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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.72 by root, Mon Aug 31 10:07:04 2009 UTC vs.
Revision 1.86 by root, Wed Sep 9 01:47:01 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	configure;	15	configure;
17		16
18	# ports are message endpoints	17	# ports are message destinations
19		18
20	# sending messages	19	# sending messages
21	snd $port, type => data...;	20	snd $port, type => data...;
22	snd $port, @msg;	21	snd $port, @msg;
23	snd @msg_with_first_element_being_a_port;	22	snd @msg_with_first_element_being_a_port;
24		23
25	# creating/using ports, the simple way	24	# creating/using ports, the simple way
26	my $simple_port = port { my @msg = @_; 0 };	25	my $simple_port = port { my @msg = @_ };
27		26
28	# creating/using ports, tagged message matching	27	# creating/using ports, tagged message matching
29	my $port = port;	28	my $port = port;
30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
31	rcv $port, pong => sub { warn "pong received\n"; 0 };	30	rcv $port, pong => sub { warn "pong received\n" };
32		31
33	# create a port on another node	32	# create a port on another node
34	my $port = spawn $node, $initfunc, @initdata;	33	my $port = spawn $node, $initfunc, @initdata;
35		34
36	# monitoring	35	# monitoring
…		…
40		39
41	=head1 CURRENT STATUS	40	=head1 CURRENT STATUS
42		41
43	bin/aemp - stable.	42	bin/aemp - stable.
44	AnyEvent::MP - stable API, should work.	43	AnyEvent::MP - stable API, should work.
45	AnyEvent::MP::Intro - uptodate, but incomplete.	44	AnyEvent::MP::Intro - explains most concepts.
46	AnyEvent::MP::Kernel - mostly stable.	45	AnyEvent::MP::Kernel - mostly stable.
47	AnyEvent::MP::Global - stable API, protocol not yet final.	46	AnyEvent::MP::Global - stable but incomplete, protocol not yet final.
48		47
49	stay tuned.	48	stay tuned.
50		49
51	=head1 DESCRIPTION	50	=head1 DESCRIPTION
52		51
53	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
54		53
…		…
56	on the same or other hosts, and you can supervise entities remotely.	55	on the same or other hosts, and you can supervise entities remotely.
57		56
58	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>
59	manual page and the examples under F<eg/>.	58	manual page and the examples under F<eg/>.
60		59
61	At the moment, this module family is a bit underdocumented.
62
63	=head1 CONCEPTS	60	=head1 CONCEPTS
64		61
65	=over 4	62	=over 4
66		63
67	=item port	64	=item port
68		65
69	A port is something you can send messages to (with the C<snd> function).	66	Not to be confused with a TCP port, a "port" is something you can send
		67	messages to (with the C<snd> function).
70		68
71	Ports allow you to register C<rcv> handlers that can match all or just	69	Ports allow you to register C<rcv> handlers that can match all or just
72	some messages. Messages send to ports will not be queued, regardless of	70	some messages. Messages send to ports will not be queued, regardless of
73	anything was listening for them or not.	71	anything was listening for them or not.
74		72
…		…
85		83
86	Nodes are either public (have one or more listening ports) or private	84	Nodes are either public (have one or more listening ports) or private
87	(no listening ports). Private nodes cannot talk to other private nodes	85	(no listening ports). Private nodes cannot talk to other private nodes
88	currently.	86	currently.
89		87
90	=item node ID - C<[a-za-Z0-9_\-.:]+>	88	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
91		89
92	A node ID is a string that uniquely identifies the node within a	90	A node ID is a string that uniquely identifies the node within a
93	network. Depending on the configuration used, node IDs can look like a	91	network. Depending on the configuration used, node IDs can look like a
94	hostname, a hostname and a port, or a random string. AnyEvent::MP itself	92	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
95	doesn't interpret node IDs in any way.	93	doesn't interpret node IDs in any way.
…		…
99	Nodes can only talk to each other by creating some kind of connection to	97	Nodes can only talk to each other by creating some kind of connection to
100	each other. To do this, nodes should listen on one or more local transport	98	each other. To do this, nodes should listen on one or more local transport
101	endpoints - binds. Currently, only standard C<ip:port> specifications can	99	endpoints - binds. Currently, only standard C<ip:port> specifications can
102	be used, which specify TCP ports to listen on.	100	be used, which specify TCP ports to listen on.
103		101
104	=item seeds - C<host:port>	102	=item seed nodes
105		103
106	When a node starts, it knows nothing about the network. To teach the node	104	When a node starts, it knows nothing about the network. To teach the node
107	about the network it first has to contact some other node within the	105	about the network it first has to contact some other node within the
108	network. This node is called a seed.	106	network. This node is called a seed.
109		107
110	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	108	Apart from the fact that other nodes know them as seed nodes and they have
		109	to have fixed listening addresses, seed nodes are perfectly normal nodes -
		110	any node can function as a seed node for others.
		111
		112	In addition to discovering the network, seed nodes are also used to
		113	maintain the network and to connect nodes that otherwise would have
		114	trouble connecting. They form the backbone of an AnyEvent::MP network.
		115
111	are expected to be long-running, and at least one of those should always	116	Seed nodes are expected to be long-running, and at least one seed node
112	be available. When nodes run out of connections (e.g. due to a network	117	should always be available. They should also be relatively responsive - a
113	error), they try to re-establish connections to some seednodes again to	118	seed node that blocks for long periods will slow down everybody else.
114	join the network.
115		119
116	Apart from being sued for seeding, seednodes are not special in any way -	120	=item seeds - C<host:port>
117	every public node can be a seednode.	121
		122	Seeds are transport endpoint(s) (usually a hostname/IP address and a
		123	TCP port) of nodes thta should be used as seed nodes.
		124
		125	The nodes listening on those endpoints are expected to be long-running,
		126	and at least one of those should always be available. When nodes run out
		127	of connections (e.g. due to a network error), they try to re-establish
		128	connections to some seednodes again to join the network.
118		129
119	=back	130	=back
120		131
121	=head1 VARIABLES/FUNCTIONS	132	=head1 VARIABLES/FUNCTIONS
122		133
…		…
161		172
162	=item $nodeid = node_of $port	173	=item $nodeid = node_of $port
163		174
164	Extracts and returns the node ID from a port ID or a node ID.	175	Extracts and returns the node ID from a port ID or a node ID.
165		176
		177	=item configure $profile, key => value...
		178
166	=item configure key => value...	179	=item configure key => value...
167		180
168	Before a node can talk to other nodes on the network (i.e. enter	181	Before a node can talk to other nodes on the network (i.e. enter
169	"distributed mode") it has to configure itself - the minimum a node needs	182	"distributed mode") it has to configure itself - the minimum a node needs
170	to know is its own name, and optionally it should know the addresses of	183	to know is its own name, and optionally it should know the addresses of
…		…
177		190
178	=item step 1, gathering configuration from profiles	191	=item step 1, gathering configuration from profiles
179		192
180	The function first looks up a profile in the aemp configuration (see the	193	The function first looks up a profile in the aemp configuration (see the
181	L<aemp> commandline utility). The profile name can be specified via the	194	L<aemp> commandline utility). The profile name can be specified via the
182	named C<profile> parameter. If it is missing, then the nodename (F<uname	195	named C<profile> parameter or can simply be the first parameter). If it is
183	-n>) will be used as profile name.	196	missing, then the nodename (F<uname -n>) will be used as profile name.
184		197
185	The profile data is then gathered as follows:	198	The profile data is then gathered as follows:
186		199
187	First, all remaining key => value pairs (all of which are conviniently	200	First, all remaining key => value pairs (all of which are conveniently
188	undocumented at the moment) will be interpreted as configuration	201	undocumented at the moment) will be interpreted as configuration
189	data. Then they will be overwritten by any values specified in the global	202	data. Then they will be overwritten by any values specified in the global
190	default configuration (see the F<aemp> utility), then the chain of	203	default configuration (see the F<aemp> utility), then the chain of
191	profiles chosen by the profile name (and any C<parent> attributes).	204	profiles chosen by the profile name (and any C<parent> attributes).
192		205
…		…
231	Example: configure a node using a profile called seed, which si suitable	244	Example: configure a node using a profile called seed, which si suitable
232	for a seed node as it binds on all local addresses on a fixed port (4040,	245	for a seed node as it binds on all local addresses on a fixed port (4040,
233	customary for aemp).	246	customary for aemp).
234		247
235	# use the aemp commandline utility	248	# use the aemp commandline utility
236	# aemp profile seed setnodeid anon/ setbinds '*:4040'	249	# aemp profile seed nodeid anon/ binds '*:4040'
237		250
238	# then use it	251	# then use it
239	configure profile => "seed";	252	configure profile => "seed";
240		253
241	# or simply use aemp from the shell again:	254	# or simply use aemp from the shell again:
…		…
372		385
373	=cut	386	=cut
374		387
375	sub rcv($@) {	388	sub rcv($@) {
376	my $port = shift;	389	my $port = shift;
377	my ($noderef, $portid) = split /#/, $port, 2;	390	my ($nodeid, $portid) = split /#/, $port, 2;
378		391
379	$NODE{$noderef} == $NODE{""}	392	$NODE{$nodeid} == $NODE{""}
380	or Carp::croak "$port: rcv can only be called on local ports, caught";	393	or Carp::croak "$port: rcv can only be called on local ports, caught";
381		394
382	while (@_) {	395	while (@_) {
383	if (ref $_[0]) {	396	if (ref $_[0]) {
384	if (my $self = $PORT_DATA{$portid}) {	397	if (my $self = $PORT_DATA{$portid}) {
…		…
475		488
476	Monitor the given port and do something when the port is killed or	489	Monitor the given port and do something when the port is killed or
477	messages to it were lost, and optionally return a guard that can be used	490	messages to it were lost, and optionally return a guard that can be used
478	to stop monitoring again.	491	to stop monitoring again.
479		492
		493	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
		495	"normally"). Note also that I<< the callback B<must> never die >>, so use
		496	C<eval> if unsure.
		497
		498	In the second form (another port given), the other port (C<$rcvport>)
		499	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
		500	"normal" kils nothing happens, while under all other conditions, the other
		501	port is killed with the same reason.
		502
		503	The third form (kill self) is the same as the second form, except that
		504	C<$rvport> defaults to C<$SELF>.
		505
		506	In the last form (message), a message of the form C<@msg, @reason> will be
		507	C<snd>.
		508
		509	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		510	alert was raised), they are removed and will not trigger again.
		511
		512	As a rule of thumb, monitoring requests should always monitor a port from
		513	a local port (or callback). The reason is that kill messages might get
		514	lost, just like any other message. Another less obvious reason is that
		515	even monitoring requests can get lost (for example, when the connection
		516	to the other node goes down permanently). When monitoring a port locally
		517	these problems do not exist.
		518
480	C<mon> effectively guarantees that, in the absence of hardware failures,	519	C<mon> effectively guarantees that, in the absence of hardware failures,
481	after starting the monitor, either all messages sent to the port will	520	after starting the monitor, either all messages sent to the port will
482	arrive, or the monitoring action will be invoked after possible message	521	arrive, or the monitoring action will be invoked after possible message
483	loss has been detected. No messages will be lost "in between" (after	522	loss has been detected. No messages will be lost "in between" (after
484	the first lost message no further messages will be received by the	523	the first lost message no further messages will be received by the
485	port). After the monitoring action was invoked, further messages might get	524	port). After the monitoring action was invoked, further messages might get
486	delivered again.	525	delivered again.
487		526
488	Note that monitoring-actions are one-shot: once messages are lost (and a	527	Inter-host-connection timeouts and monitoring depend on the transport
489	monitoring alert was raised), they are removed and will not trigger again.	528	used. The only transport currently implemented is TCP, and AnyEvent::MP
		529	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		530	non-idle connection, and usually around two hours for idle conenctions).
490		531
491	In the first form (callback), the callback is simply called with any	532	This means that monitoring is good for program errors and cleaning up
492	number of C<@reason> elements (no @reason means that the port was deleted	533	stuff eventually, but they are no replacement for a timeout when you need
493	"normally"). Note also that I<< the callback B<must> never die >>, so use	534	to ensure some maximum latency.
494	C<eval> if unsure.
495
496	In the second form (another port given), the other port (C<$rcvport>)
497	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
498	"normal" kils nothing happens, while under all other conditions, the other
499	port is killed with the same reason.
500
501	The third form (kill self) is the same as the second form, except that
502	C<$rvport> defaults to C<$SELF>.
503
504	In the last form (message), a message of the form C<@msg, @reason> will be
505	C<snd>.
506
507	As a rule of thumb, monitoring requests should always monitor a port from
508	a local port (or callback). The reason is that kill messages might get
509	lost, just like any other message. Another less obvious reason is that
510	even monitoring requests can get lost (for exmaple, when the connection
511	to the other node goes down permanently). When monitoring a port locally
512	these problems do not exist.
513		535
514	Example: call a given callback when C<$port> is killed.	536	Example: call a given callback when C<$port> is killed.
515		537
516	mon $port, sub { warn "port died because of <@_>\n" };	538	mon $port, sub { warn "port died because of <@_>\n" };
517		539
…		…
524	mon $port, $self => "restart";	546	mon $port, $self => "restart";
525		547
526	=cut	548	=cut
527		549
528	sub mon {	550	sub mon {
529	my ($noderef, $port) = split /#/, shift, 2;	551	my ($nodeid, $port) = split /#/, shift, 2;
530		552
531	my $node = $NODE{$noderef} \|\| add_node $noderef;	553	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
532		554
533	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	555	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
534		556
535	unless (ref $cb) {	557	unless (ref $cb) {
536	if (@_) {	558	if (@_) {
…		…
612	the package, then the package above the package and so on (e.g.	634	the package, then the package above the package and so on (e.g.
613	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	635	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
614	exists or it runs out of package names.	636	exists or it runs out of package names.
615		637
616	The init function is then called with the newly-created port as context	638	The init function is then called with the newly-created port as context
617	object (C<$SELF>) and the C<@initdata> values as arguments.	639	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		640	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		641	the port might not get created.
618		642
619	A common idiom is to pass a local port, immediately monitor the spawned	643	A common idiom is to pass a local port, immediately monitor the spawned
620	port, and in the remote init function, immediately monitor the passed	644	port, and in the remote init function, immediately monitor the passed
621	local port. This two-way monitoring ensures that both ports get cleaned up	645	local port. This two-way monitoring ensures that both ports get cleaned up
622	when there is a problem.	646	when there is a problem.
623		647
		648	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		649	caller before C<spawn> returns (by delaying invocation when spawn is
		650	called for the local node).
		651
624	Example: spawn a chat server port on C<$othernode>.	652	Example: spawn a chat server port on C<$othernode>.
625		653
626	# this node, executed from within a port context:	654	# this node, executed from within a port context:
627	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	655	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
628	mon $server;	656	mon $server;
…		…
642		670
643	sub _spawn {	671	sub _spawn {
644	my $port = shift;	672	my $port = shift;
645	my $init = shift;	673	my $init = shift;
646		674
		675	# rcv will create the actual port
647	local $SELF = "$NODE#$port";	676	local $SELF = "$NODE#$port";
648	eval {	677	eval {
649	&{ load_func $init }	678	&{ load_func $init }
650	};	679	};
651	_self_die if $@;	680	_self_die if $@;
652	}	681	}
653		682
654	sub spawn(@) {	683	sub spawn(@) {
655	my ($noderef, undef) = split /#/, shift, 2;	684	my ($nodeid, undef) = split /#/, shift, 2;
656		685
657	my $id = "$RUNIQ." . $ID++;	686	my $id = "$RUNIQ." . $ID++;
658		687
659	$_[0] =~ /::/	688	$_[0] =~ /::/
660	or Carp::croak "spawn init function must be a fully-qualified name, caught";	689	or Carp::croak "spawn init function must be a fully-qualified name, caught";
661		690
662	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	691	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
663		692
664	"$noderef#$id"	693	"$nodeid#$id"
665	}	694	}
666		695
667	=item after $timeout, @msg	696	=item after $timeout, @msg
668		697
669	=item after $timeout, $callback	698	=item after $timeout, $callback
…		…
708		737
709	=item * Node IDs are arbitrary strings in AEMP.	738	=item * Node IDs are arbitrary strings in AEMP.
710		739
711	Erlang relies on special naming and DNS to work everywhere in the same	740	Erlang relies on special naming and DNS to work everywhere in the same
712	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by	741	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
713	configuraiton or DNS), but will otherwise discover other odes itself.	742	configuration or DNS), but will otherwise discover other odes itself.
714		743
715	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	744	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
716	uses "local ports are like remote ports".	745	uses "local ports are like remote ports".
717		746
718	The failure modes for local ports are quite different (runtime errors	747	The failure modes for local ports are quite different (runtime errors
…		…
731		760
732	Erlang uses processes that selectively receive messages, and therefore	761	Erlang uses processes that selectively receive messages, and therefore
733	needs a queue. AEMP is event based, queuing messages would serve no	762	needs a queue. AEMP is event based, queuing messages would serve no
734	useful purpose. For the same reason the pattern-matching abilities of	763	useful purpose. For the same reason the pattern-matching abilities of
735	AnyEvent::MP are more limited, as there is little need to be able to	764	AnyEvent::MP are more limited, as there is little need to be able to
736	filter messages without dequeing them.	765	filter messages without dequeuing them.
737		766
738	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	767	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
739		768
740	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	769	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
741		770
…		…
847	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	876	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
848		877
849	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	878	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
850	your applications.	879	your applications.
851		880
		881	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		882	all nodes.
		883
852	L<AnyEvent>.	884	L<AnyEvent>.
853		885
854	=head1 AUTHOR	886	=head1 AUTHOR
855		887
856	Marc Lehmann <schmorp@schmorp.de>	888	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.72 by root, Mon Aug 31 10:07:04 2009 UTC vs. Revision 1.86 by root, Wed Sep 9 01:47:01 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.72 by root, Mon Aug 31 10:07:04 2009 UTC vs.
Revision 1.86 by root, Wed Sep 9 01:47:01 2009 UTC