[ViewVC] Diff of: cvs/AnyEvent/README

Comparing AnyEvent/README (file contents):
Revision 1.39 by root, Sun Jun 7 16:48:38 2009 UTC vs.
Revision 1.43 by root, Thu Jul 9 08:37:06 2009 UTC

…		…
169		169
170	I/O WATCHERS	170	I/O WATCHERS
171	You can create an I/O watcher by calling the "AnyEvent->io" method with	171	You can create an I/O watcher by calling the "AnyEvent->io" method with
172	the following mandatory key-value pairs as arguments:	172	the following mandatory key-value pairs as arguments:
173		173
174	"fh" is the Perl file handle (not file descriptor) to watch for	174	"fh" is the Perl file handle (or a naked file descriptor) to watch for
175	events (AnyEvent might or might not keep a reference to this file	175	events (AnyEvent might or might not keep a reference to this file
176	handle). Note that only file handles pointing to things for which	176	handle). Note that only file handles pointing to things for which
177	non-blocking operation makes sense are allowed. This includes sockets,	177	non-blocking operation makes sense are allowed. This includes sockets,
178	most character devices, pipes, fifos and so on, but not for example	178	most character devices, pipes, fifos and so on, but not for example
179	files or block devices.	179	files or block devices.
…		…
380		380
381	There is a slight catch to child watchers, however: you usually start	381	There is a slight catch to child watchers, however: you usually start
382	them after the child process was created, and this means the process	382	them after the child process was created, and this means the process
383	could have exited already (and no SIGCHLD will be sent anymore).	383	could have exited already (and no SIGCHLD will be sent anymore).
384		384
385	Not all event models handle this correctly (POE doesn't), but even for	385	Not all event models handle this correctly (neither POE nor IO::Async
		386	do, see their AnyEvent::Impl manpages for details), but even for event
386	event models that do handle this correctly, they usually need to be	387	models that do handle this correctly, they usually need to be loaded
387	loaded before the process exits (i.e. before you fork in the first	388	before the process exits (i.e. before you fork in the first place).
388	place).	389	AnyEvent's pure perl event loop handles all cases correctly regardless
		390	of when you start the watcher.
389		391
390	This means you cannot create a child watcher as the very first thing in	392	This means you cannot create a child watcher as the very first thing in
391	an AnyEvent program, you have to create at least one watcher before	393	an AnyEvent program, you have to create at least one watcher before
392	you "fork" the child (alternatively, you can call "AnyEvent::detect").	394	you "fork" the child (alternatively, you can call "AnyEvent::detect").
393		395
394	Example: fork a process and wait for it	396	Example: fork a process and wait for it
395		397
396	my $done = AnyEvent->condvar;	398	my $done = AnyEvent->condvar;
397		399
398	my $pid = fork or exit 5;	400	my $pid = fork or exit 5;
399		401
400	my $w = AnyEvent->child (	402	my $w = AnyEvent->child (
401	pid => $pid,	403	pid => $pid,
402	cb => sub {	404	cb => sub {
403	my ($pid, $status) = @_;	405	my ($pid, $status) = @_;
404	warn "pid $pid exited with status $status";	406	warn "pid $pid exited with status $status";
405	$done->send;	407	$done->send;
406	},	408	},
407	);	409	);
408		410
409	# do something else, then wait for process exit	411	# do something else, then wait for process exit
410	$done->recv;	412	$done->recv;
411		413
412	IDLE WATCHERS	414	IDLE WATCHERS
413	Sometimes there is a need to do something, but it is not so important to	415	Sometimes there is a need to do something, but it is not so important to
414	do it instantly, but only when there is nothing better to do. This	416	do it instantly, but only when there is nothing better to do. This
…		…
575	This can be used to signal any errors to the condition variable	577	This can be used to signal any errors to the condition variable
576	user/consumer.	578	user/consumer.
577		579
578	$cv->begin ([group callback])	580	$cv->begin ([group callback])
579	$cv->end	581	$cv->end
580	These two methods are EXPERIMENTAL and MIGHT CHANGE.
581
582	These two methods can be used to combine many transactions/events	582	These two methods can be used to combine many transactions/events
583	into one. For example, a function that pings many hosts in parallel	583	into one. For example, a function that pings many hosts in parallel
584	might want to use a condition variable for the whole process.	584	might want to use a condition variable for the whole process.
585		585
586	Every call to "->begin" will increment a counter, and every call to	586	Every call to "->begin" will increment a counter, and every call to
587	"->end" will decrement it. If the counter reaches 0 in "->end", the	587	"->end" will decrement it. If the counter reaches 0 in "->end", the
588	(last) callback passed to "begin" will be executed. That callback is	588	(last) callback passed to "begin" will be executed. That callback is
589	supposed to call "->send", but that is not required. If no	589	supposed to call "->send", but that is not required. If no
590	callback was set, "send" will be called without any arguments.	590	callback was set, "send" will be called without any arguments.
591		591
592	Let's clarify this with the ping example:	592	You can think of "$cv->send" giving you an OR condition (one call
		593	sends), while "$cv->begin" and "$cv->end" giving you an AND
		594	condition (all "begin" calls must be "end"'ed before the condvar
		595	sends).
		596
		597	Let's start with a simple example: you have two I/O watchers (for
		598	example, STDOUT and STDERR for a program), and you want to wait for
		599	both streams to close before activating a condvar:
		600
		601	my $cv = AnyEvent->condvar;
		602
		603	$cv->begin; # first watcher
		604	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		605	defined sysread $fh1, my $buf, 4096
		606	or $cv->end;
		607	});
		608
		609	$cv->begin; # second watcher
		610	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		611	defined sysread $fh2, my $buf, 4096
		612	or $cv->end;
		613	});
		614
		615	$cv->recv;
		616
		617	This works because for every event source (EOF on file handle),
		618	there is one call to "begin", so the condvar waits for all calls to
		619	"end" before sending.
		620
		621	The ping example mentioned above is slightly more complicated, as
		622	the there are results to be passwd back, and the number of tasks
		623	that are begung can potentially be zero:
593		624
594	my $cv = AnyEvent->condvar;	625	my $cv = AnyEvent->condvar;
595		626
596	my %result;	627	my %result;
597	$cv->begin (sub { $cv->send (\%result) });	628	$cv->begin (sub { $cv->send (\%result) });
…		…
617	the loop, which serves two important purposes: first, it sets the	648	the loop, which serves two important purposes: first, it sets the
618	callback to be called once the counter reaches 0, and second, it	649	callback to be called once the counter reaches 0, and second, it
619	ensures that "send" is called even when "no" hosts are being pinged	650	ensures that "send" is called even when "no" hosts are being pinged
620	(the loop doesn't execute once).	651	(the loop doesn't execute once).
621		652
622	This is the general pattern when you "fan out" into multiple	653	This is the general pattern when you "fan out" into multiple (but
623	subrequests: use an outer "begin"/"end" pair to set the callback and	654	potentially none) subrequests: use an outer "begin"/"end" pair to
624	ensure "end" is called at least once, and then, for each subrequest	655	set the callback and ensure "end" is called at least once, and then,
625	you start, call "begin" and for each subrequest you finish, call	656	for each subrequest you start, call "begin" and for each subrequest
626	"end".	657	you finish, call "end".
627		658
628	METHODS FOR CONSUMERS	659	METHODS FOR CONSUMERS
629	These methods should only be used by the consuming side, i.e. the code	660	These methods should only be used by the consuming side, i.e. the code
630	awaits the condition.	661	awaits the condition.
631		662
…		…
678	The callback will be called when the condition becomes "true", i.e.	709	The callback will be called when the condition becomes "true", i.e.
679	when "send" or "croak" are called, with the only argument being the	710	when "send" or "croak" are called, with the only argument being the
680	condition variable itself. Calling "recv" inside the callback or at	711	condition variable itself. Calling "recv" inside the callback or at
681	any later time is guaranteed not to block.	712	any later time is guaranteed not to block.
682		713
		714	SUPPORTED EVENT LOOPS/BACKENDS
		715	The available backend classes are (every class has its own manpage):
		716
		717	Backends that are autoprobed when no other event loop can be found.
		718	EV is the preferred backend when no other event loop seems to be in
		719	use. If EV is not installed, then AnyEvent will try Event, and,
		720	failing that, will fall back to its own pure-perl implementation,
		721	which is available everywhere as it comes with AnyEvent itself.
		722
		723	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		724	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		725	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		726
		727	Backends that are transparently being picked up when they are used.
		728	These will be used when they are currently loaded when the first
		729	watcher is created, in which case it is assumed that the application
		730	is using them. This means that AnyEvent will automatically pick the
		731	right backend when the main program loads an event module before
		732	anything starts to create watchers. Nothing special needs to be done
		733	by the main program.
		734
		735	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		736	AnyEvent::Impl::Tk based on Tk, very broken.
		737	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		738	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		739
		740	Backends with special needs.
		741	Qt requires the Qt::Application to be instantiated first, but will
		742	otherwise be picked up automatically. As long as the main program
		743	instantiates the application before any AnyEvent watchers are
		744	created, everything should just work.
		745
		746	AnyEvent::Impl::Qt based on Qt.
		747
		748	Support for IO::Async can only be partial, as it is too broken and
		749	architecturally limited to even support the AnyEvent API. It also is
		750	the only event loop that needs the loop to be set explicitly, so it
		751	can only be used by a main program knowing about AnyEvent. See
		752	AnyEvent::Impl::Async for the gory details.
		753
		754	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		755
		756	Event loops that are indirectly supported via other backends.
		757	Some event loops can be supported via other modules:
		758
		759	There is no direct support for WxWidgets (Wx) or Prima.
		760
		761	WxWidgets has no support for watching file handles. However, you can
		762	use WxWidgets through the POE adaptor, as POE has a Wx backend that
		763	simply polls 20 times per second, which was considered to be too
		764	horrible to even consider for AnyEvent.
		765
		766	Prima is not supported as nobody seems to be using it, but it has a
		767	POE backend, so it can be supported through POE.
		768
		769	AnyEvent knows about both Prima and Wx, however, and will try to
		770	load POE when detecting them, in the hope that POE will pick them
		771	up, in which case everything will be automatic.
		772
683	GLOBAL VARIABLES AND FUNCTIONS	773	GLOBAL VARIABLES AND FUNCTIONS
		774	These are not normally required to use AnyEvent, but can be useful to
		775	write AnyEvent extension modules.
		776
684	$AnyEvent::MODEL	777	$AnyEvent::MODEL
685	Contains "undef" until the first watcher is being created. Then it	778	Contains "undef" until the first watcher is being created, before
		779	the backend has been autodetected.
		780
686	contains the event model that is being used, which is the name of	781	Afterwards it contains the event model that is being used, which is
687	the Perl class implementing the model. This class is usually one of	782	the name of the Perl class implementing the model. This class is
688	the "AnyEvent::Impl:xxx" modules, but can be any other class in the	783	usually one of the "AnyEvent::Impl:xxx" modules, but can be any
689	case AnyEvent has been extended at runtime (e.g. in rxvt-unicode).	784	other class in the case AnyEvent has been extended at runtime (e.g.
690		785	in rxvt-unicode it will be "urxvt::anyevent").
691	The known classes so far are:
692
693	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
694	AnyEvent::Impl::Event based on Event, second best choice.
695	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
696	AnyEvent::Impl::Glib based on Glib, third-best choice.
697	AnyEvent::Impl::Tk based on Tk, very bad choice.
698	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
699	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
700	AnyEvent::Impl::POE based on POE, not generic enough for full support.
701
702	There is no support for WxWidgets, as WxWidgets has no support for
703	watching file handles. However, you can use WxWidgets through the
704	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
705	second, which was considered to be too horrible to even consider for
706	AnyEvent. Likewise, other POE backends can be used by AnyEvent by
707	using it's adaptor.
708
709	AnyEvent knows about Prima and Wx and will try to use POE when
710	autodetecting them.
711		786
712	AnyEvent::detect	787	AnyEvent::detect
713	Returns $AnyEvent::MODEL, forcing autodetection of the event model	788	Returns $AnyEvent::MODEL, forcing autodetection of the event model
714	if necessary. You should only call this function right before you	789	if necessary. You should only call this function right before you
715	would have created an AnyEvent watcher anyway, that is, as late as	790	would have created an AnyEvent watcher anyway, that is, as late as
716	possible at runtime.	791	possible at runtime, and not e.g. while initialising of your module.
		792
		793	If you need to do some initialisation before AnyEvent watchers are
		794	created, use "post_detect".
717		795
718	$guard = AnyEvent::post_detect { BLOCK }	796	$guard = AnyEvent::post_detect { BLOCK }
719	Arranges for the code block to be executed as soon as the event	797	Arranges for the code block to be executed as soon as the event
720	model is autodetected (or immediately if this has already happened).	798	model is autodetected (or immediately if this has already happened).
		799
		800	The block will be executed after the actual backend has been
		801	detected ($AnyEvent::MODEL is set), but before any watchers have
		802	been created, so it is possible to e.g. patch @AnyEvent::ISA or do
		803	other initialisations - see the sources of AnyEvent::Strict or
		804	AnyEvent::AIO to see how this is used.
		805
		806	The most common usage is to create some global watchers, without
		807	forcing event module detection too early, for example, AnyEvent::AIO
		808	creates and installs the global IO::AIO watcher in a "post_detect"
		809	block to avoid autodetecting the event module at load time.
721		810
722	If called in scalar or list context, then it creates and returns an	811	If called in scalar or list context, then it creates and returns an
723	object that automatically removes the callback again when it is	812	object that automatically removes the callback again when it is
724	destroyed. See Coro::BDB for a case where this is useful.	813	destroyed. See Coro::BDB for a case where this is useful.
725		814
…		…
727	If there are any code references in this array (you can "push" to it	816	If there are any code references in this array (you can "push" to it
728	before or after loading AnyEvent), then they will called directly	817	before or after loading AnyEvent), then they will called directly
729	after the event loop has been chosen.	818	after the event loop has been chosen.
730		819
731	You should check $AnyEvent::MODEL before adding to this array,	820	You should check $AnyEvent::MODEL before adding to this array,
732	though: if it contains a true value then the event loop has already	821	though: if it is defined then the event loop has already been
733	been detected, and the array will be ignored.	822	detected, and the array will be ignored.
734		823
735	Best use "AnyEvent::post_detect { BLOCK }" instead.	824	Best use "AnyEvent::post_detect { BLOCK }" when your application
		825	allows it,as it takes care of these details.
		826
		827	This variable is mainly useful for modules that can do something
		828	useful when AnyEvent is used and thus want to know when it is
		829	initialised, but do not need to even load it by default. This array
		830	provides the means to hook into AnyEvent passively, without loading
		831	it.
736		832
737	WHAT TO DO IN A MODULE	833	WHAT TO DO IN A MODULE
738	As a module author, you should "use AnyEvent" and call AnyEvent methods	834	As a module author, you should "use AnyEvent" and call AnyEvent methods
739	freely, but you should not load a specific event module or rely on it.	835	freely, but you should not load a specific event module or rely on it.
740		836
…		…
791	variable somewhere, waiting for it, and sending it when the program	887	variable somewhere, waiting for it, and sending it when the program
792	should exit cleanly.	888	should exit cleanly.
793		889
794	OTHER MODULES	890	OTHER MODULES
795	The following is a non-exhaustive list of additional modules that use	891	The following is a non-exhaustive list of additional modules that use
796	AnyEvent and can therefore be mixed easily with other AnyEvent modules	892	AnyEvent as a client and can therefore be mixed easily with other
797	in the same program. Some of the modules come with AnyEvent, some are	893	AnyEvent modules and other event loops in the same program. Some of the
798	available via CPAN.	894	modules come with AnyEvent, most are available via CPAN.
799		895
800	AnyEvent::Util	896	AnyEvent::Util
801	Contains various utility functions that replace often-used but	897	Contains various utility functions that replace often-used but
802	blocking functions such as "inet_aton" by event-/callback-based	898	blocking functions such as "inet_aton" by event-/callback-based
803	versions.	899	versions.
…		…
809	more.	905	more.
810		906
811	AnyEvent::Handle	907	AnyEvent::Handle
812	Provide read and write buffers, manages watchers for reads and	908	Provide read and write buffers, manages watchers for reads and
813	writes, supports raw and formatted I/O, I/O queued and fully	909	writes, supports raw and formatted I/O, I/O queued and fully
814	transparent and non-blocking SSL/TLS.	910	transparent and non-blocking SSL/TLS (via AnyEvent::TLS.
815		911
816	AnyEvent::DNS	912	AnyEvent::DNS
817	Provides rich asynchronous DNS resolver capabilities.	913	Provides rich asynchronous DNS resolver capabilities.
818		914
819	AnyEvent::HTTP	915	AnyEvent::HTTP
…		…
840		936
841	AnyEvent::GPSD	937	AnyEvent::GPSD
842	A non-blocking interface to gpsd, a daemon delivering GPS	938	A non-blocking interface to gpsd, a daemon delivering GPS
843	information.	939	information.
844		940
		941	AnyEvent::IRC
		942	AnyEvent based IRC client module family (replacing the older
		943	Net::IRC3).
		944
		945	AnyEvent::XMPP
		946	AnyEvent based XMPP (Jabber protocol) module family (replacing the
		947	older Net::XMPP2>.
		948
845	AnyEvent::IGS	949	AnyEvent::IGS
846	A non-blocking interface to the Internet Go Server protocol (used by	950	A non-blocking interface to the Internet Go Server protocol (used by
847	App::IGS).	951	App::IGS).
848		952
849	AnyEvent::IRC
850	AnyEvent based IRC client module family (replacing the older
851	Net::IRC3).
852
853	Net::XMPP2
854	AnyEvent based XMPP (Jabber protocol) module family.
855
856	Net::FCP	953	Net::FCP
857	AnyEvent-based implementation of the Freenet Client Protocol,	954	AnyEvent-based implementation of the Freenet Client Protocol,
858	birthplace of AnyEvent.	955	birthplace of AnyEvent.
859		956
860	Event::ExecFlow	957	Event::ExecFlow
861	High level API for event-based execution flow control.	958	High level API for event-based execution flow control.
862		959
863	Coro	960	Coro
864	Has special support for AnyEvent via Coro::AnyEvent.	961	Has special support for AnyEvent via Coro::AnyEvent.
865
866	IO::Lambda
867	The lambda approach to I/O - don't ask, look there. Can use
868	AnyEvent.
869		962
870	ERROR AND EXCEPTION HANDLING	963	ERROR AND EXCEPTION HANDLING
871	In general, AnyEvent does not do any error handling - it relies on the	964	In general, AnyEvent does not do any error handling - it relies on the
872	caller to do that if required. The AnyEvent::Strict module (see also the	965	caller to do that if required. The AnyEvent::Strict module (see also the
873	"PERL_ANYEVENT_STRICT" environment variable, below) provides strict	966	"PERL_ANYEVENT_STRICT" environment variable, below) provides strict
…		…
883	"condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()",	976	"condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()",
884	Glib uses "install_exception_handler" and so on.	977	Glib uses "install_exception_handler" and so on.
885		978
886	ENVIRONMENT VARIABLES	979	ENVIRONMENT VARIABLES
887	The following environment variables are used by this module or its	980	The following environment variables are used by this module or its
888	submodules:	981	submodules.
		982
		983	Note that AnyEvent will remove all environment variables starting with
		984	"PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is
		985	enabled.
889		986
890	"PERL_ANYEVENT_VERBOSE"	987	"PERL_ANYEVENT_VERBOSE"
891	By default, AnyEvent will be completely silent except in fatal	988	By default, AnyEvent will be completely silent except in fatal
892	conditions. You can set this environment variable to make AnyEvent	989	conditions. You can set this environment variable to make AnyEvent
893	more talkative.	990	more talkative.
…		…
902	"PERL_ANYEVENT_STRICT"	999	"PERL_ANYEVENT_STRICT"
903	AnyEvent does not do much argument checking by default, as thorough	1000	AnyEvent does not do much argument checking by default, as thorough
904	argument checking is very costly. Setting this variable to a true	1001	argument checking is very costly. Setting this variable to a true
905	value will cause AnyEvent to load "AnyEvent::Strict" and then to	1002	value will cause AnyEvent to load "AnyEvent::Strict" and then to
906	thoroughly check the arguments passed to most method calls. If it	1003	thoroughly check the arguments passed to most method calls. If it
907	finds any problems it will croak.	1004	finds any problems, it will croak.
908		1005
909	In other words, enables "strict" mode.	1006	In other words, enables "strict" mode.
910		1007
911	Unlike "use strict", it is definitely recommended ot keep it off in	1008	Unlike "use strict", it is definitely recommended to keep it off in
912	production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment	1009	production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment
913	while developing programs can be very useful, however.	1010	while developing programs can be very useful, however.
914		1011
915	"PERL_ANYEVENT_MODEL"	1012	"PERL_ANYEVENT_MODEL"
916	This can be used to specify the event model to be used by AnyEvent,	1013	This can be used to specify the event model to be used by AnyEvent,
…		…
959	EDNS0 in its DNS requests.	1056	EDNS0 in its DNS requests.
960		1057
961	"PERL_ANYEVENT_MAX_FORKS"	1058	"PERL_ANYEVENT_MAX_FORKS"
962	The maximum number of child processes that	1059	The maximum number of child processes that
963	"AnyEvent::Util::fork_call" will create in parallel.	1060	"AnyEvent::Util::fork_call" will create in parallel.
		1061
		1062	"PERL_ANYEVENT_MAX_OUTSTANDING_DNS"
		1063	The default value for the "max_outstanding" parameter for the
		1064	default DNS resolver - this is the maximum number of parallel DNS
		1065	requests that are sent to the DNS server.
		1066
		1067	"PERL_ANYEVENT_RESOLV_CONF"
		1068	The file to use instead of /etc/resolv.conf (or OS-specific
		1069	configuration) in the default resolver. When set to the empty
		1070	string, no default config will be used.
		1071
		1072	"PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH".
		1073	When neither "ca_file" nor "ca_path" was specified during
		1074	AnyEvent::TLS context creation, and either of these environment
		1075	variables exist, they will be used to specify CA certificate
		1076	locations instead of a system-dependent default.
964		1077
965	SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1078	SUPPLYING YOUR OWN EVENT MODEL INTERFACE
966	This is an advanced topic that you do not normally need to use AnyEvent	1079	This is an advanced topic that you do not normally need to use AnyEvent
967	in a module. This section is only of use to event loop authors who want	1080	in a module. This section is only of use to event loop authors who want
968	to provide AnyEvent compatibility.	1081	to provide AnyEvent compatibility.
…		…
1204	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	1317	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1205	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	1318	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1206	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	1319	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1207	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	1320	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1208	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	1321	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1322	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1323	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1209	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	1324	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1210	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	1325	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1211	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	1326	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1212	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	1327	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1213		1328
…		…
1242	few of them active), of course, but this was not subject of this	1357	few of them active), of course, but this was not subject of this
1243	benchmark.	1358	benchmark.
1244		1359
1245	The "Event" module has a relatively high setup and callback invocation	1360	The "Event" module has a relatively high setup and callback invocation
1246	cost, but overall scores in on the third place.	1361	cost, but overall scores in on the third place.
		1362
		1363	"IO::Async" performs admirably well, about on par with "Event", even
		1364	when using its pure perl backend.
1247		1365
1248	"Glib"'s memory usage is quite a bit higher, but it features a faster	1366	"Glib"'s memory usage is quite a bit higher, but it features a faster
1249	callback invocation and overall ends up in the same class as "Event".	1367	callback invocation and overall ends up in the same class as "Event".
1250	However, Glib scales extremely badly, doubling the number of watchers	1368	However, Glib scales extremely badly, doubling the number of watchers
1251	increases the processing time by more than a factor of four, making it	1369	increases the processing time by more than a factor of four, making it
…		…
1322	single "request", that is, reading the token from the pipe and	1440	single "request", that is, reading the token from the pipe and
1323	forwarding it to another server. This includes deleting the old timeout	1441	forwarding it to another server. This includes deleting the old timeout
1324	and creating a new one that moves the timeout into the future.	1442	and creating a new one that moves the timeout into the future.
1325		1443
1326	Results	1444	Results
1327	name sockets create request	1445	name sockets create request
1328	EV 20000 69.01 11.16	1446	EV 20000 69.01 11.16
1329	Perl 20000 73.32 35.87	1447	Perl 20000 73.32 35.87
		1448	IOAsync 20000 157.00 98.14 epoll
		1449	IOAsync 20000 159.31 616.06 poll
1330	Event 20000 212.62 257.32	1450	Event 20000 212.62 257.32
1331	Glib 20000 651.16 1896.30	1451	Glib 20000 651.16 1896.30
1332	POE 20000 349.67 12317.24 uses POE::Loop::Event	1452	POE 20000 349.67 12317.24 uses POE::Loop::Event
1333		1453
1334	Discussion	1454	Discussion
1335	This benchmark does measure scalability and overall performance of the	1455	This benchmark does measure scalability and overall performance of the
1336	particular event loop.	1456	particular event loop.
1337		1457
1338	EV is again fastest. Since it is using epoll on my system, the setup	1458	EV is again fastest. Since it is using epoll on my system, the setup
1339	time is relatively high, though.	1459	time is relatively high, though.
1340		1460
1341	Perl surprisingly comes second. It is much faster than the C-based event	1461	Perl surprisingly comes second. It is much faster than the C-based event
1342	loops Event and Glib.	1462	loops Event and Glib.
		1463
		1464	IO::Async performs very well when using its epoll backend, and still
		1465	quite good compared to Glib when using its pure perl backend.
1343		1466
1344	Event suffers from high setup time as well (look at its code and you	1467	Event suffers from high setup time as well (look at its code and you
1345	will understand why). Callback invocation also has a high overhead	1468	will understand why). Callback invocation also has a high overhead
1346	compared to the "$_->() for .."-style loop that the Perl event loop	1469	compared to the "$_->() for .."-style loop that the Perl event loop
1347	uses. Event uses select or poll in basically all documented	1470	uses. Event uses select or poll in basically all documented
…		…
1398		1521
1399	Summary	1522	Summary
1400	* C-based event loops perform very well with small number of watchers,	1523	* C-based event loops perform very well with small number of watchers,
1401	as the management overhead dominates.	1524	as the management overhead dominates.
1402		1525
		1526	THE IO::Lambda BENCHMARK
		1527	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1528	could be misinterpreted to make AnyEvent look bad. In fact, the
		1529	benchmark simply compares IO::Lambda with POE, and IO::Lambda looks
		1530	better (which shouldn't come as a surprise to anybody). As such, the
		1531	benchmark is fine, and mostly shows that the AnyEvent backend from
		1532	IO::Lambda isn't very optimal. But how would AnyEvent compare when used
		1533	without the extra baggage? To explore this, I wrote the equivalent
		1534	benchmark for AnyEvent.
		1535
		1536	The benchmark itself creates an echo-server, and then, for 500 times,
		1537	connects to the echo server, sends a line, waits for the reply, and then
		1538	creates the next connection. This is a rather bad benchmark, as it
		1539	doesn't test the efficiency of the framework or much non-blocking I/O,
		1540	but it is a benchmark nevertheless.
		1541
		1542	name runtime
		1543	Lambda/select 0.330 sec
		1544	+ optimized 0.122 sec
		1545	Lambda/AnyEvent 0.327 sec
		1546	+ optimized 0.138 sec
		1547	Raw sockets/select 0.077 sec
		1548	POE/select, components 0.662 sec
		1549	POE/select, raw sockets 0.226 sec
		1550	POE/select, optimized 0.404 sec
		1551
		1552	AnyEvent/select/nb 0.085 sec
		1553	AnyEvent/EV/nb 0.068 sec
		1554	+state machine 0.134 sec
		1555
		1556	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		1557	benchmarks actually make blocking connects and use 100% blocking I/O,
		1558	defeating the purpose of an event-based solution. All of the newly
		1559	written AnyEvent benchmarks use 100% non-blocking connects (using
		1560	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		1561	resolver), so AnyEvent is at a disadvantage here, as non-blocking
		1562	connects generally require a lot more bookkeeping and event handling
		1563	than blocking connects (which involve a single syscall only).
		1564
		1565	The last AnyEvent benchmark additionally uses AnyEvent::Handle, which
		1566	offers similar expressive power as POE and IO::Lambda, using
		1567	conventional Perl syntax. This means that both the echo server and the
		1568	client are 100% non-blocking, further placing it at a disadvantage.
		1569
		1570	As you can see, the AnyEvent + EV combination even beats the
		1571	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		1572	backend easily beats IO::Lambda and POE.
		1573
		1574	And even the 100% non-blocking version written using the high-level (and
		1575	slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda by a
		1576	large margin, even though it does all of DNS, tcp-connect and socket I/O
		1577	in a non-blocking way.
		1578
		1579	The two AnyEvent benchmarks programs can be found as eg/ae0.pl and
		1580	eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are
		1581	part of the IO::lambda distribution and were used without any changes.
		1582
1403	SIGNALS	1583	SIGNALS
1404	AnyEvent currently installs handlers for these signals:	1584	AnyEvent currently installs handlers for these signals:
1405		1585
1406	SIGCHLD	1586	SIGCHLD
1407	A handler for "SIGCHLD" is installed by AnyEvent's child watcher	1587	A handler for "SIGCHLD" is installed by AnyEvent's child watcher
1408	emulation for event loops that do not support them natively. Also,	1588	emulation for event loops that do not support them natively. Also,
1409	some event loops install a similar handler.	1589	some event loops install a similar handler.
		1590
		1591	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent
		1592	will reset it to default, to avoid losing child exit statuses.
1410		1593
1411	SIGPIPE	1594	SIGPIPE
1412	A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is	1595	A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is
1413	"undef" when AnyEvent gets loaded.	1596	"undef" when AnyEvent gets loaded.
1414		1597
…		…
1442		1625
1443	You can make AnyEvent completely ignore this variable by deleting it	1626	You can make AnyEvent completely ignore this variable by deleting it
1444	before the first watcher gets created, e.g. with a "BEGIN" block:	1627	before the first watcher gets created, e.g. with a "BEGIN" block:
1445		1628
1446	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1629	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1447		1630
1448	use AnyEvent;	1631	use AnyEvent;
1449		1632
1450	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	1633	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1451	be used to probe what backend is used and gain other information (which	1634	be used to probe what backend is used and gain other information (which
1452	is probably even less useful to an attacker than PERL_ANYEVENT_MODEL),	1635	is probably even less useful to an attacker than PERL_ANYEVENT_MODEL),
1453	and $ENV{PERL_ANYEGENT_STRICT}.	1636	and $ENV{PERL_ANYEVENT_STRICT}.
		1637
		1638	Note that AnyEvent will remove all environment variables starting with
		1639	"PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is
		1640	enabled.
1454		1641
1455	BUGS	1642	BUGS
1456	Perl 5.8 has numerous memleaks that sometimes hit this module and are	1643	Perl 5.8 has numerous memleaks that sometimes hit this module and are
1457	hard to work around. If you suffer from memleaks, first upgrade to Perl	1644	hard to work around. If you suffer from memleaks, first upgrade to Perl
1458	5.10 and check wether the leaks still show up. (Perl 5.10.0 has other	1645	5.10 and check wether the leaks still show up. (Perl 5.10.0 has other
…		…
1465	Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,	1652	Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,
1466	Event::Lib, Qt, POE.	1653	Event::Lib, Qt, POE.
1467		1654
1468	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,	1655	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,
1469	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,	1656	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,
1470	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE.	1657	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,
		1658	AnyEvent::Impl::IOAsync.
1471		1659
1472	Non-blocking file handles, sockets, TCP clients and servers:	1660	Non-blocking file handles, sockets, TCP clients and servers:
1473	AnyEvent::Handle, AnyEvent::Socket.	1661	AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.
1474		1662
1475	Asynchronous DNS: AnyEvent::DNS.	1663	Asynchronous DNS: AnyEvent::DNS.
1476		1664
1477	Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event,	1665	Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event,
1478		1666
1479	Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS.	1667	Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP,
		1668	AnyEvent::HTTP.
1480		1669
1481	AUTHOR	1670	AUTHOR
1482	Marc Lehmann <schmorp@schmorp.de>	1671	Marc Lehmann <schmorp@schmorp.de>
1483	http://home.schmorp.de/	1672	http://home.schmorp.de/
1484		1673

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Comparing AnyEvent/README (file contents): Revision 1.39 by root, Sun Jun 7 16:48:38 2009 UTC vs. Revision 1.43 by root, Thu Jul 9 08:37:06 2009 UTC

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Revision 1.39 by root, Sun Jun 7 16:48:38 2009 UTC vs.
Revision 1.43 by root, Thu Jul 9 08:37:06 2009 UTC