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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.78 by root, Thu Sep 3 20:16:36 2009 UTC vs.
Revision 1.93 by root, Tue Sep 22 14:14:29 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
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	# monitoring	35	# monitoring
36	mon $port, $cb->(@msg) # callback is invoked on death	36	mon $localport, $cb->(@msg) # callback is invoked on death
37	mon $port, $otherport # kill otherport on abnormal death	37	mon $localport, $otherport # kill otherport on abnormal death
38	mon $port, $otherport, @msg # send message on death	38	mon $localport, $otherport, @msg # send message on death
39		39
40	=head1 CURRENT STATUS	40	=head1 CURRENT STATUS
41		41
42	bin/aemp - stable.	42	bin/aemp - stable.
43	AnyEvent::MP - stable API, should work.	43	AnyEvent::MP - stable API, should work.
44	AnyEvent::MP::Intro - explains most concepts.	44	AnyEvent::MP::Intro - explains most concepts.
45	AnyEvent::MP::Kernel - mostly stable.	45	AnyEvent::MP::Kernel - mostly stable API.
46	AnyEvent::MP::Global - stable API, protocol not yet final.	46	AnyEvent::MP::Global - stable API.
47
48	stay tuned.
49		47
50	=head1 DESCRIPTION	48	=head1 DESCRIPTION
51		49
52	This module (-family) implements a simple message passing framework.	50	This module (-family) implements a simple message passing framework.
53		51
…		…
61		59
62	=over 4	60	=over 4
63		61
64	=item port	62	=item port
65		63
66	A port is something you can send messages to (with the C<snd> function).	64	Not to be confused with a TCP port, a "port" is something you can send
		65	messages to (with the C<snd> function).
67		66
68	Ports allow you to register C<rcv> handlers that can match all or just	67	Ports allow you to register C<rcv> handlers that can match all or just
69	some messages. Messages send to ports will not be queued, regardless of	68	some messages. Messages send to ports will not be queued, regardless of
70	anything was listening for them or not.	69	anything was listening for them or not.
71		70
…		…
82		81
83	Nodes are either public (have one or more listening ports) or private	82	Nodes are either public (have one or more listening ports) or private
84	(no listening ports). Private nodes cannot talk to other private nodes	83	(no listening ports). Private nodes cannot talk to other private nodes
85	currently.	84	currently.
86		85
87	=item node ID - C<[a-za-Z0-9_\-.:]+>	86	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
88		87
89	A node ID is a string that uniquely identifies the node within a	88	A node ID is a string that uniquely identifies the node within a
90	network. Depending on the configuration used, node IDs can look like a	89	network. Depending on the configuration used, node IDs can look like a
91	hostname, a hostname and a port, or a random string. AnyEvent::MP itself	90	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
92	doesn't interpret node IDs in any way.	91	doesn't interpret node IDs in any way.
…		…
96	Nodes can only talk to each other by creating some kind of connection to	95	Nodes can only talk to each other by creating some kind of connection to
97	each other. To do this, nodes should listen on one or more local transport	96	each other. To do this, nodes should listen on one or more local transport
98	endpoints - binds. Currently, only standard C<ip:port> specifications can	97	endpoints - binds. Currently, only standard C<ip:port> specifications can
99	be used, which specify TCP ports to listen on.	98	be used, which specify TCP ports to listen on.
100		99
101	=item seeds - C<host:port>	100	=item seed nodes
102		101
103	When a node starts, it knows nothing about the network. To teach the node	102	When a node starts, it knows nothing about the network. To teach the node
104	about the network it first has to contact some other node within the	103	about the network it first has to contact some other node within the
105	network. This node is called a seed.	104	network. This node is called a seed.
106		105
107	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	106	Apart from the fact that other nodes know them as seed nodes and they have
		107	to have fixed listening addresses, seed nodes are perfectly normal nodes -
		108	any node can function as a seed node for others.
		109
		110	In addition to discovering the network, seed nodes are also used to
		111	maintain the network and to connect nodes that otherwise would have
		112	trouble connecting. They form the backbone of an AnyEvent::MP network.
		113
108	are expected to be long-running, and at least one of those should always	114	Seed nodes are expected to be long-running, and at least one seed node
109	be available. When nodes run out of connections (e.g. due to a network	115	should always be available. They should also be relatively responsive - a
110	error), they try to re-establish connections to some seednodes again to	116	seed node that blocks for long periods will slow down everybody else.
111	join the network.
112		117
113	Apart from being sued for seeding, seednodes are not special in any way -	118	=item seeds - C<host:port>
114	every public node can be a seednode.	119
		120	Seeds are transport endpoint(s) (usually a hostname/IP address and a
		121	TCP port) of nodes thta should be used as seed nodes.
		122
		123	The nodes listening on those endpoints are expected to be long-running,
		124	and at least one of those should always be available. When nodes run out
		125	of connections (e.g. due to a network error), they try to re-establish
		126	connections to some seednodes again to join the network.
115		127
116	=back	128	=back
117		129
118	=head1 VARIABLES/FUNCTIONS	130	=head1 VARIABLES/FUNCTIONS
119		131
…		…
136	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	148	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
137		149
138	our @EXPORT = qw(	150	our @EXPORT = qw(
139	NODE $NODE *SELF node_of after	151	NODE $NODE *SELF node_of after
140	configure	152	configure
141	snd rcv mon mon_guard kil reg psub spawn	153	snd rcv mon mon_guard kil psub spawn cal
142	port	154	port
143	);	155	);
144		156
145	our $SELF;	157	our $SELF;
146		158
…		…
215	L<AnyEvent::MP::Global> module, which will then use it to keep	227	L<AnyEvent::MP::Global> module, which will then use it to keep
216	connectivity with at least one node at any point in time.	228	connectivity with at least one node at any point in time.
217		229
218	=back	230	=back
219		231
220	Example: become a distributed node using the locla node name as profile.	232	Example: become a distributed node using the local node name as profile.
221	This should be the most common form of invocation for "daemon"-type nodes.	233	This should be the most common form of invocation for "daemon"-type nodes.
222		234
223	configure	235	configure
224		236
225	Example: become an anonymous node. This form is often used for commandline	237	Example: become an anonymous node. This form is often used for commandline
…		…
474		486
475	Monitor the given port and do something when the port is killed or	487	Monitor the given port and do something when the port is killed or
476	messages to it were lost, and optionally return a guard that can be used	488	messages to it were lost, and optionally return a guard that can be used
477	to stop monitoring again.	489	to stop monitoring again.
478		490
		491	In the first form (callback), the callback is simply called with any
		492	number of C<@reason> elements (no @reason means that the port was deleted
		493	"normally"). Note also that I<< the callback B<must> never die >>, so use
		494	C<eval> if unsure.
		495
		496	In the second form (another port given), the other port (C<$rcvport>)
		497	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
		498	"normal" kils nothing happens, while under all other conditions, the other
		499	port is killed with the same reason.
		500
		501	The third form (kill self) is the same as the second form, except that
		502	C<$rvport> defaults to C<$SELF>.
		503
		504	In the last form (message), a message of the form C<@msg, @reason> will be
		505	C<snd>.
		506
		507	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		508	alert was raised), they are removed and will not trigger again.
		509
		510	As a rule of thumb, monitoring requests should always monitor a port from
		511	a local port (or callback). The reason is that kill messages might get
		512	lost, just like any other message. Another less obvious reason is that
		513	even monitoring requests can get lost (for example, when the connection
		514	to the other node goes down permanently). When monitoring a port locally
		515	these problems do not exist.
		516
479	C<mon> effectively guarantees that, in the absence of hardware failures,	517	C<mon> effectively guarantees that, in the absence of hardware failures,
480	after starting the monitor, either all messages sent to the port will	518	after starting the monitor, either all messages sent to the port will
481	arrive, or the monitoring action will be invoked after possible message	519	arrive, or the monitoring action will be invoked after possible message
482	loss has been detected. No messages will be lost "in between" (after	520	loss has been detected. No messages will be lost "in between" (after
483	the first lost message no further messages will be received by the	521	the first lost message no further messages will be received by the
484	port). After the monitoring action was invoked, further messages might get	522	port). After the monitoring action was invoked, further messages might get
485	delivered again.	523	delivered again.
486		524
487	Note that monitoring-actions are one-shot: once messages are lost (and a	525	Inter-host-connection timeouts and monitoring depend on the transport
488	monitoring alert was raised), they are removed and will not trigger again.	526	used. The only transport currently implemented is TCP, and AnyEvent::MP
		527	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		528	non-idle connection, and usually around two hours for idle conenctions).
489		529
490	In the first form (callback), the callback is simply called with any	530	This means that monitoring is good for program errors and cleaning up
491	number of C<@reason> elements (no @reason means that the port was deleted	531	stuff eventually, but they are no replacement for a timeout when you need
492	"normally"). Note also that I<< the callback B<must> never die >>, so use	532	to ensure some maximum latency.
493	C<eval> if unsure.
494
495	In the second form (another port given), the other port (C<$rcvport>)
496	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
497	"normal" kils nothing happens, while under all other conditions, the other
498	port is killed with the same reason.
499
500	The third form (kill self) is the same as the second form, except that
501	C<$rvport> defaults to C<$SELF>.
502
503	In the last form (message), a message of the form C<@msg, @reason> will be
504	C<snd>.
505
506	As a rule of thumb, monitoring requests should always monitor a port from
507	a local port (or callback). The reason is that kill messages might get
508	lost, just like any other message. Another less obvious reason is that
509	even monitoring requests can get lost (for example, when the connection
510	to the other node goes down permanently). When monitoring a port locally
511	these problems do not exist.
512		533
513	Example: call a given callback when C<$port> is killed.	534	Example: call a given callback when C<$port> is killed.
514		535
515	mon $port, sub { warn "port died because of <@_>\n" };	536	mon $port, sub { warn "port died because of <@_>\n" };
516		537
…		…
544	}	565	}
545		566
546	$node->monitor ($port, $cb);	567	$node->monitor ($port, $cb);
547		568
548	defined wantarray	569	defined wantarray
		570	and $cb += 0
549	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	571	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
550	}	572	}
551		573
552	=item $guard = mon_guard $port, $ref, $ref...	574	=item $guard = mon_guard $port, $ref, $ref...
553		575
…		…
611	the package, then the package above the package and so on (e.g.	633	the package, then the package above the package and so on (e.g.
612	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	634	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
613	exists or it runs out of package names.	635	exists or it runs out of package names.
614		636
615	The init function is then called with the newly-created port as context	637	The init function is then called with the newly-created port as context
616	object (C<$SELF>) and the C<@initdata> values as arguments.	638	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		639	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		640	the port might not get created.
617		641
618	A common idiom is to pass a local port, immediately monitor the spawned	642	A common idiom is to pass a local port, immediately monitor the spawned
619	port, and in the remote init function, immediately monitor the passed	643	port, and in the remote init function, immediately monitor the passed
620	local port. This two-way monitoring ensures that both ports get cleaned up	644	local port. This two-way monitoring ensures that both ports get cleaned up
621	when there is a problem.	645	when there is a problem.
622		646
		647	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		648	caller before C<spawn> returns (by delaying invocation when spawn is
		649	called for the local node).
		650
623	Example: spawn a chat server port on C<$othernode>.	651	Example: spawn a chat server port on C<$othernode>.
624		652
625	# this node, executed from within a port context:	653	# this node, executed from within a port context:
626	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	654	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
627	mon $server;	655	mon $server;
…		…
641		669
642	sub _spawn {	670	sub _spawn {
643	my $port = shift;	671	my $port = shift;
644	my $init = shift;	672	my $init = shift;
645		673
		674	# rcv will create the actual port
646	local $SELF = "$NODE#$port";	675	local $SELF = "$NODE#$port";
647	eval {	676	eval {
648	&{ load_func $init }	677	&{ load_func $init }
649	};	678	};
650	_self_die if $@;	679	_self_die if $@;
…		…
685	? $action[0]()	714	? $action[0]()
686	: snd @action;	715	: snd @action;
687	};	716	};
688	}	717	}
689		718
		719	=item cal $port, @msg, $callback[, $timeout]
		720
		721	A simple form of RPC - sends a message to the given C<$port> with the
		722	given contents (C<@msg>), but adds a reply port to the message.
		723
		724	The reply port is created temporarily just for the purpose of receiving
		725	the reply, and will be C<kil>ed when no longer needed.
		726
		727	A reply message sent to the port is passed to the C<$callback> as-is.
		728
		729	If an optional time-out (in seconds) is given and it is not C<undef>,
		730	then the callback will be called without any arguments after the time-out
		731	elapsed and the port is C<kil>ed.
		732
		733	If no time-out is given, then the local port will monitor the remote port
		734	instead, so it eventually gets cleaned-up.
		735
		736	Currently this function returns the temporary port, but this "feature"
		737	might go in future versions unless you can make a convincing case that
		738	this is indeed useful for something.
		739
		740	=cut
		741
		742	sub cal(@) {
		743	my $timeout = ref $_[-1] ? undef : pop;
		744	my $cb = pop;
		745
		746	my $port = port {
		747	undef $timeout;
		748	kil $SELF;
		749	&$cb;
		750	};
		751
		752	if (defined $timeout) {
		753	$timeout = AE::timer $timeout, 0, sub {
		754	undef $timeout;
		755	kil $port;
		756	$cb->();
		757	};
		758	} else {
		759	mon $_[0], sub {
		760	kil $port;
		761	$cb->();
		762	};
		763	}
		764
		765	push @_, $port;
		766	&snd;
		767
		768	$port
		769	}
		770
690	=back	771	=back
691		772
692	=head1 AnyEvent::MP vs. Distributed Erlang	773	=head1 AnyEvent::MP vs. Distributed Erlang
693		774
694	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	775	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
…		…
846	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	927	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
847		928
848	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	929	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
849	your applications.	930	your applications.
850		931
		932	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		933	all nodes.
		934
851	L<AnyEvent>.	935	L<AnyEvent>.
852		936
853	=head1 AUTHOR	937	=head1 AUTHOR
854		938
855	Marc Lehmann <schmorp@schmorp.de>	939	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.78 by root, Thu Sep 3 20:16:36 2009 UTC vs. Revision 1.93 by root, Tue Sep 22 14:14:29 2009 UTC

Diff Legend

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.78 by root, Thu Sep 3 20:16:36 2009 UTC vs.
Revision 1.93 by root, Tue Sep 22 14:14:29 2009 UTC