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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.96 by elmex, Thu Oct 1 13:19:03 2009 UTC vs.
Revision 1.127 by root, Sat Mar 3 20:35:10 2012 UTC

…		…
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 $localport, $cb->(@msg) # callback is invoked on death	40	mon $localport, $cb->(@msg) # callback is invoked on death
37	mon $localport, $otherport # kill otherport on abnormal death	41	mon $localport, $otherport # kill otherport on abnormal death
38	mon $localport, $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.
…		…
66		78
67	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
68	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
69	anything was listening for them or not.	81	anything was listening for them or not.
70		82
		83	Ports are represented by (printable) strings called "port IDs".
		84
71	=item port ID - C<nodeid#portname>	85	=item port ID - C<nodeid#portname>
72		86
73	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<#>)
74	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).
75		90
76	=item node	91	=item node
77		92
78	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,
79	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
80	ports.	95	ports.
81		96
82	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
83	(no listening ports). Private nodes cannot talk to other private nodes	98	(no listening ports). Private nodes cannot talk to other private nodes
84	currently.	99	currently, but all nodes can talk to public nodes.
85		100
		101	Nodes is represented by (printable) strings called "node IDs".
		102
86	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>	103	=item node ID - C<[A-Za-z0-9_\-.:]*>
87		104
88	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
89	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
90	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
91	doesn't interpret node IDs in any way.	108	doesn't interpret node IDs in any way except to uniquely identify a node.
92		109
93	=item binds - C<ip:port>	110	=item binds - C<ip:port>
94		111
95	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
96	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
97	endpoints - binds. Currently, only standard C<ip:port> specifications can	116	Currently, only standard C<ip:port> specifications can be used, which
98	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.
99		119
100	=item seed nodes	120	=item seed nodes
101		121
102	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
103	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
104	network. This node is called a seed.	124	network. These other nodes are called "seed nodes".
105		125
106	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
107	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
108	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.
109		129
110	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
111	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
112	trouble connecting. They form the backbone of an 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.
113		135
114	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
115	should always be available. They should also be relatively responsive - a	137	should always be available. They should also be relatively responsive - a
116	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.
117		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
118	=item seeds - C<host:port>	149	=item seed IDs - C<host:port>
119		150
120	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
121	TCP port) of nodes that should be used as seed nodes.	152	TCP port) of nodes that should be used as seed nodes.
122		153
123	The nodes listening on those endpoints are expected to be long-running,	154	=item global nodes
124	and at least one of those should always be available. When nodes run out	155
125	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
126	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).
127		170
128	=back	171	=back
129		172
130	=head1 VARIABLES/FUNCTIONS	173	=head1 VARIABLES/FUNCTIONS
131		174
…		…
133		176
134	=cut	177	=cut
135		178
136	package AnyEvent::MP;	179	package AnyEvent::MP;
137		180
		181	use AnyEvent::MP::Config ();
138	use AnyEvent::MP::Kernel;	182	use AnyEvent::MP::Kernel;
		183	use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID);
139		184
140	use common::sense;	185	use common::sense;
141		186
142	use Carp ();	187	use Carp ();
143		188
144	use AE ();	189	use AE ();
		190	use Guard ();
145		191
146	use base "Exporter";	192	use base "Exporter";
147		193
148	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	194	our $VERSION = $AnyEvent::MP::Config::VERSION;
149		195
150	our @EXPORT = qw(	196	our @EXPORT = qw(
151	NODE $NODE *SELF node_of after	197	NODE $NODE *SELF node_of after
152	configure	198	configure
153	snd rcv mon mon_guard kil psub spawn cal	199	snd rcv mon mon_guard kil psub peval spawn cal
154	port	200	port
		201	db_set db_del db_reg
155	);	202	);
156		203
157	our $SELF;	204	our $SELF;
158		205
159	sub _self_die() {	206	sub _self_die() {
…		…
182	some other nodes in the network to discover other nodes.	229	some other nodes in the network to discover other nodes.
183		230
184	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
185	never) before calling other AnyEvent::MP functions.	232	never) before calling other AnyEvent::MP functions.
186		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 these 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	=item secure => $pass->($nodeid)
		252
		253	In addition to specifying a boolean, you can specify a code reference that
		254	is called for every remote execution attempt - the execution request is
		255	granted iff the callback returns a true value.
		256
		257	See F<semp setsecure> for more info.
		258
		259	=back
		260
187	=over 4	261	=over 4
188		262
189	=item step 1, gathering configuration from profiles	263	=item step 1, gathering configuration from profiles
190		264
191	The function first looks up a profile in the aemp configuration (see the	265	The function first looks up a profile in the aemp configuration (see the
…		…
204	That means that the values specified in the profile have highest priority	278	That means that the values specified in the profile have highest priority
205	and the values specified directly via C<configure> have lowest priority,	279	and the values specified directly via C<configure> have lowest priority,
206	and can only be used to specify defaults.	280	and can only be used to specify defaults.
207		281
208	If the profile specifies a node ID, then this will become the node ID of	282	If the profile specifies a node ID, then this will become the node ID of
209	this process. If not, then the profile name will be used as node ID. The	283	this process. If not, then the profile name will be used as node ID, with
210	special node ID of C<anon/> will be replaced by a random node ID.	284	a unique randoms tring (C</%u>) appended.
		285
		286	The node ID can contain some C<%> sequences that are expanded: C<%n>
		287	is expanded to the local nodename, C<%u> is replaced by a random
		288	strign to make the node unique. For example, the F<aemp> commandline
		289	utility uses C<aemp/%n/%u> as nodename, which might expand to
		290	C<aemp/cerebro/ZQDGSIkRhEZQDGSIkRhE>.
211		291
212	=item step 2, bind listener sockets	292	=item step 2, bind listener sockets
213		293
214	The next step is to look up the binds in the profile, followed by binding	294	The next step is to look up the binds in the profile, followed by binding
215	aemp protocol listeners on all binds specified (it is possible and valid	295	aemp protocol listeners on all binds specified (it is possible and valid
…		…
221	used, meaning the node will bind on a dynamically-assigned port on every	301	used, meaning the node will bind on a dynamically-assigned port on every
222	local IP address it finds.	302	local IP address it finds.
223		303
224	=item step 3, connect to seed nodes	304	=item step 3, connect to seed nodes
225		305
226	As the last step, the seeds list from the profile is passed to the	306	As the last step, the seed ID list from the profile is passed to the
227	L<AnyEvent::MP::Global> module, which will then use it to keep	307	L<AnyEvent::MP::Global> module, which will then use it to keep
228	connectivity with at least one node at any point in time.	308	connectivity with at least one node at any point in time.
229		309
230	=back	310	=back
231		311
232	Example: become a distributed node using the local node name as profile.	312	Example: become a distributed node using the local node name as profile.
233	This should be the most common form of invocation for "daemon"-type nodes.	313	This should be the most common form of invocation for "daemon"-type nodes.
234		314
235	configure	315	configure
236		316
237	Example: become an anonymous node. This form is often used for commandline	317	Example: become a semi-anonymous node. This form is often used for
238	clients.	318	commandline clients.
239		319
240	configure nodeid => "anon/";	320	configure nodeid => "myscript/%n/%u";
241		321
242	Example: configure a node using a profile called seed, which si suitable	322	Example: configure a node using a profile called seed, which is suitable
243	for a seed node as it binds on all local addresses on a fixed port (4040,	323	for a seed node as it binds on all local addresses on a fixed port (4040,
244	customary for aemp).	324	customary for aemp).
245		325
246	# use the aemp commandline utility	326	# use the aemp commandline utility
247	# aemp profile seed nodeid anon/ binds '*:4040'	327	# aemp profile seed binds '*:4040'
248		328
249	# then use it	329	# then use it
250	configure profile => "seed";	330	configure profile => "seed";
251		331
252	# or simply use aemp from the shell again:	332	# or simply use aemp from the shell again:
…		…
322	sub _kilme {	402	sub _kilme {
323	die "received message on port without callback";	403	die "received message on port without callback";
324	}	404	}
325		405
326	sub port(;&) {	406	sub port(;&) {
327	my $id = "$UNIQ." . $ID++;	407	my $id = $UNIQ . ++$ID;
328	my $port = "$NODE#$id";	408	my $port = "$NODE#$id";
329		409
330	rcv $port, shift \|\| \&_kilme;	410	rcv $port, shift \|\| \&_kilme;
331		411
332	$port	412	$port
…		…
371	msg1 => sub { ... },	451	msg1 => sub { ... },
372	...	452	...
373	;	453	;
374		454
375	Example: temporarily register a rcv callback for a tag matching some port	455	Example: temporarily register a rcv callback for a tag matching some port
376	(e.g. for a rpc reply) and unregister it after a message was received.	456	(e.g. for an rpc reply) and unregister it after a message was received.
377		457
378	rcv $port, $otherport => sub {	458	rcv $port, $otherport => sub {
379	my @reply = @_;	459	my @reply = @_;
380		460
381	rcv $SELF, $otherport;	461	rcv $SELF, $otherport;
…		…
394	if (ref $_[0]) {	474	if (ref $_[0]) {
395	if (my $self = $PORT_DATA{$portid}) {	475	if (my $self = $PORT_DATA{$portid}) {
396	"AnyEvent::MP::Port" eq ref $self	476	"AnyEvent::MP::Port" eq ref $self
397	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	477	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
398		478
399	$self->[2] = shift;	479	$self->[0] = shift;
400	} else {	480	} else {
401	my $cb = shift;	481	my $cb = shift;
402	$PORT{$portid} = sub {	482	$PORT{$portid} = sub {
403	local $SELF = $port;	483	local $SELF = $port;
404	eval { &$cb }; _self_die if $@;	484	eval { &$cb }; _self_die if $@;
405	};	485	};
406	}	486	}
407	} elsif (defined $_[0]) {	487	} elsif (defined $_[0]) {
408	my $self = $PORT_DATA{$portid} \|\|= do {	488	my $self = $PORT_DATA{$portid} \|\|= do {
409	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	489	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
410		490
411	$PORT{$portid} = sub {	491	$PORT{$portid} = sub {
412	local $SELF = $port;	492	local $SELF = $port;
413		493
414	if (my $cb = $self->[1]{$_[0]}) {	494	if (my $cb = $self->[1]{$_[0]}) {
…		…
436	}	516	}
437		517
438	$port	518	$port
439	}	519	}
440		520
		521	=item peval $port, $coderef[, @args]
		522
		523	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
		524	when the code throews an exception the C<$port> will be killed.
		525
		526	Any remaining args will be passed to the callback. Any return values will
		527	be returned to the caller.
		528
		529	This is useful when you temporarily want to execute code in the context of
		530	a port.
		531
		532	Example: create a port and run some initialisation code in it's context.
		533
		534	my $port = port { ... };
		535
		536	peval $port, sub {
		537	init
		538	or die "unable to init";
		539	};
		540
		541	=cut
		542
		543	sub peval($$) {
		544	local $SELF = shift;
		545	my $cb = shift;
		546
		547	if (wantarray) {
		548	my @res = eval { &$cb };
		549	_self_die if $@;
		550	@res
		551	} else {
		552	my $res = eval { &$cb };
		553	_self_die if $@;
		554	$res
		555	}
		556	}
		557
441	=item $closure = psub { BLOCK }	558	=item $closure = psub { BLOCK }
442		559
443	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	560	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
444	closure is executed, sets up the environment in the same way as in C<rcv>	561	closure is executed, sets up the environment in the same way as in C<rcv>
445	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.	562	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		563
		564	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		565	BLOCK }, @_ } >>.
446		566
447	This is useful when you register callbacks from C<rcv> callbacks:	567	This is useful when you register callbacks from C<rcv> callbacks:
448		568
449	rcv delayed_reply => sub {	569	rcv delayed_reply => sub {
450	my ($delay, @reply) = @_;	570	my ($delay, @reply) = @_;
…		…
565	}	685	}
566		686
567	$node->monitor ($port, $cb);	687	$node->monitor ($port, $cb);
568		688
569	defined wantarray	689	defined wantarray
570	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })	690	and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) })
571	}	691	}
572		692
573	=item $guard = mon_guard $port, $ref, $ref...	693	=item $guard = mon_guard $port, $ref, $ref...
574		694
575	Monitors the given C<$port> and keeps the passed references. When the port	695	Monitors the given C<$port> and keeps the passed references. When the port
…		…
598		718
599	=item kil $port[, @reason]	719	=item kil $port[, @reason]
600		720
601	Kill the specified port with the given C<@reason>.	721	Kill the specified port with the given C<@reason>.
602		722
603	If no C<@reason> is specified, then the port is killed "normally" (ports	723	If no C<@reason> is specified, then the port is killed "normally" -
604	monitoring other ports will not necessarily die because a port dies	724	monitor callback will be invoked, but the kil will not cause linked ports
605	"normally").	725	(C<mon $mport, $lport> form) to get killed.
606		726
607	Otherwise, linked ports get killed with the same reason (second form of	727	If a C<@reason> is specified, then linked ports (C<mon $mport, $lport>
608	C<mon>, see above).	728	form) get killed with the same reason.
609		729
610	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	730	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
611	will be reported as reason C<< die => $@ >>.	731	will be reported as reason C<< die => $@ >>.
612		732
613	Transport/communication errors are reported as C<< transport_error =>	733	Transport/communication errors are reported as C<< transport_error =>
…		…
679	}	799	}
680		800
681	sub spawn(@) {	801	sub spawn(@) {
682	my ($nodeid, undef) = split /#/, shift, 2;	802	my ($nodeid, undef) = split /#/, shift, 2;
683		803
684	my $id = "$RUNIQ." . $ID++;	804	my $id = $RUNIQ . ++$ID;
685		805
686	$_[0] =~ /::/	806	$_[0] =~ /::/
687	or Carp::croak "spawn init function must be a fully-qualified name, caught";	807	or Carp::croak "spawn init function must be a fully-qualified name, caught";
688		808
689	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;	809	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
690		810
691	"$nodeid#$id"	811	"$nodeid#$id"
692	}	812	}
		813
693		814
694	=item after $timeout, @msg	815	=item after $timeout, @msg
695		816
696	=item after $timeout, $callback	817	=item after $timeout, $callback
697		818
…		…
727		848
728	If an optional time-out (in seconds) is given and it is not C<undef>,	849	If an optional time-out (in seconds) is given and it is not C<undef>,
729	then the callback will be called without any arguments after the time-out	850	then the callback will be called without any arguments after the time-out
730	elapsed and the port is C<kil>ed.	851	elapsed and the port is C<kil>ed.
731		852
732	If no time-out is given, then the local port will monitor the remote port	853	If no time-out is given (or it is C<undef>), then the local port will
733	instead, so it eventually gets cleaned-up.	854	monitor the remote port instead, so it eventually gets cleaned-up.
734		855
735	Currently this function returns the temporary port, but this "feature"	856	Currently this function returns the temporary port, but this "feature"
736	might go in future versions unless you can make a convincing case that	857	might go in future versions unless you can make a convincing case that
737	this is indeed useful for something.	858	this is indeed useful for something.
738		859
…		…
767	$port	888	$port
768	}	889	}
769		890
770	=back	891	=back
771		892
		893	=head1 DISTRIBUTED DATABASE
		894
		895	AnyEvent::MP comes with a simple distributed database. The database will
		896	be mirrored asynchronously at all global nodes. Other nodes bind to one of
		897	the global nodes for their needs.
		898
		899	The database consists of a two-level hash - a hash contains a hash which
		900	contains values.
		901
		902	The top level hash key is called "family", and the second-level hash key
		903	is called "subkey" or simply "key".
		904
		905	The family must be alphanumeric, i.e. start with a letter and consist
		906	of letters, digits, underscores and colons (C<[A-Za-z][A-Za-z0-9_:]*>,
		907	pretty much like Perl module names.
		908
		909	As the family namespace is global, it is recommended to prefix family names
		910	with the name of the application or module using it.
		911
		912	The subkeys must be non-empty strings, with no further restrictions.
		913
		914	The values should preferably be strings, but other perl scalars should
		915	work as well (such as undef, arrays and hashes).
		916
		917	Every database entry is owned by one node - adding the same family/subkey
		918	combination on multiple nodes will not cause discomfort for AnyEvent::MP,
		919	but the result might be nondeterministic, i.e. the key might have
		920	different values on different nodes.
		921
		922	Different subkeys in the same family can be owned by different nodes
		923	without problems, and in fact, this is the common method to create worker
		924	pools. For example, a worker port for image scaling might do this:
		925
		926	db_set my_image_scalers => $port;
		927
		928	And clients looking for an image scaler will want to get the
		929	C<my_image_scalers> keys:
		930
		931	db_keys "my_image_scalers" => 60 => sub {
		932	#d##TODO#
		933
		934	=over
		935
		936	=item db_set $family => $subkey [=> $value]
		937
		938	Sets (or replaces) a key to the database - if C<$value> is omitted,
		939	C<undef> is used instead.
		940
		941	=item db_del $family => $subkey
		942
		943	Deletes a key from the database.
		944
		945	=item $guard = db_reg $family => $subkey [=> $value]
		946
		947	Sets the key on the database and returns a guard. When the guard is
		948	destroyed, the key is deleted from the database. If C<$value> is missing,
		949	then C<undef> is used.
		950
		951	=cut
		952
		953	=back
		954
772	=head1 AnyEvent::MP vs. Distributed Erlang	955	=head1 AnyEvent::MP vs. Distributed Erlang
773		956
774	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	957	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
775	== aemp node, Erlang process == aemp port), so many of the documents and	958	== aemp node, Erlang process == aemp port), so many of the documents and
776	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	959	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
…		…
787		970
788	=item * Node IDs are arbitrary strings in AEMP.	971	=item * Node IDs are arbitrary strings in AEMP.
789		972
790	Erlang relies on special naming and DNS to work everywhere in the same	973	Erlang relies on special naming and DNS to work everywhere in the same
791	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by	974	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
792	configuration or DNS), but will otherwise discover other odes itself.	975	configuration or DNS), and possibly the addresses of some seed nodes, but
		976	will otherwise discover other nodes (and their IDs) itself.
793		977
794	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	978	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
795	uses "local ports are like remote ports".	979	uses "local ports are like remote ports".
796		980
797	The failure modes for local ports are quite different (runtime errors	981	The failure modes for local ports are quite different (runtime errors
…		…
806	ports being the special case/exception, where transport errors cannot	990	ports being the special case/exception, where transport errors cannot
807	occur.	991	occur.
808		992
809	=item * Erlang uses processes and a mailbox, AEMP does not queue.	993	=item * Erlang uses processes and a mailbox, AEMP does not queue.
810		994
811	Erlang uses processes that selectively receive messages, and therefore	995	Erlang uses processes that selectively receive messages out of order, and
812	needs a queue. AEMP is event based, queuing messages would serve no	996	therefore needs a queue. AEMP is event based, queuing messages would serve
813	useful purpose. For the same reason the pattern-matching abilities of	997	no useful purpose. For the same reason the pattern-matching abilities
814	AnyEvent::MP are more limited, as there is little need to be able to	998	of AnyEvent::MP are more limited, as there is little need to be able to
815	filter messages without dequeuing them.	999	filter messages without dequeuing them.
816		1000
817	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	1001	This is not a philosophical difference, but simply stems from AnyEvent::MP
		1002	being event-based, while Erlang is process-based.
		1003
		1004	You cna have a look at L<Coro::MP> for a more Erlang-like process model on
		1005	top of AEMP and Coro threads.
818		1006
819	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	1007	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
820		1008
821	Sending messages in Erlang is synchronous and blocks the process (and	1009	Sending messages in Erlang is synchronous and blocks the process until
		1010	a conenction has been established and the message sent (and so does not
822	so does not need a queue that can overflow). AEMP sends are immediate,	1011	need a queue that can overflow). AEMP sends return immediately, connection
823	connection establishment is handled in the background.	1012	establishment is handled in the background.
824		1013
825	=item * Erlang suffers from silent message loss, AEMP does not.	1014	=item * Erlang suffers from silent message loss, AEMP does not.
826		1015
827	Erlang makes few guarantees on messages delivery - messages can get lost	1016	Erlang implements few guarantees on messages delivery - messages can get
828	without any of the processes realising it (i.e. you send messages a, b,	1017	lost without any of the processes realising it (i.e. you send messages a,
829	and c, and the other side only receives messages a and c).	1018	b, and c, and the other side only receives messages a and c).
830		1019
831	AEMP guarantees correct ordering, and the guarantee that after one message	1020	AEMP guarantees (modulo hardware errors) correct ordering, and the
832	is lost, all following ones sent to the same port are lost as well, until	1021	guarantee that after one message is lost, all following ones sent to the
833	monitoring raises an error, so there are no silent "holes" in the message	1022	same port are lost as well, until monitoring raises an error, so there are
834	sequence.	1023	no silent "holes" in the message sequence.
		1024
		1025	If you want your software to be very reliable, you have to cope with
		1026	corrupted and even out-of-order messages in both Erlang and AEMP. AEMP
		1027	simply tries to work better in common error cases, such as when a network
		1028	link goes down.
835		1029
836	=item * Erlang can send messages to the wrong port, AEMP does not.	1030	=item * Erlang can send messages to the wrong port, AEMP does not.
837		1031
838	In Erlang it is quite likely that a node that restarts reuses a process ID	1032	In Erlang it is quite likely that a node that restarts reuses an Erlang
839	known to other nodes for a completely different process, causing messages	1033	process ID known to other nodes for a completely different process,
840	destined for that process to end up in an unrelated process.	1034	causing messages destined for that process to end up in an unrelated
		1035	process.
841		1036
842	AEMP never reuses port IDs, so old messages or old port IDs floating	1037	AEMP does not reuse port IDs, so old messages or old port IDs floating
843	around in the network will not be sent to an unrelated port.	1038	around in the network will not be sent to an unrelated port.
844		1039
845	=item * Erlang uses unprotected connections, AEMP uses secure	1040	=item * Erlang uses unprotected connections, AEMP uses secure
846	authentication and can use TLS.	1041	authentication and can use TLS.
847		1042
…		…
850		1045
851	=item * The AEMP protocol is optimised for both text-based and binary	1046	=item * The AEMP protocol is optimised for both text-based and binary
852	communications.	1047	communications.
853		1048
854	The AEMP protocol, unlike the Erlang protocol, supports both programming	1049	The AEMP protocol, unlike the Erlang protocol, supports both programming
855	language independent text-only protocols (good for debugging) and binary,	1050	language independent text-only protocols (good for debugging), and binary,
856	language-specific serialisers (e.g. Storable). By default, unless TLS is	1051	language-specific serialisers (e.g. Storable). By default, unless TLS is
857	used, the protocol is actually completely text-based.	1052	used, the protocol is actually completely text-based.
858		1053
859	It has also been carefully designed to be implementable in other languages	1054	It has also been carefully designed to be implementable in other languages
860	with a minimum of work while gracefully degrading functionality to make the	1055	with a minimum of work while gracefully degrading functionality to make the
861	protocol simple.	1056	protocol simple.
862		1057
863	=item * AEMP has more flexible monitoring options than Erlang.	1058	=item * AEMP has more flexible monitoring options than Erlang.
864		1059
865	In Erlang, you can chose to receive I<all> exit signals as messages	1060	In Erlang, you can chose to receive I<all> exit signals as messages or
866	or I<none>, there is no in-between, so monitoring single processes is	1061	I<none>, there is no in-between, so monitoring single Erlang processes is
867	difficult to implement. Monitoring in AEMP is more flexible than in	1062	difficult to implement.
868	Erlang, as one can choose between automatic kill, exit message or callback	1063
869	on a per-process basis.	1064	Monitoring in AEMP is more flexible than in Erlang, as one can choose
		1065	between automatic kill, exit message or callback on a per-port basis.
870		1066
871	=item * Erlang tries to hide remote/local connections, AEMP does not.	1067	=item * Erlang tries to hide remote/local connections, AEMP does not.
872		1068
873	Monitoring in Erlang is not an indicator of process death/crashes, in the	1069	Monitoring in Erlang is not an indicator of process death/crashes, in the
874	same way as linking is (except linking is unreliable in Erlang).	1070	same way as linking is (except linking is unreliable in Erlang).
…		…
896	overhead, as well as having to keep a proxy object everywhere.	1092	overhead, as well as having to keep a proxy object everywhere.
897		1093
898	Strings can easily be printed, easily serialised etc. and need no special	1094	Strings can easily be printed, easily serialised etc. and need no special
899	procedures to be "valid".	1095	procedures to be "valid".
900		1096
901	And as a result, a miniport consists of a single closure stored in a	1097	And as a result, a port with just a default receiver consists of a single
902	global hash - it can't become much cheaper.	1098	code reference stored in a global hash - it can't become much cheaper.
903		1099
904	=item Why favour JSON, why not a real serialising format such as Storable?	1100	=item Why favour JSON, why not a real serialising format such as Storable?
905		1101
906	In fact, any AnyEvent::MP node will happily accept Storable as framing	1102	In fact, any AnyEvent::MP node will happily accept Storable as framing
907	format, but currently there is no way to make a node use Storable by	1103	format, but currently there is no way to make a node use Storable by
…		…
923		1119
924	L<AnyEvent::MP::Intro> - a gentle introduction.	1120	L<AnyEvent::MP::Intro> - a gentle introduction.
925		1121
926	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1122	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
927		1123
928	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1124	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
929	your applications.	1125	your applications.
		1126
		1127	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
930		1128
931	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from	1129	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
932	all nodes.	1130	all nodes.
933		1131
934	L<AnyEvent>.	1132	L<AnyEvent>.

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.96 by elmex, Thu Oct 1 13:19:03 2009 UTC vs. Revision 1.127 by root, Sat Mar 3 20:35:10 2012 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.96 by elmex, Thu Oct 1 13:19:03 2009 UTC vs.
Revision 1.127 by root, Sat Mar 3 20:35:10 2012 UTC