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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.72 by root, Mon Aug 31 10:07:04 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
9	$NODE # contains this node's noderef	9	$NODE # contains this node's node ID
10	NODE # returns this node's noderef	10	NODE # returns this node's node ID
11	NODE $port # returns the noderef of the port
12		11
13	$SELF # receiving/own port id in rcv callbacks	12	$SELF # receiving/own port id in rcv callbacks
14		13
15	# initialise the node so it can send/receive messages	14	# initialise the node so it can send/receive messages
16	configure;	15	configure;
17		16
18	# ports are message endpoints	17	# ports are message destinations
19		18
20	# sending messages	19	# sending messages
21	snd $port, type => data...;	20	snd $port, type => data...;
22	snd $port, @msg;	21	snd $port, @msg;
23	snd @msg_with_first_element_being_a_port;	22	snd @msg_with_first_element_being_a_port;
24		23
25	# creating/using ports, the simple way	24	# creating/using ports, the simple way
26	my $simple_port = port { my @msg = @_; 0 };	25	my $simple_port = port { my @msg = @_ };
27		26
28	# creating/using ports, tagged message matching	27	# creating/using ports, tagged message matching
29	my $port = port;	28	my $port = port;
30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
31	rcv $port, pong => sub { warn "pong received\n"; 0 };	30	rcv $port, pong => sub { warn "pong received\n" };
32		31
33	# create a port on another node	32	# create a port on another node
34	my $port = spawn $node, $initfunc, @initdata;	33	my $port = spawn $node, $initfunc, @initdata;
35		34
		35	# destroy a port again
		36	kil $port; # "normal" kill
		37	kil $port, my_error => "everything is broken"; # error kill
		38
36	# monitoring	39	# monitoring
37	mon $port, $cb->(@msg) # callback is invoked on death	40	mon $localport, $cb->(@msg) # callback is invoked on death
38	mon $port, $otherport # kill otherport on abnormal death	41	mon $localport, $otherport # kill otherport on abnormal death
39	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	};
40		51
41	=head1 CURRENT STATUS	52	=head1 CURRENT STATUS
42		53
43	bin/aemp - stable.	54	bin/aemp - stable.
44	AnyEvent::MP - stable API, should work.	55	AnyEvent::MP - stable API, should work.
45	AnyEvent::MP::Intro - uptodate, but incomplete.	56	AnyEvent::MP::Intro - explains most concepts.
46	AnyEvent::MP::Kernel - mostly stable.	57	AnyEvent::MP::Kernel - mostly stable API.
47	AnyEvent::MP::Global - stable API, protocol not yet final.	58	AnyEvent::MP::Global - stable API.
48
49	stay tuned.
50		59
51	=head1 DESCRIPTION	60	=head1 DESCRIPTION
52		61
53	This module (-family) implements a simple message passing framework.	62	This module (-family) implements a simple message passing framework.
54		63
56	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.
57		66
58	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>
59	manual page and the examples under F<eg/>.	68	manual page and the examples under F<eg/>.
60		69
61	At the moment, this module family is a bit underdocumented.
62
63	=head1 CONCEPTS	70	=head1 CONCEPTS
64		71
65	=over 4	72	=over 4
66		73
67	=item port	74	=item port
68		75
69	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).
70		78
71	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
72	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
73	anything was listening for them or not.	81	anything was listening for them or not.
74		82
		83	Ports are represented by (printable) strings called "port IDs".
		84
75	=item port ID - C<nodeid#portname>	85	=item port ID - C<nodeid#portname>
76		86
77	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<#>)
78	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).
79		90
80	=item node	91	=item node
81		92
82	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,
83	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
84	ports.	95	ports.
85		96
86	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
87	(no listening ports). Private nodes cannot talk to other private nodes	98	(no listening ports). Private nodes cannot talk to other private nodes
88	currently.	99	currently, but all nodes can talk to public nodes.
89		100
		101	Nodes is represented by (printable) strings called "node IDs".
		102
90	=item node ID - C<[a-za-Z0-9_\-.:]+>	103	=item node ID - C<[A-Za-z0-9_\-.:]*>
91		104
92	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
93	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
94	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
95	doesn't interpret node IDs in any way.	108	doesn't interpret node IDs in any way except to uniquely identify a node.
96		109
97	=item binds - C<ip:port>	110	=item binds - C<ip:port>
98		111
99	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
100	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
101	endpoints - binds. Currently, only standard C<ip:port> specifications can	116	Currently, only standard C<ip:port> specifications can be used, which
102	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.
103		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
104	=item seeds - C<host:port>	149	=item seed IDs - C<host:port>
105		150
106	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
107	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.
108	network. This node is called a seed.
109		153
110	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	154	=item global nodes
111	are expected to be long-running, and at least one of those should always
112	be available. When nodes run out of connections (e.g. due to a network
113	error), they try to re-establish connections to some seednodes again to
114	join the network.
115		155
116	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
117	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).
118		170
119	=back	171	=back
120		172
121	=head1 VARIABLES/FUNCTIONS	173	=head1 VARIABLES/FUNCTIONS
122		174
…		…
124		176
125	=cut	177	=cut
126		178
127	package AnyEvent::MP;	179	package AnyEvent::MP;
128		180
		181	use AnyEvent::MP::Config ();
129	use AnyEvent::MP::Kernel;	182	use AnyEvent::MP::Kernel;
		183	use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID);
130		184
131	use common::sense;	185	use common::sense;
132		186
133	use Carp ();	187	use Carp ();
134		188
135	use AE ();	189	use AE ();
136		190
137	use base "Exporter";	191	use base "Exporter";
138		192
139	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	193	our $VERSION = $AnyEvent::MP::Config::VERSION;
140		194
141	our @EXPORT = qw(	195	our @EXPORT = qw(
142	NODE $NODE *SELF node_of after	196	NODE $NODE *SELF node_of after
143	configure	197	configure
144	snd rcv mon mon_guard kil reg psub spawn	198	snd rcv mon mon_guard kil psub peval spawn cal
145	port	199	port
146	);	200	);
147		201
148	our $SELF;	202	our $SELF;
149		203
…		…
161		215
162	=item $nodeid = node_of $port	216	=item $nodeid = node_of $port
163		217
164	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.
165		219
		220	=item configure $profile, key => value...
		221
166	=item configure key => value...	222	=item configure key => value...
167		223
168	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
169	"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
170	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
171	some other nodes in the network to discover other nodes.	227	some other nodes in the network to discover other nodes.
172		228
173	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
174	never) before calling other AnyEvent::MP functions.	230	never) before calling other AnyEvent::MP functions.
175		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
176	=over 4	251	=over 4
177		252
178	=item step 1, gathering configuration from profiles	253	=item step 1, gathering configuration from profiles
179		254
180	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
181	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
182	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
183	-n>) will be used as profile name.	258	missing, then the nodename (F<uname -n>) will be used as profile name.
184		259
185	The profile data is then gathered as follows:	260	The profile data is then gathered as follows:
186		261
187	First, all remaining key => value pairs (all of which are conviniently	262	First, all remaining key => value pairs (all of which are conveniently
188	undocumented at the moment) will be interpreted as configuration	263	undocumented at the moment) will be interpreted as configuration
189	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
190	default configuration (see the F<aemp> utility), then the chain of	265	default configuration (see the F<aemp> utility), then the chain of
191	profiles chosen by the profile name (and any C<parent> attributes).	266	profiles chosen by the profile name (and any C<parent> attributes).
192		267
193	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
194	and the values specified directly via C<configure> have lowest priority,	269	and the values specified directly via C<configure> have lowest priority,
195	and can only be used to specify defaults.	270	and can only be used to specify defaults.
196		271
197	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
198	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
199	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.
200		278
201	=item step 2, bind listener sockets	279	=item step 2, bind listener sockets
202		280
203	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
204	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
…		…
210	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
211	local IP address it finds.	289	local IP address it finds.
212		290
213	=item step 3, connect to seed nodes	291	=item step 3, connect to seed nodes
214		292
215	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
216	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
217	connectivity with at least one node at any point in time.	295	connectivity with at least one node at any point in time.
218		296
219	=back	297	=back
220		298
221	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.
222	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.
223		301
224	configure	302	configure
225		303
226	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
227	clients.	305	clients.
228		306
229	configure nodeid => "anon/";	307	configure nodeid => "anon/";
230		308
231	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
232	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,
233	customary for aemp).	311	customary for aemp).
234		312
235	# use the aemp commandline utility	313	# use the aemp commandline utility
236	# aemp profile seed setnodeid anon/ setbinds '*:4040'	314	# aemp profile seed binds '*:4040'
237		315
238	# then use it	316	# then use it
239	configure profile => "seed";	317	configure profile => "seed";
240		318
241	# or simply use aemp from the shell again:	319	# or simply use aemp from the shell again:
…		…
311	sub _kilme {	389	sub _kilme {
312	die "received message on port without callback";	390	die "received message on port without callback";
313	}	391	}
314		392
315	sub port(;&) {	393	sub port(;&) {
316	my $id = "$UNIQ." . $ID++;	394	my $id = $UNIQ . ++$ID;
317	my $port = "$NODE#$id";	395	my $port = "$NODE#$id";
318		396
319	rcv $port, shift \|\| \&_kilme;	397	rcv $port, shift \|\| \&_kilme;
320		398
321	$port	399	$port
…		…
360	msg1 => sub { ... },	438	msg1 => sub { ... },
361	...	439	...
362	;	440	;
363		441
364	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
365	(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.
366		444
367	rcv $port, $otherport => sub {	445	rcv $port, $otherport => sub {
368	my @reply = @_;	446	my @reply = @_;
369		447
370	rcv $SELF, $otherport;	448	rcv $SELF, $otherport;
…		…
372		450
373	=cut	451	=cut
374		452
375	sub rcv($@) {	453	sub rcv($@) {
376	my $port = shift;	454	my $port = shift;
377	my ($noderef, $portid) = split /#/, $port, 2;	455	my ($nodeid, $portid) = split /#/, $port, 2;
378		456
379	$NODE{$noderef} == $NODE{""}	457	$NODE{$nodeid} == $NODE{""}
380	or Carp::croak "$port: rcv can only be called on local ports, caught";	458	or Carp::croak "$port: rcv can only be called on local ports, caught";
381		459
382	while (@_) {	460	while (@_) {
383	if (ref $_[0]) {	461	if (ref $_[0]) {
384	if (my $self = $PORT_DATA{$portid}) {	462	if (my $self = $PORT_DATA{$portid}) {
385	"AnyEvent::MP::Port" eq ref $self	463	"AnyEvent::MP::Port" eq ref $self
386	or Carp::croak "$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";
387		465
388	$self->[2] = shift;	466	$self->[0] = shift;
389	} else {	467	} else {
390	my $cb = shift;	468	my $cb = shift;
391	$PORT{$portid} = sub {	469	$PORT{$portid} = sub {
392	local $SELF = $port;	470	local $SELF = $port;
393	eval { &$cb }; _self_die if $@;	471	eval { &$cb }; _self_die if $@;
394	};	472	};
395	}	473	}
396	} elsif (defined $_[0]) {	474	} elsif (defined $_[0]) {
397	my $self = $PORT_DATA{$portid} \|\|= do {	475	my $self = $PORT_DATA{$portid} \|\|= do {
398	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	476	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
399		477
400	$PORT{$portid} = sub {	478	$PORT{$portid} = sub {
401	local $SELF = $port;	479	local $SELF = $port;
402		480
403	if (my $cb = $self->[1]{$_[0]}) {	481	if (my $cb = $self->[1]{$_[0]}) {
…		…
425	}	503	}
426		504
427	$port	505	$port
428	}	506	}
429		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
430	=item $closure = psub { BLOCK }	545	=item $closure = psub { BLOCK }
431		546
432	Remembers C<$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
433	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>
434	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 $SELF, sub {
		552	BLOCK }, @_ } >>.
435		553
436	This is useful when you register callbacks from C<rcv> callbacks:	554	This is useful when you register callbacks from C<rcv> callbacks:
437		555
438	rcv delayed_reply => sub {	556	rcv delayed_reply => sub {
439	my ($delay, @reply) = @_;	557	my ($delay, @reply) = @_;
…		…
475		593
476	Monitor the given port and do something when the port is killed or	594	Monitor the given port and do something when the port is killed or
477	messages to it were lost, and optionally return a guard that can be used	595	messages to it were lost, and optionally return a guard that can be used
478	to stop monitoring again.	596	to stop monitoring again.
479		597
		598	In the first form (callback), the callback is simply called with any
		599	number of C<@reason> elements (no @reason means that the port was deleted
		600	"normally"). Note also that I<< the callback B<must> never die >>, so use
		601	C<eval> if unsure.
		602
		603	In the second form (another port given), the other port (C<$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
480	C<mon> effectively guarantees that, in the absence of hardware failures,	624	C<mon> effectively guarantees that, in the absence of hardware failures,
481	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
482	arrive, or the monitoring action will be invoked after possible message	626	arrive, or the monitoring action will be invoked after possible message
483	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
484	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
485	port). After the monitoring action was invoked, further messages might get	629	port). After the monitoring action was invoked, further messages might get
486	delivered again.	630	delivered again.
487		631
488	Note that monitoring-actions are one-shot: once messages are lost (and a	632	Inter-host-connection timeouts and monitoring depend on the transport
489	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).
490		636
491	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
492	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
493	"normally"). Note also that I<< the callback B<must> never die >>, so use	639	to ensure some maximum latency.
494	C<eval> if unsure.
495
496	In the second form (another port given), the other port (C<$rcvport>)
497	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
498	"normal" kils nothing happens, while under all other conditions, the other
499	port is killed with the same reason.
500
501	The third form (kill self) is the same as the second form, except that
502	C<$rvport> defaults to C<$SELF>.
503
504	In the last form (message), a message of the form C<@msg, @reason> will be
505	C<snd>.
506
507	As a rule of thumb, monitoring requests should always monitor a port from
508	a local port (or callback). The reason is that kill messages might get
509	lost, just like any other message. Another less obvious reason is that
510	even monitoring requests can get lost (for exmaple, when the connection
511	to the other node goes down permanently). When monitoring a port locally
512	these problems do not exist.
513		640
514	Example: call a given callback when C<$port> is killed.	641	Example: call a given callback when C<$port> is killed.
515		642
516	mon $port, sub { warn "port died because of <@_>\n" };	643	mon $port, sub { warn "port died because of <@_>\n" };
517		644
…		…
524	mon $port, $self => "restart";	651	mon $port, $self => "restart";
525		652
526	=cut	653	=cut
527		654
528	sub mon {	655	sub mon {
529	my ($noderef, $port) = split /#/, shift, 2;	656	my ($nodeid, $port) = split /#/, shift, 2;
530		657
531	my $node = $NODE{$noderef} \|\| add_node $noderef;	658	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
532		659
533	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	660	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
534		661
535	unless (ref $cb) {	662	unless (ref $cb) {
536	if (@_) {	663	if (@_) {
…		…
545	}	672	}
546		673
547	$node->monitor ($port, $cb);	674	$node->monitor ($port, $cb);
548		675
549	defined wantarray	676	defined wantarray
550	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	677	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
551	}	678	}
552		679
553	=item $guard = mon_guard $port, $ref, $ref...	680	=item $guard = mon_guard $port, $ref, $ref...
554		681
555	Monitors the given C<$port> and keeps the passed references. When the port	682	Monitors the given C<$port> and keeps the passed references. When the port
…		…
578		705
579	=item kil $port[, @reason]	706	=item kil $port[, @reason]
580		707
581	Kill the specified port with the given C<@reason>.	708	Kill the specified port with the given C<@reason>.
582		709
583	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" -
584	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
585	"normally").	712	(C<mon $mport, $lport> form) to get killed.
586		713
587	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>
588	C<mon>, see above).	715	form) get killed with the same reason.
589		716
590	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
591	will be reported as reason C<< die => $@ >>.	718	will be reported as reason C<< die => $@ >>.
592		719
593	Transport/communication errors are reported as C<< transport_error =>	720	Transport/communication errors are reported as C<< transport_error =>
…		…
612	the package, then the package above the package and so on (e.g.	739	the package, then the package above the package and so on (e.g.
613	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	740	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
614	exists or it runs out of package names.	741	exists or it runs out of package names.
615		742
616	The init function is then called with the newly-created port as context	743	The init function is then called with the newly-created port as context
617	object (C<$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.
618		747
619	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
620	port, and in the remote init function, immediately monitor the passed	749	port, and in the remote init function, immediately monitor the passed
621	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
622	when there is a problem.	751	when there is a problem.
623		752
		753	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		754	caller before C<spawn> returns (by delaying invocation when spawn is
		755	called for the local node).
		756
624	Example: spawn a chat server port on C<$othernode>.	757	Example: spawn a chat server port on C<$othernode>.
625		758
626	# this node, executed from within a port context:	759	# this node, executed from within a port context:
627	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	760	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
628	mon $server;	761	mon $server;
…		…
642		775
643	sub _spawn {	776	sub _spawn {
644	my $port = shift;	777	my $port = shift;
645	my $init = shift;	778	my $init = shift;
646		779
		780	# rcv will create the actual port
647	local $SELF = "$NODE#$port";	781	local $SELF = "$NODE#$port";
648	eval {	782	eval {
649	&{ load_func $init }	783	&{ load_func $init }
650	};	784	};
651	_self_die if $@;	785	_self_die if $@;
652	}	786	}
653		787
654	sub spawn(@) {	788	sub spawn(@) {
655	my ($noderef, undef) = split /#/, shift, 2;	789	my ($nodeid, undef) = split /#/, shift, 2;
656		790
657	my $id = "$RUNIQ." . $ID++;	791	my $id = $RUNIQ . ++$ID;
658		792
659	$_[0] =~ /::/	793	$_[0] =~ /::/
660	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";
661		795
662	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	796	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
663		797
664	"$noderef#$id"	798	"$nodeid#$id"
665	}	799	}
		800
666		801
667	=item after $timeout, @msg	802	=item after $timeout, @msg
668		803
669	=item after $timeout, $callback	804	=item after $timeout, $callback
670		805
…		…
686	? $action[0]()	821	? $action[0]()
687	: snd @action;	822	: snd @action;
688	};	823	};
689	}	824	}
690		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
691	=back	878	=back
692		879
693	=head1 AnyEvent::MP vs. Distributed Erlang	880	=head1 AnyEvent::MP vs. Distributed Erlang
694		881
695	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
696	== 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
697	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
698	sample:	885	sample:
699		886
700	http://www.Erlang.se/doc/programming_rules.shtml	887	http://www.erlang.se/doc/programming_rules.shtml
701	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
702	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
703	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
704		891
705	Despite the similarities, there are also some important differences:	892	Despite the similarities, there are also some important differences:
706		893
707	=over 4	894	=over 4
708		895
709	=item * Node IDs are arbitrary strings in AEMP.	896	=item * Node IDs are arbitrary strings in AEMP.
710		897
711	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
712	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
713	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.
714		902
715	=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
716	uses "local ports are like remote ports".	904	uses "local ports are like remote ports".
717		905
718	The failure modes for local ports are quite different (runtime errors	906	The failure modes for local ports are quite different (runtime errors
…		…
727	ports being the special case/exception, where transport errors cannot	915	ports being the special case/exception, where transport errors cannot
728	occur.	916	occur.
729		917
730	=item * Erlang uses processes and a mailbox, AEMP does not queue.	918	=item * Erlang uses processes and a mailbox, AEMP does not queue.
731		919
732	Erlang uses processes that selectively receive messages, and therefore	920	Erlang uses processes that selectively receive messages out of order, and
733	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
734	useful purpose. For the same reason the pattern-matching abilities of	922	no useful purpose. For the same reason the pattern-matching abilities
735	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
736	filter messages without dequeing them.	924	filter messages without dequeuing them.
737		925
738	(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.
739		931
740	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	932	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
741		933
742	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
743	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
744	connection establishment is handled in the background.	937	establishment is handled in the background.
745		938
746	=item * Erlang suffers from silent message loss, AEMP does not.	939	=item * Erlang suffers from silent message loss, AEMP does not.
747		940
748	Erlang makes few guarantees on messages delivery - messages can get lost	941	Erlang implements few guarantees on messages delivery - messages can get
749	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,
750	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).
751		944
752	AEMP guarantees correct ordering, and the guarantee that after one message	945	AEMP guarantees (modulo hardware errors) correct ordering, and the
753	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
754	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
755	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.
756		954
757	=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.
758		956
759	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
760	known to other nodes for a completely different process, causing messages	958	process ID known to other nodes for a completely different process,
761	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.
762		961
763	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
764	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.
765		964
766	=item * Erlang uses unprotected connections, AEMP uses secure	965	=item * Erlang uses unprotected connections, AEMP uses secure
767	authentication and can use TLS.	966	authentication and can use TLS.
768		967
…		…
771		970
772	=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
773	communications.	972	communications.
774		973
775	The AEMP protocol, unlike the Erlang protocol, supports both programming	974	The AEMP protocol, unlike the Erlang protocol, supports both programming
776	language independent text-only protocols (good for debugging) and binary,	975	language independent text-only protocols (good for debugging), and binary,
777	language-specific serialisers (e.g. Storable). By default, unless TLS is	976	language-specific serialisers (e.g. Storable). By default, unless TLS is
778	used, the protocol is actually completely text-based.	977	used, the protocol is actually completely text-based.
779		978
780	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
781	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
782	protocol simple.	981	protocol simple.
783		982
784	=item * AEMP has more flexible monitoring options than Erlang.	983	=item * AEMP has more flexible monitoring options than Erlang.
785		984
786	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
787	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
788	difficult to implement. Monitoring in AEMP is more flexible than in	987	difficult to implement.
789	Erlang, as one can choose between automatic kill, exit message or callback	988
790	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.
791		991
792	=item * Erlang tries to hide remote/local connections, AEMP does not.	992	=item * Erlang tries to hide remote/local connections, AEMP does not.
793		993
794	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
795	same way as linking is (except linking is unreliable in Erlang).	995	same way as linking is (except linking is unreliable in Erlang).
…		…
817	overhead, as well as having to keep a proxy object everywhere.	1017	overhead, as well as having to keep a proxy object everywhere.
818		1018
819	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
820	procedures to be "valid".	1020	procedures to be "valid".
821		1021
822	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
823	global hash - it can't become much cheaper.	1023	code reference stored in a global hash - it can't become much cheaper.
824		1024
825	=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?
826		1026
827	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
828	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
…		…
844		1044
845	L<AnyEvent::MP::Intro> - a gentle introduction.	1045	L<AnyEvent::MP::Intro> - a gentle introduction.
846		1046
847	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1047	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
848		1048
849	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1049	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
850	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.
851		1056
852	L<AnyEvent>.	1057	L<AnyEvent>.
853		1058
854	=head1 AUTHOR	1059	=head1 AUTHOR
855		1060

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.72 by root, Mon Aug 31 10:07:04 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 1.72 by root, Mon Aug 31 10:07:04 2009 UTC vs.
Revision 1.123 by root, Thu Mar 1 19:37:59 2012 UTC