[ViewVC] Diff of: cvs/AnyEvent-MP/MP.pm

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.81 by root, Mon Sep 7 18:33:44 2009 UTC vs.
Revision 1.114 by root, Thu Apr 22 16:06:19 2010 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent::MP - multi-processing/message-passing framework	3	AnyEvent::MP - erlang-style multi-processing/message-passing framework
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
30	rcv $port, pong => sub { warn "pong received\n" };	30	rcv $port, pong => sub { warn "pong received\n" };
31		31
32	# create a port on another node	32	# create a port on another node
33	my $port = spawn $node, $initfunc, @initdata;	33	my $port = spawn $node, $initfunc, @initdata;
34		34
		35	# destroy a prot again
		36	kil $port; # "normal" kill
		37	kil $port, my_error => "everything is broken"; # error kill
		38
35	# monitoring	39	# monitoring
36	mon $port, $cb->(@msg) # callback is invoked on death	40	mon $localport, $cb->(@msg) # callback is invoked on death
37	mon $port, $otherport # kill otherport on abnormal death	41	mon $localport, $otherport # kill otherport on abnormal death
38	mon $port, $otherport, @msg # send message on death	42	mon $localport, $otherport, @msg # send message on death
		43
		44	# temporarily execute code in port context
		45	peval $port, sub { die "kill the port!" };
		46
		47	# execute callbacks in $SELF port context
		48	my $timer = AE::timer 1, 0, psub {
		49	die "kill the port, delayed";
		50	};
39		51
40	=head1 CURRENT STATUS	52	=head1 CURRENT STATUS
41		53
42	bin/aemp - stable.	54	bin/aemp - stable.
43	AnyEvent::MP - stable API, should work.	55	AnyEvent::MP - stable API, should work.
44	AnyEvent::MP::Intro - explains most concepts.	56	AnyEvent::MP::Intro - explains most concepts.
45	AnyEvent::MP::Kernel - mostly stable.	57	AnyEvent::MP::Kernel - mostly stable API.
46	AnyEvent::MP::Global - stable but incomplete, protocol not yet final.	58	AnyEvent::MP::Global - stable API.
47
48	stay tuned.
49		59
50	=head1 DESCRIPTION	60	=head1 DESCRIPTION
51		61
52	This module (-family) implements a simple message passing framework.	62	This module (-family) implements a simple message passing framework.
53		63
…		…
83		93
84	Nodes are either public (have one or more listening ports) or private	94	Nodes are either public (have one or more listening ports) or private
85	(no listening ports). Private nodes cannot talk to other private nodes	95	(no listening ports). Private nodes cannot talk to other private nodes
86	currently.	96	currently.
87		97
88	=item node ID - C<[a-za-Z0-9_\-.:]+>	98	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
89		99
90	A node ID is a string that uniquely identifies the node within a	100	A node ID is a string that uniquely identifies the node within a
91	network. Depending on the configuration used, node IDs can look like a	101	network. Depending on the configuration used, node IDs can look like a
92	hostname, a hostname and a port, or a random string. AnyEvent::MP itself	102	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
93	doesn't interpret node IDs in any way.	103	doesn't interpret node IDs in any way.
…		…
97	Nodes can only talk to each other by creating some kind of connection to	107	Nodes can only talk to each other by creating some kind of connection to
98	each other. To do this, nodes should listen on one or more local transport	108	each other. To do this, nodes should listen on one or more local transport
99	endpoints - binds. Currently, only standard C<ip:port> specifications can	109	endpoints - binds. Currently, only standard C<ip:port> specifications can
100	be used, which specify TCP ports to listen on.	110	be used, which specify TCP ports to listen on.
101		111
102	=item seeds - C<host:port>	112	=item seed nodes
103		113
104	When a node starts, it knows nothing about the network. To teach the node	114	When a node starts, it knows nothing about the network. To teach the node
105	about the network it first has to contact some other node within the	115	about the network it first has to contact some other node within the
106	network. This node is called a seed.	116	network. This node is called a seed.
107		117
108	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	118	Apart from the fact that other nodes know them as seed nodes and they have
		119	to have fixed listening addresses, seed nodes are perfectly normal nodes -
		120	any node can function as a seed node for others.
		121
		122	In addition to discovering the network, seed nodes are also used to
		123	maintain the network and to connect nodes that otherwise would have
		124	trouble connecting. They form the backbone of an AnyEvent::MP network.
		125
109	are expected to be long-running, and at least one of those should always	126	Seed nodes are expected to be long-running, and at least one seed node
110	be available. When nodes run out of connections (e.g. due to a network	127	should always be available. They should also be relatively responsive - a
111	error), they try to re-establish connections to some seednodes again to	128	seed node that blocks for long periods will slow down everybody else.
112	join the network.
113		129
114	Apart from being sued for seeding, seednodes are not special in any way -	130	=item seeds - C<host:port>
115	every public node can be a seednode.	131
		132	Seeds are transport endpoint(s) (usually a hostname/IP address and a
		133	TCP port) of nodes that should be used as seed nodes.
		134
		135	The nodes listening on those endpoints are expected to be long-running,
		136	and at least one of those should always be available. When nodes run out
		137	of connections (e.g. due to a network error), they try to re-establish
		138	connections to some seednodes again to join the network.
116		139
117	=back	140	=back
118		141
119	=head1 VARIABLES/FUNCTIONS	142	=head1 VARIABLES/FUNCTIONS
120		143
…		…
132		155
133	use AE ();	156	use AE ();
134		157
135	use base "Exporter";	158	use base "Exporter";
136		159
137	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	160	our $VERSION = 1.28;
138		161
139	our @EXPORT = qw(	162	our @EXPORT = qw(
140	NODE $NODE *SELF node_of after	163	NODE $NODE *SELF node_of after
141	configure	164	configure
142	snd rcv mon mon_guard kil reg psub spawn	165	snd rcv mon mon_guard kil psub peval spawn cal
143	port	166	port
144	);	167	);
145		168
146	our $SELF;	169	our $SELF;
147		170
…		…
167		190
168	Before a node can talk to other nodes on the network (i.e. enter	191	Before a node can talk to other nodes on the network (i.e. enter
169	"distributed mode") it has to configure itself - the minimum a node needs	192	"distributed mode") it has to configure itself - the minimum a node needs
170	to know is its own name, and optionally it should know the addresses of	193	to know is its own name, and optionally it should know the addresses of
171	some other nodes in the network to discover other nodes.	194	some other nodes in the network to discover other nodes.
		195
		196	The key/value pairs are basically the same ones as documented for the
		197	F<aemp> command line utility (sans the set/del prefix).
172		198
173	This function configures a node - it must be called exactly once (or	199	This function configures a node - it must be called exactly once (or
174	never) before calling other AnyEvent::MP functions.	200	never) before calling other AnyEvent::MP functions.
175		201
176	=over 4	202	=over 4
…		…
216	L<AnyEvent::MP::Global> module, which will then use it to keep	242	L<AnyEvent::MP::Global> module, which will then use it to keep
217	connectivity with at least one node at any point in time.	243	connectivity with at least one node at any point in time.
218		244
219	=back	245	=back
220		246
221	Example: become a distributed node using the locla node name as profile.	247	Example: become a distributed node using the local node name as profile.
222	This should be the most common form of invocation for "daemon"-type nodes.	248	This should be the most common form of invocation for "daemon"-type nodes.
223		249
224	configure	250	configure
225		251
226	Example: become an anonymous node. This form is often used for commandline	252	Example: become an anonymous node. This form is often used for commandline
…		…
360	msg1 => sub { ... },	386	msg1 => sub { ... },
361	...	387	...
362	;	388	;
363		389
364	Example: temporarily register a rcv callback for a tag matching some port	390	Example: temporarily register a rcv callback for a tag matching some port
365	(e.g. for a rpc reply) and unregister it after a message was received.	391	(e.g. for an rpc reply) and unregister it after a message was received.
366		392
367	rcv $port, $otherport => sub {	393	rcv $port, $otherport => sub {
368	my @reply = @_;	394	my @reply = @_;
369		395
370	rcv $SELF, $otherport;	396	rcv $SELF, $otherport;
…		…
383	if (ref $_[0]) {	409	if (ref $_[0]) {
384	if (my $self = $PORT_DATA{$portid}) {	410	if (my $self = $PORT_DATA{$portid}) {
385	"AnyEvent::MP::Port" eq ref $self	411	"AnyEvent::MP::Port" eq ref $self
386	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	412	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
387		413
388	$self->[2] = shift;	414	$self->[0] = shift;
389	} else {	415	} else {
390	my $cb = shift;	416	my $cb = shift;
391	$PORT{$portid} = sub {	417	$PORT{$portid} = sub {
392	local $SELF = $port;	418	local $SELF = $port;
393	eval { &$cb }; _self_die if $@;	419	eval { &$cb }; _self_die if $@;
394	};	420	};
395	}	421	}
396	} elsif (defined $_[0]) {	422	} elsif (defined $_[0]) {
397	my $self = $PORT_DATA{$portid} \|\|= do {	423	my $self = $PORT_DATA{$portid} \|\|= do {
398	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	424	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
399		425
400	$PORT{$portid} = sub {	426	$PORT{$portid} = sub {
401	local $SELF = $port;	427	local $SELF = $port;
402		428
403	if (my $cb = $self->[1]{$_[0]}) {	429	if (my $cb = $self->[1]{$_[0]}) {
…		…
425	}	451	}
426		452
427	$port	453	$port
428	}	454	}
429		455
		456	=item peval $port, $coderef[, @args]
		457
		458	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
		459	when the code throews an exception the C<$port> will be killed.
		460
		461	Any remaining args will be passed to the callback. Any return values will
		462	be returned to the caller.
		463
		464	This is useful when you temporarily want to execute code in the context of
		465	a port.
		466
		467	Example: create a port and run some initialisation code in it's context.
		468
		469	my $port = port { ... };
		470
		471	peval $port, sub {
		472	init
		473	or die "unable to init";
		474	};
		475
		476	=cut
		477
		478	sub peval($$) {
		479	local $SELF = shift;
		480	my $cb = shift;
		481
		482	if (wantarray) {
		483	my @res = eval { &$cb };
		484	_self_die if $@;
		485	@res
		486	} else {
		487	my $res = eval { &$cb };
		488	_self_die if $@;
		489	$res
		490	}
		491	}
		492
430	=item $closure = psub { BLOCK }	493	=item $closure = psub { BLOCK }
431		494
432	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	495	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
433	closure is executed, sets up the environment in the same way as in C<rcv>	496	closure is executed, sets up the environment in the same way as in C<rcv>
434	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.	497	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		498
		499	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		500	BLOCK }, @_ } >>.
435		501
436	This is useful when you register callbacks from C<rcv> callbacks:	502	This is useful when you register callbacks from C<rcv> callbacks:
437		503
438	rcv delayed_reply => sub {	504	rcv delayed_reply => sub {
439	my ($delay, @reply) = @_;	505	my ($delay, @reply) = @_;
…		…
512	delivered again.	578	delivered again.
513		579
514	Inter-host-connection timeouts and monitoring depend on the transport	580	Inter-host-connection timeouts and monitoring depend on the transport
515	used. The only transport currently implemented is TCP, and AnyEvent::MP	581	used. The only transport currently implemented is TCP, and AnyEvent::MP
516	relies on TCP to detect node-downs (this can take 10-15 minutes on a	582	relies on TCP to detect node-downs (this can take 10-15 minutes on a
517	non-idle connection, and usually around two hours for idle conenctions).	583	non-idle connection, and usually around two hours for idle connections).
518		584
519	This means that monitoring is good for program errors and cleaning up	585	This means that monitoring is good for program errors and cleaning up
520	stuff eventually, but they are no replacement for a timeout when you need	586	stuff eventually, but they are no replacement for a timeout when you need
521	to ensure some maximum latency.	587	to ensure some maximum latency.
522		588
…		…
554	}	620	}
555		621
556	$node->monitor ($port, $cb);	622	$node->monitor ($port, $cb);
557		623
558	defined wantarray	624	defined wantarray
559	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	625	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
560	}	626	}
561		627
562	=item $guard = mon_guard $port, $ref, $ref...	628	=item $guard = mon_guard $port, $ref, $ref...
563		629
564	Monitors the given C<$port> and keeps the passed references. When the port	630	Monitors the given C<$port> and keeps the passed references. When the port
…		…
587		653
588	=item kil $port[, @reason]	654	=item kil $port[, @reason]
589		655
590	Kill the specified port with the given C<@reason>.	656	Kill the specified port with the given C<@reason>.
591		657
592	If no C<@reason> is specified, then the port is killed "normally" (ports	658	If no C<@reason> is specified, then the port is killed "normally" -
593	monitoring other ports will not necessarily die because a port dies	659	monitor callback will be invoked, but the kil will not cause linked ports
594	"normally").	660	(C<mon $mport, $lport> form) to get killed.
595		661
596	Otherwise, linked ports get killed with the same reason (second form of	662	If a C<@reason> is specified, then linked ports (C<mon $mport, $lport>
597	C<mon>, see above).	663	form) get killed with the same reason.
598		664
599	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	665	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
600	will be reported as reason C<< die => $@ >>.	666	will be reported as reason C<< die => $@ >>.
601		667
602	Transport/communication errors are reported as C<< transport_error =>	668	Transport/communication errors are reported as C<< transport_error =>
…		…
621	the package, then the package above the package and so on (e.g.	687	the package, then the package above the package and so on (e.g.
622	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	688	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
623	exists or it runs out of package names.	689	exists or it runs out of package names.
624		690
625	The init function is then called with the newly-created port as context	691	The init function is then called with the newly-created port as context
626	object (C<$SELF>) and the C<@initdata> values as arguments.	692	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		693	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		694	the port might not get created.
627		695
628	A common idiom is to pass a local port, immediately monitor the spawned	696	A common idiom is to pass a local port, immediately monitor the spawned
629	port, and in the remote init function, immediately monitor the passed	697	port, and in the remote init function, immediately monitor the passed
630	local port. This two-way monitoring ensures that both ports get cleaned up	698	local port. This two-way monitoring ensures that both ports get cleaned up
631	when there is a problem.	699	when there is a problem.
…		…
655		723
656	sub _spawn {	724	sub _spawn {
657	my $port = shift;	725	my $port = shift;
658	my $init = shift;	726	my $init = shift;
659		727
		728	# rcv will create the actual port
660	local $SELF = "$NODE#$port";	729	local $SELF = "$NODE#$port";
661	eval {	730	eval {
662	&{ load_func $init }	731	&{ load_func $init }
663	};	732	};
664	_self_die if $@;	733	_self_die if $@;
…		…
699	? $action[0]()	768	? $action[0]()
700	: snd @action;	769	: snd @action;
701	};	770	};
702	}	771	}
703		772
		773	=item cal $port, @msg, $callback[, $timeout]
		774
		775	A simple form of RPC - sends a message to the given C<$port> with the
		776	given contents (C<@msg>), but adds a reply port to the message.
		777
		778	The reply port is created temporarily just for the purpose of receiving
		779	the reply, and will be C<kil>ed when no longer needed.
		780
		781	A reply message sent to the port is passed to the C<$callback> as-is.
		782
		783	If an optional time-out (in seconds) is given and it is not C<undef>,
		784	then the callback will be called without any arguments after the time-out
		785	elapsed and the port is C<kil>ed.
		786
		787	If no time-out is given (or it is C<undef>), then the local port will
		788	monitor the remote port instead, so it eventually gets cleaned-up.
		789
		790	Currently this function returns the temporary port, but this "feature"
		791	might go in future versions unless you can make a convincing case that
		792	this is indeed useful for something.
		793
		794	=cut
		795
		796	sub cal(@) {
		797	my $timeout = ref $_[-1] ? undef : pop;
		798	my $cb = pop;
		799
		800	my $port = port {
		801	undef $timeout;
		802	kil $SELF;
		803	&$cb;
		804	};
		805
		806	if (defined $timeout) {
		807	$timeout = AE::timer $timeout, 0, sub {
		808	undef $timeout;
		809	kil $port;
		810	$cb->();
		811	};
		812	} else {
		813	mon $_[0], sub {
		814	kil $port;
		815	$cb->();
		816	};
		817	}
		818
		819	push @_, $port;
		820	&snd;
		821
		822	$port
		823	}
		824
704	=back	825	=back
705		826
706	=head1 AnyEvent::MP vs. Distributed Erlang	827	=head1 AnyEvent::MP vs. Distributed Erlang
707		828
708	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	829	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
709	== aemp node, Erlang process == aemp port), so many of the documents and	830	== aemp node, Erlang process == aemp port), so many of the documents and
710	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	831	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
711	sample:	832	sample:
712		833
713	http://www.Erlang.se/doc/programming_rules.shtml	834	http://www.erlang.se/doc/programming_rules.shtml
714	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	835	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
715	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6	836	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
716	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	837	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
717		838
718	Despite the similarities, there are also some important differences:	839	Despite the similarities, there are also some important differences:
719		840
720	=over 4	841	=over 4
721		842
722	=item * Node IDs are arbitrary strings in AEMP.	843	=item * Node IDs are arbitrary strings in AEMP.
723		844
724	Erlang relies on special naming and DNS to work everywhere in the same	845	Erlang relies on special naming and DNS to work everywhere in the same
725	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by	846	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
726	configuration or DNS), but will otherwise discover other odes itself.	847	configuration or DNS), and possibly the addresses of some seed nodes, but
		848	will otherwise discover other nodes (and their IDs) itself.
727		849
728	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	850	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
729	uses "local ports are like remote ports".	851	uses "local ports are like remote ports".
730		852
731	The failure modes for local ports are quite different (runtime errors	853	The failure modes for local ports are quite different (runtime errors
…		…
756	so does not need a queue that can overflow). AEMP sends are immediate,	878	so does not need a queue that can overflow). AEMP sends are immediate,
757	connection establishment is handled in the background.	879	connection establishment is handled in the background.
758		880
759	=item * Erlang suffers from silent message loss, AEMP does not.	881	=item * Erlang suffers from silent message loss, AEMP does not.
760		882
761	Erlang makes few guarantees on messages delivery - messages can get lost	883	Erlang implements few guarantees on messages delivery - messages can get
762	without any of the processes realising it (i.e. you send messages a, b,	884	lost without any of the processes realising it (i.e. you send messages a,
763	and c, and the other side only receives messages a and c).	885	b, and c, and the other side only receives messages a and c).
764		886
765	AEMP guarantees correct ordering, and the guarantee that after one message	887	AEMP guarantees correct ordering, and the guarantee that after one message
766	is lost, all following ones sent to the same port are lost as well, until	888	is lost, all following ones sent to the same port are lost as well, until
767	monitoring raises an error, so there are no silent "holes" in the message	889	monitoring raises an error, so there are no silent "holes" in the message
768	sequence.	890	sequence.
…		…
830	overhead, as well as having to keep a proxy object everywhere.	952	overhead, as well as having to keep a proxy object everywhere.
831		953
832	Strings can easily be printed, easily serialised etc. and need no special	954	Strings can easily be printed, easily serialised etc. and need no special
833	procedures to be "valid".	955	procedures to be "valid".
834		956
835	And as a result, a miniport consists of a single closure stored in a	957	And as a result, a port with just a default receiver consists of a single
836	global hash - it can't become much cheaper.	958	closure stored in a global hash - it can't become much cheaper.
837		959
838	=item Why favour JSON, why not a real serialising format such as Storable?	960	=item Why favour JSON, why not a real serialising format such as Storable?
839		961
840	In fact, any AnyEvent::MP node will happily accept Storable as framing	962	In fact, any AnyEvent::MP node will happily accept Storable as framing
841	format, but currently there is no way to make a node use Storable by	963	format, but currently there is no way to make a node use Storable by
…		…
857		979
858	L<AnyEvent::MP::Intro> - a gentle introduction.	980	L<AnyEvent::MP::Intro> - a gentle introduction.
859		981
860	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	982	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
861		983
862	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	984	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
863	your applications.	985	your applications.
		986
		987	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
864		988
865	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from	989	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
866	all nodes.	990	all nodes.
867		991
868	L<AnyEvent>.	992	L<AnyEvent>.

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.81 by root, Mon Sep 7 18:33:44 2009 UTC vs. Revision 1.114 by root, Thu Apr 22 16:06:19 2010 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.81 by root, Mon Sep 7 18:33:44 2009 UTC vs.
Revision 1.114 by root, Thu Apr 22 16:06:19 2010 UTC