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Comparing libev/ev.3 (file contents):
Revision 1.7 by root, Fri Nov 23 08:36:35 2007 UTC vs.
Revision 1.8 by root, Fri Nov 23 15:26:08 2007 UTC

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212Return the set of all backends compiled into this binary of libev and also 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 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 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 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 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. 217libev will probe for if you specify no backends explicitly.
218.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 218.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4
219.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" 219.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"
220Sets the allocation function to use (the prototype is similar to the 220Sets the allocation function to use (the prototype is similar to the
221realloc C function, the semantics are identical). It is used to allocate 221realloc C function, the semantics are identical). It is used to allocate
222and 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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256.Sp 256.Sp
257If 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
258function. 258function.
259.Sp 259.Sp
260The flags argument can be used to specify special behaviour or specific 260The 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). 261backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR).
262.Sp 262.Sp
263It supports the following flags: 263The following flags are supported:
264.RS 4 264.RS 4
265.ie n .IP """EVFLAG_AUTO""" 4 265.ie n .IP """EVFLAG_AUTO""" 4
266.el .IP "\f(CWEVFLAG_AUTO\fR" 4 266.el .IP "\f(CWEVFLAG_AUTO\fR" 4
267.IX Item "EVFLAG_AUTO" 267.IX Item "EVFLAG_AUTO"
268The 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
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312.el .IP "\f(CWEVBACKEND_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
313.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" 313.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"
314Kqueue deserves special mention, as at the time of this writing, it 314Kqueue deserves special mention, as at the time of this writing, it
315was 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
316anything but sockets and pipes, except on Darwin, where of course its 316anything but sockets and pipes, except on Darwin, where of course its
317completely useless). For this reason its not being \*(L"autodetected\*(R" unless 317completely useless). For this reason its not being \*(L"autodetected\*(R"
318you 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).
319.Sp 320.Sp
320It 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
321kernel is more efficient (which says nothing about its actual speed, of 322kernel is more efficient (which says nothing about its actual speed, of
322course). 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
323extra 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
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346.Sp 347.Sp
347If 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
348backends 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
349specified, most compiled-in backend will be tried, usually in reverse 350specified, most compiled-in backend will be tried, usually in reverse
350order 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
351.RE 374.RE
352.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 375.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4
353.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" 376.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)"
354Similar 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
355always distinct from the default loop. Unlike the default loop, it cannot 378always distinct from the default loop. Unlike the default loop, it cannot
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406.IX Item "ev_loop (loop, int flags)" 429.IX Item "ev_loop (loop, int flags)"
407Finally, this is it, the event handler. This function usually is called 430Finally, this is it, the event handler. This function usually is called
408after you initialised all your watchers and you want to start handling 431after you initialised all your watchers and you want to start handling
409events. 432events.
410.Sp 433.Sp
411If 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
412no 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.
413.Sp 436.Sp
414A 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
415those 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
416case 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.
417.Sp 440.Sp
418A 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
419neccessary) and will handle those and any outstanding ones. It will block 442neccessary) and will handle those and any outstanding ones. It will block
420your 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
421one 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.
422.Sp 448.Sp
423This flags value could be used to implement alternative looping
424constructs, but the \f(CW\*(C`prepare\*(C'\fR and \f(CW\*(C`check\*(C'\fR watchers provide a better and
425more generic mechanism.
426.Sp
427Here are the gory details of what ev_loop does: 449Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does:
428.Sp 450.Sp
429.Vb 15 451.Vb 18
430\& 1. If there are no active watchers (reference count is zero), return. 452\& * If there are no active watchers (reference count is zero), return.
431\& 2. Queue and immediately call all prepare watchers. 453\& - Queue prepare watchers and then call all outstanding watchers.
432\& 3. If we have been forked, recreate the kernel state. 454\& - If we have been forked, recreate the kernel state.
433\& 4. Update the kernel state with all outstanding changes. 455\& - Update the kernel state with all outstanding changes.
434\& 5. Update the "event loop time". 456\& - Update the "event loop time".
435\& 6. Calculate for how long to block. 457\& - Calculate for how long to block.
436\& 7. Block the process, waiting for events. 458\& - Block the process, waiting for any events.
459\& - Queue all outstanding I/O (fd) events.
437\& 8. Update the "event loop time" and do time jump handling. 460\& - Update the "event loop time" and do time jump handling.
438\& 9. Queue all outstanding timers. 461\& - Queue all outstanding timers.
439\& 10. Queue all outstanding periodics. 462\& - Queue all outstanding periodics.
440\& 11. If no events are pending now, queue all idle watchers. 463\& - If no events are pending now, queue all idle watchers.
441\& 12. Queue all check watchers. 464\& - Queue all check watchers.
442\& 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.
443\& 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
444\& was used, return, otherwise continue with step #1. 469\& were used, return, otherwise continue with step *.
445.Ve 470.Ve
446.IP "ev_unloop (loop, how)" 4 471.IP "ev_unloop (loop, how)" 4
447.IX Item "ev_unloop (loop, how)" 472.IX Item "ev_unloop (loop, how)"
448Can 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
449has 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

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