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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.54 by root, Tue Apr 22 05:12:19 2008 UTC vs.
Revision 1.66 by root, Fri Apr 25 06:58:31 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
80	module.	80	module.
81		81
82	During the first call of any watcher-creation method, the module tries	82	During the first call of any watcher-creation method, the module tries
83	to detect the currently loaded event loop by probing whether one of the	83	to detect the currently loaded event loop by probing whether one of the
84	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	84	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,
85	L<Event>, L<Glib>, L<Tk>. The first one found is used. If none are found,	85	L<Event>, L<Glib>, L<Tk>, L<AnyEvent::Impl::Perl>, L<Event::Lib>, L<Qt>,
86	the module tries to load these modules in the stated order. The first one	86	L<POE>. The first one found is used. If none are found, the module tries
		87	to load these modules (excluding Event::Lib, Qt and POE as the pure perl
		88	adaptor should always succeed) in the order given. The first one that can
87	that can be successfully loaded will be used. If, after this, still none	89	be successfully loaded will be used. If, after this, still none could be
88	could be found, AnyEvent will fall back to a pure-perl event loop, which	90	found, AnyEvent will fall back to a pure-perl event loop, which is not
89	is not very efficient, but should work everywhere.	91	very efficient, but should work everywhere.
90		92
91	Because AnyEvent first checks for modules that are already loaded, loading	93	Because AnyEvent first checks for modules that are already loaded, loading
92	an event model explicitly before first using AnyEvent will likely make	94	an event model explicitly before first using AnyEvent will likely make
93	that model the default. For example:	95	that model the default. For example:
94		96
…		…
145	events. C<poll> must be a string that is either C<r> or C<w>, which	147	events. C<poll> must be a string that is either C<r> or C<w>, which
146	creates a watcher waiting for "r"eadable or "w"ritable events,	148	creates a watcher waiting for "r"eadable or "w"ritable events,
147	respectively. C<cb> is the callback to invoke each time the file handle	149	respectively. C<cb> is the callback to invoke each time the file handle
148	becomes ready.	150	becomes ready.
149		151
150	File handles 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
151	file handle exists, too.	153	copy of it alive/open.
152		154
153	It is not allowed to close a file handle as long as any watcher is active	155	It is not allowed to close a file handle as long as any watcher is active
154	on the underlying file descriptor.	156	on the underlying file descriptor.
155		157
156	Some event loops issue spurious readyness notifications, so you should	158	Some event loops issue spurious readyness notifications, so you should
…		…
206		208
207	There are two ways to handle timers: based on real time (relative, "fire	209	There are two ways to handle timers: based on real time (relative, "fire
208	in 10 seconds") and based on wallclock time (absolute, "fire at 12	210	in 10 seconds") and based on wallclock time (absolute, "fire at 12
209	o'clock").	211	o'clock").
210		212
211	While most event loops expect timers to specified in a relative way, they use	213	While most event loops expect timers to specified in a relative way, they
212	absolute time internally. This makes a difference when your clock "jumps",	214	use absolute time internally. This makes a difference when your clock
213	for example, when ntp decides to set your clock backwards from the wrong 2014-01-01 to	215	"jumps", for example, when ntp decides to set your clock backwards from
214	2008-01-01, a watcher that you created to fire "after" a second might actually take	216	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to
215	six years to finally fire.	217	fire "after" a second might actually take six years to finally fire.
216		218
217	AnyEvent cannot compensate for this. The only event loop that is conscious	219	AnyEvent cannot compensate for this. The only event loop that is conscious
218	about these issues is L<EV>, which offers both relative (ev_timer) and	220	about these issues is L<EV>, which offers both relative (ev_timer, based
219	absolute (ev_periodic) timers.	221	on true relative time) and absolute (ev_periodic, based on wallclock time)
		222	timers.
220		223
221	AnyEvent always prefers relative timers, if available, matching the	224	AnyEvent always prefers relative timers, if available, matching the
222	AnyEvent API.	225	AnyEvent API.
223		226
224	=head2 SIGNAL WATCHERS	227	=head2 SIGNAL WATCHERS
225		228
226	You can watch for signals using a signal watcher, C<signal> is the signal	229	You can watch for signals using a signal watcher, C<signal> is the signal
227	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	230	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to
228	be invoked whenever a signal occurs.	231	be invoked whenever a signal occurs.
229		232
230	Multiple signals occurances can be clumped together into one callback	233	Multiple signal occurances can be clumped together into one callback
231	invocation, and callback invocation will be synchronous. synchronous means	234	invocation, and callback invocation will be synchronous. synchronous means
232	that it might take a while until the signal gets handled by the process,	235	that it might take a while until the signal gets handled by the process,
233	but it is guarenteed not to interrupt any other callbacks.	236	but it is guarenteed not to interrupt any other callbacks.
234		237
235	The main advantage of using these watchers is that you can share a signal	238	The main advantage of using these watchers is that you can share a signal
…		…
353		356
354	The known classes so far are:	357	The known classes so far are:
355		358
356	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.	359	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
357	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.	360	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
358	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).
359	AnyEvent::Impl::Event based on Event, also second best choice :)	362	AnyEvent::Impl::Event based on Event, second best choice.
360	AnyEvent::Impl::Glib based on Glib, third-best choice.	363	AnyEvent::Impl::Glib based on Glib, third-best choice.
361	AnyEvent::Impl::Tk based on Tk, very bad choice.	364	AnyEvent::Impl::Tk based on Tk, very bad choice.
362	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.
363		379
364	=item AnyEvent::detect	380	=item AnyEvent::detect
365		381
366	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	382	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
367	if necessary. You should only call this function right before you would	383	if necessary. You should only call this function right before you would
…		…
418	no warnings;	434	no warnings;
419	use strict;	435	use strict;
420		436
421	use Carp;	437	use Carp;
422		438
423	our $VERSION = '3.12';	439	our $VERSION = '3.3';
424	our $MODEL;	440	our $MODEL;
425		441
426	our $AUTOLOAD;	442	our $AUTOLOAD;
427	our @ISA;	443	our @ISA;
428		444
…		…
435	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],	451	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
436	[EV:: => AnyEvent::Impl::EV::],	452	[EV:: => AnyEvent::Impl::EV::],
437	[Event:: => AnyEvent::Impl::Event::],	453	[Event:: => AnyEvent::Impl::Event::],
438	[Glib:: => AnyEvent::Impl::Glib::],	454	[Glib:: => AnyEvent::Impl::Glib::],
439	[Tk:: => AnyEvent::Impl::Tk::],	455	[Tk:: => AnyEvent::Impl::Tk::],
		456	[Wx:: => AnyEvent::Impl::POE::],
		457	[Prima:: => AnyEvent::Impl::POE::],
440	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	458	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
		459	# everything below here will not be autoprobed as the pureperl backend should work everywhere
		460	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		461	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		462	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
441	);	463	);
442		464
443	our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY);	465	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);
444		466
445	sub detect() {	467	sub detect() {
446	unless ($MODEL) {	468	unless ($MODEL) {
447	no strict 'refs';	469	no strict 'refs';
448		470
		471	if ($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 $verbose;
		478	}
		479	}
		480
449	# check for already loaded models	481	# check for already loaded models
		482	unless ($MODEL) {
450	for (@REGISTRY, @models) {	483	for (@REGISTRY, @models) {
451	my ($package, $model) = @$_;	484	my ($package, $model) = @$_;
452	if (${"$package\::VERSION"} > 0) {	485	if (${"$package\::VERSION"} > 0) {
453	if (eval "require $model") {	486	if (eval "require $model") {
454	$MODEL = $model;	487	$MODEL = $model;
455	warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1;	488	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
456	last;	489	last;
		490	}
457	}	491	}
458	}	492	}
459	}
460		493
461	unless ($MODEL) {	494	unless ($MODEL) {
462	# try to load a model	495	# try to load a model
463		496
464	for (@REGISTRY, @models) {	497	for (@REGISTRY, @models) {
465	my ($package, $model) = @$_;	498	my ($package, $model) = @$_;
466	if (eval "require $package"	499	if (eval "require $package"
467	and ${"$package\::VERSION"} > 0	500	and ${"$package\::VERSION"} > 0
468	and eval "require $model") {	501	and eval "require $model") {
469	$MODEL = $model;	502	$MODEL = $model;
470	warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1;	503	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
471	last;	504	last;
		505	}
472	}	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.";
473	}	510	}
474
475	$MODEL
476	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.";
477	}	511	}
478		512
479	unshift @ISA, $MODEL;	513	unshift @ISA, $MODEL;
480	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	514	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
481	}	515	}
…		…
637		671
638	=head1 ENVIRONMENT VARIABLES	672	=head1 ENVIRONMENT VARIABLES
639		673
640	The following environment variables are used by this module:	674	The following environment variables are used by this module:
641		675
642	C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, cause AnyEvent to	676	=over 4
643	report to STDERR which event model it chooses.	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
644		708
645	=head1 EXAMPLE PROGRAM	709	=head1 EXAMPLE PROGRAM
646		710
647	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
648	to display a message once per second, and a condition variable to quit the	712	to display a message once per second, and a condition variable to quit the
…		…
796	$quit->broadcast;	860	$quit->broadcast;
797	});	861	});
798		862
799	$quit->wait;	863	$quit->wait;
800		864
		865
		866	=head1 BENCHMARK
		867
		868	To give you an idea of the performance and overheads that AnyEvent adds
		869	over the backends directly, here is a benchmark of various supported event
		870	models natively and with anyevent. The benchmark creates a lot of timers
		871	(with a zero timeout) and io watchers (watching STDOUT, a pty, to become
		872	writable), lets them fire exactly once and destroys them again.
		873
		874	Explanation of the fields:
		875
		876	I<watcher> is the number of event watchers created/destroyed. Sicne
		877	different event models have vastly different performance each backend was
		878	handed a number of watchers so that overall runtime is acceptable and
		879	similar to all backends (and keep them from crashing).
		880
		881	I<bytes> is the number of bytes (as measured by resident set size) used by
		882	each watcher.
		883
		884	I<create> is the time, in microseconds, to create a single watcher.
		885
		886	I<invoke> is the time, in microseconds, used to invoke a simple callback
		887	that simply counts down.
		888
		889	I<destroy> is the time, in microseconds, to destroy a single watcher.
		890
		891	name watcher bytes create invoke destroy comment
		892	EV/EV 400000 244 0.56 0.46 0.31 EV native interface
		893	EV/Any 100000 610 3.52 0.91 0.75
		894	CoroEV/Any 100000 610 3.49 0.92 0.75 coroutines + Coro::Signal
		895	Perl/Any 10000 654 4.64 1.22 0.77 pure perl implementation
		896	Event/Event 10000 523 28.05 21.38 5.22 Event native interface
		897	Event/Any 10000 943 34.43 20.48 1.39
		898	Glib/Any 16000 1357 96.99 12.55 55.51 quadratic behaviour
		899	Tk/Any 2000 1855 27.01 66.61 14.03 SEGV with >> 2000 watchers
		900	POE/Select 2000 6343 94.69 807.65 562.69 POE::Loop::Select
		901	POE/Event 2000 6644 108.15 768.19 14.33 POE::Loop::Event
		902
		903	Discussion: The benchmark does I<not> bench scalability of the
		904	backend. For example a select-based backend (such as the pureperl one) can
		905	never compete with a backend using epoll. In this benchmark, only a single
		906	filehandle is used.
		907
		908	EV is the sole leader regarding speed and memory use, which are both
		909	maximal/minimal. Even when going through AnyEvent, there is only one event
		910	loop that uses less memory (the Event module natively), and no faster
		911	event model.
		912
		913	The pure perl implementation is hit in a few sweet spots (both the
		914	zero timeout and the use of a single fd hit optimisations in the perl
		915	interpreter and the backend itself), but it shows that it adds very little
		916	overhead in itself. Like any select-based backend it's performance becomes
		917	really bad with lots of file descriptors.
		918
		919	The Event module has a relatively high setup and callback invocation cost,
		920	but overall scores on the third place.
		921
		922	Glib has a little higher memory cost, a bit fster callback invocation and
		923	has a similar speed as Event.
		924
		925	The Tk backend works relatively well, the fact that it crashes with
		926	more than 2000 watchers is a big setback, however, as correctness takes
		927	precedence over speed.
		928
		929	POE, regardless of backend (wether it's pure perl select backend or the
		930	Event backend) shows abysmal performance and memory usage: Watchers use
		931	almost 30 times as much memory as EV watchers, and 10 times as much memory
		932	as both Event or EV via AnyEvent.
		933
		934	Summary: using EV through AnyEvent is faster than any other event
		935	loop. The overhead AnyEvent adds can be very small, and you should avoid
		936	POE like the plague if you want performance or reasonable memory usage.
		937
		938
		939	=head1 FORK
		940
		941	Most event libraries are not fork-safe. The ones who are usually are
		942	because they are so inefficient. Only L<EV> is fully fork-aware.
		943
		944	If you have to fork, you must either do so I<before> creating your first
		945	watcher OR you must not use AnyEvent at all in the child.
		946
		947
		948	=head1 SECURITY CONSIDERATIONS
		949
		950	AnyEvent can be forced to load any event model via
		951	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to
		952	execute arbitrary code or directly gain access, it can easily be used to
		953	make the program hang or malfunction in subtle ways, as AnyEvent watchers
		954	will not be active when the program uses a different event model than
		955	specified in the variable.
		956
		957	You can make AnyEvent completely ignore this variable by deleting it
		958	before the first watcher gets created, e.g. with a C<BEGIN> block:
		959
		960	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
		961
		962	use AnyEvent;
		963
		964
801	=head1 SEE ALSO	965	=head1 SEE ALSO
802		966
803	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	967	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,
804	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>.	968	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,
		969	L<Event::Lib>, L<Qt>, L<POE>.
805		970
806	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	971	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,
		972	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,
		973	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,
807	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>,	974	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.
808	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>.
809		975
810	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	976	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.
		977
811		978
812	=head1 AUTHOR	979	=head1 AUTHOR
813		980
814	Marc Lehmann <schmorp@schmorp.de>	981	Marc Lehmann <schmorp@schmorp.de>
815	http://home.schmorp.de/	982	http://home.schmorp.de/

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.54 by root, Tue Apr 22 05:12:19 2008 UTC vs. Revision 1.66 by root, Fri Apr 25 06:58:31 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.54 by root, Tue Apr 22 05:12:19 2008 UTC vs.
Revision 1.66 by root, Fri Apr 25 06:58:31 2008 UTC