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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.127 by root, Sat Mar 3 20:35:10 2012 UTC vs.
Revision 1.151 by root, Wed Aug 17 19:45:36 2016 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
…		…
113	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
114	endpoints - binds.	119	endpoints - binds.
115		120
116	Currently, only standard C<ip:port> specifications can be used, which	121	Currently, only standard C<ip:port> specifications can be used, which
117	specify TCP ports to listen on. So a bind is basically just a tcp socket	122	specify TCP ports to listen on. So a bind is basically just a tcp socket
118	in listening mode thta accepts conenctions form other nodes.	123	in listening mode that accepts connections from other nodes.
119		124
120	=item seed nodes	125	=item seed nodes
121		126
122	When a node starts, it knows nothing about the network it is in - it	127	When a node starts, it knows nothing about the network it is in - it
123	needs to connect to at least one other node that is already in the	128	needs to connect to at least one other node that is already in the
124	network. These other nodes are called "seed nodes".	129	network. These other nodes are called "seed nodes".
125		130
126	Seed nodes themselves are not special - they are seed nodes only because	131	Seed nodes themselves are not special - they are seed nodes only because
127	some other node I<uses> them as such, but any node can be used as seed	132	some other node I<uses> them as such, but any node can be used as seed
128	node for other nodes, and eahc node cna use a different set of seed nodes.	133	node for other nodes, and eahc node can use a different set of seed nodes.
129		134
130	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
131	maintain the network - all nodes using the same seed node form are part of	136	maintain the network - all nodes using the same seed node are part of the
132	the same network. If a network is split into multiple subnets because e.g.	137	same network. If a network is split into multiple subnets because e.g. the
133	the network link between the parts goes down, then using the same seed	138	network link between the parts goes down, then using the same seed nodes
134	nodes for all nodes ensures that eventually the subnets get merged again.	139	for all nodes ensures that eventually the subnets get merged again.
135		140
136	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
137	should always be available. They should also be relatively responsive - a	142	should always be available. They should also be relatively responsive - a
138	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.
139		144
…		…
163		168
164	Any node that loads the L<AnyEvent::MP::Global> module becomes a global	169	Any node that loads the L<AnyEvent::MP::Global> module becomes a global
165	node and tries to keep connections to all other nodes. So while it can	170	node and tries to keep connections to all other nodes. So while it can
166	make sense to make every node "global" in small networks, it usually makes	171	make sense to make every node "global" in small networks, it usually makes
167	sense to only make seed nodes into global nodes in large networks (nodes	172	sense to only make seed nodes into global nodes in large networks (nodes
168	keep connections to seed nodes and global nodes, so makign them the same	173	keep connections to seed nodes and global nodes, so making them the same
169	reduces overhead).	174	reduces overhead).
170		175
171	=back	176	=back
172		177
173	=head1 VARIABLES/FUNCTIONS	178	=head1 VARIABLES/FUNCTIONS
…		…
178		183
179	package AnyEvent::MP;	184	package AnyEvent::MP;
180		185
181	use AnyEvent::MP::Config ();	186	use AnyEvent::MP::Config ();
182	use AnyEvent::MP::Kernel;	187	use AnyEvent::MP::Kernel;
183	use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID);	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	);
184		199
185	use common::sense;	200	use common::sense;
186		201
187	use Carp ();	202	use Carp ();
188		203
189	use AE ();	204	use AnyEvent ();
190	use Guard ();	205	use Guard ();
191		206
192	use base "Exporter";	207	use base "Exporter";
193		208
194	our $VERSION = $AnyEvent::MP::Config::VERSION;	209	our $VERSION = $AnyEvent::MP::Config::VERSION;
195		210
196	our @EXPORT = qw(	211	our @EXPORT = qw(
197	NODE $NODE *SELF node_of after	212	NODE $NODE
198	configure	213	configure
		214	node_of port_is_local
		215	snd kil
		216	db_set db_del
		217	db_mon db_family db_keys db_values
		218
		219	*SELF
		220
199	snd rcv mon mon_guard kil psub peval spawn cal	221	port rcv mon mon_guard psub peval spawn cal
200	port
201	db_set db_del db_reg	222	db_set db_del db_reg
		223	db_mon db_family db_keys db_values
		224
		225	after
202	);	226	);
203		227
204	our $SELF;	228	our $SELF;
205		229
206	sub _self_die() {	230	sub _self_die() {
…		…
217		241
218	=item $nodeid = node_of $port	242	=item $nodeid = node_of $port
219		243
220	Extracts and returns the node ID from a port ID or a node ID.	244	Extracts and returns the node ID from a port ID or a node ID.
221		245
		246	=item $is_local = port_is_local $port
		247
		248	Returns true iff the port is a local port.
		249
222	=item configure $profile, key => value...	250	=item configure $profile, key => value...
223		251
224	=item configure key => value...	252	=item configure key => value...
225		253
226	Before a node can talk to other nodes on the network (i.e. enter	254	Before a node can talk to other nodes on the network (i.e. enter
…		…
237	=over 4	265	=over 4
238		266
239	=item norc => $boolean (default false)	267	=item norc => $boolean (default false)
240		268
241	If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not>	269	If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not>
242	be consulted - all configuraiton options must be specified in the	270	be consulted - all configuration options must be specified in the
243	C<configure> call.	271	C<configure> call.
244		272
245	=item force => $boolean (default false)	273	=item force => $boolean (default false)
246		274
247	IF true, then the values specified in the C<configure> will take	275	IF true, then the values specified in the C<configure> will take
248	precedence over any values configured via the rc file. The default is for	276	precedence over any values configured via the rc file. The default is for
249	the rc file to override any options specified in the program.	277	the rc file to override any options specified in the program.
250
251	=item secure => $pass->($nodeid)
252
253	In addition to specifying a boolean, you can specify a code reference that
254	is called for every remote execution attempt - the execution request is
255	granted iff the callback returns a true value.
256
257	See F<semp setsecure> for more info.
258		278
259	=back	279	=back
260		280
261	=over 4	281	=over 4
262		282
…		…
291		311
292	=item step 2, bind listener sockets	312	=item step 2, bind listener sockets
293		313
294	The next step is to look up the binds in the profile, followed by binding	314	The next step is to look up the binds in the profile, followed by binding
295	aemp protocol listeners on all binds specified (it is possible and valid	315	aemp protocol listeners on all binds specified (it is possible and valid
296	to have no binds, meaning that the node cannot be contacted form the	316	to have no binds, meaning that the node cannot be contacted from the
297	outside. This means the node cannot talk to other nodes that also have no	317	outside. This means the node cannot talk to other nodes that also have no
298	binds, but it can still talk to all "normal" nodes).	318	binds, but it can still talk to all "normal" nodes).
299		319
300	If the profile does not specify a binds list, then a default of C<*> is	320	If the profile does not specify a binds list, then a default of C<*> is
301	used, meaning the node will bind on a dynamically-assigned port on every	321	used, meaning the node will bind on a dynamically-assigned port on every
…		…
397		417
398	=cut	418	=cut
399		419
400	sub rcv($@);	420	sub rcv($@);
401		421
402	sub _kilme {	422	my $KILME = sub {
403	die "received message on port without callback";	423	(my $tag = substr $_[0], 0, 30) =~ s/([^\x20-\x7e])/./g;
404	}	424	kil $SELF, unhandled_message => "no callback found for message '$tag'";
		425	};
405		426
406	sub port(;&) {	427	sub port(;&) {
407	my $id = $UNIQ . ++$ID;	428	my $id = $UNIQ . ++$ID;
408	my $port = "$NODE#$id";	429	my $port = "$NODE#$id";
409		430
410	rcv $port, shift \|\| \&_kilme;	431	rcv $port, shift \|\| $KILME;
411		432
412	$port	433	$port
413	}	434	}
414		435
415	=item rcv $local_port, $callback->(@msg)	436	=item rcv $local_port, $callback->(@msg)
…		…
420		441
421	The global C<$SELF> (exported by this module) contains C<$port> while	442	The global C<$SELF> (exported by this module) contains C<$port> while
422	executing the callback. Runtime errors during callback execution will	443	executing the callback. Runtime errors during callback execution will
423	result in the port being C<kil>ed.	444	result in the port being C<kil>ed.
424		445
425	The default callback received all messages not matched by a more specific	446	The default callback receives all messages not matched by a more specific
426	C<tag> match.	447	C<tag> match.
427		448
428	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...	449	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
429		450
430	Register (or replace) callbacks to be called on messages starting with the	451	Register (or replace) callbacks to be called on messages starting with the
…		…
465		486
466	sub rcv($@) {	487	sub rcv($@) {
467	my $port = shift;	488	my $port = shift;
468	my ($nodeid, $portid) = split /#/, $port, 2;	489	my ($nodeid, $portid) = split /#/, $port, 2;
469		490
470	$NODE{$nodeid} == $NODE{""}	491	$nodeid eq $NODE
471	or Carp::croak "$port: rcv can only be called on local ports, caught";	492	or Carp::croak "$port: rcv can only be called on local ports, caught";
472		493
473	while (@_) {	494	while (@_) {
474	if (ref $_[0]) {	495	if (ref $_[0]) {
475	if (my $self = $PORT_DATA{$portid}) {	496	if (my $self = $PORT_DATA{$portid}) {
…		…
518	$port	539	$port
519	}	540	}
520		541
521	=item peval $port, $coderef[, @args]	542	=item peval $port, $coderef[, @args]
522		543
523	Evaluates the given C<$codref> within the contetx of C<$port>, that is,	544	Evaluates the given C<$codref> within the context of C<$port>, that is,
524	when the code throews an exception the C<$port> will be killed.	545	when the code throws an exception the C<$port> will be killed.
525		546
526	Any remaining args will be passed to the callback. Any return values will	547	Any remaining args will be passed to the callback. Any return values will
527	be returned to the caller.	548	be returned to the caller.
528		549
529	This is useful when you temporarily want to execute code in the context of	550	This is useful when you temporarily want to execute code in the context of
…		…
594	$res	615	$res
595	}	616	}
596	}	617	}
597	}	618	}
598		619
		620	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		621
		622	=item $guard = mon $port # kill $SELF when $port dies
		623
599	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies	624	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
600
601	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
602
603	=item $guard = mon $port # kill $SELF when $port dies
604		625
605	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies	626	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
606		627
607	Monitor the given port and do something when the port is killed or	628	Monitor the given port and do something when the port is killed or
608	messages to it were lost, and optionally return a guard that can be used	629	messages to it were lost, and optionally return a guard that can be used
609	to stop monitoring again.	630	to stop monitoring again.
610		631
		632	The first two forms distinguish between "normal" and "abnormal" kil's:
		633
		634	In the first form (another port given), if the C<$port> is C<kil>'ed with
		635	a non-empty reason, the other port (C<$rcvport>) will be kil'ed with the
		636	same reason. That is, on "normal" kil's nothing happens, while under all
		637	other conditions, the other port is killed with the same reason.
		638
		639	The second form (kill self) is the same as the first form, except that
		640	C<$rvport> defaults to C<$SELF>.
		641
		642	The remaining forms don't distinguish between "normal" and "abnormal" kil's
		643	- it's up to the callback or receiver to check whether the C<@reason> is
		644	empty and act accordingly.
		645
611	In the first form (callback), the callback is simply called with any	646	In the third form (callback), the callback is simply called with any
612	number of C<@reason> elements (no @reason means that the port was deleted	647	number of C<@reason> elements (empty @reason means that the port was deleted
613	"normally"). Note also that I<< the callback B<must> never die >>, so use	648	"normally"). Note also that I<< the callback B<must> never die >>, so use
614	C<eval> if unsure.	649	C<eval> if unsure.
615		650
616	In the second form (another port given), the other port (C<$rcvport>)
617	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
618	"normal" kils nothing happens, while under all other conditions, the other
619	port is killed with the same reason.
620
621	The third form (kill self) is the same as the second form, except that
622	C<$rvport> defaults to C<$SELF>.
623
624	In the last form (message), a message of the form C<@msg, @reason> will be	651	In the last form (message), a message of the form C<$rcvport, @msg,
625	C<snd>.	652	@reason> will be C<snd>.
626		653
627	Monitoring-actions are one-shot: once messages are lost (and a monitoring	654	Monitoring-actions are one-shot: once messages are lost (and a monitoring
628	alert was raised), they are removed and will not trigger again.	655	alert was raised), they are removed and will not trigger again, even if it
		656	turns out that the port is still alive.
629		657
630	As a rule of thumb, monitoring requests should always monitor a port from	658	As a rule of thumb, monitoring requests should always monitor a remote
631	a local port (or callback). The reason is that kill messages might get	659	port locally (using a local C<$rcvport> or a callback). The reason is that
632	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
633	even monitoring requests can get lost (for example, when the connection	661	obvious reason is that even monitoring requests can get lost (for example,
634	to the other node goes down permanently). When monitoring a port locally	662	when the connection to the other node goes down permanently). When
635	these problems do not exist.	663	monitoring a port locally these problems do not exist.
636		664
637	C<mon> effectively guarantees that, in the absence of hardware failures,	665	C<mon> effectively guarantees that, in the absence of hardware failures,
638	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
639	arrive, or the monitoring action will be invoked after possible message	667	arrive, or the monitoring action will be invoked after possible message
640	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
…		…
731	will be reported as reason C<< die => $@ >>.	759	will be reported as reason C<< die => $@ >>.
732		760
733	Transport/communication errors are reported as C<< transport_error =>	761	Transport/communication errors are reported as C<< transport_error =>
734	$message >>.	762	$message >>.
735		763
736	=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: $!";
737		775
738	=item $port = spawn $node, $initfunc[, @initdata]	776	=item $port = spawn $node, $initfunc[, @initdata]
739		777
740	Creates a port on the node C<$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
741	case it's the node where that port resides).	779	case it's the node where that port resides).
…		…
833	ref $action[0]	871	ref $action[0]
834	? $action[0]()	872	? $action[0]()
835	: snd @action;	873	: snd @action;
836	};	874	};
837	}	875	}
		876
		877	#=item $cb2 = timeout $seconds, $cb[, @args]
838		878
839	=item cal $port, @msg, $callback[, $timeout]	879	=item cal $port, @msg, $callback[, $timeout]
840		880
841	A simple form of RPC - sends a message to the given C<$port> with the	881	A simple form of RPC - sends a message to the given C<$port> with the
842	given contents (C<@msg>), but adds a reply port to the message.	882	given contents (C<@msg>), but adds a reply port to the message.
…		…
891	=back	931	=back
892		932
893	=head1 DISTRIBUTED DATABASE	933	=head1 DISTRIBUTED DATABASE
894		934
895	AnyEvent::MP comes with a simple distributed database. The database will	935	AnyEvent::MP comes with a simple distributed database. The database will
896	be mirrored asynchronously at all global nodes. Other nodes bind to one of	936	be mirrored asynchronously on all global nodes. Other nodes bind to one
897	the global nodes for their needs.	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.
898		940
899	The database consists of a two-level hash - a hash contains a hash which	941	The database structure is that of a two-level hash - the database hash
900	contains values.	942	contains hashes which contain values, similarly to a perl hash of hashes,
		943	i.e.:
		944
		945	$DATABASE{$family}{$subkey} = $value
901		946
902	The top level hash key is called "family", and the second-level hash key	947	The top level hash key is called "family", and the second-level hash key
903	is called "subkey" or simply "key".	948	is called "subkey" or simply "key".
904		949
905	The family must be alphanumeric, i.e. start with a letter and consist	950	The family must be alphanumeric, i.e. start with a letter and consist
…		…
910	with the name of the application or module using it.	955	with the name of the application or module using it.
911		956
912	The subkeys must be non-empty strings, with no further restrictions.	957	The subkeys must be non-empty strings, with no further restrictions.
913		958
914	The values should preferably be strings, but other perl scalars should	959	The values should preferably be strings, but other perl scalars should
915	work as well (such as undef, arrays and hashes).	960	work as well (such as C<undef>, arrays and hashes).
916		961
917	Every database entry is owned by one node - adding the same family/subkey	962	Every database entry is owned by one node - adding the same family/subkey
918	combination on multiple nodes will not cause discomfort for AnyEvent::MP,	963	combination on multiple nodes will not cause discomfort for AnyEvent::MP,
919	but the result might be nondeterministic, i.e. the key might have	964	but the result might be nondeterministic, i.e. the key might have
920	different values on different nodes.	965	different values on different nodes.
…		…
924	pools. For example, a worker port for image scaling might do this:	969	pools. For example, a worker port for image scaling might do this:
925		970
926	db_set my_image_scalers => $port;	971	db_set my_image_scalers => $port;
927		972
928	And clients looking for an image scaler will want to get the	973	And clients looking for an image scaler will want to get the
929	C<my_image_scalers> keys:	974	C<my_image_scalers> keys from time to time:
930		975
931	db_keys "my_image_scalers" => 60 => sub {	976	db_keys my_image_scalers => sub {
932	#d##TODO#	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.
933		992
934	=over	993	=over
935		994
936	=item db_set $family => $subkey [=> $value]	995	=item $guard = db_set $family => $subkey [=> $value]
937		996
938	Sets (or replaces) a key to the database - if C<$value> is omitted,	997	Sets (or replaces) a key to the database - if C<$value> is omitted,
939	C<undef> is used instead.	998	C<undef> is used instead.
940		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
941	=item db_del $family => $subkey	1003	=item db_del $family => $subkey...
942		1004
943	Deletes a key from the database.	1005	Deletes one or more subkeys from the database family.
944		1006
945	=item $guard = db_reg $family => $subkey [=> $value]	1007	=item $guard = db_reg $family => $port => $value
946		1008
947	Sets the key on the database and returns a guard. When the guard is	1009	=item $guard = db_reg $family => $port
948	destroyed, the key is deleted from the database. If C<$value> is missing,	1010
949	then C<undef> is used.	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	};
950		1110
951	=cut	1111	=cut
952		1112
953	=back	1113	=back
954		1114
…		…
999	filter messages without dequeuing them.	1159	filter messages without dequeuing them.
1000		1160
1001	This is not a philosophical difference, but simply stems from AnyEvent::MP	1161	This is not a philosophical difference, but simply stems from AnyEvent::MP
1002	being event-based, while Erlang is process-based.	1162	being event-based, while Erlang is process-based.
1003		1163
1004	You cna have a look at L<Coro::MP> for a more Erlang-like process model on	1164	You can have a look at L<Coro::MP> for a more Erlang-like process model on
1005	top of AEMP and Coro threads.	1165	top of AEMP and Coro threads.
1006		1166
1007	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	1167	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
1008		1168
1009	Sending messages in Erlang is synchronous and blocks the process until	1169	Sending messages in Erlang is synchronous and blocks the process until
1010	a conenction has been established and the message sent (and so does not	1170	a connection has been established and the message sent (and so does not
1011	need a queue that can overflow). AEMP sends return immediately, connection	1171	need a queue that can overflow). AEMP sends return immediately, connection
1012	establishment is handled in the background.	1172	establishment is handled in the background.
1013		1173
1014	=item * Erlang suffers from silent message loss, AEMP does not.	1174	=item * Erlang suffers from silent message loss, AEMP does not.
1015		1175
…		…
1113	Keeping your messages simple, concentrating on data structures rather than	1273	Keeping your messages simple, concentrating on data structures rather than
1114	objects, will keep your messages clean, tidy and efficient.	1274	objects, will keep your messages clean, tidy and efficient.
1115		1275
1116	=back	1276	=back
1117		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
1118	=head1 SEE ALSO	1386	=head1 SEE ALSO
1119		1387
1120	L<AnyEvent::MP::Intro> - a gentle introduction.	1388	L<AnyEvent::MP::Intro> - a gentle introduction.
1121		1389
1122	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1390	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.127 by root, Sat Mar 3 20:35:10 2012 UTC vs. Revision 1.151 by root, Wed Aug 17 19:45:36 2016 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.127 by root, Sat Mar 3 20:35:10 2012 UTC vs.
Revision 1.151 by root, Wed Aug 17 19:45:36 2016 UTC