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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.53 by root, Fri Aug 14 15:31:21 2009 UTC vs.
Revision 1.66 by root, Fri Aug 28 01:07:24 2009 UTC

…		…
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	13	$SELF # receiving/own port id in rcv callbacks
14		14
15	# initialise the node so it can send/receive messages	15	# initialise the node so it can send/receive messages
16	initialise_node; # -OR-	16	initialise_node;
17	initialise_node "localhost:4040"; # -OR-
18	initialise_node "slave/", "localhost:4040"
19		17
20	# ports are message endpoints	18	# ports are message endpoints
21		19
22	# sending messages	20	# sending messages
23	snd $port, type => data...;	21	snd $port, type => data...;
…		…
70	=item port	68	=item port
71		69
72	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).
73		71
74	Ports allow you to register C<rcv> handlers that can match all or just	72	Ports allow you to register C<rcv> handlers that can match all or just
75	some messages. Messages will not be queued.	73	some messages. Messages send to ports will not be queued, regardless of
		74	anything was listening for them or not.
76		75
77	=item port id - C<noderef#portname>	76	=item port ID - C<noderef#portname>
78		77
79	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as	78	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as
80	separator, and a port name (a printable string of unspecified format). An	79	separator, and a port name (a printable string of unspecified format). An
81	exception is the the node port, whose ID is identical to its node	80	exception is the the node port, whose ID is identical to its node
82	reference.	81	reference.
…		…
85		84
86	A node is a single process containing at least one port - the node port,	85	A node is a single process containing at least one port - the node port,
87	which provides nodes to manage each other remotely, and to create new	86	which provides nodes to manage each other remotely, and to create new
88	ports.	87	ports.
89		88
90	Nodes are either private (single-process only), slaves (connected to a	89	Nodes are either private (single-process only), slaves (can only talk to
91	master node only) or public nodes (connectable from unrelated nodes).	90	public nodes, but do not need an open port) or public nodes (connectable
		91	from any other node).
92		92
93	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	93	=item node ID - C<[a-za-Z0-9_\-.:]+>
94		94
95	A node reference is a string that either simply identifies the node (for	95	A node ID is a string that uniquely identifies the node within a
96	private and slave nodes), or contains a recipe on how to reach a given	96	network. Depending on the configuration used, node IDs can look like a
97	node (for public nodes).	97	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		98	doesn't interpret node IDs in any way.
98		99
99	This recipe is simply a comma-separated list of C<address:port> pairs (for	100	=item binds - C<ip:port>
100	TCP/IP, other protocols might look different).
101		101
102	Node references come in two flavours: resolved (containing only numerical	102	Nodes can only talk to each other by creating some kind of connection to
103	addresses) or unresolved (where hostnames are used instead of addresses).	103	each other. To do this, nodes should listen on one or more local transport
		104	endpoints - binds. Currently, only standard C<ip:port> specifications can
		105	be used, which specify TCP ports to listen on.
104		106
105	Before using an unresolved node reference in a message you first have to	107	=item seeds - C<host:port>
106	resolve it.	108
		109	When a node starts, it knows nothing about the network. To teach the node
		110	about the network it first has to contact some other node within the
		111	network. This node is called a seed.
		112
		113	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		114	are expected to be long-running, and at least one of those should always
		115	be available. When nodes run out of connections (e.g. due to a network
		116	error), they try to re-establish connections to some seednodes again to
		117	join the network.
107		118
108	=back	119	=back
109		120
110	=head1 VARIABLES/FUNCTIONS	121	=head1 VARIABLES/FUNCTIONS
111		122
…		…
126	use base "Exporter";	137	use base "Exporter";
127		138
128	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	139	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
129		140
130	our @EXPORT = qw(	141	our @EXPORT = qw(
131	NODE $NODE *SELF node_of _any_	142	NODE $NODE *SELF node_of after
132	resolve_node initialise_node	143	resolve_node initialise_node
133	snd rcv mon kil reg psub spawn	144	snd rcv mon mon_guard kil reg psub spawn
134	port	145	port
135	);	146	);
136		147
137	our $SELF;	148	our $SELF;
138		149
…		…
142	kil $SELF, die => $msg;	153	kil $SELF, die => $msg;
143	}	154	}
144		155
145	=item $thisnode = NODE / $NODE	156	=item $thisnode = NODE / $NODE
146		157
147	The C<NODE> function returns, and the C<$NODE> variable contains the	158	The C<NODE> function returns, and the C<$NODE> variable contains the node
148	noderef of the local node. The value is initialised by a call to	159	ID of the node running in the current process. This value is initialised by
149	C<initialise_node>.	160	a call to C<initialise_node>.
150		161
151	=item $noderef = node_of $port	162	=item $nodeid = node_of $port
152		163
153	Extracts and returns the noderef from a port ID or a noderef.	164	Extracts and returns the node ID part from a port ID or a node ID.
154		165
155	=item initialise_node $noderef, $seednode, $seednode...	166	=item initialise_node $profile_name
156		167
157	=item initialise_node "slave/", $master, $master...
158
159	Before a node can talk to other nodes on the network it has to initialise	168	Before a node can talk to other nodes on the network (i.e. enter
160	itself - the minimum a node needs to know is it's own name, and optionally	169	"distributed mode") it has to initialise itself - the minimum a node needs
161	it should know the noderefs of some other nodes in the network.	170	to know is its own name, and optionally it should know the addresses of
		171	some other nodes in the network to discover other nodes.
162		172
163	This function initialises a node - it must be called exactly once (or	173	This function initialises a node - it must be called exactly once (or
164	never) before calling other AnyEvent::MP functions.	174	never) before calling other AnyEvent::MP functions.
165		175
166	All arguments (optionally except for the first) are noderefs, which can be	176	The first argument is a profile name. If it is C<undef> or missing, then
167	either resolved or unresolved.	177	the current nodename will be used instead (i.e. F<uname -n>).
168		178
169	The first argument will be looked up in the configuration database first	179	The function then looks up the profile in the aemp configuration (see the
170	(if it is C<undef> then the current nodename will be used instead) to find	180	L<aemp> commandline utility).
171	the relevant configuration profile (see L<aemp>). If none is found then
172	the default configuration is used. The configuration supplies additional
173	seed/master nodes and can override the actual noderef.
174		181
175	There are two types of networked nodes, public nodes and slave nodes:	182	If the profile specifies a node ID, then this will become the node ID of
		183	this process. If not, then the profile name will be used as node ID. The
		184	special node ID of C<anon/> will be replaced by a random node ID.
176		185
177	=over 4	186	The next step is to look up the binds in the profile, followed by binding
		187	aemp protocol listeners on all binds specified (it is possible and valid
		188	to have no binds, meaning that the node cannot be contacted form the
		189	outside. This means the node cannot talk to other nodes that also have no
		190	binds, but it can still talk to all "normal" nodes).
178		191
179	=item public nodes	192	If the profile does not specify a binds list, then the node ID will be
		193	treated as if it were of the form C<host:port>, which will be resolved and
		194	used as binds list.
180		195
181	For public nodes, C<$noderef> (supplied either directly to	196	Lastly, the seeds list from the profile is passed to the
182	C<initialise_node> or indirectly via a profile or the nodename) must be a	197	L<AnyEvent::MP::Global> module, which will then use it to keep
183	noderef (possibly unresolved, in which case it will be resolved).	198	connectivity with at least on of those seed nodes at any point in time.
184		199
185	After resolving, the node will bind itself on all endpoints and try to
186	connect to all additional C<$seednodes> that are specified. Seednodes are
187	optional and can be used to quickly bootstrap the node into an existing
188	network.
189
190	=item slave nodes
191
192	When the C<$noderef> (either as given or overriden by the config file)
193	is the special string C<slave/>, then the node will become a slave
194	node. Slave nodes cannot be contacted from outside and will route most of
195	their traffic to the master node that they attach to.
196
197	At least one additional noderef is required (either by specifying it
198	directly or because it is part of the configuration profile): The node
199	will try to connect to all of them and will become a slave attached to the
200	first node it can successfully connect to.
201
202	=back
203
204	This function will block until all nodes have been resolved and, for slave
205	nodes, until it has successfully established a connection to a master
206	server.
207
208	Example: become a public node listening on the guessed noderef, or the one	200	Example: become a distributed node listening on the guessed noderef, or
209	specified via C<aemp> for the current node. This should be the most common	201	the one specified via C<aemp> for the current node. This should be the
210	form of invocation for "daemon"-type nodes.	202	most common form of invocation for "daemon"-type nodes.
211		203
212	initialise_node;	204	initialise_node;
213		205
214	Example: become a slave node to any of the the seednodes specified via	206	Example: become an anonymous node. This form is often used for commandline
215	C<aemp>. This form is often used for commandline clients.	207	clients.
216		208
217	initialise_node "slave/";	209	initialise_node "anon/";
218		210
219	Example: become a slave node to any of the specified master servers. This	211	Example: become a distributed node. If there is no profile of the given
220	form is also often used for commandline clients.	212	name, or no binds list was specified, resolve C<localhost:4044> and bind
221		213	on the resulting addresses.
222	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
223
224	Example: become a public node, and try to contact some well-known master
225	servers to become part of the network.
226
227	initialise_node undef, "master1", "master2";
228
229	Example: become a public node listening on port C<4041>.
230
231	initialise_node 4041;
232
233	Example: become a public node, only visible on localhost port 4044.
234		214
235	initialise_node "localhost:4044";	215	initialise_node "localhost:4044";
236
237	=item $cv = resolve_node $noderef
238
239	Takes an unresolved node reference that may contain hostnames and
240	abbreviated IDs, resolves all of them and returns a resolved node
241	reference.
242
243	In addition to C<address:port> pairs allowed in resolved noderefs, the
244	following forms are supported:
245
246	=over 4
247
248	=item the empty string
249
250	An empty-string component gets resolved as if the default port (4040) was
251	specified.
252
253	=item naked port numbers (e.g. C<1234>)
254
255	These are resolved by prepending the local nodename and a colon, to be
256	further resolved.
257
258	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
259
260	These are resolved by using AnyEvent::DNS to resolve them, optionally
261	looking up SRV records for the C<aemp=4040> port, if no port was
262	specified.
263
264	=back
265		216
266	=item $SELF	217	=item $SELF
267		218
268	Contains the current port id while executing C<rcv> callbacks or C<psub>	219	Contains the current port id while executing C<rcv> callbacks or C<psub>
269	blocks.	220	blocks.
…		…
348	The default callback received all messages not matched by a more specific	299	The default callback received all messages not matched by a more specific
349	C<tag> match.	300	C<tag> match.
350		301
351	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...	302	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
352		303
353	Register callbacks to be called on messages starting with the given tag on	304	Register (or replace) callbacks to be called on messages starting with the
354	the given port (and return the port), or unregister it (when C<$callback>	305	given tag on the given port (and return the port), or unregister it (when
355	is C<$undef>).	306	C<$callback> is C<$undef> or missing). There can only be one callback
		307	registered for each tag.
356		308
357	The original message will be passed to the callback, after the first	309	The original message will be passed to the callback, after the first
358	element (the tag) has been removed. The callback will use the same	310	element (the tag) has been removed. The callback will use the same
359	environment as the default callback (see above).	311	environment as the default callback (see above).
360		312
…		…
372	rcv port,	324	rcv port,
373	msg1 => sub { ... },	325	msg1 => sub { ... },
374	...	326	...
375	;	327	;
376		328
		329	Example: temporarily register a rcv callback for a tag matching some port
		330	(e.g. for a rpc reply) and unregister it after a message was received.
		331
		332	rcv $port, $otherport => sub {
		333	my @reply = @_;
		334
		335	rcv $SELF, $otherport;
		336	};
		337
377	=cut	338	=cut
378		339
379	sub rcv($@) {	340	sub rcv($@) {
380	my $port = shift;	341	my $port = shift;
381	my ($noderef, $portid) = split /#/, $port, 2;	342	my ($noderef, $portid) = split /#/, $port, 2;
382		343
383	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	344	$NODE{$noderef} == $NODE{""}
384	or Carp::croak "$port: rcv can only be called on local ports, caught";	345	or Carp::croak "$port: rcv can only be called on local ports, caught";
385		346
386	while (@_) {	347	while (@_) {
387	if (ref $_[0]) {	348	if (ref $_[0]) {
388	if (my $self = $PORT_DATA{$portid}) {	349	if (my $self = $PORT_DATA{$portid}) {
…		…
487	message loss has been detected. No messages will be lost "in between"	448	message loss has been detected. No messages will be lost "in between"
488	(after the first lost message no further messages will be received by the	449	(after the first lost message no further messages will be received by the
489	port). After the monitoring action was invoked, further messages might get	450	port). After the monitoring action was invoked, further messages might get
490	delivered again.	451	delivered again.
491		452
		453	Note that monitoring-actions are one-shot: once released, they are removed
		454	and will not trigger again.
		455
492	In the first form (callback), the callback is simply called with any	456	In the first form (callback), the callback is simply called with any
493	number of C<@reason> elements (no @reason means that the port was deleted	457	number of C<@reason> elements (no @reason means that the port was deleted
494	"normally"). Note also that I<< the callback B<must> never die >>, so use	458	"normally"). Note also that I<< the callback B<must> never die >>, so use
495	C<eval> if unsure.	459	C<eval> if unsure.
496		460
…		…
656	my $id = "$RUNIQ." . $ID++;	620	my $id = "$RUNIQ." . $ID++;
657		621
658	$_[0] =~ /::/	622	$_[0] =~ /::/
659	or Carp::croak "spawn init function must be a fully-qualified name, caught";	623	or Carp::croak "spawn init function must be a fully-qualified name, caught";
660		624
661	($NODE{$noderef} \|\| add_node $noderef)	625	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
662	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
663		626
664	"$noderef#$id"	627	"$noderef#$id"
665	}	628	}
666		629
667	=back	630	=item after $timeout, @msg
668		631
669	=head1 NODE MESSAGES	632	=item after $timeout, $callback
670		633
671	Nodes understand the following messages sent to them. Many of them take	634	Either sends the given message, or call the given callback, after the
672	arguments called C<@reply>, which will simply be used to compose a reply	635	specified number of seconds.
673	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
674	the remaining arguments are simply the message data.
675		636
676	While other messages exist, they are not public and subject to change.	637	This is simply a utility function that come sin handy at times.
677		638
678	=over 4
679
680	=cut	639	=cut
681		640
682	=item lookup => $name, @reply	641	sub after($@) {
		642	my ($timeout, @action) = @_;
683		643
684	Replies with the port ID of the specified well-known port, or C<undef>.	644	my $t; $t = AE::timer $timeout, 0, sub {
685		645	undef $t;
686	=item devnull => ...	646	ref $action[0]
687		647	? $action[0]()
688	Generic data sink/CPU heat conversion.	648	: snd @action;
689		649	};
690	=item relay => $port, @msg	650	}
691
692	Simply forwards the message to the given port.
693
694	=item eval => $string[ @reply]
695
696	Evaluates the given string. If C<@reply> is given, then a message of the
697	form C<@reply, $@, @evalres> is sent.
698
699	Example: crash another node.
700
701	snd $othernode, eval => "exit";
702
703	=item time => @reply
704
705	Replies the the current node time to C<@reply>.
706
707	Example: tell the current node to send the current time to C<$myport> in a
708	C<timereply> message.
709
710	snd $NODE, time => $myport, timereply => 1, 2;
711	# => snd $myport, timereply => 1, 2, <time>
712		651
713	=back	652	=back
714		653
715	=head1 AnyEvent::MP vs. Distributed Erlang	654	=head1 AnyEvent::MP vs. Distributed Erlang
716		655
…		…
726		665
727	Despite the similarities, there are also some important differences:	666	Despite the similarities, there are also some important differences:
728		667
729	=over 4	668	=over 4
730		669
731	=item * Node references contain the recipe on how to contact them.	670	=item * Node IDs are arbitrary strings in AEMP.
732		671
733	Erlang relies on special naming and DNS to work everywhere in the	672	Erlang relies on special naming and DNS to work everywhere in the same
734	same way. AEMP relies on each node knowing it's own address(es), with	673	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
735	convenience functionality.	674	configuraiton or DNS), but will otherwise discover other odes itself.
736		675
737	This means that AEMP requires a less tightly controlled environment at the
738	cost of longer node references and a slightly higher management overhead.
739
740	=item Erlang has a "remote ports are like local ports" philosophy, AEMP	676	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
741	uses "local ports are like remote ports".	677	uses "local ports are like remote ports".
742		678
743	The failure modes for local ports are quite different (runtime errors	679	The failure modes for local ports are quite different (runtime errors
744	only) then for remote ports - when a local port dies, you I<know> it dies,	680	only) then for remote ports - when a local port dies, you I<know> it dies,
745	when a connection to another node dies, you know nothing about the other	681	when a connection to another node dies, you know nothing about the other
…		…
772		708
773	Erlang makes few guarantees on messages delivery - messages can get lost	709	Erlang makes few guarantees on messages delivery - messages can get lost
774	without any of the processes realising it (i.e. you send messages a, b,	710	without any of the processes realising it (i.e. you send messages a, b,
775	and c, and the other side only receives messages a and c).	711	and c, and the other side only receives messages a and c).
776		712
777	AEMP guarantees correct ordering, and the guarantee that there are no	713	AEMP guarantees correct ordering, and the guarantee that after one message
778	holes in the message sequence.	714	is lost, all following ones sent to the same port are lost as well, until
779		715	monitoring raises an error, so there are no silent "holes" in the message
780	=item * In Erlang, processes can be declared dead and later be found to be	716	sequence.
781	alive.
782
783	In Erlang it can happen that a monitored process is declared dead and
784	linked processes get killed, but later it turns out that the process is
785	still alive - and can receive messages.
786
787	In AEMP, when port monitoring detects a port as dead, then that port will
788	eventually be killed - it cannot happen that a node detects a port as dead
789	and then later sends messages to it, finding it is still alive.
790		717
791	=item * Erlang can send messages to the wrong port, AEMP does not.	718	=item * Erlang can send messages to the wrong port, AEMP does not.
792		719
793	In Erlang it is quite likely that a node that restarts reuses a process ID	720	In Erlang it is quite likely that a node that restarts reuses a process ID
794	known to other nodes for a completely different process, causing messages	721	known to other nodes for a completely different process, causing messages
…		…
798	around in the network will not be sent to an unrelated port.	725	around in the network will not be sent to an unrelated port.
799		726
800	=item * Erlang uses unprotected connections, AEMP uses secure	727	=item * Erlang uses unprotected connections, AEMP uses secure
801	authentication and can use TLS.	728	authentication and can use TLS.
802		729
803	AEMP can use a proven protocol - SSL/TLS - to protect connections and	730	AEMP can use a proven protocol - TLS - to protect connections and
804	securely authenticate nodes.	731	securely authenticate nodes.
805		732
806	=item * The AEMP protocol is optimised for both text-based and binary	733	=item * The AEMP protocol is optimised for both text-based and binary
807	communications.	734	communications.
808		735
809	The AEMP protocol, unlike the Erlang protocol, supports both	736	The AEMP protocol, unlike the Erlang protocol, supports both programming
810	language-independent text-only protocols (good for debugging) and binary,	737	language independent text-only protocols (good for debugging) and binary,
811	language-specific serialisers (e.g. Storable).	738	language-specific serialisers (e.g. Storable).
812		739
813	It has also been carefully designed to be implementable in other languages	740	It has also been carefully designed to be implementable in other languages
814	with a minimum of work while gracefully degrading fucntionality to make the	741	with a minimum of work while gracefully degrading functionality to make the
815	protocol simple.	742	protocol simple.
816		743
817	=item * AEMP has more flexible monitoring options than Erlang.	744	=item * AEMP has more flexible monitoring options than Erlang.
818		745
819	In Erlang, you can chose to receive I<all> exit signals as messages	746	In Erlang, you can chose to receive I<all> exit signals as messages

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.53 by root, Fri Aug 14 15:31:21 2009 UTC vs. Revision 1.66 by root, Fri Aug 28 01:07:24 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.53 by root, Fri Aug 14 15:31:21 2009 UTC vs.
Revision 1.66 by root, Fri Aug 28 01:07:24 2009 UTC