[ViewVC] Diff of: cvs/AnyEvent/README

Comparing AnyEvent/README (file contents):
Revision 1.58 by root, Sun Dec 20 22:49:52 2009 UTC vs.
Revision 1.70 by root, Fri Apr 13 09:57:41 2012 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, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async,
5	Qt and POE are various supported event loops/environments.	5	Qt, FLTK 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
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.
42		45
43	SUPPORT	46	SUPPORT
		47	An FAQ document is available as AnyEvent::FAQ.
		48
44	There is a mailinglist for discussing all things AnyEvent, and an IRC	49	There also is a mailinglist for discussing all things AnyEvent, and an
45	channel, too.	50	IRC channel, too.
46		51
47	See the AnyEvent project page at the Schmorpforge Ta-Sa Software	52	See the AnyEvent project page at the Schmorpforge Ta-Sa Software
48	Repository, at <http://anyevent.schmorp.de>, for more info.	53	Repository, at <http://anyevent.schmorp.de>, for more info.
49		54
50	WHY YOU SHOULD USE THIS MODULE (OR NOT)	55	WHY YOU SHOULD USE THIS MODULE (OR NOT)
…		…
68	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
69	model you use.	74	model you use.
70		75
71	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
72	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
73	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
74	cannot use anything else, as they are simply incompatible to everything	79	cannot use anything else, as they are simply incompatible to everything
75	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
76	are also forced to use the same event loop you use.	81	are also forced to use the same event loop you use.
77		82
78	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	83	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
79	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
80	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
81	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
82	But if your module uses AnyEvent, it works transparently with all event	87	your module uses AnyEvent, it works transparently with all event models
83	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
84	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
85	to AnyEvent, too, so it is future-proof).	90	AnyEvent, too, so it is future-proof).
86		91
87	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
88	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
89	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
90	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
91	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
92	wrapper as technically possible.	97	technically possible.
93		98
94	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
95	useful functionality, such as an asynchronous DNS resolver, 100%	100	useful functionality, such as an asynchronous DNS resolver, 100%
96	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
97	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
…		…
100	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
101	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
102	model, you should not use this module.	107	model, you should not use this module.
103		108
104	DESCRIPTION	109	DESCRIPTION
105	AnyEvent provides an identical interface to multiple event loops. This	110	AnyEvent provides a uniform interface to various event loops. This
106	allows module authors to utilise an event loop without forcing module	111	allows module authors to use event loop functionality without forcing
107	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
108	coexist peacefully at any one time).	113	than one event loop cannot coexist peacefully).
109		114
110	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
111	module.	116	module.
112		117
113	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
114	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
115	following modules is already loaded: EV, Event, Glib,	120	following modules is already loaded: EV, AnyEvent::Loop, Event, Glib,
116	AnyEvent::Impl::Perl, Tk, Event::Lib, Qt, POE. The first one found is	121	Tk, Event::Lib, Qt, POE. The first one found is used. If none are
117	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
118	(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
119	always succeed) in the order given. The first one that can be	124	AnyEvent::Loop should always work, so the other two are not normally
120	successfully loaded will be used. If, after this, still none could be	125	tried.
121	found, AnyEvent will fall back to a pure-perl event loop, which is not
122	very efficient, but should work everywhere.
123		126
124	Because AnyEvent first checks for modules that are already loaded,	127	Because AnyEvent first checks for modules that are already loaded,
125	loading an event model explicitly before first using AnyEvent will	128	loading an event model explicitly before first using AnyEvent will
126	likely make that model the default. For example:	129	likely make that model the default. For example:
127		130
…		…
129	use AnyEvent;	132	use AnyEvent;
130		133
131	# .. AnyEvent will likely default to Tk	134	# .. AnyEvent will likely default to Tk
132		135
133	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
134	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
135	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.
136		140
137	The pure-perl implementation of AnyEvent is called	141	The pure-perl implementation of AnyEvent is called "AnyEvent::Loop".
138	"AnyEvent::Impl::Perl". Like other event modules you can load it	142	Like other event modules you can load it explicitly and enjoy the high
139	explicitly and enjoy the high availability of that event loop :)	143	availability of that event loop :)
140		144
141	WATCHERS	145	WATCHERS
142	AnyEvent has the central concept of a watcher, which is an object that	146	AnyEvent has the central concept of a watcher, which is an object that
143	stores relevant data for each kind of event you are waiting for, such as	147	stores relevant data for each kind of event you are waiting for, such as
144	the callback to call, the file handle to watch, etc.	148	the callback to call, the file handle to watch, etc.
…		…
148	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
149	in control).	153	in control).
150		154
151	Note that callbacks must not permanently change global variables	155	Note that callbacks must not permanently change global variables
152	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
153	callbacks must not "die". The former is good programming practise in	157	callbacks must not "die". The former is good programming practice in
154	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
155	widely between event loops.	159	widely between event loops.
156		160
157	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
158	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
159	to it).	163	to it).
160		164
161	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.
162		166
163	Many watchers either are used with "recursion" (repeating timers for	167	Many watchers either are used with "recursion" (repeating timers for
164	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.
165		169
166	An any way to achieve that is this pattern:	170	One way to achieve that is this pattern:
167		171
168	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	172	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
169	# you can use $w here, for example to undef it	173	# you can use $w here, for example to undef it
170	undef $w;	174	undef $w;
171	});	175	});
…		…
202		206
203	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
204	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
205	the underlying file descriptor.	209	the underlying file descriptor.
206		210
207	Some event loops issue spurious readyness notifications, so you should	211	Some event loops issue spurious readiness notifications, so you should
208	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
209	handles.	213	handles.
210		214
211	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
212	watcher.	216	watcher.
…		…
235		239
236	Although the callback might get passed parameters, their value and	240	Although the callback might get passed parameters, their value and
237	presence is undefined and you cannot rely on them. Portable AnyEvent	241	presence is undefined and you cannot rely on them. Portable AnyEvent
238	callbacks cannot use arguments passed to time watcher callbacks.	242	callbacks cannot use arguments passed to time watcher callbacks.
239		243
240	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
241	parameter, "interval", as a strictly positive number (> 0), then the	245	parameter, "interval", as a strictly positive number (> 0), then the
242	callback will be invoked regularly at that interval (in fractional	246	callback will be invoked regularly at that interval (in fractional
243	seconds) after the first invocation. If "interval" is specified with a	247	seconds) after the first invocation. If "interval" is specified with a
244	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.
245		249
246	The callback will be rescheduled before invoking the callback, but no	250	The callback will be rescheduled before invoking the callback, but no
247	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
248	is only approximate.	252	is only approximate.
249		253
250	Example: fire an event after 7.7 seconds.	254	Example: fire an event after 7.7 seconds.
251		255
252	my $w = AnyEvent->timer (after => 7.7, cb => sub {	256	my $w = AnyEvent->timer (after => 7.7, cb => sub {
…		…
269		273
270	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,
271	they use absolute time internally. This makes a difference when your	275	they use absolute time internally. This makes a difference when your
272	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
273	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
274	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
275	finally fire.	279	finally fire.
276		280
277	AnyEvent cannot compensate for this. The only event loop that is	281	AnyEvent cannot compensate for this. The only event loop that is
278	conscious about these issues is EV, which offers both relative	282	conscious of these issues is EV, which offers both relative (ev_timer,
279	(ev_timer, based on true relative time) and absolute (ev_periodic, based	283	based on true relative time) and absolute (ev_periodic, based on
280	on wallclock time) timers.	284	wallclock time) timers.
281		285
282	AnyEvent always prefers relative timers, if available, matching the	286	AnyEvent always prefers relative timers, if available, matching the
283	AnyEvent API.	287	AnyEvent API.
284		288
285	AnyEvent has two additional methods that return the "current time":	289	AnyEvent has two additional methods that return the "current time":
…		…
304	*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
305	function to call when you want to know the current time.*	309	function to call when you want to know the current time.*
306		310
307	This function is also often faster then "AnyEvent->time", and thus	311	This function is also often faster then "AnyEvent->time", and thus
308	the preferred method if you want some timestamp (for example,	312	the preferred method if you want some timestamp (for example,
309	AnyEvent::Handle uses this to update it's activity timeouts).	313	AnyEvent::Handle uses this to update its activity timeouts).
310		314
311	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
312	exact with your timing, you can skip it without bad conscience.	316	exact with your timing; you can skip it without a bad conscience.
313		317
314	For a practical example of when these times differ, consider	318	For a practical example of when these times differ, consider
315	Event::Lib and EV and the following set-up:	319	Event::Lib and EV and the following set-up:
316		320
317	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
318	at time=500 (assume no other callbacks delay processing). In your	322	at time=500 (assume no other callbacks delay processing). In your
319	callback, you wait a second by executing "sleep 1" (blocking the	323	callback, you wait a second by executing "sleep 1" (blocking the
320	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
321	timer that fires after three seconds.	325	timer that fires after three seconds.
322		326
…		…
343	can get whatever behaviour you want with any event loop, by taking	347	can get whatever behaviour you want with any event loop, by taking
344	the difference between "AnyEvent->time" and "AnyEvent->now" into	348	the difference between "AnyEvent->time" and "AnyEvent->now" into
345	account.	349	account.
346		350
347	AnyEvent->now_update	351	AnyEvent->now_update
348	Some event loops (such as EV or AnyEvent::Impl::Perl) cache the	352	Some event loops (such as EV or AnyEvent::Loop) cache the current
349	current time for each loop iteration (see the discussion of	353	time for each loop iteration (see the discussion of AnyEvent->now,
350	AnyEvent->now, above).	354	above).
351		355
352	When a callback runs for a long time (or when the process sleeps),	356	When a callback runs for a long time (or when the process sleeps),
353	then this "current" time will differ substantially from the real	357	then this "current" time will differ substantially from the real
354	time, which might affect timers and time-outs.	358	time, which might affect timers and time-outs.
355		359
…		…
399	will not restart syscalls (that includes Async::Interrupt and AnyEvent's	403	will not restart syscalls (that includes Async::Interrupt and AnyEvent's
400	pure perl implementation).	404	pure perl implementation).
401		405
402	Safe/Unsafe Signals	406	Safe/Unsafe Signals
403	Perl signals can be either "safe" (synchronous to opcode handling) or	407	Perl signals can be either "safe" (synchronous to opcode handling) or
404	"unsafe" (asynchronous) - the former might get delayed indefinitely, the	408	"unsafe" (asynchronous) - the former might delay signal delivery
405	latter might corrupt your memory.	409	indefinitely, the latter might corrupt your memory.
406		410
407	AnyEvent signal handlers are, in addition, synchronous to the event	411	AnyEvent signal handlers are, in addition, synchronous to the event
408	loop, i.e. they will not interrupt your running perl program but will	412	loop, i.e. they will not interrupt your running perl program but will
409	only be called as part of the normal event handling (just like timer,	413	only be called as part of the normal event handling (just like timer,
410	I/O etc. callbacks, too).	414	I/O etc. callbacks, too).
411		415
412	Signal Races, Delays and Workarounds	416	Signal Races, Delays and Workarounds
413	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching	417	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
414	callbacks to signals in a generic way, which is a pity, as you cannot do	418	callbacks to signals in a generic way, which is a pity, as you cannot do
415	race-free signal handling in perl, requiring C libraries for this.	419	race-free signal handling in perl, requiring C libraries for this.
416	AnyEvent will try to do it's best, which means in some cases, signals	420	AnyEvent will try to do its best, which means in some cases, signals
417	will be delayed. The maximum time a signal might be delayed is specified	421	will be delayed. The maximum time a signal might be delayed is 10
418	in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable	422	seconds by default, but can be overriden via
419	can be changed only before the first signal watcher is created, and	423	$ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY} or $AnyEvent::MAX_SIGNAL_LATENCY
420	should be left alone otherwise. This variable determines how often	424	- see the "ENVIRONMENT VARIABLES" section for details.
421	AnyEvent polls for signals (in case a wake-up was missed). Higher values
422	will cause fewer spurious wake-ups, which is better for power and CPU
423	saving.
424		425
425	All these problems can be avoided by installing the optional	426	All these problems can be avoided by installing the optional
426	Async::Interrupt module, which works with most event loops. It will not	427	Async::Interrupt module, which works with most event loops. It will not
427	work with inherently broken event loops such as Event or Event::Lib (and	428	work with inherently broken event loops such as Event or Event::Lib (and
428	not with POE currently, as POE does it's own workaround with one-second
429	latency). For those, you just have to suffer the delays.	429	not with POE currently). For those, you just have to suffer the delays.
430		430
431	CHILD PROCESS WATCHERS	431	CHILD PROCESS WATCHERS
432	$w = AnyEvent->child (pid => <process id>, cb => <callback>);	432	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
433		433
434	You can also watch on a child process exit and catch its exit status.	434	You can also watch for a child process exit and catch its exit status.
435		435
436	The child process is specified by the "pid" argument (one some backends,	436	The child process is specified by the "pid" argument (on some backends,
437	using 0 watches for any child process exit, on others this will croak).	437	using 0 watches for any child process exit, on others this will croak).
438	The watcher will be triggered only when the child process has finished	438	The watcher will be triggered only when the child process has finished
439	and an exit status is available, not on any trace events	439	and an exit status is available, not on any trace events
440	(stopped/continued).	440	(stopped/continued).
441		441
…		…
462	This means you cannot create a child watcher as the very first thing in	462	This means you cannot create a child watcher as the very first thing in
463	an AnyEvent program, you have to create at least one watcher before	463	an AnyEvent program, you have to create at least one watcher before
464	you "fork" the child (alternatively, you can call "AnyEvent::detect").	464	you "fork" the child (alternatively, you can call "AnyEvent::detect").
465		465
466	As most event loops do not support waiting for child events, they will	466	As most event loops do not support waiting for child events, they will
467	be emulated by AnyEvent in most cases, in which the latency and race	467	be emulated by AnyEvent in most cases, in which case the latency and
468	problems mentioned in the description of signal watchers apply.	468	race problems mentioned in the description of signal watchers apply.
469		469
470	Example: fork a process and wait for it	470	Example: fork a process and wait for it
471		471
472	my $done = AnyEvent->condvar;	472	my $done = AnyEvent->condvar;
473		473
…		…
486	$done->recv;	486	$done->recv;
487		487
488	IDLE WATCHERS	488	IDLE WATCHERS
489	$w = AnyEvent->idle (cb => <callback>);	489	$w = AnyEvent->idle (cb => <callback>);
490		490
491	Sometimes there is a need to do something, but it is not so important to	491	This will repeatedly invoke the callback after the process becomes idle,
492	do it instantly, but only when there is nothing better to do. This	492	until either the watcher is destroyed or new events have been detected.
493	"nothing better to do" is usually defined to be "no other events need
494	attention by the event loop".
495		493
496	Idle watchers ideally get invoked when the event loop has nothing better	494	Idle watchers are useful when there is a need to do something, but it is
497	to do, just before it would block the process to wait for new events.	495	not so important (or wise) to do it instantly. The callback will be
498	Instead of blocking, the idle watcher is invoked.	496	invoked only when there is "nothing better to do", which is usually
		497	defined as "all outstanding events have been handled and no new events
		498	have been detected". That means that idle watchers ideally get invoked
		499	when the event loop has just polled for new events but none have been
		500	detected. Instead of blocking to wait for more events, the idle watchers
		501	will be invoked.
499		502
500	Most event loops unfortunately do not really support idle watchers (only	503	Unfortunately, most event loops do not really support idle watchers
501	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent	504	(only EV, Event and Glib do it in a usable fashion) - for the rest,
502	will simply call the callback "from time to time".	505	AnyEvent will simply call the callback "from time to time".
503		506
504	Example: read lines from STDIN, but only process them when the program	507	Example: read lines from STDIN, but only process them when the program
505	is otherwise idle:	508	is otherwise idle:
506		509
507	my @lines; # read data	510	my @lines; # read data
…		…
533		536
534	AnyEvent is slightly different: it expects somebody else to run the	537	AnyEvent is slightly different: it expects somebody else to run the
535	event loop and will only block when necessary (usually when told by the	538	event loop and will only block when necessary (usually when told by the
536	user).	539	user).
537		540
538	The instrument to do that is called a "condition variable", so called	541	The tool to do that is called a "condition variable", so called because
539	because they represent a condition that must become true.	542	they represent a condition that must become true.
540		543
541	Now is probably a good time to look at the examples further below.	544	Now is probably a good time to look at the examples further below.
542		545
543	Condition variables can be created by calling the "AnyEvent->condvar"	546	Condition variables can be created by calling the "AnyEvent->condvar"
544	method, usually without arguments. The only argument pair allowed is	547	method, usually without arguments. The only argument pair allowed is
…		…
549	After creation, the condition variable is "false" until it becomes	552	After creation, the condition variable is "false" until it becomes
550	"true" by calling the "send" method (or calling the condition variable	553	"true" by calling the "send" method (or calling the condition variable
551	as if it were a callback, read about the caveats in the description for	554	as if it were a callback, read about the caveats in the description for
552	the "->send" method).	555	the "->send" method).
553		556
554	Condition variables are similar to callbacks, except that you can	557	Since condition variables are the most complex part of the AnyEvent API,
555	optionally wait for them. They can also be called merge points - points	558	here are some different mental models of what they are - pick the ones
556	in time where multiple outstanding events have been processed. And yet	559	you can connect to:
557	another way to call them is transactions - each condition variable can	560
558	be used to represent a transaction, which finishes at some point and	561	* Condition variables are like callbacks - you can call them (and pass
559	delivers a result. And yet some people know them as "futures" - a	562	them instead of callbacks). Unlike callbacks however, you can also
560	promise to compute/deliver something that you can wait for.	563	wait for them to be called.
		564
		565	* Condition variables are signals - one side can emit or send them,
		566	the other side can wait for them, or install a handler that is
		567	called when the signal fires.
		568
		569	* Condition variables are like "Merge Points" - points in your program
		570	where you merge multiple independent results/control flows into one.
		571
		572	* Condition variables represent a transaction - functions that start
		573	some kind of transaction can return them, leaving the caller the
		574	choice between waiting in a blocking fashion, or setting a callback.
		575
		576	* Condition variables represent future values, or promises to deliver
		577	some result, long before the result is available.
561		578
562	Condition variables are very useful to signal that something has	579	Condition variables are very useful to signal that something has
563	finished, for example, if you write a module that does asynchronous http	580	finished, for example, if you write a module that does asynchronous http
564	requests, then a condition variable would be the ideal candidate to	581	requests, then a condition variable would be the ideal candidate to
565	signal the availability of results. The user can either act when the	582	signal the availability of results. The user can either act when the
…		…
578		595
579	Condition variables are represented by hash refs in perl, and the keys	596	Condition variables are represented by hash refs in perl, and the keys
580	used by AnyEvent itself are all named "_ae_XXX" to make subclassing easy	597	used by AnyEvent itself are all named "_ae_XXX" to make subclassing easy
581	(it is often useful to build your own transaction class on top of	598	(it is often useful to build your own transaction class on top of
582	AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call	599	AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call
583	it's "new" method in your own "new" method.	600	its "new" method in your own "new" method.
584		601
585	There are two "sides" to a condition variable - the "producer side"	602	There are two "sides" to a condition variable - the "producer side"
586	which eventually calls "-> send", and the "consumer side", which waits	603	which eventually calls "-> send", and the "consumer side", which waits
587	for the send to occur.	604	for the send to occur.
588		605
589	Example: wait for a timer.	606	Example: wait for a timer.
590		607
591	# wait till the result is ready	608	# condition: "wait till the timer is fired"
592	my $result_ready = AnyEvent->condvar;	609	my $timer_fired = AnyEvent->condvar;
593		610
594	# do something such as adding a timer	611	# create the timer - we could wait for, say
595	# or socket watcher the calls $result_ready->send	612	# a handle becomign ready, or even an
596	# when the "result" is ready.	613	# AnyEvent::HTTP request to finish, but
597	# in this case, we simply use a timer:	614	# in this case, we simply use a timer:
598	my $w = AnyEvent->timer (	615	my $w = AnyEvent->timer (
599	after => 1,	616	after => 1,
600	cb => sub { $result_ready->send },	617	cb => sub { $timer_fired->send },
601	);	618	);
602		619
603	# this "blocks" (while handling events) till the callback	620	# this "blocks" (while handling events) till the callback
604	# calls ->send	621	# calls ->send
605	$result_ready->recv;	622	$timer_fired->recv;
606		623
607	Example: wait for a timer, but take advantage of the fact that condition	624	Example: wait for a timer, but take advantage of the fact that condition
608	variables are also callable directly.	625	variables are also callable directly.
609		626
610	my $done = AnyEvent->condvar;	627	my $done = AnyEvent->condvar;
…		…
648	Condition variables are overloaded so one can call them directly (as	665	Condition variables are overloaded so one can call them directly (as
649	if they were a code reference). Calling them directly is the same as	666	if they were a code reference). Calling them directly is the same as
650	calling "send".	667	calling "send".
651		668
652	$cv->croak ($error)	669	$cv->croak ($error)
653	Similar to send, but causes all call's to "->recv" to invoke	670	Similar to send, but causes all calls to "->recv" to invoke
654	"Carp::croak" with the given error message/object/scalar.	671	"Carp::croak" with the given error message/object/scalar.
655		672
656	This can be used to signal any errors to the condition variable	673	This can be used to signal any errors to the condition variable
657	user/consumer. Doing it this way instead of calling "croak" directly	674	user/consumer. Doing it this way instead of calling "croak" directly
658	delays the error detetcion, but has the overwhelmign advantage that	675	delays the error detection, but has the overwhelming advantage that
659	it diagnoses the error at the place where the result is expected,	676	it diagnoses the error at the place where the result is expected,
660	and not deep in some event clalback without connection to the actual	677	and not deep in some event callback with no connection to the actual
661	code causing the problem.	678	code causing the problem.
662		679
663	$cv->begin ([group callback])	680	$cv->begin ([group callback])
664	$cv->end	681	$cv->end
665	These two methods can be used to combine many transactions/events	682	These two methods can be used to combine many transactions/events
…		…
702	there is one call to "begin", so the condvar waits for all calls to	719	there is one call to "begin", so the condvar waits for all calls to
703	"end" before sending.	720	"end" before sending.
704		721
705	The ping example mentioned above is slightly more complicated, as	722	The ping example mentioned above is slightly more complicated, as
706	the there are results to be passwd back, and the number of tasks	723	the there are results to be passwd back, and the number of tasks
707	that are begung can potentially be zero:	724	that are begun can potentially be zero:
708		725
709	my $cv = AnyEvent->condvar;	726	my $cv = AnyEvent->condvar;
710		727
711	my %result;	728	my %result;
712	$cv->begin (sub { shift->send (\%result) });	729	$cv->begin (sub { shift->send (\%result) });
…		…
733	callback to be called once the counter reaches 0, and second, it	750	callback to be called once the counter reaches 0, and second, it
734	ensures that "send" is called even when "no" hosts are being pinged	751	ensures that "send" is called even when "no" hosts are being pinged
735	(the loop doesn't execute once).	752	(the loop doesn't execute once).
736		753
737	This is the general pattern when you "fan out" into multiple (but	754	This is the general pattern when you "fan out" into multiple (but
738	potentially none) subrequests: use an outer "begin"/"end" pair to	755	potentially zero) subrequests: use an outer "begin"/"end" pair to
739	set the callback and ensure "end" is called at least once, and then,	756	set the callback and ensure "end" is called at least once, and then,
740	for each subrequest you start, call "begin" and for each subrequest	757	for each subrequest you start, call "begin" and for each subrequest
741	you finish, call "end".	758	you finish, call "end".
742		759
743	METHODS FOR CONSUMERS	760	METHODS FOR CONSUMERS
744	These methods should only be used by the consuming side, i.e. the code	761	These methods should only be used by the consuming side, i.e. the code
745	awaits the condition.	762	awaits the condition.
746		763
747	$cv->recv	764	$cv->recv
748	Wait (blocking if necessary) until the "->send" or "->croak" methods	765	Wait (blocking if necessary) until the "->send" or "->croak" methods
749	have been called on c<$cv>, while servicing other watchers normally.	766	have been called on $cv, while servicing other watchers normally.
750		767
751	You can only wait once on a condition - additional calls are valid	768	You can only wait once on a condition - additional calls are valid
752	but will return immediately.	769	but will return immediately.
753		770
754	If an error condition has been set by calling "->croak", then this	771	If an error condition has been set by calling "->croak", then this
…		…
771	example, by coupling condition variables with some kind of request	788	example, by coupling condition variables with some kind of request
772	results and supporting callbacks so the caller knows that getting	789	results and supporting callbacks so the caller knows that getting
773	the result will not block, while still supporting blocking waits if	790	the result will not block, while still supporting blocking waits if
774	the caller so desires).	791	the caller so desires).
775		792
776	You can ensure that "-recv" never blocks by setting a callback and	793	You can ensure that "->recv" never blocks by setting a callback and
777	only calling "->recv" from within that callback (or at a later	794	only calling "->recv" from within that callback (or at a later
778	time). This will work even when the event loop does not support	795	time). This will work even when the event loop does not support
779	blocking waits otherwise.	796	blocking waits otherwise.
780		797
781	$bool = $cv->ready	798	$bool = $cv->ready
…		…
784		801
785	$cb = $cv->cb ($cb->($cv))	802	$cb = $cv->cb ($cb->($cv))
786	This is a mutator function that returns the callback set and	803	This is a mutator function that returns the callback set and
787	optionally replaces it before doing so.	804	optionally replaces it before doing so.
788		805
789	The callback will be called when the condition becomes (or already	806	The callback will be called when the condition becomes "true", i.e.
790	was) "true", i.e. when "send" or "croak" are called (or were	807	when "send" or "croak" are called, with the only argument being the
791	called), with the only argument being the condition variable itself.	808	condition variable itself. If the condition is already true, the
792	Calling "recv" inside the callback or at any later time is	809	callback is called immediately when it is set. Calling "recv" inside
793	guaranteed not to block.	810	the callback or at any later time is guaranteed not to block.
794		811
795	SUPPORTED EVENT LOOPS/BACKENDS	812	SUPPORTED EVENT LOOPS/BACKENDS
796	The available backend classes are (every class has its own manpage):	813	The available backend classes are (every class has its own manpage):
797		814
798	Backends that are autoprobed when no other event loop can be found.	815	Backends that are autoprobed when no other event loop can be found.
…		…
800	use. If EV is not installed, then AnyEvent will fall back to its own	817	use. If EV is not installed, then AnyEvent will fall back to its own
801	pure-perl implementation, which is available everywhere as it comes	818	pure-perl implementation, which is available everywhere as it comes
802	with AnyEvent itself.	819	with AnyEvent itself.
803		820
804	AnyEvent::Impl::EV based on EV (interface to libev, best choice).	821	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
805	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.	822	AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
806		823
807	Backends that are transparently being picked up when they are used.	824	Backends that are transparently being picked up when they are used.
808	These will be used when they are currently loaded when the first	825	These will be used if they are already loaded when the first watcher
809	watcher is created, in which case it is assumed that the application	826	is created, in which case it is assumed that the application is
810	is using them. This means that AnyEvent will automatically pick the	827	using them. This means that AnyEvent will automatically pick the
811	right backend when the main program loads an event module before	828	right backend when the main program loads an event module before
812	anything starts to create watchers. Nothing special needs to be done	829	anything starts to create watchers. Nothing special needs to be done
813	by the main program.	830	by the main program.
814		831
815	AnyEvent::Impl::Event based on Event, very stable, few glitches.	832	AnyEvent::Impl::Event based on Event, very stable, few glitches.
816	AnyEvent::Impl::Glib based on Glib, slow but very stable.	833	AnyEvent::Impl::Glib based on Glib, slow but very stable.
817	AnyEvent::Impl::Tk based on Tk, very broken.	834	AnyEvent::Impl::Tk based on Tk, very broken.
818	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	835	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
819	AnyEvent::Impl::POE based on POE, very slow, some limitations.	836	AnyEvent::Impl::POE based on POE, very slow, some limitations.
820	AnyEvent::Impl::Irssi used when running within irssi.	837	AnyEvent::Impl::Irssi used when running within irssi.
		838	AnyEvent::Impl::IOAsync based on IO::Async.
		839	AnyEvent::Impl::Cocoa based on Cocoa::EventLoop.
		840	AnyEvent::Impl::FLTK based on FLTK (fltk 2 binding).
821		841
822	Backends with special needs.	842	Backends with special needs.
823	Qt requires the Qt::Application to be instantiated first, but will	843	Qt requires the Qt::Application to be instantiated first, but will
824	otherwise be picked up automatically. As long as the main program	844	otherwise be picked up automatically. As long as the main program
825	instantiates the application before any AnyEvent watchers are	845	instantiates the application before any AnyEvent watchers are
826	created, everything should just work.	846	created, everything should just work.
827		847
828	AnyEvent::Impl::Qt based on Qt.	848	AnyEvent::Impl::Qt based on Qt.
829		849
830	Support for IO::Async can only be partial, as it is too broken and
831	architecturally limited to even support the AnyEvent API. It also is
832	the only event loop that needs the loop to be set explicitly, so it
833	can only be used by a main program knowing about AnyEvent. See
834	AnyEvent::Impl::Async for the gory details.
835
836	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
837
838	Event loops that are indirectly supported via other backends.	850	Event loops that are indirectly supported via other backends.
839	Some event loops can be supported via other modules:	851	Some event loops can be supported via other modules:
840		852
841	There is no direct support for WxWidgets (Wx) or Prima.	853	There is no direct support for WxWidgets (Wx) or Prima.
842		854
…		…
860	Contains "undef" until the first watcher is being created, before	872	Contains "undef" until the first watcher is being created, before
861	the backend has been autodetected.	873	the backend has been autodetected.
862		874
863	Afterwards it contains the event model that is being used, which is	875	Afterwards it contains the event model that is being used, which is
864	the name of the Perl class implementing the model. This class is	876	the name of the Perl class implementing the model. This class is
865	usually one of the "AnyEvent::Impl:xxx" modules, but can be any	877	usually one of the "AnyEvent::Impl::xxx" modules, but can be any
866	other class in the case AnyEvent has been extended at runtime (e.g.	878	other class in the case AnyEvent has been extended at runtime (e.g.
867	in rxvt-unicode it will be "urxvt::anyevent").	879	in rxvt-unicode it will be "urxvt::anyevent").
868		880
869	AnyEvent::detect	881	AnyEvent::detect
870	Returns $AnyEvent::MODEL, forcing autodetection of the event model	882	Returns $AnyEvent::MODEL, forcing autodetection of the event model
871	if necessary. You should only call this function right before you	883	if necessary. You should only call this function right before you
872	would have created an AnyEvent watcher anyway, that is, as late as	884	would have created an AnyEvent watcher anyway, that is, as late as
873	possible at runtime, and not e.g. while initialising of your module.	885	possible at runtime, and not e.g. during initialisation of your
		886	module.
		887
		888	The effect of calling this function is as if a watcher had been
		889	created (specifically, actions that happen "when the first watcher
		890	is created" happen when calling detetc as well).
874		891
875	If you need to do some initialisation before AnyEvent watchers are	892	If you need to do some initialisation before AnyEvent watchers are
876	created, use "post_detect".	893	created, use "post_detect".
877		894
878	$guard = AnyEvent::post_detect { BLOCK }	895	$guard = AnyEvent::post_detect { BLOCK }
879	Arranges for the code block to be executed as soon as the event	896	Arranges for the code block to be executed as soon as the event
880	model is autodetected (or immediately if this has already happened).	897	model is autodetected (or immediately if that has already happened).
881		898
882	The block will be executed after the actual backend has been	899	The block will be executed after the actual backend has been
883	detected ($AnyEvent::MODEL is set), but before any watchers have	900	detected ($AnyEvent::MODEL is set), but before any watchers have
884	been created, so it is possible to e.g. patch @AnyEvent::ISA or do	901	been created, so it is possible to e.g. patch @AnyEvent::ISA or do
885	other initialisations - see the sources of AnyEvent::Strict or	902	other initialisations - see the sources of AnyEvent::Strict or
…		…
894	object that automatically removes the callback again when it is	911	object that automatically removes the callback again when it is
895	destroyed (or "undef" when the hook was immediately executed). See	912	destroyed (or "undef" when the hook was immediately executed). See
896	AnyEvent::AIO for a case where this is useful.	913	AnyEvent::AIO for a case where this is useful.
897		914
898	Example: Create a watcher for the IO::AIO module and store it in	915	Example: Create a watcher for the IO::AIO module and store it in
899	$WATCHER. Only do so after the event loop is initialised, though.	916	$WATCHER, but do so only do so after the event loop is initialised.
900		917
901	our WATCHER;	918	our WATCHER;
902		919
903	my $guard = AnyEvent::post_detect {	920	my $guard = AnyEvent::post_detect {
904	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);	921	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
…		…
911		928
912	$WATCHER \|\|= $guard;	929	$WATCHER \|\|= $guard;
913		930
914	@AnyEvent::post_detect	931	@AnyEvent::post_detect
915	If there are any code references in this array (you can "push" to it	932	If there are any code references in this array (you can "push" to it
916	before or after loading AnyEvent), then they will called directly	933	before or after loading AnyEvent), then they will be called directly
917	after the event loop has been chosen.	934	after the event loop has been chosen.
918		935
919	You should check $AnyEvent::MODEL before adding to this array,	936	You should check $AnyEvent::MODEL before adding to this array,
920	though: if it is defined then the event loop has already been	937	though: if it is defined then the event loop has already been
921	detected, and the array will be ignored.	938	detected, and the array will be ignored.
…		…
940	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent	957	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
941	# as soon as it is	958	# as soon as it is
942	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };	959	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
943	}	960	}
944		961
		962	AnyEvent::postpone { BLOCK }
		963	Arranges for the block to be executed as soon as possible, but not
		964	before the call itself returns. In practise, the block will be
		965	executed just before the event loop polls for new events, or shortly
		966	afterwards.
		967
		968	This function never returns anything (to make the "return postpone {
		969	... }" idiom more useful.
		970
		971	To understand the usefulness of this function, consider a function
		972	that asynchronously does something for you and returns some
		973	transaction object or guard to let you cancel the operation. For
		974	example, "AnyEvent::Socket::tcp_connect":
		975
		976	# start a conenction attempt unless one is active
		977	$self->{connect_guard} \|\|= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
		978	delete $self->{connect_guard};
		979	...
		980	};
		981
		982	Imagine that this function could instantly call the callback, for
		983	example, because it detects an obvious error such as a negative port
		984	number. Invoking the callback before the function returns causes
		985	problems however: the callback will be called and will try to delete
		986	the guard object. But since the function hasn't returned yet, there
		987	is nothing to delete. When the function eventually returns it will
		988	assign the guard object to "$self->{connect_guard}", where it will
		989	likely never be deleted, so the program thinks it is still trying to
		990	connect.
		991
		992	This is where "AnyEvent::postpone" should be used. Instead of
		993	calling the callback directly on error:
		994
		995	$cb->(undef), return # signal error to callback, BAD!
		996	if $some_error_condition;
		997
		998	It should use "postpone":
		999
		1000	AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
		1001	if $some_error_condition;
		1002
		1003	AnyEvent::log $level, $msg[, @args]
		1004	Log the given $msg at the given $level.
		1005
		1006	If AnyEvent::Log is not loaded then this function makes a simple
		1007	test to see whether the message will be logged. If the test succeeds
		1008	it will load AnyEvent::Log and call "AnyEvent::Log::log" -
		1009	consequently, look at the AnyEvent::Log documentation for details.
		1010
		1011	If the test fails it will simply return. Right now this happens when
		1012	a numerical loglevel is used and it is larger than the level
		1013	specified via $ENV{PERL_ANYEVENT_VERBOSE}.
		1014
		1015	If you want to sprinkle loads of logging calls around your code,
		1016	consider creating a logger callback with the "AnyEvent::Log::logger"
		1017	function, which can reduce typing, codesize and can reduce the
		1018	logging overhead enourmously.
		1019
945	WHAT TO DO IN A MODULE	1020	WHAT TO DO IN A MODULE
946	As a module author, you should "use AnyEvent" and call AnyEvent methods	1021	As a module author, you should "use AnyEvent" and call AnyEvent methods
947	freely, but you should not load a specific event module or rely on it.	1022	freely, but you should not load a specific event module or rely on it.
948		1023
949	Be careful when you create watchers in the module body - AnyEvent will	1024	Be careful when you create watchers in the module body - AnyEvent will
…		…
956	stall the whole program, and the whole point of using events is to stay	1031	stall the whole program, and the whole point of using events is to stay
957	interactive.	1032	interactive.
958		1033
959	It is fine, however, to call "->recv" when the user of your module	1034	It is fine, however, to call "->recv" when the user of your module
960	requests it (i.e. if you create a http request object ad have a method	1035	requests it (i.e. if you create a http request object ad have a method
961	called "results" that returns the results, it should call "->recv"	1036	called "results" that returns the results, it may call "->recv" freely,
962	freely, as the user of your module knows what she is doing. always).	1037	as the user of your module knows what she is doing. Always).
963		1038
964	WHAT TO DO IN THE MAIN PROGRAM	1039	WHAT TO DO IN THE MAIN PROGRAM
965	There will always be a single main program - the only place that should	1040	There will always be a single main program - the only place that should
966	dictate which event model to use.	1041	dictate which event model to use.
967		1042
968	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1043	If the program is not event-based, it need not do anything special, even
969	do anything special (it does not need to be event-based) and let	1044	when it depends on a module that uses an AnyEvent. If the program itself
970	AnyEvent decide which implementation to chose if some module relies on	1045	uses AnyEvent, but does not care which event loop is used, all it needs
971	it.	1046	to do is "use AnyEvent". In either case, AnyEvent will choose the best
		1047	available loop implementation.
972		1048
973	If the main program relies on a specific event model - for example, in	1049	If the main program relies on a specific event model - for example, in
974	Gtk2 programs you have to rely on the Glib module - you should load the	1050	Gtk2 programs you have to rely on the Glib module - you should load the
975	event module before loading AnyEvent or any module that uses it:	1051	event module before loading AnyEvent or any module that uses it:
976	generally speaking, you should load it as early as possible. The reason	1052	generally speaking, you should load it as early as possible. The reason
977	is that modules might create watchers when they are loaded, and AnyEvent	1053	is that modules might create watchers when they are loaded, and AnyEvent
978	will decide on the event model to use as soon as it creates watchers,	1054	will decide on the event model to use as soon as it creates watchers,
979	and it might chose the wrong one unless you load the correct one	1055	and it might choose the wrong one unless you load the correct one
980	yourself.	1056	yourself.
981		1057
982	You can chose to use a pure-perl implementation by loading the	1058	You can chose to use a pure-perl implementation by loading the
983	"AnyEvent::Impl::Perl" module, which gives you similar behaviour	1059	"AnyEvent::Loop" module, which gives you similar behaviour everywhere,
984	everywhere, but letting AnyEvent chose the model is generally better.	1060	but letting AnyEvent chose the model is generally better.
985		1061
986	MAINLOOP EMULATION	1062	MAINLOOP EMULATION
987	Sometimes (often for short test scripts, or even standalone programs who	1063	Sometimes (often for short test scripts, or even standalone programs who
988	only want to use AnyEvent), you do not want to run a specific event	1064	only want to use AnyEvent), you do not want to run a specific event
989	loop.	1065	loop.
…		…
1001		1077
1002	OTHER MODULES	1078	OTHER MODULES
1003	The following is a non-exhaustive list of additional modules that use	1079	The following is a non-exhaustive list of additional modules that use
1004	AnyEvent as a client and can therefore be mixed easily with other	1080	AnyEvent as a client and can therefore be mixed easily with other
1005	AnyEvent modules and other event loops in the same program. Some of the	1081	AnyEvent modules and other event loops in the same program. Some of the
1006	modules come with AnyEvent, most are available via CPAN.	1082	modules come as part of AnyEvent, the others are available via CPAN (see
		1083	<http://search.cpan.org/search?m=module&q=anyevent%3A%3A*> for a longer
		1084	non-exhaustive list), and the list is heavily biased towards modules of
		1085	the AnyEvent author himself :)
1007		1086
1008	AnyEvent::Util	1087	AnyEvent::Util
1009	Contains various utility functions that replace often-used but	1088	Contains various utility functions that replace often-used blocking
1010	blocking functions such as "inet_aton" by event-/callback-based	1089	functions such as "inet_aton" with event/callback-based versions.
1011	versions.
1012		1090
1013	AnyEvent::Socket	1091	AnyEvent::Socket
1014	Provides various utility functions for (internet protocol) sockets,	1092	Provides various utility functions for (internet protocol) sockets,
1015	addresses and name resolution. Also functions to create non-blocking	1093	addresses and name resolution. Also functions to create non-blocking
1016	tcp connections or tcp servers, with IPv6 and SRV record support and	1094	tcp connections or tcp servers, with IPv6 and SRV record support and
1017	more.	1095	more.
1018		1096
1019	AnyEvent::Handle	1097	AnyEvent::Handle
1020	Provide read and write buffers, manages watchers for reads and	1098	Provide read and write buffers, manages watchers for reads and
1021	writes, supports raw and formatted I/O, I/O queued and fully	1099	writes, supports raw and formatted I/O, I/O queued and fully
1022	transparent and non-blocking SSL/TLS (via AnyEvent::TLS.	1100	transparent and non-blocking SSL/TLS (via AnyEvent::TLS).
1023		1101
1024	AnyEvent::DNS	1102	AnyEvent::DNS
1025	Provides rich asynchronous DNS resolver capabilities.	1103	Provides rich asynchronous DNS resolver capabilities.
1026		1104
		1105	AnyEvent::HTTP, AnyEvent::IRC, AnyEvent::XMPP, AnyEvent::GPSD,
		1106	AnyEvent::IGS, AnyEvent::FCP
		1107	Implement event-based interfaces to the protocols of the same name
		1108	(for the curious, IGS is the International Go Server and FCP is the
		1109	Freenet Client Protocol).
		1110
1027	AnyEvent::HTTP	1111	AnyEvent::AIO
1028	A simple-to-use HTTP library that is capable of making a lot of	1112	Truly asynchronous (as opposed to non-blocking) I/O, should be in
1029	concurrent HTTP requests.	1113	the toolbox of every event programmer. AnyEvent::AIO transparently
		1114	fuses IO::AIO and AnyEvent together, giving AnyEvent access to
		1115	event-based file I/O, and much more.
		1116
		1117	AnyEvent::Filesys::Notify
		1118	AnyEvent is good for non-blocking stuff, but it can't detect file or
		1119	path changes (e.g. "watch this directory for new files", "watch this
		1120	file for changes"). The AnyEvent::Filesys::Notify module promises to
		1121	do just that in a portbale fashion, supporting inotify on GNU/Linux
		1122	and some weird, without doubt broken, stuff on OS X to monitor
		1123	files. It can fall back to blocking scans at regular intervals
		1124	transparently on other platforms, so it's about as portable as it
		1125	gets.
		1126
		1127	(I haven't used it myself, but I haven't heard anybody complaining
		1128	about it yet).
		1129
		1130	AnyEvent::DBI
		1131	Executes DBI requests asynchronously in a proxy process for you,
		1132	notifying you in an event-based way when the operation is finished.
1030		1133
1031	AnyEvent::HTTPD	1134	AnyEvent::HTTPD
1032	Provides a simple web application server framework.	1135	A simple embedded webserver.
1033		1136
1034	AnyEvent::FastPing	1137	AnyEvent::FastPing
1035	The fastest ping in the west.	1138	The fastest ping in the west.
1036		1139
1037	AnyEvent::DBI
1038	Executes DBI requests asynchronously in a proxy process.
1039
1040	AnyEvent::AIO
1041	Truly asynchronous I/O, should be in the toolbox of every event
1042	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
1043	together.
1044
1045	AnyEvent::BDB
1046	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently
1047	fuses BDB and AnyEvent together.
1048
1049	AnyEvent::GPSD
1050	A non-blocking interface to gpsd, a daemon delivering GPS
1051	information.
1052
1053	AnyEvent::IRC
1054	AnyEvent based IRC client module family (replacing the older
1055	Net::IRC3).
1056
1057	AnyEvent::XMPP
1058	AnyEvent based XMPP (Jabber protocol) module family (replacing the
1059	older Net::XMPP2>.
1060
1061	AnyEvent::IGS
1062	A non-blocking interface to the Internet Go Server protocol (used by
1063	App::IGS).
1064
1065	Net::FCP
1066	AnyEvent-based implementation of the Freenet Client Protocol,
1067	birthplace of AnyEvent.
1068
1069	Event::ExecFlow
1070	High level API for event-based execution flow control.
1071
1072	Coro	1140	Coro
1073	Has special support for AnyEvent via Coro::AnyEvent.	1141	Has special support for AnyEvent via Coro::AnyEvent, which allows
		1142	you to simply invert the flow control - don't call us, we will call
		1143	you:
		1144
		1145	async {
		1146	Coro::AnyEvent::sleep 5; # creates a 5s timer and waits for it
		1147	print "5 seconds later!\n";
		1148
		1149	Coro::AnyEvent::readable *STDIN; # uses an I/O watcher
		1150	my $line = <STDIN>; # works for ttys
		1151
		1152	AnyEvent::HTTP::http_get "url", Coro::rouse_cb;
		1153	my ($body, $hdr) = Coro::rouse_wait;
		1154	};
1074		1155
1075	SIMPLIFIED AE API	1156	SIMPLIFIED AE API
1076	Starting with version 5.0, AnyEvent officially supports a second, much	1157	Starting with version 5.0, AnyEvent officially supports a second, much
1077	simpler, API that is designed to reduce the calling, typing and memory	1158	simpler, API that is designed to reduce the calling, typing and memory
1078	overhead.	1159	overhead by using function call syntax and a fixed number of parameters.
1079		1160
1080	See the AE manpage for details.	1161	See the AE manpage for details.
1081		1162
1082	ERROR AND EXCEPTION HANDLING	1163	ERROR AND EXCEPTION HANDLING
1083	In general, AnyEvent does not do any error handling - it relies on the	1164	In general, AnyEvent does not do any error handling - it relies on the
…		…
1094	The pure perl event loop simply re-throws the exception (usually within	1175	The pure perl event loop simply re-throws the exception (usually within
1095	"condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()",	1176	"condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()",
1096	Glib uses "install_exception_handler" and so on.	1177	Glib uses "install_exception_handler" and so on.
1097		1178
1098	ENVIRONMENT VARIABLES	1179	ENVIRONMENT VARIABLES
1099	The following environment variables are used by this module or its	1180	AnyEvent supports a number of environment variables that tune the
1100	submodules.	1181	runtime behaviour. They are usually evaluated when AnyEvent is loaded,
		1182	initialised, or a submodule that uses them is loaded. Many of them also
		1183	cause AnyEvent to load additional modules - for example,
		1184	"PERL_ANYEVENT_DEBUG_WRAP" causes the AnyEvent::Debug module to be
		1185	loaded.
1101		1186
1102	Note that AnyEvent will remove all environment variables starting with	1187	All the environment variables documented here start with
1103	"PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is	1188	"PERL_ANYEVENT_", which is what AnyEvent considers its own namespace.
1104	enabled.	1189	Other modules are encouraged (but by no means required) to use
		1190	"PERL_ANYEVENT_SUBMODULE" if they have registered the
		1191	AnyEvent::Submodule namespace on CPAN, for any submodule. For example,
		1192	AnyEvent::HTTP could be expected to use "PERL_ANYEVENT_HTTP_PROXY" (it
		1193	should not access env variables starting with "AE_", see below).
		1194
		1195	All variables can also be set via the "AE_" prefix, that is, instead of
		1196	setting "PERL_ANYEVENT_VERBOSE" you can also set "AE_VERBOSE". In case
		1197	there is a clash btween anyevent and another program that uses
		1198	"AE_something" you can set the corresponding "PERL_ANYEVENT_something"
		1199	variable to the empty string, as those variables take precedence.
		1200
		1201	When AnyEvent is first loaded, it copies all "AE_xxx" env variables to
		1202	their "PERL_ANYEVENT_xxx" counterpart unless that variable already
		1203	exists. If taint mode is on, then AnyEvent will remove all environment
		1204	variables starting with "PERL_ANYEVENT_" from %ENV (or replace them with
		1205	"undef" or the empty string, if the corresaponding "AE_" variable is
		1206	set).
		1207
		1208	The exact algorithm is currently:
		1209
		1210	1. if taint mode enabled, delete all PERL_ANYEVENT_xyz variables from %ENV
		1211	2. copy over AE_xyz to PERL_ANYEVENT_xyz unless the latter alraedy exists
		1212	3. if taint mode enabled, set all PERL_ANYEVENT_xyz variables to undef.
		1213
		1214	This ensures that child processes will not see the "AE_" variables.
		1215
		1216	The following environment variables are currently known to AnyEvent:
1105		1217
1106	"PERL_ANYEVENT_VERBOSE"	1218	"PERL_ANYEVENT_VERBOSE"
1107	By default, AnyEvent will be completely silent except in fatal	1219	By default, AnyEvent will log messages with loglevel 4 ("error") or
1108	conditions. You can set this environment variable to make AnyEvent	1220	higher (see AnyEvent::Log). You can set this environment variable to
1109	more talkative.	1221	a numerical loglevel to make AnyEvent more (or less) talkative.
1110		1222
		1223	If you want to do more than just set the global logging level you
		1224	should have a look at "PERL_ANYEVENT_LOG", which allows much more
		1225	complex specifications.
		1226
		1227	When set to 0 ("off"), then no messages whatsoever will be logged
		1228	with everything else at defaults.
		1229
1111	When set to 1 or higher, causes AnyEvent to warn about unexpected	1230	When set to 5 or higher ("warn"), AnyEvent warns about unexpected
1112	conditions, such as not being able to load the event model specified	1231	conditions, such as not being able to load the event model specified
1113	by "PERL_ANYEVENT_MODEL".	1232	by "PERL_ANYEVENT_MODEL", or a guard callback throwing an exception
		1233	- this is the minimum recommended level for use during development.
1114		1234
1115	When set to 2 or higher, cause AnyEvent to report to STDERR which	1235	When set to 7 or higher (info), AnyEvent reports which event model
1116	event model it chooses.	1236	it chooses.
1117		1237
1118	When set to 8 or higher, then AnyEvent will report extra information	1238	When set to 8 or higher (debug), then AnyEvent will report extra
1119	on which optional modules it loads and how it implements certain	1239	information on which optional modules it loads and how it implements
1120	features.	1240	certain features.
		1241
		1242	"PERL_ANYEVENT_LOG"
		1243	Accepts rather complex logging specifications. For example, you
		1244	could log all "debug" messages of some module to stderr, warnings
		1245	and above to stderr, and errors and above to syslog, with:
		1246
		1247	PERL_ANYEVENT_LOG=Some::Module=debug,+log:filter=warn,+%syslog:%syslog=error,syslog
		1248
		1249	For the rather extensive details, see AnyEvent::Log.
		1250
		1251	This variable is evaluated when AnyEvent (or AnyEvent::Log) is
		1252	loaded, so will take effect even before AnyEvent has initialised
		1253	itself.
		1254
		1255	Note that specifying this environment variable causes the
		1256	AnyEvent::Log module to be loaded, while "PERL_ANYEVENT_VERBOSE"
		1257	does not, so only using the latter saves a few hundred kB of memory
		1258	unless a module explicitly needs the extra features of
		1259	AnyEvent::Log.
1121		1260
1122	"PERL_ANYEVENT_STRICT"	1261	"PERL_ANYEVENT_STRICT"
1123	AnyEvent does not do much argument checking by default, as thorough	1262	AnyEvent does not do much argument checking by default, as thorough
1124	argument checking is very costly. Setting this variable to a true	1263	argument checking is very costly. Setting this variable to a true
1125	value will cause AnyEvent to load "AnyEvent::Strict" and then to	1264	value will cause AnyEvent to load "AnyEvent::Strict" and then to
1126	thoroughly check the arguments passed to most method calls. If it	1265	thoroughly check the arguments passed to most method calls. If it
1127	finds any problems, it will croak.	1266	finds any problems, it will croak.
1128		1267
1129	In other words, enables "strict" mode.	1268	In other words, enables "strict" mode.
1130		1269
1131	Unlike "use strict" (or it's modern cousin, "use common::sense", it	1270	Unlike "use strict" (or its modern cousin, "use common::sense", it
1132	is definitely recommended to keep it off in production. Keeping	1271	is definitely recommended to keep it off in production. Keeping
1133	"PERL_ANYEVENT_STRICT=1" in your environment while developing	1272	"PERL_ANYEVENT_STRICT=1" in your environment while developing
1134	programs can be very useful, however.	1273	programs can be very useful, however.
1135		1274
		1275	"PERL_ANYEVENT_DEBUG_SHELL"
		1276	If this env variable is nonempty, then its contents will be
		1277	interpreted by "AnyEvent::Socket::parse_hostport" and
		1278	"AnyEvent::Debug::shell" (after replacing every occurance of $$ by
		1279	the process pid). The shell object is saved in
		1280	$AnyEvent::Debug::SHELL.
		1281
		1282	This happens when the first watcher is created.
		1283
		1284	For example, to bind a debug shell on a unix domain socket in
		1285	/tmp/debug<pid>.sock, you could use this:
		1286
		1287	PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog
		1288	# connect with e.g.: socat readline /tmp/debug123.sock
		1289
		1290	Or to bind to tcp port 4545 on localhost:
		1291
		1292	PERL_ANYEVENT_DEBUG_SHELL=127.0.0.1:4545 perlprog
		1293	# connect with e.g.: telnet localhost 4545
		1294
		1295	Note that creating sockets in /tmp or on localhost is very unsafe on
		1296	multiuser systems.
		1297
		1298	"PERL_ANYEVENT_DEBUG_WRAP"
		1299	Can be set to 0, 1 or 2 and enables wrapping of all watchers for
		1300	debugging purposes. See "AnyEvent::Debug::wrap" for details.
		1301
1136	"PERL_ANYEVENT_MODEL"	1302	"PERL_ANYEVENT_MODEL"
1137	This can be used to specify the event model to be used by AnyEvent,	1303	This can be used to specify the event model to be used by AnyEvent,
1138	before auto detection and -probing kicks in. It must be a string	1304	before auto detection and -probing kicks in.
1139	consisting entirely of ASCII letters. The string "AnyEvent::Impl::"	1305
1140	gets prepended and the resulting module name is loaded and if the	1306	It normally is a string consisting entirely of ASCII letters (e.g.
1141	load was successful, used as event model. If it fails to load	1307	"EV" or "IOAsync"). The string "AnyEvent::Impl::" gets prepended and
		1308	the resulting module name is loaded and - if the load was successful
		1309	- used as event model backend. If it fails to load then AnyEvent
1142	AnyEvent will proceed with auto detection and -probing.	1310	will proceed with auto detection and -probing.
1143		1311
1144	This functionality might change in future versions.	1312	If the string ends with "::" instead (e.g. "AnyEvent::Impl::EV::")
		1313	then nothing gets prepended and the module name is used as-is (hint:
		1314	"::" at the end of a string designates a module name and quotes it
		1315	appropriately).
1145		1316
1146	For example, to force the pure perl model (AnyEvent::Impl::Perl) you	1317	For example, to force the pure perl model (AnyEvent::Loop::Perl) you
1147	could start your program like this:	1318	could start your program like this:
1148		1319
1149	PERL_ANYEVENT_MODEL=Perl perl ...	1320	PERL_ANYEVENT_MODEL=Perl perl ...
		1321
		1322	"PERL_ANYEVENT_IO_MODEL"
		1323	The current file I/O model - see AnyEvent::IO for more info.
		1324
		1325	At the moment, only "Perl" (small, pure-perl, synchronous) and
		1326	"IOAIO" (truly asynchronous) are supported. The default is "IOAIO"
		1327	if AnyEvent::AIO can be loaded, otherwise it is "Perl".
1150		1328
1151	"PERL_ANYEVENT_PROTOCOLS"	1329	"PERL_ANYEVENT_PROTOCOLS"
1152	Used by both AnyEvent::DNS and AnyEvent::Socket to determine	1330	Used by both AnyEvent::DNS and AnyEvent::Socket to determine
1153	preferences for IPv4 or IPv6. The default is unspecified (and might	1331	preferences for IPv4 or IPv6. The default is unspecified (and might
1154	change, or be the result of auto probing).	1332	change, or be the result of auto probing).
…		…
1168	"PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to	1346	"PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to
1169	resolve or contact IPv6 addresses.	1347	resolve or contact IPv6 addresses.
1170	"PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4" support either IPv4 or IPv6, but	1348	"PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4" support either IPv4 or IPv6, but
1171	prefer IPv6 over IPv4.	1349	prefer IPv6 over IPv4.
1172		1350
		1351	"PERL_ANYEVENT_HOSTS"
		1352	This variable, if specified, overrides the /etc/hosts file used by
		1353	AnyEvent::Socket"::resolve_sockaddr", i.e. hosts aliases will be
		1354	read from that file instead.
		1355
1173	"PERL_ANYEVENT_EDNS0"	1356	"PERL_ANYEVENT_EDNS0"
1174	Used by AnyEvent::DNS to decide whether to use the EDNS0 extension	1357	Used by AnyEvent::DNS to decide whether to use the EDNS0 extension
1175	for DNS. This extension is generally useful to reduce DNS traffic,	1358	for DNS. This extension is generally useful to reduce DNS traffic,
1176	but some (broken) firewalls drop such DNS packets, which is why it	1359	especially when DNSSEC is involved, but some (broken) firewalls drop
1177	is off by default.	1360	such DNS packets, which is why it is off by default.
1178		1361
1179	Setting this variable to 1 will cause AnyEvent::DNS to announce	1362	Setting this variable to 1 will cause AnyEvent::DNS to announce
1180	EDNS0 in its DNS requests.	1363	EDNS0 in its DNS requests.
1181		1364
1182	"PERL_ANYEVENT_MAX_FORKS"	1365	"PERL_ANYEVENT_MAX_FORKS"
…		…
1186	"PERL_ANYEVENT_MAX_OUTSTANDING_DNS"	1369	"PERL_ANYEVENT_MAX_OUTSTANDING_DNS"
1187	The default value for the "max_outstanding" parameter for the	1370	The default value for the "max_outstanding" parameter for the
1188	default DNS resolver - this is the maximum number of parallel DNS	1371	default DNS resolver - this is the maximum number of parallel DNS
1189	requests that are sent to the DNS server.	1372	requests that are sent to the DNS server.
1190		1373
		1374	"PERL_ANYEVENT_MAX_SIGNAL_LATENCY"
		1375	Perl has inherently racy signal handling (you can basically choose
		1376	between losing signals and memory corruption) - pure perl event
		1377	loops (including "AnyEvent::Loop", when "Async::Interrupt" isn't
		1378	available) therefore have to poll regularly to avoid losing signals.
		1379
		1380	Some event loops are racy, but don't poll regularly, and some event
		1381	loops are written in C but are still racy. For those event loops,
		1382	AnyEvent installs a timer that regularly wakes up the event loop.
		1383
		1384	By default, the interval for this timer is 10 seconds, but you can
		1385	override this delay with this environment variable (or by setting
		1386	the $AnyEvent::MAX_SIGNAL_LATENCY variable before creating signal
		1387	watchers).
		1388
		1389	Lower values increase CPU (and energy) usage, higher values can
		1390	introduce long delays when reaping children or waiting for signals.
		1391
		1392	The AnyEvent::Async module, if available, will be used to avoid this
		1393	polling (with most event loops).
		1394
1191	"PERL_ANYEVENT_RESOLV_CONF"	1395	"PERL_ANYEVENT_RESOLV_CONF"
1192	The file to use instead of /etc/resolv.conf (or OS-specific	1396	The absolute path to a resolv.conf-style file to use instead of
1193	configuration) in the default resolver. When set to the empty	1397	/etc/resolv.conf (or the OS-specific configuration) in the default
1194	string, no default config will be used.	1398	resolver, or the empty string to select the default configuration.
1195		1399
1196	"PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH".	1400	"PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH".
1197	When neither "ca_file" nor "ca_path" was specified during	1401	When neither "ca_file" nor "ca_path" was specified during
1198	AnyEvent::TLS context creation, and either of these environment	1402	AnyEvent::TLS context creation, and either of these environment
1199	variables exist, they will be used to specify CA certificate	1403	variables are nonempty, they will be used to specify CA certificate
1200	locations instead of a system-dependent default.	1404	locations instead of a system-dependent default.
1201		1405
1202	"PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT"	1406	"PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT"
1203	When these are set to 1, then the respective modules are not loaded.	1407	When these are set to 1, then the respective modules are not loaded.
1204	Mostly good for testing AnyEvent itself.	1408	Mostly good for testing AnyEvent itself.
…		…
1348		1552
1349	The actual code goes further and collects all errors ("die"s,	1553	The actual code goes further and collects all errors ("die"s,
1350	exceptions) that occurred during request processing. The "result" method	1554	exceptions) that occurred during request processing. The "result" method
1351	detects whether an exception as thrown (it is stored inside the $txn	1555	detects whether an exception as thrown (it is stored inside the $txn
1352	object) and just throws the exception, which means connection errors and	1556	object) and just throws the exception, which means connection errors and
1353	other problems get reported tot he code that tries to use the result,	1557	other problems get reported to the code that tries to use the result,
1354	not in a random callback.	1558	not in a random callback.
1355		1559
1356	All of this enables the following usage styles:	1560	All of this enables the following usage styles:
1357		1561
1358	1. Blocking:	1562	1. Blocking:
…		…
1524	when used without AnyEvent), but most event loops have acceptable	1728	when used without AnyEvent), but most event loops have acceptable
1525	performance with or without AnyEvent.	1729	performance with or without AnyEvent.
1526		1730
1527	* The overhead AnyEvent adds is usually much smaller than the overhead	1731	* The overhead AnyEvent adds is usually much smaller than the overhead
1528	of the actual event loop, only with extremely fast event loops such	1732	of the actual event loop, only with extremely fast event loops such
1529	as EV adds AnyEvent significant overhead.	1733	as EV does AnyEvent add significant overhead.
1530		1734
1531	* You should avoid POE like the plague if you want performance or	1735	* You should avoid POE like the plague if you want performance or
1532	reasonable memory usage.	1736	reasonable memory usage.
1533		1737
1534	BENCHMARKING THE LARGE SERVER CASE	1738	BENCHMARKING THE LARGE SERVER CASE
…		…
1732		1936
1733	Feel free to install your own handler, or reset it to defaults.	1937	Feel free to install your own handler, or reset it to defaults.
1734		1938
1735	RECOMMENDED/OPTIONAL MODULES	1939	RECOMMENDED/OPTIONAL MODULES
1736	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and	1940	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
1737	it's built-in modules) are required to use it.	1941	its built-in modules) are required to use it.
1738		1942
1739	That does not mean that AnyEvent won't take advantage of some additional	1943	That does not mean that AnyEvent won't take advantage of some additional
1740	modules if they are installed.	1944	modules if they are installed.
1741		1945
1742	This section explains which additional modules will be used, and how	1946	This section explains which additional modules will be used, and how
…		…
1771	clock is available, can take avdantage of advanced kernel interfaces	1975	clock is available, can take avdantage of advanced kernel interfaces
1772	such as "epoll" and "kqueue", and is the fastest backend by far.	1976	such as "epoll" and "kqueue", and is the fastest backend by far.
1773	You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and	1977	You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and
1774	Glib::EV).	1978	Glib::EV).
1775		1979
		1980	If you only use backends that rely on another event loop (e.g.
		1981	"Tk"), then this module will do nothing for you.
		1982
1776	Guard	1983	Guard
1777	The guard module, when used, will be used to implement	1984	The guard module, when used, will be used to implement
1778	"AnyEvent::Util::guard". This speeds up guards considerably (and	1985	"AnyEvent::Util::guard". This speeds up guards considerably (and
1779	uses a lot less memory), but otherwise doesn't affect guard	1986	uses a lot less memory), but otherwise doesn't affect guard
1780	operation much. It is purely used for performance.	1987	operation much. It is purely used for performance.
1781		1988
1782	JSON and JSON::XS	1989	JSON and JSON::XS
1783	One of these modules is required when you want to read or write JSON	1990	One of these modules is required when you want to read or write JSON
1784	data via AnyEvent::Handle. It is also written in pure-perl, but can	1991	data via AnyEvent::Handle. JSON is also written in pure-perl, but
1785	take advantage of the ultra-high-speed JSON::XS module when it is	1992	can take advantage of the ultra-high-speed JSON::XS module when it
1786	installed.	1993	is installed.
1787
1788	In fact, AnyEvent::Handle will use JSON::XS by default if it is
1789	installed.
1790		1994
1791	Net::SSLeay	1995	Net::SSLeay
1792	Implementing TLS/SSL in Perl is certainly interesting, but not very	1996	Implementing TLS/SSL in Perl is certainly interesting, but not very
1793	worthwhile: If this module is installed, then AnyEvent::Handle (with	1997	worthwhile: If this module is installed, then AnyEvent::Handle (with
1794	the help of AnyEvent::TLS), gains the ability to do TLS/SSL.	1998	the help of AnyEvent::TLS), gains the ability to do TLS/SSL.
1795		1999
1796	Time::HiRes	2000	Time::HiRes
1797	This module is part of perl since release 5.008. It will be used	2001	This module is part of perl since release 5.008. It will be used
1798	when the chosen event library does not come with a timing source on	2002	when the chosen event library does not come with a timing source of
1799	it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will	2003	its own. The pure-perl event loop (AnyEvent::Loop) will additionally
1800	additionally use it to try to use a monotonic clock for timing	2004	load it to try to use a monotonic clock for timing stability.
1801	stability.
1802		2005
1803	FORK	2006	FORK
1804	Most event libraries are not fork-safe. The ones who are usually are	2007	Most event libraries are not fork-safe. The ones who are usually are
1805	because they rely on inefficient but fork-safe "select" or "poll" calls.	2008	because they rely on inefficient but fork-safe "select" or "poll" calls
1806	Only EV is fully fork-aware.	2009	- higher performance APIs such as BSD's kqueue or the dreaded Linux
		2010	epoll are usually badly thought-out hacks that are incompatible with
		2011	fork in one way or another. Only EV is fully fork-aware and ensures that
		2012	you continue event-processing in both parent and child (or both, if you
		2013	know what you are doing).
1807		2014
1808	This means that, in general, you cannot fork and do event processing in	2015	This means that, in general, you cannot fork and do event processing in
1809	the child if a watcher was created before the fork (which in turn	2016	the child if the event library was initialised before the fork (which
1810	initialises the event library).	2017	usually happens when the first AnyEvent watcher is created, or the
		2018	library is loaded).
1811		2019
1812	If you have to fork, you must either do so before creating your first	2020	If you have to fork, you must either do so before creating your first
1813	watcher OR you must not use AnyEvent at all in the child OR you must do	2021	watcher OR you must not use AnyEvent at all in the child OR you must do
1814	something completely out of the scope of AnyEvent.	2022	something completely out of the scope of AnyEvent.
1815		2023
1816	The problem of doing event processing in the parent and the child is	2024	The problem of doing event processing in the parent and the child is
1817	much more complicated: even for backends that are fork-aware or	2025	much more complicated: even for backends that are fork-aware or
1818	fork-safe, their behaviour is not usually what you want: fork clones all	2026	fork-safe, their behaviour is not usually what you want: fork clones all
1819	watchers, that means all timers, I/O watchers etc. are active in both	2027	watchers, that means all timers, I/O watchers etc. are active in both
1820	parent and child, which is almost never what you want.	2028	parent and child, which is almost never what you want. USing "exec" to
		2029	start worker children from some kind of manage rprocess is usually
		2030	preferred, because it is much easier and cleaner, at the expense of
		2031	having to have another binary.
1821		2032
1822	SECURITY CONSIDERATIONS	2033	SECURITY CONSIDERATIONS
1823	AnyEvent can be forced to load any event model via	2034	AnyEvent can be forced to load any event model via
1824	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used	2035	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used
1825	to execute arbitrary code or directly gain access, it can easily be used	2036	to execute arbitrary code or directly gain access, it can easily be used
…		…
1849	5.10 and check wether the leaks still show up. (Perl 5.10.0 has other	2060	5.10 and check wether the leaks still show up. (Perl 5.10.0 has other
1850	annoying memleaks, such as leaking on "map" and "grep" but it is usually	2061	annoying memleaks, such as leaking on "map" and "grep" but it is usually
1851	not as pronounced).	2062	not as pronounced).
1852		2063
1853	SEE ALSO	2064	SEE ALSO
1854	Utility functions: AnyEvent::Util.	2065	Tutorial/Introduction: AnyEvent::Intro.
1855		2066
1856	Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,	2067	FAQ: AnyEvent::FAQ.
1857	Event::Lib, Qt, POE.	2068
		2069	Utility functions: AnyEvent::Util (misc. grab-bag), AnyEvent::Log
		2070	(simply logging).
		2071
		2072	Development/Debugging: AnyEvent::Strict (stricter checking),
		2073	AnyEvent::Debug (interactive shell, watcher tracing).
		2074
		2075	Supported event modules: AnyEvent::Loop, EV, EV::Glib, Glib::EV, Event,
		2076	Glib::Event, Glib, Tk, Event::Lib, Qt, POE, FLTK.
1858		2077
1859	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,	2078	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,
1860	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,	2079	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,
1861	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,	2080	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,
1862	AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi.	2081	AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi, AnyEvent::Impl::FLTK.
1863		2082
1864	Non-blocking file handles, sockets, TCP clients and servers:	2083	Non-blocking handles, pipes, stream sockets, TCP clients and servers:
1865	AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.	2084	AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.
1866		2085
		2086	Asynchronous File I/O: AnyEvent::IO.
		2087
1867	Asynchronous DNS: AnyEvent::DNS.	2088	Asynchronous DNS: AnyEvent::DNS.
1868		2089
1869	Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event,	2090	Thread support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event.
1870		2091
1871	Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP,	2092	Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::IRC,
1872	AnyEvent::HTTP.	2093	AnyEvent::HTTP.
1873		2094
1874	AUTHOR	2095	AUTHOR
1875	Marc Lehmann <schmorp@schmorp.de>	2096	Marc Lehmann <schmorp@schmorp.de>
1876	http://home.schmorp.de/	2097	http://anyevent.schmorp.de
1877		2098

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Comparing AnyEvent/README (file contents):
Revision 1.58 by root, Sun Dec 20 22:49:52 2009 UTC vs.
Revision 1.70 by root, Fri Apr 13 09:57:41 2012 UTC