[ViewVC] Diff of: cvs/AnyEvent/lib/AnyEvent.pm

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.36 by root, Fri Nov 16 09:13:11 2007 UTC vs.
Revision 1.83 by root, Fri Apr 25 13:39:08 2008 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	Event, Coro, Glib, Tk, Perl - various supported event loops	5	EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops
6		6
7	=head1 SYNOPSIS	7	=head1 SYNOPSIS
8		8
9	use AnyEvent;	9	use AnyEvent;
10		10
14		14
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	15	my $w = AnyEvent->timer (after => $seconds, cb => sub {
16	...	16	...
17	});	17	});
18		18
19	my $w = AnyEvent->condvar; # stores wether a condition was flagged	19	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->wait; # enters "main loop" till $condvar gets ->broadcast	20	$w->wait; # enters "main loop" till $condvar gets ->broadcast
21	$w->broadcast; # wake up current and all future wait's	21	$w->broadcast; # wake up current and all future wait's
		22
		23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
		24
		25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
		26	nowadays. So what is different about AnyEvent?
		27
		28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
		29	policy> and AnyEvent is I<small and efficient>.
		30
		31	First and foremost, I<AnyEvent is not an event model> itself, it only
		32	interfaces to whatever event model the main program happens to use in a
		33	pragmatic way. For event models and certain classes of immortals alike,
		34	the statement "there can only be one" is a bitter reality: In general,
		35	only one event loop can be active at the same time in a process. AnyEvent
		36	helps hiding the differences between those event loops.
		37
		38	The goal of AnyEvent is to offer module authors the ability to do event
		39	programming (waiting for I/O or timer events) without subscribing to a
		40	religion, a way of living, and most importantly: without forcing your
		41	module users into the same thing by forcing them to use the same event
		42	model you use.
		43
		44	For modules like POE or IO::Async (which is a total misnomer as it is
		45	actually doing all I/O I<synchronously>...), using them in your module is
		46	like joining a cult: After you joined, you are dependent on them and you
		47	cannot use anything else, as it is simply incompatible to everything that
		48	isn't itself. What's worse, all the potential users of your module are
		49	I<also> forced to use the same event loop you use.
		50
		51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
		52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
		53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if
		54	your module uses one of those, every user of your module has to use it,
		55	too. But if your module uses AnyEvent, it works transparently with all
		56	event models it supports (including stuff like POE and IO::Async, as long
		57	as those use one of the supported event loops. It is trivial to add new
		58	event loops to AnyEvent, too, so it is future-proof).
		59
		60	In addition to being free of having to use I<the one and only true event
		61	model>, AnyEvent also is free of bloat and policy: with POE or similar
		62	modules, you get an enourmous amount of code and strict rules you have to
		63	follow. AnyEvent, on the other hand, is lean and up to the point, by only
		64	offering the functionality that is necessary, in as thin as a wrapper as
		65	technically possible.
		66
		67	Of course, if you want lots of policy (this can arguably be somewhat
		68	useful) and you want to force your users to use the one and only event
		69	model, you should I<not> use this module.
		70
22		71
23	=head1 DESCRIPTION	72	=head1 DESCRIPTION
24		73
25	L<AnyEvent> provides an identical interface to multiple event loops. This	74	L<AnyEvent> provides an identical interface to multiple event loops. This
26	allows module authors to utilise an event loop without forcing module	75	allows module authors to utilise an event loop without forcing module
27	users to use the same event loop (as only a single event loop can coexist	76	users to use the same event loop (as only a single event loop can coexist
28	peacefully at any one time).	77	peacefully at any one time).
29		78
30	The interface itself is vaguely similar but not identical to the Event	79	The interface itself is vaguely similar, but not identical to the L<Event>
31	module.	80	module.
32		81
33	On the first call of any method, the module tries to detect the currently	82	During the first call of any watcher-creation method, the module tries
34	loaded event loop by probing wether any of the following modules is	83	to detect the currently loaded event loop by probing whether one of the
35	loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is	84	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,
36	used. If none is found, the module tries to load these modules in the	85	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
37	order given. The first one that could be successfully loaded will be	86	L<POE>. The first one found is used. If none are found, the module tries
38	used. If still none could be found, AnyEvent will fall back to a pure-perl	87	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
39	event loop, which is also not very efficient.	88	adaptor should always succeed) in the order given. The first one that can
		89	be successfully loaded will be used. If, after this, still none could be
		90	found, AnyEvent will fall back to a pure-perl event loop, which is not
		91	very efficient, but should work everywhere.
40		92
41	Because AnyEvent first checks for modules that are already loaded, loading	93	Because AnyEvent first checks for modules that are already loaded, loading
42	an Event model explicitly before first using AnyEvent will likely make	94	an event model explicitly before first using AnyEvent will likely make
43	that model the default. For example:	95	that model the default. For example:
44		96
45	use Tk;	97	use Tk;
46	use AnyEvent;	98	use AnyEvent;
47		99
48	# .. AnyEvent will likely default to Tk	100	# .. AnyEvent will likely default to Tk
		101
		102	The I<likely> means that, if any module loads another event model and
		103	starts using it, all bets are off. Maybe you should tell their authors to
		104	use AnyEvent so their modules work together with others seamlessly...
49		105
50	The pure-perl implementation of AnyEvent is called	106	The pure-perl implementation of AnyEvent is called
51	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	107	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
52	explicitly.	108	explicitly.
53		109
…		…
56	AnyEvent has the central concept of a I<watcher>, which is an object that	112	AnyEvent has the central concept of a I<watcher>, which is an object that
57	stores relevant data for each kind of event you are waiting for, such as	113	stores relevant data for each kind of event you are waiting for, such as
58	the callback to call, the filehandle to watch, etc.	114	the callback to call, the filehandle to watch, etc.
59		115
60	These watchers are normal Perl objects with normal Perl lifetime. After	116	These watchers are normal Perl objects with normal Perl lifetime. After
61	creating a watcher it will immediately "watch" for events and invoke	117	creating a watcher it will immediately "watch" for events and invoke the
		118	callback when the event occurs (of course, only when the event model
		119	is in control).
		120
62	the callback. To disable the watcher you have to destroy it (e.g. by	121	To disable the watcher you have to destroy it (e.g. by setting the
63	setting the variable that stores it to C<undef> or otherwise deleting all	122	variable you store it in to C<undef> or otherwise deleting all references
64	references to it).	123	to it).
65		124
66	All watchers are created by calling a method on the C<AnyEvent> class.	125	All watchers are created by calling a method on the C<AnyEvent> class.
67		126
		127	Many watchers either are used with "recursion" (repeating timers for
		128	example), or need to refer to their watcher object in other ways.
		129
		130	An any way to achieve that is this pattern:
		131
		132	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
		133	# you can use $w here, for example to undef it
		134	undef $w;
		135	});
		136
		137	Note that C<my $w; $w => combination. This is necessary because in Perl,
		138	my variables are only visible after the statement in which they are
		139	declared.
		140
68	=head2 IO WATCHERS	141	=head2 I/O WATCHERS
69		142
70	You can create I/O watcher by calling the C<< AnyEvent->io >> method with	143	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
71	the following mandatory arguments:	144	with the following mandatory key-value pairs as arguments:
72		145
73	C<fh> the Perl I<filehandle> (not filedescriptor) to watch for	146	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for
74	events. C<poll> must be a string that is either C<r> or C<w>, that creates	147	events. C<poll> must be a string that is either C<r> or C<w>, which
75	a watcher waiting for "r"eadable or "w"ritable events. C<cb> the callback	148	creates a watcher waiting for "r"eadable or "w"ritable events,
76	to invoke everytime the filehandle becomes ready.	149	respectively. C<cb> is the callback to invoke each time the file handle
		150	becomes ready.
77		151
78	Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on	152	The I/O watcher might use the underlying file descriptor or a copy of it.
79	a socket you can have one r + one w, not any more (limitation comes from	153	It is not allowed to close a file handle as long as any watcher is active
80	Tk - if you are sure you are not using Tk this limitation is gone).	154	on the underlying file descriptor.
81		155
82	Filehandles will be kept alive, so as long as the watcher exists, the	156	Some event loops issue spurious readyness notifications, so you should
83	filehandle exists, too.	157	always use non-blocking calls when reading/writing from/to your file
		158	handles.
84		159
85	Example:	160	Example:
86		161
87	# wait for readability of STDIN, then read a line and disable the watcher	162	# wait for readability of STDIN, then read a line and disable the watcher
88	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	163	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
…		…
94	=head2 TIME WATCHERS	169	=head2 TIME WATCHERS
95		170
96	You can create a time watcher by calling the C<< AnyEvent->timer >>	171	You can create a time watcher by calling the C<< AnyEvent->timer >>
97	method with the following mandatory arguments:	172	method with the following mandatory arguments:
98		173
99	C<after> after how many seconds (fractions are supported) should the timer	174	C<after> specifies after how many seconds (fractional values are
100	activate. C<cb> the callback to invoke.	175	supported) should the timer activate. C<cb> the callback to invoke in that
		176	case.
101		177
102	The timer callback will be invoked at most once: if you want a repeating	178	The timer callback will be invoked at most once: if you want a repeating
103	timer you have to create a new watcher (this is a limitation by both Tk	179	timer you have to create a new watcher (this is a limitation by both Tk
104	and Glib).	180	and Glib).
105		181
…		…
109	my $w = AnyEvent->timer (after => 7.7, cb => sub {	185	my $w = AnyEvent->timer (after => 7.7, cb => sub {
110	warn "timeout\n";	186	warn "timeout\n";
111	});	187	});
112		188
113	# to cancel the timer:	189	# to cancel the timer:
114	undef $w	190	undef $w;
115		191
		192	Example 2:
		193
		194	# fire an event after 0.5 seconds, then roughly every second
		195	my $w;
		196
		197	my $cb = sub {
		198	# cancel the old timer while creating a new one
		199	$w = AnyEvent->timer (after => 1, cb => $cb);
		200	};
		201
		202	# start the "loop" by creating the first watcher
		203	$w = AnyEvent->timer (after => 0.5, cb => $cb);
		204
		205	=head3 TIMING ISSUES
		206
		207	There are two ways to handle timers: based on real time (relative, "fire
		208	in 10 seconds") and based on wallclock time (absolute, "fire at 12
		209	o'clock").
		210
		211	While most event loops expect timers to specified in a relative way, they
		212	use absolute time internally. This makes a difference when your clock
		213	"jumps", for example, when ntp decides to set your clock backwards from
		214	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to
		215	fire "after" a second might actually take six years to finally fire.
		216
		217	AnyEvent cannot compensate for this. The only event loop that is conscious
		218	about these issues is L<EV>, which offers both relative (ev_timer, based
		219	on true relative time) and absolute (ev_periodic, based on wallclock time)
		220	timers.
		221
		222	AnyEvent always prefers relative timers, if available, matching the
		223	AnyEvent API.
		224
		225	=head2 SIGNAL WATCHERS
		226
		227	You can watch for signals using a signal watcher, C<signal> is the signal
		228	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to
		229	be invoked whenever a signal occurs.
		230
		231	Multiple signal occurances can be clumped together into one callback
		232	invocation, and callback invocation will be synchronous. synchronous means
		233	that it might take a while until the signal gets handled by the process,
		234	but it is guarenteed not to interrupt any other callbacks.
		235
		236	The main advantage of using these watchers is that you can share a signal
		237	between multiple watchers.
		238
		239	This watcher might use C<%SIG>, so programs overwriting those signals
		240	directly will likely not work correctly.
		241
		242	Example: exit on SIGINT
		243
		244	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
		245
		246	=head2 CHILD PROCESS WATCHERS
		247
		248	You can also watch on a child process exit and catch its exit status.
		249
		250	The child process is specified by the C<pid> argument (if set to C<0>, it
		251	watches for any child process exit). The watcher will trigger as often
		252	as status change for the child are received. This works by installing a
		253	signal handler for C<SIGCHLD>. The callback will be called with the pid
		254	and exit status (as returned by waitpid).
		255
		256	There is a slight catch to child watchers, however: you usually start them
		257	I<after> the child process was created, and this means the process could
		258	have exited already (and no SIGCHLD will be sent anymore).
		259
		260	Not all event models handle this correctly (POE doesn't), but even for
		261	event models that I<do> handle this correctly, they usually need to be
		262	loaded before the process exits (i.e. before you fork in the first place).
		263
		264	This means you cannot create a child watcher as the very first thing in an
		265	AnyEvent program, you I<have> to create at least one watcher before you
		266	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
		267
		268	Example: fork a process and wait for it
		269
		270	my $done = AnyEvent->condvar;
		271
		272	AnyEvent::detect; # force event module to be initialised
		273
		274	my $pid = fork or exit 5;
		275
		276	my $w = AnyEvent->child (
		277	pid => $pid,
		278	cb => sub {
		279	my ($pid, $status) = @_;
		280	warn "pid $pid exited with status $status";
		281	$done->broadcast;
		282	},
		283	);
		284
		285	# do something else, then wait for process exit
		286	$done->wait;
		287
116	=head2 CONDITION WATCHERS	288	=head2 CONDITION VARIABLES
117		289
118	Condition watchers can be created by calling the C<< AnyEvent->condvar >>	290	Condition variables can be created by calling the C<< AnyEvent->condvar >>
119	method without any arguments.	291	method without any arguments.
120		292
121	A condition watcher watches for a condition - precisely that the C<<	293	A condition variable waits for a condition - precisely that the C<<
122	->broadcast >> method has been called.	294	->broadcast >> method has been called.
123		295
124	The watcher has only two methods:	296	They are very useful to signal that a condition has been fulfilled, for
		297	example, if you write a module that does asynchronous http requests,
		298	then a condition variable would be the ideal candidate to signal the
		299	availability of results.
		300
		301	You can also use condition variables to block your main program until
		302	an event occurs - for example, you could C<< ->wait >> in your main
		303	program until the user clicks the Quit button in your app, which would C<<
		304	->broadcast >> the "quit" event.
		305
		306	Note that condition variables recurse into the event loop - if you have
		307	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you
		308	lose. Therefore, condition variables are good to export to your caller, but
		309	you should avoid making a blocking wait yourself, at least in callbacks,
		310	as this asks for trouble.
		311
		312	This object has two methods:
125		313
126	=over 4	314	=over 4
127		315
128	=item $cv->wait	316	=item $cv->wait
129		317
130	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	318	Wait (blocking if necessary) until the C<< ->broadcast >> method has been
131	called on c<$cv>, while servicing other watchers normally.	319	called on c<$cv>, while servicing other watchers normally.
132		320
133	Not all event models support a blocking wait - some die in that case, so
134	if you are using this from a module, never require a blocking wait, but
135	let the caller decide wether the call will block or not (for example,
136	by coupling condition variables with some kind of request results and
137	supporting callbacks so the caller knows that getting the result will not
138	block, while still suppporting blockign waits if the caller so desires).
139
140	You can only wait once on a condition - additional calls will return	321	You can only wait once on a condition - additional calls will return
141	immediately.	322	immediately.
142		323
		324	Not all event models support a blocking wait - some die in that case
		325	(programs might want to do that to stay interactive), so I<if you are
		326	using this from a module, never require a blocking wait>, but let the
		327	caller decide whether the call will block or not (for example, by coupling
		328	condition variables with some kind of request results and supporting
		329	callbacks so the caller knows that getting the result will not block,
		330	while still suppporting blocking waits if the caller so desires).
		331
		332	Another reason I<never> to C<< ->wait >> in a module is that you cannot
		333	sensibly have two C<< ->wait >>'s in parallel, as that would require
		334	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
		335	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and
		336	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
		337	from different coroutines, however).
		338
143	=item $cv->broadcast	339	=item $cv->broadcast
144		340
145	Flag the condition as ready - a running C<< ->wait >> and all further	341	Flag the condition as ready - a running C<< ->wait >> and all further
146	calls to C<wait> will return after this method has been called. If nobody	342	calls to C<wait> will (eventually) return after this method has been
147	is waiting the broadcast will be remembered..	343	called. If nobody is waiting the broadcast will be remembered..
		344
		345	=back
148		346
149	Example:	347	Example:
150		348
151	# wait till the result is ready	349	# wait till the result is ready
152	my $result_ready = AnyEvent->condvar;	350	my $result_ready = AnyEvent->condvar;
153		351
154	# do something such as adding a timer	352	# do something such as adding a timer
155	# or socket watcher the calls $result_ready->broadcast	353	# or socket watcher the calls $result_ready->broadcast
156	# when the "result" is ready.	354	# when the "result" is ready.
		355	# in this case, we simply use a timer:
		356	my $w = AnyEvent->timer (
		357	after => 1,
		358	cb => sub { $result_ready->broadcast },
		359	);
157		360
		361	# this "blocks" (while handling events) till the watcher
		362	# calls broadcast
158	$result_ready->wait;	363	$result_ready->wait;
159		364
160	=back	365	=head1 GLOBAL VARIABLES AND FUNCTIONS
161
162	=head2 SIGNAL WATCHERS
163
164	You can listen for signals using a signal watcher, C<signal> is the signal
165	I<name> without any C<SIG> prefix. Multiple signals events can be clumped
166	together into one callback invocation, and callback invocation might or
167	might not be asynchronous.
168
169	These watchers might use C<%SIG>, so programs overwriting those signals
170	directly will likely not work correctly.
171
172	Example: exit on SIGINT
173
174	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
175
176	=head2 CHILD PROCESS WATCHERS
177
178	You can also listen for the status of a child process specified by the
179	C<pid> argument (or any child if the pid argument is 0). The watcher will
180	trigger as often as status change for the child are received. This works
181	by installing a signal handler for C<SIGCHLD>. The callback will be called with
182	the pid and exit status (as returned by waitpid).
183
184	Example: wait for pid 1333
185
186	my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" });
187
188	=head1 GLOBALS
189		366
190	=over 4	367	=over 4
191		368
192	=item $AnyEvent::MODEL	369	=item $AnyEvent::MODEL
193		370
…		…
198	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	375	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
199		376
200	The known classes so far are:	377	The known classes so far are:
201		378
202	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.	379	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
		380	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
203	AnyEvent::Impl::EV based on EV (an interface to libev, also best choice).	381	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
204	AnyEvent::Impl::Coro based on Coro::Event, second best choice.
205	AnyEvent::Impl::Event based on Event, also second best choice :)	382	AnyEvent::Impl::Event based on Event, second best choice.
206	AnyEvent::Impl::Glib based on Glib, second-best choice.	383	AnyEvent::Impl::Glib based on Glib, third-best choice.
		384	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
207	AnyEvent::Impl::Tk based on Tk, very bad choice.	385	AnyEvent::Impl::Tk based on Tk, very bad choice.
208	AnyEvent::Impl::Perl pure-perl implementation, inefficient.	386	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
		387	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		388	AnyEvent::Impl::POE based on POE, not generic enough for full support.
		389
		390	There is no support for WxWidgets, as WxWidgets has no support for
		391	watching file handles. However, you can use WxWidgets through the
		392	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
		393	second, which was considered to be too horrible to even consider for
		394	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
		395	it's adaptor.
		396
		397	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
		398	autodetecting them.
209		399
210	=item AnyEvent::detect	400	=item AnyEvent::detect
211		401
212	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if	402	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
213	necessary. You should only call this function right before you would have	403	if necessary. You should only call this function right before you would
214	created an AnyEvent watcher anyway, that is, very late at runtime.	404	have created an AnyEvent watcher anyway, that is, as late as possible at
		405	runtime.
215		406
216	=back	407	=back
217		408
218	=head1 WHAT TO DO IN A MODULE	409	=head1 WHAT TO DO IN A MODULE
219		410
220	As a module author, you should "use AnyEvent" and call AnyEvent methods	411	As a module author, you should C<use AnyEvent> and call AnyEvent methods
221	freely, but you should not load a specific event module or rely on it.	412	freely, but you should not load a specific event module or rely on it.
222		413
223	Be careful when you create watchers in the module body - Anyevent will	414	Be careful when you create watchers in the module body - AnyEvent will
224	decide which event module to use as soon as the first method is called, so	415	decide which event module to use as soon as the first method is called, so
225	by calling AnyEvent in your module body you force the user of your module	416	by calling AnyEvent in your module body you force the user of your module
226	to load the event module first.	417	to load the event module first.
227		418
		419	Never call C<< ->wait >> on a condition variable unless you I<know> that
		420	the C<< ->broadcast >> method has been called on it already. This is
		421	because it will stall the whole program, and the whole point of using
		422	events is to stay interactive.
		423
		424	It is fine, however, to call C<< ->wait >> when the user of your module
		425	requests it (i.e. if you create a http request object ad have a method
		426	called C<results> that returns the results, it should call C<< ->wait >>
		427	freely, as the user of your module knows what she is doing. always).
		428
228	=head1 WHAT TO DO IN THE MAIN PROGRAM	429	=head1 WHAT TO DO IN THE MAIN PROGRAM
229		430
230	There will always be a single main program - the only place that should	431	There will always be a single main program - the only place that should
231	dictate which event model to use.	432	dictate which event model to use.
232		433
233	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	434	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
234	do anything special and let AnyEvent decide which implementation to chose.	435	do anything special (it does not need to be event-based) and let AnyEvent
		436	decide which implementation to chose if some module relies on it.
235		437
236	If the main program relies on a specific event model (for example, in Gtk2	438	If the main program relies on a specific event model. For example, in
237	programs you have to rely on either Glib or Glib::Event), you should load	439	Gtk2 programs you have to rely on the Glib module. You should load the
238	it before loading AnyEvent or any module that uses it, generally, as early	440	event module before loading AnyEvent or any module that uses it: generally
239	as possible. The reason is that modules might create watchers when they	441	speaking, you should load it as early as possible. The reason is that
240	are loaded, and AnyEvent will decide on the event model to use as soon as	442	modules might create watchers when they are loaded, and AnyEvent will
241	it creates watchers, and it might chose the wrong one unless you load the	443	decide on the event model to use as soon as it creates watchers, and it
242	correct one yourself.	444	might chose the wrong one unless you load the correct one yourself.
243		445
244	You can chose to use a rather inefficient pure-perl implementation by	446	You can chose to use a rather inefficient pure-perl implementation by
245	loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is	447	loading the C<AnyEvent::Impl::Perl> module, which gives you similar
246	generally better.	448	behaviour everywhere, but letting AnyEvent chose is generally better.
247		449
248	=cut	450	=cut
249		451
250	package AnyEvent;	452	package AnyEvent;
251		453
252	no warnings;	454	no warnings;
253	use strict;	455	use strict;
254		456
255	use Carp;	457	use Carp;
256		458
257	our $VERSION = '2.6';	459	our $VERSION = '3.3';
258	our $MODEL;	460	our $MODEL;
259		461
260	our $AUTOLOAD;	462	our $AUTOLOAD;
261	our @ISA;	463	our @ISA;
262		464
…		…
264		466
265	our @REGISTRY;	467	our @REGISTRY;
266		468
267	my @models = (	469	my @models = (
268	[Coro::EV:: => AnyEvent::Impl::CoroEV::],	470	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
		471	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
269	[EV:: => AnyEvent::Impl::EV::],	472	[EV:: => AnyEvent::Impl::EV::],
270	[Coro::Event:: => AnyEvent::Impl::Coro::],
271	[Event:: => AnyEvent::Impl::Event::],	473	[Event:: => AnyEvent::Impl::Event::],
272	[Glib:: => AnyEvent::Impl::Glib::],	474	[Glib:: => AnyEvent::Impl::Glib::],
273	[Tk:: => AnyEvent::Impl::Tk::],	475	[Tk:: => AnyEvent::Impl::Tk::],
		476	[Wx:: => AnyEvent::Impl::POE::],
		477	[Prima:: => AnyEvent::Impl::POE::],
274	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	478	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
		479	# everything below here will not be autoprobed as the pureperl backend should work everywhere
		480	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		481	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		482	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
275	);	483	);
276		484
277	our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY);	485	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);
278		486
279	sub detect() {	487	sub detect() {
280	unless ($MODEL) {	488	unless ($MODEL) {
281	no strict 'refs';	489	no strict 'refs';
282		490
		491	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
		492	my $model = "AnyEvent::Impl::$1";
		493	if (eval "require $model") {
		494	$MODEL = $model;
		495	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;
		496	} else {
		497	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;
		498	}
		499	}
		500
283	# check for already loaded models	501	# check for already loaded models
		502	unless ($MODEL) {
284	for (@REGISTRY, @models) {	503	for (@REGISTRY, @models) {
285	my ($package, $model) = @$_;	504	my ($package, $model) = @$_;
286	if (${"$package\::VERSION"} > 0) {	505	if (${"$package\::VERSION"} > 0) {
287	if (eval "require $model") {	506	if (eval "require $model") {
288	$MODEL = $model;	507	$MODEL = $model;
289	warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1;	508	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
290	last;	509	last;
		510	}
291	}	511	}
292	}	512	}
293	}
294		513
295	unless ($MODEL) {	514	unless ($MODEL) {
296	# try to load a model	515	# try to load a model
297		516
298	for (@REGISTRY, @models) {	517	for (@REGISTRY, @models) {
299	my ($package, $model) = @$_;	518	my ($package, $model) = @$_;
300	if (eval "require $package"	519	if (eval "require $package"
301	and ${"$package\::VERSION"} > 0	520	and ${"$package\::VERSION"} > 0
302	and eval "require $model") {	521	and eval "require $model") {
303	$MODEL = $model;	522	$MODEL = $model;
304	warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1;	523	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
305	last;	524	last;
		525	}
306	}	526	}
		527
		528	$MODEL
		529	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";
307	}	530	}
308
309	$MODEL
310	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event), Glib or Tk.";
311	}	531	}
312		532
313	unshift @ISA, $MODEL;	533	unshift @ISA, $MODEL;
314	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	534	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
315	}	535	}
…		…
373		593
374	# default implementation for ->child	594	# default implementation for ->child
375		595
376	our %PID_CB;	596	our %PID_CB;
377	our $CHLD_W;	597	our $CHLD_W;
		598	our $CHLD_DELAY_W;
378	our $PID_IDLE;	599	our $PID_IDLE;
379	our $WNOHANG;	600	our $WNOHANG;
380		601
381	sub _child_wait {	602	sub _child_wait {
382	while (0 <= (my $pid = waitpid -1, $WNOHANG)) {	603	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
383	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),	604	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),
384	(values %{ $PID_CB{0} \|\| {} });	605	(values %{ $PID_CB{0} \|\| {} });
385	}	606	}
386		607
387	undef $PID_IDLE;	608	undef $PID_IDLE;
388	}	609	}
389		610
		611	sub _sigchld {
		612	# make sure we deliver these changes "synchronous" with the event loop.
		613	$CHLD_DELAY_W \|\|= AnyEvent->timer (after => 0, cb => sub {
		614	undef $CHLD_DELAY_W;
		615	&_child_wait;
		616	});
		617	}
		618
390	sub child {	619	sub child {
391	my (undef, %arg) = @_;	620	my (undef, %arg) = @_;
392		621
393	defined (my $pid = $arg{pid} + 0)	622	defined (my $pid = $arg{pid} + 0)
394	or Carp::croak "required option 'pid' is missing";	623	or Carp::croak "required option 'pid' is missing";
…		…
398	unless ($WNOHANG) {	627	unless ($WNOHANG) {
399	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	628	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;
400	}	629	}
401		630
402	unless ($CHLD_W) {	631	unless ($CHLD_W) {
403	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_child_wait);	632	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
404	# child could be a zombie already	633	# child could be a zombie already, so make at least one round
405	$PID_IDLE \|\|= AnyEvent->timer (after => 0, cb => \&_child_wait);	634	&_sigchld;
406	}	635	}
407		636
408	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	637	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"
409	}	638	}
410		639
…		…
416		645
417	undef $CHLD_W unless keys %PID_CB;	646	undef $CHLD_W unless keys %PID_CB;
418	}	647	}
419		648
420	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	649	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
		650
		651	This is an advanced topic that you do not normally need to use AnyEvent in
		652	a module. This section is only of use to event loop authors who want to
		653	provide AnyEvent compatibility.
421		654
422	If you need to support another event library which isn't directly	655	If you need to support another event library which isn't directly
423	supported by AnyEvent, you can supply your own interface to it by	656	supported by AnyEvent, you can supply your own interface to it by
424	pushing, before the first watcher gets created, the package name of	657	pushing, before the first watcher gets created, the package name of
425	the event module and the package name of the interface to use onto	658	the event module and the package name of the interface to use onto
426	C<@AnyEvent::REGISTRY>. You can do that before and even without loading	659	C<@AnyEvent::REGISTRY>. You can do that before and even without loading
427	AnyEvent.	660	AnyEvent, so it is reasonably cheap.
428		661
429	Example:	662	Example:
430		663
431	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];	664	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
432		665
433	This tells AnyEvent to (literally) use the C<urxvt::anyevent::>	666	This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
434	package/class when it finds the C<urxvt> package/module is loaded. When	667	package/class when it finds the C<urxvt> package/module is already loaded.
		668
435	AnyEvent is loaded and asked to find a suitable event model, it will	669	When AnyEvent is loaded and asked to find a suitable event model, it
436	first check for the presence of urxvt.	670	will first check for the presence of urxvt by trying to C<use> the
		671	C<urxvt::anyevent> module.
437		672
438	The class should provide implementations for all watcher types (see	673	The class should provide implementations for all watcher types. See
439	L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib>	674	L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code)
440	(Source code) and so on for actual examples, use C<perldoc -m	675	and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to
441	AnyEvent::Impl::Glib> to see the sources).	676	see the sources.
442		677
		678	If you don't provide C<signal> and C<child> watchers than AnyEvent will
		679	provide suitable (hopefully) replacements.
		680
443	The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt)	681	The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt)
444	uses the above line as-is. An interface isn't included in AnyEvent	682	terminal emulator uses the above line as-is. An interface isn't included
445	because it doesn't make sense outside the embedded interpreter inside	683	in AnyEvent because it doesn't make sense outside the embedded interpreter
446	I<rxvt-unicode>, and it is updated and maintained as part of the	684	inside I<rxvt-unicode>, and it is updated and maintained as part of the
447	I<rxvt-unicode> distribution.	685	I<rxvt-unicode> distribution.
448		686
449	I<rxvt-unicode> also cheats a bit by not providing blocking access to	687	I<rxvt-unicode> also cheats a bit by not providing blocking access to
450	condition variables: code blocking while waiting for a condition will	688	condition variables: code blocking while waiting for a condition will
451	C<die>. This still works with most modules/usages, and blocking calls must	689	C<die>. This still works with most modules/usages, and blocking calls must
452	not be in an interactive application, so it makes sense.	690	not be done in an interactive application, so it makes sense.
453		691
454	=head1 ENVIRONMENT VARIABLES	692	=head1 ENVIRONMENT VARIABLES
455		693
456	The following environment variables are used by this module:	694	The following environment variables are used by this module:
457		695
458	C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event	696	=over 4
459	model gets used.
460		697
		698	=item C<PERL_ANYEVENT_VERBOSE>
		699
		700	By default, AnyEvent will be completely silent except in fatal
		701	conditions. You can set this environment variable to make AnyEvent more
		702	talkative.
		703
		704	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		705	conditions, such as not being able to load the event model specified by
		706	C<PERL_ANYEVENT_MODEL>.
		707
		708	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		709	model it chooses.
		710
		711	=item C<PERL_ANYEVENT_MODEL>
		712
		713	This can be used to specify the event model to be used by AnyEvent, before
		714	autodetection and -probing kicks in. It must be a string consisting
		715	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		716	and the resulting module name is loaded and if the load was successful,
		717	used as event model. If it fails to load AnyEvent will proceed with
		718	autodetection and -probing.
		719
		720	This functionality might change in future versions.
		721
		722	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		723	could start your program like this:
		724
		725	PERL_ANYEVENT_MODEL=Perl perl ...
		726
		727	=back
		728
461	=head1 EXAMPLE	729	=head1 EXAMPLE PROGRAM
462		730
463	The following program uses an io watcher to read data from stdin, a timer	731	The following program uses an I/O watcher to read data from STDIN, a timer
464	to display a message once per second, and a condvar to exit the program	732	to display a message once per second, and a condition variable to quit the
465	when the user enters quit:	733	program when the user enters quit:
466		734
467	use AnyEvent;	735	use AnyEvent;
468		736
469	my $cv = AnyEvent->condvar;	737	my $cv = AnyEvent->condvar;
470		738
471	my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	739	my $io_watcher = AnyEvent->io (
		740	fh => \*STDIN,
		741	poll => 'r',
		742	cb => sub {
472	warn "io event <$_[0]>\n"; # will always output <r>	743	warn "io event <$_[0]>\n"; # will always output <r>
473	chomp (my $input = <STDIN>); # read a line	744	chomp (my $input = <STDIN>); # read a line
474	warn "read: $input\n"; # output what has been read	745	warn "read: $input\n"; # output what has been read
475	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	746	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i
		747	},
476	});	748	);
477		749
478	my $time_watcher; # can only be used once	750	my $time_watcher; # can only be used once
479		751
480	sub new_timer {	752	sub new_timer {
481	$timer = AnyEvent->timer (after => 1, cb => sub {	753	$timer = AnyEvent->timer (after => 1, cb => sub {
…		…
563	$txn->{finished}->wait;	835	$txn->{finished}->wait;
564	return $txn->{result};	836	return $txn->{result};
565		837
566	The actual code goes further and collects all errors (C<die>s, exceptions)	838	The actual code goes further and collects all errors (C<die>s, exceptions)
567	that occured during request processing. The C<result> method detects	839	that occured during request processing. The C<result> method detects
568	wether an exception as thrown (it is stored inside the $txn object)	840	whether an exception as thrown (it is stored inside the $txn object)
569	and just throws the exception, which means connection errors and other	841	and just throws the exception, which means connection errors and other
570	problems get reported tot he code that tries to use the result, not in a	842	problems get reported tot he code that tries to use the result, not in a
571	random callback.	843	random callback.
572		844
573	All of this enables the following usage styles:	845	All of this enables the following usage styles:
574		846
575	1. Blocking:	847	1. Blocking:
576		848
577	my $data = $fcp->client_get ($url);	849	my $data = $fcp->client_get ($url);
578		850
579	2. Blocking, but parallelizing:	851	2. Blocking, but running in parallel:
580		852
581	my @datas = map $_->result,	853	my @datas = map $_->result,
582	map $fcp->txn_client_get ($_),	854	map $fcp->txn_client_get ($_),
583	@urls;	855	@urls;
584		856
585	Both blocking examples work without the module user having to know	857	Both blocking examples work without the module user having to know
586	anything about events.	858	anything about events.
587		859
588	3a. Event-based in a main program, using any support Event module:	860	3a. Event-based in a main program, using any supported event module:
589		861
590	use Event;	862	use EV;
591		863
592	$fcp->txn_client_get ($url)->cb (sub {	864	$fcp->txn_client_get ($url)->cb (sub {
593	my $txn = shift;	865	my $txn = shift;
594	my $data = $txn->result;	866	my $data = $txn->result;
595	...	867	...
596	});	868	});
597		869
598	Event::loop;	870	EV::loop;
599		871
600	3b. The module user could use AnyEvent, too:	872	3b. The module user could use AnyEvent, too:
601		873
602	use AnyEvent;	874	use AnyEvent;
603		875
…		…
608	$quit->broadcast;	880	$quit->broadcast;
609	});	881	});
610		882
611	$quit->wait;	883	$quit->wait;
612		884
		885
		886	=head1 BENCHMARK
		887
		888	To give you an idea of the performance and overheads that AnyEvent adds
		889	over the event loops themselves (and to give you an impression of the
		890	speed of various event loops), here is a benchmark of various supported
		891	event models natively and with anyevent. The benchmark creates a lot of
		892	timers (with a zero timeout) and I/O watchers (watching STDOUT, a pty, to
		893	become writable, which it is), lets them fire exactly once and destroys
		894	them again.
		895
		896	Rewriting the benchmark to use many different sockets instead of using
		897	the same filehandle for all I/O watchers results in a much longer runtime
		898	(socket creation is expensive), but qualitatively the same figures, so it
		899	was not used.
		900
		901	=head2 Explanation of the columns
		902
		903	I<watcher> is the number of event watchers created/destroyed. Since
		904	different event models feature vastly different performances, each event
		905	loop was given a number of watchers so that overall runtime is acceptable
		906	and similar between tested event loop (and keep them from crashing): Glib
		907	would probably take thousands of years if asked to process the same number
		908	of watchers as EV in this benchmark.
		909
		910	I<bytes> is the number of bytes (as measured by the resident set size,
		911	RSS) consumed by each watcher. This method of measuring captures both C
		912	and Perl-based overheads.
		913
		914	I<create> is the time, in microseconds (millionths of seconds), that it
		915	takes to create a single watcher. The callback is a closure shared between
		916	all watchers, to avoid adding memory overhead. That means closure creation
		917	and memory usage is not included in the figures.
		918
		919	I<invoke> is the time, in microseconds, used to invoke a simple
		920	callback. The callback simply counts down a Perl variable and after it was
		921	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to
		922	signal the end of this phase.
		923
		924	I<destroy> is the time, in microseconds, that it takes to destroy a single
		925	watcher.
		926
		927	=head2 Results
		928
		929	name watchers bytes create invoke destroy comment
		930	EV/EV 400000 244 0.56 0.46 0.31 EV native interface
		931	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers
		932	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal
		933	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation
		934	Event/Event 16000 516 31.88 31.30 0.85 Event native interface
		935	Event/Any 16000 936 39.17 33.63 1.43 Event + AnyEvent watchers
		936	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour
		937	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers
		938	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event
		939	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select
		940
		941	=head2 Discussion
		942
		943	The benchmark does I<not> measure scalability of the event loop very
		944	well. For example, a select-based event loop (such as the pure perl one)
		945	can never compete with an event loop that uses epoll when the number of
		946	file descriptors grows high. In this benchmark, all events become ready at
		947	the same time, so select/poll-based implementations get an unnatural speed
		948	boost.
		949
		950	C<EV> is the sole leader regarding speed and memory use, which are both
		951	maximal/minimal, respectively. Even when going through AnyEvent, there are
		952	only two event loops that use slightly less memory (the C<Event> module
		953	natively and the pure perl backend), and no faster event models, not even
		954	C<Event> natively.
		955
		956	The pure perl implementation is hit in a few sweet spots (both the
		957	zero timeout and the use of a single fd hit optimisations in the perl
		958	interpreter and the backend itself, and all watchers become ready at the
		959	same time). Nevertheless this shows that it adds very little overhead in
		960	itself. Like any select-based backend its performance becomes really bad
		961	with lots of file descriptors (and few of them active), of course, but
		962	this was not subject of this benchmark.
		963
		964	The C<Event> module has a relatively high setup and callback invocation cost,
		965	but overall scores on the third place.
		966
		967	C<Glib>'s memory usage is quite a bit bit higher, but it features a
		968	faster callback invocation and overall ends up in the same class as
		969	C<Event>. However, Glib scales extremely badly, doubling the number of
		970	watchers increases the processing time by more than a factor of four,
		971	making it completely unusable when using larger numbers of watchers
		972	(note that only a single file descriptor was used in the benchmark, so
		973	inefficiencies of C<poll> do not account for this).
		974
		975	The C<Tk> adaptor works relatively well. The fact that it crashes with
		976	more than 2000 watchers is a big setback, however, as correctness takes
		977	precedence over speed. Nevertheless, its performance is surprising, as the
		978	file descriptor is dup()ed for each watcher. This shows that the dup()
		979	employed by some adaptors is not a big performance issue (it does incur a
		980	hidden memory cost inside the kernel, though, that is not reflected in the
		981	figures above).
		982
		983	C<POE>, regardless of underlying event loop (wether using its pure perl
		984	select-based backend or the Event module) shows abysmal performance and
		985	memory usage: Watchers use almost 30 times as much memory as EV watchers,
		986	and 10 times as much memory as both Event or EV via AnyEvent. Watcher
		987	invocation is almost 900 times slower than with AnyEvent's pure perl
		988	implementation. The design of the POE adaptor class in AnyEvent can not
		989	really account for this, as session creation overhead is small compared
		990	to execution of the state machine, which is coded pretty optimally within
		991	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.
		992
		993	=head2 Summary
		994
		995	Using EV through AnyEvent is faster than any other event loop, but most
		996	event loops have acceptable performance with or without AnyEvent.
		997
		998	The overhead AnyEvent adds is usually much smaller than the overhead of
		999	the actual event loop, only with extremely fast event loops such as the EV
		1000	adds AnyEvent significant overhead.
		1001
		1002	And you should simply avoid POE like the plague if you want performance or
		1003	reasonable memory usage.
		1004
		1005
		1006	=head1 FORK
		1007
		1008	Most event libraries are not fork-safe. The ones who are usually are
		1009	because they are so inefficient. Only L<EV> is fully fork-aware.
		1010
		1011	If you have to fork, you must either do so I<before> creating your first
		1012	watcher OR you must not use AnyEvent at all in the child.
		1013
		1014
		1015	=head1 SECURITY CONSIDERATIONS
		1016
		1017	AnyEvent can be forced to load any event model via
		1018	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to
		1019	execute arbitrary code or directly gain access, it can easily be used to
		1020	make the program hang or malfunction in subtle ways, as AnyEvent watchers
		1021	will not be active when the program uses a different event model than
		1022	specified in the variable.
		1023
		1024	You can make AnyEvent completely ignore this variable by deleting it
		1025	before the first watcher gets created, e.g. with a C<BEGIN> block:
		1026
		1027	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
		1028
		1029	use AnyEvent;
		1030
		1031
613	=head1 SEE ALSO	1032	=head1 SEE ALSO
614		1033
615	Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>.	1034	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,
		1035	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,
		1036	L<Event::Lib>, L<Qt>, L<POE>.
616		1037
		1038	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,
617	Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>.	1039	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,
		1040	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,
		1041	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.
618		1042
619	Nontrivial usage example: L<Net::FCP>.	1043	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.
620		1044
621	=head1	1045
		1046	=head1 AUTHOR
		1047
		1048	Marc Lehmann <schmorp@schmorp.de>
		1049	http://home.schmorp.de/
622		1050
623	=cut	1051	=cut
624		1052
625	1	1053	1
626		1054

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.36 by root, Fri Nov 16 09:13:11 2007 UTC vs. Revision 1.83 by root, Fri Apr 25 13:39:08 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.36 by root, Fri Nov 16 09:13:11 2007 UTC vs.
Revision 1.83 by root, Fri Apr 25 13:39:08 2008 UTC