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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.11 by root, Thu Jul 20 01:32:11 2006 UTC vs.
Revision 1.65 by root, Fri Apr 25 06:58:12 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 $poll type is allowed (i.e. on a socket
17	you can have one r + one w or one rw watcher, not any more (limitation by
18	Tk).
19
20	* the C<$poll_got> passed to the handler needs to be checked by looking
21	for single characters (e.g. with a regex), as it can contain more event
22	types than were requested (e.g. a 'w' watcher might generate 'rw' events,
23	limitation by Glib).
24
25	* AnyEvent will keep filehandles alive, so as long as the watcher exists,
26	the filehandle exists.
27		14
28	my $w = AnyEvent->timer (after => $seconds, cb => sub {	15	my $w = AnyEvent->timer (after => $seconds, cb => sub {
29	...	16	...
30	});	17	});
31		18
32	* 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
33
34	* timers can only be used once and must be recreated for repeated
35	operation (limitation by Glib and Tk).
36
37	my $w = AnyEvent->condvar; # kind of main loop replacement
38	$w->wait; # enters main loop till $condvar gets ->broadcast	20	$w->wait; # enters "main loop" till $condvar gets ->broadcast
39	$w->broadcast; # wake up current and all future wait's	21	$w->broadcast; # wake up current and all future wait's
40		22
41	* condvars are used to give blocking behaviour when neccessary. Create	23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
42	a condvar for any "request" or "event" your module might create, C<<	24
43	->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
44	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
45		71
46	=head1 DESCRIPTION	72	=head1 DESCRIPTION
47		73
48	L<AnyEvent> provides an identical interface to multiple event loops. This	74	L<AnyEvent> provides an identical interface to multiple event loops. This
49	allows module authors to utilizy an event loop without forcing module	75	allows module authors to utilise an event loop without forcing module
50	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
51	peacefully at any one time).	77	peacefully at any one time).
52		78
53	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>
54	module.	80	module.
55		81
56	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
57	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
58	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>,
59	used. If none is found, the module tries to load these modules in the	85	L<Event>, L<Glib>, L<Tk>, L<AnyEvent::Impl::Perl>, L<Event::Lib>, L<Qt>,
60	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
61	used. If still none could be found, it will issue an error.	87	to load these modules (excluding 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 IO 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	As long as the I/O watcher exists it will keep the file descriptor or a
		153	copy of it alive/open.
		154
		155	It is not allowed to close a file handle as long as any watcher is active
		156	on the underlying file descriptor.
		157
		158	Some event loops issue spurious readyness notifications, so you should
		159	always use non-blocking calls when reading/writing from/to your file
		160	handles.
		161
		162	Example:
		163
		164	# wait for readability of STDIN, then read a line and disable the watcher
		165	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		166	chomp (my $input = <STDIN>);
		167	warn "read: $input\n";
		168	undef $w;
		169	});
		170
		171	=head2 TIME WATCHERS
		172
		173	You can create a time watcher by calling the C<< AnyEvent->timer >>
		174	method with the following mandatory arguments:
		175
		176	C<after> specifies after how many seconds (fractional values are
		177	supported) should the timer activate. C<cb> the callback to invoke in that
		178	case.
		179
		180	The timer callback will be invoked at most once: if you want a repeating
		181	timer you have to create a new watcher (this is a limitation by both Tk
		182	and Glib).
		183
		184	Example:
		185
		186	# fire an event after 7.7 seconds
		187	my $w = AnyEvent->timer (after => 7.7, cb => sub {
		188	warn "timeout\n";
		189	});
		190
		191	# to cancel the timer:
		192	undef $w;
		193
		194	Example 2:
		195
		196	# fire an event after 0.5 seconds, then roughly every second
		197	my $w;
		198
		199	my $cb = sub {
		200	# cancel the old timer while creating a new one
		201	$w = AnyEvent->timer (after => 1, cb => $cb);
		202	};
		203
		204	# start the "loop" by creating the first watcher
		205	$w = AnyEvent->timer (after => 0.5, cb => $cb);
		206
		207	=head3 TIMING ISSUES
		208
		209	There are two ways to handle timers: based on real time (relative, "fire
		210	in 10 seconds") and based on wallclock time (absolute, "fire at 12
		211	o'clock").
		212
		213	While most event loops expect timers to specified in a relative way, they
		214	use absolute time internally. This makes a difference when your clock
		215	"jumps", for example, when ntp decides to set your clock backwards from
		216	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to
		217	fire "after" a second might actually take six years to finally fire.
		218
		219	AnyEvent cannot compensate for this. The only event loop that is conscious
		220	about these issues is L<EV>, which offers both relative (ev_timer, based
		221	on true relative time) and absolute (ev_periodic, based on wallclock time)
		222	timers.
		223
		224	AnyEvent always prefers relative timers, if available, matching the
		225	AnyEvent API.
		226
		227	=head2 SIGNAL WATCHERS
		228
		229	You can watch for signals using a signal watcher, C<signal> is the signal
		230	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to
		231	be invoked whenever a signal occurs.
		232
		233	Multiple signal occurances can be clumped together into one callback
		234	invocation, and callback invocation will be synchronous. synchronous means
		235	that it might take a while until the signal gets handled by the process,
		236	but it is guarenteed not to interrupt any other callbacks.
		237
		238	The main advantage of using these watchers is that you can share a signal
		239	between multiple watchers.
		240
		241	This watcher might use C<%SIG>, so programs overwriting those signals
		242	directly will likely not work correctly.
		243
		244	Example: exit on SIGINT
		245
		246	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
		247
		248	=head2 CHILD PROCESS WATCHERS
		249
		250	You can also watch on a child process exit and catch its exit status.
		251
		252	The child process is specified by the C<pid> argument (if set to C<0>, it
		253	watches for any child process exit). The watcher will trigger as often
		254	as status change for the child are received. This works by installing a
		255	signal handler for C<SIGCHLD>. The callback will be called with the pid
		256	and exit status (as returned by waitpid).
		257
		258	Example: wait for pid 1333
		259
		260	my $w = AnyEvent->child (
		261	pid => 1333,
		262	cb => sub {
		263	my ($pid, $status) = @_;
		264	warn "pid $pid exited with status $status";
		265	},
		266	);
		267
		268	=head2 CONDITION VARIABLES
		269
		270	Condition variables can be created by calling the C<< AnyEvent->condvar >>
		271	method without any arguments.
		272
		273	A condition variable waits for a condition - precisely that the C<<
		274	->broadcast >> method has been called.
		275
		276	They are very useful to signal that a condition has been fulfilled, for
		277	example, if you write a module that does asynchronous http requests,
		278	then a condition variable would be the ideal candidate to signal the
		279	availability of results.
		280
		281	You can also use condition variables to block your main program until
		282	an event occurs - for example, you could C<< ->wait >> in your main
		283	program until the user clicks the Quit button in your app, which would C<<
		284	->broadcast >> the "quit" event.
		285
		286	Note that condition variables recurse into the event loop - if you have
		287	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you
		288	lose. Therefore, condition variables are good to export to your caller, but
		289	you should avoid making a blocking wait yourself, at least in callbacks,
		290	as this asks for trouble.
		291
		292	This object has two methods:
62		293
63	=over 4	294	=over 4
64		295
		296	=item $cv->wait
		297
		298	Wait (blocking if necessary) until the C<< ->broadcast >> method has been
		299	called on c<$cv>, while servicing other watchers normally.
		300
		301	You can only wait once on a condition - additional calls will return
		302	immediately.
		303
		304	Not all event models support a blocking wait - some die in that case
		305	(programs might want to do that to stay interactive), so I<if you are
		306	using this from a module, never require a blocking wait>, but let the
		307	caller decide whether the call will block or not (for example, by coupling
		308	condition variables with some kind of request results and supporting
		309	callbacks so the caller knows that getting the result will not block,
		310	while still suppporting blocking waits if the caller so desires).
		311
		312	Another reason I<never> to C<< ->wait >> in a module is that you cannot
		313	sensibly have two C<< ->wait >>'s in parallel, as that would require
		314	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
		315	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and
		316	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
		317	from different coroutines, however).
		318
		319	=item $cv->broadcast
		320
		321	Flag the condition as ready - a running C<< ->wait >> and all further
		322	calls to C<wait> will (eventually) return after this method has been
		323	called. If nobody is waiting the broadcast will be remembered..
		324
		325	=back
		326
		327	Example:
		328
		329	# wait till the result is ready
		330	my $result_ready = AnyEvent->condvar;
		331
		332	# do something such as adding a timer
		333	# or socket watcher the calls $result_ready->broadcast
		334	# when the "result" is ready.
		335	# in this case, we simply use a timer:
		336	my $w = AnyEvent->timer (
		337	after => 1,
		338	cb => sub { $result_ready->broadcast },
		339	);
		340
		341	# this "blocks" (while handling events) till the watcher
		342	# calls broadcast
		343	$result_ready->wait;
		344
		345	=head1 GLOBAL VARIABLES AND FUNCTIONS
		346
		347	=over 4
		348
		349	=item $AnyEvent::MODEL
		350
		351	Contains C<undef> until the first watcher is being created. Then it
		352	contains the event model that is being used, which is the name of the
		353	Perl class implementing the model. This class is usually one of the
		354	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
		355	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
		356
		357	The known classes so far are:
		358
		359	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
		360	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
		361	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
		362	AnyEvent::Impl::Event based on Event, second best choice.
		363	AnyEvent::Impl::Glib based on Glib, third-best choice.
		364	AnyEvent::Impl::Tk based on Tk, very bad choice.
		365	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
		366	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
		367	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		368	AnyEvent::Impl::POE based on POE, not generic enough for full support.
		369
		370	There is no support for WxWidgets, as WxWidgets has no support for
		371	watching file handles. However, you can use WxWidgets through the
		372	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
		373	second, which was considered to be too horrible to even consider for
		374	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
		375	it's adaptor.
		376
		377	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
		378	autodetecting them.
		379
		380	=item AnyEvent::detect
		381
		382	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
		383	if necessary. You should only call this function right before you would
		384	have created an AnyEvent watcher anyway, that is, as late as possible at
		385	runtime.
		386
		387	=back
		388
		389	=head1 WHAT TO DO IN A MODULE
		390
		391	As a module author, you should C<use AnyEvent> and call AnyEvent methods
		392	freely, but you should not load a specific event module or rely on it.
		393
		394	Be careful when you create watchers in the module body - AnyEvent will
		395	decide which event module to use as soon as the first method is called, so
		396	by calling AnyEvent in your module body you force the user of your module
		397	to load the event module first.
		398
		399	Never call C<< ->wait >> on a condition variable unless you I<know> that
		400	the C<< ->broadcast >> method has been called on it already. This is
		401	because it will stall the whole program, and the whole point of using
		402	events is to stay interactive.
		403
		404	It is fine, however, to call C<< ->wait >> when the user of your module
		405	requests it (i.e. if you create a http request object ad have a method
		406	called C<results> that returns the results, it should call C<< ->wait >>
		407	freely, as the user of your module knows what she is doing. always).
		408
		409	=head1 WHAT TO DO IN THE MAIN PROGRAM
		410
		411	There will always be a single main program - the only place that should
		412	dictate which event model to use.
		413
		414	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
		415	do anything special (it does not need to be event-based) and let AnyEvent
		416	decide which implementation to chose if some module relies on it.
		417
		418	If the main program relies on a specific event model. For example, in
		419	Gtk2 programs you have to rely on the Glib module. You should load the
		420	event module before loading AnyEvent or any module that uses it: generally
		421	speaking, you should load it as early as possible. The reason is that
		422	modules might create watchers when they are loaded, and AnyEvent will
		423	decide on the event model to use as soon as it creates watchers, and it
		424	might chose the wrong one unless you load the correct one yourself.
		425
		426	You can chose to use a rather inefficient pure-perl implementation by
		427	loading the C<AnyEvent::Impl::Perl> module, which gives you similar
		428	behaviour everywhere, but letting AnyEvent chose is generally better.
		429
65	=cut	430	=cut
66		431
67	package AnyEvent;	432	package AnyEvent;
68		433
69	no warnings;	434	no warnings;
70	use strict 'vars';	435	use strict;
		436
71	use Carp;	437	use Carp;
72		438
73	our $VERSION = '1.02';	439	our $VERSION = '3.3';
74	our $MODEL;	440	our $MODEL;
75		441
76	our $AUTOLOAD;	442	our $AUTOLOAD;
77	our @ISA;	443	our @ISA;
78		444
79	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	445	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
80		446
81	our @REGISTRY;	447	our @REGISTRY;
82		448
83	my @models = (	449	my @models = (
		450	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
84	[Coro::Event:: => AnyEvent::Impl::Coro::],	451	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
		452	[EV:: => AnyEvent::Impl::EV::],
85	[Event:: => AnyEvent::Impl::Event::],	453	[Event:: => AnyEvent::Impl::Event::],
86	[Glib:: => AnyEvent::Impl::Glib::],	454	[Glib:: => AnyEvent::Impl::Glib::],
87	[Tk:: => AnyEvent::Impl::Tk::],	455	[Tk:: => AnyEvent::Impl::Tk::],
		456	[Wx:: => AnyEvent::Impl::POE::],
		457	[Prima:: => AnyEvent::Impl::POE::],
		458	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
		459	# everything below here will not be autoprobed as the pureperl backend should work everywhere
		460	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		461	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		462	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
88	);	463	);
89		464
90	our %method = map +($_ => 1), qw(io timer condvar broadcast wait cancel DESTROY);	465	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);
91		466
92	sub AUTOLOAD {	467	sub detect() {
93	$AUTOLOAD =~ s/.*://;
94
95	$method{$AUTOLOAD}
96	or croak "$AUTOLOAD: not a valid method for AnyEvent objects";
97
98	unless ($MODEL) {	468	unless ($MODEL) {
		469	no strict 'refs';
		470
		471	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
		472	my $model = "AnyEvent::Impl::$1";
		473	if (eval "require $model") {
		474	$MODEL = $model;
		475	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;
		476	} else {
		477	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;
		478	}
		479	}
		480
99	# check for already loaded models	481	# check for already loaded models
		482	unless ($MODEL) {
100	for (@REGISTRY, @models) {	483	for (@REGISTRY, @models) {
101	my ($package, $model) = @$_;	484	my ($package, $model) = @$_;
102	if (${"$package\::VERSION"} > 0) {	485	if (${"$package\::VERSION"} > 0) {
103	if (eval "require $model") {	486	if (eval "require $model") {
104	$MODEL = $model;	487	$MODEL = $model;
105	warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1;	488	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
106	last;	489	last;
		490	}
107	}	491	}
108	}	492	}
		493
		494	unless ($MODEL) {
		495	# try to load a model
		496
		497	for (@REGISTRY, @models) {
		498	my ($package, $model) = @$_;
		499	if (eval "require $package"
		500	and ${"$package\::VERSION"} > 0
		501	and eval "require $model") {
		502	$MODEL = $model;
		503	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
		504	last;
		505	}
		506	}
		507
		508	$MODEL
		509	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";
		510	}
109	}	511	}
110		512
111	unless ($MODEL) {	513	unshift @ISA, $MODEL;
112	# try to load a model	514	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
113
114	for (@REGISTRY, @models) {
115	my ($package, $model) = @$_;
116	if (eval "require $model") {
117	$MODEL = $model;
118	warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1;
119	last;
120	}
121	}
122
123	$MODEL
124	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Coro, Event, Glib or Tk.";
125	}
126	}	515	}
127		516
128	@ISA = $MODEL;	517	$MODEL
		518	}
		519
		520	sub AUTOLOAD {
		521	(my $func = $AUTOLOAD) =~ s/.*://;
		522
		523	$method{$func}
		524	or croak "$func: not a valid method for AnyEvent objects";
		525
		526	detect unless $MODEL;
129		527
130	my $class = shift;	528	my $class = shift;
131	$class->$AUTOLOAD (@_);	529	$class->$func (@_);
132	}	530	}
133		531
134	=back	532	package AnyEvent::Base;
		533
		534	# default implementation for ->condvar, ->wait, ->broadcast
		535
		536	sub condvar {
		537	bless \my $flag, "AnyEvent::Base::CondVar"
		538	}
		539
		540	sub AnyEvent::Base::CondVar::broadcast {
		541	${$_[0]}++;
		542	}
		543
		544	sub AnyEvent::Base::CondVar::wait {
		545	AnyEvent->one_event while !${$_[0]};
		546	}
		547
		548	# default implementation for ->signal
		549
		550	our %SIG_CB;
		551
		552	sub signal {
		553	my (undef, %arg) = @_;
		554
		555	my $signal = uc $arg{signal}
		556	or Carp::croak "required option 'signal' is missing";
		557
		558	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		559	$SIG{$signal} \|\|= sub {
		560	$_->() for values %{ $SIG_CB{$signal} \|\| {} };
		561	};
		562
		563	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
		564	}
		565
		566	sub AnyEvent::Base::Signal::DESTROY {
		567	my ($signal, $cb) = @{$_[0]};
		568
		569	delete $SIG_CB{$signal}{$cb};
		570
		571	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
		572	}
		573
		574	# default implementation for ->child
		575
		576	our %PID_CB;
		577	our $CHLD_W;
		578	our $CHLD_DELAY_W;
		579	our $PID_IDLE;
		580	our $WNOHANG;
		581
		582	sub _child_wait {
		583	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		584	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),
		585	(values %{ $PID_CB{0} \|\| {} });
		586	}
		587
		588	undef $PID_IDLE;
		589	}
		590
		591	sub _sigchld {
		592	# make sure we deliver these changes "synchronous" with the event loop.
		593	$CHLD_DELAY_W \|\|= AnyEvent->timer (after => 0, cb => sub {
		594	undef $CHLD_DELAY_W;
		595	&_child_wait;
		596	});
		597	}
		598
		599	sub child {
		600	my (undef, %arg) = @_;
		601
		602	defined (my $pid = $arg{pid} + 0)
		603	or Carp::croak "required option 'pid' is missing";
		604
		605	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
		606
		607	unless ($WNOHANG) {
		608	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;
		609	}
		610
		611	unless ($CHLD_W) {
		612	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
		613	# child could be a zombie already, so make at least one round
		614	&_sigchld;
		615	}
		616
		617	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"
		618	}
		619
		620	sub AnyEvent::Base::Child::DESTROY {
		621	my ($pid, $cb) = @{$_[0]};
		622
		623	delete $PID_CB{$pid}{$cb};
		624	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
		625
		626	undef $CHLD_W unless keys %PID_CB;
		627	}
135		628
136	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	629	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
		630
		631	This is an advanced topic that you do not normally need to use AnyEvent in
		632	a module. This section is only of use to event loop authors who want to
		633	provide AnyEvent compatibility.
137		634
138	If you need to support another event library which isn't directly	635	If you need to support another event library which isn't directly
139	supported by AnyEvent, you can supply your own interface to it by	636	supported by AnyEvent, you can supply your own interface to it by
140	pushing, before the first watcher gets created, the package name of	637	pushing, before the first watcher gets created, the package name of
141	the event module and the package name of the interface to use onto	638	the event module and the package name of the interface to use onto
142	C<@AnyEvent::REGISTRY>. You can do that before and even without loading	639	C<@AnyEvent::REGISTRY>. You can do that before and even without loading
143	AnyEvent.	640	AnyEvent, so it is reasonably cheap.
144		641
145	Example:	642	Example:
146		643
147	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];	644	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
148		645
149	This tells AnyEvent to (literally) use the C<urxvt::anyevent::> module	646	This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
150	when it finds the C<urxvt> module is loaded. When AnyEvent is loaded and	647	package/class when it finds the C<urxvt> package/module is already loaded.
151	requested to find a suitable event model, it will first check for the
152	urxvt module.
153		648
		649	When AnyEvent is loaded and asked to find a suitable event model, it
		650	will first check for the presence of urxvt by trying to C<use> the
		651	C<urxvt::anyevent> module.
		652
		653	The class should provide implementations for all watcher types. See
		654	L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code)
		655	and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to
		656	see the sources.
		657
		658	If you don't provide C<signal> and C<child> watchers than AnyEvent will
		659	provide suitable (hopefully) replacements.
		660
154	The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) uses	661	The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt)
155	the above line exactly. An interface isn't included in AnyEvent	662	terminal emulator uses the above line as-is. An interface isn't included
156	because it doesn't make sense outside the embedded interpreter inside	663	in AnyEvent because it doesn't make sense outside the embedded interpreter
157	I<rxvt-unicode>, and it is updated and maintained as part of the	664	inside I<rxvt-unicode>, and it is updated and maintained as part of the
158	I<rxvt-unicode> distribution.	665	I<rxvt-unicode> distribution.
159		666
		667	I<rxvt-unicode> also cheats a bit by not providing blocking access to
		668	condition variables: code blocking while waiting for a condition will
		669	C<die>. This still works with most modules/usages, and blocking calls must
		670	not be done in an interactive application, so it makes sense.
		671
160	=head1 ENVIRONMENT VARIABLES	672	=head1 ENVIRONMENT VARIABLES
161		673
162	The following environment variables are used by this module:	674	The following environment variables are used by this module:
163		675
164	C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event	676	=over 4
165	model gets used.
166		677
		678	=item C<PERL_ANYEVENT_VERBOSE>
		679
		680	By default, AnyEvent will be completely silent except in fatal
		681	conditions. You can set this environment variable to make AnyEvent more
		682	talkative.
		683
		684	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		685	conditions, such as not being able to load the event model specified by
		686	C<PERL_ANYEVENT_MODEL>.
		687
		688	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		689	model it chooses.
		690
		691	=item C<PERL_ANYEVENT_MODEL>
		692
		693	This can be used to specify the event model to be used by AnyEvent, before
		694	autodetection and -probing kicks in. It must be a string consisting
		695	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		696	and the resulting module name is loaded and if the load was successful,
		697	used as event model. If it fails to load AnyEvent will proceed with
		698	autodetection and -probing.
		699
		700	This functionality might change in future versions.
		701
		702	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		703	could start your program like this:
		704
		705	PERL_ANYEVENT_MODEL=Perl perl ...
		706
		707	=back
		708
167	=head1 EXAMPLE	709	=head1 EXAMPLE PROGRAM
168		710
169	The following program uses an io watcher to read data from stdin, a timer	711	The following program uses an IO watcher to read data from STDIN, a timer
170	to display a message once per second, and a condvar to exit the program	712	to display a message once per second, and a condition variable to quit the
171	when the user enters quit:	713	program when the user enters quit:
172		714
173	use AnyEvent;	715	use AnyEvent;
174		716
175	my $cv = AnyEvent->condvar;	717	my $cv = AnyEvent->condvar;
176		718
177	my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	719	my $io_watcher = AnyEvent->io (
		720	fh => \*STDIN,
		721	poll => 'r',
		722	cb => sub {
178	warn "io event <$_[0]>\n"; # will always output <r>	723	warn "io event <$_[0]>\n"; # will always output <r>
179	chomp (my $input = <STDIN>); # read a line	724	chomp (my $input = <STDIN>); # read a line
180	warn "read: $input\n"; # output what has been read	725	warn "read: $input\n"; # output what has been read
181	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	726	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i
		727	},
182	});	728	);
183		729
184	my $time_watcher; # can only be used once	730	my $time_watcher; # can only be used once
185		731
186	sub new_timer {	732	sub new_timer {
187	$timer = AnyEvent->timer (after => 1, cb => sub {	733	$timer = AnyEvent->timer (after => 1, cb => sub {
269	$txn->{finished}->wait;	815	$txn->{finished}->wait;
270	return $txn->{result};	816	return $txn->{result};
271		817
272	The actual code goes further and collects all errors (C<die>s, exceptions)	818	The actual code goes further and collects all errors (C<die>s, exceptions)
273	that occured during request processing. The C<result> method detects	819	that occured during request processing. The C<result> method detects
274	wether an exception as thrown (it is stored inside the $txn object)	820	whether an exception as thrown (it is stored inside the $txn object)
275	and just throws the exception, which means connection errors and other	821	and just throws the exception, which means connection errors and other
276	problems get reported tot he code that tries to use the result, not in a	822	problems get reported tot he code that tries to use the result, not in a
277	random callback.	823	random callback.
278		824
279	All of this enables the following usage styles:	825	All of this enables the following usage styles:
280		826
281	1. Blocking:	827	1. Blocking:
282		828
283	my $data = $fcp->client_get ($url);	829	my $data = $fcp->client_get ($url);
284		830
285	2. Blocking, but parallelizing:	831	2. Blocking, but running in parallel:
286		832
287	my @datas = map $_->result,	833	my @datas = map $_->result,
288	map $fcp->txn_client_get ($_),	834	map $fcp->txn_client_get ($_),
289	@urls;	835	@urls;
290		836
291	Both blocking examples work without the module user having to know	837	Both blocking examples work without the module user having to know
292	anything about events.	838	anything about events.
293		839
294	3a. Event-based in a main program, using any support Event module:	840	3a. Event-based in a main program, using any supported event module:
295		841
296	use Event;	842	use EV;
297		843
298	$fcp->txn_client_get ($url)->cb (sub {	844	$fcp->txn_client_get ($url)->cb (sub {
299	my $txn = shift;	845	my $txn = shift;
300	my $data = $txn->result;	846	my $data = $txn->result;
301	...	847	...
302	});	848	});
303		849
304	Event::loop;	850	EV::loop;
305		851
306	3b. The module user could use AnyEvent, too:	852	3b. The module user could use AnyEvent, too:
307		853
308	use AnyEvent;	854	use AnyEvent;
309		855
…		…
314	$quit->broadcast;	860	$quit->broadcast;
315	});	861	});
316		862
317	$quit->wait;	863	$quit->wait;
318		864
		865
		866	=head1 BENCHMARK
		867
		868	To give you an idea of the performance and overheads that AnyEvent adds
		869	over the backends directly, here is a benchmark of various supported event
		870	models natively and with anyevent. The benchmark creates a lot of timers
		871	(with a zero timeout) and io events (watching STDOUT, a pty, to become
		872	writable), lets them fire exactly once and destroys them again.
		873
		874	Explanation of the fields:
		875
		876	I<watcher> is the number of event watchers created/destroyed. Sicne
		877	different event models have vastly different performance each backend was
		878	handed a number of watchers so that overall runtime is acceptable and
		879	similar to all backends (and keep them from crashing).
		880
		881	I<bytes> is the number of bytes (as measured by resident set size) used by
		882	each watcher.
		883
		884	I<create> is the time, in microseconds, to create a single watcher.
		885
		886	I<invoke> is the time, in microseconds, used to invoke a simple callback
		887	that simply counts down.
		888
		889	I<destroy> is the time, in microseconds, to destroy a single watcher.
		890
		891	name watcher bytes create invoke destroy comment
		892	EV/EV 400000 244 0.56 0.46 0.31 EV native interface
		893	EV/Any 100000 610 3.52 0.91 0.75
		894	CoroEV/Any 100000 610 3.49 0.92 0.75 coroutines + Coro::Signal
		895	Perl/Any 10000 654 4.64 1.22 0.77 pure perl implementation
		896	Event/Event 10000 523 28.05 21.38 5.22 Event native interface
		897	Event/Any 10000 943 34.43 20.48 1.39
		898	Glib/Any 16000 1357 96.99 12.55 55.51 quadratic behaviour
		899	Tk/Any 2000 1855 27.01 66.61 14.03 SEGV with >> 2000 watchers
		900	POE/Select 2000 6343 94.69 807.65 562.69 POE::Loop::Select
		901	POE/Event 2000 6644 108.15 768.19 14.33 POE::Loop::Event
		902
		903	Discussion: The benchmark does I<not> bench scalability of the
		904	backend. For example a select-based backend (such as the pureperl one) can
		905	never compete with a backend using epoll. In this benchmark, only a single
		906	filehandle is used.
		907
		908	EV is the sole leader regarding speed and memory use, which are both
		909	maximal/minimal. Even when going through AnyEvent, there is only one event
		910	loop that uses less memory (the Event module natively), and no faster
		911	event model.
		912
		913	The pure perl implementation is hit in a few sweet spots (both the
		914	zero timeout and the use of a single fd hit optimisations in the perl
		915	interpreter and the backend itself), but it shows that it adds very little
		916	overhead in itself. Like any select-based backend it's performance becomes
		917	really bad with lots of file descriptors.
		918
		919	The Event module has a relatively high setup and callback invocation cost,
		920	but overall scores on the third place.
		921
		922	Glib has a little higher memory cost, a bit fster callback invocation and
		923	has a similar speed as Event.
		924
		925	The Tk backend works relatively well, the fact that it crashes with
		926	more than 2000 watchers is a big setback, however, as correctness takes
		927	precedence over speed.
		928
		929	POE, regardless of backend (wether it's pure perl select backend or the
		930	Event backend) shows abysmal performance and memory usage: Watchers use
		931	almost 30 times as much memory as EV watchers, and 10 times as much memory
		932	as both Event or EV via AnyEvent.
		933
		934	Summary: using EV through AnyEvent is faster than any other event
		935	loop. The overhead AnyEvent adds can be very small, and you should avoid
		936	POE like the plague if you want performance or reasonable memory usage.
		937
		938
		939	=head1 FORK
		940
		941	Most event libraries are not fork-safe. The ones who are usually are
		942	because they are so inefficient. Only L<EV> is fully fork-aware.
		943
		944	If you have to fork, you must either do so I<before> creating your first
		945	watcher OR you must not use AnyEvent at all in the child.
		946
		947
		948	=head1 SECURITY CONSIDERATIONS
		949
		950	AnyEvent can be forced to load any event model via
		951	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to
		952	execute arbitrary code or directly gain access, it can easily be used to
		953	make the program hang or malfunction in subtle ways, as AnyEvent watchers
		954	will not be active when the program uses a different event model than
		955	specified in the variable.
		956
		957	You can make AnyEvent completely ignore this variable by deleting it
		958	before the first watcher gets created, e.g. with a C<BEGIN> block:
		959
		960	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
		961
		962	use AnyEvent;
		963
		964
319	=head1 SEE ALSO	965	=head1 SEE ALSO
320		966
321	Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>.	967	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,
		968	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,
		969	L<Event::Lib>, L<Qt>, L<POE>.
322		970
		971	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,
323	Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>.	972	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,
		973	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,
		974	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.
324		975
325	Nontrivial usage example: L<Net::FCP>.	976	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.
326		977
327	=head1	978
		979	=head1 AUTHOR
		980
		981	Marc Lehmann <schmorp@schmorp.de>
		982	http://home.schmorp.de/
328		983
329	=cut	984	=cut
330		985
331	1	986	1
332		987

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.11 by root, Thu Jul 20 01:32:11 2006 UTC vs. Revision 1.65 by root, Fri Apr 25 06:58:12 2008 UTC

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Revision 1.11 by root, Thu Jul 20 01:32:11 2006 UTC vs.
Revision 1.65 by root, Fri Apr 25 06:58:12 2008 UTC