[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 1.119 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
		241	The profile data is then gathered as follows:
		242
183	First, all remaining key => value pairs (all of which are conviniently	243	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	244	undocumented at the moment) will be interpreted as configuration
185	any values specified in the global default configuration (see the F<aemp>	245	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	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
187	the values specified in the profile have highest priority and the values	249	That means that the values specified in the profile have highest priority
188	specified via C<initialise_node> have lowest priority.	250	and the values specified directly via C<configure> have lowest 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 a default of C<*> is	265	If the profile does not specify a binds list, then a default of C<*> is
201	used.	266	used, meaning the node will bind on a dynamically-assigned port on every
		267	local IP address it finds.
202		268
		269	=item step 3, connect to seed nodes
		270
203	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
204	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
205	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.
206		274
207	Example: become a distributed node listening on the guessed noderef, or	275	=back
208	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.
209	most common form of invocation for "daemon"-type nodes.	278	This should be the most common form of invocation for "daemon"-type nodes.
210		279
211	initialise_node;	280	configure
212		281
213	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
214	clients.	283	clients.
215		284
216	initialise_node "anon/";	285	configure nodeid => "anon/";
217		286
218	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
219	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,
220	on the resulting addresses.	289	customary for aemp).
221		290
222	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)"
223		302
224	=item $SELF	303	=item $SELF
225		304
226	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>
227	blocks.	306	blocks.
…		…
337	msg1 => sub { ... },	416	msg1 => sub { ... },
338	...	417	...
339	;	418	;
340		419
341	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
342	(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.
343		422
344	rcv $port, $otherport => sub {	423	rcv $port, $otherport => sub {
345	my @reply = @_;	424	my @reply = @_;
346		425
347	rcv $SELF, $otherport;	426	rcv $SELF, $otherport;
…		…
349		428
350	=cut	429	=cut
351		430
352	sub rcv($@) {	431	sub rcv($@) {
353	my $port = shift;	432	my $port = shift;
354	my ($noderef, $portid) = split /#/, $port, 2;	433	my ($nodeid, $portid) = split /#/, $port, 2;
355		434
356	$NODE{$noderef} == $NODE{""}	435	$NODE{$nodeid} == $NODE{""}
357	or Carp::croak "$port: rcv can only be called on local ports, caught";	436	or Carp::croak "$port: rcv can only be called on local ports, caught";
358		437
359	while (@_) {	438	while (@_) {
360	if (ref $_[0]) {	439	if (ref $_[0]) {
361	if (my $self = $PORT_DATA{$portid}) {	440	if (my $self = $PORT_DATA{$portid}) {
362	"AnyEvent::MP::Port" eq ref $self	441	"AnyEvent::MP::Port" eq ref $self
363	or Carp::croak "$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";
364		443
365	$self->[2] = shift;	444	$self->[0] = shift;
366	} else {	445	} else {
367	my $cb = shift;	446	my $cb = shift;
368	$PORT{$portid} = sub {	447	$PORT{$portid} = sub {
369	local $SELF = $port;	448	local $SELF = $port;
370	eval { &$cb }; _self_die if $@;	449	eval { &$cb }; _self_die if $@;
371	};	450	};
372	}	451	}
373	} elsif (defined $_[0]) {	452	} elsif (defined $_[0]) {
374	my $self = $PORT_DATA{$portid} \|\|= do {	453	my $self = $PORT_DATA{$portid} \|\|= do {
375	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	454	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
376		455
377	$PORT{$portid} = sub {	456	$PORT{$portid} = sub {
378	local $SELF = $port;	457	local $SELF = $port;
379		458
380	if (my $cb = $self->[1]{$_[0]}) {	459	if (my $cb = $self->[1]{$_[0]}) {
…		…
402	}	481	}
403		482
404	$port	483	$port
405	}	484	}
406		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
407	=item $closure = psub { BLOCK }	523	=item $closure = psub { BLOCK }
408		524
409	Remembers C<$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
410	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>
411	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 $SELF, sub {
		530	BLOCK }, @_ } >>.
412		531
413	This is useful when you register callbacks from C<rcv> callbacks:	532	This is useful when you register callbacks from C<rcv> callbacks:
414		533
415	rcv delayed_reply => sub {	534	rcv delayed_reply => sub {
416	my ($delay, @reply) = @_;	535	my ($delay, @reply) = @_;
…		…
452		571
453	Monitor the given port and do something when the port is killed or	572	Monitor the given port and do something when the port is killed or
454	messages to it were lost, and optionally return a guard that can be used	573	messages to it were lost, and optionally return a guard that can be used
455	to stop monitoring again.	574	to stop monitoring again.
456		575
		576	In the first form (callback), the callback is simply called with any
		577	number of C<@reason> elements (no @reason means that the port was deleted
		578	"normally"). Note also that I<< the callback B<must> never die >>, so use
		579	C<eval> if unsure.
		580
		581	In the second form (another port given), the other port (C<$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
457	C<mon> effectively guarantees that, in the absence of hardware failures,	602	C<mon> effectively guarantees that, in the absence of hardware failures,
458	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
459	arrive, or the monitoring action will be invoked after possible message	604	arrive, or the monitoring action will be invoked after possible message
460	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
461	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
462	port). After the monitoring action was invoked, further messages might get	607	port). After the monitoring action was invoked, further messages might get
463	delivered again.	608	delivered again.
464		609
465	Note that monitoring-actions are one-shot: once messages are lost (and a	610	Inter-host-connection timeouts and monitoring depend on the transport
466	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).
467		614
468	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
469	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
470	"normally"). Note also that I<< the callback B<must> never die >>, so use	617	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<$SELF>.
480
481	In the last form (message), a message of the form C<@msg, @reason> will be
482	C<snd>.
483
484	As a rule of thumb, monitoring requests should always monitor a port from
485	a local port (or callback). The reason is that kill messages might get
486	lost, just like any other message. Another less obvious reason is that
487	even monitoring requests can get lost (for exmaple, when the connection
488	to the other node goes down permanently). When monitoring a port locally
489	these problems do not exist.
490		618
491	Example: call a given callback when C<$port> is killed.	619	Example: call a given callback when C<$port> is killed.
492		620
493	mon $port, sub { warn "port died because of <@_>\n" };	621	mon $port, sub { warn "port died because of <@_>\n" };
494		622
…		…
501	mon $port, $self => "restart";	629	mon $port, $self => "restart";
502		630
503	=cut	631	=cut
504		632
505	sub mon {	633	sub mon {
506	my ($noderef, $port) = split /#/, shift, 2;	634	my ($nodeid, $port) = split /#/, shift, 2;
507		635
508	my $node = $NODE{$noderef} \|\| add_node $noderef;	636	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
509		637
510	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,';
511		639
512	unless (ref $cb) {	640	unless (ref $cb) {
513	if (@_) {	641	if (@_) {
…		…
522	}	650	}
523		651
524	$node->monitor ($port, $cb);	652	$node->monitor ($port, $cb);
525		653
526	defined wantarray	654	defined wantarray
527	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	655	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
528	}	656	}
529		657
530	=item $guard = mon_guard $port, $ref, $ref...	658	=item $guard = mon_guard $port, $ref, $ref...
531		659
532	Monitors the given C<$port> and keeps the passed references. When the port	660	Monitors the given C<$port> and keeps the passed references. When the port
…		…
555		683
556	=item kil $port[, @reason]	684	=item kil $port[, @reason]
557		685
558	Kill the specified port with the given C<@reason>.	686	Kill the specified port with the given C<@reason>.
559		687
560	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" -
561	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
562	"normally").	690	(C<mon $mport, $lport> form) to get killed.
563		691
564	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>
565	C<mon>, see above).	693	form) get killed with the same reason.
566		694
567	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
568	will be reported as reason C<< die => $@ >>.	696	will be reported as reason C<< die => $@ >>.
569		697
570	Transport/communication errors are reported as C<< transport_error =>	698	Transport/communication errors are reported as C<< transport_error =>
…		…
589	the package, then the package above the package and so on (e.g.	717	the package, then the package above the package and so on (e.g.
590	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	718	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
591	exists or it runs out of package names.	719	exists or it runs out of package names.
592		720
593	The init function is then called with the newly-created port as context	721	The init function is then called with the newly-created port as context
594	object (C<$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.
595		725
596	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
597	port, and in the remote init function, immediately monitor the passed	727	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	728	local port. This two-way monitoring ensures that both ports get cleaned up
599	when there is a problem.	729	when there is a problem.
600		730
		731	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		732	caller before C<spawn> returns (by delaying invocation when spawn is
		733	called for the local node).
		734
601	Example: spawn a chat server port on C<$othernode>.	735	Example: spawn a chat server port on C<$othernode>.
602		736
603	# this node, executed from within a port context:	737	# this node, executed from within a port context:
604	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	738	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
605	mon $server;	739	mon $server;
…		…
619		753
620	sub _spawn {	754	sub _spawn {
621	my $port = shift;	755	my $port = shift;
622	my $init = shift;	756	my $init = shift;
623		757
		758	# rcv will create the actual port
624	local $SELF = "$NODE#$port";	759	local $SELF = "$NODE#$port";
625	eval {	760	eval {
626	&{ load_func $init }	761	&{ load_func $init }
627	};	762	};
628	_self_die if $@;	763	_self_die if $@;
629	}	764	}
630		765
631	sub spawn(@) {	766	sub spawn(@) {
632	my ($noderef, undef) = split /#/, shift, 2;	767	my ($nodeid, undef) = split /#/, shift, 2;
633		768
634	my $id = "$RUNIQ." . $ID++;	769	my $id = "$RUNIQ." . $ID++;
635		770
636	$_[0] =~ /::/	771	$_[0] =~ /::/
637	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";
638		773
639	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	774	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
640		775
641	"$noderef#$id"	776	"$nodeid#$id"
642	}	777	}
643		778
644	=item after $timeout, @msg	779	=item after $timeout, @msg
645		780
646	=item after $timeout, $callback	781	=item after $timeout, $callback
…		…
663	? $action[0]()	798	? $action[0]()
664	: snd @action;	799	: snd @action;
665	};	800	};
666	}	801	}
667		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
668	=back	855	=back
669		856
670	=head1 AnyEvent::MP vs. Distributed Erlang	857	=head1 AnyEvent::MP vs. Distributed Erlang
671		858
672	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
673	== 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
674	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
675	sample:	862	sample:
676		863
677	http://www.Erlang.se/doc/programming_rules.shtml	864	http://www.erlang.se/doc/programming_rules.shtml
678	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
679	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
680	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
681		868
682	Despite the similarities, there are also some important differences:	869	Despite the similarities, there are also some important differences:
683		870
684	=over 4	871	=over 4
685		872
686	=item * Node IDs are arbitrary strings in AEMP.	873	=item * Node IDs are arbitrary strings in AEMP.
687		874
688	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
689	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
690	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.
691		879
692	=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
693	uses "local ports are like remote ports".	881	uses "local ports are like remote ports".
694		882
695	The failure modes for local ports are quite different (runtime errors	883	The failure modes for local ports are quite different (runtime errors
…		…
704	ports being the special case/exception, where transport errors cannot	892	ports being the special case/exception, where transport errors cannot
705	occur.	893	occur.
706		894
707	=item * Erlang uses processes and a mailbox, AEMP does not queue.	895	=item * Erlang uses processes and a mailbox, AEMP does not queue.
708		896
709	Erlang uses processes that selectively receive messages, and therefore	897	Erlang uses processes that selectively receive messages out of order, and
710	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
711	useful purpose. For the same reason the pattern-matching abilities of	899	no useful purpose. For the same reason the pattern-matching abilities
712	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
713	filter messages without dequeing them.	901	filter messages without dequeuing them.
714		902
715	(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.
716		908
717	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	909	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
718		910
719	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
720	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
721	connection establishment is handled in the background.	914	establishment is handled in the background.
722		915
723	=item * Erlang suffers from silent message loss, AEMP does not.	916	=item * Erlang suffers from silent message loss, AEMP does not.
724		917
725	Erlang makes few guarantees on messages delivery - messages can get lost	918	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,	919	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).	920	b, and c, and the other side only receives messages a and c).
728		921
729	AEMP guarantees correct ordering, and the guarantee that after one message	922	AEMP guarantees (modulo hardware errors) correct ordering, and the
730	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
731	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
732	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.
733		931
734	=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.
735		933
736	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
737	known to other nodes for a completely different process, causing messages	935	process ID known to other nodes for a completely different process,
738	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.
739		938
740	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
741	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.
742		941
743	=item * Erlang uses unprotected connections, AEMP uses secure	942	=item * Erlang uses unprotected connections, AEMP uses secure
744	authentication and can use TLS.	943	authentication and can use TLS.
745		944
…		…
748		947
749	=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
750	communications.	949	communications.
751		950
752	The AEMP protocol, unlike the Erlang protocol, supports both programming	951	The AEMP protocol, unlike the Erlang protocol, supports both programming
753	language independent text-only protocols (good for debugging) and binary,	952	language independent text-only protocols (good for debugging), and binary,
754	language-specific serialisers (e.g. Storable). By default, unless TLS is	953	language-specific serialisers (e.g. Storable). By default, unless TLS is
755	used, the protocol is actually completely text-based.	954	used, the protocol is actually completely text-based.
756		955
757	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
758	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
759	protocol simple.	958	protocol simple.
760		959
761	=item * AEMP has more flexible monitoring options than Erlang.	960	=item * AEMP has more flexible monitoring options than Erlang.
762		961
763	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
764	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
765	difficult to implement. Monitoring in AEMP is more flexible than in	964	difficult to implement.
766	Erlang, as one can choose between automatic kill, exit message or callback	965
767	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.
768		968
769	=item * Erlang tries to hide remote/local connections, AEMP does not.	969	=item * Erlang tries to hide remote/local connections, AEMP does not.
770		970
771	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
772	same way as linking is (except linking is unreliable in Erlang).	972	same way as linking is (except linking is unreliable in Erlang).
…		…
794	overhead, as well as having to keep a proxy object everywhere.	994	overhead, as well as having to keep a proxy object everywhere.
795		995
796	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
797	procedures to be "valid".	997	procedures to be "valid".
798		998
799	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
800	global hash - it can't become much cheaper.	1000	code reference stored in a global hash - it can't become much cheaper.
801		1001
802	=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?
803		1003
804	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
805	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
…		…
821		1021
822	L<AnyEvent::MP::Intro> - a gentle introduction.	1022	L<AnyEvent::MP::Intro> - a gentle introduction.
823		1023
824	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1024	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
825		1025
826	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1026	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
827	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.
828		1033
829	L<AnyEvent>.	1034	L<AnyEvent>.
830		1035
831	=head1 AUTHOR	1036	=head1 AUTHOR
832		1037

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

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