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

Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.121 by root, Tue Feb 28 18:37:24 2012 UTC vs.
Revision 1.142 by root, Fri Mar 23 13:44:01 2012 UTC

…		…
35	# destroy a port again	35	# destroy a port again
36	kil $port; # "normal" kill	36	kil $port; # "normal" kill
37	kil $port, my_error => "everything is broken"; # error kill	37	kil $port, my_error => "everything is broken"; # error kill
38		38
39	# monitoring	39	# monitoring
40	mon $localport, $cb->(@msg) # callback is invoked on death	40	mon $port, $cb->(@msg) # callback is invoked on death
41	mon $localport, $otherport # kill otherport on abnormal death	41	mon $port, $localport # kill localport on abnormal death
42	mon $localport, $otherport, @msg # send message on death	42	mon $port, $localport, @msg # send message on death
43		43
44	# temporarily execute code in port context	44	# temporarily execute code in port context
45	peval $port, sub { die "kill the port!" };	45	peval $port, sub { die "kill the port!" };
46		46
47	# execute callbacks in $SELF port context	47	# execute callbacks in $SELF port context
48	my $timer = AE::timer 1, 0, psub {	48	my $timer = AE::timer 1, 0, psub {
49	die "kill the port, delayed";	49	die "kill the port, delayed";
50	};	50	};
51		51
52	=head1 CURRENT STATUS
53
54	bin/aemp - stable.
55	AnyEvent::MP - stable API, should work.
56	AnyEvent::MP::Intro - explains most concepts.
57	AnyEvent::MP::Kernel - mostly stable API.
58	AnyEvent::MP::Global - stable API.
59
60	=head1 DESCRIPTION	52	=head1 DESCRIPTION
61		53
62	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
63		55
64	Despite its simplicity, you can securely message other processes running	56	Despite its simplicity, you can securely message other processes running
…		…
82		74
83	Ports are represented by (printable) strings called "port IDs".	75	Ports are represented by (printable) strings called "port IDs".
84		76
85	=item port ID - C<nodeid#portname>	77	=item port ID - C<nodeid#portname>
86		78
87	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as	79	A port ID is the concatenation of a node ID, a hash-mark (C<#>)
88	separator, and a port name (a printable string of unspecified format).	80	as separator, and a port name (a printable string of unspecified
		81	format created by AnyEvent::MP).
89		82
90	=item node	83	=item node
91		84
92	A node is a single process containing at least one port - the node port,	85	A node is a single process containing at least one port - the node port,
93	which enables nodes to manage each other remotely, and to create new	86	which enables nodes to manage each other remotely, and to create new
…		…
183		176
184	use common::sense;	177	use common::sense;
185		178
186	use Carp ();	179	use Carp ();
187		180
188	use AE ();	181	use AnyEvent ();
		182	use Guard ();
189		183
190	use base "Exporter";	184	use base "Exporter";
191		185
192	our $VERSION = $AnyEvent::MP::Config::VERSION;	186	our $VERSION = $AnyEvent::MP::Config::VERSION;
193		187
194	our @EXPORT = qw(	188	our @EXPORT = qw(
195	NODE $NODE *SELF node_of after	189	NODE $NODE *SELF node_of after
196	configure	190	configure
197	snd rcv mon mon_guard kil psub peval spawn cal	191	snd rcv mon mon_guard kil psub peval spawn cal
198	port	192	port
		193	db_set db_del db_reg
		194	db_mon db_family db_keys db_values
199	);	195	);
200		196
201	our $SELF;	197	our $SELF;
202		198
203	sub _self_die() {	199	sub _self_die() {
…		…
227		223
228	This function configures a node - it must be called exactly once (or	224	This function configures a node - it must be called exactly once (or
229	never) before calling other AnyEvent::MP functions.	225	never) before calling other AnyEvent::MP functions.
230		226
231	The key/value pairs are basically the same ones as documented for the	227	The key/value pairs are basically the same ones as documented for the
232	F<aemp> command line utility (sans the set/del prefix), with two additions:	228	F<aemp> command line utility (sans the set/del prefix), with these additions:
233		229
234	=over 4	230	=over 4
235		231
236	=item norc => $boolean (default false)	232	=item norc => $boolean (default false)
237		233
…		…
267	That means that the values specified in the profile have highest priority	263	That means that the values specified in the profile have highest priority
268	and the values specified directly via C<configure> have lowest priority,	264	and the values specified directly via C<configure> have lowest priority,
269	and can only be used to specify defaults.	265	and can only be used to specify defaults.
270		266
271	If the profile specifies a node ID, then this will become the node ID of	267	If the profile specifies a node ID, then this will become the node ID of
272	this process. If not, then the profile name will be used as node ID. The	268	this process. If not, then the profile name will be used as node ID, with
273	special node ID of C<anon/> will be replaced by a random node ID.	269	a unique randoms tring (C</%u>) appended.
		270
		271	The node ID can contain some C<%> sequences that are expanded: C<%n>
		272	is expanded to the local nodename, C<%u> is replaced by a random
		273	strign to make the node unique. For example, the F<aemp> commandline
		274	utility uses C<aemp/%n/%u> as nodename, which might expand to
		275	C<aemp/cerebro/ZQDGSIkRhEZQDGSIkRhE>.
274		276
275	=item step 2, bind listener sockets	277	=item step 2, bind listener sockets
276		278
277	The next step is to look up the binds in the profile, followed by binding	279	The next step is to look up the binds in the profile, followed by binding
278	aemp protocol listeners on all binds specified (it is possible and valid	280	aemp protocol listeners on all binds specified (it is possible and valid
…		…
295	Example: become a distributed node using the local node name as profile.	297	Example: become a distributed node using the local node name as profile.
296	This should be the most common form of invocation for "daemon"-type nodes.	298	This should be the most common form of invocation for "daemon"-type nodes.
297		299
298	configure	300	configure
299		301
300	Example: become an anonymous node. This form is often used for commandline	302	Example: become a semi-anonymous node. This form is often used for
301	clients.	303	commandline clients.
302		304
303	configure nodeid => "anon/";	305	configure nodeid => "myscript/%n/%u";
304		306
305	Example: configure a node using a profile called seed, which is suitable	307	Example: configure a node using a profile called seed, which is suitable
306	for a seed node as it binds on all local addresses on a fixed port (4040,	308	for a seed node as it binds on all local addresses on a fixed port (4040,
307	customary for aemp).	309	customary for aemp).
308		310
309	# use the aemp commandline utility	311	# use the aemp commandline utility
310	# aemp profile seed nodeid anon/ binds '*:4040'	312	# aemp profile seed binds '*:4040'
311		313
312	# then use it	314	# then use it
313	configure profile => "seed";	315	configure profile => "seed";
314		316
315	# or simply use aemp from the shell again:	317	# or simply use aemp from the shell again:
…		…
380		382
381	=cut	383	=cut
382		384
383	sub rcv($@);	385	sub rcv($@);
384		386
385	sub _kilme {	387	my $KILME = sub {
386	die "received message on port without callback";	388	(my $tag = substr $_[0], 0, 30) =~ s/([\x20-\x7e])/./g;
387	}	389	kil $SELF, unhandled_message => "no callback found for message '$tag'";
		390	};
388		391
389	sub port(;&) {	392	sub port(;&) {
390	my $id = "$UNIQ." . ++$ID;	393	my $id = $UNIQ . ++$ID;
391	my $port = "$NODE#$id";	394	my $port = "$NODE#$id";
392		395
393	rcv $port, shift \|\| \&_kilme;	396	rcv $port, shift \|\| $KILME;
394		397
395	$port	398	$port
396	}	399	}
397		400
398	=item rcv $local_port, $callback->(@msg)	401	=item rcv $local_port, $callback->(@msg)
…		…
403		406
404	The global C<$SELF> (exported by this module) contains C<$port> while	407	The global C<$SELF> (exported by this module) contains C<$port> while
405	executing the callback. Runtime errors during callback execution will	408	executing the callback. Runtime errors during callback execution will
406	result in the port being C<kil>ed.	409	result in the port being C<kil>ed.
407		410
408	The default callback received all messages not matched by a more specific	411	The default callback receives all messages not matched by a more specific
409	C<tag> match.	412	C<tag> match.
410		413
411	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...	414	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
412		415
413	Register (or replace) callbacks to be called on messages starting with the	416	Register (or replace) callbacks to be called on messages starting with the
…		…
577	$res	580	$res
578	}	581	}
579	}	582	}
580	}	583	}
581		584
		585	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		586
		587	=item $guard = mon $port # kill $SELF when $port dies
		588
582	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies	589	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
583
584	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
585
586	=item $guard = mon $port # kill $SELF when $port dies
587		590
588	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies	591	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
589		592
590	Monitor the given port and do something when the port is killed or	593	Monitor the given port and do something when the port is killed or
591	messages to it were lost, and optionally return a guard that can be used	594	messages to it were lost, and optionally return a guard that can be used
592	to stop monitoring again.	595	to stop monitoring again.
593		596
		597	The first two forms distinguish between "normal" and "abnormal" kil's:
		598
		599	In the first form (another port given), if the C<$port> is C<kil>'ed with
		600	a non-empty reason, the other port (C<$rcvport>) will be kil'ed with the
		601	same reason. That is, on "normal" kil's nothing happens, while under all
		602	other conditions, the other port is killed with the same reason.
		603
		604	The second form (kill self) is the same as the first form, except that
		605	C<$rvport> defaults to C<$SELF>.
		606
		607	The remaining forms don't distinguish between "normal" and "abnormal" kil's
		608	- it's up to the callback or receiver to check whether the C<@reason> is
		609	empty and act accordingly.
		610
594	In the first form (callback), the callback is simply called with any	611	In the third form (callback), the callback is simply called with any
595	number of C<@reason> elements (no @reason means that the port was deleted	612	number of C<@reason> elements (empty @reason means that the port was deleted
596	"normally"). Note also that I<< the callback B<must> never die >>, so use	613	"normally"). Note also that I<< the callback B<must> never die >>, so use
597	C<eval> if unsure.	614	C<eval> if unsure.
598		615
599	In the second form (another port given), the other port (C<$rcvport>)
600	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
601	"normal" kils nothing happens, while under all other conditions, the other
602	port is killed with the same reason.
603
604	The third form (kill self) is the same as the second form, except that
605	C<$rvport> defaults to C<$SELF>.
606
607	In the last form (message), a message of the form C<@msg, @reason> will be	616	In the last form (message), a message of the form C<$rcvport, @msg,
608	C<snd>.	617	@reason> will be C<snd>.
609		618
610	Monitoring-actions are one-shot: once messages are lost (and a monitoring	619	Monitoring-actions are one-shot: once messages are lost (and a monitoring
611	alert was raised), they are removed and will not trigger again.	620	alert was raised), they are removed and will not trigger again, even if it
		621	turns out that the port is still alive.
612		622
613	As a rule of thumb, monitoring requests should always monitor a port from	623	As a rule of thumb, monitoring requests should always monitor a remote
614	a local port (or callback). The reason is that kill messages might get	624	port locally (using a local C<$rcvport> or a callback). The reason is that
615	lost, just like any other message. Another less obvious reason is that	625	kill messages might get lost, just like any other message. Another less
616	even monitoring requests can get lost (for example, when the connection	626	obvious reason is that even monitoring requests can get lost (for example,
617	to the other node goes down permanently). When monitoring a port locally	627	when the connection to the other node goes down permanently). When
618	these problems do not exist.	628	monitoring a port locally these problems do not exist.
619		629
620	C<mon> effectively guarantees that, in the absence of hardware failures,	630	C<mon> effectively guarantees that, in the absence of hardware failures,
621	after starting the monitor, either all messages sent to the port will	631	after starting the monitor, either all messages sent to the port will
622	arrive, or the monitoring action will be invoked after possible message	632	arrive, or the monitoring action will be invoked after possible message
623	loss has been detected. No messages will be lost "in between" (after	633	loss has been detected. No messages will be lost "in between" (after
…		…
668	}	678	}
669		679
670	$node->monitor ($port, $cb);	680	$node->monitor ($port, $cb);
671		681
672	defined wantarray	682	defined wantarray
673	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })	683	and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) })
674	}	684	}
675		685
676	=item $guard = mon_guard $port, $ref, $ref...	686	=item $guard = mon_guard $port, $ref, $ref...
677		687
678	Monitors the given C<$port> and keeps the passed references. When the port	688	Monitors the given C<$port> and keeps the passed references. When the port
…		…
714	will be reported as reason C<< die => $@ >>.	724	will be reported as reason C<< die => $@ >>.
715		725
716	Transport/communication errors are reported as C<< transport_error =>	726	Transport/communication errors are reported as C<< transport_error =>
717	$message >>.	727	$message >>.
718		728
719	=cut	729	Common idioms:
		730
		731	# silently remove yourself, do not kill linked ports
		732	kil $SELF;
		733
		734	# report a failure in some detail
		735	kil $SELF, failure_mode_1 => "it failed with too high temperature";
		736
		737	# do not waste much time with killing, just die when something goes wrong
		738	open my $fh, "<file"
		739	or die "file: $!";
720		740
721	=item $port = spawn $node, $initfunc[, @initdata]	741	=item $port = spawn $node, $initfunc[, @initdata]
722		742
723	Creates a port on the node C<$node> (which can also be a port ID, in which	743	Creates a port on the node C<$node> (which can also be a port ID, in which
724	case it's the node where that port resides).	744	case it's the node where that port resides).
…		…
782	}	802	}
783		803
784	sub spawn(@) {	804	sub spawn(@) {
785	my ($nodeid, undef) = split /#/, shift, 2;	805	my ($nodeid, undef) = split /#/, shift, 2;
786		806
787	my $id = "$RUNIQ." . ++$ID;	807	my $id = $RUNIQ . ++$ID;
788		808
789	$_[0] =~ /::/	809	$_[0] =~ /::/
790	or Carp::croak "spawn init function must be a fully-qualified name, caught";	810	or Carp::croak "spawn init function must be a fully-qualified name, caught";
791		811
792	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;	812	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
…		…
816	ref $action[0]	836	ref $action[0]
817	? $action[0]()	837	? $action[0]()
818	: snd @action;	838	: snd @action;
819	};	839	};
820	}	840	}
		841
		842	#=item $cb2 = timeout $seconds, $cb[, @args]
821		843
822	=item cal $port, @msg, $callback[, $timeout]	844	=item cal $port, @msg, $callback[, $timeout]
823		845
824	A simple form of RPC - sends a message to the given C<$port> with the	846	A simple form of RPC - sends a message to the given C<$port> with the
825	given contents (C<@msg>), but adds a reply port to the message.	847	given contents (C<@msg>), but adds a reply port to the message.
…		…
871	$port	893	$port
872	}	894	}
873		895
874	=back	896	=back
875		897
		898	=head1 DISTRIBUTED DATABASE
		899
		900	AnyEvent::MP comes with a simple distributed database. The database will
		901	be mirrored asynchronously on all global nodes. Other nodes bind to one
		902	of the global nodes for their needs. Every node has a "local database"
		903	which contains all the values that are set locally. All local databases
		904	are merged together to form the global database, which can be queried.
		905
		906	The database structure is that of a two-level hash - the database hash
		907	contains hashes which contain values, similarly to a perl hash of hashes,
		908	i.e.:
		909
		910	$DATABASE{$family}{$subkey} = $value
		911
		912	The top level hash key is called "family", and the second-level hash key
		913	is called "subkey" or simply "key".
		914
		915	The family must be alphanumeric, i.e. start with a letter and consist
		916	of letters, digits, underscores and colons (C<[A-Za-z][A-Za-z0-9_:]*>,
		917	pretty much like Perl module names.
		918
		919	As the family namespace is global, it is recommended to prefix family names
		920	with the name of the application or module using it.
		921
		922	The subkeys must be non-empty strings, with no further restrictions.
		923
		924	The values should preferably be strings, but other perl scalars should
		925	work as well (such as C<undef>, arrays and hashes).
		926
		927	Every database entry is owned by one node - adding the same family/subkey
		928	combination on multiple nodes will not cause discomfort for AnyEvent::MP,
		929	but the result might be nondeterministic, i.e. the key might have
		930	different values on different nodes.
		931
		932	Different subkeys in the same family can be owned by different nodes
		933	without problems, and in fact, this is the common method to create worker
		934	pools. For example, a worker port for image scaling might do this:
		935
		936	db_set my_image_scalers => $port;
		937
		938	And clients looking for an image scaler will want to get the
		939	C<my_image_scalers> keys from time to time:
		940
		941	db_keys my_image_scalers => sub {
		942	@ports = @{ $_[0] };
		943	};
		944
		945	Or better yet, they want to monitor the database family, so they always
		946	have a reasonable up-to-date copy:
		947
		948	db_mon my_image_scalers => sub {
		949	@ports = keys %{ $_[0] };
		950	};
		951
		952	In general, you can set or delete single subkeys, but query and monitor
		953	whole families only.
		954
		955	If you feel the need to monitor or query a single subkey, try giving it
		956	it's own family.
		957
		958	=over
		959
		960	=item $guard = db_set $family => $subkey [=> $value]
		961
		962	Sets (or replaces) a key to the database - if C<$value> is omitted,
		963	C<undef> is used instead.
		964
		965	When called in non-void context, C<db_set> returns a guard that
		966	automatically calls C<db_del> when it is destroyed.
		967
		968	=item db_del $family => $subkey...
		969
		970	Deletes one or more subkeys from the database family.
		971
		972	=item $guard = db_reg $family => $port => $value
		973
		974	=item $guard = db_reg $family => $port
		975
		976	=item $guard = db_reg $family
		977
		978	Registers a port in the given family and optionally returns a guard to
		979	remove it.
		980
		981	This function basically does the same as:
		982
		983	db_set $family => $port => $value
		984
		985	Except that the port is monitored and automatically removed from the
		986	database family when it is kil'ed.
		987
		988	If C<$value> is missing, C<undef> is used. If C<$port> is missing, then
		989	C<$SELF> is used.
		990
		991	This function is most useful to register a port in some port group (which
		992	is just another name for a database family), and have it removed when the
		993	port is gone. This works best when the port is a local port.
		994
		995	=cut
		996
		997	sub db_reg($$;$) {
		998	my $family = shift;
		999	my $port = @_ ? shift : $SELF;
		1000
		1001	my $clr = sub { db_del $family => $port };
		1002	mon $port, $clr;
		1003
		1004	db_set $family => $port => $_[0];
		1005
		1006	defined wantarray
		1007	and &Guard::guard ($clr)
		1008	}
		1009
		1010	=item db_family $family => $cb->(\%familyhash)
		1011
		1012	Queries the named database C<$family> and call the callback with the
		1013	family represented as a hash. You can keep and freely modify the hash.
		1014
		1015	=item db_keys $family => $cb->(\@keys)
		1016
		1017	Same as C<db_family>, except it only queries the family I<subkeys> and passes
		1018	them as array reference to the callback.
		1019
		1020	=item db_values $family => $cb->(\@values)
		1021
		1022	Same as C<db_family>, except it only queries the family I<values> and passes them
		1023	as array reference to the callback.
		1024
		1025	=item $guard = db_mon $family => $cb->($familyhash, \@added, \@changed, \@deleted)
		1026
		1027	Creates a monitor on the given database family. Each time a key is set
		1028	or or is deleted the callback is called with a hash containing the
		1029	database family and three lists of added, changed and deleted subkeys,
		1030	respectively. If no keys have changed then the array reference might be
		1031	C<undef> or even missing.
		1032
		1033	If not called in void context, a guard object is returned that, when
		1034	destroyed, stops the monitor.
		1035
		1036	The family hash reference and the key arrays belong to AnyEvent::MP and
		1037	B<must not be modified or stored> by the callback. When in doubt, make a
		1038	copy.
		1039
		1040	As soon as possible after the monitoring starts, the callback will be
		1041	called with the intiial contents of the family, even if it is empty,
		1042	i.e. there will always be a timely call to the callback with the current
		1043	contents.
		1044
		1045	It is possible that the callback is called with a change event even though
		1046	the subkey is already present and the value has not changed.
		1047
		1048	The monitoring stops when the guard object is destroyed.
		1049
		1050	Example: on every change to the family "mygroup", print out all keys.
		1051
		1052	my $guard = db_mon mygroup => sub {
		1053	my ($family, $a, $c, $d) = @_;
		1054	print "mygroup members: ", (join " ", keys %$family), "\n";
		1055	};
		1056
		1057	Exmaple: wait until the family "My::Module::workers" is non-empty.
		1058
		1059	my $guard; $guard = db_mon My::Module::workers => sub {
		1060	my ($family, $a, $c, $d) = @_;
		1061	return unless %$family;
		1062	undef $guard;
		1063	print "My::Module::workers now nonempty\n";
		1064	};
		1065
		1066	Example: print all changes to the family "AnyRvent::Fantasy::Module".
		1067
		1068	my $guard = db_mon AnyRvent::Fantasy::Module => sub {
		1069	my ($family, $a, $c, $d) = @_;
		1070
		1071	print "+$_=$family->{$_}\n" for @$a;
		1072	print "*$_=$family->{$_}\n" for @$c;
		1073	print "-$_=$family->{$_}\n" for @$d;
		1074	};
		1075
		1076	=cut
		1077
		1078	=back
		1079
876	=head1 AnyEvent::MP vs. Distributed Erlang	1080	=head1 AnyEvent::MP vs. Distributed Erlang
877		1081
878	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	1082	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
879	== aemp node, Erlang process == aemp port), so many of the documents and	1083	== aemp node, Erlang process == aemp port), so many of the documents and
880	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	1084	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
…		…
1034	Keeping your messages simple, concentrating on data structures rather than	1238	Keeping your messages simple, concentrating on data structures rather than
1035	objects, will keep your messages clean, tidy and efficient.	1239	objects, will keep your messages clean, tidy and efficient.
1036		1240
1037	=back	1241	=back
1038		1242
		1243	=head1 PORTING FROM AnyEvent::MP VERSION 1.X
		1244
		1245	AEMP version 2 has a few major incompatible changes compared to version 1:
		1246
		1247	=over 4
		1248
		1249	=item AnyEvent::MP::Global no longer has group management functions.
		1250
		1251	At least not officially - the grp_* functions are still exported and might
		1252	work, but they will be removed in some later release.
		1253
		1254	AnyEvent::MP now comes with a distributed database that is more
		1255	powerful. Its database families map closely to port groups, but the API
		1256	has changed (the functions are also now exported by AnyEvent::MP). Here is
		1257	a rough porting guide:
		1258
		1259	grp_reg $group, $port # old
		1260	db_reg $group, $port # new
		1261
		1262	$list = grp_get $group # old
		1263	db_keys $group, sub { my $list = shift } # new
		1264
		1265	grp_mon $group, $cb->(\@ports, $add, $del) # old
		1266	db_mon $group, $cb->(\%ports, $add, $change, $del) # new
		1267
		1268	C<grp_reg> is a no-brainer (just replace by C<db_reg>), but C<grp_get> is
		1269	no longer instant, because the local node might not have a copy of the
		1270	group. You can either modify your code to allow for a callback, or use
		1271	C<db_mon> to keep an updated copy of the group:
		1272
		1273	my $local_group_copy;
		1274	db_mon $group => sub { $local_group_copy = $_[0] };
		1275
		1276	# now "keys %$local_group_copy" always returns the most up-to-date
		1277	# list of ports in the group.
		1278
		1279	C<grp_mon> can be replaced by C<db_mon> with minor changes - C<db_mon>
		1280	passes a hash as first argument, and an extra C<$chg> argument that can be
		1281	ignored:
		1282
		1283	db_mon $group => sub {
		1284	my ($ports, $add, $chg, $lde) = @_;
		1285	$ports = [keys %$ports];
		1286
		1287	# now $ports, $add and $del are the same as
		1288	# were originally passed by grp_mon.
		1289	...
		1290	};
		1291
		1292	=item Nodes not longer connect to all other nodes.
		1293
		1294	In AEMP 1.x, every node automatically loads the L<AnyEvent::MP::Global>
		1295	module, which in turn would create connections to all other nodes in the
		1296	network (helped by the seed nodes).
		1297
		1298	In version 2.x, global nodes still connect to all other global nodes, but
		1299	other nodes don't - now every node either is a global node itself, or
		1300	attaches itself to another global node.
		1301
		1302	If a node isn't a global node itself, then it attaches itself to one
		1303	of its seed nodes. If that seed node isn't a global node yet, it will
		1304	automatically be upgraded to a global node.
		1305
		1306	So in many cases, nothing needs to be changed - one just has to make sure
		1307	that all seed nodes are meshed together with the other seed nodes (as with
		1308	AEMP 1.x), and other nodes specify them as seed nodes. This is most easily
		1309	achieved by specifying the same set of seed nodes for all nodes in the
		1310	network.
		1311
		1312	Not opening a connection to every other node is usually an advantage,
		1313	except when you need the lower latency of an already established
		1314	connection. To ensure a node establishes a connection to another node,
		1315	you can monitor the node port (C<mon $node, ...>), which will attempt to
		1316	create the connection (and notify you when the connection fails).
		1317
		1318	=item Listener-less nodes (nodes without binds) are gone.
		1319
		1320	And are not coming back, at least not in their old form. If no C<binds>
		1321	are specified for a node, AnyEvent::MP assumes a default of C<:>.
		1322
		1323	There are vague plans to implement some form of routing domains, which
		1324	might or might not bring back listener-less nodes, but don't count on it.
		1325
		1326	The fact that most connections are now optional somewhat mitigates this,
		1327	as a node can be effectively unreachable from the outside without any
		1328	problems, as long as it isn't a global node and only reaches out to other
		1329	nodes (as opposed to being contacted from other nodes).
		1330
		1331	=item $AnyEvent::MP::Kernel::WARN has gone.
		1332
		1333	AnyEvent has acquired a logging framework (L<AnyEvent::Log>), and AEMP now
		1334	uses this, and so should your programs.
		1335
		1336	Every module now documents what kinds of messages it generates, with
		1337	AnyEvent::MP acting as a catch all.
		1338
		1339	On the positive side, this means that instead of setting
		1340	C<PERL_ANYEVENT_MP_WARNLEVEL>, you can get away by setting C<AE_VERBOSE> -
		1341	much less to type.
		1342
		1343	=back
		1344
		1345	=head1 LOGGING
		1346
		1347	AnyEvent::MP does not normally log anything by itself, but sinc eit is the
		1348	root of the contetx hierarchy for AnyEvent::MP modules, it will receive
		1349	all log messages by submodules.
		1350
1039	=head1 SEE ALSO	1351	=head1 SEE ALSO
1040		1352
1041	L<AnyEvent::MP::Intro> - a gentle introduction.	1353	L<AnyEvent::MP::Intro> - a gentle introduction.
1042		1354
1043	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1355	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.

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Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.121 by root, Tue Feb 28 18:37:24 2012 UTC vs.
Revision 1.142 by root, Fri Mar 23 13:44:01 2012 UTC