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Comparing libev/ev.3 (file contents):
Revision 1.5 by root, Fri Nov 23 04:36:03 2007 UTC vs.
Revision 1.6 by root, Fri Nov 23 05:14:58 2007 UTC

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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
217\&\f(CW\*(C`EVFLAG_AUTO\*(C'\fR will probe for.
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
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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 \s-1EVFLAG_AUTO\s0).
248.Sp 262.Sp
249It supports the following flags: 263It supports the following flags:
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
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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.
293.ie n .IP """EVMETHOD_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 307.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)" 4 308.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4
295.IX Item "EVMETHOD_KQUEUE (value 8, most BSD clones)" 309.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"
296Kqueue deserves special mention, as at the time of this writing, it 310Kqueue deserves special mention, as at the time of this writing, it
297was broken on all BSDs except NetBSD (usually it doesn't work with 311was broken on all BSDs except NetBSD (usually it doesn't work with
298anything but sockets and pipes, except on Darwin, where of course its 312anything but sockets and pipes, except on Darwin, where of course its
299completely useless). For this reason its not being \*(L"autodetected\*(R" unless 313completely useless). For this reason its not being \*(L"autodetected\*(R" unless
300you explicitly specify the flags (i.e. you don't use \s-1EVFLAG_AUTO\s0). 314you explicitly specify the flags (i.e. you don't use \s-1EVFLAG_AUTO\s0).
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302It scales in the same way as the epoll backend, but the interface to the 316It 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 317kernel is more efficient (which says nothing about its actual speed, of
304course). While starting and stopping an I/O watcher does not cause an 318course). 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 319extra syscall as with epoll, it still adds up to four event changes per
306incident, so its best to avoid that. 320incident, so its best to avoid that.
307.ie n .IP """EVMETHOD_DEVPOLL"" (value 16, Solaris 8)" 4 321.ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4
308.el .IP "\f(CWEVMETHOD_DEVPOLL\fR (value 16, Solaris 8)" 4 322.el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4
309.IX Item "EVMETHOD_DEVPOLL (value 16, Solaris 8)" 323.IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)"
310This is not implemented yet (and might never be). 324This is not implemented yet (and might never be).
311.ie n .IP """EVMETHOD_PORT"" (value 32, Solaris 10)" 4 325.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4
312.el .IP "\f(CWEVMETHOD_PORT\fR (value 32, Solaris 10)" 4 326.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4
313.IX Item "EVMETHOD_PORT (value 32, Solaris 10)" 327.IX Item "EVBACKEND_PORT (value 32, Solaris 10)"
314This uses the Solaris 10 port mechanism. As with everything on Solaris, 328This uses the Solaris 10 port mechanism. As with everything on Solaris,
315it's really slow, but it still scales very well (O(active_fds)). 329it's really slow, but it still scales very well (O(active_fds)).
316.ie n .IP """EVMETHOD_ALL""" 4 330.ie n .IP """EVBACKEND_ALL""" 4
317.el .IP "\f(CWEVMETHOD_ALL\fR" 4 331.el .IP "\f(CWEVBACKEND_ALL\fR" 4
318.IX Item "EVMETHOD_ALL" 332.IX Item "EVBACKEND_ALL"
319Try all backends (even potentially broken ones that wouldn't be tried 333Try 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 334with \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. 335\&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR.
322.RE 336.RE
323.RS 4 337.RS 4
324.Sp 338.Sp
325If one or more of these are ored into the flags value, then only these 339If 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 340backends will be tried (in the reverse order as given here). If none are
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358quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: 372quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR:
359.Sp 373.Sp
360.Vb 1 374.Vb 1
361\& pthread_atfork (0, 0, ev_default_fork); 375\& pthread_atfork (0, 0, ev_default_fork);
362.Ve 376.Ve
377.Sp
378At the moment, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR are safe to use
379without calling this function, so if you force one of those backends you
380do not need to care.
363.IP "ev_loop_fork (loop)" 4 381.IP "ev_loop_fork (loop)" 4
364.IX Item "ev_loop_fork (loop)" 382.IX Item "ev_loop_fork (loop)"
365Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by 383Like \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 384\&\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. 385after fork, and how you do this is entirely your own problem.
368.IP "unsigned int ev_method (loop)" 4 386.IP "unsigned int ev_backend (loop)" 4
369.IX Item "unsigned int ev_method (loop)" 387.IX Item "unsigned int ev_backend (loop)"
370Returns one of the \f(CW\*(C`EVMETHOD_*\*(C'\fR flags indicating the event backend in 388Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
371use. 389use.
372.IP "ev_tstamp ev_now (loop)" 4 390.IP "ev_tstamp ev_now (loop)" 4
373.IX Item "ev_tstamp ev_now (loop)" 391.IX Item "ev_tstamp ev_now (loop)"
374Returns the current \*(L"event loop time\*(R", which is the time the event loop 392Returns 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 393got events and started processing them. This timestamp does not change
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482*)\*(C'\fR), and you can stop watching for events at any time by calling the 500*)\*(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. 501corresponding stop function (\f(CW\*(C`ev_<type>_stop (loop, watcher *)\*(C'\fR.
484.PP 502.PP
485As long as your watcher is active (has been started but not stopped) you 503As 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 504must not touch the values stored in it. Most specifically you must never
487reinitialise it or call its set method. 505reinitialise it or call its set macro.
488.PP 506.PP
489You can check whether an event is active by calling the \f(CW\*(C`ev_is_active 507You 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 508(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 509callback for it has not been called yet) you can use the \f(CW\*(C`ev_is_pending
492(watcher *)\*(C'\fR macro. 510(watcher *)\*(C'\fR macro.
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612descriptors correctly if you register interest in two or more fds pointing 630descriptors correctly if you register interest in two or more fds pointing
613to the same underlying file/socket etc. description (that is, they share 631to the same underlying file/socket etc. description (that is, they share
614the same underlying \*(L"file open\*(R"). 632the same underlying \*(L"file open\*(R").
615.PP 633.PP
616If you must do this, then force the use of a known-to-be-good backend 634If 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 635(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and
618\&\s-1EVMETHOD_POLL\s0). 636\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR).
619.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 637.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)" 638.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
621.PD 0 639.PD 0
622.IP "ev_io_set (ev_io *, int fd, int events)" 4 640.IP "ev_io_set (ev_io *, int fd, int events)" 4
623.IX Item "ev_io_set (ev_io *, int fd, int events)" 641.IX Item "ev_io_set (ev_io *, int fd, int events)"

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