[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 1.105 by root, Sun Nov 8 23:58:02 2009 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 = 1.23;
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
…		…
216	L<AnyEvent::MP::Global> module, which will then use it to keep	239	L<AnyEvent::MP::Global> module, which will then use it to keep
217	connectivity with at least one node at any point in time.	240	connectivity with at least one node at any point in time.
218		241
219	=back	242	=back
220		243
221	Example: become a distributed node using the locla node name as profile.	244	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.	245	This should be the most common form of invocation for "daemon"-type nodes.
223		246
224	configure	247	configure
225		248
226	Example: become an anonymous node. This form is often used for commandline	249	Example: become an anonymous node. This form is often used for commandline
…		…
360	msg1 => sub { ... },	383	msg1 => sub { ... },
361	...	384	...
362	;	385	;
363		386
364	Example: temporarily register a rcv callback for a tag matching some port	387	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.	388	(e.g. for an rpc reply) and unregister it after a message was received.
366		389
367	rcv $port, $otherport => sub {	390	rcv $port, $otherport => sub {
368	my @reply = @_;	391	my @reply = @_;
369		392
370	rcv $SELF, $otherport;	393	rcv $SELF, $otherport;
…		…
383	if (ref $_[0]) {	406	if (ref $_[0]) {
384	if (my $self = $PORT_DATA{$portid}) {	407	if (my $self = $PORT_DATA{$portid}) {
385	"AnyEvent::MP::Port" eq ref $self	408	"AnyEvent::MP::Port" eq ref $self
386	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	409	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
387		410
388	$self->[2] = shift;	411	$self->[0] = shift;
389	} else {	412	} else {
390	my $cb = shift;	413	my $cb = shift;
391	$PORT{$portid} = sub {	414	$PORT{$portid} = sub {
392	local $SELF = $port;	415	local $SELF = $port;
393	eval { &$cb }; _self_die if $@;	416	eval { &$cb }; _self_die if $@;
394	};	417	};
395	}	418	}
396	} elsif (defined $_[0]) {	419	} elsif (defined $_[0]) {
397	my $self = $PORT_DATA{$portid} \|\|= do {	420	my $self = $PORT_DATA{$portid} \|\|= do {
398	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	421	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
399		422
400	$PORT{$portid} = sub {	423	$PORT{$portid} = sub {
401	local $SELF = $port;	424	local $SELF = $port;
402		425
403	if (my $cb = $self->[1]{$_[0]}) {	426	if (my $cb = $self->[1]{$_[0]}) {
…		…
425	}	448	}
426		449
427	$port	450	$port
428	}	451	}
429		452
		453	=item peval $port, $coderef[, @args]
		454
		455	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
		456	when the code throews an exception the C<$port> will be killed.
		457
		458	Any remaining args will be passed to the callback. Any return values will
		459	be returned to the caller.
		460
		461	This is useful when you temporarily want to execute code in the context of
		462	a port.
		463
		464	Example: create a port and run some initialisation code in it's context.
		465
		466	my $port = port { ... };
		467
		468	peval $port, sub {
		469	init
		470	or die "unable to init";
		471	};
		472
		473	=cut
		474
		475	sub peval($$) {
		476	local $SELF = shift;
		477	my $cb = shift;
		478
		479	if (wantarray) {
		480	my @res = eval { &$cb };
		481	_self_die if $@;
		482	@res
		483	} else {
		484	my $res = eval { &$cb };
		485	_self_die if $@;
		486	$res
		487	}
		488	}
		489
430	=item $closure = psub { BLOCK }	490	=item $closure = psub { BLOCK }
431		491
432	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	492	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>	493	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.	494	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		495
		496	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		497	BLOCK } } >>.
435		498
436	This is useful when you register callbacks from C<rcv> callbacks:	499	This is useful when you register callbacks from C<rcv> callbacks:
437		500
438	rcv delayed_reply => sub {	501	rcv delayed_reply => sub {
439	my ($delay, @reply) = @_;	502	my ($delay, @reply) = @_;
…		…
512	delivered again.	575	delivered again.
513		576
514	Inter-host-connection timeouts and monitoring depend on the transport	577	Inter-host-connection timeouts and monitoring depend on the transport
515	used. The only transport currently implemented is TCP, and AnyEvent::MP	578	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	579	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).	580	non-idle connection, and usually around two hours for idle connections).
518		581
519	This means that monitoring is good for program errors and cleaning up	582	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	583	stuff eventually, but they are no replacement for a timeout when you need
521	to ensure some maximum latency.	584	to ensure some maximum latency.
522		585
…		…
554	}	617	}
555		618
556	$node->monitor ($port, $cb);	619	$node->monitor ($port, $cb);
557		620
558	defined wantarray	621	defined wantarray
559	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	622	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
560	}	623	}
561		624
562	=item $guard = mon_guard $port, $ref, $ref...	625	=item $guard = mon_guard $port, $ref, $ref...
563		626
564	Monitors the given C<$port> and keeps the passed references. When the port	627	Monitors the given C<$port> and keeps the passed references. When the port
…		…
621	the package, then the package above the package and so on (e.g.	684	the package, then the package above the package and so on (e.g.
622	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	685	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
623	exists or it runs out of package names.	686	exists or it runs out of package names.
624		687
625	The init function is then called with the newly-created port as context	688	The init function is then called with the newly-created port as context
626	object (C<$SELF>) and the C<@initdata> values as arguments.	689	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		690	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		691	the port might not get created.
627		692
628	A common idiom is to pass a local port, immediately monitor the spawned	693	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	694	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	695	local port. This two-way monitoring ensures that both ports get cleaned up
631	when there is a problem.	696	when there is a problem.
…		…
655		720
656	sub _spawn {	721	sub _spawn {
657	my $port = shift;	722	my $port = shift;
658	my $init = shift;	723	my $init = shift;
659		724
		725	# rcv will create the actual port
660	local $SELF = "$NODE#$port";	726	local $SELF = "$NODE#$port";
661	eval {	727	eval {
662	&{ load_func $init }	728	&{ load_func $init }
663	};	729	};
664	_self_die if $@;	730	_self_die if $@;
…		…
699	? $action[0]()	765	? $action[0]()
700	: snd @action;	766	: snd @action;
701	};	767	};
702	}	768	}
703		769
		770	=item cal $port, @msg, $callback[, $timeout]
		771
		772	A simple form of RPC - sends a message to the given C<$port> with the
		773	given contents (C<@msg>), but adds a reply port to the message.
		774
		775	The reply port is created temporarily just for the purpose of receiving
		776	the reply, and will be C<kil>ed when no longer needed.
		777
		778	A reply message sent to the port is passed to the C<$callback> as-is.
		779
		780	If an optional time-out (in seconds) is given and it is not C<undef>,
		781	then the callback will be called without any arguments after the time-out
		782	elapsed and the port is C<kil>ed.
		783
		784	If no time-out is given (or it is C<undef>), then the local port will
		785	monitor the remote port instead, so it eventually gets cleaned-up.
		786
		787	Currently this function returns the temporary port, but this "feature"
		788	might go in future versions unless you can make a convincing case that
		789	this is indeed useful for something.
		790
		791	=cut
		792
		793	sub cal(@) {
		794	my $timeout = ref $_[-1] ? undef : pop;
		795	my $cb = pop;
		796
		797	my $port = port {
		798	undef $timeout;
		799	kil $SELF;
		800	&$cb;
		801	};
		802
		803	if (defined $timeout) {
		804	$timeout = AE::timer $timeout, 0, sub {
		805	undef $timeout;
		806	kil $port;
		807	$cb->();
		808	};
		809	} else {
		810	mon $_[0], sub {
		811	kil $port;
		812	$cb->();
		813	};
		814	}
		815
		816	push @_, $port;
		817	&snd;
		818
		819	$port
		820	}
		821
704	=back	822	=back
705		823
706	=head1 AnyEvent::MP vs. Distributed Erlang	824	=head1 AnyEvent::MP vs. Distributed Erlang
707		825
708	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	826	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	827	== 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	828	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
711	sample:	829	sample:
712		830
713	http://www.Erlang.se/doc/programming_rules.shtml	831	http://www.erlang.se/doc/programming_rules.shtml
714	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	832	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	833	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	834	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
717		835
718	Despite the similarities, there are also some important differences:	836	Despite the similarities, there are also some important differences:
719		837
720	=over 4	838	=over 4
721		839
722	=item * Node IDs are arbitrary strings in AEMP.	840	=item * Node IDs are arbitrary strings in AEMP.
723		841
724	Erlang relies on special naming and DNS to work everywhere in the same	842	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	843	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.	844	configuration or DNS), and possibly the addresses of some seed nodes, but
		845	will otherwise discover other nodes (and their IDs) itself.
727		846
728	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	847	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
729	uses "local ports are like remote ports".	848	uses "local ports are like remote ports".
730		849
731	The failure modes for local ports are quite different (runtime errors	850	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,	875	so does not need a queue that can overflow). AEMP sends are immediate,
757	connection establishment is handled in the background.	876	connection establishment is handled in the background.
758		877
759	=item * Erlang suffers from silent message loss, AEMP does not.	878	=item * Erlang suffers from silent message loss, AEMP does not.
760		879
761	Erlang makes few guarantees on messages delivery - messages can get lost	880	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,	881	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).	882	b, and c, and the other side only receives messages a and c).
764		883
765	AEMP guarantees correct ordering, and the guarantee that after one message	884	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	885	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	886	monitoring raises an error, so there are no silent "holes" in the message
768	sequence.	887	sequence.
…		…
860	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	979	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
861		980
862	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	981	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
863	your applications.	982	your applications.
864		983
		984	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
		985
865	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from	986	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
866	all nodes.	987	all nodes.
867		988
868	L<AnyEvent>.	989	L<AnyEvent>.
869		990

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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 1.105 by root, Sun Nov 8 23:58:02 2009 UTC

Diff Legend

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.81 by root, Mon Sep 7 18:33:44 2009 UTC vs.
Revision 1.105 by root, Sun Nov 8 23:58:02 2009 UTC