if
439no event watchers registered by it are active. It is also an excellent 653no event watchers registered by it are active. It is also an excellent
440way to do this for generic recurring timers or from within third-party 654way to do this for generic recurring timers or from within third-party
441libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR. 655libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.
656.Sp
657Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR
658running when nothing else is active.
659.Sp
660.Vb 4
661\& struct ev_signal exitsig;
662\& ev_signal_init (&exitsig, sig_cb, SIGINT);
663\& ev_signal_start (loop, &exitsig);
664\& evf_unref (loop);
665.Ve
666.Sp
667Example: For some weird reason, unregister the above signal handler again.
668.Sp
669.Vb 2
670\& ev_ref (loop);
671\& ev_signal_stop (loop, &exitsig);
672.Ve
442.SH "ANATOMY OF A WATCHER" 673.SH "ANATOMY OF A WATCHER"
443.IX Header "ANATOMY OF A WATCHER" 674.IX Header "ANATOMY OF A WATCHER"
444A watcher is a structure that you create and register to record your 675A watcher is a structure that you create and register to record your
445interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to 676interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to
446become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: 677become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that:
… …
482*)\*(C'\fR), and you can stop watching for events at any time by calling the 713*)\*(C'\fR), and you can stop watching for events at any time by calling the
483corresponding stop function (\f(CW\*(C`ev_<type>_stop (loop, watcher *)\*(C'\fR. 714corresponding stop function (\f(CW\*(C`ev_<type>_stop (loop, watcher *)\*(C'\fR.
484.PP 715.PP
485As long as your watcher is active (has been started but not stopped) you 716As long as your watcher is active (has been started but not stopped) you
486must not touch the values stored in it. Most specifically you must never 717must not touch the values stored in it. Most specifically you must never
487reinitialise it or call its set method. 718reinitialise it or call its \f(CW\*(C`set\*(C'\fR macro.
488.PP
489You can check whether an event is active by calling the \f(CW\*(C`ev_is_active
490(watcher *)\*(C'\fR macro. To see whether an event is outstanding (but the
491callback for it has not been called yet) you can use the \f(CW\*(C`ev_is_pending
492(watcher *)\*(C'\fR macro.
493.PP 719.PP
494Each and every callback receives the event loop pointer as first, the 720Each and every callback receives the event loop pointer as first, the
495registered watcher structure as second, and a bitset of received events as 721registered watcher structure as second, and a bitset of received events as
496third argument. 722third argument.
497.PP 723.PP
… …
522The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread. 748The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread.
523.ie n .IP """EV_CHILD""" 4 749.ie n .IP """EV_CHILD""" 4
524.el .IP "\f(CWEV_CHILD\fR" 4 750.el .IP "\f(CWEV_CHILD\fR" 4
525.IX Item "EV_CHILD" 751.IX Item "EV_CHILD"
526The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change. 752The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change.
753.ie n .IP """EV_STAT""" 4
754.el .IP "\f(CWEV_STAT\fR" 4
755.IX Item "EV_STAT"
756The path specified in the \f(CW\*(C`ev_stat\*(C'\fR watcher changed its attributes somehow.
527.ie n .IP """EV_IDLE""" 4 757.ie n .IP """EV_IDLE""" 4
528.el .IP "\f(CWEV_IDLE\fR" 4 758.el .IP "\f(CWEV_IDLE\fR" 4
529.IX Item "EV_IDLE" 759.IX Item "EV_IDLE"
530The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do. 760The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do.
531.ie n .IP """EV_PREPARE""" 4 761.ie n .IP """EV_PREPARE""" 4
… …
541\&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any 771\&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any
542received events. Callbacks of both watcher types can start and stop as 772received events. Callbacks of both watcher types can start and stop as
543many watchers as they want, and all of them will be taken into account 773many watchers as they want, and all of them will be taken into account
544(for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep 774(for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep
545\&\f(CW\*(C`ev_loop\*(C'\fR from blocking). 775\&\f(CW\*(C`ev_loop\*(C'\fR from blocking).
776.ie n .IP """EV_EMBED""" 4
777.el .IP "\f(CWEV_EMBED\fR" 4
778.IX Item "EV_EMBED"
779The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention.
780.ie n .IP """EV_FORK""" 4
781.el .IP "\f(CWEV_FORK\fR" 4
782.IX Item "EV_FORK"
783The event loop has been resumed in the child process after fork (see
784\&\f(CW\*(C`ev_fork\*(C'\fR).
546.ie n .IP """EV_ERROR""" 4 785.ie n .IP """EV_ERROR""" 4
547.el .IP "\f(CWEV_ERROR\fR" 4 786.el .IP "\f(CWEV_ERROR\fR" 4
548.IX Item "EV_ERROR" 787.IX Item "EV_ERROR"
549An unspecified error has occured, the watcher has been stopped. This might 788An unspecified error has occured, the watcher has been stopped. This might
550happen because the watcher could not be properly started because libev 789happen because the watcher could not be properly started because libev
… …
555Libev will usually signal a few \*(L"dummy\*(R" events together with an error, 794Libev will usually signal a few \*(L"dummy\*(R" events together with an error,
556for example it might indicate that a fd is readable or writable, and if 795for example it might indicate that a fd is readable or writable, and if
557your callbacks is well-written it can just attempt the operation and cope 796your callbacks is well-written it can just attempt the operation and cope
558with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded 797with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded
559programs, though, so beware. 798programs, though, so beware.
799.Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0"
800.IX Subsection "GENERIC WATCHER FUNCTIONS"
801In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type,
802e.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.
803.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4
804.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4
805.IX Item "ev_init (ev_TYPE *watcher, callback)"
806This macro initialises the generic portion of a watcher. The contents
807of the watcher object can be arbitrary (so \f(CW\*(C`malloc\*(C'\fR will do). Only
808the generic parts of the watcher are initialised, you \fIneed\fR to call
809the type-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR macro afterwards to initialise the
810type-specific parts. For each type there is also a \f(CW\*(C`ev_TYPE_init\*(C'\fR macro
811which rolls both calls into one.
812.Sp
813You can reinitialise a watcher at any time as long as it has been stopped
814(or never started) and there are no pending events outstanding.
815.Sp
816The callback is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher,
817int revents)\*(C'\fR.
818.ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4
819.el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4
820.IX Item "ev_TYPE_set (ev_TYPE *, [args])"
821This macro initialises the type-specific parts of a watcher. You need to
822call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can
823call \f(CW\*(C`ev_TYPE_set\*(C'\fR any number of times. You must not, however, call this
824macro on a watcher that is active (it can be pending, however, which is a
825difference to the \f(CW\*(C`ev_init\*(C'\fR macro).
826.Sp
827Although some watcher types do not have type-specific arguments
828(e.g. \f(CW\*(C`ev_prepare\*(C'\fR) you still need to call its \f(CW\*(C`set\*(C'\fR macro.
829.ie n .IP """ev_TYPE_init"" (ev_TYPE *watcher, callback, [args])" 4
830.el .IP "\f(CWev_TYPE_init\fR (ev_TYPE *watcher, callback, [args])" 4
831.IX Item "ev_TYPE_init (ev_TYPE *watcher, callback, [args])"
832This convinience macro rolls both \f(CW\*(C`ev_init\*(C'\fR and \f(CW\*(C`ev_TYPE_set\*(C'\fR macro
833calls into a single call. This is the most convinient method to initialise
834a watcher. The same limitations apply, of course.
835.ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4
836.el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4
837.IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)"
838Starts (activates) the given watcher. Only active watchers will receive
839events. If the watcher is already active nothing will happen.
840.ie n .IP """ev_TYPE_stop"" (loop *, ev_TYPE *watcher)" 4
841.el .IP "\f(CWev_TYPE_stop\fR (loop *, ev_TYPE *watcher)" 4
842.IX Item "ev_TYPE_stop (loop *, ev_TYPE *watcher)"
843Stops the given watcher again (if active) and clears the pending
844status. It is possible that stopped watchers are pending (for example,
845non-repeating timers are being stopped when they become pending), but
846\&\f(CW\*(C`ev_TYPE_stop\*(C'\fR ensures that the watcher is neither active nor pending. If
847you want to free or reuse the memory used by the watcher it is therefore a
848good idea to always call its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function.
849.IP "bool ev_is_active (ev_TYPE *watcher)" 4
850.IX Item "bool ev_is_active (ev_TYPE *watcher)"
851Returns a true value iff the watcher is active (i.e. it has been started
852and not yet been stopped). As long as a watcher is active you must not modify
853it.
854.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
855.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
856Returns a true value iff the watcher is pending, (i.e. it has outstanding
857events but its callback has not yet been invoked). As long as a watcher
858is pending (but not active) you must not call an init function on it (but
859\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to
860libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it).
861.IP "callback = ev_cb (ev_TYPE *watcher)" 4
862.IX Item "callback = ev_cb (ev_TYPE *watcher)"
863Returns the callback currently set on the watcher.
864.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
865.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
866Change the callback. You can change the callback at virtually any time
867(modulo threads).
560.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 868.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
561.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 869.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
562Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change 870Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change
563and read at any time, libev will completely ignore it. This can be used 871and read at any time, libev will completely ignore it. This can be used
564to associate arbitrary data with your watcher. If you need more data and 872to associate arbitrary data with your watcher. If you need more data and
… …
590More interesting and less C\-conformant ways of catsing your callback type 898More interesting and less C\-conformant ways of catsing your callback type
591have been omitted.... 899have been omitted....
592.SH "WATCHER TYPES" 900.SH "WATCHER TYPES"
593.IX Header "WATCHER TYPES" 901.IX Header "WATCHER TYPES"
594This section describes each watcher in detail, but will not repeat 902This section describes each watcher in detail, but will not repeat
595information given in the last section. 903information given in the last section. Any initialisation/set macros,
904functions and members specific to the watcher type are explained.
905.PP
906Members are additionally marked with either \fI[read\-only]\fR, meaning that,
907while the watcher is active, you can look at the member and expect some
908sensible content, but you must not modify it (you can modify it while the
909watcher is stopped to your hearts content), or \fI[read\-write]\fR, which
910means you can expect it to have some sensible content while the watcher
911is active, but you can also modify it. Modifying it may not do something
912sensible or take immediate effect (or do anything at all), but libev will
913not crash or malfunction in any way.
596.ie n .Sh """ev_io"" \- is this file descriptor readable or writable" 914.ie n .Sh """ev_io"" \- is this file descriptor readable or writable?"
597.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable" 915.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?"
598.IX Subsection "ev_io - is this file descriptor readable or writable" 916.IX Subsection "ev_io - is this file descriptor readable or writable?"
599I/O watchers check whether a file descriptor is readable or writable 917I/O watchers check whether a file descriptor is readable or writable
600in each iteration of the event loop (This behaviour is called 918in each iteration of the event loop, or, more precisely, when reading
601level-triggering because you keep receiving events as long as the 919would not block the process and writing would at least be able to write
602condition persists. Remember you can stop the watcher if you don't want to 920some data. This behaviour is called level-triggering because you keep
603act on the event and neither want to receive future events). 921receiving events as long as the condition persists. Remember you can stop
922the watcher if you don't want to act on the event and neither want to
923receive future events.
604.PP 924.PP
605In general you can register as many read and/or write event watchers per 925In general you can register as many read and/or write event watchers per
606fd as you want (as long as you don't confuse yourself). Setting all file 926fd as you want (as long as you don't confuse yourself). Setting all file
607descriptors to non-blocking mode is also usually a good idea (but not 927descriptors to non-blocking mode is also usually a good idea (but not
608required if you know what you are doing). 928required if you know what you are doing).
609.PP 929.PP
610You have to be careful with dup'ed file descriptors, though. Some backends 930You have to be careful with dup'ed file descriptors, though. Some backends
611(the linux epoll backend is a notable example) cannot handle dup'ed file 931(the linux epoll backend is a notable example) cannot handle dup'ed file
612descriptors correctly if you register interest in two or more fds pointing 932descriptors correctly if you register interest in two or more fds pointing
613to the same underlying file/socket etc. description (that is, they share 933to the same underlying file/socket/etc. description (that is, they share
614the same underlying \*(L"file open\*(R"). 934the same underlying \*(L"file open\*(R").
615.PP 935.PP
616If you must do this, then force the use of a known-to-be-good backend 936If you must do this, then force the use of a known-to-be-good backend
617(at the time of this writing, this includes only \s-1EVMETHOD_SELECT\s0 and 937(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and
618\&\s-1EVMETHOD_POLL\s0). 938\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR).
939.PP
940Another thing you have to watch out for is that it is quite easy to
941receive \*(L"spurious\*(R" readyness notifications, that is your callback might
942be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block
943because there is no data. Not only are some backends known to create a
944lot of those (for example solaris ports), it is very easy to get into
945this situation even with a relatively standard program structure. Thus
946it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning
947\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
948.PP
949If you cannot run the fd in non-blocking mode (for example you should not
950play around with an Xlib connection), then you have to seperately re-test
951wether a file descriptor is really ready with a known-to-be good interface
952such as poll (fortunately in our Xlib example, Xlib already does this on
953its own, so its quite safe to use).
619.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 954.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
620.IX Item "ev_io_init (ev_io *, callback, int fd, int events)" 955.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
621.PD 0 956.PD 0
622.IP "ev_io_set (ev_io *, int fd, int events)" 4 957.IP "ev_io_set (ev_io *, int fd, int events)" 4
623.IX Item "ev_io_set (ev_io *, int fd, int events)" 958.IX Item "ev_io_set (ev_io *, int fd, int events)"
624.PD 959.PD
625Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The fd is the file descriptor to rceeive 960Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to
626events 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 | 961rceeive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or
627EV_WRITE\*(C'\fR to receive the given events. 962\&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events.
963.IP "int fd [read\-only]" 4
964.IX Item "int fd [read-only]"
965The file descriptor being watched.
966.IP "int events [read\-only]" 4
967.IX Item "int events [read-only]"
968The events being watched.
969.PP
970Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well
971readable, but only once. Since it is likely line\-buffered, you could
972attempt to read a whole line in the callback.
973.PP
974.Vb 6
975\& static void
976\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
977\& {
978\& ev_io_stop (loop, w);
979\& .. read from stdin here (or from w->fd) and haqndle any I/O errors
980\& }
981.Ve
982.PP
983.Vb 6
984\& ...
985\& struct ev_loop *loop = ev_default_init (0);
986\& struct ev_io stdin_readable;
987\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
988\& ev_io_start (loop, &stdin_readable);
989\& ev_loop (loop, 0);
990.Ve
628.ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts" 991.ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts"
629.el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts" 992.el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts"
630.IX Subsection "ev_timer - relative and optionally recurring timeouts" 993.IX Subsection "ev_timer - relative and optionally repeating timeouts"
631Timer watchers are simple relative timers that generate an event after a 994Timer watchers are simple relative timers that generate an event after a
632given time, and optionally repeating in regular intervals after that. 995given time, and optionally repeating in regular intervals after that.
633.PP 996.PP
634The timers are based on real time, that is, if you register an event that 997The timers are based on real time, that is, if you register an event that
635times out after an hour and you reset your system clock to last years 998times out after an hour and you reset your system clock to last years
… …
675.Sp 1038.Sp
676If the timer is repeating, either start it if necessary (with the repeat 1039If the timer is repeating, either start it if necessary (with the repeat
677value), or reset the running timer to the repeat value. 1040value), or reset the running timer to the repeat value.
678.Sp 1041.Sp
679This sounds a bit complicated, but here is a useful and typical 1042This sounds a bit complicated, but here is a useful and typical
680example: Imagine you have a tcp connection and you want a so-called idle 1043example: Imagine you have a tcp connection and you want a so-called
681timeout, that is, you want to be called when there have been, say, 60 1044idle timeout, that is, you want to be called when there have been,
682seconds of inactivity on the socket. The easiest way to do this is to 1045say, 60 seconds of inactivity on the socket. The easiest way to do
683configure an \f(CW\*(C`ev_timer\*(C'\fR with after=repeat=60 and calling ev_timer_again each 1046this is to configure an \f(CW\*(C`ev_timer\*(C'\fR with \f(CW\*(C`after\*(C'\fR=\f(CW\*(C`repeat\*(C'\fR=\f(CW60\fR and calling
684time you successfully read or write some data. If you go into an idle 1047\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If
685state where you do not expect data to travel on the socket, you can stop 1048you go into an idle state where you do not expect data to travel on the
686the timer, and again will automatically restart it if need be. 1049socket, you can stop the timer, and again will automatically restart it if
1050need be.
1051.Sp
1052You can also ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR altogether
1053and only ever use the \f(CW\*(C`repeat\*(C'\fR value:
1054.Sp
1055.Vb 8
1056\& ev_timer_init (timer, callback, 0., 5.);
1057\& ev_timer_again (loop, timer);
1058\& ...
1059\& timer->again = 17.;
1060\& ev_timer_again (loop, timer);
1061\& ...
1062\& timer->again = 10.;
1063\& ev_timer_again (loop, timer);
1064.Ve
1065.Sp
1066This is more efficient then stopping/starting the timer eahc time you want
1067to modify its timeout value.
1068.IP "ev_tstamp repeat [read\-write]" 4
1069.IX Item "ev_tstamp repeat [read-write]"
1070The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out
1071or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any),
1072which is also when any modifications are taken into account.
1073.PP
1074Example: Create a timer that fires after 60 seconds.
1075.PP
1076.Vb 5
1077\& static void
1078\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1079\& {
1080\& .. one minute over, w is actually stopped right here
1081\& }
1082.Ve
1083.PP
1084.Vb 3
1085\& struct ev_timer mytimer;
1086\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1087\& ev_timer_start (loop, &mytimer);
1088.Ve
1089.PP
1090Example: Create a timeout timer that times out after 10 seconds of
1091inactivity.
1092.PP
1093.Vb 5
1094\& static void
1095\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1096\& {
1097\& .. ten seconds without any activity
1098\& }
1099.Ve
1100.PP
1101.Vb 4
1102\& struct ev_timer mytimer;
1103\& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1104\& ev_timer_again (&mytimer); /* start timer */
1105\& ev_loop (loop, 0);
1106.Ve
1107.PP
1108.Vb 3
1109\& // and in some piece of code that gets executed on any "activity":
1110\& // reset the timeout to start ticking again at 10 seconds
1111\& ev_timer_again (&mytimer);
1112.Ve
687.ie n .Sh """ev_periodic"" \- to cron or not to cron" 1113.ie n .Sh """ev_periodic"" \- to cron or not to cron?"
688.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron" 1114.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?"
689.IX Subsection "ev_periodic - to cron or not to cron" 1115.IX Subsection "ev_periodic - to cron or not to cron?"
690Periodic watchers are also timers of a kind, but they are very versatile 1116Periodic watchers are also timers of a kind, but they are very versatile
691(and unfortunately a bit complex). 1117(and unfortunately a bit complex).
692.PP 1118.PP
693Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) 1119Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time)
694but on wallclock time (absolute time). You can tell a periodic watcher 1120but on wallclock time (absolute time). You can tell a periodic watcher
695to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a 1121to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a
696periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () 1122periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now ()
697+ 10.>) and then reset your system clock to the last year, then it will 1123+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will
698take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger 1124take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger
699roughly 10 seconds later and of course not if you reset your system time 1125roughly 10 seconds later and of course not if you reset your system time
700again). 1126again).
701.PP 1127.PP
702They can also be used to implement vastly more complex timers, such as 1128They can also be used to implement vastly more complex timers, such as
… …
783.IX Item "ev_periodic_again (loop, ev_periodic *)" 1209.IX Item "ev_periodic_again (loop, ev_periodic *)"
784Simply stops and restarts the periodic watcher again. This is only useful 1210Simply stops and restarts the periodic watcher again. This is only useful
785when you changed some parameters or the reschedule callback would return 1211when you changed some parameters or the reschedule callback would return
786a different time than the last time it was called (e.g. in a crond like 1212a different time than the last time it was called (e.g. in a crond like
787program when the crontabs have changed). 1213program when the crontabs have changed).
1214.IP "ev_tstamp interval [read\-write]" 4
1215.IX Item "ev_tstamp interval [read-write]"
1216The current interval value. Can be modified any time, but changes only
1217take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being
1218called.
1219.IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4
1220.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]"
1221The current reschedule callback, or \f(CW0\fR, if this functionality is
1222switched off. Can be changed any time, but changes only take effect when
1223the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1224.PP
1225Example: Call a callback every hour, or, more precisely, whenever the
1226system clock is divisible by 3600. The callback invocation times have
1227potentially a lot of jittering, but good long-term stability.
1228.PP
1229.Vb 5
1230\& static void
1231\& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1232\& {
1233\& ... its now a full hour (UTC, or TAI or whatever your clock follows)
1234\& }
1235.Ve
1236.PP
1237.Vb 3
1238\& struct ev_periodic hourly_tick;
1239\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1240\& ev_periodic_start (loop, &hourly_tick);
1241.Ve
1242.PP
1243Example: The same as above, but use a reschedule callback to do it:
1244.PP
1245.Vb 1
1246\& #include <math.h>
1247.Ve
1248.PP
1249.Vb 5
1250\& static ev_tstamp
1251\& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1252\& {
1253\& return fmod (now, 3600.) + 3600.;
1254\& }
1255.Ve
1256.PP
1257.Vb 1
1258\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1259.Ve
1260.PP
1261Example: Call a callback every hour, starting now:
1262.PP
1263.Vb 4
1264\& struct ev_periodic hourly_tick;
1265\& ev_periodic_init (&hourly_tick, clock_cb,
1266\& fmod (ev_now (loop), 3600.), 3600., 0);
1267\& ev_periodic_start (loop, &hourly_tick);
1268.Ve
788.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled" 1269.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!"
789.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled" 1270.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!"
790.IX Subsection "ev_signal - signal me when a signal gets signalled" 1271.IX Subsection "ev_signal - signal me when a signal gets signalled!"
791Signal watchers will trigger an event when the process receives a specific 1272Signal watchers will trigger an event when the process receives a specific
792signal one or more times. Even though signals are very asynchronous, libev 1273signal one or more times. Even though signals are very asynchronous, libev
793will try it's best to deliver signals synchronously, i.e. as part of the 1274will try it's best to deliver signals synchronously, i.e. as part of the
794normal event processing, like any other event. 1275normal event processing, like any other event.
795.PP 1276.PP
… …
805.IP "ev_signal_set (ev_signal *, int signum)" 4 1286.IP "ev_signal_set (ev_signal *, int signum)" 4
806.IX Item "ev_signal_set (ev_signal *, int signum)" 1287.IX Item "ev_signal_set (ev_signal *, int signum)"
807.PD 1288.PD
808Configures the watcher to trigger on the given signal number (usually one 1289Configures the watcher to trigger on the given signal number (usually one
809of the \f(CW\*(C`SIGxxx\*(C'\fR constants). 1290of the \f(CW\*(C`SIGxxx\*(C'\fR constants).
1291.IP "int signum [read\-only]" 4
1292.IX Item "int signum [read-only]"
1293The signal the watcher watches out for.
810.ie n .Sh """ev_child"" \- wait for pid status changes" 1294.ie n .Sh """ev_child"" \- watch out for process status changes"
811.el .Sh "\f(CWev_child\fP \- wait for pid status changes" 1295.el .Sh "\f(CWev_child\fP \- watch out for process status changes"
812.IX Subsection "ev_child - wait for pid status changes" 1296.IX Subsection "ev_child - watch out for process status changes"
813Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to 1297Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to
814some child status changes (most typically when a child of yours dies). 1298some child status changes (most typically when a child of yours dies).
815.IP "ev_child_init (ev_child *, callback, int pid)" 4 1299.IP "ev_child_init (ev_child *, callback, int pid)" 4
816.IX Item "ev_child_init (ev_child *, callback, int pid)" 1300.IX Item "ev_child_init (ev_child *, callback, int pid)"
817.PD 0 1301.PD 0
… …
822\&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look 1306\&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look
823at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see 1307at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see
824the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems 1308the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems
825\&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the 1309\&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the
826process causing the status change. 1310process causing the status change.
1311.IP "int pid [read\-only]" 4
1312.IX Item "int pid [read-only]"
1313The process id this watcher watches out for, or \f(CW0\fR, meaning any process id.
1314.IP "int rpid [read\-write]" 4
1315.IX Item "int rpid [read-write]"
1316The process id that detected a status change.
1317.IP "int rstatus [read\-write]" 4
1318.IX Item "int rstatus [read-write]"
1319The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems
1320\&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details).
1321.PP
1322Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.
1323.PP
1324.Vb 5
1325\& static void
1326\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1327\& {
1328\& ev_unloop (loop, EVUNLOOP_ALL);
1329\& }
1330.Ve
1331.PP
1332.Vb 3
1333\& struct ev_signal signal_watcher;
1334\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1335\& ev_signal_start (loop, &sigint_cb);
1336.Ve
1337.ie n .Sh """ev_stat"" \- did the file attributes just change?"
1338.el .Sh "\f(CWev_stat\fP \- did the file attributes just change?"
1339.IX Subsection "ev_stat - did the file attributes just change?"
1340This watches a filesystem path for attribute changes. That is, it calls
1341\&\f(CW\*(C`stat\*(C'\fR regularly (or when the \s-1OS\s0 says it changed) and sees if it changed
1342compared to the last time, invoking the callback if it did.
1343.PP
1344The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does
1345not exist\*(R" is a status change like any other. The condition \*(L"path does
1346not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is
1347otherwise always forced to be at least one) and all the other fields of
1348the stat buffer having unspecified contents.
1349.PP
1350Since there is no standard to do this, the portable implementation simply
1351calls \f(CW\*(C`stat (2)\*(C'\fR regulalry on the path to see if it changed somehow. You
1352can specify a recommended polling interval for this case. If you specify
1353a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable,
1354unspecified default\fR value will be used (which you can expect to be around
1355five seconds, although this might change dynamically). Libev will also
1356impose a minimum interval which is currently around \f(CW0.1\fR, but thats
1357usually overkill.
1358.PP
1359This watcher type is not meant for massive numbers of stat watchers,
1360as even with OS-supported change notifications, this can be
1361resource\-intensive.
1362.PP
1363At the time of this writing, no specific \s-1OS\s0 backends are implemented, but
1364if demand increases, at least a kqueue and inotify backend will be added.
1365.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
1366.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
1367.PD 0
1368.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4
1369.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
1370.PD
1371Configures the watcher to wait for status changes of the given
1372\&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to
1373be detected and should normally be specified as \f(CW0\fR to let libev choose
1374a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same
1375path for as long as the watcher is active.
1376.Sp
1377The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected,
1378relative to the attributes at the time the watcher was started (or the
1379last change was detected).
1380.IP "ev_stat_stat (ev_stat *)" 4
1381.IX Item "ev_stat_stat (ev_stat *)"
1382Updates the stat buffer immediately with new values. If you change the
1383watched path in your callback, you could call this fucntion to avoid
1384detecting this change (while introducing a race condition). Can also be
1385useful simply to find out the new values.
1386.IP "ev_statdata attr [read\-only]" 4
1387.IX Item "ev_statdata attr [read-only]"
1388The most-recently detected attributes of the file. Although the type is of
1389\&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types
1390suitable for your system. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there
1391was some error while \f(CW\*(C`stat\*(C'\fRing the file.
1392.IP "ev_statdata prev [read\-only]" 4
1393.IX Item "ev_statdata prev [read-only]"
1394The previous attributes of the file. The callback gets invoked whenever
1395\&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR.
1396.IP "ev_tstamp interval [read\-only]" 4
1397.IX Item "ev_tstamp interval [read-only]"
1398The specified interval.
1399.IP "const char *path [read\-only]" 4
1400.IX Item "const char *path [read-only]"
1401The filesystem path that is being watched.
1402.PP
1403Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes.
1404.PP
1405.Vb 15
1406\& static void
1407\& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1408\& {
1409\& /* /etc/passwd changed in some way */
1410\& if (w->attr.st_nlink)
1411\& {
1412\& printf ("passwd current size %ld\en", (long)w->attr.st_size);
1413\& printf ("passwd current atime %ld\en", (long)w->attr.st_mtime);
1414\& printf ("passwd current mtime %ld\en", (long)w->attr.st_mtime);
1415\& }
1416\& else
1417\& /* you shalt not abuse printf for puts */
1418\& puts ("wow, /etc/passwd is not there, expect problems. "
1419\& "if this is windows, they already arrived\en");
1420\& }
1421.Ve
1422.PP
1423.Vb 2
1424\& ...
1425\& ev_stat passwd;
1426.Ve
1427.PP
1428.Vb 2
1429\& ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
1430\& ev_stat_start (loop, &passwd);
1431.Ve
827.ie n .Sh """ev_idle"" \- when you've got nothing better to do" 1432.ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
828.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do" 1433.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
829.IX Subsection "ev_idle - when you've got nothing better to do" 1434.IX Subsection "ev_idle - when you've got nothing better to do..."
830Idle watchers trigger events when there are no other events are pending 1435Idle watchers trigger events when there are no other events are pending
831(prepare, check and other idle watchers do not count). That is, as long 1436(prepare, check and other idle watchers do not count). That is, as long
832as your process is busy handling sockets or timeouts (or even signals, 1437as your process is busy handling sockets or timeouts (or even signals,
833imagine) it will not be triggered. But when your process is idle all idle 1438imagine) it will not be triggered. But when your process is idle all idle
834watchers are being called again and again, once per event loop iteration \- 1439watchers are being called again and again, once per event loop iteration \-
… …
845.IP "ev_idle_init (ev_signal *, callback)" 4 1450.IP "ev_idle_init (ev_signal *, callback)" 4
846.IX Item "ev_idle_init (ev_signal *, callback)" 1451.IX Item "ev_idle_init (ev_signal *, callback)"
847Initialises and configures the idle watcher \- it has no parameters of any 1452Initialises and configures the idle watcher \- it has no parameters of any
848kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, 1453kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,
849believe me. 1454believe me.
1455.PP
1456Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the
1457callback, free it. Also, use no error checking, as usual.
1458.PP
1459.Vb 7
1460\& static void
1461\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1462\& {
1463\& free (w);
1464\& // now do something you wanted to do when the program has
1465\& // no longer asnything immediate to do.
1466\& }
1467.Ve
1468.PP
1469.Vb 3
1470\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1471\& ev_idle_init (idle_watcher, idle_cb);
1472\& ev_idle_start (loop, idle_cb);
1473.Ve
850.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop" 1474.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!"
851.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop" 1475.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!"
852.IX Subsection "ev_prepare and ev_check - customise your event loop" 1476.IX Subsection "ev_prepare and ev_check - customise your event loop!"
853Prepare and check watchers are usually (but not always) used in tandem: 1477Prepare and check watchers are usually (but not always) used in tandem:
854prepare watchers get invoked before the process blocks and check watchers 1478prepare watchers get invoked before the process blocks and check watchers
855afterwards. 1479afterwards.
856.PP 1480.PP
1481You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter
1482the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR
1483watchers. Other loops than the current one are fine, however. The
1484rationale behind this is that you do not need to check for recursion in
1485those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking,
1486\&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be
1487called in pairs bracketing the blocking call.
1488.PP
857Their main purpose is to integrate other event mechanisms into libev. This 1489Their main purpose is to integrate other event mechanisms into libev and
858could be used, for example, to track variable changes, implement your own 1490their use is somewhat advanced. This could be used, for example, to track
859watchers, integrate net-snmp or a coroutine library and lots more. 1491variable changes, implement your own watchers, integrate net-snmp or a
1492coroutine library and lots more. They are also occasionally useful if
1493you cache some data and want to flush it before blocking (for example,
1494in X programs you might want to do an \f(CW\*(C`XFlush ()\*(C'\fR in an \f(CW\*(C`ev_prepare\*(C'\fR
1495watcher).
860.PP 1496.PP
861This is done by examining in each prepare call which file descriptors need 1497This is done by examining in each prepare call which file descriptors need
862to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for 1498to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for
863them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries 1499them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries
864provide just this functionality). Then, in the check watcher you check for 1500provide just this functionality). Then, in the check watcher you check for
… …
882.IX Item "ev_check_init (ev_check *, callback)" 1518.IX Item "ev_check_init (ev_check *, callback)"
883.PD 1519.PD
884Initialises and configures the prepare or check watcher \- they have no 1520Initialises and configures the prepare or check watcher \- they have no
885parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR 1521parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR
886macros, but using them is utterly, utterly and completely pointless. 1522macros, but using them is utterly, utterly and completely pointless.
1523.PP
1524Example: To include a library such as adns, you would add \s-1IO\s0 watchers
1525and a timeout watcher in a prepare handler, as required by libadns, and
1526in a check watcher, destroy them and call into libadns. What follows is
1527pseudo-code only of course:
1528.PP
1529.Vb 2
1530\& static ev_io iow [nfd];
1531\& static ev_timer tw;
1532.Ve
1533.PP
1534.Vb 9
1535\& static void
1536\& io_cb (ev_loop *loop, ev_io *w, int revents)
1537\& {
1538\& // set the relevant poll flags
1539\& // could also call adns_processreadable etc. here
1540\& struct pollfd *fd = (struct pollfd *)w->data;
1541\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1542\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1543\& }
1544.Ve
1545.PP
1546.Vb 7
1547\& // create io watchers for each fd and a timer before blocking
1548\& static void
1549\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1550\& {
1551\& int timeout = 3600000;truct pollfd fds [nfd];
1552\& // actual code will need to loop here and realloc etc.
1553\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1554.Ve
1555.PP
1556.Vb 3
1557\& /* the callback is illegal, but won't be called as we stop during check */
1558\& ev_timer_init (&tw, 0, timeout * 1e-3);
1559\& ev_timer_start (loop, &tw);
1560.Ve
1561.PP
1562.Vb 6
1563\& // create on ev_io per pollfd
1564\& for (int i = 0; i < nfd; ++i)
1565\& {
1566\& ev_io_init (iow + i, io_cb, fds [i].fd,
1567\& ((fds [i].events & POLLIN ? EV_READ : 0)
1568\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1569.Ve
1570.PP
1571.Vb 5
1572\& fds [i].revents = 0;
1573\& iow [i].data = fds + i;
1574\& ev_io_start (loop, iow + i);
1575\& }
1576\& }
1577.Ve
1578.PP
1579.Vb 5
1580\& // stop all watchers after blocking
1581\& static void
1582\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1583\& {
1584\& ev_timer_stop (loop, &tw);
1585.Ve
1586.PP
1587.Vb 2
1588\& for (int i = 0; i < nfd; ++i)
1589\& ev_io_stop (loop, iow + i);
1590.Ve
1591.PP
1592.Vb 2
1593\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1594\& }
1595.Ve
1596.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1597.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
1598.IX Subsection "ev_embed - when one backend isn't enough..."
1599This is a rather advanced watcher type that lets you embed one event loop
1600into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded
1601loop, other types of watchers might be handled in a delayed or incorrect
1602fashion and must not be used).
1603.PP
1604There are primarily two reasons you would want that: work around bugs and
1605prioritise I/O.
1606.PP
1607As an example for a bug workaround, the kqueue backend might only support
1608sockets on some platform, so it is unusable as generic backend, but you
1609still want to make use of it because you have many sockets and it scales
1610so nicely. In this case, you would create a kqueue-based loop and embed it
1611into your default loop (which might use e.g. poll). Overall operation will
1612be a bit slower because first libev has to poll and then call kevent, but
1613at least you can use both at what they are best.
1614.PP
1615As for prioritising I/O: rarely you have the case where some fds have
1616to be watched and handled very quickly (with low latency), and even
1617priorities and idle watchers might have too much overhead. In this case
1618you would put all the high priority stuff in one loop and all the rest in
1619a second one, and embed the second one in the first.
1620.PP
1621As long as the watcher is active, the callback will be invoked every time
1622there might be events pending in the embedded loop. The callback must then
1623call \f(CW\*(C`ev_embed_sweep (mainloop, watcher)\*(C'\fR to make a single sweep and invoke
1624their callbacks (you could also start an idle watcher to give the embedded
1625loop strictly lower priority for example). You can also set the callback
1626to \f(CW0\fR, in which case the embed watcher will automatically execute the
1627embedded loop sweep.
1628.PP
1629As long as the watcher is started it will automatically handle events. The
1630callback will be invoked whenever some events have been handled. You can
1631set the callback to \f(CW0\fR to avoid having to specify one if you are not
1632interested in that.
1633.PP
1634Also, there have not currently been made special provisions for forking:
1635when you fork, you not only have to call \f(CW\*(C`ev_loop_fork\*(C'\fR on both loops,
1636but you will also have to stop and restart any \f(CW\*(C`ev_embed\*(C'\fR watchers
1637yourself.
1638.PP
1639Unfortunately, not all backends are embeddable, only the ones returned by
1640\&\f(CW\*(C`ev_embeddable_backends\*(C'\fR are, which, unfortunately, does not include any
1641portable one.
1642.PP
1643So when you want to use this feature you will always have to be prepared
1644that you cannot get an embeddable loop. The recommended way to get around
1645this is to have a separate variables for your embeddable loop, try to
1646create it, and if that fails, use the normal loop for everything:
1647.PP
1648.Vb 3
1649\& struct ev_loop *loop_hi = ev_default_init (0);
1650\& struct ev_loop *loop_lo = 0;
1651\& struct ev_embed embed;
1652.Ve
1653.PP
1654.Vb 5
1655\& // see if there is a chance of getting one that works
1656\& // (remember that a flags value of 0 means autodetection)
1657\& loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
1658\& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
1659\& : 0;
1660.Ve
1661.PP
1662.Vb 8
1663\& // if we got one, then embed it, otherwise default to loop_hi
1664\& if (loop_lo)
1665\& {
1666\& ev_embed_init (&embed, 0, loop_lo);
1667\& ev_embed_start (loop_hi, &embed);
1668\& }
1669\& else
1670\& loop_lo = loop_hi;
1671.Ve
1672.IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
1673.IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)"
1674.PD 0
1675.IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
1676.IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)"
1677.PD
1678Configures the watcher to embed the given loop, which must be
1679embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be
1680invoked automatically, otherwise it is the responsibility of the callback
1681to invoke it (it will continue to be called until the sweep has been done,
1682if you do not want thta, you need to temporarily stop the embed watcher).
1683.IP "ev_embed_sweep (loop, ev_embed *)" 4
1684.IX Item "ev_embed_sweep (loop, ev_embed *)"
1685Make a single, non-blocking sweep over the embedded loop. This works
1686similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most
1687apropriate way for embedded loops.
1688.IP "struct ev_loop *loop [read\-only]" 4
1689.IX Item "struct ev_loop *loop [read-only]"
1690The embedded event loop.
1691.ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork"
1692.el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork"
1693.IX Subsection "ev_fork - the audacity to resume the event loop after a fork"
1694Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because
1695whoever is a good citizen cared to tell libev about it by calling
1696\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the
1697event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called,
1698and only in the child after the fork. If whoever good citizen calling
1699\&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork
1700handlers will be invoked, too, of course.
1701.IP "ev_fork_init (ev_signal *, callback)" 4
1702.IX Item "ev_fork_init (ev_signal *, callback)"
1703Initialises and configures the fork watcher \- it has no parameters of any
1704kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless,
1705believe me.
887.SH "OTHER FUNCTIONS" 1706.SH "OTHER FUNCTIONS"
888.IX Header "OTHER FUNCTIONS" 1707.IX Header "OTHER FUNCTIONS"
889There are some other functions of possible interest. Described. Here. Now. 1708There are some other functions of possible interest. Described. Here. Now.
890.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 1709.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4
891.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 1710.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)"
… …
920.Ve 1739.Ve
921.Sp 1740.Sp
922.Vb 1 1741.Vb 1
923\& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); 1742\& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
924.Ve 1743.Ve
925.IP "ev_feed_event (loop, watcher, int events)" 4 1744.IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4
926.IX Item "ev_feed_event (loop, watcher, int events)" 1745.IX Item "ev_feed_event (ev_loop *, watcher *, int revents)"
927Feeds the given event set into the event loop, as if the specified event 1746Feeds the given event set into the event loop, as if the specified event
928had happened for the specified watcher (which must be a pointer to an 1747had happened for the specified watcher (which must be a pointer to an
929initialised but not necessarily started event watcher). 1748initialised but not necessarily started event watcher).
930.IP "ev_feed_fd_event (loop, int fd, int revents)" 4 1749.IP "ev_feed_fd_event (ev_loop *, int fd, int revents)" 4
931.IX Item "ev_feed_fd_event (loop, int fd, int revents)" 1750.IX Item "ev_feed_fd_event (ev_loop *, int fd, int revents)"
932Feed an event on the given fd, as if a file descriptor backend detected 1751Feed an event on the given fd, as if a file descriptor backend detected
933the given events it. 1752the given events it.
934.IP "ev_feed_signal_event (loop, int signum)" 4 1753.IP "ev_feed_signal_event (ev_loop *loop, int signum)" 4
935.IX Item "ev_feed_signal_event (loop, int signum)" 1754.IX Item "ev_feed_signal_event (ev_loop *loop, int signum)"
936Feed an event as if the given signal occured (loop must be the default loop!). 1755Feed an event as if the given signal occured (\f(CW\*(C`loop\*(C'\fR must be the default
1756loop!).
937.SH "LIBEVENT EMULATION" 1757.SH "LIBEVENT EMULATION"
938.IX Header "LIBEVENT EMULATION" 1758.IX Header "LIBEVENT EMULATION"
939Libev offers a compatibility emulation layer for libevent. It cannot 1759Libev offers a compatibility emulation layer for libevent. It cannot
940emulate the internals of libevent, so here are some usage hints: 1760emulate the internals of libevent, so here are some usage hints:
941.IP "* Use it by including <event.h>, as usual." 4 1761.IP "* Use it by including <event.h>, as usual." 4
… …
952.IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4 1772.IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4
953.IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library." 1773.IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library."
954.PD 1774.PD
955.SH "\*(C+ SUPPORT" 1775.SH "\*(C+ SUPPORT"
956.IX Header " SUPPORT" 1776.IX Header " SUPPORT"
957\&\s-1TBD\s0. 1777Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow
1778you to use some convinience methods to start/stop watchers and also change
1779the callback model to a model using method callbacks on objects.
1780.PP
1781To use it,
1782.PP
1783.Vb 1
1784\& #include <ev++.h>
1785.Ve
1786.PP
1787(it is not installed by default). This automatically includes \fIev.h\fR
1788and puts all of its definitions (many of them macros) into the global
1789namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace.
1790.PP
1791It should support all the same embedding options as \fIev.h\fR, most notably
1792\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
1793.PP
1794Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
1795.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
1796.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
1797.IX Item "ev::READ, ev::WRITE etc."
1798These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc.
1799macros from \fIev.h\fR.
1800.ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4
1801.el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4
1802.IX Item "ev::tstamp, ev::now"
1803Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix.
1804.ie n .IP """ev::io""\fR, \f(CW""ev::timer""\fR, \f(CW""ev::periodic""\fR, \f(CW""ev::idle""\fR, \f(CW""ev::sig"" etc." 4
1805.el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4
1806.IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc."
1807For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of
1808the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR
1809which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
1810defines by many implementations.
1811.Sp
1812All of those classes have these methods:
1813.RS 4
1814.IP "ev::TYPE::TYPE (object *, object::method *)" 4
1815.IX Item "ev::TYPE::TYPE (object *, object::method *)"
1816.PD 0
1817.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4
1818.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)"
1819.IP "ev::TYPE::~TYPE" 4
1820.IX Item "ev::TYPE::~TYPE"
1821.PD
1822The constructor takes a pointer to an object and a method pointer to
1823the event handler callback to call in this class. The constructor calls
1824\&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method
1825before starting it. If you do not specify a loop then the constructor
1826automatically associates the default loop with this watcher.
1827.Sp
1828The destructor automatically stops the watcher if it is active.
1829.IP "w\->set (struct ev_loop *)" 4
1830.IX Item "w->set (struct ev_loop *)"
1831Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
1832do this when the watcher is inactive (and not pending either).
1833.IP "w\->set ([args])" 4
1834.IX Item "w->set ([args])"
1835Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be
1836called at least once. Unlike the C counterpart, an active watcher gets
1837automatically stopped and restarted.
1838.IP "w\->start ()" 4
1839.IX Item "w->start ()"
1840Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the
1841constructor already takes the loop.
1842.IP "w\->stop ()" 4
1843.IX Item "w->stop ()"
1844Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
1845.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4
1846.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4
1847.IX Item "w->again () ev::timer, ev::periodic only"
1848For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding
1849\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function.
1850.ie n .IP "w\->sweep () ""ev::embed"" only" 4
1851.el .IP "w\->sweep () \f(CWev::embed\fR only" 4
1852.IX Item "w->sweep () ev::embed only"
1853Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR.
1854.ie n .IP "w\->update () ""ev::stat"" only" 4
1855.el .IP "w\->update () \f(CWev::stat\fR only" 4
1856.IX Item "w->update () ev::stat only"
1857Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR.
1858.RE
1859.RS 4
1860.RE
1861.PP
1862Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in
1863the constructor.
1864.PP
1865.Vb 4
1866\& class myclass
1867\& {
1868\& ev_io io; void io_cb (ev::io &w, int revents);
1869\& ev_idle idle void idle_cb (ev::idle &w, int revents);
1870.Ve
1871.PP
1872.Vb 2
1873\& myclass ();
1874\& }
1875.Ve
1876.PP
1877.Vb 6
1878\& myclass::myclass (int fd)
1879\& : io (this, &myclass::io_cb),
1880\& idle (this, &myclass::idle_cb)
1881\& {
1882\& io.start (fd, ev::READ);
1883\& }
1884.Ve
1885.SH "MACRO MAGIC"
1886.IX Header "MACRO MAGIC"
1887Libev can be compiled with a variety of options, the most fundemantal is
1888\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines wether (most) functions and
1889callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
1890.PP
1891To make it easier to write programs that cope with either variant, the
1892following macros are defined:
1893.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
1894.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4
1895.IX Item "EV_A, EV_A_"
1896This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev
1897loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument,
1898\&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example:
1899.Sp
1900.Vb 3
1901\& ev_unref (EV_A);
1902\& ev_timer_add (EV_A_ watcher);
1903\& ev_loop (EV_A_ 0);
1904.Ve
1905.Sp
1906It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope,
1907which is often provided by the following macro.
1908.ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4
1909.el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4
1910.IX Item "EV_P, EV_P_"
1911This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev
1912loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter,
1913\&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example:
1914.Sp
1915.Vb 2
1916\& // this is how ev_unref is being declared
1917\& static void ev_unref (EV_P);
1918.Ve
1919.Sp
1920.Vb 2
1921\& // this is how you can declare your typical callback
1922\& static void cb (EV_P_ ev_timer *w, int revents)
1923.Ve
1924.Sp
1925It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite
1926suitable for use with \f(CW\*(C`EV_A\*(C'\fR.
1927.ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4
1928.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
1929.IX Item "EV_DEFAULT, EV_DEFAULT_"
1930Similar to the other two macros, this gives you the value of the default
1931loop, if multiple loops are supported (\*(L"ev loop default\*(R").
1932.PP
1933Example: Declare and initialise a check watcher, working regardless of
1934wether multiple loops are supported or not.
1935.PP
1936.Vb 5
1937\& static void
1938\& check_cb (EV_P_ ev_timer *w, int revents)
1939\& {
1940\& ev_check_stop (EV_A_ w);
1941\& }
1942.Ve
1943.PP
1944.Vb 4
1945\& ev_check check;
1946\& ev_check_init (&check, check_cb);
1947\& ev_check_start (EV_DEFAULT_ &check);
1948\& ev_loop (EV_DEFAULT_ 0);
1949.Ve
1950.SH "EMBEDDING"
1951.IX Header "EMBEDDING"
1952Libev can (and often is) directly embedded into host
1953applications. Examples of applications that embed it include the Deliantra
1954Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe)
1955and rxvt\-unicode.
1956.PP
1957The goal is to enable you to just copy the neecssary files into your
1958source directory without having to change even a single line in them, so
1959you can easily upgrade by simply copying (or having a checked-out copy of
1960libev somewhere in your source tree).
1961.Sh "\s-1FILESETS\s0"
1962.IX Subsection "FILESETS"
1963Depending on what features you need you need to include one or more sets of files
1964in your app.
1965.PP
1966\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR
1967.IX Subsection "CORE EVENT LOOP"
1968.PP
1969To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual
1970configuration (no autoconf):
1971.PP
1972.Vb 2
1973\& #define EV_STANDALONE 1
1974\& #include "ev.c"
1975.Ve
1976.PP
1977This will automatically include \fIev.h\fR, too, and should be done in a
1978single C source file only to provide the function implementations. To use
1979it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best
1980done by writing a wrapper around \fIev.h\fR that you can include instead and
1981where you can put other configuration options):
1982.PP
1983.Vb 2
1984\& #define EV_STANDALONE 1
1985\& #include "ev.h"
1986.Ve
1987.PP
1988Both header files and implementation files can be compiled with a \*(C+
1989compiler (at least, thats a stated goal, and breakage will be treated
1990as a bug).
1991.PP
1992You need the following files in your source tree, or in a directory
1993in your include path (e.g. in libev/ when using \-Ilibev):
1994.PP
1995.Vb 4
1996\& ev.h
1997\& ev.c
1998\& ev_vars.h
1999\& ev_wrap.h
2000.Ve
2001.PP
2002.Vb 1
2003\& ev_win32.c required on win32 platforms only
2004.Ve
2005.PP
2006.Vb 5
2007\& ev_select.c only when select backend is enabled (which is by default)
2008\& ev_poll.c only when poll backend is enabled (disabled by default)
2009\& ev_epoll.c only when the epoll backend is enabled (disabled by default)
2010\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2011\& ev_port.c only when the solaris port backend is enabled (disabled by default)
2012.Ve
2013.PP
2014\&\fIev.c\fR includes the backend files directly when enabled, so you only need
2015to compile this single file.
2016.PP
2017\fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR
2018.IX Subsection "LIBEVENT COMPATIBILITY API"
2019.PP
2020To include the libevent compatibility \s-1API\s0, also include:
2021.PP
2022.Vb 1
2023\& #include "event.c"
2024.Ve
2025.PP
2026in the file including \fIev.c\fR, and:
2027.PP
2028.Vb 1
2029\& #include "event.h"
2030.Ve
2031.PP
2032in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR.
2033.PP
2034You need the following additional files for this:
2035.PP
2036.Vb 2
2037\& event.h
2038\& event.c
2039.Ve
2040.PP
2041\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR
2042.IX Subsection "AUTOCONF SUPPORT"
2043.PP
2044Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in
2045whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your
2046\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then
2047include \fIconfig.h\fR and configure itself accordingly.
2048.PP
2049For this of course you need the m4 file:
2050.PP
2051.Vb 1
2052\& libev.m4
2053.Ve
2054.Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0"
2055.IX Subsection "PREPROCESSOR SYMBOLS/MACROS"
2056Libev can be configured via a variety of preprocessor symbols you have to define
2057before including any of its files. The default is not to build for multiplicity
2058and only include the select backend.
2059.IP "\s-1EV_STANDALONE\s0" 4
2060.IX Item "EV_STANDALONE"
2061Must always be \f(CW1\fR if you do not use autoconf configuration, which
2062keeps libev from including \fIconfig.h\fR, and it also defines dummy
2063implementations for some libevent functions (such as logging, which is not
2064supported). It will also not define any of the structs usually found in
2065\&\fIevent.h\fR that are not directly supported by the libev core alone.
2066.IP "\s-1EV_USE_MONOTONIC\s0" 4
2067.IX Item "EV_USE_MONOTONIC"
2068If defined to be \f(CW1\fR, libev will try to detect the availability of the
2069monotonic clock option at both compiletime and runtime. Otherwise no use
2070of the monotonic clock option will be attempted. If you enable this, you
2071usually have to link against librt or something similar. Enabling it when
2072the functionality isn't available is safe, though, althoguh you have
2073to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR
2074function is hiding in (often \fI\-lrt\fR).
2075.IP "\s-1EV_USE_REALTIME\s0" 4
2076.IX Item "EV_USE_REALTIME"
2077If defined to be \f(CW1\fR, libev will try to detect the availability of the
2078realtime clock option at compiletime (and assume its availability at
2079runtime if successful). Otherwise no use of the realtime clock option will
2080be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get
2081(CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See tzhe note about libraries
2082in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though.
2083.IP "\s-1EV_USE_SELECT\s0" 4
2084.IX Item "EV_USE_SELECT"
2085If undefined or defined to be \f(CW1\fR, libev will compile in support for the
2086\&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no
2087other method takes over, select will be it. Otherwise the select backend
2088will not be compiled in.
2089.IP "\s-1EV_SELECT_USE_FD_SET\s0" 4
2090.IX Item "EV_SELECT_USE_FD_SET"
2091If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR
2092structure. This is useful if libev doesn't compile due to a missing
2093\&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it misguesses the bitset layout on
2094exotic systems. This usually limits the range of file descriptors to some
2095low limit such as 1024 or might have other limitations (winsocket only
2096allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might
2097influence the size of the \f(CW\*(C`fd_set\*(C'\fR used.
2098.IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4
2099.IX Item "EV_SELECT_IS_WINSOCKET"
2100When defined to \f(CW1\fR, the select backend will assume that
2101select/socket/connect etc. don't understand file descriptors but
2102wants osf handles on win32 (this is the case when the select to
2103be used is the winsock select). This means that it will call
2104\&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise,
2105it is assumed that all these functions actually work on fds, even
2106on win32. Should not be defined on non\-win32 platforms.
2107.IP "\s-1EV_USE_POLL\s0" 4
2108.IX Item "EV_USE_POLL"
2109If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2)
2110backend. Otherwise it will be enabled on non\-win32 platforms. It
2111takes precedence over select.
2112.IP "\s-1EV_USE_EPOLL\s0" 4
2113.IX Item "EV_USE_EPOLL"
2114If defined to be \f(CW1\fR, libev will compile in support for the Linux
2115\&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime,
2116otherwise another method will be used as fallback. This is the
2117preferred backend for GNU/Linux systems.
2118.IP "\s-1EV_USE_KQUEUE\s0" 4
2119.IX Item "EV_USE_KQUEUE"
2120If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style
2121\&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime,
2122otherwise another method will be used as fallback. This is the preferred
2123backend for \s-1BSD\s0 and BSD-like systems, although on most BSDs kqueue only
2124supports some types of fds correctly (the only platform we found that
2125supports ptys for example was NetBSD), so kqueue might be compiled in, but
2126not be used unless explicitly requested. The best way to use it is to find
2127out whether kqueue supports your type of fd properly and use an embedded
2128kqueue loop.
2129.IP "\s-1EV_USE_PORT\s0" 4
2130.IX Item "EV_USE_PORT"
2131If defined to be \f(CW1\fR, libev will compile in support for the Solaris
213210 port style backend. Its availability will be detected at runtime,
2133otherwise another method will be used as fallback. This is the preferred
2134backend for Solaris 10 systems.
2135.IP "\s-1EV_USE_DEVPOLL\s0" 4
2136.IX Item "EV_USE_DEVPOLL"
2137reserved for future expansion, works like the \s-1USE\s0 symbols above.
2138.IP "\s-1EV_H\s0" 4
2139.IX Item "EV_H"
2140The name of the \fIev.h\fR header file used to include it. The default if
2141undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This
2142can be used to virtually rename the \fIev.h\fR header file in case of conflicts.
2143.IP "\s-1EV_CONFIG_H\s0" 4
2144.IX Item "EV_CONFIG_H"
2145If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override
2146\&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to
2147\&\f(CW\*(C`EV_H\*(C'\fR, above.
2148.IP "\s-1EV_EVENT_H\s0" 4
2149.IX Item "EV_EVENT_H"
2150Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea
2151of how the \fIevent.h\fR header can be found.
2152.IP "\s-1EV_PROTOTYPES\s0" 4
2153.IX Item "EV_PROTOTYPES"
2154If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function
2155prototypes, but still define all the structs and other symbols. This is
2156occasionally useful if you want to provide your own wrapper functions
2157around libev functions.
2158.IP "\s-1EV_MULTIPLICITY\s0" 4
2159.IX Item "EV_MULTIPLICITY"
2160If undefined or defined to \f(CW1\fR, then all event-loop-specific functions
2161will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create
2162additional independent event loops. Otherwise there will be no support
2163for multiple event loops and there is no first event loop pointer
2164argument. Instead, all functions act on the single default loop.
2165.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
2166.IX Item "EV_PERIODIC_ENABLE"
2167If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
2168defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2169code.
2170.IP "\s-1EV_EMBED_ENABLE\s0" 4
2171.IX Item "EV_EMBED_ENABLE"
2172If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If
2173defined to be \f(CW0\fR, then they are not.
2174.IP "\s-1EV_STAT_ENABLE\s0" 4
2175.IX Item "EV_STAT_ENABLE"
2176If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If
2177defined to be \f(CW0\fR, then they are not.
2178.IP "\s-1EV_FORK_ENABLE\s0" 4
2179.IX Item "EV_FORK_ENABLE"
2180If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If
2181defined to be \f(CW0\fR, then they are not.
2182.IP "\s-1EV_MINIMAL\s0" 4
2183.IX Item "EV_MINIMAL"
2184If you need to shave off some kilobytes of code at the expense of some
2185speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override
2186some inlining decisions, saves roughly 30% codesize of amd64.
2187.IP "\s-1EV_PID_HASHSIZE\s0" 4
2188.IX Item "EV_PID_HASHSIZE"
2189\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by
2190pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more
2191than enough. If you need to manage thousands of children you might want to
2192increase this value.
2193.IP "\s-1EV_COMMON\s0" 4
2194.IX Item "EV_COMMON"
2195By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
2196this macro to a something else you can include more and other types of
2197members. You have to define it each time you include one of the files,
2198though, and it must be identical each time.
2199.Sp
2200For example, the perl \s-1EV\s0 module uses something like this:
2201.Sp
2202.Vb 3
2203\& #define EV_COMMON \e
2204\& SV *self; /* contains this struct */ \e
2205\& SV *cb_sv, *fh /* note no trailing ";" */
2206.Ve
2207.IP "\s-1EV_CB_DECLARE\s0 (type)" 4
2208.IX Item "EV_CB_DECLARE (type)"
2209.PD 0
2210.IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4
2211.IX Item "EV_CB_INVOKE (watcher, revents)"
2212.IP "ev_set_cb (ev, cb)" 4
2213.IX Item "ev_set_cb (ev, cb)"
2214.PD
2215Can be used to change the callback member declaration in each watcher,
2216and the way callbacks are invoked and set. Must expand to a struct member
2217definition and a statement, respectively. See the \fIev.v\fR header file for
2218their default definitions. One possible use for overriding these is to
2219avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
2220method calls instead of plain function calls in \*(C+.
2221.Sh "\s-1EXAMPLES\s0"
2222.IX Subsection "EXAMPLES"
2223For a real-world example of a program the includes libev
2224verbatim, you can have a look at the \s-1EV\s0 perl module
2225(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in
2226the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public
2227interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file
2228will be compiled. It is pretty complex because it provides its own header
2229file.
2230.Sp
2231The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
2232that everybody includes and which overrides some autoconf choices:
2233.Sp
2234.Vb 4
2235\& #define EV_USE_POLL 0
2236\& #define EV_MULTIPLICITY 0
2237\& #define EV_PERIODICS 0
2238\& #define EV_CONFIG_H <config.h>
2239.Ve
2240.Sp
2241.Vb 1
2242\& #include "ev++.h"
2243.Ve
2244.Sp
2245And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled:
2246.Sp
2247.Vb 2
2248\& #include "ev_cpp.h"
2249\& #include "ev.c"
2250.Ve
2251.SH "COMPLEXITIES"
2252.IX Header "COMPLEXITIES"
2253In this section the complexities of (many of) the algorithms used inside
2254libev will be explained. For complexity discussions about backends see the
2255documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
2256.RS 4
2257.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
2258.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
2259.PD 0
2260.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
2261.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2262.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
2263.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2264.IP "Stopping check/prepare/idle watchers: O(1)" 4
2265.IX Item "Stopping check/prepare/idle watchers: O(1)"
2266.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 4
2267.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))"
2268.IP "Finding the next timer per loop iteration: O(1)" 4
2269.IX Item "Finding the next timer per loop iteration: O(1)"
2270.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
2271.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
2272.IP "Activating one watcher: O(1)" 4
2273.IX Item "Activating one watcher: O(1)"
2274.RE
2275.RS 4
2276.PD
958.SH "AUTHOR" 2277.SH "AUTHOR"
959.IX Header "AUTHOR" 2278.IX Header "AUTHOR"
960Marc Lehmann <libev@schmorp.de>. 2279Marc Lehmann <libev@schmorp.de>.

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