[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 1.66 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...;
24	snd $port, @msg;	22	snd $port, @msg;
25	snd @msg_with_first_element_being_a_port;	23	snd @msg_with_first_element_being_a_port;
26		24
27	# creating/using ports, the simple way	25	# creating/using ports, the simple way
28	my $somple_port = port { my @msg = @_; 0 };	26	my $simple_port = port { my @msg = @_; 0 };
29		27
30	# creating/using ports, tagged message matching	28	# creating/using ports, tagged message matching
31	my $port = port;	29	my $port = port;
32	rcv $port, ping => sub { snd $_[0], "pong"; 0 };	30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
33	rcv $port, pong => sub { warn "pong received\n"; 0 };	31	rcv $port, pong => sub { warn "pong received\n"; 0 };
…		…
69		67
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	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
75	messages. All C<rcv> handlers will receive messages they match, messages	73	some messages. Messages send to ports will not be queued, regardless of
76	will not be queued.	74	anything was listening for them or not.
77		75
78	=item port id - C<noderef#portname>	76	=item port ID - C<noderef#portname>
79		77
80	A port id is normaly 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
81	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
82	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
83	reference.	81	reference.
84		82
85	=item node	83	=item node
86		84
87	A node is a single process containing at least one port - the node	85	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	86	which provides nodes to manage each other remotely, and to create new
89	create new ports, among other things.	87	ports.
90		88
91	Nodes are either private (single-process only), slaves (connected to a	89	Nodes are either private (single-process only), slaves (can only talk to
92	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).
93		92
94	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	93	=item node ID - C<[a-za-Z0-9_\-.:]+>
95		94
96	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
97	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
98	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.
99		99
100	This recipe is simply a comma-separated list of C<address:port> pairs (for	100	=item binds - C<ip:port>
101	TCP/IP, other protocols might look different).
102		101
103	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
104	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.
105		106
106	Before using an unresolved node reference in a message you first have to	107	=item seeds - C<host:port>
107	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.
108		118
109	=back	119	=back
110		120
111	=head1 VARIABLES/FUNCTIONS	121	=head1 VARIABLES/FUNCTIONS
112		122
…		…
127	use base "Exporter";	137	use base "Exporter";
128		138
129	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	139	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
130		140
131	our @EXPORT = qw(	141	our @EXPORT = qw(
132	NODE $NODE *SELF node_of _any_	142	NODE $NODE *SELF node_of after
133	resolve_node initialise_node	143	resolve_node initialise_node
134	snd rcv mon kil reg psub spawn	144	snd rcv mon mon_guard kil reg psub spawn
135	port	145	port
136	);	146	);
137		147
138	our $SELF;	148	our $SELF;
139		149
…		…
143	kil $SELF, die => $msg;	153	kil $SELF, die => $msg;
144	}	154	}
145		155
146	=item $thisnode = NODE / $NODE	156	=item $thisnode = NODE / $NODE
147		157
148	The C<NODE> function returns, and the C<$NODE> variable contains the	158	The C<NODE> function returns, and the C<$NODE> variable contains the node
149	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
150	C<initialise_node>.	160	a call to C<initialise_node>.
151		161
152	=item $noderef = node_of $port	162	=item $nodeid = node_of $port
153		163
154	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.
155		165
156	=item initialise_node $noderef, $seednode, $seednode...	166	=item initialise_node $profile_name
157		167
158	=item initialise_node "slave/", $master, $master...
159
160	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
161	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
162	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.
163		172
164	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
165	never) before calling other AnyEvent::MP functions.	174	never) before calling other AnyEvent::MP functions.
166		175
167	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
168	either resolved or unresolved.	177	the current nodename will be used instead (i.e. F<uname -n>).
169		178
170	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
171	(if it is C<undef> then the current nodename will be used instead) to find	180	L<aemp> commandline utility).
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		181
176	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.
177		185
178	=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).
179		191
180	=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.
181		195
182	For public nodes, C<$noderef> (supplied either directly to	196	Lastly, the seeds list from the profile is passed to the
183	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
184	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.
185		199
186	After resolving, the node will bind itself on all endpoints and try to
187	connect to all additional C<$seednodes> that are specified. Seednodes are
188	optional and can be used to quickly bootstrap the node into an existing
189	network.
190
191	=item slave nodes
192
193	When the C<$noderef> (either as given or overriden by the config file)
194	is the special string C<slave/>, then the node will become a slave
195	node. Slave nodes cannot be contacted from outside and will route most of
196	their traffic to the master node that they attach to.
197
198	At least one additional noderef is required (either by specifying it
199	directly or because it is part of the configuration profile): The node
200	will try to connect to all of them and will become a slave attached to the
201	first node it can successfully connect to.
202
203	=back
204
205	This function will block until all nodes have been resolved and, for slave
206	nodes, until it has successfully established a connection to a master
207	server.
208
209	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
210	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
211	form of invocation for "daemon"-type nodes.	202	most common form of invocation for "daemon"-type nodes.
212		203
213	initialise_node;	204	initialise_node;
214		205
215	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
216	C<aemp>. This form is often used for commandline clients.	207	clients.
217		208
218	initialise_node "slave/";	209	initialise_node "anon/";
219		210
220	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
221	form is also often used for commandline clients.	212	name, or no binds list was specified, resolve C<localhost:4044> and bind
222		213	on the resulting addresses.
223	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
224
225	Example: become a public node, and try to contact some well-known master
226	servers to become part of the network.
227
228	initialise_node undef, "master1", "master2";
229
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		214
236	initialise_node "localhost:4044";	215	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		216
267	=item $SELF	217	=item $SELF
268		218
269	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>
270	blocks.	220	blocks.
…		…
349	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
350	C<tag> match.	300	C<tag> match.
351		301
352	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...	302	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
353		303
354	Register callbacks to be called on messages starting with the given tag on	304	Register (or replace) callbacks to be called on messages starting with the
355	the given port (and return the port), or unregister it (when C<$callback>	305	given tag on the given port (and return the port), or unregister it (when
356	is C<$undef>).	306	C<$callback> is C<$undef> or missing). There can only be one callback
		307	registered for each tag.
357		308
358	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
359	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
360	environment as the default callback (see above).	311	environment as the default callback (see above).
361		312
…		…
373	rcv port,	324	rcv port,
374	msg1 => sub { ... },	325	msg1 => sub { ... },
375	...	326	...
376	;	327	;
377		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, $otherport;
		336	};
		337
378	=cut	338	=cut
379		339
380	sub rcv($@) {	340	sub rcv($@) {
381	my $port = shift;	341	my $port = shift;
382	my ($noderef, $portid) = split /#/, $port, 2;	342	my ($noderef, $portid) = split /#/, $port, 2;
383		343
384	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	344	$NODE{$noderef} == $NODE{""}
385	or Carp::croak "$port: rcv can only be called on local ports, caught";	345	or Carp::croak "$port: rcv can only be called on local ports, caught";
386		346
387	while (@_) {	347	while (@_) {
388	if (ref $_[0]) {	348	if (ref $_[0]) {
389	if (my $self = $PORT_DATA{$portid}) {	349	if (my $self = $PORT_DATA{$portid}) {
…		…
488	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"
489	(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
490	port). After the monitoring action was invoked, further messages might get	450	port). After the monitoring action was invoked, further messages might get
491	delivered again.	451	delivered again.
492		452
		453	Note that monitoring-actions are one-shot: once released, they are removed
		454	and will not trigger again.
		455
493	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
494	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
495	"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
496	C<eval> if unsure.	459	C<eval> if unsure.
497		460
…		…
657	my $id = "$RUNIQ." . $ID++;	620	my $id = "$RUNIQ." . $ID++;
658		621
659	$_[0] =~ /::/	622	$_[0] =~ /::/
660	or Carp::croak "spawn init function must be a fully-qualified name, caught";	623	or Carp::croak "spawn init function must be a fully-qualified name, caught";
661		624
662	($NODE{$noderef} \|\| add_node $noderef)	625	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
663	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
664		626
665	"$noderef#$id"	627	"$noderef#$id"
666	}	628	}
667		629
668	=back	630	=item after $timeout, @msg
669		631
670	=head1 NODE MESSAGES	632	=item after $timeout, $callback
671		633
672	Nodes understand the following messages sent to them. Many of them take	634	Either sends the given message, or call the given callback, after the
673	arguments called C<@reply>, which will simply be used to compose a reply	635	specified number of seconds.
674	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
675	the remaining arguments are simply the message data.
676		636
677	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.
678		638
679	=over 4
680
681	=cut	639	=cut
682		640
683	=item lookup => $name, @reply	641	sub after($@) {
		642	my ($timeout, @action) = @_;
684		643
685	Replies with the port ID of the specified well-known port, or C<undef>.	644	my $t; $t = AE::timer $timeout, 0, sub {
686		645	undef $t;
687	=item devnull => ...	646	ref $action[0]
688		647	? $action[0]()
689	Generic data sink/CPU heat conversion.	648	: snd @action;
690		649	};
691	=item relay => $port, @msg	650	}
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		651
714	=back	652	=back
715		653
716	=head1 AnyEvent::MP vs. Distributed Erlang	654	=head1 AnyEvent::MP vs. Distributed Erlang
717		655
…		…
727		665
728	Despite the similarities, there are also some important differences:	666	Despite the similarities, there are also some important differences:
729		667
730	=over 4	668	=over 4
731		669
732	=item * Node references contain the recipe on how to contact them.	670	=item * Node IDs are arbitrary strings in AEMP.
733		671
734	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
735	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
736	convenience functionality.	674	configuraiton or DNS), but will otherwise discover other odes itself.
737		675
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	676	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
742	uses "local ports are like remote ports".	677	uses "local ports are like remote ports".
743		678
744	The failure modes for local ports are quite different (runtime errors	679	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,	680	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	681	when a connection to another node dies, you know nothing about the other
…		…
773		708
774	Erlang makes few guarantees on messages delivery - messages can get lost	709	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,	710	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).	711	and c, and the other side only receives messages a and c).
777		712
778	AEMP guarantees correct ordering, and the guarantee that there are no	713	AEMP guarantees correct ordering, and the guarantee that after one message
779	holes in the message sequence.	714	is lost, all following ones sent to the same port are lost as well, until
780		715	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	716	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		717
792	=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.
793		719
794	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
795	known to other nodes for a completely different process, causing messages	721	known to other nodes for a completely different process, causing messages
…		…
799	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.
800		726
801	=item * Erlang uses unprotected connections, AEMP uses secure	727	=item * Erlang uses unprotected connections, AEMP uses secure
802	authentication and can use TLS.	728	authentication and can use TLS.
803		729
804	AEMP can use a proven protocol - SSL/TLS - to protect connections and	730	AEMP can use a proven protocol - TLS - to protect connections and
805	securely authenticate nodes.	731	securely authenticate nodes.
806		732
807	=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
808	communications.	734	communications.
809		735
810	The AEMP protocol, unlike the Erlang protocol, supports both	736	The AEMP protocol, unlike the Erlang protocol, supports both programming
811	language-independent text-only protocols (good for debugging) and binary,	737	language independent text-only protocols (good for debugging) and binary,
812	language-specific serialisers (e.g. Storable).	738	language-specific serialisers (e.g. Storable).
813		739
814	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
815	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
816	protocol simple.	742	protocol simple.
817		743
818	=item * AEMP has more flexible monitoring options than Erlang.	744	=item * AEMP has more flexible monitoring options than Erlang.
819		745
820	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 1.52 by root, Fri Aug 14 15:13:20 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 1.52 by root, Fri Aug 14 15:13:20 2009 UTC vs.
Revision 1.66 by root, Fri Aug 28 01:07:24 2009 UTC