[ViewVC] Diff of: cvs/AnyEvent/README

Comparing AnyEvent/README (file contents):
Revision 1.46 by root, Sat Jul 18 05:19:09 2009 UTC vs.
Revision 1.64 by root, Fri Dec 31 04:50:44 2010 UTC

…		…
1	NAME	1	NAME
2	AnyEvent - provide framework for multiple event loops	2	AnyEvent - the DBI of event loop programming
3		3
4	EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported	4	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async,
5	event loops.	5	Qt and POE are various supported event loops/environments.
6		6
7	SYNOPSIS	7	SYNOPSIS
8	use AnyEvent;	8	use AnyEvent;
9		9
		10	# if you prefer function calls, look at the AE manpage for
		11	# an alternative API.
		12
10	# file descriptor readable	13	# file handle or descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });	14	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
12		15
13	# one-shot or repeating timers	16	# one-shot or repeating timers
14	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });	17	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
15	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...	18	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...);
16		19
17	print AnyEvent->now; # prints current event loop time	20	print AnyEvent->now; # prints current event loop time
18	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.	21	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
19		22
20	# POSIX signal	23	# POSIX signal
37		40
38	INTRODUCTION/TUTORIAL	41	INTRODUCTION/TUTORIAL
39	This manpage is mainly a reference manual. If you are interested in a	42	This manpage is mainly a reference manual. If you are interested in a
40	tutorial or some gentle introduction, have a look at the AnyEvent::Intro	43	tutorial or some gentle introduction, have a look at the AnyEvent::Intro
41	manpage.	44	manpage.
		45
		46	SUPPORT
		47	An FAQ document is available as AnyEvent::FAQ.
		48
		49	There also is a mailinglist for discussing all things AnyEvent, and an
		50	IRC channel, too.
		51
		52	See the AnyEvent project page at the Schmorpforge Ta-Sa Software
		53	Repository, at <http://anyevent.schmorp.de>, for more info.
42		54
43	WHY YOU SHOULD USE THIS MODULE (OR NOT)	55	WHY YOU SHOULD USE THIS MODULE (OR NOT)
44	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	56	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
45	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
46		58
…		…
61	module users into the same thing by forcing them to use the same event	73	module users into the same thing by forcing them to use the same event
62	model you use.	74	model you use.
63		75
64	For modules like POE or IO::Async (which is a total misnomer as it is	76	For modules like POE or IO::Async (which is a total misnomer as it is
65	actually doing all I/O synchronously...), using them in your module is	77	actually doing all I/O synchronously...), using them in your module is
66	like joining a cult: After you joined, you are dependent on them and you	78	like joining a cult: After you join, you are dependent on them and you
67	cannot use anything else, as they are simply incompatible to everything	79	cannot use anything else, as they are simply incompatible to everything
68	that isn't them. What's worse, all the potential users of your module	80	that isn't them. What's worse, all the potential users of your module
69	are also forced to use the same event loop you use.	81	are also forced to use the same event loop you use.
70		82
71	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	83	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
72	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	84	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
73	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if your	85	with the rest: POE + EV? No go. Tk + Event? No go. Again: if your module
74	module uses one of those, every user of your module has to use it, too.	86	uses one of those, every user of your module has to use it, too. But if
75	But if your module uses AnyEvent, it works transparently with all event	87	your module uses AnyEvent, it works transparently with all event models
76	models it supports (including stuff like IO::Async, as long as those use	88	it supports (including stuff like IO::Async, as long as those use one of
77	one of the supported event loops. It is trivial to add new event loops	89	the supported event loops. It is easy to add new event loops to
78	to AnyEvent, too, so it is future-proof).	90	AnyEvent, too, so it is future-proof).
79		91
80	In addition to being free of having to use *the one and only true event	92	In addition to being free of having to use *the one and only true event
81	model*, AnyEvent also is free of bloat and policy: with POE or similar	93	model*, AnyEvent also is free of bloat and policy: with POE or similar
82	modules, you get an enormous amount of code and strict rules you have to	94	modules, you get an enormous amount of code and strict rules you have to
83	follow. AnyEvent, on the other hand, is lean and up to the point, by	95	follow. AnyEvent, on the other hand, is lean and to the point, by only
84	only offering the functionality that is necessary, in as thin as a	96	offering the functionality that is necessary, in as thin as a wrapper as
85	wrapper as technically possible.	97	technically possible.
86		98
87	Of course, AnyEvent comes with a big (and fully optional!) toolbox of	99	Of course, AnyEvent comes with a big (and fully optional!) toolbox of
88	useful functionality, such as an asynchronous DNS resolver, 100%	100	useful functionality, such as an asynchronous DNS resolver, 100%
89	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms	101	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
90	such as Windows) and lots of real-world knowledge and workarounds for	102	such as Windows) and lots of real-world knowledge and workarounds for
…		…
93	Now, if you do want lots of policy (this can arguably be somewhat	105	Now, if you do want lots of policy (this can arguably be somewhat
94	useful) and you want to force your users to use the one and only event	106	useful) and you want to force your users to use the one and only event
95	model, you should not use this module.	107	model, you should not use this module.
96		108
97	DESCRIPTION	109	DESCRIPTION
98	AnyEvent provides an identical interface to multiple event loops. This	110	AnyEvent provides a uniform interface to various event loops. This
99	allows module authors to utilise an event loop without forcing module	111	allows module authors to use event loop functionality without forcing
100	users to use the same event loop (as only a single event loop can	112	module users to use a specific event loop implementation (since more
101	coexist peacefully at any one time).	113	than one event loop cannot coexist peacefully).
102		114
103	The interface itself is vaguely similar, but not identical to the Event	115	The interface itself is vaguely similar, but not identical to the Event
104	module.	116	module.
105		117
106	During the first call of any watcher-creation method, the module tries	118	During the first call of any watcher-creation method, the module tries
107	to detect the currently loaded event loop by probing whether one of the	119	to detect the currently loaded event loop by probing whether one of the
108	following modules is already loaded: EV, Event, Glib,	120	following modules is already loaded: EV, AnyEvent::Impl::Perl, Event,
109	AnyEvent::Impl::Perl, Tk, Event::Lib, Qt, POE. The first one found is	121	Glib, Tk, Event::Lib, Qt, POE. The first one found is used. If none are
110	used. If none are found, the module tries to load these modules	122	detected, the module tries to load the first four modules in the order
111	(excluding Tk, Event::Lib, Qt and POE as the pure perl adaptor should	123	given; but note that if EV is not available, the pure-perl
112	always succeed) in the order given. The first one that can be	124	AnyEvent::Impl::Perl should always work, so the other two are not
113	successfully loaded will be used. If, after this, still none could be	125	normally tried.
114	found, AnyEvent will fall back to a pure-perl event loop, which is not
115	very efficient, but should work everywhere.
116		126
117	Because AnyEvent first checks for modules that are already loaded,	127	Because AnyEvent first checks for modules that are already loaded,
118	loading an event model explicitly before first using AnyEvent will	128	loading an event model explicitly before first using AnyEvent will
119	likely make that model the default. For example:	129	likely make that model the default. For example:
120		130
…		…
122	use AnyEvent;	132	use AnyEvent;
123		133
124	# .. AnyEvent will likely default to Tk	134	# .. AnyEvent will likely default to Tk
125		135
126	The likely means that, if any module loads another event model and	136	The likely means that, if any module loads another event model and
127	starts using it, all bets are off. Maybe you should tell their authors	137	starts using it, all bets are off - this case should be very rare
128	to use AnyEvent so their modules work together with others seamlessly...	138	though, as very few modules hardcode event loops without announcing this
		139	very loudly.
129		140
130	The pure-perl implementation of AnyEvent is called	141	The pure-perl implementation of AnyEvent is called
131	"AnyEvent::Impl::Perl". Like other event modules you can load it	142	"AnyEvent::Impl::Perl". Like other event modules you can load it
132	explicitly and enjoy the high availability of that event loop :)	143	explicitly and enjoy the high availability of that event loop :)
133		144
…		…
141	callback when the event occurs (of course, only when the event model is	152	callback when the event occurs (of course, only when the event model is
142	in control).	153	in control).
143		154
144	Note that callbacks must not permanently change global variables	155	Note that callbacks must not permanently change global variables
145	potentially in use by the event loop (such as $_ or $[) and that	156	potentially in use by the event loop (such as $_ or $[) and that
146	callbacks must not "die". The former is good programming practise in	157	callbacks must not "die". The former is good programming practice in
147	Perl and the latter stems from the fact that exception handling differs	158	Perl and the latter stems from the fact that exception handling differs
148	widely between event loops.	159	widely between event loops.
149		160
150	To disable the watcher you have to destroy it (e.g. by setting the	161	To disable a watcher you have to destroy it (e.g. by setting the
151	variable you store it in to "undef" or otherwise deleting all references	162	variable you store it in to "undef" or otherwise deleting all references
152	to it).	163	to it).
153		164
154	All watchers are created by calling a method on the "AnyEvent" class.	165	All watchers are created by calling a method on the "AnyEvent" class.
155		166
156	Many watchers either are used with "recursion" (repeating timers for	167	Many watchers either are used with "recursion" (repeating timers for
157	example), or need to refer to their watcher object in other ways.	168	example), or need to refer to their watcher object in other ways.
158		169
159	An any way to achieve that is this pattern:	170	One way to achieve that is this pattern:
160		171
161	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	172	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
162	# you can use $w here, for example to undef it	173	# you can use $w here, for example to undef it
163	undef $w;	174	undef $w;
164	});	175	});
…		…
166	Note that "my $w; $w =" combination. This is necessary because in Perl,	177	Note that "my $w; $w =" combination. This is necessary because in Perl,
167	my variables are only visible after the statement in which they are	178	my variables are only visible after the statement in which they are
168	declared.	179	declared.
169		180
170	I/O WATCHERS	181	I/O WATCHERS
		182	$w = AnyEvent->io (
		183	fh => <filehandle_or_fileno>,
		184	poll => <"r" or "w">,
		185	cb => <callback>,
		186	);
		187
171	You can create an I/O watcher by calling the "AnyEvent->io" method with	188	You can create an I/O watcher by calling the "AnyEvent->io" method with
172	the following mandatory key-value pairs as arguments:	189	the following mandatory key-value pairs as arguments:
173		190
174	"fh" is the Perl file handle (or a naked file descriptor) to watch for	191	"fh" is the Perl file handle (or a naked file descriptor) to watch for
175	events (AnyEvent might or might not keep a reference to this file	192	events (AnyEvent might or might not keep a reference to this file
…		…
189		206
190	The I/O watcher might use the underlying file descriptor or a copy of	207	The I/O watcher might use the underlying file descriptor or a copy of
191	it. You must not close a file handle as long as any watcher is active on	208	it. You must not close a file handle as long as any watcher is active on
192	the underlying file descriptor.	209	the underlying file descriptor.
193		210
194	Some event loops issue spurious readyness notifications, so you should	211	Some event loops issue spurious readiness notifications, so you should
195	always use non-blocking calls when reading/writing from/to your file	212	always use non-blocking calls when reading/writing from/to your file
196	handles.	213	handles.
197		214
198	Example: wait for readability of STDIN, then read a line and disable the	215	Example: wait for readability of STDIN, then read a line and disable the
199	watcher.	216	watcher.
…		…
203	warn "read: $input\n";	220	warn "read: $input\n";
204	undef $w;	221	undef $w;
205	});	222	});
206		223
207	TIME WATCHERS	224	TIME WATCHERS
		225	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		226
		227	$w = AnyEvent->timer (
		228	after => <fractional_seconds>,
		229	interval => <fractional_seconds>,
		230	cb => <callback>,
		231	);
		232
208	You can create a time watcher by calling the "AnyEvent->timer" method	233	You can create a time watcher by calling the "AnyEvent->timer" method
209	with the following mandatory arguments:	234	with the following mandatory arguments:
210		235
211	"after" specifies after how many seconds (fractional values are	236	"after" specifies after how many seconds (fractional values are
212	supported) the callback should be invoked. "cb" is the callback to	237	supported) the callback should be invoked. "cb" is the callback to
…		…
214		239
215	Although the callback might get passed parameters, their value and	240	Although the callback might get passed parameters, their value and
216	presence is undefined and you cannot rely on them. Portable AnyEvent	241	presence is undefined and you cannot rely on them. Portable AnyEvent
217	callbacks cannot use arguments passed to time watcher callbacks.	242	callbacks cannot use arguments passed to time watcher callbacks.
218		243
219	The callback will normally be invoked once only. If you specify another	244	The callback will normally be invoked only once. If you specify another
220	parameter, "interval", as a strictly positive number (> 0), then the	245	parameter, "interval", as a strictly positive number (> 0), then the
221	callback will be invoked regularly at that interval (in fractional	246	callback will be invoked regularly at that interval (in fractional
222	seconds) after the first invocation. If "interval" is specified with a	247	seconds) after the first invocation. If "interval" is specified with a
223	false value, then it is treated as if it were missing.	248	false value, then it is treated as if it were not specified at all.
224		249
225	The callback will be rescheduled before invoking the callback, but no	250	The callback will be rescheduled before invoking the callback, but no
226	attempt is done to avoid timer drift in most backends, so the interval	251	attempt is made to avoid timer drift in most backends, so the interval
227	is only approximate.	252	is only approximate.
228		253
229	Example: fire an event after 7.7 seconds.	254	Example: fire an event after 7.7 seconds.
230		255
231	my $w = AnyEvent->timer (after => 7.7, cb => sub {	256	my $w = AnyEvent->timer (after => 7.7, cb => sub {
…		…
248		273
249	While most event loops expect timers to specified in a relative way,	274	While most event loops expect timers to specified in a relative way,
250	they use absolute time internally. This makes a difference when your	275	they use absolute time internally. This makes a difference when your
251	clock "jumps", for example, when ntp decides to set your clock backwards	276	clock "jumps", for example, when ntp decides to set your clock backwards
252	from the wrong date of 2014-01-01 to 2008-01-01, a watcher that is	277	from the wrong date of 2014-01-01 to 2008-01-01, a watcher that is
253	supposed to fire "after" a second might actually take six years to	278	supposed to fire "after a second" might actually take six years to
254	finally fire.	279	finally fire.
255		280
256	AnyEvent cannot compensate for this. The only event loop that is	281	AnyEvent cannot compensate for this. The only event loop that is
257	conscious about these issues is EV, which offers both relative	282	conscious of these issues is EV, which offers both relative (ev_timer,
258	(ev_timer, based on true relative time) and absolute (ev_periodic, based	283	based on true relative time) and absolute (ev_periodic, based on
259	on wallclock time) timers.	284	wallclock time) timers.
260		285
261	AnyEvent always prefers relative timers, if available, matching the	286	AnyEvent always prefers relative timers, if available, matching the
262	AnyEvent API.	287	AnyEvent API.
263		288
264	AnyEvent has two additional methods that return the "current time":	289	AnyEvent has two additional methods that return the "current time":
…		…
283	*In almost all cases (in all cases if you don't care), this is the	308	*In almost all cases (in all cases if you don't care), this is the
284	function to call when you want to know the current time.*	309	function to call when you want to know the current time.*
285		310
286	This function is also often faster then "AnyEvent->time", and thus	311	This function is also often faster then "AnyEvent->time", and thus
287	the preferred method if you want some timestamp (for example,	312	the preferred method if you want some timestamp (for example,
288	AnyEvent::Handle uses this to update it's activity timeouts).	313	AnyEvent::Handle uses this to update its activity timeouts).
289		314
290	The rest of this section is only of relevance if you try to be very	315	The rest of this section is only of relevance if you try to be very
291	exact with your timing, you can skip it without bad conscience.	316	exact with your timing; you can skip it without a bad conscience.
292		317
293	For a practical example of when these times differ, consider	318	For a practical example of when these times differ, consider
294	Event::Lib and EV and the following set-up:	319	Event::Lib and EV and the following set-up:
295		320
296	The event loop is running and has just invoked one of your callback	321	The event loop is running and has just invoked one of your callbacks
297	at time=500 (assume no other callbacks delay processing). In your	322	at time=500 (assume no other callbacks delay processing). In your
298	callback, you wait a second by executing "sleep 1" (blocking the	323	callback, you wait a second by executing "sleep 1" (blocking the
299	process for a second) and then (at time=501) you create a relative	324	process for a second) and then (at time=501) you create a relative
300	timer that fires after three seconds.	325	timer that fires after three seconds.
301		326
…		…
333	time, which might affect timers and time-outs.	358	time, which might affect timers and time-outs.
334		359
335	When this is the case, you can call this method, which will update	360	When this is the case, you can call this method, which will update
336	the event loop's idea of "current time".	361	the event loop's idea of "current time".
337		362
		363	A typical example would be a script in a web server (e.g.
		364	"mod_perl") - when mod_perl executes the script, then the event loop
		365	will have the wrong idea about the "current time" (being potentially
		366	far in the past, when the script ran the last time). In that case
		367	you should arrange a call to "AnyEvent->now_update" each time the
		368	web server process wakes up again (e.g. at the start of your script,
		369	or in a handler).
		370
338	Note that updating the time might cause some events to be handled.	371	Note that updating the time might cause some events to be handled.
339		372
340	SIGNAL WATCHERS	373	SIGNAL WATCHERS
		374	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		375
341	You can watch for signals using a signal watcher, "signal" is the signal	376	You can watch for signals using a signal watcher, "signal" is the signal
342	name in uppercase and without any "SIG" prefix, "cb" is the Perl	377	name in uppercase and without any "SIG" prefix, "cb" is the Perl
343	callback to be invoked whenever a signal occurs.	378	callback to be invoked whenever a signal occurs.
344		379
345	Although the callback might get passed parameters, their value and	380	Although the callback might get passed parameters, their value and
…		…
357		392
358	This watcher might use %SIG (depending on the event loop used), so	393	This watcher might use %SIG (depending on the event loop used), so
359	programs overwriting those signals directly will likely not work	394	programs overwriting those signals directly will likely not work
360	correctly.	395	correctly.
361		396
		397	Example: exit on SIGINT
		398
		399	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
		400
		401	Restart Behaviour
		402	While restart behaviour is up to the event loop implementation, most
		403	will not restart syscalls (that includes Async::Interrupt and AnyEvent's
		404	pure perl implementation).
		405
		406	Safe/Unsafe Signals
		407	Perl signals can be either "safe" (synchronous to opcode handling) or
		408	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		409	latter might corrupt your memory.
		410
		411	AnyEvent signal handlers are, in addition, synchronous to the event
		412	loop, i.e. they will not interrupt your running perl program but will
		413	only be called as part of the normal event handling (just like timer,
		414	I/O etc. callbacks, too).
		415
		416	Signal Races, Delays and Workarounds
362	Also note that many event loops (e.g. Glib, Tk, Qt, IO::Async) do not	417	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
363	support attaching callbacks to signals, which is a pity, as you cannot	418	callbacks to signals in a generic way, which is a pity, as you cannot do
364	do race-free signal handling in perl. AnyEvent will try to do it's best,	419	race-free signal handling in perl, requiring C libraries for this.
365	but in some cases, signals will be delayed. The maximum time a signal	420	AnyEvent will try to do its best, which means in some cases, signals
366	might be delayed is specified in $AnyEvent::MAX_SIGNAL_LATENCY (default:	421	will be delayed. The maximum time a signal might be delayed is specified
367	10 seconds). This variable can be changed only before the first signal	422	in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable
368	watcher is created, and should be left alone otherwise. Higher values	423	can be changed only before the first signal watcher is created, and
		424	should be left alone otherwise. This variable determines how often
		425	AnyEvent polls for signals (in case a wake-up was missed). Higher values
369	will cause fewer spurious wake-ups, which is better for power and CPU	426	will cause fewer spurious wake-ups, which is better for power and CPU
		427	saving.
		428
370	saving. All these problems can be avoided by installing the optional	429	All these problems can be avoided by installing the optional
371	Async::Interrupt module.	430	Async::Interrupt module, which works with most event loops. It will not
372		431	work with inherently broken event loops such as Event or Event::Lib (and
373	Example: exit on SIGINT	432	not with POE currently, as POE does its own workaround with one-second
374		433	latency). For those, you just have to suffer the delays.
375	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
376		434
377	CHILD PROCESS WATCHERS	435	CHILD PROCESS WATCHERS
		436	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		437
378	You can also watch on a child process exit and catch its exit status.	438	You can also watch for a child process exit and catch its exit status.
379		439
380	The child process is specified by the "pid" argument (if set to 0, it	440	The child process is specified by the "pid" argument (on some backends,
381	watches for any child process exit). The watcher will triggered only	441	using 0 watches for any child process exit, on others this will croak).
382	when the child process has finished and an exit status is available, not	442	The watcher will be triggered only when the child process has finished
383	on any trace events (stopped/continued).	443	and an exit status is available, not on any trace events
		444	(stopped/continued).
384		445
385	The callback will be called with the pid and exit status (as returned by	446	The callback will be called with the pid and exit status (as returned by
386	waitpid), so unlike other watcher types, you can rely on child watcher	447	waitpid), so unlike other watcher types, you can rely on child watcher
387	callback arguments.	448	callback arguments.
388		449
…		…
427		488
428	# do something else, then wait for process exit	489	# do something else, then wait for process exit
429	$done->recv;	490	$done->recv;
430		491
431	IDLE WATCHERS	492	IDLE WATCHERS
432	Sometimes there is a need to do something, but it is not so important to	493	$w = AnyEvent->idle (cb => <callback>);
433	do it instantly, but only when there is nothing better to do. This
434	"nothing better to do" is usually defined to be "no other events need
435	attention by the event loop".
436		494
437	Idle watchers ideally get invoked when the event loop has nothing better	495	This will repeatedly invoke the callback after the process becomes idle,
438	to do, just before it would block the process to wait for new events.	496	until either the watcher is destroyed or new events have been detected.
439	Instead of blocking, the idle watcher is invoked.
440		497
441	Most event loops unfortunately do not really support idle watchers (only	498	Idle watchers are useful when there is a need to do something, but it is
		499	not so important (or wise) to do it instantly. The callback will be
		500	invoked only when there is "nothing better to do", which is usually
		501	defined as "all outstanding events have been handled and no new events
		502	have been detected". That means that idle watchers ideally get invoked
		503	when the event loop has just polled for new events but none have been
		504	detected. Instead of blocking to wait for more events, the idle watchers
		505	will be invoked.
		506
		507	Unfortunately, most event loops do not really support idle watchers
442	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent	508	(only EV, Event and Glib do it in a usable fashion) - for the rest,
443	will simply call the callback "from time to time".	509	AnyEvent will simply call the callback "from time to time".
444		510
445	Example: read lines from STDIN, but only process them when the program	511	Example: read lines from STDIN, but only process them when the program
446	is otherwise idle:	512	is otherwise idle:
447		513
448	my @lines; # read data	514	my @lines; # read data
…		…
461	}	527	}
462	});	528	});
463	});	529	});
464		530
465	CONDITION VARIABLES	531	CONDITION VARIABLES
		532	$cv = AnyEvent->condvar;
		533
		534	$cv->send (<list>);
		535	my @res = $cv->recv;
		536
466	If you are familiar with some event loops you will know that all of them	537	If you are familiar with some event loops you will know that all of them
467	require you to run some blocking "loop", "run" or similar function that	538	require you to run some blocking "loop", "run" or similar function that
468	will actively watch for new events and call your callbacks.	539	will actively watch for new events and call your callbacks.
469		540
470	AnyEvent is slightly different: it expects somebody else to run the	541	AnyEvent is slightly different: it expects somebody else to run the
471	event loop and will only block when necessary (usually when told by the	542	event loop and will only block when necessary (usually when told by the
472	user).	543	user).
473		544
474	The instrument to do that is called a "condition variable", so called	545	The tool to do that is called a "condition variable", so called because
475	because they represent a condition that must become true.	546	they represent a condition that must become true.
476		547
477	Now is probably a good time to look at the examples further below.	548	Now is probably a good time to look at the examples further below.
478		549
479	Condition variables can be created by calling the "AnyEvent->condvar"	550	Condition variables can be created by calling the "AnyEvent->condvar"
480	method, usually without arguments. The only argument pair allowed is	551	method, usually without arguments. The only argument pair allowed is
…		…
485	After creation, the condition variable is "false" until it becomes	556	After creation, the condition variable is "false" until it becomes
486	"true" by calling the "send" method (or calling the condition variable	557	"true" by calling the "send" method (or calling the condition variable
487	as if it were a callback, read about the caveats in the description for	558	as if it were a callback, read about the caveats in the description for
488	the "->send" method).	559	the "->send" method).
489		560
490	Condition variables are similar to callbacks, except that you can	561	Since condition variables are the most complex part of the AnyEvent API,
491	optionally wait for them. They can also be called merge points - points	562	here are some different mental models of what they are - pick the ones
492	in time where multiple outstanding events have been processed. And yet	563	you can connect to:
493	another way to call them is transactions - each condition variable can	564
494	be used to represent a transaction, which finishes at some point and	565	* Condition variables are like callbacks - you can call them (and pass
495	delivers a result.	566	them instead of callbacks). Unlike callbacks however, you can also
		567	wait for them to be called.
		568
		569	* Condition variables are signals - one side can emit or send them,
		570	the other side can wait for them, or install a handler that is
		571	called when the signal fires.
		572
		573	* Condition variables are like "Merge Points" - points in your program
		574	where you merge multiple independent results/control flows into one.
		575
		576	* Condition variables represent a transaction - functions that start
		577	some kind of transaction can return them, leaving the caller the
		578	choice between waiting in a blocking fashion, or setting a callback.
		579
		580	* Condition variables represent future values, or promises to deliver
		581	some result, long before the result is available.
496		582
497	Condition variables are very useful to signal that something has	583	Condition variables are very useful to signal that something has
498	finished, for example, if you write a module that does asynchronous http	584	finished, for example, if you write a module that does asynchronous http
499	requests, then a condition variable would be the ideal candidate to	585	requests, then a condition variable would be the ideal candidate to
500	signal the availability of results. The user can either act when the	586	signal the availability of results. The user can either act when the
…		…
513		599
514	Condition variables are represented by hash refs in perl, and the keys	600	Condition variables are represented by hash refs in perl, and the keys
515	used by AnyEvent itself are all named "_ae_XXX" to make subclassing easy	601	used by AnyEvent itself are all named "_ae_XXX" to make subclassing easy
516	(it is often useful to build your own transaction class on top of	602	(it is often useful to build your own transaction class on top of
517	AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call	603	AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call
518	it's "new" method in your own "new" method.	604	its "new" method in your own "new" method.
519		605
520	There are two "sides" to a condition variable - the "producer side"	606	There are two "sides" to a condition variable - the "producer side"
521	which eventually calls "-> send", and the "consumer side", which waits	607	which eventually calls "-> send", and the "consumer side", which waits
522	for the send to occur.	608	for the send to occur.
523		609
524	Example: wait for a timer.	610	Example: wait for a timer.
525		611
526	# wait till the result is ready	612	# condition: "wait till the timer is fired"
527	my $result_ready = AnyEvent->condvar;	613	my $timer_fired = AnyEvent->condvar;
528		614
529	# do something such as adding a timer	615	# create the timer - we could wait for, say
530	# or socket watcher the calls $result_ready->send	616	# a handle becomign ready, or even an
531	# when the "result" is ready.	617	# AnyEvent::HTTP request to finish, but
532	# in this case, we simply use a timer:	618	# in this case, we simply use a timer:
533	my $w = AnyEvent->timer (	619	my $w = AnyEvent->timer (
534	after => 1,	620	after => 1,
535	cb => sub { $result_ready->send },	621	cb => sub { $timer_fired->send },
536	);	622	);
537		623
538	# this "blocks" (while handling events) till the callback	624	# this "blocks" (while handling events) till the callback
539	# calls -<send	625	# calls ->send
540	$result_ready->recv;	626	$timer_fired->recv;
541		627
542	Example: wait for a timer, but take advantage of the fact that condition	628	Example: wait for a timer, but take advantage of the fact that condition
543	variables are also callable directly.	629	variables are also callable directly.
544		630
545	my $done = AnyEvent->condvar;	631	my $done = AnyEvent->condvar;
…		…
583	Condition variables are overloaded so one can call them directly (as	669	Condition variables are overloaded so one can call them directly (as
584	if they were a code reference). Calling them directly is the same as	670	if they were a code reference). Calling them directly is the same as
585	calling "send".	671	calling "send".
586		672
587	$cv->croak ($error)	673	$cv->croak ($error)
588	Similar to send, but causes all call's to "->recv" to invoke	674	Similar to send, but causes all calls to "->recv" to invoke
589	"Carp::croak" with the given error message/object/scalar.	675	"Carp::croak" with the given error message/object/scalar.
590		676
591	This can be used to signal any errors to the condition variable	677	This can be used to signal any errors to the condition variable
592	user/consumer. Doing it this way instead of calling "croak" directly	678	user/consumer. Doing it this way instead of calling "croak" directly
593	delays the error detetcion, but has the overwhelmign advantage that	679	delays the error detection, but has the overwhelming advantage that
594	it diagnoses the error at the place where the result is expected,	680	it diagnoses the error at the place where the result is expected,
595	and not deep in some event clalback without connection to the actual	681	and not deep in some event callback with no connection to the actual
596	code causing the problem.	682	code causing the problem.
597		683
598	$cv->begin ([group callback])	684	$cv->begin ([group callback])
599	$cv->end	685	$cv->end
600	These two methods can be used to combine many transactions/events	686	These two methods can be used to combine many transactions/events
601	into one. For example, a function that pings many hosts in parallel	687	into one. For example, a function that pings many hosts in parallel
602	might want to use a condition variable for the whole process.	688	might want to use a condition variable for the whole process.
603		689
604	Every call to "->begin" will increment a counter, and every call to	690	Every call to "->begin" will increment a counter, and every call to
605	"->end" will decrement it. If the counter reaches 0 in "->end", the	691	"->end" will decrement it. If the counter reaches 0 in "->end", the
606	(last) callback passed to "begin" will be executed. That callback is	692	(last) callback passed to "begin" will be executed, passing the
607	supposed to call "->send", but that is not required. If no	693	condvar as first argument. That callback is supposed to call
		694	"->send", but that is not required. If no group callback was set,
608	callback was set, "send" will be called without any arguments.	695	"send" will be called without any arguments.
609		696
610	You can think of "$cv->send" giving you an OR condition (one call	697	You can think of "$cv->send" giving you an OR condition (one call
611	sends), while "$cv->begin" and "$cv->end" giving you an AND	698	sends), while "$cv->begin" and "$cv->end" giving you an AND
612	condition (all "begin" calls must be "end"'ed before the condvar	699	condition (all "begin" calls must be "end"'ed before the condvar
613	sends).	700	sends).
…		…
636	there is one call to "begin", so the condvar waits for all calls to	723	there is one call to "begin", so the condvar waits for all calls to
637	"end" before sending.	724	"end" before sending.
638		725
639	The ping example mentioned above is slightly more complicated, as	726	The ping example mentioned above is slightly more complicated, as
640	the there are results to be passwd back, and the number of tasks	727	the there are results to be passwd back, and the number of tasks
641	that are begung can potentially be zero:	728	that are begun can potentially be zero:
642		729
643	my $cv = AnyEvent->condvar;	730	my $cv = AnyEvent->condvar;
644		731
645	my %result;	732	my %result;
646	$cv->begin (sub { $cv->send (\%result) });	733	$cv->begin (sub { shift->send (\%result) });
647		734
648	for my $host (@list_of_hosts) {	735	for my $host (@list_of_hosts) {
649	$cv->begin;	736	$cv->begin;
650	ping_host_then_call_callback $host, sub {	737	ping_host_then_call_callback $host, sub {
651	$result{$host} = ...;	738	$result{$host} = ...;
…		…
667	callback to be called once the counter reaches 0, and second, it	754	callback to be called once the counter reaches 0, and second, it
668	ensures that "send" is called even when "no" hosts are being pinged	755	ensures that "send" is called even when "no" hosts are being pinged
669	(the loop doesn't execute once).	756	(the loop doesn't execute once).
670		757
671	This is the general pattern when you "fan out" into multiple (but	758	This is the general pattern when you "fan out" into multiple (but
672	potentially none) subrequests: use an outer "begin"/"end" pair to	759	potentially zero) subrequests: use an outer "begin"/"end" pair to
673	set the callback and ensure "end" is called at least once, and then,	760	set the callback and ensure "end" is called at least once, and then,
674	for each subrequest you start, call "begin" and for each subrequest	761	for each subrequest you start, call "begin" and for each subrequest
675	you finish, call "end".	762	you finish, call "end".
676		763
677	METHODS FOR CONSUMERS	764	METHODS FOR CONSUMERS
678	These methods should only be used by the consuming side, i.e. the code	765	These methods should only be used by the consuming side, i.e. the code
679	awaits the condition.	766	awaits the condition.
680		767
681	$cv->recv	768	$cv->recv
682	Wait (blocking if necessary) until the "->send" or "->croak" methods	769	Wait (blocking if necessary) until the "->send" or "->croak" methods
683	have been called on c<$cv>, while servicing other watchers normally.	770	have been called on $cv, while servicing other watchers normally.
684		771
685	You can only wait once on a condition - additional calls are valid	772	You can only wait once on a condition - additional calls are valid
686	but will return immediately.	773	but will return immediately.
687		774
688	If an error condition has been set by calling "->croak", then this	775	If an error condition has been set by calling "->croak", then this
…		…
705	example, by coupling condition variables with some kind of request	792	example, by coupling condition variables with some kind of request
706	results and supporting callbacks so the caller knows that getting	793	results and supporting callbacks so the caller knows that getting
707	the result will not block, while still supporting blocking waits if	794	the result will not block, while still supporting blocking waits if
708	the caller so desires).	795	the caller so desires).
709		796
710	You can ensure that "-recv" never blocks by setting a callback and	797	You can ensure that "->recv" never blocks by setting a callback and
711	only calling "->recv" from within that callback (or at a later	798	only calling "->recv" from within that callback (or at a later
712	time). This will work even when the event loop does not support	799	time). This will work even when the event loop does not support
713	blocking waits otherwise.	800	blocking waits otherwise.
714		801
715	$bool = $cv->ready	802	$bool = $cv->ready
…		…
720	This is a mutator function that returns the callback set and	807	This is a mutator function that returns the callback set and
721	optionally replaces it before doing so.	808	optionally replaces it before doing so.
722		809
723	The callback will be called when the condition becomes "true", i.e.	810	The callback will be called when the condition becomes "true", i.e.
724	when "send" or "croak" are called, with the only argument being the	811	when "send" or "croak" are called, with the only argument being the
725	condition variable itself. Calling "recv" inside the callback or at	812	condition variable itself. If the condition is already true, the
		813	callback is called immediately when it is set. Calling "recv" inside
726	any later time is guaranteed not to block.	814	the callback or at any later time is guaranteed not to block.
727		815
728	SUPPORTED EVENT LOOPS/BACKENDS	816	SUPPORTED EVENT LOOPS/BACKENDS
729	The available backend classes are (every class has its own manpage):	817	The available backend classes are (every class has its own manpage):
730		818
731	Backends that are autoprobed when no other event loop can be found.	819	Backends that are autoprobed when no other event loop can be found.
732	EV is the preferred backend when no other event loop seems to be in	820	EV is the preferred backend when no other event loop seems to be in
733	use. If EV is not installed, then AnyEvent will try Event, and,	821	use. If EV is not installed, then AnyEvent will fall back to its own
734	failing that, will fall back to its own pure-perl implementation,	822	pure-perl implementation, which is available everywhere as it comes
735	which is available everywhere as it comes with AnyEvent itself.	823	with AnyEvent itself.
736		824
737	AnyEvent::Impl::EV based on EV (interface to libev, best choice).	825	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
738	AnyEvent::Impl::Event based on Event, very stable, few glitches.
739	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.	826	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
740		827
741	Backends that are transparently being picked up when they are used.	828	Backends that are transparently being picked up when they are used.
742	These will be used when they are currently loaded when the first	829	These will be used if they are already loaded when the first watcher
743	watcher is created, in which case it is assumed that the application	830	is created, in which case it is assumed that the application is
744	is using them. This means that AnyEvent will automatically pick the	831	using them. This means that AnyEvent will automatically pick the
745	right backend when the main program loads an event module before	832	right backend when the main program loads an event module before
746	anything starts to create watchers. Nothing special needs to be done	833	anything starts to create watchers. Nothing special needs to be done
747	by the main program.	834	by the main program.
748		835
		836	AnyEvent::Impl::Event based on Event, very stable, few glitches.
749	AnyEvent::Impl::Glib based on Glib, slow but very stable.	837	AnyEvent::Impl::Glib based on Glib, slow but very stable.
750	AnyEvent::Impl::Tk based on Tk, very broken.	838	AnyEvent::Impl::Tk based on Tk, very broken.
751	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	839	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
752	AnyEvent::Impl::POE based on POE, very slow, some limitations.	840	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		841	AnyEvent::Impl::Irssi used when running within irssi.
		842	AnyEvent::Impl::IOAsync based on IO::Async.
		843	AnyEvent::Impl::Cocoa based on Cocoa::EventLoop.
753		844
754	Backends with special needs.	845	Backends with special needs.
755	Qt requires the Qt::Application to be instantiated first, but will	846	Qt requires the Qt::Application to be instantiated first, but will
756	otherwise be picked up automatically. As long as the main program	847	otherwise be picked up automatically. As long as the main program
757	instantiates the application before any AnyEvent watchers are	848	instantiates the application before any AnyEvent watchers are
758	created, everything should just work.	849	created, everything should just work.
759		850
760	AnyEvent::Impl::Qt based on Qt.	851	AnyEvent::Impl::Qt based on Qt.
761		852
762	Support for IO::Async can only be partial, as it is too broken and
763	architecturally limited to even support the AnyEvent API. It also is
764	the only event loop that needs the loop to be set explicitly, so it
765	can only be used by a main program knowing about AnyEvent. See
766	AnyEvent::Impl::Async for the gory details.
767
768	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
769
770	Event loops that are indirectly supported via other backends.	853	Event loops that are indirectly supported via other backends.
771	Some event loops can be supported via other modules:	854	Some event loops can be supported via other modules:
772		855
773	There is no direct support for WxWidgets (Wx) or Prima.	856	There is no direct support for WxWidgets (Wx) or Prima.
774		857
…		…
792	Contains "undef" until the first watcher is being created, before	875	Contains "undef" until the first watcher is being created, before
793	the backend has been autodetected.	876	the backend has been autodetected.
794		877
795	Afterwards it contains the event model that is being used, which is	878	Afterwards it contains the event model that is being used, which is
796	the name of the Perl class implementing the model. This class is	879	the name of the Perl class implementing the model. This class is
797	usually one of the "AnyEvent::Impl:xxx" modules, but can be any	880	usually one of the "AnyEvent::Impl::xxx" modules, but can be any
798	other class in the case AnyEvent has been extended at runtime (e.g.	881	other class in the case AnyEvent has been extended at runtime (e.g.
799	in rxvt-unicode it will be "urxvt::anyevent").	882	in rxvt-unicode it will be "urxvt::anyevent").
800		883
801	AnyEvent::detect	884	AnyEvent::detect
802	Returns $AnyEvent::MODEL, forcing autodetection of the event model	885	Returns $AnyEvent::MODEL, forcing autodetection of the event model
803	if necessary. You should only call this function right before you	886	if necessary. You should only call this function right before you
804	would have created an AnyEvent watcher anyway, that is, as late as	887	would have created an AnyEvent watcher anyway, that is, as late as
805	possible at runtime, and not e.g. while initialising of your module.	888	possible at runtime, and not e.g. during initialisation of your
		889	module.
806		890
807	If you need to do some initialisation before AnyEvent watchers are	891	If you need to do some initialisation before AnyEvent watchers are
808	created, use "post_detect".	892	created, use "post_detect".
809		893
810	$guard = AnyEvent::post_detect { BLOCK }	894	$guard = AnyEvent::post_detect { BLOCK }
811	Arranges for the code block to be executed as soon as the event	895	Arranges for the code block to be executed as soon as the event
812	model is autodetected (or immediately if this has already happened).	896	model is autodetected (or immediately if that has already happened).
813		897
814	The block will be executed after the actual backend has been	898	The block will be executed after the actual backend has been
815	detected ($AnyEvent::MODEL is set), but before any watchers have	899	detected ($AnyEvent::MODEL is set), but before any watchers have
816	been created, so it is possible to e.g. patch @AnyEvent::ISA or do	900	been created, so it is possible to e.g. patch @AnyEvent::ISA or do
817	other initialisations - see the sources of AnyEvent::Strict or	901	other initialisations - see the sources of AnyEvent::Strict or
…		…
822	creates and installs the global IO::AIO watcher in a "post_detect"	906	creates and installs the global IO::AIO watcher in a "post_detect"
823	block to avoid autodetecting the event module at load time.	907	block to avoid autodetecting the event module at load time.
824		908
825	If called in scalar or list context, then it creates and returns an	909	If called in scalar or list context, then it creates and returns an
826	object that automatically removes the callback again when it is	910	object that automatically removes the callback again when it is
		911	destroyed (or "undef" when the hook was immediately executed). See
827	destroyed. See Coro::BDB for a case where this is useful.	912	AnyEvent::AIO for a case where this is useful.
		913
		914	Example: Create a watcher for the IO::AIO module and store it in
		915	$WATCHER, but do so only do so after the event loop is initialised.
		916
		917	our WATCHER;
		918
		919	my $guard = AnyEvent::post_detect {
		920	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		921	};
		922
		923	# the \|\|= is important in case post_detect immediately runs the block,
		924	# as to not clobber the newly-created watcher. assigning both watcher and
		925	# post_detect guard to the same variable has the advantage of users being
		926	# able to just C<undef $WATCHER> if the watcher causes them grief.
		927
		928	$WATCHER \|\|= $guard;
828		929
829	@AnyEvent::post_detect	930	@AnyEvent::post_detect
830	If there are any code references in this array (you can "push" to it	931	If there are any code references in this array (you can "push" to it
831	before or after loading AnyEvent), then they will called directly	932	before or after loading AnyEvent), then they will be called directly
832	after the event loop has been chosen.	933	after the event loop has been chosen.
833		934
834	You should check $AnyEvent::MODEL before adding to this array,	935	You should check $AnyEvent::MODEL before adding to this array,
835	though: if it is defined then the event loop has already been	936	though: if it is defined then the event loop has already been
836	detected, and the array will be ignored.	937	detected, and the array will be ignored.
837		938
838	Best use "AnyEvent::post_detect { BLOCK }" when your application	939	Best use "AnyEvent::post_detect { BLOCK }" when your application
839	allows it,as it takes care of these details.	940	allows it, as it takes care of these details.
840		941
841	This variable is mainly useful for modules that can do something	942	This variable is mainly useful for modules that can do something
842	useful when AnyEvent is used and thus want to know when it is	943	useful when AnyEvent is used and thus want to know when it is
843	initialised, but do not need to even load it by default. This array	944	initialised, but do not need to even load it by default. This array
844	provides the means to hook into AnyEvent passively, without loading	945	provides the means to hook into AnyEvent passively, without loading
845	it.	946	it.
846		947
		948	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		949	together, you could put this into Coro (this is the actual code used
		950	by Coro to accomplish this):
		951
		952	if (defined $AnyEvent::MODEL) {
		953	# AnyEvent already initialised, so load Coro::AnyEvent
		954	require Coro::AnyEvent;
		955	} else {
		956	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		957	# as soon as it is
		958	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		959	}
		960
847	WHAT TO DO IN A MODULE	961	WHAT TO DO IN A MODULE
848	As a module author, you should "use AnyEvent" and call AnyEvent methods	962	As a module author, you should "use AnyEvent" and call AnyEvent methods
849	freely, but you should not load a specific event module or rely on it.	963	freely, but you should not load a specific event module or rely on it.
850		964
851	Be careful when you create watchers in the module body - AnyEvent will	965	Be careful when you create watchers in the module body - AnyEvent will
…		…
858	stall the whole program, and the whole point of using events is to stay	972	stall the whole program, and the whole point of using events is to stay
859	interactive.	973	interactive.
860		974
861	It is fine, however, to call "->recv" when the user of your module	975	It is fine, however, to call "->recv" when the user of your module
862	requests it (i.e. if you create a http request object ad have a method	976	requests it (i.e. if you create a http request object ad have a method
863	called "results" that returns the results, it should call "->recv"	977	called "results" that returns the results, it may call "->recv" freely,
864	freely, as the user of your module knows what she is doing. always).	978	as the user of your module knows what she is doing. Always).
865		979
866	WHAT TO DO IN THE MAIN PROGRAM	980	WHAT TO DO IN THE MAIN PROGRAM
867	There will always be a single main program - the only place that should	981	There will always be a single main program - the only place that should
868	dictate which event model to use.	982	dictate which event model to use.
869		983
870	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	984	If the program is not event-based, it need not do anything special, even
871	do anything special (it does not need to be event-based) and let	985	when it depends on a module that uses an AnyEvent. If the program itself
872	AnyEvent decide which implementation to chose if some module relies on	986	uses AnyEvent, but does not care which event loop is used, all it needs
873	it.	987	to do is "use AnyEvent". In either case, AnyEvent will choose the best
		988	available loop implementation.
874		989
875	If the main program relies on a specific event model - for example, in	990	If the main program relies on a specific event model - for example, in
876	Gtk2 programs you have to rely on the Glib module - you should load the	991	Gtk2 programs you have to rely on the Glib module - you should load the
877	event module before loading AnyEvent or any module that uses it:	992	event module before loading AnyEvent or any module that uses it:
878	generally speaking, you should load it as early as possible. The reason	993	generally speaking, you should load it as early as possible. The reason
879	is that modules might create watchers when they are loaded, and AnyEvent	994	is that modules might create watchers when they are loaded, and AnyEvent
880	will decide on the event model to use as soon as it creates watchers,	995	will decide on the event model to use as soon as it creates watchers,
881	and it might chose the wrong one unless you load the correct one	996	and it might choose the wrong one unless you load the correct one
882	yourself.	997	yourself.
883		998
884	You can chose to use a pure-perl implementation by loading the	999	You can chose to use a pure-perl implementation by loading the
885	"AnyEvent::Impl::Perl" module, which gives you similar behaviour	1000	"AnyEvent::Impl::Perl" module, which gives you similar behaviour
886	everywhere, but letting AnyEvent chose the model is generally better.	1001	everywhere, but letting AnyEvent chose the model is generally better.
…		…
903		1018
904	OTHER MODULES	1019	OTHER MODULES
905	The following is a non-exhaustive list of additional modules that use	1020	The following is a non-exhaustive list of additional modules that use
906	AnyEvent as a client and can therefore be mixed easily with other	1021	AnyEvent as a client and can therefore be mixed easily with other
907	AnyEvent modules and other event loops in the same program. Some of the	1022	AnyEvent modules and other event loops in the same program. Some of the
908	modules come with AnyEvent, most are available via CPAN.	1023	modules come as part of AnyEvent, the others are available via CPAN.
909		1024
910	AnyEvent::Util	1025	AnyEvent::Util
911	Contains various utility functions that replace often-used but	1026	Contains various utility functions that replace often-used blocking
912	blocking functions such as "inet_aton" by event-/callback-based	1027	functions such as "inet_aton" with event/callback-based versions.
913	versions.
914		1028
915	AnyEvent::Socket	1029	AnyEvent::Socket
916	Provides various utility functions for (internet protocol) sockets,	1030	Provides various utility functions for (internet protocol) sockets,
917	addresses and name resolution. Also functions to create non-blocking	1031	addresses and name resolution. Also functions to create non-blocking
918	tcp connections or tcp servers, with IPv6 and SRV record support and	1032	tcp connections or tcp servers, with IPv6 and SRV record support and
919	more.	1033	more.
920		1034
921	AnyEvent::Handle	1035	AnyEvent::Handle
922	Provide read and write buffers, manages watchers for reads and	1036	Provide read and write buffers, manages watchers for reads and
923	writes, supports raw and formatted I/O, I/O queued and fully	1037	writes, supports raw and formatted I/O, I/O queued and fully
924	transparent and non-blocking SSL/TLS (via AnyEvent::TLS.	1038	transparent and non-blocking SSL/TLS (via AnyEvent::TLS).
925		1039
926	AnyEvent::DNS	1040	AnyEvent::DNS
927	Provides rich asynchronous DNS resolver capabilities.	1041	Provides rich asynchronous DNS resolver capabilities.
928		1042
		1043	AnyEvent::HTTP, AnyEvent::IRC, AnyEvent::XMPP, AnyEvent::GPSD,
		1044	AnyEvent::IGS, AnyEvent::FCP
		1045	Implement event-based interfaces to the protocols of the same name
		1046	(for the curious, IGS is the International Go Server and FCP is the
		1047	Freenet Client Protocol).
		1048
		1049	AnyEvent::Handle::UDP
		1050	Here be danger!
		1051
		1052	As Pauli would put it, "Not only is it not right, it's not even
		1053	wrong!" - there are so many things wrong with AnyEvent::Handle::UDP,
		1054	most notably its use of a stream-based API with a protocol that
		1055	isn't streamable, that the only way to improve it is to delete it.
		1056
		1057	It features data corruption (but typically only under load) and
		1058	general confusion. On top, the author is not only clueless about UDP
		1059	but also fact-resistant - some gems of his understanding: "connect
		1060	doesn't work with UDP", "UDP packets are not IP packets", "UDP only
		1061	has datagrams, not packets", "I don't need to implement proper error
		1062	checking as UDP doesn't support error checking" and so on - he
		1063	doesn't even understand what's wrong with his module when it is
		1064	explained to him.
		1065
929	AnyEvent::HTTP	1066	AnyEvent::DBI
930	A simple-to-use HTTP library that is capable of making a lot of	1067	Executes DBI requests asynchronously in a proxy process for you,
931	concurrent HTTP requests.	1068	notifying you in an event-based way when the operation is finished.
		1069
		1070	AnyEvent::AIO
		1071	Truly asynchronous (as opposed to non-blocking) I/O, should be in
		1072	the toolbox of every event programmer. AnyEvent::AIO transparently
		1073	fuses IO::AIO and AnyEvent together, giving AnyEvent access to
		1074	event-based file I/O, and much more.
932		1075
933	AnyEvent::HTTPD	1076	AnyEvent::HTTPD
934	Provides a simple web application server framework.	1077	A simple embedded webserver.
935		1078
936	AnyEvent::FastPing	1079	AnyEvent::FastPing
937	The fastest ping in the west.	1080	The fastest ping in the west.
938		1081
939	AnyEvent::DBI
940	Executes DBI requests asynchronously in a proxy process.
941
942	AnyEvent::AIO
943	Truly asynchronous I/O, should be in the toolbox of every event
944	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
945	together.
946
947	AnyEvent::BDB
948	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently
949	fuses BDB and AnyEvent together.
950
951	AnyEvent::GPSD
952	A non-blocking interface to gpsd, a daemon delivering GPS
953	information.
954
955	AnyEvent::IRC
956	AnyEvent based IRC client module family (replacing the older
957	Net::IRC3).
958
959	AnyEvent::XMPP
960	AnyEvent based XMPP (Jabber protocol) module family (replacing the
961	older Net::XMPP2>.
962
963	AnyEvent::IGS
964	A non-blocking interface to the Internet Go Server protocol (used by
965	App::IGS).
966
967	Net::FCP
968	AnyEvent-based implementation of the Freenet Client Protocol,
969	birthplace of AnyEvent.
970
971	Event::ExecFlow
972	High level API for event-based execution flow control.
973
974	Coro	1082	Coro
975	Has special support for AnyEvent via Coro::AnyEvent.	1083	Has special support for AnyEvent via Coro::AnyEvent.
		1084
		1085	SIMPLIFIED AE API
		1086	Starting with version 5.0, AnyEvent officially supports a second, much
		1087	simpler, API that is designed to reduce the calling, typing and memory
		1088	overhead by using function call syntax and a fixed number of parameters.
		1089
		1090	See the AE manpage for details.
976		1091
977	ERROR AND EXCEPTION HANDLING	1092	ERROR AND EXCEPTION HANDLING
978	In general, AnyEvent does not do any error handling - it relies on the	1093	In general, AnyEvent does not do any error handling - it relies on the
979	caller to do that if required. The AnyEvent::Strict module (see also the	1094	caller to do that if required. The AnyEvent::Strict module (see also the
980	"PERL_ANYEVENT_STRICT" environment variable, below) provides strict	1095	"PERL_ANYEVENT_STRICT" environment variable, below) provides strict
…		…
1021	thoroughly check the arguments passed to most method calls. If it	1136	thoroughly check the arguments passed to most method calls. If it
1022	finds any problems, it will croak.	1137	finds any problems, it will croak.
1023		1138
1024	In other words, enables "strict" mode.	1139	In other words, enables "strict" mode.
1025		1140
1026	Unlike "use strict" (or it's modern cousin, "use common::sense", it	1141	Unlike "use strict" (or its modern cousin, "use common::sense", it
1027	is definitely recommended to keep it off in production. Keeping	1142	is definitely recommended to keep it off in production. Keeping
1028	"PERL_ANYEVENT_STRICT=1" in your environment while developing	1143	"PERL_ANYEVENT_STRICT=1" in your environment while developing
1029	programs can be very useful, however.	1144	programs can be very useful, however.
1030		1145
1031	"PERL_ANYEVENT_MODEL"	1146	"PERL_ANYEVENT_MODEL"
…		…
1159	warn "read: $input\n"; # output what has been read	1274	warn "read: $input\n"; # output what has been read
1160	$cv->send if $input =~ /^q/i; # quit program if /^q/i	1275	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1161	},	1276	},
1162	);	1277	);
1163		1278
1164	my $time_watcher; # can only be used once
1165
1166	sub new_timer {
1167	$timer = AnyEvent->timer (after => 1, cb => sub {	1279	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1168	warn "timeout\n"; # print 'timeout' about every second	1280	warn "timeout\n"; # print 'timeout' at most every second
1169	&new_timer; # and restart the time
1170	});
1171	}	1281	});
1172
1173	new_timer; # create first timer
1174		1282
1175	$cv->recv; # wait until user enters /^q/i	1283	$cv->recv; # wait until user enters /^q/i
1176		1284
1177	REAL-WORLD EXAMPLE	1285	REAL-WORLD EXAMPLE
1178	Consider the Net::FCP module. It features (among others) the following	1286	Consider the Net::FCP module. It features (among others) the following
…		…
1250		1358
1251	The actual code goes further and collects all errors ("die"s,	1359	The actual code goes further and collects all errors ("die"s,
1252	exceptions) that occurred during request processing. The "result" method	1360	exceptions) that occurred during request processing. The "result" method
1253	detects whether an exception as thrown (it is stored inside the $txn	1361	detects whether an exception as thrown (it is stored inside the $txn
1254	object) and just throws the exception, which means connection errors and	1362	object) and just throws the exception, which means connection errors and
1255	other problems get reported tot he code that tries to use the result,	1363	other problems get reported to the code that tries to use the result,
1256	not in a random callback.	1364	not in a random callback.
1257		1365
1258	All of this enables the following usage styles:	1366	All of this enables the following usage styles:
1259		1367
1260	1. Blocking:	1368	1. Blocking:
…		…
1305	through AnyEvent. The benchmark creates a lot of timers (with a zero	1413	through AnyEvent. The benchmark creates a lot of timers (with a zero
1306	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1414	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1307	which it is), lets them fire exactly once and destroys them again.	1415	which it is), lets them fire exactly once and destroys them again.
1308		1416
1309	Source code for this benchmark is found as eg/bench in the AnyEvent	1417	Source code for this benchmark is found as eg/bench in the AnyEvent
1310	distribution.	1418	distribution. It uses the AE interface, which makes a real difference
		1419	for the EV and Perl backends only.
1311		1420
1312	Explanation of the columns	1421	Explanation of the columns
1313	watcher is the number of event watchers created/destroyed. Since	1422	watcher is the number of event watchers created/destroyed. Since
1314	different event models feature vastly different performances, each event	1423	different event models feature vastly different performances, each event
1315	loop was given a number of watchers so that overall runtime is	1424	loop was given a number of watchers so that overall runtime is
…		…
1334	destroy is the time, in microseconds, that it takes to destroy a	1443	destroy is the time, in microseconds, that it takes to destroy a
1335	single watcher.	1444	single watcher.
1336		1445
1337	Results	1446	Results
1338	name watchers bytes create invoke destroy comment	1447	name watchers bytes create invoke destroy comment
1339	EV/EV 400000 224 0.47 0.35 0.27 EV native interface	1448	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1340	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	1449	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1341	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	1450	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1342	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	1451	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1343	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	1452	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1344	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	1453	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
1345	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll	1454	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
1346	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll	1455	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1347	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	1456	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1348	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	1457	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1349	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	1458	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1350	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	1459	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1351		1460
1352	Discussion	1461	Discussion
1353	The benchmark does not measure scalability of the event loop very	1462	The benchmark does not measure scalability of the event loop very
1354	well. For example, a select-based event loop (such as the pure perl one)	1463	well. For example, a select-based event loop (such as the pure perl one)
1355	can never compete with an event loop that uses epoll when the number of	1464	can never compete with an event loop that uses epoll when the number of
…		…
1366	benchmark machine, handling an event takes roughly 1600 CPU cycles with	1475	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1367	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000	1476	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000
1368	CPU cycles with POE.	1477	CPU cycles with POE.
1369		1478
1370	"EV" is the sole leader regarding speed and memory use, which are both	1479	"EV" is the sole leader regarding speed and memory use, which are both
1371	maximal/minimal, respectively. Even when going through AnyEvent, it uses	1480	maximal/minimal, respectively. When using the AE API there is zero
		1481	overhead (when going through the AnyEvent API create is about 5-6 times
		1482	slower, with other times being equal, so still uses far less memory than
1372	far less memory than any other event loop and is still faster than Event	1483	any other event loop and is still faster than Event natively).
1373	natively.
1374		1484
1375	The pure perl implementation is hit in a few sweet spots (both the	1485	The pure perl implementation is hit in a few sweet spots (both the
1376	constant timeout and the use of a single fd hit optimisations in the	1486	constant timeout and the use of a single fd hit optimisations in the
1377	perl interpreter and the backend itself). Nevertheless this shows that	1487	perl interpreter and the backend itself). Nevertheless this shows that
1378	it adds very little overhead in itself. Like any select-based backend	1488	it adds very little overhead in itself. Like any select-based backend
…		…
1448	In this benchmark, we use 10000 socket pairs (20000 sockets), of which	1558	In this benchmark, we use 10000 socket pairs (20000 sockets), of which
1449	100 (1%) are active. This mirrors the activity of large servers with	1559	100 (1%) are active. This mirrors the activity of large servers with
1450	many connections, most of which are idle at any one point in time.	1560	many connections, most of which are idle at any one point in time.
1451		1561
1452	Source code for this benchmark is found as eg/bench2 in the AnyEvent	1562	Source code for this benchmark is found as eg/bench2 in the AnyEvent
1453	distribution.	1563	distribution. It uses the AE interface, which makes a real difference
		1564	for the EV and Perl backends only.
1454		1565
1455	Explanation of the columns	1566	Explanation of the columns
1456	sockets is the number of sockets, and twice the number of "servers"	1567	sockets is the number of sockets, and twice the number of "servers"
1457	(as each server has a read and write socket end).	1568	(as each server has a read and write socket end).
1458		1569
…		…
1464	forwarding it to another server. This includes deleting the old timeout	1575	forwarding it to another server. This includes deleting the old timeout
1465	and creating a new one that moves the timeout into the future.	1576	and creating a new one that moves the timeout into the future.
1466		1577
1467	Results	1578	Results
1468	name sockets create request	1579	name sockets create request
1469	EV 20000 69.01 11.16	1580	EV 20000 62.66 7.99
1470	Perl 20000 73.32 35.87	1581	Perl 20000 68.32 32.64
1471	IOAsync 20000 157.00 98.14 epoll	1582	IOAsync 20000 174.06 101.15 epoll
1472	IOAsync 20000 159.31 616.06 poll	1583	IOAsync 20000 174.67 610.84 poll
1473	Event 20000 212.62 257.32	1584	Event 20000 202.69 242.91
1474	Glib 20000 651.16 1896.30	1585	Glib 20000 557.01 1689.52
1475	POE 20000 349.67 12317.24 uses POE::Loop::Event	1586	POE 20000 341.54 12086.32 uses POE::Loop::Event
1476		1587
1477	Discussion	1588	Discussion
1478	This benchmark does measure scalability and overall performance of the	1589	This benchmark does measure scalability and overall performance of the
1479	particular event loop.	1590	particular event loop.
1480		1591
…		…
1593	As you can see, the AnyEvent + EV combination even beats the	1704	As you can see, the AnyEvent + EV combination even beats the
1594	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl	1705	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
1595	backend easily beats IO::Lambda and POE.	1706	backend easily beats IO::Lambda and POE.
1596		1707
1597	And even the 100% non-blocking version written using the high-level (and	1708	And even the 100% non-blocking version written using the high-level (and
1598	slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda by a	1709	slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda
1599	large margin, even though it does all of DNS, tcp-connect and socket I/O	1710	higher level ("unoptimised") abstractions by a large margin, even though
1600	in a non-blocking way.	1711	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
1601		1712
1602	The two AnyEvent benchmarks programs can be found as eg/ae0.pl and	1713	The two AnyEvent benchmarks programs can be found as eg/ae0.pl and
1603	eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are	1714	eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are
1604	part of the IO::lambda distribution and were used without any changes.	1715	part of the IO::Lambda distribution and were used without any changes.
1605		1716
1606	SIGNALS	1717	SIGNALS
1607	AnyEvent currently installs handlers for these signals:	1718	AnyEvent currently installs handlers for these signals:
1608		1719
1609	SIGCHLD	1720	SIGCHLD
…		…
1631		1742
1632	Feel free to install your own handler, or reset it to defaults.	1743	Feel free to install your own handler, or reset it to defaults.
1633		1744
1634	RECOMMENDED/OPTIONAL MODULES	1745	RECOMMENDED/OPTIONAL MODULES
1635	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and	1746	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
1636	it's built-in modules) are required to use it.	1747	its built-in modules) are required to use it.
1637		1748
1638	That does not mean that AnyEvent won't take advantage of some additional	1749	That does not mean that AnyEvent won't take advantage of some additional
1639	modules if they are installed.	1750	modules if they are installed.
1640		1751
1641	This section epxlains which additional modules will be used, and how	1752	This section explains which additional modules will be used, and how
1642	they affect AnyEvent's operetion.	1753	they affect AnyEvent's operation.
1643		1754
1644	Async::Interrupt	1755	Async::Interrupt
1645	This slightly arcane module is used to implement fast signal	1756	This slightly arcane module is used to implement fast signal
1646	handling: To my knowledge, there is no way to do completely	1757	handling: To my knowledge, there is no way to do completely
1647	race-free and quick signal handling in pure perl. To ensure that	1758	race-free and quick signal handling in pure perl. To ensure that
1648	signals still get delivered, AnyEvent will start an interval timer	1759	signals still get delivered, AnyEvent will start an interval timer
1649	to wake up perl (and catch the signals) with soemd elay (default is	1760	to wake up perl (and catch the signals) with some delay (default is
1650	10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY).	1761	10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY).
1651		1762
1652	If this module is available, then it will be used to implement	1763	If this module is available, then it will be used to implement
1653	signal catching, which means that signals will not be delayed, and	1764	signal catching, which means that signals will not be delayed, and
1654	the event loop will not be interrupted regularly, which is more	1765	the event loop will not be interrupted regularly, which is more
1655	efficient (And good for battery life on laptops).	1766	efficient (and good for battery life on laptops).
1656		1767
1657	This affects not just the pure-perl event loop, but also other event	1768	This affects not just the pure-perl event loop, but also other event
1658	loops that have no signal handling on their own (e.g. Glib, Tk, Qt).	1769	loops that have no signal handling on their own (e.g. Glib, Tk, Qt).
		1770
		1771	Some event loops (POE, Event, Event::Lib) offer signal watchers
		1772	natively, and either employ their own workarounds (POE) or use
		1773	AnyEvent's workaround (using $AnyEvent::MAX_SIGNAL_LATENCY).
		1774	Installing Async::Interrupt does nothing for those backends.
1659		1775
1660	EV This module isn't really "optional", as it is simply one of the	1776	EV This module isn't really "optional", as it is simply one of the
1661	backend event loops that AnyEvent can use. However, it is simply the	1777	backend event loops that AnyEvent can use. However, it is simply the
1662	best event loop available in terms of features, speed and stability:	1778	best event loop available in terms of features, speed and stability:
1663	It supports the AnyEvent API optimally, implements all the watcher	1779	It supports the AnyEvent API optimally, implements all the watcher
…		…
1665	clock is available, can take avdantage of advanced kernel interfaces	1781	clock is available, can take avdantage of advanced kernel interfaces
1666	such as "epoll" and "kqueue", and is the fastest backend by far.	1782	such as "epoll" and "kqueue", and is the fastest backend by far.
1667	You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and	1783	You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and
1668	Glib::EV).	1784	Glib::EV).
1669		1785
		1786	If you only use backends that rely on another event loop (e.g.
		1787	"Tk"), then this module will do nothing for you.
		1788
1670	Guard	1789	Guard
1671	The guard module, when used, will be used to implement	1790	The guard module, when used, will be used to implement
1672	"AnyEvent::Util::guard". This speeds up guards considerably (and	1791	"AnyEvent::Util::guard". This speeds up guards considerably (and
1673	uses a lot less memory), but otherwise doesn't affect guard	1792	uses a lot less memory), but otherwise doesn't affect guard
1674	operation much. It is purely used for performance.	1793	operation much. It is purely used for performance.
1675		1794
1676	JSON and JSON::XS	1795	JSON and JSON::XS
1677	This module is required when you want to read or write JSON data via	1796	One of these modules is required when you want to read or write JSON
1678	AnyEvent::Handle. It is also written in pure-perl, but can take	1797	data via AnyEvent::Handle. JSON is also written in pure-perl, but
1679	advantage of the ulta-high-speed JSON::XS module when it is	1798	can take advantage of the ultra-high-speed JSON::XS module when it
1680	installed.	1799	is installed.
1681
1682	In fact, AnyEvent::Handle will use JSON::XS by default if it is
1683	installed.
1684		1800
1685	Net::SSLeay	1801	Net::SSLeay
1686	Implementing TLS/SSL in Perl is certainly interesting, but not very	1802	Implementing TLS/SSL in Perl is certainly interesting, but not very
1687	worthwhile: If this module is installed, then AnyEvent::Handle (with	1803	worthwhile: If this module is installed, then AnyEvent::Handle (with
1688	the help of AnyEvent::TLS), gains the ability to do TLS/SSL.	1804	the help of AnyEvent::TLS), gains the ability to do TLS/SSL.
1689		1805
1690	Time::HiRes	1806	Time::HiRes
1691	This module is part of perl since release 5.008. It will be used	1807	This module is part of perl since release 5.008. It will be used
1692	when the chosen event library does not come with a timing source on	1808	when the chosen event library does not come with a timing source of
1693	it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will	1809	its own. The pure-perl event loop (AnyEvent::Impl::Perl) will
1694	additionally use it to try to use a monotonic clock for timing	1810	additionally use it to try to use a monotonic clock for timing
1695	stability.	1811	stability.
1696		1812
1697	FORK	1813	FORK
1698	Most event libraries are not fork-safe. The ones who are usually are	1814	Most event libraries are not fork-safe. The ones who are usually are
1699	because they rely on inefficient but fork-safe "select" or "poll" calls.	1815	because they rely on inefficient but fork-safe "select" or "poll" calls
1700	Only EV is fully fork-aware.	1816	- higher performance APIs such as BSD's kqueue or the dreaded Linux
		1817	epoll are usually badly thought-out hacks that are incompatible with
		1818	fork in one way or another. Only EV is fully fork-aware and ensures that
		1819	you continue event-processing in both parent and child (or both, if you
		1820	know what you are doing).
		1821
		1822	This means that, in general, you cannot fork and do event processing in
		1823	the child if the event library was initialised before the fork (which
		1824	usually happens when the first AnyEvent watcher is created, or the
		1825	library is loaded).
1701		1826
1702	If you have to fork, you must either do so before creating your first	1827	If you have to fork, you must either do so before creating your first
1703	watcher OR you must not use AnyEvent at all in the child OR you must do	1828	watcher OR you must not use AnyEvent at all in the child OR you must do
1704	something completely out of the scope of AnyEvent.	1829	something completely out of the scope of AnyEvent.
		1830
		1831	The problem of doing event processing in the parent and the child is
		1832	much more complicated: even for backends that are fork-aware or
		1833	fork-safe, their behaviour is not usually what you want: fork clones all
		1834	watchers, that means all timers, I/O watchers etc. are active in both
		1835	parent and child, which is almost never what you want. USing "exec" to
		1836	start worker children from some kind of manage rprocess is usually
		1837	preferred, because it is much easier and cleaner, at the expense of
		1838	having to have another binary.
1705		1839
1706	SECURITY CONSIDERATIONS	1840	SECURITY CONSIDERATIONS
1707	AnyEvent can be forced to load any event model via	1841	AnyEvent can be forced to load any event model via
1708	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used	1842	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used
1709	to execute arbitrary code or directly gain access, it can easily be used	1843	to execute arbitrary code or directly gain access, it can easily be used
…		…
1733	5.10 and check wether the leaks still show up. (Perl 5.10.0 has other	1867	5.10 and check wether the leaks still show up. (Perl 5.10.0 has other
1734	annoying memleaks, such as leaking on "map" and "grep" but it is usually	1868	annoying memleaks, such as leaking on "map" and "grep" but it is usually
1735	not as pronounced).	1869	not as pronounced).
1736		1870
1737	SEE ALSO	1871	SEE ALSO
		1872	Tutorial/Introduction: AnyEvent::Intro.
		1873
		1874	FAQ: AnyEvent::FAQ.
		1875
1738	Utility functions: AnyEvent::Util.	1876	Utility functions: AnyEvent::Util.
1739		1877
1740	Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,	1878	Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,
1741	Event::Lib, Qt, POE.	1879	Event::Lib, Qt, POE.
1742		1880
1743	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,	1881	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,
1744	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,	1882	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,
1745	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,	1883	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,
1746	AnyEvent::Impl::IOAsync.	1884	AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi.
1747		1885
1748	Non-blocking file handles, sockets, TCP clients and servers:	1886	Non-blocking file handles, sockets, TCP clients and servers:
1749	AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.	1887	AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.
1750		1888
1751	Asynchronous DNS: AnyEvent::DNS.	1889	Asynchronous DNS: AnyEvent::DNS.
1752		1890
1753	Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event,	1891	Thread support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event.
1754		1892
1755	Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP,	1893	Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::IRC,
1756	AnyEvent::HTTP.	1894	AnyEvent::HTTP.
1757		1895
1758	AUTHOR	1896	AUTHOR
1759	Marc Lehmann <schmorp@schmorp.de>	1897	Marc Lehmann <schmorp@schmorp.de>
1760	http://home.schmorp.de/	1898	http://home.schmorp.de/

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Comparing AnyEvent/README (file contents): Revision 1.46 by root, Sat Jul 18 05:19:09 2009 UTC vs. Revision 1.64 by root, Fri Dec 31 04:50:44 2010 UTC

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Comparing AnyEvent/README (file contents):
Revision 1.46 by root, Sat Jul 18 05:19:09 2009 UTC vs.
Revision 1.64 by root, Fri Dec 31 04:50:44 2010 UTC