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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.125 by root, Sat Mar 3 13:07:19 2012 UTC vs.
Revision 1.153 by root, Sat Nov 2 01:30:49 2019 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 = '2.02'; # also in MP/Config.pm
195		210
196	our @EXPORT = qw(	211	our @EXPORT = qw(
197	NODE $NODE *SELF node_of after
198	configure	212	configure
		213
		214	NODE $NODE
		215	*SELF
		216
		217	node_of port_is_local
		218
		219	snd kil
199	snd rcv mon mon_guard kil psub peval spawn cal	220	port rcv mon mon_guard psub peval spawn cal
200	port
201	db_set db_del db_reg	221	db_set db_del db_reg
		222	db_mon db_family db_keys db_values
		223
		224	after
202	);	225	);
203		226
204	our $SELF;	227	our $SELF;
205		228
206	sub _self_die() {	229	sub _self_die() {
…		…
217		240
218	=item $nodeid = node_of $port	241	=item $nodeid = node_of $port
219		242
220	Extracts and returns the node ID from a port ID or a node ID.	243	Extracts and returns the node ID from a port ID or a node ID.
221		244
		245	=item $is_local = port_is_local $port
		246
		247	Returns true iff the port is a local port.
		248
222	=item configure $profile, key => value...	249	=item configure $profile, key => value...
223		250
224	=item configure key => value...	251	=item configure key => value...
225		252
226	Before a node can talk to other nodes on the network (i.e. enter	253	Before a node can talk to other nodes on the network (i.e. enter
…		…
230		257
231	This function configures a node - it must be called exactly once (or	258	This function configures a node - it must be called exactly once (or
232	never) before calling other AnyEvent::MP functions.	259	never) before calling other AnyEvent::MP functions.
233		260
234	The key/value pairs are basically the same ones as documented for the	261	The key/value pairs are basically the same ones as documented for the
235	F<aemp> command line utility (sans the set/del prefix), with two additions:	262	F<aemp> command line utility (sans the set/del prefix), with these additions:
236		263
237	=over 4	264	=over 4
238		265
239	=item norc => $boolean (default false)	266	=item norc => $boolean (default false)
240		267
241	If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not>	268	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	269	be consulted - all configuration options must be specified in the
243	C<configure> call.	270	C<configure> call.
244		271
245	=item force => $boolean (default false)	272	=item force => $boolean (default false)
246		273
247	IF true, then the values specified in the C<configure> will take	274	IF true, then the values specified in the C<configure> will take
…		…
271	and the values specified directly via C<configure> have lowest priority,	298	and the values specified directly via C<configure> have lowest priority,
272	and can only be used to specify defaults.	299	and can only be used to specify defaults.
273		300
274	If the profile specifies a node ID, then this will become the node ID of	301	If the profile specifies a node ID, then this will become the node ID of
275	this process. If not, then the profile name will be used as node ID, with	302	this process. If not, then the profile name will be used as node ID, with
276	a slash (C</>) attached.	303	a unique randoms tring (C</%u>) appended.
277		304
278	If the node ID (or profile name) ends with a slash (C</>), then a random	305	The node ID can contain some C<%> sequences that are expanded: C<%n>
279	string is appended to make it unique.	306	is expanded to the local nodename, C<%u> is replaced by a random
		307	strign to make the node unique. For example, the F<aemp> commandline
		308	utility uses C<aemp/%n/%u> as nodename, which might expand to
		309	C<aemp/cerebro/ZQDGSIkRhEZQDGSIkRhE>.
280		310
281	=item step 2, bind listener sockets	311	=item step 2, bind listener sockets
282		312
283	The next step is to look up the binds in the profile, followed by binding	313	The next step is to look up the binds in the profile, followed by binding
284	aemp protocol listeners on all binds specified (it is possible and valid	314	aemp protocol listeners on all binds specified (it is possible and valid
285	to have no binds, meaning that the node cannot be contacted form the	315	to have no binds, meaning that the node cannot be contacted from the
286	outside. This means the node cannot talk to other nodes that also have no	316	outside. This means the node cannot talk to other nodes that also have no
287	binds, but it can still talk to all "normal" nodes).	317	binds, but it can still talk to all "normal" nodes).
288		318
289	If the profile does not specify a binds list, then a default of C<*> is	319	If the profile does not specify a binds list, then a default of C<*> is
290	used, meaning the node will bind on a dynamically-assigned port on every	320	used, meaning the node will bind on a dynamically-assigned port on every
…		…
301	Example: become a distributed node using the local node name as profile.	331	Example: become a distributed node using the local node name as profile.
302	This should be the most common form of invocation for "daemon"-type nodes.	332	This should be the most common form of invocation for "daemon"-type nodes.
303		333
304	configure	334	configure
305		335
306	Example: become an anonymous node. This form is often used for commandline	336	Example: become a semi-anonymous node. This form is often used for
307	clients.	337	commandline clients.
308		338
309	configure nodeid => "anon/";	339	configure nodeid => "myscript/%n/%u";
310		340
311	Example: configure a node using a profile called seed, which is suitable	341	Example: configure a node using a profile called seed, which is suitable
312	for a seed node as it binds on all local addresses on a fixed port (4040,	342	for a seed node as it binds on all local addresses on a fixed port (4040,
313	customary for aemp).	343	customary for aemp).
314		344
…		…
386		416
387	=cut	417	=cut
388		418
389	sub rcv($@);	419	sub rcv($@);
390		420
391	sub _kilme {	421	my $KILME = sub {
392	die "received message on port without callback";	422	(my $tag = substr $_[0], 0, 30) =~ s/([^\x20-\x7e])/./g;
393	}	423	kil $SELF, unhandled_message => "no callback found for message '$tag'";
		424	};
394		425
395	sub port(;&) {	426	sub port(;&) {
396	my $id = $UNIQ . ++$ID;	427	my $id = $UNIQ . ++$ID;
397	my $port = "$NODE#$id";	428	my $port = "$NODE#$id";
398		429
399	rcv $port, shift \|\| \&_kilme;	430	rcv $port, shift \|\| $KILME;
400		431
401	$port	432	$port
402	}	433	}
403		434
404	=item rcv $local_port, $callback->(@msg)	435	=item rcv $local_port, $callback->(@msg)
…		…
409		440
410	The global C<$SELF> (exported by this module) contains C<$port> while	441	The global C<$SELF> (exported by this module) contains C<$port> while
411	executing the callback. Runtime errors during callback execution will	442	executing the callback. Runtime errors during callback execution will
412	result in the port being C<kil>ed.	443	result in the port being C<kil>ed.
413		444
414	The default callback received all messages not matched by a more specific	445	The default callback receives all messages not matched by a more specific
415	C<tag> match.	446	C<tag> match.
416		447
417	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...	448	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
418		449
419	Register (or replace) callbacks to be called on messages starting with the	450	Register (or replace) callbacks to be called on messages starting with the
…		…
454		485
455	sub rcv($@) {	486	sub rcv($@) {
456	my $port = shift;	487	my $port = shift;
457	my ($nodeid, $portid) = split /#/, $port, 2;	488	my ($nodeid, $portid) = split /#/, $port, 2;
458		489
459	$NODE{$nodeid} == $NODE{""}	490	$nodeid eq $NODE
460	or Carp::croak "$port: rcv can only be called on local ports, caught";	491	or Carp::croak "$port: rcv can only be called on local ports, caught";
461		492
462	while (@_) {	493	while (@_) {
463	if (ref $_[0]) {	494	if (ref $_[0]) {
464	if (my $self = $PORT_DATA{$portid}) {	495	if (my $self = $PORT_DATA{$portid}) {
…		…
507	$port	538	$port
508	}	539	}
509		540
510	=item peval $port, $coderef[, @args]	541	=item peval $port, $coderef[, @args]
511		542
512	Evaluates the given C<$codref> within the contetx of C<$port>, that is,	543	Evaluates the given C<$codref> within the context of C<$port>, that is,
513	when the code throews an exception the C<$port> will be killed.	544	when the code throws an exception the C<$port> will be killed.
514		545
515	Any remaining args will be passed to the callback. Any return values will	546	Any remaining args will be passed to the callback. Any return values will
516	be returned to the caller.	547	be returned to the caller.
517		548
518	This is useful when you temporarily want to execute code in the context of	549	This is useful when you temporarily want to execute code in the context of
…		…
583	$res	614	$res
584	}	615	}
585	}	616	}
586	}	617	}
587		618
		619	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		620
		621	=item $guard = mon $port # kill $SELF when $port dies
		622
588	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies	623	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
589
590	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
591
592	=item $guard = mon $port # kill $SELF when $port dies
593		624
594	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies	625	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
595		626
596	Monitor the given port and do something when the port is killed or	627	Monitor the given port and do something when the port is killed or
597	messages to it were lost, and optionally return a guard that can be used	628	messages to it were lost, and optionally return a guard that can be used
598	to stop monitoring again.	629	to stop monitoring again.
599		630
		631	The first two forms distinguish between "normal" and "abnormal" kil's:
		632
		633	In the first form (another port given), if the C<$port> is C<kil>'ed with
		634	a non-empty reason, the other port (C<$rcvport>) will be kil'ed with the
		635	same reason. That is, on "normal" kil's nothing happens, while under all
		636	other conditions, the other port is killed with the same reason.
		637
		638	The second form (kill self) is the same as the first form, except that
		639	C<$rvport> defaults to C<$SELF>.
		640
		641	The remaining forms don't distinguish between "normal" and "abnormal" kil's
		642	- it's up to the callback or receiver to check whether the C<@reason> is
		643	empty and act accordingly.
		644
600	In the first form (callback), the callback is simply called with any	645	In the third form (callback), the callback is simply called with any
601	number of C<@reason> elements (no @reason means that the port was deleted	646	number of C<@reason> elements (empty @reason means that the port was deleted
602	"normally"). Note also that I<< the callback B<must> never die >>, so use	647	"normally"). Note also that I<< the callback B<must> never die >>, so use
603	C<eval> if unsure.	648	C<eval> if unsure.
604		649
605	In the second form (another port given), the other port (C<$rcvport>)
606	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
607	"normal" kils nothing happens, while under all other conditions, the other
608	port is killed with the same reason.
609
610	The third form (kill self) is the same as the second form, except that
611	C<$rvport> defaults to C<$SELF>.
612
613	In the last form (message), a message of the form C<@msg, @reason> will be	650	In the last form (message), a message of the form C<$rcvport, @msg,
614	C<snd>.	651	@reason> will be C<snd>.
615		652
616	Monitoring-actions are one-shot: once messages are lost (and a monitoring	653	Monitoring-actions are one-shot: once messages are lost (and a monitoring
617	alert was raised), they are removed and will not trigger again.	654	alert was raised), they are removed and will not trigger again, even if it
		655	turns out that the port is still alive.
618		656
619	As a rule of thumb, monitoring requests should always monitor a port from	657	As a rule of thumb, monitoring requests should always monitor a remote
620	a local port (or callback). The reason is that kill messages might get	658	port locally (using a local C<$rcvport> or a callback). The reason is that
621	lost, just like any other message. Another less obvious reason is that	659	kill messages might get lost, just like any other message. Another less
622	even monitoring requests can get lost (for example, when the connection	660	obvious reason is that even monitoring requests can get lost (for example,
623	to the other node goes down permanently). When monitoring a port locally	661	when the connection to the other node goes down permanently). When
624	these problems do not exist.	662	monitoring a port locally these problems do not exist.
625		663
626	C<mon> effectively guarantees that, in the absence of hardware failures,	664	C<mon> effectively guarantees that, in the absence of hardware failures,
627	after starting the monitor, either all messages sent to the port will	665	after starting the monitor, either all messages sent to the port will
628	arrive, or the monitoring action will be invoked after possible message	666	arrive, or the monitoring action will be invoked after possible message
629	loss has been detected. No messages will be lost "in between" (after	667	loss has been detected. No messages will be lost "in between" (after
…		…
720	will be reported as reason C<< die => $@ >>.	758	will be reported as reason C<< die => $@ >>.
721		759
722	Transport/communication errors are reported as C<< transport_error =>	760	Transport/communication errors are reported as C<< transport_error =>
723	$message >>.	761	$message >>.
724		762
725	=cut	763	Common idioms:
		764
		765	# silently remove yourself, do not kill linked ports
		766	kil $SELF;
		767
		768	# report a failure in some detail
		769	kil $SELF, failure_mode_1 => "it failed with too high temperature";
		770
		771	# do not waste much time with killing, just die when something goes wrong
		772	open my $fh, "<file"
		773	or die "file: $!";
726		774
727	=item $port = spawn $node, $initfunc[, @initdata]	775	=item $port = spawn $node, $initfunc[, @initdata]
728		776
729	Creates a port on the node C<$node> (which can also be a port ID, in which	777	Creates a port on the node C<$node> (which can also be a port ID, in which
730	case it's the node where that port resides).	778	case it's the node where that port resides).
…		…
822	ref $action[0]	870	ref $action[0]
823	? $action[0]()	871	? $action[0]()
824	: snd @action;	872	: snd @action;
825	};	873	};
826	}	874	}
		875
		876	#=item $cb2 = timeout $seconds, $cb[, @args]
827		877
828	=item cal $port, @msg, $callback[, $timeout]	878	=item cal $port, @msg, $callback[, $timeout]
829		879
830	A simple form of RPC - sends a message to the given C<$port> with the	880	A simple form of RPC - sends a message to the given C<$port> with the
831	given contents (C<@msg>), but adds a reply port to the message.	881	given contents (C<@msg>), but adds a reply port to the message.
…		…
880	=back	930	=back
881		931
882	=head1 DISTRIBUTED DATABASE	932	=head1 DISTRIBUTED DATABASE
883		933
884	AnyEvent::MP comes with a simple distributed database. The database will	934	AnyEvent::MP comes with a simple distributed database. The database will
885	be mirrored asynchronously at all global nodes. Other nodes bind to one of	935	be mirrored asynchronously on all global nodes. Other nodes bind to one
886	the global nodes for their needs.	936	of the global nodes for their needs. Every node has a "local database"
		937	which contains all the values that are set locally. All local databases
		938	are merged together to form the global database, which can be queried.
887		939
888	The database consists of a two-level hash - a hash contains a hash which	940	The database structure is that of a two-level hash - the database hash
889	contains values.	941	contains hashes which contain values, similarly to a perl hash of hashes,
		942	i.e.:
		943
		944	$DATABASE{$family}{$subkey} = $value
890		945
891	The top level hash key is called "family", and the second-level hash key	946	The top level hash key is called "family", and the second-level hash key
892	is simply called "key".	947	is called "subkey" or simply "key".
893		948
894	The family must be alphanumeric, i.e. start with a letter and consist	949	The family must be alphanumeric, i.e. start with a letter and consist
895	of letters, digits, underscores and colons (C<[A-Za-z][A-Za-z0-9_:]*>,	950	of letters, digits, underscores and colons (C<[A-Za-z][A-Za-z0-9_:]*>,
896	pretty much like Perl module names.	951	pretty much like Perl module names.
897		952
898	As the family namespace is global, it is recommended to prefix family names	953	As the family namespace is global, it is recommended to prefix family names
899	with the name of the application or module using it.	954	with the name of the application or module using it.
900		955
901	The keys must be strings, with no other limitations.	956	The subkeys must be non-empty strings, with no further restrictions.
902		957
903	The values should preferably be strings, but other perl scalars should	958	The values should preferably be strings, but other perl scalars should
904	work as well (such as undef, arrays and hashes).	959	work as well (such as C<undef>, arrays and hashes).
905		960
906	Every database entry is owned by one node - adding the same family/key	961	Every database entry is owned by one node - adding the same family/subkey
907	combination on multiple nodes will not cause discomfort for AnyEvent::MP,	962	combination on multiple nodes will not cause discomfort for AnyEvent::MP,
908	but the result might be nondeterministic, i.e. the key might have	963	but the result might be nondeterministic, i.e. the key might have
909	different values on different nodes.	964	different values on different nodes.
910		965
911	=item db_set $family => $key => $value	966	Different subkeys in the same family can be owned by different nodes
		967	without problems, and in fact, this is the common method to create worker
		968	pools. For example, a worker port for image scaling might do this:
912		969
913	Sets (or replaces) a key to the database.	970	db_set my_image_scalers => $port;
914		971
915	=item db_del $family => $key	972	And clients looking for an image scaler will want to get the
		973	C<my_image_scalers> keys from time to time:
916		974
917	Deletes a key from the database.	975	db_keys my_image_scalers => sub {
		976	@ports = @{ $_[0] };
		977	};
918		978
		979	Or better yet, they want to monitor the database family, so they always
		980	have a reasonable up-to-date copy:
		981
		982	db_mon my_image_scalers => sub {
		983	@ports = keys %{ $_[0] };
		984	};
		985
		986	In general, you can set or delete single subkeys, but query and monitor
		987	whole families only.
		988
		989	If you feel the need to monitor or query a single subkey, try giving it
		990	it's own family.
		991
		992	=over
		993
919	=item $guard = db_reg $family => $key [=> $value]	994	=item $guard = db_set $family => $subkey [=> $value]
920		995
921	Sets the key on the database and returns a guard. When the guard is	996	Sets (or replaces) a key to the database - if C<$value> is omitted,
922	destroyed, the key is deleted from the database. If C<$value> is missing,	997	C<undef> is used instead.
923	then C<undef> is used.	998
		999	When called in non-void context, C<db_set> returns a guard that
		1000	automatically calls C<db_del> when it is destroyed.
		1001
		1002	=item db_del $family => $subkey...
		1003
		1004	Deletes one or more subkeys from the database family.
		1005
		1006	=item $guard = db_reg $family => $port => $value
		1007
		1008	=item $guard = db_reg $family => $port
		1009
		1010	=item $guard = db_reg $family
		1011
		1012	Registers a port in the given family and optionally returns a guard to
		1013	remove it.
		1014
		1015	This function basically does the same as:
		1016
		1017	db_set $family => $port => $value
		1018
		1019	Except that the port is monitored and automatically removed from the
		1020	database family when it is kil'ed.
		1021
		1022	If C<$value> is missing, C<undef> is used. If C<$port> is missing, then
		1023	C<$SELF> is used.
		1024
		1025	This function is most useful to register a port in some port group (which
		1026	is just another name for a database family), and have it removed when the
		1027	port is gone. This works best when the port is a local port.
		1028
		1029	=cut
		1030
		1031	sub db_reg($$;$) {
		1032	my $family = shift;
		1033	my $port = @_ ? shift : $SELF;
		1034
		1035	my $clr = sub { db_del $family => $port };
		1036	mon $port, $clr;
		1037
		1038	db_set $family => $port => $_[0];
		1039
		1040	defined wantarray
		1041	and &Guard::guard ($clr)
		1042	}
		1043
		1044	=item db_family $family => $cb->(\%familyhash)
		1045
		1046	Queries the named database C<$family> and call the callback with the
		1047	family represented as a hash. You can keep and freely modify the hash.
		1048
		1049	=item db_keys $family => $cb->(\@keys)
		1050
		1051	Same as C<db_family>, except it only queries the family I<subkeys> and passes
		1052	them as array reference to the callback.
		1053
		1054	=item db_values $family => $cb->(\@values)
		1055
		1056	Same as C<db_family>, except it only queries the family I<values> and passes them
		1057	as array reference to the callback.
		1058
		1059	=item $guard = db_mon $family => $cb->(\%familyhash, \@added, \@changed, \@deleted)
		1060
		1061	Creates a monitor on the given database family. Each time a key is
		1062	set or is deleted the callback is called with a hash containing the
		1063	database family and three lists of added, changed and deleted subkeys,
		1064	respectively. If no keys have changed then the array reference might be
		1065	C<undef> or even missing.
		1066
		1067	If not called in void context, a guard object is returned that, when
		1068	destroyed, stops the monitor.
		1069
		1070	The family hash reference and the key arrays belong to AnyEvent::MP and
		1071	B<must not be modified or stored> by the callback. When in doubt, make a
		1072	copy.
		1073
		1074	As soon as possible after the monitoring starts, the callback will be
		1075	called with the intiial contents of the family, even if it is empty,
		1076	i.e. there will always be a timely call to the callback with the current
		1077	contents.
		1078
		1079	It is possible that the callback is called with a change event even though
		1080	the subkey is already present and the value has not changed.
		1081
		1082	The monitoring stops when the guard object is destroyed.
		1083
		1084	Example: on every change to the family "mygroup", print out all keys.
		1085
		1086	my $guard = db_mon mygroup => sub {
		1087	my ($family, $a, $c, $d) = @_;
		1088	print "mygroup members: ", (join " ", keys %$family), "\n";
		1089	};
		1090
		1091	Exmaple: wait until the family "My::Module::workers" is non-empty.
		1092
		1093	my $guard; $guard = db_mon My::Module::workers => sub {
		1094	my ($family, $a, $c, $d) = @_;
		1095	return unless %$family;
		1096	undef $guard;
		1097	print "My::Module::workers now nonempty\n";
		1098	};
		1099
		1100	Example: print all changes to the family "AnyEvent::Fantasy::Module".
		1101
		1102	my $guard = db_mon AnyEvent::Fantasy::Module => sub {
		1103	my ($family, $a, $c, $d) = @_;
		1104
		1105	print "+$_=$family->{$_}\n" for @$a;
		1106	print "*$_=$family->{$_}\n" for @$c;
		1107	print "-$_=$family->{$_}\n" for @$d;
		1108	};
924		1109
925	=cut	1110	=cut
926		1111
927	=back	1112	=back
928		1113
…		…
973	filter messages without dequeuing them.	1158	filter messages without dequeuing them.
974		1159
975	This is not a philosophical difference, but simply stems from AnyEvent::MP	1160	This is not a philosophical difference, but simply stems from AnyEvent::MP
976	being event-based, while Erlang is process-based.	1161	being event-based, while Erlang is process-based.
977		1162
978	You cna have a look at L<Coro::MP> for a more Erlang-like process model on	1163	You can have a look at L<Coro::MP> for a more Erlang-like process model on
979	top of AEMP and Coro threads.	1164	top of AEMP and Coro threads.
980		1165
981	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	1166	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
982		1167
983	Sending messages in Erlang is synchronous and blocks the process until	1168	Sending messages in Erlang is synchronous and blocks the process until
984	a conenction has been established and the message sent (and so does not	1169	a connection has been established and the message sent (and so does not
985	need a queue that can overflow). AEMP sends return immediately, connection	1170	need a queue that can overflow). AEMP sends return immediately, connection
986	establishment is handled in the background.	1171	establishment is handled in the background.
987		1172
988	=item * Erlang suffers from silent message loss, AEMP does not.	1173	=item * Erlang suffers from silent message loss, AEMP does not.
989		1174
…		…
1087	Keeping your messages simple, concentrating on data structures rather than	1272	Keeping your messages simple, concentrating on data structures rather than
1088	objects, will keep your messages clean, tidy and efficient.	1273	objects, will keep your messages clean, tidy and efficient.
1089		1274
1090	=back	1275	=back
1091		1276
		1277	=head1 PORTING FROM AnyEvent::MP VERSION 1.X
		1278
		1279	AEMP version 2 has a few major incompatible changes compared to version 1:
		1280
		1281	=over 4
		1282
		1283	=item AnyEvent::MP::Global no longer has group management functions.
		1284
		1285	At least not officially - the grp_* functions are still exported and might
		1286	work, but they will be removed in some later release.
		1287
		1288	AnyEvent::MP now comes with a distributed database that is more
		1289	powerful. Its database families map closely to port groups, but the API
		1290	has changed (the functions are also now exported by AnyEvent::MP). Here is
		1291	a rough porting guide:
		1292
		1293	grp_reg $group, $port # old
		1294	db_reg $group, $port # new
		1295
		1296	$list = grp_get $group # old
		1297	db_keys $group, sub { my $list = shift } # new
		1298
		1299	grp_mon $group, $cb->(\@ports, $add, $del) # old
		1300	db_mon $group, $cb->(\%ports, $add, $change, $del) # new
		1301
		1302	C<grp_reg> is a no-brainer (just replace by C<db_reg>), but C<grp_get> is
		1303	no longer instant, because the local node might not have a copy of the
		1304	group. You can either modify your code to allow for a callback, or use
		1305	C<db_mon> to keep an updated copy of the group:
		1306
		1307	my $local_group_copy;
		1308	db_mon $group => sub { $local_group_copy = $_[0] };
		1309
		1310	# now "keys %$local_group_copy" always returns the most up-to-date
		1311	# list of ports in the group.
		1312
		1313	C<grp_mon> can be replaced by C<db_mon> with minor changes - C<db_mon>
		1314	passes a hash as first argument, and an extra C<$chg> argument that can be
		1315	ignored:
		1316
		1317	db_mon $group => sub {
		1318	my ($ports, $add, $chg, $del) = @_;
		1319	$ports = [keys %$ports];
		1320
		1321	# now $ports, $add and $del are the same as
		1322	# were originally passed by grp_mon.
		1323	...
		1324	};
		1325
		1326	=item Nodes not longer connect to all other nodes.
		1327
		1328	In AEMP 1.x, every node automatically loads the L<AnyEvent::MP::Global>
		1329	module, which in turn would create connections to all other nodes in the
		1330	network (helped by the seed nodes).
		1331
		1332	In version 2.x, global nodes still connect to all other global nodes, but
		1333	other nodes don't - now every node either is a global node itself, or
		1334	attaches itself to another global node.
		1335
		1336	If a node isn't a global node itself, then it attaches itself to one
		1337	of its seed nodes. If that seed node isn't a global node yet, it will
		1338	automatically be upgraded to a global node.
		1339
		1340	So in many cases, nothing needs to be changed - one just has to make sure
		1341	that all seed nodes are meshed together with the other seed nodes (as with
		1342	AEMP 1.x), and other nodes specify them as seed nodes. This is most easily
		1343	achieved by specifying the same set of seed nodes for all nodes in the
		1344	network.
		1345
		1346	Not opening a connection to every other node is usually an advantage,
		1347	except when you need the lower latency of an already established
		1348	connection. To ensure a node establishes a connection to another node,
		1349	you can monitor the node port (C<mon $node, ...>), which will attempt to
		1350	create the connection (and notify you when the connection fails).
		1351
		1352	=item Listener-less nodes (nodes without binds) are gone.
		1353
		1354	And are not coming back, at least not in their old form. If no C<binds>
		1355	are specified for a node, AnyEvent::MP assumes a default of C<:>.
		1356
		1357	There are vague plans to implement some form of routing domains, which
		1358	might or might not bring back listener-less nodes, but don't count on it.
		1359
		1360	The fact that most connections are now optional somewhat mitigates this,
		1361	as a node can be effectively unreachable from the outside without any
		1362	problems, as long as it isn't a global node and only reaches out to other
		1363	nodes (as opposed to being contacted from other nodes).
		1364
		1365	=item $AnyEvent::MP::Kernel::WARN has gone.
		1366
		1367	AnyEvent has acquired a logging framework (L<AnyEvent::Log>), and AEMP now
		1368	uses this, and so should your programs.
		1369
		1370	Every module now documents what kinds of messages it generates, with
		1371	AnyEvent::MP acting as a catch all.
		1372
		1373	On the positive side, this means that instead of setting
		1374	C<PERL_ANYEVENT_MP_WARNLEVEL>, you can get away by setting C<AE_VERBOSE> -
		1375	much less to type.
		1376
		1377	=back
		1378
		1379	=head1 LOGGING
		1380
		1381	AnyEvent::MP does not normally log anything by itself, but since it is the
		1382	root of the context hierarchy for AnyEvent::MP modules, it will receive
		1383	all log messages by submodules.
		1384
1092	=head1 SEE ALSO	1385	=head1 SEE ALSO
1093		1386
1094	L<AnyEvent::MP::Intro> - a gentle introduction.	1387	L<AnyEvent::MP::Intro> - a gentle introduction.
1095		1388
1096	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1389	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.125 by root, Sat Mar 3 13:07:19 2012 UTC vs. Revision 1.153 by root, Sat Nov 2 01:30:49 2019 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.125 by root, Sat Mar 3 13:07:19 2012 UTC vs.
Revision 1.153 by root, Sat Nov 2 01:30:49 2019 UTC