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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.77 by elmex, Thu Sep 3 07:57:30 2009 UTC vs.
Revision 1.119 by root, Sun Feb 26 10:29:59 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
…		…
158		212
159	=item $nodeid = node_of $port	213	=item $nodeid = node_of $port
160		214
161	Extracts and returns the node ID from a port ID or a node ID.	215	Extracts and returns the node ID from a port ID or a node ID.
162		216
		217	=item configure $profile, key => value...
		218
163	=item configure key => value...	219	=item configure key => value...
164		220
165	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
166	"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
167	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
168	some other nodes in the network to discover other nodes.	224	some other nodes in the network to discover other nodes.
169		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).
		228
170	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
171	never) before calling other AnyEvent::MP functions.	230	never) before calling other AnyEvent::MP functions.
172		231
173	=over 4	232	=over 4
174		233
175	=item step 1, gathering configuration from profiles	234	=item step 1, gathering configuration from profiles
176		235
177	The function first looks up a profile in the aemp configuration (see the	236	The function first looks up a profile in the aemp configuration (see the
178	L<aemp> commandline utility). The profile name can be specified via the	237	L<aemp> commandline utility). The profile name can be specified via the
179	named C<profile> parameter. If it is missing, then the nodename (F<uname	238	named C<profile> parameter or can simply be the first parameter). If it is
180	-n>) will be used as profile name.	239	missing, then the nodename (F<uname -n>) will be used as profile name.
181		240
182	The profile data is then gathered as follows:	241	The profile data is then gathered as follows:
183		242
184	First, all remaining key => value pairs (all of which are conveniently	243	First, all remaining key => value pairs (all of which are conveniently
185	undocumented at the moment) will be interpreted as configuration	244	undocumented at the moment) will be interpreted as configuration
…		…
207	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
208	local IP address it finds.	267	local IP address it finds.
209		268
210	=item step 3, connect to seed nodes	269	=item step 3, connect to seed nodes
211		270
212	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
213	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
214	connectivity with at least one node at any point in time.	273	connectivity with at least one node at any point in time.
215		274
216	=back	275	=back
217		276
218	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.
219	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.
220		279
221	configure	280	configure
222		281
223	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
…		…
357	msg1 => sub { ... },	416	msg1 => sub { ... },
358	...	417	...
359	;	418	;
360		419
361	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
362	(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.
363		422
364	rcv $port, $otherport => sub {	423	rcv $port, $otherport => sub {
365	my @reply = @_;	424	my @reply = @_;
366		425
367	rcv $SELF, $otherport;	426	rcv $SELF, $otherport;
…		…
380	if (ref $_[0]) {	439	if (ref $_[0]) {
381	if (my $self = $PORT_DATA{$portid}) {	440	if (my $self = $PORT_DATA{$portid}) {
382	"AnyEvent::MP::Port" eq ref $self	441	"AnyEvent::MP::Port" eq ref $self
383	or Carp::croak "$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";
384		443
385	$self->[2] = shift;	444	$self->[0] = shift;
386	} else {	445	} else {
387	my $cb = shift;	446	my $cb = shift;
388	$PORT{$portid} = sub {	447	$PORT{$portid} = sub {
389	local $SELF = $port;	448	local $SELF = $port;
390	eval { &$cb }; _self_die if $@;	449	eval { &$cb }; _self_die if $@;
391	};	450	};
392	}	451	}
393	} elsif (defined $_[0]) {	452	} elsif (defined $_[0]) {
394	my $self = $PORT_DATA{$portid} \|\|= do {	453	my $self = $PORT_DATA{$portid} \|\|= do {
395	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	454	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
396		455
397	$PORT{$portid} = sub {	456	$PORT{$portid} = sub {
398	local $SELF = $port;	457	local $SELF = $port;
399		458
400	if (my $cb = $self->[1]{$_[0]}) {	459	if (my $cb = $self->[1]{$_[0]}) {
…		…
422	}	481	}
423		482
424	$port	483	$port
425	}	484	}
426		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
427	=item $closure = psub { BLOCK }	523	=item $closure = psub { BLOCK }
428		524
429	Remembers C<$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
430	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>
431	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 $SELF, sub {
		530	BLOCK }, @_ } >>.
432		531
433	This is useful when you register callbacks from C<rcv> callbacks:	532	This is useful when you register callbacks from C<rcv> callbacks:
434		533
435	rcv delayed_reply => sub {	534	rcv delayed_reply => sub {
436	my ($delay, @reply) = @_;	535	my ($delay, @reply) = @_;
…		…
472		571
473	Monitor the given port and do something when the port is killed or	572	Monitor the given port and do something when the port is killed or
474	messages to it were lost, and optionally return a guard that can be used	573	messages to it were lost, and optionally return a guard that can be used
475	to stop monitoring again.	574	to stop monitoring again.
476		575
		576	In the first form (callback), the callback is simply called with any
		577	number of C<@reason> elements (no @reason means that the port was deleted
		578	"normally"). Note also that I<< the callback B<must> never die >>, so use
		579	C<eval> if unsure.
		580
		581	In the second form (another port given), the other port (C<$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
477	C<mon> effectively guarantees that, in the absence of hardware failures,	602	C<mon> effectively guarantees that, in the absence of hardware failures,
478	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
479	arrive, or the monitoring action will be invoked after possible message	604	arrive, or the monitoring action will be invoked after possible message
480	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
481	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
482	port). After the monitoring action was invoked, further messages might get	607	port). After the monitoring action was invoked, further messages might get
483	delivered again.	608	delivered again.
484		609
485	Note that monitoring-actions are one-shot: once messages are lost (and a	610	Inter-host-connection timeouts and monitoring depend on the transport
486	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).
487		614
488	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
489	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
490	"normally"). Note also that I<< the callback B<must> never die >>, so use	617	to ensure some maximum latency.
491	C<eval> if unsure.
492
493	In the second form (another port given), the other port (C<$rcvport>)
494	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
495	"normal" kils nothing happens, while under all other conditions, the other
496	port is killed with the same reason.
497
498	The third form (kill self) is the same as the second form, except that
499	C<$rvport> defaults to C<$SELF>.
500
501	In the last form (message), a message of the form C<@msg, @reason> will be
502	C<snd>.
503
504	As a rule of thumb, monitoring requests should always monitor a port from
505	a local port (or callback). The reason is that kill messages might get
506	lost, just like any other message. Another less obvious reason is that
507	even monitoring requests can get lost (for example, when the connection
508	to the other node goes down permanently). When monitoring a port locally
509	these problems do not exist.
510		618
511	Example: call a given callback when C<$port> is killed.	619	Example: call a given callback when C<$port> is killed.
512		620
513	mon $port, sub { warn "port died because of <@_>\n" };	621	mon $port, sub { warn "port died because of <@_>\n" };
514		622
…		…
542	}	650	}
543		651
544	$node->monitor ($port, $cb);	652	$node->monitor ($port, $cb);
545		653
546	defined wantarray	654	defined wantarray
547	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	655	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
548	}	656	}
549		657
550	=item $guard = mon_guard $port, $ref, $ref...	658	=item $guard = mon_guard $port, $ref, $ref...
551		659
552	Monitors the given C<$port> and keeps the passed references. When the port	660	Monitors the given C<$port> and keeps the passed references. When the port
…		…
575		683
576	=item kil $port[, @reason]	684	=item kil $port[, @reason]
577		685
578	Kill the specified port with the given C<@reason>.	686	Kill the specified port with the given C<@reason>.
579		687
580	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" -
581	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
582	"normally").	690	(C<mon $mport, $lport> form) to get killed.
583		691
584	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>
585	C<mon>, see above).	693	form) get killed with the same reason.
586		694
587	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
588	will be reported as reason C<< die => $@ >>.	696	will be reported as reason C<< die => $@ >>.
589		697
590	Transport/communication errors are reported as C<< transport_error =>	698	Transport/communication errors are reported as C<< transport_error =>
…		…
609	the package, then the package above the package and so on (e.g.	717	the package, then the package above the package and so on (e.g.
610	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	718	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
611	exists or it runs out of package names.	719	exists or it runs out of package names.
612		720
613	The init function is then called with the newly-created port as context	721	The init function is then called with the newly-created port as context
614	object (C<$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.
615		725
616	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
617	port, and in the remote init function, immediately monitor the passed	727	port, and in the remote init function, immediately monitor the passed
618	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
619	when there is a problem.	729	when there is a problem.
620		730
		731	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		732	caller before C<spawn> returns (by delaying invocation when spawn is
		733	called for the local node).
		734
621	Example: spawn a chat server port on C<$othernode>.	735	Example: spawn a chat server port on C<$othernode>.
622		736
623	# this node, executed from within a port context:	737	# this node, executed from within a port context:
624	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	738	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
625	mon $server;	739	mon $server;
…		…
639		753
640	sub _spawn {	754	sub _spawn {
641	my $port = shift;	755	my $port = shift;
642	my $init = shift;	756	my $init = shift;
643		757
		758	# rcv will create the actual port
644	local $SELF = "$NODE#$port";	759	local $SELF = "$NODE#$port";
645	eval {	760	eval {
646	&{ load_func $init }	761	&{ load_func $init }
647	};	762	};
648	_self_die if $@;	763	_self_die if $@;
…		…
683	? $action[0]()	798	? $action[0]()
684	: snd @action;	799	: snd @action;
685	};	800	};
686	}	801	}
687		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
688	=back	855	=back
689		856
690	=head1 AnyEvent::MP vs. Distributed Erlang	857	=head1 AnyEvent::MP vs. Distributed Erlang
691		858
692	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
693	== 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
694	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
695	sample:	862	sample:
696		863
697	http://www.Erlang.se/doc/programming_rules.shtml	864	http://www.erlang.se/doc/programming_rules.shtml
698	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
699	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
700	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
701		868
702	Despite the similarities, there are also some important differences:	869	Despite the similarities, there are also some important differences:
703		870
704	=over 4	871	=over 4
705		872
706	=item * Node IDs are arbitrary strings in AEMP.	873	=item * Node IDs are arbitrary strings in AEMP.
707		874
708	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
709	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
710	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.
711		879
712	=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
713	uses "local ports are like remote ports".	881	uses "local ports are like remote ports".
714		882
715	The failure modes for local ports are quite different (runtime errors	883	The failure modes for local ports are quite different (runtime errors
…		…
724	ports being the special case/exception, where transport errors cannot	892	ports being the special case/exception, where transport errors cannot
725	occur.	893	occur.
726		894
727	=item * Erlang uses processes and a mailbox, AEMP does not queue.	895	=item * Erlang uses processes and a mailbox, AEMP does not queue.
728		896
729	Erlang uses processes that selectively receive messages, and therefore	897	Erlang uses processes that selectively receive messages out of order, and
730	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
731	useful purpose. For the same reason the pattern-matching abilities of	899	no useful purpose. For the same reason the pattern-matching abilities
732	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
733	filter messages without dequeuing them.	901	filter messages without dequeuing them.
734		902
735	(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.
736		908
737	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	909	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
738		910
739	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
740	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
741	connection establishment is handled in the background.	914	establishment is handled in the background.
742		915
743	=item * Erlang suffers from silent message loss, AEMP does not.	916	=item * Erlang suffers from silent message loss, AEMP does not.
744		917
745	Erlang makes few guarantees on messages delivery - messages can get lost	918	Erlang implements few guarantees on messages delivery - messages can get
746	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,
747	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).
748		921
749	AEMP guarantees correct ordering, and the guarantee that after one message	922	AEMP guarantees (modulo hardware errors) correct ordering, and the
750	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
751	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
752	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.
753		931
754	=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.
755		933
756	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
757	known to other nodes for a completely different process, causing messages	935	process ID known to other nodes for a completely different process,
758	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.
759		938
760	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
761	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.
762		941
763	=item * Erlang uses unprotected connections, AEMP uses secure	942	=item * Erlang uses unprotected connections, AEMP uses secure
764	authentication and can use TLS.	943	authentication and can use TLS.
765		944
…		…
768		947
769	=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
770	communications.	949	communications.
771		950
772	The AEMP protocol, unlike the Erlang protocol, supports both programming	951	The AEMP protocol, unlike the Erlang protocol, supports both programming
773	language independent text-only protocols (good for debugging) and binary,	952	language independent text-only protocols (good for debugging), and binary,
774	language-specific serialisers (e.g. Storable). By default, unless TLS is	953	language-specific serialisers (e.g. Storable). By default, unless TLS is
775	used, the protocol is actually completely text-based.	954	used, the protocol is actually completely text-based.
776		955
777	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
778	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
779	protocol simple.	958	protocol simple.
780		959
781	=item * AEMP has more flexible monitoring options than Erlang.	960	=item * AEMP has more flexible monitoring options than Erlang.
782		961
783	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
784	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
785	difficult to implement. Monitoring in AEMP is more flexible than in	964	difficult to implement.
786	Erlang, as one can choose between automatic kill, exit message or callback	965
787	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.
788		968
789	=item * Erlang tries to hide remote/local connections, AEMP does not.	969	=item * Erlang tries to hide remote/local connections, AEMP does not.
790		970
791	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
792	same way as linking is (except linking is unreliable in Erlang).	972	same way as linking is (except linking is unreliable in Erlang).
…		…
814	overhead, as well as having to keep a proxy object everywhere.	994	overhead, as well as having to keep a proxy object everywhere.
815		995
816	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
817	procedures to be "valid".	997	procedures to be "valid".
818		998
819	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
820	global hash - it can't become much cheaper.	1000	code reference stored in a global hash - it can't become much cheaper.
821		1001
822	=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?
823		1003
824	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
825	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
…		…
841		1021
842	L<AnyEvent::MP::Intro> - a gentle introduction.	1022	L<AnyEvent::MP::Intro> - a gentle introduction.
843		1023
844	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1024	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
845		1025
846	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1026	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
847	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.
848		1033
849	L<AnyEvent>.	1034	L<AnyEvent>.
850		1035
851	=head1 AUTHOR	1036	=head1 AUTHOR
852		1037

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.77 by elmex, Thu Sep 3 07:57:30 2009 UTC vs.
Revision 1.119 by root, Sun Feb 26 10:29:59 2012 UTC