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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.71 by root, Sun Aug 30 19:52:56 2009 UTC vs.
Revision 1.100 by root, Fri Oct 2 20:41:56 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
36	# monitoring	35	# monitoring
37	mon $port, $cb->(@msg) # callback is invoked on death	36	mon $localport, $cb->(@msg) # callback is invoked on death
38	mon $port, $otherport # kill otherport on abnormal death	37	mon $localport, $otherport # kill otherport on abnormal death
39	mon $port, $otherport, @msg # send message on death	38	mon $localport, $otherport, @msg # send message on death
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 API.
47	AnyEvent::MP::Global - stable API, protocol not yet final.	46	AnyEvent::MP::Global - stable API.
48
49	stay tuned.
50		47
51	=head1 DESCRIPTION	48	=head1 DESCRIPTION
52		49
53	This module (-family) implements a simple message passing framework.	50	This module (-family) implements a simple message passing framework.
54		51
56	on the same or other hosts, and you can supervise entities remotely.	53	on the same or other hosts, and you can supervise entities remotely.
57		54
58	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	55	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
59	manual page and the examples under F<eg/>.	56	manual page and the examples under F<eg/>.
60		57
61	At the moment, this module family is a bit underdocumented.
62
63	=head1 CONCEPTS	58	=head1 CONCEPTS
64		59
65	=over 4	60	=over 4
66		61
67	=item port	62	=item port
68		63
69	A port is something you can send messages to (with the C<snd> function).	64	Not to be confused with a TCP port, a "port" is something you can send
		65	messages to (with the C<snd> function).
70		66
71	Ports allow you to register C<rcv> handlers that can match all or just	67	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	68	some messages. Messages send to ports will not be queued, regardless of
73	anything was listening for them or not.	69	anything was listening for them or not.
74		70
…		…
85		81
86	Nodes are either public (have one or more listening ports) or private	82	Nodes are either public (have one or more listening ports) or private
87	(no listening ports). Private nodes cannot talk to other private nodes	83	(no listening ports). Private nodes cannot talk to other private nodes
88	currently.	84	currently.
89		85
90	=item node ID - C<[a-za-Z0-9_\-.:]+>	86	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
91		87
92	A node ID is a string that uniquely identifies the node within a	88	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	89	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	90	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
95	doesn't interpret node IDs in any way.	91	doesn't interpret node IDs in any way.
…		…
99	Nodes can only talk to each other by creating some kind of connection to	95	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	96	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	97	endpoints - binds. Currently, only standard C<ip:port> specifications can
102	be used, which specify TCP ports to listen on.	98	be used, which specify TCP ports to listen on.
103		99
104	=item seeds - C<host:port>	100	=item seed nodes
105		101
106	When a node starts, it knows nothing about the network. To teach the node	102	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	103	about the network it first has to contact some other node within the
108	network. This node is called a seed.	104	network. This node is called a seed.
109		105
110	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	106	Apart from the fact that other nodes know them as seed nodes and they have
		107	to have fixed listening addresses, seed nodes are perfectly normal nodes -
		108	any node can function as a seed node for others.
		109
		110	In addition to discovering the network, seed nodes are also used to
		111	maintain the network and to connect nodes that otherwise would have
		112	trouble connecting. They form the backbone of an AnyEvent::MP network.
		113
111	are expected to be long-running, and at least one of those should always	114	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	115	should always be available. They should also be relatively responsive - a
113	error), they try to re-establish connections to some seednodes again to	116	seed node that blocks for long periods will slow down everybody else.
114	join the network.
115		117
116	Apart from being sued for seeding, seednodes are not special in any way -	118	=item seeds - C<host:port>
117	every public node can be a seednode.	119
		120	Seeds are transport endpoint(s) (usually a hostname/IP address and a
		121	TCP port) of nodes that should be used as seed nodes.
		122
		123	The nodes listening on those endpoints are expected to be long-running,
		124	and at least one of those should always be available. When nodes run out
		125	of connections (e.g. due to a network error), they try to re-establish
		126	connections to some seednodes again to join the network.
118		127
119	=back	128	=back
120		129
121	=head1 VARIABLES/FUNCTIONS	130	=head1 VARIABLES/FUNCTIONS
122		131
…		…
134		143
135	use AE ();	144	use AE ();
136		145
137	use base "Exporter";	146	use base "Exporter";
138		147
139	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	148	our $VERSION = 1.21;
140		149
141	our @EXPORT = qw(	150	our @EXPORT = qw(
142	NODE $NODE *SELF node_of after	151	NODE $NODE *SELF node_of after
143	initialise_node	152	configure
144	snd rcv mon mon_guard kil reg psub spawn	153	snd rcv mon mon_guard kil psub spawn cal
145	port	154	port
146	);	155	);
147		156
148	our $SELF;	157	our $SELF;
149		158
…		…
155		164
156	=item $thisnode = NODE / $NODE	165	=item $thisnode = NODE / $NODE
157		166
158	The C<NODE> function returns, and the C<$NODE> variable contains, the node	167	The C<NODE> function returns, and the C<$NODE> variable contains, the node
159	ID of the node running in the current process. This value is initialised by	168	ID of the node running in the current process. This value is initialised by
160	a call to C<initialise_node>.	169	a call to C<configure>.
161		170
162	=item $nodeid = node_of $port	171	=item $nodeid = node_of $port
163		172
164	Extracts and returns the node ID from a port ID or a node ID.	173	Extracts and returns the node ID from a port ID or a node ID.
165		174
166	=item initialise_node $profile_name, key => value...	175	=item configure $profile, key => value...
		176
		177	=item configure key => value...
167		178
168	Before a node can talk to other nodes on the network (i.e. enter	179	Before a node can talk to other nodes on the network (i.e. enter
169	"distributed mode") it has to initialise itself - the minimum a node needs	180	"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	181	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.	182	some other nodes in the network to discover other nodes.
172		183
173	This function initialises a node - it must be called exactly once (or	184	This function configures a node - it must be called exactly once (or
174	never) before calling other AnyEvent::MP functions.	185	never) before calling other AnyEvent::MP functions.
175		186
176	The first argument is a profile name. If it is C<undef> or missing, then	187	=over 4
177	the current nodename will be used instead (i.e. F<uname -n>).
178		188
		189	=item step 1, gathering configuration from profiles
		190
179	The function first looks up the profile in the aemp configuration (see the	191	The function first looks up a profile in the aemp configuration (see the
180	L<aemp> commandline utility). the profile is calculated as follows:	192	L<aemp> commandline utility). The profile name can be specified via the
		193	named C<profile> parameter or can simply be the first parameter). If it is
		194	missing, then the nodename (F<uname -n>) will be used as profile name.
181		195
		196	The profile data is then gathered as follows:
		197
182	First, all remaining key => value pairs (all of which are conviniently	198	First, all remaining key => value pairs (all of which are conveniently
183	undocumented at the moment) will be used. Then they will be overwritten by	199	undocumented at the moment) will be interpreted as configuration
184	any values specified in the global default configuration (see the F<aemp>	200	data. Then they will be overwritten by any values specified in the global
185	utility), then the chain of profiles selected, if any. That means that	201	default configuration (see the F<aemp> utility), then the chain of
		202	profiles chosen by the profile name (and any C<parent> attributes).
		203
186	the values specified in the profile have highest priority and the values	204	That means that the values specified in the profile have highest priority
187	specified via C<initialise_node> have lowest priority.	205	and the values specified directly via C<configure> have lowest priority,
		206	and can only be used to specify defaults.
188		207
189	If the profile specifies a node ID, then this will become the node ID of	208	If the profile specifies a node ID, then this will become the node ID of
190	this process. If not, then the profile name will be used as node ID. The	209	this process. If not, then the profile name will be used as node ID. The
191	special node ID of C<anon/> will be replaced by a random node ID.	210	special node ID of C<anon/> will be replaced by a random node ID.
		211
		212	=item step 2, bind listener sockets
192		213
193	The next step is to look up the binds in the profile, followed by binding	214	The next step is to look up the binds in the profile, followed by binding
194	aemp protocol listeners on all binds specified (it is possible and valid	215	aemp protocol listeners on all binds specified (it is possible and valid
195	to have no binds, meaning that the node cannot be contacted form the	216	to have no binds, meaning that the node cannot be contacted form the
196	outside. This means the node cannot talk to other nodes that also have no	217	outside. This means the node cannot talk to other nodes that also have no
197	binds, but it can still talk to all "normal" nodes).	218	binds, but it can still talk to all "normal" nodes).
198		219
199	If the profile does not specify a binds list, then a default of C<*> is	220	If the profile does not specify a binds list, then a default of C<*> is
200	used.	221	used, meaning the node will bind on a dynamically-assigned port on every
		222	local IP address it finds.
201		223
		224	=item step 3, connect to seed nodes
		225
202	Lastly, the seeds list from the profile is passed to the	226	As the last step, the seeds list from the profile is passed to the
203	L<AnyEvent::MP::Global> module, which will then use it to keep	227	L<AnyEvent::MP::Global> module, which will then use it to keep
204	connectivity with at least on of those seed nodes at any point in time.	228	connectivity with at least one node at any point in time.
205		229
206	Example: become a distributed node listening on the guessed noderef, or	230	=back
207	the one specified via C<aemp> for the current node. This should be the	231
		232	Example: become a distributed node using the local node name as profile.
208	most common form of invocation for "daemon"-type nodes.	233	This should be the most common form of invocation for "daemon"-type nodes.
209		234
210	initialise_node;	235	configure
211		236
212	Example: become an anonymous node. This form is often used for commandline	237	Example: become an anonymous node. This form is often used for commandline
213	clients.	238	clients.
214		239
215	initialise_node "anon/";	240	configure nodeid => "anon/";
216		241
217	Example: become a distributed node. If there is no profile of the given	242	Example: configure a node using a profile called seed, which si suitable
218	name, or no binds list was specified, resolve C<localhost:4044> and bind	243	for a seed node as it binds on all local addresses on a fixed port (4040,
219	on the resulting addresses.	244	customary for aemp).
220		245
221	initialise_node "localhost:4044";	246	# use the aemp commandline utility
		247	# aemp profile seed nodeid anon/ binds '*:4040'
		248
		249	# then use it
		250	configure profile => "seed";
		251
		252	# or simply use aemp from the shell again:
		253	# aemp run profile seed
		254
		255	# or provide a nicer-to-remember nodeid
		256	# aemp run profile seed nodeid "$(hostname)"
222		257
223	=item $SELF	258	=item $SELF
224		259
225	Contains the current port id while executing C<rcv> callbacks or C<psub>	260	Contains the current port id while executing C<rcv> callbacks or C<psub>
226	blocks.	261	blocks.
…		…
348		383
349	=cut	384	=cut
350		385
351	sub rcv($@) {	386	sub rcv($@) {
352	my $port = shift;	387	my $port = shift;
353	my ($noderef, $portid) = split /#/, $port, 2;	388	my ($nodeid, $portid) = split /#/, $port, 2;
354		389
355	$NODE{$noderef} == $NODE{""}	390	$NODE{$nodeid} == $NODE{""}
356	or Carp::croak "$port: rcv can only be called on local ports, caught";	391	or Carp::croak "$port: rcv can only be called on local ports, caught";
357		392
358	while (@_) {	393	while (@_) {
359	if (ref $_[0]) {	394	if (ref $_[0]) {
360	if (my $self = $PORT_DATA{$portid}) {	395	if (my $self = $PORT_DATA{$portid}) {
…		…
451		486
452	Monitor the given port and do something when the port is killed or	487	Monitor the given port and do something when the port is killed or
453	messages to it were lost, and optionally return a guard that can be used	488	messages to it were lost, and optionally return a guard that can be used
454	to stop monitoring again.	489	to stop monitoring again.
455		490
		491	In the first form (callback), the callback is simply called with any
		492	number of C<@reason> elements (no @reason means that the port was deleted
		493	"normally"). Note also that I<< the callback B<must> never die >>, so use
		494	C<eval> if unsure.
		495
		496	In the second form (another port given), the other port (C<$rcvport>)
		497	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
		498	"normal" kils nothing happens, while under all other conditions, the other
		499	port is killed with the same reason.
		500
		501	The third form (kill self) is the same as the second form, except that
		502	C<$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	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		508	alert was raised), they are removed and will not trigger again.
		509
		510	As a rule of thumb, monitoring requests should always monitor a port from
		511	a local port (or callback). The reason is that kill messages might get
		512	lost, just like any other message. Another less obvious reason is that
		513	even monitoring requests can get lost (for example, when the connection
		514	to the other node goes down permanently). When monitoring a port locally
		515	these problems do not exist.
		516
456	C<mon> effectively guarantees that, in the absence of hardware failures,	517	C<mon> effectively guarantees that, in the absence of hardware failures,
457	after starting the monitor, either all messages sent to the port will	518	after starting the monitor, either all messages sent to the port will
458	arrive, or the monitoring action will be invoked after possible message	519	arrive, or the monitoring action will be invoked after possible message
459	loss has been detected. No messages will be lost "in between" (after	520	loss has been detected. No messages will be lost "in between" (after
460	the first lost message no further messages will be received by the	521	the first lost message no further messages will be received by the
461	port). After the monitoring action was invoked, further messages might get	522	port). After the monitoring action was invoked, further messages might get
462	delivered again.	523	delivered again.
463		524
464	Note that monitoring-actions are one-shot: once messages are lost (and a	525	Inter-host-connection timeouts and monitoring depend on the transport
465	monitoring alert was raised), they are removed and will not trigger again.	526	used. The only transport currently implemented is TCP, and AnyEvent::MP
		527	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		528	non-idle connection, and usually around two hours for idle connections).
466		529
467	In the first form (callback), the callback is simply called with any	530	This means that monitoring is good for program errors and cleaning up
468	number of C<@reason> elements (no @reason means that the port was deleted	531	stuff eventually, but they are no replacement for a timeout when you need
469	"normally"). Note also that I<< the callback B<must> never die >>, so use	532	to ensure some maximum latency.
470	C<eval> if unsure.
471
472	In the second form (another port given), the other port (C<$rcvport>)
473	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
474	"normal" kils nothing happens, while under all other conditions, the other
475	port is killed with the same reason.
476
477	The third form (kill self) is the same as the second form, except that
478	C<$rvport> defaults to C<$SELF>.
479
480	In the last form (message), a message of the form C<@msg, @reason> will be
481	C<snd>.
482
483	As a rule of thumb, monitoring requests should always monitor a port from
484	a local port (or callback). The reason is that kill messages might get
485	lost, just like any other message. Another less obvious reason is that
486	even monitoring requests can get lost (for exmaple, when the connection
487	to the other node goes down permanently). When monitoring a port locally
488	these problems do not exist.
489		533
490	Example: call a given callback when C<$port> is killed.	534	Example: call a given callback when C<$port> is killed.
491		535
492	mon $port, sub { warn "port died because of <@_>\n" };	536	mon $port, sub { warn "port died because of <@_>\n" };
493		537
…		…
500	mon $port, $self => "restart";	544	mon $port, $self => "restart";
501		545
502	=cut	546	=cut
503		547
504	sub mon {	548	sub mon {
505	my ($noderef, $port) = split /#/, shift, 2;	549	my ($nodeid, $port) = split /#/, shift, 2;
506		550
507	my $node = $NODE{$noderef} \|\| add_node $noderef;	551	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
508		552
509	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	553	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
510		554
511	unless (ref $cb) {	555	unless (ref $cb) {
512	if (@_) {	556	if (@_) {
…		…
521	}	565	}
522		566
523	$node->monitor ($port, $cb);	567	$node->monitor ($port, $cb);
524		568
525	defined wantarray	569	defined wantarray
526	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	570	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
527	}	571	}
528		572
529	=item $guard = mon_guard $port, $ref, $ref...	573	=item $guard = mon_guard $port, $ref, $ref...
530		574
531	Monitors the given C<$port> and keeps the passed references. When the port	575	Monitors the given C<$port> and keeps the passed references. When the port
…		…
588	the package, then the package above the package and so on (e.g.	632	the package, then the package above the package and so on (e.g.
589	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	633	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
590	exists or it runs out of package names.	634	exists or it runs out of package names.
591		635
592	The init function is then called with the newly-created port as context	636	The init function is then called with the newly-created port as context
593	object (C<$SELF>) and the C<@initdata> values as arguments.	637	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		638	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		639	the port might not get created.
594		640
595	A common idiom is to pass a local port, immediately monitor the spawned	641	A common idiom is to pass a local port, immediately monitor the spawned
596	port, and in the remote init function, immediately monitor the passed	642	port, and in the remote init function, immediately monitor the passed
597	local port. This two-way monitoring ensures that both ports get cleaned up	643	local port. This two-way monitoring ensures that both ports get cleaned up
598	when there is a problem.	644	when there is a problem.
599		645
		646	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		647	caller before C<spawn> returns (by delaying invocation when spawn is
		648	called for the local node).
		649
600	Example: spawn a chat server port on C<$othernode>.	650	Example: spawn a chat server port on C<$othernode>.
601		651
602	# this node, executed from within a port context:	652	# this node, executed from within a port context:
603	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	653	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
604	mon $server;	654	mon $server;
…		…
618		668
619	sub _spawn {	669	sub _spawn {
620	my $port = shift;	670	my $port = shift;
621	my $init = shift;	671	my $init = shift;
622		672
		673	# rcv will create the actual port
623	local $SELF = "$NODE#$port";	674	local $SELF = "$NODE#$port";
624	eval {	675	eval {
625	&{ load_func $init }	676	&{ load_func $init }
626	};	677	};
627	_self_die if $@;	678	_self_die if $@;
628	}	679	}
629		680
630	sub spawn(@) {	681	sub spawn(@) {
631	my ($noderef, undef) = split /#/, shift, 2;	682	my ($nodeid, undef) = split /#/, shift, 2;
632		683
633	my $id = "$RUNIQ." . $ID++;	684	my $id = "$RUNIQ." . $ID++;
634		685
635	$_[0] =~ /::/	686	$_[0] =~ /::/
636	or Carp::croak "spawn init function must be a fully-qualified name, caught";	687	or Carp::croak "spawn init function must be a fully-qualified name, caught";
637		688
638	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	689	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
639		690
640	"$noderef#$id"	691	"$nodeid#$id"
641	}	692	}
642		693
643	=item after $timeout, @msg	694	=item after $timeout, @msg
644		695
645	=item after $timeout, $callback	696	=item after $timeout, $callback
…		…
662	? $action[0]()	713	? $action[0]()
663	: snd @action;	714	: snd @action;
664	};	715	};
665	}	716	}
666		717
		718	=item cal $port, @msg, $callback[, $timeout]
		719
		720	A simple form of RPC - sends a message to the given C<$port> with the
		721	given contents (C<@msg>), but adds a reply port to the message.
		722
		723	The reply port is created temporarily just for the purpose of receiving
		724	the reply, and will be C<kil>ed when no longer needed.
		725
		726	A reply message sent to the port is passed to the C<$callback> as-is.
		727
		728	If an optional time-out (in seconds) is given and it is not C<undef>,
		729	then the callback will be called without any arguments after the time-out
		730	elapsed and the port is C<kil>ed.
		731
		732	If no time-out is given (or it is C<undef>), then the local port will
		733	monitor the remote port instead, so it eventually gets cleaned-up.
		734
		735	Currently this function returns the temporary port, but this "feature"
		736	might go in future versions unless you can make a convincing case that
		737	this is indeed useful for something.
		738
		739	=cut
		740
		741	sub cal(@) {
		742	my $timeout = ref $_[-1] ? undef : pop;
		743	my $cb = pop;
		744
		745	my $port = port {
		746	undef $timeout;
		747	kil $SELF;
		748	&$cb;
		749	};
		750
		751	if (defined $timeout) {
		752	$timeout = AE::timer $timeout, 0, sub {
		753	undef $timeout;
		754	kil $port;
		755	$cb->();
		756	};
		757	} else {
		758	mon $_[0], sub {
		759	kil $port;
		760	$cb->();
		761	};
		762	}
		763
		764	push @_, $port;
		765	&snd;
		766
		767	$port
		768	}
		769
667	=back	770	=back
668		771
669	=head1 AnyEvent::MP vs. Distributed Erlang	772	=head1 AnyEvent::MP vs. Distributed Erlang
670		773
671	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	774	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
672	== aemp node, Erlang process == aemp port), so many of the documents and	775	== aemp node, Erlang process == aemp port), so many of the documents and
673	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	776	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
674	sample:	777	sample:
675		778
676	http://www.Erlang.se/doc/programming_rules.shtml	779	http://www.erlang.se/doc/programming_rules.shtml
677	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	780	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
678	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6	781	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
679	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	782	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
680		783
681	Despite the similarities, there are also some important differences:	784	Despite the similarities, there are also some important differences:
682		785
683	=over 4	786	=over 4
684		787
685	=item * Node IDs are arbitrary strings in AEMP.	788	=item * Node IDs are arbitrary strings in AEMP.
686		789
687	Erlang relies on special naming and DNS to work everywhere in the same	790	Erlang relies on special naming and DNS to work everywhere in the same
688	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by	791	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
689	configuraiton or DNS), but will otherwise discover other odes itself.	792	configuration or DNS), and possibly the addresses of some seed nodes, but
		793	will otherwise discover other nodes (and their IDs) itself.
690		794
691	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	795	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
692	uses "local ports are like remote ports".	796	uses "local ports are like remote ports".
693		797
694	The failure modes for local ports are quite different (runtime errors	798	The failure modes for local ports are quite different (runtime errors
…		…
707		811
708	Erlang uses processes that selectively receive messages, and therefore	812	Erlang uses processes that selectively receive messages, and therefore
709	needs a queue. AEMP is event based, queuing messages would serve no	813	needs a queue. AEMP is event based, queuing messages would serve no
710	useful purpose. For the same reason the pattern-matching abilities of	814	useful purpose. For the same reason the pattern-matching abilities of
711	AnyEvent::MP are more limited, as there is little need to be able to	815	AnyEvent::MP are more limited, as there is little need to be able to
712	filter messages without dequeing them.	816	filter messages without dequeuing them.
713		817
714	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	818	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
715		819
716	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	820	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
717		821
…		…
719	so does not need a queue that can overflow). AEMP sends are immediate,	823	so does not need a queue that can overflow). AEMP sends are immediate,
720	connection establishment is handled in the background.	824	connection establishment is handled in the background.
721		825
722	=item * Erlang suffers from silent message loss, AEMP does not.	826	=item * Erlang suffers from silent message loss, AEMP does not.
723		827
724	Erlang makes few guarantees on messages delivery - messages can get lost	828	Erlang implements few guarantees on messages delivery - messages can get
725	without any of the processes realising it (i.e. you send messages a, b,	829	lost without any of the processes realising it (i.e. you send messages a,
726	and c, and the other side only receives messages a and c).	830	b, and c, and the other side only receives messages a and c).
727		831
728	AEMP guarantees correct ordering, and the guarantee that after one message	832	AEMP guarantees correct ordering, and the guarantee that after one message
729	is lost, all following ones sent to the same port are lost as well, until	833	is lost, all following ones sent to the same port are lost as well, until
730	monitoring raises an error, so there are no silent "holes" in the message	834	monitoring raises an error, so there are no silent "holes" in the message
731	sequence.	835	sequence.
…		…
823	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	927	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
824		928
825	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	929	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
826	your applications.	930	your applications.
827		931
		932	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		933	all nodes.
		934
828	L<AnyEvent>.	935	L<AnyEvent>.
829		936
830	=head1 AUTHOR	937	=head1 AUTHOR
831		938
832	Marc Lehmann <schmorp@schmorp.de>	939	Marc Lehmann <schmorp@schmorp.de>

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Revision 1.71 by root, Sun Aug 30 19:52:56 2009 UTC vs.
Revision 1.100 by root, Fri Oct 2 20:41:56 2009 UTC