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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.69 by root, Sun Aug 30 18:51:49 2009 UTC vs.
Revision 1.80 by root, Fri Sep 4 22:30:29 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;	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
…		…
38	mon $port, $otherport # kill otherport on abnormal death	37	mon $port, $otherport # kill otherport on abnormal death
39	mon $port, $otherport, @msg # send message on death	38	mon $port, $otherport, @msg # send message on death
40		39
41	=head1 CURRENT STATUS	40	=head1 CURRENT STATUS
42		41
		42	bin/aemp - stable.
43	AnyEvent::MP - stable API, should work	43	AnyEvent::MP - stable API, should work.
44	AnyEvent::MP::Intro - outdated	44	AnyEvent::MP::Intro - explains most concepts.
45	AnyEvent::MP::Kernel - mostly stable	45	AnyEvent::MP::Kernel - mostly stable.
46	AnyEvent::MP::Global - mostly stable	46	AnyEvent::MP::Global - stable but incomplete, protocol not yet final.
47	AnyEvent::MP::Node - mostly stable, but internal anyways
48	AnyEvent::MP::Transport - mostly stable, but internal anyways
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
…		…
57	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.
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 and the examples under F<eg/>.	58	manual page and the examples under F<eg/>.
61		59
62	At the moment, this module family is a bit underdocumented.
63
64	=head1 CONCEPTS	60	=head1 CONCEPTS
65		61
66	=over 4	62	=over 4
67		63
68	=item port	64	=item port
69		65
70	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).
71		68
72	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
73	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
74	anything was listening for them or not.	71	anything was listening for them or not.
75		72
…		…
139		136
140	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	137	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
141		138
142	our @EXPORT = qw(	139	our @EXPORT = qw(
143	NODE $NODE *SELF node_of after	140	NODE $NODE *SELF node_of after
144	initialise_node	141	configure
145	snd rcv mon mon_guard kil reg psub spawn	142	snd rcv mon mon_guard kil reg psub spawn
146	port	143	port
147	);	144	);
148		145
149	our $SELF;	146	our $SELF;
…		…
156		153
157	=item $thisnode = NODE / $NODE	154	=item $thisnode = NODE / $NODE
158		155
159	The C<NODE> function returns, and the C<$NODE> variable contains, the node	156	The C<NODE> function returns, and the C<$NODE> variable contains, the node
160	ID of the node running in the current process. This value is initialised by	157	ID of the node running in the current process. This value is initialised by
161	a call to C<initialise_node>.	158	a call to C<configure>.
162		159
163	=item $nodeid = node_of $port	160	=item $nodeid = node_of $port
164		161
165	Extracts and returns the node ID from a port ID or a node ID.	162	Extracts and returns the node ID from a port ID or a node ID.
166		163
167	=item initialise_node $profile_name, key => value...	164	=item configure $profile, key => value...
		165
		166	=item configure key => value...
168		167
169	Before a node can talk to other nodes on the network (i.e. enter	168	Before a node can talk to other nodes on the network (i.e. enter
170	"distributed mode") it has to initialise itself - the minimum a node needs	169	"distributed mode") it has to configure itself - the minimum a node needs
171	to know is its own name, and optionally it should know the addresses of	170	to know is its own name, and optionally it should know the addresses of
172	some other nodes in the network to discover other nodes.	171	some other nodes in the network to discover other nodes.
173		172
174	This function initialises a node - it must be called exactly once (or	173	This function configures a node - it must be called exactly once (or
175	never) before calling other AnyEvent::MP functions.	174	never) before calling other AnyEvent::MP functions.
176		175
177	The first argument is a profile name. If it is C<undef> or missing, then	176	=over 4
178	the current nodename will be used instead (i.e. F<uname -n>).
179		177
		178	=item step 1, gathering configuration from profiles
		179
180	The function first looks up the profile in the aemp configuration (see the	180	The function first looks up a profile in the aemp configuration (see the
181	L<aemp> commandline utility). the profile is calculated as follows:	181	L<aemp> commandline utility). The profile name can be specified via the
		182	named C<profile> parameter or can simply be the first parameter). If it is
		183	missing, then the nodename (F<uname -n>) will be used as profile name.
182		184
183	First, all remaining key => value pairs will be used. Then they will be	185	The profile data is then gathered as follows:
184	overwritten by any values specified in the global default configuration	186
185	(see the F<aemp> utility), then the chain of profiles selected, if	187	First, all remaining key => value pairs (all of which are conveniently
		188	undocumented at the moment) will be interpreted as configuration
		189	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
		191	profiles chosen by the profile name (and any C<parent> attributes).
		192
186	any. That means that the values specified in the profile have highest	193	That means that the values specified in the profile have highest priority
187	priority and the values specified via C<initialise_node> have lowest	194	and the values specified directly via C<configure> have lowest priority,
188	priority.	195	and can only be used to specify defaults.
189		196
190	If the profile specifies a node ID, then this will become the node ID of	197	If the profile specifies a node ID, then this will become the node ID of
191	this process. If not, then the profile name will be used as node ID. The	198	this process. If not, then the profile name will be used as node ID. The
192	special node ID of C<anon/> will be replaced by a random node ID.	199	special node ID of C<anon/> will be replaced by a random node ID.
		200
		201	=item step 2, bind listener sockets
193		202
194	The next step is to look up the binds in the profile, followed by binding	203	The next step is to look up the binds in the profile, followed by binding
195	aemp protocol listeners on all binds specified (it is possible and valid	204	aemp protocol listeners on all binds specified (it is possible and valid
196	to have no binds, meaning that the node cannot be contacted form the	205	to have no binds, meaning that the node cannot be contacted form the
197	outside. This means the node cannot talk to other nodes that also have no	206	outside. This means the node cannot talk to other nodes that also have no
198	binds, but it can still talk to all "normal" nodes).	207	binds, but it can still talk to all "normal" nodes).
199		208
200	If the profile does not specify a binds list, then the node ID will be	209	If the profile does not specify a binds list, then a default of C<*> is
201	treated as if it were of the form C<host:port>, which will be resolved and	210	used, meaning the node will bind on a dynamically-assigned port on every
202	used as binds list.	211	local IP address it finds.
203		212
		213	=item step 3, connect to seed nodes
		214
204	Lastly, the seeds list from the profile is passed to the	215	As the last step, the seeds list from the profile is passed to the
205	L<AnyEvent::MP::Global> module, which will then use it to keep	216	L<AnyEvent::MP::Global> module, which will then use it to keep
206	connectivity with at least on of those seed nodes at any point in time.	217	connectivity with at least one node at any point in time.
207		218
208	Example: become a distributed node listening on the guessed noderef, or	219	=back
209	the one specified via C<aemp> for the current node. This should be the	220
		221	Example: become a distributed node using the locla node name as profile.
210	most common form of invocation for "daemon"-type nodes.	222	This should be the most common form of invocation for "daemon"-type nodes.
211		223
212	initialise_node;	224	configure
213		225
214	Example: become an anonymous node. This form is often used for commandline	226	Example: become an anonymous node. This form is often used for commandline
215	clients.	227	clients.
216		228
217	initialise_node "anon/";	229	configure nodeid => "anon/";
218		230
219	Example: become a distributed node. If there is no profile of the given	231	Example: configure a node using a profile called seed, which si suitable
220	name, or no binds list was specified, resolve C<localhost:4044> and bind	232	for a seed node as it binds on all local addresses on a fixed port (4040,
221	on the resulting addresses.	233	customary for aemp).
222		234
223	initialise_node "localhost:4044";	235	# use the aemp commandline utility
		236	# aemp profile seed nodeid anon/ binds '*:4040'
		237
		238	# then use it
		239	configure profile => "seed";
		240
		241	# or simply use aemp from the shell again:
		242	# aemp run profile seed
		243
		244	# or provide a nicer-to-remember nodeid
		245	# aemp run profile seed nodeid "$(hostname)"
224		246
225	=item $SELF	247	=item $SELF
226		248
227	Contains the current port id while executing C<rcv> callbacks or C<psub>	249	Contains the current port id while executing C<rcv> callbacks or C<psub>
228	blocks.	250	blocks.
…		…
350		372
351	=cut	373	=cut
352		374
353	sub rcv($@) {	375	sub rcv($@) {
354	my $port = shift;	376	my $port = shift;
355	my ($noderef, $portid) = split /#/, $port, 2;	377	my ($nodeid, $portid) = split /#/, $port, 2;
356		378
357	$NODE{$noderef} == $NODE{""}	379	$NODE{$nodeid} == $NODE{""}
358	or Carp::croak "$port: rcv can only be called on local ports, caught";	380	or Carp::croak "$port: rcv can only be called on local ports, caught";
359		381
360	while (@_) {	382	while (@_) {
361	if (ref $_[0]) {	383	if (ref $_[0]) {
362	if (my $self = $PORT_DATA{$portid}) {	384	if (my $self = $PORT_DATA{$portid}) {
…		…
453		475
454	Monitor the given port and do something when the port is killed or	476	Monitor the given port and do something when the port is killed or
455	messages to it were lost, and optionally return a guard that can be used	477	messages to it were lost, and optionally return a guard that can be used
456	to stop monitoring again.	478	to stop monitoring again.
457		479
		480	In the first form (callback), the callback is simply called with any
		481	number of C<@reason> elements (no @reason means that the port was deleted
		482	"normally"). Note also that I<< the callback B<must> never die >>, so use
		483	C<eval> if unsure.
		484
		485	In the second form (another port given), the other port (C<$rcvport>)
		486	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
		487	"normal" kils nothing happens, while under all other conditions, the other
		488	port is killed with the same reason.
		489
		490	The third form (kill self) is the same as the second form, except that
		491	C<$rvport> defaults to C<$SELF>.
		492
		493	In the last form (message), a message of the form C<@msg, @reason> will be
		494	C<snd>.
		495
		496	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		497	alert was raised), they are removed and will not trigger again.
		498
		499	As a rule of thumb, monitoring requests should always monitor a port from
		500	a local port (or callback). The reason is that kill messages might get
		501	lost, just like any other message. Another less obvious reason is that
		502	even monitoring requests can get lost (for example, when the connection
		503	to the other node goes down permanently). When monitoring a port locally
		504	these problems do not exist.
		505
458	C<mon> effectively guarantees that, in the absence of hardware failures,	506	C<mon> effectively guarantees that, in the absence of hardware failures,
459	after starting the monitor, either all messages sent to the port will	507	after starting the monitor, either all messages sent to the port will
460	arrive, or the monitoring action will be invoked after possible message	508	arrive, or the monitoring action will be invoked after possible message
461	loss has been detected. No messages will be lost "in between" (after	509	loss has been detected. No messages will be lost "in between" (after
462	the first lost message no further messages will be received by the	510	the first lost message no further messages will be received by the
463	port). After the monitoring action was invoked, further messages might get	511	port). After the monitoring action was invoked, further messages might get
464	delivered again.	512	delivered again.
465		513
466	Note that monitoring-actions are one-shot: once messages are lost (and a	514	Inter-host-connection timeouts and monitoring depend on the transport
467	monitoring alert was raised), they are removed and will not trigger again.	515	used. The only transport currently implemented is TCP, and AnyEvent::MP
		516	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		517	non-idle connection, and usually around two hours for idle conenctions).
468		518
469	In the first form (callback), the callback is simply called with any	519	This means that monitoring is good for program errors and cleaning up
470	number of C<@reason> elements (no @reason means that the port was deleted	520	stuff eventually, but they are no replacement for a timeout when you need
471	"normally"). Note also that I<< the callback B<must> never die >>, so use	521	to ensure some maximum latency.
472	C<eval> if unsure.
473
474	In the second form (another port given), the other port (C<$rcvport>)
475	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
476	"normal" kils nothing happens, while under all other conditions, the other
477	port is killed with the same reason.
478
479	The third form (kill self) is the same as the second form, except that
480	C<$rvport> defaults to C<$SELF>.
481
482	In the last form (message), a message of the form C<@msg, @reason> will be
483	C<snd>.
484
485	As a rule of thumb, monitoring requests should always monitor a port from
486	a local port (or callback). The reason is that kill messages might get
487	lost, just like any other message. Another less obvious reason is that
488	even monitoring requests can get lost (for exmaple, when the connection
489	to the other node goes down permanently). When monitoring a port locally
490	these problems do not exist.
491		522
492	Example: call a given callback when C<$port> is killed.	523	Example: call a given callback when C<$port> is killed.
493		524
494	mon $port, sub { warn "port died because of <@_>\n" };	525	mon $port, sub { warn "port died because of <@_>\n" };
495		526
…		…
502	mon $port, $self => "restart";	533	mon $port, $self => "restart";
503		534
504	=cut	535	=cut
505		536
506	sub mon {	537	sub mon {
507	my ($noderef, $port) = split /#/, shift, 2;	538	my ($nodeid, $port) = split /#/, shift, 2;
508		539
509	my $node = $NODE{$noderef} \|\| add_node $noderef;	540	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
510		541
511	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	542	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
512		543
513	unless (ref $cb) {	544	unless (ref $cb) {
514	if (@_) {	545	if (@_) {
…		…
597	A common idiom is to pass a local port, immediately monitor the spawned	628	A common idiom is to pass a local port, immediately monitor the spawned
598	port, and in the remote init function, immediately monitor the passed	629	port, and in the remote init function, immediately monitor the passed
599	local port. This two-way monitoring ensures that both ports get cleaned up	630	local port. This two-way monitoring ensures that both ports get cleaned up
600	when there is a problem.	631	when there is a problem.
601		632
		633	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		634	caller before C<spawn> returns (by delaying invocation when spawn is
		635	called for the local node).
		636
602	Example: spawn a chat server port on C<$othernode>.	637	Example: spawn a chat server port on C<$othernode>.
603		638
604	# this node, executed from within a port context:	639	# this node, executed from within a port context:
605	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	640	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
606	mon $server;	641	mon $server;
…		…
628	};	663	};
629	_self_die if $@;	664	_self_die if $@;
630	}	665	}
631		666
632	sub spawn(@) {	667	sub spawn(@) {
633	my ($noderef, undef) = split /#/, shift, 2;	668	my ($nodeid, undef) = split /#/, shift, 2;
634		669
635	my $id = "$RUNIQ." . $ID++;	670	my $id = "$RUNIQ." . $ID++;
636		671
637	$_[0] =~ /::/	672	$_[0] =~ /::/
638	or Carp::croak "spawn init function must be a fully-qualified name, caught";	673	or Carp::croak "spawn init function must be a fully-qualified name, caught";
639		674
640	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	675	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
641		676
642	"$noderef#$id"	677	"$nodeid#$id"
643	}	678	}
644		679
645	=item after $timeout, @msg	680	=item after $timeout, @msg
646		681
647	=item after $timeout, $callback	682	=item after $timeout, $callback
…		…
686		721
687	=item * Node IDs are arbitrary strings in AEMP.	722	=item * Node IDs are arbitrary strings in AEMP.
688		723
689	Erlang relies on special naming and DNS to work everywhere in the same	724	Erlang relies on special naming and DNS to work everywhere in the same
690	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by	725	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
691	configuraiton or DNS), but will otherwise discover other odes itself.	726	configuration or DNS), but will otherwise discover other odes itself.
692		727
693	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	728	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
694	uses "local ports are like remote ports".	729	uses "local ports are like remote ports".
695		730
696	The failure modes for local ports are quite different (runtime errors	731	The failure modes for local ports are quite different (runtime errors
…		…
709		744
710	Erlang uses processes that selectively receive messages, and therefore	745	Erlang uses processes that selectively receive messages, and therefore
711	needs a queue. AEMP is event based, queuing messages would serve no	746	needs a queue. AEMP is event based, queuing messages would serve no
712	useful purpose. For the same reason the pattern-matching abilities of	747	useful purpose. For the same reason the pattern-matching abilities of
713	AnyEvent::MP are more limited, as there is little need to be able to	748	AnyEvent::MP are more limited, as there is little need to be able to
714	filter messages without dequeing them.	749	filter messages without dequeuing them.
715		750
716	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	751	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
717		752
718	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	753	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
719		754

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.69 by root, Sun Aug 30 18:51:49 2009 UTC vs. Revision 1.80 by root, Fri Sep 4 22:30:29 2009 UTC

Diff Legend

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.69 by root, Sun Aug 30 18:51:49 2009 UTC vs.
Revision 1.80 by root, Fri Sep 4 22:30:29 2009 UTC