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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.97 by root, Fri Oct 2 13:29:49 2009 UTC vs.
Revision 1.156 by root, Sat Oct 23 03:35:49 2021 UTC

…		…
30	rcv $port, pong => sub { warn "pong received\n" };	30	rcv $port, pong => sub { warn "pong received\n" };
31		31
32	# create a port on another node	32	# create a port on another node
33	my $port = spawn $node, $initfunc, @initdata;	33	my $port = spawn $node, $initfunc, @initdata;
34		34
		35	# destroy a port again
		36	kil $port; # "normal" kill
		37	kil $port, my_error => "everything is broken"; # error kill
		38
35	# monitoring	39	# monitoring
36	mon $localport, $cb->(@msg) # callback is invoked on death	40	mon $port, $cb->(@msg) # callback is invoked on death
37	mon $localport, $otherport # kill otherport on abnormal death	41	mon $port, $localport # kill localport on abnormal death
38	mon $localport, $otherport, @msg # send message on death	42	mon $port, $localport, @msg # send message on death
39		43
40	=head1 CURRENT STATUS	44	# temporarily execute code in port context
		45	peval $port, sub { die "kill the port!" };
41		46
42	bin/aemp - stable.	47	# execute callbacks in $SELF port context
43	AnyEvent::MP - stable API, should work.	48	my $timer = AE::timer 1, 0, psub {
44	AnyEvent::MP::Intro - explains most concepts.	49	die "kill the port, delayed";
45	AnyEvent::MP::Kernel - mostly stable API.	50	};
46	AnyEvent::MP::Global - stable API.	51
		52	# distributed database - modification
		53	db_set $family => $subkey [=> $value] # add a subkey
		54	db_del $family => $subkey... # delete one or more subkeys
		55	db_reg $family => $port [=> $value] # register a port
		56
		57	# distributed database - queries
		58	db_family $family => $cb->(\%familyhash)
		59	db_keys $family => $cb->(\@keys)
		60	db_values $family => $cb->(\@values)
		61
		62	# distributed database - monitoring a family
		63	db_mon $family => $cb->(\%familyhash, \@added, \@changed, \@deleted)
47		64
48	=head1 DESCRIPTION	65	=head1 DESCRIPTION
49		66
50	This module (-family) implements a simple message passing framework.	67	This module (-family) implements a simple message passing framework.
51		68
…		…
59		76
60	=over 4	77	=over 4
61		78
62	=item port	79	=item port
63		80
64	Not to be confused with a TCP port, a "port" is something you can send	81	Not to be confused with TCP ports, a "port" is something you can send
65	messages to (with the C<snd> function).	82	messages to (with the C<snd> function).
66		83
67	Ports allow you to register C<rcv> handlers that can match all or just	84	Ports allow you to register C<rcv> handlers that can match all or just
68	some messages. Messages send to ports will not be queued, regardless of	85	some messages. Messages send to ports will not be queued, regardless of
69	anything was listening for them or not.	86	whether anything was listening for them or not.
		87
		88	Ports are represented by (printable) strings called "port IDs".
70		89
71	=item port ID - C<nodeid#portname>	90	=item port ID - C<nodeid#portname>
72		91
73	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as	92	A port ID is the concatenation of a node ID, a hash-mark (C<#>)
74	separator, and a port name (a printable string of unspecified format).	93	as separator, and a port name (a printable string of unspecified
		94	format created by AnyEvent::MP).
75		95
76	=item node	96	=item node
77		97
78	A node is a single process containing at least one port - the node port,	98	A node is a single process containing at least one port - the node port,
79	which enables nodes to manage each other remotely, and to create new	99	which enables nodes to manage each other remotely, and to create new
80	ports.	100	ports.
81		101
82	Nodes are either public (have one or more listening ports) or private	102	Nodes are either public (have one or more listening ports) or private
83	(no listening ports). Private nodes cannot talk to other private nodes	103	(no listening ports). Private nodes cannot talk to other private nodes
84	currently.	104	currently, but all nodes can talk to public nodes.
85		105
		106	Nodes is represented by (printable) strings called "node IDs".
		107
86	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>	108	=item node ID - C<[A-Za-z0-9_\-.:]*>
87		109
88	A node ID is a string that uniquely identifies the node within a	110	A node ID is a string that uniquely identifies the node within a
89	network. Depending on the configuration used, node IDs can look like a	111	network. Depending on the configuration used, node IDs can look like a
90	hostname, a hostname and a port, or a random string. AnyEvent::MP itself	112	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
91	doesn't interpret node IDs in any way.	113	doesn't interpret node IDs in any way except to uniquely identify a node.
92		114
93	=item binds - C<ip:port>	115	=item binds - C<ip:port>
94		116
95	Nodes can only talk to each other by creating some kind of connection to	117	Nodes can only talk to each other by creating some kind of connection to
96	each other. To do this, nodes should listen on one or more local transport	118	each other. To do this, nodes should listen on one or more local transport
		119	endpoints - binds.
		120
97	endpoints - binds. Currently, only standard C<ip:port> specifications can	121	Currently, only standard C<ip:port> specifications can be used, which
98	be used, which specify TCP ports to listen on.	122	specify TCP ports to listen on. So a bind is basically just a tcp socket
		123	in listening mode that accepts connections from other nodes.
99		124
100	=item seed nodes	125	=item seed nodes
101		126
102	When a node starts, it knows nothing about the network. To teach the node	127	When a node starts, it knows nothing about the network it is in - it
103	about the network it first has to contact some other node within the	128	needs to connect to at least one other node that is already in the
104	network. This node is called a seed.	129	network. These other nodes are called "seed nodes".
105		130
106	Apart from the fact that other nodes know them as seed nodes and they have	131	Seed nodes themselves are not special - they are seed nodes only because
107	to have fixed listening addresses, seed nodes are perfectly normal nodes -	132	some other node I<uses> them as such, but any node can be used as seed
108	any node can function as a seed node for others.	133	node for other nodes, and eahc node can use a different set of seed nodes.
109		134
110	In addition to discovering the network, seed nodes are also used to	135	In addition to discovering the network, seed nodes are also used to
111	maintain the network and to connect nodes that otherwise would have	136	maintain the network - all nodes using the same seed node are part of the
112	trouble connecting. They form the backbone of an AnyEvent::MP network.	137	same network. If a network is split into multiple subnets because e.g. the
		138	network link between the parts goes down, then using the same seed nodes
		139	for all nodes ensures that eventually the subnets get merged again.
113		140
114	Seed nodes are expected to be long-running, and at least one seed node	141	Seed nodes are expected to be long-running, and at least one seed node
115	should always be available. They should also be relatively responsive - a	142	should always be available. They should also be relatively responsive - a
116	seed node that blocks for long periods will slow down everybody else.	143	seed node that blocks for long periods will slow down everybody else.
117		144
		145	For small networks, it's best if every node uses the same set of seed
		146	nodes. For large networks, it can be useful to specify "regional" seed
		147	nodes for most nodes in an area, and use all seed nodes as seed nodes for
		148	each other. What's important is that all seed nodes connections form a
		149	complete graph, so that the network cannot split into separate subnets
		150	forever.
		151
		152	Seed nodes are represented by seed IDs.
		153
118	=item seeds - C<host:port>	154	=item seed IDs - C<host:port>
119		155
120	Seeds are transport endpoint(s) (usually a hostname/IP address and a	156	Seed IDs are transport endpoint(s) (usually a hostname/IP address and a
121	TCP port) of nodes that should be used as seed nodes.	157	TCP port) of nodes that should be used as seed nodes.
122		158
123	The nodes listening on those endpoints are expected to be long-running,	159	=item global nodes
124	and at least one of those should always be available. When nodes run out	160
125	of connections (e.g. due to a network error), they try to re-establish	161	An AEMP network needs a discovery service - nodes need to know how to
126	connections to some seednodes again to join the network.	162	connect to other nodes they only know by name. In addition, AEMP offers a
		163	distributed "group database", which maps group names to a list of strings
		164	- for example, to register worker ports.
		165
		166	A network needs at least one global node to work, and allows every node to
		167	be a global node.
		168
		169	Any node that loads the L<AnyEvent::MP::Global> module becomes a global
		170	node and tries to keep connections to all other nodes. So while it can
		171	make sense to make every node "global" in small networks, it usually makes
		172	sense to only make seed nodes into global nodes in large networks (nodes
		173	keep connections to seed nodes and global nodes, so making them the same
		174	reduces overhead).
127		175
128	=back	176	=back
129		177
130	=head1 VARIABLES/FUNCTIONS	178	=head1 VARIABLES/FUNCTIONS
131		179
…		…
133		181
134	=cut	182	=cut
135		183
136	package AnyEvent::MP;	184	package AnyEvent::MP;
137		185
		186	use AnyEvent::MP::Config ();
138	use AnyEvent::MP::Kernel;	187	use AnyEvent::MP::Kernel;
		188	use AnyEvent::MP::Kernel qw(
		189	%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID
		190	add_node load_func
		191
		192	NODE $NODE
		193	configure
		194	node_of port_is_local
		195	snd kil
		196	db_set db_del
		197	db_mon db_family db_keys db_values
		198	);
139		199
140	use common::sense;	200	use common::sense;
141		201
142	use Carp ();	202	use Carp ();
143		203
144	use AE ();	204	use AnyEvent ();
		205	use Guard ();
145		206
146	use base "Exporter";	207	use base "Exporter";
147		208
148	our $VERSION = 1.2;	209	our $VERSION = '2.02'; # also in MP/Config.pm
149		210
150	our @EXPORT = qw(	211	our @EXPORT = qw(
151	NODE $NODE *SELF node_of after
152	configure	212	configure
		213
		214	NODE $NODE
		215	*SELF
		216
		217	node_of port_is_local
		218
		219	snd kil
153	snd rcv mon mon_guard kil psub spawn cal	220	port rcv mon mon_guard psub peval spawn cal
154	port	221	db_set db_del db_reg
		222	db_mon db_family db_keys db_values
		223
		224	after
155	);	225	);
156		226
157	our $SELF;	227	our $SELF;
158		228
159	sub _self_die() {	229	sub _self_die() {
…		…
170		240
171	=item $nodeid = node_of $port	241	=item $nodeid = node_of $port
172		242
173	Extracts and returns the node ID from a port ID or a node ID.	243	Extracts and returns the node ID from a port ID or a node ID.
174		244
		245	=item $is_local = port_is_local $port
		246
		247	Returns true iff the port is a local port.
		248
175	=item configure $profile, key => value...	249	=item configure $profile, key => value...
176		250
177	=item configure key => value...	251	=item configure key => value...
178		252
179	Before a node can talk to other nodes on the network (i.e. enter	253	Before a node can talk to other nodes on the network (i.e. enter
…		…
181	to know is its own name, and optionally it should know the addresses of	255	to know is its own name, and optionally it should know the addresses of
182	some other nodes in the network to discover other nodes.	256	some other nodes in the network to discover other nodes.
183		257
184	This function configures a node - it must be called exactly once (or	258	This function configures a node - it must be called exactly once (or
185	never) before calling other AnyEvent::MP functions.	259	never) before calling other AnyEvent::MP functions.
		260
		261	The key/value pairs are basically the same ones as documented for the
		262	F<aemp> command line utility (sans the set/del prefix), with these additions:
		263
		264	=over 4
		265
		266	=item norc => $boolean (default false)
		267
		268	If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not>
		269	be consulted - all configuration options must be specified in the
		270	C<configure> call.
		271
		272	=item force => $boolean (default false)
		273
		274	IF true, then the values specified in the C<configure> will take
		275	precedence over any values configured via the rc file. The default is for
		276	the rc file to override any options specified in the program.
		277
		278	=back
186		279
187	=over 4	280	=over 4
188		281
189	=item step 1, gathering configuration from profiles	282	=item step 1, gathering configuration from profiles
190		283
…		…
204	That means that the values specified in the profile have highest priority	297	That means that the values specified in the profile have highest priority
205	and the values specified directly via C<configure> have lowest priority,	298	and the values specified directly via C<configure> have lowest priority,
206	and can only be used to specify defaults.	299	and can only be used to specify defaults.
207		300
208	If the profile specifies a node ID, then this will become the node ID of	301	If the profile specifies a node ID, then this will become the node ID of
209	this process. If not, then the profile name will be used as node ID. The	302	this process. If not, then the profile name will be used as node ID, with
210	special node ID of C<anon/> will be replaced by a random node ID.	303	a unique randoms tring (C</%u>) appended.
		304
		305	The node ID can contain some C<%> sequences that are expanded: C<%n>
		306	is expanded to the local nodename, C<%u> is replaced by a random
		307	string to make the node unique. For example, the F<aemp> commandline
		308	utility uses C<aemp/%n/%u> as nodename, which might expand to
		309	C<aemp/cerebro/ZQDGSIkRhEZQDGSIkRhE>.
211		310
212	=item step 2, bind listener sockets	311	=item step 2, bind listener sockets
213		312
214	The next step is to look up the binds in the profile, followed by binding	313	The next step is to look up the binds in the profile, followed by binding
215	aemp protocol listeners on all binds specified (it is possible and valid	314	aemp protocol listeners on all binds specified (it is possible and valid
216	to have no binds, meaning that the node cannot be contacted form the	315	to have no binds, meaning that the node cannot be contacted from the
217	outside. This means the node cannot talk to other nodes that also have no	316	outside. This means the node cannot talk to other nodes that also have no
218	binds, but it can still talk to all "normal" nodes).	317	binds, but it can still talk to all "normal" nodes).
219		318
220	If the profile does not specify a binds list, then a default of C<*> is	319	If the profile does not specify a binds list, then a default of C<*> is
221	used, meaning the node will bind on a dynamically-assigned port on every	320	used, meaning the node will bind on a dynamically-assigned port on every
222	local IP address it finds.	321	local IP address it finds.
223		322
224	=item step 3, connect to seed nodes	323	=item step 3, connect to seed nodes
225		324
226	As the last step, the seeds list from the profile is passed to the	325	As the last step, the seed ID list from the profile is passed to the
227	L<AnyEvent::MP::Global> module, which will then use it to keep	326	L<AnyEvent::MP::Global> module, which will then use it to keep
228	connectivity with at least one node at any point in time.	327	connectivity with at least one node at any point in time.
229		328
230	=back	329	=back
231		330
232	Example: become a distributed node using the local node name as profile.	331	Example: become a distributed node using the local node name as profile.
233	This should be the most common form of invocation for "daemon"-type nodes.	332	This should be the most common form of invocation for "daemon"-type nodes.
234		333
235	configure	334	configure
236		335
237	Example: become an anonymous node. This form is often used for commandline	336	Example: become a semi-anonymous node. This form is often used for
238	clients.	337	commandline clients.
239		338
240	configure nodeid => "anon/";	339	configure nodeid => "myscript/%n/%u";
241		340
242	Example: configure a node using a profile called seed, which si suitable	341	Example: configure a node using a profile called seed, which is suitable
243	for a seed node as it binds on all local addresses on a fixed port (4040,	342	for a seed node as it binds on all local addresses on a fixed port (4040,
244	customary for aemp).	343	customary for aemp).
245		344
246	# use the aemp commandline utility	345	# use the aemp commandline utility
247	# aemp profile seed nodeid anon/ binds '*:4040'	346	# aemp profile seed binds '*:4040'
248		347
249	# then use it	348	# then use it
250	configure profile => "seed";	349	configure profile => "seed";
251		350
252	# or simply use aemp from the shell again:	351	# or simply use aemp from the shell again:
…		…
317		416
318	=cut	417	=cut
319		418
320	sub rcv($@);	419	sub rcv($@);
321		420
322	sub _kilme {	421	my $KILME = sub {
323	die "received message on port without callback";	422	(my $tag = substr $_[0], 0, 30) =~ s/([^\x20-\x7e])/./g;
324	}	423	kil $SELF, unhandled_message => "no callback found for message '$tag'";
		424	};
325		425
326	sub port(;&) {	426	sub port(;&) {
327	my $id = "$UNIQ." . $ID++;	427	my $id = $UNIQ . ++$ID;
328	my $port = "$NODE#$id";	428	my $port = "$NODE#$id";
329		429
330	rcv $port, shift \|\| \&_kilme;	430	rcv $port, shift \|\| $KILME;
331		431
332	$port	432	$port
333	}	433	}
334		434
335	=item rcv $local_port, $callback->(@msg)	435	=item rcv $local_port, $callback->(@msg)
…		…
340		440
341	The global C<$SELF> (exported by this module) contains C<$port> while	441	The global C<$SELF> (exported by this module) contains C<$port> while
342	executing the callback. Runtime errors during callback execution will	442	executing the callback. Runtime errors during callback execution will
343	result in the port being C<kil>ed.	443	result in the port being C<kil>ed.
344		444
345	The default callback received all messages not matched by a more specific	445	The default callback receives all messages not matched by a more specific
346	C<tag> match.	446	C<tag> match.
347		447
348	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...	448	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
349		449
350	Register (or replace) callbacks to be called on messages starting with the	450	Register (or replace) callbacks to be called on messages starting with the
…		…
371	msg1 => sub { ... },	471	msg1 => sub { ... },
372	...	472	...
373	;	473	;
374		474
375	Example: temporarily register a rcv callback for a tag matching some port	475	Example: temporarily register a rcv callback for a tag matching some port
376	(e.g. for a rpc reply) and unregister it after a message was received.	476	(e.g. for an rpc reply) and unregister it after a message was received.
377		477
378	rcv $port, $otherport => sub {	478	rcv $port, $otherport => sub {
379	my @reply = @_;	479	my @reply = @_;
380		480
381	rcv $SELF, $otherport;	481	rcv $SELF, $otherport;
…		…
385		485
386	sub rcv($@) {	486	sub rcv($@) {
387	my $port = shift;	487	my $port = shift;
388	my ($nodeid, $portid) = split /#/, $port, 2;	488	my ($nodeid, $portid) = split /#/, $port, 2;
389		489
390	$NODE{$nodeid} == $NODE{""}	490	$nodeid eq $NODE
391	or Carp::croak "$port: rcv can only be called on local ports, caught";	491	or Carp::croak "$port: rcv can only be called on local ports, caught";
392		492
393	while (@_) {	493	while (@_) {
394	if (ref $_[0]) {	494	if (ref $_[0]) {
395	if (my $self = $PORT_DATA{$portid}) {	495	if (my $self = $PORT_DATA{$portid}) {
396	"AnyEvent::MP::Port" eq ref $self	496	"AnyEvent::MP::Port" eq ref $self
397	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	497	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
398		498
399	$self->[2] = shift;	499	$self->[0] = shift;
400	} else {	500	} else {
401	my $cb = shift;	501	my $cb = shift;
402	$PORT{$portid} = sub {	502	$PORT{$portid} = sub {
403	local $SELF = $port;	503	local $SELF = $port;
404	eval { &$cb }; _self_die if $@;	504	eval { &$cb }; _self_die if $@;
405	};	505	};
406	}	506	}
407	} elsif (defined $_[0]) {	507	} elsif (defined $_[0]) {
408	my $self = $PORT_DATA{$portid} \|\|= do {	508	my $self = $PORT_DATA{$portid} \|\|= do {
409	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	509	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
410		510
411	$PORT{$portid} = sub {	511	$PORT{$portid} = sub {
412	local $SELF = $port;	512	local $SELF = $port;
413		513
414	if (my $cb = $self->[1]{$_[0]}) {	514	if (my $cb = $self->[1]{$_[0]}) {
…		…
436	}	536	}
437		537
438	$port	538	$port
439	}	539	}
440		540
		541	=item peval $port, $coderef[, @args]
		542
		543	Evaluates the given C<$codref> within the context of C<$port>, that is,
		544	when the code throws an exception the C<$port> will be killed.
		545
		546	Any remaining args will be passed to the callback. Any return values will
		547	be returned to the caller.
		548
		549	This is useful when you temporarily want to execute code in the context of
		550	a port.
		551
		552	Example: create a port and run some initialisation code in it's context.
		553
		554	my $port = port { ... };
		555
		556	peval $port, sub {
		557	init
		558	or die "unable to init";
		559	};
		560
		561	=cut
		562
		563	sub peval($$) {
		564	local $SELF = shift;
		565	my $cb = shift;
		566
		567	if (wantarray) {
		568	my @res = eval { &$cb };
		569	_self_die if $@;
		570	@res
		571	} else {
		572	my $res = eval { &$cb };
		573	_self_die if $@;
		574	$res
		575	}
		576	}
		577
441	=item $closure = psub { BLOCK }	578	=item $closure = psub { BLOCK }
442		579
443	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	580	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
444	closure is executed, sets up the environment in the same way as in C<rcv>	581	closure is executed, sets up the environment in the same way as in C<rcv>
445	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.	582	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		583
		584	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		585	BLOCK }, @_ } >>.
446		586
447	This is useful when you register callbacks from C<rcv> callbacks:	587	This is useful when you register callbacks from C<rcv> callbacks:
448		588
449	rcv delayed_reply => sub {	589	rcv delayed_reply => sub {
450	my ($delay, @reply) = @_;	590	my ($delay, @reply) = @_;
…		…
474	$res	614	$res
475	}	615	}
476	}	616	}
477	}	617	}
478		618
		619	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		620
		621	=item $guard = mon $port # kill $SELF when $port dies
		622
479	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies	623	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
480
481	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
482
483	=item $guard = mon $port # kill $SELF when $port dies
484		624
485	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies	625	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
486		626
487	Monitor the given port and do something when the port is killed or	627	Monitor the given port and do something when the port is killed or
488	messages to it were lost, and optionally return a guard that can be used	628	messages to it were lost, and optionally return a guard that can be used
489	to stop monitoring again.	629	to stop monitoring again.
490		630
		631	The first two forms distinguish between "normal" and "abnormal" kil's:
		632
		633	In the first form (another port given), if the C<$port> is C<kil>'ed with
		634	a non-empty reason, the other port (C<$rcvport>) will be kil'ed with the
		635	same reason. That is, on "normal" kil's nothing happens, while under all
		636	other conditions, the other port is killed with the same reason.
		637
		638	The second form (kill self) is the same as the first form, except that
		639	C<$rvport> defaults to C<$SELF>.
		640
		641	The remaining forms don't distinguish between "normal" and "abnormal" kil's
		642	- it's up to the callback or receiver to check whether the C<@reason> is
		643	empty and act accordingly.
		644
491	In the first form (callback), the callback is simply called with any	645	In the third form (callback), the callback is simply called with any
492	number of C<@reason> elements (no @reason means that the port was deleted	646	number of C<@reason> elements (empty @reason means that the port was deleted
493	"normally"). Note also that I<< the callback B<must> never die >>, so use	647	"normally"). Note also that I<< the callback B<must> never die >>, so use
494	C<eval> if unsure.	648	C<eval> if unsure.
495		649
496	In the second form (another port given), the other port (C<$rcvport>)
497	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
498	"normal" kils nothing happens, while under all other conditions, the other
499	port is killed with the same reason.
500
501	The third form (kill self) is the same as the second form, except that
502	C<$rvport> defaults to C<$SELF>.
503
504	In the last form (message), a message of the form C<@msg, @reason> will be	650	In the last form (message), a message of the form C<$rcvport, @msg,
505	C<snd>.	651	@reason> will be C<snd>.
506		652
507	Monitoring-actions are one-shot: once messages are lost (and a monitoring	653	Monitoring-actions are one-shot: once messages are lost (and a monitoring
508	alert was raised), they are removed and will not trigger again.	654	alert was raised), they are removed and will not trigger again, even if it
		655	turns out that the port is still alive (but monitoring actions added after
		656	that will again trigger).
509		657
510	As a rule of thumb, monitoring requests should always monitor a port from	658	As a rule of thumb, monitoring requests should always monitor a remote
511	a local port (or callback). The reason is that kill messages might get	659	port locally (using a local C<$rcvport> or a callback). The reason is that
512	lost, just like any other message. Another less obvious reason is that	660	kill messages might get lost, just like any other message. Another less
513	even monitoring requests can get lost (for example, when the connection	661	obvious reason is that even monitoring requests can get lost (for example,
514	to the other node goes down permanently). When monitoring a port locally	662	when the connection to the other node goes down permanently). When
515	these problems do not exist.	663	monitoring a port locally these problems do not exist.
516		664
517	C<mon> effectively guarantees that, in the absence of hardware failures,	665	C<mon> effectively guarantees that, in the absence of hardware failures,
518	after starting the monitor, either all messages sent to the port will	666	after starting the monitor, either all messages sent to the port will
519	arrive, or the monitoring action will be invoked after possible message	667	arrive, or the monitoring action will be invoked after possible message
520	loss has been detected. No messages will be lost "in between" (after	668	loss has been detected. No messages will be lost "in between" (after
…		…
565	}	713	}
566		714
567	$node->monitor ($port, $cb);	715	$node->monitor ($port, $cb);
568		716
569	defined wantarray	717	defined wantarray
570	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })	718	and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) })
571	}	719	}
572		720
573	=item $guard = mon_guard $port, $ref, $ref...	721	=item $guard = mon_guard $port, $ref, $ref...
574		722
575	Monitors the given C<$port> and keeps the passed references. When the port	723	Monitors the given C<$port> and keeps the passed references. When the port
…		…
598		746
599	=item kil $port[, @reason]	747	=item kil $port[, @reason]
600		748
601	Kill the specified port with the given C<@reason>.	749	Kill the specified port with the given C<@reason>.
602		750
603	If no C<@reason> is specified, then the port is killed "normally" (ports	751	If no C<@reason> is specified, then the port is killed "normally" -
604	monitoring other ports will not necessarily die because a port dies	752	monitor callback will be invoked, but the kil will not cause linked ports
605	"normally").	753	(C<mon $mport, $lport> form) to get killed.
606		754
607	Otherwise, linked ports get killed with the same reason (second form of	755	If a C<@reason> is specified, then linked ports (C<mon $mport, $lport>
608	C<mon>, see above).	756	form) get killed with the same reason.
609		757
610	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	758	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
611	will be reported as reason C<< die => $@ >>.	759	will be reported as reason C<< die => $@ >>.
612		760
613	Transport/communication errors are reported as C<< transport_error =>	761	Transport/communication errors are reported as C<< transport_error =>
614	$message >>.	762	$message >>.
615		763
616	=cut	764	Common idioms:
		765
		766	# silently remove yourself, do not kill linked ports
		767	kil $SELF;
		768
		769	# report a failure in some detail
		770	kil $SELF, failure_mode_1 => "it failed with too high temperature";
		771
		772	# do not waste much time with killing, just die when something goes wrong
		773	open my $fh, "<file"
		774	or die "file: $!";
617		775
618	=item $port = spawn $node, $initfunc[, @initdata]	776	=item $port = spawn $node, $initfunc[, @initdata]
619		777
620	Creates a port on the node C<$node> (which can also be a port ID, in which	778	Creates a port on the node C<$node> (which can also be a port ID, in which
621	case it's the node where that port resides).	779	case it's the node where that port resides).
…		…
679	}	837	}
680		838
681	sub spawn(@) {	839	sub spawn(@) {
682	my ($nodeid, undef) = split /#/, shift, 2;	840	my ($nodeid, undef) = split /#/, shift, 2;
683		841
684	my $id = "$RUNIQ." . $ID++;	842	my $id = $RUNIQ . ++$ID;
685		843
686	$_[0] =~ /::/	844	$_[0] =~ /::/
687	or Carp::croak "spawn init function must be a fully-qualified name, caught";	845	or Carp::croak "spawn init function must be a fully-qualified name, caught";
688		846
689	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;	847	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
690		848
691	"$nodeid#$id"	849	"$nodeid#$id"
692	}	850	}
		851
693		852
694	=item after $timeout, @msg	853	=item after $timeout, @msg
695		854
696	=item after $timeout, $callback	855	=item after $timeout, $callback
697		856
…		…
713	? $action[0]()	872	? $action[0]()
714	: snd @action;	873	: snd @action;
715	};	874	};
716	}	875	}
717		876
		877	#=item $cb2 = timeout $seconds, $cb[, @args]
		878
718	=item cal $port, @msg, $callback[, $timeout]	879	=item cal $port, @msg, $callback[, $timeout]
719		880
720	A simple form of RPC - sends a message to the given C<$port> with the	881	A simple form of RPC - sends a message to the given C<$port> with the
721	given contents (C<@msg>), but adds a reply port to the message.	882	given contents (C<@msg>), but appends a reply port to the message.
722		883
723	The reply port is created temporarily just for the purpose of receiving	884	The reply port is created temporarily just for the purpose of receiving
724	the reply, and will be C<kil>ed when no longer needed.	885	the reply, and will be C<kil>ed when no longer needed.
725		886
726	A reply message sent to the port is passed to the C<$callback> as-is.	887	A reply message sent to the port is passed to the C<$callback> as-is.
727		888
728	If an optional time-out (in seconds) is given and it is not C<undef>,	889	If an optional time-out (in seconds) is given and it is not C<undef>,
729	then the callback will be called without any arguments after the time-out	890	then the callback will be called without any arguments after the time-out
730	elapsed and the port is C<kil>ed.	891	elapsed and the port is C<kil>ed.
731		892
732	If no time-out is given, then the local port will monitor the remote port	893	If no time-out is given (or it is C<undef>), then the local port will
733	instead, so it eventually gets cleaned-up.	894	monitor the remote port instead, so it eventually gets cleaned-up.
734		895
735	Currently this function returns the temporary port, but this "feature"	896	Currently this function returns the temporary port, but this "feature"
736	might go in future versions unless you can make a convincing case that	897	might go in future versions unless you can make a convincing case that
737	this is indeed useful for something.	898	this is indeed useful for something.
738		899
…		…
767	$port	928	$port
768	}	929	}
769		930
770	=back	931	=back
771		932
		933	=head1 DISTRIBUTED DATABASE
		934
		935	AnyEvent::MP comes with a simple distributed database. The database will
		936	be mirrored asynchronously on all global nodes. Other nodes bind to one
		937	of the global nodes for their needs. Every node has a "local database"
		938	which contains all the values that are set locally. All local databases
		939	are merged together to form the global database, which can be queried.
		940
		941	The database structure is that of a two-level hash - the database hash
		942	contains hashes which contain values, similarly to a perl hash of hashes,
		943	i.e.:
		944
		945	$DATABASE{$family}{$subkey} = $value
		946
		947	The top level hash key is called "family", and the second-level hash key
		948	is called "subkey" or simply "key".
		949
		950	The family must be alphanumeric, i.e. start with a letter and consist
		951	of letters, digits, underscores and colons (C<[A-Za-z][A-Za-z0-9_:]*>,
		952	pretty much like Perl module names.
		953
		954	As the family namespace is global, it is recommended to prefix family names
		955	with the name of the application or module using it.
		956
		957	The subkeys must be non-empty strings, with no further restrictions.
		958
		959	The values should preferably be strings, but other perl scalars should
		960	work as well (such as C<undef>, arrays and hashes).
		961
		962	Every database entry is owned by one node - adding the same family/subkey
		963	combination on multiple nodes will not cause discomfort for AnyEvent::MP,
		964	but the result might be nondeterministic, i.e. the key might have
		965	different values on different nodes.
		966
		967	Different subkeys in the same family can be owned by different nodes
		968	without problems, and in fact, this is the common method to create worker
		969	pools. For example, a worker port for image scaling might do this:
		970
		971	db_set my_image_scalers => $port; # value not used
		972
		973	And clients looking for an image scaler will want to get the
		974	C<my_image_scalers> keys from time to time:
		975
		976	db_keys my_image_scalers => sub {
		977	@ports = @{ $_[0] };
		978	};
		979
		980	Or better yet, they want to monitor the database family, so they always
		981	have a reasonable up-to-date copy:
		982
		983	db_mon my_image_scalers => sub {
		984	@ports = keys %{ $_[0] };
		985	};
		986
		987	In general, you can set or delete single subkeys, but query and monitor
		988	whole families only.
		989
		990	If you feel the need to monitor or query a single subkey, try giving it
		991	it's own family.
		992
		993	=over
		994
		995	=item $guard = db_set $family => $subkey [=> $value]
		996
		997	Sets (or replaces) a key to the database - if C<$value> is omitted,
		998	C<undef> is used instead.
		999
		1000	When called in non-void context, C<db_set> returns a guard that
		1001	automatically calls C<db_del> when it is destroyed.
		1002
		1003	=item db_del $family => $subkey...
		1004
		1005	Deletes one or more subkeys from the database family.
		1006
		1007	=item $guard = db_reg $family => $port => $value
		1008
		1009	=item $guard = db_reg $family => $port
		1010
		1011	=item $guard = db_reg $family
		1012
		1013	Registers a port in the given family and optionally returns a guard to
		1014	remove it.
		1015
		1016	This function basically does the same as:
		1017
		1018	db_set $family => $port => $value
		1019
		1020	Except that the port is monitored and automatically removed from the
		1021	database family when it is kil'ed.
		1022
		1023	If C<$value> is missing, C<undef> is used. If C<$port> is missing, then
		1024	C<$SELF> is used.
		1025
		1026	This function is most useful to register a port in some port group (which
		1027	is just another name for a database family), and have it removed when the
		1028	port is gone. This works best when the port is a local port.
		1029
		1030	=cut
		1031
		1032	sub db_reg($$;$) {
		1033	my $family = shift;
		1034	my $port = @_ ? shift : $SELF;
		1035
		1036	my $clr = sub { db_del $family => $port };
		1037	mon $port, $clr;
		1038
		1039	db_set $family => $port => $_[0];
		1040
		1041	defined wantarray
		1042	and &Guard::guard ($clr)
		1043	}
		1044
		1045	=item db_family $family => $cb->(\%familyhash)
		1046
		1047	Queries the named database C<$family> and call the callback with the
		1048	family represented as a hash. You can keep and freely modify the hash.
		1049
		1050	=item db_keys $family => $cb->(\@keys)
		1051
		1052	Same as C<db_family>, except it only queries the family I<subkeys> and passes
		1053	them as array reference to the callback.
		1054
		1055	=item db_values $family => $cb->(\@values)
		1056
		1057	Same as C<db_family>, except it only queries the family I<values> and passes them
		1058	as array reference to the callback.
		1059
		1060	=item $guard = db_mon $family => $cb->(\%familyhash, \@added, \@changed, \@deleted)
		1061
		1062	Creates a monitor on the given database family. Each time a key is
		1063	set or is deleted the callback is called with a hash containing the
		1064	database family and three lists of added, changed and deleted subkeys,
		1065	respectively. If no keys have changed then the array reference might be
		1066	C<undef> or even missing.
		1067
		1068	If not called in void context, a guard object is returned that, when
		1069	destroyed, stops the monitor.
		1070
		1071	The family hash reference and the key arrays belong to AnyEvent::MP and
		1072	B<must not be modified or stored> by the callback. When in doubt, make a
		1073	copy.
		1074
		1075	As soon as possible after the monitoring starts, the callback will be
		1076	called with the intiial contents of the family, even if it is empty,
		1077	i.e. there will always be a timely call to the callback with the current
		1078	contents.
		1079
		1080	It is possible that the callback is called with a change event even though
		1081	the subkey is already present and the value has not changed.
		1082
		1083	The monitoring stops when the guard object is destroyed.
		1084
		1085	Example: on every change to the family "mygroup", print out all keys.
		1086
		1087	my $guard = db_mon mygroup => sub {
		1088	my ($family, $a, $c, $d) = @_;
		1089	print "mygroup members: ", (join " ", keys %$family), "\n";
		1090	};
		1091
		1092	Exmaple: wait until the family "My::Module::workers" is non-empty.
		1093
		1094	my $guard; $guard = db_mon My::Module::workers => sub {
		1095	my ($family, $a, $c, $d) = @_;
		1096	return unless %$family;
		1097	undef $guard;
		1098	print "My::Module::workers now nonempty\n";
		1099	};
		1100
		1101	Example: print all changes to the family "AnyEvent::Fantasy::Module".
		1102
		1103	my $guard = db_mon AnyEvent::Fantasy::Module => sub {
		1104	my ($family, $a, $c, $d) = @_;
		1105
		1106	print "+$_=$family->{$_}\n" for @$a;
		1107	print "*$_=$family->{$_}\n" for @$c;
		1108	print "-$_=$family->{$_}\n" for @$d;
		1109	};
		1110
		1111	=cut
		1112
		1113	=back
		1114
772	=head1 AnyEvent::MP vs. Distributed Erlang	1115	=head1 AnyEvent::MP vs. Distributed Erlang
773		1116
774	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	1117	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
775	== aemp node, Erlang process == aemp port), so many of the documents and	1118	== aemp node, Erlang process == aemp port), so many of the documents and
776	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	1119	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
…		…
787		1130
788	=item * Node IDs are arbitrary strings in AEMP.	1131	=item * Node IDs are arbitrary strings in AEMP.
789		1132
790	Erlang relies on special naming and DNS to work everywhere in the same	1133	Erlang relies on special naming and DNS to work everywhere in the same
791	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by	1134	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
792	configuration or DNS), but will otherwise discover other odes itself.	1135	configuration or DNS), and possibly the addresses of some seed nodes, but
		1136	will otherwise discover other nodes (and their IDs) itself.
793		1137
794	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	1138	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
795	uses "local ports are like remote ports".	1139	uses "local ports are like remote ports".
796		1140
797	The failure modes for local ports are quite different (runtime errors	1141	The failure modes for local ports are quite different (runtime errors
…		…
806	ports being the special case/exception, where transport errors cannot	1150	ports being the special case/exception, where transport errors cannot
807	occur.	1151	occur.
808		1152
809	=item * Erlang uses processes and a mailbox, AEMP does not queue.	1153	=item * Erlang uses processes and a mailbox, AEMP does not queue.
810		1154
811	Erlang uses processes that selectively receive messages, and therefore	1155	Erlang uses processes that selectively receive messages out of order, and
812	needs a queue. AEMP is event based, queuing messages would serve no	1156	therefore needs a queue. AEMP is event based, queuing messages would serve
813	useful purpose. For the same reason the pattern-matching abilities of	1157	no useful purpose. For the same reason the pattern-matching abilities
814	AnyEvent::MP are more limited, as there is little need to be able to	1158	of AnyEvent::MP are more limited, as there is little need to be able to
815	filter messages without dequeuing them.	1159	filter messages without dequeuing them.
816		1160
817	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	1161	This is not a philosophical difference, but simply stems from AnyEvent::MP
		1162	being event-based, while Erlang is process-based.
		1163
		1164	You can have a look at L<Coro::MP> for a more Erlang-like process model on
		1165	top of AEMP and Coro threads.
818		1166
819	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	1167	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
820		1168
821	Sending messages in Erlang is synchronous and blocks the process (and	1169	Sending messages in Erlang is synchronous and blocks the process until
		1170	a connection has been established and the message sent (and so does not
822	so does not need a queue that can overflow). AEMP sends are immediate,	1171	need a queue that can overflow). AEMP sends return immediately, connection
823	connection establishment is handled in the background.	1172	establishment is handled in the background.
824		1173
825	=item * Erlang suffers from silent message loss, AEMP does not.	1174	=item * Erlang suffers from silent message loss, AEMP does not.
826		1175
827	Erlang makes few guarantees on messages delivery - messages can get lost	1176	Erlang implements few guarantees on messages delivery - messages can get
828	without any of the processes realising it (i.e. you send messages a, b,	1177	lost without any of the processes realising it (i.e. you send messages a,
829	and c, and the other side only receives messages a and c).	1178	b, and c, and the other side only receives messages a and c).
830		1179
831	AEMP guarantees correct ordering, and the guarantee that after one message	1180	AEMP guarantees (modulo hardware errors) correct ordering, and the
832	is lost, all following ones sent to the same port are lost as well, until	1181	guarantee that after one message is lost, all following ones sent to the
833	monitoring raises an error, so there are no silent "holes" in the message	1182	same port are lost as well, until monitoring raises an error, so there are
834	sequence.	1183	no silent "holes" in the message sequence.
		1184
		1185	If you want your software to be very reliable, you have to cope with
		1186	corrupted and even out-of-order messages in both Erlang and AEMP. AEMP
		1187	simply tries to work better in common error cases, such as when a network
		1188	link goes down.
835		1189
836	=item * Erlang can send messages to the wrong port, AEMP does not.	1190	=item * Erlang can send messages to the wrong port, AEMP does not.
837		1191
838	In Erlang it is quite likely that a node that restarts reuses a process ID	1192	In Erlang it is quite likely that a node that restarts reuses an Erlang
839	known to other nodes for a completely different process, causing messages	1193	process ID known to other nodes for a completely different process,
840	destined for that process to end up in an unrelated process.	1194	causing messages destined for that process to end up in an unrelated
		1195	process.
841		1196
842	AEMP never reuses port IDs, so old messages or old port IDs floating	1197	AEMP does not reuse port IDs, so old messages or old port IDs floating
843	around in the network will not be sent to an unrelated port.	1198	around in the network will not be sent to an unrelated port.
844		1199
845	=item * Erlang uses unprotected connections, AEMP uses secure	1200	=item * Erlang uses unprotected connections, AEMP uses secure
846	authentication and can use TLS.	1201	authentication and can use TLS.
847		1202
…		…
850		1205
851	=item * The AEMP protocol is optimised for both text-based and binary	1206	=item * The AEMP protocol is optimised for both text-based and binary
852	communications.	1207	communications.
853		1208
854	The AEMP protocol, unlike the Erlang protocol, supports both programming	1209	The AEMP protocol, unlike the Erlang protocol, supports both programming
855	language independent text-only protocols (good for debugging) and binary,	1210	language independent text-only protocols (good for debugging), and binary,
856	language-specific serialisers (e.g. Storable). By default, unless TLS is	1211	language-specific serialisers (e.g. Storable). By default, unless TLS is
857	used, the protocol is actually completely text-based.	1212	used, the protocol is actually completely text-based.
858		1213
859	It has also been carefully designed to be implementable in other languages	1214	It has also been carefully designed to be implementable in other languages
860	with a minimum of work while gracefully degrading functionality to make the	1215	with a minimum of work while gracefully degrading functionality to make the
861	protocol simple.	1216	protocol simple.
862		1217
863	=item * AEMP has more flexible monitoring options than Erlang.	1218	=item * AEMP has more flexible monitoring options than Erlang.
864		1219
865	In Erlang, you can chose to receive I<all> exit signals as messages	1220	In Erlang, you can chose to receive I<all> exit signals as messages or
866	or I<none>, there is no in-between, so monitoring single processes is	1221	I<none>, there is no in-between, so monitoring single Erlang processes is
867	difficult to implement. Monitoring in AEMP is more flexible than in	1222	difficult to implement.
868	Erlang, as one can choose between automatic kill, exit message or callback	1223
869	on a per-process basis.	1224	Monitoring in AEMP is more flexible than in Erlang, as one can choose
		1225	between automatic kill, exit message or callback on a per-port basis.
870		1226
871	=item * Erlang tries to hide remote/local connections, AEMP does not.	1227	=item * Erlang tries to hide remote/local connections, AEMP does not.
872		1228
873	Monitoring in Erlang is not an indicator of process death/crashes, in the	1229	Monitoring in Erlang is not an indicator of process death/crashes, in the
874	same way as linking is (except linking is unreliable in Erlang).	1230	same way as linking is (except linking is unreliable in Erlang).
…		…
896	overhead, as well as having to keep a proxy object everywhere.	1252	overhead, as well as having to keep a proxy object everywhere.
897		1253
898	Strings can easily be printed, easily serialised etc. and need no special	1254	Strings can easily be printed, easily serialised etc. and need no special
899	procedures to be "valid".	1255	procedures to be "valid".
900		1256
901	And as a result, a miniport consists of a single closure stored in a	1257	And as a result, a port with just a default receiver consists of a single
902	global hash - it can't become much cheaper.	1258	code reference stored in a global hash - it can't become much cheaper.
903		1259
904	=item Why favour JSON, why not a real serialising format such as Storable?	1260	=item Why favour JSON, why not a real serialising format such as Storable?
905		1261
906	In fact, any AnyEvent::MP node will happily accept Storable as framing	1262	In fact, any AnyEvent::MP node will happily accept Storable as framing
907	format, but currently there is no way to make a node use Storable by	1263	format, but currently there is no way to make a node use Storable by
…		…
917	Keeping your messages simple, concentrating on data structures rather than	1273	Keeping your messages simple, concentrating on data structures rather than
918	objects, will keep your messages clean, tidy and efficient.	1274	objects, will keep your messages clean, tidy and efficient.
919		1275
920	=back	1276	=back
921		1277
		1278	=head1 PORTING FROM AnyEvent::MP VERSION 1.X
		1279
		1280	AEMP version 2 has a few major incompatible changes compared to version 1:
		1281
		1282	=over 4
		1283
		1284	=item AnyEvent::MP::Global no longer has group management functions.
		1285
		1286	At least not officially - the grp_* functions are still exported and might
		1287	work, but they will be removed in some later release.
		1288
		1289	AnyEvent::MP now comes with a distributed database that is more
		1290	powerful. Its database families map closely to port groups, but the API
		1291	has changed (the functions are also now exported by AnyEvent::MP). Here is
		1292	a rough porting guide:
		1293
		1294	grp_reg $group, $port # old
		1295	db_reg $group, $port # new
		1296
		1297	$list = grp_get $group # old
		1298	db_keys $group, sub { my $list = shift } # new
		1299
		1300	grp_mon $group, $cb->(\@ports, $add, $del) # old
		1301	db_mon $group, $cb->(\%ports, $add, $change, $del) # new
		1302
		1303	C<grp_reg> is a no-brainer (just replace by C<db_reg>), but C<grp_get> is
		1304	no longer instant, because the local node might not have a copy of the
		1305	group. You can either modify your code to allow for a callback, or use
		1306	C<db_mon> to keep an updated copy of the group:
		1307
		1308	my $local_group_copy;
		1309	db_mon $group => sub { $local_group_copy = $_[0] };
		1310
		1311	# now "keys %$local_group_copy" always returns the most up-to-date
		1312	# list of ports in the group.
		1313
		1314	C<grp_mon> can be replaced by C<db_mon> with minor changes - C<db_mon>
		1315	passes a hash as first argument, and an extra C<$chg> argument that can be
		1316	ignored:
		1317
		1318	db_mon $group => sub {
		1319	my ($ports, $add, $chg, $del) = @_;
		1320	$ports = [keys %$ports];
		1321
		1322	# now $ports, $add and $del are the same as
		1323	# were originally passed by grp_mon.
		1324	...
		1325	};
		1326
		1327	=item Nodes not longer connect to all other nodes.
		1328
		1329	In AEMP 1.x, every node automatically loads the L<AnyEvent::MP::Global>
		1330	module, which in turn would create connections to all other nodes in the
		1331	network (helped by the seed nodes).
		1332
		1333	In version 2.x, global nodes still connect to all other global nodes, but
		1334	other nodes don't - now every node either is a global node itself, or
		1335	attaches itself to another global node.
		1336
		1337	If a node isn't a global node itself, then it attaches itself to one
		1338	of its seed nodes. If that seed node isn't a global node yet, it will
		1339	automatically be upgraded to a global node.
		1340
		1341	So in many cases, nothing needs to be changed - one just has to make sure
		1342	that all seed nodes are meshed together with the other seed nodes (as with
		1343	AEMP 1.x), and other nodes specify them as seed nodes. This is most easily
		1344	achieved by specifying the same set of seed nodes for all nodes in the
		1345	network.
		1346
		1347	Not opening a connection to every other node is usually an advantage,
		1348	except when you need the lower latency of an already established
		1349	connection. To ensure a node establishes a connection to another node,
		1350	you can monitor the node port (C<mon $node, ...>), which will attempt to
		1351	create the connection (and notify you when the connection fails).
		1352
		1353	=item Listener-less nodes (nodes without binds) are gone.
		1354
		1355	And are not coming back, at least not in their old form. If no C<binds>
		1356	are specified for a node, AnyEvent::MP assumes a default of C<:>.
		1357
		1358	There are vague plans to implement some form of routing domains, which
		1359	might or might not bring back listener-less nodes, but don't count on it.
		1360
		1361	The fact that most connections are now optional somewhat mitigates this,
		1362	as a node can be effectively unreachable from the outside without any
		1363	problems, as long as it isn't a global node and only reaches out to other
		1364	nodes (as opposed to being contacted from other nodes).
		1365
		1366	=item $AnyEvent::MP::Kernel::WARN has gone.
		1367
		1368	AnyEvent has acquired a logging framework (L<AnyEvent::Log>), and AEMP now
		1369	uses this, and so should your programs.
		1370
		1371	Every module now documents what kinds of messages it generates, with
		1372	AnyEvent::MP acting as a catch all.
		1373
		1374	On the positive side, this means that instead of setting
		1375	C<PERL_ANYEVENT_MP_WARNLEVEL>, you can get away by setting C<AE_VERBOSE> -
		1376	much less to type.
		1377
		1378	=back
		1379
		1380	=head1 LOGGING
		1381
		1382	AnyEvent::MP does not normally log anything by itself, but since it is the
		1383	root of the context hierarchy for AnyEvent::MP modules, it will receive
		1384	all log messages by submodules.
		1385
922	=head1 SEE ALSO	1386	=head1 SEE ALSO
923		1387
924	L<AnyEvent::MP::Intro> - a gentle introduction.	1388	L<AnyEvent::MP::Intro> - a gentle introduction.
925		1389
926	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1390	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
927		1391
928	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1392	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
929	your applications.	1393	your applications.
		1394
		1395	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
930		1396
931	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from	1397	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
932	all nodes.	1398	all nodes.
933		1399
934	L<AnyEvent>.	1400	L<AnyEvent>.

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.97 by root, Fri Oct 2 13:29:49 2009 UTC vs. Revision 1.156 by root, Sat Oct 23 03:35:49 2021 UTC

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Revision 1.97 by root, Fri Oct 2 13:29:49 2009 UTC vs.
Revision 1.156 by root, Sat Oct 23 03:35:49 2021 UTC