[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 1.119 by root, Sun Feb 26 10:29:59 2012 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 port 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
		83	Ports are represented by (printable) strings called "port IDs".
		84
76	=item port ID - C<nodeid#portname>	85	=item port ID - C<nodeid#portname>
77		86
78	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as	87	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
79	separator, and a port name (a printable string of unspecified format).	88	separator, and a port name (a printable string of unspecified format).
80		89
…		…
84	which enables nodes to manage each other remotely, and to create new	93	which enables nodes to manage each other remotely, and to create new
85	ports.	94	ports.
86		95
87	Nodes are either public (have one or more listening ports) or private	96	Nodes are either public (have one or more listening ports) or private
88	(no listening ports). Private nodes cannot talk to other private nodes	97	(no listening ports). Private nodes cannot talk to other private nodes
89	currently.	98	currently, but all nodes can talk to public nodes.
90		99
		100	Nodes is represented by (printable) strings called "node IDs".
		101
91	=item node ID - C<[a-za-Z0-9_\-.:]+>	102	=item node ID - C<[A-Za-z0-9_\-.:]*>
92		103
93	A node ID is a string that uniquely identifies the node within a	104	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	105	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	106	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
96	doesn't interpret node IDs in any way.	107	doesn't interpret node IDs in any way except to uniquely identify a node.
97		108
98	=item binds - C<ip:port>	109	=item binds - C<ip:port>
99		110
100	Nodes can only talk to each other by creating some kind of connection to	111	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	112	each other. To do this, nodes should listen on one or more local transport
		113	endpoints - binds.
		114
102	endpoints - binds. Currently, only standard C<ip:port> specifications can	115	Currently, only standard C<ip:port> specifications can be used, which
103	be used, which specify TCP ports to listen on.	116	specify TCP ports to listen on. So a bind is basically just a tcp socket
		117	in listening mode thta accepts conenctions form other nodes.
104		118
		119	=item seed nodes
		120
		121	When a node starts, it knows nothing about the network it is in - it
		122	needs to connect to at least one other node that is already in the
		123	network. These other nodes are called "seed nodes".
		124
		125	Seed nodes themselves are not special - they are seed nodes only because
		126	some other node I<uses> them as such, but any node can be used as seed
		127	node for other nodes, and eahc node cna use a different set of seed nodes.
		128
		129	In addition to discovering the network, seed nodes are also used to
		130	maintain the network - all nodes using the same seed node form are part of
		131	the same network. If a network is split into multiple subnets because e.g.
		132	the network link between the parts goes down, then using the same seed
		133	nodes for all nodes ensures that eventually the subnets get merged again.
		134
		135	Seed nodes are expected to be long-running, and at least one seed node
		136	should always be available. They should also be relatively responsive - a
		137	seed node that blocks for long periods will slow down everybody else.
		138
		139	For small networks, it's best if every node uses the same set of seed
		140	nodes. For large networks, it can be useful to specify "regional" seed
		141	nodes for most nodes in an area, and use all seed nodes as seed nodes for
		142	each other. What's important is that all seed nodes connections form a
		143	complete graph, so that the network cannot split into separate subnets
		144	forever.
		145
		146	Seed nodes are represented by seed IDs.
		147
105	=item seeds - C<host:port>	148	=item seed IDs - C<host:port>
106		149
107	When a node starts, it knows nothing about the network. To teach the node	150	Seed IDs are transport endpoint(s) (usually a hostname/IP address and a
108	about the network it first has to contact some other node within the	151	TCP port) of nodes that should be used as seed nodes.
109	network. This node is called a seed.
110		152
111	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	153	=item global nodes
112	are expected to be long-running, and at least one of those should always
113	be available. When nodes run out of connections (e.g. due to a network
114	error), they try to re-establish connections to some seednodes again to
115	join the network.
116		154
117	Apart from being sued for seeding, seednodes are not special in any way -	155	An AEMP network needs a discovery service - nodes need to know how to
118	every public node can be a seednode.	156	connect to other nodes they only know by name. In addition, AEMP offers a
		157	distributed "group database", which maps group names to a list of strings
		158	- for example, to register worker ports.
		159
		160	A network needs at least one global node to work, and allows every node to
		161	be a global node.
		162
		163	Any node that loads the L<AnyEvent::MP::Global> module becomes a global
		164	node and tries to keep connections to all other nodes. So while it can
		165	make sense to make every node "global" in small networks, it usually makes
		166	sense to only make seed nodes into global nodes in large networks (nodes
		167	keep connections to seed nodes and global nodes, so makign them the same
		168	reduces overhead).
119		169
120	=back	170	=back
121		171
122	=head1 VARIABLES/FUNCTIONS	172	=head1 VARIABLES/FUNCTIONS
123		173
…		…
135		185
136	use AE ();	186	use AE ();
137		187
138	use base "Exporter";	188	use base "Exporter";
139		189
140	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	190	our $VERSION = '1.30';
141		191
142	our @EXPORT = qw(	192	our @EXPORT = qw(
143	NODE $NODE *SELF node_of after	193	NODE $NODE *SELF node_of after
144	initialise_node	194	configure
145	snd rcv mon mon_guard kil reg psub spawn	195	snd rcv mon mon_guard kil psub peval spawn cal
146	port	196	port
147	);	197	);
148		198
149	our $SELF;	199	our $SELF;
150		200
…		…
156		206
157	=item $thisnode = NODE / $NODE	207	=item $thisnode = NODE / $NODE
158		208
159	The C<NODE> function returns, and the C<$NODE> variable contains, the node	209	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	210	ID of the node running in the current process. This value is initialised by
161	a call to C<initialise_node>.	211	a call to C<configure>.
162		212
163	=item $nodeid = node_of $port	213	=item $nodeid = node_of $port
164		214
165	Extracts and returns the node ID from a port ID or a node ID.	215	Extracts and returns the node ID from a port ID or a node ID.
166		216
167	=item initialise_node $profile_name, key => value...	217	=item configure $profile, key => value...
		218
		219	=item configure key => value...
168		220
169	Before a node can talk to other nodes on the network (i.e. enter	221	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	222	"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	223	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.	224	some other nodes in the network to discover other nodes.
173		225
		226	The key/value pairs are basically the same ones as documented for the
		227	F<aemp> command line utility (sans the set/del prefix).
		228
174	This function initialises a node - it must be called exactly once (or	229	This function configures a node - it must be called exactly once (or
175	never) before calling other AnyEvent::MP functions.	230	never) before calling other AnyEvent::MP functions.
176		231
177	The first argument is a profile name. If it is C<undef> or missing, then	232	=over 4
178	the current nodename will be used instead (i.e. F<uname -n>).
179		233
		234	=item step 1, gathering configuration from profiles
		235
180	The function first looks up the profile in the aemp configuration (see the	236	The function first looks up a profile in the aemp configuration (see the
181	L<aemp> commandline utility). the profile is calculated as follows:	237	L<aemp> commandline utility). The profile name can be specified via the
		238	named C<profile> parameter or can simply be the first parameter). If it is
		239	missing, then the nodename (F<uname -n>) will be used as profile name.
182		240
183	First, all remaining key => value pairs will be used. Then they will be	241	The profile data is then gathered as follows:
184	overwritten by any values specified in the global default configuration	242
185	(see the F<aemp> utility), then the chain of profiles selected, if	243	First, all remaining key => value pairs (all of which are conveniently
		244	undocumented at the moment) will be interpreted as configuration
		245	data. Then they will be overwritten by any values specified in the global
		246	default configuration (see the F<aemp> utility), then the chain of
		247	profiles chosen by the profile name (and any C<parent> attributes).
		248
186	any. That means that the values specified in the profile have highest	249	That means that the values specified in the profile have highest priority
187	priority and the values specified via C<initialise_node> have lowest	250	and the values specified directly via C<configure> have lowest priority,
188	priority.	251	and can only be used to specify defaults.
189		252
190	If the profile specifies a node ID, then this will become the node ID of	253	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	254	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.	255	special node ID of C<anon/> will be replaced by a random node ID.
		256
		257	=item step 2, bind listener sockets
193		258
194	The next step is to look up the binds in the profile, followed by binding	259	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	260	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	261	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	262	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).	263	binds, but it can still talk to all "normal" nodes).
199		264
200	If the profile does not specify a binds list, then the node ID will be	265	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	266	used, meaning the node will bind on a dynamically-assigned port on every
202	used as binds list.	267	local IP address it finds.
203		268
		269	=item step 3, connect to seed nodes
		270
204	Lastly, the seeds list from the profile is passed to the	271	As the last step, the seed ID list from the profile is passed to the
205	L<AnyEvent::MP::Global> module, which will then use it to keep	272	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.	273	connectivity with at least one node at any point in time.
207		274
208	Example: become a distributed node listening on the guessed noderef, or	275	=back
209	the one specified via C<aemp> for the current node. This should be the	276
		277	Example: become a distributed node using the local node name as profile.
210	most common form of invocation for "daemon"-type nodes.	278	This should be the most common form of invocation for "daemon"-type nodes.
211		279
212	initialise_node;	280	configure
213		281
214	Example: become an anonymous node. This form is often used for commandline	282	Example: become an anonymous node. This form is often used for commandline
215	clients.	283	clients.
216		284
217	initialise_node "anon/";	285	configure nodeid => "anon/";
218		286
219	Example: become a distributed node. If there is no profile of the given	287	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	288	for a seed node as it binds on all local addresses on a fixed port (4040,
221	on the resulting addresses.	289	customary for aemp).
222		290
223	initialise_node "localhost:4044";	291	# use the aemp commandline utility
		292	# aemp profile seed nodeid anon/ binds '*:4040'
		293
		294	# then use it
		295	configure profile => "seed";
		296
		297	# or simply use aemp from the shell again:
		298	# aemp run profile seed
		299
		300	# or provide a nicer-to-remember nodeid
		301	# aemp run profile seed nodeid "$(hostname)"
224		302
225	=item $SELF	303	=item $SELF
226		304
227	Contains the current port id while executing C<rcv> callbacks or C<psub>	305	Contains the current port id while executing C<rcv> callbacks or C<psub>
228	blocks.	306	blocks.
…		…
338	msg1 => sub { ... },	416	msg1 => sub { ... },
339	...	417	...
340	;	418	;
341		419
342	Example: temporarily register a rcv callback for a tag matching some port	420	Example: temporarily register a rcv callback for a tag matching some port
343	(e.g. for a rpc reply) and unregister it after a message was received.	421	(e.g. for an rpc reply) and unregister it after a message was received.
344		422
345	rcv $port, $otherport => sub {	423	rcv $port, $otherport => sub {
346	my @reply = @_;	424	my @reply = @_;
347		425
348	rcv $SELF, $otherport;	426	rcv $SELF, $otherport;
…		…
350		428
351	=cut	429	=cut
352		430
353	sub rcv($@) {	431	sub rcv($@) {
354	my $port = shift;	432	my $port = shift;
355	my ($noderef, $portid) = split /#/, $port, 2;	433	my ($nodeid, $portid) = split /#/, $port, 2;
356		434
357	$NODE{$noderef} == $NODE{""}	435	$NODE{$nodeid} == $NODE{""}
358	or Carp::croak "$port: rcv can only be called on local ports, caught";	436	or Carp::croak "$port: rcv can only be called on local ports, caught";
359		437
360	while (@_) {	438	while (@_) {
361	if (ref $_[0]) {	439	if (ref $_[0]) {
362	if (my $self = $PORT_DATA{$portid}) {	440	if (my $self = $PORT_DATA{$portid}) {
363	"AnyEvent::MP::Port" eq ref $self	441	"AnyEvent::MP::Port" eq ref $self
364	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	442	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
365		443
366	$self->[2] = shift;	444	$self->[0] = shift;
367	} else {	445	} else {
368	my $cb = shift;	446	my $cb = shift;
369	$PORT{$portid} = sub {	447	$PORT{$portid} = sub {
370	local $SELF = $port;	448	local $SELF = $port;
371	eval { &$cb }; _self_die if $@;	449	eval { &$cb }; _self_die if $@;
372	};	450	};
373	}	451	}
374	} elsif (defined $_[0]) {	452	} elsif (defined $_[0]) {
375	my $self = $PORT_DATA{$portid} \|\|= do {	453	my $self = $PORT_DATA{$portid} \|\|= do {
376	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	454	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
377		455
378	$PORT{$portid} = sub {	456	$PORT{$portid} = sub {
379	local $SELF = $port;	457	local $SELF = $port;
380		458
381	if (my $cb = $self->[1]{$_[0]}) {	459	if (my $cb = $self->[1]{$_[0]}) {
…		…
403	}	481	}
404		482
405	$port	483	$port
406	}	484	}
407		485
		486	=item peval $port, $coderef[, @args]
		487
		488	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
		489	when the code throews an exception the C<$port> will be killed.
		490
		491	Any remaining args will be passed to the callback. Any return values will
		492	be returned to the caller.
		493
		494	This is useful when you temporarily want to execute code in the context of
		495	a port.
		496
		497	Example: create a port and run some initialisation code in it's context.
		498
		499	my $port = port { ... };
		500
		501	peval $port, sub {
		502	init
		503	or die "unable to init";
		504	};
		505
		506	=cut
		507
		508	sub peval($$) {
		509	local $SELF = shift;
		510	my $cb = shift;
		511
		512	if (wantarray) {
		513	my @res = eval { &$cb };
		514	_self_die if $@;
		515	@res
		516	} else {
		517	my $res = eval { &$cb };
		518	_self_die if $@;
		519	$res
		520	}
		521	}
		522
408	=item $closure = psub { BLOCK }	523	=item $closure = psub { BLOCK }
409		524
410	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	525	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
411	closure is executed, sets up the environment in the same way as in C<rcv>	526	closure is executed, sets up the environment in the same way as in C<rcv>
412	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.	527	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		528
		529	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		530	BLOCK }, @_ } >>.
413		531
414	This is useful when you register callbacks from C<rcv> callbacks:	532	This is useful when you register callbacks from C<rcv> callbacks:
415		533
416	rcv delayed_reply => sub {	534	rcv delayed_reply => sub {
417	my ($delay, @reply) = @_;	535	my ($delay, @reply) = @_;
…		…
453		571
454	Monitor the given port and do something when the port is killed or	572	Monitor the given port and do something when the port is killed or
455	messages to it were lost, and optionally return a guard that can be used	573	messages to it were lost, and optionally return a guard that can be used
456	to stop monitoring again.	574	to stop monitoring again.
457		575
		576	In the first form (callback), the callback is simply called with any
		577	number of C<@reason> elements (no @reason means that the port was deleted
		578	"normally"). Note also that I<< the callback B<must> never die >>, so use
		579	C<eval> if unsure.
		580
		581	In the second form (another port given), the other port (C<$rcvport>)
		582	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
		583	"normal" kils nothing happens, while under all other conditions, the other
		584	port is killed with the same reason.
		585
		586	The third form (kill self) is the same as the second form, except that
		587	C<$rvport> defaults to C<$SELF>.
		588
		589	In the last form (message), a message of the form C<@msg, @reason> will be
		590	C<snd>.
		591
		592	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		593	alert was raised), they are removed and will not trigger again.
		594
		595	As a rule of thumb, monitoring requests should always monitor a port from
		596	a local port (or callback). The reason is that kill messages might get
		597	lost, just like any other message. Another less obvious reason is that
		598	even monitoring requests can get lost (for example, when the connection
		599	to the other node goes down permanently). When monitoring a port locally
		600	these problems do not exist.
		601
458	C<mon> effectively guarantees that, in the absence of hardware failures,	602	C<mon> effectively guarantees that, in the absence of hardware failures,
459	after starting the monitor, either all messages sent to the port will	603	after starting the monitor, either all messages sent to the port will
460	arrive, or the monitoring action will be invoked after possible message	604	arrive, or the monitoring action will be invoked after possible message
461	loss has been detected. No messages will be lost "in between" (after	605	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	606	the first lost message no further messages will be received by the
463	port). After the monitoring action was invoked, further messages might get	607	port). After the monitoring action was invoked, further messages might get
464	delivered again.	608	delivered again.
465		609
466	Note that monitoring-actions are one-shot: once messages are lost (and a	610	Inter-host-connection timeouts and monitoring depend on the transport
467	monitoring alert was raised), they are removed and will not trigger again.	611	used. The only transport currently implemented is TCP, and AnyEvent::MP
		612	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		613	non-idle connection, and usually around two hours for idle connections).
468		614
469	In the first form (callback), the callback is simply called with any	615	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	616	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	617	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<$SELF>.
481
482	In the last form (message), a message of the form C<@msg, @reason> will be
483	C<snd>.
484
485	As a rule of thumb, monitoring requests should always monitor a port from
486	a local port (or callback). The reason is that kill messages might get
487	lost, just like any other message. Another less obvious reason is that
488	even monitoring requests can get lost (for exmaple, when the connection
489	to the other node goes down permanently). When monitoring a port locally
490	these problems do not exist.
491		618
492	Example: call a given callback when C<$port> is killed.	619	Example: call a given callback when C<$port> is killed.
493		620
494	mon $port, sub { warn "port died because of <@_>\n" };	621	mon $port, sub { warn "port died because of <@_>\n" };
495		622
…		…
502	mon $port, $self => "restart";	629	mon $port, $self => "restart";
503		630
504	=cut	631	=cut
505		632
506	sub mon {	633	sub mon {
507	my ($noderef, $port) = split /#/, shift, 2;	634	my ($nodeid, $port) = split /#/, shift, 2;
508		635
509	my $node = $NODE{$noderef} \|\| add_node $noderef;	636	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
510		637
511	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	638	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
512		639
513	unless (ref $cb) {	640	unless (ref $cb) {
514	if (@_) {	641	if (@_) {
…		…
523	}	650	}
524		651
525	$node->monitor ($port, $cb);	652	$node->monitor ($port, $cb);
526		653
527	defined wantarray	654	defined wantarray
528	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	655	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
529	}	656	}
530		657
531	=item $guard = mon_guard $port, $ref, $ref...	658	=item $guard = mon_guard $port, $ref, $ref...
532		659
533	Monitors the given C<$port> and keeps the passed references. When the port	660	Monitors the given C<$port> and keeps the passed references. When the port
…		…
556		683
557	=item kil $port[, @reason]	684	=item kil $port[, @reason]
558		685
559	Kill the specified port with the given C<@reason>.	686	Kill the specified port with the given C<@reason>.
560		687
561	If no C<@reason> is specified, then the port is killed "normally" (ports	688	If no C<@reason> is specified, then the port is killed "normally" -
562	monitoring other ports will not necessarily die because a port dies	689	monitor callback will be invoked, but the kil will not cause linked ports
563	"normally").	690	(C<mon $mport, $lport> form) to get killed.
564		691
565	Otherwise, linked ports get killed with the same reason (second form of	692	If a C<@reason> is specified, then linked ports (C<mon $mport, $lport>
566	C<mon>, see above).	693	form) get killed with the same reason.
567		694
568	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	695	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
569	will be reported as reason C<< die => $@ >>.	696	will be reported as reason C<< die => $@ >>.
570		697
571	Transport/communication errors are reported as C<< transport_error =>	698	Transport/communication errors are reported as C<< transport_error =>
…		…
590	the package, then the package above the package and so on (e.g.	717	the package, then the package above the package and so on (e.g.
591	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	718	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
592	exists or it runs out of package names.	719	exists or it runs out of package names.
593		720
594	The init function is then called with the newly-created port as context	721	The init function is then called with the newly-created port as context
595	object (C<$SELF>) and the C<@initdata> values as arguments.	722	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		723	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		724	the port might not get created.
596		725
597	A common idiom is to pass a local port, immediately monitor the spawned	726	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	727	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	728	local port. This two-way monitoring ensures that both ports get cleaned up
600	when there is a problem.	729	when there is a problem.
601		730
		731	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		732	caller before C<spawn> returns (by delaying invocation when spawn is
		733	called for the local node).
		734
602	Example: spawn a chat server port on C<$othernode>.	735	Example: spawn a chat server port on C<$othernode>.
603		736
604	# this node, executed from within a port context:	737	# this node, executed from within a port context:
605	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	738	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
606	mon $server;	739	mon $server;
…		…
620		753
621	sub _spawn {	754	sub _spawn {
622	my $port = shift;	755	my $port = shift;
623	my $init = shift;	756	my $init = shift;
624		757
		758	# rcv will create the actual port
625	local $SELF = "$NODE#$port";	759	local $SELF = "$NODE#$port";
626	eval {	760	eval {
627	&{ load_func $init }	761	&{ load_func $init }
628	};	762	};
629	_self_die if $@;	763	_self_die if $@;
630	}	764	}
631		765
632	sub spawn(@) {	766	sub spawn(@) {
633	my ($noderef, undef) = split /#/, shift, 2;	767	my ($nodeid, undef) = split /#/, shift, 2;
634		768
635	my $id = "$RUNIQ." . $ID++;	769	my $id = "$RUNIQ." . $ID++;
636		770
637	$_[0] =~ /::/	771	$_[0] =~ /::/
638	or Carp::croak "spawn init function must be a fully-qualified name, caught";	772	or Carp::croak "spawn init function must be a fully-qualified name, caught";
639		773
640	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	774	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
641		775
642	"$noderef#$id"	776	"$nodeid#$id"
643	}	777	}
644		778
645	=item after $timeout, @msg	779	=item after $timeout, @msg
646		780
647	=item after $timeout, $callback	781	=item after $timeout, $callback
…		…
664	? $action[0]()	798	? $action[0]()
665	: snd @action;	799	: snd @action;
666	};	800	};
667	}	801	}
668		802
		803	=item cal $port, @msg, $callback[, $timeout]
		804
		805	A simple form of RPC - sends a message to the given C<$port> with the
		806	given contents (C<@msg>), but adds a reply port to the message.
		807
		808	The reply port is created temporarily just for the purpose of receiving
		809	the reply, and will be C<kil>ed when no longer needed.
		810
		811	A reply message sent to the port is passed to the C<$callback> as-is.
		812
		813	If an optional time-out (in seconds) is given and it is not C<undef>,
		814	then the callback will be called without any arguments after the time-out
		815	elapsed and the port is C<kil>ed.
		816
		817	If no time-out is given (or it is C<undef>), then the local port will
		818	monitor the remote port instead, so it eventually gets cleaned-up.
		819
		820	Currently this function returns the temporary port, but this "feature"
		821	might go in future versions unless you can make a convincing case that
		822	this is indeed useful for something.
		823
		824	=cut
		825
		826	sub cal(@) {
		827	my $timeout = ref $_[-1] ? undef : pop;
		828	my $cb = pop;
		829
		830	my $port = port {
		831	undef $timeout;
		832	kil $SELF;
		833	&$cb;
		834	};
		835
		836	if (defined $timeout) {
		837	$timeout = AE::timer $timeout, 0, sub {
		838	undef $timeout;
		839	kil $port;
		840	$cb->();
		841	};
		842	} else {
		843	mon $_[0], sub {
		844	kil $port;
		845	$cb->();
		846	};
		847	}
		848
		849	push @_, $port;
		850	&snd;
		851
		852	$port
		853	}
		854
669	=back	855	=back
670		856
671	=head1 AnyEvent::MP vs. Distributed Erlang	857	=head1 AnyEvent::MP vs. Distributed Erlang
672		858
673	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	859	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
674	== aemp node, Erlang process == aemp port), so many of the documents and	860	== aemp node, Erlang process == aemp port), so many of the documents and
675	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	861	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
676	sample:	862	sample:
677		863
678	http://www.Erlang.se/doc/programming_rules.shtml	864	http://www.erlang.se/doc/programming_rules.shtml
679	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	865	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
680	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6	866	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
681	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	867	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
682		868
683	Despite the similarities, there are also some important differences:	869	Despite the similarities, there are also some important differences:
684		870
685	=over 4	871	=over 4
686		872
687	=item * Node IDs are arbitrary strings in AEMP.	873	=item * Node IDs are arbitrary strings in AEMP.
688		874
689	Erlang relies on special naming and DNS to work everywhere in the same	875	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	876	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.	877	configuration or DNS), and possibly the addresses of some seed nodes, but
		878	will otherwise discover other nodes (and their IDs) itself.
692		879
693	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	880	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
694	uses "local ports are like remote ports".	881	uses "local ports are like remote ports".
695		882
696	The failure modes for local ports are quite different (runtime errors	883	The failure modes for local ports are quite different (runtime errors
…		…
705	ports being the special case/exception, where transport errors cannot	892	ports being the special case/exception, where transport errors cannot
706	occur.	893	occur.
707		894
708	=item * Erlang uses processes and a mailbox, AEMP does not queue.	895	=item * Erlang uses processes and a mailbox, AEMP does not queue.
709		896
710	Erlang uses processes that selectively receive messages, and therefore	897	Erlang uses processes that selectively receive messages out of order, and
711	needs a queue. AEMP is event based, queuing messages would serve no	898	therefore needs a queue. AEMP is event based, queuing messages would serve
712	useful purpose. For the same reason the pattern-matching abilities of	899	no useful purpose. For the same reason the pattern-matching abilities
713	AnyEvent::MP are more limited, as there is little need to be able to	900	of AnyEvent::MP are more limited, as there is little need to be able to
714	filter messages without dequeing them.	901	filter messages without dequeuing them.
715		902
716	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	903	This is not a philosophical difference, but simply stems from AnyEvent::MP
		904	being event-based, while Erlang is process-based.
		905
		906	You cna have a look at L<Coro::MP> for a more Erlang-like process model on
		907	top of AEMP and Coro threads.
717		908
718	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	909	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
719		910
720	Sending messages in Erlang is synchronous and blocks the process (and	911	Sending messages in Erlang is synchronous and blocks the process until
		912	a conenction has been established and the message sent (and so does not
721	so does not need a queue that can overflow). AEMP sends are immediate,	913	need a queue that can overflow). AEMP sends return immediately, connection
722	connection establishment is handled in the background.	914	establishment is handled in the background.
723		915
724	=item * Erlang suffers from silent message loss, AEMP does not.	916	=item * Erlang suffers from silent message loss, AEMP does not.
725		917
726	Erlang makes few guarantees on messages delivery - messages can get lost	918	Erlang implements few guarantees on messages delivery - messages can get
727	without any of the processes realising it (i.e. you send messages a, b,	919	lost without any of the processes realising it (i.e. you send messages a,
728	and c, and the other side only receives messages a and c).	920	b, and c, and the other side only receives messages a and c).
729		921
730	AEMP guarantees correct ordering, and the guarantee that after one message	922	AEMP guarantees (modulo hardware errors) correct ordering, and the
731	is lost, all following ones sent to the same port are lost as well, until	923	guarantee that after one message is lost, all following ones sent to the
732	monitoring raises an error, so there are no silent "holes" in the message	924	same port are lost as well, until monitoring raises an error, so there are
733	sequence.	925	no silent "holes" in the message sequence.
		926
		927	If you want your software to be very reliable, you have to cope with
		928	corrupted and even out-of-order messages in both Erlang and AEMP. AEMP
		929	simply tries to work better in common error cases, such as when a network
		930	link goes down.
734		931
735	=item * Erlang can send messages to the wrong port, AEMP does not.	932	=item * Erlang can send messages to the wrong port, AEMP does not.
736		933
737	In Erlang it is quite likely that a node that restarts reuses a process ID	934	In Erlang it is quite likely that a node that restarts reuses an Erlang
738	known to other nodes for a completely different process, causing messages	935	process ID known to other nodes for a completely different process,
739	destined for that process to end up in an unrelated process.	936	causing messages destined for that process to end up in an unrelated
		937	process.
740		938
741	AEMP never reuses port IDs, so old messages or old port IDs floating	939	AEMP does not reuse port IDs, so old messages or old port IDs floating
742	around in the network will not be sent to an unrelated port.	940	around in the network will not be sent to an unrelated port.
743		941
744	=item * Erlang uses unprotected connections, AEMP uses secure	942	=item * Erlang uses unprotected connections, AEMP uses secure
745	authentication and can use TLS.	943	authentication and can use TLS.
746		944
…		…
749		947
750	=item * The AEMP protocol is optimised for both text-based and binary	948	=item * The AEMP protocol is optimised for both text-based and binary
751	communications.	949	communications.
752		950
753	The AEMP protocol, unlike the Erlang protocol, supports both programming	951	The AEMP protocol, unlike the Erlang protocol, supports both programming
754	language independent text-only protocols (good for debugging) and binary,	952	language independent text-only protocols (good for debugging), and binary,
755	language-specific serialisers (e.g. Storable). By default, unless TLS is	953	language-specific serialisers (e.g. Storable). By default, unless TLS is
756	used, the protocol is actually completely text-based.	954	used, the protocol is actually completely text-based.
757		955
758	It has also been carefully designed to be implementable in other languages	956	It has also been carefully designed to be implementable in other languages
759	with a minimum of work while gracefully degrading functionality to make the	957	with a minimum of work while gracefully degrading functionality to make the
760	protocol simple.	958	protocol simple.
761		959
762	=item * AEMP has more flexible monitoring options than Erlang.	960	=item * AEMP has more flexible monitoring options than Erlang.
763		961
764	In Erlang, you can chose to receive I<all> exit signals as messages	962	In Erlang, you can chose to receive I<all> exit signals as messages or
765	or I<none>, there is no in-between, so monitoring single processes is	963	I<none>, there is no in-between, so monitoring single Erlang processes is
766	difficult to implement. Monitoring in AEMP is more flexible than in	964	difficult to implement.
767	Erlang, as one can choose between automatic kill, exit message or callback	965
768	on a per-process basis.	966	Monitoring in AEMP is more flexible than in Erlang, as one can choose
		967	between automatic kill, exit message or callback on a per-port basis.
769		968
770	=item * Erlang tries to hide remote/local connections, AEMP does not.	969	=item * Erlang tries to hide remote/local connections, AEMP does not.
771		970
772	Monitoring in Erlang is not an indicator of process death/crashes, in the	971	Monitoring in Erlang is not an indicator of process death/crashes, in the
773	same way as linking is (except linking is unreliable in Erlang).	972	same way as linking is (except linking is unreliable in Erlang).
…		…
795	overhead, as well as having to keep a proxy object everywhere.	994	overhead, as well as having to keep a proxy object everywhere.
796		995
797	Strings can easily be printed, easily serialised etc. and need no special	996	Strings can easily be printed, easily serialised etc. and need no special
798	procedures to be "valid".	997	procedures to be "valid".
799		998
800	And as a result, a miniport consists of a single closure stored in a	999	And as a result, a port with just a default receiver consists of a single
801	global hash - it can't become much cheaper.	1000	code reference stored in a global hash - it can't become much cheaper.
802		1001
803	=item Why favour JSON, why not a real serialising format such as Storable?	1002	=item Why favour JSON, why not a real serialising format such as Storable?
804		1003
805	In fact, any AnyEvent::MP node will happily accept Storable as framing	1004	In fact, any AnyEvent::MP node will happily accept Storable as framing
806	format, but currently there is no way to make a node use Storable by	1005	format, but currently there is no way to make a node use Storable by
…		…
822		1021
823	L<AnyEvent::MP::Intro> - a gentle introduction.	1022	L<AnyEvent::MP::Intro> - a gentle introduction.
824		1023
825	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1024	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
826		1025
827	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1026	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
828	your applications.	1027	your applications.
		1028
		1029	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
		1030
		1031	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		1032	all nodes.
829		1033
830	L<AnyEvent>.	1034	L<AnyEvent>.
831		1035
832	=head1 AUTHOR	1036	=head1 AUTHOR
833		1037

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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 1.119 by root, Sun Feb 26 10:29:59 2012 UTC

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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 1.119 by root, Sun Feb 26 10:29:59 2012 UTC