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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.26 by root, Tue Aug 4 22:05:43 2009 UTC vs.
Revision 1.53 by root, Fri Aug 14 15:31:21 2009 UTC

…		…
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's noderef
10	NODE # returns this node's noderef	10	NODE # returns this node's noderef
11	NODE $port # returns the noderef of the port	11	NODE $port # returns the noderef of the port
12		12
		13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# initialise the node so it can send/receive messages
		16	initialise_node; # -OR-
		17	initialise_node "localhost:4040"; # -OR-
		18	initialise_node "slave/", "localhost:4040"
		19
		20	# ports are message endpoints
		21
		22	# sending messages
13	snd $port, type => data...;	23	snd $port, type => data...;
		24	snd $port, @msg;
		25	snd @msg_with_first_element_being_a_port;
14		26
15	$SELF # receiving/own port id in rcv callbacks	27	# creating/using ports, the simple way
		28	my $simple_port = port { my @msg = @_; 0 };
16		29
17	rcv $port, smartmatch => $cb->($port, @msg);	30	# creating/using ports, tagged message matching
18		31	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	32	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	33	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		34
24	# more, smarter, matches (_any_ is exported by this module)	35	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	36	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	37
		38	# monitoring
		39	mon $port, $cb->(@msg) # callback is invoked on death
		40	mon $port, $otherport # kill otherport on abnormal death
		41	mon $port, $otherport, @msg # send message on death
		42
		43	=head1 CURRENT STATUS
		44
		45	AnyEvent::MP - stable API, should work
		46	AnyEvent::MP::Intro - outdated
		47	AnyEvent::MP::Kernel - WIP
		48	AnyEvent::MP::Transport - mostly stable
		49
		50	stay tuned.
27		51
28	=head1 DESCRIPTION	52	=head1 DESCRIPTION
29		53
30	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
31		55
…		…
35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	manual page.	60	manual page.
37		61
38	At the moment, this module family is severly broken and underdocumented,	62	At the moment, this module family is severly broken and underdocumented,
39	so do not use. This was uploaded mainly to reserve the CPAN namespace -	63	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	stay tuned! The basic API should be finished, however.	64	stay tuned!
41		65
42	=head1 CONCEPTS	66	=head1 CONCEPTS
43		67
44	=over 4	68	=over 4
45		69
46	=item port	70	=item port
47		71
48	A port is something you can send messages to with the C<snd> function, and	72	A port is something you can send messages to (with the C<snd> function).
49	you can register C<rcv> handlers with. All C<rcv> handlers will receive	73
		74	Ports allow you to register C<rcv> handlers that can match all or just
50	messages they match, messages will not be queued.	75	some messages. Messages will not be queued.
51		76
52	=item port id - C<noderef#portname>	77	=item port id - C<noderef#portname>
53		78
54	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	79	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as
55	by a port name (a printable string of unspecified format).	80	separator, and a port name (a printable string of unspecified format). An
		81	exception is the the node port, whose ID is identical to its node
		82	reference.
56		83
57	=item node	84	=item node
58		85
59	A node is a single process containing at least one port - the node	86	A node is a single process containing at least one port - the node port,
60	port. You can send messages to node ports to let them create new ports,	87	which provides nodes to manage each other remotely, and to create new
61	among other things.	88	ports.
62		89
63	Initially, nodes are either private (single-process only) or hidden	90	Nodes are either private (single-process only), slaves (connected to a
64	(connected to a master node only). Only when they epxlicitly "become	91	master node only) or public nodes (connectable from unrelated nodes).
65	public" can you send them messages from unrelated other nodes.
66		92
67	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	93	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
68		94
69	A noderef is a string that either uniquely identifies a given node (for	95	A node reference is a string that either simply identifies the node (for
70	private and hidden nodes), or contains a recipe on how to reach a given	96	private and slave nodes), or contains a recipe on how to reach a given
71	node (for public nodes).	97	node (for public nodes).
72		98
		99	This recipe is simply a comma-separated list of C<address:port> pairs (for
		100	TCP/IP, other protocols might look different).
		101
		102	Node references come in two flavours: resolved (containing only numerical
		103	addresses) or unresolved (where hostnames are used instead of addresses).
		104
		105	Before using an unresolved node reference in a message you first have to
		106	resolve it.
		107
73	=back	108	=back
74		109
75	=head1 VARIABLES/FUNCTIONS	110	=head1 VARIABLES/FUNCTIONS
76		111
77	=over 4	112	=over 4
78		113
79	=cut	114	=cut
80		115
81	package AnyEvent::MP;	116	package AnyEvent::MP;
82		117
83	use AnyEvent::MP::Base;	118	use AnyEvent::MP::Kernel;
84		119
85	use common::sense;	120	use common::sense;
86		121
87	use Carp ();	122	use Carp ();
88		123
89	use AE ();	124	use AE ();
90		125
91	use base "Exporter";	126	use base "Exporter";
92		127
93	our $VERSION = '0.1';	128	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		129
94	our @EXPORT = qw(	130	our @EXPORT = qw(
95	NODE $NODE *SELF node_of _any_	131	NODE $NODE *SELF node_of _any_
96	become_slave become_public	132	resolve_node initialise_node
97	snd rcv mon kil reg psub	133	snd rcv mon kil reg psub spawn
98	port	134	port
99	);	135	);
100		136
101	our $SELF;	137	our $SELF;
102		138
…		…
106	kil $SELF, die => $msg;	142	kil $SELF, die => $msg;
107	}	143	}
108		144
109	=item $thisnode = NODE / $NODE	145	=item $thisnode = NODE / $NODE
110		146
111	The C<NODE> function returns, and the C<$NODE> variable contains	147	The C<NODE> function returns, and the C<$NODE> variable contains the
112	the noderef of the local node. The value is initialised by a call	148	noderef of the local node. The value is initialised by a call to
113	to C<become_public> or C<become_slave>, after which all local port	149	C<initialise_node>.
114	identifiers become invalid.
115		150
116	=item $noderef = node_of $portid	151	=item $noderef = node_of $port
117		152
118	Extracts and returns the noderef from a portid or a noderef.	153	Extracts and returns the noderef from a port ID or a noderef.
		154
		155	=item initialise_node $noderef, $seednode, $seednode...
		156
		157	=item initialise_node "slave/", $master, $master...
		158
		159	Before a node can talk to other nodes on the network it has to initialise
		160	itself - the minimum a node needs to know is it's own name, and optionally
		161	it should know the noderefs of some other nodes in the network.
		162
		163	This function initialises a node - it must be called exactly once (or
		164	never) before calling other AnyEvent::MP functions.
		165
		166	All arguments (optionally except for the first) are noderefs, which can be
		167	either resolved or unresolved.
		168
		169	The first argument will be looked up in the configuration database first
		170	(if it is C<undef> then the current nodename will be used instead) to find
		171	the relevant configuration profile (see L<aemp>). If none is found then
		172	the default configuration is used. The configuration supplies additional
		173	seed/master nodes and can override the actual noderef.
		174
		175	There are two types of networked nodes, public nodes and slave nodes:
		176
		177	=over 4
		178
		179	=item public nodes
		180
		181	For public nodes, C<$noderef> (supplied either directly to
		182	C<initialise_node> or indirectly via a profile or the nodename) must be a
		183	noderef (possibly unresolved, in which case it will be resolved).
		184
		185	After resolving, the node will bind itself on all endpoints and try to
		186	connect to all additional C<$seednodes> that are specified. Seednodes are
		187	optional and can be used to quickly bootstrap the node into an existing
		188	network.
		189
		190	=item slave nodes
		191
		192	When the C<$noderef> (either as given or overriden by the config file)
		193	is the special string C<slave/>, then the node will become a slave
		194	node. Slave nodes cannot be contacted from outside and will route most of
		195	their traffic to the master node that they attach to.
		196
		197	At least one additional noderef is required (either by specifying it
		198	directly or because it is part of the configuration profile): The node
		199	will try to connect to all of them and will become a slave attached to the
		200	first node it can successfully connect to.
		201
		202	=back
		203
		204	This function will block until all nodes have been resolved and, for slave
		205	nodes, until it has successfully established a connection to a master
		206	server.
		207
		208	Example: become a public node listening on the guessed noderef, or the one
		209	specified via C<aemp> for the current node. This should be the most common
		210	form of invocation for "daemon"-type nodes.
		211
		212	initialise_node;
		213
		214	Example: become a slave node to any of the the seednodes specified via
		215	C<aemp>. This form is often used for commandline clients.
		216
		217	initialise_node "slave/";
		218
		219	Example: become a slave node to any of the specified master servers. This
		220	form is also often used for commandline clients.
		221
		222	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		223
		224	Example: become a public node, and try to contact some well-known master
		225	servers to become part of the network.
		226
		227	initialise_node undef, "master1", "master2";
		228
		229	Example: become a public node listening on port C<4041>.
		230
		231	initialise_node 4041;
		232
		233	Example: become a public node, only visible on localhost port 4044.
		234
		235	initialise_node "localhost:4044";
		236
		237	=item $cv = resolve_node $noderef
		238
		239	Takes an unresolved node reference that may contain hostnames and
		240	abbreviated IDs, resolves all of them and returns a resolved node
		241	reference.
		242
		243	In addition to C<address:port> pairs allowed in resolved noderefs, the
		244	following forms are supported:
		245
		246	=over 4
		247
		248	=item the empty string
		249
		250	An empty-string component gets resolved as if the default port (4040) was
		251	specified.
		252
		253	=item naked port numbers (e.g. C<1234>)
		254
		255	These are resolved by prepending the local nodename and a colon, to be
		256	further resolved.
		257
		258	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		259
		260	These are resolved by using AnyEvent::DNS to resolve them, optionally
		261	looking up SRV records for the C<aemp=4040> port, if no port was
		262	specified.
		263
		264	=back
119		265
120	=item $SELF	266	=item $SELF
121		267
122	Contains the current port id while executing C<rcv> callbacks or C<psub>	268	Contains the current port id while executing C<rcv> callbacks or C<psub>
123	blocks.	269	blocks.
…		…
126		272
127	Due to some quirks in how perl exports variables, it is impossible to	273	Due to some quirks in how perl exports variables, it is impossible to
128	just export C<$SELF>, all the symbols called C<SELF> are exported by this	274	just export C<$SELF>, all the symbols called C<SELF> are exported by this
129	module, but only C<$SELF> is currently used.	275	module, but only C<$SELF> is currently used.
130		276
131	=item snd $portid, type => @data	277	=item snd $port, type => @data
132		278
133	=item snd $portid, @msg	279	=item snd $port, @msg
134		280
135	Send the given message to the given port ID, which can identify either	281	Send the given message to the given port ID, which can identify either
136	a local or a remote port, and can be either a string or soemthignt hat	282	a local or a remote port, and must be a port ID.
137	stringifies a sa port ID (such as a port object :).
138		283
139	While the message can be about anything, it is highly recommended to use a	284	While the message can be about anything, it is highly recommended to use a
140	string as first element (a portid, or some word that indicates a request	285	string as first element (a port ID, or some word that indicates a request
141	type etc.).	286	type etc.).
142		287
143	The message data effectively becomes read-only after a call to this	288	The message data effectively becomes read-only after a call to this
144	function: modifying any argument is not allowed and can cause many	289	function: modifying any argument is not allowed and can cause many
145	problems.	290	problems.
…		…
148	JSON is used, then only strings, numbers and arrays and hashes consisting	293	JSON is used, then only strings, numbers and arrays and hashes consisting
149	of those are allowed (no objects). When Storable is used, then anything	294	of those are allowed (no objects). When Storable is used, then anything
150	that Storable can serialise and deserialise is allowed, and for the local	295	that Storable can serialise and deserialise is allowed, and for the local
151	node, anything can be passed.	296	node, anything can be passed.
152		297
153	=item kil $portid[, @reason]	298	=item $local_port = port
154		299
155	Kill the specified port with the given C<@reason>.	300	Create a new local port object and returns its port ID. Initially it has
		301	no callbacks set and will throw an error when it receives messages.
156		302
157	If no C<@reason> is specified, then the port is killed "normally" (linked	303	=item $local_port = port { my @msg = @_ }
158	ports will not be kileld, or even notified).
159		304
160	Otherwise, linked ports get killed with the same reason (second form of	305	Creates a new local port, and returns its ID. Semantically the same as
161	C<mon>, see below).	306	creating a port and calling C<rcv $port, $callback> on it.
162		307
163	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	308	The block will be called for every message received on the port, with the
164	will be reported as reason C<< die => $@ >>.	309	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		310	port to be C<kil>ed. The message will be passed as-is, no extra argument
		311	(i.e. no port ID) will be passed to the callback.
165		312
166	Transport/communication errors are reported as C<< transport_error =>	313	If you want to stop/destroy the port, simply C<kil> it:
167	$message >>.
168		314
169	=item $guard = mon $portid, $cb->(@reason)	315	my $port = port {
170
171	=item $guard = mon $portid, $otherport
172
173	=item $guard = mon $portid, $otherport, @msg
174
175	Monitor the given port and do something when the port is killed.
176
177	In the first form, the callback is simply called with any number
178	of C<@reason> elements (no @reason means that the port was deleted
179	"normally"). Note also that I<< the callback B<must> never die >>, so use
180	C<eval> if unsure.
181
182	In the second form, the other port will be C<kil>'ed with C<@reason>, iff
183	a @reason was specified, i.e. on "normal" kils nothing happens, while
184	under all other conditions, the other port is killed with the same reason.
185
186	In the last form, a message of the form C<@msg, @reason> will be C<snd>.
187
188	Example: call a given callback when C<$port> is killed.
189
190	mon $port, sub { warn "port died because of <@_>\n" };
191
192	Example: kill ourselves when C<$port> is killed abnormally.
193
194	mon $port, $self;
195
196	Example: send us a restart message another C<$port> is killed.
197
198	mon $port, $self => "restart";
199
200	=cut
201
202	sub mon {
203	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);
204
205	my $node = $NODE{$noderef} \|\| add_node $noderef;
206
207	#TODO: ports must not be references
208	if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) {
209	if (@_) {
210	# send a kill info message
211	my (@msg) = ($cb, @_);	316	my @msg = @_;
212	$cb = sub { snd @msg, @_ };
213	} else {
214	# simply kill other port
215	my $port = $cb;
216	$cb = sub { kil $port, @_ if @_ };
217	}	317	...
		318	kil $SELF;
218	}	319	};
219		320
220	$node->monitor ($port, $cb);	321	=cut
221		322
222	defined wantarray	323	sub rcv($@);
223	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	324
		325	sub _kilme {
		326	die "received message on port without callback";
224	}	327	}
225
226	=item $guard = mon_guard $port, $ref, $ref...
227
228	Monitors the given C<$port> and keeps the passed references. When the port
229	is killed, the references will be freed.
230
231	Optionally returns a guard that will stop the monitoring.
232
233	This function is useful when you create e.g. timers or other watchers and
234	want to free them when the port gets killed:
235
236	$port->rcv (start => sub {
237	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
238	undef $timer if 0.9 < rand;
239	});
240	});
241
242	=cut
243
244	sub mon_guard {
245	my ($port, @refs) = @_;
246
247	mon $port, sub { 0 && @refs }
248	}
249
250	=item lnk $port1, $port2
251
252	Link two ports. This is simply a shorthand for:
253
254	mon $port1, $port2;
255	mon $port2, $port1;
256
257	It means that if either one is killed abnormally, the other one gets
258	killed as well.
259
260	=item $local_port = port
261
262	Create a new local port object that supports message matching.
263
264	=item $portid = port { my @msg = @_; $finished }
265
266	Creates a "mini port", that is, a very lightweight port without any
267	pattern matching behind it, and returns its ID.
268
269	The block will be called for every message received on the port. When the
270	callback returns a true value its job is considered "done" and the port
271	will be destroyed. Otherwise it will stay alive.
272
273	The message will be passed as-is, no extra argument (i.e. no port id) will
274	be passed to the callback.
275
276	If you need the local port id in the callback, this works nicely:
277
278	my $port; $port = miniport {
279	snd $otherport, reply => $port;
280	};
281
282	=cut
283		328
284	sub port(;&) {	329	sub port(;&) {
285	my $id = "$UNIQ." . $ID++;	330	my $id = "$UNIQ." . $ID++;
286	my $port = "$NODE#$id";	331	my $port = "$NODE#$id";
287		332
288	if (@_) {	333	rcv $port, shift \|\| \&_kilme;
289	my $cb = shift;
290	$PORT{$id} = sub {
291	local $SELF = $port;
292	eval {
293	&$cb
294	and kil $id;
295	};
296	_self_die if $@;
297	};
298	} else {
299	my $self = bless {
300	id => "$NODE#$id",
301	}, "AnyEvent::MP::Port";
302
303	$PORT_DATA{$id} = $self;
304	$PORT{$id} = sub {
305	local $SELF = $port;
306
307	eval {
308	for (@{ $self->{rc0}{$_[0]} }) {
309	$_ && &{$_->[0]}
310	&& undef $_;
311	}
312
313	for (@{ $self->{rcv}{$_[0]} }) {
314	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
315	&& &{$_->[0]}
316	&& undef $_;
317	}
318
319	for (@{ $self->{any} }) {
320	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
321	&& &{$_->[0]}
322	&& undef $_;
323	}
324	};
325	_self_die if $@;
326	};
327	}
328		334
329	$port	335	$port
330	}	336	}
331		337
332	=item reg $portid, $name	338	=item rcv $local_port, $callback->(@msg)
333		339
334	Registers the given port under the name C<$name>. If the name already	340	Replaces the default callback on the specified port. There is no way to
335	exists it is replaced.	341	remove the default callback: use C<sub { }> to disable it, or better
		342	C<kil> the port when it is no longer needed.
336		343
337	A port can only be registered under one well known name.
338
339	A port automatically becomes unregistered when it is killed.
340
341	=cut
342
343	sub reg(@) {
344	my ($portid, $name) = @_;
345
346	$REG{$name} = $portid;
347	}
348
349	=item rcv $portid, tagstring => $callback->(@msg), ...
350
351	=item rcv $portid, $smartmatch => $callback->(@msg), ...
352
353	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
354
355	Register callbacks to be called on matching messages on the given port.
356
357	The callback has to return a true value when its work is done, after
358	which is will be removed, or a false value in which case it will stay
359	registered.
360
361	The global C<$SELF> (exported by this module) contains C<$portid> while	344	The global C<$SELF> (exported by this module) contains C<$port> while
362	executing the callback.	345	executing the callback. Runtime errors during callback execution will
		346	result in the port being C<kil>ed.
363		347
364	Runtime errors wdurign callback execution will result in the port being	348	The default callback received all messages not matched by a more specific
365	C<kil>ed.	349	C<tag> match.
366		350
367	If the match is an array reference, then it will be matched against the	351	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
368	first elements of the message, otherwise only the first element is being
369	matched.
370		352
371	Any element in the match that is specified as C<_any_> (a function	353	Register callbacks to be called on messages starting with the given tag on
372	exported by this module) matches any single element of the message.	354	the given port (and return the port), or unregister it (when C<$callback>
		355	is C<$undef>).
373		356
374	While not required, it is highly recommended that the first matching	357	The original message will be passed to the callback, after the first
375	element is a string identifying the message. The one-string-only match is	358	element (the tag) has been removed. The callback will use the same
376	also the most efficient match (by far).	359	environment as the default callback (see above).
		360
		361	Example: create a port and bind receivers on it in one go.
		362
		363	my $port = rcv port,
		364	msg1 => sub { ... },
		365	msg2 => sub { ... },
		366	;
		367
		368	Example: create a port, bind receivers and send it in a message elsewhere
		369	in one go:
		370
		371	snd $otherport, reply =>
		372	rcv port,
		373	msg1 => sub { ... },
		374	...
		375	;
377		376
378	=cut	377	=cut
379		378
380	sub rcv($@) {	379	sub rcv($@) {
		380	my $port = shift;
381	my ($noderef, $port) = split /#/, shift, 2;	381	my ($noderef, $portid) = split /#/, $port, 2;
382		382
383	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	383	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
384	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";	384	or Carp::croak "$port: rcv can only be called on local ports, caught";
385
386	my $self = $PORT_DATA{$port}
387	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
388
389	"AnyEvent::MP::Port" eq ref $self
390	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
391		385
392	while (@_) {	386	while (@_) {
393	my ($match, $cb) = splice @_, 0, 2;
394
395	if (!ref $match) {	387	if (ref $_[0]) {
396	push @{ $self->{rc0}{$match} }, [$cb];	388	if (my $self = $PORT_DATA{$portid}) {
397	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	389	"AnyEvent::MP::Port" eq ref $self
398	my ($type, @match) = @$match;	390	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
399	@match	391
400	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	392	$self->[2] = shift;
401	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
402	} else {	393	} else {
403	push @{ $self->{any} }, [$cb, $match];	394	my $cb = shift;
		395	$PORT{$portid} = sub {
		396	local $SELF = $port;
		397	eval { &$cb }; _self_die if $@;
		398	};
		399	}
		400	} elsif (defined $_[0]) {
		401	my $self = $PORT_DATA{$portid} \|\|= do {
		402	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		403
		404	$PORT{$portid} = sub {
		405	local $SELF = $port;
		406
		407	if (my $cb = $self->[1]{$_[0]}) {
		408	shift;
		409	eval { &$cb }; _self_die if $@;
		410	} else {
		411	&{ $self->[0] };
		412	}
		413	};
		414
		415	$self
		416	};
		417
		418	"AnyEvent::MP::Port" eq ref $self
		419	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		420
		421	my ($tag, $cb) = splice @_, 0, 2;
		422
		423	if (defined $cb) {
		424	$self->[1]{$tag} = $cb;
		425	} else {
		426	delete $self->[1]{$tag};
		427	}
404	}	428	}
405	}	429	}
		430
		431	$port
406	}	432	}
407		433
408	=item $closure = psub { BLOCK }	434	=item $closure = psub { BLOCK }
409		435
410	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	436	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
…		…
441	$res	467	$res
442	}	468	}
443	}	469	}
444	}	470	}
445		471
446	=back	472	=item $guard = mon $port, $cb->(@reason)
447		473
448	=head1 FUNCTIONS FOR NODES	474	=item $guard = mon $port, $rcvport
449		475
450	=over 4	476	=item $guard = mon $port
451		477
452	=item become_public endpoint...	478	=item $guard = mon $port, $rcvport, @msg
453		479
454	Tells the node to become a public node, i.e. reachable from other nodes.	480	Monitor the given port and do something when the port is killed or
		481	messages to it were lost, and optionally return a guard that can be used
		482	to stop monitoring again.
455		483
456	If no arguments are given, or the first argument is C<undef>, then	484	C<mon> effectively guarantees that, in the absence of hardware failures,
457	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the	485	that after starting the monitor, either all messages sent to the port
458	local nodename resolves to.	486	will arrive, or the monitoring action will be invoked after possible
		487	message loss has been detected. No messages will be lost "in between"
		488	(after the first lost message no further messages will be received by the
		489	port). After the monitoring action was invoked, further messages might get
		490	delivered again.
459		491
460	Otherwise the first argument must be an array-reference with transport	492	In the first form (callback), the callback is simply called with any
461	endpoints ("ip:port", "hostname:port") or port numbers (in which case the	493	number of C<@reason> elements (no @reason means that the port was deleted
462	local nodename is used as hostname). The endpoints are all resolved and	494	"normally"). Note also that I<< the callback B<must> never die >>, so use
463	will become the node reference.	495	C<eval> if unsure.
464		496
		497	In the second form (another port given), the other port (C<$rcvport>)
		498	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
		499	"normal" kils nothing happens, while under all other conditions, the other
		500	port is killed with the same reason.
		501
		502	The third form (kill self) is the same as the second form, except that
		503	C<$rvport> defaults to C<$SELF>.
		504
		505	In the last form (message), a message of the form C<@msg, @reason> will be
		506	C<snd>.
		507
		508	As a rule of thumb, monitoring requests should always monitor a port from
		509	a local port (or callback). The reason is that kill messages might get
		510	lost, just like any other message. Another less obvious reason is that
		511	even monitoring requests can get lost (for exmaple, when the connection
		512	to the other node goes down permanently). When monitoring a port locally
		513	these problems do not exist.
		514
		515	Example: call a given callback when C<$port> is killed.
		516
		517	mon $port, sub { warn "port died because of <@_>\n" };
		518
		519	Example: kill ourselves when C<$port> is killed abnormally.
		520
		521	mon $port;
		522
		523	Example: send us a restart message when another C<$port> is killed.
		524
		525	mon $port, $self => "restart";
		526
465	=cut	527	=cut
		528
		529	sub mon {
		530	my ($noderef, $port) = split /#/, shift, 2;
		531
		532	my $node = $NODE{$noderef} \|\| add_node $noderef;
		533
		534	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		535
		536	unless (ref $cb) {
		537	if (@_) {
		538	# send a kill info message
		539	my (@msg) = ($cb, @_);
		540	$cb = sub { snd @msg, @_ };
		541	} else {
		542	# simply kill other port
		543	my $port = $cb;
		544	$cb = sub { kil $port, @_ if @_ };
		545	}
		546	}
		547
		548	$node->monitor ($port, $cb);
		549
		550	defined wantarray
		551	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		552	}
		553
		554	=item $guard = mon_guard $port, $ref, $ref...
		555
		556	Monitors the given C<$port> and keeps the passed references. When the port
		557	is killed, the references will be freed.
		558
		559	Optionally returns a guard that will stop the monitoring.
		560
		561	This function is useful when you create e.g. timers or other watchers and
		562	want to free them when the port gets killed:
		563
		564	$port->rcv (start => sub {
		565	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		566	undef $timer if 0.9 < rand;
		567	});
		568	});
		569
		570	=cut
		571
		572	sub mon_guard {
		573	my ($port, @refs) = @_;
		574
		575	#TODO: mon-less form?
		576
		577	mon $port, sub { 0 && @refs }
		578	}
		579
		580	=item kil $port[, @reason]
		581
		582	Kill the specified port with the given C<@reason>.
		583
		584	If no C<@reason> is specified, then the port is killed "normally" (linked
		585	ports will not be kileld, or even notified).
		586
		587	Otherwise, linked ports get killed with the same reason (second form of
		588	C<mon>, see below).
		589
		590	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		591	will be reported as reason C<< die => $@ >>.
		592
		593	Transport/communication errors are reported as C<< transport_error =>
		594	$message >>.
		595
		596	=cut
		597
		598	=item $port = spawn $node, $initfunc[, @initdata]
		599
		600	Creates a port on the node C<$node> (which can also be a port ID, in which
		601	case it's the node where that port resides).
		602
		603	The port ID of the newly created port is return immediately, and it is
		604	permissible to immediately start sending messages or monitor the port.
		605
		606	After the port has been created, the init function is
		607	called. This function must be a fully-qualified function name
		608	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		609	program, use C<::name>.
		610
		611	If the function doesn't exist, then the node tries to C<require>
		612	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
		614	exists or it runs out of package names.
		615
		616	The init function is then called with the newly-created port as context
		617	object (C<$SELF>) and the C<@initdata> values as arguments.
		618
		619	A common idiom is to pass your own port, monitor the spawned port, and
		620	in the init function, monitor the original port. This two-way monitoring
		621	ensures that both ports get cleaned up when there is a problem.
		622
		623	Example: spawn a chat server port on C<$othernode>.
		624
		625	# this node, executed from within a port context:
		626	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		627	mon $server;
		628
		629	# init function on C<$othernode>
		630	sub connect {
		631	my ($srcport) = @_;
		632
		633	mon $srcport;
		634
		635	rcv $SELF, sub {
		636	...
		637	};
		638	}
		639
		640	=cut
		641
		642	sub _spawn {
		643	my $port = shift;
		644	my $init = shift;
		645
		646	local $SELF = "$NODE#$port";
		647	eval {
		648	&{ load_func $init }
		649	};
		650	_self_die if $@;
		651	}
		652
		653	sub spawn(@) {
		654	my ($noderef, undef) = split /#/, shift, 2;
		655
		656	my $id = "$RUNIQ." . $ID++;
		657
		658	$_[0] =~ /::/
		659	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		660
		661	($NODE{$noderef} \|\| add_node $noderef)
		662	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
		663
		664	"$noderef#$id"
		665	}
466		666
467	=back	667	=back
468		668
469	=head1 NODE MESSAGES	669	=head1 NODE MESSAGES
470		670
471	Nodes understand the following messages sent to them. Many of them take	671	Nodes understand the following messages sent to them. Many of them take
472	arguments called C<@reply>, which will simply be used to compose a reply	672	arguments called C<@reply>, which will simply be used to compose a reply
473	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	673	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
474	the remaining arguments are simply the message data.	674	the remaining arguments are simply the message data.
475		675
		676	While other messages exist, they are not public and subject to change.
		677
476	=over 4	678	=over 4
477		679
478	=cut	680	=cut
479		681
480	=item lookup => $name, @reply	682	=item lookup => $name, @reply
…		…
510		712
511	=back	713	=back
512		714
513	=head1 AnyEvent::MP vs. Distributed Erlang	715	=head1 AnyEvent::MP vs. Distributed Erlang
514		716
515	AnyEvent::MP got lots of its ideas from distributed erlang. Despite the	717	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
516	similarities (erlang node == aemp node, erlang process == aemp port and so	718	== aemp node, Erlang process == aemp port), so many of the documents and
		719	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		720	sample:
		721
		722	http://www.Erlang.se/doc/programming_rules.shtml
		723	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		724	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		725	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		726
517	on), there are also some important differences:	727	Despite the similarities, there are also some important differences:
518		728
519	=over 4	729	=over 4
520		730
521	=item * Node references contain the recipe on how to contact them.	731	=item * Node references contain the recipe on how to contact them.
522		732
523	Erlang relies on special naming and DNS to work everywhere in the	733	Erlang relies on special naming and DNS to work everywhere in the
524	same way. AEMP relies on each node knowing it's own address(es), with	734	same way. AEMP relies on each node knowing it's own address(es), with
525	convenience functionality.	735	convenience functionality.
526		736
		737	This means that AEMP requires a less tightly controlled environment at the
		738	cost of longer node references and a slightly higher management overhead.
		739
		740	=item Erlang has a "remote ports are like local ports" philosophy, AEMP
		741	uses "local ports are like remote ports".
		742
		743	The failure modes for local ports are quite different (runtime errors
		744	only) then for remote ports - when a local port dies, you I<know> it dies,
		745	when a connection to another node dies, you know nothing about the other
		746	port.
		747
		748	Erlang pretends remote ports are as reliable as local ports, even when
		749	they are not.
		750
		751	AEMP encourages a "treat remote ports differently" philosophy, with local
		752	ports being the special case/exception, where transport errors cannot
		753	occur.
		754
527	=item * Erlang uses processes and a mailbox, AEMP does not queue.	755	=item * Erlang uses processes and a mailbox, AEMP does not queue.
528		756
529	Erlang uses processes that selctively receive messages, and therefore	757	Erlang uses processes that selectively receive messages, and therefore
530	needs a queue. AEMP is event based, queuing messages would serve no useful	758	needs a queue. AEMP is event based, queuing messages would serve no
531	purpose.	759	useful purpose. For the same reason the pattern-matching abilities of
		760	AnyEvent::MP are more limited, as there is little need to be able to
		761	filter messages without dequeing them.
532		762
533	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	763	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
534		764
535	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	765	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
536		766
537	Sending messages in erlang is synchronous and blocks the process. AEMP	767	Sending messages in Erlang is synchronous and blocks the process (and
538	sends are immediate, connection establishment is handled in the	768	so does not need a queue that can overflow). AEMP sends are immediate,
539	background.	769	connection establishment is handled in the background.
540		770
541	=item * Erlang can silently lose messages, AEMP cannot.	771	=item * Erlang suffers from silent message loss, AEMP does not.
542		772
543	Erlang makes few guarantees on messages delivery - messages can get lost	773	Erlang makes few guarantees on messages delivery - messages can get lost
544	without any of the processes realising it (i.e. you send messages a, b,	774	without any of the processes realising it (i.e. you send messages a, b,
545	and c, and the other side only receives messages a and c).	775	and c, and the other side only receives messages a and c).
546		776
547	AEMP guarantees correct ordering, and the guarantee that there are no	777	AEMP guarantees correct ordering, and the guarantee that there are no
548	holes in the message sequence.	778	holes in the message sequence.
549		779
550	=item * In erlang, processes can be declared dead and later be found to be	780	=item * In Erlang, processes can be declared dead and later be found to be
551	alive.	781	alive.
552		782
553	In erlang it can happen that a monitored process is declared dead and	783	In Erlang it can happen that a monitored process is declared dead and
554	linked processes get killed, but later it turns out that the process is	784	linked processes get killed, but later it turns out that the process is
555	still alive - and can receive messages.	785	still alive - and can receive messages.
556		786
557	In AEMP, when port monitoring detects a port as dead, then that port will	787	In AEMP, when port monitoring detects a port as dead, then that port will
558	eventually be killed - it cannot happen that a node detects a port as dead	788	eventually be killed - it cannot happen that a node detects a port as dead
559	and then later sends messages to it, finding it is still alive.	789	and then later sends messages to it, finding it is still alive.
560		790
561	=item * Erlang can send messages to the wrong port, AEMP does not.	791	=item * Erlang can send messages to the wrong port, AEMP does not.
562		792
563	In erlang it is quite possible that a node that restarts reuses a process	793	In Erlang it is quite likely that a node that restarts reuses a process ID
564	ID known to other nodes for a completely different process, causing	794	known to other nodes for a completely different process, causing messages
565	messages destined for that process to end up in an unrelated process.	795	destined for that process to end up in an unrelated process.
566		796
567	AEMP never reuses port IDs, so old messages or old port IDs floating	797	AEMP never reuses port IDs, so old messages or old port IDs floating
568	around in the network will not be sent to an unrelated port.	798	around in the network will not be sent to an unrelated port.
569		799
570	=item * Erlang uses unprotected connections, AEMP uses secure	800	=item * Erlang uses unprotected connections, AEMP uses secure
571	authentication and can use TLS.	801	authentication and can use TLS.
572		802
573	AEMP can use a proven protocol - SSL/TLS - to protect connections and	803	AEMP can use a proven protocol - SSL/TLS - to protect connections and
574	securely authenticate nodes.	804	securely authenticate nodes.
575		805
		806	=item * The AEMP protocol is optimised for both text-based and binary
		807	communications.
		808
		809	The AEMP protocol, unlike the Erlang protocol, supports both
		810	language-independent text-only protocols (good for debugging) and binary,
		811	language-specific serialisers (e.g. Storable).
		812
		813	It has also been carefully designed to be implementable in other languages
		814	with a minimum of work while gracefully degrading fucntionality to make the
		815	protocol simple.
		816
		817	=item * AEMP has more flexible monitoring options than Erlang.
		818
		819	In Erlang, you can chose to receive I<all> exit signals as messages
		820	or I<none>, there is no in-between, so monitoring single processes is
		821	difficult to implement. Monitoring in AEMP is more flexible than in
		822	Erlang, as one can choose between automatic kill, exit message or callback
		823	on a per-process basis.
		824
		825	=item * Erlang tries to hide remote/local connections, AEMP does not.
		826
		827	Monitoring in Erlang is not an indicator of process death/crashes,
		828	as linking is (except linking is unreliable in Erlang).
		829
		830	In AEMP, you don't "look up" registered port names or send to named ports
		831	that might or might not be persistent. Instead, you normally spawn a port
		832	on the remote node. The init function monitors the you, and you monitor
		833	the remote port. Since both monitors are local to the node, they are much
		834	more reliable.
		835
		836	This also saves round-trips and avoids sending messages to the wrong port
		837	(hard to do in Erlang).
		838
		839	=back
		840
		841	=head1 RATIONALE
		842
		843	=over 4
		844
		845	=item Why strings for ports and noderefs, why not objects?
		846
		847	We considered "objects", but found that the actual number of methods
		848	thatc an be called are very low. Since port IDs and noderefs travel over
		849	the network frequently, the serialising/deserialising would add lots of
		850	overhead, as well as having to keep a proxy object.
		851
		852	Strings can easily be printed, easily serialised etc. and need no special
		853	procedures to be "valid".
		854
		855	And a a miniport consists of a single closure stored in a global hash - it
		856	can't become much cheaper.
		857
		858	=item Why favour JSON, why not real serialising format such as Storable?
		859
		860	In fact, any AnyEvent::MP node will happily accept Storable as framing
		861	format, but currently there is no way to make a node use Storable by
		862	default.
		863
		864	The default framing protocol is JSON because a) JSON::XS is many times
		865	faster for small messages and b) most importantly, after years of
		866	experience we found that object serialisation is causing more problems
		867	than it gains: Just like function calls, objects simply do not travel
		868	easily over the network, mostly because they will always be a copy, so you
		869	always have to re-think your design.
		870
		871	Keeping your messages simple, concentrating on data structures rather than
		872	objects, will keep your messages clean, tidy and efficient.
		873
576	=back	874	=back
577		875
578	=head1 SEE ALSO	876	=head1 SEE ALSO
579		877
580	L<AnyEvent>.	878	L<AnyEvent>.

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Revision 1.53 by root, Fri Aug 14 15:31:21 2009 UTC