ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/libev/ev.3
(Generate patch)

Comparing libev/ev.3 (file contents):
Revision 1.5 by root, Fri Nov 23 04:36:03 2007 UTC vs.
Revision 1.8 by root, Fri Nov 23 15:26:08 2007 UTC

… …
199.Sp 199.Sp
200Usually, it's a good idea to terminate if the major versions mismatch, 200Usually, it's a good idea to terminate if the major versions mismatch,
201as this indicates an incompatible change. Minor versions are usually 201as this indicates an incompatible change. Minor versions are usually
202compatible to older versions, so a larger minor version alone is usually 202compatible to older versions, so a larger minor version alone is usually
203not a problem. 203not a problem.
204.IP "unsigned int ev_supported_backends ()" 4
205.IX Item "unsigned int ev_supported_backends ()"
206Return 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
208availability on the system you are running on). See \f(CW\*(C`ev_default_loop\*(C'\fR for
209a description of the set values.
210.IP "unsigned int ev_recommended_backends ()" 4
211.IX Item "unsigned int ev_recommended_backends ()"
212Return 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
214returned 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
216(assuming you know what you are doing). This is the set of backends that
217libev will probe for if you specify no backends explicitly.
204.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 218.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4
205.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" 219.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"
206Sets the allocation function to use (the prototype is similar to the 220Sets the allocation function to use (the prototype is similar to the
207realloc C function, the semantics are identical). It is used to allocate 221realloc C function, the semantics are identical). It is used to allocate
208and free memory (no surprises here). If it returns zero when memory 222and free memory (no surprises here). If it returns zero when memory
… …
236.IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 250.IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4
237.IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" 251.IX Item "struct ev_loop *ev_default_loop (unsigned int flags)"
238This will initialise the default event loop if it hasn't been initialised 252This 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 253yet 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 254false. If it already was initialised it simply returns it (and ignores the
241flags). 255flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards).
242.Sp 256.Sp
243If you don't know what event loop to use, use the one returned from this 257If you don't know what event loop to use, use the one returned from this
244function. 258function.
245.Sp 259.Sp
246The flags argument can be used to specify special behaviour or specific 260The 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). 261backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR).
248.Sp 262.Sp
249It supports the following flags: 263The following flags are supported:
250.RS 4 264.RS 4
251.ie n .IP """EVFLAG_AUTO""" 4 265.ie n .IP """EVFLAG_AUTO""" 4
252.el .IP "\f(CWEVFLAG_AUTO\fR" 4 266.el .IP "\f(CWEVFLAG_AUTO\fR" 4
253.IX Item "EVFLAG_AUTO" 267.IX Item "EVFLAG_AUTO"
254The default flags value. Use this if you have no clue (it's the right 268The 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 274or 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 275\&\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 276override 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 277useful to try out specific backends to test their performance, or to work
264around bugs. 278around bugs.
265.ie n .IP """EVMETHOD_SELECT"" (value 1, portable select backend)" 4 279.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
266.el .IP "\f(CWEVMETHOD_SELECT\fR (value 1, portable select backend)" 4 280.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
267.IX Item "EVMETHOD_SELECT (value 1, portable select backend)" 281.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
268This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 282This 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, 283libev 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 284but 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 285using this backend. It doesn't scale too well (O(highest_fd)), but its usually
272the fastest backend for a low number of fds. 286the fastest backend for a low number of fds.
273.ie n .IP """EVMETHOD_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 287.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)" 4 288.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)" 289.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 290And 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 291select, 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 292number 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). 293lot of inactive fds). It scales similarly to select, i.e. O(total_fds).
280.ie n .IP """EVMETHOD_EPOLL"" (value 4, Linux)" 4 294.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4
281.el .IP "\f(CWEVMETHOD_EPOLL\fR (value 4, Linux)" 4 295.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4
282.IX Item "EVMETHOD_EPOLL (value 4, Linux)" 296.IX Item "EVBACKEND_EPOLL (value 4, Linux)"
283For few fds, this backend is a bit little slower than poll and select, 297For 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 298but 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 299O(total_fds) where n is the total number of fds (or the highest fd), epoll scales
286either O(1) or O(active_fds). 300either O(1) or O(active_fds).
287.Sp 301.Sp
288While stopping and starting an I/O watcher in the same iteration will 302While stopping and starting an I/O watcher in the same iteration will
289result in some caching, there is still a syscall per such incident 303result 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 304(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 305best to avoid that. Also, \fIdup()\fRed file descriptors might not work very
292well if you register events for both fds. 306well if you register events for both fds.
307.Sp
308Please note that epoll sometimes generates spurious notifications, so you
309need to use non-blocking I/O or other means to avoid blocking when no data
310(or space) is available.
293.ie n .IP """EVMETHOD_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 311.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)" 4 312.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4
295.IX Item "EVMETHOD_KQUEUE (value 8, most BSD clones)" 313.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"
296Kqueue deserves special mention, as at the time of this writing, it 314Kqueue deserves special mention, as at the time of this writing, it
297was broken on all BSDs except NetBSD (usually it doesn't work with 315was broken on all BSDs except NetBSD (usually it doesn't work with
298anything but sockets and pipes, except on Darwin, where of course its 316anything but sockets and pipes, except on Darwin, where of course its
299completely useless). For this reason its not being \*(L"autodetected\*(R" unless 317completely 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). 318unless you explicitly specify it explicitly in the flags (i.e. using
319\&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR).
301.Sp 320.Sp
302It scales in the same way as the epoll backend, but the interface to the 321It 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 322kernel is more efficient (which says nothing about its actual speed, of
304course). While starting and stopping an I/O watcher does not cause an 323course). 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 324extra syscall as with epoll, it still adds up to four event changes per
306incident, so its best to avoid that. 325incident, so its best to avoid that.
307.ie n .IP """EVMETHOD_DEVPOLL"" (value 16, Solaris 8)" 4 326.ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4
308.el .IP "\f(CWEVMETHOD_DEVPOLL\fR (value 16, Solaris 8)" 4 327.el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4
309.IX Item "EVMETHOD_DEVPOLL (value 16, Solaris 8)" 328.IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)"
310This is not implemented yet (and might never be). 329This is not implemented yet (and might never be).
311.ie n .IP """EVMETHOD_PORT"" (value 32, Solaris 10)" 4 330.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4
312.el .IP "\f(CWEVMETHOD_PORT\fR (value 32, Solaris 10)" 4 331.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4
313.IX Item "EVMETHOD_PORT (value 32, Solaris 10)" 332.IX Item "EVBACKEND_PORT (value 32, Solaris 10)"
314This uses the Solaris 10 port mechanism. As with everything on Solaris, 333This uses the Solaris 10 port mechanism. As with everything on Solaris,
315it's really slow, but it still scales very well (O(active_fds)). 334it's really slow, but it still scales very well (O(active_fds)).
335.Sp
336Please note that solaris ports can result in a lot of spurious
337notifications, so you need to use non-blocking I/O or other means to avoid
338blocking when no data (or space) is available.
316.ie n .IP """EVMETHOD_ALL""" 4 339.ie n .IP """EVBACKEND_ALL""" 4
317.el .IP "\f(CWEVMETHOD_ALL\fR" 4 340.el .IP "\f(CWEVBACKEND_ALL\fR" 4
318.IX Item "EVMETHOD_ALL" 341.IX Item "EVBACKEND_ALL"
319Try all backends (even potentially broken ones that wouldn't be tried 342Try 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 343with \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. 344\&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR.
322.RE 345.RE
323.RS 4 346.RS 4
324.Sp 347.Sp
325If one or more of these are ored into the flags value, then only these 348If 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 349backends will be tried (in the reverse order as given here). If none are
327specified, most compiled-in backend will be tried, usually in reverse 350specified, most compiled-in backend will be tried, usually in reverse
328order of their flag values :) 351order of their flag values :)
352.Sp
353The most typical usage is like this:
354.Sp
355.Vb 2
356\& if (!ev_default_loop (0))
357\& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
358.Ve
359.Sp
360Restrict libev to the select and poll backends, and do not allow
361environment settings to be taken into account:
362.Sp
363.Vb 1
364\& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
365.Ve
366.Sp
367Use whatever libev has to offer, but make sure that kqueue is used if
368available (warning, breaks stuff, best use only with your own private
369event loop and only if you know the \s-1OS\s0 supports your types of fds):
370.Sp
371.Vb 1
372\& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
373.Ve
329.RE 374.RE
330.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 375.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4
331.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" 376.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 377Similar 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 378always distinct from the default loop. Unlike the default loop, it cannot
… …
358quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: 403quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR:
359.Sp 404.Sp
360.Vb 1 405.Vb 1
361\& pthread_atfork (0, 0, ev_default_fork); 406\& pthread_atfork (0, 0, ev_default_fork);
362.Ve 407.Ve
408.Sp
409At the moment, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR are safe to use
410without calling this function, so if you force one of those backends you
411do not need to care.
363.IP "ev_loop_fork (loop)" 4 412.IP "ev_loop_fork (loop)" 4
364.IX Item "ev_loop_fork (loop)" 413.IX Item "ev_loop_fork (loop)"
365Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by 414Like \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 415\&\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. 416after fork, and how you do this is entirely your own problem.
368.IP "unsigned int ev_method (loop)" 4 417.IP "unsigned int ev_backend (loop)" 4
369.IX Item "unsigned int ev_method (loop)" 418.IX Item "unsigned int ev_backend (loop)"
370Returns one of the \f(CW\*(C`EVMETHOD_*\*(C'\fR flags indicating the event backend in 419Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
371use. 420use.
372.IP "ev_tstamp ev_now (loop)" 4 421.IP "ev_tstamp ev_now (loop)" 4
373.IX Item "ev_tstamp ev_now (loop)" 422.IX Item "ev_tstamp ev_now (loop)"
374Returns the current \*(L"event loop time\*(R", which is the time the event loop 423Returns 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 424got events and started processing them. This timestamp does not change
… …
380.IX Item "ev_loop (loop, int flags)" 429.IX Item "ev_loop (loop, int flags)"
381Finally, this is it, the event handler. This function usually is called 430Finally, this is it, the event handler. This function usually is called
382after you initialised all your watchers and you want to start handling 431after you initialised all your watchers and you want to start handling
383events. 432events.
384.Sp 433.Sp
385If the flags argument is specified as 0, it will not return until either 434If 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. 435either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called.
387.Sp 436.Sp
388A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle 437A 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 438those 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. 439case there are no events and will return after one iteration of the loop.
391.Sp 440.Sp
392A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if 441A 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 442neccessary) and will handle those and any outstanding ones. It will block
394your process until at least one new event arrives, and will return after 443your process until at least one new event arrives, and will return after
395one iteration of the loop. 444one iteration of the loop. This is useful if you are waiting for some
445external event in conjunction with something not expressible using other
446libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is
447usually a better approach for this kind of thing.
396.Sp 448.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: 449Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does:
402.Sp 450.Sp
403.Vb 15 451.Vb 18
404\& 1. If there are no active watchers (reference count is zero), return. 452\& * If there are no active watchers (reference count is zero), return.
405\& 2. Queue and immediately call all prepare watchers. 453\& - Queue prepare watchers and then call all outstanding watchers.
406\& 3. If we have been forked, recreate the kernel state. 454\& - If we have been forked, recreate the kernel state.
407\& 4. Update the kernel state with all outstanding changes. 455\& - Update the kernel state with all outstanding changes.
408\& 5. Update the "event loop time". 456\& - Update the "event loop time".
409\& 6. Calculate for how long to block. 457\& - Calculate for how long to block.
410\& 7. Block the process, waiting for events. 458\& - Block the process, waiting for any events.
459\& - Queue all outstanding I/O (fd) events.
411\& 8. Update the "event loop time" and do time jump handling. 460\& - Update the "event loop time" and do time jump handling.
412\& 9. Queue all outstanding timers. 461\& - Queue all outstanding timers.
413\& 10. Queue all outstanding periodics. 462\& - Queue all outstanding periodics.
414\& 11. If no events are pending now, queue all idle watchers. 463\& - If no events are pending now, queue all idle watchers.
415\& 12. Queue all check watchers. 464\& - Queue all check watchers.
416\& 13. Call all queued watchers in reverse order (i.e. check watchers first). 465\& - Call all queued watchers in reverse order (i.e. check watchers first).
466\& Signals and child watchers are implemented as I/O watchers, and will
467\& 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 468\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
418\& was used, return, otherwise continue with step #1. 469\& were used, return, otherwise continue with step *.
419.Ve 470.Ve
420.IP "ev_unloop (loop, how)" 4 471.IP "ev_unloop (loop, how)" 4
421.IX Item "ev_unloop (loop, how)" 472.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 473Can 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 474has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either
… …
482*)\*(C'\fR), and you can stop watching for events at any time by calling the 533*)\*(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. 534corresponding stop function (\f(CW\*(C`ev_<type>_stop (loop, watcher *)\*(C'\fR.
484.PP 535.PP
485As long as your watcher is active (has been started but not stopped) you 536As 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 537must not touch the values stored in it. Most specifically you must never
487reinitialise it or call its set method. 538reinitialise it or call its set macro.
488.PP 539.PP
489You can check whether an event is active by calling the \f(CW\*(C`ev_is_active 540You 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 541(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 542callback for it has not been called yet) you can use the \f(CW\*(C`ev_is_pending
492(watcher *)\*(C'\fR macro. 543(watcher *)\*(C'\fR macro.
… …
612descriptors correctly if you register interest in two or more fds pointing 663descriptors correctly if you register interest in two or more fds pointing
613to the same underlying file/socket etc. description (that is, they share 664to the same underlying file/socket etc. description (that is, they share
614the same underlying \*(L"file open\*(R"). 665the same underlying \*(L"file open\*(R").
615.PP 666.PP
616If you must do this, then force the use of a known-to-be-good backend 667If 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 668(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and
618\&\s-1EVMETHOD_POLL\s0). 669\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR).
619.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 670.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)" 671.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
621.PD 0 672.PD 0
622.IP "ev_io_set (ev_io *, int fd, int events)" 4 673.IP "ev_io_set (ev_io *, int fd, int events)" 4
623.IX Item "ev_io_set (ev_io *, int fd, int events)" 674.IX Item "ev_io_set (ev_io *, int fd, int events)"
624.PD 675.PD
625Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The fd is the file descriptor to rceeive 676Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The fd is the file descriptor to rceeive
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 | 677events 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 |
627EV_WRITE\*(C'\fR to receive the given events. 678EV_WRITE\*(C'\fR to receive the given events.
679.Sp
680Please note that most of the more scalable backend mechanisms (for example
681epoll and solaris ports) can result in spurious readyness notifications
682for file descriptors, so you practically need to use non-blocking I/O (and
683treat callback invocation as hint only), or retest separately with a safe
684interface before doing I/O (XLib can do this), or force the use of either
685\&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR, which don't suffer from this
686problem. Also note that it is quite easy to have your callback invoked
687when the readyness condition is no longer valid even when employing
688typical ways of handling events, so its a good idea to use non-blocking
689I/O unconditionally.
628.ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts" 690.ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts"
629.el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts" 691.el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts"
630.IX Subsection "ev_timer - relative and optionally recurring timeouts" 692.IX Subsection "ev_timer - relative and optionally recurring timeouts"
631Timer watchers are simple relative timers that generate an event after a 693Timer watchers are simple relative timers that generate an event after a
632given time, and optionally repeating in regular intervals after that. 694given time, and optionally repeating in regular intervals after that.

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines