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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.86 by root, Wed Sep 9 01:47:01 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 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<#>) as
76	separator, and a port name (a printable string of unspecified format).	88	separator, and a port name (a printable string of unspecified format).
77		89
…		…
81	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
82	ports.	94	ports.
83		95
84	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
85	(no listening ports). Private nodes cannot talk to other private nodes	97	(no listening ports). Private nodes cannot talk to other private nodes
86	currently.	98	currently, but all nodes can talk to public nodes.
87		99
		100	Nodes is represented by (printable) strings called "node IDs".
		101
88	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>	102	=item node ID - C<[A-Za-z0-9_\-.:]*>
89		103
90	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
91	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
92	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
93	doesn't interpret node IDs in any way.	107	doesn't interpret node IDs in any way except to uniquely identify a node.
94		108
95	=item binds - C<ip:port>	109	=item binds - C<ip:port>
96		110
97	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
98	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
99	endpoints - binds. Currently, only standard C<ip:port> specifications can	115	Currently, only standard C<ip:port> specifications can be used, which
100	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.
101		118
102	=item seed nodes	119	=item seed nodes
103		120
104	When a node starts, it knows nothing about the network. To teach the node	121	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	122	needs to connect to at least one other node that is already in the
106	network. This node is called a seed.	123	network. These other nodes are called "seed nodes".
107		124
108	Apart from the fact that other nodes know them as seed nodes and they have	125	Seed nodes themselves are not special - they are seed nodes only because
109	to have fixed listening addresses, seed nodes are perfectly normal nodes -	126	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.	127	node for other nodes, and eahc node cna use a different set of seed nodes.
111		128
112	In addition to discovering the network, seed nodes are also used to	129	In addition to discovering the network, seed nodes are also used to
113	maintain the network and to connect nodes that otherwise would have	130	maintain the network - all nodes using the same seed node form are part of
114	trouble connecting. They form the backbone of an AnyEvent::MP network.	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.
115		134
116	Seed nodes are expected to be long-running, and at least one seed node	135	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	136	should always be available. They should also be relatively responsive - a
118	seed node that blocks for long periods will slow down everybody else.	137	seed node that blocks for long periods will slow down everybody else.
119		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
120	=item seeds - C<host:port>	148	=item seed IDs - C<host:port>
121		149
122	Seeds are transport endpoint(s) (usually a hostname/IP address and a	150	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.	151	TCP port) of nodes that should be used as seed nodes.
124		152
125	The nodes listening on those endpoints are expected to be long-running,	153	=item global nodes
126	and at least one of those should always be available. When nodes run out	154
127	of connections (e.g. due to a network error), they try to re-establish	155	An AEMP network needs a discovery service - nodes need to know how to
128	connections to some seednodes again to join the network.	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).
129		169
130	=back	170	=back
131		171
132	=head1 VARIABLES/FUNCTIONS	172	=head1 VARIABLES/FUNCTIONS
133		173
…		…
135		175
136	=cut	176	=cut
137		177
138	package AnyEvent::MP;	178	package AnyEvent::MP;
139		179
		180	use AnyEvent::MP::Config ();
140	use AnyEvent::MP::Kernel;	181	use AnyEvent::MP::Kernel;
		182	use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID);
141		183
142	use common::sense;	184	use common::sense;
143		185
144	use Carp ();	186	use Carp ();
145		187
146	use AE ();	188	use AE ();
147		189
148	use base "Exporter";	190	use base "Exporter";
149		191
150	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	192	our $VERSION = $AnyEvent::MP::Config::VERSION;
151		193
152	our @EXPORT = qw(	194	our @EXPORT = qw(
153	NODE $NODE *SELF node_of after	195	NODE $NODE *SELF node_of after
154	configure	196	configure
155	snd rcv mon mon_guard kil reg psub spawn	197	snd rcv mon mon_guard kil psub peval spawn cal
156	port	198	port
157	);	199	);
158		200
159	our $SELF;	201	our $SELF;
160		202
…		…
183	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
184	some other nodes in the network to discover other nodes.	226	some other nodes in the network to discover other nodes.
185		227
186	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
187	never) before calling other AnyEvent::MP functions.	229	never) before calling other AnyEvent::MP functions.
		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
188		249
189	=over 4	250	=over 4
190		251
191	=item step 1, gathering configuration from profiles	252	=item step 1, gathering configuration from profiles
192		253
…		…
223	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
224	local IP address it finds.	285	local IP address it finds.
225		286
226	=item step 3, connect to seed nodes	287	=item step 3, connect to seed nodes
227		288
228	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
229	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
230	connectivity with at least one node at any point in time.	291	connectivity with at least one node at any point in time.
231		292
232	=back	293	=back
233		294
234	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.
235	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.
236		297
237	configure	298	configure
238		299
239	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
240	clients.	301	clients.
241		302
242	configure nodeid => "anon/";	303	configure nodeid => "anon/";
243		304
244	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
245	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,
246	customary for aemp).	307	customary for aemp).
247		308
248	# use the aemp commandline utility	309	# use the aemp commandline utility
249	# aemp profile seed nodeid anon/ binds '*:4040'	310	# aemp profile seed nodeid anon/ binds '*:4040'
…		…
324	sub _kilme {	385	sub _kilme {
325	die "received message on port without callback";	386	die "received message on port without callback";
326	}	387	}
327		388
328	sub port(;&) {	389	sub port(;&) {
329	my $id = "$UNIQ." . $ID++;	390	my $id = "$UNIQ." . ++$ID;
330	my $port = "$NODE#$id";	391	my $port = "$NODE#$id";
331		392
332	rcv $port, shift \|\| \&_kilme;	393	rcv $port, shift \|\| \&_kilme;
333		394
334	$port	395	$port
…		…
373	msg1 => sub { ... },	434	msg1 => sub { ... },
374	...	435	...
375	;	436	;
376		437
377	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
378	(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.
379		440
380	rcv $port, $otherport => sub {	441	rcv $port, $otherport => sub {
381	my @reply = @_;	442	my @reply = @_;
382		443
383	rcv $SELF, $otherport;	444	rcv $SELF, $otherport;
…		…
396	if (ref $_[0]) {	457	if (ref $_[0]) {
397	if (my $self = $PORT_DATA{$portid}) {	458	if (my $self = $PORT_DATA{$portid}) {
398	"AnyEvent::MP::Port" eq ref $self	459	"AnyEvent::MP::Port" eq ref $self
399	or Carp::croak "$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";
400		461
401	$self->[2] = shift;	462	$self->[0] = shift;
402	} else {	463	} else {
403	my $cb = shift;	464	my $cb = shift;
404	$PORT{$portid} = sub {	465	$PORT{$portid} = sub {
405	local $SELF = $port;	466	local $SELF = $port;
406	eval { &$cb }; _self_die if $@;	467	eval { &$cb }; _self_die if $@;
407	};	468	};
408	}	469	}
409	} elsif (defined $_[0]) {	470	} elsif (defined $_[0]) {
410	my $self = $PORT_DATA{$portid} \|\|= do {	471	my $self = $PORT_DATA{$portid} \|\|= do {
411	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	472	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
412		473
413	$PORT{$portid} = sub {	474	$PORT{$portid} = sub {
414	local $SELF = $port;	475	local $SELF = $port;
415		476
416	if (my $cb = $self->[1]{$_[0]}) {	477	if (my $cb = $self->[1]{$_[0]}) {
…		…
438	}	499	}
439		500
440	$port	501	$port
441	}	502	}
442		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
443	=item $closure = psub { BLOCK }	541	=item $closure = psub { BLOCK }
444		542
445	Remembers C<$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
446	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>
447	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 $SELF, sub {
		548	BLOCK }, @_ } >>.
448		549
449	This is useful when you register callbacks from C<rcv> callbacks:	550	This is useful when you register callbacks from C<rcv> callbacks:
450		551
451	rcv delayed_reply => sub {	552	rcv delayed_reply => sub {
452	my ($delay, @reply) = @_;	553	my ($delay, @reply) = @_;
…		…
525	delivered again.	626	delivered again.
526		627
527	Inter-host-connection timeouts and monitoring depend on the transport	628	Inter-host-connection timeouts and monitoring depend on the transport
528	used. The only transport currently implemented is TCP, and AnyEvent::MP	629	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	630	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).	631	non-idle connection, and usually around two hours for idle connections).
531		632
532	This means that monitoring is good for program errors and cleaning up	633	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	634	stuff eventually, but they are no replacement for a timeout when you need
534	to ensure some maximum latency.	635	to ensure some maximum latency.
535		636
…		…
567	}	668	}
568		669
569	$node->monitor ($port, $cb);	670	$node->monitor ($port, $cb);
570		671
571	defined wantarray	672	defined wantarray
572	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	673	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
573	}	674	}
574		675
575	=item $guard = mon_guard $port, $ref, $ref...	676	=item $guard = mon_guard $port, $ref, $ref...
576		677
577	Monitors the given C<$port> and keeps the passed references. When the port	678	Monitors the given C<$port> and keeps the passed references. When the port
…		…
600		701
601	=item kil $port[, @reason]	702	=item kil $port[, @reason]
602		703
603	Kill the specified port with the given C<@reason>.	704	Kill the specified port with the given C<@reason>.
604		705
605	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" -
606	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
607	"normally").	708	(C<mon $mport, $lport> form) to get killed.
608		709
609	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>
610	C<mon>, see above).	711	form) get killed with the same reason.
611		712
612	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
613	will be reported as reason C<< die => $@ >>.	714	will be reported as reason C<< die => $@ >>.
614		715
615	Transport/communication errors are reported as C<< transport_error =>	716	Transport/communication errors are reported as C<< transport_error =>
…		…
681	}	782	}
682		783
683	sub spawn(@) {	784	sub spawn(@) {
684	my ($nodeid, undef) = split /#/, shift, 2;	785	my ($nodeid, undef) = split /#/, shift, 2;
685		786
686	my $id = "$RUNIQ." . $ID++;	787	my $id = "$RUNIQ." . ++$ID;
687		788
688	$_[0] =~ /::/	789	$_[0] =~ /::/
689	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";
690		791
691	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;	792	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
692		793
693	"$nodeid#$id"	794	"$nodeid#$id"
694	}	795	}
		796
695		797
696	=item after $timeout, @msg	798	=item after $timeout, @msg
697		799
698	=item after $timeout, $callback	800	=item after $timeout, $callback
699		801
…		…
715	? $action[0]()	817	? $action[0]()
716	: snd @action;	818	: snd @action;
717	};	819	};
718	}	820	}
719		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
720	=back	874	=back
721		875
722	=head1 AnyEvent::MP vs. Distributed Erlang	876	=head1 AnyEvent::MP vs. Distributed Erlang
723		877
724	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
725	== 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
726	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
727	sample:	881	sample:
728		882
729	http://www.Erlang.se/doc/programming_rules.shtml	883	http://www.erlang.se/doc/programming_rules.shtml
730	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
731	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
732	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
733		887
734	Despite the similarities, there are also some important differences:	888	Despite the similarities, there are also some important differences:
735		889
736	=over 4	890	=over 4
737		891
738	=item * Node IDs are arbitrary strings in AEMP.	892	=item * Node IDs are arbitrary strings in AEMP.
739		893
740	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
741	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
742	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.
743		898
744	=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
745	uses "local ports are like remote ports".	900	uses "local ports are like remote ports".
746		901
747	The failure modes for local ports are quite different (runtime errors	902	The failure modes for local ports are quite different (runtime errors
…		…
756	ports being the special case/exception, where transport errors cannot	911	ports being the special case/exception, where transport errors cannot
757	occur.	912	occur.
758		913
759	=item * Erlang uses processes and a mailbox, AEMP does not queue.	914	=item * Erlang uses processes and a mailbox, AEMP does not queue.
760		915
761	Erlang uses processes that selectively receive messages, and therefore	916	Erlang uses processes that selectively receive messages out of order, and
762	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
763	useful purpose. For the same reason the pattern-matching abilities of	918	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	919	of AnyEvent::MP are more limited, as there is little need to be able to
765	filter messages without dequeuing them.	920	filter messages without dequeuing them.
766		921
767	(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.
768		927
769	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	928	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
770		929
771	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
772	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
773	connection establishment is handled in the background.	933	establishment is handled in the background.
774		934
775	=item * Erlang suffers from silent message loss, AEMP does not.	935	=item * Erlang suffers from silent message loss, AEMP does not.
776		936
777	Erlang makes few guarantees on messages delivery - messages can get lost	937	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,	938	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).	939	b, and c, and the other side only receives messages a and c).
780		940
781	AEMP guarantees correct ordering, and the guarantee that after one message	941	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	942	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	943	same port are lost as well, until monitoring raises an error, so there are
784	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.
785		950
786	=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.
787		952
788	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
789	known to other nodes for a completely different process, causing messages	954	process ID known to other nodes for a completely different process,
790	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.
791		957
792	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
793	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.
794		960
795	=item * Erlang uses unprotected connections, AEMP uses secure	961	=item * Erlang uses unprotected connections, AEMP uses secure
796	authentication and can use TLS.	962	authentication and can use TLS.
797		963
…		…
800		966
801	=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
802	communications.	968	communications.
803		969
804	The AEMP protocol, unlike the Erlang protocol, supports both programming	970	The AEMP protocol, unlike the Erlang protocol, supports both programming
805	language independent text-only protocols (good for debugging) and binary,	971	language independent text-only protocols (good for debugging), and binary,
806	language-specific serialisers (e.g. Storable). By default, unless TLS is	972	language-specific serialisers (e.g. Storable). By default, unless TLS is
807	used, the protocol is actually completely text-based.	973	used, the protocol is actually completely text-based.
808		974
809	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
810	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
811	protocol simple.	977	protocol simple.
812		978
813	=item * AEMP has more flexible monitoring options than Erlang.	979	=item * AEMP has more flexible monitoring options than Erlang.
814		980
815	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
816	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
817	difficult to implement. Monitoring in AEMP is more flexible than in	983	difficult to implement.
818	Erlang, as one can choose between automatic kill, exit message or callback	984
819	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.
820		987
821	=item * Erlang tries to hide remote/local connections, AEMP does not.	988	=item * Erlang tries to hide remote/local connections, AEMP does not.
822		989
823	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
824	same way as linking is (except linking is unreliable in Erlang).	991	same way as linking is (except linking is unreliable in Erlang).
…		…
846	overhead, as well as having to keep a proxy object everywhere.	1013	overhead, as well as having to keep a proxy object everywhere.
847		1014
848	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
849	procedures to be "valid".	1016	procedures to be "valid".
850		1017
851	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
852	global hash - it can't become much cheaper.	1019	code reference stored in a global hash - it can't become much cheaper.
853		1020
854	=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?
855		1022
856	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
857	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
…		…
873		1040
874	L<AnyEvent::MP::Intro> - a gentle introduction.	1041	L<AnyEvent::MP::Intro> - a gentle introduction.
875		1042
876	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1043	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
877		1044
878	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1045	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
879	your applications.	1046	your applications.
		1047
		1048	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
880		1049
881	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from	1050	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
882	all nodes.	1051	all nodes.
883		1052
884	L<AnyEvent>.	1053	L<AnyEvent>.

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.86 by root, Wed Sep 9 01:47:01 2009 UTC vs. Revision 1.121 by root, Tue Feb 28 18:37:24 2012 UTC

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Revision 1.86 by root, Wed Sep 9 01:47:01 2009 UTC vs.
Revision 1.121 by root, Tue Feb 28 18:37:24 2012 UTC