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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.75 by root, Mon Aug 31 13:18:06 2009 UTC vs.
Revision 1.123 by root, Thu Mar 1 19:37:59 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 - uptodate, but incomplete.	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
…		…
55	on the same or other hosts, and you can supervise entities remotely.	65	on the same or other hosts, and you can supervise entities remotely.
56		66
57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	67	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
58	manual page and the examples under F<eg/>.	68	manual page and the examples under F<eg/>.
59		69
60	At the moment, this module family is a bit underdocumented.
61
62	=head1 CONCEPTS	70	=head1 CONCEPTS
63		71
64	=over 4	72	=over 4
65		73
66	=item port	74	=item port
67		75
68	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).
69		78
70	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
71	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
72	anything was listening for them or not.	81	anything was listening for them or not.
73		82
		83	Ports are represented by (printable) strings called "port IDs".
		84
74	=item port ID - C<nodeid#portname>	85	=item port ID - C<nodeid#portname>
75		86
76	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<#>)
77	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).
78		90
79	=item node	91	=item node
80		92
81	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,
82	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
83	ports.	95	ports.
84		96
85	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
86	(no listening ports). Private nodes cannot talk to other private nodes	98	(no listening ports). Private nodes cannot talk to other private nodes
87	currently.	99	currently, but all nodes can talk to public nodes.
88		100
		101	Nodes is represented by (printable) strings called "node IDs".
		102
89	=item node ID - C<[a-za-Z0-9_\-.:]+>	103	=item node ID - C<[A-Za-z0-9_\-.:]*>
90		104
91	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
92	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
93	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
94	doesn't interpret node IDs in any way.	108	doesn't interpret node IDs in any way except to uniquely identify a node.
95		109
96	=item binds - C<ip:port>	110	=item binds - C<ip:port>
97		111
98	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
99	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
100	endpoints - binds. Currently, only standard C<ip:port> specifications can	116	Currently, only standard C<ip:port> specifications can be used, which
101	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.
102		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
103	=item seeds - C<host:port>	149	=item seed IDs - C<host:port>
104		150
105	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
106	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.
107	network. This node is called a seed.
108		153
109	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	154	=item global nodes
110	are expected to be long-running, and at least one of those should always
111	be available. When nodes run out of connections (e.g. due to a network
112	error), they try to re-establish connections to some seednodes again to
113	join the network.
114		155
115	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
116	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).
117		170
118	=back	171	=back
119		172
120	=head1 VARIABLES/FUNCTIONS	173	=head1 VARIABLES/FUNCTIONS
121		174
…		…
123		176
124	=cut	177	=cut
125		178
126	package AnyEvent::MP;	179	package AnyEvent::MP;
127		180
		181	use AnyEvent::MP::Config ();
128	use AnyEvent::MP::Kernel;	182	use AnyEvent::MP::Kernel;
		183	use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID);
129		184
130	use common::sense;	185	use common::sense;
131		186
132	use Carp ();	187	use Carp ();
133		188
134	use AE ();	189	use AE ();
135		190
136	use base "Exporter";	191	use base "Exporter";
137		192
138	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	193	our $VERSION = $AnyEvent::MP::Config::VERSION;
139		194
140	our @EXPORT = qw(	195	our @EXPORT = qw(
141	NODE $NODE *SELF node_of after	196	NODE $NODE *SELF node_of after
142	configure	197	configure
143	snd rcv mon mon_guard kil reg psub spawn	198	snd rcv mon mon_guard kil psub peval spawn cal
144	port	199	port
145	);	200	);
146		201
147	our $SELF;	202	our $SELF;
148		203
…		…
160		215
161	=item $nodeid = node_of $port	216	=item $nodeid = node_of $port
162		217
163	Extracts and returns the node ID from a port ID or a node ID.	218	Extracts and returns the node ID from a port ID or a node ID.
164		219
		220	=item configure $profile, key => value...
		221
165	=item configure key => value...	222	=item configure key => value...
166		223
167	Before a node can talk to other nodes on the network (i.e. enter	224	Before a node can talk to other nodes on the network (i.e. enter
168	"distributed mode") it has to configure itself - the minimum a node needs	225	"distributed mode") it has to configure itself - the minimum a node needs
169	to know is its own name, and optionally it should know the addresses of	226	to know is its own name, and optionally it should know the addresses of
170	some other nodes in the network to discover other nodes.	227	some other nodes in the network to discover other nodes.
171		228
172	This function configures a node - it must be called exactly once (or	229	This function configures a node - it must be called exactly once (or
173	never) before calling other AnyEvent::MP functions.	230	never) before calling other AnyEvent::MP functions.
174		231
		232	The key/value pairs are basically the same ones as documented for the
		233	F<aemp> command line utility (sans the set/del prefix), with two additions:
		234
		235	=over 4
		236
		237	=item norc => $boolean (default false)
		238
		239	If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not>
		240	be consulted - all configuraiton options must be specified in the
		241	C<configure> call.
		242
		243	=item force => $boolean (default false)
		244
		245	IF true, then the values specified in the C<configure> will take
		246	precedence over any values configured via the rc file. The default is for
		247	the rc file to override any options specified in the program.
		248
		249	=back
		250
175	=over 4	251	=over 4
176		252
177	=item step 1, gathering configuration from profiles	253	=item step 1, gathering configuration from profiles
178		254
179	The function first looks up a profile in the aemp configuration (see the	255	The function first looks up a profile in the aemp configuration (see the
180	L<aemp> commandline utility). The profile name can be specified via the	256	L<aemp> commandline utility). The profile name can be specified via the
181	named C<profile> parameter. If it is missing, then the nodename (F<uname	257	named C<profile> parameter or can simply be the first parameter). If it is
182	-n>) will be used as profile name.	258	missing, then the nodename (F<uname -n>) will be used as profile name.
183		259
184	The profile data is then gathered as follows:	260	The profile data is then gathered as follows:
185		261
186	First, all remaining key => value pairs (all of which are conviniently	262	First, all remaining key => value pairs (all of which are conveniently
187	undocumented at the moment) will be interpreted as configuration	263	undocumented at the moment) will be interpreted as configuration
188	data. Then they will be overwritten by any values specified in the global	264	data. Then they will be overwritten by any values specified in the global
189	default configuration (see the F<aemp> utility), then the chain of	265	default configuration (see the F<aemp> utility), then the chain of
190	profiles chosen by the profile name (and any C<parent> attributes).	266	profiles chosen by the profile name (and any C<parent> attributes).
191		267
192	That means that the values specified in the profile have highest priority	268	That means that the values specified in the profile have highest priority
193	and the values specified directly via C<configure> have lowest priority,	269	and the values specified directly via C<configure> have lowest priority,
194	and can only be used to specify defaults.	270	and can only be used to specify defaults.
195		271
196	If the profile specifies a node ID, then this will become the node ID of	272	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	273	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.	274	a slash (C</>) attached.
		275
		276	If the node ID (or profile name) ends with a slash (C</>), then a random
		277	string is appended to make it unique.
199		278
200	=item step 2, bind listener sockets	279	=item step 2, bind listener sockets
201		280
202	The next step is to look up the binds in the profile, followed by binding	281	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	282	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	288	used, meaning the node will bind on a dynamically-assigned port on every
210	local IP address it finds.	289	local IP address it finds.
211		290
212	=item step 3, connect to seed nodes	291	=item step 3, connect to seed nodes
213		292
214	As the last step, the seeds list from the profile is passed to the	293	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	294	L<AnyEvent::MP::Global> module, which will then use it to keep
216	connectivity with at least one node at any point in time.	295	connectivity with at least one node at any point in time.
217		296
218	=back	297	=back
219		298
220	Example: become a distributed node using the locla node name as profile.	299	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.	300	This should be the most common form of invocation for "daemon"-type nodes.
222		301
223	configure	302	configure
224		303
225	Example: become an anonymous node. This form is often used for commandline	304	Example: become an anonymous node. This form is often used for commandline
226	clients.	305	clients.
227		306
228	configure nodeid => "anon/";	307	configure nodeid => "anon/";
229		308
230	Example: configure a node using a profile called seed, which si suitable	309	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,	310	for a seed node as it binds on all local addresses on a fixed port (4040,
232	customary for aemp).	311	customary for aemp).
233		312
234	# use the aemp commandline utility	313	# use the aemp commandline utility
235	# aemp profile seed nodeid anon/ binds '*:4040'	314	# aemp profile seed binds '*:4040'
236		315
237	# then use it	316	# then use it
238	configure profile => "seed";	317	configure profile => "seed";
239		318
240	# or simply use aemp from the shell again:	319	# or simply use aemp from the shell again:
…		…
310	sub _kilme {	389	sub _kilme {
311	die "received message on port without callback";	390	die "received message on port without callback";
312	}	391	}
313		392
314	sub port(;&) {	393	sub port(;&) {
315	my $id = "$UNIQ." . $ID++;	394	my $id = $UNIQ . ++$ID;
316	my $port = "$NODE#$id";	395	my $port = "$NODE#$id";
317		396
318	rcv $port, shift \|\| \&_kilme;	397	rcv $port, shift \|\| \&_kilme;
319		398
320	$port	399	$port
…		…
359	msg1 => sub { ... },	438	msg1 => sub { ... },
360	...	439	...
361	;	440	;
362		441
363	Example: temporarily register a rcv callback for a tag matching some port	442	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.	443	(e.g. for an rpc reply) and unregister it after a message was received.
365		444
366	rcv $port, $otherport => sub {	445	rcv $port, $otherport => sub {
367	my @reply = @_;	446	my @reply = @_;
368		447
369	rcv $SELF, $otherport;	448	rcv $SELF, $otherport;
…		…
382	if (ref $_[0]) {	461	if (ref $_[0]) {
383	if (my $self = $PORT_DATA{$portid}) {	462	if (my $self = $PORT_DATA{$portid}) {
384	"AnyEvent::MP::Port" eq ref $self	463	"AnyEvent::MP::Port" eq ref $self
385	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	464	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
386		465
387	$self->[2] = shift;	466	$self->[0] = shift;
388	} else {	467	} else {
389	my $cb = shift;	468	my $cb = shift;
390	$PORT{$portid} = sub {	469	$PORT{$portid} = sub {
391	local $SELF = $port;	470	local $SELF = $port;
392	eval { &$cb }; _self_die if $@;	471	eval { &$cb }; _self_die if $@;
393	};	472	};
394	}	473	}
395	} elsif (defined $_[0]) {	474	} elsif (defined $_[0]) {
396	my $self = $PORT_DATA{$portid} \|\|= do {	475	my $self = $PORT_DATA{$portid} \|\|= do {
397	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	476	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
398		477
399	$PORT{$portid} = sub {	478	$PORT{$portid} = sub {
400	local $SELF = $port;	479	local $SELF = $port;
401		480
402	if (my $cb = $self->[1]{$_[0]}) {	481	if (my $cb = $self->[1]{$_[0]}) {
…		…
424	}	503	}
425		504
426	$port	505	$port
427	}	506	}
428		507
		508	=item peval $port, $coderef[, @args]
		509
		510	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
		511	when the code throews an exception the C<$port> will be killed.
		512
		513	Any remaining args will be passed to the callback. Any return values will
		514	be returned to the caller.
		515
		516	This is useful when you temporarily want to execute code in the context of
		517	a port.
		518
		519	Example: create a port and run some initialisation code in it's context.
		520
		521	my $port = port { ... };
		522
		523	peval $port, sub {
		524	init
		525	or die "unable to init";
		526	};
		527
		528	=cut
		529
		530	sub peval($$) {
		531	local $SELF = shift;
		532	my $cb = shift;
		533
		534	if (wantarray) {
		535	my @res = eval { &$cb };
		536	_self_die if $@;
		537	@res
		538	} else {
		539	my $res = eval { &$cb };
		540	_self_die if $@;
		541	$res
		542	}
		543	}
		544
429	=item $closure = psub { BLOCK }	545	=item $closure = psub { BLOCK }
430		546
431	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	547	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>	548	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.	549	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		550
		551	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		552	BLOCK }, @_ } >>.
434		553
435	This is useful when you register callbacks from C<rcv> callbacks:	554	This is useful when you register callbacks from C<rcv> callbacks:
436		555
437	rcv delayed_reply => sub {	556	rcv delayed_reply => sub {
438	my ($delay, @reply) = @_;	557	my ($delay, @reply) = @_;
…		…
474		593
475	Monitor the given port and do something when the port is killed or	594	Monitor the given port and do something when the port is killed or
476	messages to it were lost, and optionally return a guard that can be used	595	messages to it were lost, and optionally return a guard that can be used
477	to stop monitoring again.	596	to stop monitoring again.
478		597
		598	In the first form (callback), the callback is simply called with any
		599	number of C<@reason> elements (no @reason means that the port was deleted
		600	"normally"). Note also that I<< the callback B<must> never die >>, so use
		601	C<eval> if unsure.
		602
		603	In the second form (another port given), the other port (C<$rcvport>)
		604	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
		605	"normal" kils nothing happens, while under all other conditions, the other
		606	port is killed with the same reason.
		607
		608	The third form (kill self) is the same as the second form, except that
		609	C<$rvport> defaults to C<$SELF>.
		610
		611	In the last form (message), a message of the form C<@msg, @reason> will be
		612	C<snd>.
		613
		614	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		615	alert was raised), they are removed and will not trigger again.
		616
		617	As a rule of thumb, monitoring requests should always monitor a port from
		618	a local port (or callback). The reason is that kill messages might get
		619	lost, just like any other message. Another less obvious reason is that
		620	even monitoring requests can get lost (for example, when the connection
		621	to the other node goes down permanently). When monitoring a port locally
		622	these problems do not exist.
		623
479	C<mon> effectively guarantees that, in the absence of hardware failures,	624	C<mon> effectively guarantees that, in the absence of hardware failures,
480	after starting the monitor, either all messages sent to the port will	625	after starting the monitor, either all messages sent to the port will
481	arrive, or the monitoring action will be invoked after possible message	626	arrive, or the monitoring action will be invoked after possible message
482	loss has been detected. No messages will be lost "in between" (after	627	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	628	the first lost message no further messages will be received by the
484	port). After the monitoring action was invoked, further messages might get	629	port). After the monitoring action was invoked, further messages might get
485	delivered again.	630	delivered again.
486		631
487	Note that monitoring-actions are one-shot: once messages are lost (and a	632	Inter-host-connection timeouts and monitoring depend on the transport
488	monitoring alert was raised), they are removed and will not trigger again.	633	used. The only transport currently implemented is TCP, and AnyEvent::MP
		634	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		635	non-idle connection, and usually around two hours for idle connections).
489		636
490	In the first form (callback), the callback is simply called with any	637	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	638	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	639	to ensure some maximum latency.
493	C<eval> if unsure.
494
495	In the second form (another port given), the other port (C<$rcvport>)
496	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
497	"normal" kils nothing happens, while under all other conditions, the other
498	port is killed with the same reason.
499
500	The third form (kill self) is the same as the second form, except that
501	C<$rvport> defaults to C<$SELF>.
502
503	In the last form (message), a message of the form C<@msg, @reason> will be
504	C<snd>.
505
506	As a rule of thumb, monitoring requests should always monitor a port from
507	a local port (or callback). The reason is that kill messages might get
508	lost, just like any other message. Another less obvious reason is that
509	even monitoring requests can get lost (for exmaple, when the connection
510	to the other node goes down permanently). When monitoring a port locally
511	these problems do not exist.
512		640
513	Example: call a given callback when C<$port> is killed.	641	Example: call a given callback when C<$port> is killed.
514		642
515	mon $port, sub { warn "port died because of <@_>\n" };	643	mon $port, sub { warn "port died because of <@_>\n" };
516		644
…		…
544	}	672	}
545		673
546	$node->monitor ($port, $cb);	674	$node->monitor ($port, $cb);
547		675
548	defined wantarray	676	defined wantarray
549	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	677	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
550	}	678	}
551		679
552	=item $guard = mon_guard $port, $ref, $ref...	680	=item $guard = mon_guard $port, $ref, $ref...
553		681
554	Monitors the given C<$port> and keeps the passed references. When the port	682	Monitors the given C<$port> and keeps the passed references. When the port
…		…
577		705
578	=item kil $port[, @reason]	706	=item kil $port[, @reason]
579		707
580	Kill the specified port with the given C<@reason>.	708	Kill the specified port with the given C<@reason>.
581		709
582	If no C<@reason> is specified, then the port is killed "normally" (ports	710	If no C<@reason> is specified, then the port is killed "normally" -
583	monitoring other ports will not necessarily die because a port dies	711	monitor callback will be invoked, but the kil will not cause linked ports
584	"normally").	712	(C<mon $mport, $lport> form) to get killed.
585		713
586	Otherwise, linked ports get killed with the same reason (second form of	714	If a C<@reason> is specified, then linked ports (C<mon $mport, $lport>
587	C<mon>, see above).	715	form) get killed with the same reason.
588		716
589	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	717	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
590	will be reported as reason C<< die => $@ >>.	718	will be reported as reason C<< die => $@ >>.
591		719
592	Transport/communication errors are reported as C<< transport_error =>	720	Transport/communication errors are reported as C<< transport_error =>
…		…
611	the package, then the package above the package and so on (e.g.	739	the package, then the package above the package and so on (e.g.
612	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	740	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
613	exists or it runs out of package names.	741	exists or it runs out of package names.
614		742
615	The init function is then called with the newly-created port as context	743	The init function is then called with the newly-created port as context
616	object (C<$SELF>) and the C<@initdata> values as arguments.	744	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		745	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		746	the port might not get created.
617		747
618	A common idiom is to pass a local port, immediately monitor the spawned	748	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	749	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	750	local port. This two-way monitoring ensures that both ports get cleaned up
621	when there is a problem.	751	when there is a problem.
622		752
		753	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		754	caller before C<spawn> returns (by delaying invocation when spawn is
		755	called for the local node).
		756
623	Example: spawn a chat server port on C<$othernode>.	757	Example: spawn a chat server port on C<$othernode>.
624		758
625	# this node, executed from within a port context:	759	# this node, executed from within a port context:
626	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	760	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
627	mon $server;	761	mon $server;
…		…
641		775
642	sub _spawn {	776	sub _spawn {
643	my $port = shift;	777	my $port = shift;
644	my $init = shift;	778	my $init = shift;
645		779
		780	# rcv will create the actual port
646	local $SELF = "$NODE#$port";	781	local $SELF = "$NODE#$port";
647	eval {	782	eval {
648	&{ load_func $init }	783	&{ load_func $init }
649	};	784	};
650	_self_die if $@;	785	_self_die if $@;
651	}	786	}
652		787
653	sub spawn(@) {	788	sub spawn(@) {
654	my ($nodeid, undef) = split /#/, shift, 2;	789	my ($nodeid, undef) = split /#/, shift, 2;
655		790
656	my $id = "$RUNIQ." . $ID++;	791	my $id = $RUNIQ . ++$ID;
657		792
658	$_[0] =~ /::/	793	$_[0] =~ /::/
659	or Carp::croak "spawn init function must be a fully-qualified name, caught";	794	or Carp::croak "spawn init function must be a fully-qualified name, caught";
660		795
661	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;	796	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
662		797
663	"$nodeid#$id"	798	"$nodeid#$id"
664	}	799	}
		800
665		801
666	=item after $timeout, @msg	802	=item after $timeout, @msg
667		803
668	=item after $timeout, $callback	804	=item after $timeout, $callback
669		805
…		…
685	? $action[0]()	821	? $action[0]()
686	: snd @action;	822	: snd @action;
687	};	823	};
688	}	824	}
689		825
		826	=item cal $port, @msg, $callback[, $timeout]
		827
		828	A simple form of RPC - sends a message to the given C<$port> with the
		829	given contents (C<@msg>), but adds a reply port to the message.
		830
		831	The reply port is created temporarily just for the purpose of receiving
		832	the reply, and will be C<kil>ed when no longer needed.
		833
		834	A reply message sent to the port is passed to the C<$callback> as-is.
		835
		836	If an optional time-out (in seconds) is given and it is not C<undef>,
		837	then the callback will be called without any arguments after the time-out
		838	elapsed and the port is C<kil>ed.
		839
		840	If no time-out is given (or it is C<undef>), then the local port will
		841	monitor the remote port instead, so it eventually gets cleaned-up.
		842
		843	Currently this function returns the temporary port, but this "feature"
		844	might go in future versions unless you can make a convincing case that
		845	this is indeed useful for something.
		846
		847	=cut
		848
		849	sub cal(@) {
		850	my $timeout = ref $_[-1] ? undef : pop;
		851	my $cb = pop;
		852
		853	my $port = port {
		854	undef $timeout;
		855	kil $SELF;
		856	&$cb;
		857	};
		858
		859	if (defined $timeout) {
		860	$timeout = AE::timer $timeout, 0, sub {
		861	undef $timeout;
		862	kil $port;
		863	$cb->();
		864	};
		865	} else {
		866	mon $_[0], sub {
		867	kil $port;
		868	$cb->();
		869	};
		870	}
		871
		872	push @_, $port;
		873	&snd;
		874
		875	$port
		876	}
		877
690	=back	878	=back
691		879
692	=head1 AnyEvent::MP vs. Distributed Erlang	880	=head1 AnyEvent::MP vs. Distributed Erlang
693		881
694	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	882	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	883	== 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	884	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
697	sample:	885	sample:
698		886
699	http://www.Erlang.se/doc/programming_rules.shtml	887	http://www.erlang.se/doc/programming_rules.shtml
700	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	888	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	889	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	890	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
703		891
704	Despite the similarities, there are also some important differences:	892	Despite the similarities, there are also some important differences:
705		893
706	=over 4	894	=over 4
707		895
708	=item * Node IDs are arbitrary strings in AEMP.	896	=item * Node IDs are arbitrary strings in AEMP.
709		897
710	Erlang relies on special naming and DNS to work everywhere in the same	898	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	899	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
712	configuraiton or DNS), but will otherwise discover other odes itself.	900	configuration or DNS), and possibly the addresses of some seed nodes, but
		901	will otherwise discover other nodes (and their IDs) itself.
713		902
714	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	903	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
715	uses "local ports are like remote ports".	904	uses "local ports are like remote ports".
716		905
717	The failure modes for local ports are quite different (runtime errors	906	The failure modes for local ports are quite different (runtime errors
…		…
726	ports being the special case/exception, where transport errors cannot	915	ports being the special case/exception, where transport errors cannot
727	occur.	916	occur.
728		917
729	=item * Erlang uses processes and a mailbox, AEMP does not queue.	918	=item * Erlang uses processes and a mailbox, AEMP does not queue.
730		919
731	Erlang uses processes that selectively receive messages, and therefore	920	Erlang uses processes that selectively receive messages out of order, and
732	needs a queue. AEMP is event based, queuing messages would serve no	921	therefore needs a queue. AEMP is event based, queuing messages would serve
733	useful purpose. For the same reason the pattern-matching abilities of	922	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	923	of AnyEvent::MP are more limited, as there is little need to be able to
735	filter messages without dequeing them.	924	filter messages without dequeuing them.
736		925
737	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	926	This is not a philosophical difference, but simply stems from AnyEvent::MP
		927	being event-based, while Erlang is process-based.
		928
		929	You cna have a look at L<Coro::MP> for a more Erlang-like process model on
		930	top of AEMP and Coro threads.
738		931
739	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	932	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
740		933
741	Sending messages in Erlang is synchronous and blocks the process (and	934	Sending messages in Erlang is synchronous and blocks the process until
		935	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,	936	need a queue that can overflow). AEMP sends return immediately, connection
743	connection establishment is handled in the background.	937	establishment is handled in the background.
744		938
745	=item * Erlang suffers from silent message loss, AEMP does not.	939	=item * Erlang suffers from silent message loss, AEMP does not.
746		940
747	Erlang makes few guarantees on messages delivery - messages can get lost	941	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,	942	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).	943	b, and c, and the other side only receives messages a and c).
750		944
751	AEMP guarantees correct ordering, and the guarantee that after one message	945	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	946	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	947	same port are lost as well, until monitoring raises an error, so there are
754	sequence.	948	no silent "holes" in the message sequence.
		949
		950	If you want your software to be very reliable, you have to cope with
		951	corrupted and even out-of-order messages in both Erlang and AEMP. AEMP
		952	simply tries to work better in common error cases, such as when a network
		953	link goes down.
755		954
756	=item * Erlang can send messages to the wrong port, AEMP does not.	955	=item * Erlang can send messages to the wrong port, AEMP does not.
757		956
758	In Erlang it is quite likely that a node that restarts reuses a process ID	957	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	958	process ID known to other nodes for a completely different process,
760	destined for that process to end up in an unrelated process.	959	causing messages destined for that process to end up in an unrelated
		960	process.
761		961
762	AEMP never reuses port IDs, so old messages or old port IDs floating	962	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.	963	around in the network will not be sent to an unrelated port.
764		964
765	=item * Erlang uses unprotected connections, AEMP uses secure	965	=item * Erlang uses unprotected connections, AEMP uses secure
766	authentication and can use TLS.	966	authentication and can use TLS.
767		967
…		…
770		970
771	=item * The AEMP protocol is optimised for both text-based and binary	971	=item * The AEMP protocol is optimised for both text-based and binary
772	communications.	972	communications.
773		973
774	The AEMP protocol, unlike the Erlang protocol, supports both programming	974	The AEMP protocol, unlike the Erlang protocol, supports both programming
775	language independent text-only protocols (good for debugging) and binary,	975	language independent text-only protocols (good for debugging), and binary,
776	language-specific serialisers (e.g. Storable). By default, unless TLS is	976	language-specific serialisers (e.g. Storable). By default, unless TLS is
777	used, the protocol is actually completely text-based.	977	used, the protocol is actually completely text-based.
778		978
779	It has also been carefully designed to be implementable in other languages	979	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	980	with a minimum of work while gracefully degrading functionality to make the
781	protocol simple.	981	protocol simple.
782		982
783	=item * AEMP has more flexible monitoring options than Erlang.	983	=item * AEMP has more flexible monitoring options than Erlang.
784		984
785	In Erlang, you can chose to receive I<all> exit signals as messages	985	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	986	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	987	difficult to implement.
788	Erlang, as one can choose between automatic kill, exit message or callback	988
789	on a per-process basis.	989	Monitoring in AEMP is more flexible than in Erlang, as one can choose
		990	between automatic kill, exit message or callback on a per-port basis.
790		991
791	=item * Erlang tries to hide remote/local connections, AEMP does not.	992	=item * Erlang tries to hide remote/local connections, AEMP does not.
792		993
793	Monitoring in Erlang is not an indicator of process death/crashes, in the	994	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).	995	same way as linking is (except linking is unreliable in Erlang).
…		…
816	overhead, as well as having to keep a proxy object everywhere.	1017	overhead, as well as having to keep a proxy object everywhere.
817		1018
818	Strings can easily be printed, easily serialised etc. and need no special	1019	Strings can easily be printed, easily serialised etc. and need no special
819	procedures to be "valid".	1020	procedures to be "valid".
820		1021
821	And as a result, a miniport consists of a single closure stored in a	1022	And as a result, a port with just a default receiver consists of a single
822	global hash - it can't become much cheaper.	1023	code reference stored in a global hash - it can't become much cheaper.
823		1024
824	=item Why favour JSON, why not a real serialising format such as Storable?	1025	=item Why favour JSON, why not a real serialising format such as Storable?
825		1026
826	In fact, any AnyEvent::MP node will happily accept Storable as framing	1027	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	1028	format, but currently there is no way to make a node use Storable by
…		…
843		1044
844	L<AnyEvent::MP::Intro> - a gentle introduction.	1045	L<AnyEvent::MP::Intro> - a gentle introduction.
845		1046
846	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1047	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
847		1048
848	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1049	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
849	your applications.	1050	your applications.
		1051
		1052	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
		1053
		1054	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		1055	all nodes.
850		1056
851	L<AnyEvent>.	1057	L<AnyEvent>.
852		1058
853	=head1 AUTHOR	1059	=head1 AUTHOR
854		1060

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.75 by root, Mon Aug 31 13:18:06 2009 UTC vs. Revision 1.123 by root, Thu Mar 1 19:37:59 2012 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.75 by root, Mon Aug 31 13:18:06 2009 UTC vs.
Revision 1.123 by root, Thu Mar 1 19:37:59 2012 UTC