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

Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.78 by root, Thu Sep 3 20:16:36 2009 UTC vs.
Revision 1.127 by root, Sat Mar 3 20:35:10 2012 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent::MP - multi-processing/message-passing framework	3	AnyEvent::MP - erlang-style multi-processing/message-passing framework
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
30	rcv $port, pong => sub { warn "pong received\n" };	30	rcv $port, pong => sub { warn "pong received\n" };
31		31
32	# create a port on another node	32	# create a port on another node
33	my $port = spawn $node, $initfunc, @initdata;	33	my $port = spawn $node, $initfunc, @initdata;
34		34
		35	# destroy a port again
		36	kil $port; # "normal" kill
		37	kil $port, my_error => "everything is broken"; # error kill
		38
35	# monitoring	39	# monitoring
36	mon $port, $cb->(@msg) # callback is invoked on death	40	mon $localport, $cb->(@msg) # callback is invoked on death
37	mon $port, $otherport # kill otherport on abnormal death	41	mon $localport, $otherport # kill otherport on abnormal death
38	mon $port, $otherport, @msg # send message on death	42	mon $localport, $otherport, @msg # send message on death
		43
		44	# temporarily execute code in port context
		45	peval $port, sub { die "kill the port!" };
		46
		47	# execute callbacks in $SELF port context
		48	my $timer = AE::timer 1, 0, psub {
		49	die "kill the port, delayed";
		50	};
39		51
40	=head1 CURRENT STATUS	52	=head1 CURRENT STATUS
41		53
42	bin/aemp - stable.	54	bin/aemp - stable.
43	AnyEvent::MP - stable API, should work.	55	AnyEvent::MP - stable API, should work.
44	AnyEvent::MP::Intro - explains most concepts.	56	AnyEvent::MP::Intro - explains most concepts.
45	AnyEvent::MP::Kernel - mostly stable.	57	AnyEvent::MP::Kernel - mostly stable API.
46	AnyEvent::MP::Global - stable API, protocol not yet final.	58	AnyEvent::MP::Global - stable API.
47
48	stay tuned.
49		59
50	=head1 DESCRIPTION	60	=head1 DESCRIPTION
51		61
52	This module (-family) implements a simple message passing framework.	62	This module (-family) implements a simple message passing framework.
53		63
…		…
61		71
62	=over 4	72	=over 4
63		73
64	=item port	74	=item port
65		75
66	A port is something you can send messages to (with the C<snd> function).	76	Not to be confused with a TCP port, a "port" is something you can send
		77	messages to (with the C<snd> function).
67		78
68	Ports allow you to register C<rcv> handlers that can match all or just	79	Ports allow you to register C<rcv> handlers that can match all or just
69	some messages. Messages send to ports will not be queued, regardless of	80	some messages. Messages send to ports will not be queued, regardless of
70	anything was listening for them or not.	81	anything was listening for them or not.
71		82
		83	Ports are represented by (printable) strings called "port IDs".
		84
72	=item port ID - C<nodeid#portname>	85	=item port ID - C<nodeid#portname>
73		86
74	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as	87	A port ID is the concatenation of a node ID, a hash-mark (C<#>)
75	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).
76		90
77	=item node	91	=item node
78		92
79	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,
80	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
81	ports.	95	ports.
82		96
83	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
84	(no listening ports). Private nodes cannot talk to other private nodes	98	(no listening ports). Private nodes cannot talk to other private nodes
85	currently.	99	currently, but all nodes can talk to public nodes.
86		100
		101	Nodes is represented by (printable) strings called "node IDs".
		102
87	=item node ID - C<[a-za-Z0-9_\-.:]+>	103	=item node ID - C<[A-Za-z0-9_\-.:]*>
88		104
89	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
90	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
91	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
92	doesn't interpret node IDs in any way.	108	doesn't interpret node IDs in any way except to uniquely identify a node.
93		109
94	=item binds - C<ip:port>	110	=item binds - C<ip:port>
95		111
96	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
97	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
98	endpoints - binds. Currently, only standard C<ip:port> specifications can	116	Currently, only standard C<ip:port> specifications can be used, which
99	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.
100		119
		120	=item seed nodes
		121
		122	When a node starts, it knows nothing about the network it is in - it
		123	needs to connect to at least one other node that is already in the
		124	network. These other nodes are called "seed nodes".
		125
		126	Seed nodes themselves are not special - they are seed nodes only because
		127	some other node I<uses> them as such, but any node can be used as seed
		128	node for other nodes, and eahc node cna use a different set of seed nodes.
		129
		130	In addition to discovering the network, seed nodes are also used to
		131	maintain the network - all nodes using the same seed node form are part of
		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.
		135
		136	Seed nodes are expected to be long-running, and at least one seed node
		137	should always be available. They should also be relatively responsive - a
		138	seed node that blocks for long periods will slow down everybody else.
		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
101	=item seeds - C<host:port>	149	=item seed IDs - C<host:port>
102		150
103	When a node starts, it knows nothing about the network. To teach the node	151	Seed IDs are transport endpoint(s) (usually a hostname/IP address and a
104	about the network it first has to contact some other node within the	152	TCP port) of nodes that should be used as seed nodes.
105	network. This node is called a seed.
106		153
107	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	154	=item global nodes
108	are expected to be long-running, and at least one of those should always
109	be available. When nodes run out of connections (e.g. due to a network
110	error), they try to re-establish connections to some seednodes again to
111	join the network.
112		155
113	Apart from being sued for seeding, seednodes are not special in any way -	156	An AEMP network needs a discovery service - nodes need to know how to
114	every public node can be a seednode.	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).
115		170
116	=back	171	=back
117		172
118	=head1 VARIABLES/FUNCTIONS	173	=head1 VARIABLES/FUNCTIONS
119		174
…		…
121		176
122	=cut	177	=cut
123		178
124	package AnyEvent::MP;	179	package AnyEvent::MP;
125		180
		181	use AnyEvent::MP::Config ();
126	use AnyEvent::MP::Kernel;	182	use AnyEvent::MP::Kernel;
		183	use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID);
127		184
128	use common::sense;	185	use common::sense;
129		186
130	use Carp ();	187	use Carp ();
131		188
132	use AE ();	189	use AE ();
		190	use Guard ();
133		191
134	use base "Exporter";	192	use base "Exporter";
135		193
136	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	194	our $VERSION = $AnyEvent::MP::Config::VERSION;
137		195
138	our @EXPORT = qw(	196	our @EXPORT = qw(
139	NODE $NODE *SELF node_of after	197	NODE $NODE *SELF node_of after
140	configure	198	configure
141	snd rcv mon mon_guard kil reg psub spawn	199	snd rcv mon mon_guard kil psub peval spawn cal
142	port	200	port
		201	db_set db_del db_reg
143	);	202	);
144		203
145	our $SELF;	204	our $SELF;
146		205
147	sub _self_die() {	206	sub _self_die() {
…		…
170	some other nodes in the network to discover other nodes.	229	some other nodes in the network to discover other nodes.
171		230
172	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
173	never) before calling other AnyEvent::MP functions.	232	never) before calling other AnyEvent::MP functions.
174		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
175	=over 4	261	=over 4
176		262
177	=item step 1, gathering configuration from profiles	263	=item step 1, gathering configuration from profiles
178		264
179	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
…		…
192	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
193	and the values specified directly via C<configure> have lowest priority,	279	and the values specified directly via C<configure> have lowest priority,
194	and can only be used to specify defaults.	280	and can only be used to specify defaults.
195		281
196	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
197	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
198	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>.
199		291
200	=item step 2, bind listener sockets	292	=item step 2, bind listener sockets
201		293
202	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
203	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
…		…
209	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
210	local IP address it finds.	302	local IP address it finds.
211		303
212	=item step 3, connect to seed nodes	304	=item step 3, connect to seed nodes
213		305
214	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
215	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
216	connectivity with at least one node at any point in time.	308	connectivity with at least one node at any point in time.
217		309
218	=back	310	=back
219		311
220	Example: become a distributed node using the locla node name as profile.	312	Example: become a distributed node using the local node name as profile.
221	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.
222		314
223	configure	315	configure
224		316
225	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
226	clients.	318	commandline clients.
227		319
228	configure nodeid => "anon/";	320	configure nodeid => "myscript/%n/%u";
229		321
230	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
231	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,
232	customary for aemp).	324	customary for aemp).
233		325
234	# use the aemp commandline utility	326	# use the aemp commandline utility
235	# aemp profile seed nodeid anon/ binds '*:4040'	327	# aemp profile seed binds '*:4040'
236		328
237	# then use it	329	# then use it
238	configure profile => "seed";	330	configure profile => "seed";
239		331
240	# or simply use aemp from the shell again:	332	# or simply use aemp from the shell again:
…		…
310	sub _kilme {	402	sub _kilme {
311	die "received message on port without callback";	403	die "received message on port without callback";
312	}	404	}
313		405
314	sub port(;&) {	406	sub port(;&) {
315	my $id = "$UNIQ." . $ID++;	407	my $id = $UNIQ . ++$ID;
316	my $port = "$NODE#$id";	408	my $port = "$NODE#$id";
317		409
318	rcv $port, shift \|\| \&_kilme;	410	rcv $port, shift \|\| \&_kilme;
319		411
320	$port	412	$port
…		…
359	msg1 => sub { ... },	451	msg1 => sub { ... },
360	...	452	...
361	;	453	;
362		454
363	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
364	(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.
365		457
366	rcv $port, $otherport => sub {	458	rcv $port, $otherport => sub {
367	my @reply = @_;	459	my @reply = @_;
368		460
369	rcv $SELF, $otherport;	461	rcv $SELF, $otherport;
…		…
382	if (ref $_[0]) {	474	if (ref $_[0]) {
383	if (my $self = $PORT_DATA{$portid}) {	475	if (my $self = $PORT_DATA{$portid}) {
384	"AnyEvent::MP::Port" eq ref $self	476	"AnyEvent::MP::Port" eq ref $self
385	or Carp::croak "$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";
386		478
387	$self->[2] = shift;	479	$self->[0] = shift;
388	} else {	480	} else {
389	my $cb = shift;	481	my $cb = shift;
390	$PORT{$portid} = sub {	482	$PORT{$portid} = sub {
391	local $SELF = $port;	483	local $SELF = $port;
392	eval { &$cb }; _self_die if $@;	484	eval { &$cb }; _self_die if $@;
393	};	485	};
394	}	486	}
395	} elsif (defined $_[0]) {	487	} elsif (defined $_[0]) {
396	my $self = $PORT_DATA{$portid} \|\|= do {	488	my $self = $PORT_DATA{$portid} \|\|= do {
397	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	489	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
398		490
399	$PORT{$portid} = sub {	491	$PORT{$portid} = sub {
400	local $SELF = $port;	492	local $SELF = $port;
401		493
402	if (my $cb = $self->[1]{$_[0]}) {	494	if (my $cb = $self->[1]{$_[0]}) {
…		…
424	}	516	}
425		517
426	$port	518	$port
427	}	519	}
428		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
429	=item $closure = psub { BLOCK }	558	=item $closure = psub { BLOCK }
430		559
431	Remembers C<$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
432	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>
433	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 $SELF, sub {
		565	BLOCK }, @_ } >>.
434		566
435	This is useful when you register callbacks from C<rcv> callbacks:	567	This is useful when you register callbacks from C<rcv> callbacks:
436		568
437	rcv delayed_reply => sub {	569	rcv delayed_reply => sub {
438	my ($delay, @reply) = @_;	570	my ($delay, @reply) = @_;
…		…
474		606
475	Monitor the given port and do something when the port is killed or	607	Monitor the given port and do something when the port is killed or
476	messages to it were lost, and optionally return a guard that can be used	608	messages to it were lost, and optionally return a guard that can be used
477	to stop monitoring again.	609	to stop monitoring again.
478		610
		611	In the first form (callback), the callback is simply called with any
		612	number of C<@reason> elements (no @reason means that the port was deleted
		613	"normally"). Note also that I<< the callback B<must> never die >>, so use
		614	C<eval> if unsure.
		615
		616	In the second form (another port given), the other port (C<$rcvport>)
		617	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
		618	"normal" kils nothing happens, while under all other conditions, the other
		619	port is killed with the same reason.
		620
		621	The third form (kill self) is the same as the second form, except that
		622	C<$rvport> defaults to C<$SELF>.
		623
		624	In the last form (message), a message of the form C<@msg, @reason> will be
		625	C<snd>.
		626
		627	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		628	alert was raised), they are removed and will not trigger again.
		629
		630	As a rule of thumb, monitoring requests should always monitor a port from
		631	a local port (or callback). The reason is that kill messages might get
		632	lost, just like any other message. Another less obvious reason is that
		633	even monitoring requests can get lost (for example, when the connection
		634	to the other node goes down permanently). When monitoring a port locally
		635	these problems do not exist.
		636
479	C<mon> effectively guarantees that, in the absence of hardware failures,	637	C<mon> effectively guarantees that, in the absence of hardware failures,
480	after starting the monitor, either all messages sent to the port will	638	after starting the monitor, either all messages sent to the port will
481	arrive, or the monitoring action will be invoked after possible message	639	arrive, or the monitoring action will be invoked after possible message
482	loss has been detected. No messages will be lost "in between" (after	640	loss has been detected. No messages will be lost "in between" (after
483	the first lost message no further messages will be received by the	641	the first lost message no further messages will be received by the
484	port). After the monitoring action was invoked, further messages might get	642	port). After the monitoring action was invoked, further messages might get
485	delivered again.	643	delivered again.
486		644
487	Note that monitoring-actions are one-shot: once messages are lost (and a	645	Inter-host-connection timeouts and monitoring depend on the transport
488	monitoring alert was raised), they are removed and will not trigger again.	646	used. The only transport currently implemented is TCP, and AnyEvent::MP
		647	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		648	non-idle connection, and usually around two hours for idle connections).
489		649
490	In the first form (callback), the callback is simply called with any	650	This means that monitoring is good for program errors and cleaning up
491	number of C<@reason> elements (no @reason means that the port was deleted	651	stuff eventually, but they are no replacement for a timeout when you need
492	"normally"). Note also that I<< the callback B<must> never die >>, so use	652	to ensure some maximum latency.
493	C<eval> if unsure.
494
495	In the second form (another port given), the other port (C<$rcvport>)
496	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
497	"normal" kils nothing happens, while under all other conditions, the other
498	port is killed with the same reason.
499
500	The third form (kill self) is the same as the second form, except that
501	C<$rvport> defaults to C<$SELF>.
502
503	In the last form (message), a message of the form C<@msg, @reason> will be
504	C<snd>.
505
506	As a rule of thumb, monitoring requests should always monitor a port from
507	a local port (or callback). The reason is that kill messages might get
508	lost, just like any other message. Another less obvious reason is that
509	even monitoring requests can get lost (for example, when the connection
510	to the other node goes down permanently). When monitoring a port locally
511	these problems do not exist.
512		653
513	Example: call a given callback when C<$port> is killed.	654	Example: call a given callback when C<$port> is killed.
514		655
515	mon $port, sub { warn "port died because of <@_>\n" };	656	mon $port, sub { warn "port died because of <@_>\n" };
516		657
…		…
544	}	685	}
545		686
546	$node->monitor ($port, $cb);	687	$node->monitor ($port, $cb);
547		688
548	defined wantarray	689	defined wantarray
549	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	690	and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) })
550	}	691	}
551		692
552	=item $guard = mon_guard $port, $ref, $ref...	693	=item $guard = mon_guard $port, $ref, $ref...
553		694
554	Monitors the given C<$port> and keeps the passed references. When the port	695	Monitors the given C<$port> and keeps the passed references. When the port
…		…
577		718
578	=item kil $port[, @reason]	719	=item kil $port[, @reason]
579		720
580	Kill the specified port with the given C<@reason>.	721	Kill the specified port with the given C<@reason>.
581		722
582	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" -
583	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
584	"normally").	725	(C<mon $mport, $lport> form) to get killed.
585		726
586	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>
587	C<mon>, see above).	728	form) get killed with the same reason.
588		729
589	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
590	will be reported as reason C<< die => $@ >>.	731	will be reported as reason C<< die => $@ >>.
591		732
592	Transport/communication errors are reported as C<< transport_error =>	733	Transport/communication errors are reported as C<< transport_error =>
…		…
611	the package, then the package above the package and so on (e.g.	752	the package, then the package above the package and so on (e.g.
612	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	753	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
613	exists or it runs out of package names.	754	exists or it runs out of package names.
614		755
615	The init function is then called with the newly-created port as context	756	The init function is then called with the newly-created port as context
616	object (C<$SELF>) and the C<@initdata> values as arguments.	757	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		758	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		759	the port might not get created.
617		760
618	A common idiom is to pass a local port, immediately monitor the spawned	761	A common idiom is to pass a local port, immediately monitor the spawned
619	port, and in the remote init function, immediately monitor the passed	762	port, and in the remote init function, immediately monitor the passed
620	local port. This two-way monitoring ensures that both ports get cleaned up	763	local port. This two-way monitoring ensures that both ports get cleaned up
621	when there is a problem.	764	when there is a problem.
622		765
		766	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		767	caller before C<spawn> returns (by delaying invocation when spawn is
		768	called for the local node).
		769
623	Example: spawn a chat server port on C<$othernode>.	770	Example: spawn a chat server port on C<$othernode>.
624		771
625	# this node, executed from within a port context:	772	# this node, executed from within a port context:
626	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	773	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
627	mon $server;	774	mon $server;
…		…
641		788
642	sub _spawn {	789	sub _spawn {
643	my $port = shift;	790	my $port = shift;
644	my $init = shift;	791	my $init = shift;
645		792
		793	# rcv will create the actual port
646	local $SELF = "$NODE#$port";	794	local $SELF = "$NODE#$port";
647	eval {	795	eval {
648	&{ load_func $init }	796	&{ load_func $init }
649	};	797	};
650	_self_die if $@;	798	_self_die if $@;
651	}	799	}
652		800
653	sub spawn(@) {	801	sub spawn(@) {
654	my ($nodeid, undef) = split /#/, shift, 2;	802	my ($nodeid, undef) = split /#/, shift, 2;
655		803
656	my $id = "$RUNIQ." . $ID++;	804	my $id = $RUNIQ . ++$ID;
657		805
658	$_[0] =~ /::/	806	$_[0] =~ /::/
659	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";
660		808
661	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;	809	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
662		810
663	"$nodeid#$id"	811	"$nodeid#$id"
664	}	812	}
		813
665		814
666	=item after $timeout, @msg	815	=item after $timeout, @msg
667		816
668	=item after $timeout, $callback	817	=item after $timeout, $callback
669		818
…		…
685	? $action[0]()	834	? $action[0]()
686	: snd @action;	835	: snd @action;
687	};	836	};
688	}	837	}
689		838
		839	=item cal $port, @msg, $callback[, $timeout]
		840
		841	A simple form of RPC - sends a message to the given C<$port> with the
		842	given contents (C<@msg>), but adds a reply port to the message.
		843
		844	The reply port is created temporarily just for the purpose of receiving
		845	the reply, and will be C<kil>ed when no longer needed.
		846
		847	A reply message sent to the port is passed to the C<$callback> as-is.
		848
		849	If an optional time-out (in seconds) is given and it is not C<undef>,
		850	then the callback will be called without any arguments after the time-out
		851	elapsed and the port is C<kil>ed.
		852
		853	If no time-out is given (or it is C<undef>), then the local port will
		854	monitor the remote port instead, so it eventually gets cleaned-up.
		855
		856	Currently this function returns the temporary port, but this "feature"
		857	might go in future versions unless you can make a convincing case that
		858	this is indeed useful for something.
		859
		860	=cut
		861
		862	sub cal(@) {
		863	my $timeout = ref $_[-1] ? undef : pop;
		864	my $cb = pop;
		865
		866	my $port = port {
		867	undef $timeout;
		868	kil $SELF;
		869	&$cb;
		870	};
		871
		872	if (defined $timeout) {
		873	$timeout = AE::timer $timeout, 0, sub {
		874	undef $timeout;
		875	kil $port;
		876	$cb->();
		877	};
		878	} else {
		879	mon $_[0], sub {
		880	kil $port;
		881	$cb->();
		882	};
		883	}
		884
		885	push @_, $port;
		886	&snd;
		887
		888	$port
		889	}
		890
		891	=back
		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
690	=back	953	=back
691		954
692	=head1 AnyEvent::MP vs. Distributed Erlang	955	=head1 AnyEvent::MP vs. Distributed Erlang
693		956
694	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
695	== 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
696	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
697	sample:	960	sample:
698		961
699	http://www.Erlang.se/doc/programming_rules.shtml	962	http://www.erlang.se/doc/programming_rules.shtml
700	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	963	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
701	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6	964	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
702	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	965	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
703		966
704	Despite the similarities, there are also some important differences:	967	Despite the similarities, there are also some important differences:
705		968
706	=over 4	969	=over 4
707		970
708	=item * Node IDs are arbitrary strings in AEMP.	971	=item * Node IDs are arbitrary strings in AEMP.
709		972
710	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
711	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
712	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.
713		977
714	=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
715	uses "local ports are like remote ports".	979	uses "local ports are like remote ports".
716		980
717	The failure modes for local ports are quite different (runtime errors	981	The failure modes for local ports are quite different (runtime errors
…		…
726	ports being the special case/exception, where transport errors cannot	990	ports being the special case/exception, where transport errors cannot
727	occur.	991	occur.
728		992
729	=item * Erlang uses processes and a mailbox, AEMP does not queue.	993	=item * Erlang uses processes and a mailbox, AEMP does not queue.
730		994
731	Erlang uses processes that selectively receive messages, and therefore	995	Erlang uses processes that selectively receive messages out of order, and
732	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
733	useful purpose. For the same reason the pattern-matching abilities of	997	no useful purpose. For the same reason the pattern-matching abilities
734	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
735	filter messages without dequeuing them.	999	filter messages without dequeuing them.
736		1000
737	(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.
738		1006
739	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	1007	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
740		1008
741	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
742	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
743	connection establishment is handled in the background.	1012	establishment is handled in the background.
744		1013
745	=item * Erlang suffers from silent message loss, AEMP does not.	1014	=item * Erlang suffers from silent message loss, AEMP does not.
746		1015
747	Erlang makes few guarantees on messages delivery - messages can get lost	1016	Erlang implements few guarantees on messages delivery - messages can get
748	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,
749	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).
750		1019
751	AEMP guarantees correct ordering, and the guarantee that after one message	1020	AEMP guarantees (modulo hardware errors) correct ordering, and the
752	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
753	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
754	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.
755		1029
756	=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.
757		1031
758	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
759	known to other nodes for a completely different process, causing messages	1033	process ID known to other nodes for a completely different process,
760	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.
761		1036
762	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
763	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.
764		1039
765	=item * Erlang uses unprotected connections, AEMP uses secure	1040	=item * Erlang uses unprotected connections, AEMP uses secure
766	authentication and can use TLS.	1041	authentication and can use TLS.
767		1042
…		…
770		1045
771	=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
772	communications.	1047	communications.
773		1048
774	The AEMP protocol, unlike the Erlang protocol, supports both programming	1049	The AEMP protocol, unlike the Erlang protocol, supports both programming
775	language independent text-only protocols (good for debugging) and binary,	1050	language independent text-only protocols (good for debugging), and binary,
776	language-specific serialisers (e.g. Storable). By default, unless TLS is	1051	language-specific serialisers (e.g. Storable). By default, unless TLS is
777	used, the protocol is actually completely text-based.	1052	used, the protocol is actually completely text-based.
778		1053
779	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
780	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
781	protocol simple.	1056	protocol simple.
782		1057
783	=item * AEMP has more flexible monitoring options than Erlang.	1058	=item * AEMP has more flexible monitoring options than Erlang.
784		1059
785	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
786	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
787	difficult to implement. Monitoring in AEMP is more flexible than in	1062	difficult to implement.
788	Erlang, as one can choose between automatic kill, exit message or callback	1063
789	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.
790		1066
791	=item * Erlang tries to hide remote/local connections, AEMP does not.	1067	=item * Erlang tries to hide remote/local connections, AEMP does not.
792		1068
793	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
794	same way as linking is (except linking is unreliable in Erlang).	1070	same way as linking is (except linking is unreliable in Erlang).
…		…
816	overhead, as well as having to keep a proxy object everywhere.	1092	overhead, as well as having to keep a proxy object everywhere.
817		1093
818	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
819	procedures to be "valid".	1095	procedures to be "valid".
820		1096
821	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
822	global hash - it can't become much cheaper.	1098	code reference stored in a global hash - it can't become much cheaper.
823		1099
824	=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?
825		1101
826	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
827	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
…		…
843		1119
844	L<AnyEvent::MP::Intro> - a gentle introduction.	1120	L<AnyEvent::MP::Intro> - a gentle introduction.
845		1121
846	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1122	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
847		1123
848	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1124	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
849	your applications.	1125	your applications.
		1126
		1127	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
		1128
		1129	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		1130	all nodes.
850		1131
851	L<AnyEvent>.	1132	L<AnyEvent>.
852		1133
853	=head1 AUTHOR	1134	=head1 AUTHOR
854		1135

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing cvsroot/AnyEvent-MP/MP.pm (file contents): Revision 1.78 by root, Thu Sep 3 20:16:36 2009 UTC vs. Revision 1.127 by root, Sat Mar 3 20:35:10 2012 UTC

Diff Legend

Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.78 by root, Thu Sep 3 20:16:36 2009 UTC vs.
Revision 1.127 by root, Sat Mar 3 20:35:10 2012 UTC