[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 1.120 by root, Sun Feb 26 11:12:54 2012 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 port 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 API, 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
…		…
61		71
62	=over 4	72	=over 4
63		73
64	=item port	74	=item port
65		75
66	A port is something you can send messages to (with the C<snd> function).	76	Not to be confused with a TCP port, a "port" is something you can send
		77	messages to (with the C<snd> function).
67		78
68	Ports allow you to register C<rcv> handlers that can match all or just	79	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	80	some messages. Messages send to ports will not be queued, regardless of
70	anything was listening for them or not.	81	anything was listening for them or not.
71		82
		83	Ports are represented by (printable) strings called "port IDs".
		84
72	=item port ID - C<nodeid#portname>	85	=item port ID - C<nodeid#portname>
73		86
74	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as	87	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
75	separator, and a port name (a printable string of unspecified format).	88	separator, and a port name (a printable string of unspecified format).
76		89
…		…
80	which enables nodes to manage each other remotely, and to create new	93	which enables nodes to manage each other remotely, and to create new
81	ports.	94	ports.
82		95
83	Nodes are either public (have one or more listening ports) or private	96	Nodes are either public (have one or more listening ports) or private
84	(no listening ports). Private nodes cannot talk to other private nodes	97	(no listening ports). Private nodes cannot talk to other private nodes
85	currently.	98	currently, but all nodes can talk to public nodes.
86		99
		100	Nodes is represented by (printable) strings called "node IDs".
		101
87	=item node ID - C<[a-za-Z0-9_\-.:]+>	102	=item node ID - C<[A-Za-z0-9_\-.:]*>
88		103
89	A node ID is a string that uniquely identifies the node within a	104	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	105	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	106	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
92	doesn't interpret node IDs in any way.	107	doesn't interpret node IDs in any way except to uniquely identify a node.
93		108
94	=item binds - C<ip:port>	109	=item binds - C<ip:port>
95		110
96	Nodes can only talk to each other by creating some kind of connection to	111	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	112	each other. To do this, nodes should listen on one or more local transport
		113	endpoints - binds.
		114
98	endpoints - binds. Currently, only standard C<ip:port> specifications can	115	Currently, only standard C<ip:port> specifications can be used, which
99	be used, which specify TCP ports to listen on.	116	specify TCP ports to listen on. So a bind is basically just a tcp socket
		117	in listening mode thta accepts conenctions form other nodes.
100		118
		119	=item seed nodes
		120
		121	When a node starts, it knows nothing about the network it is in - it
		122	needs to connect to at least one other node that is already in the
		123	network. These other nodes are called "seed nodes".
		124
		125	Seed nodes themselves are not special - they are seed nodes only because
		126	some other node I<uses> them as such, but any node can be used as seed
		127	node for other nodes, and eahc node cna use a different set of seed nodes.
		128
		129	In addition to discovering the network, seed nodes are also used to
		130	maintain the network - all nodes using the same seed node form are part of
		131	the same network. If a network is split into multiple subnets because e.g.
		132	the network link between the parts goes down, then using the same seed
		133	nodes for all nodes ensures that eventually the subnets get merged again.
		134
		135	Seed nodes are expected to be long-running, and at least one seed node
		136	should always be available. They should also be relatively responsive - a
		137	seed node that blocks for long periods will slow down everybody else.
		138
		139	For small networks, it's best if every node uses the same set of seed
		140	nodes. For large networks, it can be useful to specify "regional" seed
		141	nodes for most nodes in an area, and use all seed nodes as seed nodes for
		142	each other. What's important is that all seed nodes connections form a
		143	complete graph, so that the network cannot split into separate subnets
		144	forever.
		145
		146	Seed nodes are represented by seed IDs.
		147
101	=item seeds - C<host:port>	148	=item seed IDs - C<host:port>
102		149
103	When a node starts, it knows nothing about the network. To teach the node	150	Seed IDs are transport endpoint(s) (usually a hostname/IP address and a
104	about the network it first has to contact some other node within the	151	TCP port) of nodes that should be used as seed nodes.
105	network. This node is called a seed.
106		152
107	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	153	=item global nodes
108	are expected to be long-running, and at least one of those should always
109	be available. When nodes run out of connections (e.g. due to a network
110	error), they try to re-establish connections to some seednodes again to
111	join the network.
112		154
113	Apart from being sued for seeding, seednodes are not special in any way -	155	An AEMP network needs a discovery service - nodes need to know how to
114	every public node can be a seednode.	156	connect to other nodes they only know by name. In addition, AEMP offers a
		157	distributed "group database", which maps group names to a list of strings
		158	- for example, to register worker ports.
		159
		160	A network needs at least one global node to work, and allows every node to
		161	be a global node.
		162
		163	Any node that loads the L<AnyEvent::MP::Global> module becomes a global
		164	node and tries to keep connections to all other nodes. So while it can
		165	make sense to make every node "global" in small networks, it usually makes
		166	sense to only make seed nodes into global nodes in large networks (nodes
		167	keep connections to seed nodes and global nodes, so makign them the same
		168	reduces overhead).
115		169
116	=back	170	=back
117		171
118	=head1 VARIABLES/FUNCTIONS	172	=head1 VARIABLES/FUNCTIONS
119		173
…		…
131		185
132	use AE ();	186	use AE ();
133		187
134	use base "Exporter";	188	use base "Exporter";
135		189
136	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	190	our $VERSION = '1.30';
137		191
138	our @EXPORT = qw(	192	our @EXPORT = qw(
139	NODE $NODE *SELF node_of after	193	NODE $NODE *SELF node_of after
140	configure	194	configure
141	snd rcv mon mon_guard kil reg psub spawn	195	snd rcv mon mon_guard kil psub peval spawn cal
142	port	196	port
143	);	197	);
144		198
145	our $SELF;	199	our $SELF;
146		200
…		…
166		220
167	Before a node can talk to other nodes on the network (i.e. enter	221	Before a node can talk to other nodes on the network (i.e. enter
168	"distributed mode") it has to configure itself - the minimum a node needs	222	"distributed mode") it has to configure itself - the minimum a node needs
169	to know is its own name, and optionally it should know the addresses of	223	to know is its own name, and optionally it should know the addresses of
170	some other nodes in the network to discover other nodes.	224	some other nodes in the network to discover other nodes.
		225
		226	The key/value pairs are basically the same ones as documented for the
		227	F<aemp> command line utility (sans the set/del prefix).
171		228
172	This function configures a node - it must be called exactly once (or	229	This function configures a node - it must be called exactly once (or
173	never) before calling other AnyEvent::MP functions.	230	never) before calling other AnyEvent::MP functions.
174		231
175	=over 4	232	=over 4
…		…
209	used, meaning the node will bind on a dynamically-assigned port on every	266	used, meaning the node will bind on a dynamically-assigned port on every
210	local IP address it finds.	267	local IP address it finds.
211		268
212	=item step 3, connect to seed nodes	269	=item step 3, connect to seed nodes
213		270
214	As the last step, the seeds list from the profile is passed to the	271	As the last step, the seed ID list from the profile is passed to the
215	L<AnyEvent::MP::Global> module, which will then use it to keep	272	L<AnyEvent::MP::Global> module, which will then use it to keep
216	connectivity with at least one node at any point in time.	273	connectivity with at least one node at any point in time.
217		274
218	=back	275	=back
219		276
220	Example: become a distributed node using the locla node name as profile.	277	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.	278	This should be the most common form of invocation for "daemon"-type nodes.
222		279
223	configure	280	configure
224		281
225	Example: become an anonymous node. This form is often used for commandline	282	Example: become an anonymous node. This form is often used for commandline
226	clients.	283	clients.
227		284
228	configure nodeid => "anon/";	285	configure nodeid => "anon/";
229		286
230	Example: configure a node using a profile called seed, which si suitable	287	Example: configure a node using a profile called seed, which is suitable
231	for a seed node as it binds on all local addresses on a fixed port (4040,	288	for a seed node as it binds on all local addresses on a fixed port (4040,
232	customary for aemp).	289	customary for aemp).
233		290
234	# use the aemp commandline utility	291	# use the aemp commandline utility
235	# aemp profile seed nodeid anon/ binds '*:4040'	292	# aemp profile seed nodeid anon/ binds '*:4040'
…		…
359	msg1 => sub { ... },	416	msg1 => sub { ... },
360	...	417	...
361	;	418	;
362		419
363	Example: temporarily register a rcv callback for a tag matching some port	420	Example: temporarily register a rcv callback for a tag matching some port
364	(e.g. for a rpc reply) and unregister it after a message was received.	421	(e.g. for an rpc reply) and unregister it after a message was received.
365		422
366	rcv $port, $otherport => sub {	423	rcv $port, $otherport => sub {
367	my @reply = @_;	424	my @reply = @_;
368		425
369	rcv $SELF, $otherport;	426	rcv $SELF, $otherport;
…		…
382	if (ref $_[0]) {	439	if (ref $_[0]) {
383	if (my $self = $PORT_DATA{$portid}) {	440	if (my $self = $PORT_DATA{$portid}) {
384	"AnyEvent::MP::Port" eq ref $self	441	"AnyEvent::MP::Port" eq ref $self
385	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	442	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
386		443
387	$self->[2] = shift;	444	$self->[0] = shift;
388	} else {	445	} else {
389	my $cb = shift;	446	my $cb = shift;
390	$PORT{$portid} = sub {	447	$PORT{$portid} = sub {
391	local $SELF = $port;	448	local $SELF = $port;
392	eval { &$cb }; _self_die if $@;	449	eval { &$cb }; _self_die if $@;
393	};	450	};
394	}	451	}
395	} elsif (defined $_[0]) {	452	} elsif (defined $_[0]) {
396	my $self = $PORT_DATA{$portid} \|\|= do {	453	my $self = $PORT_DATA{$portid} \|\|= do {
397	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	454	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
398		455
399	$PORT{$portid} = sub {	456	$PORT{$portid} = sub {
400	local $SELF = $port;	457	local $SELF = $port;
401		458
402	if (my $cb = $self->[1]{$_[0]}) {	459	if (my $cb = $self->[1]{$_[0]}) {
…		…
424	}	481	}
425		482
426	$port	483	$port
427	}	484	}
428		485
		486	=item peval $port, $coderef[, @args]
		487
		488	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
		489	when the code throews an exception the C<$port> will be killed.
		490
		491	Any remaining args will be passed to the callback. Any return values will
		492	be returned to the caller.
		493
		494	This is useful when you temporarily want to execute code in the context of
		495	a port.
		496
		497	Example: create a port and run some initialisation code in it's context.
		498
		499	my $port = port { ... };
		500
		501	peval $port, sub {
		502	init
		503	or die "unable to init";
		504	};
		505
		506	=cut
		507
		508	sub peval($$) {
		509	local $SELF = shift;
		510	my $cb = shift;
		511
		512	if (wantarray) {
		513	my @res = eval { &$cb };
		514	_self_die if $@;
		515	@res
		516	} else {
		517	my $res = eval { &$cb };
		518	_self_die if $@;
		519	$res
		520	}
		521	}
		522
429	=item $closure = psub { BLOCK }	523	=item $closure = psub { BLOCK }
430		524
431	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	525	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
432	closure is executed, sets up the environment in the same way as in C<rcv>	526	closure is executed, sets up the environment in the same way as in C<rcv>
433	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.	527	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		528
		529	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		530	BLOCK }, @_ } >>.
434		531
435	This is useful when you register callbacks from C<rcv> callbacks:	532	This is useful when you register callbacks from C<rcv> callbacks:
436		533
437	rcv delayed_reply => sub {	534	rcv delayed_reply => sub {
438	my ($delay, @reply) = @_;	535	my ($delay, @reply) = @_;
…		…
474		571
475	Monitor the given port and do something when the port is killed or	572	Monitor the given port and do something when the port is killed or
476	messages to it were lost, and optionally return a guard that can be used	573	messages to it were lost, and optionally return a guard that can be used
477	to stop monitoring again.	574	to stop monitoring again.
478		575
		576	In the first form (callback), the callback is simply called with any
		577	number of C<@reason> elements (no @reason means that the port was deleted
		578	"normally"). Note also that I<< the callback B<must> never die >>, so use
		579	C<eval> if unsure.
		580
		581	In the second form (another port given), the other port (C<$rcvport>)
		582	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
		583	"normal" kils nothing happens, while under all other conditions, the other
		584	port is killed with the same reason.
		585
		586	The third form (kill self) is the same as the second form, except that
		587	C<$rvport> defaults to C<$SELF>.
		588
		589	In the last form (message), a message of the form C<@msg, @reason> will be
		590	C<snd>.
		591
		592	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		593	alert was raised), they are removed and will not trigger again.
		594
		595	As a rule of thumb, monitoring requests should always monitor a port from
		596	a local port (or callback). The reason is that kill messages might get
		597	lost, just like any other message. Another less obvious reason is that
		598	even monitoring requests can get lost (for example, when the connection
		599	to the other node goes down permanently). When monitoring a port locally
		600	these problems do not exist.
		601
479	C<mon> effectively guarantees that, in the absence of hardware failures,	602	C<mon> effectively guarantees that, in the absence of hardware failures,
480	after starting the monitor, either all messages sent to the port will	603	after starting the monitor, either all messages sent to the port will
481	arrive, or the monitoring action will be invoked after possible message	604	arrive, or the monitoring action will be invoked after possible message
482	loss has been detected. No messages will be lost "in between" (after	605	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	606	the first lost message no further messages will be received by the
484	port). After the monitoring action was invoked, further messages might get	607	port). After the monitoring action was invoked, further messages might get
485	delivered again.	608	delivered again.
486		609
487	Note that monitoring-actions are one-shot: once messages are lost (and a	610	Inter-host-connection timeouts and monitoring depend on the transport
488	monitoring alert was raised), they are removed and will not trigger again.	611	used. The only transport currently implemented is TCP, and AnyEvent::MP
		612	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		613	non-idle connection, and usually around two hours for idle connections).
489		614
490	In the first form (callback), the callback is simply called with any	615	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	616	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	617	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<$SELF>.
502
503	In the last form (message), a message of the form C<@msg, @reason> will be
504	C<snd>.
505
506	As a rule of thumb, monitoring requests should always monitor a port from
507	a local port (or callback). The reason is that kill messages might get
508	lost, just like any other message. Another less obvious reason is that
509	even monitoring requests can get lost (for example, when the connection
510	to the other node goes down permanently). When monitoring a port locally
511	these problems do not exist.
512		618
513	Example: call a given callback when C<$port> is killed.	619	Example: call a given callback when C<$port> is killed.
514		620
515	mon $port, sub { warn "port died because of <@_>\n" };	621	mon $port, sub { warn "port died because of <@_>\n" };
516		622
…		…
544	}	650	}
545		651
546	$node->monitor ($port, $cb);	652	$node->monitor ($port, $cb);
547		653
548	defined wantarray	654	defined wantarray
549	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	655	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
550	}	656	}
551		657
552	=item $guard = mon_guard $port, $ref, $ref...	658	=item $guard = mon_guard $port, $ref, $ref...
553		659
554	Monitors the given C<$port> and keeps the passed references. When the port	660	Monitors the given C<$port> and keeps the passed references. When the port
…		…
577		683
578	=item kil $port[, @reason]	684	=item kil $port[, @reason]
579		685
580	Kill the specified port with the given C<@reason>.	686	Kill the specified port with the given C<@reason>.
581		687
582	If no C<@reason> is specified, then the port is killed "normally" (ports	688	If no C<@reason> is specified, then the port is killed "normally" -
583	monitoring other ports will not necessarily die because a port dies	689	monitor callback will be invoked, but the kil will not cause linked ports
584	"normally").	690	(C<mon $mport, $lport> form) to get killed.
585		691
586	Otherwise, linked ports get killed with the same reason (second form of	692	If a C<@reason> is specified, then linked ports (C<mon $mport, $lport>
587	C<mon>, see above).	693	form) get killed with the same reason.
588		694
589	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	695	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
590	will be reported as reason C<< die => $@ >>.	696	will be reported as reason C<< die => $@ >>.
591		697
592	Transport/communication errors are reported as C<< transport_error =>	698	Transport/communication errors are reported as C<< transport_error =>
…		…
611	the package, then the package above the package and so on (e.g.	717	the package, then the package above the package and so on (e.g.
612	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	718	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
613	exists or it runs out of package names.	719	exists or it runs out of package names.
614		720
615	The init function is then called with the newly-created port as context	721	The init function is then called with the newly-created port as context
616	object (C<$SELF>) and the C<@initdata> values as arguments.	722	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		723	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		724	the port might not get created.
617		725
618	A common idiom is to pass a local port, immediately monitor the spawned	726	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	727	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	728	local port. This two-way monitoring ensures that both ports get cleaned up
621	when there is a problem.	729	when there is a problem.
622		730
		731	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		732	caller before C<spawn> returns (by delaying invocation when spawn is
		733	called for the local node).
		734
623	Example: spawn a chat server port on C<$othernode>.	735	Example: spawn a chat server port on C<$othernode>.
624		736
625	# this node, executed from within a port context:	737	# this node, executed from within a port context:
626	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	738	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
627	mon $server;	739	mon $server;
…		…
641		753
642	sub _spawn {	754	sub _spawn {
643	my $port = shift;	755	my $port = shift;
644	my $init = shift;	756	my $init = shift;
645		757
		758	# rcv will create the actual port
646	local $SELF = "$NODE#$port";	759	local $SELF = "$NODE#$port";
647	eval {	760	eval {
648	&{ load_func $init }	761	&{ load_func $init }
649	};	762	};
650	_self_die if $@;	763	_self_die if $@;
…		…
685	? $action[0]()	798	? $action[0]()
686	: snd @action;	799	: snd @action;
687	};	800	};
688	}	801	}
689		802
		803	=item cal $port, @msg, $callback[, $timeout]
		804
		805	A simple form of RPC - sends a message to the given C<$port> with the
		806	given contents (C<@msg>), but adds a reply port to the message.
		807
		808	The reply port is created temporarily just for the purpose of receiving
		809	the reply, and will be C<kil>ed when no longer needed.
		810
		811	A reply message sent to the port is passed to the C<$callback> as-is.
		812
		813	If an optional time-out (in seconds) is given and it is not C<undef>,
		814	then the callback will be called without any arguments after the time-out
		815	elapsed and the port is C<kil>ed.
		816
		817	If no time-out is given (or it is C<undef>), then the local port will
		818	monitor the remote port instead, so it eventually gets cleaned-up.
		819
		820	Currently this function returns the temporary port, but this "feature"
		821	might go in future versions unless you can make a convincing case that
		822	this is indeed useful for something.
		823
		824	=cut
		825
		826	sub cal(@) {
		827	my $timeout = ref $_[-1] ? undef : pop;
		828	my $cb = pop;
		829
		830	my $port = port {
		831	undef $timeout;
		832	kil $SELF;
		833	&$cb;
		834	};
		835
		836	if (defined $timeout) {
		837	$timeout = AE::timer $timeout, 0, sub {
		838	undef $timeout;
		839	kil $port;
		840	$cb->();
		841	};
		842	} else {
		843	mon $_[0], sub {
		844	kil $port;
		845	$cb->();
		846	};
		847	}
		848
		849	push @_, $port;
		850	&snd;
		851
		852	$port
		853	}
		854
690	=back	855	=back
691		856
692	=head1 AnyEvent::MP vs. Distributed Erlang	857	=head1 AnyEvent::MP vs. Distributed Erlang
693		858
694	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	859	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
695	== aemp node, Erlang process == aemp port), so many of the documents and	860	== aemp node, Erlang process == aemp port), so many of the documents and
696	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	861	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
697	sample:	862	sample:
698		863
699	http://www.Erlang.se/doc/programming_rules.shtml	864	http://www.erlang.se/doc/programming_rules.shtml
700	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	865	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
701	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6	866	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
702	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	867	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
703		868
704	Despite the similarities, there are also some important differences:	869	Despite the similarities, there are also some important differences:
705		870
706	=over 4	871	=over 4
707		872
708	=item * Node IDs are arbitrary strings in AEMP.	873	=item * Node IDs are arbitrary strings in AEMP.
709		874
710	Erlang relies on special naming and DNS to work everywhere in the same	875	Erlang relies on special naming and DNS to work everywhere in the same
711	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by	876	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
712	configuration or DNS), but will otherwise discover other odes itself.	877	configuration or DNS), and possibly the addresses of some seed nodes, but
		878	will otherwise discover other nodes (and their IDs) itself.
713		879
714	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	880	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
715	uses "local ports are like remote ports".	881	uses "local ports are like remote ports".
716		882
717	The failure modes for local ports are quite different (runtime errors	883	The failure modes for local ports are quite different (runtime errors
…		…
726	ports being the special case/exception, where transport errors cannot	892	ports being the special case/exception, where transport errors cannot
727	occur.	893	occur.
728		894
729	=item * Erlang uses processes and a mailbox, AEMP does not queue.	895	=item * Erlang uses processes and a mailbox, AEMP does not queue.
730		896
731	Erlang uses processes that selectively receive messages, and therefore	897	Erlang uses processes that selectively receive messages out of order, and
732	needs a queue. AEMP is event based, queuing messages would serve no	898	therefore needs a queue. AEMP is event based, queuing messages would serve
733	useful purpose. For the same reason the pattern-matching abilities of	899	no useful purpose. For the same reason the pattern-matching abilities
734	AnyEvent::MP are more limited, as there is little need to be able to	900	of AnyEvent::MP are more limited, as there is little need to be able to
735	filter messages without dequeuing them.	901	filter messages without dequeuing them.
736		902
737	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	903	This is not a philosophical difference, but simply stems from AnyEvent::MP
		904	being event-based, while Erlang is process-based.
		905
		906	You cna have a look at L<Coro::MP> for a more Erlang-like process model on
		907	top of AEMP and Coro threads.
738		908
739	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	909	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
740		910
741	Sending messages in Erlang is synchronous and blocks the process (and	911	Sending messages in Erlang is synchronous and blocks the process until
		912	a conenction has been established and the message sent (and so does not
742	so does not need a queue that can overflow). AEMP sends are immediate,	913	need a queue that can overflow). AEMP sends return immediately, connection
743	connection establishment is handled in the background.	914	establishment is handled in the background.
744		915
745	=item * Erlang suffers from silent message loss, AEMP does not.	916	=item * Erlang suffers from silent message loss, AEMP does not.
746		917
747	Erlang makes few guarantees on messages delivery - messages can get lost	918	Erlang implements few guarantees on messages delivery - messages can get
748	without any of the processes realising it (i.e. you send messages a, b,	919	lost without any of the processes realising it (i.e. you send messages a,
749	and c, and the other side only receives messages a and c).	920	b, and c, and the other side only receives messages a and c).
750		921
751	AEMP guarantees correct ordering, and the guarantee that after one message	922	AEMP guarantees (modulo hardware errors) correct ordering, and the
752	is lost, all following ones sent to the same port are lost as well, until	923	guarantee that after one message is lost, all following ones sent to the
753	monitoring raises an error, so there are no silent "holes" in the message	924	same port are lost as well, until monitoring raises an error, so there are
754	sequence.	925	no silent "holes" in the message sequence.
		926
		927	If you want your software to be very reliable, you have to cope with
		928	corrupted and even out-of-order messages in both Erlang and AEMP. AEMP
		929	simply tries to work better in common error cases, such as when a network
		930	link goes down.
755		931
756	=item * Erlang can send messages to the wrong port, AEMP does not.	932	=item * Erlang can send messages to the wrong port, AEMP does not.
757		933
758	In Erlang it is quite likely that a node that restarts reuses a process ID	934	In Erlang it is quite likely that a node that restarts reuses an Erlang
759	known to other nodes for a completely different process, causing messages	935	process ID known to other nodes for a completely different process,
760	destined for that process to end up in an unrelated process.	936	causing messages destined for that process to end up in an unrelated
		937	process.
761		938
762	AEMP never reuses port IDs, so old messages or old port IDs floating	939	AEMP does not reuse port IDs, so old messages or old port IDs floating
763	around in the network will not be sent to an unrelated port.	940	around in the network will not be sent to an unrelated port.
764		941
765	=item * Erlang uses unprotected connections, AEMP uses secure	942	=item * Erlang uses unprotected connections, AEMP uses secure
766	authentication and can use TLS.	943	authentication and can use TLS.
767		944
…		…
770		947
771	=item * The AEMP protocol is optimised for both text-based and binary	948	=item * The AEMP protocol is optimised for both text-based and binary
772	communications.	949	communications.
773		950
774	The AEMP protocol, unlike the Erlang protocol, supports both programming	951	The AEMP protocol, unlike the Erlang protocol, supports both programming
775	language independent text-only protocols (good for debugging) and binary,	952	language independent text-only protocols (good for debugging), and binary,
776	language-specific serialisers (e.g. Storable). By default, unless TLS is	953	language-specific serialisers (e.g. Storable). By default, unless TLS is
777	used, the protocol is actually completely text-based.	954	used, the protocol is actually completely text-based.
778		955
779	It has also been carefully designed to be implementable in other languages	956	It has also been carefully designed to be implementable in other languages
780	with a minimum of work while gracefully degrading functionality to make the	957	with a minimum of work while gracefully degrading functionality to make the
781	protocol simple.	958	protocol simple.
782		959
783	=item * AEMP has more flexible monitoring options than Erlang.	960	=item * AEMP has more flexible monitoring options than Erlang.
784		961
785	In Erlang, you can chose to receive I<all> exit signals as messages	962	In Erlang, you can chose to receive I<all> exit signals as messages or
786	or I<none>, there is no in-between, so monitoring single processes is	963	I<none>, there is no in-between, so monitoring single Erlang processes is
787	difficult to implement. Monitoring in AEMP is more flexible than in	964	difficult to implement.
788	Erlang, as one can choose between automatic kill, exit message or callback	965
789	on a per-process basis.	966	Monitoring in AEMP is more flexible than in Erlang, as one can choose
		967	between automatic kill, exit message or callback on a per-port basis.
790		968
791	=item * Erlang tries to hide remote/local connections, AEMP does not.	969	=item * Erlang tries to hide remote/local connections, AEMP does not.
792		970
793	Monitoring in Erlang is not an indicator of process death/crashes, in the	971	Monitoring in Erlang is not an indicator of process death/crashes, in the
794	same way as linking is (except linking is unreliable in Erlang).	972	same way as linking is (except linking is unreliable in Erlang).
…		…
816	overhead, as well as having to keep a proxy object everywhere.	994	overhead, as well as having to keep a proxy object everywhere.
817		995
818	Strings can easily be printed, easily serialised etc. and need no special	996	Strings can easily be printed, easily serialised etc. and need no special
819	procedures to be "valid".	997	procedures to be "valid".
820		998
821	And as a result, a miniport consists of a single closure stored in a	999	And as a result, a port with just a default receiver consists of a single
822	global hash - it can't become much cheaper.	1000	code reference stored in a global hash - it can't become much cheaper.
823		1001
824	=item Why favour JSON, why not a real serialising format such as Storable?	1002	=item Why favour JSON, why not a real serialising format such as Storable?
825		1003
826	In fact, any AnyEvent::MP node will happily accept Storable as framing	1004	In fact, any AnyEvent::MP node will happily accept Storable as framing
827	format, but currently there is no way to make a node use Storable by	1005	format, but currently there is no way to make a node use Storable by
…		…
843		1021
844	L<AnyEvent::MP::Intro> - a gentle introduction.	1022	L<AnyEvent::MP::Intro> - a gentle introduction.
845		1023
846	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1024	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
847		1025
848	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1026	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
849	your applications.	1027	your applications.
		1028
		1029	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
		1030
		1031	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		1032	all nodes.
850		1033
851	L<AnyEvent>.	1034	L<AnyEvent>.
852		1035
853	=head1 AUTHOR	1036	=head1 AUTHOR
854		1037

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Revision 1.78 by root, Thu Sep 3 20:16:36 2009 UTC vs.
Revision 1.120 by root, Sun Feb 26 11:12:54 2012 UTC