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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.33 by root, Fri Nov 9 19:34:32 2007 UTC vs.
Revision 1.64 by root, Fri Apr 25 06:54:08 2008 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	Event, Coro, Glib, Tk, Perl - various supported event loops	5	EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops
6		6
7	=head1 SYNOPSIS	7	=head1 SYNOPSIS
8		8
9	use AnyEvent;	9	use AnyEvent;
10		10
14		14
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	15	my $w = AnyEvent->timer (after => $seconds, cb => sub {
16	...	16	...
17	});	17	});
18		18
19	my $w = AnyEvent->condvar; # stores wether a condition was flagged	19	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->wait; # enters "main loop" till $condvar gets ->broadcast	20	$w->wait; # enters "main loop" till $condvar gets ->broadcast
21	$w->broadcast; # wake up current and all future wait's	21	$w->broadcast; # wake up current and all future wait's
		22
		23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
		24
		25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
		26	nowadays. So what is different about AnyEvent?
		27
		28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
		29	policy> and AnyEvent is I<small and efficient>.
		30
		31	First and foremost, I<AnyEvent is not an event model> itself, it only
		32	interfaces to whatever event model the main program happens to use in a
		33	pragmatic way. For event models and certain classes of immortals alike,
		34	the statement "there can only be one" is a bitter reality: In general,
		35	only one event loop can be active at the same time in a process. AnyEvent
		36	helps hiding the differences between those event loops.
		37
		38	The goal of AnyEvent is to offer module authors the ability to do event
		39	programming (waiting for I/O or timer events) without subscribing to a
		40	religion, a way of living, and most importantly: without forcing your
		41	module users into the same thing by forcing them to use the same event
		42	model you use.
		43
		44	For modules like POE or IO::Async (which is a total misnomer as it is
		45	actually doing all I/O I<synchronously>...), using them in your module is
		46	like joining a cult: After you joined, you are dependent on them and you
		47	cannot use anything else, as it is simply incompatible to everything that
		48	isn't itself. What's worse, all the potential users of your module are
		49	I<also> forced to use the same event loop you use.
		50
		51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
		52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
		53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if
		54	your module uses one of those, every user of your module has to use it,
		55	too. But if your module uses AnyEvent, it works transparently with all
		56	event models it supports (including stuff like POE and IO::Async, as long
		57	as those use one of the supported event loops. It is trivial to add new
		58	event loops to AnyEvent, too, so it is future-proof).
		59
		60	In addition to being free of having to use I<the one and only true event
		61	model>, AnyEvent also is free of bloat and policy: with POE or similar
		62	modules, you get an enourmous amount of code and strict rules you have to
		63	follow. AnyEvent, on the other hand, is lean and up to the point, by only
		64	offering the functionality that is necessary, in as thin as a wrapper as
		65	technically possible.
		66
		67	Of course, if you want lots of policy (this can arguably be somewhat
		68	useful) and you want to force your users to use the one and only event
		69	model, you should I<not> use this module.
		70
22		71
23	=head1 DESCRIPTION	72	=head1 DESCRIPTION
24		73
25	L<AnyEvent> provides an identical interface to multiple event loops. This	74	L<AnyEvent> provides an identical interface to multiple event loops. This
26	allows module authors to utilise an event loop without forcing module	75	allows module authors to utilise an event loop without forcing module
27	users to use the same event loop (as only a single event loop can coexist	76	users to use the same event loop (as only a single event loop can coexist
28	peacefully at any one time).	77	peacefully at any one time).
29		78
30	The interface itself is vaguely similar but not identical to the Event	79	The interface itself is vaguely similar, but not identical to the L<Event>
31	module.	80	module.
32		81
33	On the first call of any method, the module tries to detect the currently	82	During the first call of any watcher-creation method, the module tries
34	loaded event loop by probing wether any of the following modules is	83	to detect the currently loaded event loop by probing whether one of the
35	loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is	84	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,
36	used. If none is found, the module tries to load these modules in the	85	L<Event>, L<Glib>, L<Tk>, L<AnyEvent::Impl::Perl>, 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 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 IO WATCHERS
69		142
70	You can create I/O watcher by calling the C<< AnyEvent->io >> method with	143	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
71	the following mandatory arguments:	144	with the following mandatory key-value pairs as arguments:
72		145
73	C<fh> the Perl I<filehandle> (not filedescriptor) to watch for	146	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for
74	events. C<poll> must be a string that is either C<r> or C<w>, that creates	147	events. C<poll> must be a string that is either C<r> or C<w>, which
75	a watcher waiting for "r"eadable or "w"ritable events. C<cb> teh callback	148	creates a watcher waiting for "r"eadable or "w"ritable events,
76	to invoke everytime the filehandle becomes ready.	149	respectively. C<cb> is the callback to invoke each time the file handle
		150	becomes ready.
77		151
78	Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on	152	As long as the I/O watcher exists it will keep the file descriptor or a
79	a socket you can have one r + one w, not any more (limitation comes from	153	copy of it alive/open.
80	Tk - if you are sure you are not using Tk this limitation is gone).
81		154
82	Filehandles will be kept alive, so as long as the watcher exists, the	155	It is not allowed to close a file handle as long as any watcher is active
83	filehandle exists, too.	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.
84		161
85	Example:	162	Example:
86		163
87	# wait for readability of STDIN, then read a line and disable the watcher	164	# 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 {	165	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
…		…
94	=head2 TIME WATCHERS	171	=head2 TIME WATCHERS
95		172
96	You can create a time watcher by calling the C<< AnyEvent->timer >>	173	You can create a time watcher by calling the C<< AnyEvent->timer >>
97	method with the following mandatory arguments:	174	method with the following mandatory arguments:
98		175
99	C<after> after how many seconds (fractions are supported) should the timer	176	C<after> specifies after how many seconds (fractional values are
100	activate. C<cb> the callback to invoke.	177	supported) should the timer activate. C<cb> the callback to invoke in that
		178	case.
101		179
102	The timer callback will be invoked at most once: if you want a repeating	180	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	181	timer you have to create a new watcher (this is a limitation by both Tk
104	and Glib).	182	and Glib).
105		183
…		…
109	my $w = AnyEvent->timer (after => 7.7, cb => sub {	187	my $w = AnyEvent->timer (after => 7.7, cb => sub {
110	warn "timeout\n";	188	warn "timeout\n";
111	});	189	});
112		190
113	# to cancel the timer:	191	# to cancel the timer:
114	undef $w	192	undef $w;
115		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
116	=head2 CONDITION WATCHERS	268	=head2 CONDITION VARIABLES
117		269
118	Condition watchers can be created by calling the C<< AnyEvent->condvar >>	270	Condition variables can be created by calling the C<< AnyEvent->condvar >>
119	method without any arguments.	271	method without any arguments.
120		272
121	A condition watcher watches for a condition - precisely that the C<<	273	A condition variable waits for a condition - precisely that the C<<
122	->broadcast >> method has been called.	274	->broadcast >> method has been called.
123		275
124	The watcher has only two methods:	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:
125		293
126	=over 4	294	=over 4
127		295
128	=item $cv->wait	296	=item $cv->wait
129		297
130	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	298	Wait (blocking if necessary) until the C<< ->broadcast >> method has been
131	called on c<$cv>, while servicing other watchers normally.	299	called on c<$cv>, while servicing other watchers normally.
132		300
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	301	You can only wait once on a condition - additional calls will return
141	immediately.	302	immediately.
142		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
143	=item $cv->broadcast	319	=item $cv->broadcast
144		320
145	Flag the condition as ready - a running C<< ->wait >> and all further	321	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	322	calls to C<wait> will (eventually) return after this method has been
147	is waiting the broadcast will be remembered..	323	called. If nobody is waiting the broadcast will be remembered..
		324
		325	=back
148		326
149	Example:	327	Example:
150		328
151	# wait till the result is ready	329	# wait till the result is ready
152	my $result_ready = AnyEvent->condvar;	330	my $result_ready = AnyEvent->condvar;
153		331
154	# do something such as adding a timer	332	# do something such as adding a timer
155	# or socket watcher the calls $result_ready->broadcast	333	# or socket watcher the calls $result_ready->broadcast
156	# when the "result" is ready.	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	);
157		340
		341	# this "blocks" (while handling events) till the watcher
		342	# calls broadcast
158	$result_ready->wait;	343	$result_ready->wait;
159		344
160	=back	345	=head1 GLOBAL VARIABLES AND FUNCTIONS
161
162	=head2 SIGNAL WATCHERS
163
164	You can listen for signals using a signal watcher, C<signal> is the signal
165	I<name> without any C<SIG> prefix. Multiple signals events can be clumped
166	together into one callback invocation, and callback invocation might or
167	might not be asynchronous.
168
169	These watchers might use C<%SIG>, so programs overwriting those signals
170	directly will likely not work correctly.
171
172	Example: exit on SIGINT
173
174	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
175
176	=head2 CHILD PROCESS WATCHERS
177
178	You can also listen for the status of a child process specified by the
179	C<pid> argument (or any child if the pid argument is 0). The watcher will
180	trigger as often as status change for the child are received. This works
181	by installing a signal handler for C<SIGCHLD>. The callback will be called with
182	the pid and exit status (as returned by waitpid).
183
184	Example: wait for pid 1333
185
186	my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" });
187
188	=head1 GLOBALS
189		346
190	=over 4	347	=over 4
191		348
192	=item $AnyEvent::MODEL	349	=item $AnyEvent::MODEL
193		350
…		…
198	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	355	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
199		356
200	The known classes so far are:	357	The known classes so far are:
201		358
202	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.	359	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
		360	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
203	AnyEvent::Impl::EV based on EV (an interface to libev, also best choice).	361	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
204	AnyEvent::Impl::Coro based on Coro::Event, second best choice.
205	AnyEvent::Impl::Event based on Event, also second best choice :)	362	AnyEvent::Impl::Event based on Event, second best choice.
206	AnyEvent::Impl::Glib based on Glib, second-best choice.	363	AnyEvent::Impl::Glib based on Glib, third-best choice.
207	AnyEvent::Impl::Tk based on Tk, very bad choice.	364	AnyEvent::Impl::Tk based on Tk, very bad choice.
208	AnyEvent::Impl::Perl pure-perl implementation, inefficient.	365	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
		366	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
		367	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		368	AnyEvent::Impl::POE based on POE, not generic enough for full support.
		369
		370	There is no support for WxWidgets, as WxWidgets has no support for
		371	watching file handles. However, you can use WxWidgets through the
		372	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
		373	second, which was considered to be too horrible to even consider for
		374	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
		375	it's adaptor.
		376
		377	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
		378	autodetecting them.
209		379
210	=item AnyEvent::detect	380	=item AnyEvent::detect
211		381
212	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if	382	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
213	necessary. You should only call this function right before you would have	383	if necessary. You should only call this function right before you would
214	created an AnyEvent watcher anyway, that is, very late at runtime.	384	have created an AnyEvent watcher anyway, that is, as late as possible at
		385	runtime.
215		386
216	=back	387	=back
217		388
218	=head1 WHAT TO DO IN A MODULE	389	=head1 WHAT TO DO IN A MODULE
219		390
220	As a module author, you should "use AnyEvent" and call AnyEvent methods	391	As a module author, you should C<use AnyEvent> and call AnyEvent methods
221	freely, but you should not load a specific event module or rely on it.	392	freely, but you should not load a specific event module or rely on it.
222		393
223	Be careful when you create watchers in the module body - Anyevent will	394	Be careful when you create watchers in the module body - AnyEvent will
224	decide which event module to use as soon as the first method is called, so	395	decide which event module to use as soon as the first method is called, so
225	by calling AnyEvent in your module body you force the user of your module	396	by calling AnyEvent in your module body you force the user of your module
226	to load the event module first.	397	to load the event module first.
227		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
228	=head1 WHAT TO DO IN THE MAIN PROGRAM	409	=head1 WHAT TO DO IN THE MAIN PROGRAM
229		410
230	There will always be a single main program - the only place that should	411	There will always be a single main program - the only place that should
231	dictate which event model to use.	412	dictate which event model to use.
232		413
233	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	414	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
234	do anything special and let AnyEvent decide which implementation to chose.	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.
235		417
236	If the main program relies on a specific event model (for example, in Gtk2	418	If the main program relies on a specific event model. For example, in
237	programs you have to rely on either Glib or Glib::Event), you should load	419	Gtk2 programs you have to rely on the Glib module. You should load the
238	it before loading AnyEvent or any module that uses it, generally, as early	420	event module before loading AnyEvent or any module that uses it: generally
239	as possible. The reason is that modules might create watchers when they	421	speaking, you should load it as early as possible. The reason is that
240	are loaded, and AnyEvent will decide on the event model to use as soon as	422	modules might create watchers when they are loaded, and AnyEvent will
241	it creates watchers, and it might chose the wrong one unless you load the	423	decide on the event model to use as soon as it creates watchers, and it
242	correct one yourself.	424	might chose the wrong one unless you load the correct one yourself.
243		425
244	You can chose to use a rather inefficient pure-perl implementation by	426	You can chose to use a rather inefficient pure-perl implementation by
245	loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is	427	loading the C<AnyEvent::Impl::Perl> module, which gives you similar
246	generally better.	428	behaviour everywhere, but letting AnyEvent chose is generally better.
247		429
248	=cut	430	=cut
249		431
250	package AnyEvent;	432	package AnyEvent;
251		433
252	no warnings;	434	no warnings;
253	use strict;	435	use strict;
254		436
255	use Carp;	437	use Carp;
256		438
257	our $VERSION = '2.55';	439	our $VERSION = '3.3';
258	our $MODEL;	440	our $MODEL;
259		441
260	our $AUTOLOAD;	442	our $AUTOLOAD;
261	our @ISA;	443	our @ISA;
262		444
…		…
264		446
265	our @REGISTRY;	447	our @REGISTRY;
266		448
267	my @models = (	449	my @models = (
268	[Coro::EV:: => AnyEvent::Impl::CoroEV::],	450	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
		451	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
269	[EV:: => AnyEvent::Impl::EV::],	452	[EV:: => AnyEvent::Impl::EV::],
270	[Coro::Event:: => AnyEvent::Impl::Coro::],
271	[Event:: => AnyEvent::Impl::Event::],	453	[Event:: => AnyEvent::Impl::Event::],
272	[Glib:: => AnyEvent::Impl::Glib::],	454	[Glib:: => AnyEvent::Impl::Glib::],
273	[Tk:: => AnyEvent::Impl::Tk::],	455	[Tk:: => AnyEvent::Impl::Tk::],
		456	[Wx:: => AnyEvent::Impl::POE::],
		457	[Prima:: => AnyEvent::Impl::POE::],
274	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	458	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
		459	# everything below here will not be autoprobed as the pureperl backend should work everywhere
		460	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		461	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		462	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
275	);	463	);
276		464
277	our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY);	465	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);
278		466
279	sub detect() {	467	sub detect() {
280	unless ($MODEL) {	468	unless ($MODEL) {
281	no strict 'refs';	469	no strict 'refs';
282		470
		471	if ($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 $verbose;
		478	}
		479	}
		480
283	# check for already loaded models	481	# check for already loaded models
		482	unless ($MODEL) {
284	for (@REGISTRY, @models) {	483	for (@REGISTRY, @models) {
285	my ($package, $model) = @$_;	484	my ($package, $model) = @$_;
286	if (${"$package\::VERSION"} > 0) {	485	if (${"$package\::VERSION"} > 0) {
287	if (eval "require $model") {	486	if (eval "require $model") {
288	$MODEL = $model;	487	$MODEL = $model;
289	warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1;	488	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
290	last;	489	last;
		490	}
291	}	491	}
292	}	492	}
293	}
294		493
295	unless ($MODEL) {	494	unless ($MODEL) {
296	# try to load a model	495	# try to load a model
297		496
298	for (@REGISTRY, @models) {	497	for (@REGISTRY, @models) {
299	my ($package, $model) = @$_;	498	my ($package, $model) = @$_;
300	if (eval "require $package"	499	if (eval "require $package"
301	and ${"$package\::VERSION"} > 0	500	and ${"$package\::VERSION"} > 0
302	and eval "require $model") {	501	and eval "require $model") {
303	$MODEL = $model;	502	$MODEL = $model;
304	warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1;	503	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
305	last;	504	last;
		505	}
306	}	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.";
307	}	510	}
308
309	$MODEL
310	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Event (or Coro+Event), Glib or Tk.";
311	}	511	}
312		512
313	unshift @ISA, $MODEL;	513	unshift @ISA, $MODEL;
314	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	514	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
315	}	515	}
…		…
373		573
374	# default implementation for ->child	574	# default implementation for ->child
375		575
376	our %PID_CB;	576	our %PID_CB;
377	our $CHLD_W;	577	our $CHLD_W;
		578	our $CHLD_DELAY_W;
378	our $PID_IDLE;	579	our $PID_IDLE;
379	our $WNOHANG;	580	our $WNOHANG;
380		581
381	sub _child_wait {	582	sub _child_wait {
382	while (0 <= (my $pid = waitpid -1, $WNOHANG)) {	583	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
383	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),	584	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),
384	(values %{ $PID_CB{0} \|\| {} });	585	(values %{ $PID_CB{0} \|\| {} });
385	}	586	}
386		587
387	undef $PID_IDLE;	588	undef $PID_IDLE;
388	}	589	}
389		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
390	sub child {	599	sub child {
391	my (undef, %arg) = @_;	600	my (undef, %arg) = @_;
392		601
393	defined (my $pid = $arg{pid} + 0)	602	defined (my $pid = $arg{pid} + 0)
394	or Carp::croak "required option 'pid' is missing";	603	or Carp::croak "required option 'pid' is missing";
…		…
398	unless ($WNOHANG) {	607	unless ($WNOHANG) {
399	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	608	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;
400	}	609	}
401		610
402	unless ($CHLD_W) {	611	unless ($CHLD_W) {
403	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_child_wait);	612	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
404	# child could be a zombie already	613	# child could be a zombie already, so make at least one round
405	$PID_IDLE \|\|= AnyEvent->timer (after => 0, cb => \&_child_wait);	614	&_sigchld;
406	}	615	}
407		616
408	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	617	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"
409	}	618	}
410		619
…		…
416		625
417	undef $CHLD_W unless keys %PID_CB;	626	undef $CHLD_W unless keys %PID_CB;
418	}	627	}
419		628
420	=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.
421		634
422	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
423	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
424	pushing, before the first watcher gets created, the package name of	637	pushing, before the first watcher gets created, the package name of
425	the event module and the package name of the interface to use onto	638	the event module and the package name of the interface to use onto
426	C<@AnyEvent::REGISTRY>. You can do that before and even without loading	639	C<@AnyEvent::REGISTRY>. You can do that before and even without loading
427	AnyEvent.	640	AnyEvent, so it is reasonably cheap.
428		641
429	Example:	642	Example:
430		643
431	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];	644	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
432		645
433	This tells AnyEvent to (literally) use the C<urxvt::anyevent::>	646	This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
434	package/class when it finds the C<urxvt> package/module is loaded. When	647	package/class when it finds the C<urxvt> package/module is already loaded.
		648
435	AnyEvent is loaded and asked to find a suitable event model, it will	649	When AnyEvent is loaded and asked to find a suitable event model, it
436	first check for the presence of urxvt.	650	will first check for the presence of urxvt by trying to C<use> the
		651	C<urxvt::anyevent> module.
437		652
438	The class should provide implementations for all watcher types (see	653	The class should provide implementations for all watcher types. See
439	L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib>	654	L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code)
440	(Source code) and so on for actual examples, use C<perldoc -m	655	and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to
441	AnyEvent::Impl::Glib> to see the sources).	656	see the sources.
442		657
		658	If you don't provide C<signal> and C<child> watchers than AnyEvent will
		659	provide suitable (hopefully) replacements.
		660
443	The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt)	661	The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt)
444	uses the above line as-is. An interface isn't included in AnyEvent	662	terminal emulator uses the above line as-is. An interface isn't included
445	because it doesn't make sense outside the embedded interpreter inside	663	in AnyEvent because it doesn't make sense outside the embedded interpreter
446	I<rxvt-unicode>, and it is updated and maintained as part of the	664	inside I<rxvt-unicode>, and it is updated and maintained as part of the
447	I<rxvt-unicode> distribution.	665	I<rxvt-unicode> distribution.
448		666
449	I<rxvt-unicode> also cheats a bit by not providing blocking access to	667	I<rxvt-unicode> also cheats a bit by not providing blocking access to
450	condition variables: code blocking while waiting for a condition will	668	condition variables: code blocking while waiting for a condition will
451	C<die>. This still works with most modules/usages, and blocking calls must	669	C<die>. This still works with most modules/usages, and blocking calls must
452	not be in an interactive application, so it makes sense.	670	not be done in an interactive application, so it makes sense.
453		671
454	=head1 ENVIRONMENT VARIABLES	672	=head1 ENVIRONMENT VARIABLES
455		673
456	The following environment variables are used by this module:	674	The following environment variables are used by this module:
457		675
458	C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event	676	=over 4
459	model gets used.
460		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
461	=head1 EXAMPLE	709	=head1 EXAMPLE PROGRAM
462		710
463	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
464	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
465	when the user enters quit:	713	program when the user enters quit:
466		714
467	use AnyEvent;	715	use AnyEvent;
468		716
469	my $cv = AnyEvent->condvar;	717	my $cv = AnyEvent->condvar;
470		718
471	my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	719	my $io_watcher = AnyEvent->io (
		720	fh => \*STDIN,
		721	poll => 'r',
		722	cb => sub {
472	warn "io event <$_[0]>\n"; # will always output <r>	723	warn "io event <$_[0]>\n"; # will always output <r>
473	chomp (my $input = <STDIN>); # read a line	724	chomp (my $input = <STDIN>); # read a line
474	warn "read: $input\n"; # output what has been read	725	warn "read: $input\n"; # output what has been read
475	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	726	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i
		727	},
476	});	728	);
477		729
478	my $time_watcher; # can only be used once	730	my $time_watcher; # can only be used once
479		731
480	sub new_timer {	732	sub new_timer {
481	$timer = AnyEvent->timer (after => 1, cb => sub {	733	$timer = AnyEvent->timer (after => 1, cb => sub {
…		…
563	$txn->{finished}->wait;	815	$txn->{finished}->wait;
564	return $txn->{result};	816	return $txn->{result};
565		817
566	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)
567	that occured during request processing. The C<result> method detects	819	that occured during request processing. The C<result> method detects
568	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)
569	and just throws the exception, which means connection errors and other	821	and just throws the exception, which means connection errors and other
570	problems get reported tot he code that tries to use the result, not in a	822	problems get reported tot he code that tries to use the result, not in a
571	random callback.	823	random callback.
572		824
573	All of this enables the following usage styles:	825	All of this enables the following usage styles:
574		826
575	1. Blocking:	827	1. Blocking:
576		828
577	my $data = $fcp->client_get ($url);	829	my $data = $fcp->client_get ($url);
578		830
579	2. Blocking, but parallelizing:	831	2. Blocking, but running in parallel:
580		832
581	my @datas = map $_->result,	833	my @datas = map $_->result,
582	map $fcp->txn_client_get ($_),	834	map $fcp->txn_client_get ($_),
583	@urls;	835	@urls;
584		836
585	Both blocking examples work without the module user having to know	837	Both blocking examples work without the module user having to know
586	anything about events.	838	anything about events.
587		839
588	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:
589		841
590	use Event;	842	use EV;
591		843
592	$fcp->txn_client_get ($url)->cb (sub {	844	$fcp->txn_client_get ($url)->cb (sub {
593	my $txn = shift;	845	my $txn = shift;
594	my $data = $txn->result;	846	my $data = $txn->result;
595	...	847	...
596	});	848	});
597		849
598	Event::loop;	850	EV::loop;
599		851
600	3b. The module user could use AnyEvent, too:	852	3b. The module user could use AnyEvent, too:
601		853
602	use AnyEvent;	854	use AnyEvent;
603		855
…		…
608	$quit->broadcast;	860	$quit->broadcast;
609	});	861	});
610		862
611	$quit->wait;	863	$quit->wait;
612		864
		865
		866	=head1 BENCHMARK
		867
		868	To give you an idea of the performance an doverheads that AnyEvent adds
		869	over the backends, here is a benchmark of various supported backends. The
		870	benchmark creates a lot of timers (with zero timeout) and io events
		871	(watching STDOUT, a pty, to become writable).
		872
		873	Explanation of the fields:
		874
		875	I<watcher> is the number of event watchers created/destroyed. Sicne
		876	different event models have vastly different performance each backend was
		877	handed a number of watchers so that overall runtime is acceptable and
		878	similar to all backends (and keep them from crashing).
		879
		880	I<bytes> is the number of bytes (as measured by resident set size) used by
		881	each watcher.
		882
		883	I<create> is the time, in microseconds, to create a single watcher.
		884
		885	I<invoke> is the time, in microseconds, used to invoke a simple callback
		886	that simply counts down.
		887
		888	I<destroy> is the time, in microseconds, to destroy a single watcher.
		889
		890	name watcher bytes create invoke destroy comment
		891	EV/EV 400000 244 0.56 0.46 0.31 EV native interface
		892	EV/Any 100000 610 3.52 0.91 0.75
		893	CoroEV/Any 100000 610 3.49 0.92 0.75 coroutines + Coro::Signal
		894	Perl/Any 10000 654 4.64 1.22 0.77 pure perl implementation
		895	Event/Event 10000 523 28.05 21.38 5.22 Event native interface
		896	Event/Any 10000 943 34.43 20.48 1.39
		897	Glib/Any 16000 1357 96.99 12.55 55.51 quadratic behaviour
		898	Tk/Any 2000 1855 27.01 66.61 14.03 SEGV with >> 2000 watchers
		899	POE/Select 2000 6343 94.69 807.65 562.69 POE::Loop::Select
		900	POE/Event 2000 6644 108.15 768.19 14.33 POE::Loop::Event
		901
		902	Discussion: The benchmark does I<not> bench scalability of the
		903	backend. For example a select-based backend (such as the pureperl one) can
		904	never compete with a backend using epoll. In this benchmark, only a single
		905	filehandle is used.
		906
		907	EV is the sole leader regarding speed and memory use, which are both
		908	maximal/minimal. Even when going through AnyEvent, there is only one event
		909	loop that uses less memory (the Event module natively), and no faster
		910	event model.
		911
		912	The pure perl implementation is hit in a few sweet spots (both the
		913	zero timeout and the use of a single fd hit optimisations in the perl
		914	interpreter and the backend itself), but it shows that it adds very little
		915	overhead in itself. Like any select-based backend it's performance becomes
		916	really bad with lots of file descriptors.
		917
		918	The Event module has a relatively high setup and callback invocation cost,
		919	but overall scores on the third place.
		920
		921	Glib has a little higher memory cost, a bit fster callback invocation and
		922	has a similar speed as Event.
		923
		924	The Tk backend works relatively well, the fact that it crashes with
		925	more than 2000 watchers is a big setback, however, as correctness takes
		926	precedence over speed.
		927
		928	POE, regardless of backend (wether it's pure perl select backend or the
		929	Event backend) shows abysmal performance and memory usage: Watchers use
		930	almost 30 times as much memory as EV watchers, and 10 times as much memory
		931	as both Event or EV via AnyEvent.
		932
		933	Summary: using EV through AnyEvent is faster than any other event
		934	loop. The overhead AnyEvent adds can be very small, and you should avoid
		935	POE like the plague if you want performance or reasonable memory usage.
		936
		937
		938	=head1 FORK
		939
		940	Most event libraries are not fork-safe. The ones who are usually are
		941	because they are so inefficient. Only L<EV> is fully fork-aware.
		942
		943	If you have to fork, you must either do so I<before> creating your first
		944	watcher OR you must not use AnyEvent at all in the child.
		945
		946
		947	=head1 SECURITY CONSIDERATIONS
		948
		949	AnyEvent can be forced to load any event model via
		950	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to
		951	execute arbitrary code or directly gain access, it can easily be used to
		952	make the program hang or malfunction in subtle ways, as AnyEvent watchers
		953	will not be active when the program uses a different event model than
		954	specified in the variable.
		955
		956	You can make AnyEvent completely ignore this variable by deleting it
		957	before the first watcher gets created, e.g. with a C<BEGIN> block:
		958
		959	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
		960
		961	use AnyEvent;
		962
		963
613	=head1 SEE ALSO	964	=head1 SEE ALSO
614		965
615	Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>.	966	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,
		967	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,
		968	L<Event::Lib>, L<Qt>, L<POE>.
616		969
		970	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,
617	Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>.	971	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,
		972	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,
		973	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.
618		974
619	Nontrivial usage example: L<Net::FCP>.	975	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.
620		976
621	=head1	977
		978	=head1 AUTHOR
		979
		980	Marc Lehmann <schmorp@schmorp.de>
		981	http://home.schmorp.de/
622		982
623	=cut	983	=cut
624		984
625	1	985	1
626		986

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.33 by root, Fri Nov 9 19:34:32 2007 UTC vs. Revision 1.64 by root, Fri Apr 25 06:54:08 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.33 by root, Fri Nov 9 19:34:32 2007 UTC vs.
Revision 1.64 by root, Fri Apr 25 06:54:08 2008 UTC