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

Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.77 by elmex, Thu Sep 3 07:57:30 2009 UTC vs.
Revision 1.121 by root, Tue Feb 28 18:37:24 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
…		…
121		175
122	=cut	176	=cut
123		177
124	package AnyEvent::MP;	178	package AnyEvent::MP;
125		179
		180	use AnyEvent::MP::Config ();
126	use AnyEvent::MP::Kernel;	181	use AnyEvent::MP::Kernel;
		182	use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID);
127		183
128	use common::sense;	184	use common::sense;
129		185
130	use Carp ();	186	use Carp ();
131		187
132	use AE ();	188	use AE ();
133		189
134	use base "Exporter";	190	use base "Exporter";
135		191
136	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	192	our $VERSION = $AnyEvent::MP::Config::VERSION;
137		193
138	our @EXPORT = qw(	194	our @EXPORT = qw(
139	NODE $NODE *SELF node_of after	195	NODE $NODE *SELF node_of after
140	configure	196	configure
141	snd rcv mon mon_guard kil reg psub spawn	197	snd rcv mon mon_guard kil psub peval spawn cal
142	port	198	port
143	);	199	);
144		200
145	our $SELF;	201	our $SELF;
146		202
…		…
158		214
159	=item $nodeid = node_of $port	215	=item $nodeid = node_of $port
160		216
161	Extracts and returns the node ID from a port ID or a node ID.	217	Extracts and returns the node ID from a port ID or a node ID.
162		218
		219	=item configure $profile, key => value...
		220
163	=item configure key => value...	221	=item configure key => value...
164		222
165	Before a node can talk to other nodes on the network (i.e. enter	223	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	224	"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	225	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.	226	some other nodes in the network to discover other nodes.
169		227
170	This function configures a node - it must be called exactly once (or	228	This function configures a node - it must be called exactly once (or
171	never) before calling other AnyEvent::MP functions.	229	never) before calling other AnyEvent::MP functions.
172		230
		231	The key/value pairs are basically the same ones as documented for the
		232	F<aemp> command line utility (sans the set/del prefix), with two additions:
		233
		234	=over 4
		235
		236	=item norc => $boolean (default false)
		237
		238	If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not>
		239	be consulted - all configuraiton options must be specified in the
		240	C<configure> call.
		241
		242	=item force => $boolean (default false)
		243
		244	IF true, then the values specified in the C<configure> will take
		245	precedence over any values configured via the rc file. The default is for
		246	the rc file to override any options specified in the program.
		247
		248	=back
		249
173	=over 4	250	=over 4
174		251
175	=item step 1, gathering configuration from profiles	252	=item step 1, gathering configuration from profiles
176		253
177	The function first looks up a profile in the aemp configuration (see the	254	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	255	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	256	named C<profile> parameter or can simply be the first parameter). If it is
180	-n>) will be used as profile name.	257	missing, then the nodename (F<uname -n>) will be used as profile name.
181		258
182	The profile data is then gathered as follows:	259	The profile data is then gathered as follows:
183		260
184	First, all remaining key => value pairs (all of which are conveniently	261	First, all remaining key => value pairs (all of which are conveniently
185	undocumented at the moment) will be interpreted as configuration	262	undocumented at the moment) will be interpreted as configuration
…		…
207	used, meaning the node will bind on a dynamically-assigned port on every	284	used, meaning the node will bind on a dynamically-assigned port on every
208	local IP address it finds.	285	local IP address it finds.
209		286
210	=item step 3, connect to seed nodes	287	=item step 3, connect to seed nodes
211		288
212	As the last step, the seeds list from the profile is passed to the	289	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	290	L<AnyEvent::MP::Global> module, which will then use it to keep
214	connectivity with at least one node at any point in time.	291	connectivity with at least one node at any point in time.
215		292
216	=back	293	=back
217		294
218	Example: become a distributed node using the locla node name as profile.	295	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.	296	This should be the most common form of invocation for "daemon"-type nodes.
220		297
221	configure	298	configure
222		299
223	Example: become an anonymous node. This form is often used for commandline	300	Example: become an anonymous node. This form is often used for commandline
224	clients.	301	clients.
225		302
226	configure nodeid => "anon/";	303	configure nodeid => "anon/";
227		304
228	Example: configure a node using a profile called seed, which si suitable	305	Example: configure a node using a profile called seed, which is suitable
229	for a seed node as it binds on all local addresses on a fixed port (4040,	306	for a seed node as it binds on all local addresses on a fixed port (4040,
230	customary for aemp).	307	customary for aemp).
231		308
232	# use the aemp commandline utility	309	# use the aemp commandline utility
233	# aemp profile seed nodeid anon/ binds '*:4040'	310	# aemp profile seed nodeid anon/ binds '*:4040'
…		…
308	sub _kilme {	385	sub _kilme {
309	die "received message on port without callback";	386	die "received message on port without callback";
310	}	387	}
311		388
312	sub port(;&) {	389	sub port(;&) {
313	my $id = "$UNIQ." . $ID++;	390	my $id = "$UNIQ." . ++$ID;
314	my $port = "$NODE#$id";	391	my $port = "$NODE#$id";
315		392
316	rcv $port, shift \|\| \&_kilme;	393	rcv $port, shift \|\| \&_kilme;
317		394
318	$port	395	$port
…		…
357	msg1 => sub { ... },	434	msg1 => sub { ... },
358	...	435	...
359	;	436	;
360		437
361	Example: temporarily register a rcv callback for a tag matching some port	438	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.	439	(e.g. for an rpc reply) and unregister it after a message was received.
363		440
364	rcv $port, $otherport => sub {	441	rcv $port, $otherport => sub {
365	my @reply = @_;	442	my @reply = @_;
366		443
367	rcv $SELF, $otherport;	444	rcv $SELF, $otherport;
…		…
380	if (ref $_[0]) {	457	if (ref $_[0]) {
381	if (my $self = $PORT_DATA{$portid}) {	458	if (my $self = $PORT_DATA{$portid}) {
382	"AnyEvent::MP::Port" eq ref $self	459	"AnyEvent::MP::Port" eq ref $self
383	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	460	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
384		461
385	$self->[2] = shift;	462	$self->[0] = shift;
386	} else {	463	} else {
387	my $cb = shift;	464	my $cb = shift;
388	$PORT{$portid} = sub {	465	$PORT{$portid} = sub {
389	local $SELF = $port;	466	local $SELF = $port;
390	eval { &$cb }; _self_die if $@;	467	eval { &$cb }; _self_die if $@;
391	};	468	};
392	}	469	}
393	} elsif (defined $_[0]) {	470	} elsif (defined $_[0]) {
394	my $self = $PORT_DATA{$portid} \|\|= do {	471	my $self = $PORT_DATA{$portid} \|\|= do {
395	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	472	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
396		473
397	$PORT{$portid} = sub {	474	$PORT{$portid} = sub {
398	local $SELF = $port;	475	local $SELF = $port;
399		476
400	if (my $cb = $self->[1]{$_[0]}) {	477	if (my $cb = $self->[1]{$_[0]}) {
…		…
422	}	499	}
423		500
424	$port	501	$port
425	}	502	}
426		503
		504	=item peval $port, $coderef[, @args]
		505
		506	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
		507	when the code throews an exception the C<$port> will be killed.
		508
		509	Any remaining args will be passed to the callback. Any return values will
		510	be returned to the caller.
		511
		512	This is useful when you temporarily want to execute code in the context of
		513	a port.
		514
		515	Example: create a port and run some initialisation code in it's context.
		516
		517	my $port = port { ... };
		518
		519	peval $port, sub {
		520	init
		521	or die "unable to init";
		522	};
		523
		524	=cut
		525
		526	sub peval($$) {
		527	local $SELF = shift;
		528	my $cb = shift;
		529
		530	if (wantarray) {
		531	my @res = eval { &$cb };
		532	_self_die if $@;
		533	@res
		534	} else {
		535	my $res = eval { &$cb };
		536	_self_die if $@;
		537	$res
		538	}
		539	}
		540
427	=item $closure = psub { BLOCK }	541	=item $closure = psub { BLOCK }
428		542
429	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	543	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>	544	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.	545	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		546
		547	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		548	BLOCK }, @_ } >>.
432		549
433	This is useful when you register callbacks from C<rcv> callbacks:	550	This is useful when you register callbacks from C<rcv> callbacks:
434		551
435	rcv delayed_reply => sub {	552	rcv delayed_reply => sub {
436	my ($delay, @reply) = @_;	553	my ($delay, @reply) = @_;
…		…
472		589
473	Monitor the given port and do something when the port is killed or	590	Monitor the given port and do something when the port is killed or
474	messages to it were lost, and optionally return a guard that can be used	591	messages to it were lost, and optionally return a guard that can be used
475	to stop monitoring again.	592	to stop monitoring again.
476		593
		594	In the first form (callback), the callback is simply called with any
		595	number of C<@reason> elements (no @reason means that the port was deleted
		596	"normally"). Note also that I<< the callback B<must> never die >>, so use
		597	C<eval> if unsure.
		598
		599	In the second form (another port given), the other port (C<$rcvport>)
		600	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
		601	"normal" kils nothing happens, while under all other conditions, the other
		602	port is killed with the same reason.
		603
		604	The third form (kill self) is the same as the second form, except that
		605	C<$rvport> defaults to C<$SELF>.
		606
		607	In the last form (message), a message of the form C<@msg, @reason> will be
		608	C<snd>.
		609
		610	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		611	alert was raised), they are removed and will not trigger again.
		612
		613	As a rule of thumb, monitoring requests should always monitor a port from
		614	a local port (or callback). The reason is that kill messages might get
		615	lost, just like any other message. Another less obvious reason is that
		616	even monitoring requests can get lost (for example, when the connection
		617	to the other node goes down permanently). When monitoring a port locally
		618	these problems do not exist.
		619
477	C<mon> effectively guarantees that, in the absence of hardware failures,	620	C<mon> effectively guarantees that, in the absence of hardware failures,
478	after starting the monitor, either all messages sent to the port will	621	after starting the monitor, either all messages sent to the port will
479	arrive, or the monitoring action will be invoked after possible message	622	arrive, or the monitoring action will be invoked after possible message
480	loss has been detected. No messages will be lost "in between" (after	623	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	624	the first lost message no further messages will be received by the
482	port). After the monitoring action was invoked, further messages might get	625	port). After the monitoring action was invoked, further messages might get
483	delivered again.	626	delivered again.
484		627
485	Note that monitoring-actions are one-shot: once messages are lost (and a	628	Inter-host-connection timeouts and monitoring depend on the transport
486	monitoring alert was raised), they are removed and will not trigger again.	629	used. The only transport currently implemented is TCP, and AnyEvent::MP
		630	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		631	non-idle connection, and usually around two hours for idle connections).
487		632
488	In the first form (callback), the callback is simply called with any	633	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	634	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	635	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<$SELF>.
500
501	In the last form (message), a message of the form C<@msg, @reason> will be
502	C<snd>.
503
504	As a rule of thumb, monitoring requests should always monitor a port from
505	a local port (or callback). The reason is that kill messages might get
506	lost, just like any other message. Another less obvious reason is that
507	even monitoring requests can get lost (for example, when the connection
508	to the other node goes down permanently). When monitoring a port locally
509	these problems do not exist.
510		636
511	Example: call a given callback when C<$port> is killed.	637	Example: call a given callback when C<$port> is killed.
512		638
513	mon $port, sub { warn "port died because of <@_>\n" };	639	mon $port, sub { warn "port died because of <@_>\n" };
514		640
…		…
542	}	668	}
543		669
544	$node->monitor ($port, $cb);	670	$node->monitor ($port, $cb);
545		671
546	defined wantarray	672	defined wantarray
547	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	673	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
548	}	674	}
549		675
550	=item $guard = mon_guard $port, $ref, $ref...	676	=item $guard = mon_guard $port, $ref, $ref...
551		677
552	Monitors the given C<$port> and keeps the passed references. When the port	678	Monitors the given C<$port> and keeps the passed references. When the port
…		…
575		701
576	=item kil $port[, @reason]	702	=item kil $port[, @reason]
577		703
578	Kill the specified port with the given C<@reason>.	704	Kill the specified port with the given C<@reason>.
579		705
580	If no C<@reason> is specified, then the port is killed "normally" (ports	706	If no C<@reason> is specified, then the port is killed "normally" -
581	monitoring other ports will not necessarily die because a port dies	707	monitor callback will be invoked, but the kil will not cause linked ports
582	"normally").	708	(C<mon $mport, $lport> form) to get killed.
583		709
584	Otherwise, linked ports get killed with the same reason (second form of	710	If a C<@reason> is specified, then linked ports (C<mon $mport, $lport>
585	C<mon>, see above).	711	form) get killed with the same reason.
586		712
587	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	713	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
588	will be reported as reason C<< die => $@ >>.	714	will be reported as reason C<< die => $@ >>.
589		715
590	Transport/communication errors are reported as C<< transport_error =>	716	Transport/communication errors are reported as C<< transport_error =>
…		…
609	the package, then the package above the package and so on (e.g.	735	the package, then the package above the package and so on (e.g.
610	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	736	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
611	exists or it runs out of package names.	737	exists or it runs out of package names.
612		738
613	The init function is then called with the newly-created port as context	739	The init function is then called with the newly-created port as context
614	object (C<$SELF>) and the C<@initdata> values as arguments.	740	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		741	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		742	the port might not get created.
615		743
616	A common idiom is to pass a local port, immediately monitor the spawned	744	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	745	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	746	local port. This two-way monitoring ensures that both ports get cleaned up
619	when there is a problem.	747	when there is a problem.
620		748
		749	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		750	caller before C<spawn> returns (by delaying invocation when spawn is
		751	called for the local node).
		752
621	Example: spawn a chat server port on C<$othernode>.	753	Example: spawn a chat server port on C<$othernode>.
622		754
623	# this node, executed from within a port context:	755	# this node, executed from within a port context:
624	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	756	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
625	mon $server;	757	mon $server;
…		…
639		771
640	sub _spawn {	772	sub _spawn {
641	my $port = shift;	773	my $port = shift;
642	my $init = shift;	774	my $init = shift;
643		775
		776	# rcv will create the actual port
644	local $SELF = "$NODE#$port";	777	local $SELF = "$NODE#$port";
645	eval {	778	eval {
646	&{ load_func $init }	779	&{ load_func $init }
647	};	780	};
648	_self_die if $@;	781	_self_die if $@;
649	}	782	}
650		783
651	sub spawn(@) {	784	sub spawn(@) {
652	my ($nodeid, undef) = split /#/, shift, 2;	785	my ($nodeid, undef) = split /#/, shift, 2;
653		786
654	my $id = "$RUNIQ." . $ID++;	787	my $id = "$RUNIQ." . ++$ID;
655		788
656	$_[0] =~ /::/	789	$_[0] =~ /::/
657	or Carp::croak "spawn init function must be a fully-qualified name, caught";	790	or Carp::croak "spawn init function must be a fully-qualified name, caught";
658		791
659	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;	792	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
660		793
661	"$nodeid#$id"	794	"$nodeid#$id"
662	}	795	}
		796
663		797
664	=item after $timeout, @msg	798	=item after $timeout, @msg
665		799
666	=item after $timeout, $callback	800	=item after $timeout, $callback
667		801
…		…
683	? $action[0]()	817	? $action[0]()
684	: snd @action;	818	: snd @action;
685	};	819	};
686	}	820	}
687		821
		822	=item cal $port, @msg, $callback[, $timeout]
		823
		824	A simple form of RPC - sends a message to the given C<$port> with the
		825	given contents (C<@msg>), but adds a reply port to the message.
		826
		827	The reply port is created temporarily just for the purpose of receiving
		828	the reply, and will be C<kil>ed when no longer needed.
		829
		830	A reply message sent to the port is passed to the C<$callback> as-is.
		831
		832	If an optional time-out (in seconds) is given and it is not C<undef>,
		833	then the callback will be called without any arguments after the time-out
		834	elapsed and the port is C<kil>ed.
		835
		836	If no time-out is given (or it is C<undef>), then the local port will
		837	monitor the remote port instead, so it eventually gets cleaned-up.
		838
		839	Currently this function returns the temporary port, but this "feature"
		840	might go in future versions unless you can make a convincing case that
		841	this is indeed useful for something.
		842
		843	=cut
		844
		845	sub cal(@) {
		846	my $timeout = ref $_[-1] ? undef : pop;
		847	my $cb = pop;
		848
		849	my $port = port {
		850	undef $timeout;
		851	kil $SELF;
		852	&$cb;
		853	};
		854
		855	if (defined $timeout) {
		856	$timeout = AE::timer $timeout, 0, sub {
		857	undef $timeout;
		858	kil $port;
		859	$cb->();
		860	};
		861	} else {
		862	mon $_[0], sub {
		863	kil $port;
		864	$cb->();
		865	};
		866	}
		867
		868	push @_, $port;
		869	&snd;
		870
		871	$port
		872	}
		873
688	=back	874	=back
689		875
690	=head1 AnyEvent::MP vs. Distributed Erlang	876	=head1 AnyEvent::MP vs. Distributed Erlang
691		877
692	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	878	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	879	== 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	880	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
695	sample:	881	sample:
696		882
697	http://www.Erlang.se/doc/programming_rules.shtml	883	http://www.erlang.se/doc/programming_rules.shtml
698	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	884	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	885	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	886	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
701		887
702	Despite the similarities, there are also some important differences:	888	Despite the similarities, there are also some important differences:
703		889
704	=over 4	890	=over 4
705		891
706	=item * Node IDs are arbitrary strings in AEMP.	892	=item * Node IDs are arbitrary strings in AEMP.
707		893
708	Erlang relies on special naming and DNS to work everywhere in the same	894	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	895	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.	896	configuration or DNS), and possibly the addresses of some seed nodes, but
		897	will otherwise discover other nodes (and their IDs) itself.
711		898
712	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	899	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
713	uses "local ports are like remote ports".	900	uses "local ports are like remote ports".
714		901
715	The failure modes for local ports are quite different (runtime errors	902	The failure modes for local ports are quite different (runtime errors
…		…
724	ports being the special case/exception, where transport errors cannot	911	ports being the special case/exception, where transport errors cannot
725	occur.	912	occur.
726		913
727	=item * Erlang uses processes and a mailbox, AEMP does not queue.	914	=item * Erlang uses processes and a mailbox, AEMP does not queue.
728		915
729	Erlang uses processes that selectively receive messages, and therefore	916	Erlang uses processes that selectively receive messages out of order, and
730	needs a queue. AEMP is event based, queuing messages would serve no	917	therefore needs a queue. AEMP is event based, queuing messages would serve
731	useful purpose. For the same reason the pattern-matching abilities of	918	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	919	of AnyEvent::MP are more limited, as there is little need to be able to
733	filter messages without dequeuing them.	920	filter messages without dequeuing them.
734		921
735	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	922	This is not a philosophical difference, but simply stems from AnyEvent::MP
		923	being event-based, while Erlang is process-based.
		924
		925	You cna have a look at L<Coro::MP> for a more Erlang-like process model on
		926	top of AEMP and Coro threads.
736		927
737	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	928	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
738		929
739	Sending messages in Erlang is synchronous and blocks the process (and	930	Sending messages in Erlang is synchronous and blocks the process until
		931	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,	932	need a queue that can overflow). AEMP sends return immediately, connection
741	connection establishment is handled in the background.	933	establishment is handled in the background.
742		934
743	=item * Erlang suffers from silent message loss, AEMP does not.	935	=item * Erlang suffers from silent message loss, AEMP does not.
744		936
745	Erlang makes few guarantees on messages delivery - messages can get lost	937	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,	938	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).	939	b, and c, and the other side only receives messages a and c).
748		940
749	AEMP guarantees correct ordering, and the guarantee that after one message	941	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	942	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	943	same port are lost as well, until monitoring raises an error, so there are
752	sequence.	944	no silent "holes" in the message sequence.
		945
		946	If you want your software to be very reliable, you have to cope with
		947	corrupted and even out-of-order messages in both Erlang and AEMP. AEMP
		948	simply tries to work better in common error cases, such as when a network
		949	link goes down.
753		950
754	=item * Erlang can send messages to the wrong port, AEMP does not.	951	=item * Erlang can send messages to the wrong port, AEMP does not.
755		952
756	In Erlang it is quite likely that a node that restarts reuses a process ID	953	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	954	process ID known to other nodes for a completely different process,
758	destined for that process to end up in an unrelated process.	955	causing messages destined for that process to end up in an unrelated
		956	process.
759		957
760	AEMP never reuses port IDs, so old messages or old port IDs floating	958	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.	959	around in the network will not be sent to an unrelated port.
762		960
763	=item * Erlang uses unprotected connections, AEMP uses secure	961	=item * Erlang uses unprotected connections, AEMP uses secure
764	authentication and can use TLS.	962	authentication and can use TLS.
765		963
…		…
768		966
769	=item * The AEMP protocol is optimised for both text-based and binary	967	=item * The AEMP protocol is optimised for both text-based and binary
770	communications.	968	communications.
771		969
772	The AEMP protocol, unlike the Erlang protocol, supports both programming	970	The AEMP protocol, unlike the Erlang protocol, supports both programming
773	language independent text-only protocols (good for debugging) and binary,	971	language independent text-only protocols (good for debugging), and binary,
774	language-specific serialisers (e.g. Storable). By default, unless TLS is	972	language-specific serialisers (e.g. Storable). By default, unless TLS is
775	used, the protocol is actually completely text-based.	973	used, the protocol is actually completely text-based.
776		974
777	It has also been carefully designed to be implementable in other languages	975	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	976	with a minimum of work while gracefully degrading functionality to make the
779	protocol simple.	977	protocol simple.
780		978
781	=item * AEMP has more flexible monitoring options than Erlang.	979	=item * AEMP has more flexible monitoring options than Erlang.
782		980
783	In Erlang, you can chose to receive I<all> exit signals as messages	981	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	982	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	983	difficult to implement.
786	Erlang, as one can choose between automatic kill, exit message or callback	984
787	on a per-process basis.	985	Monitoring in AEMP is more flexible than in Erlang, as one can choose
		986	between automatic kill, exit message or callback on a per-port basis.
788		987
789	=item * Erlang tries to hide remote/local connections, AEMP does not.	988	=item * Erlang tries to hide remote/local connections, AEMP does not.
790		989
791	Monitoring in Erlang is not an indicator of process death/crashes, in the	990	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).	991	same way as linking is (except linking is unreliable in Erlang).
…		…
814	overhead, as well as having to keep a proxy object everywhere.	1013	overhead, as well as having to keep a proxy object everywhere.
815		1014
816	Strings can easily be printed, easily serialised etc. and need no special	1015	Strings can easily be printed, easily serialised etc. and need no special
817	procedures to be "valid".	1016	procedures to be "valid".
818		1017
819	And as a result, a miniport consists of a single closure stored in a	1018	And as a result, a port with just a default receiver consists of a single
820	global hash - it can't become much cheaper.	1019	code reference stored in a global hash - it can't become much cheaper.
821		1020
822	=item Why favour JSON, why not a real serialising format such as Storable?	1021	=item Why favour JSON, why not a real serialising format such as Storable?
823		1022
824	In fact, any AnyEvent::MP node will happily accept Storable as framing	1023	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	1024	format, but currently there is no way to make a node use Storable by
…		…
841		1040
842	L<AnyEvent::MP::Intro> - a gentle introduction.	1041	L<AnyEvent::MP::Intro> - a gentle introduction.
843		1042
844	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1043	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
845		1044
846	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1045	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
847	your applications.	1046	your applications.
		1047
		1048	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
		1049
		1050	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		1051	all nodes.
848		1052
849	L<AnyEvent>.	1053	L<AnyEvent>.
850		1054
851	=head1 AUTHOR	1055	=head1 AUTHOR
852		1056

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Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.77 by elmex, Thu Sep 3 07:57:30 2009 UTC vs.
Revision 1.121 by root, Tue Feb 28 18:37:24 2012 UTC