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Revision 1.30 by root, Fri Nov 23 04:36:03 2007 UTC vs.
Revision 1.31 by root, Fri Nov 23 05:00:45 2007 UTC

75Usually, it's a good idea to terminate if the major versions mismatch, 75Usually, it's a good idea to terminate if the major versions mismatch,
76as this indicates an incompatible change. Minor versions are usually 76as this indicates an incompatible change. Minor versions are usually
77compatible to older versions, so a larger minor version alone is usually 77compatible to older versions, so a larger minor version alone is usually
78not a problem. 78not a problem.
79 79
80=item unsigned int ev_supported_backends ()
81
82Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*>
83value) compiled into this binary of libev (independent of their
84availability on the system you are running on). See C<ev_default_loop> for
85a description of the set values.
86
87=item unsigned int ev_recommended_backends ()
88
89Return the set of all backends compiled into this binary of libev and also
90recommended for this platform. This set is often smaller than the one
91returned by C<ev_supported_backends>, as for example kqueue is broken on
92most BSDs and will not be autodetected unless you explicitly request it
93(assuming you know what you are doing). This is the set of backends that
94C<EVFLAG_AUTO> will probe for.
95
80=item ev_set_allocator (void *(*cb)(void *ptr, long size)) 96=item ev_set_allocator (void *(*cb)(void *ptr, long size))
81 97
82Sets the allocation function to use (the prototype is similar to the 98Sets the allocation function to use (the prototype is similar to the
83realloc C function, the semantics are identical). It is used to allocate 99realloc C function, the semantics are identical). It is used to allocate
84and free memory (no surprises here). If it returns zero when memory 100and free memory (no surprises here). If it returns zero when memory
119=item struct ev_loop *ev_default_loop (unsigned int flags) 135=item struct ev_loop *ev_default_loop (unsigned int flags)
120 136
121This will initialise the default event loop if it hasn't been initialised 137This will initialise the default event loop if it hasn't been initialised
122yet and return it. If the default loop could not be initialised, returns 138yet and return it. If the default loop could not be initialised, returns
123false. If it already was initialised it simply returns it (and ignores the 139false. If it already was initialised it simply returns it (and ignores the
124flags). 140flags. If that is troubling you, check C<ev_backend ()> afterwards).
125 141
126If you don't know what event loop to use, use the one returned from this 142If you don't know what event loop to use, use the one returned from this
127function. 143function.
128 144
129The flags argument can be used to specify special behaviour or specific 145The flags argument can be used to specify special behaviour or specific
130backends to use, and is usually specified as 0 (or EVFLAG_AUTO). 146backends to use, and is usually specified as C<0> (or EVFLAG_AUTO).
131 147
132It supports the following flags: 148It supports the following flags:
133 149
134=over 4 150=over 4
135 151
145C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will 161C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
146override the flags completely if it is found in the environment. This is 162override the flags completely if it is found in the environment. This is
147useful to try out specific backends to test their performance, or to work 163useful to try out specific backends to test their performance, or to work
148around bugs. 164around bugs.
149 165
150=item C<EVMETHOD_SELECT> (value 1, portable select backend) 166=item C<EVBACKEND_SELECT> (value 1, portable select backend)
151 167
152This is your standard select(2) backend. Not I<completely> standard, as 168This is your standard select(2) backend. Not I<completely> standard, as
153libev tries to roll its own fd_set with no limits on the number of fds, 169libev tries to roll its own fd_set with no limits on the number of fds,
154but if that fails, expect a fairly low limit on the number of fds when 170but if that fails, expect a fairly low limit on the number of fds when
155using this backend. It doesn't scale too well (O(highest_fd)), but its usually 171using this backend. It doesn't scale too well (O(highest_fd)), but its usually
156the fastest backend for a low number of fds. 172the fastest backend for a low number of fds.
157 173
158=item C<EVMETHOD_POLL> (value 2, poll backend, available everywhere except on windows) 174=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)
159 175
160And this is your standard poll(2) backend. It's more complicated than 176And this is your standard poll(2) backend. It's more complicated than
161select, but handles sparse fds better and has no artificial limit on the 177select, but handles sparse fds better and has no artificial limit on the
162number of fds you can use (except it will slow down considerably with a 178number of fds you can use (except it will slow down considerably with a
163lot of inactive fds). It scales similarly to select, i.e. O(total_fds). 179lot of inactive fds). It scales similarly to select, i.e. O(total_fds).
164 180
165=item C<EVMETHOD_EPOLL> (value 4, Linux) 181=item C<EVBACKEND_EPOLL> (value 4, Linux)
166 182
167For few fds, this backend is a bit little slower than poll and select, 183For few fds, this backend is a bit little slower than poll and select,
168but it scales phenomenally better. While poll and select usually scale like 184but it scales phenomenally better. While poll and select usually scale like
169O(total_fds) where n is the total number of fds (or the highest fd), epoll scales 185O(total_fds) where n is the total number of fds (or the highest fd), epoll scales
170either O(1) or O(active_fds). 186either O(1) or O(active_fds).
173result in some caching, there is still a syscall per such incident 189result in some caching, there is still a syscall per such incident
174(because the fd could point to a different file description now), so its 190(because the fd could point to a different file description now), so its
175best to avoid that. Also, dup()ed file descriptors might not work very 191best to avoid that. Also, dup()ed file descriptors might not work very
176well if you register events for both fds. 192well if you register events for both fds.
177 193
178=item C<EVMETHOD_KQUEUE> (value 8, most BSD clones) 194=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
179 195
180Kqueue deserves special mention, as at the time of this writing, it 196Kqueue deserves special mention, as at the time of this writing, it
181was broken on all BSDs except NetBSD (usually it doesn't work with 197was broken on all BSDs except NetBSD (usually it doesn't work with
182anything but sockets and pipes, except on Darwin, where of course its 198anything but sockets and pipes, except on Darwin, where of course its
183completely useless). For this reason its not being "autodetected" unless 199completely useless). For this reason its not being "autodetected" unless
187kernel is more efficient (which says nothing about its actual speed, of 203kernel is more efficient (which says nothing about its actual speed, of
188course). While starting and stopping an I/O watcher does not cause an 204course). While starting and stopping an I/O watcher does not cause an
189extra syscall as with epoll, it still adds up to four event changes per 205extra syscall as with epoll, it still adds up to four event changes per
190incident, so its best to avoid that. 206incident, so its best to avoid that.
191 207
192=item C<EVMETHOD_DEVPOLL> (value 16, Solaris 8) 208=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
193 209
194This is not implemented yet (and might never be). 210This is not implemented yet (and might never be).
195 211
196=item C<EVMETHOD_PORT> (value 32, Solaris 10) 212=item C<EVBACKEND_PORT> (value 32, Solaris 10)
197 213
198This uses the Solaris 10 port mechanism. As with everything on Solaris, 214This uses the Solaris 10 port mechanism. As with everything on Solaris,
199it's really slow, but it still scales very well (O(active_fds)). 215it's really slow, but it still scales very well (O(active_fds)).
200 216
201=item C<EVMETHOD_ALL> 217=item C<EVBACKEND_ALL>
202 218
203Try all backends (even potentially broken ones that wouldn't be tried 219Try all backends (even potentially broken ones that wouldn't be tried
204with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as 220with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
205C<EVMETHOD_ALL & ~EVMETHOD_KQUEUE>. 221C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
206 222
207=back 223=back
208 224
209If one or more of these are ored into the flags value, then only these 225If one or more of these are ored into the flags value, then only these
210backends will be tried (in the reverse order as given here). If none are 226backends will be tried (in the reverse order as given here). If none are
244it just in case after a fork. To make this easy, the function will fit in 260it just in case after a fork. To make this easy, the function will fit in
245quite nicely into a call to C<pthread_atfork>: 261quite nicely into a call to C<pthread_atfork>:
246 262
247 pthread_atfork (0, 0, ev_default_fork); 263 pthread_atfork (0, 0, ev_default_fork);
248 264
265At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use
266without calling this function, so if you force one of those backends you
267do not need to care.
268
249=item ev_loop_fork (loop) 269=item ev_loop_fork (loop)
250 270
251Like C<ev_default_fork>, but acts on an event loop created by 271Like C<ev_default_fork>, but acts on an event loop created by
252C<ev_loop_new>. Yes, you have to call this on every allocated event loop 272C<ev_loop_new>. Yes, you have to call this on every allocated event loop
253after fork, and how you do this is entirely your own problem. 273after fork, and how you do this is entirely your own problem.
254 274
255=item unsigned int ev_method (loop) 275=item unsigned int ev_backend (loop)
256 276
257Returns one of the C<EVMETHOD_*> flags indicating the event backend in 277Returns one of the C<EVBACKEND_*> flags indicating the event backend in
258use. 278use.
259 279
260=item ev_tstamp ev_now (loop) 280=item ev_tstamp ev_now (loop)
261 281
262Returns the current "event loop time", which is the time the event loop 282Returns the current "event loop time", which is the time the event loop
368*) >>), and you can stop watching for events at any time by calling the 388*) >>), and you can stop watching for events at any time by calling the
369corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. 389corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>.
370 390
371As long as your watcher is active (has been started but not stopped) you 391As long as your watcher is active (has been started but not stopped) you
372must not touch the values stored in it. Most specifically you must never 392must not touch the values stored in it. Most specifically you must never
373reinitialise it or call its set method. 393reinitialise it or call its set macro.
374 394
375You can check whether an event is active by calling the C<ev_is_active 395You can check whether an event is active by calling the C<ev_is_active
376(watcher *)> macro. To see whether an event is outstanding (but the 396(watcher *)> macro. To see whether an event is outstanding (but the
377callback for it has not been called yet) you can use the C<ev_is_pending 397callback for it has not been called yet) you can use the C<ev_is_pending
378(watcher *)> macro. 398(watcher *)> macro.
495descriptors correctly if you register interest in two or more fds pointing 515descriptors correctly if you register interest in two or more fds pointing
496to the same underlying file/socket etc. description (that is, they share 516to the same underlying file/socket etc. description (that is, they share
497the same underlying "file open"). 517the same underlying "file open").
498 518
499If you must do this, then force the use of a known-to-be-good backend 519If you must do this, then force the use of a known-to-be-good backend
500(at the time of this writing, this includes only EVMETHOD_SELECT and 520(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
501EVMETHOD_POLL). 521C<EVBACKEND_POLL>).
502 522
503=over 4 523=over 4
504 524
505=item ev_io_init (ev_io *, callback, int fd, int events) 525=item ev_io_init (ev_io *, callback, int fd, int events)
506 526

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