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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.120 by root, Sun Feb 26 11:12:54 2012 UTC vs.
Revision 1.143 by root, Fri Mar 23 17:54:36 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	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
53		56
54	bin/aemp - stable.	57	# distributed database - queries
55	AnyEvent::MP - stable API, should work.	58	db_family $family => $cb->(\%familyhash)
56	AnyEvent::MP::Intro - explains most concepts.	59	db_keys $family => $cb->(\@keys)
57	AnyEvent::MP::Kernel - mostly stable API.	60	db_values $family => $cb->(\@values)
58	AnyEvent::MP::Global - stable API.	61
		62	# distributed database - monitoring a family
		63	db_mon $family => $cb->(\%familyhash, \@added, \@changed, \@deleted)
59		64
60	=head1 DESCRIPTION	65	=head1 DESCRIPTION
61		66
62	This module (-family) implements a simple message passing framework.	67	This module (-family) implements a simple message passing framework.
63		68
…		…
82		87
83	Ports are represented by (printable) strings called "port IDs".	88	Ports are represented by (printable) strings called "port IDs".
84		89
85	=item port ID - C<nodeid#portname>	90	=item port ID - C<nodeid#portname>
86		91
87	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<#>)
88	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).
89		95
90	=item node	96	=item node
91		97
92	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,
93	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
…		…
175		181
176	=cut	182	=cut
177		183
178	package AnyEvent::MP;	184	package AnyEvent::MP;
179		185
		186	use AnyEvent::MP::Config ();
180	use AnyEvent::MP::Kernel;	187	use AnyEvent::MP::Kernel;
		188	use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID);
181		189
182	use common::sense;	190	use common::sense;
183		191
184	use Carp ();	192	use Carp ();
185		193
186	use AE ();	194	use AnyEvent ();
		195	use Guard ();
187		196
188	use base "Exporter";	197	use base "Exporter";
189		198
190	our $VERSION = '1.30';	199	our $VERSION = $AnyEvent::MP::Config::VERSION;
191		200
192	our @EXPORT = qw(	201	our @EXPORT = qw(
193	NODE $NODE *SELF node_of after	202	NODE $NODE *SELF node_of after
194	configure	203	configure
195	snd rcv mon mon_guard kil psub peval spawn cal	204	snd rcv mon mon_guard kil psub peval spawn cal
196	port	205	port
		206	db_set db_del db_reg
		207	db_mon db_family db_keys db_values
197	);	208	);
198		209
199	our $SELF;	210	our $SELF;
200		211
201	sub _self_die() {	212	sub _self_die() {
…		…
221	Before a node can talk to other nodes on the network (i.e. enter	232	Before a node can talk to other nodes on the network (i.e. enter
222	"distributed mode") it has to configure itself - the minimum a node needs	233	"distributed mode") it has to configure itself - the minimum a node needs
223	to know is its own name, and optionally it should know the addresses of	234	to know is its own name, and optionally it should know the addresses of
224	some other nodes in the network to discover other nodes.	235	some other nodes in the network to discover other nodes.
225		236
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
229	This function configures a node - it must be called exactly once (or	237	This function configures a node - it must be called exactly once (or
230	never) before calling other AnyEvent::MP functions.	238	never) before calling other AnyEvent::MP functions.
		239
		240	The key/value pairs are basically the same ones as documented for the
		241	F<aemp> command line utility (sans the set/del prefix), with these additions:
		242
		243	=over 4
		244
		245	=item norc => $boolean (default false)
		246
		247	If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not>
		248	be consulted - all configuraiton options must be specified in the
		249	C<configure> call.
		250
		251	=item force => $boolean (default false)
		252
		253	IF true, then the values specified in the C<configure> will take
		254	precedence over any values configured via the rc file. The default is for
		255	the rc file to override any options specified in the program.
		256
		257	=back
231		258
232	=over 4	259	=over 4
233		260
234	=item step 1, gathering configuration from profiles	261	=item step 1, gathering configuration from profiles
235		262
…		…
249	That means that the values specified in the profile have highest priority	276	That means that the values specified in the profile have highest priority
250	and the values specified directly via C<configure> have lowest priority,	277	and the values specified directly via C<configure> have lowest priority,
251	and can only be used to specify defaults.	278	and can only be used to specify defaults.
252		279
253	If the profile specifies a node ID, then this will become the node ID of	280	If the profile specifies a node ID, then this will become the node ID of
254	this process. If not, then the profile name will be used as node ID. The	281	this process. If not, then the profile name will be used as node ID, with
255	special node ID of C<anon/> will be replaced by a random node ID.	282	a unique randoms tring (C</%u>) appended.
		283
		284	The node ID can contain some C<%> sequences that are expanded: C<%n>
		285	is expanded to the local nodename, C<%u> is replaced by a random
		286	strign to make the node unique. For example, the F<aemp> commandline
		287	utility uses C<aemp/%n/%u> as nodename, which might expand to
		288	C<aemp/cerebro/ZQDGSIkRhEZQDGSIkRhE>.
256		289
257	=item step 2, bind listener sockets	290	=item step 2, bind listener sockets
258		291
259	The next step is to look up the binds in the profile, followed by binding	292	The next step is to look up the binds in the profile, followed by binding
260	aemp protocol listeners on all binds specified (it is possible and valid	293	aemp protocol listeners on all binds specified (it is possible and valid
…		…
277	Example: become a distributed node using the local node name as profile.	310	Example: become a distributed node using the local node name as profile.
278	This should be the most common form of invocation for "daemon"-type nodes.	311	This should be the most common form of invocation for "daemon"-type nodes.
279		312
280	configure	313	configure
281		314
282	Example: become an anonymous node. This form is often used for commandline	315	Example: become a semi-anonymous node. This form is often used for
283	clients.	316	commandline clients.
284		317
285	configure nodeid => "anon/";	318	configure nodeid => "myscript/%n/%u";
286		319
287	Example: configure a node using a profile called seed, which is suitable	320	Example: configure a node using a profile called seed, which is suitable
288	for a seed node as it binds on all local addresses on a fixed port (4040,	321	for a seed node as it binds on all local addresses on a fixed port (4040,
289	customary for aemp).	322	customary for aemp).
290		323
291	# use the aemp commandline utility	324	# use the aemp commandline utility
292	# aemp profile seed nodeid anon/ binds '*:4040'	325	# aemp profile seed binds '*:4040'
293		326
294	# then use it	327	# then use it
295	configure profile => "seed";	328	configure profile => "seed";
296		329
297	# or simply use aemp from the shell again:	330	# or simply use aemp from the shell again:
…		…
362		395
363	=cut	396	=cut
364		397
365	sub rcv($@);	398	sub rcv($@);
366		399
367	sub _kilme {	400	my $KILME = sub {
368	die "received message on port without callback";	401	(my $tag = substr $_[0], 0, 30) =~ s/([\x20-\x7e])/./g;
369	}	402	kil $SELF, unhandled_message => "no callback found for message '$tag'";
		403	};
370		404
371	sub port(;&) {	405	sub port(;&) {
372	my $id = "$UNIQ." . $ID++;	406	my $id = $UNIQ . ++$ID;
373	my $port = "$NODE#$id";	407	my $port = "$NODE#$id";
374		408
375	rcv $port, shift \|\| \&_kilme;	409	rcv $port, shift \|\| $KILME;
376		410
377	$port	411	$port
378	}	412	}
379		413
380	=item rcv $local_port, $callback->(@msg)	414	=item rcv $local_port, $callback->(@msg)
…		…
385		419
386	The global C<$SELF> (exported by this module) contains C<$port> while	420	The global C<$SELF> (exported by this module) contains C<$port> while
387	executing the callback. Runtime errors during callback execution will	421	executing the callback. Runtime errors during callback execution will
388	result in the port being C<kil>ed.	422	result in the port being C<kil>ed.
389		423
390	The default callback received all messages not matched by a more specific	424	The default callback receives all messages not matched by a more specific
391	C<tag> match.	425	C<tag> match.
392		426
393	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...	427	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
394		428
395	Register (or replace) callbacks to be called on messages starting with the	429	Register (or replace) callbacks to be called on messages starting with the
…		…
559	$res	593	$res
560	}	594	}
561	}	595	}
562	}	596	}
563		597
		598	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		599
		600	=item $guard = mon $port # kill $SELF when $port dies
		601
564	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies	602	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
565
566	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
567
568	=item $guard = mon $port # kill $SELF when $port dies
569		603
570	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies	604	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
571		605
572	Monitor the given port and do something when the port is killed or	606	Monitor the given port and do something when the port is killed or
573	messages to it were lost, and optionally return a guard that can be used	607	messages to it were lost, and optionally return a guard that can be used
574	to stop monitoring again.	608	to stop monitoring again.
575		609
		610	The first two forms distinguish between "normal" and "abnormal" kil's:
		611
		612	In the first form (another port given), if the C<$port> is C<kil>'ed with
		613	a non-empty reason, the other port (C<$rcvport>) will be kil'ed with the
		614	same reason. That is, on "normal" kil's nothing happens, while under all
		615	other conditions, the other port is killed with the same reason.
		616
		617	The second form (kill self) is the same as the first form, except that
		618	C<$rvport> defaults to C<$SELF>.
		619
		620	The remaining forms don't distinguish between "normal" and "abnormal" kil's
		621	- it's up to the callback or receiver to check whether the C<@reason> is
		622	empty and act accordingly.
		623
576	In the first form (callback), the callback is simply called with any	624	In the third form (callback), the callback is simply called with any
577	number of C<@reason> elements (no @reason means that the port was deleted	625	number of C<@reason> elements (empty @reason means that the port was deleted
578	"normally"). Note also that I<< the callback B<must> never die >>, so use	626	"normally"). Note also that I<< the callback B<must> never die >>, so use
579	C<eval> if unsure.	627	C<eval> if unsure.
580		628
581	In the second form (another port given), the other port (C<$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	629	In the last form (message), a message of the form C<$rcvport, @msg,
590	C<snd>.	630	@reason> will be C<snd>.
591		631
592	Monitoring-actions are one-shot: once messages are lost (and a monitoring	632	Monitoring-actions are one-shot: once messages are lost (and a monitoring
593	alert was raised), they are removed and will not trigger again.	633	alert was raised), they are removed and will not trigger again, even if it
		634	turns out that the port is still alive.
594		635
595	As a rule of thumb, monitoring requests should always monitor a port from	636	As a rule of thumb, monitoring requests should always monitor a remote
596	a local port (or callback). The reason is that kill messages might get	637	port locally (using a local C<$rcvport> or a callback). The reason is that
597	lost, just like any other message. Another less obvious reason is that	638	kill messages might get lost, just like any other message. Another less
598	even monitoring requests can get lost (for example, when the connection	639	obvious reason is that even monitoring requests can get lost (for example,
599	to the other node goes down permanently). When monitoring a port locally	640	when the connection to the other node goes down permanently). When
600	these problems do not exist.	641	monitoring a port locally these problems do not exist.
601		642
602	C<mon> effectively guarantees that, in the absence of hardware failures,	643	C<mon> effectively guarantees that, in the absence of hardware failures,
603	after starting the monitor, either all messages sent to the port will	644	after starting the monitor, either all messages sent to the port will
604	arrive, or the monitoring action will be invoked after possible message	645	arrive, or the monitoring action will be invoked after possible message
605	loss has been detected. No messages will be lost "in between" (after	646	loss has been detected. No messages will be lost "in between" (after
…		…
650	}	691	}
651		692
652	$node->monitor ($port, $cb);	693	$node->monitor ($port, $cb);
653		694
654	defined wantarray	695	defined wantarray
655	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })	696	and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) })
656	}	697	}
657		698
658	=item $guard = mon_guard $port, $ref, $ref...	699	=item $guard = mon_guard $port, $ref, $ref...
659		700
660	Monitors the given C<$port> and keeps the passed references. When the port	701	Monitors the given C<$port> and keeps the passed references. When the port
…		…
696	will be reported as reason C<< die => $@ >>.	737	will be reported as reason C<< die => $@ >>.
697		738
698	Transport/communication errors are reported as C<< transport_error =>	739	Transport/communication errors are reported as C<< transport_error =>
699	$message >>.	740	$message >>.
700		741
701	=cut	742	Common idioms:
		743
		744	# silently remove yourself, do not kill linked ports
		745	kil $SELF;
		746
		747	# report a failure in some detail
		748	kil $SELF, failure_mode_1 => "it failed with too high temperature";
		749
		750	# do not waste much time with killing, just die when something goes wrong
		751	open my $fh, "<file"
		752	or die "file: $!";
702		753
703	=item $port = spawn $node, $initfunc[, @initdata]	754	=item $port = spawn $node, $initfunc[, @initdata]
704		755
705	Creates a port on the node C<$node> (which can also be a port ID, in which	756	Creates a port on the node C<$node> (which can also be a port ID, in which
706	case it's the node where that port resides).	757	case it's the node where that port resides).
…		…
764	}	815	}
765		816
766	sub spawn(@) {	817	sub spawn(@) {
767	my ($nodeid, undef) = split /#/, shift, 2;	818	my ($nodeid, undef) = split /#/, shift, 2;
768		819
769	my $id = "$RUNIQ." . $ID++;	820	my $id = $RUNIQ . ++$ID;
770		821
771	$_[0] =~ /::/	822	$_[0] =~ /::/
772	or Carp::croak "spawn init function must be a fully-qualified name, caught";	823	or Carp::croak "spawn init function must be a fully-qualified name, caught";
773		824
774	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;	825	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
775		826
776	"$nodeid#$id"	827	"$nodeid#$id"
777	}	828	}
		829
778		830
779	=item after $timeout, @msg	831	=item after $timeout, @msg
780		832
781	=item after $timeout, $callback	833	=item after $timeout, $callback
782		834
…		…
797	ref $action[0]	849	ref $action[0]
798	? $action[0]()	850	? $action[0]()
799	: snd @action;	851	: snd @action;
800	};	852	};
801	}	853	}
		854
		855	#=item $cb2 = timeout $seconds, $cb[, @args]
802		856
803	=item cal $port, @msg, $callback[, $timeout]	857	=item cal $port, @msg, $callback[, $timeout]
804		858
805	A simple form of RPC - sends a message to the given C<$port> with the	859	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.	860	given contents (C<@msg>), but adds a reply port to the message.
…		…
852	$port	906	$port
853	}	907	}
854		908
855	=back	909	=back
856		910
		911	=head1 DISTRIBUTED DATABASE
		912
		913	AnyEvent::MP comes with a simple distributed database. The database will
		914	be mirrored asynchronously on all global nodes. Other nodes bind to one
		915	of the global nodes for their needs. Every node has a "local database"
		916	which contains all the values that are set locally. All local databases
		917	are merged together to form the global database, which can be queried.
		918
		919	The database structure is that of a two-level hash - the database hash
		920	contains hashes which contain values, similarly to a perl hash of hashes,
		921	i.e.:
		922
		923	$DATABASE{$family}{$subkey} = $value
		924
		925	The top level hash key is called "family", and the second-level hash key
		926	is called "subkey" or simply "key".
		927
		928	The family must be alphanumeric, i.e. start with a letter and consist
		929	of letters, digits, underscores and colons (C<[A-Za-z][A-Za-z0-9_:]*>,
		930	pretty much like Perl module names.
		931
		932	As the family namespace is global, it is recommended to prefix family names
		933	with the name of the application or module using it.
		934
		935	The subkeys must be non-empty strings, with no further restrictions.
		936
		937	The values should preferably be strings, but other perl scalars should
		938	work as well (such as C<undef>, arrays and hashes).
		939
		940	Every database entry is owned by one node - adding the same family/subkey
		941	combination on multiple nodes will not cause discomfort for AnyEvent::MP,
		942	but the result might be nondeterministic, i.e. the key might have
		943	different values on different nodes.
		944
		945	Different subkeys in the same family can be owned by different nodes
		946	without problems, and in fact, this is the common method to create worker
		947	pools. For example, a worker port for image scaling might do this:
		948
		949	db_set my_image_scalers => $port;
		950
		951	And clients looking for an image scaler will want to get the
		952	C<my_image_scalers> keys from time to time:
		953
		954	db_keys my_image_scalers => sub {
		955	@ports = @{ $_[0] };
		956	};
		957
		958	Or better yet, they want to monitor the database family, so they always
		959	have a reasonable up-to-date copy:
		960
		961	db_mon my_image_scalers => sub {
		962	@ports = keys %{ $_[0] };
		963	};
		964
		965	In general, you can set or delete single subkeys, but query and monitor
		966	whole families only.
		967
		968	If you feel the need to monitor or query a single subkey, try giving it
		969	it's own family.
		970
		971	=over
		972
		973	=item $guard = db_set $family => $subkey [=> $value]
		974
		975	Sets (or replaces) a key to the database - if C<$value> is omitted,
		976	C<undef> is used instead.
		977
		978	When called in non-void context, C<db_set> returns a guard that
		979	automatically calls C<db_del> when it is destroyed.
		980
		981	=item db_del $family => $subkey...
		982
		983	Deletes one or more subkeys from the database family.
		984
		985	=item $guard = db_reg $family => $port => $value
		986
		987	=item $guard = db_reg $family => $port
		988
		989	=item $guard = db_reg $family
		990
		991	Registers a port in the given family and optionally returns a guard to
		992	remove it.
		993
		994	This function basically does the same as:
		995
		996	db_set $family => $port => $value
		997
		998	Except that the port is monitored and automatically removed from the
		999	database family when it is kil'ed.
		1000
		1001	If C<$value> is missing, C<undef> is used. If C<$port> is missing, then
		1002	C<$SELF> is used.
		1003
		1004	This function is most useful to register a port in some port group (which
		1005	is just another name for a database family), and have it removed when the
		1006	port is gone. This works best when the port is a local port.
		1007
		1008	=cut
		1009
		1010	sub db_reg($$;$) {
		1011	my $family = shift;
		1012	my $port = @_ ? shift : $SELF;
		1013
		1014	my $clr = sub { db_del $family => $port };
		1015	mon $port, $clr;
		1016
		1017	db_set $family => $port => $_[0];
		1018
		1019	defined wantarray
		1020	and &Guard::guard ($clr)
		1021	}
		1022
		1023	=item db_family $family => $cb->(\%familyhash)
		1024
		1025	Queries the named database C<$family> and call the callback with the
		1026	family represented as a hash. You can keep and freely modify the hash.
		1027
		1028	=item db_keys $family => $cb->(\@keys)
		1029
		1030	Same as C<db_family>, except it only queries the family I<subkeys> and passes
		1031	them as array reference to the callback.
		1032
		1033	=item db_values $family => $cb->(\@values)
		1034
		1035	Same as C<db_family>, except it only queries the family I<values> and passes them
		1036	as array reference to the callback.
		1037
		1038	=item $guard = db_mon $family => $cb->(\%familyhash, \@added, \@changed, \@deleted)
		1039
		1040	Creates a monitor on the given database family. Each time a key is set
		1041	or or is deleted the callback is called with a hash containing the
		1042	database family and three lists of added, changed and deleted subkeys,
		1043	respectively. If no keys have changed then the array reference might be
		1044	C<undef> or even missing.
		1045
		1046	If not called in void context, a guard object is returned that, when
		1047	destroyed, stops the monitor.
		1048
		1049	The family hash reference and the key arrays belong to AnyEvent::MP and
		1050	B<must not be modified or stored> by the callback. When in doubt, make a
		1051	copy.
		1052
		1053	As soon as possible after the monitoring starts, the callback will be
		1054	called with the intiial contents of the family, even if it is empty,
		1055	i.e. there will always be a timely call to the callback with the current
		1056	contents.
		1057
		1058	It is possible that the callback is called with a change event even though
		1059	the subkey is already present and the value has not changed.
		1060
		1061	The monitoring stops when the guard object is destroyed.
		1062
		1063	Example: on every change to the family "mygroup", print out all keys.
		1064
		1065	my $guard = db_mon mygroup => sub {
		1066	my ($family, $a, $c, $d) = @_;
		1067	print "mygroup members: ", (join " ", keys %$family), "\n";
		1068	};
		1069
		1070	Exmaple: wait until the family "My::Module::workers" is non-empty.
		1071
		1072	my $guard; $guard = db_mon My::Module::workers => sub {
		1073	my ($family, $a, $c, $d) = @_;
		1074	return unless %$family;
		1075	undef $guard;
		1076	print "My::Module::workers now nonempty\n";
		1077	};
		1078
		1079	Example: print all changes to the family "AnyRvent::Fantasy::Module".
		1080
		1081	my $guard = db_mon AnyRvent::Fantasy::Module => sub {
		1082	my ($family, $a, $c, $d) = @_;
		1083
		1084	print "+$_=$family->{$_}\n" for @$a;
		1085	print "*$_=$family->{$_}\n" for @$c;
		1086	print "-$_=$family->{$_}\n" for @$d;
		1087	};
		1088
		1089	=cut
		1090
		1091	=back
		1092
857	=head1 AnyEvent::MP vs. Distributed Erlang	1093	=head1 AnyEvent::MP vs. Distributed Erlang
858		1094
859	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	1095	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
860	== aemp node, Erlang process == aemp port), so many of the documents and	1096	== aemp node, Erlang process == aemp port), so many of the documents and
861	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	1097	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
…		…
1015	Keeping your messages simple, concentrating on data structures rather than	1251	Keeping your messages simple, concentrating on data structures rather than
1016	objects, will keep your messages clean, tidy and efficient.	1252	objects, will keep your messages clean, tidy and efficient.
1017		1253
1018	=back	1254	=back
1019		1255
		1256	=head1 PORTING FROM AnyEvent::MP VERSION 1.X
		1257
		1258	AEMP version 2 has a few major incompatible changes compared to version 1:
		1259
		1260	=over 4
		1261
		1262	=item AnyEvent::MP::Global no longer has group management functions.
		1263
		1264	At least not officially - the grp_* functions are still exported and might
		1265	work, but they will be removed in some later release.
		1266
		1267	AnyEvent::MP now comes with a distributed database that is more
		1268	powerful. Its database families map closely to port groups, but the API
		1269	has changed (the functions are also now exported by AnyEvent::MP). Here is
		1270	a rough porting guide:
		1271
		1272	grp_reg $group, $port # old
		1273	db_reg $group, $port # new
		1274
		1275	$list = grp_get $group # old
		1276	db_keys $group, sub { my $list = shift } # new
		1277
		1278	grp_mon $group, $cb->(\@ports, $add, $del) # old
		1279	db_mon $group, $cb->(\%ports, $add, $change, $del) # new
		1280
		1281	C<grp_reg> is a no-brainer (just replace by C<db_reg>), but C<grp_get> is
		1282	no longer instant, because the local node might not have a copy of the
		1283	group. You can either modify your code to allow for a callback, or use
		1284	C<db_mon> to keep an updated copy of the group:
		1285
		1286	my $local_group_copy;
		1287	db_mon $group => sub { $local_group_copy = $_[0] };
		1288
		1289	# now "keys %$local_group_copy" always returns the most up-to-date
		1290	# list of ports in the group.
		1291
		1292	C<grp_mon> can be replaced by C<db_mon> with minor changes - C<db_mon>
		1293	passes a hash as first argument, and an extra C<$chg> argument that can be
		1294	ignored:
		1295
		1296	db_mon $group => sub {
		1297	my ($ports, $add, $chg, $lde) = @_;
		1298	$ports = [keys %$ports];
		1299
		1300	# now $ports, $add and $del are the same as
		1301	# were originally passed by grp_mon.
		1302	...
		1303	};
		1304
		1305	=item Nodes not longer connect to all other nodes.
		1306
		1307	In AEMP 1.x, every node automatically loads the L<AnyEvent::MP::Global>
		1308	module, which in turn would create connections to all other nodes in the
		1309	network (helped by the seed nodes).
		1310
		1311	In version 2.x, global nodes still connect to all other global nodes, but
		1312	other nodes don't - now every node either is a global node itself, or
		1313	attaches itself to another global node.
		1314
		1315	If a node isn't a global node itself, then it attaches itself to one
		1316	of its seed nodes. If that seed node isn't a global node yet, it will
		1317	automatically be upgraded to a global node.
		1318
		1319	So in many cases, nothing needs to be changed - one just has to make sure
		1320	that all seed nodes are meshed together with the other seed nodes (as with
		1321	AEMP 1.x), and other nodes specify them as seed nodes. This is most easily
		1322	achieved by specifying the same set of seed nodes for all nodes in the
		1323	network.
		1324
		1325	Not opening a connection to every other node is usually an advantage,
		1326	except when you need the lower latency of an already established
		1327	connection. To ensure a node establishes a connection to another node,
		1328	you can monitor the node port (C<mon $node, ...>), which will attempt to
		1329	create the connection (and notify you when the connection fails).
		1330
		1331	=item Listener-less nodes (nodes without binds) are gone.
		1332
		1333	And are not coming back, at least not in their old form. If no C<binds>
		1334	are specified for a node, AnyEvent::MP assumes a default of C<:>.
		1335
		1336	There are vague plans to implement some form of routing domains, which
		1337	might or might not bring back listener-less nodes, but don't count on it.
		1338
		1339	The fact that most connections are now optional somewhat mitigates this,
		1340	as a node can be effectively unreachable from the outside without any
		1341	problems, as long as it isn't a global node and only reaches out to other
		1342	nodes (as opposed to being contacted from other nodes).
		1343
		1344	=item $AnyEvent::MP::Kernel::WARN has gone.
		1345
		1346	AnyEvent has acquired a logging framework (L<AnyEvent::Log>), and AEMP now
		1347	uses this, and so should your programs.
		1348
		1349	Every module now documents what kinds of messages it generates, with
		1350	AnyEvent::MP acting as a catch all.
		1351
		1352	On the positive side, this means that instead of setting
		1353	C<PERL_ANYEVENT_MP_WARNLEVEL>, you can get away by setting C<AE_VERBOSE> -
		1354	much less to type.
		1355
		1356	=back
		1357
		1358	=head1 LOGGING
		1359
		1360	AnyEvent::MP does not normally log anything by itself, but sinc eit is the
		1361	root of the contetx hierarchy for AnyEvent::MP modules, it will receive
		1362	all log messages by submodules.
		1363
1020	=head1 SEE ALSO	1364	=head1 SEE ALSO
1021		1365
1022	L<AnyEvent::MP::Intro> - a gentle introduction.	1366	L<AnyEvent::MP::Intro> - a gentle introduction.
1023		1367
1024	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1368	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.120 by root, Sun Feb 26 11:12:54 2012 UTC vs.
Revision 1.143 by root, Fri Mar 23 17:54:36 2012 UTC