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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.85 by root, Tue Sep 8 01:54:13 2009 UTC vs.
Revision 1.124 by root, Sat Mar 3 11:38:43 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 but incomplete, protocol not yet final.	58	AnyEvent::MP::Global - stable API.
47
48	stay tuned.
49		59
50	=head1 DESCRIPTION	60	=head1 DESCRIPTION
51		61
52	This module (-family) implements a simple message passing framework.	62	This module (-family) implements a simple message passing framework.
53		63
…		…
68		78
69	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
70	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
71	anything was listening for them or not.	81	anything was listening for them or not.
72		82
		83	Ports are represented by (printable) strings called "port IDs".
		84
73	=item port ID - C<nodeid#portname>	85	=item port ID - C<nodeid#portname>
74		86
75	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<#>)
76	separator, and a port name (a printable string of unspecified format).	88	as separator, and a port name (a printable string of unspecified
		89	format created by AnyEvent::MP).
77		90
78	=item node	91	=item node
79		92
80	A node is a single process containing at least one port - the node port,	93	A node is a single process containing at least one port - the node port,
81	which enables nodes to manage each other remotely, and to create new	94	which enables nodes to manage each other remotely, and to create new
82	ports.	95	ports.
83		96
84	Nodes are either public (have one or more listening ports) or private	97	Nodes are either public (have one or more listening ports) or private
85	(no listening ports). Private nodes cannot talk to other private nodes	98	(no listening ports). Private nodes cannot talk to other private nodes
86	currently.	99	currently, but all nodes can talk to public nodes.
87		100
		101	Nodes is represented by (printable) strings called "node IDs".
		102
88	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>	103	=item node ID - C<[A-Za-z0-9_\-.:]*>
89		104
90	A node ID is a string that uniquely identifies the node within a	105	A node ID is a string that uniquely identifies the node within a
91	network. Depending on the configuration used, node IDs can look like a	106	network. Depending on the configuration used, node IDs can look like a
92	hostname, a hostname and a port, or a random string. AnyEvent::MP itself	107	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
93	doesn't interpret node IDs in any way.	108	doesn't interpret node IDs in any way except to uniquely identify a node.
94		109
95	=item binds - C<ip:port>	110	=item binds - C<ip:port>
96		111
97	Nodes can only talk to each other by creating some kind of connection to	112	Nodes can only talk to each other by creating some kind of connection to
98	each other. To do this, nodes should listen on one or more local transport	113	each other. To do this, nodes should listen on one or more local transport
		114	endpoints - binds.
		115
99	endpoints - binds. Currently, only standard C<ip:port> specifications can	116	Currently, only standard C<ip:port> specifications can be used, which
100	be used, which specify TCP ports to listen on.	117	specify TCP ports to listen on. So a bind is basically just a tcp socket
		118	in listening mode thta accepts conenctions form other nodes.
101		119
102	=item seed nodes	120	=item seed nodes
103		121
104	When a node starts, it knows nothing about the network. To teach the node	122	When a node starts, it knows nothing about the network it is in - it
105	about the network it first has to contact some other node within the	123	needs to connect to at least one other node that is already in the
106	network. This node is called a seed.	124	network. These other nodes are called "seed nodes".
107		125
108	Apart from the fact that other nodes know them as seed nodes and they have	126	Seed nodes themselves are not special - they are seed nodes only because
109	to have fixed listening addresses, seed nodes are perfectly normal nodes -	127	some other node I<uses> them as such, but any node can be used as seed
110	any node can function as a seed node for others.	128	node for other nodes, and eahc node cna use a different set of seed nodes.
111		129
112	In addition to discovering the network, seed nodes are also used to	130	In addition to discovering the network, seed nodes are also used to
113	maintain the network and to connect nodes that otherwise would have	131	maintain the network - all nodes using the same seed node form are part of
114	trouble connecting. They form the backbone of the AnyEvent::MP network.	132	the same network. If a network is split into multiple subnets because e.g.
		133	the network link between the parts goes down, then using the same seed
		134	nodes for all nodes ensures that eventually the subnets get merged again.
115		135
116	Seed nodes are expected to be long-running, and at least one seed node	136	Seed nodes are expected to be long-running, and at least one seed node
117	should always be available. They should also be relatively responsive - a	137	should always be available. They should also be relatively responsive - a
118	seed node that blocks for long periods will slow down everybody else.	138	seed node that blocks for long periods will slow down everybody else.
119		139
		140	For small networks, it's best if every node uses the same set of seed
		141	nodes. For large networks, it can be useful to specify "regional" seed
		142	nodes for most nodes in an area, and use all seed nodes as seed nodes for
		143	each other. What's important is that all seed nodes connections form a
		144	complete graph, so that the network cannot split into separate subnets
		145	forever.
		146
		147	Seed nodes are represented by seed IDs.
		148
120	=item seeds - C<host:port>	149	=item seed IDs - C<host:port>
121		150
122	Seeds are transport endpoint(s) (usually a hostname/IP address and a	151	Seed IDs are transport endpoint(s) (usually a hostname/IP address and a
123	TCP port) of nodes thta should be used as seed nodes.	152	TCP port) of nodes that should be used as seed nodes.
124		153
125	The nodes listening on those endpoints are expected to be long-running,	154	=item global nodes
126	and at least one of those should always be available. When nodes run out	155
127	of connections (e.g. due to a network error), they try to re-establish	156	An AEMP network needs a discovery service - nodes need to know how to
128	connections to some seednodes again to join the network.	157	connect to other nodes they only know by name. In addition, AEMP offers a
		158	distributed "group database", which maps group names to a list of strings
		159	- for example, to register worker ports.
		160
		161	A network needs at least one global node to work, and allows every node to
		162	be a global node.
		163
		164	Any node that loads the L<AnyEvent::MP::Global> module becomes a global
		165	node and tries to keep connections to all other nodes. So while it can
		166	make sense to make every node "global" in small networks, it usually makes
		167	sense to only make seed nodes into global nodes in large networks (nodes
		168	keep connections to seed nodes and global nodes, so makign them the same
		169	reduces overhead).
129		170
130	=back	171	=back
131		172
132	=head1 VARIABLES/FUNCTIONS	173	=head1 VARIABLES/FUNCTIONS
133		174
…		…
135		176
136	=cut	177	=cut
137		178
138	package AnyEvent::MP;	179	package AnyEvent::MP;
139		180
		181	use AnyEvent::MP::Config ();
140	use AnyEvent::MP::Kernel;	182	use AnyEvent::MP::Kernel;
		183	use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID);
141		184
142	use common::sense;	185	use common::sense;
143		186
144	use Carp ();	187	use Carp ();
145		188
146	use AE ();	189	use AE ();
		190	use Guard ();
147		191
148	use base "Exporter";	192	use base "Exporter";
149		193
150	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	194	our $VERSION = $AnyEvent::MP::Config::VERSION;
151		195
152	our @EXPORT = qw(	196	our @EXPORT = qw(
153	NODE $NODE *SELF node_of after	197	NODE $NODE *SELF node_of after
154	configure	198	configure
155	snd rcv mon mon_guard kil reg psub spawn	199	snd rcv mon mon_guard kil psub peval spawn cal
156	port	200	port
		201	db_set db_del db_reg
157	);	202	);
158		203
159	our $SELF;	204	our $SELF;
160		205
161	sub _self_die() {	206	sub _self_die() {
…		…
184	some other nodes in the network to discover other nodes.	229	some other nodes in the network to discover other nodes.
185		230
186	This function configures a node - it must be called exactly once (or	231	This function configures a node - it must be called exactly once (or
187	never) before calling other AnyEvent::MP functions.	232	never) before calling other AnyEvent::MP functions.
188		233
		234	The key/value pairs are basically the same ones as documented for the
		235	F<aemp> command line utility (sans the set/del prefix), with two additions:
		236
		237	=over 4
		238
		239	=item norc => $boolean (default false)
		240
		241	If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not>
		242	be consulted - all configuraiton options must be specified in the
		243	C<configure> call.
		244
		245	=item force => $boolean (default false)
		246
		247	IF true, then the values specified in the C<configure> will take
		248	precedence over any values configured via the rc file. The default is for
		249	the rc file to override any options specified in the program.
		250
		251	=back
		252
189	=over 4	253	=over 4
190		254
191	=item step 1, gathering configuration from profiles	255	=item step 1, gathering configuration from profiles
192		256
193	The function first looks up a profile in the aemp configuration (see the	257	The function first looks up a profile in the aemp configuration (see the
…		…
206	That means that the values specified in the profile have highest priority	270	That means that the values specified in the profile have highest priority
207	and the values specified directly via C<configure> have lowest priority,	271	and the values specified directly via C<configure> have lowest priority,
208	and can only be used to specify defaults.	272	and can only be used to specify defaults.
209		273
210	If the profile specifies a node ID, then this will become the node ID of	274	If the profile specifies a node ID, then this will become the node ID of
211	this process. If not, then the profile name will be used as node ID. The	275	this process. If not, then the profile name will be used as node ID, with
212	special node ID of C<anon/> will be replaced by a random node ID.	276	a slash (C</>) attached.
		277
		278	If the node ID (or profile name) ends with a slash (C</>), then a random
		279	string is appended to make it unique.
213		280
214	=item step 2, bind listener sockets	281	=item step 2, bind listener sockets
215		282
216	The next step is to look up the binds in the profile, followed by binding	283	The next step is to look up the binds in the profile, followed by binding
217	aemp protocol listeners on all binds specified (it is possible and valid	284	aemp protocol listeners on all binds specified (it is possible and valid
…		…
223	used, meaning the node will bind on a dynamically-assigned port on every	290	used, meaning the node will bind on a dynamically-assigned port on every
224	local IP address it finds.	291	local IP address it finds.
225		292
226	=item step 3, connect to seed nodes	293	=item step 3, connect to seed nodes
227		294
228	As the last step, the seeds list from the profile is passed to the	295	As the last step, the seed ID list from the profile is passed to the
229	L<AnyEvent::MP::Global> module, which will then use it to keep	296	L<AnyEvent::MP::Global> module, which will then use it to keep
230	connectivity with at least one node at any point in time.	297	connectivity with at least one node at any point in time.
231		298
232	=back	299	=back
233		300
234	Example: become a distributed node using the locla node name as profile.	301	Example: become a distributed node using the local node name as profile.
235	This should be the most common form of invocation for "daemon"-type nodes.	302	This should be the most common form of invocation for "daemon"-type nodes.
236		303
237	configure	304	configure
238		305
239	Example: become an anonymous node. This form is often used for commandline	306	Example: become an anonymous node. This form is often used for commandline
240	clients.	307	clients.
241		308
242	configure nodeid => "anon/";	309	configure nodeid => "anon/";
243		310
244	Example: configure a node using a profile called seed, which si suitable	311	Example: configure a node using a profile called seed, which is suitable
245	for a seed node as it binds on all local addresses on a fixed port (4040,	312	for a seed node as it binds on all local addresses on a fixed port (4040,
246	customary for aemp).	313	customary for aemp).
247		314
248	# use the aemp commandline utility	315	# use the aemp commandline utility
249	# aemp profile seed nodeid anon/ binds '*:4040'	316	# aemp profile seed binds '*:4040'
250		317
251	# then use it	318	# then use it
252	configure profile => "seed";	319	configure profile => "seed";
253		320
254	# or simply use aemp from the shell again:	321	# or simply use aemp from the shell again:
…		…
324	sub _kilme {	391	sub _kilme {
325	die "received message on port without callback";	392	die "received message on port without callback";
326	}	393	}
327		394
328	sub port(;&) {	395	sub port(;&) {
329	my $id = "$UNIQ." . $ID++;	396	my $id = $UNIQ . ++$ID;
330	my $port = "$NODE#$id";	397	my $port = "$NODE#$id";
331		398
332	rcv $port, shift \|\| \&_kilme;	399	rcv $port, shift \|\| \&_kilme;
333		400
334	$port	401	$port
…		…
373	msg1 => sub { ... },	440	msg1 => sub { ... },
374	...	441	...
375	;	442	;
376		443
377	Example: temporarily register a rcv callback for a tag matching some port	444	Example: temporarily register a rcv callback for a tag matching some port
378	(e.g. for a rpc reply) and unregister it after a message was received.	445	(e.g. for an rpc reply) and unregister it after a message was received.
379		446
380	rcv $port, $otherport => sub {	447	rcv $port, $otherport => sub {
381	my @reply = @_;	448	my @reply = @_;
382		449
383	rcv $SELF, $otherport;	450	rcv $SELF, $otherport;
…		…
396	if (ref $_[0]) {	463	if (ref $_[0]) {
397	if (my $self = $PORT_DATA{$portid}) {	464	if (my $self = $PORT_DATA{$portid}) {
398	"AnyEvent::MP::Port" eq ref $self	465	"AnyEvent::MP::Port" eq ref $self
399	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	466	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
400		467
401	$self->[2] = shift;	468	$self->[0] = shift;
402	} else {	469	} else {
403	my $cb = shift;	470	my $cb = shift;
404	$PORT{$portid} = sub {	471	$PORT{$portid} = sub {
405	local $SELF = $port;	472	local $SELF = $port;
406	eval { &$cb }; _self_die if $@;	473	eval { &$cb }; _self_die if $@;
407	};	474	};
408	}	475	}
409	} elsif (defined $_[0]) {	476	} elsif (defined $_[0]) {
410	my $self = $PORT_DATA{$portid} \|\|= do {	477	my $self = $PORT_DATA{$portid} \|\|= do {
411	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	478	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
412		479
413	$PORT{$portid} = sub {	480	$PORT{$portid} = sub {
414	local $SELF = $port;	481	local $SELF = $port;
415		482
416	if (my $cb = $self->[1]{$_[0]}) {	483	if (my $cb = $self->[1]{$_[0]}) {
…		…
438	}	505	}
439		506
440	$port	507	$port
441	}	508	}
442		509
		510	=item peval $port, $coderef[, @args]
		511
		512	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
		513	when the code throews an exception the C<$port> will be killed.
		514
		515	Any remaining args will be passed to the callback. Any return values will
		516	be returned to the caller.
		517
		518	This is useful when you temporarily want to execute code in the context of
		519	a port.
		520
		521	Example: create a port and run some initialisation code in it's context.
		522
		523	my $port = port { ... };
		524
		525	peval $port, sub {
		526	init
		527	or die "unable to init";
		528	};
		529
		530	=cut
		531
		532	sub peval($$) {
		533	local $SELF = shift;
		534	my $cb = shift;
		535
		536	if (wantarray) {
		537	my @res = eval { &$cb };
		538	_self_die if $@;
		539	@res
		540	} else {
		541	my $res = eval { &$cb };
		542	_self_die if $@;
		543	$res
		544	}
		545	}
		546
443	=item $closure = psub { BLOCK }	547	=item $closure = psub { BLOCK }
444		548
445	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	549	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
446	closure is executed, sets up the environment in the same way as in C<rcv>	550	closure is executed, sets up the environment in the same way as in C<rcv>
447	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.	551	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		552
		553	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		554	BLOCK }, @_ } >>.
448		555
449	This is useful when you register callbacks from C<rcv> callbacks:	556	This is useful when you register callbacks from C<rcv> callbacks:
450		557
451	rcv delayed_reply => sub {	558	rcv delayed_reply => sub {
452	my ($delay, @reply) = @_;	559	my ($delay, @reply) = @_;
…		…
525	delivered again.	632	delivered again.
526		633
527	Inter-host-connection timeouts and monitoring depend on the transport	634	Inter-host-connection timeouts and monitoring depend on the transport
528	used. The only transport currently implemented is TCP, and AnyEvent::MP	635	used. The only transport currently implemented is TCP, and AnyEvent::MP
529	relies on TCP to detect node-downs (this can take 10-15 minutes on a	636	relies on TCP to detect node-downs (this can take 10-15 minutes on a
530	non-idle connection, and usually around two hours for idle conenctions).	637	non-idle connection, and usually around two hours for idle connections).
531		638
532	This means that monitoring is good for program errors and cleaning up	639	This means that monitoring is good for program errors and cleaning up
533	stuff eventually, but they are no replacement for a timeout when you need	640	stuff eventually, but they are no replacement for a timeout when you need
534	to ensure some maximum latency.	641	to ensure some maximum latency.
535		642
…		…
567	}	674	}
568		675
569	$node->monitor ($port, $cb);	676	$node->monitor ($port, $cb);
570		677
571	defined wantarray	678	defined wantarray
572	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	679	and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) })
573	}	680	}
574		681
575	=item $guard = mon_guard $port, $ref, $ref...	682	=item $guard = mon_guard $port, $ref, $ref...
576		683
577	Monitors the given C<$port> and keeps the passed references. When the port	684	Monitors the given C<$port> and keeps the passed references. When the port
…		…
600		707
601	=item kil $port[, @reason]	708	=item kil $port[, @reason]
602		709
603	Kill the specified port with the given C<@reason>.	710	Kill the specified port with the given C<@reason>.
604		711
605	If no C<@reason> is specified, then the port is killed "normally" (ports	712	If no C<@reason> is specified, then the port is killed "normally" -
606	monitoring other ports will not necessarily die because a port dies	713	monitor callback will be invoked, but the kil will not cause linked ports
607	"normally").	714	(C<mon $mport, $lport> form) to get killed.
608		715
609	Otherwise, linked ports get killed with the same reason (second form of	716	If a C<@reason> is specified, then linked ports (C<mon $mport, $lport>
610	C<mon>, see above).	717	form) get killed with the same reason.
611		718
612	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	719	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
613	will be reported as reason C<< die => $@ >>.	720	will be reported as reason C<< die => $@ >>.
614		721
615	Transport/communication errors are reported as C<< transport_error =>	722	Transport/communication errors are reported as C<< transport_error =>
…		…
681	}	788	}
682		789
683	sub spawn(@) {	790	sub spawn(@) {
684	my ($nodeid, undef) = split /#/, shift, 2;	791	my ($nodeid, undef) = split /#/, shift, 2;
685		792
686	my $id = "$RUNIQ." . $ID++;	793	my $id = $RUNIQ . ++$ID;
687		794
688	$_[0] =~ /::/	795	$_[0] =~ /::/
689	or Carp::croak "spawn init function must be a fully-qualified name, caught";	796	or Carp::croak "spawn init function must be a fully-qualified name, caught";
690		797
691	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;	798	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
692		799
693	"$nodeid#$id"	800	"$nodeid#$id"
694	}	801	}
		802
695		803
696	=item after $timeout, @msg	804	=item after $timeout, @msg
697		805
698	=item after $timeout, $callback	806	=item after $timeout, $callback
699		807
…		…
715	? $action[0]()	823	? $action[0]()
716	: snd @action;	824	: snd @action;
717	};	825	};
718	}	826	}
719		827
		828	=item cal $port, @msg, $callback[, $timeout]
		829
		830	A simple form of RPC - sends a message to the given C<$port> with the
		831	given contents (C<@msg>), but adds a reply port to the message.
		832
		833	The reply port is created temporarily just for the purpose of receiving
		834	the reply, and will be C<kil>ed when no longer needed.
		835
		836	A reply message sent to the port is passed to the C<$callback> as-is.
		837
		838	If an optional time-out (in seconds) is given and it is not C<undef>,
		839	then the callback will be called without any arguments after the time-out
		840	elapsed and the port is C<kil>ed.
		841
		842	If no time-out is given (or it is C<undef>), then the local port will
		843	monitor the remote port instead, so it eventually gets cleaned-up.
		844
		845	Currently this function returns the temporary port, but this "feature"
		846	might go in future versions unless you can make a convincing case that
		847	this is indeed useful for something.
		848
		849	=cut
		850
		851	sub cal(@) {
		852	my $timeout = ref $_[-1] ? undef : pop;
		853	my $cb = pop;
		854
		855	my $port = port {
		856	undef $timeout;
		857	kil $SELF;
		858	&$cb;
		859	};
		860
		861	if (defined $timeout) {
		862	$timeout = AE::timer $timeout, 0, sub {
		863	undef $timeout;
		864	kil $port;
		865	$cb->();
		866	};
		867	} else {
		868	mon $_[0], sub {
		869	kil $port;
		870	$cb->();
		871	};
		872	}
		873
		874	push @_, $port;
		875	&snd;
		876
		877	$port
		878	}
		879
		880	=back
		881
		882	=head1 DISTRIBUTED DATABASE
		883
		884	AnyEvent::MP comes with a simple distributed database. The database will
		885	be mirrored asynchronously at all global nodes. Other nodes bind to one of
		886	the global nodes for their needs.
		887
		888	The database consists of a two-level hash - a hash contains a hash which
		889	contains values.
		890
		891	The top level hash key is called "family", and the second-level hash key
		892	is simply called "key".
		893
		894	The family and key must be alphanumeric ASCII strings, i.e. start
		895	with a letter and consist of letters, digits, underscores and colons
		896	(C<[A-Za-z][A-Za-z0-9_:]*>, pretty much like Perl module names.
		897
		898	As the family namespaceis global, it is recommended to prefix family names
		899	with the name of the application or module using it.
		900
		901	The values should preferably be strings, but other perl scalars should
		902	work as well (such as arrays and hashes).
		903
		904	Every database entry is owned by one node - adding the same family/key
		905	combination on multiple nodes will not cause discomfort for AnyEvent::MP,
		906	but the result might be nondeterministic, i.e. the key might have
		907	different values on different nodes.
		908
		909	=item db_set $family => $key => $value
		910
		911	Sets (or replaces) a key to the database.
		912
		913	=item db_del $family => $key
		914
		915	Deletes a key from the database.
		916
		917	=item $guard = db_reg $family => $key [=> $value]
		918
		919	Sets the key on the database and returns a guard. When the guard is
		920	destroyed, the key is deleted from the database. If C<$value> is missing,
		921	then C<undef> is used.
		922
		923	=cut
		924
720	=back	925	=back
721		926
722	=head1 AnyEvent::MP vs. Distributed Erlang	927	=head1 AnyEvent::MP vs. Distributed Erlang
723		928
724	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	929	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
725	== aemp node, Erlang process == aemp port), so many of the documents and	930	== aemp node, Erlang process == aemp port), so many of the documents and
726	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	931	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
727	sample:	932	sample:
728		933
729	http://www.Erlang.se/doc/programming_rules.shtml	934	http://www.erlang.se/doc/programming_rules.shtml
730	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	935	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
731	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6	936	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
732	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	937	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
733		938
734	Despite the similarities, there are also some important differences:	939	Despite the similarities, there are also some important differences:
735		940
736	=over 4	941	=over 4
737		942
738	=item * Node IDs are arbitrary strings in AEMP.	943	=item * Node IDs are arbitrary strings in AEMP.
739		944
740	Erlang relies on special naming and DNS to work everywhere in the same	945	Erlang relies on special naming and DNS to work everywhere in the same
741	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by	946	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
742	configuration or DNS), but will otherwise discover other odes itself.	947	configuration or DNS), and possibly the addresses of some seed nodes, but
		948	will otherwise discover other nodes (and their IDs) itself.
743		949
744	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	950	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
745	uses "local ports are like remote ports".	951	uses "local ports are like remote ports".
746		952
747	The failure modes for local ports are quite different (runtime errors	953	The failure modes for local ports are quite different (runtime errors
…		…
756	ports being the special case/exception, where transport errors cannot	962	ports being the special case/exception, where transport errors cannot
757	occur.	963	occur.
758		964
759	=item * Erlang uses processes and a mailbox, AEMP does not queue.	965	=item * Erlang uses processes and a mailbox, AEMP does not queue.
760		966
761	Erlang uses processes that selectively receive messages, and therefore	967	Erlang uses processes that selectively receive messages out of order, and
762	needs a queue. AEMP is event based, queuing messages would serve no	968	therefore needs a queue. AEMP is event based, queuing messages would serve
763	useful purpose. For the same reason the pattern-matching abilities of	969	no useful purpose. For the same reason the pattern-matching abilities
764	AnyEvent::MP are more limited, as there is little need to be able to	970	of AnyEvent::MP are more limited, as there is little need to be able to
765	filter messages without dequeuing them.	971	filter messages without dequeuing them.
766		972
767	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	973	This is not a philosophical difference, but simply stems from AnyEvent::MP
		974	being event-based, while Erlang is process-based.
		975
		976	You cna have a look at L<Coro::MP> for a more Erlang-like process model on
		977	top of AEMP and Coro threads.
768		978
769	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	979	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
770		980
771	Sending messages in Erlang is synchronous and blocks the process (and	981	Sending messages in Erlang is synchronous and blocks the process until
		982	a conenction has been established and the message sent (and so does not
772	so does not need a queue that can overflow). AEMP sends are immediate,	983	need a queue that can overflow). AEMP sends return immediately, connection
773	connection establishment is handled in the background.	984	establishment is handled in the background.
774		985
775	=item * Erlang suffers from silent message loss, AEMP does not.	986	=item * Erlang suffers from silent message loss, AEMP does not.
776		987
777	Erlang makes few guarantees on messages delivery - messages can get lost	988	Erlang implements few guarantees on messages delivery - messages can get
778	without any of the processes realising it (i.e. you send messages a, b,	989	lost without any of the processes realising it (i.e. you send messages a,
779	and c, and the other side only receives messages a and c).	990	b, and c, and the other side only receives messages a and c).
780		991
781	AEMP guarantees correct ordering, and the guarantee that after one message	992	AEMP guarantees (modulo hardware errors) correct ordering, and the
782	is lost, all following ones sent to the same port are lost as well, until	993	guarantee that after one message is lost, all following ones sent to the
783	monitoring raises an error, so there are no silent "holes" in the message	994	same port are lost as well, until monitoring raises an error, so there are
784	sequence.	995	no silent "holes" in the message sequence.
		996
		997	If you want your software to be very reliable, you have to cope with
		998	corrupted and even out-of-order messages in both Erlang and AEMP. AEMP
		999	simply tries to work better in common error cases, such as when a network
		1000	link goes down.
785		1001
786	=item * Erlang can send messages to the wrong port, AEMP does not.	1002	=item * Erlang can send messages to the wrong port, AEMP does not.
787		1003
788	In Erlang it is quite likely that a node that restarts reuses a process ID	1004	In Erlang it is quite likely that a node that restarts reuses an Erlang
789	known to other nodes for a completely different process, causing messages	1005	process ID known to other nodes for a completely different process,
790	destined for that process to end up in an unrelated process.	1006	causing messages destined for that process to end up in an unrelated
		1007	process.
791		1008
792	AEMP never reuses port IDs, so old messages or old port IDs floating	1009	AEMP does not reuse port IDs, so old messages or old port IDs floating
793	around in the network will not be sent to an unrelated port.	1010	around in the network will not be sent to an unrelated port.
794		1011
795	=item * Erlang uses unprotected connections, AEMP uses secure	1012	=item * Erlang uses unprotected connections, AEMP uses secure
796	authentication and can use TLS.	1013	authentication and can use TLS.
797		1014
…		…
800		1017
801	=item * The AEMP protocol is optimised for both text-based and binary	1018	=item * The AEMP protocol is optimised for both text-based and binary
802	communications.	1019	communications.
803		1020
804	The AEMP protocol, unlike the Erlang protocol, supports both programming	1021	The AEMP protocol, unlike the Erlang protocol, supports both programming
805	language independent text-only protocols (good for debugging) and binary,	1022	language independent text-only protocols (good for debugging), and binary,
806	language-specific serialisers (e.g. Storable). By default, unless TLS is	1023	language-specific serialisers (e.g. Storable). By default, unless TLS is
807	used, the protocol is actually completely text-based.	1024	used, the protocol is actually completely text-based.
808		1025
809	It has also been carefully designed to be implementable in other languages	1026	It has also been carefully designed to be implementable in other languages
810	with a minimum of work while gracefully degrading functionality to make the	1027	with a minimum of work while gracefully degrading functionality to make the
811	protocol simple.	1028	protocol simple.
812		1029
813	=item * AEMP has more flexible monitoring options than Erlang.	1030	=item * AEMP has more flexible monitoring options than Erlang.
814		1031
815	In Erlang, you can chose to receive I<all> exit signals as messages	1032	In Erlang, you can chose to receive I<all> exit signals as messages or
816	or I<none>, there is no in-between, so monitoring single processes is	1033	I<none>, there is no in-between, so monitoring single Erlang processes is
817	difficult to implement. Monitoring in AEMP is more flexible than in	1034	difficult to implement.
818	Erlang, as one can choose between automatic kill, exit message or callback	1035
819	on a per-process basis.	1036	Monitoring in AEMP is more flexible than in Erlang, as one can choose
		1037	between automatic kill, exit message or callback on a per-port basis.
820		1038
821	=item * Erlang tries to hide remote/local connections, AEMP does not.	1039	=item * Erlang tries to hide remote/local connections, AEMP does not.
822		1040
823	Monitoring in Erlang is not an indicator of process death/crashes, in the	1041	Monitoring in Erlang is not an indicator of process death/crashes, in the
824	same way as linking is (except linking is unreliable in Erlang).	1042	same way as linking is (except linking is unreliable in Erlang).
…		…
846	overhead, as well as having to keep a proxy object everywhere.	1064	overhead, as well as having to keep a proxy object everywhere.
847		1065
848	Strings can easily be printed, easily serialised etc. and need no special	1066	Strings can easily be printed, easily serialised etc. and need no special
849	procedures to be "valid".	1067	procedures to be "valid".
850		1068
851	And as a result, a miniport consists of a single closure stored in a	1069	And as a result, a port with just a default receiver consists of a single
852	global hash - it can't become much cheaper.	1070	code reference stored in a global hash - it can't become much cheaper.
853		1071
854	=item Why favour JSON, why not a real serialising format such as Storable?	1072	=item Why favour JSON, why not a real serialising format such as Storable?
855		1073
856	In fact, any AnyEvent::MP node will happily accept Storable as framing	1074	In fact, any AnyEvent::MP node will happily accept Storable as framing
857	format, but currently there is no way to make a node use Storable by	1075	format, but currently there is no way to make a node use Storable by
…		…
873		1091
874	L<AnyEvent::MP::Intro> - a gentle introduction.	1092	L<AnyEvent::MP::Intro> - a gentle introduction.
875		1093
876	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1094	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
877		1095
878	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1096	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
879	your applications.	1097	your applications.
		1098
		1099	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
880		1100
881	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from	1101	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
882	all nodes.	1102	all nodes.
883		1103
884	L<AnyEvent>.	1104	L<AnyEvent>.

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.85 by root, Tue Sep 8 01:54:13 2009 UTC vs. Revision 1.124 by root, Sat Mar 3 11:38:43 2012 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.85 by root, Tue Sep 8 01:54:13 2009 UTC vs.
Revision 1.124 by root, Sat Mar 3 11:38:43 2012 UTC