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Revision 1.62 by root, Sun Jun 6 10:13:57 2010 UTC vs.
Revision 1.79 by root, Tue Feb 26 02:08:34 2019 UTC

…		…
1	NAME	1	NAME
2	AnyEvent - the DBI of event loop programming	2	AnyEvent - the DBI of event loop programming
3		3
4	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async,	4	EV, Event, Glib, Tk, UV, Perl, Event::Lib, Irssi, rxvt-unicode,
5	Qt and POE are various supported event loops/environments.	5	IO::Async, Qt, FLTK and POE are various supported event
		6	loops/environments.
6		7
7	SYNOPSIS	8	SYNOPSIS
8	use AnyEvent;	9	use AnyEvent;
9		10
10	# if you prefer function calls, look at the AE manpage for	11	# if you prefer function calls, look at the AE manpage for
13	# file handle or descriptor readable	14	# file handle or descriptor readable
14	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });	15	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
15		16
16	# one-shot or repeating timers	17	# one-shot or repeating timers
17	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });	18	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
18	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...	19	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...);
19		20
20	print AnyEvent->now; # prints current event loop time	21	print AnyEvent->now; # prints current event loop time
21	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.	22	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
22		23
23	# POSIX signal	24	# POSIX signal
…		…
42	This manpage is mainly a reference manual. If you are interested in a	43	This manpage is mainly a reference manual. If you are interested in a
43	tutorial or some gentle introduction, have a look at the AnyEvent::Intro	44	tutorial or some gentle introduction, have a look at the AnyEvent::Intro
44	manpage.	45	manpage.
45		46
46	SUPPORT	47	SUPPORT
		48	An FAQ document is available as AnyEvent::FAQ.
		49
47	There is a mailinglist for discussing all things AnyEvent, and an IRC	50	There also is a mailinglist for discussing all things AnyEvent, and an
48	channel, too.	51	IRC channel, too.
49		52
50	See the AnyEvent project page at the Schmorpforge Ta-Sa Software	53	See the AnyEvent project page at the Schmorpforge Ta-Sa Software
51	Repository, at <http://anyevent.schmorp.de>, for more info.	54	Repository, at <http://anyevent.schmorp.de>, for more info.
52		55
53	WHY YOU SHOULD USE THIS MODULE (OR NOT)	56	WHY YOU SHOULD USE THIS MODULE (OR NOT)
…		…
71	module users into the same thing by forcing them to use the same event	74	module users into the same thing by forcing them to use the same event
72	model you use.	75	model you use.
73		76
74	For modules like POE or IO::Async (which is a total misnomer as it is	77	For modules like POE or IO::Async (which is a total misnomer as it is
75	actually doing all I/O synchronously...), using them in your module is	78	actually doing all I/O synchronously...), using them in your module is
76	like joining a cult: After you joined, you are dependent on them and you	79	like joining a cult: After you join, you are dependent on them and you
77	cannot use anything else, as they are simply incompatible to everything	80	cannot use anything else, as they are simply incompatible to everything
78	that isn't them. What's worse, all the potential users of your module	81	that isn't them. What's worse, all the potential users of your module
79	are also forced to use the same event loop you use.	82	are also forced to use the same event loop you use.
80		83
81	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	84	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
82	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	85	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
83	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if your	86	with the rest: POE + EV? No go. Tk + Event? No go. Again: if your module
84	module uses one of those, every user of your module has to use it, too.	87	uses one of those, every user of your module has to use it, too. But if
85	But if your module uses AnyEvent, it works transparently with all event	88	your module uses AnyEvent, it works transparently with all event models
86	models it supports (including stuff like IO::Async, as long as those use	89	it supports (including stuff like IO::Async, as long as those use one of
87	one of the supported event loops. It is trivial to add new event loops	90	the supported event loops. It is easy to add new event loops to
88	to AnyEvent, too, so it is future-proof).	91	AnyEvent, too, so it is future-proof).
89		92
90	In addition to being free of having to use *the one and only true event	93	In addition to being free of having to use *the one and only true event
91	model*, AnyEvent also is free of bloat and policy: with POE or similar	94	model*, AnyEvent also is free of bloat and policy: with POE or similar
92	modules, you get an enormous amount of code and strict rules you have to	95	modules, you get an enormous amount of code and strict rules you have to
93	follow. AnyEvent, on the other hand, is lean and up to the point, by	96	follow. AnyEvent, on the other hand, is lean and to the point, by only
94	only offering the functionality that is necessary, in as thin as a	97	offering the functionality that is necessary, in as thin as a wrapper as
95	wrapper as technically possible.	98	technically possible.
96		99
97	Of course, AnyEvent comes with a big (and fully optional!) toolbox of	100	Of course, AnyEvent comes with a big (and fully optional!) toolbox of
98	useful functionality, such as an asynchronous DNS resolver, 100%	101	useful functionality, such as an asynchronous DNS resolver, 100%
99	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms	102	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
100	such as Windows) and lots of real-world knowledge and workarounds for	103	such as Windows) and lots of real-world knowledge and workarounds for
…		…
103	Now, if you do want lots of policy (this can arguably be somewhat	106	Now, if you do want lots of policy (this can arguably be somewhat
104	useful) and you want to force your users to use the one and only event	107	useful) and you want to force your users to use the one and only event
105	model, you should not use this module.	108	model, you should not use this module.
106		109
107	DESCRIPTION	110	DESCRIPTION
108	AnyEvent provides an identical interface to multiple event loops. This	111	AnyEvent provides a uniform interface to various event loops. This
109	allows module authors to utilise an event loop without forcing module	112	allows module authors to use event loop functionality without forcing
110	users to use the same event loop (as only a single event loop can	113	module users to use a specific event loop implementation (since more
111	coexist peacefully at any one time).	114	than one event loop cannot coexist peacefully).
112		115
113	The interface itself is vaguely similar, but not identical to the Event	116	The interface itself is vaguely similar, but not identical to the Event
114	module.	117	module.
115		118
116	During the first call of any watcher-creation method, the module tries	119	During the first call of any watcher-creation method, the module tries
117	to detect the currently loaded event loop by probing whether one of the	120	to detect the currently loaded event loop by probing whether one of the
118	following modules is already loaded: EV, Event, Glib,	121	following modules is already loaded: EV, AnyEvent::Loop, Event, Glib,
119	AnyEvent::Impl::Perl, Tk, Event::Lib, Qt, POE. The first one found is	122	Tk, Event::Lib, Qt, POE. The first one found is used. If none are
120	used. If none are found, the module tries to load these modules	123	detected, the module tries to load the first four modules in the order
121	(excluding Tk, Event::Lib, Qt and POE as the pure perl adaptor should	124	given; but note that if EV is not available, the pure-perl
122	always succeed) in the order given. The first one that can be	125	AnyEvent::Loop should always work, so the other two are not normally
123	successfully loaded will be used. If, after this, still none could be	126	tried.
124	found, AnyEvent will fall back to a pure-perl event loop, which is not
125	very efficient, but should work everywhere.
126		127
127	Because AnyEvent first checks for modules that are already loaded,	128	Because AnyEvent first checks for modules that are already loaded,
128	loading an event model explicitly before first using AnyEvent will	129	loading an event model explicitly before first using AnyEvent will
129	likely make that model the default. For example:	130	likely make that model the default. For example:
130		131
…		…
132	use AnyEvent;	133	use AnyEvent;
133		134
134	# .. AnyEvent will likely default to Tk	135	# .. AnyEvent will likely default to Tk
135		136
136	The likely means that, if any module loads another event model and	137	The likely means that, if any module loads another event model and
137	starts using it, all bets are off. Maybe you should tell their authors	138	starts using it, all bets are off - this case should be very rare
138	to use AnyEvent so their modules work together with others seamlessly...	139	though, as very few modules hardcode event loops without announcing this
		140	very loudly.
139		141
140	The pure-perl implementation of AnyEvent is called	142	The pure-perl implementation of AnyEvent is called "AnyEvent::Loop".
141	"AnyEvent::Impl::Perl". Like other event modules you can load it	143	Like other event modules you can load it explicitly and enjoy the high
142	explicitly and enjoy the high availability of that event loop :)	144	availability of that event loop :)
143		145
144	WATCHERS	146	WATCHERS
145	AnyEvent has the central concept of a watcher, which is an object that	147	AnyEvent has the central concept of a watcher, which is an object that
146	stores relevant data for each kind of event you are waiting for, such as	148	stores relevant data for each kind of event you are waiting for, such as
147	the callback to call, the file handle to watch, etc.	149	the callback to call, the file handle to watch, etc.
…		…
151	callback when the event occurs (of course, only when the event model is	153	callback when the event occurs (of course, only when the event model is
152	in control).	154	in control).
153		155
154	Note that callbacks must not permanently change global variables	156	Note that callbacks must not permanently change global variables
155	potentially in use by the event loop (such as $_ or $[) and that	157	potentially in use by the event loop (such as $_ or $[) and that
156	callbacks must not "die". The former is good programming practise in	158	callbacks must not "die". The former is good programming practice in
157	Perl and the latter stems from the fact that exception handling differs	159	Perl and the latter stems from the fact that exception handling differs
158	widely between event loops.	160	widely between event loops.
159		161
160	To disable the watcher you have to destroy it (e.g. by setting the	162	To disable a watcher you have to destroy it (e.g. by setting the
161	variable you store it in to "undef" or otherwise deleting all references	163	variable you store it in to "undef" or otherwise deleting all references
162	to it).	164	to it).
163		165
164	All watchers are created by calling a method on the "AnyEvent" class.	166	All watchers are created by calling a method on the "AnyEvent" class.
165		167
166	Many watchers either are used with "recursion" (repeating timers for	168	Many watchers either are used with "recursion" (repeating timers for
167	example), or need to refer to their watcher object in other ways.	169	example), or need to refer to their watcher object in other ways.
168		170
169	An any way to achieve that is this pattern:	171	One way to achieve that is this pattern:
170		172
171	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	173	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
172	# you can use $w here, for example to undef it	174	# you can use $w here, for example to undef it
173	undef $w;	175	undef $w;
174	});	176	});
…		…
205		207
206	The I/O watcher might use the underlying file descriptor or a copy of	208	The I/O watcher might use the underlying file descriptor or a copy of
207	it. You must not close a file handle as long as any watcher is active on	209	it. You must not close a file handle as long as any watcher is active on
208	the underlying file descriptor.	210	the underlying file descriptor.
209		211
210	Some event loops issue spurious readyness notifications, so you should	212	Some event loops issue spurious readiness notifications, so you should
211	always use non-blocking calls when reading/writing from/to your file	213	always use non-blocking calls when reading/writing from/to your file
212	handles.	214	handles.
213		215
214	Example: wait for readability of STDIN, then read a line and disable the	216	Example: wait for readability of STDIN, then read a line and disable the
215	watcher.	217	watcher.
…		…
238		240
239	Although the callback might get passed parameters, their value and	241	Although the callback might get passed parameters, their value and
240	presence is undefined and you cannot rely on them. Portable AnyEvent	242	presence is undefined and you cannot rely on them. Portable AnyEvent
241	callbacks cannot use arguments passed to time watcher callbacks.	243	callbacks cannot use arguments passed to time watcher callbacks.
242		244
243	The callback will normally be invoked once only. If you specify another	245	The callback will normally be invoked only once. If you specify another
244	parameter, "interval", as a strictly positive number (> 0), then the	246	parameter, "interval", as a strictly positive number (> 0), then the
245	callback will be invoked regularly at that interval (in fractional	247	callback will be invoked regularly at that interval (in fractional
246	seconds) after the first invocation. If "interval" is specified with a	248	seconds) after the first invocation. If "interval" is specified with a
247	false value, then it is treated as if it were missing.	249	false value, then it is treated as if it were not specified at all.
248		250
249	The callback will be rescheduled before invoking the callback, but no	251	The callback will be rescheduled before invoking the callback, but no
250	attempt is done to avoid timer drift in most backends, so the interval	252	attempt is made to avoid timer drift in most backends, so the interval
251	is only approximate.	253	is only approximate.
252		254
253	Example: fire an event after 7.7 seconds.	255	Example: fire an event after 7.7 seconds.
254		256
255	my $w = AnyEvent->timer (after => 7.7, cb => sub {	257	my $w = AnyEvent->timer (after => 7.7, cb => sub {
…		…
261		263
262	Example 2: fire an event after 0.5 seconds, then roughly every second.	264	Example 2: fire an event after 0.5 seconds, then roughly every second.
263		265
264	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {	266	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
265	warn "timeout\n";	267	warn "timeout\n";
266	};	268	});
267		269
268	TIMING ISSUES	270	TIMING ISSUES
269	There are two ways to handle timers: based on real time (relative, "fire	271	There are two ways to handle timers: based on real time (relative, "fire
270	in 10 seconds") and based on wallclock time (absolute, "fire at 12	272	in 10 seconds") and based on wallclock time (absolute, "fire at 12
271	o'clock").	273	o'clock").
272		274
273	While most event loops expect timers to specified in a relative way,	275	While most event loops expect timers to specified in a relative way,
274	they use absolute time internally. This makes a difference when your	276	they use absolute time internally. This makes a difference when your
275	clock "jumps", for example, when ntp decides to set your clock backwards	277	clock "jumps", for example, when ntp decides to set your clock backwards
276	from the wrong date of 2014-01-01 to 2008-01-01, a watcher that is	278	from the wrong date of 2014-01-01 to 2008-01-01, a watcher that is
277	supposed to fire "after" a second might actually take six years to	279	supposed to fire "after a second" might actually take six years to
278	finally fire.	280	finally fire.
279		281
280	AnyEvent cannot compensate for this. The only event loop that is	282	AnyEvent cannot compensate for this. The only event loop that is
281	conscious about these issues is EV, which offers both relative	283	conscious of these issues is EV, which offers both relative (ev_timer,
282	(ev_timer, based on true relative time) and absolute (ev_periodic, based	284	based on true relative time) and absolute (ev_periodic, based on
283	on wallclock time) timers.	285	wallclock time) timers.
284		286
285	AnyEvent always prefers relative timers, if available, matching the	287	AnyEvent always prefers relative timers, if available, matching the
286	AnyEvent API.	288	AnyEvent API.
287		289
288	AnyEvent has two additional methods that return the "current time":	290	AnyEvent has two additional methods that return the "current time":
…		…
307	*In almost all cases (in all cases if you don't care), this is the	309	*In almost all cases (in all cases if you don't care), this is the
308	function to call when you want to know the current time.*	310	function to call when you want to know the current time.*
309		311
310	This function is also often faster then "AnyEvent->time", and thus	312	This function is also often faster then "AnyEvent->time", and thus
311	the preferred method if you want some timestamp (for example,	313	the preferred method if you want some timestamp (for example,
312	AnyEvent::Handle uses this to update it's activity timeouts).	314	AnyEvent::Handle uses this to update its activity timeouts).
313		315
314	The rest of this section is only of relevance if you try to be very	316	The rest of this section is only of relevance if you try to be very
315	exact with your timing, you can skip it without bad conscience.	317	exact with your timing; you can skip it without a bad conscience.
316		318
317	For a practical example of when these times differ, consider	319	For a practical example of when these times differ, consider
318	Event::Lib and EV and the following set-up:	320	Event::Lib and EV and the following set-up:
319		321
320	The event loop is running and has just invoked one of your callback	322	The event loop is running and has just invoked one of your callbacks
321	at time=500 (assume no other callbacks delay processing). In your	323	at time=500 (assume no other callbacks delay processing). In your
322	callback, you wait a second by executing "sleep 1" (blocking the	324	callback, you wait a second by executing "sleep 1" (blocking the
323	process for a second) and then (at time=501) you create a relative	325	process for a second) and then (at time=501) you create a relative
324	timer that fires after three seconds.	326	timer that fires after three seconds.
325		327
…		…
346	can get whatever behaviour you want with any event loop, by taking	348	can get whatever behaviour you want with any event loop, by taking
347	the difference between "AnyEvent->time" and "AnyEvent->now" into	349	the difference between "AnyEvent->time" and "AnyEvent->now" into
348	account.	350	account.
349		351
350	AnyEvent->now_update	352	AnyEvent->now_update
351	Some event loops (such as EV or AnyEvent::Impl::Perl) cache the	353	Some event loops (such as EV or AnyEvent::Loop) cache the current
352	current time for each loop iteration (see the discussion of	354	time for each loop iteration (see the discussion of AnyEvent->now,
353	AnyEvent->now, above).	355	above).
354		356
355	When a callback runs for a long time (or when the process sleeps),	357	When a callback runs for a long time (or when the process sleeps),
356	then this "current" time will differ substantially from the real	358	then this "current" time will differ substantially from the real
357	time, which might affect timers and time-outs.	359	time, which might affect timers and time-outs.
358		360
…		…
402	will not restart syscalls (that includes Async::Interrupt and AnyEvent's	404	will not restart syscalls (that includes Async::Interrupt and AnyEvent's
403	pure perl implementation).	405	pure perl implementation).
404		406
405	Safe/Unsafe Signals	407	Safe/Unsafe Signals
406	Perl signals can be either "safe" (synchronous to opcode handling) or	408	Perl signals can be either "safe" (synchronous to opcode handling) or
407	"unsafe" (asynchronous) - the former might get delayed indefinitely, the	409	"unsafe" (asynchronous) - the former might delay signal delivery
408	latter might corrupt your memory.	410	indefinitely, the latter might corrupt your memory.
409		411
410	AnyEvent signal handlers are, in addition, synchronous to the event	412	AnyEvent signal handlers are, in addition, synchronous to the event
411	loop, i.e. they will not interrupt your running perl program but will	413	loop, i.e. they will not interrupt your running perl program but will
412	only be called as part of the normal event handling (just like timer,	414	only be called as part of the normal event handling (just like timer,
413	I/O etc. callbacks, too).	415	I/O etc. callbacks, too).
414		416
415	Signal Races, Delays and Workarounds	417	Signal Races, Delays and Workarounds
416	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching	418	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
417	callbacks to signals in a generic way, which is a pity, as you cannot do	419	callbacks to signals in a generic way, which is a pity, as you cannot do
418	race-free signal handling in perl, requiring C libraries for this.	420	race-free signal handling in perl, requiring C libraries for this.
419	AnyEvent will try to do it's best, which means in some cases, signals	421	AnyEvent will try to do its best, which means in some cases, signals
420	will be delayed. The maximum time a signal might be delayed is specified	422	will be delayed. The maximum time a signal might be delayed is 10
421	in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable	423	seconds by default, but can be overriden via
422	can be changed only before the first signal watcher is created, and	424	$ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY} or $AnyEvent::MAX_SIGNAL_LATENCY
423	should be left alone otherwise. This variable determines how often	425	- see the "ENVIRONMENT VARIABLES" section for details.
424	AnyEvent polls for signals (in case a wake-up was missed). Higher values
425	will cause fewer spurious wake-ups, which is better for power and CPU
426	saving.
427		426
428	All these problems can be avoided by installing the optional	427	All these problems can be avoided by installing the optional
429	Async::Interrupt module, which works with most event loops. It will not	428	Async::Interrupt module, which works with most event loops. It will not
430	work with inherently broken event loops such as Event or Event::Lib (and	429	work with inherently broken event loops such as Event or Event::Lib (and
431	not with POE currently, as POE does it's own workaround with one-second
432	latency). For those, you just have to suffer the delays.	430	not with POE currently). For those, you just have to suffer the delays.
433		431
434	CHILD PROCESS WATCHERS	432	CHILD PROCESS WATCHERS
435	$w = AnyEvent->child (pid => <process id>, cb => <callback>);	433	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
436		434
437	You can also watch on a child process exit and catch its exit status.	435	You can also watch for a child process exit and catch its exit status.
438		436
439	The child process is specified by the "pid" argument (one some backends,	437	The child process is specified by the "pid" argument (on some backends,
440	using 0 watches for any child process exit, on others this will croak).	438	using 0 watches for any child process exit, on others this will croak).
441	The watcher will be triggered only when the child process has finished	439	The watcher will be triggered only when the child process has finished
442	and an exit status is available, not on any trace events	440	and an exit status is available, not on any trace events
443	(stopped/continued).	441	(stopped/continued).
444		442
…		…
465	This means you cannot create a child watcher as the very first thing in	463	This means you cannot create a child watcher as the very first thing in
466	an AnyEvent program, you have to create at least one watcher before	464	an AnyEvent program, you have to create at least one watcher before
467	you "fork" the child (alternatively, you can call "AnyEvent::detect").	465	you "fork" the child (alternatively, you can call "AnyEvent::detect").
468		466
469	As most event loops do not support waiting for child events, they will	467	As most event loops do not support waiting for child events, they will
470	be emulated by AnyEvent in most cases, in which the latency and race	468	be emulated by AnyEvent in most cases, in which case the latency and
471	problems mentioned in the description of signal watchers apply.	469	race problems mentioned in the description of signal watchers apply.
472		470
473	Example: fork a process and wait for it	471	Example: fork a process and wait for it
474		472
475	my $done = AnyEvent->condvar;	473	my $done = AnyEvent->condvar;
476		474
		475	# this forks and immediately calls exit in the child. this
		476	# normally has all sorts of bad consequences for your parent,
		477	# so take this as an example only. always fork and exec,
		478	# or call POSIX::_exit, in real code.
477	my $pid = fork or exit 5;	479	my $pid = fork or exit 5;
478		480
479	my $w = AnyEvent->child (	481	my $w = AnyEvent->child (
480	pid => $pid,	482	pid => $pid,
481	cb => sub {	483	cb => sub {
…		…
489	$done->recv;	491	$done->recv;
490		492
491	IDLE WATCHERS	493	IDLE WATCHERS
492	$w = AnyEvent->idle (cb => <callback>);	494	$w = AnyEvent->idle (cb => <callback>);
493		495
494	Repeatedly invoke the callback after the process becomes idle, until	496	This will repeatedly invoke the callback after the process becomes idle,
495	either the watcher is destroyed or new events have been detected.	497	until either the watcher is destroyed or new events have been detected.
496		498
497	Idle watchers are useful when there is a need to do something, but it is	499	Idle watchers are useful when there is a need to do something, but it is
498	not so important (or wise) to do it instantly. The callback will be	500	not so important (or wise) to do it instantly. The callback will be
499	invoked only when there is "nothing better to do", which is usually	501	invoked only when there is "nothing better to do", which is usually
500	defined as "all outstanding events have been handled and no new events	502	defined as "all outstanding events have been handled and no new events
…		…
570	called when the signal fires.	572	called when the signal fires.
571		573
572	* Condition variables are like "Merge Points" - points in your program	574	* Condition variables are like "Merge Points" - points in your program
573	where you merge multiple independent results/control flows into one.	575	where you merge multiple independent results/control flows into one.
574		576
575	* Condition variables represent a transaction - function that start	577	* Condition variables represent a transaction - functions that start
576	some kind of transaction can return them, leaving the caller the	578	some kind of transaction can return them, leaving the caller the
577	choice between waiting in a blocking fashion, or setting a callback.	579	choice between waiting in a blocking fashion, or setting a callback.
578		580
579	* Condition variables represent future values, or promises to deliver	581	* Condition variables represent future values, or promises to deliver
580	some result, long before the result is available.	582	some result, long before the result is available.
…		…
598		600
599	Condition variables are represented by hash refs in perl, and the keys	601	Condition variables are represented by hash refs in perl, and the keys
600	used by AnyEvent itself are all named "_ae_XXX" to make subclassing easy	602	used by AnyEvent itself are all named "_ae_XXX" to make subclassing easy
601	(it is often useful to build your own transaction class on top of	603	(it is often useful to build your own transaction class on top of
602	AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call	604	AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call
603	it's "new" method in your own "new" method.	605	its "new" method in your own "new" method.
604		606
605	There are two "sides" to a condition variable - the "producer side"	607	There are two "sides" to a condition variable - the "producer side"
606	which eventually calls "-> send", and the "consumer side", which waits	608	which eventually calls "-> send", and the "consumer side", which waits
607	for the send to occur.	609	for the send to occur.
608		610
…		…
668	Condition variables are overloaded so one can call them directly (as	670	Condition variables are overloaded so one can call them directly (as
669	if they were a code reference). Calling them directly is the same as	671	if they were a code reference). Calling them directly is the same as
670	calling "send".	672	calling "send".
671		673
672	$cv->croak ($error)	674	$cv->croak ($error)
673	Similar to send, but causes all call's to "->recv" to invoke	675	Similar to send, but causes all calls to "->recv" to invoke
674	"Carp::croak" with the given error message/object/scalar.	676	"Carp::croak" with the given error message/object/scalar.
675		677
676	This can be used to signal any errors to the condition variable	678	This can be used to signal any errors to the condition variable
677	user/consumer. Doing it this way instead of calling "croak" directly	679	user/consumer. Doing it this way instead of calling "croak" directly
678	delays the error detetcion, but has the overwhelmign advantage that	680	delays the error detection, but has the overwhelming advantage that
679	it diagnoses the error at the place where the result is expected,	681	it diagnoses the error at the place where the result is expected,
680	and not deep in some event clalback without connection to the actual	682	and not deep in some event callback with no connection to the actual
681	code causing the problem.	683	code causing the problem.
682		684
683	$cv->begin ([group callback])	685	$cv->begin ([group callback])
684	$cv->end	686	$cv->end
685	These two methods can be used to combine many transactions/events	687	These two methods can be used to combine many transactions/events
…		…
721	This works because for every event source (EOF on file handle),	723	This works because for every event source (EOF on file handle),
722	there is one call to "begin", so the condvar waits for all calls to	724	there is one call to "begin", so the condvar waits for all calls to
723	"end" before sending.	725	"end" before sending.
724		726
725	The ping example mentioned above is slightly more complicated, as	727	The ping example mentioned above is slightly more complicated, as
726	the there are results to be passwd back, and the number of tasks	728	the there are results to be passed back, and the number of tasks
727	that are begung can potentially be zero:	729	that are begun can potentially be zero:
728		730
729	my $cv = AnyEvent->condvar;	731	my $cv = AnyEvent->condvar;
730		732
731	my %result;	733	my %result;
732	$cv->begin (sub { shift->send (\%result) });	734	$cv->begin (sub { shift->send (\%result) });
…		…
739	};	741	};
740	}	742	}
741		743
742	$cv->end;	744	$cv->end;
743		745
		746	...
		747
		748	my $results = $cv->recv;
		749
744	This code fragment supposedly pings a number of hosts and calls	750	This code fragment supposedly pings a number of hosts and calls
745	"send" after results for all then have have been gathered - in any	751	"send" after results for all then have have been gathered - in any
746	order. To achieve this, the code issues a call to "begin" when it	752	order. To achieve this, the code issues a call to "begin" when it
747	starts each ping request and calls "end" when it has received some	753	starts each ping request and calls "end" when it has received some
748	result for it. Since "begin" and "end" only maintain a counter, the	754	result for it. Since "begin" and "end" only maintain a counter, the
…		…
753	callback to be called once the counter reaches 0, and second, it	759	callback to be called once the counter reaches 0, and second, it
754	ensures that "send" is called even when "no" hosts are being pinged	760	ensures that "send" is called even when "no" hosts are being pinged
755	(the loop doesn't execute once).	761	(the loop doesn't execute once).
756		762
757	This is the general pattern when you "fan out" into multiple (but	763	This is the general pattern when you "fan out" into multiple (but
758	potentially none) subrequests: use an outer "begin"/"end" pair to	764	potentially zero) subrequests: use an outer "begin"/"end" pair to
759	set the callback and ensure "end" is called at least once, and then,	765	set the callback and ensure "end" is called at least once, and then,
760	for each subrequest you start, call "begin" and for each subrequest	766	for each subrequest you start, call "begin" and for each subrequest
761	you finish, call "end".	767	you finish, call "end".
762		768
763	METHODS FOR CONSUMERS	769	METHODS FOR CONSUMERS
764	These methods should only be used by the consuming side, i.e. the code	770	These methods should only be used by the consuming side, i.e. the code
765	awaits the condition.	771	awaits the condition.
766		772
767	$cv->recv	773	$cv->recv
768	Wait (blocking if necessary) until the "->send" or "->croak" methods	774	Wait (blocking if necessary) until the "->send" or "->croak" methods
769	have been called on c<$cv>, while servicing other watchers normally.	775	have been called on $cv, while servicing other watchers normally.
770		776
771	You can only wait once on a condition - additional calls are valid	777	You can only wait once on a condition - additional calls are valid
772	but will return immediately.	778	but will return immediately.
773		779
774	If an error condition has been set by calling "->croak", then this	780	If an error condition has been set by calling "->croak", then this
…		…
777	In list context, all parameters passed to "send" will be returned,	783	In list context, all parameters passed to "send" will be returned,
778	in scalar context only the first one will be returned.	784	in scalar context only the first one will be returned.
779		785
780	Note that doing a blocking wait in a callback is not supported by	786	Note that doing a blocking wait in a callback is not supported by
781	any event loop, that is, recursive invocation of a blocking "->recv"	787	any event loop, that is, recursive invocation of a blocking "->recv"
782	is not allowed, and the "recv" call will "croak" if such a condition	788	is not allowed and the "recv" call will "croak" if such a condition
783	is detected. This condition can be slightly loosened by using	789	is detected. This requirement can be dropped by relying on
784	Coro::AnyEvent, which allows you to do a blocking "->recv" from any	790	Coro::AnyEvent , which allows you to do a blocking "->recv" from any
785	thread that doesn't run the event loop itself.	791	thread that doesn't run the event loop itself. Coro::AnyEvent is
		792	loaded automatically when Coro is used with AnyEvent, so code does
		793	not need to do anything special to take advantage of that: any code
		794	that would normally block your program because it calls "recv", be
		795	executed in an "async" thread instead without blocking other
		796	threads.
786		797
787	Not all event models support a blocking wait - some die in that case	798	Not all event models support a blocking wait - some die in that case
788	(programs might want to do that to stay interactive), so *if you are	799	(programs might want to do that to stay interactive), so *if you are
789	using this from a module, never require a blocking wait*. Instead,	800	using this from a module, never require a blocking wait*. Instead,
790	let the caller decide whether the call will block or not (for	801	let the caller decide whether the call will block or not (for
791	example, by coupling condition variables with some kind of request	802	example, by coupling condition variables with some kind of request
792	results and supporting callbacks so the caller knows that getting	803	results and supporting callbacks so the caller knows that getting
793	the result will not block, while still supporting blocking waits if	804	the result will not block, while still supporting blocking waits if
794	the caller so desires).	805	the caller so desires).
795		806
796	You can ensure that "-recv" never blocks by setting a callback and	807	You can ensure that "->recv" never blocks by setting a callback and
797	only calling "->recv" from within that callback (or at a later	808	only calling "->recv" from within that callback (or at a later
798	time). This will work even when the event loop does not support	809	time). This will work even when the event loop does not support
799	blocking waits otherwise.	810	blocking waits otherwise.
800		811
801	$bool = $cv->ready	812	$bool = $cv->ready
802	Returns true when the condition is "true", i.e. whether "send" or	813	Returns true when the condition is "true", i.e. whether "send" or
803	"croak" have been called.	814	"croak" have been called.
804		815
805	$cb = $cv->cb ($cb->($cv))	816	$cb = $cv->cb ($cb->($cv))
806	This is a mutator function that returns the callback set and	817	This is a mutator function that returns the callback set (or "undef"
807	optionally replaces it before doing so.	818	if not) and optionally replaces it before doing so.
808		819
809	The callback will be called when the condition becomes (or already	820	The callback will be called when the condition becomes "true", i.e.
810	was) "true", i.e. when "send" or "croak" are called (or were	821	when "send" or "croak" are called, with the only argument being the
811	called), with the only argument being the condition variable itself.	822	condition variable itself. If the condition is already true, the
812	Calling "recv" inside the callback or at any later time is	823	callback is called immediately when it is set. Calling "recv" inside
813	guaranteed not to block.	824	the callback or at any later time is guaranteed not to block.
		825
		826	Additionally, when the callback is invoked, it is also removed from
		827	the condvar (reset to "undef"), so the condvar does not keep a
		828	reference to the callback after invocation.
814		829
815	SUPPORTED EVENT LOOPS/BACKENDS	830	SUPPORTED EVENT LOOPS/BACKENDS
816	The available backend classes are (every class has its own manpage):	831	The following backend classes are part of the AnyEvent distribution
		832	(every class has its own manpage):
817		833
818	Backends that are autoprobed when no other event loop can be found.	834	Backends that are autoprobed when no other event loop can be found.
819	EV is the preferred backend when no other event loop seems to be in	835	EV is the preferred backend when no other event loop seems to be in
820	use. If EV is not installed, then AnyEvent will fall back to its own	836	use. If EV is not installed, then AnyEvent will fall back to its own
821	pure-perl implementation, which is available everywhere as it comes	837	pure-perl implementation, which is available everywhere as it comes
822	with AnyEvent itself.	838	with AnyEvent itself.
823		839
824	AnyEvent::Impl::EV based on EV (interface to libev, best choice).	840	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
825	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.	841	AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
826		842
827	Backends that are transparently being picked up when they are used.	843	Backends that are transparently being picked up when they are used.
828	These will be used when they are currently loaded when the first	844	These will be used if they are already loaded when the first watcher
829	watcher is created, in which case it is assumed that the application	845	is created, in which case it is assumed that the application is
830	is using them. This means that AnyEvent will automatically pick the	846	using them. This means that AnyEvent will automatically pick the
831	right backend when the main program loads an event module before	847	right backend when the main program loads an event module before
832	anything starts to create watchers. Nothing special needs to be done	848	anything starts to create watchers. Nothing special needs to be done
833	by the main program.	849	by the main program.
834		850
835	AnyEvent::Impl::Event based on Event, very stable, few glitches.	851	AnyEvent::Impl::Event based on Event, very stable, few glitches.
836	AnyEvent::Impl::Glib based on Glib, slow but very stable.	852	AnyEvent::Impl::Glib based on Glib, slow but very stable.
837	AnyEvent::Impl::Tk based on Tk, very broken.	853	AnyEvent::Impl::Tk based on Tk, very broken.
		854	AnyEvent::Impl::UV based on UV, innovated square wheels.
838	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	855	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
839	AnyEvent::Impl::POE based on POE, very slow, some limitations.	856	AnyEvent::Impl::POE based on POE, very slow, some limitations.
840	AnyEvent::Impl::Irssi used when running within irssi.	857	AnyEvent::Impl::Irssi used when running within irssi.
		858	AnyEvent::Impl::IOAsync based on IO::Async.
		859	AnyEvent::Impl::Cocoa based on Cocoa::EventLoop.
		860	AnyEvent::Impl::FLTK based on FLTK (fltk 2 binding).
841		861
842	Backends with special needs.	862	Backends with special needs.
843	Qt requires the Qt::Application to be instantiated first, but will	863	Qt requires the Qt::Application to be instantiated first, but will
844	otherwise be picked up automatically. As long as the main program	864	otherwise be picked up automatically. As long as the main program
845	instantiates the application before any AnyEvent watchers are	865	instantiates the application before any AnyEvent watchers are
846	created, everything should just work.	866	created, everything should just work.
847		867
848	AnyEvent::Impl::Qt based on Qt.	868	AnyEvent::Impl::Qt based on Qt.
849		869
850	Support for IO::Async can only be partial, as it is too broken and
851	architecturally limited to even support the AnyEvent API. It also is
852	the only event loop that needs the loop to be set explicitly, so it
853	can only be used by a main program knowing about AnyEvent. See
854	AnyEvent::Impl::Async for the gory details.
855
856	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
857
858	Event loops that are indirectly supported via other backends.	870	Event loops that are indirectly supported via other backends.
859	Some event loops can be supported via other modules:	871	Some event loops can be supported via other modules:
860		872
861	There is no direct support for WxWidgets (Wx) or Prima.	873	There is no direct support for WxWidgets (Wx) or Prima.
862		874
…		…
870		882
871	AnyEvent knows about both Prima and Wx, however, and will try to	883	AnyEvent knows about both Prima and Wx, however, and will try to
872	load POE when detecting them, in the hope that POE will pick them	884	load POE when detecting them, in the hope that POE will pick them
873	up, in which case everything will be automatic.	885	up, in which case everything will be automatic.
874		886
		887	Known event loops outside the AnyEvent distribution
		888	The following event loops or programs support AnyEvent by providing
		889	their own AnyEvent backend. They will be picked up automatically.
		890
		891	urxvt::anyevent available to rxvt-unicode extensions
		892
875	GLOBAL VARIABLES AND FUNCTIONS	893	GLOBAL VARIABLES AND FUNCTIONS
876	These are not normally required to use AnyEvent, but can be useful to	894	These are not normally required to use AnyEvent, but can be useful to
877	write AnyEvent extension modules.	895	write AnyEvent extension modules.
878		896
879	$AnyEvent::MODEL	897	$AnyEvent::MODEL
880	Contains "undef" until the first watcher is being created, before	898	Contains "undef" until the first watcher is being created, before
881	the backend has been autodetected.	899	the backend has been autodetected.
882		900
883	Afterwards it contains the event model that is being used, which is	901	Afterwards it contains the event model that is being used, which is
884	the name of the Perl class implementing the model. This class is	902	the name of the Perl class implementing the model. This class is
885	usually one of the "AnyEvent::Impl:xxx" modules, but can be any	903	usually one of the "AnyEvent::Impl::xxx" modules, but can be any
886	other class in the case AnyEvent has been extended at runtime (e.g.	904	other class in the case AnyEvent has been extended at runtime (e.g.
887	in rxvt-unicode it will be "urxvt::anyevent").	905	in rxvt-unicode it will be "urxvt::anyevent").
888		906
889	AnyEvent::detect	907	AnyEvent::detect
890	Returns $AnyEvent::MODEL, forcing autodetection of the event model	908	Returns $AnyEvent::MODEL, forcing autodetection of the event model
891	if necessary. You should only call this function right before you	909	if necessary. You should only call this function right before you
892	would have created an AnyEvent watcher anyway, that is, as late as	910	would have created an AnyEvent watcher anyway, that is, as late as
893	possible at runtime, and not e.g. while initialising of your module.	911	possible at runtime, and not e.g. during initialisation of your
		912	module.
		913
		914	The effect of calling this function is as if a watcher had been
		915	created (specifically, actions that happen "when the first watcher
		916	is created" happen when calling detetc as well).
894		917
895	If you need to do some initialisation before AnyEvent watchers are	918	If you need to do some initialisation before AnyEvent watchers are
896	created, use "post_detect".	919	created, use "post_detect".
897		920
898	$guard = AnyEvent::post_detect { BLOCK }	921	$guard = AnyEvent::post_detect { BLOCK }
899	Arranges for the code block to be executed as soon as the event	922	Arranges for the code block to be executed as soon as the event
900	model is autodetected (or immediately if this has already happened).	923	model is autodetected (or immediately if that has already happened).
901		924
902	The block will be executed after the actual backend has been	925	The block will be executed after the actual backend has been
903	detected ($AnyEvent::MODEL is set), but before any watchers have	926	detected ($AnyEvent::MODEL is set), so it is possible to do some
904	been created, so it is possible to e.g. patch @AnyEvent::ISA or do	927	initialisation only when AnyEvent is actually initialised - see the
905	other initialisations - see the sources of AnyEvent::Strict or
906	AnyEvent::AIO to see how this is used.	928	sources of AnyEvent::AIO to see how this is used.
907		929
908	The most common usage is to create some global watchers, without	930	The most common usage is to create some global watchers, without
909	forcing event module detection too early, for example, AnyEvent::AIO	931	forcing event module detection too early. For example, AnyEvent::AIO
910	creates and installs the global IO::AIO watcher in a "post_detect"	932	creates and installs the global IO::AIO watcher in a "post_detect"
911	block to avoid autodetecting the event module at load time.	933	block to avoid autodetecting the event module at load time.
912		934
913	If called in scalar or list context, then it creates and returns an	935	If called in scalar or list context, then it creates and returns an
914	object that automatically removes the callback again when it is	936	object that automatically removes the callback again when it is
915	destroyed (or "undef" when the hook was immediately executed). See	937	destroyed (or "undef" when the hook was immediately executed). See
916	AnyEvent::AIO for a case where this is useful.	938	AnyEvent::AIO for a case where this is useful.
917		939
918	Example: Create a watcher for the IO::AIO module and store it in	940	Example: Create a watcher for the IO::AIO module and store it in
919	$WATCHER. Only do so after the event loop is initialised, though.	941	$WATCHER, but do so only do so after the event loop is initialised.
920		942
921	our WATCHER;	943	our WATCHER;
922		944
923	my $guard = AnyEvent::post_detect {	945	my $guard = AnyEvent::post_detect {
924	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);	946	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
…		…
930	# able to just C<undef $WATCHER> if the watcher causes them grief.	952	# able to just C<undef $WATCHER> if the watcher causes them grief.
931		953
932	$WATCHER \|\|= $guard;	954	$WATCHER \|\|= $guard;
933		955
934	@AnyEvent::post_detect	956	@AnyEvent::post_detect
935	If there are any code references in this array (you can "push" to it	957	This is a lower level interface then "AnyEvent::post_detect" (the
936	before or after loading AnyEvent), then they will called directly	958	function). This variable is mainly useful for modules that can do
		959	something useful when AnyEvent is used and thus want to know when it
		960	is initialised, but do not need to even load it by default. This
		961	array provides the means to hook into AnyEvent passively, without
		962	loading it.
		963
		964	Here is how it works: If there are any code references in this array
		965	(you can "push" to it before or after loading AnyEvent), then they
937	after the event loop has been chosen.	966	will be called directly after the event loop has been chosen.
938		967
939	You should check $AnyEvent::MODEL before adding to this array,	968	You should check $AnyEvent::MODEL before adding to this array,
940	though: if it is defined then the event loop has already been	969	though: if it is defined then the event loop has already been
941	detected, and the array will be ignored.	970	detected, and the array will be ignored.
942		971
943	Best use "AnyEvent::post_detect { BLOCK }" when your application	972	Best use "AnyEvent::post_detect { BLOCK }" when your application
944	allows it, as it takes care of these details.	973	allows it, as it takes care of these details.
945
946	This variable is mainly useful for modules that can do something
947	useful when AnyEvent is used and thus want to know when it is
948	initialised, but do not need to even load it by default. This array
949	provides the means to hook into AnyEvent passively, without loading
950	it.
951		974
952	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used	975	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
953	together, you could put this into Coro (this is the actual code used	976	together, you could put this into Coro (this is the actual code used
954	by Coro to accomplish this):	977	by Coro to accomplish this):
955		978
…		…
960	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent	983	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
961	# as soon as it is	984	# as soon as it is
962	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };	985	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
963	}	986	}
964		987
		988	AnyEvent::postpone { BLOCK }
		989	Arranges for the block to be executed as soon as possible, but not
		990	before the call itself returns. In practise, the block will be
		991	executed just before the event loop polls for new events, or shortly
		992	afterwards.
		993
		994	This function never returns anything (to make the "return postpone {
		995	... }" idiom more useful.
		996
		997	To understand the usefulness of this function, consider a function
		998	that asynchronously does something for you and returns some
		999	transaction object or guard to let you cancel the operation. For
		1000	example, "AnyEvent::Socket::tcp_connect":
		1001
		1002	# start a connection attempt unless one is active
		1003	$self->{connect_guard} \|\|= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
		1004	delete $self->{connect_guard};
		1005	...
		1006	};
		1007
		1008	Imagine that this function could instantly call the callback, for
		1009	example, because it detects an obvious error such as a negative port
		1010	number. Invoking the callback before the function returns causes
		1011	problems however: the callback will be called and will try to delete
		1012	the guard object. But since the function hasn't returned yet, there
		1013	is nothing to delete. When the function eventually returns it will
		1014	assign the guard object to "$self->{connect_guard}", where it will
		1015	likely never be deleted, so the program thinks it is still trying to
		1016	connect.
		1017
		1018	This is where "AnyEvent::postpone" should be used. Instead of
		1019	calling the callback directly on error:
		1020
		1021	$cb->(undef), return # signal error to callback, BAD!
		1022	if $some_error_condition;
		1023
		1024	It should use "postpone":
		1025
		1026	AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
		1027	if $some_error_condition;
		1028
		1029	AnyEvent::log $level, $msg[, @args]
		1030	Log the given $msg at the given $level.
		1031
		1032	If AnyEvent::Log is not loaded then this function makes a simple
		1033	test to see whether the message will be logged. If the test succeeds
		1034	it will load AnyEvent::Log and call "AnyEvent::Log::log" -
		1035	consequently, look at the AnyEvent::Log documentation for details.
		1036
		1037	If the test fails it will simply return. Right now this happens when
		1038	a numerical loglevel is used and it is larger than the level
		1039	specified via $ENV{PERL_ANYEVENT_VERBOSE}.
		1040
		1041	If you want to sprinkle loads of logging calls around your code,
		1042	consider creating a logger callback with the "AnyEvent::Log::logger"
		1043	function, which can reduce typing, codesize and can reduce the
		1044	logging overhead enourmously.
		1045
		1046	AnyEvent::fh_block $filehandle
		1047	AnyEvent::fh_unblock $filehandle
		1048	Sets blocking or non-blocking behaviour for the given filehandle.
		1049
965	WHAT TO DO IN A MODULE	1050	WHAT TO DO IN A MODULE
966	As a module author, you should "use AnyEvent" and call AnyEvent methods	1051	As a module author, you should "use AnyEvent" and call AnyEvent methods
967	freely, but you should not load a specific event module or rely on it.	1052	freely, but you should not load a specific event module or rely on it.
968		1053
969	Be careful when you create watchers in the module body - AnyEvent will	1054	Be careful when you create watchers in the module body - AnyEvent will
…		…
976	stall the whole program, and the whole point of using events is to stay	1061	stall the whole program, and the whole point of using events is to stay
977	interactive.	1062	interactive.
978		1063
979	It is fine, however, to call "->recv" when the user of your module	1064	It is fine, however, to call "->recv" when the user of your module
980	requests it (i.e. if you create a http request object ad have a method	1065	requests it (i.e. if you create a http request object ad have a method
981	called "results" that returns the results, it should call "->recv"	1066	called "results" that returns the results, it may call "->recv" freely,
982	freely, as the user of your module knows what she is doing. always).	1067	as the user of your module knows what she is doing. Always).
983		1068
984	WHAT TO DO IN THE MAIN PROGRAM	1069	WHAT TO DO IN THE MAIN PROGRAM
985	There will always be a single main program - the only place that should	1070	There will always be a single main program - the only place that should
986	dictate which event model to use.	1071	dictate which event model to use.
987		1072
988	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1073	If the program is not event-based, it need not do anything special, even
989	do anything special (it does not need to be event-based) and let	1074	when it depends on a module that uses an AnyEvent. If the program itself
990	AnyEvent decide which implementation to chose if some module relies on	1075	uses AnyEvent, but does not care which event loop is used, all it needs
991	it.	1076	to do is "use AnyEvent". In either case, AnyEvent will choose the best
		1077	available loop implementation.
992		1078
993	If the main program relies on a specific event model - for example, in	1079	If the main program relies on a specific event model - for example, in
994	Gtk2 programs you have to rely on the Glib module - you should load the	1080	Gtk2 programs you have to rely on the Glib module - you should load the
995	event module before loading AnyEvent or any module that uses it:	1081	event module before loading AnyEvent or any module that uses it:
996	generally speaking, you should load it as early as possible. The reason	1082	generally speaking, you should load it as early as possible. The reason
997	is that modules might create watchers when they are loaded, and AnyEvent	1083	is that modules might create watchers when they are loaded, and AnyEvent
998	will decide on the event model to use as soon as it creates watchers,	1084	will decide on the event model to use as soon as it creates watchers,
999	and it might chose the wrong one unless you load the correct one	1085	and it might choose the wrong one unless you load the correct one
1000	yourself.	1086	yourself.
1001		1087
1002	You can chose to use a pure-perl implementation by loading the	1088	You can chose to use a pure-perl implementation by loading the
1003	"AnyEvent::Impl::Perl" module, which gives you similar behaviour	1089	"AnyEvent::Loop" module, which gives you similar behaviour everywhere,
1004	everywhere, but letting AnyEvent chose the model is generally better.	1090	but letting AnyEvent chose the model is generally better.
1005		1091
1006	MAINLOOP EMULATION	1092	MAINLOOP EMULATION
1007	Sometimes (often for short test scripts, or even standalone programs who	1093	Sometimes (often for short test scripts, or even standalone programs who
1008	only want to use AnyEvent), you do not want to run a specific event	1094	only want to use AnyEvent), you do not want to run a specific event
1009	loop.	1095	loop.
…		…
1021		1107
1022	OTHER MODULES	1108	OTHER MODULES
1023	The following is a non-exhaustive list of additional modules that use	1109	The following is a non-exhaustive list of additional modules that use
1024	AnyEvent as a client and can therefore be mixed easily with other	1110	AnyEvent as a client and can therefore be mixed easily with other
1025	AnyEvent modules and other event loops in the same program. Some of the	1111	AnyEvent modules and other event loops in the same program. Some of the
1026	modules come as part of AnyEvent, the others are available via CPAN.	1112	modules come as part of AnyEvent, the others are available via CPAN (see
		1113	<http://search.cpan.org/search?m=module&q=anyevent%3A%3A*> for a longer
		1114	non-exhaustive list), and the list is heavily biased towards modules of
		1115	the AnyEvent author himself :)
1027		1116
1028	AnyEvent::Util	1117	AnyEvent::Util (part of the AnyEvent distribution)
1029	Contains various utility functions that replace often-used but	1118	Contains various utility functions that replace often-used blocking
1030	blocking functions such as "inet_aton" by event-/callback-based	1119	functions such as "inet_aton" with event/callback-based versions.
1031	versions.
1032		1120
1033	AnyEvent::Socket	1121	AnyEvent::Socket (part of the AnyEvent distribution)
1034	Provides various utility functions for (internet protocol) sockets,	1122	Provides various utility functions for (internet protocol) sockets,
1035	addresses and name resolution. Also functions to create non-blocking	1123	addresses and name resolution. Also functions to create non-blocking
1036	tcp connections or tcp servers, with IPv6 and SRV record support and	1124	tcp connections or tcp servers, with IPv6 and SRV record support and
1037	more.	1125	more.
1038		1126
1039	AnyEvent::Handle	1127	AnyEvent::Handle (part of the AnyEvent distribution)
1040	Provide read and write buffers, manages watchers for reads and	1128	Provide read and write buffers, manages watchers for reads and
1041	writes, supports raw and formatted I/O, I/O queued and fully	1129	writes, supports raw and formatted I/O, I/O queued and fully
1042	transparent and non-blocking SSL/TLS (via AnyEvent::TLS.	1130	transparent and non-blocking SSL/TLS (via AnyEvent::TLS).
1043		1131
1044	AnyEvent::DNS	1132	AnyEvent::DNS (part of the AnyEvent distribution)
1045	Provides rich asynchronous DNS resolver capabilities.	1133	Provides rich asynchronous DNS resolver capabilities.
1046		1134
1047	AnyEvent::HTTP, AnyEvent::IRC, AnyEvent::XMPP, AnyEvent::GPSD,	1135	AnyEvent::HTTP, AnyEvent::IRC, AnyEvent::XMPP, AnyEvent::GPSD,
1048	AnyEvent::IGS, AnyEvent::FCP	1136	AnyEvent::IGS, AnyEvent::FCP
1049	Implement event-based interfaces to the protocols of the same name	1137	Implement event-based interfaces to the protocols of the same name
1050	(for the curious, IGS is the International Go Server and FCP is the	1138	(for the curious, IGS is the International Go Server and FCP is the
1051	Freenet Client Protocol).	1139	Freenet Client Protocol).
1052		1140
1053	AnyEvent::Handle::UDP	1141	AnyEvent::AIO (part of the AnyEvent distribution)
1054	Here be danger!
1055
1056	As Pauli would put it, "Not only is it not right, it's not even
1057	wrong!" - there are so many things wrong with AnyEvent::Handle::UDP,
1058	most notably it's use of a stream-based API with a protocol that
1059	isn't streamable, that the only way to improve it is to delete it.
1060
1061	It features data corruption (but typically only under load) and
1062	general confusion. On top, the author is not only clueless about UDP
1063	but also fact-resistant - some gems of his understanding: "connect
1064	doesn't work with UDP", "UDP packets are not IP packets", "UDP only
1065	has datagrams, not packets", "I don't need to implement proper error
1066	checking as UDP doesn't support error checking" and so on - he
1067	doesn't even understand what's wrong with his module when it is
1068	explained to him.
1069
1070	AnyEvent::DBI
1071	Executes DBI requests asynchronously in a proxy process for you,
1072	notifying you in an event-bnased way when the operation is finished.
1073
1074	AnyEvent::AIO
1075	Truly asynchronous (as opposed to non-blocking) I/O, should be in	1142	Truly asynchronous (as opposed to non-blocking) I/O, should be in
1076	the toolbox of every event programmer. AnyEvent::AIO transparently	1143	the toolbox of every event programmer. AnyEvent::AIO transparently
1077	fuses IO::AIO and AnyEvent together, giving AnyEvent access to	1144	fuses IO::AIO and AnyEvent together, giving AnyEvent access to
1078	event-based file I/O, and much more.	1145	event-based file I/O, and much more.
1079		1146
		1147	AnyEvent::Fork, AnyEvent::Fork::RPC, AnyEvent::Fork::Pool,
		1148	AnyEvent::Fork::Remote
		1149	These let you safely fork new subprocesses, either locally or
		1150	remotely (e.g.v ia ssh), using some RPC protocol or not, without the
		1151	limitations normally imposed by fork (AnyEvent works fine for
		1152	example). Dynamically-resized worker pools are obviously included as
		1153	well.
		1154
		1155	And they are quite tiny and fast as well - "abusing" AnyEvent::Fork
		1156	just to exec external programs can easily beat using "fork" and
		1157	"exec" (or even "system") in most programs.
		1158
		1159	AnyEvent::Filesys::Notify
		1160	AnyEvent is good for non-blocking stuff, but it can't detect file or
		1161	path changes (e.g. "watch this directory for new files", "watch this
		1162	file for changes"). The AnyEvent::Filesys::Notify module promises to
		1163	do just that in a portbale fashion, supporting inotify on GNU/Linux
		1164	and some weird, without doubt broken, stuff on OS X to monitor
		1165	files. It can fall back to blocking scans at regular intervals
		1166	transparently on other platforms, so it's about as portable as it
		1167	gets.
		1168
		1169	(I haven't used it myself, but it seems the biggest problem with it
		1170	is it quite bad performance).
		1171
1080	AnyEvent::HTTPD	1172	AnyEvent::DBI
1081	A simple embedded webserver.	1173	Executes DBI requests asynchronously in a proxy process for you,
		1174	notifying you in an event-based way when the operation is finished.
1082		1175
1083	AnyEvent::FastPing	1176	AnyEvent::FastPing
1084	The fastest ping in the west.	1177	The fastest ping in the west.
1085		1178
1086	Coro	1179	Coro
1087	Has special support for AnyEvent via Coro::AnyEvent.	1180	Has special support for AnyEvent via Coro::AnyEvent, which allows
		1181	you to simply invert the flow control - don't call us, we will call
		1182	you:
		1183
		1184	async {
		1185	Coro::AnyEvent::sleep 5; # creates a 5s timer and waits for it
		1186	print "5 seconds later!\n";
		1187
		1188	Coro::AnyEvent::readable *STDIN; # uses an I/O watcher
		1189	my $line = <STDIN>; # works for ttys
		1190
		1191	AnyEvent::HTTP::http_get "url", Coro::rouse_cb;
		1192	my ($body, $hdr) = Coro::rouse_wait;
		1193	};
1088		1194
1089	SIMPLIFIED AE API	1195	SIMPLIFIED AE API
1090	Starting with version 5.0, AnyEvent officially supports a second, much	1196	Starting with version 5.0, AnyEvent officially supports a second, much
1091	simpler, API that is designed to reduce the calling, typing and memory	1197	simpler, API that is designed to reduce the calling, typing and memory
1092	overhead by using function call syntax and a fixed number of parameters.	1198	overhead by using function call syntax and a fixed number of parameters.
…		…
1108	The pure perl event loop simply re-throws the exception (usually within	1214	The pure perl event loop simply re-throws the exception (usually within
1109	"condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()",	1215	"condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()",
1110	Glib uses "install_exception_handler" and so on.	1216	Glib uses "install_exception_handler" and so on.
1111		1217
1112	ENVIRONMENT VARIABLES	1218	ENVIRONMENT VARIABLES
1113	The following environment variables are used by this module or its	1219	AnyEvent supports a number of environment variables that tune the
1114	submodules.	1220	runtime behaviour. They are usually evaluated when AnyEvent is loaded,
		1221	initialised, or a submodule that uses them is loaded. Many of them also
		1222	cause AnyEvent to load additional modules - for example,
		1223	"PERL_ANYEVENT_DEBUG_WRAP" causes the AnyEvent::Debug module to be
		1224	loaded.
1115		1225
1116	Note that AnyEvent will remove all environment variables starting with	1226	All the environment variables documented here start with
1117	"PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is	1227	"PERL_ANYEVENT_", which is what AnyEvent considers its own namespace.
1118	enabled.	1228	Other modules are encouraged (but by no means required) to use
		1229	"PERL_ANYEVENT_SUBMODULE" if they have registered the
		1230	AnyEvent::Submodule namespace on CPAN, for any submodule. For example,
		1231	AnyEvent::HTTP could be expected to use "PERL_ANYEVENT_HTTP_PROXY" (it
		1232	should not access env variables starting with "AE_", see below).
		1233
		1234	All variables can also be set via the "AE_" prefix, that is, instead of
		1235	setting "PERL_ANYEVENT_VERBOSE" you can also set "AE_VERBOSE". In case
		1236	there is a clash btween anyevent and another program that uses
		1237	"AE_something" you can set the corresponding "PERL_ANYEVENT_something"
		1238	variable to the empty string, as those variables take precedence.
		1239
		1240	When AnyEvent is first loaded, it copies all "AE_xxx" env variables to
		1241	their "PERL_ANYEVENT_xxx" counterpart unless that variable already
		1242	exists. If taint mode is on, then AnyEvent will remove all environment
		1243	variables starting with "PERL_ANYEVENT_" from %ENV (or replace them with
		1244	"undef" or the empty string, if the corresaponding "AE_" variable is
		1245	set).
		1246
		1247	The exact algorithm is currently:
		1248
		1249	1. if taint mode enabled, delete all PERL_ANYEVENT_xyz variables from %ENV
		1250	2. copy over AE_xyz to PERL_ANYEVENT_xyz unless the latter alraedy exists
		1251	3. if taint mode enabled, set all PERL_ANYEVENT_xyz variables to undef.
		1252
		1253	This ensures that child processes will not see the "AE_" variables.
		1254
		1255	The following environment variables are currently known to AnyEvent:
1119		1256
1120	"PERL_ANYEVENT_VERBOSE"	1257	"PERL_ANYEVENT_VERBOSE"
1121	By default, AnyEvent will be completely silent except in fatal	1258	By default, AnyEvent will log messages with loglevel 4 ("error") or
1122	conditions. You can set this environment variable to make AnyEvent	1259	higher (see AnyEvent::Log). You can set this environment variable to
1123	more talkative.	1260	a numerical loglevel to make AnyEvent more (or less) talkative.
1124		1261
		1262	If you want to do more than just set the global logging level you
		1263	should have a look at "PERL_ANYEVENT_LOG", which allows much more
		1264	complex specifications.
		1265
		1266	When set to 0 ("off"), then no messages whatsoever will be logged
		1267	with everything else at defaults.
		1268
1125	When set to 1 or higher, causes AnyEvent to warn about unexpected	1269	When set to 5 or higher ("warn"), AnyEvent warns about unexpected
1126	conditions, such as not being able to load the event model specified	1270	conditions, such as not being able to load the event model specified
1127	by "PERL_ANYEVENT_MODEL".	1271	by "PERL_ANYEVENT_MODEL", or a guard callback throwing an exception
		1272	- this is the minimum recommended level for use during development.
1128		1273
1129	When set to 2 or higher, cause AnyEvent to report to STDERR which	1274	When set to 7 or higher (info), AnyEvent reports which event model
1130	event model it chooses.	1275	it chooses.
1131		1276
1132	When set to 8 or higher, then AnyEvent will report extra information	1277	When set to 8 or higher (debug), then AnyEvent will report extra
1133	on which optional modules it loads and how it implements certain	1278	information on which optional modules it loads and how it implements
1134	features.	1279	certain features.
		1280
		1281	"PERL_ANYEVENT_LOG"
		1282	Accepts rather complex logging specifications. For example, you
		1283	could log all "debug" messages of some module to stderr, warnings
		1284	and above to stderr, and errors and above to syslog, with:
		1285
		1286	PERL_ANYEVENT_LOG=Some::Module=debug,+log:filter=warn,+%syslog:%syslog=error,syslog
		1287
		1288	For the rather extensive details, see AnyEvent::Log.
		1289
		1290	This variable is evaluated when AnyEvent (or AnyEvent::Log) is
		1291	loaded, so will take effect even before AnyEvent has initialised
		1292	itself.
		1293
		1294	Note that specifying this environment variable causes the
		1295	AnyEvent::Log module to be loaded, while "PERL_ANYEVENT_VERBOSE"
		1296	does not, so only using the latter saves a few hundred kB of memory
		1297	unless a module explicitly needs the extra features of
		1298	AnyEvent::Log.
1135		1299
1136	"PERL_ANYEVENT_STRICT"	1300	"PERL_ANYEVENT_STRICT"
1137	AnyEvent does not do much argument checking by default, as thorough	1301	AnyEvent does not do much argument checking by default, as thorough
1138	argument checking is very costly. Setting this variable to a true	1302	argument checking is very costly. Setting this variable to a true
1139	value will cause AnyEvent to load "AnyEvent::Strict" and then to	1303	value will cause AnyEvent to load "AnyEvent::Strict" and then to
1140	thoroughly check the arguments passed to most method calls. If it	1304	thoroughly check the arguments passed to most method calls. If it
1141	finds any problems, it will croak.	1305	finds any problems, it will croak.
1142		1306
1143	In other words, enables "strict" mode.	1307	In other words, enables "strict" mode.
1144		1308
1145	Unlike "use strict" (or it's modern cousin, "use common::sense", it	1309	Unlike "use strict" (or its modern cousin, "use common::sense", it
1146	is definitely recommended to keep it off in production. Keeping	1310	is definitely recommended to keep it off in production. Keeping
1147	"PERL_ANYEVENT_STRICT=1" in your environment while developing	1311	"PERL_ANYEVENT_STRICT=1" in your environment while developing
1148	programs can be very useful, however.	1312	programs can be very useful, however.
1149		1313
		1314	"PERL_ANYEVENT_DEBUG_SHELL"
		1315	If this env variable is nonempty, then its contents will be
		1316	interpreted by "AnyEvent::Socket::parse_hostport" and
		1317	"AnyEvent::Debug::shell" (after replacing every occurance of $$ by
		1318	the process pid). The shell object is saved in
		1319	$AnyEvent::Debug::SHELL.
		1320
		1321	This happens when the first watcher is created.
		1322
		1323	For example, to bind a debug shell on a unix domain socket in
		1324	/tmp/debug<pid>.sock, you could use this:
		1325
		1326	PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog
		1327	# connect with e.g.: socat readline /tmp/debug123.sock
		1328
		1329	Or to bind to tcp port 4545 on localhost:
		1330
		1331	PERL_ANYEVENT_DEBUG_SHELL=127.0.0.1:4545 perlprog
		1332	# connect with e.g.: telnet localhost 4545
		1333
		1334	Note that creating sockets in /tmp or on localhost is very unsafe on
		1335	multiuser systems.
		1336
		1337	"PERL_ANYEVENT_DEBUG_WRAP"
		1338	Can be set to 0, 1 or 2 and enables wrapping of all watchers for
		1339	debugging purposes. See "AnyEvent::Debug::wrap" for details.
		1340
1150	"PERL_ANYEVENT_MODEL"	1341	"PERL_ANYEVENT_MODEL"
1151	This can be used to specify the event model to be used by AnyEvent,	1342	This can be used to specify the event model to be used by AnyEvent,
1152	before auto detection and -probing kicks in. It must be a string	1343	before auto detection and -probing kicks in.
1153	consisting entirely of ASCII letters. The string "AnyEvent::Impl::"	1344
1154	gets prepended and the resulting module name is loaded and if the	1345	It normally is a string consisting entirely of ASCII letters (e.g.
1155	load was successful, used as event model. If it fails to load	1346	"EV" or "IOAsync"). The string "AnyEvent::Impl::" gets prepended and
		1347	the resulting module name is loaded and - if the load was successful
		1348	- used as event model backend. If it fails to load then AnyEvent
1156	AnyEvent will proceed with auto detection and -probing.	1349	will proceed with auto detection and -probing.
1157		1350
1158	This functionality might change in future versions.	1351	If the string ends with "::" instead (e.g. "AnyEvent::Impl::EV::")
		1352	then nothing gets prepended and the module name is used as-is (hint:
		1353	"::" at the end of a string designates a module name and quotes it
		1354	appropriately).
1159		1355
1160	For example, to force the pure perl model (AnyEvent::Impl::Perl) you	1356	For example, to force the pure perl model (AnyEvent::Loop::Perl) you
1161	could start your program like this:	1357	could start your program like this:
1162		1358
1163	PERL_ANYEVENT_MODEL=Perl perl ...	1359	PERL_ANYEVENT_MODEL=Perl perl ...
		1360
		1361	"PERL_ANYEVENT_IO_MODEL"
		1362	The current file I/O model - see AnyEvent::IO for more info.
		1363
		1364	At the moment, only "Perl" (small, pure-perl, synchronous) and
		1365	"IOAIO" (truly asynchronous) are supported. The default is "IOAIO"
		1366	if AnyEvent::AIO can be loaded, otherwise it is "Perl".
1164		1367
1165	"PERL_ANYEVENT_PROTOCOLS"	1368	"PERL_ANYEVENT_PROTOCOLS"
1166	Used by both AnyEvent::DNS and AnyEvent::Socket to determine	1369	Used by both AnyEvent::DNS and AnyEvent::Socket to determine
1167	preferences for IPv4 or IPv6. The default is unspecified (and might	1370	preferences for IPv4 or IPv6. The default is unspecified (and might
1168	change, or be the result of auto probing).	1371	change, or be the result of auto probing).
…		…
1172	mentioned will be used, and preference will be given to protocols	1375	mentioned will be used, and preference will be given to protocols
1173	mentioned earlier in the list.	1376	mentioned earlier in the list.
1174		1377
1175	This variable can effectively be used for denial-of-service attacks	1378	This variable can effectively be used for denial-of-service attacks
1176	against local programs (e.g. when setuid), although the impact is	1379	against local programs (e.g. when setuid), although the impact is
1177	likely small, as the program has to handle conenction and other	1380	likely small, as the program has to handle connection and other
1178	failures anyways.	1381	failures anyways.
1179		1382
1180	Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over	1383	Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over
1181	IPv6, but support both and try to use both.	1384	IPv6, but support both and try to use both.
1182	"PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to	1385	"PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to
1183	resolve or contact IPv6 addresses.	1386	resolve or contact IPv6 addresses.
1184	"PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4" support either IPv4 or IPv6, but	1387	"PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4" support either IPv4 or IPv6, but
1185	prefer IPv6 over IPv4.	1388	prefer IPv6 over IPv4.
1186		1389
		1390	"PERL_ANYEVENT_HOSTS"
		1391	This variable, if specified, overrides the /etc/hosts file used by
		1392	AnyEvent::Socket"::resolve_sockaddr", i.e. hosts aliases will be
		1393	read from that file instead.
		1394
1187	"PERL_ANYEVENT_EDNS0"	1395	"PERL_ANYEVENT_EDNS0"
1188	Used by AnyEvent::DNS to decide whether to use the EDNS0 extension	1396	Used by AnyEvent::DNS to decide whether to use the EDNS0 extension
1189	for DNS. This extension is generally useful to reduce DNS traffic,	1397	for DNS. This extension is generally useful to reduce DNS traffic,
1190	but some (broken) firewalls drop such DNS packets, which is why it	1398	especially when DNSSEC is involved, but some (broken) firewalls drop
1191	is off by default.	1399	such DNS packets, which is why it is off by default.
1192		1400
1193	Setting this variable to 1 will cause AnyEvent::DNS to announce	1401	Setting this variable to 1 will cause AnyEvent::DNS to announce
1194	EDNS0 in its DNS requests.	1402	EDNS0 in its DNS requests.
1195		1403
1196	"PERL_ANYEVENT_MAX_FORKS"	1404	"PERL_ANYEVENT_MAX_FORKS"
…		…
1200	"PERL_ANYEVENT_MAX_OUTSTANDING_DNS"	1408	"PERL_ANYEVENT_MAX_OUTSTANDING_DNS"
1201	The default value for the "max_outstanding" parameter for the	1409	The default value for the "max_outstanding" parameter for the
1202	default DNS resolver - this is the maximum number of parallel DNS	1410	default DNS resolver - this is the maximum number of parallel DNS
1203	requests that are sent to the DNS server.	1411	requests that are sent to the DNS server.
1204		1412
		1413	"PERL_ANYEVENT_MAX_SIGNAL_LATENCY"
		1414	Perl has inherently racy signal handling (you can basically choose
		1415	between losing signals and memory corruption) - pure perl event
		1416	loops (including "AnyEvent::Loop", when "Async::Interrupt" isn't
		1417	available) therefore have to poll regularly to avoid losing signals.
		1418
		1419	Some event loops are racy, but don't poll regularly, and some event
		1420	loops are written in C but are still racy. For those event loops,
		1421	AnyEvent installs a timer that regularly wakes up the event loop.
		1422
		1423	By default, the interval for this timer is 10 seconds, but you can
		1424	override this delay with this environment variable (or by setting
		1425	the $AnyEvent::MAX_SIGNAL_LATENCY variable before creating signal
		1426	watchers).
		1427
		1428	Lower values increase CPU (and energy) usage, higher values can
		1429	introduce long delays when reaping children or waiting for signals.
		1430
		1431	The AnyEvent::Async module, if available, will be used to avoid this
		1432	polling (with most event loops).
		1433
1205	"PERL_ANYEVENT_RESOLV_CONF"	1434	"PERL_ANYEVENT_RESOLV_CONF"
1206	The file to use instead of /etc/resolv.conf (or OS-specific	1435	The absolute path to a resolv.conf-style file to use instead of
1207	configuration) in the default resolver. When set to the empty	1436	/etc/resolv.conf (or the OS-specific configuration) in the default
1208	string, no default config will be used.	1437	resolver, or the empty string to select the default configuration.
1209		1438
1210	"PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH".	1439	"PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH".
1211	When neither "ca_file" nor "ca_path" was specified during	1440	When neither "ca_file" nor "ca_path" was specified during
1212	AnyEvent::TLS context creation, and either of these environment	1441	AnyEvent::TLS context creation, and either of these environment
1213	variables exist, they will be used to specify CA certificate	1442	variables are nonempty, they will be used to specify CA certificate
1214	locations instead of a system-dependent default.	1443	locations instead of a system-dependent default.
1215		1444
1216	"PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT"	1445	"PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT"
1217	When these are set to 1, then the respective modules are not loaded.	1446	When these are set to 1, then the respective modules are not loaded.
1218	Mostly good for testing AnyEvent itself.	1447	Mostly good for testing AnyEvent itself.
…		…
1390	my $txn = shift;	1619	my $txn = shift;
1391	my $data = $txn->result;	1620	my $data = $txn->result;
1392	...	1621	...
1393	});	1622	});
1394		1623
1395	EV::loop;	1624	EV::run;
1396		1625
1397	3b. The module user could use AnyEvent, too:	1626	3b. The module user could use AnyEvent, too:
1398		1627
1399	use AnyEvent;	1628	use AnyEvent;
1400		1629
…		…
1538	when used without AnyEvent), but most event loops have acceptable	1767	when used without AnyEvent), but most event loops have acceptable
1539	performance with or without AnyEvent.	1768	performance with or without AnyEvent.
1540		1769
1541	* The overhead AnyEvent adds is usually much smaller than the overhead	1770	* The overhead AnyEvent adds is usually much smaller than the overhead
1542	of the actual event loop, only with extremely fast event loops such	1771	of the actual event loop, only with extremely fast event loops such
1543	as EV adds AnyEvent significant overhead.	1772	as EV does AnyEvent add significant overhead.
1544		1773
1545	* You should avoid POE like the plague if you want performance or	1774	* You should avoid POE like the plague if you want performance or
1546	reasonable memory usage.	1775	reasonable memory usage.
1547		1776
1548	BENCHMARKING THE LARGE SERVER CASE	1777	BENCHMARKING THE LARGE SERVER CASE
…		…
1746		1975
1747	Feel free to install your own handler, or reset it to defaults.	1976	Feel free to install your own handler, or reset it to defaults.
1748		1977
1749	RECOMMENDED/OPTIONAL MODULES	1978	RECOMMENDED/OPTIONAL MODULES
1750	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and	1979	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
1751	it's built-in modules) are required to use it.	1980	its built-in modules) are required to use it.
1752		1981
1753	That does not mean that AnyEvent won't take advantage of some additional	1982	That does not mean that AnyEvent won't take advantage of some additional
1754	modules if they are installed.	1983	modules if they are installed.
1755		1984
1756	This section explains which additional modules will be used, and how	1985	This section explains which additional modules will be used, and how
…		…
1807	worthwhile: If this module is installed, then AnyEvent::Handle (with	2036	worthwhile: If this module is installed, then AnyEvent::Handle (with
1808	the help of AnyEvent::TLS), gains the ability to do TLS/SSL.	2037	the help of AnyEvent::TLS), gains the ability to do TLS/SSL.
1809		2038
1810	Time::HiRes	2039	Time::HiRes
1811	This module is part of perl since release 5.008. It will be used	2040	This module is part of perl since release 5.008. It will be used
1812	when the chosen event library does not come with a timing source on	2041	when the chosen event library does not come with a timing source of
1813	it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will	2042	its own. The pure-perl event loop (AnyEvent::Loop) will additionally
1814	additionally use it to try to use a monotonic clock for timing	2043	load it to try to use a monotonic clock for timing stability.
1815	stability.	2044
		2045	AnyEvent::AIO (and IO::AIO)
		2046	The default implementation of AnyEvent::IO is to do I/O
		2047	synchronously, stopping programs while they access the disk, which
		2048	is fine for a lot of programs.
		2049
		2050	Installing AnyEvent::AIO (and its IO::AIO dependency) makes it
		2051	switch to a true asynchronous implementation, so event processing
		2052	can continue even while waiting for disk I/O.
1816		2053
1817	FORK	2054	FORK
1818	Most event libraries are not fork-safe. The ones who are usually are	2055	Most event libraries are not fork-safe. The ones who are usually are
1819	because they rely on inefficient but fork-safe "select" or "poll" calls	2056	because they rely on inefficient but fork-safe "select" or "poll" calls
1820	- higher performance APIs such as BSD's kqueue or the dreaded Linux	2057	- higher performance APIs such as BSD's kqueue or the dreaded Linux
…		…
1828	usually happens when the first AnyEvent watcher is created, or the	2065	usually happens when the first AnyEvent watcher is created, or the
1829	library is loaded).	2066	library is loaded).
1830		2067
1831	If you have to fork, you must either do so before creating your first	2068	If you have to fork, you must either do so before creating your first
1832	watcher OR you must not use AnyEvent at all in the child OR you must do	2069	watcher OR you must not use AnyEvent at all in the child OR you must do
1833	something completely out of the scope of AnyEvent.	2070	something completely out of the scope of AnyEvent (see below).
1834		2071
1835	The problem of doing event processing in the parent and the child is	2072	The problem of doing event processing in the parent and the child is
1836	much more complicated: even for backends that are fork-aware or	2073	much more complicated: even for backends that are fork-aware or
1837	fork-safe, their behaviour is not usually what you want: fork clones all	2074	fork-safe, their behaviour is not usually what you want: fork clones all
1838	watchers, that means all timers, I/O watchers etc. are active in both	2075	watchers, that means all timers, I/O watchers etc. are active in both
1839	parent and child, which is almost never what you want. USing "exec" to	2076	parent and child, which is almost never what you want. Using "exec" to
1840	start worker children from some kind of manage rprocess is usually	2077	start worker children from some kind of manage prrocess is usually
1841	preferred, because it is much easier and cleaner, at the expense of	2078	preferred, because it is much easier and cleaner, at the expense of
1842	having to have another binary.	2079	having to have another binary.
		2080
		2081	In addition to logical problems with fork, there are also implementation
		2082	problems. For example, on POSIX systems, you cannot fork at all in Perl
		2083	code if a thread (I am talking of pthreads here) was ever created in the
		2084	process, and this is just the tip of the iceberg. In general, using fork
		2085	from Perl is difficult, and attempting to use fork without an exec to
		2086	implement some kind of parallel processing is almost certainly doomed.
		2087
		2088	To safely fork and exec, you should use a module such as Proc::FastSpawn
		2089	that let's you safely fork and exec new processes.
		2090
		2091	If you want to do multiprocessing using processes, you can look at the
		2092	AnyEvent::Fork module (and some related modules such as
		2093	AnyEvent::Fork::RPC, AnyEvent::Fork::Pool and AnyEvent::Fork::Remote).
		2094	This module allows you to safely create subprocesses without any
		2095	limitations - you can use X11 toolkits or AnyEvent in the children
		2096	created by AnyEvent::Fork safely and without any special precautions.
1843		2097
1844	SECURITY CONSIDERATIONS	2098	SECURITY CONSIDERATIONS
1845	AnyEvent can be forced to load any event model via	2099	AnyEvent can be forced to load any event model via
1846	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used	2100	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used
1847	to execute arbitrary code or directly gain access, it can easily be used	2101	to execute arbitrary code or directly gain access, it can easily be used
…		…
1871	5.10 and check wether the leaks still show up. (Perl 5.10.0 has other	2125	5.10 and check wether the leaks still show up. (Perl 5.10.0 has other
1872	annoying memleaks, such as leaking on "map" and "grep" but it is usually	2126	annoying memleaks, such as leaking on "map" and "grep" but it is usually
1873	not as pronounced).	2127	not as pronounced).
1874		2128
1875	SEE ALSO	2129	SEE ALSO
1876	Utility functions: AnyEvent::Util.	2130	Tutorial/Introduction: AnyEvent::Intro.
1877		2131
1878	Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,	2132	FAQ: AnyEvent::FAQ.
1879	Event::Lib, Qt, POE.	2133
		2134	Utility functions: AnyEvent::Util (misc. grab-bag), AnyEvent::Log
		2135	(simply logging).
		2136
		2137	Development/Debugging: AnyEvent::Strict (stricter checking),
		2138	AnyEvent::Debug (interactive shell, watcher tracing).
		2139
		2140	Supported event modules: AnyEvent::Loop, EV, EV::Glib, Glib::EV, Event,
		2141	Glib::Event, Glib, Tk, Event::Lib, Qt, POE, FLTK, Cocoa::EventLoop, UV.
1880		2142
1881	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,	2143	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,
1882	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,	2144	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,
1883	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,	2145	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,
		2146	AnyEvent::Impl::IOAsync, AnyEvent::Impl::Irssi, AnyEvent::Impl::FLTK,
1884	AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi.	2147	AnyEvent::Impl::Cocoa, AnyEvent::Impl::UV.
1885		2148
1886	Non-blocking file handles, sockets, TCP clients and servers:	2149	Non-blocking handles, pipes, stream sockets, TCP clients and servers:
1887	AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.	2150	AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.
1888		2151
		2152	Asynchronous File I/O: AnyEvent::IO.
		2153
1889	Asynchronous DNS: AnyEvent::DNS.	2154	Asynchronous DNS: AnyEvent::DNS.
1890		2155
1891	Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event,	2156	Thread support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event.
1892		2157
1893	Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP,	2158	Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::IRC,
1894	AnyEvent::HTTP.	2159	AnyEvent::HTTP.
1895		2160
1896	AUTHOR	2161	AUTHOR
1897	Marc Lehmann <schmorp@schmorp.de>	2162	Marc Lehmann <schmorp@schmorp.de>
1898	http://home.schmorp.de/	2163	http://anyevent.schmorp.de
1899		2164

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Revision 1.79 by root, Tue Feb 26 02:08:34 2019 UTC