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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.25 by root, Wed Apr 11 00:36:59 2007 UTC vs.
Revision 1.90 by root, Fri Apr 25 14:24:29 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
74	events. C<poll> must be a string that is either C<r> or C<w>, that creates	147	for events. C<poll> must be a string that is either C<r> or C<w>,
75	a watcher waiting for "r"eadable or "w"ritable events. C<cb> teh callback	148	which 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	Although the callback might get passed parameters, their value and
79	a socket you can have one r + one w, not any more (limitation comes from	153	presence is undefined and you cannot rely on them. Portable AnyEvent
80	Tk - if you are sure you are not using Tk this limitation is gone).	154	callbacks cannot use arguments passed to I/O watcher callbacks.
81		155
82	Filehandles will be kept alive, so as long as the watcher exists, the	156	The I/O watcher might use the underlying file descriptor or a copy of it.
83	filehandle exists, too.	157	You must not close a file handle as long as any watcher is active on the
		158	underlying file descriptor.
		159
		160	Some event loops issue spurious readyness notifications, so you should
		161	always use non-blocking calls when reading/writing from/to your file
		162	handles.
84		163
85	Example:	164	Example:
86		165
87	# wait for readability of STDIN, then read a line and disable the watcher	166	# 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 {	167	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
…		…
94	=head2 TIME WATCHERS	173	=head2 TIME WATCHERS
95		174
96	You can create a time watcher by calling the C<< AnyEvent->timer >>	175	You can create a time watcher by calling the C<< AnyEvent->timer >>
97	method with the following mandatory arguments:	176	method with the following mandatory arguments:
98		177
99	C<after> after how many seconds (fractions are supported) should the timer	178	C<after> specifies after how many seconds (fractional values are
100	activate. C<cb> the callback to invoke.	179	supported) the callback should be invoked. C<cb> is the callback to invoke
		180	in that case.
		181
		182	Although the callback might get passed parameters, their value and
		183	presence is undefined and you cannot rely on them. Portable AnyEvent
		184	callbacks cannot use arguments passed to time watcher callbacks.
101		185
102	The timer callback will be invoked at most once: if you want a repeating	186	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	187	timer you have to create a new watcher (this is a limitation by both Tk
104	and Glib).	188	and Glib).
105		189
…		…
109	my $w = AnyEvent->timer (after => 7.7, cb => sub {	193	my $w = AnyEvent->timer (after => 7.7, cb => sub {
110	warn "timeout\n";	194	warn "timeout\n";
111	});	195	});
112		196
113	# to cancel the timer:	197	# to cancel the timer:
114	undef $w	198	undef $w;
115		199
		200	Example 2:
		201
		202	# fire an event after 0.5 seconds, then roughly every second
		203	my $w;
		204
		205	my $cb = sub {
		206	# cancel the old timer while creating a new one
		207	$w = AnyEvent->timer (after => 1, cb => $cb);
		208	};
		209
		210	# start the "loop" by creating the first watcher
		211	$w = AnyEvent->timer (after => 0.5, cb => $cb);
		212
		213	=head3 TIMING ISSUES
		214
		215	There are two ways to handle timers: based on real time (relative, "fire
		216	in 10 seconds") and based on wallclock time (absolute, "fire at 12
		217	o'clock").
		218
		219	While most event loops expect timers to specified in a relative way, they
		220	use absolute time internally. This makes a difference when your clock
		221	"jumps", for example, when ntp decides to set your clock backwards from
		222	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to
		223	fire "after" a second might actually take six years to finally fire.
		224
		225	AnyEvent cannot compensate for this. The only event loop that is conscious
		226	about these issues is L<EV>, which offers both relative (ev_timer, based
		227	on true relative time) and absolute (ev_periodic, based on wallclock time)
		228	timers.
		229
		230	AnyEvent always prefers relative timers, if available, matching the
		231	AnyEvent API.
		232
		233	=head2 SIGNAL WATCHERS
		234
		235	You can watch for signals using a signal watcher, C<signal> is the signal
		236	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to
		237	be invoked whenever a signal occurs.
		238
		239	Although the callback might get passed parameters, their value and
		240	presence is undefined and you cannot rely on them. Portable AnyEvent
		241	callbacks cannot use arguments passed to signal watcher callbacks.
		242
		243	Multiple signal occurances can be clumped together into one callback
		244	invocation, and callback invocation will be synchronous. synchronous means
		245	that it might take a while until the signal gets handled by the process,
		246	but it is guarenteed not to interrupt any other callbacks.
		247
		248	The main advantage of using these watchers is that you can share a signal
		249	between multiple watchers.
		250
		251	This watcher might use C<%SIG>, so programs overwriting those signals
		252	directly will likely not work correctly.
		253
		254	Example: exit on SIGINT
		255
		256	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
		257
		258	=head2 CHILD PROCESS WATCHERS
		259
		260	You can also watch on a child process exit and catch its exit status.
		261
		262	The child process is specified by the C<pid> argument (if set to C<0>, it
		263	watches for any child process exit). The watcher will trigger as often
		264	as status change for the child are received. This works by installing a
		265	signal handler for C<SIGCHLD>. The callback will be called with the pid
		266	and exit status (as returned by waitpid), so unlike other watcher types,
		267	you I<can> rely on child watcher callback arguments.
		268
		269	There is a slight catch to child watchers, however: you usually start them
		270	I<after> the child process was created, and this means the process could
		271	have exited already (and no SIGCHLD will be sent anymore).
		272
		273	Not all event models handle this correctly (POE doesn't), but even for
		274	event models that I<do> handle this correctly, they usually need to be
		275	loaded before the process exits (i.e. before you fork in the first place).
		276
		277	This means you cannot create a child watcher as the very first thing in an
		278	AnyEvent program, you I<have> to create at least one watcher before you
		279	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
		280
		281	Example: fork a process and wait for it
		282
		283	my $done = AnyEvent->condvar;
		284
		285	AnyEvent::detect; # force event module to be initialised
		286
		287	my $pid = fork or exit 5;
		288
		289	my $w = AnyEvent->child (
		290	pid => $pid,
		291	cb => sub {
		292	my ($pid, $status) = @_;
		293	warn "pid $pid exited with status $status";
		294	$done->broadcast;
		295	},
		296	);
		297
		298	# do something else, then wait for process exit
		299	$done->wait;
		300
116	=head2 CONDITION WATCHERS	301	=head2 CONDITION VARIABLES
117		302
118	Condition watchers can be created by calling the C<< AnyEvent->condvar >>	303	Condition variables can be created by calling the C<< AnyEvent->condvar >>
119	method without any arguments.	304	method without any arguments.
120		305
121	A condition watcher watches for a condition - precisely that the C<<	306	A condition variable waits for a condition - precisely that the C<<
122	->broadcast >> method has been called.	307	->broadcast >> method has been called.
123		308
124	The watcher has only two methods:	309	They are very useful to signal that a condition has been fulfilled, for
		310	example, if you write a module that does asynchronous http requests,
		311	then a condition variable would be the ideal candidate to signal the
		312	availability of results.
		313
		314	You can also use condition variables to block your main program until
		315	an event occurs - for example, you could C<< ->wait >> in your main
		316	program until the user clicks the Quit button in your app, which would C<<
		317	->broadcast >> the "quit" event.
		318
		319	Note that condition variables recurse into the event loop - if you have
		320	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you
		321	lose. Therefore, condition variables are good to export to your caller, but
		322	you should avoid making a blocking wait yourself, at least in callbacks,
		323	as this asks for trouble.
		324
		325	This object has two methods:
125		326
126	=over 4	327	=over 4
127		328
128	=item $cv->wait	329	=item $cv->wait
129		330
130	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	331	Wait (blocking if necessary) until the C<< ->broadcast >> method has been
131	called on c<$cv>, while servicing other watchers normally.	332	called on c<$cv>, while servicing other watchers normally.
132		333
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	334	You can only wait once on a condition - additional calls will return
141	immediately.	335	immediately.
142		336
		337	Not all event models support a blocking wait - some die in that case
		338	(programs might want to do that to stay interactive), so I<if you are
		339	using this from a module, never require a blocking wait>, but let the
		340	caller decide whether the call will block or not (for example, by coupling
		341	condition variables with some kind of request results and supporting
		342	callbacks so the caller knows that getting the result will not block,
		343	while still suppporting blocking waits if the caller so desires).
		344
		345	Another reason I<never> to C<< ->wait >> in a module is that you cannot
		346	sensibly have two C<< ->wait >>'s in parallel, as that would require
		347	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
		348	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and
		349	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
		350	from different coroutines, however).
		351
143	=item $cv->broadcast	352	=item $cv->broadcast
144		353
145	Flag the condition as ready - a running C<< ->wait >> and all further	354	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	355	calls to C<wait> will (eventually) return after this method has been
147	is waiting the broadcast will be remembered..	356	called. If nobody is waiting the broadcast will be remembered..
		357
		358	=back
148		359
149	Example:	360	Example:
150		361
151	# wait till the result is ready	362	# wait till the result is ready
152	my $result_ready = AnyEvent->condvar;	363	my $result_ready = AnyEvent->condvar;
153		364
154	# do something such as adding a timer	365	# do something such as adding a timer
155	# or socket watcher the calls $result_ready->broadcast	366	# or socket watcher the calls $result_ready->broadcast
156	# when the "result" is ready.	367	# when the "result" is ready.
		368	# in this case, we simply use a timer:
		369	my $w = AnyEvent->timer (
		370	after => 1,
		371	cb => sub { $result_ready->broadcast },
		372	);
157		373
		374	# this "blocks" (while handling events) till the watcher
		375	# calls broadcast
158	$result_ready->wait;	376	$result_ready->wait;
159		377
160	=back	378	=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. The watcher will only trigger once. This works by
180	installing a signal handler for C<SIGCHLD>.
181
182	Example: wait for pid 1333
183
184	my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" });
185
186	=head1 GLOBALS
187		379
188	=over 4	380	=over 4
189		381
190	=item $AnyEvent::MODEL	382	=item $AnyEvent::MODEL
191		383
…		…
195	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	387	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
196	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	388	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
197		389
198	The known classes so far are:	390	The known classes so far are:
199		391
200	AnyEvent::Impl::Coro based on Coro::Event, best choise.	392	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
		393	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
		394	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
201	AnyEvent::Impl::Event based on Event, also best choice :)	395	AnyEvent::Impl::Event based on Event, second best choice.
202	AnyEvent::Impl::Glib based on Glib, second-best choice.	396	AnyEvent::Impl::Glib based on Glib, third-best choice.
		397	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
203	AnyEvent::Impl::Tk based on Tk, very bad choice.	398	AnyEvent::Impl::Tk based on Tk, very bad choice.
204	AnyEvent::Impl::Perl pure-perl implementation, inefficient.	399	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
		400	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		401	AnyEvent::Impl::POE based on POE, not generic enough for full support.
		402
		403	There is no support for WxWidgets, as WxWidgets has no support for
		404	watching file handles. However, you can use WxWidgets through the
		405	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
		406	second, which was considered to be too horrible to even consider for
		407	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
		408	it's adaptor.
		409
		410	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
		411	autodetecting them.
205		412
206	=item AnyEvent::detect	413	=item AnyEvent::detect
207		414
208	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if	415	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
209	necessary. You should only call this function right before you would have	416	if necessary. You should only call this function right before you would
210	created an AnyEvent watcher anyway, that is, very late at runtime.	417	have created an AnyEvent watcher anyway, that is, as late as possible at
		418	runtime.
211		419
212	=back	420	=back
213		421
214	=head1 WHAT TO DO IN A MODULE	422	=head1 WHAT TO DO IN A MODULE
215		423
216	As a module author, you should "use AnyEvent" and call AnyEvent methods	424	As a module author, you should C<use AnyEvent> and call AnyEvent methods
217	freely, but you should not load a specific event module or rely on it.	425	freely, but you should not load a specific event module or rely on it.
218		426
219	Be careful when you create watchers in the module body - Anyevent will	427	Be careful when you create watchers in the module body - AnyEvent will
220	decide which event module to use as soon as the first method is called, so	428	decide which event module to use as soon as the first method is called, so
221	by calling AnyEvent in your module body you force the user of your module	429	by calling AnyEvent in your module body you force the user of your module
222	to load the event module first.	430	to load the event module first.
223		431
		432	Never call C<< ->wait >> on a condition variable unless you I<know> that
		433	the C<< ->broadcast >> method has been called on it already. This is
		434	because it will stall the whole program, and the whole point of using
		435	events is to stay interactive.
		436
		437	It is fine, however, to call C<< ->wait >> when the user of your module
		438	requests it (i.e. if you create a http request object ad have a method
		439	called C<results> that returns the results, it should call C<< ->wait >>
		440	freely, as the user of your module knows what she is doing. always).
		441
224	=head1 WHAT TO DO IN THE MAIN PROGRAM	442	=head1 WHAT TO DO IN THE MAIN PROGRAM
225		443
226	There will always be a single main program - the only place that should	444	There will always be a single main program - the only place that should
227	dictate which event model to use.	445	dictate which event model to use.
228		446
229	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	447	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
230	do anything special and let AnyEvent decide which implementation to chose.	448	do anything special (it does not need to be event-based) and let AnyEvent
		449	decide which implementation to chose if some module relies on it.
231		450
232	If the main program relies on a specific event model (for example, in Gtk2	451	If the main program relies on a specific event model. For example, in
233	programs you have to rely on either Glib or Glib::Event), you should load	452	Gtk2 programs you have to rely on the Glib module. You should load the
234	it before loading AnyEvent or any module that uses it, generally, as early	453	event module before loading AnyEvent or any module that uses it: generally
235	as possible. The reason is that modules might create watchers when they	454	speaking, you should load it as early as possible. The reason is that
236	are loaded, and AnyEvent will decide on the event model to use as soon as	455	modules might create watchers when they are loaded, and AnyEvent will
237	it creates watchers, and it might chose the wrong one unless you load the	456	decide on the event model to use as soon as it creates watchers, and it
238	correct one yourself.	457	might chose the wrong one unless you load the correct one yourself.
239		458
240	You can chose to use a rather inefficient pure-perl implementation by	459	You can chose to use a rather inefficient pure-perl implementation by
241	loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is	460	loading the C<AnyEvent::Impl::Perl> module, which gives you similar
242	generally better.	461	behaviour everywhere, but letting AnyEvent chose is generally better.
243		462
244	=cut	463	=cut
245		464
246	package AnyEvent;	465	package AnyEvent;
247		466
248	no warnings;	467	no warnings;
249	use strict;	468	use strict;
250		469
251	use Carp;	470	use Carp;
252		471
253	our $VERSION = '2.52';	472	our $VERSION = '3.3';
254	our $MODEL;	473	our $MODEL;
255		474
256	our $AUTOLOAD;	475	our $AUTOLOAD;
257	our @ISA;	476	our @ISA;
258		477
259	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	478	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
260		479
261	our @REGISTRY;	480	our @REGISTRY;
262		481
263	my @models = (	482	my @models = (
		483	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
264	[Coro::Event:: => AnyEvent::Impl::Coro::],	484	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
		485	[EV:: => AnyEvent::Impl::EV::],
265	[Event:: => AnyEvent::Impl::Event::],	486	[Event:: => AnyEvent::Impl::Event::],
266	[Glib:: => AnyEvent::Impl::Glib::],	487	[Glib:: => AnyEvent::Impl::Glib::],
267	[Tk:: => AnyEvent::Impl::Tk::],	488	[Tk:: => AnyEvent::Impl::Tk::],
		489	[Wx:: => AnyEvent::Impl::POE::],
		490	[Prima:: => AnyEvent::Impl::POE::],
268	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	491	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
		492	# everything below here will not be autoprobed as the pureperl backend should work everywhere
		493	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		494	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		495	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
269	);	496	);
270		497
271	our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY);	498	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);
272		499
273	sub detect() {	500	sub detect() {
274	unless ($MODEL) {	501	unless ($MODEL) {
275	no strict 'refs';	502	no strict 'refs';
276		503
		504	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
		505	my $model = "AnyEvent::Impl::$1";
		506	if (eval "require $model") {
		507	$MODEL = $model;
		508	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;
		509	} else {
		510	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;
		511	}
		512	}
		513
277	# check for already loaded models	514	# check for already loaded models
		515	unless ($MODEL) {
278	for (@REGISTRY, @models) {	516	for (@REGISTRY, @models) {
279	my ($package, $model) = @$_;	517	my ($package, $model) = @$_;
280	if (${"$package\::VERSION"} > 0) {	518	if (${"$package\::VERSION"} > 0) {
281	if (eval "require $model") {	519	if (eval "require $model") {
282	$MODEL = $model;	520	$MODEL = $model;
283	warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1;	521	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
284	last;	522	last;
		523	}
285	}	524	}
286	}	525	}
287	}
288		526
289	unless ($MODEL) {	527	unless ($MODEL) {
290	# try to load a model	528	# try to load a model
291		529
292	for (@REGISTRY, @models) {	530	for (@REGISTRY, @models) {
293	my ($package, $model) = @$_;	531	my ($package, $model) = @$_;
294	if (eval "require $package"	532	if (eval "require $package"
295	and ${"$package\::VERSION"} > 0	533	and ${"$package\::VERSION"} > 0
296	and eval "require $model") {	534	and eval "require $model") {
297	$MODEL = $model;	535	$MODEL = $model;
298	warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1;	536	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
299	last;	537	last;
		538	}
300	}	539	}
		540
		541	$MODEL
		542	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.";
301	}	543	}
302
303	$MODEL
304	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Event (or Coro+Event), Glib or Tk.";
305	}	544	}
306		545
307	unshift @ISA, $MODEL;	546	unshift @ISA, $MODEL;
308	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	547	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
309	}	548	}
…		…
367		606
368	# default implementation for ->child	607	# default implementation for ->child
369		608
370	our %PID_CB;	609	our %PID_CB;
371	our $CHLD_W;	610	our $CHLD_W;
		611	our $CHLD_DELAY_W;
372	our $PID_IDLE;	612	our $PID_IDLE;
373	our $WNOHANG;	613	our $WNOHANG;
374		614
375	sub _child_wait {	615	sub _child_wait {
376	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	616	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
377	$_->() for values %{ (delete $PID_CB{$pid}) \|\| {} };	617	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),
		618	(values %{ $PID_CB{0} \|\| {} });
378	}	619	}
379		620
380	undef $PID_IDLE;	621	undef $PID_IDLE;
381	}	622	}
382		623
		624	sub _sigchld {
		625	# make sure we deliver these changes "synchronous" with the event loop.
		626	$CHLD_DELAY_W \|\|= AnyEvent->timer (after => 0, cb => sub {
		627	undef $CHLD_DELAY_W;
		628	&_child_wait;
		629	});
		630	}
		631
383	sub child {	632	sub child {
384	my (undef, %arg) = @_;	633	my (undef, %arg) = @_;
385		634
386	my $pid = uc $arg{pid}	635	defined (my $pid = $arg{pid} + 0)
387	or Carp::croak "required option 'pid' is missing";	636	or Carp::croak "required option 'pid' is missing";
388		637
389	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	638	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
390		639
391	unless ($WNOHANG) {	640	unless ($WNOHANG) {
392	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	641	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;
393	}	642	}
394		643
395	unless ($CHLD_W) {	644	unless ($CHLD_W) {
396	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_child_wait);	645	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
397	# child could be a zombie already	646	# child could be a zombie already, so make at least one round
398	$PID_IDLE \|\|= AnyEvent->timer (after => 0, cb => \&_child_wait);	647	&_sigchld;
399	}	648	}
400		649
401	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	650	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"
402	}	651	}
403		652
…		…
409		658
410	undef $CHLD_W unless keys %PID_CB;	659	undef $CHLD_W unless keys %PID_CB;
411	}	660	}
412		661
413	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	662	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
		663
		664	This is an advanced topic that you do not normally need to use AnyEvent in
		665	a module. This section is only of use to event loop authors who want to
		666	provide AnyEvent compatibility.
414		667
415	If you need to support another event library which isn't directly	668	If you need to support another event library which isn't directly
416	supported by AnyEvent, you can supply your own interface to it by	669	supported by AnyEvent, you can supply your own interface to it by
417	pushing, before the first watcher gets created, the package name of	670	pushing, before the first watcher gets created, the package name of
418	the event module and the package name of the interface to use onto	671	the event module and the package name of the interface to use onto
419	C<@AnyEvent::REGISTRY>. You can do that before and even without loading	672	C<@AnyEvent::REGISTRY>. You can do that before and even without loading
420	AnyEvent.	673	AnyEvent, so it is reasonably cheap.
421		674
422	Example:	675	Example:
423		676
424	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];	677	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
425		678
426	This tells AnyEvent to (literally) use the C<urxvt::anyevent::>	679	This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
427	package/class when it finds the C<urxvt> package/module is loaded. When	680	package/class when it finds the C<urxvt> package/module is already loaded.
		681
428	AnyEvent is loaded and asked to find a suitable event model, it will	682	When AnyEvent is loaded and asked to find a suitable event model, it
429	first check for the presence of urxvt.	683	will first check for the presence of urxvt by trying to C<use> the
		684	C<urxvt::anyevent> module.
430		685
431	The class should provide implementations for all watcher types (see	686	The class should provide implementations for all watcher types. See
432	L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib>	687	L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code)
433	(Source code) and so on for actual examples, use C<perldoc -m	688	and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to
434	AnyEvent::Impl::Glib> to see the sources).	689	see the sources.
435		690
		691	If you don't provide C<signal> and C<child> watchers than AnyEvent will
		692	provide suitable (hopefully) replacements.
		693
436	The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt)	694	The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt)
437	uses the above line as-is. An interface isn't included in AnyEvent	695	terminal emulator uses the above line as-is. An interface isn't included
438	because it doesn't make sense outside the embedded interpreter inside	696	in AnyEvent because it doesn't make sense outside the embedded interpreter
439	I<rxvt-unicode>, and it is updated and maintained as part of the	697	inside I<rxvt-unicode>, and it is updated and maintained as part of the
440	I<rxvt-unicode> distribution.	698	I<rxvt-unicode> distribution.
441		699
442	I<rxvt-unicode> also cheats a bit by not providing blocking access to	700	I<rxvt-unicode> also cheats a bit by not providing blocking access to
443	condition variables: code blocking while waiting for a condition will	701	condition variables: code blocking while waiting for a condition will
444	C<die>. This still works with most modules/usages, and blocking calls must	702	C<die>. This still works with most modules/usages, and blocking calls must
445	not be in an interactive application, so it makes sense.	703	not be done in an interactive application, so it makes sense.
446		704
447	=head1 ENVIRONMENT VARIABLES	705	=head1 ENVIRONMENT VARIABLES
448		706
449	The following environment variables are used by this module:	707	The following environment variables are used by this module:
450		708
451	C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event	709	=over 4
452	model gets used.
453		710
		711	=item C<PERL_ANYEVENT_VERBOSE>
		712
		713	By default, AnyEvent will be completely silent except in fatal
		714	conditions. You can set this environment variable to make AnyEvent more
		715	talkative.
		716
		717	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		718	conditions, such as not being able to load the event model specified by
		719	C<PERL_ANYEVENT_MODEL>.
		720
		721	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		722	model it chooses.
		723
		724	=item C<PERL_ANYEVENT_MODEL>
		725
		726	This can be used to specify the event model to be used by AnyEvent, before
		727	autodetection and -probing kicks in. It must be a string consisting
		728	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		729	and the resulting module name is loaded and if the load was successful,
		730	used as event model. If it fails to load AnyEvent will proceed with
		731	autodetection and -probing.
		732
		733	This functionality might change in future versions.
		734
		735	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		736	could start your program like this:
		737
		738	PERL_ANYEVENT_MODEL=Perl perl ...
		739
		740	=back
		741
454	=head1 EXAMPLE	742	=head1 EXAMPLE PROGRAM
455		743
456	The following program uses an io watcher to read data from stdin, a timer	744	The following program uses an I/O watcher to read data from STDIN, a timer
457	to display a message once per second, and a condvar to exit the program	745	to display a message once per second, and a condition variable to quit the
458	when the user enters quit:	746	program when the user enters quit:
459		747
460	use AnyEvent;	748	use AnyEvent;
461		749
462	my $cv = AnyEvent->condvar;	750	my $cv = AnyEvent->condvar;
463		751
464	my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	752	my $io_watcher = AnyEvent->io (
		753	fh => \*STDIN,
		754	poll => 'r',
		755	cb => sub {
465	warn "io event <$_[0]>\n"; # will always output <r>	756	warn "io event <$_[0]>\n"; # will always output <r>
466	chomp (my $input = <STDIN>); # read a line	757	chomp (my $input = <STDIN>); # read a line
467	warn "read: $input\n"; # output what has been read	758	warn "read: $input\n"; # output what has been read
468	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	759	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i
		760	},
469	});	761	);
470		762
471	my $time_watcher; # can only be used once	763	my $time_watcher; # can only be used once
472		764
473	sub new_timer {	765	sub new_timer {
474	$timer = AnyEvent->timer (after => 1, cb => sub {	766	$timer = AnyEvent->timer (after => 1, cb => sub {
…		…
556	$txn->{finished}->wait;	848	$txn->{finished}->wait;
557	return $txn->{result};	849	return $txn->{result};
558		850
559	The actual code goes further and collects all errors (C<die>s, exceptions)	851	The actual code goes further and collects all errors (C<die>s, exceptions)
560	that occured during request processing. The C<result> method detects	852	that occured during request processing. The C<result> method detects
561	wether an exception as thrown (it is stored inside the $txn object)	853	whether an exception as thrown (it is stored inside the $txn object)
562	and just throws the exception, which means connection errors and other	854	and just throws the exception, which means connection errors and other
563	problems get reported tot he code that tries to use the result, not in a	855	problems get reported tot he code that tries to use the result, not in a
564	random callback.	856	random callback.
565		857
566	All of this enables the following usage styles:	858	All of this enables the following usage styles:
567		859
568	1. Blocking:	860	1. Blocking:
569		861
570	my $data = $fcp->client_get ($url);	862	my $data = $fcp->client_get ($url);
571		863
572	2. Blocking, but parallelizing:	864	2. Blocking, but running in parallel:
573		865
574	my @datas = map $_->result,	866	my @datas = map $_->result,
575	map $fcp->txn_client_get ($_),	867	map $fcp->txn_client_get ($_),
576	@urls;	868	@urls;
577		869
578	Both blocking examples work without the module user having to know	870	Both blocking examples work without the module user having to know
579	anything about events.	871	anything about events.
580		872
581	3a. Event-based in a main program, using any support Event module:	873	3a. Event-based in a main program, using any supported event module:
582		874
583	use Event;	875	use EV;
584		876
585	$fcp->txn_client_get ($url)->cb (sub {	877	$fcp->txn_client_get ($url)->cb (sub {
586	my $txn = shift;	878	my $txn = shift;
587	my $data = $txn->result;	879	my $data = $txn->result;
588	...	880	...
589	});	881	});
590		882
591	Event::loop;	883	EV::loop;
592		884
593	3b. The module user could use AnyEvent, too:	885	3b. The module user could use AnyEvent, too:
594		886
595	use AnyEvent;	887	use AnyEvent;
596		888
…		…
601	$quit->broadcast;	893	$quit->broadcast;
602	});	894	});
603		895
604	$quit->wait;	896	$quit->wait;
605		897
		898
		899	=head1 BENCHMARK
		900
		901	To give you an idea of the performance and overheads that AnyEvent adds
		902	over the event loops themselves (and to give you an impression of the
		903	speed of various event loops), here is a benchmark of various supported
		904	event models natively and with anyevent. The benchmark creates a lot of
		905	timers (with a zero timeout) and I/O watchers (watching STDOUT, a pty, to
		906	become writable, which it is), lets them fire exactly once and destroys
		907	them again.
		908
		909	Rewriting the benchmark to use many different sockets instead of using
		910	the same filehandle for all I/O watchers results in a much longer runtime
		911	(socket creation is expensive), but qualitatively the same figures, so it
		912	was not used.
		913
		914	=head2 Explanation of the columns
		915
		916	I<watcher> is the number of event watchers created/destroyed. Since
		917	different event models feature vastly different performances, each event
		918	loop was given a number of watchers so that overall runtime is acceptable
		919	and similar between tested event loop (and keep them from crashing): Glib
		920	would probably take thousands of years if asked to process the same number
		921	of watchers as EV in this benchmark.
		922
		923	I<bytes> is the number of bytes (as measured by the resident set size,
		924	RSS) consumed by each watcher. This method of measuring captures both C
		925	and Perl-based overheads.
		926
		927	I<create> is the time, in microseconds (millionths of seconds), that it
		928	takes to create a single watcher. The callback is a closure shared between
		929	all watchers, to avoid adding memory overhead. That means closure creation
		930	and memory usage is not included in the figures.
		931
		932	I<invoke> is the time, in microseconds, used to invoke a simple
		933	callback. The callback simply counts down a Perl variable and after it was
		934	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to
		935	signal the end of this phase.
		936
		937	I<destroy> is the time, in microseconds, that it takes to destroy a single
		938	watcher.
		939
		940	=head2 Results
		941
		942	name watchers bytes create invoke destroy comment
		943	EV/EV 400000 244 0.56 0.46 0.31 EV native interface
		944	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers
		945	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal
		946	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation
		947	Event/Event 16000 516 31.88 31.30 0.85 Event native interface
		948	Event/Any 16000 936 39.17 33.63 1.43 Event + AnyEvent watchers
		949	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour
		950	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers
		951	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event
		952	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select
		953
		954	=head2 Discussion
		955
		956	The benchmark does I<not> measure scalability of the event loop very
		957	well. For example, a select-based event loop (such as the pure perl one)
		958	can never compete with an event loop that uses epoll when the number of
		959	file descriptors grows high. In this benchmark, all events become ready at
		960	the same time, so select/poll-based implementations get an unnatural speed
		961	boost.
		962
		963	C<EV> is the sole leader regarding speed and memory use, which are both
		964	maximal/minimal, respectively. Even when going through AnyEvent, it uses
		965	far less memory than any other event loop and is still faster than Event
		966	natively.
		967
		968	The pure perl implementation is hit in a few sweet spots (both the
		969	constant timeout and the use of a single fd hit optimisations in the perl
		970	interpreter and the backend itself). Nevertheless this shows that it
		971	adds very little overhead in itself. Like any select-based backend its
		972	performance becomes really bad with lots of file descriptors (and few of
		973	them active), of course, but this was not subject of this benchmark.
		974
		975	The C<Event> module has a relatively high setup and callback invocation
		976	cost, but overall scores in on the third place.
		977
		978	C<Glib>'s memory usage is quite a bit higher, but it features a
		979	faster callback invocation and overall ends up in the same class as
		980	C<Event>. However, Glib scales extremely badly, doubling the number of
		981	watchers increases the processing time by more than a factor of four,
		982	making it completely unusable when using larger numbers of watchers
		983	(note that only a single file descriptor was used in the benchmark, so
		984	inefficiencies of C<poll> do not account for this).
		985
		986	The C<Tk> adaptor works relatively well. The fact that it crashes with
		987	more than 2000 watchers is a big setback, however, as correctness takes
		988	precedence over speed. Nevertheless, its performance is surprising, as the
		989	file descriptor is dup()ed for each watcher. This shows that the dup()
		990	employed by some adaptors is not a big performance issue (it does incur a
		991	hidden memory cost inside the kernel which is not reflected in the figures
		992	above).
		993
		994	C<POE>, regardless of underlying event loop (whether using its pure
		995	perl select-based backend or the Event module, the POE-EV backend
		996	couldn't be tested because it wasn't working) shows abysmal performance
		997	and memory usage: Watchers use almost 30 times as much memory as
		998	EV watchers, and 10 times as much memory as Event (the high memory
		999	requirements are caused by requiring a session for each watcher). Watcher
		1000	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1001	implementation. The design of the POE adaptor class in AnyEvent can not
		1002	really account for this, as session creation overhead is small compared
		1003	to execution of the state machine, which is coded pretty optimally within
		1004	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.
		1005
		1006	=head2 Summary
		1007
		1008	=over 4
		1009
		1010	=item * Using EV through AnyEvent is faster than any other event loop
		1011	(even when used without AnyEvent), but most event loops have acceptable
		1012	performance with or without AnyEvent.
		1013
		1014	=item * The overhead AnyEvent adds is usually much smaller than the overhead of
		1015	the actual event loop, only with extremely fast event loops such as EV
		1016	adds AnyEvent significant overhead.
		1017
		1018	=item * You should avoid POE like the plague if you want performance or
		1019	reasonable memory usage.
		1020
		1021	=back
		1022
		1023
		1024	=head1 FORK
		1025
		1026	Most event libraries are not fork-safe. The ones who are usually are
		1027	because they are so inefficient. Only L<EV> is fully fork-aware.
		1028
		1029	If you have to fork, you must either do so I<before> creating your first
		1030	watcher OR you must not use AnyEvent at all in the child.
		1031
		1032
		1033	=head1 SECURITY CONSIDERATIONS
		1034
		1035	AnyEvent can be forced to load any event model via
		1036	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to
		1037	execute arbitrary code or directly gain access, it can easily be used to
		1038	make the program hang or malfunction in subtle ways, as AnyEvent watchers
		1039	will not be active when the program uses a different event model than
		1040	specified in the variable.
		1041
		1042	You can make AnyEvent completely ignore this variable by deleting it
		1043	before the first watcher gets created, e.g. with a C<BEGIN> block:
		1044
		1045	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
		1046
		1047	use AnyEvent;
		1048
		1049
606	=head1 SEE ALSO	1050	=head1 SEE ALSO
607		1051
608	Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>.	1052	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,
		1053	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,
		1054	L<Event::Lib>, L<Qt>, L<POE>.
609		1055
		1056	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,
610	Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>.	1057	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,
		1058	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,
		1059	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.
611		1060
612	Nontrivial usage example: L<Net::FCP>.	1061	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.
613		1062
614	=head1	1063
		1064	=head1 AUTHOR
		1065
		1066	Marc Lehmann <schmorp@schmorp.de>
		1067	http://home.schmorp.de/
615		1068
616	=cut	1069	=cut
617		1070
618	1	1071	1
619		1072

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.25 by root, Wed Apr 11 00:36:59 2007 UTC vs. Revision 1.90 by root, Fri Apr 25 14:24:29 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.25 by root, Wed Apr 11 00:36:59 2007 UTC vs.
Revision 1.90 by root, Fri Apr 25 14:24:29 2008 UTC