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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.6 by root, Mon Dec 19 17:03:29 2005 UTC vs.
Revision 1.82 by root, Fri Apr 25 13:32:39 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 - 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
11	my $w = AnyEvent->io (fh => ..., poll => "[rw]+", cb => sub {	11	my $w = AnyEvent->io (fh => $fh, poll => "r\|w", cb => sub {
12	my ($poll_got) = @_;
13	...	12	...
14	});	13	});
15
16	- only one io watcher per $fh and $poll type is allowed
17	(i.e. on a socket you can have one r + one w or one rw
18	watcher, not any more.
19
20	- AnyEvent will keep filehandles alive, so as long as the watcher exists,
21	the filehandle exists.
22		14
23	my $w = AnyEvent->timer (after => $seconds, cb => sub {	15	my $w = AnyEvent->timer (after => $seconds, cb => sub {
24	...	16	...
25	});	17	});
26		18
27	- io and time watchers get canceled whenever $w is destroyed, so keep a copy	19	my $w = AnyEvent->condvar; # stores whether a condition was flagged
28
29	- timers can only be used once and must be recreated for repeated operation
30
31	my $w = AnyEvent->condvar; # kind of main loop replacement
32	$w->wait; # enters main loop till $condvar gets ->broadcast	20	$w->wait; # enters "main loop" till $condvar gets ->broadcast
33	$w->broadcast; # wake up current and all future wait's	21	$w->broadcast; # wake up current and all future wait's
34		22
35	- condvars are used to give blocking behaviour when neccessary. Create	23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
36	a condvar for any "request" or "event" your module might create, C<<	24
37	->broadcast >> it when the event happens and provide a function that calls	25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
38	C<< ->wait >> for it. See the examples below.	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
39		71
40	=head1 DESCRIPTION	72	=head1 DESCRIPTION
41		73
42	L<AnyEvent> provides an identical interface to multiple event loops. This	74	L<AnyEvent> provides an identical interface to multiple event loops. This
43	allows module authors to utilizy an event loop without forcing module	75	allows module authors to utilise an event loop without forcing module
44	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
45	peacefully at any one time).	77	peacefully at any one time).
46		78
47	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>
48	module.	80	module.
49		81
50	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
51	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
52	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>,
53	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>,
54	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
55	used. If still none could be found, it will issue an error.	87	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
		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.
		92
		93	Because AnyEvent first checks for modules that are already loaded, loading
		94	an event model explicitly before first using AnyEvent will likely make
		95	that model the default. For example:
		96
		97	use Tk;
		98	use AnyEvent;
		99
		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...
		105
		106	The pure-perl implementation of AnyEvent is called
		107	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
		108	explicitly.
		109
		110	=head1 WATCHERS
		111
		112	AnyEvent has the central concept of a I<watcher>, which is an object that
		113	stores relevant data for each kind of event you are waiting for, such as
		114	the callback to call, the filehandle to watch, etc.
		115
		116	These watchers are normal Perl objects with normal Perl lifetime. After
		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
		121	To disable the watcher you have to destroy it (e.g. by setting the
		122	variable you store it in to C<undef> or otherwise deleting all references
		123	to it).
		124
		125	All watchers are created by calling a method on the C<AnyEvent> class.
		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
		141	=head2 I/O WATCHERS
		142
		143	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
		144	with the following mandatory key-value pairs as arguments:
		145
		146	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for
		147	events. C<poll> must be a string that is either C<r> or C<w>, which
		148	creates a watcher waiting for "r"eadable or "w"ritable events,
		149	respectively. C<cb> is the callback to invoke each time the file handle
		150	becomes ready.
		151
		152	The I/O watcher might use the underlying file descriptor or a copy of it.
		153	It is not allowed to close a file handle as long as any watcher is active
		154	on the underlying file descriptor.
		155
		156	Some event loops issue spurious readyness notifications, so you should
		157	always use non-blocking calls when reading/writing from/to your file
		158	handles.
		159
		160	Example:
		161
		162	# wait for readability of STDIN, then read a line and disable the watcher
		163	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		164	chomp (my $input = <STDIN>);
		165	warn "read: $input\n";
		166	undef $w;
		167	});
		168
		169	=head2 TIME WATCHERS
		170
		171	You can create a time watcher by calling the C<< AnyEvent->timer >>
		172	method with the following mandatory arguments:
		173
		174	C<after> specifies after how many seconds (fractional values are
		175	supported) should the timer activate. C<cb> the callback to invoke in that
		176	case.
		177
		178	The timer callback will be invoked at most once: if you want a repeating
		179	timer you have to create a new watcher (this is a limitation by both Tk
		180	and Glib).
		181
		182	Example:
		183
		184	# fire an event after 7.7 seconds
		185	my $w = AnyEvent->timer (after => 7.7, cb => sub {
		186	warn "timeout\n";
		187	});
		188
		189	# to cancel the timer:
		190	undef $w;
		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
		288	=head2 CONDITION VARIABLES
		289
		290	Condition variables can be created by calling the C<< AnyEvent->condvar >>
		291	method without any arguments.
		292
		293	A condition variable waits for a condition - precisely that the C<<
		294	->broadcast >> method has been called.
		295
		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:
56		313
57	=over 4	314	=over 4
58		315
		316	=item $cv->wait
		317
		318	Wait (blocking if necessary) until the C<< ->broadcast >> method has been
		319	called on c<$cv>, while servicing other watchers normally.
		320
		321	You can only wait once on a condition - additional calls will return
		322	immediately.
		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
		339	=item $cv->broadcast
		340
		341	Flag the condition as ready - a running C<< ->wait >> and all further
		342	calls to C<wait> will (eventually) return after this method has been
		343	called. If nobody is waiting the broadcast will be remembered..
		344
		345	=back
		346
		347	Example:
		348
		349	# wait till the result is ready
		350	my $result_ready = AnyEvent->condvar;
		351
		352	# do something such as adding a timer
		353	# or socket watcher the calls $result_ready->broadcast
		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	);
		360
		361	# this "blocks" (while handling events) till the watcher
		362	# calls broadcast
		363	$result_ready->wait;
		364
		365	=head1 GLOBAL VARIABLES AND FUNCTIONS
		366
		367	=over 4
		368
		369	=item $AnyEvent::MODEL
		370
		371	Contains C<undef> until the first watcher is being created. Then it
		372	contains the event model that is being used, which is the name of the
		373	Perl class implementing the model. This class is usually one of the
		374	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
		375	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
		376
		377	The known classes so far are:
		378
		379	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
		380	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
		381	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
		382	AnyEvent::Impl::Event based on Event, second best choice.
		383	AnyEvent::Impl::Glib based on Glib, third-best choice.
		384	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
		385	AnyEvent::Impl::Tk based on Tk, very bad choice.
		386	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
		387	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		388	AnyEvent::Impl::POE based on POE, not generic enough for full support.
		389
		390	There is no support for WxWidgets, as WxWidgets has no support for
		391	watching file handles. However, you can use WxWidgets through the
		392	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
		393	second, which was considered to be too horrible to even consider for
		394	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
		395	it's adaptor.
		396
		397	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
		398	autodetecting them.
		399
		400	=item AnyEvent::detect
		401
		402	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
		403	if necessary. You should only call this function right before you would
		404	have created an AnyEvent watcher anyway, that is, as late as possible at
		405	runtime.
		406
		407	=back
		408
		409	=head1 WHAT TO DO IN A MODULE
		410
		411	As a module author, you should C<use AnyEvent> and call AnyEvent methods
		412	freely, but you should not load a specific event module or rely on it.
		413
		414	Be careful when you create watchers in the module body - AnyEvent will
		415	decide which event module to use as soon as the first method is called, so
		416	by calling AnyEvent in your module body you force the user of your module
		417	to load the event module first.
		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
		429	=head1 WHAT TO DO IN THE MAIN PROGRAM
		430
		431	There will always be a single main program - the only place that should
		432	dictate which event model to use.
		433
		434	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
		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.
		437
		438	If the main program relies on a specific event model. For example, in
		439	Gtk2 programs you have to rely on the Glib module. You should load the
		440	event module before loading AnyEvent or any module that uses it: generally
		441	speaking, you should load it as early as possible. The reason is that
		442	modules might create watchers when they are loaded, and AnyEvent will
		443	decide on the event model to use as soon as it creates watchers, and it
		444	might chose the wrong one unless you load the correct one yourself.
		445
		446	You can chose to use a rather inefficient pure-perl implementation by
		447	loading the C<AnyEvent::Impl::Perl> module, which gives you similar
		448	behaviour everywhere, but letting AnyEvent chose is generally better.
		449
59	=cut	450	=cut
60		451
61	package AnyEvent;	452	package AnyEvent;
62		453
63	no warnings;	454	no warnings;
64	use strict 'vars';	455	use strict;
		456
65	use Carp;	457	use Carp;
66		458
67	our $VERSION = 0.3;	459	our $VERSION = '3.3';
68	our $MODEL;	460	our $MODEL;
69		461
70	our $AUTOLOAD;	462	our $AUTOLOAD;
71	our @ISA;	463	our @ISA;
72		464
		465	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		466
		467	our @REGISTRY;
		468
73	my @models = (	469	my @models = (
74	[Coro => Coro::Event::],	470	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
75	[Event => Event::],	471	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
76	[Glib => Glib::],	472	[EV:: => AnyEvent::Impl::EV::],
77	[Tk => Tk::],	473	[Event:: => AnyEvent::Impl::Event::],
		474	[Glib:: => AnyEvent::Impl::Glib::],
		475	[Tk:: => AnyEvent::Impl::Tk::],
		476	[Wx:: => AnyEvent::Impl::POE::],
		477	[Prima:: => AnyEvent::Impl::POE::],
		478	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
		479	# everything below here will not be autoprobed as the pureperl backend should work everywhere
		480	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		481	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		482	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
78	);	483	);
79		484
80	our %method = map +($_ => 1), qw(io timer condvar broadcast wait cancel DESTROY);	485	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);
81		486
82	sub AUTOLOAD {	487	sub detect() {
83	$AUTOLOAD =~ s/.*://;
84
85	$method{$AUTOLOAD}
86	or croak "$AUTOLOAD: not a valid method for AnyEvent objects";
87
88	unless ($MODEL) {	488	unless ($MODEL) {
89	# check for already loaded models	489	no strict 'refs';
90	for (@models) {	490
91	my ($model, $package) = @$_;	491	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
92	if (scalar keys %{ *{"$package\::"} }) {	492	my $model = "AnyEvent::Impl::$1";
93	eval "require AnyEvent::Impl::$model";	493	if (eval "require $model") {
94	last if $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 $verbose;
95	}	498	}
96	}	499	}
97		500
		501	# check for already loaded models
98	unless ($MODEL) {	502	unless ($MODEL) {
99	# try to load a model
100
101	for (@models) {	503	for (@REGISTRY, @models) {
102	my ($model, $package) = @$_;	504	my ($package, $model) = @$_;
103	eval "require AnyEvent::Impl::$model";	505	if (${"$package\::VERSION"} > 0) {
104	last if $MODEL;	506	if (eval "require $model") {
		507	$MODEL = $model;
		508	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
		509	last;
		510	}
		511	}
105	}	512	}
106		513
		514	unless ($MODEL) {
		515	# try to load a model
		516
		517	for (@REGISTRY, @models) {
		518	my ($package, $model) = @$_;
		519	if (eval "require $package"
		520	and ${"$package\::VERSION"} > 0
		521	and eval "require $model") {
		522	$MODEL = $model;
		523	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
		524	last;
		525	}
		526	}
		527
107	$MODEL	528	$MODEL
108	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Coro, Event, Glib or Tk.";	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.";
		530	}
109	}	531	}
		532
		533	unshift @ISA, $MODEL;
		534	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
110	}	535	}
111		536
112	@ISA = $MODEL;	537	$MODEL
		538	}
		539
		540	sub AUTOLOAD {
		541	(my $func = $AUTOLOAD) =~ s/.*://;
		542
		543	$method{$func}
		544	or croak "$func: not a valid method for AnyEvent objects";
		545
		546	detect unless $MODEL;
113		547
114	my $class = shift;	548	my $class = shift;
115	$class->$AUTOLOAD (@_);	549	$class->$func (@_);
116	}	550	}
117		551
		552	package AnyEvent::Base;
		553
		554	# default implementation for ->condvar, ->wait, ->broadcast
		555
		556	sub condvar {
		557	bless \my $flag, "AnyEvent::Base::CondVar"
		558	}
		559
		560	sub AnyEvent::Base::CondVar::broadcast {
		561	${$_[0]}++;
		562	}
		563
		564	sub AnyEvent::Base::CondVar::wait {
		565	AnyEvent->one_event while !${$_[0]};
		566	}
		567
		568	# default implementation for ->signal
		569
		570	our %SIG_CB;
		571
		572	sub signal {
		573	my (undef, %arg) = @_;
		574
		575	my $signal = uc $arg{signal}
		576	or Carp::croak "required option 'signal' is missing";
		577
		578	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		579	$SIG{$signal} \|\|= sub {
		580	$_->() for values %{ $SIG_CB{$signal} \|\| {} };
		581	};
		582
		583	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
		584	}
		585
		586	sub AnyEvent::Base::Signal::DESTROY {
		587	my ($signal, $cb) = @{$_[0]};
		588
		589	delete $SIG_CB{$signal}{$cb};
		590
		591	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
		592	}
		593
		594	# default implementation for ->child
		595
		596	our %PID_CB;
		597	our $CHLD_W;
		598	our $CHLD_DELAY_W;
		599	our $PID_IDLE;
		600	our $WNOHANG;
		601
		602	sub _child_wait {
		603	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		604	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),
		605	(values %{ $PID_CB{0} \|\| {} });
		606	}
		607
		608	undef $PID_IDLE;
		609	}
		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
		619	sub child {
		620	my (undef, %arg) = @_;
		621
		622	defined (my $pid = $arg{pid} + 0)
		623	or Carp::croak "required option 'pid' is missing";
		624
		625	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
		626
		627	unless ($WNOHANG) {
		628	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;
		629	}
		630
		631	unless ($CHLD_W) {
		632	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
		633	# child could be a zombie already, so make at least one round
		634	&_sigchld;
		635	}
		636
		637	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"
		638	}
		639
		640	sub AnyEvent::Base::Child::DESTROY {
		641	my ($pid, $cb) = @{$_[0]};
		642
		643	delete $PID_CB{$pid}{$cb};
		644	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
		645
		646	undef $CHLD_W unless keys %PID_CB;
		647	}
		648
		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.
		654
		655	If you need to support another event library which isn't directly
		656	supported by AnyEvent, you can supply your own interface to it by
		657	pushing, before the first watcher gets created, the package name of
		658	the event module and the package name of the interface to use onto
		659	C<@AnyEvent::REGISTRY>. You can do that before and even without loading
		660	AnyEvent, so it is reasonably cheap.
		661
		662	Example:
		663
		664	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
		665
		666	This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
		667	package/class when it finds the C<urxvt> package/module is already loaded.
		668
		669	When AnyEvent is loaded and asked to find a suitable event model, it
		670	will first check for the presence of urxvt by trying to C<use> the
		671	C<urxvt::anyevent> module.
		672
		673	The class should provide implementations for all watcher types. See
		674	L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code)
		675	and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to
		676	see the sources.
		677
		678	If you don't provide C<signal> and C<child> watchers than AnyEvent will
		679	provide suitable (hopefully) replacements.
		680
		681	The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt)
		682	terminal emulator uses the above line as-is. An interface isn't included
		683	in AnyEvent because it doesn't make sense outside the embedded interpreter
		684	inside I<rxvt-unicode>, and it is updated and maintained as part of the
		685	I<rxvt-unicode> distribution.
		686
		687	I<rxvt-unicode> also cheats a bit by not providing blocking access to
		688	condition variables: code blocking while waiting for a condition will
		689	C<die>. This still works with most modules/usages, and blocking calls must
		690	not be done in an interactive application, so it makes sense.
		691
		692	=head1 ENVIRONMENT VARIABLES
		693
		694	The following environment variables are used by this module:
		695
		696	=over 4
		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
118	=back	727	=back
119		728
120	=head1 EXAMPLE	729	=head1 EXAMPLE PROGRAM
121		730
122	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
123	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
124	when the user enters quit:	733	program when the user enters quit:
125		734
126	use AnyEvent;	735	use AnyEvent;
127		736
128	my $cv = AnyEvent->condvar;	737	my $cv = AnyEvent->condvar;
129		738
130	my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	739	my $io_watcher = AnyEvent->io (
		740	fh => \*STDIN,
		741	poll => 'r',
		742	cb => sub {
131	warn "io event <$_[0]>\n"; # will always output <r>	743	warn "io event <$_[0]>\n"; # will always output <r>
132	chomp (my $input = <STDIN>); # read a line	744	chomp (my $input = <STDIN>); # read a line
133	warn "read: $input\n"; # output what has been read	745	warn "read: $input\n"; # output what has been read
134	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	746	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i
		747	},
135	});	748	);
136		749
137	my $time_watcher; # can only be used once	750	my $time_watcher; # can only be used once
138		751
139	sub new_timer {	752	sub new_timer {
140	$timer = AnyEvent->timer (after => 1, cb => sub {	753	$timer = AnyEvent->timer (after => 1, cb => sub {
222	$txn->{finished}->wait;	835	$txn->{finished}->wait;
223	return $txn->{result};	836	return $txn->{result};
224		837
225	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)
226	that occured during request processing. The C<result> method detects	839	that occured during request processing. The C<result> method detects
227	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)
228	and just throws the exception, which means connection errors and other	841	and just throws the exception, which means connection errors and other
229	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
230	random callback.	843	random callback.
231		844
232	All of this enables the following usage styles:	845	All of this enables the following usage styles:
233		846
234	1. Blocking:	847	1. Blocking:
235		848
236	my $data = $fcp->client_get ($url);	849	my $data = $fcp->client_get ($url);
237		850
238	2. Blocking, but parallelizing:	851	2. Blocking, but running in parallel:
239		852
240	my @datas = map $_->result,	853	my @datas = map $_->result,
241	map $fcp->txn_client_get ($_),	854	map $fcp->txn_client_get ($_),
242	@urls;	855	@urls;
243		856
244	Both blocking examples work without the module user having to know	857	Both blocking examples work without the module user having to know
245	anything about events.	858	anything about events.
246		859
247	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:
248		861
249	use Event;	862	use EV;
250		863
251	$fcp->txn_client_get ($url)->cb (sub {	864	$fcp->txn_client_get ($url)->cb (sub {
252	my $txn = shift;	865	my $txn = shift;
253	my $data = $txn->result;	866	my $data = $txn->result;
254	...	867	...
255	});	868	});
256		869
257	Event::loop;	870	EV::loop;
258		871
259	3b. The module user could use AnyEvent, too:	872	3b. The module user could use AnyEvent, too:
260		873
261	use AnyEvent;	874	use AnyEvent;
262		875
…		…
267	$quit->broadcast;	880	$quit->broadcast;
268	});	881	});
269		882
270	$quit->wait;	883	$quit->wait;
271		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 610 3.52 0.91 0.75 EV + AnyEvent watchers
		932	CoroEV/Any 100000 610 3.49 0.92 0.75 coroutines + Coro::Signal
		933	Perl/Any 100000 513 4.91 0.92 1.15 pure perl implementation
		934	Event/Event 16000 523 28.05 21.38 0.86 Event native interface
		935	Event/Any 16000 943 34.43 20.48 1.39 Event + AnyEvent watchers
		936	Glib/Any 16000 1357 96.99 12.55 55.51 quadratic behaviour
		937	Tk/Any 2000 1855 27.01 66.61 14.03 SEGV with >> 2000 watchers
		938	POE/Event 2000 6644 108.15 768.19 14.33 via POE::Loop::Event
		939	POE/Select 2000 6343 94.69 807.65 562.69 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
272	=head1 SEE ALSO	1032	=head1 SEE ALSO
273		1033
274	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>.
275		1037
		1038	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,
276	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>.
277		1042
278	Nontrivial usage example: L<Net::FCP>.	1043	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.
279		1044
280	=head1	1045
		1046	=head1 AUTHOR
		1047
		1048	Marc Lehmann <schmorp@schmorp.de>
		1049	http://home.schmorp.de/
281		1050
282	=cut	1051	=cut
283		1052
284	1	1053	1
285		1054

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.6 by root, Mon Dec 19 17:03:29 2005 UTC vs. Revision 1.82 by root, Fri Apr 25 13:32:39 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.6 by root, Mon Dec 19 17:03:29 2005 UTC vs.
Revision 1.82 by root, Fri Apr 25 13:32:39 2008 UTC