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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.52 by root, Fri Aug 14 15:13:20 2009 UTC vs.
Revision 1.77 by elmex, Thu Sep 3 07:57:30 2009 UTC

…		…
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; # -OR-	15	configure;
17	initialise_node "localhost:4040"; # -OR-
18	initialise_node "slave/", "localhost:4040"
19		16
20	# ports are message endpoints	17	# ports are message destinations
21		18
22	# sending messages	19	# sending messages
23	snd $port, type => data...;	20	snd $port, type => data...;
24	snd $port, @msg;	21	snd $port, @msg;
25	snd @msg_with_first_element_being_a_port;	22	snd @msg_with_first_element_being_a_port;
26		23
27	# creating/using ports, the simple way	24	# creating/using ports, the simple way
28	my $somple_port = port { my @msg = @_; 0 };	25	my $simple_port = port { my @msg = @_ };
29		26
30	# creating/using ports, tagged message matching	27	# creating/using ports, tagged message matching
31	my $port = port;	28	my $port = port;
32	rcv $port, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
33	rcv $port, pong => sub { warn "pong received\n"; 0 };	30	rcv $port, pong => sub { warn "pong received\n" };
34		31
35	# create a port on another node	32	# create a port on another node
36	my $port = spawn $node, $initfunc, @initdata;	33	my $port = spawn $node, $initfunc, @initdata;
37		34
38	# monitoring	35	# monitoring
…		…
40	mon $port, $otherport # kill otherport on abnormal death	37	mon $port, $otherport # kill otherport on abnormal death
41	mon $port, $otherport, @msg # send message on death	38	mon $port, $otherport, @msg # send message on death
42		39
43	=head1 CURRENT STATUS	40	=head1 CURRENT STATUS
44		41
		42	bin/aemp - stable.
45	AnyEvent::MP - stable API, should work	43	AnyEvent::MP - stable API, should work.
46	AnyEvent::MP::Intro - outdated	44	AnyEvent::MP::Intro - explains most concepts.
47	AnyEvent::MP::Kernel - WIP
48	AnyEvent::MP::Transport - mostly stable	45	AnyEvent::MP::Kernel - mostly stable.
		46	AnyEvent::MP::Global - stable API, protocol not yet final.
49		47
50	stay tuned.	48	stay tuned.
51		49
52	=head1 DESCRIPTION	50	=head1 DESCRIPTION
53		51
54	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
55		53
56	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
57	on the same or other hosts.	55	on the same or other hosts, and you can supervise entities remotely.
58		56
59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
60	manual page.	58	manual page and the examples under F<eg/>.
61
62	At the moment, this module family is severly broken and underdocumented,
63	so do not use. This was uploaded mainly to reserve the CPAN namespace -
64	stay tuned!
65		59
66	=head1 CONCEPTS	60	=head1 CONCEPTS
67		61
68	=over 4	62	=over 4
69		63
70	=item port	64	=item port
71		65
72	A port is something you can send messages to (with the C<snd> function).	66	A port is something you can send messages to (with the C<snd> function).
73		67
74	Some ports allow you to register C<rcv> handlers that can match specific	68	Ports allow you to register C<rcv> handlers that can match all or just
75	messages. All C<rcv> handlers will receive messages they match, messages	69	some messages. Messages send to ports will not be queued, regardless of
76	will not be queued.	70	anything was listening for them or not.
77		71
78	=item port id - C<noderef#portname>	72	=item port ID - C<nodeid#portname>
79		73
80	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	74	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
81	separator, and a port name (a printable string of unspecified format). An	75	separator, and a port name (a printable string of unspecified format).
82	exception is the the node port, whose ID is identical to its node
83	reference.
84		76
85	=item node	77	=item node
86		78
87	A node is a single process containing at least one port - the node	79	A node is a single process containing at least one port - the node port,
88	port. You can send messages to node ports to find existing ports or to	80	which enables nodes to manage each other remotely, and to create new
89	create new ports, among other things.	81	ports.
90		82
91	Nodes are either private (single-process only), slaves (connected to a	83	Nodes are either public (have one or more listening ports) or private
92	master node only) or public nodes (connectable from unrelated nodes).	84	(no listening ports). Private nodes cannot talk to other private nodes
		85	currently.
93		86
94	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	87	=item node ID - C<[a-za-Z0-9_\-.:]+>
95		88
96	A node reference is a string that either simply identifies the node (for	89	A node ID is a string that uniquely identifies the node within a
97	private and slave nodes), or contains a recipe on how to reach a given	90	network. Depending on the configuration used, node IDs can look like a
98	node (for public nodes).	91	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		92	doesn't interpret node IDs in any way.
99		93
100	This recipe is simply a comma-separated list of C<address:port> pairs (for	94	=item binds - C<ip:port>
101	TCP/IP, other protocols might look different).
102		95
103	Node references come in two flavours: resolved (containing only numerical	96	Nodes can only talk to each other by creating some kind of connection to
104	addresses) or unresolved (where hostnames are used instead of addresses).	97	each other. To do this, nodes should listen on one or more local transport
		98	endpoints - binds. Currently, only standard C<ip:port> specifications can
		99	be used, which specify TCP ports to listen on.
105		100
106	Before using an unresolved node reference in a message you first have to	101	=item seeds - C<host:port>
107	resolve it.	102
		103	When a node starts, it knows nothing about the network. To teach the node
		104	about the network it first has to contact some other node within the
		105	network. This node is called a seed.
		106
		107	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		108	are expected to be long-running, and at least one of those should always
		109	be available. When nodes run out of connections (e.g. due to a network
		110	error), they try to re-establish connections to some seednodes again to
		111	join the network.
		112
		113	Apart from being sued for seeding, seednodes are not special in any way -
		114	every public node can be a seednode.
108		115
109	=back	116	=back
110		117
111	=head1 VARIABLES/FUNCTIONS	118	=head1 VARIABLES/FUNCTIONS
112		119
…		…
127	use base "Exporter";	134	use base "Exporter";
128		135
129	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	136	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
130		137
131	our @EXPORT = qw(	138	our @EXPORT = qw(
132	NODE $NODE *SELF node_of _any_	139	NODE $NODE *SELF node_of after
133	resolve_node initialise_node	140	configure
134	snd rcv mon kil reg psub spawn	141	snd rcv mon mon_guard kil reg psub spawn
135	port	142	port
136	);	143	);
137		144
138	our $SELF;	145	our $SELF;
139		146
…		…
143	kil $SELF, die => $msg;	150	kil $SELF, die => $msg;
144	}	151	}
145		152
146	=item $thisnode = NODE / $NODE	153	=item $thisnode = NODE / $NODE
147		154
148	The C<NODE> function returns, and the C<$NODE> variable contains the	155	The C<NODE> function returns, and the C<$NODE> variable contains, the node
149	noderef of the local node. The value is initialised by a call to	156	ID of the node running in the current process. This value is initialised by
150	C<initialise_node>.	157	a call to C<configure>.
151		158
152	=item $noderef = node_of $port	159	=item $nodeid = node_of $port
153		160
154	Extracts and returns the noderef from a port ID or a noderef.	161	Extracts and returns the node ID from a port ID or a node ID.
155		162
156	=item initialise_node $noderef, $seednode, $seednode...	163	=item configure key => value...
157		164
158	=item initialise_node "slave/", $master, $master...
159
160	Before a node can talk to other nodes on the network it has to initialise	165	Before a node can talk to other nodes on the network (i.e. enter
161	itself - the minimum a node needs to know is it's own name, and optionally	166	"distributed mode") it has to configure itself - the minimum a node needs
162	it should know the noderefs of some other nodes in the network.	167	to know is its own name, and optionally it should know the addresses of
		168	some other nodes in the network to discover other nodes.
163		169
164	This function initialises a node - it must be called exactly once (or	170	This function configures a node - it must be called exactly once (or
165	never) before calling other AnyEvent::MP functions.	171	never) before calling other AnyEvent::MP functions.
166		172
167	All arguments (optionally except for the first) are noderefs, which can be
168	either resolved or unresolved.
169
170	The first argument will be looked up in the configuration database first
171	(if it is C<undef> then the current nodename will be used instead) to find
172	the relevant configuration profile (see L<aemp>). If none is found then
173	the default configuration is used. The configuration supplies additional
174	seed/master nodes and can override the actual noderef.
175
176	There are two types of networked nodes, public nodes and slave nodes:
177
178	=over 4	173	=over 4
179		174
180	=item public nodes	175	=item step 1, gathering configuration from profiles
181		176
182	For public nodes, C<$noderef> (supplied either directly to	177	The function first looks up a profile in the aemp configuration (see the
183	C<initialise_node> or indirectly via a profile or the nodename) must be a	178	L<aemp> commandline utility). The profile name can be specified via the
184	noderef (possibly unresolved, in which case it will be resolved).	179	named C<profile> parameter. If it is missing, then the nodename (F<uname
		180	-n>) will be used as profile name.
185		181
186	After resolving, the node will bind itself on all endpoints and try to	182	The profile data is then gathered as follows:
187	connect to all additional C<$seednodes> that are specified. Seednodes are
188	optional and can be used to quickly bootstrap the node into an existing
189	network.
190		183
191	=item slave nodes	184	First, all remaining key => value pairs (all of which are conveniently
		185	undocumented at the moment) will be interpreted as configuration
		186	data. Then they will be overwritten by any values specified in the global
		187	default configuration (see the F<aemp> utility), then the chain of
		188	profiles chosen by the profile name (and any C<parent> attributes).
192		189
193	When the C<$noderef> (either as given or overriden by the config file)	190	That means that the values specified in the profile have highest priority
194	is the special string C<slave/>, then the node will become a slave	191	and the values specified directly via C<configure> have lowest priority,
195	node. Slave nodes cannot be contacted from outside and will route most of	192	and can only be used to specify defaults.
196	their traffic to the master node that they attach to.
197		193
198	At least one additional noderef is required (either by specifying it	194	If the profile specifies a node ID, then this will become the node ID of
199	directly or because it is part of the configuration profile): The node	195	this process. If not, then the profile name will be used as node ID. The
200	will try to connect to all of them and will become a slave attached to the	196	special node ID of C<anon/> will be replaced by a random node ID.
201	first node it can successfully connect to.	197
		198	=item step 2, bind listener sockets
		199
		200	The next step is to look up the binds in the profile, followed by binding
		201	aemp protocol listeners on all binds specified (it is possible and valid
		202	to have no binds, meaning that the node cannot be contacted form the
		203	outside. This means the node cannot talk to other nodes that also have no
		204	binds, but it can still talk to all "normal" nodes).
		205
		206	If the profile does not specify a binds list, then a default of C<*> is
		207	used, meaning the node will bind on a dynamically-assigned port on every
		208	local IP address it finds.
		209
		210	=item step 3, connect to seed nodes
		211
		212	As the last step, the seeds list from the profile is passed to the
		213	L<AnyEvent::MP::Global> module, which will then use it to keep
		214	connectivity with at least one node at any point in time.
202		215
203	=back	216	=back
204		217
205	This function will block until all nodes have been resolved and, for slave	218	Example: become a distributed node using the locla node name as profile.
206	nodes, until it has successfully established a connection to a master	219	This should be the most common form of invocation for "daemon"-type nodes.
207	server.
208		220
209	Example: become a public node listening on the guessed noderef, or the one	221	configure
210	specified via C<aemp> for the current node. This should be the most common
211	form of invocation for "daemon"-type nodes.
212		222
213	initialise_node;	223	Example: become an anonymous node. This form is often used for commandline
		224	clients.
214		225
215	Example: become a slave node to any of the the seednodes specified via	226	configure nodeid => "anon/";
216	C<aemp>. This form is often used for commandline clients.
217		227
218	initialise_node "slave/";	228	Example: configure a node using a profile called seed, which si suitable
		229	for a seed node as it binds on all local addresses on a fixed port (4040,
		230	customary for aemp).
219		231
220	Example: become a slave node to any of the specified master servers. This	232	# use the aemp commandline utility
221	form is also often used for commandline clients.	233	# aemp profile seed nodeid anon/ binds '*:4040'
222		234
223	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";	235	# then use it
		236	configure profile => "seed";
224		237
225	Example: become a public node, and try to contact some well-known master	238	# or simply use aemp from the shell again:
226	servers to become part of the network.	239	# aemp run profile seed
227		240
228	initialise_node undef, "master1", "master2";	241	# or provide a nicer-to-remember nodeid
229		242	# aemp run profile seed nodeid "$(hostname)"
230	Example: become a public node listening on port C<4041>.
231
232	initialise_node 4041;
233
234	Example: become a public node, only visible on localhost port 4044.
235
236	initialise_node "localhost:4044";
237
238	=item $cv = resolve_node $noderef
239
240	Takes an unresolved node reference that may contain hostnames and
241	abbreviated IDs, resolves all of them and returns a resolved node
242	reference.
243
244	In addition to C<address:port> pairs allowed in resolved noderefs, the
245	following forms are supported:
246
247	=over 4
248
249	=item the empty string
250
251	An empty-string component gets resolved as if the default port (4040) was
252	specified.
253
254	=item naked port numbers (e.g. C<1234>)
255
256	These are resolved by prepending the local nodename and a colon, to be
257	further resolved.
258
259	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
260
261	These are resolved by using AnyEvent::DNS to resolve them, optionally
262	looking up SRV records for the C<aemp=4040> port, if no port was
263	specified.
264
265	=back
266		243
267	=item $SELF	244	=item $SELF
268		245
269	Contains the current port id while executing C<rcv> callbacks or C<psub>	246	Contains the current port id while executing C<rcv> callbacks or C<psub>
270	blocks.	247	blocks.
271		248
272	=item SELF, %SELF, @SELF...	249	=item *SELF, SELF, %SELF, @SELF...
273		250
274	Due to some quirks in how perl exports variables, it is impossible to	251	Due to some quirks in how perl exports variables, it is impossible to
275	just export C<$SELF>, all the symbols called C<SELF> are exported by this	252	just export C<$SELF>, all the symbols named C<SELF> are exported by this
276	module, but only C<$SELF> is currently used.	253	module, but only C<$SELF> is currently used.
277		254
278	=item snd $port, type => @data	255	=item snd $port, type => @data
279		256
280	=item snd $port, @msg	257	=item snd $port, @msg
281		258
282	Send the given message to the given port ID, which can identify either	259	Send the given message to the given port, which can identify either a
283	a local or a remote port, and must be a port ID.	260	local or a remote port, and must be a port ID.
284		261
285	While the message can be about anything, it is highly recommended to use a	262	While the message can be almost anything, it is highly recommended to
286	string as first element (a port ID, or some word that indicates a request	263	use a string as first element (a port ID, or some word that indicates a
287	type etc.).	264	request type etc.) and to consist if only simple perl values (scalars,
		265	arrays, hashes) - if you think you need to pass an object, think again.
288		266
289	The message data effectively becomes read-only after a call to this	267	The message data logically becomes read-only after a call to this
290	function: modifying any argument is not allowed and can cause many	268	function: modifying any argument (or values referenced by them) is
291	problems.	269	forbidden, as there can be considerable time between the call to C<snd>
		270	and the time the message is actually being serialised - in fact, it might
		271	never be copied as within the same process it is simply handed to the
		272	receiving port.
292		273
293	The type of data you can transfer depends on the transport protocol: when	274	The type of data you can transfer depends on the transport protocol: when
294	JSON is used, then only strings, numbers and arrays and hashes consisting	275	JSON is used, then only strings, numbers and arrays and hashes consisting
295	of those are allowed (no objects). When Storable is used, then anything	276	of those are allowed (no objects). When Storable is used, then anything
296	that Storable can serialise and deserialise is allowed, and for the local	277	that Storable can serialise and deserialise is allowed, and for the local
297	node, anything can be passed.	278	node, anything can be passed. Best rely only on the common denominator of
		279	these.
298		280
299	=item $local_port = port	281	=item $local_port = port
300		282
301	Create a new local port object and returns its port ID. Initially it has	283	Create a new local port object and returns its port ID. Initially it has
302	no callbacks set and will throw an error when it receives messages.	284	no callbacks set and will throw an error when it receives messages.
…		…
349	The default callback received all messages not matched by a more specific	331	The default callback received all messages not matched by a more specific
350	C<tag> match.	332	C<tag> match.
351		333
352	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...	334	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
353		335
354	Register callbacks to be called on messages starting with the given tag on	336	Register (or replace) callbacks to be called on messages starting with the
355	the given port (and return the port), or unregister it (when C<$callback>	337	given tag on the given port (and return the port), or unregister it (when
356	is C<$undef>).	338	C<$callback> is C<$undef> or missing). There can only be one callback
		339	registered for each tag.
357		340
358	The original message will be passed to the callback, after the first	341	The original message will be passed to the callback, after the first
359	element (the tag) has been removed. The callback will use the same	342	element (the tag) has been removed. The callback will use the same
360	environment as the default callback (see above).	343	environment as the default callback (see above).
361		344
…		…
373	rcv port,	356	rcv port,
374	msg1 => sub { ... },	357	msg1 => sub { ... },
375	...	358	...
376	;	359	;
377		360
		361	Example: temporarily register a rcv callback for a tag matching some port
		362	(e.g. for a rpc reply) and unregister it after a message was received.
		363
		364	rcv $port, $otherport => sub {
		365	my @reply = @_;
		366
		367	rcv $SELF, $otherport;
		368	};
		369
378	=cut	370	=cut
379		371
380	sub rcv($@) {	372	sub rcv($@) {
381	my $port = shift;	373	my $port = shift;
382	my ($noderef, $portid) = split /#/, $port, 2;	374	my ($nodeid, $portid) = split /#/, $port, 2;
383		375
384	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	376	$NODE{$nodeid} == $NODE{""}
385	or Carp::croak "$port: rcv can only be called on local ports, caught";	377	or Carp::croak "$port: rcv can only be called on local ports, caught";
386		378
387	while (@_) {	379	while (@_) {
388	if (ref $_[0]) {	380	if (ref $_[0]) {
389	if (my $self = $PORT_DATA{$portid}) {	381	if (my $self = $PORT_DATA{$portid}) {
…		…
468	$res	460	$res
469	}	461	}
470	}	462	}
471	}	463	}
472		464
473	=item $guard = mon $port, $cb->(@reason)	465	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
474		466
475	=item $guard = mon $port, $rcvport	467	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
476		468
477	=item $guard = mon $port	469	=item $guard = mon $port # kill $SELF when $port dies
478		470
479	=item $guard = mon $port, $rcvport, @msg	471	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
480		472
481	Monitor the given port and do something when the port is killed or	473	Monitor the given port and do something when the port is killed or
482	messages to it were lost, and optionally return a guard that can be used	474	messages to it were lost, and optionally return a guard that can be used
483	to stop monitoring again.	475	to stop monitoring again.
484		476
485	C<mon> effectively guarantees that, in the absence of hardware failures,	477	C<mon> effectively guarantees that, in the absence of hardware failures,
486	that after starting the monitor, either all messages sent to the port	478	after starting the monitor, either all messages sent to the port will
487	will arrive, or the monitoring action will be invoked after possible	479	arrive, or the monitoring action will be invoked after possible message
488	message loss has been detected. No messages will be lost "in between"	480	loss has been detected. No messages will be lost "in between" (after
489	(after the first lost message no further messages will be received by the	481	the first lost message no further messages will be received by the
490	port). After the monitoring action was invoked, further messages might get	482	port). After the monitoring action was invoked, further messages might get
491	delivered again.	483	delivered again.
		484
		485	Note that monitoring-actions are one-shot: once messages are lost (and a
		486	monitoring alert was raised), they are removed and will not trigger again.
492		487
493	In the first form (callback), the callback is simply called with any	488	In the first form (callback), the callback is simply called with any
494	number of C<@reason> elements (no @reason means that the port was deleted	489	number of C<@reason> elements (no @reason means that the port was deleted
495	"normally"). Note also that I<< the callback B<must> never die >>, so use	490	"normally"). Note also that I<< the callback B<must> never die >>, so use
496	C<eval> if unsure.	491	C<eval> if unsure.
497		492
498	In the second form (another port given), the other port (C<$rcvport>)	493	In the second form (another port given), the other port (C<$rcvport>)
499	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	494	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
500	"normal" kils nothing happens, while under all other conditions, the other	495	"normal" kils nothing happens, while under all other conditions, the other
501	port is killed with the same reason.	496	port is killed with the same reason.
502		497
503	The third form (kill self) is the same as the second form, except that	498	The third form (kill self) is the same as the second form, except that
504	C<$rvport> defaults to C<$SELF>.	499	C<$rvport> defaults to C<$SELF>.
…		…
507	C<snd>.	502	C<snd>.
508		503
509	As a rule of thumb, monitoring requests should always monitor a port from	504	As a rule of thumb, monitoring requests should always monitor a port from
510	a local port (or callback). The reason is that kill messages might get	505	a local port (or callback). The reason is that kill messages might get
511	lost, just like any other message. Another less obvious reason is that	506	lost, just like any other message. Another less obvious reason is that
512	even monitoring requests can get lost (for exmaple, when the connection	507	even monitoring requests can get lost (for example, when the connection
513	to the other node goes down permanently). When monitoring a port locally	508	to the other node goes down permanently). When monitoring a port locally
514	these problems do not exist.	509	these problems do not exist.
515		510
516	Example: call a given callback when C<$port> is killed.	511	Example: call a given callback when C<$port> is killed.
517		512
…		…
526	mon $port, $self => "restart";	521	mon $port, $self => "restart";
527		522
528	=cut	523	=cut
529		524
530	sub mon {	525	sub mon {
531	my ($noderef, $port) = split /#/, shift, 2;	526	my ($nodeid, $port) = split /#/, shift, 2;
532		527
533	my $node = $NODE{$noderef} \|\| add_node $noderef;	528	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
534		529
535	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	530	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
536		531
537	unless (ref $cb) {	532	unless (ref $cb) {
538	if (@_) {	533	if (@_) {
…		…
558	is killed, the references will be freed.	553	is killed, the references will be freed.
559		554
560	Optionally returns a guard that will stop the monitoring.	555	Optionally returns a guard that will stop the monitoring.
561		556
562	This function is useful when you create e.g. timers or other watchers and	557	This function is useful when you create e.g. timers or other watchers and
563	want to free them when the port gets killed:	558	want to free them when the port gets killed (note the use of C<psub>):
564		559
565	$port->rcv (start => sub {	560	$port->rcv (start => sub {
566	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	561	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
567	undef $timer if 0.9 < rand;	562	undef $timer if 0.9 < rand;
568	});	563	});
569	});	564	});
570		565
571	=cut	566	=cut
…		…
580		575
581	=item kil $port[, @reason]	576	=item kil $port[, @reason]
582		577
583	Kill the specified port with the given C<@reason>.	578	Kill the specified port with the given C<@reason>.
584		579
585	If no C<@reason> is specified, then the port is killed "normally" (linked	580	If no C<@reason> is specified, then the port is killed "normally" (ports
586	ports will not be kileld, or even notified).	581	monitoring other ports will not necessarily die because a port dies
		582	"normally").
587		583
588	Otherwise, linked ports get killed with the same reason (second form of	584	Otherwise, linked ports get killed with the same reason (second form of
589	C<mon>, see below).	585	C<mon>, see above).
590		586
591	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	587	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
592	will be reported as reason C<< die => $@ >>.	588	will be reported as reason C<< die => $@ >>.
593		589
594	Transport/communication errors are reported as C<< transport_error =>	590	Transport/communication errors are reported as C<< transport_error =>
…		…
599	=item $port = spawn $node, $initfunc[, @initdata]	595	=item $port = spawn $node, $initfunc[, @initdata]
600		596
601	Creates a port on the node C<$node> (which can also be a port ID, in which	597	Creates a port on the node C<$node> (which can also be a port ID, in which
602	case it's the node where that port resides).	598	case it's the node where that port resides).
603		599
604	The port ID of the newly created port is return immediately, and it is	600	The port ID of the newly created port is returned immediately, and it is
605	permissible to immediately start sending messages or monitor the port.	601	possible to immediately start sending messages or to monitor the port.
606		602
607	After the port has been created, the init function is	603	After the port has been created, the init function is called on the remote
608	called. This function must be a fully-qualified function name	604	node, in the same context as a C<rcv> callback. This function must be a
609	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main	605	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
610	program, use C<::name>.	606	specify a function in the main program, use C<::name>.
611		607
612	If the function doesn't exist, then the node tries to C<require>	608	If the function doesn't exist, then the node tries to C<require>
613	the package, then the package above the package and so on (e.g.	609	the package, then the package above the package and so on (e.g.
614	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	610	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
615	exists or it runs out of package names.	611	exists or it runs out of package names.
616		612
617	The init function is then called with the newly-created port as context	613	The init function is then called with the newly-created port as context
618	object (C<$SELF>) and the C<@initdata> values as arguments.	614	object (C<$SELF>) and the C<@initdata> values as arguments.
619		615
620	A common idiom is to pass your own port, monitor the spawned port, and	616	A common idiom is to pass a local port, immediately monitor the spawned
621	in the init function, monitor the original port. This two-way monitoring	617	port, and in the remote init function, immediately monitor the passed
622	ensures that both ports get cleaned up when there is a problem.	618	local port. This two-way monitoring ensures that both ports get cleaned up
		619	when there is a problem.
623		620
624	Example: spawn a chat server port on C<$othernode>.	621	Example: spawn a chat server port on C<$othernode>.
625		622
626	# this node, executed from within a port context:	623	# this node, executed from within a port context:
627	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	624	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
…		…
650	};	647	};
651	_self_die if $@;	648	_self_die if $@;
652	}	649	}
653		650
654	sub spawn(@) {	651	sub spawn(@) {
655	my ($noderef, undef) = split /#/, shift, 2;	652	my ($nodeid, undef) = split /#/, shift, 2;
656		653
657	my $id = "$RUNIQ." . $ID++;	654	my $id = "$RUNIQ." . $ID++;
658		655
659	$_[0] =~ /::/	656	$_[0] =~ /::/
660	or Carp::croak "spawn init function must be a fully-qualified name, caught";	657	or Carp::croak "spawn init function must be a fully-qualified name, caught";
661		658
662	($NODE{$noderef} \|\| add_node $noderef)	659	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
663	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
664		660
665	"$noderef#$id"	661	"$nodeid#$id"
666	}	662	}
667		663
668	=back	664	=item after $timeout, @msg
669		665
670	=head1 NODE MESSAGES	666	=item after $timeout, $callback
671		667
672	Nodes understand the following messages sent to them. Many of them take	668	Either sends the given message, or call the given callback, after the
673	arguments called C<@reply>, which will simply be used to compose a reply	669	specified number of seconds.
674	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
675	the remaining arguments are simply the message data.
676		670
677	While other messages exist, they are not public and subject to change.	671	This is simply a utility function that comes in handy at times - the
		672	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		673	so it may go away in the future.
678		674
679	=over 4
680
681	=cut	675	=cut
682		676
683	=item lookup => $name, @reply	677	sub after($@) {
		678	my ($timeout, @action) = @_;
684		679
685	Replies with the port ID of the specified well-known port, or C<undef>.	680	my $t; $t = AE::timer $timeout, 0, sub {
686		681	undef $t;
687	=item devnull => ...	682	ref $action[0]
688		683	? $action[0]()
689	Generic data sink/CPU heat conversion.	684	: snd @action;
690		685	};
691	=item relay => $port, @msg	686	}
692
693	Simply forwards the message to the given port.
694
695	=item eval => $string[ @reply]
696
697	Evaluates the given string. If C<@reply> is given, then a message of the
698	form C<@reply, $@, @evalres> is sent.
699
700	Example: crash another node.
701
702	snd $othernode, eval => "exit";
703
704	=item time => @reply
705
706	Replies the the current node time to C<@reply>.
707
708	Example: tell the current node to send the current time to C<$myport> in a
709	C<timereply> message.
710
711	snd $NODE, time => $myport, timereply => 1, 2;
712	# => snd $myport, timereply => 1, 2, <time>
713		687
714	=back	688	=back
715		689
716	=head1 AnyEvent::MP vs. Distributed Erlang	690	=head1 AnyEvent::MP vs. Distributed Erlang
717		691
…		…
727		701
728	Despite the similarities, there are also some important differences:	702	Despite the similarities, there are also some important differences:
729		703
730	=over 4	704	=over 4
731		705
732	=item * Node references contain the recipe on how to contact them.	706	=item * Node IDs are arbitrary strings in AEMP.
733		707
734	Erlang relies on special naming and DNS to work everywhere in the	708	Erlang relies on special naming and DNS to work everywhere in the same
735	same way. AEMP relies on each node knowing it's own address(es), with	709	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
736	convenience functionality.	710	configuration or DNS), but will otherwise discover other odes itself.
737		711
738	This means that AEMP requires a less tightly controlled environment at the
739	cost of longer node references and a slightly higher management overhead.
740
741	=item Erlang has a "remote ports are like local ports" philosophy, AEMP	712	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
742	uses "local ports are like remote ports".	713	uses "local ports are like remote ports".
743		714
744	The failure modes for local ports are quite different (runtime errors	715	The failure modes for local ports are quite different (runtime errors
745	only) then for remote ports - when a local port dies, you I<know> it dies,	716	only) then for remote ports - when a local port dies, you I<know> it dies,
746	when a connection to another node dies, you know nothing about the other	717	when a connection to another node dies, you know nothing about the other
…		…
757		728
758	Erlang uses processes that selectively receive messages, and therefore	729	Erlang uses processes that selectively receive messages, and therefore
759	needs a queue. AEMP is event based, queuing messages would serve no	730	needs a queue. AEMP is event based, queuing messages would serve no
760	useful purpose. For the same reason the pattern-matching abilities of	731	useful purpose. For the same reason the pattern-matching abilities of
761	AnyEvent::MP are more limited, as there is little need to be able to	732	AnyEvent::MP are more limited, as there is little need to be able to
762	filter messages without dequeing them.	733	filter messages without dequeuing them.
763		734
764	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	735	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
765		736
766	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	737	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
767		738
…		…
773		744
774	Erlang makes few guarantees on messages delivery - messages can get lost	745	Erlang makes few guarantees on messages delivery - messages can get lost
775	without any of the processes realising it (i.e. you send messages a, b,	746	without any of the processes realising it (i.e. you send messages a, b,
776	and c, and the other side only receives messages a and c).	747	and c, and the other side only receives messages a and c).
777		748
778	AEMP guarantees correct ordering, and the guarantee that there are no	749	AEMP guarantees correct ordering, and the guarantee that after one message
779	holes in the message sequence.	750	is lost, all following ones sent to the same port are lost as well, until
780		751	monitoring raises an error, so there are no silent "holes" in the message
781	=item * In Erlang, processes can be declared dead and later be found to be	752	sequence.
782	alive.
783
784	In Erlang it can happen that a monitored process is declared dead and
785	linked processes get killed, but later it turns out that the process is
786	still alive - and can receive messages.
787
788	In AEMP, when port monitoring detects a port as dead, then that port will
789	eventually be killed - it cannot happen that a node detects a port as dead
790	and then later sends messages to it, finding it is still alive.
791		753
792	=item * Erlang can send messages to the wrong port, AEMP does not.	754	=item * Erlang can send messages to the wrong port, AEMP does not.
793		755
794	In Erlang it is quite likely that a node that restarts reuses a process ID	756	In Erlang it is quite likely that a node that restarts reuses a process ID
795	known to other nodes for a completely different process, causing messages	757	known to other nodes for a completely different process, causing messages
…		…
799	around in the network will not be sent to an unrelated port.	761	around in the network will not be sent to an unrelated port.
800		762
801	=item * Erlang uses unprotected connections, AEMP uses secure	763	=item * Erlang uses unprotected connections, AEMP uses secure
802	authentication and can use TLS.	764	authentication and can use TLS.
803		765
804	AEMP can use a proven protocol - SSL/TLS - to protect connections and	766	AEMP can use a proven protocol - TLS - to protect connections and
805	securely authenticate nodes.	767	securely authenticate nodes.
806		768
807	=item * The AEMP protocol is optimised for both text-based and binary	769	=item * The AEMP protocol is optimised for both text-based and binary
808	communications.	770	communications.
809		771
810	The AEMP protocol, unlike the Erlang protocol, supports both	772	The AEMP protocol, unlike the Erlang protocol, supports both programming
811	language-independent text-only protocols (good for debugging) and binary,	773	language independent text-only protocols (good for debugging) and binary,
812	language-specific serialisers (e.g. Storable).	774	language-specific serialisers (e.g. Storable). By default, unless TLS is
		775	used, the protocol is actually completely text-based.
813		776
814	It has also been carefully designed to be implementable in other languages	777	It has also been carefully designed to be implementable in other languages
815	with a minimum of work while gracefully degrading fucntionality to make the	778	with a minimum of work while gracefully degrading functionality to make the
816	protocol simple.	779	protocol simple.
817		780
818	=item * AEMP has more flexible monitoring options than Erlang.	781	=item * AEMP has more flexible monitoring options than Erlang.
819		782
820	In Erlang, you can chose to receive I<all> exit signals as messages	783	In Erlang, you can chose to receive I<all> exit signals as messages
…		…
823	Erlang, as one can choose between automatic kill, exit message or callback	786	Erlang, as one can choose between automatic kill, exit message or callback
824	on a per-process basis.	787	on a per-process basis.
825		788
826	=item * Erlang tries to hide remote/local connections, AEMP does not.	789	=item * Erlang tries to hide remote/local connections, AEMP does not.
827		790
828	Monitoring in Erlang is not an indicator of process death/crashes,	791	Monitoring in Erlang is not an indicator of process death/crashes, in the
829	as linking is (except linking is unreliable in Erlang).	792	same way as linking is (except linking is unreliable in Erlang).
830		793
831	In AEMP, you don't "look up" registered port names or send to named ports	794	In AEMP, you don't "look up" registered port names or send to named ports
832	that might or might not be persistent. Instead, you normally spawn a port	795	that might or might not be persistent. Instead, you normally spawn a port
833	on the remote node. The init function monitors the you, and you monitor	796	on the remote node. The init function monitors you, and you monitor the
834	the remote port. Since both monitors are local to the node, they are much	797	remote port. Since both monitors are local to the node, they are much more
835	more reliable.	798	reliable (no need for C<spawn_link>).
836		799
837	This also saves round-trips and avoids sending messages to the wrong port	800	This also saves round-trips and avoids sending messages to the wrong port
838	(hard to do in Erlang).	801	(hard to do in Erlang).
839		802
840	=back	803	=back
841		804
842	=head1 RATIONALE	805	=head1 RATIONALE
843		806
844	=over 4	807	=over 4
845		808
846	=item Why strings for ports and noderefs, why not objects?	809	=item Why strings for port and node IDs, why not objects?
847		810
848	We considered "objects", but found that the actual number of methods	811	We considered "objects", but found that the actual number of methods
849	thatc an be called are very low. Since port IDs and noderefs travel over	812	that can be called are quite low. Since port and node IDs travel over
850	the network frequently, the serialising/deserialising would add lots of	813	the network frequently, the serialising/deserialising would add lots of
851	overhead, as well as having to keep a proxy object.	814	overhead, as well as having to keep a proxy object everywhere.
852		815
853	Strings can easily be printed, easily serialised etc. and need no special	816	Strings can easily be printed, easily serialised etc. and need no special
854	procedures to be "valid".	817	procedures to be "valid".
855		818
856	And a a miniport consists of a single closure stored in a global hash - it	819	And as a result, a miniport consists of a single closure stored in a
857	can't become much cheaper.	820	global hash - it can't become much cheaper.
858		821
859	=item Why favour JSON, why not real serialising format such as Storable?	822	=item Why favour JSON, why not a real serialising format such as Storable?
860		823
861	In fact, any AnyEvent::MP node will happily accept Storable as framing	824	In fact, any AnyEvent::MP node will happily accept Storable as framing
862	format, but currently there is no way to make a node use Storable by	825	format, but currently there is no way to make a node use Storable by
863	default.	826	default (although all nodes will accept it).
864		827
865	The default framing protocol is JSON because a) JSON::XS is many times	828	The default framing protocol is JSON because a) JSON::XS is many times
866	faster for small messages and b) most importantly, after years of	829	faster for small messages and b) most importantly, after years of
867	experience we found that object serialisation is causing more problems	830	experience we found that object serialisation is causing more problems
868	than it gains: Just like function calls, objects simply do not travel	831	than it solves: Just like function calls, objects simply do not travel
869	easily over the network, mostly because they will always be a copy, so you	832	easily over the network, mostly because they will always be a copy, so you
870	always have to re-think your design.	833	always have to re-think your design.
871		834
872	Keeping your messages simple, concentrating on data structures rather than	835	Keeping your messages simple, concentrating on data structures rather than
873	objects, will keep your messages clean, tidy and efficient.	836	objects, will keep your messages clean, tidy and efficient.
874		837
875	=back	838	=back
876		839
877	=head1 SEE ALSO	840	=head1 SEE ALSO
878		841
		842	L<AnyEvent::MP::Intro> - a gentle introduction.
		843
		844	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		845
		846	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		847	your applications.
		848
879	L<AnyEvent>.	849	L<AnyEvent>.
880		850
881	=head1 AUTHOR	851	=head1 AUTHOR
882		852
883	Marc Lehmann <schmorp@schmorp.de>	853	Marc Lehmann <schmorp@schmorp.de>

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Revision 1.52 by root, Fri Aug 14 15:13:20 2009 UTC vs.
Revision 1.77 by elmex, Thu Sep 3 07:57:30 2009 UTC