[ViewVC] Diff of: cvs/AnyEvent/README

Comparing AnyEvent/README (file contents):
Revision 1.54 by root, Tue Sep 1 18:27:46 2009 UTC vs.
Revision 1.65 by root, Sat Aug 13 22:44:05 2011 UTC

…		…
5	Qt and POE are various supported event loops/environments.	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
…		…
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
356	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
357	the event loop's idea of "current time".	361	the event loop's idea of "current time".
		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).
358		370
359	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.
360		372
361	SIGNAL WATCHERS	373	SIGNAL WATCHERS
362	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);	374	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
…		…
384		396
385	Example: exit on SIGINT	397	Example: exit on SIGINT
386		398
387	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	399	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
388		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
389	Signal Races, Delays and Workarounds	416	Signal Races, Delays and Workarounds
390	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
391	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
392	race-free signal handling in perl, requiring C libraries for this.	419	race-free signal handling in perl, requiring C libraries for this.
393	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
394	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 specified
395	in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable	422	in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable
396	can be changed only before the first signal watcher is created, and	423	can be changed only before the first signal watcher is created, and
397	should be left alone otherwise. This variable determines how often	424	should be left alone otherwise. This variable determines how often
398	AnyEvent polls for signals (in case a wake-up was missed). Higher values	425	AnyEvent polls for signals (in case a wake-up was missed). Higher values
…		…
400	saving.	427	saving.
401		428
402	All these problems can be avoided by installing the optional	429	All these problems can be avoided by installing the optional
403	Async::Interrupt module, which works with most event loops. It will not	430	Async::Interrupt module, which works with most event loops. It will not
404	work with inherently broken event loops such as Event or Event::Lib (and	431	work with inherently broken event loops such as Event or Event::Lib (and
405	not with POE currently, as POE does it's own workaround with one-second	432	not with POE currently, as POE does its own workaround with one-second
406	latency). For those, you just have to suffer the delays.	433	latency). For those, you just have to suffer the delays.
407		434
408	CHILD PROCESS WATCHERS	435	CHILD PROCESS WATCHERS
409	$w = AnyEvent->child (pid => <process id>, cb => <callback>);	436	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
410		437
411	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.
412		439
413	The child process is specified by the "pid" argument (one some backends,	440	The child process is specified by the "pid" argument (on some backends,
414	using 0 watches for any child process exit, on others this will croak).	441	using 0 watches for any child process exit, on others this will croak).
415	The watcher will be triggered only when the child process has finished	442	The watcher will be triggered only when the child process has finished
416	and an exit status is available, not on any trace events	443	and an exit status is available, not on any trace events
417	(stopped/continued).	444	(stopped/continued).
418		445
…		…
439	This means you cannot create a child watcher as the very first thing in	466	This means you cannot create a child watcher as the very first thing in
440	an AnyEvent program, you have to create at least one watcher before	467	an AnyEvent program, you have to create at least one watcher before
441	you "fork" the child (alternatively, you can call "AnyEvent::detect").	468	you "fork" the child (alternatively, you can call "AnyEvent::detect").
442		469
443	As most event loops do not support waiting for child events, they will	470	As most event loops do not support waiting for child events, they will
444	be emulated by AnyEvent in most cases, in which the latency and race	471	be emulated by AnyEvent in most cases, in which case the latency and
445	problems mentioned in the description of signal watchers apply.	472	race problems mentioned in the description of signal watchers apply.
446		473
447	Example: fork a process and wait for it	474	Example: fork a process and wait for it
448		475
449	my $done = AnyEvent->condvar;	476	my $done = AnyEvent->condvar;
450		477
…		…
463	$done->recv;	490	$done->recv;
464		491
465	IDLE WATCHERS	492	IDLE WATCHERS
466	$w = AnyEvent->idle (cb => <callback>);	493	$w = AnyEvent->idle (cb => <callback>);
467		494
468	Sometimes there is a need to do something, but it is not so important to	495	This will repeatedly invoke the callback after the process becomes idle,
469	do it instantly, but only when there is nothing better to do. This	496	until either the watcher is destroyed or new events have been detected.
470	"nothing better to do" is usually defined to be "no other events need
471	attention by the event loop".
472		497
473	Idle watchers ideally get invoked when the event loop has nothing better	498	Idle watchers are useful when there is a need to do something, but it is
474	to do, just before it would block the process to wait for new events.	499	not so important (or wise) to do it instantly. The callback will be
475	Instead of blocking, the idle watcher is invoked.	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.
476		506
477	Most event loops unfortunately do not really support idle watchers (only	507	Unfortunately, most event loops do not really support idle watchers
478	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,
479	will simply call the callback "from time to time".	509	AnyEvent will simply call the callback "from time to time".
480		510
481	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
482	is otherwise idle:	512	is otherwise idle:
483		513
484	my @lines; # read data	514	my @lines; # read data
…		…
510		540
511	AnyEvent is slightly different: it expects somebody else to run the	541	AnyEvent is slightly different: it expects somebody else to run the
512	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
513	user).	543	user).
514		544
515	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
516	because they represent a condition that must become true.	546	they represent a condition that must become true.
517		547
518	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.
519		549
520	Condition variables can be created by calling the "AnyEvent->condvar"	550	Condition variables can be created by calling the "AnyEvent->condvar"
521	method, usually without arguments. The only argument pair allowed is	551	method, usually without arguments. The only argument pair allowed is
…		…
526	After creation, the condition variable is "false" until it becomes	556	After creation, the condition variable is "false" until it becomes
527	"true" by calling the "send" method (or calling the condition variable	557	"true" by calling the "send" method (or calling the condition variable
528	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
529	the "->send" method).	559	the "->send" method).
530		560
531	Condition variables are similar to callbacks, except that you can	561	Since condition variables are the most complex part of the AnyEvent API,
532	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
533	in time where multiple outstanding events have been processed. And yet	563	you can connect to:
534	another way to call them is transactions - each condition variable can	564
535	be used to represent a transaction, which finishes at some point and	565	* Condition variables are like callbacks - you can call them (and pass
536	delivers a result. And yet some people know them as "futures" - a	566	them instead of callbacks). Unlike callbacks however, you can also
537	promise to compute/deliver something that you can wait for.	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.
538		582
539	Condition variables are very useful to signal that something has	583	Condition variables are very useful to signal that something has
540	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
541	requests, then a condition variable would be the ideal candidate to	585	requests, then a condition variable would be the ideal candidate to
542	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
…		…
555		599
556	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
557	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
558	(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
559	AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call	603	AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call
560	it's "new" method in your own "new" method.	604	its "new" method in your own "new" method.
561		605
562	There are two "sides" to a condition variable - the "producer side"	606	There are two "sides" to a condition variable - the "producer side"
563	which eventually calls "-> send", and the "consumer side", which waits	607	which eventually calls "-> send", and the "consumer side", which waits
564	for the send to occur.	608	for the send to occur.
565		609
566	Example: wait for a timer.	610	Example: wait for a timer.
567		611
568	# wait till the result is ready	612	# condition: "wait till the timer is fired"
569	my $result_ready = AnyEvent->condvar;	613	my $timer_fired = AnyEvent->condvar;
570		614
571	# do something such as adding a timer	615	# create the timer - we could wait for, say
572	# or socket watcher the calls $result_ready->send	616	# a handle becomign ready, or even an
573	# when the "result" is ready.	617	# AnyEvent::HTTP request to finish, but
574	# in this case, we simply use a timer:	618	# in this case, we simply use a timer:
575	my $w = AnyEvent->timer (	619	my $w = AnyEvent->timer (
576	after => 1,	620	after => 1,
577	cb => sub { $result_ready->send },	621	cb => sub { $timer_fired->send },
578	);	622	);
579		623
580	# this "blocks" (while handling events) till the callback	624	# this "blocks" (while handling events) till the callback
581	# calls ->send	625	# calls ->send
582	$result_ready->recv;	626	$timer_fired->recv;
583		627
584	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
585	variables are also callable directly.	629	variables are also callable directly.
586		630
587	my $done = AnyEvent->condvar;	631	my $done = AnyEvent->condvar;
…		…
625	Condition variables are overloaded so one can call them directly (as	669	Condition variables are overloaded so one can call them directly (as
626	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
627	calling "send".	671	calling "send".
628		672
629	$cv->croak ($error)	673	$cv->croak ($error)
630	Similar to send, but causes all call's to "->recv" to invoke	674	Similar to send, but causes all calls to "->recv" to invoke
631	"Carp::croak" with the given error message/object/scalar.	675	"Carp::croak" with the given error message/object/scalar.
632		676
633	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
634	user/consumer. Doing it this way instead of calling "croak" directly	678	user/consumer. Doing it this way instead of calling "croak" directly
635	delays the error detetcion, but has the overwhelmign advantage that	679	delays the error detection, but has the overwhelming advantage that
636	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,
637	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
638	code causing the problem.	682	code causing the problem.
639		683
640	$cv->begin ([group callback])	684	$cv->begin ([group callback])
641	$cv->end	685	$cv->end
642	These two methods can be used to combine many transactions/events	686	These two methods can be used to combine many transactions/events
…		…
679	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
680	"end" before sending.	724	"end" before sending.
681		725
682	The ping example mentioned above is slightly more complicated, as	726	The ping example mentioned above is slightly more complicated, as
683	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
684	that are begung can potentially be zero:	728	that are begun can potentially be zero:
685		729
686	my $cv = AnyEvent->condvar;	730	my $cv = AnyEvent->condvar;
687		731
688	my %result;	732	my %result;
689	$cv->begin (sub { shift->send (\%result) });	733	$cv->begin (sub { shift->send (\%result) });
…		…
710	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
711	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
712	(the loop doesn't execute once).	756	(the loop doesn't execute once).
713		757
714	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
715	potentially none) subrequests: use an outer "begin"/"end" pair to	759	potentially zero) subrequests: use an outer "begin"/"end" pair to
716	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,
717	for each subrequest you start, call "begin" and for each subrequest	761	for each subrequest you start, call "begin" and for each subrequest
718	you finish, call "end".	762	you finish, call "end".
719		763
720	METHODS FOR CONSUMERS	764	METHODS FOR CONSUMERS
721	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
722	awaits the condition.	766	awaits the condition.
723		767
724	$cv->recv	768	$cv->recv
725	Wait (blocking if necessary) until the "->send" or "->croak" methods	769	Wait (blocking if necessary) until the "->send" or "->croak" methods
726	have been called on c<$cv>, while servicing other watchers normally.	770	have been called on $cv, while servicing other watchers normally.
727		771
728	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
729	but will return immediately.	773	but will return immediately.
730		774
731	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
…		…
748	example, by coupling condition variables with some kind of request	792	example, by coupling condition variables with some kind of request
749	results and supporting callbacks so the caller knows that getting	793	results and supporting callbacks so the caller knows that getting
750	the result will not block, while still supporting blocking waits if	794	the result will not block, while still supporting blocking waits if
751	the caller so desires).	795	the caller so desires).
752		796
753	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
754	only calling "->recv" from within that callback (or at a later	798	only calling "->recv" from within that callback (or at a later
755	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
756	blocking waits otherwise.	800	blocking waits otherwise.
757		801
758	$bool = $cv->ready	802	$bool = $cv->ready
…		…
761		805
762	$cb = $cv->cb ($cb->($cv))	806	$cb = $cv->cb ($cb->($cv))
763	This is a mutator function that returns the callback set and	807	This is a mutator function that returns the callback set and
764	optionally replaces it before doing so.	808	optionally replaces it before doing so.
765		809
766	The callback will be called when the condition becomes (or already	810	The callback will be called when the condition becomes "true", i.e.
767	was) "true", i.e. when "send" or "croak" are called (or were	811	when "send" or "croak" are called, with the only argument being the
768	called), with the only argument being the condition variable itself.	812	condition variable itself. If the condition is already true, the
769	Calling "recv" inside the callback or at any later time is	813	callback is called immediately when it is set. Calling "recv" inside
770	guaranteed not to block.	814	the callback or at any later time is guaranteed not to block.
771		815
772	SUPPORTED EVENT LOOPS/BACKENDS	816	SUPPORTED EVENT LOOPS/BACKENDS
773	The available backend classes are (every class has its own manpage):	817	The available backend classes are (every class has its own manpage):
774		818
775	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.
…		…
777	use. If EV is not installed, then AnyEvent will fall back to its own	821	use. If EV is not installed, then AnyEvent will fall back to its own
778	pure-perl implementation, which is available everywhere as it comes	822	pure-perl implementation, which is available everywhere as it comes
779	with AnyEvent itself.	823	with AnyEvent itself.
780		824
781	AnyEvent::Impl::EV based on EV (interface to libev, best choice).	825	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
782	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.	826	AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
783		827
784	Backends that are transparently being picked up when they are used.	828	Backends that are transparently being picked up when they are used.
785	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
786	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
787	is using them. This means that AnyEvent will automatically pick the	831	using them. This means that AnyEvent will automatically pick the
788	right backend when the main program loads an event module before	832	right backend when the main program loads an event module before
789	anything starts to create watchers. Nothing special needs to be done	833	anything starts to create watchers. Nothing special needs to be done
790	by the main program.	834	by the main program.
791		835
792	AnyEvent::Impl::Event based on Event, very stable, few glitches.	836	AnyEvent::Impl::Event based on Event, very stable, few glitches.
793	AnyEvent::Impl::Glib based on Glib, slow but very stable.	837	AnyEvent::Impl::Glib based on Glib, slow but very stable.
794	AnyEvent::Impl::Tk based on Tk, very broken.	838	AnyEvent::Impl::Tk based on Tk, very broken.
795	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	839	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
796	AnyEvent::Impl::POE based on POE, very slow, some limitations.	840	AnyEvent::Impl::POE based on POE, very slow, some limitations.
797	AnyEvent::Impl::Irssi used when running within irssi.	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.
		844	AnyEvent::Impl::FLTK2 based on FLTK (fltk 2 binding).
798		845
799	Backends with special needs.	846	Backends with special needs.
800	Qt requires the Qt::Application to be instantiated first, but will	847	Qt requires the Qt::Application to be instantiated first, but will
801	otherwise be picked up automatically. As long as the main program	848	otherwise be picked up automatically. As long as the main program
802	instantiates the application before any AnyEvent watchers are	849	instantiates the application before any AnyEvent watchers are
803	created, everything should just work.	850	created, everything should just work.
804		851
805	AnyEvent::Impl::Qt based on Qt.	852	AnyEvent::Impl::Qt based on Qt.
806		853
807	Support for IO::Async can only be partial, as it is too broken and
808	architecturally limited to even support the AnyEvent API. It also is
809	the only event loop that needs the loop to be set explicitly, so it
810	can only be used by a main program knowing about AnyEvent. See
811	AnyEvent::Impl::Async for the gory details.
812
813	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
814
815	Event loops that are indirectly supported via other backends.	854	Event loops that are indirectly supported via other backends.
816	Some event loops can be supported via other modules:	855	Some event loops can be supported via other modules:
817		856
818	There is no direct support for WxWidgets (Wx) or Prima.	857	There is no direct support for WxWidgets (Wx) or Prima.
819		858
…		…
837	Contains "undef" until the first watcher is being created, before	876	Contains "undef" until the first watcher is being created, before
838	the backend has been autodetected.	877	the backend has been autodetected.
839		878
840	Afterwards it contains the event model that is being used, which is	879	Afterwards it contains the event model that is being used, which is
841	the name of the Perl class implementing the model. This class is	880	the name of the Perl class implementing the model. This class is
842	usually one of the "AnyEvent::Impl:xxx" modules, but can be any	881	usually one of the "AnyEvent::Impl::xxx" modules, but can be any
843	other class in the case AnyEvent has been extended at runtime (e.g.	882	other class in the case AnyEvent has been extended at runtime (e.g.
844	in rxvt-unicode it will be "urxvt::anyevent").	883	in rxvt-unicode it will be "urxvt::anyevent").
845		884
846	AnyEvent::detect	885	AnyEvent::detect
847	Returns $AnyEvent::MODEL, forcing autodetection of the event model	886	Returns $AnyEvent::MODEL, forcing autodetection of the event model
848	if necessary. You should only call this function right before you	887	if necessary. You should only call this function right before you
849	would have created an AnyEvent watcher anyway, that is, as late as	888	would have created an AnyEvent watcher anyway, that is, as late as
850	possible at runtime, and not e.g. while initialising of your module.	889	possible at runtime, and not e.g. during initialisation of your
		890	module.
		891
		892	The effect of calling this function is as if a watcher had been
		893	created (specifically, actions that happen "when the first watcher
		894	is created" happen when calling detetc as well).
851		895
852	If you need to do some initialisation before AnyEvent watchers are	896	If you need to do some initialisation before AnyEvent watchers are
853	created, use "post_detect".	897	created, use "post_detect".
854		898
855	$guard = AnyEvent::post_detect { BLOCK }	899	$guard = AnyEvent::post_detect { BLOCK }
856	Arranges for the code block to be executed as soon as the event	900	Arranges for the code block to be executed as soon as the event
857	model is autodetected (or immediately if this has already happened).	901	model is autodetected (or immediately if that has already happened).
858		902
859	The block will be executed after the actual backend has been	903	The block will be executed after the actual backend has been
860	detected ($AnyEvent::MODEL is set), but before any watchers have	904	detected ($AnyEvent::MODEL is set), but before any watchers have
861	been created, so it is possible to e.g. patch @AnyEvent::ISA or do	905	been created, so it is possible to e.g. patch @AnyEvent::ISA or do
862	other initialisations - see the sources of AnyEvent::Strict or	906	other initialisations - see the sources of AnyEvent::Strict or
…		…
871	object that automatically removes the callback again when it is	915	object that automatically removes the callback again when it is
872	destroyed (or "undef" when the hook was immediately executed). See	916	destroyed (or "undef" when the hook was immediately executed). See
873	AnyEvent::AIO for a case where this is useful.	917	AnyEvent::AIO for a case where this is useful.
874		918
875	Example: Create a watcher for the IO::AIO module and store it in	919	Example: Create a watcher for the IO::AIO module and store it in
876	$WATCHER. Only do so after the event loop is initialised, though.	920	$WATCHER, but do so only do so after the event loop is initialised.
877		921
878	our WATCHER;	922	our WATCHER;
879		923
880	my $guard = AnyEvent::post_detect {	924	my $guard = AnyEvent::post_detect {
881	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);	925	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
…		…
888		932
889	$WATCHER \|\|= $guard;	933	$WATCHER \|\|= $guard;
890		934
891	@AnyEvent::post_detect	935	@AnyEvent::post_detect
892	If there are any code references in this array (you can "push" to it	936	If there are any code references in this array (you can "push" to it
893	before or after loading AnyEvent), then they will called directly	937	before or after loading AnyEvent), then they will be called directly
894	after the event loop has been chosen.	938	after the event loop has been chosen.
895		939
896	You should check $AnyEvent::MODEL before adding to this array,	940	You should check $AnyEvent::MODEL before adding to this array,
897	though: if it is defined then the event loop has already been	941	though: if it is defined then the event loop has already been
898	detected, and the array will be ignored.	942	detected, and the array will be ignored.
899		943
900	Best use "AnyEvent::post_detect { BLOCK }" when your application	944	Best use "AnyEvent::post_detect { BLOCK }" when your application
901	allows it,as it takes care of these details.	945	allows it, as it takes care of these details.
902		946
903	This variable is mainly useful for modules that can do something	947	This variable is mainly useful for modules that can do something
904	useful when AnyEvent is used and thus want to know when it is	948	useful when AnyEvent is used and thus want to know when it is
905	initialised, but do not need to even load it by default. This array	949	initialised, but do not need to even load it by default. This array
906	provides the means to hook into AnyEvent passively, without loading	950	provides the means to hook into AnyEvent passively, without loading
907	it.	951	it.
908		952
		953	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		954	together, you could put this into Coro (this is the actual code used
		955	by Coro to accomplish this):
		956
		957	if (defined $AnyEvent::MODEL) {
		958	# AnyEvent already initialised, so load Coro::AnyEvent
		959	require Coro::AnyEvent;
		960	} else {
		961	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		962	# as soon as it is
		963	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		964	}
		965
		966	AnyEvent::postpone { BLOCK }
		967	Arranges for the block to be executed as soon as possible, but not
		968	before the call itself returns. In practise, the block will be
		969	executed just before the event loop polls for new events, or shortly
		970	afterwards.
		971
		972	This function never returns anything (to make the "return postpone {
		973	... }" idiom more useful.
		974
		975	To understand the usefulness of this function, consider a function
		976	that asynchronously does something for you and returns some
		977	transaction object or guard to let you cancel the operation. For
		978	example, "AnyEvent::Socket::tcp_connect":
		979
		980	# start a conenction attempt unless one is active
		981	$self->{connect_guard} \|\|= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
		982	delete $self->{connect_guard};
		983	...
		984	};
		985
		986	Imagine that this function could instantly call the callback, for
		987	example, because it detects an obvious error such as a negative port
		988	number. Invoking the callback before the function returns causes
		989	problems however: the callback will be called and will try to delete
		990	the guard object. But since the function hasn't returned yet, there
		991	is nothing to delete. When the function eventually returns it will
		992	assign the guard object to "$self->{connect_guard}", where it will
		993	likely never be deleted, so the program thinks it is still trying to
		994	connect.
		995
		996	This is where "AnyEvent::postpone" should be used. Instead of
		997	calling the callback directly on error:
		998
		999	$cb->(undef), return # signal error to callback, BAD!
		1000	if $some_error_condition;
		1001
		1002	It should use "postpone":
		1003
		1004	AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
		1005	if $some_error_condition;
		1006
909	WHAT TO DO IN A MODULE	1007	WHAT TO DO IN A MODULE
910	As a module author, you should "use AnyEvent" and call AnyEvent methods	1008	As a module author, you should "use AnyEvent" and call AnyEvent methods
911	freely, but you should not load a specific event module or rely on it.	1009	freely, but you should not load a specific event module or rely on it.
912		1010
913	Be careful when you create watchers in the module body - AnyEvent will	1011	Be careful when you create watchers in the module body - AnyEvent will
…		…
920	stall the whole program, and the whole point of using events is to stay	1018	stall the whole program, and the whole point of using events is to stay
921	interactive.	1019	interactive.
922		1020
923	It is fine, however, to call "->recv" when the user of your module	1021	It is fine, however, to call "->recv" when the user of your module
924	requests it (i.e. if you create a http request object ad have a method	1022	requests it (i.e. if you create a http request object ad have a method
925	called "results" that returns the results, it should call "->recv"	1023	called "results" that returns the results, it may call "->recv" freely,
926	freely, as the user of your module knows what she is doing. always).	1024	as the user of your module knows what she is doing. Always).
927		1025
928	WHAT TO DO IN THE MAIN PROGRAM	1026	WHAT TO DO IN THE MAIN PROGRAM
929	There will always be a single main program - the only place that should	1027	There will always be a single main program - the only place that should
930	dictate which event model to use.	1028	dictate which event model to use.
931		1029
932	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1030	If the program is not event-based, it need not do anything special, even
933	do anything special (it does not need to be event-based) and let	1031	when it depends on a module that uses an AnyEvent. If the program itself
934	AnyEvent decide which implementation to chose if some module relies on	1032	uses AnyEvent, but does not care which event loop is used, all it needs
935	it.	1033	to do is "use AnyEvent". In either case, AnyEvent will choose the best
		1034	available loop implementation.
936		1035
937	If the main program relies on a specific event model - for example, in	1036	If the main program relies on a specific event model - for example, in
938	Gtk2 programs you have to rely on the Glib module - you should load the	1037	Gtk2 programs you have to rely on the Glib module - you should load the
939	event module before loading AnyEvent or any module that uses it:	1038	event module before loading AnyEvent or any module that uses it:
940	generally speaking, you should load it as early as possible. The reason	1039	generally speaking, you should load it as early as possible. The reason
941	is that modules might create watchers when they are loaded, and AnyEvent	1040	is that modules might create watchers when they are loaded, and AnyEvent
942	will decide on the event model to use as soon as it creates watchers,	1041	will decide on the event model to use as soon as it creates watchers,
943	and it might chose the wrong one unless you load the correct one	1042	and it might choose the wrong one unless you load the correct one
944	yourself.	1043	yourself.
945		1044
946	You can chose to use a pure-perl implementation by loading the	1045	You can chose to use a pure-perl implementation by loading the
947	"AnyEvent::Impl::Perl" module, which gives you similar behaviour	1046	"AnyEvent::Loop" module, which gives you similar behaviour everywhere,
948	everywhere, but letting AnyEvent chose the model is generally better.	1047	but letting AnyEvent chose the model is generally better.
949		1048
950	MAINLOOP EMULATION	1049	MAINLOOP EMULATION
951	Sometimes (often for short test scripts, or even standalone programs who	1050	Sometimes (often for short test scripts, or even standalone programs who
952	only want to use AnyEvent), you do not want to run a specific event	1051	only want to use AnyEvent), you do not want to run a specific event
953	loop.	1052	loop.
…		…
965		1064
966	OTHER MODULES	1065	OTHER MODULES
967	The following is a non-exhaustive list of additional modules that use	1066	The following is a non-exhaustive list of additional modules that use
968	AnyEvent as a client and can therefore be mixed easily with other	1067	AnyEvent as a client and can therefore be mixed easily with other
969	AnyEvent modules and other event loops in the same program. Some of the	1068	AnyEvent modules and other event loops in the same program. Some of the
970	modules come with AnyEvent, most are available via CPAN.	1069	modules come as part of AnyEvent, the others are available via CPAN.
971		1070
972	AnyEvent::Util	1071	AnyEvent::Util
973	Contains various utility functions that replace often-used but	1072	Contains various utility functions that replace often-used blocking
974	blocking functions such as "inet_aton" by event-/callback-based	1073	functions such as "inet_aton" with event/callback-based versions.
975	versions.
976		1074
977	AnyEvent::Socket	1075	AnyEvent::Socket
978	Provides various utility functions for (internet protocol) sockets,	1076	Provides various utility functions for (internet protocol) sockets,
979	addresses and name resolution. Also functions to create non-blocking	1077	addresses and name resolution. Also functions to create non-blocking
980	tcp connections or tcp servers, with IPv6 and SRV record support and	1078	tcp connections or tcp servers, with IPv6 and SRV record support and
981	more.	1079	more.
982		1080
983	AnyEvent::Handle	1081	AnyEvent::Handle
984	Provide read and write buffers, manages watchers for reads and	1082	Provide read and write buffers, manages watchers for reads and
985	writes, supports raw and formatted I/O, I/O queued and fully	1083	writes, supports raw and formatted I/O, I/O queued and fully
986	transparent and non-blocking SSL/TLS (via AnyEvent::TLS.	1084	transparent and non-blocking SSL/TLS (via AnyEvent::TLS).
987		1085
988	AnyEvent::DNS	1086	AnyEvent::DNS
989	Provides rich asynchronous DNS resolver capabilities.	1087	Provides rich asynchronous DNS resolver capabilities.
990		1088
		1089	AnyEvent::HTTP, AnyEvent::IRC, AnyEvent::XMPP, AnyEvent::GPSD,
		1090	AnyEvent::IGS, AnyEvent::FCP
		1091	Implement event-based interfaces to the protocols of the same name
		1092	(for the curious, IGS is the International Go Server and FCP is the
		1093	Freenet Client Protocol).
		1094
		1095	AnyEvent::Handle::UDP
		1096	Here be danger!
		1097
		1098	As Pauli would put it, "Not only is it not right, it's not even
		1099	wrong!" - there are so many things wrong with AnyEvent::Handle::UDP,
		1100	most notably its use of a stream-based API with a protocol that
		1101	isn't streamable, that the only way to improve it is to delete it.
		1102
		1103	It features data corruption (but typically only under load) and
		1104	general confusion. On top, the author is not only clueless about UDP
		1105	but also fact-resistant - some gems of his understanding: "connect
		1106	doesn't work with UDP", "UDP packets are not IP packets", "UDP only
		1107	has datagrams, not packets", "I don't need to implement proper error
		1108	checking as UDP doesn't support error checking" and so on - he
		1109	doesn't even understand what's wrong with his module when it is
		1110	explained to him.
		1111
991	AnyEvent::HTTP	1112	AnyEvent::DBI
992	A simple-to-use HTTP library that is capable of making a lot of	1113	Executes DBI requests asynchronously in a proxy process for you,
993	concurrent HTTP requests.	1114	notifying you in an event-based way when the operation is finished.
		1115
		1116	AnyEvent::AIO
		1117	Truly asynchronous (as opposed to non-blocking) I/O, should be in
		1118	the toolbox of every event programmer. AnyEvent::AIO transparently
		1119	fuses IO::AIO and AnyEvent together, giving AnyEvent access to
		1120	event-based file I/O, and much more.
994		1121
995	AnyEvent::HTTPD	1122	AnyEvent::HTTPD
996	Provides a simple web application server framework.	1123	A simple embedded webserver.
997		1124
998	AnyEvent::FastPing	1125	AnyEvent::FastPing
999	The fastest ping in the west.	1126	The fastest ping in the west.
1000
1001	AnyEvent::DBI
1002	Executes DBI requests asynchronously in a proxy process.
1003
1004	AnyEvent::AIO
1005	Truly asynchronous I/O, should be in the toolbox of every event
1006	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
1007	together.
1008
1009	AnyEvent::BDB
1010	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently
1011	fuses BDB and AnyEvent together.
1012
1013	AnyEvent::GPSD
1014	A non-blocking interface to gpsd, a daemon delivering GPS
1015	information.
1016
1017	AnyEvent::IRC
1018	AnyEvent based IRC client module family (replacing the older
1019	Net::IRC3).
1020
1021	AnyEvent::XMPP
1022	AnyEvent based XMPP (Jabber protocol) module family (replacing the
1023	older Net::XMPP2>.
1024
1025	AnyEvent::IGS
1026	A non-blocking interface to the Internet Go Server protocol (used by
1027	App::IGS).
1028
1029	Net::FCP
1030	AnyEvent-based implementation of the Freenet Client Protocol,
1031	birthplace of AnyEvent.
1032
1033	Event::ExecFlow
1034	High level API for event-based execution flow control.
1035		1127
1036	Coro	1128	Coro
1037	Has special support for AnyEvent via Coro::AnyEvent.	1129	Has special support for AnyEvent via Coro::AnyEvent.
1038		1130
1039	SIMPLIFIED AE API	1131	SIMPLIFIED AE API
1040	Starting with version 5.0, AnyEvent officially supports a second, much	1132	Starting with version 5.0, AnyEvent officially supports a second, much
1041	simpler, API that is designed to reduce the calling, typing and memory	1133	simpler, API that is designed to reduce the calling, typing and memory
1042	overhead.	1134	overhead by using function call syntax and a fixed number of parameters.
1043		1135
1044	See the AE manpage for details.	1136	See the AE manpage for details.
1045		1137
1046	ERROR AND EXCEPTION HANDLING	1138	ERROR AND EXCEPTION HANDLING
1047	In general, AnyEvent does not do any error handling - it relies on the	1139	In general, AnyEvent does not do any error handling - it relies on the
…		…
1090	thoroughly check the arguments passed to most method calls. If it	1182	thoroughly check the arguments passed to most method calls. If it
1091	finds any problems, it will croak.	1183	finds any problems, it will croak.
1092		1184
1093	In other words, enables "strict" mode.	1185	In other words, enables "strict" mode.
1094		1186
1095	Unlike "use strict" (or it's modern cousin, "use common::sense", it	1187	Unlike "use strict" (or its modern cousin, "use common::sense", it
1096	is definitely recommended to keep it off in production. Keeping	1188	is definitely recommended to keep it off in production. Keeping
1097	"PERL_ANYEVENT_STRICT=1" in your environment while developing	1189	"PERL_ANYEVENT_STRICT=1" in your environment while developing
1098	programs can be very useful, however.	1190	programs can be very useful, however.
1099		1191
		1192	"PERL_ANYEVENT_DEBUG_SHELL"
		1193	If this env variable is set, then its contents will be interpreted
		1194	by "AnyEvent::Socket::parse_hostport" (after replacing every
		1195	occurance of $$ by the process pid) and an "AnyEvent::Debug::shell"
		1196	is bound on that port. The shell object is saved in
		1197	$AnyEvent::Debug::SHELL.
		1198
		1199	This takes place when the first watcher is created.
		1200
		1201	For example, to bind a debug shell on a unix domain socket in
		1202	/tmp/debug<pid>.sock, you could use this:
		1203
		1204	PERL_ANYEVENT_DEBUG_SHELL=unix/:/tmp/debug\$\$.sock perlprog
		1205
		1206	Note that creating sockets in /tmp is very unsafe on multiuser
		1207	systems.
		1208
		1209	"PERL_ANYEVENT_DEBUG_WRAP"
		1210	Can be set to 0, 1 or 2 and enables wrapping of all watchers for
		1211	debugging purposes. See "AnyEvent::Debug::wrap" for details.
		1212
1100	"PERL_ANYEVENT_MODEL"	1213	"PERL_ANYEVENT_MODEL"
1101	This can be used to specify the event model to be used by AnyEvent,	1214	This can be used to specify the event model to be used by AnyEvent,
1102	before auto detection and -probing kicks in. It must be a string	1215	before auto detection and -probing kicks in.
1103	consisting entirely of ASCII letters. The string "AnyEvent::Impl::"	1216
1104	gets prepended and the resulting module name is loaded and if the	1217	It normally is a string consisting entirely of ASCII letters (e.g.
1105	load was successful, used as event model. If it fails to load	1218	"EV" or "IOAsync"). The string "AnyEvent::Impl::" gets prepended and
		1219	the resulting module name is loaded and - if the load was successful
		1220	- used as event model backend. If it fails to load then AnyEvent
1106	AnyEvent will proceed with auto detection and -probing.	1221	will proceed with auto detection and -probing.
1107		1222
1108	This functionality might change in future versions.	1223	If the string ends with "::" instead (e.g. "AnyEvent::Impl::EV::")
		1224	then nothing gets prepended and the module name is used as-is (hint:
		1225	"::" at the end of a string designates a module name and quotes it
		1226	appropriately).
1109		1227
1110	For example, to force the pure perl model (AnyEvent::Impl::Perl) you	1228	For example, to force the pure perl model (AnyEvent::Loop::Perl) you
1111	could start your program like this:	1229	could start your program like this:
1112		1230
1113	PERL_ANYEVENT_MODEL=Perl perl ...	1231	PERL_ANYEVENT_MODEL=Perl perl ...
1114		1232
1115	"PERL_ANYEVENT_PROTOCOLS"	1233	"PERL_ANYEVENT_PROTOCOLS"
…		…
1312		1430
1313	The actual code goes further and collects all errors ("die"s,	1431	The actual code goes further and collects all errors ("die"s,
1314	exceptions) that occurred during request processing. The "result" method	1432	exceptions) that occurred during request processing. The "result" method
1315	detects whether an exception as thrown (it is stored inside the $txn	1433	detects whether an exception as thrown (it is stored inside the $txn
1316	object) and just throws the exception, which means connection errors and	1434	object) and just throws the exception, which means connection errors and
1317	other problems get reported tot he code that tries to use the result,	1435	other problems get reported to the code that tries to use the result,
1318	not in a random callback.	1436	not in a random callback.
1319		1437
1320	All of this enables the following usage styles:	1438	All of this enables the following usage styles:
1321		1439
1322	1. Blocking:	1440	1. Blocking:
…		…
1696		1814
1697	Feel free to install your own handler, or reset it to defaults.	1815	Feel free to install your own handler, or reset it to defaults.
1698		1816
1699	RECOMMENDED/OPTIONAL MODULES	1817	RECOMMENDED/OPTIONAL MODULES
1700	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and	1818	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
1701	it's built-in modules) are required to use it.	1819	its built-in modules) are required to use it.
1702		1820
1703	That does not mean that AnyEvent won't take advantage of some additional	1821	That does not mean that AnyEvent won't take advantage of some additional
1704	modules if they are installed.	1822	modules if they are installed.
1705		1823
1706	This section epxlains which additional modules will be used, and how	1824	This section explains which additional modules will be used, and how
1707	they affect AnyEvent's operetion.	1825	they affect AnyEvent's operation.
1708		1826
1709	Async::Interrupt	1827	Async::Interrupt
1710	This slightly arcane module is used to implement fast signal	1828	This slightly arcane module is used to implement fast signal
1711	handling: To my knowledge, there is no way to do completely	1829	handling: To my knowledge, there is no way to do completely
1712	race-free and quick signal handling in pure perl. To ensure that	1830	race-free and quick signal handling in pure perl. To ensure that
…		…
1715	10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY).	1833	10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY).
1716		1834
1717	If this module is available, then it will be used to implement	1835	If this module is available, then it will be used to implement
1718	signal catching, which means that signals will not be delayed, and	1836	signal catching, which means that signals will not be delayed, and
1719	the event loop will not be interrupted regularly, which is more	1837	the event loop will not be interrupted regularly, which is more
1720	efficient (And good for battery life on laptops).	1838	efficient (and good for battery life on laptops).
1721		1839
1722	This affects not just the pure-perl event loop, but also other event	1840	This affects not just the pure-perl event loop, but also other event
1723	loops that have no signal handling on their own (e.g. Glib, Tk, Qt).	1841	loops that have no signal handling on their own (e.g. Glib, Tk, Qt).
1724		1842
1725	Some event loops (POE, Event, Event::Lib) offer signal watchers	1843	Some event loops (POE, Event, Event::Lib) offer signal watchers
…		…
1735	clock is available, can take avdantage of advanced kernel interfaces	1853	clock is available, can take avdantage of advanced kernel interfaces
1736	such as "epoll" and "kqueue", and is the fastest backend by far.	1854	such as "epoll" and "kqueue", and is the fastest backend by far.
1737	You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and	1855	You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and
1738	Glib::EV).	1856	Glib::EV).
1739		1857
		1858	If you only use backends that rely on another event loop (e.g.
		1859	"Tk"), then this module will do nothing for you.
		1860
1740	Guard	1861	Guard
1741	The guard module, when used, will be used to implement	1862	The guard module, when used, will be used to implement
1742	"AnyEvent::Util::guard". This speeds up guards considerably (and	1863	"AnyEvent::Util::guard". This speeds up guards considerably (and
1743	uses a lot less memory), but otherwise doesn't affect guard	1864	uses a lot less memory), but otherwise doesn't affect guard
1744	operation much. It is purely used for performance.	1865	operation much. It is purely used for performance.
1745		1866
1746	JSON and JSON::XS	1867	JSON and JSON::XS
1747	This module is required when you want to read or write JSON data via	1868	One of these modules is required when you want to read or write JSON
1748	AnyEvent::Handle. It is also written in pure-perl, but can take	1869	data via AnyEvent::Handle. JSON is also written in pure-perl, but
1749	advantage of the ultra-high-speed JSON::XS module when it is	1870	can take advantage of the ultra-high-speed JSON::XS module when it
1750	installed.	1871	is installed.
1751
1752	In fact, AnyEvent::Handle will use JSON::XS by default if it is
1753	installed.
1754		1872
1755	Net::SSLeay	1873	Net::SSLeay
1756	Implementing TLS/SSL in Perl is certainly interesting, but not very	1874	Implementing TLS/SSL in Perl is certainly interesting, but not very
1757	worthwhile: If this module is installed, then AnyEvent::Handle (with	1875	worthwhile: If this module is installed, then AnyEvent::Handle (with
1758	the help of AnyEvent::TLS), gains the ability to do TLS/SSL.	1876	the help of AnyEvent::TLS), gains the ability to do TLS/SSL.
1759		1877
1760	Time::HiRes	1878	Time::HiRes
1761	This module is part of perl since release 5.008. It will be used	1879	This module is part of perl since release 5.008. It will be used
1762	when the chosen event library does not come with a timing source on	1880	when the chosen event library does not come with a timing source of
1763	it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will	1881	its own. The pure-perl event loop (AnyEvent::Loop) will additionally
1764	additionally use it to try to use a monotonic clock for timing	1882	load it to try to use a monotonic clock for timing stability.
1765	stability.
1766		1883
1767	FORK	1884	FORK
1768	Most event libraries are not fork-safe. The ones who are usually are	1885	Most event libraries are not fork-safe. The ones who are usually are
1769	because they rely on inefficient but fork-safe "select" or "poll" calls.	1886	because they rely on inefficient but fork-safe "select" or "poll" calls
1770	Only EV is fully fork-aware.	1887	- higher performance APIs such as BSD's kqueue or the dreaded Linux
		1888	epoll are usually badly thought-out hacks that are incompatible with
		1889	fork in one way or another. Only EV is fully fork-aware and ensures that
		1890	you continue event-processing in both parent and child (or both, if you
		1891	know what you are doing).
		1892
		1893	This means that, in general, you cannot fork and do event processing in
		1894	the child if the event library was initialised before the fork (which
		1895	usually happens when the first AnyEvent watcher is created, or the
		1896	library is loaded).
1771		1897
1772	If you have to fork, you must either do so before creating your first	1898	If you have to fork, you must either do so before creating your first
1773	watcher OR you must not use AnyEvent at all in the child OR you must do	1899	watcher OR you must not use AnyEvent at all in the child OR you must do
1774	something completely out of the scope of AnyEvent.	1900	something completely out of the scope of AnyEvent.
		1901
		1902	The problem of doing event processing in the parent and the child is
		1903	much more complicated: even for backends that are fork-aware or
		1904	fork-safe, their behaviour is not usually what you want: fork clones all
		1905	watchers, that means all timers, I/O watchers etc. are active in both
		1906	parent and child, which is almost never what you want. USing "exec" to
		1907	start worker children from some kind of manage rprocess is usually
		1908	preferred, because it is much easier and cleaner, at the expense of
		1909	having to have another binary.
1775		1910
1776	SECURITY CONSIDERATIONS	1911	SECURITY CONSIDERATIONS
1777	AnyEvent can be forced to load any event model via	1912	AnyEvent can be forced to load any event model via
1778	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used	1913	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used
1779	to execute arbitrary code or directly gain access, it can easily be used	1914	to execute arbitrary code or directly gain access, it can easily be used
…		…
1803	5.10 and check wether the leaks still show up. (Perl 5.10.0 has other	1938	5.10 and check wether the leaks still show up. (Perl 5.10.0 has other
1804	annoying memleaks, such as leaking on "map" and "grep" but it is usually	1939	annoying memleaks, such as leaking on "map" and "grep" but it is usually
1805	not as pronounced).	1940	not as pronounced).
1806		1941
1807	SEE ALSO	1942	SEE ALSO
		1943	Tutorial/Introduction: AnyEvent::Intro.
		1944
		1945	FAQ: AnyEvent::FAQ.
		1946
1808	Utility functions: AnyEvent::Util.	1947	Utility functions: AnyEvent::Util.
1809		1948
1810	Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,	1949	Event modules: AnyEvent::Loop, EV, EV::Glib, Glib::EV, Event,
1811	Event::Lib, Qt, POE.	1950	Glib::Event, Glib, Tk, Event::Lib, Qt, POE.
1812		1951
1813	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,	1952	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,
1814	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,	1953	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,
1815	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,	1954	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,
1816	AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi.	1955	AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi.
…		…
1818	Non-blocking file handles, sockets, TCP clients and servers:	1957	Non-blocking file handles, sockets, TCP clients and servers:
1819	AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.	1958	AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.
1820		1959
1821	Asynchronous DNS: AnyEvent::DNS.	1960	Asynchronous DNS: AnyEvent::DNS.
1822		1961
1823	Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event,	1962	Thread support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event.
1824		1963
1825	Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP,	1964	Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::IRC,
1826	AnyEvent::HTTP.	1965	AnyEvent::HTTP.
1827		1966
1828	AUTHOR	1967	AUTHOR
1829	Marc Lehmann <schmorp@schmorp.de>	1968	Marc Lehmann <schmorp@schmorp.de>
1830	http://home.schmorp.de/	1969	http://home.schmorp.de/

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Comparing AnyEvent/README (file contents): Revision 1.54 by root, Tue Sep 1 18:27:46 2009 UTC vs. Revision 1.65 by root, Sat Aug 13 22:44:05 2011 UTC

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Comparing AnyEvent/README (file contents):
Revision 1.54 by root, Tue Sep 1 18:27:46 2009 UTC vs.
Revision 1.65 by root, Sat Aug 13 22:44:05 2011 UTC