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Revision 1.6 by root, Fri Nov 23 05:14:58 2007 UTC vs.
Revision 1.21 by root, Mon Nov 26 10:20:42 2007 UTC

… …
127.\} 127.\}
128.rm #[ #] #H #V #F C 128.rm #[ #] #H #V #F C
129.\" ======================================================================== 129.\" ========================================================================
130.\" 130.\"
131.IX Title ""<STANDARD INPUT>" 1" 131.IX Title ""<STANDARD INPUT>" 1"
132.TH "<STANDARD INPUT>" 1 "2007-11-23" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH "<STANDARD INPUT>" 1 "2007-11-26" "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
… …
173.IX Header "TIME REPRESENTATION" 173.IX Header "TIME REPRESENTATION"
174Libev represents time as a single floating point number, representing the 174Libev represents time as a single floating point number, representing the
175(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near 175(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 176the 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 177called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases
178to the double type in C. 178to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on
179it, you should treat it as such.
179.SH "GLOBAL FUNCTIONS" 180.SH "GLOBAL FUNCTIONS"
180.IX Header "GLOBAL FUNCTIONS" 181.IX Header "GLOBAL FUNCTIONS"
181These functions can be called anytime, even before initialising the 182These functions can be called anytime, even before initialising the
182library in any way. 183library in any way.
183.IP "ev_tstamp ev_time ()" 4 184.IP "ev_tstamp ev_time ()" 4
… …
199.Sp 200.Sp
200Usually, it's a good idea to terminate if the major versions mismatch, 201Usually, it's a good idea to terminate if the major versions mismatch,
201as this indicates an incompatible change. Minor versions are usually 202as this indicates an incompatible change. Minor versions are usually
202compatible to older versions, so a larger minor version alone is usually 203compatible to older versions, so a larger minor version alone is usually
203not a problem. 204not a problem.
205.Sp
206Example: make sure we haven't accidentally been linked against the wrong
207version:
208.Sp
209.Vb 3
210\& assert (("libev version mismatch",
211\& ev_version_major () == EV_VERSION_MAJOR
212\& && ev_version_minor () >= EV_VERSION_MINOR));
213.Ve
204.IP "unsigned int ev_supported_backends ()" 4 214.IP "unsigned int ev_supported_backends ()" 4
205.IX Item "unsigned int ev_supported_backends ()" 215.IX Item "unsigned int ev_supported_backends ()"
206Return the set of all backends (i.e. their corresponding \f(CW\*(C`EV_BACKEND_*\*(C'\fR 216Return the set of all backends (i.e. their corresponding \f(CW\*(C`EV_BACKEND_*\*(C'\fR
207value) compiled into this binary of libev (independent of their 217value) compiled into this binary of libev (independent of their
208availability on the system you are running on). See \f(CW\*(C`ev_default_loop\*(C'\fR for 218availability on the system you are running on). See \f(CW\*(C`ev_default_loop\*(C'\fR for
209a description of the set values. 219a description of the set values.
220.Sp
221Example: make sure we have the epoll method, because yeah this is cool and
222a must have and can we have a torrent of it please!!!11
223.Sp
224.Vb 2
225\& assert (("sorry, no epoll, no sex",
226\& ev_supported_backends () & EVBACKEND_EPOLL));
227.Ve
210.IP "unsigned int ev_recommended_backends ()" 4 228.IP "unsigned int ev_recommended_backends ()" 4
211.IX Item "unsigned int ev_recommended_backends ()" 229.IX Item "unsigned int ev_recommended_backends ()"
212Return the set of all backends compiled into this binary of libev and also 230Return the set of all backends compiled into this binary of libev and also
213recommended for this platform. This set is often smaller than the one 231recommended for this platform. This set is often smaller than the one
214returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on 232returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on
215most BSDs and will not be autodetected unless you explicitly request it 233most BSDs and will not be autodetected unless you explicitly request it
216(assuming you know what you are doing). This is the set of backends that 234(assuming you know what you are doing). This is the set of backends that
217\&\f(CW\*(C`EVFLAG_AUTO\*(C'\fR will probe for. 235libev will probe for if you specify no backends explicitly.
236.IP "unsigned int ev_embeddable_backends ()" 4
237.IX Item "unsigned int ev_embeddable_backends ()"
238Returns the set of backends that are embeddable in other event loops. This
239is the theoretical, all\-platform, value. To find which backends
240might be supported on the current system, you would need to look at
241\&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for
242recommended ones.
243.Sp
244See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.
218.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 245.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4
219.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" 246.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"
220Sets the allocation function to use (the prototype is similar to the 247Sets the allocation function to use (the prototype is similar to the
221realloc C function, the semantics are identical). It is used to allocate 248realloc C function, the semantics are identical). It is used to allocate
222and free memory (no surprises here). If it returns zero when memory 249and free memory (no surprises here). If it returns zero when memory
… …
224destructive action. The default is your system realloc function. 251destructive action. The default is your system realloc function.
225.Sp 252.Sp
226You could override this function in high-availability programs to, say, 253You could override this function in high-availability programs to, say,
227free some memory if it cannot allocate memory, to use a special allocator, 254free some memory if it cannot allocate memory, to use a special allocator,
228or even to sleep a while and retry until some memory is available. 255or even to sleep a while and retry until some memory is available.
256.Sp
257Example: replace the libev allocator with one that waits a bit and then
258retries: better than mine).
259.Sp
260.Vb 6
261\& static void *
262\& persistent_realloc (void *ptr, long size)
263\& {
264\& for (;;)
265\& {
266\& void *newptr = realloc (ptr, size);
267.Ve
268.Sp
269.Vb 2
270\& if (newptr)
271\& return newptr;
272.Ve
273.Sp
274.Vb 3
275\& sleep (60);
276\& }
277\& }
278.Ve
279.Sp
280.Vb 2
281\& ...
282\& ev_set_allocator (persistent_realloc);
283.Ve
229.IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 284.IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4
230.IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" 285.IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));"
231Set the callback function to call on a retryable syscall error (such 286Set the callback function to call on a retryable syscall error (such
232as failed select, poll, epoll_wait). The message is a printable string 287as failed select, poll, epoll_wait). The message is a printable string
233indicating the system call or subsystem causing the problem. If this 288indicating the system call or subsystem causing the problem. If this
234callback is set, then libev will expect it to remedy the sitution, no 289callback is set, then libev will expect it to remedy the sitution, no
235matter what, when it returns. That is, libev will generally retry the 290matter what, when it returns. That is, libev will generally retry the
236requested operation, or, if the condition doesn't go away, do bad stuff 291requested operation, or, if the condition doesn't go away, do bad stuff
237(such as abort). 292(such as abort).
293.Sp
294Example: do the same thing as libev does internally:
295.Sp
296.Vb 6
297\& static void
298\& fatal_error (const char *msg)
299\& {
300\& perror (msg);
301\& abort ();
302\& }
303.Ve
304.Sp
305.Vb 2
306\& ...
307\& ev_set_syserr_cb (fatal_error);
308.Ve
238.SH "FUNCTIONS CONTROLLING THE EVENT LOOP" 309.SH "FUNCTIONS CONTROLLING THE EVENT LOOP"
239.IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" 310.IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP"
240An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR. The library knows two 311An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR. The library knows two
241types of such loops, the \fIdefault\fR loop, which supports signals and child 312types of such loops, the \fIdefault\fR loop, which supports signals and child
242events, and dynamically created loops which do not. 313events, and dynamically created loops which do not.
… …
256.Sp 327.Sp
257If you don't know what event loop to use, use the one returned from this 328If you don't know what event loop to use, use the one returned from this
258function. 329function.
259.Sp 330.Sp
260The flags argument can be used to specify special behaviour or specific 331The flags argument can be used to specify special behaviour or specific
261backends to use, and is usually specified as \f(CW0\fR (or \s-1EVFLAG_AUTO\s0). 332backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR).
262.Sp 333.Sp
263It supports the following flags: 334The following flags are supported:
264.RS 4 335.RS 4
265.ie n .IP """EVFLAG_AUTO""" 4 336.ie n .IP """EVFLAG_AUTO""" 4
266.el .IP "\f(CWEVFLAG_AUTO\fR" 4 337.el .IP "\f(CWEVFLAG_AUTO\fR" 4
267.IX Item "EVFLAG_AUTO" 338.IX Item "EVFLAG_AUTO"
268The default flags value. Use this if you have no clue (it's the right 339The default flags value. Use this if you have no clue (it's the right
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302While stopping and starting an I/O watcher in the same iteration will 373While stopping and starting an I/O watcher in the same iteration will
303result in some caching, there is still a syscall per such incident 374result in some caching, there is still a syscall per such incident
304(because the fd could point to a different file description now), so its 375(because the fd could point to a different file description now), so its
305best to avoid that. Also, \fIdup()\fRed file descriptors might not work very 376best to avoid that. Also, \fIdup()\fRed file descriptors might not work very
306well if you register events for both fds. 377well if you register events for both fds.
378.Sp
379Please note that epoll sometimes generates spurious notifications, so you
380need to use non-blocking I/O or other means to avoid blocking when no data
381(or space) is available.
307.ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 382.ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4
308.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 383.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4
309.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" 384.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"
310Kqueue deserves special mention, as at the time of this writing, it 385Kqueue deserves special mention, as at the time of this writing, it
311was broken on all BSDs except NetBSD (usually it doesn't work with 386was broken on all BSDs except NetBSD (usually it doesn't work with
312anything but sockets and pipes, except on Darwin, where of course its 387anything but sockets and pipes, except on Darwin, where of course its
313completely useless). For this reason its not being \*(L"autodetected\*(R" unless 388completely useless). For this reason its not being \*(L"autodetected\*(R"
314you explicitly specify the flags (i.e. you don't use \s-1EVFLAG_AUTO\s0). 389unless you explicitly specify it explicitly in the flags (i.e. using
390\&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR).
315.Sp 391.Sp
316It scales in the same way as the epoll backend, but the interface to the 392It scales in the same way as the epoll backend, but the interface to the
317kernel is more efficient (which says nothing about its actual speed, of 393kernel is more efficient (which says nothing about its actual speed, of
318course). While starting and stopping an I/O watcher does not cause an 394course). While starting and stopping an I/O watcher does not cause an
319extra syscall as with epoll, it still adds up to four event changes per 395extra syscall as with epoll, it still adds up to four event changes per
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325.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 401.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4
326.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 402.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4
327.IX Item "EVBACKEND_PORT (value 32, Solaris 10)" 403.IX Item "EVBACKEND_PORT (value 32, Solaris 10)"
328This uses the Solaris 10 port mechanism. As with everything on Solaris, 404This uses the Solaris 10 port mechanism. As with everything on Solaris,
329it's really slow, but it still scales very well (O(active_fds)). 405it's really slow, but it still scales very well (O(active_fds)).
406.Sp
407Please note that solaris ports can result in a lot of spurious
408notifications, so you need to use non-blocking I/O or other means to avoid
409blocking when no data (or space) is available.
330.ie n .IP """EVBACKEND_ALL""" 4 410.ie n .IP """EVBACKEND_ALL""" 4
331.el .IP "\f(CWEVBACKEND_ALL\fR" 4 411.el .IP "\f(CWEVBACKEND_ALL\fR" 4
332.IX Item "EVBACKEND_ALL" 412.IX Item "EVBACKEND_ALL"
333Try all backends (even potentially broken ones that wouldn't be tried 413Try all backends (even potentially broken ones that wouldn't be tried
334with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as 414with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as
… …
338.Sp 418.Sp
339If one or more of these are ored into the flags value, then only these 419If one or more of these are ored into the flags value, then only these
340backends will be tried (in the reverse order as given here). If none are 420backends will be tried (in the reverse order as given here). If none are
341specified, most compiled-in backend will be tried, usually in reverse 421specified, most compiled-in backend will be tried, usually in reverse
342order of their flag values :) 422order of their flag values :)
423.Sp
424The most typical usage is like this:
425.Sp
426.Vb 2
427\& if (!ev_default_loop (0))
428\& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
429.Ve
430.Sp
431Restrict libev to the select and poll backends, and do not allow
432environment settings to be taken into account:
433.Sp
434.Vb 1
435\& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
436.Ve
437.Sp
438Use whatever libev has to offer, but make sure that kqueue is used if
439available (warning, breaks stuff, best use only with your own private
440event loop and only if you know the \s-1OS\s0 supports your types of fds):
441.Sp
442.Vb 1
443\& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
444.Ve
343.RE 445.RE
344.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 446.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4
345.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" 447.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)"
346Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is 448Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is
347always distinct from the default loop. Unlike the default loop, it cannot 449always distinct from the default loop. Unlike the default loop, it cannot
348handle signal and child watchers, and attempts to do so will be greeted by 450handle signal and child watchers, and attempts to do so will be greeted by
349undefined behaviour (or a failed assertion if assertions are enabled). 451undefined behaviour (or a failed assertion if assertions are enabled).
452.Sp
453Example: try to create a event loop that uses epoll and nothing else.
454.Sp
455.Vb 3
456\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
457\& if (!epoller)
458\& fatal ("no epoll found here, maybe it hides under your chair");
459.Ve
350.IP "ev_default_destroy ()" 4 460.IP "ev_default_destroy ()" 4
351.IX Item "ev_default_destroy ()" 461.IX Item "ev_default_destroy ()"
352Destroys the default loop again (frees all memory and kernel state 462Destroys the default loop again (frees all memory and kernel state
353etc.). This stops all registered event watchers (by not touching them in 463etc.). None of the active event watchers will be stopped in the normal
354any way whatsoever, although you cannot rely on this :). 464sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your
465responsibility to either stop all watchers cleanly yoursef \fIbefore\fR
466calling this function, or cope with the fact afterwards (which is usually
467the easiest thing, youc na just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them
468for example).
355.IP "ev_loop_destroy (loop)" 4 469.IP "ev_loop_destroy (loop)" 4
356.IX Item "ev_loop_destroy (loop)" 470.IX Item "ev_loop_destroy (loop)"
357Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an 471Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an
358earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. 472earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR.
359.IP "ev_default_fork ()" 4 473.IP "ev_default_fork ()" 4
… …
388Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in 502Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
389use. 503use.
390.IP "ev_tstamp ev_now (loop)" 4 504.IP "ev_tstamp ev_now (loop)" 4
391.IX Item "ev_tstamp ev_now (loop)" 505.IX Item "ev_tstamp ev_now (loop)"
392Returns the current \*(L"event loop time\*(R", which is the time the event loop 506Returns the current \*(L"event loop time\*(R", which is the time the event loop
393got events and started processing them. This timestamp does not change 507received events and started processing them. This timestamp does not
394as long as callbacks are being processed, and this is also the base time 508change as long as callbacks are being processed, and this is also the base
395used for relative timers. You can treat it as the timestamp of the event 509time used for relative timers. You can treat it as the timestamp of the
396occuring (or more correctly, the mainloop finding out about it). 510event occuring (or more correctly, libev finding out about it).
397.IP "ev_loop (loop, int flags)" 4 511.IP "ev_loop (loop, int flags)" 4
398.IX Item "ev_loop (loop, int flags)" 512.IX Item "ev_loop (loop, int flags)"
399Finally, this is it, the event handler. This function usually is called 513Finally, this is it, the event handler. This function usually is called
400after you initialised all your watchers and you want to start handling 514after you initialised all your watchers and you want to start handling
401events. 515events.
402.Sp 516.Sp
403If the flags argument is specified as 0, it will not return until either 517If the flags argument is specified as \f(CW0\fR, it will not return until
404no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. 518either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called.
519.Sp
520Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than
521relying on all watchers to be stopped when deciding when a program has
522finished (especially in interactive programs), but having a program that
523automatically loops as long as it has to and no longer by virtue of
524relying on its watchers stopping correctly is a thing of beauty.
405.Sp 525.Sp
406A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle 526A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle
407those events and any outstanding ones, but will not block your process in 527those events and any outstanding ones, but will not block your process in
408case there are no events and will return after one iteration of the loop. 528case there are no events and will return after one iteration of the loop.
409.Sp 529.Sp
410A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if 530A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if
411neccessary) and will handle those and any outstanding ones. It will block 531neccessary) and will handle those and any outstanding ones. It will block
412your process until at least one new event arrives, and will return after 532your process until at least one new event arrives, and will return after
413one iteration of the loop. 533one iteration of the loop. This is useful if you are waiting for some
534external event in conjunction with something not expressible using other
535libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is
536usually a better approach for this kind of thing.
414.Sp 537.Sp
415This flags value could be used to implement alternative looping
416constructs, but the \f(CW\*(C`prepare\*(C'\fR and \f(CW\*(C`check\*(C'\fR watchers provide a better and
417more generic mechanism.
418.Sp
419Here are the gory details of what ev_loop does: 538Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does:
420.Sp 539.Sp
421.Vb 15 540.Vb 18
422\& 1. If there are no active watchers (reference count is zero), return. 541\& * If there are no active watchers (reference count is zero), return.
423\& 2. Queue and immediately call all prepare watchers. 542\& - Queue prepare watchers and then call all outstanding watchers.
424\& 3. If we have been forked, recreate the kernel state. 543\& - If we have been forked, recreate the kernel state.
425\& 4. Update the kernel state with all outstanding changes. 544\& - Update the kernel state with all outstanding changes.
426\& 5. Update the "event loop time". 545\& - Update the "event loop time".
427\& 6. Calculate for how long to block. 546\& - Calculate for how long to block.
428\& 7. Block the process, waiting for events. 547\& - Block the process, waiting for any events.
548\& - Queue all outstanding I/O (fd) events.
429\& 8. Update the "event loop time" and do time jump handling. 549\& - Update the "event loop time" and do time jump handling.
430\& 9. Queue all outstanding timers. 550\& - Queue all outstanding timers.
431\& 10. Queue all outstanding periodics. 551\& - Queue all outstanding periodics.
432\& 11. If no events are pending now, queue all idle watchers. 552\& - If no events are pending now, queue all idle watchers.
433\& 12. Queue all check watchers. 553\& - Queue all check watchers.
434\& 13. Call all queued watchers in reverse order (i.e. check watchers first). 554\& - Call all queued watchers in reverse order (i.e. check watchers first).
555\& Signals and child watchers are implemented as I/O watchers, and will
556\& be handled here by queueing them when their watcher gets executed.
435\& 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK 557\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
436\& was used, return, otherwise continue with step #1. 558\& were used, return, otherwise continue with step *.
559.Ve
560.Sp
561Example: queue some jobs and then loop until no events are outsanding
562anymore.
563.Sp
564.Vb 4
565\& ... queue jobs here, make sure they register event watchers as long
566\& ... as they still have work to do (even an idle watcher will do..)
567\& ev_loop (my_loop, 0);
568\& ... jobs done. yeah!
437.Ve 569.Ve
438.IP "ev_unloop (loop, how)" 4 570.IP "ev_unloop (loop, how)" 4
439.IX Item "ev_unloop (loop, how)" 571.IX Item "ev_unloop (loop, how)"
440Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it 572Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it
441has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either 573has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either
… …
455example, libev itself uses this for its internal signal pipe: It is not 587example, libev itself uses this for its internal signal pipe: It is not
456visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if 588visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if
457no event watchers registered by it are active. It is also an excellent 589no event watchers registered by it are active. It is also an excellent
458way to do this for generic recurring timers or from within third-party 590way to do this for generic recurring timers or from within third-party
459libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR. 591libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.
592.Sp
593Example: create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR
594running when nothing else is active.
595.Sp
596.Vb 4
597\& struct dv_signal exitsig;
598\& ev_signal_init (&exitsig, sig_cb, SIGINT);
599\& ev_signal_start (myloop, &exitsig);
600\& evf_unref (myloop);
601.Ve
602.Sp
603Example: for some weird reason, unregister the above signal handler again.
604.Sp
605.Vb 2
606\& ev_ref (myloop);
607\& ev_signal_stop (myloop, &exitsig);
608.Ve
460.SH "ANATOMY OF A WATCHER" 609.SH "ANATOMY OF A WATCHER"
461.IX Header "ANATOMY OF A WATCHER" 610.IX Header "ANATOMY OF A WATCHER"
462A watcher is a structure that you create and register to record your 611A watcher is a structure that you create and register to record your
463interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to 612interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to
464become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: 613become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that:
… …
500*)\*(C'\fR), and you can stop watching for events at any time by calling the 649*)\*(C'\fR), and you can stop watching for events at any time by calling the
501corresponding stop function (\f(CW\*(C`ev_<type>_stop (loop, watcher *)\*(C'\fR. 650corresponding stop function (\f(CW\*(C`ev_<type>_stop (loop, watcher *)\*(C'\fR.
502.PP 651.PP
503As long as your watcher is active (has been started but not stopped) you 652As long as your watcher is active (has been started but not stopped) you
504must not touch the values stored in it. Most specifically you must never 653must not touch the values stored in it. Most specifically you must never
505reinitialise it or call its set macro. 654reinitialise it or call its \f(CW\*(C`set\*(C'\fR macro.
506.PP
507You can check whether an event is active by calling the \f(CW\*(C`ev_is_active
508(watcher *)\*(C'\fR macro. To see whether an event is outstanding (but the
509callback for it has not been called yet) you can use the \f(CW\*(C`ev_is_pending
510(watcher *)\*(C'\fR macro.
511.PP 655.PP
512Each and every callback receives the event loop pointer as first, the 656Each and every callback receives the event loop pointer as first, the
513registered watcher structure as second, and a bitset of received events as 657registered watcher structure as second, and a bitset of received events as
514third argument. 658third argument.
515.PP 659.PP
… …
573Libev will usually signal a few \*(L"dummy\*(R" events together with an error, 717Libev will usually signal a few \*(L"dummy\*(R" events together with an error,
574for example it might indicate that a fd is readable or writable, and if 718for example it might indicate that a fd is readable or writable, and if
575your callbacks is well-written it can just attempt the operation and cope 719your callbacks is well-written it can just attempt the operation and cope
576with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded 720with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded
577programs, though, so beware. 721programs, though, so beware.
722.Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0"
723.IX Subsection "GENERIC WATCHER FUNCTIONS"
724In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type,
725e.g. \f(CW\*(C`timer\*(C'\fR for \f(CW\*(C`ev_timer\*(C'\fR watchers and \f(CW\*(C`io\*(C'\fR for \f(CW\*(C`ev_io\*(C'\fR watchers.
726.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4
727.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4
728.IX Item "ev_init (ev_TYPE *watcher, callback)"
729This macro initialises the generic portion of a watcher. The contents
730of the watcher object can be arbitrary (so \f(CW\*(C`malloc\*(C'\fR will do). Only
731the generic parts of the watcher are initialised, you \fIneed\fR to call
732the type-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR macro afterwards to initialise the
733type-specific parts. For each type there is also a \f(CW\*(C`ev_TYPE_init\*(C'\fR macro
734which rolls both calls into one.
735.Sp
736You can reinitialise a watcher at any time as long as it has been stopped
737(or never started) and there are no pending events outstanding.
738.Sp
739The callback is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher,
740int revents)\*(C'\fR.
741.ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4
742.el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4
743.IX Item "ev_TYPE_set (ev_TYPE *, [args])"
744This macro initialises the type-specific parts of a watcher. You need to
745call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can
746call \f(CW\*(C`ev_TYPE_set\*(C'\fR any number of times. You must not, however, call this
747macro on a watcher that is active (it can be pending, however, which is a
748difference to the \f(CW\*(C`ev_init\*(C'\fR macro).
749.Sp
750Although some watcher types do not have type-specific arguments
751(e.g. \f(CW\*(C`ev_prepare\*(C'\fR) you still need to call its \f(CW\*(C`set\*(C'\fR macro.
752.ie n .IP """ev_TYPE_init"" (ev_TYPE *watcher, callback, [args])" 4
753.el .IP "\f(CWev_TYPE_init\fR (ev_TYPE *watcher, callback, [args])" 4
754.IX Item "ev_TYPE_init (ev_TYPE *watcher, callback, [args])"
755This convinience macro rolls both \f(CW\*(C`ev_init\*(C'\fR and \f(CW\*(C`ev_TYPE_set\*(C'\fR macro
756calls into a single call. This is the most convinient method to initialise
757a watcher. The same limitations apply, of course.
758.ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4
759.el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4
760.IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)"
761Starts (activates) the given watcher. Only active watchers will receive
762events. If the watcher is already active nothing will happen.
763.ie n .IP """ev_TYPE_stop"" (loop *, ev_TYPE *watcher)" 4
764.el .IP "\f(CWev_TYPE_stop\fR (loop *, ev_TYPE *watcher)" 4
765.IX Item "ev_TYPE_stop (loop *, ev_TYPE *watcher)"
766Stops the given watcher again (if active) and clears the pending
767status. It is possible that stopped watchers are pending (for example,
768non-repeating timers are being stopped when they become pending), but
769\&\f(CW\*(C`ev_TYPE_stop\*(C'\fR ensures that the watcher is neither active nor pending. If
770you want to free or reuse the memory used by the watcher it is therefore a
771good idea to always call its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function.
772.IP "bool ev_is_active (ev_TYPE *watcher)" 4
773.IX Item "bool ev_is_active (ev_TYPE *watcher)"
774Returns a true value iff the watcher is active (i.e. it has been started
775and not yet been stopped). As long as a watcher is active you must not modify
776it.
777.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
778.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
779Returns a true value iff the watcher is pending, (i.e. it has outstanding
780events but its callback has not yet been invoked). As long as a watcher
781is pending (but not active) you must not call an init function on it (but
782\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to
783libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it).
784.IP "callback = ev_cb (ev_TYPE *watcher)" 4
785.IX Item "callback = ev_cb (ev_TYPE *watcher)"
786Returns the callback currently set on the watcher.
787.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
788.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
789Change the callback. You can change the callback at virtually any time
790(modulo threads).
578.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 791.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
579.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 792.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
580Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change 793Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change
581and read at any time, libev will completely ignore it. This can be used 794and read at any time, libev will completely ignore it. This can be used
582to associate arbitrary data with your watcher. If you need more data and 795to associate arbitrary data with your watcher. If you need more data and
… …
609have been omitted.... 822have been omitted....
610.SH "WATCHER TYPES" 823.SH "WATCHER TYPES"
611.IX Header "WATCHER TYPES" 824.IX Header "WATCHER TYPES"
612This section describes each watcher in detail, but will not repeat 825This section describes each watcher in detail, but will not repeat
613information given in the last section. 826information given in the last section.
614.ie n .Sh """ev_io"" \- is this file descriptor readable or writable" 827.ie n .Sh """ev_io"" \- is this file descriptor readable or writable?"
615.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable" 828.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?"
616.IX Subsection "ev_io - is this file descriptor readable or writable" 829.IX Subsection "ev_io - is this file descriptor readable or writable?"
617I/O watchers check whether a file descriptor is readable or writable 830I/O watchers check whether a file descriptor is readable or writable
618in each iteration of the event loop (This behaviour is called 831in each iteration of the event loop, or, more precisely, when reading
619level-triggering because you keep receiving events as long as the 832would not block the process and writing would at least be able to write
620condition persists. Remember you can stop the watcher if you don't want to 833some data. This behaviour is called level-triggering because you keep
621act on the event and neither want to receive future events). 834receiving events as long as the condition persists. Remember you can stop
835the watcher if you don't want to act on the event and neither want to
836receive future events.
622.PP 837.PP
623In general you can register as many read and/or write event watchers per 838In general you can register as many read and/or write event watchers per
624fd as you want (as long as you don't confuse yourself). Setting all file 839fd as you want (as long as you don't confuse yourself). Setting all file
625descriptors to non-blocking mode is also usually a good idea (but not 840descriptors to non-blocking mode is also usually a good idea (but not
626required if you know what you are doing). 841required if you know what you are doing).
627.PP 842.PP
628You have to be careful with dup'ed file descriptors, though. Some backends 843You have to be careful with dup'ed file descriptors, though. Some backends
629(the linux epoll backend is a notable example) cannot handle dup'ed file 844(the linux epoll backend is a notable example) cannot handle dup'ed file
630descriptors correctly if you register interest in two or more fds pointing 845descriptors correctly if you register interest in two or more fds pointing
631to the same underlying file/socket etc. description (that is, they share 846to the same underlying file/socket/etc. description (that is, they share
632the same underlying \*(L"file open\*(R"). 847the same underlying \*(L"file open\*(R").
633.PP 848.PP
634If you must do this, then force the use of a known-to-be-good backend 849If you must do this, then force the use of a known-to-be-good backend
635(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and 850(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and
636\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). 851\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR).
852.PP
853Another thing you have to watch out for is that it is quite easy to
854receive \*(L"spurious\*(R" readyness notifications, that is your callback might
855be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block
856because there is no data. Not only are some backends known to create a
857lot of those (for example solaris ports), it is very easy to get into
858this situation even with a relatively standard program structure. Thus
859it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning
860\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
861.PP
862If you cannot run the fd in non-blocking mode (for example you should not
863play around with an Xlib connection), then you have to seperately re-test
864wether a file descriptor is really ready with a known-to-be good interface
865such as poll (fortunately in our Xlib example, Xlib already does this on
866its own, so its quite safe to use).
637.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 867.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
638.IX Item "ev_io_init (ev_io *, callback, int fd, int events)" 868.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
639.PD 0 869.PD 0
640.IP "ev_io_set (ev_io *, int fd, int events)" 4 870.IP "ev_io_set (ev_io *, int fd, int events)" 4
641.IX Item "ev_io_set (ev_io *, int fd, int events)" 871.IX Item "ev_io_set (ev_io *, int fd, int events)"
642.PD 872.PD
643Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The fd is the file descriptor to rceeive 873Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to
644events 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 | 874rceeive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or
645EV_WRITE\*(C'\fR to receive the given events. 875\&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events.
876.PP
877Example: call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well
878readable, but only once. Since it is likely line\-buffered, you could
879attempt to read a whole line in the callback:
880.PP
881.Vb 6
882\& static void
883\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
884\& {
885\& ev_io_stop (loop, w);
886\& .. read from stdin here (or from w->fd) and haqndle any I/O errors
887\& }
888.Ve
889.PP
890.Vb 6
891\& ...
892\& struct ev_loop *loop = ev_default_init (0);
893\& struct ev_io stdin_readable;
894\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
895\& ev_io_start (loop, &stdin_readable);
896\& ev_loop (loop, 0);
897.Ve
646.ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts" 898.ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts"
647.el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts" 899.el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts"
648.IX Subsection "ev_timer - relative and optionally recurring timeouts" 900.IX Subsection "ev_timer - relative and optionally repeating timeouts"
649Timer watchers are simple relative timers that generate an event after a 901Timer watchers are simple relative timers that generate an event after a
650given time, and optionally repeating in regular intervals after that. 902given time, and optionally repeating in regular intervals after that.
651.PP 903.PP
652The timers are based on real time, that is, if you register an event that 904The timers are based on real time, that is, if you register an event that
653times out after an hour and you reset your system clock to last years 905times out after an hour and you reset your system clock to last years
… …
700seconds of inactivity on the socket. The easiest way to do this is to 952seconds of inactivity on the socket. The easiest way to do this is to
701configure an \f(CW\*(C`ev_timer\*(C'\fR with after=repeat=60 and calling ev_timer_again each 953configure an \f(CW\*(C`ev_timer\*(C'\fR with after=repeat=60 and calling ev_timer_again each
702time you successfully read or write some data. If you go into an idle 954time you successfully read or write some data. If you go into an idle
703state where you do not expect data to travel on the socket, you can stop 955state where you do not expect data to travel on the socket, you can stop
704the timer, and again will automatically restart it if need be. 956the timer, and again will automatically restart it if need be.
957.PP
958Example: create a timer that fires after 60 seconds.
959.PP
960.Vb 5
961\& static void
962\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
963\& {
964\& .. one minute over, w is actually stopped right here
965\& }
966.Ve
967.PP
968.Vb 3
969\& struct ev_timer mytimer;
970\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
971\& ev_timer_start (loop, &mytimer);
972.Ve
973.PP
974Example: create a timeout timer that times out after 10 seconds of
975inactivity.
976.PP
977.Vb 5
978\& static void
979\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
980\& {
981\& .. ten seconds without any activity
982\& }
983.Ve
984.PP
985.Vb 4
986\& struct ev_timer mytimer;
987\& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
988\& ev_timer_again (&mytimer); /* start timer */
989\& ev_loop (loop, 0);
990.Ve
991.PP
992.Vb 3
993\& // and in some piece of code that gets executed on any "activity":
994\& // reset the timeout to start ticking again at 10 seconds
995\& ev_timer_again (&mytimer);
996.Ve
705.ie n .Sh """ev_periodic"" \- to cron or not to cron" 997.ie n .Sh """ev_periodic"" \- to cron or not to cron?"
706.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron" 998.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?"
707.IX Subsection "ev_periodic - to cron or not to cron" 999.IX Subsection "ev_periodic - to cron or not to cron?"
708Periodic watchers are also timers of a kind, but they are very versatile 1000Periodic watchers are also timers of a kind, but they are very versatile
709(and unfortunately a bit complex). 1001(and unfortunately a bit complex).
710.PP 1002.PP
711Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) 1003Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time)
712but on wallclock time (absolute time). You can tell a periodic watcher 1004but on wallclock time (absolute time). You can tell a periodic watcher
713to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a 1005to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a
714periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () 1006periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now ()
715+ 10.>) and then reset your system clock to the last year, then it will 1007+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will
716take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger 1008take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger
717roughly 10 seconds later and of course not if you reset your system time 1009roughly 10 seconds later and of course not if you reset your system time
718again). 1010again).
719.PP 1011.PP
720They can also be used to implement vastly more complex timers, such as 1012They can also be used to implement vastly more complex timers, such as
… …
801.IX Item "ev_periodic_again (loop, ev_periodic *)" 1093.IX Item "ev_periodic_again (loop, ev_periodic *)"
802Simply stops and restarts the periodic watcher again. This is only useful 1094Simply stops and restarts the periodic watcher again. This is only useful
803when you changed some parameters or the reschedule callback would return 1095when you changed some parameters or the reschedule callback would return
804a different time than the last time it was called (e.g. in a crond like 1096a different time than the last time it was called (e.g. in a crond like
805program when the crontabs have changed). 1097program when the crontabs have changed).
1098.PP
1099Example: call a callback every hour, or, more precisely, whenever the
1100system clock is divisible by 3600. The callback invocation times have
1101potentially a lot of jittering, but good long-term stability.
1102.PP
1103.Vb 5
1104\& static void
1105\& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1106\& {
1107\& ... its now a full hour (UTC, or TAI or whatever your clock follows)
1108\& }
1109.Ve
1110.PP
1111.Vb 3
1112\& struct ev_periodic hourly_tick;
1113\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1114\& ev_periodic_start (loop, &hourly_tick);
1115.Ve
1116.PP
1117Example: the same as above, but use a reschedule callback to do it:
1118.PP
1119.Vb 1
1120\& #include <math.h>
1121.Ve
1122.PP
1123.Vb 5
1124\& static ev_tstamp
1125\& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1126\& {
1127\& return fmod (now, 3600.) + 3600.;
1128\& }
1129.Ve
1130.PP
1131.Vb 1
1132\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1133.Ve
1134.PP
1135Example: call a callback every hour, starting now:
1136.PP
1137.Vb 4
1138\& struct ev_periodic hourly_tick;
1139\& ev_periodic_init (&hourly_tick, clock_cb,
1140\& fmod (ev_now (loop), 3600.), 3600., 0);
1141\& ev_periodic_start (loop, &hourly_tick);
1142.Ve
806.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled" 1143.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!"
807.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled" 1144.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!"
808.IX Subsection "ev_signal - signal me when a signal gets signalled" 1145.IX Subsection "ev_signal - signal me when a signal gets signalled!"
809Signal watchers will trigger an event when the process receives a specific 1146Signal watchers will trigger an event when the process receives a specific
810signal one or more times. Even though signals are very asynchronous, libev 1147signal one or more times. Even though signals are very asynchronous, libev
811will try it's best to deliver signals synchronously, i.e. as part of the 1148will try it's best to deliver signals synchronously, i.e. as part of the
812normal event processing, like any other event. 1149normal event processing, like any other event.
813.PP 1150.PP
… …
823.IP "ev_signal_set (ev_signal *, int signum)" 4 1160.IP "ev_signal_set (ev_signal *, int signum)" 4
824.IX Item "ev_signal_set (ev_signal *, int signum)" 1161.IX Item "ev_signal_set (ev_signal *, int signum)"
825.PD 1162.PD
826Configures the watcher to trigger on the given signal number (usually one 1163Configures the watcher to trigger on the given signal number (usually one
827of the \f(CW\*(C`SIGxxx\*(C'\fR constants). 1164of the \f(CW\*(C`SIGxxx\*(C'\fR constants).
828.ie n .Sh """ev_child"" \- wait for pid status changes" 1165.ie n .Sh """ev_child"" \- watch out for process status changes"
829.el .Sh "\f(CWev_child\fP \- wait for pid status changes" 1166.el .Sh "\f(CWev_child\fP \- watch out for process status changes"
830.IX Subsection "ev_child - wait for pid status changes" 1167.IX Subsection "ev_child - watch out for process status changes"
831Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to 1168Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to
832some child status changes (most typically when a child of yours dies). 1169some child status changes (most typically when a child of yours dies).
833.IP "ev_child_init (ev_child *, callback, int pid)" 4 1170.IP "ev_child_init (ev_child *, callback, int pid)" 4
834.IX Item "ev_child_init (ev_child *, callback, int pid)" 1171.IX Item "ev_child_init (ev_child *, callback, int pid)"
835.PD 0 1172.PD 0
… …
840\&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look 1177\&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look
841at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see 1178at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see
842the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems 1179the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems
843\&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the 1180\&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the
844process causing the status change. 1181process causing the status change.
1182.PP
1183Example: try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.
1184.PP
1185.Vb 5
1186\& static void
1187\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1188\& {
1189\& ev_unloop (loop, EVUNLOOP_ALL);
1190\& }
1191.Ve
1192.PP
1193.Vb 3
1194\& struct ev_signal signal_watcher;
1195\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1196\& ev_signal_start (loop, &sigint_cb);
1197.Ve
845.ie n .Sh """ev_idle"" \- when you've got nothing better to do" 1198.ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
846.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do" 1199.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
847.IX Subsection "ev_idle - when you've got nothing better to do" 1200.IX Subsection "ev_idle - when you've got nothing better to do..."
848Idle watchers trigger events when there are no other events are pending 1201Idle watchers trigger events when there are no other events are pending
849(prepare, check and other idle watchers do not count). That is, as long 1202(prepare, check and other idle watchers do not count). That is, as long
850as your process is busy handling sockets or timeouts (or even signals, 1203as your process is busy handling sockets or timeouts (or even signals,
851imagine) it will not be triggered. But when your process is idle all idle 1204imagine) it will not be triggered. But when your process is idle all idle
852watchers are being called again and again, once per event loop iteration \- 1205watchers are being called again and again, once per event loop iteration \-
… …
863.IP "ev_idle_init (ev_signal *, callback)" 4 1216.IP "ev_idle_init (ev_signal *, callback)" 4
864.IX Item "ev_idle_init (ev_signal *, callback)" 1217.IX Item "ev_idle_init (ev_signal *, callback)"
865Initialises and configures the idle watcher \- it has no parameters of any 1218Initialises and configures the idle watcher \- it has no parameters of any
866kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, 1219kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,
867believe me. 1220believe me.
1221.PP
1222Example: dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR, start it, and in the
1223callback, free it. Alos, use no error checking, as usual.
1224.PP
1225.Vb 7
1226\& static void
1227\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1228\& {
1229\& free (w);
1230\& // now do something you wanted to do when the program has
1231\& // no longer asnything immediate to do.
1232\& }
1233.Ve
1234.PP
1235.Vb 3
1236\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1237\& ev_idle_init (idle_watcher, idle_cb);
1238\& ev_idle_start (loop, idle_cb);
1239.Ve
868.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop" 1240.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!"
869.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop" 1241.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!"
870.IX Subsection "ev_prepare and ev_check - customise your event loop" 1242.IX Subsection "ev_prepare and ev_check - customise your event loop!"
871Prepare and check watchers are usually (but not always) used in tandem: 1243Prepare and check watchers are usually (but not always) used in tandem:
872prepare watchers get invoked before the process blocks and check watchers 1244prepare watchers get invoked before the process blocks and check watchers
873afterwards. 1245afterwards.
874.PP 1246.PP
1247You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter
1248the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR
1249watchers. Other loops than the current one are fine, however. The
1250rationale behind this is that you do not need to check for recursion in
1251those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking,
1252\&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be
1253called in pairs bracketing the blocking call.
1254.PP
875Their main purpose is to integrate other event mechanisms into libev. This 1255Their main purpose is to integrate other event mechanisms into libev and
876could be used, for example, to track variable changes, implement your own 1256their use is somewhat advanced. This could be used, for example, to track
877watchers, integrate net-snmp or a coroutine library and lots more. 1257variable changes, implement your own watchers, integrate net-snmp or a
1258coroutine library and lots more. They are also occasionally useful if
1259you cache some data and want to flush it before blocking (for example,
1260in X programs you might want to do an \f(CW\*(C`XFlush ()\*(C'\fR in an \f(CW\*(C`ev_prepare\*(C'\fR
1261watcher).
878.PP 1262.PP
879This is done by examining in each prepare call which file descriptors need 1263This is done by examining in each prepare call which file descriptors need
880to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for 1264to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for
881them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries 1265them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries
882provide just this functionality). Then, in the check watcher you check for 1266provide just this functionality). Then, in the check watcher you check for
… …
900.IX Item "ev_check_init (ev_check *, callback)" 1284.IX Item "ev_check_init (ev_check *, callback)"
901.PD 1285.PD
902Initialises and configures the prepare or check watcher \- they have no 1286Initialises and configures the prepare or check watcher \- they have no
903parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR 1287parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR
904macros, but using them is utterly, utterly and completely pointless. 1288macros, but using them is utterly, utterly and completely pointless.
1289.PP
1290Example: To include a library such as adns, you would add \s-1IO\s0 watchers
1291and a timeout watcher in a prepare handler, as required by libadns, and
1292in a check watcher, destroy them and call into libadns. What follows is
1293pseudo-code only of course:
1294.PP
1295.Vb 2
1296\& static ev_io iow [nfd];
1297\& static ev_timer tw;
1298.Ve
1299.PP
1300.Vb 9
1301\& static void
1302\& io_cb (ev_loop *loop, ev_io *w, int revents)
1303\& {
1304\& // set the relevant poll flags
1305\& // could also call adns_processreadable etc. here
1306\& struct pollfd *fd = (struct pollfd *)w->data;
1307\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1308\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1309\& }
1310.Ve
1311.PP
1312.Vb 7
1313\& // create io watchers for each fd and a timer before blocking
1314\& static void
1315\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1316\& {
1317\& int timeout = 3600000;truct pollfd fds [nfd];
1318\& // actual code will need to loop here and realloc etc.
1319\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1320.Ve
1321.PP
1322.Vb 3
1323\& /* the callback is illegal, but won't be called as we stop during check */
1324\& ev_timer_init (&tw, 0, timeout * 1e-3);
1325\& ev_timer_start (loop, &tw);
1326.Ve
1327.PP
1328.Vb 6
1329\& // create on ev_io per pollfd
1330\& for (int i = 0; i < nfd; ++i)
1331\& {
1332\& ev_io_init (iow + i, io_cb, fds [i].fd,
1333\& ((fds [i].events & POLLIN ? EV_READ : 0)
1334\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1335.Ve
1336.PP
1337.Vb 5
1338\& fds [i].revents = 0;
1339\& iow [i].data = fds + i;
1340\& ev_io_start (loop, iow + i);
1341\& }
1342\& }
1343.Ve
1344.PP
1345.Vb 5
1346\& // stop all watchers after blocking
1347\& static void
1348\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1349\& {
1350\& ev_timer_stop (loop, &tw);
1351.Ve
1352.PP
1353.Vb 2
1354\& for (int i = 0; i < nfd; ++i)
1355\& ev_io_stop (loop, iow + i);
1356.Ve
1357.PP
1358.Vb 2
1359\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1360\& }
1361.Ve
1362.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1363.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
1364.IX Subsection "ev_embed - when one backend isn't enough..."
1365This is a rather advanced watcher type that lets you embed one event loop
1366into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded
1367loop, other types of watchers might be handled in a delayed or incorrect
1368fashion and must not be used).
1369.PP
1370There are primarily two reasons you would want that: work around bugs and
1371prioritise I/O.
1372.PP
1373As an example for a bug workaround, the kqueue backend might only support
1374sockets on some platform, so it is unusable as generic backend, but you
1375still want to make use of it because you have many sockets and it scales
1376so nicely. In this case, you would create a kqueue-based loop and embed it
1377into your default loop (which might use e.g. poll). Overall operation will
1378be a bit slower because first libev has to poll and then call kevent, but
1379at least you can use both at what they are best.
1380.PP
1381As for prioritising I/O: rarely you have the case where some fds have
1382to be watched and handled very quickly (with low latency), and even
1383priorities and idle watchers might have too much overhead. In this case
1384you would put all the high priority stuff in one loop and all the rest in
1385a second one, and embed the second one in the first.
1386.PP
1387As long as the watcher is active, the callback will be invoked every time
1388there might be events pending in the embedded loop. The callback must then
1389call \f(CW\*(C`ev_embed_sweep (mainloop, watcher)\*(C'\fR to make a single sweep and invoke
1390their callbacks (you could also start an idle watcher to give the embedded
1391loop strictly lower priority for example). You can also set the callback
1392to \f(CW0\fR, in which case the embed watcher will automatically execute the
1393embedded loop sweep.
1394.PP
1395As long as the watcher is started it will automatically handle events. The
1396callback will be invoked whenever some events have been handled. You can
1397set the callback to \f(CW0\fR to avoid having to specify one if you are not
1398interested in that.
1399.PP
1400Also, there have not currently been made special provisions for forking:
1401when you fork, you not only have to call \f(CW\*(C`ev_loop_fork\*(C'\fR on both loops,
1402but you will also have to stop and restart any \f(CW\*(C`ev_embed\*(C'\fR watchers
1403yourself.
1404.PP
1405Unfortunately, not all backends are embeddable, only the ones returned by
1406\&\f(CW\*(C`ev_embeddable_backends\*(C'\fR are, which, unfortunately, does not include any
1407portable one.
1408.PP
1409So when you want to use this feature you will always have to be prepared
1410that you cannot get an embeddable loop. The recommended way to get around
1411this is to have a separate variables for your embeddable loop, try to
1412create it, and if that fails, use the normal loop for everything:
1413.PP
1414.Vb 3
1415\& struct ev_loop *loop_hi = ev_default_init (0);
1416\& struct ev_loop *loop_lo = 0;
1417\& struct ev_embed embed;
1418.Ve
1419.PP
1420.Vb 5
1421\& // see if there is a chance of getting one that works
1422\& // (remember that a flags value of 0 means autodetection)
1423\& loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
1424\& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
1425\& : 0;
1426.Ve
1427.PP
1428.Vb 8
1429\& // if we got one, then embed it, otherwise default to loop_hi
1430\& if (loop_lo)
1431\& {
1432\& ev_embed_init (&embed, 0, loop_lo);
1433\& ev_embed_start (loop_hi, &embed);
1434\& }
1435\& else
1436\& loop_lo = loop_hi;
1437.Ve
1438.IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
1439.IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)"
1440.PD 0
1441.IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
1442.IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)"
1443.PD
1444Configures the watcher to embed the given loop, which must be
1445embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be
1446invoked automatically, otherwise it is the responsibility of the callback
1447to invoke it (it will continue to be called until the sweep has been done,
1448if you do not want thta, you need to temporarily stop the embed watcher).
1449.IP "ev_embed_sweep (loop, ev_embed *)" 4
1450.IX Item "ev_embed_sweep (loop, ev_embed *)"
1451Make a single, non-blocking sweep over the embedded loop. This works
1452similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most
1453apropriate way for embedded loops.
905.SH "OTHER FUNCTIONS" 1454.SH "OTHER FUNCTIONS"
906.IX Header "OTHER FUNCTIONS" 1455.IX Header "OTHER FUNCTIONS"
907There are some other functions of possible interest. Described. Here. Now. 1456There are some other functions of possible interest. Described. Here. Now.
908.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 1457.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4
909.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 1458.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)"
… …
938.Ve 1487.Ve
939.Sp 1488.Sp
940.Vb 1 1489.Vb 1
941\& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); 1490\& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
942.Ve 1491.Ve
943.IP "ev_feed_event (loop, watcher, int events)" 4 1492.IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4
944.IX Item "ev_feed_event (loop, watcher, int events)" 1493.IX Item "ev_feed_event (ev_loop *, watcher *, int revents)"
945Feeds the given event set into the event loop, as if the specified event 1494Feeds the given event set into the event loop, as if the specified event
946had happened for the specified watcher (which must be a pointer to an 1495had happened for the specified watcher (which must be a pointer to an
947initialised but not necessarily started event watcher). 1496initialised but not necessarily started event watcher).
948.IP "ev_feed_fd_event (loop, int fd, int revents)" 4 1497.IP "ev_feed_fd_event (ev_loop *, int fd, int revents)" 4
949.IX Item "ev_feed_fd_event (loop, int fd, int revents)" 1498.IX Item "ev_feed_fd_event (ev_loop *, int fd, int revents)"
950Feed an event on the given fd, as if a file descriptor backend detected 1499Feed an event on the given fd, as if a file descriptor backend detected
951the given events it. 1500the given events it.
952.IP "ev_feed_signal_event (loop, int signum)" 4 1501.IP "ev_feed_signal_event (ev_loop *loop, int signum)" 4
953.IX Item "ev_feed_signal_event (loop, int signum)" 1502.IX Item "ev_feed_signal_event (ev_loop *loop, int signum)"
954Feed an event as if the given signal occured (loop must be the default loop!). 1503Feed an event as if the given signal occured (\f(CW\*(C`loop\*(C'\fR must be the default
1504loop!).
955.SH "LIBEVENT EMULATION" 1505.SH "LIBEVENT EMULATION"
956.IX Header "LIBEVENT EMULATION" 1506.IX Header "LIBEVENT EMULATION"
957Libev offers a compatibility emulation layer for libevent. It cannot 1507Libev offers a compatibility emulation layer for libevent. It cannot
958emulate the internals of libevent, so here are some usage hints: 1508emulate the internals of libevent, so here are some usage hints:
959.IP "* Use it by including <event.h>, as usual." 4 1509.IP "* Use it by including <event.h>, as usual." 4
… …
970.IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4 1520.IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4
971.IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library." 1521.IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library."
972.PD 1522.PD
973.SH "\*(C+ SUPPORT" 1523.SH "\*(C+ SUPPORT"
974.IX Header " SUPPORT" 1524.IX Header " SUPPORT"
975\&\s-1TBD\s0. 1525Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow
1526you to use some convinience methods to start/stop watchers and also change
1527the callback model to a model using method callbacks on objects.
1528.PP
1529To use it,
1530.PP
1531.Vb 1
1532\& #include <ev++.h>
1533.Ve
1534.PP
1535(it is not installed by default). This automatically includes \fIev.h\fR
1536and puts all of its definitions (many of them macros) into the global
1537namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace.
1538.PP
1539It should support all the same embedding options as \fIev.h\fR, most notably
1540\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
1541.PP
1542Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
1543.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
1544.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
1545.IX Item "ev::READ, ev::WRITE etc."
1546These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc.
1547macros from \fIev.h\fR.
1548.ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4
1549.el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4
1550.IX Item "ev::tstamp, ev::now"
1551Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix.
1552.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
1553.el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4
1554.IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc."
1555For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of
1556the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR
1557which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
1558defines by many implementations.
1559.Sp
1560All of those classes have these methods:
1561.RS 4
1562.IP "ev::TYPE::TYPE (object *, object::method *)" 4
1563.IX Item "ev::TYPE::TYPE (object *, object::method *)"
1564.PD 0
1565.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4
1566.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)"
1567.IP "ev::TYPE::~TYPE" 4
1568.IX Item "ev::TYPE::~TYPE"
1569.PD
1570The constructor takes a pointer to an object and a method pointer to
1571the event handler callback to call in this class. The constructor calls
1572\&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method
1573before starting it. If you do not specify a loop then the constructor
1574automatically associates the default loop with this watcher.
1575.Sp
1576The destructor automatically stops the watcher if it is active.
1577.IP "w\->set (struct ev_loop *)" 4
1578.IX Item "w->set (struct ev_loop *)"
1579Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
1580do this when the watcher is inactive (and not pending either).
1581.IP "w\->set ([args])" 4
1582.IX Item "w->set ([args])"
1583Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be
1584called at least once. Unlike the C counterpart, an active watcher gets
1585automatically stopped and restarted.
1586.IP "w\->start ()" 4
1587.IX Item "w->start ()"
1588Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the
1589constructor already takes the loop.
1590.IP "w\->stop ()" 4
1591.IX Item "w->stop ()"
1592Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
1593.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4
1594.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4
1595.IX Item "w->again () ev::timer, ev::periodic only"
1596For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding
1597\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function.
1598.ie n .IP "w\->sweep () ""ev::embed"" only" 4
1599.el .IP "w\->sweep () \f(CWev::embed\fR only" 4
1600.IX Item "w->sweep () ev::embed only"
1601Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR.
1602.RE
1603.RS 4
1604.RE
1605.PP
1606Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in
1607the constructor.
1608.PP
1609.Vb 4
1610\& class myclass
1611\& {
1612\& ev_io io; void io_cb (ev::io &w, int revents);
1613\& ev_idle idle void idle_cb (ev::idle &w, int revents);
1614.Ve
1615.PP
1616.Vb 2
1617\& myclass ();
1618\& }
1619.Ve
1620.PP
1621.Vb 6
1622\& myclass::myclass (int fd)
1623\& : io (this, &myclass::io_cb),
1624\& idle (this, &myclass::idle_cb)
1625\& {
1626\& io.start (fd, ev::READ);
1627\& }
1628.Ve
1629.SH "EMBEDDING"
1630.IX Header "EMBEDDING"
1631Libev can (and often is) directly embedded into host
1632applications. Examples of applications that embed it include the Deliantra
1633Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe)
1634and rxvt\-unicode.
1635.PP
1636The goal is to enable you to just copy the neecssary files into your
1637source directory without having to change even a single line in them, so
1638you can easily upgrade by simply copying (or having a checked-out copy of
1639libev somewhere in your source tree).
1640.Sh "\s-1FILESETS\s0"
1641.IX Subsection "FILESETS"
1642Depending on what features you need you need to include one or more sets of files
1643in your app.
1644.PP
1645\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR
1646.IX Subsection "CORE EVENT LOOP"
1647.PP
1648To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual
1649configuration (no autoconf):
1650.PP
1651.Vb 2
1652\& #define EV_STANDALONE 1
1653\& #include "ev.c"
1654.Ve
1655.PP
1656This will automatically include \fIev.h\fR, too, and should be done in a
1657single C source file only to provide the function implementations. To use
1658it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best
1659done by writing a wrapper around \fIev.h\fR that you can include instead and
1660where you can put other configuration options):
1661.PP
1662.Vb 2
1663\& #define EV_STANDALONE 1
1664\& #include "ev.h"
1665.Ve
1666.PP
1667Both header files and implementation files can be compiled with a \*(C+
1668compiler (at least, thats a stated goal, and breakage will be treated
1669as a bug).
1670.PP
1671You need the following files in your source tree, or in a directory
1672in your include path (e.g. in libev/ when using \-Ilibev):
1673.PP
1674.Vb 4
1675\& ev.h
1676\& ev.c
1677\& ev_vars.h
1678\& ev_wrap.h
1679.Ve
1680.PP
1681.Vb 1
1682\& ev_win32.c required on win32 platforms only
1683.Ve
1684.PP
1685.Vb 5
1686\& ev_select.c only when select backend is enabled (which is by default)
1687\& ev_poll.c only when poll backend is enabled (disabled by default)
1688\& ev_epoll.c only when the epoll backend is enabled (disabled by default)
1689\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1690\& ev_port.c only when the solaris port backend is enabled (disabled by default)
1691.Ve
1692.PP
1693\&\fIev.c\fR includes the backend files directly when enabled, so you only need
1694to compile this single file.
1695.PP
1696\fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR
1697.IX Subsection "LIBEVENT COMPATIBILITY API"
1698.PP
1699To include the libevent compatibility \s-1API\s0, also include:
1700.PP
1701.Vb 1
1702\& #include "event.c"
1703.Ve
1704.PP
1705in the file including \fIev.c\fR, and:
1706.PP
1707.Vb 1
1708\& #include "event.h"
1709.Ve
1710.PP
1711in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR.
1712.PP
1713You need the following additional files for this:
1714.PP
1715.Vb 2
1716\& event.h
1717\& event.c
1718.Ve
1719.PP
1720\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR
1721.IX Subsection "AUTOCONF SUPPORT"
1722.PP
1723Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in
1724whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your
1725\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then
1726include \fIconfig.h\fR and configure itself accordingly.
1727.PP
1728For this of course you need the m4 file:
1729.PP
1730.Vb 1
1731\& libev.m4
1732.Ve
1733.Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0"
1734.IX Subsection "PREPROCESSOR SYMBOLS/MACROS"
1735Libev can be configured via a variety of preprocessor symbols you have to define
1736before including any of its files. The default is not to build for multiplicity
1737and only include the select backend.
1738.IP "\s-1EV_STANDALONE\s0" 4
1739.IX Item "EV_STANDALONE"
1740Must always be \f(CW1\fR if you do not use autoconf configuration, which
1741keeps libev from including \fIconfig.h\fR, and it also defines dummy
1742implementations for some libevent functions (such as logging, which is not
1743supported). It will also not define any of the structs usually found in
1744\&\fIevent.h\fR that are not directly supported by the libev core alone.
1745.IP "\s-1EV_USE_MONOTONIC\s0" 4
1746.IX Item "EV_USE_MONOTONIC"
1747If defined to be \f(CW1\fR, libev will try to detect the availability of the
1748monotonic clock option at both compiletime and runtime. Otherwise no use
1749of the monotonic clock option will be attempted. If you enable this, you
1750usually have to link against librt or something similar. Enabling it when
1751the functionality isn't available is safe, though, althoguh you have
1752to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR
1753function is hiding in (often \fI\-lrt\fR).
1754.IP "\s-1EV_USE_REALTIME\s0" 4
1755.IX Item "EV_USE_REALTIME"
1756If defined to be \f(CW1\fR, libev will try to detect the availability of the
1757realtime clock option at compiletime (and assume its availability at
1758runtime if successful). Otherwise no use of the realtime clock option will
1759be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get
1760(CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See tzhe note about libraries
1761in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though.
1762.IP "\s-1EV_USE_SELECT\s0" 4
1763.IX Item "EV_USE_SELECT"
1764If undefined or defined to be \f(CW1\fR, libev will compile in support for the
1765\&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no
1766other method takes over, select will be it. Otherwise the select backend
1767will not be compiled in.
1768.IP "\s-1EV_SELECT_USE_FD_SET\s0" 4
1769.IX Item "EV_SELECT_USE_FD_SET"
1770If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR
1771structure. This is useful if libev doesn't compile due to a missing
1772\&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it misguesses the bitset layout on
1773exotic systems. This usually limits the range of file descriptors to some
1774low limit such as 1024 or might have other limitations (winsocket only
1775allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might
1776influence the size of the \f(CW\*(C`fd_set\*(C'\fR used.
1777.IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4
1778.IX Item "EV_SELECT_IS_WINSOCKET"
1779When defined to \f(CW1\fR, the select backend will assume that
1780select/socket/connect etc. don't understand file descriptors but
1781wants osf handles on win32 (this is the case when the select to
1782be used is the winsock select). This means that it will call
1783\&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise,
1784it is assumed that all these functions actually work on fds, even
1785on win32. Should not be defined on non\-win32 platforms.
1786.IP "\s-1EV_USE_POLL\s0" 4
1787.IX Item "EV_USE_POLL"
1788If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2)
1789backend. Otherwise it will be enabled on non\-win32 platforms. It
1790takes precedence over select.
1791.IP "\s-1EV_USE_EPOLL\s0" 4
1792.IX Item "EV_USE_EPOLL"
1793If defined to be \f(CW1\fR, libev will compile in support for the Linux
1794\&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime,
1795otherwise another method will be used as fallback. This is the
1796preferred backend for GNU/Linux systems.
1797.IP "\s-1EV_USE_KQUEUE\s0" 4
1798.IX Item "EV_USE_KQUEUE"
1799If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style
1800\&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime,
1801otherwise another method will be used as fallback. This is the preferred
1802backend for \s-1BSD\s0 and BSD-like systems, although on most BSDs kqueue only
1803supports some types of fds correctly (the only platform we found that
1804supports ptys for example was NetBSD), so kqueue might be compiled in, but
1805not be used unless explicitly requested. The best way to use it is to find
1806out whether kqueue supports your type of fd properly and use an embedded
1807kqueue loop.
1808.IP "\s-1EV_USE_PORT\s0" 4
1809.IX Item "EV_USE_PORT"
1810If defined to be \f(CW1\fR, libev will compile in support for the Solaris
181110 port style backend. Its availability will be detected at runtime,
1812otherwise another method will be used as fallback. This is the preferred
1813backend for Solaris 10 systems.
1814.IP "\s-1EV_USE_DEVPOLL\s0" 4
1815.IX Item "EV_USE_DEVPOLL"
1816reserved for future expansion, works like the \s-1USE\s0 symbols above.
1817.IP "\s-1EV_H\s0" 4
1818.IX Item "EV_H"
1819The name of the \fIev.h\fR header file used to include it. The default if
1820undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This
1821can be used to virtually rename the \fIev.h\fR header file in case of conflicts.
1822.IP "\s-1EV_CONFIG_H\s0" 4
1823.IX Item "EV_CONFIG_H"
1824If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override
1825\&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to
1826\&\f(CW\*(C`EV_H\*(C'\fR, above.
1827.IP "\s-1EV_EVENT_H\s0" 4
1828.IX Item "EV_EVENT_H"
1829Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea
1830of how the \fIevent.h\fR header can be found.
1831.IP "\s-1EV_PROTOTYPES\s0" 4
1832.IX Item "EV_PROTOTYPES"
1833If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function
1834prototypes, but still define all the structs and other symbols. This is
1835occasionally useful if you want to provide your own wrapper functions
1836around libev functions.
1837.IP "\s-1EV_MULTIPLICITY\s0" 4
1838.IX Item "EV_MULTIPLICITY"
1839If undefined or defined to \f(CW1\fR, then all event-loop-specific functions
1840will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create
1841additional independent event loops. Otherwise there will be no support
1842for multiple event loops and there is no first event loop pointer
1843argument. Instead, all functions act on the single default loop.
1844.IP "\s-1EV_PERIODICS\s0" 4
1845.IX Item "EV_PERIODICS"
1846If undefined or defined to be \f(CW1\fR, then periodic timers are supported,
1847otherwise not. This saves a few kb of code.
1848.IP "\s-1EV_COMMON\s0" 4
1849.IX Item "EV_COMMON"
1850By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
1851this macro to a something else you can include more and other types of
1852members. You have to define it each time you include one of the files,
1853though, and it must be identical each time.
1854.Sp
1855For example, the perl \s-1EV\s0 module uses something like this:
1856.Sp
1857.Vb 3
1858\& #define EV_COMMON \e
1859\& SV *self; /* contains this struct */ \e
1860\& SV *cb_sv, *fh /* note no trailing ";" */
1861.Ve
1862.IP "\s-1EV_CB_DECLARE\s0 (type)" 4
1863.IX Item "EV_CB_DECLARE (type)"
1864.PD 0
1865.IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4
1866.IX Item "EV_CB_INVOKE (watcher, revents)"
1867.IP "ev_set_cb (ev, cb)" 4
1868.IX Item "ev_set_cb (ev, cb)"
1869.PD
1870Can be used to change the callback member declaration in each watcher,
1871and the way callbacks are invoked and set. Must expand to a struct member
1872definition and a statement, respectively. See the \fIev.v\fR header file for
1873their default definitions. One possible use for overriding these is to
1874avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
1875method calls instead of plain function calls in \*(C+.
1876.Sh "\s-1EXAMPLES\s0"
1877.IX Subsection "EXAMPLES"
1878For a real-world example of a program the includes libev
1879verbatim, you can have a look at the \s-1EV\s0 perl module
1880(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in
1881the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public
1882interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file
1883will be compiled. It is pretty complex because it provides its own header
1884file.
1885.Sp
1886The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
1887that everybody includes and which overrides some autoconf choices:
1888.Sp
1889.Vb 4
1890\& #define EV_USE_POLL 0
1891\& #define EV_MULTIPLICITY 0
1892\& #define EV_PERIODICS 0
1893\& #define EV_CONFIG_H <config.h>
1894.Ve
1895.Sp
1896.Vb 1
1897\& #include "ev++.h"
1898.Ve
1899.Sp
1900And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled:
1901.Sp
1902.Vb 2
1903\& #include "ev_cpp.h"
1904\& #include "ev.c"
1905.Ve
1906.SH "COMPLEXITIES"
1907.IX Header "COMPLEXITIES"
1908In this section the complexities of (many of) the algorithms used inside
1909libev will be explained. For complexity discussions about backends see the
1910documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
1911.RS 4
1912.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
1913.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
1914.PD 0
1915.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
1916.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
1917.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
1918.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
1919.IP "Stopping check/prepare/idle watchers: O(1)" 4
1920.IX Item "Stopping check/prepare/idle watchers: O(1)"
1921.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 4
1922.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))"
1923.IP "Finding the next timer per loop iteration: O(1)" 4
1924.IX Item "Finding the next timer per loop iteration: O(1)"
1925.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
1926.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
1927.IP "Activating one watcher: O(1)" 4
1928.IX Item "Activating one watcher: O(1)"
1929.RE
1930.RS 4
1931.PD
976.SH "AUTHOR" 1932.SH "AUTHOR"
977.IX Header "AUTHOR" 1933.IX Header "AUTHOR"
978Marc Lehmann <libev@schmorp.de>. 1934Marc Lehmann <libev@schmorp.de>.

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