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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.69 by root, Sun Aug 30 18:51:49 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	initialise_node;	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
		54	bin/aemp - stable.
43	AnyEvent::MP - stable API, should work	55	AnyEvent::MP - stable API, should work.
44	AnyEvent::MP::Intro - outdated	56	AnyEvent::MP::Intro - explains most concepts.
45	AnyEvent::MP::Kernel - mostly stable	57	AnyEvent::MP::Kernel - mostly stable API.
46	AnyEvent::MP::Global - mostly stable	58	AnyEvent::MP::Global - stable API.
47	AnyEvent::MP::Node - mostly stable, but internal anyways
48	AnyEvent::MP::Transport - mostly stable, but internal anyways
49
50	stay tuned.
51		59
52	=head1 DESCRIPTION	60	=head1 DESCRIPTION
53		61
54	This module (-family) implements a simple message passing framework.	62	This module (-family) implements a simple message passing framework.
55		63
57	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.
58		66
59	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>
60	manual page and the examples under F<eg/>.	68	manual page and the examples under F<eg/>.
61		69
62	At the moment, this module family is a bit underdocumented.
63
64	=head1 CONCEPTS	70	=head1 CONCEPTS
65		71
66	=over 4	72	=over 4
67		73
68	=item port	74	=item port
69		75
70	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).
71		78
72	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
73	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
74	anything was listening for them or not.	81	anything was listening for them or not.
75		82
		83	Ports are represented by (printable) strings called "port IDs".
		84
76	=item port ID - C<nodeid#portname>	85	=item port ID - C<nodeid#portname>
77		86
78	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<#>)
79	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).
80		90
81	=item node	91	=item node
82		92
83	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,
84	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
85	ports.	95	ports.
86		96
87	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
88	(no listening ports). Private nodes cannot talk to other private nodes	98	(no listening ports). Private nodes cannot talk to other private nodes
89	currently.	99	currently, but all nodes can talk to public nodes.
90		100
		101	Nodes is represented by (printable) strings called "node IDs".
		102
91	=item node ID - C<[a-za-Z0-9_\-.:]+>	103	=item node ID - C<[A-Za-z0-9_\-.:]*>
92		104
93	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
94	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
95	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
96	doesn't interpret node IDs in any way.	108	doesn't interpret node IDs in any way except to uniquely identify a node.
97		109
98	=item binds - C<ip:port>	110	=item binds - C<ip:port>
99		111
100	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
101	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
102	endpoints - binds. Currently, only standard C<ip:port> specifications can	116	Currently, only standard C<ip:port> specifications can be used, which
103	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.
104		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
105	=item seeds - C<host:port>	149	=item seed IDs - C<host:port>
106		150
107	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
108	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.
109	network. This node is called a seed.
110		153
111	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	154	=item global nodes
112	are expected to be long-running, and at least one of those should always
113	be available. When nodes run out of connections (e.g. due to a network
114	error), they try to re-establish connections to some seednodes again to
115	join the network.
116		155
117	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
118	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).
119		170
120	=back	171	=back
121		172
122	=head1 VARIABLES/FUNCTIONS	173	=head1 VARIABLES/FUNCTIONS
123		174
…		…
125		176
126	=cut	177	=cut
127		178
128	package AnyEvent::MP;	179	package AnyEvent::MP;
129		180
		181	use AnyEvent::MP::Config ();
130	use AnyEvent::MP::Kernel;	182	use AnyEvent::MP::Kernel;
		183	use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID);
131		184
132	use common::sense;	185	use common::sense;
133		186
134	use Carp ();	187	use Carp ();
135		188
136	use AE ();	189	use AE ();
137		190
138	use base "Exporter";	191	use base "Exporter";
139		192
140	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	193	our $VERSION = $AnyEvent::MP::Config::VERSION;
141		194
142	our @EXPORT = qw(	195	our @EXPORT = qw(
143	NODE $NODE *SELF node_of after	196	NODE $NODE *SELF node_of after
144	initialise_node	197	configure
145	snd rcv mon mon_guard kil reg psub spawn	198	snd rcv mon mon_guard kil psub peval spawn cal
146	port	199	port
147	);	200	);
148		201
149	our $SELF;	202	our $SELF;
150		203
…		…
156		209
157	=item $thisnode = NODE / $NODE	210	=item $thisnode = NODE / $NODE
158		211
159	The C<NODE> function returns, and the C<$NODE> variable contains, the node	212	The C<NODE> function returns, and the C<$NODE> variable contains, the node
160	ID of the node running in the current process. This value is initialised by	213	ID of the node running in the current process. This value is initialised by
161	a call to C<initialise_node>.	214	a call to C<configure>.
162		215
163	=item $nodeid = node_of $port	216	=item $nodeid = node_of $port
164		217
165	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.
166		219
167	=item initialise_node $profile_name, key => value...	220	=item configure $profile, key => value...
		221
		222	=item configure key => value...
168		223
169	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
170	"distributed mode") it has to initialise itself - the minimum a node needs	225	"distributed mode") it has to configure itself - the minimum a node needs
171	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
172	some other nodes in the network to discover other nodes.	227	some other nodes in the network to discover other nodes.
173		228
174	This function initialises a node - it must be called exactly once (or	229	This function configures a node - it must be called exactly once (or
175	never) before calling other AnyEvent::MP functions.	230	never) before calling other AnyEvent::MP functions.
176		231
177	The first argument is a profile name. If it is C<undef> or missing, then	232	The key/value pairs are basically the same ones as documented for the
178	the current nodename will be used instead (i.e. F<uname -n>).	233	F<aemp> command line utility (sans the set/del prefix), with two additions:
179		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
		251	=over 4
		252
		253	=item step 1, gathering configuration from profiles
		254
180	The function first looks up the 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 is calculated as follows:	256	L<aemp> commandline utility). The profile name can be specified via the
		257	named C<profile> parameter or can simply be the first parameter). If it is
		258	missing, then the nodename (F<uname -n>) will be used as profile name.
182		259
183	First, all remaining key => value pairs will be used. Then they will be	260	The profile data is then gathered as follows:
184	overwritten by any values specified in the global default configuration	261
185	(see the F<aemp> utility), then the chain of profiles selected, if	262	First, all remaining key => value pairs (all of which are conveniently
		263	undocumented at the moment) will be interpreted as configuration
		264	data. Then they will be overwritten by any values specified in the global
		265	default configuration (see the F<aemp> utility), then the chain of
		266	profiles chosen by the profile name (and any C<parent> attributes).
		267
186	any. That means that the values specified in the profile have highest	268	That means that the values specified in the profile have highest priority
187	priority and the values specified via C<initialise_node> have lowest	269	and the values specified directly via C<configure> have lowest priority,
188	priority.	270	and can only be used to specify defaults.
189		271
190	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
191	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
192	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.
		278
		279	=item step 2, bind listener sockets
193		280
194	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
195	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
196	to have no binds, meaning that the node cannot be contacted form the	283	to have no binds, meaning that the node cannot be contacted form the
197	outside. This means the node cannot talk to other nodes that also have no	284	outside. This means the node cannot talk to other nodes that also have no
198	binds, but it can still talk to all "normal" nodes).	285	binds, but it can still talk to all "normal" nodes).
199		286
200	If the profile does not specify a binds list, then the node ID will be	287	If the profile does not specify a binds list, then a default of C<*> is
201	treated as if it were of the form C<host:port>, which will be resolved and	288	used, meaning the node will bind on a dynamically-assigned port on every
202	used as binds list.	289	local IP address it finds.
203		290
		291	=item step 3, connect to seed nodes
		292
204	Lastly, 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
205	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
206	connectivity with at least on of those seed nodes at any point in time.	295	connectivity with at least one node at any point in time.
207		296
208	Example: become a distributed node listening on the guessed noderef, or	297	=back
209	the one specified via C<aemp> for the current node. This should be the	298
		299	Example: become a distributed node using the local node name as profile.
210	most common form of invocation for "daemon"-type nodes.	300	This should be the most common form of invocation for "daemon"-type nodes.
211		301
212	initialise_node;	302	configure
213		303
214	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
215	clients.	305	clients.
216		306
217	initialise_node "anon/";	307	configure nodeid => "anon/";
218		308
219	Example: become a distributed node. If there is no profile of the given	309	Example: configure a node using a profile called seed, which is suitable
220	name, or no binds list was specified, resolve C<localhost:4044> and bind	310	for a seed node as it binds on all local addresses on a fixed port (4040,
221	on the resulting addresses.	311	customary for aemp).
222		312
223	initialise_node "localhost:4044";	313	# use the aemp commandline utility
		314	# aemp profile seed binds '*:4040'
		315
		316	# then use it
		317	configure profile => "seed";
		318
		319	# or simply use aemp from the shell again:
		320	# aemp run profile seed
		321
		322	# or provide a nicer-to-remember nodeid
		323	# aemp run profile seed nodeid "$(hostname)"
224		324
225	=item $SELF	325	=item $SELF
226		326
227	Contains the current port id while executing C<rcv> callbacks or C<psub>	327	Contains the current port id while executing C<rcv> callbacks or C<psub>
228	blocks.	328	blocks.
…		…
289	sub _kilme {	389	sub _kilme {
290	die "received message on port without callback";	390	die "received message on port without callback";
291	}	391	}
292		392
293	sub port(;&) {	393	sub port(;&) {
294	my $id = "$UNIQ." . $ID++;	394	my $id = $UNIQ . ++$ID;
295	my $port = "$NODE#$id";	395	my $port = "$NODE#$id";
296		396
297	rcv $port, shift \|\| \&_kilme;	397	rcv $port, shift \|\| \&_kilme;
298		398
299	$port	399	$port
…		…
338	msg1 => sub { ... },	438	msg1 => sub { ... },
339	...	439	...
340	;	440	;
341		441
342	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
343	(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.
344		444
345	rcv $port, $otherport => sub {	445	rcv $port, $otherport => sub {
346	my @reply = @_;	446	my @reply = @_;
347		447
348	rcv $SELF, $otherport;	448	rcv $SELF, $otherport;
…		…
350		450
351	=cut	451	=cut
352		452
353	sub rcv($@) {	453	sub rcv($@) {
354	my $port = shift;	454	my $port = shift;
355	my ($noderef, $portid) = split /#/, $port, 2;	455	my ($nodeid, $portid) = split /#/, $port, 2;
356		456
357	$NODE{$noderef} == $NODE{""}	457	$NODE{$nodeid} == $NODE{""}
358	or Carp::croak "$port: rcv can only be called on local ports, caught";	458	or Carp::croak "$port: rcv can only be called on local ports, caught";
359		459
360	while (@_) {	460	while (@_) {
361	if (ref $_[0]) {	461	if (ref $_[0]) {
362	if (my $self = $PORT_DATA{$portid}) {	462	if (my $self = $PORT_DATA{$portid}) {
363	"AnyEvent::MP::Port" eq ref $self	463	"AnyEvent::MP::Port" eq ref $self
364	or Carp::croak "$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";
365		465
366	$self->[2] = shift;	466	$self->[0] = shift;
367	} else {	467	} else {
368	my $cb = shift;	468	my $cb = shift;
369	$PORT{$portid} = sub {	469	$PORT{$portid} = sub {
370	local $SELF = $port;	470	local $SELF = $port;
371	eval { &$cb }; _self_die if $@;	471	eval { &$cb }; _self_die if $@;
372	};	472	};
373	}	473	}
374	} elsif (defined $_[0]) {	474	} elsif (defined $_[0]) {
375	my $self = $PORT_DATA{$portid} \|\|= do {	475	my $self = $PORT_DATA{$portid} \|\|= do {
376	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	476	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
377		477
378	$PORT{$portid} = sub {	478	$PORT{$portid} = sub {
379	local $SELF = $port;	479	local $SELF = $port;
380		480
381	if (my $cb = $self->[1]{$_[0]}) {	481	if (my $cb = $self->[1]{$_[0]}) {
…		…
403	}	503	}
404		504
405	$port	505	$port
406	}	506	}
407		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
408	=item $closure = psub { BLOCK }	545	=item $closure = psub { BLOCK }
409		546
410	Remembers C<$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
411	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>
412	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 $SELF, sub {
		552	BLOCK }, @_ } >>.
413		553
414	This is useful when you register callbacks from C<rcv> callbacks:	554	This is useful when you register callbacks from C<rcv> callbacks:
415		555
416	rcv delayed_reply => sub {	556	rcv delayed_reply => sub {
417	my ($delay, @reply) = @_;	557	my ($delay, @reply) = @_;
…		…
453		593
454	Monitor the given port and do something when the port is killed or	594	Monitor the given port and do something when the port is killed or
455	messages to it were lost, and optionally return a guard that can be used	595	messages to it were lost, and optionally return a guard that can be used
456	to stop monitoring again.	596	to stop monitoring again.
457		597
		598	In the first form (callback), the callback is simply called with any
		599	number of C<@reason> elements (no @reason means that the port was deleted
		600	"normally"). Note also that I<< the callback B<must> never die >>, so use
		601	C<eval> if unsure.
		602
		603	In the second form (another port given), the other port (C<$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
458	C<mon> effectively guarantees that, in the absence of hardware failures,	624	C<mon> effectively guarantees that, in the absence of hardware failures,
459	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
460	arrive, or the monitoring action will be invoked after possible message	626	arrive, or the monitoring action will be invoked after possible message
461	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
462	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
463	port). After the monitoring action was invoked, further messages might get	629	port). After the monitoring action was invoked, further messages might get
464	delivered again.	630	delivered again.
465		631
466	Note that monitoring-actions are one-shot: once messages are lost (and a	632	Inter-host-connection timeouts and monitoring depend on the transport
467	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).
468		636
469	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
470	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
471	"normally"). Note also that I<< the callback B<must> never die >>, so use	639	to ensure some maximum latency.
472	C<eval> if unsure.
473
474	In the second form (another port given), the other port (C<$rcvport>)
475	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
476	"normal" kils nothing happens, while under all other conditions, the other
477	port is killed with the same reason.
478
479	The third form (kill self) is the same as the second form, except that
480	C<$rvport> defaults to C<$SELF>.
481
482	In the last form (message), a message of the form C<@msg, @reason> will be
483	C<snd>.
484
485	As a rule of thumb, monitoring requests should always monitor a port from
486	a local port (or callback). The reason is that kill messages might get
487	lost, just like any other message. Another less obvious reason is that
488	even monitoring requests can get lost (for exmaple, when the connection
489	to the other node goes down permanently). When monitoring a port locally
490	these problems do not exist.
491		640
492	Example: call a given callback when C<$port> is killed.	641	Example: call a given callback when C<$port> is killed.
493		642
494	mon $port, sub { warn "port died because of <@_>\n" };	643	mon $port, sub { warn "port died because of <@_>\n" };
495		644
…		…
502	mon $port, $self => "restart";	651	mon $port, $self => "restart";
503		652
504	=cut	653	=cut
505		654
506	sub mon {	655	sub mon {
507	my ($noderef, $port) = split /#/, shift, 2;	656	my ($nodeid, $port) = split /#/, shift, 2;
508		657
509	my $node = $NODE{$noderef} \|\| add_node $noderef;	658	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
510		659
511	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,';
512		661
513	unless (ref $cb) {	662	unless (ref $cb) {
514	if (@_) {	663	if (@_) {
…		…
523	}	672	}
524		673
525	$node->monitor ($port, $cb);	674	$node->monitor ($port, $cb);
526		675
527	defined wantarray	676	defined wantarray
528	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	677	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
529	}	678	}
530		679
531	=item $guard = mon_guard $port, $ref, $ref...	680	=item $guard = mon_guard $port, $ref, $ref...
532		681
533	Monitors the given C<$port> and keeps the passed references. When the port	682	Monitors the given C<$port> and keeps the passed references. When the port
…		…
556		705
557	=item kil $port[, @reason]	706	=item kil $port[, @reason]
558		707
559	Kill the specified port with the given C<@reason>.	708	Kill the specified port with the given C<@reason>.
560		709
561	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" -
562	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
563	"normally").	712	(C<mon $mport, $lport> form) to get killed.
564		713
565	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>
566	C<mon>, see above).	715	form) get killed with the same reason.
567		716
568	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
569	will be reported as reason C<< die => $@ >>.	718	will be reported as reason C<< die => $@ >>.
570		719
571	Transport/communication errors are reported as C<< transport_error =>	720	Transport/communication errors are reported as C<< transport_error =>
…		…
590	the package, then the package above the package and so on (e.g.	739	the package, then the package above the package and so on (e.g.
591	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	740	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
592	exists or it runs out of package names.	741	exists or it runs out of package names.
593		742
594	The init function is then called with the newly-created port as context	743	The init function is then called with the newly-created port as context
595	object (C<$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.
596		747
597	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
598	port, and in the remote init function, immediately monitor the passed	749	port, and in the remote init function, immediately monitor the passed
599	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
600	when there is a problem.	751	when there is a problem.
601		752
		753	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		754	caller before C<spawn> returns (by delaying invocation when spawn is
		755	called for the local node).
		756
602	Example: spawn a chat server port on C<$othernode>.	757	Example: spawn a chat server port on C<$othernode>.
603		758
604	# this node, executed from within a port context:	759	# this node, executed from within a port context:
605	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	760	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
606	mon $server;	761	mon $server;
…		…
620		775
621	sub _spawn {	776	sub _spawn {
622	my $port = shift;	777	my $port = shift;
623	my $init = shift;	778	my $init = shift;
624		779
		780	# rcv will create the actual port
625	local $SELF = "$NODE#$port";	781	local $SELF = "$NODE#$port";
626	eval {	782	eval {
627	&{ load_func $init }	783	&{ load_func $init }
628	};	784	};
629	_self_die if $@;	785	_self_die if $@;
630	}	786	}
631		787
632	sub spawn(@) {	788	sub spawn(@) {
633	my ($noderef, undef) = split /#/, shift, 2;	789	my ($nodeid, undef) = split /#/, shift, 2;
634		790
635	my $id = "$RUNIQ." . $ID++;	791	my $id = $RUNIQ . ++$ID;
636		792
637	$_[0] =~ /::/	793	$_[0] =~ /::/
638	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";
639		795
640	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	796	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
641		797
642	"$noderef#$id"	798	"$nodeid#$id"
643	}	799	}
		800
644		801
645	=item after $timeout, @msg	802	=item after $timeout, @msg
646		803
647	=item after $timeout, $callback	804	=item after $timeout, $callback
648		805
…		…
664	? $action[0]()	821	? $action[0]()
665	: snd @action;	822	: snd @action;
666	};	823	};
667	}	824	}
668		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
669	=back	878	=back
670		879
671	=head1 AnyEvent::MP vs. Distributed Erlang	880	=head1 AnyEvent::MP vs. Distributed Erlang
672		881
673	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
674	== 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
675	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
676	sample:	885	sample:
677		886
678	http://www.Erlang.se/doc/programming_rules.shtml	887	http://www.erlang.se/doc/programming_rules.shtml
679	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
680	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
681	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
682		891
683	Despite the similarities, there are also some important differences:	892	Despite the similarities, there are also some important differences:
684		893
685	=over 4	894	=over 4
686		895
687	=item * Node IDs are arbitrary strings in AEMP.	896	=item * Node IDs are arbitrary strings in AEMP.
688		897
689	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
690	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
691	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.
692		902
693	=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
694	uses "local ports are like remote ports".	904	uses "local ports are like remote ports".
695		905
696	The failure modes for local ports are quite different (runtime errors	906	The failure modes for local ports are quite different (runtime errors
…		…
705	ports being the special case/exception, where transport errors cannot	915	ports being the special case/exception, where transport errors cannot
706	occur.	916	occur.
707		917
708	=item * Erlang uses processes and a mailbox, AEMP does not queue.	918	=item * Erlang uses processes and a mailbox, AEMP does not queue.
709		919
710	Erlang uses processes that selectively receive messages, and therefore	920	Erlang uses processes that selectively receive messages out of order, and
711	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
712	useful purpose. For the same reason the pattern-matching abilities of	922	no useful purpose. For the same reason the pattern-matching abilities
713	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
714	filter messages without dequeing them.	924	filter messages without dequeuing them.
715		925
716	(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.
717		931
718	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	932	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
719		933
720	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
721	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
722	connection establishment is handled in the background.	937	establishment is handled in the background.
723		938
724	=item * Erlang suffers from silent message loss, AEMP does not.	939	=item * Erlang suffers from silent message loss, AEMP does not.
725		940
726	Erlang makes few guarantees on messages delivery - messages can get lost	941	Erlang implements few guarantees on messages delivery - messages can get
727	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,
728	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).
729		944
730	AEMP guarantees correct ordering, and the guarantee that after one message	945	AEMP guarantees (modulo hardware errors) correct ordering, and the
731	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
732	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
733	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.
734		954
735	=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.
736		956
737	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
738	known to other nodes for a completely different process, causing messages	958	process ID known to other nodes for a completely different process,
739	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.
740		961
741	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
742	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.
743		964
744	=item * Erlang uses unprotected connections, AEMP uses secure	965	=item * Erlang uses unprotected connections, AEMP uses secure
745	authentication and can use TLS.	966	authentication and can use TLS.
746		967
…		…
749		970
750	=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
751	communications.	972	communications.
752		973
753	The AEMP protocol, unlike the Erlang protocol, supports both programming	974	The AEMP protocol, unlike the Erlang protocol, supports both programming
754	language independent text-only protocols (good for debugging) and binary,	975	language independent text-only protocols (good for debugging), and binary,
755	language-specific serialisers (e.g. Storable). By default, unless TLS is	976	language-specific serialisers (e.g. Storable). By default, unless TLS is
756	used, the protocol is actually completely text-based.	977	used, the protocol is actually completely text-based.
757		978
758	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
759	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
760	protocol simple.	981	protocol simple.
761		982
762	=item * AEMP has more flexible monitoring options than Erlang.	983	=item * AEMP has more flexible monitoring options than Erlang.
763		984
764	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
765	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
766	difficult to implement. Monitoring in AEMP is more flexible than in	987	difficult to implement.
767	Erlang, as one can choose between automatic kill, exit message or callback	988
768	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.
769		991
770	=item * Erlang tries to hide remote/local connections, AEMP does not.	992	=item * Erlang tries to hide remote/local connections, AEMP does not.
771		993
772	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
773	same way as linking is (except linking is unreliable in Erlang).	995	same way as linking is (except linking is unreliable in Erlang).
…		…
795	overhead, as well as having to keep a proxy object everywhere.	1017	overhead, as well as having to keep a proxy object everywhere.
796		1018
797	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
798	procedures to be "valid".	1020	procedures to be "valid".
799		1021
800	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
801	global hash - it can't become much cheaper.	1023	code reference stored in a global hash - it can't become much cheaper.
802		1024
803	=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?
804		1026
805	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
806	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
…		…
822		1044
823	L<AnyEvent::MP::Intro> - a gentle introduction.	1045	L<AnyEvent::MP::Intro> - a gentle introduction.
824		1046
825	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1047	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
826		1048
827	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1049	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
828	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.
829		1056
830	L<AnyEvent>.	1057	L<AnyEvent>.
831		1058
832	=head1 AUTHOR	1059	=head1 AUTHOR
833		1060

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.69 by root, Sun Aug 30 18:51:49 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 1.69 by root, Sun Aug 30 18:51:49 2009 UTC vs.
Revision 1.123 by root, Thu Mar 1 19:37:59 2012 UTC