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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.35 by root, Thu Aug 6 10:21:48 2009 UTC vs.
Revision 1.68 by root, Fri Aug 28 23:06:33 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;
		17
		18	# ports are message endpoints
		19
		20	# sending messages
13	snd $port, type => data...;	21	snd $port, type => data...;
		22	snd $port, @msg;
		23	snd @msg_with_first_element_being_a_port;
14		24
15	$SELF # receiving/own port id in rcv callbacks	25	# creating/using ports, the simple way
		26	my $simple_port = port { my @msg = @_; 0 };
16		27
17	rcv $port, smartmatch => $cb->($port, @msg);	28	# creating/using ports, tagged message matching
18		29	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	31	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		32
24	# more, smarter, matches (_any_ is exported by this module)	33	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	34	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
27
28	# linking two ports, so they both crash together
29	lnk $port1, $port2;
30		35
31	# monitoring	36	# monitoring
32	mon $port, $cb->(@msg) # callback is invoked on death	37	mon $port, $cb->(@msg) # callback is invoked on death
33	mon $port, $otherport # kill otherport on abnormal death	38	mon $port, $otherport # kill otherport on abnormal death
34	mon $port, $otherport, @msg # send message on death	39	mon $port, $otherport, @msg # send message on death
35		40
		41	=head1 CURRENT STATUS
		42
		43	AnyEvent::MP - stable API, should work
		44	AnyEvent::MP::Intro - outdated
		45	AnyEvent::MP::Kernel - mostly stable
		46	AnyEvent::MP::Global - mostly stable
		47	AnyEvent::MP::Node - mostly stable, but internal anyways
		48	AnyEvent::MP::Transport - mostly stable, but internal anyways
		49
		50	stay tuned.
		51
36	=head1 DESCRIPTION	52	=head1 DESCRIPTION
37		53
38	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
39		55
40	Despite its simplicity, you can securely message other processes running	56	Despite its simplicity, you can securely message other processes running
41	on the same or other hosts.	57	on the same or other hosts, and you can supervise entities remotely.
42		58
43	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>
44	manual page.	60	manual page and the examples under F<eg/>.
45		61
46	At the moment, this module family is severly broken and underdocumented,	62	At the moment, this module family is a bit underdocumented.
47	so do not use. This was uploaded mainly to reserve the CPAN namespace -
48	stay tuned! The basic API should be finished, however.
49		63
50	=head1 CONCEPTS	64	=head1 CONCEPTS
51		65
52	=over 4	66	=over 4
53		67
54	=item port	68	=item port
55		69
56	A port is something you can send messages to (with the C<snd> function).	70	A port is something you can send messages to (with the C<snd> function).
57		71
58	Some ports allow you to register C<rcv> handlers that can match specific	72	Ports allow you to register C<rcv> handlers that can match all or just
59	messages. All C<rcv> handlers will receive messages they match, messages	73	some messages. Messages send to ports will not be queued, regardless of
60	will not be queued.	74	anything was listening for them or not.
61		75
62	=item port id - C<noderef#portname>	76	=item port ID - C<nodeid#portname>
63		77
64	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	78	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
65	separator, and a port name (a printable string of unspecified format). An	79	separator, and a port name (a printable string of unspecified format).
66	exception is the the node port, whose ID is identical to its node
67	reference.
68		80
69	=item node	81	=item node
70		82
71	A node is a single process containing at least one port - the node	83	A node is a single process containing at least one port - the node port,
72	port. You can send messages to node ports to find existing ports or to	84	which enables nodes to manage each other remotely, and to create new
73	create new ports, among other things.	85	ports.
74		86
75	Nodes are either private (single-process only), slaves (connected to a	87	Nodes are either public (have one or more listening ports) or private
76	master node only) or public nodes (connectable from unrelated nodes).	88	(no listening ports). Private nodes cannot talk to other private nodes
		89	currently.
77		90
78	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	91	=item node ID - C<[a-za-Z0-9_\-.:]+>
79		92
80	A node reference is a string that either simply identifies the node (for	93	A node ID is a string that uniquely identifies the node within a
81	private and slave nodes), or contains a recipe on how to reach a given	94	network. Depending on the configuration used, node IDs can look like a
82	node (for public nodes).	95	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		96	doesn't interpret node IDs in any way.
83		97
84	This recipe is simply a comma-separated list of C<address:port> pairs (for	98	=item binds - C<ip:port>
85	TCP/IP, other protocols might look different).
86		99
87	Node references come in two flavours: resolved (containing only numerical	100	Nodes can only talk to each other by creating some kind of connection to
88	addresses) or unresolved (where hostnames are used instead of addresses).	101	each other. To do this, nodes should listen on one or more local transport
		102	endpoints - binds. Currently, only standard C<ip:port> specifications can
		103	be used, which specify TCP ports to listen on.
89		104
90	Before using an unresolved node reference in a message you first have to	105	=item seeds - C<host:port>
91	resolve it.	106
		107	When a node starts, it knows nothing about the network. To teach the node
		108	about the network it first has to contact some other node within the
		109	network. This node is called a seed.
		110
		111	Seeds are transport endpoint(s) of as many nodes as one wants. Those 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
		117	Apart from being sued for seeding, seednodes are not special in any way -
		118	every public node can be a seednode.
92		119
93	=back	120	=back
94		121
95	=head1 VARIABLES/FUNCTIONS	122	=head1 VARIABLES/FUNCTIONS
96		123
…		…
98		125
99	=cut	126	=cut
100		127
101	package AnyEvent::MP;	128	package AnyEvent::MP;
102		129
103	use AnyEvent::MP::Base;	130	use AnyEvent::MP::Kernel;
104		131
105	use common::sense;	132	use common::sense;
106		133
107	use Carp ();	134	use Carp ();
108		135
109	use AE ();	136	use AE ();
110		137
111	use base "Exporter";	138	use base "Exporter";
112		139
113	our $VERSION = '0.1';	140	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		141
114	our @EXPORT = qw(	142	our @EXPORT = qw(
115	NODE $NODE *SELF node_of _any_	143	NODE $NODE *SELF node_of after
116	resolve_node initialise_node	144	initialise_node
117	snd rcv mon kil reg psub	145	snd rcv mon mon_guard kil reg psub spawn
118	port	146	port
119	);	147	);
120		148
121	our $SELF;	149	our $SELF;
122		150
…		…
126	kil $SELF, die => $msg;	154	kil $SELF, die => $msg;
127	}	155	}
128		156
129	=item $thisnode = NODE / $NODE	157	=item $thisnode = NODE / $NODE
130		158
131	The C<NODE> function returns, and the C<$NODE> variable contains	159	The C<NODE> function returns, and the C<$NODE> variable contains, the node
132	the noderef of the local node. The value is initialised by a call	160	ID of the node running in the current process. This value is initialised by
133	to C<become_public> or C<become_slave>, after which all local port	161	a call to C<initialise_node>.
134	identifiers become invalid.
135		162
136	=item $noderef = node_of $port	163	=item $nodeid = node_of $port
137		164
138	Extracts and returns the noderef from a portid or a noderef.	165	Extracts and returns the node ID from a port ID or a node ID.
139		166
140	=item initialise_node $noderef, $seednode, $seednode...	167	=item initialise_node $profile_name
141		168
142	=item initialise_node "slave/", $master, $master...
143
144	Before a node can talk to other nodes on the network it has to initialise	169	Before a node can talk to other nodes on the network (i.e. enter
145	itself - the minimum a node needs to know is it's own name, and optionally	170	"distributed mode") it has to initialise itself - the minimum a node needs
146	it should know the noderefs of some other nodes in the network.	171	to know is its own name, and optionally it should know the addresses of
		172	some other nodes in the network to discover other nodes.
147		173
148	This function initialises a node - it must be called exactly once (or	174	This function initialises a node - it must be called exactly once (or
149	never) before calling other AnyEvent::MP functions.	175	never) before calling other AnyEvent::MP functions.
150		176
151	All arguments are noderefs, which can be either resolved or unresolved.	177	The first argument is a profile name. If it is C<undef> or missing, then
		178	the current nodename will be used instead (i.e. F<uname -n>).
152		179
153	There are two types of networked nodes, public nodes and slave nodes:	180	The function then looks up the profile in the aemp configuration (see the
		181	L<aemp> commandline utility).
154		182
155	=over 4	183	If the profile specifies a node ID, then this will become the node ID of
		184	this process. If not, then the profile name will be used as node ID. The
		185	special node ID of C<anon/> will be replaced by a random node ID.
156		186
157	=item public nodes	187	The next step is to look up the binds in the profile, followed by binding
		188	aemp protocol listeners on all binds specified (it is possible and valid
		189	to have no binds, meaning that the node cannot be contacted form the
		190	outside. This means the node cannot talk to other nodes that also have no
		191	binds, but it can still talk to all "normal" nodes).
158		192
159	For public nodes, C<$noderef> must either be a (possibly unresolved)	193	If the profile does not specify a binds list, then the node ID will be
160	noderef, in which case it will be resolved, or C<undef> (or missing), in	194	treated as if it were of the form C<host:port>, which will be resolved and
161	which case the noderef will be guessed.	195	used as binds list.
162		196
163	Afterwards, the node will bind itself on all endpoints and try to connect	197	Lastly, the seeds list from the profile is passed to the
164	to all additional C<$seednodes> that are specified. Seednodes are optional	198	L<AnyEvent::MP::Global> module, which will then use it to keep
165	and can be used to quickly bootstrap the node into an existing network.	199	connectivity with at least on of those seed nodes at any point in time.
166		200
167	=item slave nodes	201	Example: become a distributed node listening on the guessed noderef, or
168		202	the one specified via C<aemp> for the current node. This should be the
169	When the C<$noderef> is the special string C<slave/>, then the node will	203	most common form of invocation for "daemon"-type nodes.
170	become a slave node. Slave nodes cannot be contacted from outside and will
171	route most of their traffic to the master node that they attach to.
172
173	At least one additional noderef is required: The node will try to connect
174	to all of them and will become a slave attached to the first node it can
175	successfully connect to.
176
177	=back
178
179	This function will block until all nodes have been resolved and, for slave
180	nodes, until it has successfully established a connection to a master
181	server.
182
183	Example: become a public node listening on the default node.
184		204
185	initialise_node;	205	initialise_node;
186		206
187	Example: become a public node, and try to contact some well-known master	207	Example: become an anonymous node. This form is often used for commandline
188	servers to become part of the network.	208	clients.
189		209
190	initialise_node undef, "master1", "master2";
191
192	Example: become a public node listening on port C<4041>.
193
194	initialise_node 4041;	210	initialise_node "anon/";
195		211
196	Example: become a public node, only visible on localhost port 4044.	212	Example: become a distributed node. If there is no profile of the given
		213	name, or no binds list was specified, resolve C<localhost:4044> and bind
		214	on the resulting addresses.
197		215
198	initialise_node "locahost:4044";	216	initialise_node "localhost:4044";
199
200	Example: become a slave node to any of the specified master servers.
201
202	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
203
204	=item $cv = resolve_node $noderef
205
206	Takes an unresolved node reference that may contain hostnames and
207	abbreviated IDs, resolves all of them and returns a resolved node
208	reference.
209
210	In addition to C<address:port> pairs allowed in resolved noderefs, the
211	following forms are supported:
212
213	=over 4
214
215	=item the empty string
216
217	An empty-string component gets resolved as if the default port (4040) was
218	specified.
219
220	=item naked port numbers (e.g. C<1234>)
221
222	These are resolved by prepending the local nodename and a colon, to be
223	further resolved.
224
225	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
226
227	These are resolved by using AnyEvent::DNS to resolve them, optionally
228	looking up SRV records for the C<aemp=4040> port, if no port was
229	specified.
230
231	=back
232		217
233	=item $SELF	218	=item $SELF
234		219
235	Contains the current port id while executing C<rcv> callbacks or C<psub>	220	Contains the current port id while executing C<rcv> callbacks or C<psub>
236	blocks.	221	blocks.
237		222
238	=item SELF, %SELF, @SELF...	223	=item *SELF, SELF, %SELF, @SELF...
239		224
240	Due to some quirks in how perl exports variables, it is impossible to	225	Due to some quirks in how perl exports variables, it is impossible to
241	just export C<$SELF>, all the symbols called C<SELF> are exported by this	226	just export C<$SELF>, all the symbols named C<SELF> are exported by this
242	module, but only C<$SELF> is currently used.	227	module, but only C<$SELF> is currently used.
243		228
244	=item snd $port, type => @data	229	=item snd $port, type => @data
245		230
246	=item snd $port, @msg	231	=item snd $port, @msg
247		232
248	Send the given message to the given port ID, which can identify either	233	Send the given message to the given port, which can identify either a
249	a local or a remote port, and can be either a string or soemthignt hat	234	local or a remote port, and must be a port ID.
250	stringifies a sa port ID (such as a port object :).
251		235
252	While the message can be about anything, it is highly recommended to use a	236	While the message can be almost anything, it is highly recommended to
253	string as first element (a portid, or some word that indicates a request	237	use a string as first element (a port ID, or some word that indicates a
254	type etc.).	238	request type etc.) and to consist if only simple perl values (scalars,
		239	arrays, hashes) - if you think you need to pass an object, think again.
255		240
256	The message data effectively becomes read-only after a call to this	241	The message data logically becomes read-only after a call to this
257	function: modifying any argument is not allowed and can cause many	242	function: modifying any argument (or values referenced by them) is
258	problems.	243	forbidden, as there can be considerable time between the call to C<snd>
		244	and the time the message is actually being serialised - in fact, it might
		245	never be copied as within the same process it is simply handed to the
		246	receiving port.
259		247
260	The type of data you can transfer depends on the transport protocol: when	248	The type of data you can transfer depends on the transport protocol: when
261	JSON is used, then only strings, numbers and arrays and hashes consisting	249	JSON is used, then only strings, numbers and arrays and hashes consisting
262	of those are allowed (no objects). When Storable is used, then anything	250	of those are allowed (no objects). When Storable is used, then anything
263	that Storable can serialise and deserialise is allowed, and for the local	251	that Storable can serialise and deserialise is allowed, and for the local
264	node, anything can be passed.	252	node, anything can be passed. Best rely only on the common denominator of
		253	these.
265		254
266	=item $local_port = port	255	=item $local_port = port
267		256
268	Create a new local port object that can be used either as a pattern	257	Create a new local port object and returns its port ID. Initially it has
269	matching port ("full port") or a single-callback port ("miniport"),	258	no callbacks set and will throw an error when it receives messages.
270	depending on how C<rcv> callbacks are bound to the object.
271		259
272	=item $port = port { my @msg = @_; $finished }	260	=item $local_port = port { my @msg = @_ }
273		261
274	Creates a "miniport", that is, a very lightweight port without any pattern	262	Creates a new local port, and returns its ID. Semantically the same as
275	matching behind it, and returns its ID. Semantically the same as creating
276	a port and calling C<rcv $port, $callback> on it.	263	creating a port and calling C<rcv $port, $callback> on it.
277		264
278	The block will be called for every message received on the port. When the	265	The block will be called for every message received on the port, with the
279	callback returns a true value its job is considered "done" and the port	266	global variable C<$SELF> set to the port ID. Runtime errors will cause the
280	will be destroyed. Otherwise it will stay alive.	267	port to be C<kil>ed. The message will be passed as-is, no extra argument
		268	(i.e. no port ID) will be passed to the callback.
281		269
282	The message will be passed as-is, no extra argument (i.e. no port id) will	270	If you want to stop/destroy the port, simply C<kil> it:
283	be passed to the callback.
284		271
285	If you need the local port id in the callback, this works nicely:	272	my $port = port {
286		273	my @msg = @_;
287	my $port; $port = port {	274	...
288	snd $otherport, reply => $port;	275	kil $SELF;
289	};	276	};
290		277
291	=cut	278	=cut
292		279
293	sub rcv($@);	280	sub rcv($@);
		281
		282	sub _kilme {
		283	die "received message on port without callback";
		284	}
294		285
295	sub port(;&) {	286	sub port(;&) {
296	my $id = "$UNIQ." . $ID++;	287	my $id = "$UNIQ." . $ID++;
297	my $port = "$NODE#$id";	288	my $port = "$NODE#$id";
298		289
299	if (@_) {	290	rcv $port, shift \|\| \&_kilme;
300	rcv $port, shift;
301	} else {
302	$PORT{$id} = sub { }; # nop
303	}
304		291
305	$port	292	$port
306	}	293	}
307		294
308	=item reg $port, $name
309
310	Registers the given port under the name C<$name>. If the name already
311	exists it is replaced.
312
313	A port can only be registered under one well known name.
314
315	A port automatically becomes unregistered when it is killed.
316
317	=cut
318
319	sub reg(@) {
320	my ($port, $name) = @_;
321
322	$REG{$name} = $port;
323	}
324
325	=item rcv $port, $callback->(@msg)	295	=item rcv $local_port, $callback->(@msg)
326		296
327	Replaces the callback on the specified miniport (after converting it to	297	Replaces the default callback on the specified port. There is no way to
328	one if required).	298	remove the default callback: use C<sub { }> to disable it, or better
329		299	C<kil> the port when it is no longer needed.
330	=item rcv $port, tagstring => $callback->(@msg), ...
331
332	=item rcv $port, $smartmatch => $callback->(@msg), ...
333
334	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
335
336	Register callbacks to be called on matching messages on the given full
337	port (after converting it to one if required).
338
339	The callback has to return a true value when its work is done, after
340	which is will be removed, or a false value in which case it will stay
341	registered.
342		300
343	The global C<$SELF> (exported by this module) contains C<$port> while	301	The global C<$SELF> (exported by this module) contains C<$port> while
344	executing the callback.	302	executing the callback. Runtime errors during callback execution will
		303	result in the port being C<kil>ed.
345		304
346	Runtime errors wdurign callback execution will result in the port being	305	The default callback received all messages not matched by a more specific
347	C<kil>ed.	306	C<tag> match.
348		307
349	If the match is an array reference, then it will be matched against the	308	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
350	first elements of the message, otherwise only the first element is being
351	matched.
352		309
353	Any element in the match that is specified as C<_any_> (a function	310	Register (or replace) callbacks to be called on messages starting with the
354	exported by this module) matches any single element of the message.	311	given tag on the given port (and return the port), or unregister it (when
		312	C<$callback> is C<$undef> or missing). There can only be one callback
		313	registered for each tag.
355		314
356	While not required, it is highly recommended that the first matching	315	The original message will be passed to the callback, after the first
357	element is a string identifying the message. The one-string-only match is	316	element (the tag) has been removed. The callback will use the same
358	also the most efficient match (by far).	317	environment as the default callback (see above).
		318
		319	Example: create a port and bind receivers on it in one go.
		320
		321	my $port = rcv port,
		322	msg1 => sub { ... },
		323	msg2 => sub { ... },
		324	;
		325
		326	Example: create a port, bind receivers and send it in a message elsewhere
		327	in one go:
		328
		329	snd $otherport, reply =>
		330	rcv port,
		331	msg1 => sub { ... },
		332	...
		333	;
		334
		335	Example: temporarily register a rcv callback for a tag matching some port
		336	(e.g. for a rpc reply) and unregister it after a message was received.
		337
		338	rcv $port, $otherport => sub {
		339	my @reply = @_;
		340
		341	rcv $SELF, $otherport;
		342	};
359		343
360	=cut	344	=cut
361		345
362	sub rcv($@) {	346	sub rcv($@) {
363	my $port = shift;	347	my $port = shift;
364	my ($noderef, $portid) = split /#/, $port, 2;	348	my ($noderef, $portid) = split /#/, $port, 2;
365		349
366	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	350	$NODE{$noderef} == $NODE{""}
367	or Carp::croak "$port: rcv can only be called on local ports, caught";	351	or Carp::croak "$port: rcv can only be called on local ports, caught";
368		352
369	if (@_ == 1) {	353	while (@_) {
		354	if (ref $_[0]) {
		355	if (my $self = $PORT_DATA{$portid}) {
		356	"AnyEvent::MP::Port" eq ref $self
		357	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		358
		359	$self->[2] = shift;
		360	} else {
370	my $cb = shift;	361	my $cb = shift;
371	delete $PORT_DATA{$portid};
372	$PORT{$portid} = sub {	362	$PORT{$portid} = sub {
373	local $SELF = $port;	363	local $SELF = $port;
374	eval {	364	eval { &$cb }; _self_die if $@;
375	&$cb	365	};
376	and kil $port;
377	};	366	}
378	_self_die if $@;	367	} elsif (defined $_[0]) {
379	};
380	} else {
381	my $self = $PORT_DATA{$portid} \|\|= do {	368	my $self = $PORT_DATA{$portid} \|\|= do {
382	my $self = bless {	369	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
383	id => $port,
384	}, "AnyEvent::MP::Port";
385		370
386	$PORT{$portid} = sub {	371	$PORT{$portid} = sub {
387	local $SELF = $port;	372	local $SELF = $port;
388		373
389	eval {
390	for (@{ $self->{rc0}{$_[0]} }) {	374	if (my $cb = $self->[1]{$_[0]}) {
391	$_ && &{$_->[0]}	375	shift;
392	&& undef $_;	376	eval { &$cb }; _self_die if $@;
393	}	377	} else {
394
395	for (@{ $self->{rcv}{$_[0]} }) {
396	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
397	&& &{$_->[0]}	378	&{ $self->[0] };
398	&& undef $_;
399	}
400
401	for (@{ $self->{any} }) {
402	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
403	&& &{$_->[0]}
404	&& undef $_;
405	}	379	}
406	};	380	};
407	_self_die if $@;	381
		382	$self
408	};	383	};
409		384
410	$self
411	};
412
413	"AnyEvent::MP::Port" eq ref $self	385	"AnyEvent::MP::Port" eq ref $self
414	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	386	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
415		387
416	while (@_) {
417	my ($match, $cb) = splice @_, 0, 2;	388	my ($tag, $cb) = splice @_, 0, 2;
418		389
419	if (!ref $match) {	390	if (defined $cb) {
420	push @{ $self->{rc0}{$match} }, [$cb];	391	$self->[1]{$tag} = $cb;
421	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
422	my ($type, @match) = @$match;
423	@match
424	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
425	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
426	} else {	392	} else {
427	push @{ $self->{any} }, [$cb, $match];	393	delete $self->[1]{$tag};
428	}	394	}
429	}	395	}
430	}	396	}
431		397
432	$port	398	$port
…		…
468	$res	434	$res
469	}	435	}
470	}	436	}
471	}	437	}
472		438
473	=item $guard = mon $port, $cb->(@reason)	439	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
474		440
475	=item $guard = mon $port, $otherport	441	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
476		442
477	=item $guard = mon $port, $otherport, @msg	443	=item $guard = mon $port # kill $SELF when $port dies
478		444
		445	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		446
479	Monitor the given port and do something when the port is killed.	447	Monitor the given port and do something when the port is killed or
		448	messages to it were lost, and optionally return a guard that can be used
		449	to stop monitoring again.
480		450
		451	C<mon> effectively guarantees that, in the absence of hardware failures,
		452	after starting the monitor, either all messages sent to the port will
		453	arrive, or the monitoring action will be invoked after possible message
		454	loss has been detected. No messages will be lost "in between" (after
		455	the first lost message no further messages will be received by the
		456	port). After the monitoring action was invoked, further messages might get
		457	delivered again.
		458
		459	Note that monitoring-actions are one-shot: once messages are lost (and a
		460	monitoring alert was raised), they are removed and will not trigger again.
		461
481	In the first form, the callback is simply called with any number	462	In the first form (callback), the callback is simply called with any
482	of C<@reason> elements (no @reason means that the port was deleted	463	number of C<@reason> elements (no @reason means that the port was deleted
483	"normally"). Note also that I<< the callback B<must> never die >>, so use	464	"normally"). Note also that I<< the callback B<must> never die >>, so use
484	C<eval> if unsure.	465	C<eval> if unsure.
485		466
486	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	467	In the second form (another port given), the other port (C<$rcvport>)
487	a @reason was specified, i.e. on "normal" kils nothing happens, while	468	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
488	under all other conditions, the other port is killed with the same reason.	469	"normal" kils nothing happens, while under all other conditions, the other
		470	port is killed with the same reason.
489		471
		472	The third form (kill self) is the same as the second form, except that
		473	C<$rvport> defaults to C<$SELF>.
		474
490	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	475	In the last form (message), a message of the form C<@msg, @reason> will be
		476	C<snd>.
		477
		478	As a rule of thumb, monitoring requests should always monitor a port from
		479	a local port (or callback). The reason is that kill messages might get
		480	lost, just like any other message. Another less obvious reason is that
		481	even monitoring requests can get lost (for exmaple, when the connection
		482	to the other node goes down permanently). When monitoring a port locally
		483	these problems do not exist.
491		484
492	Example: call a given callback when C<$port> is killed.	485	Example: call a given callback when C<$port> is killed.
493		486
494	mon $port, sub { warn "port died because of <@_>\n" };	487	mon $port, sub { warn "port died because of <@_>\n" };
495		488
496	Example: kill ourselves when C<$port> is killed abnormally.	489	Example: kill ourselves when C<$port> is killed abnormally.
497		490
498	mon $port, $self;	491	mon $port;
499		492
500	Example: send us a restart message another C<$port> is killed.	493	Example: send us a restart message when another C<$port> is killed.
501		494
502	mon $port, $self => "restart";	495	mon $port, $self => "restart";
503		496
504	=cut	497	=cut
505		498
506	sub mon {	499	sub mon {
507	my ($noderef, $port) = split /#/, shift, 2;	500	my ($noderef, $port) = split /#/, shift, 2;
508		501
509	my $node = $NODE{$noderef} \|\| add_node $noderef;	502	my $node = $NODE{$noderef} \|\| add_node $noderef;
510		503
511	my $cb = shift;	504	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
512		505
513	unless (ref $cb) {	506	unless (ref $cb) {
514	if (@_) {	507	if (@_) {
515	# send a kill info message	508	# send a kill info message
516	my (@msg) = ($cb, @_);	509	my (@msg) = ($cb, @_);
…		…
534	is killed, the references will be freed.	527	is killed, the references will be freed.
535		528
536	Optionally returns a guard that will stop the monitoring.	529	Optionally returns a guard that will stop the monitoring.
537		530
538	This function is useful when you create e.g. timers or other watchers and	531	This function is useful when you create e.g. timers or other watchers and
539	want to free them when the port gets killed:	532	want to free them when the port gets killed (note the use of C<psub>):
540		533
541	$port->rcv (start => sub {	534	$port->rcv (start => sub {
542	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	535	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
543	undef $timer if 0.9 < rand;	536	undef $timer if 0.9 < rand;
544	});	537	});
545	});	538	});
546		539
547	=cut	540	=cut
548		541
549	sub mon_guard {	542	sub mon_guard {
550	my ($port, @refs) = @_;	543	my ($port, @refs) = @_;
551		544
		545	#TODO: mon-less form?
		546
552	mon $port, sub { 0 && @refs }	547	mon $port, sub { 0 && @refs }
553	}	548	}
554		549
555	=item lnk $port1, $port2
556
557	Link two ports. This is simply a shorthand for:
558
559	mon $port1, $port2;
560	mon $port2, $port1;
561
562	It means that if either one is killed abnormally, the other one gets
563	killed as well.
564
565	=item kil $port[, @reason]	550	=item kil $port[, @reason]
566		551
567	Kill the specified port with the given C<@reason>.	552	Kill the specified port with the given C<@reason>.
568		553
569	If no C<@reason> is specified, then the port is killed "normally" (linked	554	If no C<@reason> is specified, then the port is killed "normally" (ports
570	ports will not be kileld, or even notified).	555	monitoring other ports will not necessarily die because a port dies
		556	"normally").
571		557
572	Otherwise, linked ports get killed with the same reason (second form of	558	Otherwise, linked ports get killed with the same reason (second form of
573	C<mon>, see below).	559	C<mon>, see above).
574		560
575	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	561	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
576	will be reported as reason C<< die => $@ >>.	562	will be reported as reason C<< die => $@ >>.
577		563
578	Transport/communication errors are reported as C<< transport_error =>	564	Transport/communication errors are reported as C<< transport_error =>
579	$message >>.	565	$message >>.
580		566
581	=back
582
583	=head1 NODE MESSAGES
584
585	Nodes understand the following messages sent to them. Many of them take
586	arguments called C<@reply>, which will simply be used to compose a reply
587	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
588	the remaining arguments are simply the message data.
589
590	While other messages exist, they are not public and subject to change.
591
592	=over 4
593
594	=cut	567	=cut
595		568
596	=item lookup => $name, @reply	569	=item $port = spawn $node, $initfunc[, @initdata]
597		570
598	Replies with the port ID of the specified well-known port, or C<undef>.	571	Creates a port on the node C<$node> (which can also be a port ID, in which
		572	case it's the node where that port resides).
599		573
600	=item devnull => ...	574	The port ID of the newly created port is returned immediately, and it is
		575	possible to immediately start sending messages or to monitor the port.
601		576
602	Generic data sink/CPU heat conversion.	577	After the port has been created, the init function is called on the remote
		578	node, in the same context as a C<rcv> callback. This function must be a
		579	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		580	specify a function in the main program, use C<::name>.
603		581
604	=item relay => $port, @msg	582	If the function doesn't exist, then the node tries to C<require>
		583	the package, then the package above the package and so on (e.g.
		584	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		585	exists or it runs out of package names.
605		586
606	Simply forwards the message to the given port.	587	The init function is then called with the newly-created port as context
		588	object (C<$SELF>) and the C<@initdata> values as arguments.
607		589
608	=item eval => $string[ @reply]	590	A common idiom is to pass a local port, immediately monitor the spawned
		591	port, and in the remote init function, immediately monitor the passed
		592	local port. This two-way monitoring ensures that both ports get cleaned up
		593	when there is a problem.
609		594
610	Evaluates the given string. If C<@reply> is given, then a message of the	595	Example: spawn a chat server port on C<$othernode>.
611	form C<@reply, $@, @evalres> is sent.
612		596
613	Example: crash another node.	597	# this node, executed from within a port context:
		598	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		599	mon $server;
614		600
615	snd $othernode, eval => "exit";	601	# init function on C<$othernode>
		602	sub connect {
		603	my ($srcport) = @_;
616		604
617	=item time => @reply	605	mon $srcport;
618		606
619	Replies the the current node time to C<@reply>.	607	rcv $SELF, sub {
		608	...
		609	};
		610	}
620		611
621	Example: tell the current node to send the current time to C<$myport> in a	612	=cut
622	C<timereply> message.
623		613
624	snd $NODE, time => $myport, timereply => 1, 2;	614	sub _spawn {
625	# => snd $myport, timereply => 1, 2, <time>	615	my $port = shift;
		616	my $init = shift;
		617
		618	local $SELF = "$NODE#$port";
		619	eval {
		620	&{ load_func $init }
		621	};
		622	_self_die if $@;
		623	}
		624
		625	sub spawn(@) {
		626	my ($noderef, undef) = split /#/, shift, 2;
		627
		628	my $id = "$RUNIQ." . $ID++;
		629
		630	$_[0] =~ /::/
		631	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		632
		633	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		634
		635	"$noderef#$id"
		636	}
		637
		638	=item after $timeout, @msg
		639
		640	=item after $timeout, $callback
		641
		642	Either sends the given message, or call the given callback, after the
		643	specified number of seconds.
		644
		645	This is simply a utility function that comes in handy at times - the
		646	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		647	so it may go away in the future.
		648
		649	=cut
		650
		651	sub after($@) {
		652	my ($timeout, @action) = @_;
		653
		654	my $t; $t = AE::timer $timeout, 0, sub {
		655	undef $t;
		656	ref $action[0]
		657	? $action[0]()
		658	: snd @action;
		659	};
		660	}
626		661
627	=back	662	=back
628		663
629	=head1 AnyEvent::MP vs. Distributed Erlang	664	=head1 AnyEvent::MP vs. Distributed Erlang
630		665
…		…
640		675
641	Despite the similarities, there are also some important differences:	676	Despite the similarities, there are also some important differences:
642		677
643	=over 4	678	=over 4
644		679
645	=item * Node references contain the recipe on how to contact them.	680	=item * Node IDs are arbitrary strings in AEMP.
646		681
647	Erlang relies on special naming and DNS to work everywhere in the	682	Erlang relies on special naming and DNS to work everywhere in the same
648	same way. AEMP relies on each node knowing it's own address(es), with	683	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
649	convenience functionality.	684	configuraiton or DNS), but will otherwise discover other odes itself.
650		685
651	This means that AEMP requires a less tightly controlled environment at the	686	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
652	cost of longer node references and a slightly higher management overhead.	687	uses "local ports are like remote ports".
		688
		689	The failure modes for local ports are quite different (runtime errors
		690	only) then for remote ports - when a local port dies, you I<know> it dies,
		691	when a connection to another node dies, you know nothing about the other
		692	port.
		693
		694	Erlang pretends remote ports are as reliable as local ports, even when
		695	they are not.
		696
		697	AEMP encourages a "treat remote ports differently" philosophy, with local
		698	ports being the special case/exception, where transport errors cannot
		699	occur.
653		700
654	=item * Erlang uses processes and a mailbox, AEMP does not queue.	701	=item * Erlang uses processes and a mailbox, AEMP does not queue.
655		702
656	Erlang uses processes that selctively receive messages, and therefore	703	Erlang uses processes that selectively receive messages, and therefore
657	needs a queue. AEMP is event based, queuing messages would serve no useful	704	needs a queue. AEMP is event based, queuing messages would serve no
658	purpose.	705	useful purpose. For the same reason the pattern-matching abilities of
		706	AnyEvent::MP are more limited, as there is little need to be able to
		707	filter messages without dequeing them.
659		708
660	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	709	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
661		710
662	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	711	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
663		712
664	Sending messages in Erlang is synchronous and blocks the process. AEMP	713	Sending messages in Erlang is synchronous and blocks the process (and
665	sends are immediate, connection establishment is handled in the	714	so does not need a queue that can overflow). AEMP sends are immediate,
666	background.	715	connection establishment is handled in the background.
667		716
668	=item * Erlang can silently lose messages, AEMP cannot.	717	=item * Erlang suffers from silent message loss, AEMP does not.
669		718
670	Erlang makes few guarantees on messages delivery - messages can get lost	719	Erlang makes few guarantees on messages delivery - messages can get lost
671	without any of the processes realising it (i.e. you send messages a, b,	720	without any of the processes realising it (i.e. you send messages a, b,
672	and c, and the other side only receives messages a and c).	721	and c, and the other side only receives messages a and c).
673		722
674	AEMP guarantees correct ordering, and the guarantee that there are no	723	AEMP guarantees correct ordering, and the guarantee that after one message
675	holes in the message sequence.	724	is lost, all following ones sent to the same port are lost as well, until
676		725	monitoring raises an error, so there are no silent "holes" in the message
677	=item * In Erlang, processes can be declared dead and later be found to be	726	sequence.
678	alive.
679
680	In Erlang it can happen that a monitored process is declared dead and
681	linked processes get killed, but later it turns out that the process is
682	still alive - and can receive messages.
683
684	In AEMP, when port monitoring detects a port as dead, then that port will
685	eventually be killed - it cannot happen that a node detects a port as dead
686	and then later sends messages to it, finding it is still alive.
687		727
688	=item * Erlang can send messages to the wrong port, AEMP does not.	728	=item * Erlang can send messages to the wrong port, AEMP does not.
689		729
690	In Erlang it is quite possible that a node that restarts reuses a process	730	In Erlang it is quite likely that a node that restarts reuses a process ID
691	ID known to other nodes for a completely different process, causing	731	known to other nodes for a completely different process, causing messages
692	messages destined for that process to end up in an unrelated process.	732	destined for that process to end up in an unrelated process.
693		733
694	AEMP never reuses port IDs, so old messages or old port IDs floating	734	AEMP never reuses port IDs, so old messages or old port IDs floating
695	around in the network will not be sent to an unrelated port.	735	around in the network will not be sent to an unrelated port.
696		736
697	=item * Erlang uses unprotected connections, AEMP uses secure	737	=item * Erlang uses unprotected connections, AEMP uses secure
698	authentication and can use TLS.	738	authentication and can use TLS.
699		739
700	AEMP can use a proven protocol - SSL/TLS - to protect connections and	740	AEMP can use a proven protocol - TLS - to protect connections and
701	securely authenticate nodes.	741	securely authenticate nodes.
702		742
703	=item * The AEMP protocol is optimised for both text-based and binary	743	=item * The AEMP protocol is optimised for both text-based and binary
704	communications.	744	communications.
705		745
706	The AEMP protocol, unlike the Erlang protocol, supports both	746	The AEMP protocol, unlike the Erlang protocol, supports both programming
707	language-independent text-only protocols (good for debugging) and binary,	747	language independent text-only protocols (good for debugging) and binary,
708	language-specific serialisers (e.g. Storable).	748	language-specific serialisers (e.g. Storable). By default, unless TLS is
		749	used, the protocol is actually completely text-based.
709		750
710	It has also been carefully designed to be implementable in other languages	751	It has also been carefully designed to be implementable in other languages
711	with a minimum of work while gracefully degrading fucntionality to make the	752	with a minimum of work while gracefully degrading functionality to make the
712	protocol simple.	753	protocol simple.
713		754
714	=item * AEMP has more flexible monitoring options than Erlang.	755	=item * AEMP has more flexible monitoring options than Erlang.
715		756
716	In Erlang, you can chose to receive I<all> exit signals as messages	757	In Erlang, you can chose to receive I<all> exit signals as messages
717	or I<none>, there is no in-between, so monitoring single processes is	758	or I<none>, there is no in-between, so monitoring single processes is
718	difficult to implement. Monitoring in AEMP is more flexible than in	759	difficult to implement. Monitoring in AEMP is more flexible than in
719	Erlang, as one can choose between automatic kill, exit message or callback	760	Erlang, as one can choose between automatic kill, exit message or callback
720	on a per-process basis.	761	on a per-process basis.
721		762
722	=item * Erlang has different semantics for monitoring and linking, AEMP has the same.	763	=item * Erlang tries to hide remote/local connections, AEMP does not.
723		764
724	Monitoring in Erlang is not an indicator of process death/crashes,	765	Monitoring in Erlang is not an indicator of process death/crashes, in the
725	as linking is (except linking is unreliable in Erlang). In AEMP, the	766	same way as linking is (except linking is unreliable in Erlang).
726	semantics of monitoring and linking are identical, linking is simply	767
727	two-way monitoring with automatic kill.	768	In AEMP, you don't "look up" registered port names or send to named ports
		769	that might or might not be persistent. Instead, you normally spawn a port
		770	on the remote node. The init function monitors you, and you monitor the
		771	remote port. Since both monitors are local to the node, they are much more
		772	reliable (no need for C<spawn_link>).
		773
		774	This also saves round-trips and avoids sending messages to the wrong port
		775	(hard to do in Erlang).
728		776
729	=back	777	=back
730		778
		779	=head1 RATIONALE
		780
		781	=over 4
		782
		783	=item Why strings for port and node IDs, why not objects?
		784
		785	We considered "objects", but found that the actual number of methods
		786	that can be called are quite low. Since port and node IDs travel over
		787	the network frequently, the serialising/deserialising would add lots of
		788	overhead, as well as having to keep a proxy object everywhere.
		789
		790	Strings can easily be printed, easily serialised etc. and need no special
		791	procedures to be "valid".
		792
		793	And as a result, a miniport consists of a single closure stored in a
		794	global hash - it can't become much cheaper.
		795
		796	=item Why favour JSON, why not a real serialising format such as Storable?
		797
		798	In fact, any AnyEvent::MP node will happily accept Storable as framing
		799	format, but currently there is no way to make a node use Storable by
		800	default (although all nodes will accept it).
		801
		802	The default framing protocol is JSON because a) JSON::XS is many times
		803	faster for small messages and b) most importantly, after years of
		804	experience we found that object serialisation is causing more problems
		805	than it solves: Just like function calls, objects simply do not travel
		806	easily over the network, mostly because they will always be a copy, so you
		807	always have to re-think your design.
		808
		809	Keeping your messages simple, concentrating on data structures rather than
		810	objects, will keep your messages clean, tidy and efficient.
		811
		812	=back
		813
731	=head1 SEE ALSO	814	=head1 SEE ALSO
		815
		816	L<AnyEvent::MP::Intro> - a gentle introduction.
		817
		818	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		819
		820	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		821	your applications.
732		822
733	L<AnyEvent>.	823	L<AnyEvent>.
734		824
735	=head1 AUTHOR	825	=head1 AUTHOR
736		826

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.35 by root, Thu Aug 6 10:21:48 2009 UTC vs. Revision 1.68 by root, Fri Aug 28 23:06:33 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.35 by root, Thu Aug 6 10:21:48 2009 UTC vs.
Revision 1.68 by root, Fri Aug 28 23:06:33 2009 UTC