[ViewVC] Diff of: cvs/libev/ev.pod

Comparing libev/ev.pod (file contents):
Revision 1.266 by root, Wed Aug 26 17:15:05 2009 UTC vs.
Revision 1.306 by root, Mon Oct 18 07:36:05 2010 UTC

…		…
75	While this document tries to be as complete as possible in documenting	75	While this document tries to be as complete as possible in documenting
76	libev, its usage and the rationale behind its design, it is not a tutorial	76	libev, its usage and the rationale behind its design, it is not a tutorial
77	on event-based programming, nor will it introduce event-based programming	77	on event-based programming, nor will it introduce event-based programming
78	with libev.	78	with libev.
79		79
80	Familarity with event based programming techniques in general is assumed	80	Familiarity with event based programming techniques in general is assumed
81	throughout this document.	81	throughout this document.
82		82
83	=head1 ABOUT LIBEV	83	=head1 ABOUT LIBEV
84		84
85	Libev is an event loop: you register interest in certain events (such as a	85	Libev is an event loop: you register interest in certain events (such as a
…		…
118	Libev is very configurable. In this manual the default (and most common)	118	Libev is very configurable. In this manual the default (and most common)
119	configuration will be described, which supports multiple event loops. For	119	configuration will be described, which supports multiple event loops. For
120	more info about various configuration options please have a look at	120	more info about various configuration options please have a look at
121	B<EMBED> section in this manual. If libev was configured without support	121	B<EMBED> section in this manual. If libev was configured without support
122	for multiple event loops, then all functions taking an initial argument of	122	for multiple event loops, then all functions taking an initial argument of
123	name C<loop> (which is always of type C<ev_loop *>) will not have	123	name C<loop> (which is always of type C<struct ev_loop *>) will not have
124	this argument.	124	this argument.
125		125
126	=head2 TIME REPRESENTATION	126	=head2 TIME REPRESENTATION
127		127
128	Libev represents time as a single floating point number, representing	128	Libev represents time as a single floating point number, representing
129	the (fractional) number of seconds since the (POSIX) epoch (somewhere	129	the (fractional) number of seconds since the (POSIX) epoch (in practise
130	near the beginning of 1970, details are complicated, don't ask). This	130	somewhere near the beginning of 1970, details are complicated, don't
131	type is called C<ev_tstamp>, which is what you should use too. It usually	131	ask). This type is called C<ev_tstamp>, which is what you should use
132	aliases to the C<double> type in C. When you need to do any calculations	132	too. It usually aliases to the C<double> type in C. When you need to do
133	on it, you should treat it as some floating point value. Unlike the name	133	any calculations on it, you should treat it as some floating point value.
		134
134	component C<stamp> might indicate, it is also used for time differences	135	Unlike the name component C<stamp> might indicate, it is also used for
135	throughout libev.	136	time differences (e.g. delays) throughout libev.
136		137
137	=head1 ERROR HANDLING	138	=head1 ERROR HANDLING
138		139
139	Libev knows three classes of errors: operating system errors, usage errors	140	Libev knows three classes of errors: operating system errors, usage errors
140	and internal errors (bugs).	141	and internal errors (bugs).
…		…
191	as this indicates an incompatible change. Minor versions are usually	192	as this indicates an incompatible change. Minor versions are usually
192	compatible to older versions, so a larger minor version alone is usually	193	compatible to older versions, so a larger minor version alone is usually
193	not a problem.	194	not a problem.
194		195
195	Example: Make sure we haven't accidentally been linked against the wrong	196	Example: Make sure we haven't accidentally been linked against the wrong
196	version.	197	version (note, however, that this will not detect ABI mismatches :).
197		198
198	assert (("libev version mismatch",	199	assert (("libev version mismatch",
199	ev_version_major () == EV_VERSION_MAJOR	200	ev_version_major () == EV_VERSION_MAJOR
200	&& ev_version_minor () >= EV_VERSION_MINOR));	201	&& ev_version_minor () >= EV_VERSION_MINOR));
201		202
…		…
345	useful to try out specific backends to test their performance, or to work	346	useful to try out specific backends to test their performance, or to work
346	around bugs.	347	around bugs.
347		348
348	=item C<EVFLAG_FORKCHECK>	349	=item C<EVFLAG_FORKCHECK>
349		350
350	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after	351	Instead of calling C<ev_loop_fork> manually after a fork, you can also
351	a fork, you can also make libev check for a fork in each iteration by	352	make libev check for a fork in each iteration by enabling this flag.
352	enabling this flag.
353		353
354	This works by calling C<getpid ()> on every iteration of the loop,	354	This works by calling C<getpid ()> on every iteration of the loop,
355	and thus this might slow down your event loop if you do a lot of loop	355	and thus this might slow down your event loop if you do a lot of loop
356	iterations and little real work, but is usually not noticeable (on my	356	iterations and little real work, but is usually not noticeable (on my
357	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence	357	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
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370	When this flag is specified, then libev will not attempt to use the	370	When this flag is specified, then libev will not attempt to use the
371	I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and	371	I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and
372	testing, this flag can be useful to conserve inotify file descriptors, as	372	testing, this flag can be useful to conserve inotify file descriptors, as
373	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.	373	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
374		374
375	=item C<EVFLAG_NOSIGNALFD>	375	=item C<EVFLAG_SIGNALFD>
376		376
377	When this flag is specified, then libev will not attempt to use the	377	When this flag is specified, then libev will attempt to use the
378	I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This is	378	I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API
379	probably only useful to work around any bugs in libev. Consequently, this	379	delivers signals synchronously, which makes it both faster and might make
380	flag might go away once the signalfd functionality is considered stable,	380	it possible to get the queued signal data. It can also simplify signal
381	so it's useful mostly in environment variables and not in program code.	381	handling with threads, as long as you properly block signals in your
		382	threads that are not interested in handling them.
		383
		384	Signalfd will not be used by default as this changes your signal mask, and
		385	there are a lot of shoddy libraries and programs (glib's threadpool for
		386	example) that can't properly initialise their signal masks.
382		387
383	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	388	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
384		389
385	This is your standard select(2) backend. Not I<completely> standard, as	390	This is your standard select(2) backend. Not I<completely> standard, as
386	libev tries to roll its own fd_set with no limits on the number of fds,	391	libev tries to roll its own fd_set with no limits on the number of fds,
…		…
410		415
411	This backend maps C<EV_READ> to C<POLLIN \| POLLERR \| POLLHUP>, and	416	This backend maps C<EV_READ> to C<POLLIN \| POLLERR \| POLLHUP>, and
412	C<EV_WRITE> to C<POLLOUT \| POLLERR \| POLLHUP>.	417	C<EV_WRITE> to C<POLLOUT \| POLLERR \| POLLHUP>.
413		418
414	=item C<EVBACKEND_EPOLL> (value 4, Linux)	419	=item C<EVBACKEND_EPOLL> (value 4, Linux)
		420
		421	Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9
		422	kernels).
415		423
416	For few fds, this backend is a bit little slower than poll and select,	424	For few fds, this backend is a bit little slower than poll and select,
417	but it scales phenomenally better. While poll and select usually scale	425	but it scales phenomenally better. While poll and select usually scale
418	like O(total_fds) where n is the total number of fds (or the highest fd),	426	like O(total_fds) where n is the total number of fds (or the highest fd),
419	epoll scales either O(1) or O(active_fds).	427	epoll scales either O(1) or O(active_fds).
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431	of course I<doesn't>, and epoll just loves to report events for totally	439	of course I<doesn't>, and epoll just loves to report events for totally
432	I<different> file descriptors (even already closed ones, so one cannot	440	I<different> file descriptors (even already closed ones, so one cannot
433	even remove them from the set) than registered in the set (especially	441	even remove them from the set) than registered in the set (especially
434	on SMP systems). Libev tries to counter these spurious notifications by	442	on SMP systems). Libev tries to counter these spurious notifications by
435	employing an additional generation counter and comparing that against the	443	employing an additional generation counter and comparing that against the
436	events to filter out spurious ones, recreating the set when required.	444	events to filter out spurious ones, recreating the set when required. Last
		445	not least, it also refuses to work with some file descriptors which work
		446	perfectly fine with C<select> (files, many character devices...).
437		447
438	While stopping, setting and starting an I/O watcher in the same iteration	448	While stopping, setting and starting an I/O watcher in the same iteration
439	will result in some caching, there is still a system call per such	449	will result in some caching, there is still a system call per such
440	incident (because the same I<file descriptor> could point to a different	450	incident (because the same I<file descriptor> could point to a different
441	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed	451	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
559	ev_default_loop (ev_recommended_backends () \| EVBACKEND_KQUEUE);	569	ev_default_loop (ev_recommended_backends () \| EVBACKEND_KQUEUE);
560		570
561	=item struct ev_loop *ev_loop_new (unsigned int flags)	571	=item struct ev_loop *ev_loop_new (unsigned int flags)
562		572
563	Similar to C<ev_default_loop>, but always creates a new event loop that is	573	Similar to C<ev_default_loop>, but always creates a new event loop that is
564	always distinct from the default loop. Unlike the default loop, it cannot	574	always distinct from the default loop.
565	handle signal and child watchers, and attempts to do so will be greeted by
566	undefined behaviour (or a failed assertion if assertions are enabled).
567		575
568	Note that this function I<is> thread-safe, and the recommended way to use	576	Note that this function I<is> thread-safe, and one common way to use
569	libev with threads is indeed to create one loop per thread, and using the	577	libev with threads is indeed to create one loop per thread, and using the
570	default loop in the "main" or "initial" thread.	578	default loop in the "main" or "initial" thread.
571		579
572	Example: Try to create a event loop that uses epoll and nothing else.	580	Example: Try to create a event loop that uses epoll and nothing else.
573		581
…		…
575	if (!epoller)	583	if (!epoller)
576	fatal ("no epoll found here, maybe it hides under your chair");	584	fatal ("no epoll found here, maybe it hides under your chair");
577		585
578	=item ev_default_destroy ()	586	=item ev_default_destroy ()
579		587
580	Destroys the default loop again (frees all memory and kernel state	588	Destroys the default loop (frees all memory and kernel state etc.). None
581	etc.). None of the active event watchers will be stopped in the normal	589	of the active event watchers will be stopped in the normal sense, so
582	sense, so e.g. C<ev_is_active> might still return true. It is your	590	e.g. C<ev_is_active> might still return true. It is your responsibility to
583	responsibility to either stop all watchers cleanly yourself I<before>	591	either stop all watchers cleanly yourself I<before> calling this function,
584	calling this function, or cope with the fact afterwards (which is usually	592	or cope with the fact afterwards (which is usually the easiest thing, you
585	the easiest thing, you can just ignore the watchers and/or C<free ()> them	593	can just ignore the watchers and/or C<free ()> them for example).
586	for example).
587		594
588	Note that certain global state, such as signal state (and installed signal	595	Note that certain global state, such as signal state (and installed signal
589	handlers), will not be freed by this function, and related watchers (such	596	handlers), will not be freed by this function, and related watchers (such
590	as signal and child watchers) would need to be stopped manually.	597	as signal and child watchers) would need to be stopped manually.
591		598
592	In general it is not advisable to call this function except in the	599	In general it is not advisable to call this function except in the
593	rare occasion where you really need to free e.g. the signal handling	600	rare occasion where you really need to free e.g. the signal handling
594	pipe fds. If you need dynamically allocated loops it is better to use	601	pipe fds. If you need dynamically allocated loops it is better to use
595	C<ev_loop_new> and C<ev_loop_destroy>).	602	C<ev_loop_new> and C<ev_loop_destroy>.
596		603
597	=item ev_loop_destroy (loop)	604	=item ev_loop_destroy (loop)
598		605
599	Like C<ev_default_destroy>, but destroys an event loop created by an	606	Like C<ev_default_destroy>, but destroys an event loop created by an
600	earlier call to C<ev_loop_new>.	607	earlier call to C<ev_loop_new>.
…		…
606	name, you can call it anytime, but it makes most sense after forking, in	613	name, you can call it anytime, but it makes most sense after forking, in
607	the child process (or both child and parent, but that again makes little	614	the child process (or both child and parent, but that again makes little
608	sense). You I<must> call it in the child before using any of the libev	615	sense). You I<must> call it in the child before using any of the libev
609	functions, and it will only take effect at the next C<ev_loop> iteration.	616	functions, and it will only take effect at the next C<ev_loop> iteration.
610		617
		618	Again, you I<have> to call it on I<any> loop that you want to re-use after
		619	a fork, I<even if you do not plan to use the loop in the parent>. This is
		620	because some kernel interfaces cough I<kqueue> cough do funny things
		621	during fork.
		622
611	On the other hand, you only need to call this function in the child	623	On the other hand, you only need to call this function in the child
612	process if and only if you want to use the event library in the child. If	624	process if and only if you want to use the event loop in the child. If you
613	you just fork+exec, you don't have to call it at all.	625	just fork+exec or create a new loop in the child, you don't have to call
		626	it at all.
614		627
615	The function itself is quite fast and it's usually not a problem to call	628	The function itself is quite fast and it's usually not a problem to call
616	it just in case after a fork. To make this easy, the function will fit in	629	it just in case after a fork. To make this easy, the function will fit in
617	quite nicely into a call to C<pthread_atfork>:	630	quite nicely into a call to C<pthread_atfork>:
618		631
…		…
620		633
621	=item ev_loop_fork (loop)	634	=item ev_loop_fork (loop)
622		635
623	Like C<ev_default_fork>, but acts on an event loop created by	636	Like C<ev_default_fork>, but acts on an event loop created by
624	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	637	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
625	after fork that you want to re-use in the child, and how you do this is	638	after fork that you want to re-use in the child, and how you keep track of
626	entirely your own problem.	639	them is entirely your own problem.
627		640
628	=item int ev_is_default_loop (loop)	641	=item int ev_is_default_loop (loop)
629		642
630	Returns true when the given loop is, in fact, the default loop, and false	643	Returns true when the given loop is, in fact, the default loop, and false
631	otherwise.	644	otherwise.
632		645
633	=item unsigned int ev_loop_count (loop)	646	=item unsigned int ev_iteration (loop)
634		647
635	Returns the count of loop iterations for the loop, which is identical to	648	Returns the current iteration count for the loop, which is identical to
636	the number of times libev did poll for new events. It starts at C<0> and	649	the number of times libev did poll for new events. It starts at C<0> and
637	happily wraps around with enough iterations.	650	happily wraps around with enough iterations.
638		651
639	This value can sometimes be useful as a generation counter of sorts (it	652	This value can sometimes be useful as a generation counter of sorts (it
640	"ticks" the number of loop iterations), as it roughly corresponds with	653	"ticks" the number of loop iterations), as it roughly corresponds with
641	C<ev_prepare> and C<ev_check> calls.	654	C<ev_prepare> and C<ev_check> calls - and is incremented between the
		655	prepare and check phases.
642		656
643	=item unsigned int ev_loop_depth (loop)	657	=item unsigned int ev_depth (loop)
644		658
645	Returns the number of times C<ev_loop> was entered minus the number of	659	Returns the number of times C<ev_loop> was entered minus the number of
646	times C<ev_loop> was exited, in other words, the recursion depth.	660	times C<ev_loop> was exited, in other words, the recursion depth.
647		661
648	Outside C<ev_loop>, this number is zero. In a callback, this number is	662	Outside C<ev_loop>, this number is zero. In a callback, this number is
649	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),	663	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),
650	in which case it is higher.	664	in which case it is higher.
651		665
652	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	666	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread
653	etc.), doesn't count as exit.	667	etc.), doesn't count as "exit" - consider this as a hint to avoid such
		668	ungentleman behaviour unless it's really convenient.
654		669
655	=item unsigned int ev_backend (loop)	670	=item unsigned int ev_backend (loop)
656		671
657	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	672	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
658	use.	673	use.
…		…
692	C<ev_resume> directly afterwards to resume timer processing.	707	C<ev_resume> directly afterwards to resume timer processing.
693		708
694	Effectively, all C<ev_timer> watchers will be delayed by the time spend	709	Effectively, all C<ev_timer> watchers will be delayed by the time spend
695	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers	710	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers
696	will be rescheduled (that is, they will lose any events that would have	711	will be rescheduled (that is, they will lose any events that would have
697	occured while suspended).	712	occurred while suspended).
698		713
699	After calling C<ev_suspend> you B<must not> call I<any> function on the	714	After calling C<ev_suspend> you B<must not> call I<any> function on the
700	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>	715	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>
701	without a previous call to C<ev_suspend>.	716	without a previous call to C<ev_suspend>.
702		717
…		…
704	event loop time (see C<ev_now_update>).	719	event loop time (see C<ev_now_update>).
705		720
706	=item ev_loop (loop, int flags)	721	=item ev_loop (loop, int flags)
707		722
708	Finally, this is it, the event handler. This function usually is called	723	Finally, this is it, the event handler. This function usually is called
709	after you initialised all your watchers and you want to start handling	724	after you have initialised all your watchers and you want to start
710	events.	725	handling events.
711		726
712	If the flags argument is specified as C<0>, it will not return until	727	If the flags argument is specified as C<0>, it will not return until
713	either no event watchers are active anymore or C<ev_unloop> was called.	728	either no event watchers are active anymore or C<ev_unloop> was called.
714		729
715	Please note that an explicit C<ev_unloop> is usually better than	730	Please note that an explicit C<ev_unloop> is usually better than
…		…
779	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	794	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or
780	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	795	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.
781		796
782	This "unloop state" will be cleared when entering C<ev_loop> again.	797	This "unloop state" will be cleared when entering C<ev_loop> again.
783		798
784	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	799	It is safe to call C<ev_unloop> from outside any C<ev_loop> calls.
785		800
786	=item ev_ref (loop)	801	=item ev_ref (loop)
787		802
788	=item ev_unref (loop)	803	=item ev_unref (loop)
789		804
790	Ref/unref can be used to add or remove a reference count on the event	805	Ref/unref can be used to add or remove a reference count on the event
791	loop: Every watcher keeps one reference, and as long as the reference	806	loop: Every watcher keeps one reference, and as long as the reference
792	count is nonzero, C<ev_loop> will not return on its own.	807	count is nonzero, C<ev_loop> will not return on its own.
793		808
794	If you have a watcher you never unregister that should not keep C<ev_loop>	809	This is useful when you have a watcher that you never intend to
795	from returning, call ev_unref() after starting, and ev_ref() before	810	unregister, but that nevertheless should not keep C<ev_loop> from
		811	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
796	stopping it.	812	before stopping it.
797		813
798	As an example, libev itself uses this for its internal signal pipe: It	814	As an example, libev itself uses this for its internal signal pipe: It
799	is not visible to the libev user and should not keep C<ev_loop> from	815	is not visible to the libev user and should not keep C<ev_loop> from
800	exiting if no event watchers registered by it are active. It is also an	816	exiting if no event watchers registered by it are active. It is also an
801	excellent way to do this for generic recurring timers or from within	817	excellent way to do this for generic recurring timers or from within
…		…
858	usually doesn't make much sense to set it to a lower value than C<0.01>,	874	usually doesn't make much sense to set it to a lower value than C<0.01>,
859	as this approaches the timing granularity of most systems. Note that if	875	as this approaches the timing granularity of most systems. Note that if
860	you do transactions with the outside world and you can't increase the	876	you do transactions with the outside world and you can't increase the
861	parallelity, then this setting will limit your transaction rate (if you	877	parallelity, then this setting will limit your transaction rate (if you
862	need to poll once per transaction and the I/O collect interval is 0.01,	878	need to poll once per transaction and the I/O collect interval is 0.01,
863	then you can't do more than 100 transations per second).	879	then you can't do more than 100 transactions per second).
864		880
865	Setting the I<timeout collect interval> can improve the opportunity for	881	Setting the I<timeout collect interval> can improve the opportunity for
866	saving power, as the program will "bundle" timer callback invocations that	882	saving power, as the program will "bundle" timer callback invocations that
867	are "near" in time together, by delaying some, thus reducing the number of	883	are "near" in time together, by delaying some, thus reducing the number of
868	times the process sleeps and wakes up again. Another useful technique to	884	times the process sleeps and wakes up again. Another useful technique to
…		…
916		932
917	While event loop modifications are allowed between invocations of	933	While event loop modifications are allowed between invocations of
918	C<release> and C<acquire> (that's their only purpose after all), no	934	C<release> and C<acquire> (that's their only purpose after all), no
919	modifications done will affect the event loop, i.e. adding watchers will	935	modifications done will affect the event loop, i.e. adding watchers will
920	have no effect on the set of file descriptors being watched, or the time	936	have no effect on the set of file descriptors being watched, or the time
921	waited. USe an C<ev_async> watcher to wake up C<ev_loop> when you want it	937	waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it
922	to take note of any changes you made.	938	to take note of any changes you made.
923		939
924	In theory, threads executing C<ev_loop> will be async-cancel safe between	940	In theory, threads executing C<ev_loop> will be async-cancel safe between
925	invocations of C<release> and C<acquire>.	941	invocations of C<release> and C<acquire>.
926		942
…		…
1023	=item C<EV_WRITE>	1039	=item C<EV_WRITE>
1024		1040
1025	The file descriptor in the C<ev_io> watcher has become readable and/or	1041	The file descriptor in the C<ev_io> watcher has become readable and/or
1026	writable.	1042	writable.
1027		1043
1028	=item C<EV_TIMEOUT>	1044	=item C<EV_TIMER>
1029		1045
1030	The C<ev_timer> watcher has timed out.	1046	The C<ev_timer> watcher has timed out.
1031		1047
1032	=item C<EV_PERIODIC>	1048	=item C<EV_PERIODIC>
1033		1049
…		…
1123		1139
1124	ev_io w;	1140	ev_io w;
1125	ev_init (&w, my_cb);	1141	ev_init (&w, my_cb);
1126	ev_io_set (&w, STDIN_FILENO, EV_READ);	1142	ev_io_set (&w, STDIN_FILENO, EV_READ);
1127		1143
1128	=item C<ev_TYPE_set> (ev_TYPE *, [args])	1144	=item C<ev_TYPE_set> (ev_TYPE *watcher, [args])
1129		1145
1130	This macro initialises the type-specific parts of a watcher. You need to	1146	This macro initialises the type-specific parts of a watcher. You need to
1131	call C<ev_init> at least once before you call this macro, but you can	1147	call C<ev_init> at least once before you call this macro, but you can
1132	call C<ev_TYPE_set> any number of times. You must not, however, call this	1148	call C<ev_TYPE_set> any number of times. You must not, however, call this
1133	macro on a watcher that is active (it can be pending, however, which is a	1149	macro on a watcher that is active (it can be pending, however, which is a
…		…
1146		1162
1147	Example: Initialise and set an C<ev_io> watcher in one step.	1163	Example: Initialise and set an C<ev_io> watcher in one step.
1148		1164
1149	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);	1165	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);
1150		1166
1151	=item C<ev_TYPE_start> (loop , ev_TYPE watcher)	1167	=item C<ev_TYPE_start> (loop, ev_TYPE *watcher)
1152		1168
1153	Starts (activates) the given watcher. Only active watchers will receive	1169	Starts (activates) the given watcher. Only active watchers will receive
1154	events. If the watcher is already active nothing will happen.	1170	events. If the watcher is already active nothing will happen.
1155		1171
1156	Example: Start the C<ev_io> watcher that is being abused as example in this	1172	Example: Start the C<ev_io> watcher that is being abused as example in this
1157	whole section.	1173	whole section.
1158		1174
1159	ev_io_start (EV_DEFAULT_UC, &w);	1175	ev_io_start (EV_DEFAULT_UC, &w);
1160		1176
1161	=item C<ev_TYPE_stop> (loop , ev_TYPE watcher)	1177	=item C<ev_TYPE_stop> (loop, ev_TYPE *watcher)
1162		1178
1163	Stops the given watcher if active, and clears the pending status (whether	1179	Stops the given watcher if active, and clears the pending status (whether
1164	the watcher was active or not).	1180	the watcher was active or not).
1165		1181
1166	It is possible that stopped watchers are pending - for example,	1182	It is possible that stopped watchers are pending - for example,
…		…
1191	=item ev_cb_set (ev_TYPE *watcher, callback)	1207	=item ev_cb_set (ev_TYPE *watcher, callback)
1192		1208
1193	Change the callback. You can change the callback at virtually any time	1209	Change the callback. You can change the callback at virtually any time
1194	(modulo threads).	1210	(modulo threads).
1195		1211
1196	=item ev_set_priority (ev_TYPE *watcher, priority)	1212	=item ev_set_priority (ev_TYPE *watcher, int priority)
1197		1213
1198	=item int ev_priority (ev_TYPE *watcher)	1214	=item int ev_priority (ev_TYPE *watcher)
1199		1215
1200	Set and query the priority of the watcher. The priority is a small	1216	Set and query the priority of the watcher. The priority is a small
1201	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>	1217	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
…		…
1232	returns its C<revents> bitset (as if its callback was invoked). If the	1248	returns its C<revents> bitset (as if its callback was invoked). If the
1233	watcher isn't pending it does nothing and returns C<0>.	1249	watcher isn't pending it does nothing and returns C<0>.
1234		1250
1235	Sometimes it can be useful to "poll" a watcher instead of waiting for its	1251	Sometimes it can be useful to "poll" a watcher instead of waiting for its
1236	callback to be invoked, which can be accomplished with this function.	1252	callback to be invoked, which can be accomplished with this function.
		1253
		1254	=item ev_feed_event (loop, ev_TYPE *watcher, int revents)
		1255
		1256	Feeds the given event set into the event loop, as if the specified event
		1257	had happened for the specified watcher (which must be a pointer to an
		1258	initialised but not necessarily started event watcher). Obviously you must
		1259	not free the watcher as long as it has pending events.
		1260
		1261	Stopping the watcher, letting libev invoke it, or calling
		1262	C<ev_clear_pending> will clear the pending event, even if the watcher was
		1263	not started in the first place.
		1264
		1265	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
		1266	functions that do not need a watcher.
1237		1267
1238	=back	1268	=back
1239		1269
1240		1270
1241	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1271	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
1352		1382
1353	For example, to emulate how many other event libraries handle priorities,	1383	For example, to emulate how many other event libraries handle priorities,
1354	you can associate an C<ev_idle> watcher to each such watcher, and in	1384	you can associate an C<ev_idle> watcher to each such watcher, and in
1355	the normal watcher callback, you just start the idle watcher. The real	1385	the normal watcher callback, you just start the idle watcher. The real
1356	processing is done in the idle watcher callback. This causes libev to	1386	processing is done in the idle watcher callback. This causes libev to
1357	continously poll and process kernel event data for the watcher, but when	1387	continuously poll and process kernel event data for the watcher, but when
1358	the lock-out case is known to be rare (which in turn is rare :), this is	1388	the lock-out case is known to be rare (which in turn is rare :), this is
1359	workable.	1389	workable.
1360		1390
1361	Usually, however, the lock-out model implemented that way will perform	1391	Usually, however, the lock-out model implemented that way will perform
1362	miserably under the type of load it was designed to handle. In that case,	1392	miserably under the type of load it was designed to handle. In that case,
…		…
1376	{	1406	{
1377	// stop the I/O watcher, we received the event, but	1407	// stop the I/O watcher, we received the event, but
1378	// are not yet ready to handle it.	1408	// are not yet ready to handle it.
1379	ev_io_stop (EV_A_ w);	1409	ev_io_stop (EV_A_ w);
1380		1410
1381	// start the idle watcher to ahndle the actual event.	1411	// start the idle watcher to handle the actual event.
1382	// it will not be executed as long as other watchers	1412	// it will not be executed as long as other watchers
1383	// with the default priority are receiving events.	1413	// with the default priority are receiving events.
1384	ev_idle_start (EV_A_ &idle);	1414	ev_idle_start (EV_A_ &idle);
1385	}	1415	}
1386		1416
…		…
1440		1470
1441	If you cannot use non-blocking mode, then force the use of a	1471	If you cannot use non-blocking mode, then force the use of a
1442	known-to-be-good backend (at the time of this writing, this includes only	1472	known-to-be-good backend (at the time of this writing, this includes only
1443	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file	1473	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1444	descriptors for which non-blocking operation makes no sense (such as	1474	descriptors for which non-blocking operation makes no sense (such as
1445	files) - libev doesn't guarentee any specific behaviour in that case.	1475	files) - libev doesn't guarantee any specific behaviour in that case.
1446		1476
1447	Another thing you have to watch out for is that it is quite easy to	1477	Another thing you have to watch out for is that it is quite easy to
1448	receive "spurious" readiness notifications, that is your callback might	1478	receive "spurious" readiness notifications, that is your callback might
1449	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1479	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1450	because there is no data. Not only are some backends known to create a	1480	because there is no data. Not only are some backends known to create a
…		…
1515		1545
1516	So when you encounter spurious, unexplained daemon exits, make sure you	1546	So when you encounter spurious, unexplained daemon exits, make sure you
1517	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1547	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1518	somewhere, as that would have given you a big clue).	1548	somewhere, as that would have given you a big clue).
1519		1549
		1550	=head3 The special problem of accept()ing when you can't
		1551
		1552	Many implementations of the POSIX C<accept> function (for example,
		1553	found in post-2004 Linux) have the peculiar behaviour of not removing a
		1554	connection from the pending queue in all error cases.
		1555
		1556	For example, larger servers often run out of file descriptors (because
		1557	of resource limits), causing C<accept> to fail with C<ENFILE> but not
		1558	rejecting the connection, leading to libev signalling readiness on
		1559	the next iteration again (the connection still exists after all), and
		1560	typically causing the program to loop at 100% CPU usage.
		1561
		1562	Unfortunately, the set of errors that cause this issue differs between
		1563	operating systems, there is usually little the app can do to remedy the
		1564	situation, and no known thread-safe method of removing the connection to
		1565	cope with overload is known (to me).
		1566
		1567	One of the easiest ways to handle this situation is to just ignore it
		1568	- when the program encounters an overload, it will just loop until the
		1569	situation is over. While this is a form of busy waiting, no OS offers an
		1570	event-based way to handle this situation, so it's the best one can do.
		1571
		1572	A better way to handle the situation is to log any errors other than
		1573	C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such
		1574	messages, and continue as usual, which at least gives the user an idea of
		1575	what could be wrong ("raise the ulimit!"). For extra points one could stop
		1576	the C<ev_io> watcher on the listening fd "for a while", which reduces CPU
		1577	usage.
		1578
		1579	If your program is single-threaded, then you could also keep a dummy file
		1580	descriptor for overload situations (e.g. by opening F</dev/null>), and
		1581	when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>,
		1582	close that fd, and create a new dummy fd. This will gracefully refuse
		1583	clients under typical overload conditions.
		1584
		1585	The last way to handle it is to simply log the error and C<exit>, as
		1586	is often done with C<malloc> failures, but this results in an easy
		1587	opportunity for a DoS attack.
1520		1588
1521	=head3 Watcher-Specific Functions	1589	=head3 Watcher-Specific Functions
1522		1590
1523	=over 4	1591	=over 4
1524		1592
…		…
1671	ev_tstamp timeout = last_activity + 60.;	1739	ev_tstamp timeout = last_activity + 60.;
1672		1740
1673	// if last_activity + 60. is older than now, we did time out	1741	// if last_activity + 60. is older than now, we did time out
1674	if (timeout < now)	1742	if (timeout < now)
1675	{	1743	{
1676	// timeout occured, take action	1744	// timeout occurred, take action
1677	}	1745	}
1678	else	1746	else
1679	{	1747	{
1680	// callback was invoked, but there was some activity, re-arm	1748	// callback was invoked, but there was some activity, re-arm
1681	// the watcher to fire in last_activity + 60, which is	1749	// the watcher to fire in last_activity + 60, which is
…		…
1703	to the current time (meaning we just have some activity :), then call the	1771	to the current time (meaning we just have some activity :), then call the
1704	callback, which will "do the right thing" and start the timer:	1772	callback, which will "do the right thing" and start the timer:
1705		1773
1706	ev_init (timer, callback);	1774	ev_init (timer, callback);
1707	last_activity = ev_now (loop);	1775	last_activity = ev_now (loop);
1708	callback (loop, timer, EV_TIMEOUT);	1776	callback (loop, timer, EV_TIMER);
1709		1777
1710	And when there is some activity, simply store the current time in	1778	And when there is some activity, simply store the current time in
1711	C<last_activity>, no libev calls at all:	1779	C<last_activity>, no libev calls at all:
1712		1780
1713	last_actiivty = ev_now (loop);	1781	last_activity = ev_now (loop);
1714		1782
1715	This technique is slightly more complex, but in most cases where the	1783	This technique is slightly more complex, but in most cases where the
1716	time-out is unlikely to be triggered, much more efficient.	1784	time-out is unlikely to be triggered, much more efficient.
1717		1785
1718	Changing the timeout is trivial as well (if it isn't hard-coded in the	1786	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1837	C<repeat> value), or reset the running timer to the C<repeat> value.	1905	C<repeat> value), or reset the running timer to the C<repeat> value.
1838		1906
1839	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a	1907	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a
1840	usage example.	1908	usage example.
1841		1909
1842	=item ev_timer_remaining (loop, ev_timer *)	1910	=item ev_tstamp ev_timer_remaining (loop, ev_timer *)
1843		1911
1844	Returns the remaining time until a timer fires. If the timer is active,	1912	Returns the remaining time until a timer fires. If the timer is active,
1845	then this time is relative to the current event loop time, otherwise it's	1913	then this time is relative to the current event loop time, otherwise it's
1846	the timeout value currently configured.	1914	the timeout value currently configured.
1847		1915
1848	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns	1916	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns
1849	C<5>. When the timer is started and one second passes, C<ev_timer_remain>	1917	C<5>. When the timer is started and one second passes, C<ev_timer_remaining>
1850	will return C<4>. When the timer expires and is restarted, it will return	1918	will return C<4>. When the timer expires and is restarted, it will return
1851	roughly C<7> (likely slightly less as callback invocation takes some time,	1919	roughly C<7> (likely slightly less as callback invocation takes some time,
1852	too), and so on.	1920	too), and so on.
1853		1921
1854	=item ev_tstamp repeat [read-write]	1922	=item ev_tstamp repeat [read-write]
…		…
2057	Example: Call a callback every hour, or, more precisely, whenever the	2125	Example: Call a callback every hour, or, more precisely, whenever the
2058	system time is divisible by 3600. The callback invocation times have	2126	system time is divisible by 3600. The callback invocation times have
2059	potentially a lot of jitter, but good long-term stability.	2127	potentially a lot of jitter, but good long-term stability.
2060		2128
2061	static void	2129	static void
2062	clock_cb (struct ev_loop loop, ev_io w, int revents)	2130	clock_cb (struct ev_loop loop, ev_periodic w, int revents)
2063	{	2131	{
2064	... its now a full hour (UTC, or TAI or whatever your clock follows)	2132	... its now a full hour (UTC, or TAI or whatever your clock follows)
2065	}	2133	}
2066		2134
2067	ev_periodic hourly_tick;	2135	ev_periodic hourly_tick;
…		…
2114	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should	2182	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should
2115	not be unduly interrupted. If you have a problem with system calls getting	2183	not be unduly interrupted. If you have a problem with system calls getting
2116	interrupted by signals you can block all signals in an C<ev_check> watcher	2184	interrupted by signals you can block all signals in an C<ev_check> watcher
2117	and unblock them in an C<ev_prepare> watcher.	2185	and unblock them in an C<ev_prepare> watcher.
2118		2186
2119	=head3 The special problem of inheritance over execve	2187	=head3 The special problem of inheritance over fork/execve/pthread_create
2120		2188
2121	Both the signal mask (C<sigprocmask>) and the signal disposition	2189	Both the signal mask (C<sigprocmask>) and the signal disposition
2122	(C<sigaction>) are unspecified after starting a signal watcher (and after	2190	(C<sigaction>) are unspecified after starting a signal watcher (and after
2123	stopping it again), that is, libev might or might not block the signal,	2191	stopping it again), that is, libev might or might not block the signal,
2124	and might or might not set or restore the installed signal handler.	2192	and might or might not set or restore the installed signal handler.
…		…
2130		2198
2131	This means that before calling C<exec> (from the child) you should reset	2199	This means that before calling C<exec> (from the child) you should reset
2132	the signal mask to whatever "default" you expect (all clear is a good	2200	the signal mask to whatever "default" you expect (all clear is a good
2133	choice usually).	2201	choice usually).
2134		2202
2135	In current versions of libev, you can ensure that the signal mask is not	2203	The simplest way to ensure that the signal mask is reset in the child is
2136	blocking any signals (except temporarily, so thread users watch out) by	2204	to install a fork handler with C<pthread_atfork> that resets it. That will
2137	specifying the C<EVFLAG_NOSIGNALFD> when creating the event loop. This is	2205	catch fork calls done by libraries (such as the libc) as well.
2138	not guaranteed for future versions, however.	2206
		2207	In current versions of libev, the signal will not be blocked indefinitely
		2208	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces
		2209	the window of opportunity for problems, it will not go away, as libev
		2210	I<has> to modify the signal mask, at least temporarily.
		2211
		2212	So I can't stress this enough: I<If you do not reset your signal mask when
		2213	you expect it to be empty, you have a race condition in your code>. This
		2214	is not a libev-specific thing, this is true for most event libraries.
2139		2215
2140	=head3 Watcher-Specific Functions and Data Members	2216	=head3 Watcher-Specific Functions and Data Members
2141		2217
2142	=over 4	2218	=over 4
2143		2219
…		…
2891	C<ev_default_fork> cheats and calls it in the wrong process, the fork	2967	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2892	handlers will be invoked, too, of course.	2968	handlers will be invoked, too, of course.
2893		2969
2894	=head3 The special problem of life after fork - how is it possible?	2970	=head3 The special problem of life after fork - how is it possible?
2895		2971
2896	Most uses of C<fork()> consist of forking, then some simple calls to ste	2972	Most uses of C<fork()> consist of forking, then some simple calls to set
2897	up/change the process environment, followed by a call to C<exec()>. This	2973	up/change the process environment, followed by a call to C<exec()>. This
2898	sequence should be handled by libev without any problems.	2974	sequence should be handled by libev without any problems.
2899		2975
2900	This changes when the application actually wants to do event handling	2976	This changes when the application actually wants to do event handling
2901	in the child, or both parent in child, in effect "continuing" after the	2977	in the child, or both parent in child, in effect "continuing" after the
…		…
2935	believe me.	3011	believe me.
2936		3012
2937	=back	3013	=back
2938		3014
2939		3015
2940	=head2 C<ev_async> - how to wake up another event loop	3016	=head2 C<ev_async> - how to wake up an event loop
2941		3017
2942	In general, you cannot use an C<ev_loop> from multiple threads or other	3018	In general, you cannot use an C<ev_loop> from multiple threads or other
2943	asynchronous sources such as signal handlers (as opposed to multiple event	3019	asynchronous sources such as signal handlers (as opposed to multiple event
2944	loops - those are of course safe to use in different threads).	3020	loops - those are of course safe to use in different threads).
2945		3021
2946	Sometimes, however, you need to wake up another event loop you do not	3022	Sometimes, however, you need to wake up an event loop you do not control,
2947	control, for example because it belongs to another thread. This is what	3023	for example because it belongs to another thread. This is what C<ev_async>
2948	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3024	watchers do: as long as the C<ev_async> watcher is active, you can signal
2949	can signal it by calling C<ev_async_send>, which is thread- and signal	3025	it by calling C<ev_async_send>, which is thread- and signal safe.
2950	safe.
2951		3026
2952	This functionality is very similar to C<ev_signal> watchers, as signals,	3027	This functionality is very similar to C<ev_signal> watchers, as signals,
2953	too, are asynchronous in nature, and signals, too, will be compressed	3028	too, are asynchronous in nature, and signals, too, will be compressed
2954	(i.e. the number of callback invocations may be less than the number of	3029	(i.e. the number of callback invocations may be less than the number of
2955	C<ev_async_sent> calls).	3030	C<ev_async_sent> calls).
…		…
2960	=head3 Queueing	3035	=head3 Queueing
2961		3036
2962	C<ev_async> does not support queueing of data in any way. The reason	3037	C<ev_async> does not support queueing of data in any way. The reason
2963	is that the author does not know of a simple (or any) algorithm for a	3038	is that the author does not know of a simple (or any) algorithm for a
2964	multiple-writer-single-reader queue that works in all cases and doesn't	3039	multiple-writer-single-reader queue that works in all cases and doesn't
2965	need elaborate support such as pthreads.	3040	need elaborate support such as pthreads or unportable memory access
		3041	semantics.
2966		3042
2967	That means that if you want to queue data, you have to provide your own	3043	That means that if you want to queue data, you have to provide your own
2968	queue. But at least I can tell you how to implement locking around your	3044	queue. But at least I can tell you how to implement locking around your
2969	queue:	3045	queue:
2970		3046
…		…
3109		3185
3110	If C<timeout> is less than 0, then no timeout watcher will be	3186	If C<timeout> is less than 0, then no timeout watcher will be
3111	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	3187	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
3112	repeat = 0) will be started. C<0> is a valid timeout.	3188	repeat = 0) will be started. C<0> is a valid timeout.
3113		3189
3114	The callback has the type C<void (cb)(int revents, void arg)> and gets	3190	The callback has the type C<void (cb)(int revents, void arg)> and is
3115	passed an C<revents> set like normal event callbacks (a combination of	3191	passed an C<revents> set like normal event callbacks (a combination of
3116	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	3192	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg>
3117	value passed to C<ev_once>. Note that it is possible to receive I<both>	3193	value passed to C<ev_once>. Note that it is possible to receive I<both>
3118	a timeout and an io event at the same time - you probably should give io	3194	a timeout and an io event at the same time - you probably should give io
3119	events precedence.	3195	events precedence.
3120		3196
3121	Example: wait up to ten seconds for data to appear on STDIN_FILENO.	3197	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
3122		3198
3123	static void stdin_ready (int revents, void *arg)	3199	static void stdin_ready (int revents, void *arg)
3124	{	3200	{
3125	if (revents & EV_READ)	3201	if (revents & EV_READ)
3126	/* stdin might have data for us, joy! */;	3202	/* stdin might have data for us, joy! */;
3127	else if (revents & EV_TIMEOUT)	3203	else if (revents & EV_TIMER)
3128	/* doh, nothing entered */;	3204	/* doh, nothing entered */;
3129	}	3205	}
3130		3206
3131	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3207	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3132		3208
3133	=item ev_feed_event (struct ev_loop , watcher , int revents)
3134
3135	Feeds the given event set into the event loop, as if the specified event
3136	had happened for the specified watcher (which must be a pointer to an
3137	initialised but not necessarily started event watcher).
3138
3139	=item ev_feed_fd_event (struct ev_loop *, int fd, int revents)	3209	=item ev_feed_fd_event (loop, int fd, int revents)
3140		3210
3141	Feed an event on the given fd, as if a file descriptor backend detected	3211	Feed an event on the given fd, as if a file descriptor backend detected
3142	the given events it.	3212	the given events it.
3143		3213
3144	=item ev_feed_signal_event (struct ev_loop *loop, int signum)	3214	=item ev_feed_signal_event (loop, int signum)
3145		3215
3146	Feed an event as if the given signal occurred (C<loop> must be the default	3216	Feed an event as if the given signal occurred (C<loop> must be the default
3147	loop!).	3217	loop!).
3148		3218
3149	=back	3219	=back
…		…
3229		3299
3230	=over 4	3300	=over 4
3231		3301
3232	=item ev::TYPE::TYPE ()	3302	=item ev::TYPE::TYPE ()
3233		3303
3234	=item ev::TYPE::TYPE (struct ev_loop *)	3304	=item ev::TYPE::TYPE (loop)
3235		3305
3236	=item ev::TYPE::~TYPE	3306	=item ev::TYPE::~TYPE
3237		3307
3238	The constructor (optionally) takes an event loop to associate the watcher	3308	The constructor (optionally) takes an event loop to associate the watcher
3239	with. If it is omitted, it will use C<EV_DEFAULT>.	3309	with. If it is omitted, it will use C<EV_DEFAULT>.
…		…
3272	myclass obj;	3342	myclass obj;
3273	ev::io iow;	3343	ev::io iow;
3274	iow.set <myclass, &myclass::io_cb> (&obj);	3344	iow.set <myclass, &myclass::io_cb> (&obj);
3275		3345
3276	=item w->set (object *)	3346	=item w->set (object *)
3277
3278	This is an B<experimental> feature that might go away in a future version.
3279		3347
3280	This is a variation of a method callback - leaving out the method to call	3348	This is a variation of a method callback - leaving out the method to call
3281	will default the method to C<operator ()>, which makes it possible to use	3349	will default the method to C<operator ()>, which makes it possible to use
3282	functor objects without having to manually specify the C<operator ()> all	3350	functor objects without having to manually specify the C<operator ()> all
3283	the time. Incidentally, you can then also leave out the template argument	3351	the time. Incidentally, you can then also leave out the template argument
…		…
3316	Example: Use a plain function as callback.	3384	Example: Use a plain function as callback.
3317		3385
3318	static void io_cb (ev::io &w, int revents) { }	3386	static void io_cb (ev::io &w, int revents) { }
3319	iow.set <io_cb> ();	3387	iow.set <io_cb> ();
3320		3388
3321	=item w->set (struct ev_loop *)	3389	=item w->set (loop)
3322		3390
3323	Associates a different C<struct ev_loop> with this watcher. You can only	3391	Associates a different C<struct ev_loop> with this watcher. You can only
3324	do this when the watcher is inactive (and not pending either).	3392	do this when the watcher is inactive (and not pending either).
3325		3393
3326	=item w->set ([arguments])	3394	=item w->set ([arguments])
…		…
3425	Erkki Seppala has written Ocaml bindings for libev, to be found at	3493	Erkki Seppala has written Ocaml bindings for libev, to be found at
3426	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	3494	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
3427		3495
3428	=item Lua	3496	=item Lua
3429		3497
3430	Brian Maher has written a partial interface to libev	3498	Brian Maher has written a partial interface to libev for lua (at the
3431	for lua (only C<ev_io> and C<ev_timer>), to be found at	3499	time of this writing, only C<ev_io> and C<ev_timer>), to be found at
3432	L<http://github.com/brimworks/lua-ev>.	3500	L<http://github.com/brimworks/lua-ev>.
3433		3501
3434	=back	3502	=back
3435		3503
3436		3504
…		…
3591	libev.m4	3659	libev.m4
3592		3660
3593	=head2 PREPROCESSOR SYMBOLS/MACROS	3661	=head2 PREPROCESSOR SYMBOLS/MACROS
3594		3662
3595	Libev can be configured via a variety of preprocessor symbols you have to	3663	Libev can be configured via a variety of preprocessor symbols you have to
3596	define before including any of its files. The default in the absence of	3664	define before including (or compiling) any of its files. The default in
3597	autoconf is documented for every option.	3665	the absence of autoconf is documented for every option.
		3666
		3667	Symbols marked with "(h)" do not change the ABI, and can have different
		3668	values when compiling libev vs. including F<ev.h>, so it is permissible
		3669	to redefine them before including F<ev.h> without breaking compatibility
		3670	to a compiled library. All other symbols change the ABI, which means all
		3671	users of libev and the libev code itself must be compiled with compatible
		3672	settings.
3598		3673
3599	=over 4	3674	=over 4
3600		3675
3601	=item EV_STANDALONE	3676	=item EV_STANDALONE (h)
3602		3677
3603	Must always be C<1> if you do not use autoconf configuration, which	3678	Must always be C<1> if you do not use autoconf configuration, which
3604	keeps libev from including F<config.h>, and it also defines dummy	3679	keeps libev from including F<config.h>, and it also defines dummy
3605	implementations for some libevent functions (such as logging, which is not	3680	implementations for some libevent functions (such as logging, which is not
3606	supported). It will also not define any of the structs usually found in	3681	supported). It will also not define any of the structs usually found in
…		…
3756	as well as for signal and thread safety in C<ev_async> watchers.	3831	as well as for signal and thread safety in C<ev_async> watchers.
3757		3832
3758	In the absence of this define, libev will use C<sig_atomic_t volatile>	3833	In the absence of this define, libev will use C<sig_atomic_t volatile>
3759	(from F<signal.h>), which is usually good enough on most platforms.	3834	(from F<signal.h>), which is usually good enough on most platforms.
3760		3835
3761	=item EV_H	3836	=item EV_H (h)
3762		3837
3763	The name of the F<ev.h> header file used to include it. The default if	3838	The name of the F<ev.h> header file used to include it. The default if
3764	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be	3839	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
3765	used to virtually rename the F<ev.h> header file in case of conflicts.	3840	used to virtually rename the F<ev.h> header file in case of conflicts.
3766		3841
3767	=item EV_CONFIG_H	3842	=item EV_CONFIG_H (h)
3768		3843
3769	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	3844	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
3770	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	3845	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
3771	C<EV_H>, above.	3846	C<EV_H>, above.
3772		3847
3773	=item EV_EVENT_H	3848	=item EV_EVENT_H (h)
3774		3849
3775	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	3850	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
3776	of how the F<event.h> header can be found, the default is C<"event.h">.	3851	of how the F<event.h> header can be found, the default is C<"event.h">.
3777		3852
3778	=item EV_PROTOTYPES	3853	=item EV_PROTOTYPES (h)
3779		3854
3780	If defined to be C<0>, then F<ev.h> will not define any function	3855	If defined to be C<0>, then F<ev.h> will not define any function
3781	prototypes, but still define all the structs and other symbols. This is	3856	prototypes, but still define all the structs and other symbols. This is
3782	occasionally useful if you want to provide your own wrapper functions	3857	occasionally useful if you want to provide your own wrapper functions
3783	around libev functions.	3858	around libev functions.
…		…
3805	fine.	3880	fine.
3806		3881
3807	If your embedding application does not need any priorities, defining these	3882	If your embedding application does not need any priorities, defining these
3808	both to C<0> will save some memory and CPU.	3883	both to C<0> will save some memory and CPU.
3809		3884
3810	=item EV_PERIODIC_ENABLE	3885	=item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE,
		3886	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
		3887	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3811		3888
3812	If undefined or defined to be C<1>, then periodic timers are supported. If	3889	If undefined or defined to be C<1> (and the platform supports it), then
3813	defined to be C<0>, then they are not. Disabling them saves a few kB of	3890	the respective watcher type is supported. If defined to be C<0>, then it
3814	code.	3891	is not. Disabling watcher types mainly saves code size.
3815		3892
3816	=item EV_IDLE_ENABLE	3893	=item EV_FEATURES
3817
3818	If undefined or defined to be C<1>, then idle watchers are supported. If
3819	defined to be C<0>, then they are not. Disabling them saves a few kB of
3820	code.
3821
3822	=item EV_EMBED_ENABLE
3823
3824	If undefined or defined to be C<1>, then embed watchers are supported. If
3825	defined to be C<0>, then they are not. Embed watchers rely on most other
3826	watcher types, which therefore must not be disabled.
3827
3828	=item EV_STAT_ENABLE
3829
3830	If undefined or defined to be C<1>, then stat watchers are supported. If
3831	defined to be C<0>, then they are not.
3832
3833	=item EV_FORK_ENABLE
3834
3835	If undefined or defined to be C<1>, then fork watchers are supported. If
3836	defined to be C<0>, then they are not.
3837
3838	=item EV_ASYNC_ENABLE
3839
3840	If undefined or defined to be C<1>, then async watchers are supported. If
3841	defined to be C<0>, then they are not.
3842
3843	=item EV_MINIMAL
3844		3894
3845	If you need to shave off some kilobytes of code at the expense of some	3895	If you need to shave off some kilobytes of code at the expense of some
3846	speed (but with the full API), define this symbol to C<1>. Currently this	3896	speed (but with the full API), you can define this symbol to request
3847	is used to override some inlining decisions, saves roughly 30% code size	3897	certain subsets of functionality. The default is to enable all features
3848	on amd64. It also selects a much smaller 2-heap for timer management over	3898	that can be enabled on the platform.
3849	the default 4-heap.
3850		3899
3851	You can save even more by disabling watcher types you do not need	3900	A typical way to use this symbol is to define it to C<0> (or to a bitset
3852	and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert>	3901	with some broad features you want) and then selectively re-enable
3853	(C<-DNDEBUG>) will usually reduce code size a lot.	3902	additional parts you want, for example if you want everything minimal,
		3903	but multiple event loop support, async and child watchers and the poll
		3904	backend, use this:
3854		3905
3855	Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to	3906	#define EV_FEATURES 0
3856	provide a bare-bones event library. See C<ev.h> for details on what parts	3907	#define EV_MULTIPLICITY 1
3857	of the API are still available, and do not complain if this subset changes	3908	#define EV_USE_POLL 1
3858	over time.	3909	#define EV_CHILD_ENABLE 1
		3910	#define EV_ASYNC_ENABLE 1
		3911
		3912	The actual value is a bitset, it can be a combination of the following
		3913	values:
		3914
		3915	=over 4
		3916
		3917	=item C<1> - faster/larger code
		3918
		3919	Use larger code to speed up some operations.
		3920
		3921	Currently this is used to override some inlining decisions (enlarging the
		3922	code size by roughly 30% on amd64).
		3923
		3924	When optimising for size, use of compiler flags such as C<-Os> with
		3925	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
		3926	assertions.
		3927
		3928	=item C<2> - faster/larger data structures
		3929
		3930	Replaces the small 2-heap for timer management by a faster 4-heap, larger
		3931	hash table sizes and so on. This will usually further increase code size
		3932	and can additionally have an effect on the size of data structures at
		3933	runtime.
		3934
		3935	=item C<4> - full API configuration
		3936
		3937	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
		3938	enables multiplicity (C<EV_MULTIPLICITY>=1).
		3939
		3940	=item C<8> - full API
		3941
		3942	This enables a lot of the "lesser used" API functions. See C<ev.h> for
		3943	details on which parts of the API are still available without this
		3944	feature, and do not complain if this subset changes over time.
		3945
		3946	=item C<16> - enable all optional watcher types
		3947
		3948	Enables all optional watcher types. If you want to selectively enable
		3949	only some watcher types other than I/O and timers (e.g. prepare,
		3950	embed, async, child...) you can enable them manually by defining
		3951	C<EV_watchertype_ENABLE> to C<1> instead.
		3952
		3953	=item C<32> - enable all backends
		3954
		3955	This enables all backends - without this feature, you need to enable at
		3956	least one backend manually (C<EV_USE_SELECT> is a good choice).
		3957
		3958	=item C<64> - enable OS-specific "helper" APIs
		3959
		3960	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
		3961	default.
		3962
		3963	=back
		3964
		3965	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>
		3966	reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb
		3967	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
		3968	watchers, timers and monotonic clock support.
		3969
		3970	With an intelligent-enough linker (gcc+binutils are intelligent enough
		3971	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
		3972	your program might be left out as well - a binary starting a timer and an
		3973	I/O watcher then might come out at only 5Kb.
		3974
		3975	=item EV_AVOID_STDIO
		3976
		3977	If this is set to C<1> at compiletime, then libev will avoid using stdio
		3978	functions (printf, scanf, perror etc.). This will increase the code size
		3979	somewhat, but if your program doesn't otherwise depend on stdio and your
		3980	libc allows it, this avoids linking in the stdio library which is quite
		3981	big.
		3982
		3983	Note that error messages might become less precise when this option is
		3984	enabled.
3859		3985
3860	=item EV_NSIG	3986	=item EV_NSIG
3861		3987
3862	The highest supported signal number, +1 (or, the number of	3988	The highest supported signal number, +1 (or, the number of
3863	signals): Normally, libev tries to deduce the maximum number of signals	3989	signals): Normally, libev tries to deduce the maximum number of signals
3864	automatically, but sometimes this fails, in which case it can be	3990	automatically, but sometimes this fails, in which case it can be
3865	specified. Also, using a lower number than detected (C<32> should be	3991	specified. Also, using a lower number than detected (C<32> should be
3866	good for about any system in existance) can save some memory, as libev	3992	good for about any system in existence) can save some memory, as libev
3867	statically allocates some 12-24 bytes per signal number.	3993	statically allocates some 12-24 bytes per signal number.
3868		3994
3869	=item EV_PID_HASHSIZE	3995	=item EV_PID_HASHSIZE
3870		3996
3871	C<ev_child> watchers use a small hash table to distribute workload by	3997	C<ev_child> watchers use a small hash table to distribute workload by
3872	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	3998	pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled),
3873	than enough. If you need to manage thousands of children you might want to	3999	usually more than enough. If you need to manage thousands of children you
3874	increase this value (I<must> be a power of two).	4000	might want to increase this value (I<must> be a power of two).
3875		4001
3876	=item EV_INOTIFY_HASHSIZE	4002	=item EV_INOTIFY_HASHSIZE
3877		4003
3878	C<ev_stat> watchers use a small hash table to distribute workload by	4004	C<ev_stat> watchers use a small hash table to distribute workload by
3879	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	4005	inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES>
3880	usually more than enough. If you need to manage thousands of C<ev_stat>	4006	disabled), usually more than enough. If you need to manage thousands of
3881	watchers you might want to increase this value (I<must> be a power of	4007	C<ev_stat> watchers you might want to increase this value (I<must> be a
3882	two).	4008	power of two).
3883		4009
3884	=item EV_USE_4HEAP	4010	=item EV_USE_4HEAP
3885		4011
3886	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4012	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3887	timer and periodics heaps, libev uses a 4-heap when this symbol is defined	4013	timer and periodics heaps, libev uses a 4-heap when this symbol is defined
3888	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably	4014	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
3889	faster performance with many (thousands) of watchers.	4015	faster performance with many (thousands) of watchers.
3890		4016
3891	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4017	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3892	(disabled).	4018	will be C<0>.
3893		4019
3894	=item EV_HEAP_CACHE_AT	4020	=item EV_HEAP_CACHE_AT
3895		4021
3896	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4022	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3897	timer and periodics heaps, libev can cache the timestamp (I<at>) within	4023	timer and periodics heaps, libev can cache the timestamp (I<at>) within
3898	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),	4024	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
3899	which uses 8-12 bytes more per watcher and a few hundred bytes more code,	4025	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
3900	but avoids random read accesses on heap changes. This improves performance	4026	but avoids random read accesses on heap changes. This improves performance
3901	noticeably with many (hundreds) of watchers.	4027	noticeably with many (hundreds) of watchers.
3902		4028
3903	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4029	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3904	(disabled).	4030	will be C<0>.
3905		4031
3906	=item EV_VERIFY	4032	=item EV_VERIFY
3907		4033
3908	Controls how much internal verification (see C<ev_loop_verify ()>) will	4034	Controls how much internal verification (see C<ev_loop_verify ()>) will
3909	be done: If set to C<0>, no internal verification code will be compiled	4035	be done: If set to C<0>, no internal verification code will be compiled
…		…
3911	called. If set to C<2>, then the internal verification code will be	4037	called. If set to C<2>, then the internal verification code will be
3912	called once per loop, which can slow down libev. If set to C<3>, then the	4038	called once per loop, which can slow down libev. If set to C<3>, then the
3913	verification code will be called very frequently, which will slow down	4039	verification code will be called very frequently, which will slow down
3914	libev considerably.	4040	libev considerably.
3915		4041
3916	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be	4042	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3917	C<0>.	4043	will be C<0>.
3918		4044
3919	=item EV_COMMON	4045	=item EV_COMMON
3920		4046
3921	By default, all watchers have a C<void *data> member. By redefining	4047	By default, all watchers have a C<void *data> member. By redefining
3922	this macro to a something else you can include more and other types of	4048	this macro to something else you can include more and other types of
3923	members. You have to define it each time you include one of the files,	4049	members. You have to define it each time you include one of the files,
3924	though, and it must be identical each time.	4050	though, and it must be identical each time.
3925		4051
3926	For example, the perl EV module uses something like this:	4052	For example, the perl EV module uses something like this:
3927		4053
…		…
3980	file.	4106	file.
3981		4107
3982	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	4108	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3983	that everybody includes and which overrides some configure choices:	4109	that everybody includes and which overrides some configure choices:
3984		4110
3985	#define EV_MINIMAL 1	4111	#define EV_FEATURES 8
3986	#define EV_USE_POLL 0	4112	#define EV_USE_SELECT 1
3987	#define EV_MULTIPLICITY 0
3988	#define EV_PERIODIC_ENABLE 0	4113	#define EV_PREPARE_ENABLE 1
		4114	#define EV_IDLE_ENABLE 1
3989	#define EV_STAT_ENABLE 0	4115	#define EV_SIGNAL_ENABLE 1
3990	#define EV_FORK_ENABLE 0	4116	#define EV_CHILD_ENABLE 1
		4117	#define EV_USE_STDEXCEPT 0
3991	#define EV_CONFIG_H <config.h>	4118	#define EV_CONFIG_H <config.h>
3992	#define EV_MINPRI 0
3993	#define EV_MAXPRI 0
3994		4119
3995	#include "ev++.h"	4120	#include "ev++.h"
3996		4121
3997	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4122	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3998		4123
…		…
4227	maintainable.	4352	maintainable.
4228		4353
4229	And of course, some compiler warnings are just plain stupid, or simply	4354	And of course, some compiler warnings are just plain stupid, or simply
4230	wrong (because they don't actually warn about the condition their message	4355	wrong (because they don't actually warn about the condition their message
4231	seems to warn about). For example, certain older gcc versions had some	4356	seems to warn about). For example, certain older gcc versions had some
4232	warnings that resulted an extreme number of false positives. These have	4357	warnings that resulted in an extreme number of false positives. These have
4233	been fixed, but some people still insist on making code warn-free with	4358	been fixed, but some people still insist on making code warn-free with
4234	such buggy versions.	4359	such buggy versions.
4235		4360
4236	While libev is written to generate as few warnings as possible,	4361	While libev is written to generate as few warnings as possible,
4237	"warn-free" code is not a goal, and it is recommended not to build libev	4362	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4273	I suggest using suppression lists.	4398	I suggest using suppression lists.
4274		4399
4275		4400
4276	=head1 PORTABILITY NOTES	4401	=head1 PORTABILITY NOTES
4277		4402
		4403	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4404
		4405	GNU/Linux is the only common platform that supports 64 bit file/large file
		4406	interfaces but I<disables> them by default.
		4407
		4408	That means that libev compiled in the default environment doesn't support
		4409	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4410
		4411	Unfortunately, many programs try to work around this GNU/Linux issue
		4412	by enabling the large file API, which makes them incompatible with the
		4413	standard libev compiled for their system.
		4414
		4415	Likewise, libev cannot enable the large file API itself as this would
		4416	suddenly make it incompatible to the default compile time environment,
		4417	i.e. all programs not using special compile switches.
		4418
		4419	=head2 OS/X AND DARWIN BUGS
		4420
		4421	The whole thing is a bug if you ask me - basically any system interface
		4422	you touch is broken, whether it is locales, poll, kqueue or even the
		4423	OpenGL drivers.
		4424
		4425	=head3 C<kqueue> is buggy
		4426
		4427	The kqueue syscall is broken in all known versions - most versions support
		4428	only sockets, many support pipes.
		4429
		4430	Libev tries to work around this by not using C<kqueue> by default on
		4431	this rotten platform, but of course you can still ask for it when creating
		4432	a loop.
		4433
		4434	=head3 C<poll> is buggy
		4435
		4436	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4437	implementation by something calling C<kqueue> internally around the 10.5.6
		4438	release, so now C<kqueue> I<and> C<poll> are broken.
		4439
		4440	Libev tries to work around this by not using C<poll> by default on
		4441	this rotten platform, but of course you can still ask for it when creating
		4442	a loop.
		4443
		4444	=head3 C<select> is buggy
		4445
		4446	All that's left is C<select>, and of course Apple found a way to fuck this
		4447	one up as well: On OS/X, C<select> actively limits the number of file
		4448	descriptors you can pass in to 1024 - your program suddenly crashes when
		4449	you use more.
		4450
		4451	There is an undocumented "workaround" for this - defining
		4452	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4453	work on OS/X.
		4454
		4455	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4456
		4457	=head3 C<errno> reentrancy
		4458
		4459	The default compile environment on Solaris is unfortunately so
		4460	thread-unsafe that you can't even use components/libraries compiled
		4461	without C<-D_REENTRANT> (as long as they use C<errno>), which, of course,
		4462	isn't defined by default.
		4463
		4464	If you want to use libev in threaded environments you have to make sure
		4465	it's compiled with C<_REENTRANT> defined.
		4466
		4467	=head3 Event port backend
		4468
		4469	The scalable event interface for Solaris is called "event ports". Unfortunately,
		4470	this mechanism is very buggy. If you run into high CPU usage, your program
		4471	freezes or you get a large number of spurious wakeups, make sure you have
		4472	all the relevant and latest kernel patches applied. No, I don't know which
		4473	ones, but there are multiple ones.
		4474
		4475	If you can't get it to work, you can try running the program by setting
		4476	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4477	C<select> backends.
		4478
		4479	=head2 AIX POLL BUG
		4480
		4481	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4482	this by trying to avoid the poll backend altogether (i.e. it's not even
		4483	compiled in), which normally isn't a big problem as C<select> works fine
		4484	with large bitsets, and AIX is dead anyway.
		4485
4278	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4486	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4487
		4488	=head3 General issues
4279		4489
4280	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4490	Win32 doesn't support any of the standards (e.g. POSIX) that libev
4281	requires, and its I/O model is fundamentally incompatible with the POSIX	4491	requires, and its I/O model is fundamentally incompatible with the POSIX
4282	model. Libev still offers limited functionality on this platform in	4492	model. Libev still offers limited functionality on this platform in
4283	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4493	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4284	descriptors. This only applies when using Win32 natively, not when using	4494	descriptors. This only applies when using Win32 natively, not when using
4285	e.g. cygwin.	4495	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4496	as every compielr comes with a slightly differently broken/incompatible
		4497	environment.
4286		4498
4287	Lifting these limitations would basically require the full	4499	Lifting these limitations would basically require the full
4288	re-implementation of the I/O system. If you are into these kinds of	4500	re-implementation of the I/O system. If you are into this kind of thing,
4289	things, then note that glib does exactly that for you in a very portable	4501	then note that glib does exactly that for you in a very portable way (note
4290	way (note also that glib is the slowest event library known to man).	4502	also that glib is the slowest event library known to man).
4291		4503
4292	There is no supported compilation method available on windows except	4504	There is no supported compilation method available on windows except
4293	embedding it into other applications.	4505	embedding it into other applications.
4294		4506
4295	Sensible signal handling is officially unsupported by Microsoft - libev	4507	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4323	you do I<not> compile the F<ev.c> or any other embedded source files!):	4535	you do I<not> compile the F<ev.c> or any other embedded source files!):
4324		4536
4325	#include "evwrap.h"	4537	#include "evwrap.h"
4326	#include "ev.c"	4538	#include "ev.c"
4327		4539
4328	=over 4
4329
4330	=item The winsocket select function	4540	=head3 The winsocket C<select> function
4331		4541
4332	The winsocket C<select> function doesn't follow POSIX in that it	4542	The winsocket C<select> function doesn't follow POSIX in that it
4333	requires socket I<handles> and not socket I<file descriptors> (it is	4543	requires socket I<handles> and not socket I<file descriptors> (it is
4334	also extremely buggy). This makes select very inefficient, and also	4544	also extremely buggy). This makes select very inefficient, and also
4335	requires a mapping from file descriptors to socket handles (the Microsoft	4545	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4344	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	4554	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4345		4555
4346	Note that winsockets handling of fd sets is O(n), so you can easily get a	4556	Note that winsockets handling of fd sets is O(n), so you can easily get a
4347	complexity in the O(n²) range when using win32.	4557	complexity in the O(n²) range when using win32.
4348		4558
4349	=item Limited number of file descriptors	4559	=head3 Limited number of file descriptors
4350		4560
4351	Windows has numerous arbitrary (and low) limits on things.	4561	Windows has numerous arbitrary (and low) limits on things.
4352		4562
4353	Early versions of winsocket's select only supported waiting for a maximum	4563	Early versions of winsocket's select only supported waiting for a maximum
4354	of C<64> handles (probably owning to the fact that all windows kernels	4564	of C<64> handles (probably owning to the fact that all windows kernels
…		…
4369	runtime libraries. This might get you to about C<512> or C<2048> sockets	4579	runtime libraries. This might get you to about C<512> or C<2048> sockets
4370	(depending on windows version and/or the phase of the moon). To get more,	4580	(depending on windows version and/or the phase of the moon). To get more,
4371	you need to wrap all I/O functions and provide your own fd management, but	4581	you need to wrap all I/O functions and provide your own fd management, but
4372	the cost of calling select (O(n²)) will likely make this unworkable.	4582	the cost of calling select (O(n²)) will likely make this unworkable.
4373		4583
4374	=back
4375
4376	=head2 PORTABILITY REQUIREMENTS	4584	=head2 PORTABILITY REQUIREMENTS
4377		4585
4378	In addition to a working ISO-C implementation and of course the	4586	In addition to a working ISO-C implementation and of course the
4379	backend-specific APIs, libev relies on a few additional extensions:	4587	backend-specific APIs, libev relies on a few additional extensions:
4380		4588
…		…
4500	involves iterating over all running async watchers or all signal numbers.	4708	involves iterating over all running async watchers or all signal numbers.
4501		4709
4502	=back	4710	=back
4503		4711
4504		4712
		4713	=head1 PORTING FROM LIBEV 3.X TO 4.X
		4714
		4715	The major version 4 introduced some minor incompatible changes to the API.
		4716
		4717	At the moment, the C<ev.h> header file tries to implement superficial
		4718	compatibility, so most programs should still compile. Those might be
		4719	removed in later versions of libev, so better update early than late.
		4720
		4721	=over 4
		4722
		4723	=item C<ev_loop_count> renamed to C<ev_iteration>
		4724
		4725	=item C<ev_loop_depth> renamed to C<ev_depth>
		4726
		4727	=item C<ev_loop_verify> renamed to C<ev_verify>
		4728
		4729	Most functions working on C<struct ev_loop> objects don't have an
		4730	C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is
		4731	still called C<ev_loop_fork> because it would otherwise clash with the
		4732	C<ev_fork> typedef.
		4733
		4734	=item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents>
		4735
		4736	This is a simple rename - all other watcher types use their name
		4737	as revents flag, and now C<ev_timer> does, too.
		4738
		4739	Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions
		4740	and continue to be present for the foreseeable future, so this is mostly a
		4741	documentation change.
		4742
		4743	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
		4744
		4745	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
		4746	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
		4747	and work, but the library code will of course be larger.
		4748
		4749	=back
		4750
		4751
4505	=head1 GLOSSARY	4752	=head1 GLOSSARY
4506		4753
4507	=over 4	4754	=over 4
4508		4755
4509	=item active	4756	=item active
…		…
4530	A change of state of some external event, such as data now being available	4777	A change of state of some external event, such as data now being available
4531	for reading on a file descriptor, time having passed or simply not having	4778	for reading on a file descriptor, time having passed or simply not having
4532	any other events happening anymore.	4779	any other events happening anymore.
4533		4780
4534	In libev, events are represented as single bits (such as C<EV_READ> or	4781	In libev, events are represented as single bits (such as C<EV_READ> or
4535	C<EV_TIMEOUT>).	4782	C<EV_TIMER>).
4536		4783
4537	=item event library	4784	=item event library
4538		4785
4539	A software package implementing an event model and loop.	4786	A software package implementing an event model and loop.
4540		4787

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Comparing libev/ev.pod (file contents): Revision 1.266 by root, Wed Aug 26 17:15:05 2009 UTC vs. Revision 1.306 by root, Mon Oct 18 07:36:05 2010 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.266 by root, Wed Aug 26 17:15:05 2009 UTC vs.
Revision 1.306 by root, Mon Oct 18 07:36:05 2010 UTC