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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 "2007-11-22" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH "<STANDARD INPUT>" 1 "2007-11-28" "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), the Linux \f(CW\*(C`inotify\*(C'\fR interface
159events (related to \s-1SIGCHLD\s0), and event watchers dealing with the event 218(for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers
160loop mechanism itself (idle, prepare and check watchers). It also is quite 219with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals
161fast (see this benchmark comparing 220(\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event
162it to libevent for example). 221watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR,
222\&\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
223file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events
224(\f(CW\*(C`ev_fork\*(C'\fR).
225.PP
226It also is quite fast (see this
227benchmark comparing it to libevent
228for example).
163.SH "CONVENTIONS" 229.SH "CONVENTIONS"
164.IX Header "CONVENTIONS" 230.IX Header "CONVENTIONS"
165Libev is very configurable. In this manual the default configuration 231Libev is very configurable. In this manual the default configuration will
166will be described, which supports multiple event loops. For more info 232be described, which supports multiple event loops. For more info about
167about various configuration options please have a look at the file 233various 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 234this manual. If libev was configured without support for multiple event
169support for multiple event loops, then all functions taking an initial 235loops, 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) 236(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" 237.SH "TIME REPRESENTATION"
173.IX Header "TIME REPRESENTATION" 238.IX Header "TIME REPRESENTATION"
174Libev represents time as a single floating point number, representing the 239Libev represents time as a single floating point number, representing the
175(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near 240(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 241the 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 242called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases
178to the double type in C. 243to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on
244it, you should treat it as such.
179.SH "GLOBAL FUNCTIONS" 245.SH "GLOBAL FUNCTIONS"
180.IX Header "GLOBAL FUNCTIONS" 246.IX Header "GLOBAL FUNCTIONS"
181These functions can be called anytime, even before initialising the 247These functions can be called anytime, even before initialising the
182library in any way. 248library in any way.
183.IP "ev_tstamp ev_time ()" 4 249.IP "ev_tstamp ev_time ()" 4
… …
199.Sp 265.Sp
200Usually, it's a good idea to terminate if the major versions mismatch, 266Usually, it's a good idea to terminate if the major versions mismatch,
201as this indicates an incompatible change. Minor versions are usually 267as this indicates an incompatible change. Minor versions are usually
202compatible to older versions, so a larger minor version alone is usually 268compatible to older versions, so a larger minor version alone is usually
203not a problem. 269not a problem.
270.Sp
271Example: Make sure we haven't accidentally been linked against the wrong
272version.
273.Sp
274.Vb 3
275\& assert (("libev version mismatch",
276\& ev_version_major () == EV_VERSION_MAJOR
277\& && ev_version_minor () >= EV_VERSION_MINOR));
278.Ve
279.IP "unsigned int ev_supported_backends ()" 4
280.IX Item "unsigned int ev_supported_backends ()"
281Return the set of all backends (i.e. their corresponding \f(CW\*(C`EV_BACKEND_*\*(C'\fR
282value) compiled into this binary of libev (independent of their
283availability on the system you are running on). See \f(CW\*(C`ev_default_loop\*(C'\fR for
284a description of the set values.
285.Sp
286Example: make sure we have the epoll method, because yeah this is cool and
287a must have and can we have a torrent of it please!!!11
288.Sp
289.Vb 2
290\& assert (("sorry, no epoll, no sex",
291\& ev_supported_backends () & EVBACKEND_EPOLL));
292.Ve
293.IP "unsigned int ev_recommended_backends ()" 4
294.IX Item "unsigned int ev_recommended_backends ()"
295Return the set of all backends compiled into this binary of libev and also
296recommended for this platform. This set is often smaller than the one
297returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on
298most BSDs and will not be autodetected unless you explicitly request it
299(assuming you know what you are doing). This is the set of backends that
300libev will probe for if you specify no backends explicitly.
301.IP "unsigned int ev_embeddable_backends ()" 4
302.IX Item "unsigned int ev_embeddable_backends ()"
303Returns the set of backends that are embeddable in other event loops. This
304is the theoretical, all\-platform, value. To find which backends
305might be supported on the current system, you would need to look at
306\&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for
307recommended ones.
308.Sp
309See 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))" 4 310.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4
205.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" 311.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"
206Sets the allocation function to use (the prototype is similar to the 312Sets the allocation function to use (the prototype is similar \- the
207realloc C function, the semantics are identical). It is used to allocate 313semantics is identical \- to the realloc C function). It is used to
208and free memory (no surprises here). If it returns zero when memory 314allocate and free memory (no surprises here). If it returns zero when
209needs to be allocated, the library might abort or take some potentially 315memory needs to be allocated, the library might abort or take some
210destructive action. The default is your system realloc function. 316potentially destructive action. The default is your system realloc
317function.
211.Sp 318.Sp
212You could override this function in high-availability programs to, say, 319You could override this function in high-availability programs to, say,
213free some memory if it cannot allocate memory, to use a special allocator, 320free 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. 321or even to sleep a while and retry until some memory is available.
322.Sp
323Example: Replace the libev allocator with one that waits a bit and then
324retries).
325.Sp
326.Vb 6
327\& static void *
328\& persistent_realloc (void *ptr, size_t size)
329\& {
330\& for (;;)
331\& {
332\& void *newptr = realloc (ptr, size);
333.Ve
334.Sp
335.Vb 2
336\& if (newptr)
337\& return newptr;
338.Ve
339.Sp
340.Vb 3
341\& sleep (60);
342\& }
343\& }
344.Ve
345.Sp
346.Vb 2
347\& ...
348\& ev_set_allocator (persistent_realloc);
349.Ve
215.IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 350.IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4
216.IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" 351.IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));"
217Set the callback function to call on a retryable syscall error (such 352Set the callback function to call on a retryable syscall error (such
218as failed select, poll, epoll_wait). The message is a printable string 353as failed select, poll, epoll_wait). The message is a printable string
219indicating the system call or subsystem causing the problem. If this 354indicating the system call or subsystem causing the problem. If this
220callback is set, then libev will expect it to remedy the sitution, no 355callback is set, then libev will expect it to remedy the sitution, no
221matter what, when it returns. That is, libev will generally retry the 356matter what, when it returns. That is, libev will generally retry the
222requested operation, or, if the condition doesn't go away, do bad stuff 357requested operation, or, if the condition doesn't go away, do bad stuff
223(such as abort). 358(such as abort).
359.Sp
360Example: This is basically the same thing that libev does internally, too.
361.Sp
362.Vb 6
363\& static void
364\& fatal_error (const char *msg)
365\& {
366\& perror (msg);
367\& abort ();
368\& }
369.Ve
370.Sp
371.Vb 2
372\& ...
373\& ev_set_syserr_cb (fatal_error);
374.Ve
224.SH "FUNCTIONS CONTROLLING THE EVENT LOOP" 375.SH "FUNCTIONS CONTROLLING THE EVENT LOOP"
225.IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" 376.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 377An 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 378types of such loops, the \fIdefault\fR loop, which supports signals and child
228events, and dynamically created loops which do not. 379events, and dynamically created loops which do not.
… …
236.IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 387.IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4
237.IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" 388.IX Item "struct ev_loop *ev_default_loop (unsigned int flags)"
238This will initialise the default event loop if it hasn't been initialised 389This 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 390yet 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 391false. If it already was initialised it simply returns it (and ignores the
241flags). 392flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards).
242.Sp 393.Sp
243If you don't know what event loop to use, use the one returned from this 394If you don't know what event loop to use, use the one returned from this
244function. 395function.
245.Sp 396.Sp
246The flags argument can be used to specify special behaviour or specific 397The 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). 398backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR).
248.Sp 399.Sp
249It supports the following flags: 400The following flags are supported:
250.RS 4 401.RS 4
251.ie n .IP """EVFLAG_AUTO""" 4 402.ie n .IP """EVFLAG_AUTO""" 4
252.el .IP "\f(CWEVFLAG_AUTO\fR" 4 403.el .IP "\f(CWEVFLAG_AUTO\fR" 4
253.IX Item "EVFLAG_AUTO" 404.IX Item "EVFLAG_AUTO"
254The default flags value. Use this if you have no clue (it's the right 405The 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 411or 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 412\&\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 413override 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 414useful to try out specific backends to test their performance, or to work
264around bugs. 415around bugs.
265.ie n .IP """EVMETHOD_SELECT"" (value 1, portable select backend)" 4 416.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
266.el .IP "\f(CWEVMETHOD_SELECT\fR (value 1, portable select backend)" 4 417.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
267.IX Item "EVMETHOD_SELECT (value 1, portable select backend)" 418.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
268This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 419This 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, 420libev 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 421but 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 422using this backend. It doesn't scale too well (O(highest_fd)), but its usually
272the fastest backend for a low number of fds. 423the fastest backend for a low number of fds.
273.ie n .IP """EVMETHOD_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 424.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)" 4 425.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)" 426.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 427And 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 428select, 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 429number 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). 430lot of inactive fds). It scales similarly to select, i.e. O(total_fds).
280.ie n .IP """EVMETHOD_EPOLL"" (value 4, Linux)" 4 431.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4
281.el .IP "\f(CWEVMETHOD_EPOLL\fR (value 4, Linux)" 4 432.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4
282.IX Item "EVMETHOD_EPOLL (value 4, Linux)" 433.IX Item "EVBACKEND_EPOLL (value 4, Linux)"
283For few fds, this backend is a bit little slower than poll and select, 434For 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 435but 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 436O(total_fds) where n is the total number of fds (or the highest fd), epoll scales
286either O(1) or O(active_fds). 437either O(1) or O(active_fds).
287.Sp 438.Sp
288While stopping and starting an I/O watcher in the same iteration will 439While stopping and starting an I/O watcher in the same iteration will
289result in some caching, there is still a syscall per such incident 440result 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 441(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 442best to avoid that. Also, \fIdup()\fRed file descriptors might not work very
292well if you register events for both fds. 443well if you register events for both fds.
444.Sp
445Please note that epoll sometimes generates spurious notifications, so you
446need to use non-blocking I/O or other means to avoid blocking when no data
447(or space) is available.
293.ie n .IP """EVMETHOD_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 448.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)" 4 449.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4
295.IX Item "EVMETHOD_KQUEUE (value 8, most BSD clones)" 450.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"
296Kqueue deserves special mention, as at the time of this writing, it 451Kqueue deserves special mention, as at the time of this writing, it
297was broken on all BSDs except NetBSD (usually it doesn't work with 452was broken on all BSDs except NetBSD (usually it doesn't work with
298anything but sockets and pipes, except on Darwin, where of course its 453anything but sockets and pipes, except on Darwin, where of course its
299completely useless). For this reason its not being \*(L"autodetected\*(R" unless 454completely 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). 455unless you explicitly specify it explicitly in the flags (i.e. using
456\&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR).
301.Sp 457.Sp
302It scales in the same way as the epoll backend, but the interface to the 458It 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 459kernel is more efficient (which says nothing about its actual speed, of
304course). While starting and stopping an I/O watcher does not cause an 460course). 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 461extra syscall as with epoll, it still adds up to four event changes per
306incident, so its best to avoid that. 462incident, so its best to avoid that.
307.ie n .IP """EVMETHOD_DEVPOLL"" (value 16, Solaris 8)" 4 463.ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4
308.el .IP "\f(CWEVMETHOD_DEVPOLL\fR (value 16, Solaris 8)" 4 464.el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4
309.IX Item "EVMETHOD_DEVPOLL (value 16, Solaris 8)" 465.IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)"
310This is not implemented yet (and might never be). 466This is not implemented yet (and might never be).
311.ie n .IP """EVMETHOD_PORT"" (value 32, Solaris 10)" 4 467.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4
312.el .IP "\f(CWEVMETHOD_PORT\fR (value 32, Solaris 10)" 4 468.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4
313.IX Item "EVMETHOD_PORT (value 32, Solaris 10)" 469.IX Item "EVBACKEND_PORT (value 32, Solaris 10)"
314This uses the Solaris 10 port mechanism. As with everything on Solaris, 470This uses the Solaris 10 port mechanism. As with everything on Solaris,
315it's really slow, but it still scales very well (O(active_fds)). 471it's really slow, but it still scales very well (O(active_fds)).
472.Sp
473Please note that solaris ports can result in a lot of spurious
474notifications, so you need to use non-blocking I/O or other means to avoid
475blocking when no data (or space) is available.
316.ie n .IP """EVMETHOD_ALL""" 4 476.ie n .IP """EVBACKEND_ALL""" 4
317.el .IP "\f(CWEVMETHOD_ALL\fR" 4 477.el .IP "\f(CWEVBACKEND_ALL\fR" 4
318.IX Item "EVMETHOD_ALL" 478.IX Item "EVBACKEND_ALL"
319Try all backends (even potentially broken ones that wouldn't be tried 479Try 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 480with \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. 481\&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR.
322.RE 482.RE
323.RS 4 483.RS 4
324.Sp 484.Sp
325If one or more of these are ored into the flags value, then only these 485If 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 486backends will be tried (in the reverse order as given here). If none are
327specified, most compiled-in backend will be tried, usually in reverse 487specified, most compiled-in backend will be tried, usually in reverse
328order of their flag values :) 488order of their flag values :)
489.Sp
490The most typical usage is like this:
491.Sp
492.Vb 2
493\& if (!ev_default_loop (0))
494\& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
495.Ve
496.Sp
497Restrict libev to the select and poll backends, and do not allow
498environment settings to be taken into account:
499.Sp
500.Vb 1
501\& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
502.Ve
503.Sp
504Use whatever libev has to offer, but make sure that kqueue is used if
505available (warning, breaks stuff, best use only with your own private
506event loop and only if you know the \s-1OS\s0 supports your types of fds):
507.Sp
508.Vb 1
509\& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
510.Ve
329.RE 511.RE
330.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 512.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4
331.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" 513.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 514Similar 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 515always 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 516handle signal and child watchers, and attempts to do so will be greeted by
335undefined behaviour (or a failed assertion if assertions are enabled). 517undefined behaviour (or a failed assertion if assertions are enabled).
518.Sp
519Example: Try to create a event loop that uses epoll and nothing else.
520.Sp
521.Vb 3
522\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
523\& if (!epoller)
524\& fatal ("no epoll found here, maybe it hides under your chair");
525.Ve
336.IP "ev_default_destroy ()" 4 526.IP "ev_default_destroy ()" 4
337.IX Item "ev_default_destroy ()" 527.IX Item "ev_default_destroy ()"
338Destroys the default loop again (frees all memory and kernel state 528Destroys the default loop again (frees all memory and kernel state
339etc.). This stops all registered event watchers (by not touching them in 529etc.). None of the active event watchers will be stopped in the normal
340any way whatsoever, although you cannot rely on this :). 530sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your
531responsibility to either stop all watchers cleanly yoursef \fIbefore\fR
532calling this function, or cope with the fact afterwards (which is usually
533the easiest thing, youc na just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them
534for example).
341.IP "ev_loop_destroy (loop)" 4 535.IP "ev_loop_destroy (loop)" 4
342.IX Item "ev_loop_destroy (loop)" 536.IX Item "ev_loop_destroy (loop)"
343Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an 537Like \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. 538earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR.
345.IP "ev_default_fork ()" 4 539.IP "ev_default_fork ()" 4
… …
347This function reinitialises the kernel state for backends that have 541This function reinitialises the kernel state for backends that have
348one. Despite the name, you can call it anytime, but it makes most sense 542one. Despite the name, you can call it anytime, but it makes most sense
349after forking, in either the parent or child process (or both, but that 543after forking, in either the parent or child process (or both, but that
350again makes little sense). 544again makes little sense).
351.Sp 545.Sp
352You \fImust\fR call this function after forking if and only if you want to 546You \fImust\fR call this function in the child process after forking if and
353use the event library in both processes. If you just fork+exec, you don't 547only if you want to use the event library in both processes. If you just
354have to call it. 548fork+exec, you don't have to call it.
355.Sp 549.Sp
356The function itself is quite fast and it's usually not a problem to call 550The function itself is quite fast and it's usually not a problem to call
357it just in case after a fork. To make this easy, the function will fit in 551it just in case after a fork. To make this easy, the function will fit in
358quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: 552quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR:
359.Sp 553.Sp
360.Vb 1 554.Vb 1
361\& pthread_atfork (0, 0, ev_default_fork); 555\& pthread_atfork (0, 0, ev_default_fork);
362.Ve 556.Ve
557.Sp
558At the moment, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR are safe to use
559without calling this function, so if you force one of those backends you
560do not need to care.
363.IP "ev_loop_fork (loop)" 4 561.IP "ev_loop_fork (loop)" 4
364.IX Item "ev_loop_fork (loop)" 562.IX Item "ev_loop_fork (loop)"
365Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by 563Like \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 564\&\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. 565after fork, and how you do this is entirely your own problem.
368.IP "unsigned int ev_method (loop)" 4 566.IP "unsigned int ev_backend (loop)" 4
369.IX Item "unsigned int ev_method (loop)" 567.IX Item "unsigned int ev_backend (loop)"
370Returns one of the \f(CW\*(C`EVMETHOD_*\*(C'\fR flags indicating the event backend in 568Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
371use. 569use.
372.IP "ev_tstamp ev_now (loop)" 4 570.IP "ev_tstamp ev_now (loop)" 4
373.IX Item "ev_tstamp ev_now (loop)" 571.IX Item "ev_tstamp ev_now (loop)"
374Returns the current \*(L"event loop time\*(R", which is the time the event loop 572Returns 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 573received events and started processing them. This timestamp does not
376as long as callbacks are being processed, and this is also the base time 574change 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 575time used for relative timers. You can treat it as the timestamp of the
378occuring (or more correctly, the mainloop finding out about it). 576event occuring (or more correctly, libev finding out about it).
379.IP "ev_loop (loop, int flags)" 4 577.IP "ev_loop (loop, int flags)" 4
380.IX Item "ev_loop (loop, int flags)" 578.IX Item "ev_loop (loop, int flags)"
381Finally, this is it, the event handler. This function usually is called 579Finally, this is it, the event handler. This function usually is called
382after you initialised all your watchers and you want to start handling 580after you initialised all your watchers and you want to start handling
383events. 581events.
384.Sp 582.Sp
385If the flags argument is specified as 0, it will not return until either 583If 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. 584either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called.
585.Sp
586Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than
587relying on all watchers to be stopped when deciding when a program has
588finished (especially in interactive programs), but having a program that
589automatically loops as long as it has to and no longer by virtue of
590relying on its watchers stopping correctly is a thing of beauty.
387.Sp 591.Sp
388A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle 592A 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 593those 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. 594case there are no events and will return after one iteration of the loop.
391.Sp 595.Sp
392A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if 596A 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 597neccessary) and will handle those and any outstanding ones. It will block
394your process until at least one new event arrives, and will return after 598your process until at least one new event arrives, and will return after
395one iteration of the loop. 599one iteration of the loop. This is useful if you are waiting for some
600external event in conjunction with something not expressible using other
601libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is
602usually a better approach for this kind of thing.
396.Sp 603.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: 604Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does:
402.Sp 605.Sp
403.Vb 15 606.Vb 18
404\& 1. If there are no active watchers (reference count is zero), return. 607\& * If there are no active watchers (reference count is zero), return.
405\& 2. Queue and immediately call all prepare watchers. 608\& - Queue prepare watchers and then call all outstanding watchers.
406\& 3. If we have been forked, recreate the kernel state. 609\& - If we have been forked, recreate the kernel state.
407\& 4. Update the kernel state with all outstanding changes. 610\& - Update the kernel state with all outstanding changes.
408\& 5. Update the "event loop time". 611\& - Update the "event loop time".
409\& 6. Calculate for how long to block. 612\& - Calculate for how long to block.
410\& 7. Block the process, waiting for events. 613\& - Block the process, waiting for any events.
614\& - Queue all outstanding I/O (fd) events.
411\& 8. Update the "event loop time" and do time jump handling. 615\& - Update the "event loop time" and do time jump handling.
412\& 9. Queue all outstanding timers. 616\& - Queue all outstanding timers.
413\& 10. Queue all outstanding periodics. 617\& - Queue all outstanding periodics.
414\& 11. If no events are pending now, queue all idle watchers. 618\& - If no events are pending now, queue all idle watchers.
415\& 12. Queue all check watchers. 619\& - Queue all check watchers.
416\& 13. Call all queued watchers in reverse order (i.e. check watchers first). 620\& - Call all queued watchers in reverse order (i.e. check watchers first).
621\& Signals and child watchers are implemented as I/O watchers, and will
622\& 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 623\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
418\& was used, return, otherwise continue with step #1. 624\& were used, return, otherwise continue with step *.
625.Ve
626.Sp
627Example: Queue some jobs and then loop until no events are outsanding
628anymore.
629.Sp
630.Vb 4
631\& ... queue jobs here, make sure they register event watchers as long
632\& ... as they still have work to do (even an idle watcher will do..)
633\& ev_loop (my_loop, 0);
634\& ... jobs done. yeah!
419.Ve 635.Ve
420.IP "ev_unloop (loop, how)" 4 636.IP "ev_unloop (loop, how)" 4
421.IX Item "ev_unloop (loop, how)" 637.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 638Can 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 639has 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 653example, 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 654visible 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 655no 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 656way 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. 657libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.
658.Sp
659Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR
660running when nothing else is active.
661.Sp
662.Vb 4
663\& struct ev_signal exitsig;
664\& ev_signal_init (&exitsig, sig_cb, SIGINT);
665\& ev_signal_start (loop, &exitsig);
666\& evf_unref (loop);
667.Ve
668.Sp
669Example: For some weird reason, unregister the above signal handler again.
670.Sp
671.Vb 2
672\& ev_ref (loop);
673\& ev_signal_stop (loop, &exitsig);
674.Ve
442.SH "ANATOMY OF A WATCHER" 675.SH "ANATOMY OF A WATCHER"
443.IX Header "ANATOMY OF A WATCHER" 676.IX Header "ANATOMY OF A WATCHER"
444A watcher is a structure that you create and register to record your 677A 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 678interest 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: 679become 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 715*)\*(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. 716corresponding stop function (\f(CW\*(C`ev_<type>_stop (loop, watcher *)\*(C'\fR.
484.PP 717.PP
485As long as your watcher is active (has been started but not stopped) you 718As 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 719must not touch the values stored in it. Most specifically you must never
487reinitialise it or call its set method. 720reinitialise 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 721.PP
494Each and every callback receives the event loop pointer as first, the 722Each and every callback receives the event loop pointer as first, the
495registered watcher structure as second, and a bitset of received events as 723registered watcher structure as second, and a bitset of received events as
496third argument. 724third argument.
497.PP 725.PP
… …
522The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread. 750The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread.
523.ie n .IP """EV_CHILD""" 4 751.ie n .IP """EV_CHILD""" 4
524.el .IP "\f(CWEV_CHILD\fR" 4 752.el .IP "\f(CWEV_CHILD\fR" 4
525.IX Item "EV_CHILD" 753.IX Item "EV_CHILD"
526The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change. 754The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change.
755.ie n .IP """EV_STAT""" 4
756.el .IP "\f(CWEV_STAT\fR" 4
757.IX Item "EV_STAT"
758The path specified in the \f(CW\*(C`ev_stat\*(C'\fR watcher changed its attributes somehow.
527.ie n .IP """EV_IDLE""" 4 759.ie n .IP """EV_IDLE""" 4
528.el .IP "\f(CWEV_IDLE\fR" 4 760.el .IP "\f(CWEV_IDLE\fR" 4
529.IX Item "EV_IDLE" 761.IX Item "EV_IDLE"
530The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do. 762The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do.
531.ie n .IP """EV_PREPARE""" 4 763.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 773\&\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 774received 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 775many 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 776(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). 777\&\f(CW\*(C`ev_loop\*(C'\fR from blocking).
778.ie n .IP """EV_EMBED""" 4
779.el .IP "\f(CWEV_EMBED\fR" 4
780.IX Item "EV_EMBED"
781The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention.
782.ie n .IP """EV_FORK""" 4
783.el .IP "\f(CWEV_FORK\fR" 4
784.IX Item "EV_FORK"
785The event loop has been resumed in the child process after fork (see
786\&\f(CW\*(C`ev_fork\*(C'\fR).
546.ie n .IP """EV_ERROR""" 4 787.ie n .IP """EV_ERROR""" 4
547.el .IP "\f(CWEV_ERROR\fR" 4 788.el .IP "\f(CWEV_ERROR\fR" 4
548.IX Item "EV_ERROR" 789.IX Item "EV_ERROR"
549An unspecified error has occured, the watcher has been stopped. This might 790An unspecified error has occured, the watcher has been stopped. This might
550happen because the watcher could not be properly started because libev 791happen because the watcher could not be properly started because libev
… …
555Libev will usually signal a few \*(L"dummy\*(R" events together with an error, 796Libev 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 797for 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 798your 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 799with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded
559programs, though, so beware. 800programs, though, so beware.
801.Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0"
802.IX Subsection "GENERIC WATCHER FUNCTIONS"
803In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type,
804e.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.
805.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4
806.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4
807.IX Item "ev_init (ev_TYPE *watcher, callback)"
808This macro initialises the generic portion of a watcher. The contents
809of the watcher object can be arbitrary (so \f(CW\*(C`malloc\*(C'\fR will do). Only
810the generic parts of the watcher are initialised, you \fIneed\fR to call
811the type-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR macro afterwards to initialise the
812type-specific parts. For each type there is also a \f(CW\*(C`ev_TYPE_init\*(C'\fR macro
813which rolls both calls into one.
814.Sp
815You can reinitialise a watcher at any time as long as it has been stopped
816(or never started) and there are no pending events outstanding.
817.Sp
818The callback is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher,
819int revents)\*(C'\fR.
820.ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4
821.el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4
822.IX Item "ev_TYPE_set (ev_TYPE *, [args])"
823This macro initialises the type-specific parts of a watcher. You need to
824call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can
825call \f(CW\*(C`ev_TYPE_set\*(C'\fR any number of times. You must not, however, call this
826macro on a watcher that is active (it can be pending, however, which is a
827difference to the \f(CW\*(C`ev_init\*(C'\fR macro).
828.Sp
829Although some watcher types do not have type-specific arguments
830(e.g. \f(CW\*(C`ev_prepare\*(C'\fR) you still need to call its \f(CW\*(C`set\*(C'\fR macro.
831.ie n .IP """ev_TYPE_init"" (ev_TYPE *watcher, callback, [args])" 4
832.el .IP "\f(CWev_TYPE_init\fR (ev_TYPE *watcher, callback, [args])" 4
833.IX Item "ev_TYPE_init (ev_TYPE *watcher, callback, [args])"
834This convinience macro rolls both \f(CW\*(C`ev_init\*(C'\fR and \f(CW\*(C`ev_TYPE_set\*(C'\fR macro
835calls into a single call. This is the most convinient method to initialise
836a watcher. The same limitations apply, of course.
837.ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4
838.el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4
839.IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)"
840Starts (activates) the given watcher. Only active watchers will receive
841events. If the watcher is already active nothing will happen.
842.ie n .IP """ev_TYPE_stop"" (loop *, ev_TYPE *watcher)" 4
843.el .IP "\f(CWev_TYPE_stop\fR (loop *, ev_TYPE *watcher)" 4
844.IX Item "ev_TYPE_stop (loop *, ev_TYPE *watcher)"
845Stops the given watcher again (if active) and clears the pending
846status. It is possible that stopped watchers are pending (for example,
847non-repeating timers are being stopped when they become pending), but
848\&\f(CW\*(C`ev_TYPE_stop\*(C'\fR ensures that the watcher is neither active nor pending. If
849you want to free or reuse the memory used by the watcher it is therefore a
850good idea to always call its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function.
851.IP "bool ev_is_active (ev_TYPE *watcher)" 4
852.IX Item "bool ev_is_active (ev_TYPE *watcher)"
853Returns a true value iff the watcher is active (i.e. it has been started
854and not yet been stopped). As long as a watcher is active you must not modify
855it.
856.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
857.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
858Returns a true value iff the watcher is pending, (i.e. it has outstanding
859events but its callback has not yet been invoked). As long as a watcher
860is pending (but not active) you must not call an init function on it (but
861\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to
862libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it).
863.IP "callback ev_cb (ev_TYPE *watcher)" 4
864.IX Item "callback ev_cb (ev_TYPE *watcher)"
865Returns the callback currently set on the watcher.
866.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
867.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
868Change the callback. You can change the callback at virtually any time
869(modulo threads).
560.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 870.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" 871.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 872Each 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 873and 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 874to associate arbitrary data with your watcher. If you need more data and
… …
585\& struct my_io *w = (struct my_io *)w_; 895\& struct my_io *w = (struct my_io *)w_;
586\& ... 896\& ...
587\& } 897\& }
588.Ve 898.Ve
589.PP 899.PP
590More interesting and less C\-conformant ways of catsing your callback type 900More interesting and less C\-conformant ways of casting your callback type
591have been omitted.... 901instead have been omitted.
902.PP
903Another common scenario is having some data structure with multiple
904watchers:
905.PP
906.Vb 6
907\& struct my_biggy
908\& {
909\& int some_data;
910\& ev_timer t1;
911\& ev_timer t2;
912\& }
913.Ve
914.PP
915In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated,
916you need to use \f(CW\*(C`offsetof\*(C'\fR:
917.PP
918.Vb 1
919\& #include <stddef.h>
920.Ve
921.PP
922.Vb 6
923\& static void
924\& t1_cb (EV_P_ struct ev_timer *w, int revents)
925\& {
926\& struct my_biggy big = (struct my_biggy *
927\& (((char *)w) - offsetof (struct my_biggy, t1));
928\& }
929.Ve
930.PP
931.Vb 6
932\& static void
933\& t2_cb (EV_P_ struct ev_timer *w, int revents)
934\& {
935\& struct my_biggy big = (struct my_biggy *
936\& (((char *)w) - offsetof (struct my_biggy, t2));
937\& }
938.Ve
592.SH "WATCHER TYPES" 939.SH "WATCHER TYPES"
593.IX Header "WATCHER TYPES" 940.IX Header "WATCHER TYPES"
594This section describes each watcher in detail, but will not repeat 941This section describes each watcher in detail, but will not repeat
595information given in the last section. 942information given in the last section. Any initialisation/set macros,
943functions and members specific to the watcher type are explained.
944.PP
945Members are additionally marked with either \fI[read\-only]\fR, meaning that,
946while the watcher is active, you can look at the member and expect some
947sensible content, but you must not modify it (you can modify it while the
948watcher is stopped to your hearts content), or \fI[read\-write]\fR, which
949means you can expect it to have some sensible content while the watcher
950is active, but you can also modify it. Modifying it may not do something
951sensible or take immediate effect (or do anything at all), but libev will
952not crash or malfunction in any way.
596.ie n .Sh """ev_io"" \- is this file descriptor readable or writable" 953.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" 954.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" 955.IX Subsection "ev_io - is this file descriptor readable or writable?"
599I/O watchers check whether a file descriptor is readable or writable 956I/O watchers check whether a file descriptor is readable or writable
600in each iteration of the event loop (This behaviour is called 957in each iteration of the event loop, or, more precisely, when reading
601level-triggering because you keep receiving events as long as the 958would 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 959some data. This behaviour is called level-triggering because you keep
603act on the event and neither want to receive future events). 960receiving events as long as the condition persists. Remember you can stop
961the watcher if you don't want to act on the event and neither want to
962receive future events.
604.PP 963.PP
605In general you can register as many read and/or write event watchers per 964In 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 965fd 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 966descriptors to non-blocking mode is also usually a good idea (but not
608required if you know what you are doing). 967required if you know what you are doing).
609.PP 968.PP
610You have to be careful with dup'ed file descriptors, though. Some backends 969You 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 970(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 971descriptors correctly if you register interest in two or more fds pointing
613to the same underlying file/socket etc. description (that is, they share 972to the same underlying file/socket/etc. description (that is, they share
614the same underlying \*(L"file open\*(R"). 973the same underlying \*(L"file open\*(R").
615.PP 974.PP
616If you must do this, then force the use of a known-to-be-good backend 975If 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 976(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and
618\&\s-1EVMETHOD_POLL\s0). 977\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR).
978.PP
979Another thing you have to watch out for is that it is quite easy to
980receive \*(L"spurious\*(R" readyness notifications, that is your callback might
981be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block
982because there is no data. Not only are some backends known to create a
983lot of those (for example solaris ports), it is very easy to get into
984this situation even with a relatively standard program structure. Thus
985it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning
986\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
987.PP
988If you cannot run the fd in non-blocking mode (for example you should not
989play around with an Xlib connection), then you have to seperately re-test
990wether a file descriptor is really ready with a known-to-be good interface
991such as poll (fortunately in our Xlib example, Xlib already does this on
992its own, so its quite safe to use).
619.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 993.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)" 994.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
621.PD 0 995.PD 0
622.IP "ev_io_set (ev_io *, int fd, int events)" 4 996.IP "ev_io_set (ev_io *, int fd, int events)" 4
623.IX Item "ev_io_set (ev_io *, int fd, int events)" 997.IX Item "ev_io_set (ev_io *, int fd, int events)"
624.PD 998.PD
625Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The fd is the file descriptor to rceeive 999Configures 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 | 1000rceeive 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. 1001\&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events.
1002.IP "int fd [read\-only]" 4
1003.IX Item "int fd [read-only]"
1004The file descriptor being watched.
1005.IP "int events [read\-only]" 4
1006.IX Item "int events [read-only]"
1007The events being watched.
1008.PP
1009Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well
1010readable, but only once. Since it is likely line\-buffered, you could
1011attempt to read a whole line in the callback.
1012.PP
1013.Vb 6
1014\& static void
1015\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1016\& {
1017\& ev_io_stop (loop, w);
1018\& .. read from stdin here (or from w->fd) and haqndle any I/O errors
1019\& }
1020.Ve
1021.PP
1022.Vb 6
1023\& ...
1024\& struct ev_loop *loop = ev_default_init (0);
1025\& struct ev_io stdin_readable;
1026\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1027\& ev_io_start (loop, &stdin_readable);
1028\& ev_loop (loop, 0);
1029.Ve
628.ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts" 1030.ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts"
629.el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts" 1031.el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts"
630.IX Subsection "ev_timer - relative and optionally recurring timeouts" 1032.IX Subsection "ev_timer - relative and optionally repeating timeouts"
631Timer watchers are simple relative timers that generate an event after a 1033Timer watchers are simple relative timers that generate an event after a
632given time, and optionally repeating in regular intervals after that. 1034given time, and optionally repeating in regular intervals after that.
633.PP 1035.PP
634The timers are based on real time, that is, if you register an event that 1036The 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 1037times out after an hour and you reset your system clock to last years
… …
675.Sp 1077.Sp
676If the timer is repeating, either start it if necessary (with the repeat 1078If the timer is repeating, either start it if necessary (with the repeat
677value), or reset the running timer to the repeat value. 1079value), or reset the running timer to the repeat value.
678.Sp 1080.Sp
679This sounds a bit complicated, but here is a useful and typical 1081This 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 1082example: 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 1083idle 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 1084say, 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 1085this 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 1086\&\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 1087you 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. 1088socket, you can stop the timer, and again will automatically restart it if
1089need be.
1090.Sp
1091You can also ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR altogether
1092and only ever use the \f(CW\*(C`repeat\*(C'\fR value:
1093.Sp
1094.Vb 8
1095\& ev_timer_init (timer, callback, 0., 5.);
1096\& ev_timer_again (loop, timer);
1097\& ...
1098\& timer->again = 17.;
1099\& ev_timer_again (loop, timer);
1100\& ...
1101\& timer->again = 10.;
1102\& ev_timer_again (loop, timer);
1103.Ve
1104.Sp
1105This is more efficient then stopping/starting the timer eahc time you want
1106to modify its timeout value.
1107.IP "ev_tstamp repeat [read\-write]" 4
1108.IX Item "ev_tstamp repeat [read-write]"
1109The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out
1110or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any),
1111which is also when any modifications are taken into account.
1112.PP
1113Example: Create a timer that fires after 60 seconds.
1114.PP
1115.Vb 5
1116\& static void
1117\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1118\& {
1119\& .. one minute over, w is actually stopped right here
1120\& }
1121.Ve
1122.PP
1123.Vb 3
1124\& struct ev_timer mytimer;
1125\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1126\& ev_timer_start (loop, &mytimer);
1127.Ve
1128.PP
1129Example: Create a timeout timer that times out after 10 seconds of
1130inactivity.
1131.PP
1132.Vb 5
1133\& static void
1134\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1135\& {
1136\& .. ten seconds without any activity
1137\& }
1138.Ve
1139.PP
1140.Vb 4
1141\& struct ev_timer mytimer;
1142\& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1143\& ev_timer_again (&mytimer); /* start timer */
1144\& ev_loop (loop, 0);
1145.Ve
1146.PP
1147.Vb 3
1148\& // and in some piece of code that gets executed on any "activity":
1149\& // reset the timeout to start ticking again at 10 seconds
1150\& ev_timer_again (&mytimer);
1151.Ve
687.ie n .Sh """ev_periodic"" \- to cron or not to cron" 1152.ie n .Sh """ev_periodic"" \- to cron or not to cron?"
688.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron" 1153.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?"
689.IX Subsection "ev_periodic - to cron or not to cron" 1154.IX Subsection "ev_periodic - to cron or not to cron?"
690Periodic watchers are also timers of a kind, but they are very versatile 1155Periodic watchers are also timers of a kind, but they are very versatile
691(and unfortunately a bit complex). 1156(and unfortunately a bit complex).
692.PP 1157.PP
693Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) 1158Unlike \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 1159but 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 1160to 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 () 1161periodic 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 1162+ 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 1163take 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 1164roughly 10 seconds later and of course not if you reset your system time
700again). 1165again).
701.PP 1166.PP
702They can also be used to implement vastly more complex timers, such as 1167They can also be used to implement vastly more complex timers, such as
… …
783.IX Item "ev_periodic_again (loop, ev_periodic *)" 1248.IX Item "ev_periodic_again (loop, ev_periodic *)"
784Simply stops and restarts the periodic watcher again. This is only useful 1249Simply stops and restarts the periodic watcher again. This is only useful
785when you changed some parameters or the reschedule callback would return 1250when 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 1251a different time than the last time it was called (e.g. in a crond like
787program when the crontabs have changed). 1252program when the crontabs have changed).
1253.IP "ev_tstamp interval [read\-write]" 4
1254.IX Item "ev_tstamp interval [read-write]"
1255The current interval value. Can be modified any time, but changes only
1256take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being
1257called.
1258.IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4
1259.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]"
1260The current reschedule callback, or \f(CW0\fR, if this functionality is
1261switched off. Can be changed any time, but changes only take effect when
1262the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1263.PP
1264Example: Call a callback every hour, or, more precisely, whenever the
1265system clock is divisible by 3600. The callback invocation times have
1266potentially a lot of jittering, but good long-term stability.
1267.PP
1268.Vb 5
1269\& static void
1270\& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1271\& {
1272\& ... its now a full hour (UTC, or TAI or whatever your clock follows)
1273\& }
1274.Ve
1275.PP
1276.Vb 3
1277\& struct ev_periodic hourly_tick;
1278\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1279\& ev_periodic_start (loop, &hourly_tick);
1280.Ve
1281.PP
1282Example: The same as above, but use a reschedule callback to do it:
1283.PP
1284.Vb 1
1285\& #include <math.h>
1286.Ve
1287.PP
1288.Vb 5
1289\& static ev_tstamp
1290\& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1291\& {
1292\& return fmod (now, 3600.) + 3600.;
1293\& }
1294.Ve
1295.PP
1296.Vb 1
1297\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1298.Ve
1299.PP
1300Example: Call a callback every hour, starting now:
1301.PP
1302.Vb 4
1303\& struct ev_periodic hourly_tick;
1304\& ev_periodic_init (&hourly_tick, clock_cb,
1305\& fmod (ev_now (loop), 3600.), 3600., 0);
1306\& ev_periodic_start (loop, &hourly_tick);
1307.Ve
788.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled" 1308.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" 1309.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" 1310.IX Subsection "ev_signal - signal me when a signal gets signalled!"
791Signal watchers will trigger an event when the process receives a specific 1311Signal watchers will trigger an event when the process receives a specific
792signal one or more times. Even though signals are very asynchronous, libev 1312signal 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 1313will try it's best to deliver signals synchronously, i.e. as part of the
794normal event processing, like any other event. 1314normal event processing, like any other event.
795.PP 1315.PP
… …
805.IP "ev_signal_set (ev_signal *, int signum)" 4 1325.IP "ev_signal_set (ev_signal *, int signum)" 4
806.IX Item "ev_signal_set (ev_signal *, int signum)" 1326.IX Item "ev_signal_set (ev_signal *, int signum)"
807.PD 1327.PD
808Configures the watcher to trigger on the given signal number (usually one 1328Configures the watcher to trigger on the given signal number (usually one
809of the \f(CW\*(C`SIGxxx\*(C'\fR constants). 1329of the \f(CW\*(C`SIGxxx\*(C'\fR constants).
1330.IP "int signum [read\-only]" 4
1331.IX Item "int signum [read-only]"
1332The signal the watcher watches out for.
810.ie n .Sh """ev_child"" \- wait for pid status changes" 1333.ie n .Sh """ev_child"" \- watch out for process status changes"
811.el .Sh "\f(CWev_child\fP \- wait for pid status changes" 1334.el .Sh "\f(CWev_child\fP \- watch out for process status changes"
812.IX Subsection "ev_child - wait for pid status changes" 1335.IX Subsection "ev_child - watch out for process status changes"
813Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to 1336Child 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). 1337some child status changes (most typically when a child of yours dies).
815.IP "ev_child_init (ev_child *, callback, int pid)" 4 1338.IP "ev_child_init (ev_child *, callback, int pid)" 4
816.IX Item "ev_child_init (ev_child *, callback, int pid)" 1339.IX Item "ev_child_init (ev_child *, callback, int pid)"
817.PD 0 1340.PD 0
… …
822\&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look 1345\&\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 1346at 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 1347the 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 1348\&\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. 1349process causing the status change.
1350.IP "int pid [read\-only]" 4
1351.IX Item "int pid [read-only]"
1352The process id this watcher watches out for, or \f(CW0\fR, meaning any process id.
1353.IP "int rpid [read\-write]" 4
1354.IX Item "int rpid [read-write]"
1355The process id that detected a status change.
1356.IP "int rstatus [read\-write]" 4
1357.IX Item "int rstatus [read-write]"
1358The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems
1359\&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details).
1360.PP
1361Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.
1362.PP
1363.Vb 5
1364\& static void
1365\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1366\& {
1367\& ev_unloop (loop, EVUNLOOP_ALL);
1368\& }
1369.Ve
1370.PP
1371.Vb 3
1372\& struct ev_signal signal_watcher;
1373\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1374\& ev_signal_start (loop, &sigint_cb);
1375.Ve
1376.ie n .Sh """ev_stat"" \- did the file attributes just change?"
1377.el .Sh "\f(CWev_stat\fP \- did the file attributes just change?"
1378.IX Subsection "ev_stat - did the file attributes just change?"
1379This watches a filesystem path for attribute changes. That is, it calls
1380\&\f(CW\*(C`stat\*(C'\fR regularly (or when the \s-1OS\s0 says it changed) and sees if it changed
1381compared to the last time, invoking the callback if it did.
1382.PP
1383The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does
1384not exist\*(R" is a status change like any other. The condition \*(L"path does
1385not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is
1386otherwise always forced to be at least one) and all the other fields of
1387the stat buffer having unspecified contents.
1388.PP
1389Since there is no standard to do this, the portable implementation simply
1390calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You
1391can specify a recommended polling interval for this case. If you specify
1392a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable,
1393unspecified default\fR value will be used (which you can expect to be around
1394five seconds, although this might change dynamically). Libev will also
1395impose a minimum interval which is currently around \f(CW0.1\fR, but thats
1396usually overkill.
1397.PP
1398This watcher type is not meant for massive numbers of stat watchers,
1399as even with OS-supported change notifications, this can be
1400resource\-intensive.
1401.PP
1402At the time of this writing, only the Linux inotify interface is
1403implemented (implementing kqueue support is left as an exercise for the
1404reader). Inotify will be used to give hints only and should not change the
1405semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs
1406to fall back to regular polling again even with inotify, but changes are
1407usually detected immediately, and if the file exists there will be no
1408polling.
1409.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
1410.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
1411.PD 0
1412.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4
1413.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
1414.PD
1415Configures the watcher to wait for status changes of the given
1416\&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to
1417be detected and should normally be specified as \f(CW0\fR to let libev choose
1418a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same
1419path for as long as the watcher is active.
1420.Sp
1421The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected,
1422relative to the attributes at the time the watcher was started (or the
1423last change was detected).
1424.IP "ev_stat_stat (ev_stat *)" 4
1425.IX Item "ev_stat_stat (ev_stat *)"
1426Updates the stat buffer immediately with new values. If you change the
1427watched path in your callback, you could call this fucntion to avoid
1428detecting this change (while introducing a race condition). Can also be
1429useful simply to find out the new values.
1430.IP "ev_statdata attr [read\-only]" 4
1431.IX Item "ev_statdata attr [read-only]"
1432The most-recently detected attributes of the file. Although the type is of
1433\&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types
1434suitable for your system. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there
1435was some error while \f(CW\*(C`stat\*(C'\fRing the file.
1436.IP "ev_statdata prev [read\-only]" 4
1437.IX Item "ev_statdata prev [read-only]"
1438The previous attributes of the file. The callback gets invoked whenever
1439\&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR.
1440.IP "ev_tstamp interval [read\-only]" 4
1441.IX Item "ev_tstamp interval [read-only]"
1442The specified interval.
1443.IP "const char *path [read\-only]" 4
1444.IX Item "const char *path [read-only]"
1445The filesystem path that is being watched.
1446.PP
1447Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes.
1448.PP
1449.Vb 15
1450\& static void
1451\& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1452\& {
1453\& /* /etc/passwd changed in some way */
1454\& if (w->attr.st_nlink)
1455\& {
1456\& printf ("passwd current size %ld\en", (long)w->attr.st_size);
1457\& printf ("passwd current atime %ld\en", (long)w->attr.st_mtime);
1458\& printf ("passwd current mtime %ld\en", (long)w->attr.st_mtime);
1459\& }
1460\& else
1461\& /* you shalt not abuse printf for puts */
1462\& puts ("wow, /etc/passwd is not there, expect problems. "
1463\& "if this is windows, they already arrived\en");
1464\& }
1465.Ve
1466.PP
1467.Vb 2
1468\& ...
1469\& ev_stat passwd;
1470.Ve
1471.PP
1472.Vb 2
1473\& ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
1474\& ev_stat_start (loop, &passwd);
1475.Ve
827.ie n .Sh """ev_idle"" \- when you've got nothing better to do" 1476.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" 1477.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" 1478.IX Subsection "ev_idle - when you've got nothing better to do..."
830Idle watchers trigger events when there are no other events are pending 1479Idle 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 1480(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, 1481as 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 1482imagine) 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 \- 1483watchers are being called again and again, once per event loop iteration \-
… …
845.IP "ev_idle_init (ev_signal *, callback)" 4 1494.IP "ev_idle_init (ev_signal *, callback)" 4
846.IX Item "ev_idle_init (ev_signal *, callback)" 1495.IX Item "ev_idle_init (ev_signal *, callback)"
847Initialises and configures the idle watcher \- it has no parameters of any 1496Initialises 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, 1497kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,
849believe me. 1498believe me.
1499.PP
1500Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the
1501callback, free it. Also, use no error checking, as usual.
1502.PP
1503.Vb 7
1504\& static void
1505\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1506\& {
1507\& free (w);
1508\& // now do something you wanted to do when the program has
1509\& // no longer asnything immediate to do.
1510\& }
1511.Ve
1512.PP
1513.Vb 3
1514\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1515\& ev_idle_init (idle_watcher, idle_cb);
1516\& ev_idle_start (loop, idle_cb);
1517.Ve
850.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop" 1518.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" 1519.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" 1520.IX Subsection "ev_prepare and ev_check - customise your event loop!"
853Prepare and check watchers are usually (but not always) used in tandem: 1521Prepare and check watchers are usually (but not always) used in tandem:
854prepare watchers get invoked before the process blocks and check watchers 1522prepare watchers get invoked before the process blocks and check watchers
855afterwards. 1523afterwards.
856.PP 1524.PP
1525You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter
1526the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR
1527watchers. Other loops than the current one are fine, however. The
1528rationale behind this is that you do not need to check for recursion in
1529those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking,
1530\&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be
1531called in pairs bracketing the blocking call.
1532.PP
857Their main purpose is to integrate other event mechanisms into libev. This 1533Their main purpose is to integrate other event mechanisms into libev and
858could be used, for example, to track variable changes, implement your own 1534their use is somewhat advanced. This could be used, for example, to track
859watchers, integrate net-snmp or a coroutine library and lots more. 1535variable changes, implement your own watchers, integrate net-snmp or a
1536coroutine library and lots more. They are also occasionally useful if
1537you cache some data and want to flush it before blocking (for example,
1538in X programs you might want to do an \f(CW\*(C`XFlush ()\*(C'\fR in an \f(CW\*(C`ev_prepare\*(C'\fR
1539watcher).
860.PP 1540.PP
861This is done by examining in each prepare call which file descriptors need 1541This 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 1542to 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 1543them 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 1544provide just this functionality). Then, in the check watcher you check for
… …
882.IX Item "ev_check_init (ev_check *, callback)" 1562.IX Item "ev_check_init (ev_check *, callback)"
883.PD 1563.PD
884Initialises and configures the prepare or check watcher \- they have no 1564Initialises 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 1565parameters 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. 1566macros, but using them is utterly, utterly and completely pointless.
1567.PP
1568Example: To include a library such as adns, you would add \s-1IO\s0 watchers
1569and a timeout watcher in a prepare handler, as required by libadns, and
1570in a check watcher, destroy them and call into libadns. What follows is
1571pseudo-code only of course:
1572.PP
1573.Vb 2
1574\& static ev_io iow [nfd];
1575\& static ev_timer tw;
1576.Ve
1577.PP
1578.Vb 9
1579\& static void
1580\& io_cb (ev_loop *loop, ev_io *w, int revents)
1581\& {
1582\& // set the relevant poll flags
1583\& // could also call adns_processreadable etc. here
1584\& struct pollfd *fd = (struct pollfd *)w->data;
1585\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1586\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1587\& }
1588.Ve
1589.PP
1590.Vb 7
1591\& // create io watchers for each fd and a timer before blocking
1592\& static void
1593\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1594\& {
1595\& int timeout = 3600000;truct pollfd fds [nfd];
1596\& // actual code will need to loop here and realloc etc.
1597\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1598.Ve
1599.PP
1600.Vb 3
1601\& /* the callback is illegal, but won't be called as we stop during check */
1602\& ev_timer_init (&tw, 0, timeout * 1e-3);
1603\& ev_timer_start (loop, &tw);
1604.Ve
1605.PP
1606.Vb 6
1607\& // create on ev_io per pollfd
1608\& for (int i = 0; i < nfd; ++i)
1609\& {
1610\& ev_io_init (iow + i, io_cb, fds [i].fd,
1611\& ((fds [i].events & POLLIN ? EV_READ : 0)
1612\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1613.Ve
1614.PP
1615.Vb 5
1616\& fds [i].revents = 0;
1617\& iow [i].data = fds + i;
1618\& ev_io_start (loop, iow + i);
1619\& }
1620\& }
1621.Ve
1622.PP
1623.Vb 5
1624\& // stop all watchers after blocking
1625\& static void
1626\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1627\& {
1628\& ev_timer_stop (loop, &tw);
1629.Ve
1630.PP
1631.Vb 2
1632\& for (int i = 0; i < nfd; ++i)
1633\& ev_io_stop (loop, iow + i);
1634.Ve
1635.PP
1636.Vb 2
1637\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1638\& }
1639.Ve
1640.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1641.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
1642.IX Subsection "ev_embed - when one backend isn't enough..."
1643This is a rather advanced watcher type that lets you embed one event loop
1644into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded
1645loop, other types of watchers might be handled in a delayed or incorrect
1646fashion and must not be used).
1647.PP
1648There are primarily two reasons you would want that: work around bugs and
1649prioritise I/O.
1650.PP
1651As an example for a bug workaround, the kqueue backend might only support
1652sockets on some platform, so it is unusable as generic backend, but you
1653still want to make use of it because you have many sockets and it scales
1654so nicely. In this case, you would create a kqueue-based loop and embed it
1655into your default loop (which might use e.g. poll). Overall operation will
1656be a bit slower because first libev has to poll and then call kevent, but
1657at least you can use both at what they are best.
1658.PP
1659As for prioritising I/O: rarely you have the case where some fds have
1660to be watched and handled very quickly (with low latency), and even
1661priorities and idle watchers might have too much overhead. In this case
1662you would put all the high priority stuff in one loop and all the rest in
1663a second one, and embed the second one in the first.
1664.PP
1665As long as the watcher is active, the callback will be invoked every time
1666there might be events pending in the embedded loop. The callback must then
1667call \f(CW\*(C`ev_embed_sweep (mainloop, watcher)\*(C'\fR to make a single sweep and invoke
1668their callbacks (you could also start an idle watcher to give the embedded
1669loop strictly lower priority for example). You can also set the callback
1670to \f(CW0\fR, in which case the embed watcher will automatically execute the
1671embedded loop sweep.
1672.PP
1673As long as the watcher is started it will automatically handle events. The
1674callback will be invoked whenever some events have been handled. You can
1675set the callback to \f(CW0\fR to avoid having to specify one if you are not
1676interested in that.
1677.PP
1678Also, there have not currently been made special provisions for forking:
1679when you fork, you not only have to call \f(CW\*(C`ev_loop_fork\*(C'\fR on both loops,
1680but you will also have to stop and restart any \f(CW\*(C`ev_embed\*(C'\fR watchers
1681yourself.
1682.PP
1683Unfortunately, not all backends are embeddable, only the ones returned by
1684\&\f(CW\*(C`ev_embeddable_backends\*(C'\fR are, which, unfortunately, does not include any
1685portable one.
1686.PP
1687So when you want to use this feature you will always have to be prepared
1688that you cannot get an embeddable loop. The recommended way to get around
1689this is to have a separate variables for your embeddable loop, try to
1690create it, and if that fails, use the normal loop for everything:
1691.PP
1692.Vb 3
1693\& struct ev_loop *loop_hi = ev_default_init (0);
1694\& struct ev_loop *loop_lo = 0;
1695\& struct ev_embed embed;
1696.Ve
1697.PP
1698.Vb 5
1699\& // see if there is a chance of getting one that works
1700\& // (remember that a flags value of 0 means autodetection)
1701\& loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
1702\& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
1703\& : 0;
1704.Ve
1705.PP
1706.Vb 8
1707\& // if we got one, then embed it, otherwise default to loop_hi
1708\& if (loop_lo)
1709\& {
1710\& ev_embed_init (&embed, 0, loop_lo);
1711\& ev_embed_start (loop_hi, &embed);
1712\& }
1713\& else
1714\& loop_lo = loop_hi;
1715.Ve
1716.IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
1717.IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)"
1718.PD 0
1719.IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
1720.IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)"
1721.PD
1722Configures the watcher to embed the given loop, which must be
1723embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be
1724invoked automatically, otherwise it is the responsibility of the callback
1725to invoke it (it will continue to be called until the sweep has been done,
1726if you do not want thta, you need to temporarily stop the embed watcher).
1727.IP "ev_embed_sweep (loop, ev_embed *)" 4
1728.IX Item "ev_embed_sweep (loop, ev_embed *)"
1729Make a single, non-blocking sweep over the embedded loop. This works
1730similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most
1731apropriate way for embedded loops.
1732.IP "struct ev_loop *loop [read\-only]" 4
1733.IX Item "struct ev_loop *loop [read-only]"
1734The embedded event loop.
1735.ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork"
1736.el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork"
1737.IX Subsection "ev_fork - the audacity to resume the event loop after a fork"
1738Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because
1739whoever is a good citizen cared to tell libev about it by calling
1740\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the
1741event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called,
1742and only in the child after the fork. If whoever good citizen calling
1743\&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork
1744handlers will be invoked, too, of course.
1745.IP "ev_fork_init (ev_signal *, callback)" 4
1746.IX Item "ev_fork_init (ev_signal *, callback)"
1747Initialises and configures the fork watcher \- it has no parameters of any
1748kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless,
1749believe me.
887.SH "OTHER FUNCTIONS" 1750.SH "OTHER FUNCTIONS"
888.IX Header "OTHER FUNCTIONS" 1751.IX Header "OTHER FUNCTIONS"
889There are some other functions of possible interest. Described. Here. Now. 1752There are some other functions of possible interest. Described. Here. Now.
890.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 1753.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)" 1754.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)"
… …
920.Ve 1783.Ve
921.Sp 1784.Sp
922.Vb 1 1785.Vb 1
923\& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); 1786\& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
924.Ve 1787.Ve
925.IP "ev_feed_event (loop, watcher, int events)" 4 1788.IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4
926.IX Item "ev_feed_event (loop, watcher, int events)" 1789.IX Item "ev_feed_event (ev_loop *, watcher *, int revents)"
927Feeds the given event set into the event loop, as if the specified event 1790Feeds 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 1791had happened for the specified watcher (which must be a pointer to an
929initialised but not necessarily started event watcher). 1792initialised but not necessarily started event watcher).
930.IP "ev_feed_fd_event (loop, int fd, int revents)" 4 1793.IP "ev_feed_fd_event (ev_loop *, int fd, int revents)" 4
931.IX Item "ev_feed_fd_event (loop, int fd, int revents)" 1794.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 1795Feed an event on the given fd, as if a file descriptor backend detected
933the given events it. 1796the given events it.
934.IP "ev_feed_signal_event (loop, int signum)" 4 1797.IP "ev_feed_signal_event (ev_loop *loop, int signum)" 4
935.IX Item "ev_feed_signal_event (loop, int signum)" 1798.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!). 1799Feed an event as if the given signal occured (\f(CW\*(C`loop\*(C'\fR must be the default
1800loop!).
937.SH "LIBEVENT EMULATION" 1801.SH "LIBEVENT EMULATION"
938.IX Header "LIBEVENT EMULATION" 1802.IX Header "LIBEVENT EMULATION"
939Libev offers a compatibility emulation layer for libevent. It cannot 1803Libev offers a compatibility emulation layer for libevent. It cannot
940emulate the internals of libevent, so here are some usage hints: 1804emulate the internals of libevent, so here are some usage hints:
941.IP "* Use it by including <event.h>, as usual." 4 1805.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 1816.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." 1817.IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library."
954.PD 1818.PD
955.SH "\*(C+ SUPPORT" 1819.SH "\*(C+ SUPPORT"
956.IX Header " SUPPORT" 1820.IX Header " SUPPORT"
957\&\s-1TBD\s0. 1821Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow
1822you to use some convinience methods to start/stop watchers and also change
1823the callback model to a model using method callbacks on objects.
1824.PP
1825To use it,
1826.PP
1827.Vb 1
1828\& #include <ev++.h>
1829.Ve
1830.PP
1831(it is not installed by default). This automatically includes \fIev.h\fR
1832and puts all of its definitions (many of them macros) into the global
1833namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace.
1834.PP
1835It should support all the same embedding options as \fIev.h\fR, most notably
1836\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
1837.PP
1838Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
1839.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
1840.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
1841.IX Item "ev::READ, ev::WRITE etc."
1842These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc.
1843macros from \fIev.h\fR.
1844.ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4
1845.el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4
1846.IX Item "ev::tstamp, ev::now"
1847Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix.
1848.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
1849.el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4
1850.IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc."
1851For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of
1852the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR
1853which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
1854defines by many implementations.
1855.Sp
1856All of those classes have these methods:
1857.RS 4
1858.IP "ev::TYPE::TYPE (object *, object::method *)" 4
1859.IX Item "ev::TYPE::TYPE (object *, object::method *)"
1860.PD 0
1861.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4
1862.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)"
1863.IP "ev::TYPE::~TYPE" 4
1864.IX Item "ev::TYPE::~TYPE"
1865.PD
1866The constructor takes a pointer to an object and a method pointer to
1867the event handler callback to call in this class. The constructor calls
1868\&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method
1869before starting it. If you do not specify a loop then the constructor
1870automatically associates the default loop with this watcher.
1871.Sp
1872The destructor automatically stops the watcher if it is active.
1873.IP "w\->set (struct ev_loop *)" 4
1874.IX Item "w->set (struct ev_loop *)"
1875Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
1876do this when the watcher is inactive (and not pending either).
1877.IP "w\->set ([args])" 4
1878.IX Item "w->set ([args])"
1879Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be
1880called at least once. Unlike the C counterpart, an active watcher gets
1881automatically stopped and restarted.
1882.IP "w\->start ()" 4
1883.IX Item "w->start ()"
1884Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the
1885constructor already takes the loop.
1886.IP "w\->stop ()" 4
1887.IX Item "w->stop ()"
1888Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
1889.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4
1890.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4
1891.IX Item "w->again () ev::timer, ev::periodic only"
1892For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding
1893\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function.
1894.ie n .IP "w\->sweep () ""ev::embed"" only" 4
1895.el .IP "w\->sweep () \f(CWev::embed\fR only" 4
1896.IX Item "w->sweep () ev::embed only"
1897Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR.
1898.ie n .IP "w\->update () ""ev::stat"" only" 4
1899.el .IP "w\->update () \f(CWev::stat\fR only" 4
1900.IX Item "w->update () ev::stat only"
1901Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR.
1902.RE
1903.RS 4
1904.RE
1905.PP
1906Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in
1907the constructor.
1908.PP
1909.Vb 4
1910\& class myclass
1911\& {
1912\& ev_io io; void io_cb (ev::io &w, int revents);
1913\& ev_idle idle void idle_cb (ev::idle &w, int revents);
1914.Ve
1915.PP
1916.Vb 2
1917\& myclass ();
1918\& }
1919.Ve
1920.PP
1921.Vb 6
1922\& myclass::myclass (int fd)
1923\& : io (this, &myclass::io_cb),
1924\& idle (this, &myclass::idle_cb)
1925\& {
1926\& io.start (fd, ev::READ);
1927\& }
1928.Ve
1929.SH "MACRO MAGIC"
1930.IX Header "MACRO MAGIC"
1931Libev can be compiled with a variety of options, the most fundemantal is
1932\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines wether (most) functions and
1933callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
1934.PP
1935To make it easier to write programs that cope with either variant, the
1936following macros are defined:
1937.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
1938.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4
1939.IX Item "EV_A, EV_A_"
1940This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev
1941loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument,
1942\&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example:
1943.Sp
1944.Vb 3
1945\& ev_unref (EV_A);
1946\& ev_timer_add (EV_A_ watcher);
1947\& ev_loop (EV_A_ 0);
1948.Ve
1949.Sp
1950It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope,
1951which is often provided by the following macro.
1952.ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4
1953.el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4
1954.IX Item "EV_P, EV_P_"
1955This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev
1956loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter,
1957\&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example:
1958.Sp
1959.Vb 2
1960\& // this is how ev_unref is being declared
1961\& static void ev_unref (EV_P);
1962.Ve
1963.Sp
1964.Vb 2
1965\& // this is how you can declare your typical callback
1966\& static void cb (EV_P_ ev_timer *w, int revents)
1967.Ve
1968.Sp
1969It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite
1970suitable for use with \f(CW\*(C`EV_A\*(C'\fR.
1971.ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4
1972.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
1973.IX Item "EV_DEFAULT, EV_DEFAULT_"
1974Similar to the other two macros, this gives you the value of the default
1975loop, if multiple loops are supported (\*(L"ev loop default\*(R").
1976.PP
1977Example: Declare and initialise a check watcher, working regardless of
1978wether multiple loops are supported or not.
1979.PP
1980.Vb 5
1981\& static void
1982\& check_cb (EV_P_ ev_timer *w, int revents)
1983\& {
1984\& ev_check_stop (EV_A_ w);
1985\& }
1986.Ve
1987.PP
1988.Vb 4
1989\& ev_check check;
1990\& ev_check_init (&check, check_cb);
1991\& ev_check_start (EV_DEFAULT_ &check);
1992\& ev_loop (EV_DEFAULT_ 0);
1993.Ve
1994.SH "EMBEDDING"
1995.IX Header "EMBEDDING"
1996Libev can (and often is) directly embedded into host
1997applications. Examples of applications that embed it include the Deliantra
1998Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe)
1999and rxvt\-unicode.
2000.PP
2001The goal is to enable you to just copy the neecssary files into your
2002source directory without having to change even a single line in them, so
2003you can easily upgrade by simply copying (or having a checked-out copy of
2004libev somewhere in your source tree).
2005.Sh "\s-1FILESETS\s0"
2006.IX Subsection "FILESETS"
2007Depending on what features you need you need to include one or more sets of files
2008in your app.
2009.PP
2010\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR
2011.IX Subsection "CORE EVENT LOOP"
2012.PP
2013To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual
2014configuration (no autoconf):
2015.PP
2016.Vb 2
2017\& #define EV_STANDALONE 1
2018\& #include "ev.c"
2019.Ve
2020.PP
2021This will automatically include \fIev.h\fR, too, and should be done in a
2022single C source file only to provide the function implementations. To use
2023it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best
2024done by writing a wrapper around \fIev.h\fR that you can include instead and
2025where you can put other configuration options):
2026.PP
2027.Vb 2
2028\& #define EV_STANDALONE 1
2029\& #include "ev.h"
2030.Ve
2031.PP
2032Both header files and implementation files can be compiled with a \*(C+
2033compiler (at least, thats a stated goal, and breakage will be treated
2034as a bug).
2035.PP
2036You need the following files in your source tree, or in a directory
2037in your include path (e.g. in libev/ when using \-Ilibev):
2038.PP
2039.Vb 4
2040\& ev.h
2041\& ev.c
2042\& ev_vars.h
2043\& ev_wrap.h
2044.Ve
2045.PP
2046.Vb 1
2047\& ev_win32.c required on win32 platforms only
2048.Ve
2049.PP
2050.Vb 5
2051\& ev_select.c only when select backend is enabled (which is by default)
2052\& ev_poll.c only when poll backend is enabled (disabled by default)
2053\& ev_epoll.c only when the epoll backend is enabled (disabled by default)
2054\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2055\& ev_port.c only when the solaris port backend is enabled (disabled by default)
2056.Ve
2057.PP
2058\&\fIev.c\fR includes the backend files directly when enabled, so you only need
2059to compile this single file.
2060.PP
2061\fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR
2062.IX Subsection "LIBEVENT COMPATIBILITY API"
2063.PP
2064To include the libevent compatibility \s-1API\s0, also include:
2065.PP
2066.Vb 1
2067\& #include "event.c"
2068.Ve
2069.PP
2070in the file including \fIev.c\fR, and:
2071.PP
2072.Vb 1
2073\& #include "event.h"
2074.Ve
2075.PP
2076in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR.
2077.PP
2078You need the following additional files for this:
2079.PP
2080.Vb 2
2081\& event.h
2082\& event.c
2083.Ve
2084.PP
2085\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR
2086.IX Subsection "AUTOCONF SUPPORT"
2087.PP
2088Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in
2089whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your
2090\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then
2091include \fIconfig.h\fR and configure itself accordingly.
2092.PP
2093For this of course you need the m4 file:
2094.PP
2095.Vb 1
2096\& libev.m4
2097.Ve
2098.Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0"
2099.IX Subsection "PREPROCESSOR SYMBOLS/MACROS"
2100Libev can be configured via a variety of preprocessor symbols you have to define
2101before including any of its files. The default is not to build for multiplicity
2102and only include the select backend.
2103.IP "\s-1EV_STANDALONE\s0" 4
2104.IX Item "EV_STANDALONE"
2105Must always be \f(CW1\fR if you do not use autoconf configuration, which
2106keeps libev from including \fIconfig.h\fR, and it also defines dummy
2107implementations for some libevent functions (such as logging, which is not
2108supported). It will also not define any of the structs usually found in
2109\&\fIevent.h\fR that are not directly supported by the libev core alone.
2110.IP "\s-1EV_USE_MONOTONIC\s0" 4
2111.IX Item "EV_USE_MONOTONIC"
2112If defined to be \f(CW1\fR, libev will try to detect the availability of the
2113monotonic clock option at both compiletime and runtime. Otherwise no use
2114of the monotonic clock option will be attempted. If you enable this, you
2115usually have to link against librt or something similar. Enabling it when
2116the functionality isn't available is safe, though, althoguh you have
2117to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR
2118function is hiding in (often \fI\-lrt\fR).
2119.IP "\s-1EV_USE_REALTIME\s0" 4
2120.IX Item "EV_USE_REALTIME"
2121If defined to be \f(CW1\fR, libev will try to detect the availability of the
2122realtime clock option at compiletime (and assume its availability at
2123runtime if successful). Otherwise no use of the realtime clock option will
2124be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get
2125(CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See tzhe note about libraries
2126in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though.
2127.IP "\s-1EV_USE_SELECT\s0" 4
2128.IX Item "EV_USE_SELECT"
2129If undefined or defined to be \f(CW1\fR, libev will compile in support for the
2130\&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no
2131other method takes over, select will be it. Otherwise the select backend
2132will not be compiled in.
2133.IP "\s-1EV_SELECT_USE_FD_SET\s0" 4
2134.IX Item "EV_SELECT_USE_FD_SET"
2135If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR
2136structure. This is useful if libev doesn't compile due to a missing
2137\&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it misguesses the bitset layout on
2138exotic systems. This usually limits the range of file descriptors to some
2139low limit such as 1024 or might have other limitations (winsocket only
2140allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might
2141influence the size of the \f(CW\*(C`fd_set\*(C'\fR used.
2142.IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4
2143.IX Item "EV_SELECT_IS_WINSOCKET"
2144When defined to \f(CW1\fR, the select backend will assume that
2145select/socket/connect etc. don't understand file descriptors but
2146wants osf handles on win32 (this is the case when the select to
2147be used is the winsock select). This means that it will call
2148\&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise,
2149it is assumed that all these functions actually work on fds, even
2150on win32. Should not be defined on non\-win32 platforms.
2151.IP "\s-1EV_USE_POLL\s0" 4
2152.IX Item "EV_USE_POLL"
2153If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2)
2154backend. Otherwise it will be enabled on non\-win32 platforms. It
2155takes precedence over select.
2156.IP "\s-1EV_USE_EPOLL\s0" 4
2157.IX Item "EV_USE_EPOLL"
2158If defined to be \f(CW1\fR, libev will compile in support for the Linux
2159\&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime,
2160otherwise another method will be used as fallback. This is the
2161preferred backend for GNU/Linux systems.
2162.IP "\s-1EV_USE_KQUEUE\s0" 4
2163.IX Item "EV_USE_KQUEUE"
2164If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style
2165\&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime,
2166otherwise another method will be used as fallback. This is the preferred
2167backend for \s-1BSD\s0 and BSD-like systems, although on most BSDs kqueue only
2168supports some types of fds correctly (the only platform we found that
2169supports ptys for example was NetBSD), so kqueue might be compiled in, but
2170not be used unless explicitly requested. The best way to use it is to find
2171out whether kqueue supports your type of fd properly and use an embedded
2172kqueue loop.
2173.IP "\s-1EV_USE_PORT\s0" 4
2174.IX Item "EV_USE_PORT"
2175If defined to be \f(CW1\fR, libev will compile in support for the Solaris
217610 port style backend. Its availability will be detected at runtime,
2177otherwise another method will be used as fallback. This is the preferred
2178backend for Solaris 10 systems.
2179.IP "\s-1EV_USE_DEVPOLL\s0" 4
2180.IX Item "EV_USE_DEVPOLL"
2181reserved for future expansion, works like the \s-1USE\s0 symbols above.
2182.IP "\s-1EV_USE_INOTIFY\s0" 4
2183.IX Item "EV_USE_INOTIFY"
2184If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify
2185interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will
2186be detected at runtime.
2187.IP "\s-1EV_H\s0" 4
2188.IX Item "EV_H"
2189The name of the \fIev.h\fR header file used to include it. The default if
2190undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This
2191can be used to virtually rename the \fIev.h\fR header file in case of conflicts.
2192.IP "\s-1EV_CONFIG_H\s0" 4
2193.IX Item "EV_CONFIG_H"
2194If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override
2195\&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to
2196\&\f(CW\*(C`EV_H\*(C'\fR, above.
2197.IP "\s-1EV_EVENT_H\s0" 4
2198.IX Item "EV_EVENT_H"
2199Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea
2200of how the \fIevent.h\fR header can be found.
2201.IP "\s-1EV_PROTOTYPES\s0" 4
2202.IX Item "EV_PROTOTYPES"
2203If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function
2204prototypes, but still define all the structs and other symbols. This is
2205occasionally useful if you want to provide your own wrapper functions
2206around libev functions.
2207.IP "\s-1EV_MULTIPLICITY\s0" 4
2208.IX Item "EV_MULTIPLICITY"
2209If undefined or defined to \f(CW1\fR, then all event-loop-specific functions
2210will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create
2211additional independent event loops. Otherwise there will be no support
2212for multiple event loops and there is no first event loop pointer
2213argument. Instead, all functions act on the single default loop.
2214.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
2215.IX Item "EV_PERIODIC_ENABLE"
2216If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
2217defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2218code.
2219.IP "\s-1EV_EMBED_ENABLE\s0" 4
2220.IX Item "EV_EMBED_ENABLE"
2221If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If
2222defined to be \f(CW0\fR, then they are not.
2223.IP "\s-1EV_STAT_ENABLE\s0" 4
2224.IX Item "EV_STAT_ENABLE"
2225If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If
2226defined to be \f(CW0\fR, then they are not.
2227.IP "\s-1EV_FORK_ENABLE\s0" 4
2228.IX Item "EV_FORK_ENABLE"
2229If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If
2230defined to be \f(CW0\fR, then they are not.
2231.IP "\s-1EV_MINIMAL\s0" 4
2232.IX Item "EV_MINIMAL"
2233If you need to shave off some kilobytes of code at the expense of some
2234speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override
2235some inlining decisions, saves roughly 30% codesize of amd64.
2236.IP "\s-1EV_PID_HASHSIZE\s0" 4
2237.IX Item "EV_PID_HASHSIZE"
2238\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by
2239pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more
2240than enough. If you need to manage thousands of children you might want to
2241increase this value (\fImust\fR be a power of two).
2242.IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4
2243.IX Item "EV_INOTIFY_HASHSIZE"
2244\&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by
2245inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR),
2246usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR
2247watchers you might want to increase this value (\fImust\fR be a power of
2248two).
2249.IP "\s-1EV_COMMON\s0" 4
2250.IX Item "EV_COMMON"
2251By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
2252this macro to a something else you can include more and other types of
2253members. You have to define it each time you include one of the files,
2254though, and it must be identical each time.
2255.Sp
2256For example, the perl \s-1EV\s0 module uses something like this:
2257.Sp
2258.Vb 3
2259\& #define EV_COMMON \e
2260\& SV *self; /* contains this struct */ \e
2261\& SV *cb_sv, *fh /* note no trailing ";" */
2262.Ve
2263.IP "\s-1EV_CB_DECLARE\s0 (type)" 4
2264.IX Item "EV_CB_DECLARE (type)"
2265.PD 0
2266.IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4
2267.IX Item "EV_CB_INVOKE (watcher, revents)"
2268.IP "ev_set_cb (ev, cb)" 4
2269.IX Item "ev_set_cb (ev, cb)"
2270.PD
2271Can be used to change the callback member declaration in each watcher,
2272and the way callbacks are invoked and set. Must expand to a struct member
2273definition and a statement, respectively. See the \fIev.v\fR header file for
2274their default definitions. One possible use for overriding these is to
2275avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
2276method calls instead of plain function calls in \*(C+.
2277.Sh "\s-1EXAMPLES\s0"
2278.IX Subsection "EXAMPLES"
2279For a real-world example of a program the includes libev
2280verbatim, you can have a look at the \s-1EV\s0 perl module
2281(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in
2282the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public
2283interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file
2284will be compiled. It is pretty complex because it provides its own header
2285file.
2286.Sp
2287The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
2288that everybody includes and which overrides some autoconf choices:
2289.Sp
2290.Vb 4
2291\& #define EV_USE_POLL 0
2292\& #define EV_MULTIPLICITY 0
2293\& #define EV_PERIODICS 0
2294\& #define EV_CONFIG_H <config.h>
2295.Ve
2296.Sp
2297.Vb 1
2298\& #include "ev++.h"
2299.Ve
2300.Sp
2301And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled:
2302.Sp
2303.Vb 2
2304\& #include "ev_cpp.h"
2305\& #include "ev.c"
2306.Ve
2307.SH "COMPLEXITIES"
2308.IX Header "COMPLEXITIES"
2309In this section the complexities of (many of) the algorithms used inside
2310libev will be explained. For complexity discussions about backends see the
2311documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
2312.RS 4
2313.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
2314.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
2315.PD 0
2316.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
2317.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2318.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
2319.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2320.IP "Stopping check/prepare/idle watchers: O(1)" 4
2321.IX Item "Stopping check/prepare/idle watchers: O(1)"
2322.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
2323.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
2324.IP "Finding the next timer per loop iteration: O(1)" 4
2325.IX Item "Finding the next timer per loop iteration: O(1)"
2326.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
2327.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
2328.IP "Activating one watcher: O(1)" 4
2329.IX Item "Activating one watcher: O(1)"
2330.RE
2331.RS 4
2332.PD
958.SH "AUTHOR" 2333.SH "AUTHOR"
959.IX Header "AUTHOR" 2334.IX Header "AUTHOR"
960Marc Lehmann <libev@schmorp.de>. 2335Marc Lehmann <libev@schmorp.de>.

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