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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.70 by root, Sun Aug 30 19:49:47 2009 UTC vs.
Revision 1.103 by root, Sat Oct 17 01:42:39 2009 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent::MP - multi-processing/message-passing framework	3	AnyEvent::MP - erlang-style multi-processing/message-passing framework
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
		35	# destroy a prot again
		36	kil $port; # "normal" kill
		37	kil $port, my_error => "everything is broken"; # error kill
		38
36	# monitoring	39	# monitoring
37	mon $port, $cb->(@msg) # callback is invoked on death	40	mon $localport, $cb->(@msg) # callback is invoked on death
38	mon $port, $otherport # kill otherport on abnormal death	41	mon $localport, $otherport # kill otherport on abnormal death
39	mon $port, $otherport, @msg # send message on death	42	mon $localport, $otherport, @msg # send message on death
		43
		44	# temporarily execute code in port context
		45	peval $port, sub { die "kill the port!" };
		46
		47	# execute callbacks in $SELF port context
		48	my $timer = AE::timer 1, 0, psub {
		49	die "kill the port, delayed";
		50	};
40		51
41	=head1 CURRENT STATUS	52	=head1 CURRENT STATUS
42		53
		54	bin/aemp - stable.
43	AnyEvent::MP - stable API, should work	55	AnyEvent::MP - stable API, should work.
44	AnyEvent::MP::Intro - outdated	56	AnyEvent::MP::Intro - explains most concepts.
45	AnyEvent::MP::Kernel - mostly stable	57	AnyEvent::MP::Kernel - mostly stable API.
46	AnyEvent::MP::Global - mostly stable	58	AnyEvent::MP::Global - stable API.
47	AnyEvent::MP::Node - mostly stable, but internal anyways
48	AnyEvent::MP::Transport - mostly stable, but internal anyways
49
50	stay tuned.
51		59
52	=head1 DESCRIPTION	60	=head1 DESCRIPTION
53		61
54	This module (-family) implements a simple message passing framework.	62	This module (-family) implements a simple message passing framework.
55		63
57	on the same or other hosts, and you can supervise entities remotely.	65	on the same or other hosts, and you can supervise entities remotely.
58		66
59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	67	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
60	manual page and the examples under F<eg/>.	68	manual page and the examples under F<eg/>.
61		69
62	At the moment, this module family is a bit underdocumented.
63
64	=head1 CONCEPTS	70	=head1 CONCEPTS
65		71
66	=over 4	72	=over 4
67		73
68	=item port	74	=item port
69		75
70	A port is something you can send messages to (with the C<snd> function).	76	Not to be confused with a TCP port, a "port" is something you can send
		77	messages to (with the C<snd> function).
71		78
72	Ports allow you to register C<rcv> handlers that can match all or just	79	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	80	some messages. Messages send to ports will not be queued, regardless of
74	anything was listening for them or not.	81	anything was listening for them or not.
75		82
…		…
86		93
87	Nodes are either public (have one or more listening ports) or private	94	Nodes are either public (have one or more listening ports) or private
88	(no listening ports). Private nodes cannot talk to other private nodes	95	(no listening ports). Private nodes cannot talk to other private nodes
89	currently.	96	currently.
90		97
91	=item node ID - C<[a-za-Z0-9_\-.:]+>	98	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
92		99
93	A node ID is a string that uniquely identifies the node within a	100	A node ID is a string that uniquely identifies the node within a
94	network. Depending on the configuration used, node IDs can look like a	101	network. Depending on the configuration used, node IDs can look like a
95	hostname, a hostname and a port, or a random string. AnyEvent::MP itself	102	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
96	doesn't interpret node IDs in any way.	103	doesn't interpret node IDs in any way.
…		…
100	Nodes can only talk to each other by creating some kind of connection to	107	Nodes can only talk to each other by creating some kind of connection to
101	each other. To do this, nodes should listen on one or more local transport	108	each other. To do this, nodes should listen on one or more local transport
102	endpoints - binds. Currently, only standard C<ip:port> specifications can	109	endpoints - binds. Currently, only standard C<ip:port> specifications can
103	be used, which specify TCP ports to listen on.	110	be used, which specify TCP ports to listen on.
104		111
105	=item seeds - C<host:port>	112	=item seed nodes
106		113
107	When a node starts, it knows nothing about the network. To teach the node	114	When a node starts, it knows nothing about the network. To teach the node
108	about the network it first has to contact some other node within the	115	about the network it first has to contact some other node within the
109	network. This node is called a seed.	116	network. This node is called a seed.
110		117
111	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	118	Apart from the fact that other nodes know them as seed nodes and they have
		119	to have fixed listening addresses, seed nodes are perfectly normal nodes -
		120	any node can function as a seed node for others.
		121
		122	In addition to discovering the network, seed nodes are also used to
		123	maintain the network and to connect nodes that otherwise would have
		124	trouble connecting. They form the backbone of an AnyEvent::MP network.
		125
112	are expected to be long-running, and at least one of those should always	126	Seed nodes are expected to be long-running, and at least one seed node
113	be available. When nodes run out of connections (e.g. due to a network	127	should always be available. They should also be relatively responsive - a
114	error), they try to re-establish connections to some seednodes again to	128	seed node that blocks for long periods will slow down everybody else.
115	join the network.
116		129
117	Apart from being sued for seeding, seednodes are not special in any way -	130	=item seeds - C<host:port>
118	every public node can be a seednode.	131
		132	Seeds are transport endpoint(s) (usually a hostname/IP address and a
		133	TCP port) of nodes that should be used as seed nodes.
		134
		135	The nodes listening on those endpoints are expected to be long-running,
		136	and at least one of those should always be available. When nodes run out
		137	of connections (e.g. due to a network error), they try to re-establish
		138	connections to some seednodes again to join the network.
119		139
120	=back	140	=back
121		141
122	=head1 VARIABLES/FUNCTIONS	142	=head1 VARIABLES/FUNCTIONS
123		143
…		…
135		155
136	use AE ();	156	use AE ();
137		157
138	use base "Exporter";	158	use base "Exporter";
139		159
140	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	160	our $VERSION = 1.22;
141		161
142	our @EXPORT = qw(	162	our @EXPORT = qw(
143	NODE $NODE *SELF node_of after	163	NODE $NODE *SELF node_of after
144	initialise_node	164	configure
145	snd rcv mon mon_guard kil reg psub spawn	165	snd rcv mon mon_guard kil psub peval spawn cal
146	port	166	port
147	);	167	);
148		168
149	our $SELF;	169	our $SELF;
150		170
…		…
156		176
157	=item $thisnode = NODE / $NODE	177	=item $thisnode = NODE / $NODE
158		178
159	The C<NODE> function returns, and the C<$NODE> variable contains, the node	179	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	180	ID of the node running in the current process. This value is initialised by
161	a call to C<initialise_node>.	181	a call to C<configure>.
162		182
163	=item $nodeid = node_of $port	183	=item $nodeid = node_of $port
164		184
165	Extracts and returns the node ID from a port ID or a node ID.	185	Extracts and returns the node ID from a port ID or a node ID.
166		186
167	=item initialise_node $profile_name, key => value...	187	=item configure $profile, key => value...
		188
		189	=item configure key => value...
168		190
169	Before a node can talk to other nodes on the network (i.e. enter	191	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	192	"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	193	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.	194	some other nodes in the network to discover other nodes.
173		195
174	This function initialises a node - it must be called exactly once (or	196	This function configures a node - it must be called exactly once (or
175	never) before calling other AnyEvent::MP functions.	197	never) before calling other AnyEvent::MP functions.
176		198
177	The first argument is a profile name. If it is C<undef> or missing, then	199	=over 4
178	the current nodename will be used instead (i.e. F<uname -n>).
179		200
		201	=item step 1, gathering configuration from profiles
		202
180	The function first looks up the profile in the aemp configuration (see the	203	The function first looks up a profile in the aemp configuration (see the
181	L<aemp> commandline utility). the profile is calculated as follows:	204	L<aemp> commandline utility). The profile name can be specified via the
		205	named C<profile> parameter or can simply be the first parameter). If it is
		206	missing, then the nodename (F<uname -n>) will be used as profile name.
182		207
		208	The profile data is then gathered as follows:
		209
183	First, all remaining key => value pairs (all of which are conviniently	210	First, all remaining key => value pairs (all of which are conveniently
184	undocumented at the moment) will be used. Then they will be overwritten by	211	undocumented at the moment) will be interpreted as configuration
185	any values specified in the global default configuration (see the F<aemp>	212	data. Then they will be overwritten by any values specified in the global
186	utility), then the chain of profiles selected, if any. That means that	213	default configuration (see the F<aemp> utility), then the chain of
		214	profiles chosen by the profile name (and any C<parent> attributes).
		215
187	the values specified in the profile have highest priority and the values	216	That means that the values specified in the profile have highest priority
188	specified via C<initialise_node> have lowest priority.	217	and the values specified directly via C<configure> have lowest priority,
		218	and can only be used to specify defaults.
189		219
190	If the profile specifies a node ID, then this will become the node ID of	220	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	221	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.	222	special node ID of C<anon/> will be replaced by a random node ID.
		223
		224	=item step 2, bind listener sockets
193		225
194	The next step is to look up the binds in the profile, followed by binding	226	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	227	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	228	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	229	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).	230	binds, but it can still talk to all "normal" nodes).
199		231
200	If the profile does not specify a binds list, then a default of C<*> is	232	If the profile does not specify a binds list, then a default of C<*> is
201	used.	233	used, meaning the node will bind on a dynamically-assigned port on every
		234	local IP address it finds.
202		235
		236	=item step 3, connect to seed nodes
		237
203	Lastly, the seeds list from the profile is passed to the	238	As the last step, the seeds list from the profile is passed to the
204	L<AnyEvent::MP::Global> module, which will then use it to keep	239	L<AnyEvent::MP::Global> module, which will then use it to keep
205	connectivity with at least on of those seed nodes at any point in time.	240	connectivity with at least one node at any point in time.
206		241
207	Example: become a distributed node listening on the guessed noderef, or	242	=back
208	the one specified via C<aemp> for the current node. This should be the	243
		244	Example: become a distributed node using the local node name as profile.
209	most common form of invocation for "daemon"-type nodes.	245	This should be the most common form of invocation for "daemon"-type nodes.
210		246
211	initialise_node;	247	configure
212		248
213	Example: become an anonymous node. This form is often used for commandline	249	Example: become an anonymous node. This form is often used for commandline
214	clients.	250	clients.
215		251
216	initialise_node "anon/";	252	configure nodeid => "anon/";
217		253
218	Example: become a distributed node. If there is no profile of the given	254	Example: configure a node using a profile called seed, which si suitable
219	name, or no binds list was specified, resolve C<localhost:4044> and bind	255	for a seed node as it binds on all local addresses on a fixed port (4040,
220	on the resulting addresses.	256	customary for aemp).
221		257
222	initialise_node "localhost:4044";	258	# use the aemp commandline utility
		259	# aemp profile seed nodeid anon/ binds '*:4040'
		260
		261	# then use it
		262	configure profile => "seed";
		263
		264	# or simply use aemp from the shell again:
		265	# aemp run profile seed
		266
		267	# or provide a nicer-to-remember nodeid
		268	# aemp run profile seed nodeid "$(hostname)"
223		269
224	=item $SELF	270	=item $SELF
225		271
226	Contains the current port id while executing C<rcv> callbacks or C<psub>	272	Contains the current port id while executing C<rcv> callbacks or C<psub>
227	blocks.	273	blocks.
…		…
337	msg1 => sub { ... },	383	msg1 => sub { ... },
338	...	384	...
339	;	385	;
340		386
341	Example: temporarily register a rcv callback for a tag matching some port	387	Example: temporarily register a rcv callback for a tag matching some port
342	(e.g. for a rpc reply) and unregister it after a message was received.	388	(e.g. for an rpc reply) and unregister it after a message was received.
343		389
344	rcv $port, $otherport => sub {	390	rcv $port, $otherport => sub {
345	my @reply = @_;	391	my @reply = @_;
346		392
347	rcv $SELF, $otherport;	393	rcv $SELF, $otherport;
…		…
349		395
350	=cut	396	=cut
351		397
352	sub rcv($@) {	398	sub rcv($@) {
353	my $port = shift;	399	my $port = shift;
354	my ($noderef, $portid) = split /#/, $port, 2;	400	my ($nodeid, $portid) = split /#/, $port, 2;
355		401
356	$NODE{$noderef} == $NODE{""}	402	$NODE{$nodeid} == $NODE{""}
357	or Carp::croak "$port: rcv can only be called on local ports, caught";	403	or Carp::croak "$port: rcv can only be called on local ports, caught";
358		404
359	while (@_) {	405	while (@_) {
360	if (ref $_[0]) {	406	if (ref $_[0]) {
361	if (my $self = $PORT_DATA{$portid}) {	407	if (my $self = $PORT_DATA{$portid}) {
362	"AnyEvent::MP::Port" eq ref $self	408	"AnyEvent::MP::Port" eq ref $self
363	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	409	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
364		410
365	$self->[2] = shift;	411	$self->[0] = shift;
366	} else {	412	} else {
367	my $cb = shift;	413	my $cb = shift;
368	$PORT{$portid} = sub {	414	$PORT{$portid} = sub {
369	local $SELF = $port;	415	local $SELF = $port;
370	eval { &$cb }; _self_die if $@;	416	eval { &$cb }; _self_die if $@;
371	};	417	};
372	}	418	}
373	} elsif (defined $_[0]) {	419	} elsif (defined $_[0]) {
374	my $self = $PORT_DATA{$portid} \|\|= do {	420	my $self = $PORT_DATA{$portid} \|\|= do {
375	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	421	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
376		422
377	$PORT{$portid} = sub {	423	$PORT{$portid} = sub {
378	local $SELF = $port;	424	local $SELF = $port;
379		425
380	if (my $cb = $self->[1]{$_[0]}) {	426	if (my $cb = $self->[1]{$_[0]}) {
…		…
402	}	448	}
403		449
404	$port	450	$port
405	}	451	}
406		452
		453	=item peval $port, $coderef[, @args]
		454
		455	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
		456	when the code throews an exception the C<$port> will be killed.
		457
		458	Any remaining args will be passed to the callback. Any return values will
		459	be returned to the caller.
		460
		461	This is useful when you temporarily want to execute code in the context of
		462	a port.
		463
		464	Example: create a port and run some initialisation code in it's context.
		465
		466	my $port = port { ... };
		467
		468	peval $port, sub {
		469	init
		470	or die "unable to init";
		471	};
		472
		473	=cut
		474
		475	sub peval($$) {
		476	local $SELF = shift;
		477	my $cb = shift;
		478
		479	if (wantarray) {
		480	my @res = eval { &$cb };
		481	_self_die if $@;
		482	@res
		483	} else {
		484	my $res = eval { &$cb };
		485	_self_die if $@;
		486	$res
		487	}
		488	}
		489
407	=item $closure = psub { BLOCK }	490	=item $closure = psub { BLOCK }
408		491
409	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	492	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
410	closure is executed, sets up the environment in the same way as in C<rcv>	493	closure is executed, sets up the environment in the same way as in C<rcv>
411	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.	494	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		495
		496	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		497	BLOCK } } >>.
412		498
413	This is useful when you register callbacks from C<rcv> callbacks:	499	This is useful when you register callbacks from C<rcv> callbacks:
414		500
415	rcv delayed_reply => sub {	501	rcv delayed_reply => sub {
416	my ($delay, @reply) = @_;	502	my ($delay, @reply) = @_;
…		…
452		538
453	Monitor the given port and do something when the port is killed or	539	Monitor the given port and do something when the port is killed or
454	messages to it were lost, and optionally return a guard that can be used	540	messages to it were lost, and optionally return a guard that can be used
455	to stop monitoring again.	541	to stop monitoring again.
456		542
		543	In the first form (callback), the callback is simply called with any
		544	number of C<@reason> elements (no @reason means that the port was deleted
		545	"normally"). Note also that I<< the callback B<must> never die >>, so use
		546	C<eval> if unsure.
		547
		548	In the second form (another port given), the other port (C<$rcvport>)
		549	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
		550	"normal" kils nothing happens, while under all other conditions, the other
		551	port is killed with the same reason.
		552
		553	The third form (kill self) is the same as the second form, except that
		554	C<$rvport> defaults to C<$SELF>.
		555
		556	In the last form (message), a message of the form C<@msg, @reason> will be
		557	C<snd>.
		558
		559	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		560	alert was raised), they are removed and will not trigger again.
		561
		562	As a rule of thumb, monitoring requests should always monitor a port from
		563	a local port (or callback). The reason is that kill messages might get
		564	lost, just like any other message. Another less obvious reason is that
		565	even monitoring requests can get lost (for example, when the connection
		566	to the other node goes down permanently). When monitoring a port locally
		567	these problems do not exist.
		568
457	C<mon> effectively guarantees that, in the absence of hardware failures,	569	C<mon> effectively guarantees that, in the absence of hardware failures,
458	after starting the monitor, either all messages sent to the port will	570	after starting the monitor, either all messages sent to the port will
459	arrive, or the monitoring action will be invoked after possible message	571	arrive, or the monitoring action will be invoked after possible message
460	loss has been detected. No messages will be lost "in between" (after	572	loss has been detected. No messages will be lost "in between" (after
461	the first lost message no further messages will be received by the	573	the first lost message no further messages will be received by the
462	port). After the monitoring action was invoked, further messages might get	574	port). After the monitoring action was invoked, further messages might get
463	delivered again.	575	delivered again.
464		576
465	Note that monitoring-actions are one-shot: once messages are lost (and a	577	Inter-host-connection timeouts and monitoring depend on the transport
466	monitoring alert was raised), they are removed and will not trigger again.	578	used. The only transport currently implemented is TCP, and AnyEvent::MP
		579	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		580	non-idle connection, and usually around two hours for idle connections).
467		581
468	In the first form (callback), the callback is simply called with any	582	This means that monitoring is good for program errors and cleaning up
469	number of C<@reason> elements (no @reason means that the port was deleted	583	stuff eventually, but they are no replacement for a timeout when you need
470	"normally"). Note also that I<< the callback B<must> never die >>, so use	584	to ensure some maximum latency.
471	C<eval> if unsure.
472
473	In the second form (another port given), the other port (C<$rcvport>)
474	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
475	"normal" kils nothing happens, while under all other conditions, the other
476	port is killed with the same reason.
477
478	The third form (kill self) is the same as the second form, except that
479	C<$rvport> defaults to C<$SELF>.
480
481	In the last form (message), a message of the form C<@msg, @reason> will be
482	C<snd>.
483
484	As a rule of thumb, monitoring requests should always monitor a port from
485	a local port (or callback). The reason is that kill messages might get
486	lost, just like any other message. Another less obvious reason is that
487	even monitoring requests can get lost (for exmaple, when the connection
488	to the other node goes down permanently). When monitoring a port locally
489	these problems do not exist.
490		585
491	Example: call a given callback when C<$port> is killed.	586	Example: call a given callback when C<$port> is killed.
492		587
493	mon $port, sub { warn "port died because of <@_>\n" };	588	mon $port, sub { warn "port died because of <@_>\n" };
494		589
…		…
501	mon $port, $self => "restart";	596	mon $port, $self => "restart";
502		597
503	=cut	598	=cut
504		599
505	sub mon {	600	sub mon {
506	my ($noderef, $port) = split /#/, shift, 2;	601	my ($nodeid, $port) = split /#/, shift, 2;
507		602
508	my $node = $NODE{$noderef} \|\| add_node $noderef;	603	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
509		604
510	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	605	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
511		606
512	unless (ref $cb) {	607	unless (ref $cb) {
513	if (@_) {	608	if (@_) {
…		…
522	}	617	}
523		618
524	$node->monitor ($port, $cb);	619	$node->monitor ($port, $cb);
525		620
526	defined wantarray	621	defined wantarray
527	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	622	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
528	}	623	}
529		624
530	=item $guard = mon_guard $port, $ref, $ref...	625	=item $guard = mon_guard $port, $ref, $ref...
531		626
532	Monitors the given C<$port> and keeps the passed references. When the port	627	Monitors the given C<$port> and keeps the passed references. When the port
…		…
589	the package, then the package above the package and so on (e.g.	684	the package, then the package above the package and so on (e.g.
590	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	685	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
591	exists or it runs out of package names.	686	exists or it runs out of package names.
592		687
593	The init function is then called with the newly-created port as context	688	The init function is then called with the newly-created port as context
594	object (C<$SELF>) and the C<@initdata> values as arguments.	689	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		690	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		691	the port might not get created.
595		692
596	A common idiom is to pass a local port, immediately monitor the spawned	693	A common idiom is to pass a local port, immediately monitor the spawned
597	port, and in the remote init function, immediately monitor the passed	694	port, and in the remote init function, immediately monitor the passed
598	local port. This two-way monitoring ensures that both ports get cleaned up	695	local port. This two-way monitoring ensures that both ports get cleaned up
599	when there is a problem.	696	when there is a problem.
600		697
		698	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		699	caller before C<spawn> returns (by delaying invocation when spawn is
		700	called for the local node).
		701
601	Example: spawn a chat server port on C<$othernode>.	702	Example: spawn a chat server port on C<$othernode>.
602		703
603	# this node, executed from within a port context:	704	# this node, executed from within a port context:
604	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	705	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
605	mon $server;	706	mon $server;
…		…
619		720
620	sub _spawn {	721	sub _spawn {
621	my $port = shift;	722	my $port = shift;
622	my $init = shift;	723	my $init = shift;
623		724
		725	# rcv will create the actual port
624	local $SELF = "$NODE#$port";	726	local $SELF = "$NODE#$port";
625	eval {	727	eval {
626	&{ load_func $init }	728	&{ load_func $init }
627	};	729	};
628	_self_die if $@;	730	_self_die if $@;
629	}	731	}
630		732
631	sub spawn(@) {	733	sub spawn(@) {
632	my ($noderef, undef) = split /#/, shift, 2;	734	my ($nodeid, undef) = split /#/, shift, 2;
633		735
634	my $id = "$RUNIQ." . $ID++;	736	my $id = "$RUNIQ." . $ID++;
635		737
636	$_[0] =~ /::/	738	$_[0] =~ /::/
637	or Carp::croak "spawn init function must be a fully-qualified name, caught";	739	or Carp::croak "spawn init function must be a fully-qualified name, caught";
638		740
639	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	741	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
640		742
641	"$noderef#$id"	743	"$nodeid#$id"
642	}	744	}
643		745
644	=item after $timeout, @msg	746	=item after $timeout, @msg
645		747
646	=item after $timeout, $callback	748	=item after $timeout, $callback
…		…
663	? $action[0]()	765	? $action[0]()
664	: snd @action;	766	: snd @action;
665	};	767	};
666	}	768	}
667		769
		770	=item cal $port, @msg, $callback[, $timeout]
		771
		772	A simple form of RPC - sends a message to the given C<$port> with the
		773	given contents (C<@msg>), but adds a reply port to the message.
		774
		775	The reply port is created temporarily just for the purpose of receiving
		776	the reply, and will be C<kil>ed when no longer needed.
		777
		778	A reply message sent to the port is passed to the C<$callback> as-is.
		779
		780	If an optional time-out (in seconds) is given and it is not C<undef>,
		781	then the callback will be called without any arguments after the time-out
		782	elapsed and the port is C<kil>ed.
		783
		784	If no time-out is given (or it is C<undef>), then the local port will
		785	monitor the remote port instead, so it eventually gets cleaned-up.
		786
		787	Currently this function returns the temporary port, but this "feature"
		788	might go in future versions unless you can make a convincing case that
		789	this is indeed useful for something.
		790
		791	=cut
		792
		793	sub cal(@) {
		794	my $timeout = ref $_[-1] ? undef : pop;
		795	my $cb = pop;
		796
		797	my $port = port {
		798	undef $timeout;
		799	kil $SELF;
		800	&$cb;
		801	};
		802
		803	if (defined $timeout) {
		804	$timeout = AE::timer $timeout, 0, sub {
		805	undef $timeout;
		806	kil $port;
		807	$cb->();
		808	};
		809	} else {
		810	mon $_[0], sub {
		811	kil $port;
		812	$cb->();
		813	};
		814	}
		815
		816	push @_, $port;
		817	&snd;
		818
		819	$port
		820	}
		821
668	=back	822	=back
669		823
670	=head1 AnyEvent::MP vs. Distributed Erlang	824	=head1 AnyEvent::MP vs. Distributed Erlang
671		825
672	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	826	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
673	== aemp node, Erlang process == aemp port), so many of the documents and	827	== aemp node, Erlang process == aemp port), so many of the documents and
674	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	828	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
675	sample:	829	sample:
676		830
677	http://www.Erlang.se/doc/programming_rules.shtml	831	http://www.erlang.se/doc/programming_rules.shtml
678	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	832	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
679	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6	833	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
680	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	834	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
681		835
682	Despite the similarities, there are also some important differences:	836	Despite the similarities, there are also some important differences:
683		837
684	=over 4	838	=over 4
685		839
686	=item * Node IDs are arbitrary strings in AEMP.	840	=item * Node IDs are arbitrary strings in AEMP.
687		841
688	Erlang relies on special naming and DNS to work everywhere in the same	842	Erlang relies on special naming and DNS to work everywhere in the same
689	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by	843	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
690	configuraiton or DNS), but will otherwise discover other odes itself.	844	configuration or DNS), and possibly the addresses of some seed nodes, but
		845	will otherwise discover other nodes (and their IDs) itself.
691		846
692	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	847	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
693	uses "local ports are like remote ports".	848	uses "local ports are like remote ports".
694		849
695	The failure modes for local ports are quite different (runtime errors	850	The failure modes for local ports are quite different (runtime errors
…		…
708		863
709	Erlang uses processes that selectively receive messages, and therefore	864	Erlang uses processes that selectively receive messages, and therefore
710	needs a queue. AEMP is event based, queuing messages would serve no	865	needs a queue. AEMP is event based, queuing messages would serve no
711	useful purpose. For the same reason the pattern-matching abilities of	866	useful purpose. For the same reason the pattern-matching abilities of
712	AnyEvent::MP are more limited, as there is little need to be able to	867	AnyEvent::MP are more limited, as there is little need to be able to
713	filter messages without dequeing them.	868	filter messages without dequeuing them.
714		869
715	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	870	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
716		871
717	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	872	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
718		873
…		…
720	so does not need a queue that can overflow). AEMP sends are immediate,	875	so does not need a queue that can overflow). AEMP sends are immediate,
721	connection establishment is handled in the background.	876	connection establishment is handled in the background.
722		877
723	=item * Erlang suffers from silent message loss, AEMP does not.	878	=item * Erlang suffers from silent message loss, AEMP does not.
724		879
725	Erlang makes few guarantees on messages delivery - messages can get lost	880	Erlang implements few guarantees on messages delivery - messages can get
726	without any of the processes realising it (i.e. you send messages a, b,	881	lost without any of the processes realising it (i.e. you send messages a,
727	and c, and the other side only receives messages a and c).	882	b, and c, and the other side only receives messages a and c).
728		883
729	AEMP guarantees correct ordering, and the guarantee that after one message	884	AEMP guarantees correct ordering, and the guarantee that after one message
730	is lost, all following ones sent to the same port are lost as well, until	885	is lost, all following ones sent to the same port are lost as well, until
731	monitoring raises an error, so there are no silent "holes" in the message	886	monitoring raises an error, so there are no silent "holes" in the message
732	sequence.	887	sequence.
…		…
824	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	979	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
825		980
826	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	981	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
827	your applications.	982	your applications.
828		983
		984	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		985	all nodes.
		986
829	L<AnyEvent>.	987	L<AnyEvent>.
830		988
831	=head1 AUTHOR	989	=head1 AUTHOR
832		990
833	Marc Lehmann <schmorp@schmorp.de>	991	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.70 by root, Sun Aug 30 19:49:47 2009 UTC vs.
Revision 1.103 by root, Sat Oct 17 01:42:39 2009 UTC