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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.51 by root, Wed Apr 16 15:10:10 2008 UTC vs.
Revision 1.70 by root, Fri Apr 25 07:25:44 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	EV, Event, Coro::EV, Coro::Event, 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		22
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		24
…		…
29	policy> and AnyEvent is I<small and efficient>.	29	policy> and AnyEvent is I<small and efficient>.
30		30
31	First and foremost, I<AnyEvent is not an event model> itself, it only	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	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,	33	pragmatic way. For event models and certain classes of immortals alike,
34	the statement "there can only be one" is a bitter reality, and AnyEvent	34	the statement "there can only be one" is a bitter reality: In general,
35	helps hiding the differences.	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.
36		37
37	The goal of AnyEvent is to offer module authors the ability to do event	38	The goal of AnyEvent is to offer module authors the ability to do event
38	programming (waiting for I/O or timer events) without subscribing to a	39	programming (waiting for I/O or timer events) without subscribing to a
39	religion, a way of living, and most importantly: without forcing your	40	religion, a way of living, and most importantly: without forcing your
40	module users into the same thing by forcing them to use the same event	41	module users into the same thing by forcing them to use the same event
41	model you use.	42	model you use.
42		43
43	For modules like POE or IO::Async (which is actually doing all I/O	44	For modules like POE or IO::Async (which is a total misnomer as it is
44	I<synchronously>...), using them in your module is like joining a	45	actually doing all I/O I<synchronously>...), using them in your module is
45	cult: After you joined, you are dependent on them and you cannot use	46	like joining a cult: After you joined, you are dependent on them and you
46	anything else, as it is simply incompatible to everything that isn't	47	cannot use anything else, as it is simply incompatible to everything that
47	itself.	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.
48		50
49	AnyEvent + POE works fine. AnyEvent + Glib works fine. AnyEvent + Tk	51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
50	works fine etc. etc. but none of these work together with the rest: POE	52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
51	+ IO::Async? no go. Tk + Event? no go. If your module uses one of	53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if
52	those, every user of your module has to use it, too. If your module	54	your module uses one of those, every user of your module has to use it,
53	uses AnyEvent, it works transparently with all event models it supports	55	too. But if your module uses AnyEvent, it works transparently with all
54	(including stuff like POE and IO::Async).	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).
55		59
56	In addition of being free of having to use I<the one and only true event	60	In addition to being free of having to use I<the one and only true event
57	model>, AnyEvent also is free of bloat and policy: with POE or similar	61	model>, AnyEvent also is free of bloat and policy: with POE or similar
58	modules, you get an enourmous amount of code and strict rules you have	62	modules, you get an enourmous amount of code and strict rules you have to
59	to follow. AnyEvent, on the other hand, is lean and to the point by only	63	follow. AnyEvent, on the other hand, is lean and up to the point, by only
60	offering the functionality that is useful, in as thin as a wrapper as	64	offering the functionality that is necessary, in as thin as a wrapper as
61	technically possible.	65	technically possible.
62		66
63	Of course, if you want lots of policy (this can arguably be somewhat	67	Of course, if you want lots of policy (this can arguably be somewhat
64	useful) and you want to force your users to use the one and only event	68	useful) and you want to force your users to use the one and only event
65	model, you should I<not> use this module.	69	model, you should I<not> use this module.
…		…
70	L<AnyEvent> provides an identical interface to multiple event loops. This	74	L<AnyEvent> provides an identical interface to multiple event loops. This
71	allows module authors to utilise an event loop without forcing module	75	allows module authors to utilise an event loop without forcing module
72	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
73	peacefully at any one time).	77	peacefully at any one time).
74		78
75	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>
76	module.	80	module.
77		81
78	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
79	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
80	loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, L<Event>, L<Glib>, L<Tk>. The	84	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,
		85	L<Event>, L<Glib>, L<Tk>, L<AnyEvent::Impl::Perl>, L<Event::Lib>, L<Qt>,
81	first one found is used. If none are found, the module tries to load these	86	L<POE>. The first one found is used. If none are found, the module tries
82	modules in the order given. The first one that could be successfully	87	to load these modules (excluding Event::Lib, Qt and POE as the pure perl
83	loaded will be used. If still none could be found, AnyEvent will fall back	88	adaptor should always succeed) in the order given. The first one that can
84	to a pure-perl event loop, which is also not very efficient.	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.
85		92
86	Because AnyEvent first checks for modules that are already loaded, loading	93	Because AnyEvent first checks for modules that are already loaded, loading
87	an Event model explicitly before first using AnyEvent will likely make	94	an event model explicitly before first using AnyEvent will likely make
88	that model the default. For example:	95	that model the default. For example:
89		96
90	use Tk;	97	use Tk;
91	use AnyEvent;	98	use AnyEvent;
92		99
93	# .. 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...
94		105
95	The pure-perl implementation of AnyEvent is called	106	The pure-perl implementation of AnyEvent is called
96	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
97	explicitly.	108	explicitly.
98		109
…		…
101	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
102	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
103	the callback to call, the filehandle to watch, etc.	114	the callback to call, the filehandle to watch, etc.
104		115
105	These watchers are normal Perl objects with normal Perl lifetime. After	116	These watchers are normal Perl objects with normal Perl lifetime. After
106	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
107	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
108	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
109	references to it).	123	to it).
110		124
111	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.
112		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
113	=head2 IO WATCHERS	141	=head2 IO WATCHERS
114		142
115	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
116	the following mandatory arguments:	144	with the following mandatory key-value pairs as arguments:
117		145
118	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
119	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
120	a watcher waiting for "r"eadable or "w"ritable events. C<cb> the callback	148	creates a watcher waiting for "r"eadable or "w"ritable events,
121	to invoke everytime the filehandle becomes ready.	149	respectively. C<cb> is the callback to invoke each time the file handle
		150	becomes ready.
122		151
123	Filehandles will be kept alive, so as long as the watcher exists, the	152	As long as the I/O watcher exists it will keep the file descriptor or a
124	filehandle exists, too.	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.
125		161
126	Example:	162	Example:
127		163
128	# 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
129	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	165	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
…		…
135	=head2 TIME WATCHERS	171	=head2 TIME WATCHERS
136		172
137	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 >>
138	method with the following mandatory arguments:	174	method with the following mandatory arguments:
139		175
140	C<after> after how many seconds (fractions are supported) should the timer	176	C<after> specifies after how many seconds (fractional values are
141	activate. C<cb> the callback to invoke.	177	supported) should the timer activate. C<cb> the callback to invoke in that
		178	case.
142		179
143	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
144	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
145	and Glib).	182	and Glib).
146		183
…		…
152	});	189	});
153		190
154	# to cancel the timer:	191	# to cancel the timer:
155	undef $w;	192	undef $w;
156		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
157	=head2 CONDITION WATCHERS	268	=head2 CONDITION VARIABLES
158		269
159	Condition watchers can be created by calling the C<< AnyEvent->condvar >>	270	Condition variables can be created by calling the C<< AnyEvent->condvar >>
160	method without any arguments.	271	method without any arguments.
161		272
162	A condition watcher watches for a condition - precisely that the C<<	273	A condition variable waits for a condition - precisely that the C<<
163	->broadcast >> method has been called.	274	->broadcast >> method has been called.
164		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
165	Note that condition watchers recurse into the event loop - if you have	286	Note that condition variables recurse into the event loop - if you have
166	two watchers that call C<< ->wait >> in a round-robbin fashion, you	287	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you
167	lose. Therefore, condition watchers are good to export to your caller, but	288	lose. Therefore, condition variables are good to export to your caller, but
168	you should avoid making a blocking wait, at least in callbacks, as this	289	you should avoid making a blocking wait yourself, at least in callbacks,
169	usually asks for trouble.	290	as this asks for trouble.
170		291
171	The watcher has only two methods:	292	This object has two methods:
172		293
173	=over 4	294	=over 4
174		295
175	=item $cv->wait	296	=item $cv->wait
176		297
…		…
179		300
180	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
181	immediately.	302	immediately.
182		303
183	Not all event models support a blocking wait - some die in that case	304	Not all event models support a blocking wait - some die in that case
184	(programs might want to do that so they stay interactive), so I<if you	305	(programs might want to do that to stay interactive), so I<if you are
185	are using this from a module, never require a blocking wait>, but let the	306	using this from a module, never require a blocking wait>, but let the
186	caller decide wether the call will block or not (for example, by coupling	307	caller decide whether the call will block or not (for example, by coupling
187	condition variables with some kind of request results and supporting	308	condition variables with some kind of request results and supporting
188	callbacks so the caller knows that getting the result will not block,	309	callbacks so the caller knows that getting the result will not block,
189	while still suppporting blocking waits if the caller so desires).	310	while still suppporting blocking waits if the caller so desires).
190		311
191	Another reason I<never> to C<< ->wait >> in a module is that you cannot	312	Another reason I<never> to C<< ->wait >> in a module is that you cannot
192	sensibly have two C<< ->wait >>'s in parallel, as that would require	313	sensibly have two C<< ->wait >>'s in parallel, as that would require
193	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	314	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
194	can supply (the coroutine-aware backends C<Coro::EV> and C<Coro::Event>	315	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and
195	explicitly support concurrent C<< ->wait >>'s from different coroutines,	316	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
196	however).	317	from different coroutines, however).
197		318
198	=item $cv->broadcast	319	=item $cv->broadcast
199		320
200	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
201	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
202	is waiting the broadcast will be remembered..	323	called. If nobody is waiting the broadcast will be remembered..
		324
		325	=back
203		326
204	Example:	327	Example:
205		328
206	# wait till the result is ready	329	# wait till the result is ready
207	my $result_ready = AnyEvent->condvar;	330	my $result_ready = AnyEvent->condvar;
208		331
209	# do something such as adding a timer	332	# do something such as adding a timer
210	# or socket watcher the calls $result_ready->broadcast	333	# or socket watcher the calls $result_ready->broadcast
211	# 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	);
212		340
		341	# this "blocks" (while handling events) till the watcher
		342	# calls broadcast
213	$result_ready->wait;	343	$result_ready->wait;
214		344
215	=back	345	=head1 GLOBAL VARIABLES AND FUNCTIONS
216
217	=head2 SIGNAL WATCHERS
218
219	You can listen for signals using a signal watcher, C<signal> is the signal
220	I<name> without any C<SIG> prefix. Multiple signals events can be clumped
221	together into one callback invocation, and callback invocation might or
222	might not be asynchronous.
223
224	These watchers might use C<%SIG>, so programs overwriting those signals
225	directly will likely not work correctly.
226
227	Example: exit on SIGINT
228
229	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
230
231	=head2 CHILD PROCESS WATCHERS
232
233	You can also listen for the status of a child process specified by the
234	C<pid> argument (or any child if the pid argument is 0). The watcher will
235	trigger as often as status change for the child are received. This works
236	by installing a signal handler for C<SIGCHLD>. The callback will be called with
237	the pid and exit status (as returned by waitpid).
238
239	Example: wait for pid 1333
240
241	my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" });
242
243	=head1 GLOBALS
244		346
245	=over 4	347	=over 4
246		348
247	=item $AnyEvent::MODEL	349	=item $AnyEvent::MODEL
248		350
…		…
254		356
255	The known classes so far are:	357	The known classes so far are:
256		358
257	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.	359	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
258	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.	360	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
259	AnyEvent::Impl::EV based on EV (an interface to libev, also best choice).	361	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
260	AnyEvent::Impl::Event based on Event, also second best choice :)	362	AnyEvent::Impl::Event based on Event, second best choice.
261	AnyEvent::Impl::Glib based on Glib, third-best choice.	363	AnyEvent::Impl::Glib based on Glib, third-best choice.
262	AnyEvent::Impl::Tk based on Tk, very bad choice.	364	AnyEvent::Impl::Tk based on Tk, very bad choice.
263	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.	365	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
		366	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
		367	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		368	AnyEvent::Impl::POE based on POE, not generic enough for full support.
		369
		370	There is no support for WxWidgets, as WxWidgets has no support for
		371	watching file handles. However, you can use WxWidgets through the
		372	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
		373	second, which was considered to be too horrible to even consider for
		374	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
		375	it's adaptor.
		376
		377	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
		378	autodetecting them.
264		379
265	=item AnyEvent::detect	380	=item AnyEvent::detect
266		381
267	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if	382	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
268	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
269	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.
270		386
271	=back	387	=back
272		388
273	=head1 WHAT TO DO IN A MODULE	389	=head1 WHAT TO DO IN A MODULE
274		390
275	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
276	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.
277		393
278	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
279	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
280	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
281	to load the event module first.	397	to load the event module first.
282		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
283	=head1 WHAT TO DO IN THE MAIN PROGRAM	409	=head1 WHAT TO DO IN THE MAIN PROGRAM
284		410
285	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
286	dictate which event model to use.	412	dictate which event model to use.
287		413
288	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
289	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.
290		417
291	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
292	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
293	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
294	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
295	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
296	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
297	correct one yourself.	424	might chose the wrong one unless you load the correct one yourself.
298		425
299	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
300	loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is	427	loading the C<AnyEvent::Impl::Perl> module, which gives you similar
301	generally better.	428	behaviour everywhere, but letting AnyEvent chose is generally better.
302		429
303	=cut	430	=cut
304		431
305	package AnyEvent;	432	package AnyEvent;
306		433
307	no warnings;	434	no warnings;
308	use strict;	435	use strict;
309		436
310	use Carp;	437	use Carp;
311		438
312	our $VERSION = '3.1';	439	our $VERSION = '3.3';
313	our $MODEL;	440	our $MODEL;
314		441
315	our $AUTOLOAD;	442	our $AUTOLOAD;
316	our @ISA;	443	our @ISA;
317		444
…		…
324	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],	451	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
325	[EV:: => AnyEvent::Impl::EV::],	452	[EV:: => AnyEvent::Impl::EV::],
326	[Event:: => AnyEvent::Impl::Event::],	453	[Event:: => AnyEvent::Impl::Event::],
327	[Glib:: => AnyEvent::Impl::Glib::],	454	[Glib:: => AnyEvent::Impl::Glib::],
328	[Tk:: => AnyEvent::Impl::Tk::],	455	[Tk:: => AnyEvent::Impl::Tk::],
		456	[Wx:: => AnyEvent::Impl::POE::],
		457	[Prima:: => AnyEvent::Impl::POE::],
329	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	458	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
		459	# everything below here will not be autoprobed as the pureperl backend should work everywhere
		460	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		461	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		462	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
330	);	463	);
331		464
332	our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY);	465	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);
333		466
334	sub detect() {	467	sub detect() {
335	unless ($MODEL) {	468	unless ($MODEL) {
336	no strict 'refs';	469	no strict 'refs';
337		470
		471	if ($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 $verbose;
		478	}
		479	}
		480
338	# check for already loaded models	481	# check for already loaded models
		482	unless ($MODEL) {
339	for (@REGISTRY, @models) {	483	for (@REGISTRY, @models) {
340	my ($package, $model) = @$_;	484	my ($package, $model) = @$_;
341	if (${"$package\::VERSION"} > 0) {	485	if (${"$package\::VERSION"} > 0) {
342	if (eval "require $model") {	486	if (eval "require $model") {
343	$MODEL = $model;	487	$MODEL = $model;
344	warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1;	488	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
345	last;	489	last;
		490	}
346	}	491	}
347	}	492	}
348	}
349		493
350	unless ($MODEL) {	494	unless ($MODEL) {
351	# try to load a model	495	# try to load a model
352		496
353	for (@REGISTRY, @models) {	497	for (@REGISTRY, @models) {
354	my ($package, $model) = @$_;	498	my ($package, $model) = @$_;
355	if (eval "require $package"	499	if (eval "require $package"
356	and ${"$package\::VERSION"} > 0	500	and ${"$package\::VERSION"} > 0
357	and eval "require $model") {	501	and eval "require $model") {
358	$MODEL = $model;	502	$MODEL = $model;
359	warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1;	503	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
360	last;	504	last;
		505	}
361	}	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.";
362	}	510	}
363
364	$MODEL
365	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event), Glib or Tk.";
366	}	511	}
367		512
368	unshift @ISA, $MODEL;	513	unshift @ISA, $MODEL;
369	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	514	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
370	}	515	}
…		…
481	undef $CHLD_W unless keys %PID_CB;	626	undef $CHLD_W unless keys %PID_CB;
482	}	627	}
483		628
484	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	629	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
485		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.
		634
486	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
487	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
488	pushing, before the first watcher gets created, the package name of	637	pushing, before the first watcher gets created, the package name of
489	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
490	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
491	AnyEvent.	640	AnyEvent, so it is reasonably cheap.
492		641
493	Example:	642	Example:
494		643
495	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];	644	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
496		645
497	This tells AnyEvent to (literally) use the C<urxvt::anyevent::>	646	This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
498	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
499	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
500	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.
501		652
502	The class should provide implementations for all watcher types (see	653	The class should provide implementations for all watcher types. See
503	L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib>	654	L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code)
504	(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
505	AnyEvent::Impl::Glib> to see the sources).	656	see the sources.
506		657
		658	If you don't provide C<signal> and C<child> watchers than AnyEvent will
		659	provide suitable (hopefully) replacements.
		660
507	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)
508	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
509	because it doesn't make sense outside the embedded interpreter inside	663	in AnyEvent because it doesn't make sense outside the embedded interpreter
510	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
511	I<rxvt-unicode> distribution.	665	I<rxvt-unicode> distribution.
512		666
513	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
514	condition variables: code blocking while waiting for a condition will	668	condition variables: code blocking while waiting for a condition will
515	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
516	not be in an interactive application, so it makes sense.	670	not be done in an interactive application, so it makes sense.
517		671
518	=head1 ENVIRONMENT VARIABLES	672	=head1 ENVIRONMENT VARIABLES
519		673
520	The following environment variables are used by this module:	674	The following environment variables are used by this module:
521		675
522	C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event	676	=over 4
523	model gets used.
524		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
525	=head1 EXAMPLE	709	=head1 EXAMPLE PROGRAM
526		710
527	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
528	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
529	when the user enters quit:	713	program when the user enters quit:
530		714
531	use AnyEvent;	715	use AnyEvent;
532		716
533	my $cv = AnyEvent->condvar;	717	my $cv = AnyEvent->condvar;
534		718
535	my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	719	my $io_watcher = AnyEvent->io (
		720	fh => \*STDIN,
		721	poll => 'r',
		722	cb => sub {
536	warn "io event <$_[0]>\n"; # will always output <r>	723	warn "io event <$_[0]>\n"; # will always output <r>
537	chomp (my $input = <STDIN>); # read a line	724	chomp (my $input = <STDIN>); # read a line
538	warn "read: $input\n"; # output what has been read	725	warn "read: $input\n"; # output what has been read
539	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	726	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i
		727	},
540	});	728	);
541		729
542	my $time_watcher; # can only be used once	730	my $time_watcher; # can only be used once
543		731
544	sub new_timer {	732	sub new_timer {
545	$timer = AnyEvent->timer (after => 1, cb => sub {	733	$timer = AnyEvent->timer (after => 1, cb => sub {
…		…
627	$txn->{finished}->wait;	815	$txn->{finished}->wait;
628	return $txn->{result};	816	return $txn->{result};
629		817
630	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)
631	that occured during request processing. The C<result> method detects	819	that occured during request processing. The C<result> method detects
632	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)
633	and just throws the exception, which means connection errors and other	821	and just throws the exception, which means connection errors and other
634	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
635	random callback.	823	random callback.
636		824
637	All of this enables the following usage styles:	825	All of this enables the following usage styles:
…		…
672	$quit->broadcast;	860	$quit->broadcast;
673	});	861	});
674		862
675	$quit->wait;	863	$quit->wait;
676		864
		865
		866	=head1 BENCHMARK
		867
		868	To give you an idea of the performance and overheads that AnyEvent adds
		869	over the event loops directly, here is a benchmark of various supported
		870	event models natively and with anyevent. The benchmark creates a lot of
		871	timers (with a zero timeout) and io watchers (watching STDOUT, a pty, to
		872	become writable, which it is), lets them fire exactly once and destroys
		873	them again.
		874
		875	=head2 Explanation of the columns
		876
		877	I<watcher> is the number of event watchers created/destroyed. Since
		878	different event models feature vastly different performances, each event
		879	loop was given a number of watchers so that overall runtime is acceptable
		880	and similar between tested event loop (and keep them from crashing): Glib
		881	would probably take thousands of years if asked to process the same number
		882	of watchers as EV in this benchmark.
		883
		884	I<bytes> is the number of bytes (as measured by the resident set size,
		885	RSS) consumed by each watcher. This method of measuring captures both C
		886	and Perl-based overheads.
		887
		888	I<create> is the time, in microseconds (millionths of seconds), that it
		889	takes to create a single watcher. The callback is a closure shared between
		890	all watchers, to avoid adding memory overhead. That means closure creation
		891	and memory usage is not included in the figures.
		892
		893	I<invoke> is the time, in microseconds, used to invoke a simple
		894	callback. The callback simply counts down a Perl variable and after it was
		895	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to
		896	signal the end of this phase.
		897
		898	I<destroy> is the time, in microseconds, that it takes destroy a single
		899	watcher.
		900
		901	=head2 Results
		902
		903	name watcher bytes create invoke destroy comment
		904	EV/EV 400000 244 0.56 0.46 0.31 EV native interface
		905	EV/Any 100000 610 3.52 0.91 0.75 EV + AnyEvent watchers
		906	CoroEV/Any 100000 610 3.49 0.92 0.75 coroutines + Coro::Signal
		907	Perl/Any 16000 654 4.64 1.22 0.77 pure perl implementation
		908	Event/Event 16000 523 28.05 21.38 0.86 Event native interface
		909	Event/Any 16000 943 34.43 20.48 1.39 Event + AnyEvent watchers
		910	Glib/Any 16000 1357 96.99 12.55 55.51 quadratic behaviour
		911	Tk/Any 2000 1855 27.01 66.61 14.03 SEGV with >> 2000 watchers
		912	POE/Event 2000 6644 108.15 768.19 14.33 via POE::Loop::Event
		913	POE/Select 2000 6343 94.69 807.65 562.69 via POE::Loop::Select
		914
		915	=head2 Discussion
		916
		917	The benchmark does I<not> measure scalability of the event loop very
		918	well. For example, a select-based event loop (such as the pure perl one)
		919	can never compete with an event loop that uses epoll when the number of
		920	file descriptors grows high. In this benchmark, only a single filehandle
		921	is used (although some of the AnyEvent adaptors dup() its file descriptor
		922	to worka round bugs).
		923
		924	C<EV> is the sole leader regarding speed and memory use, which are both
		925	maximal/minimal, respectively. Even when going through AnyEvent, there is
		926	only one event loop that uses less memory (the C<Event> module natively), and
		927	no faster event model, not event C<Event> natively.
		928
		929	The pure perl implementation is hit in a few sweet spots (both the
		930	zero timeout and the use of a single fd hit optimisations in the perl
		931	interpreter and the backend itself). Nevertheless tis shows that it
		932	adds very little overhead in itself. Like any select-based backend its
		933	performance becomes really bad with lots of file descriptors, of course,
		934	but this was not subjetc of this benchmark.
		935
		936	The C<Event> module has a relatively high setup and callback invocation cost,
		937	but overall scores on the third place.
		938
		939	C<Glib>'s memory usage is quite a bit bit higher, features a faster
		940	callback invocation and overall lands in the same class as C<Event>.
		941
		942	The C<Tk> adaptor works relatively well, the fact that it crashes with
		943	more than 2000 watchers is a big setback, however, as correctness takes
		944	precedence over speed. Nevertheless, its performance is surprising, as the
		945	file descriptor is dup()ed for each watcher. This shows that the dup()
		946	employed by some adaptors is not a big performance issue (it does incur a
		947	hidden memory cost inside the kernel, though).
		948
		949	C<POE>, regardless of backend (wether using its pure perl select-based
		950	backend or the Event backend) shows abysmal performance and memory
		951	usage: Watchers use almost 30 times as much memory as EV watchers, and 10
		952	times as much memory as both Event or EV via AnyEvent. Watcher invocation
		953	is almost 700 times slower as with AnyEvent's pure perl implementation.
		954
		955	Summary: using EV through AnyEvent is faster than any other event
		956	loop. The overhead AnyEvent adds can be very small, and you should avoid
		957	POE like the plague if you want performance or reasonable memory usage.
		958
		959
		960	=head1 FORK
		961
		962	Most event libraries are not fork-safe. The ones who are usually are
		963	because they are so inefficient. Only L<EV> is fully fork-aware.
		964
		965	If you have to fork, you must either do so I<before> creating your first
		966	watcher OR you must not use AnyEvent at all in the child.
		967
		968
		969	=head1 SECURITY CONSIDERATIONS
		970
		971	AnyEvent can be forced to load any event model via
		972	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to
		973	execute arbitrary code or directly gain access, it can easily be used to
		974	make the program hang or malfunction in subtle ways, as AnyEvent watchers
		975	will not be active when the program uses a different event model than
		976	specified in the variable.
		977
		978	You can make AnyEvent completely ignore this variable by deleting it
		979	before the first watcher gets created, e.g. with a C<BEGIN> block:
		980
		981	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
		982
		983	use AnyEvent;
		984
		985
677	=head1 SEE ALSO	986	=head1 SEE ALSO
678		987
679	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	988	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,
680	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>.	989	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,
		990	L<Event::Lib>, L<Qt>, L<POE>.
681		991
682	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	992	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,
		993	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,
		994	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,
683	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>,	995	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.
684	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>.
685		996
686	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	997	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.
687		998
688	=head1	999
		1000	=head1 AUTHOR
		1001
		1002	Marc Lehmann <schmorp@schmorp.de>
		1003	http://home.schmorp.de/
689		1004
690	=cut	1005	=cut
691		1006
692	1	1007	1
693		1008

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.51 by root, Wed Apr 16 15:10:10 2008 UTC vs. Revision 1.70 by root, Fri Apr 25 07:25:44 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.51 by root, Wed Apr 16 15:10:10 2008 UTC vs.
Revision 1.70 by root, Fri Apr 25 07:25:44 2008 UTC