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

Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.119 by root, Sun Feb 26 10:29:59 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
…		…
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
…		…
112	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
113	endpoints - binds.	119	endpoints - binds.
114		120
115	Currently, only standard C<ip:port> specifications can be used, which	121	Currently, only standard C<ip:port> specifications can be used, which
116	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
117	in listening mode thta accepts conenctions form other nodes.	123	in listening mode that accepts connections from other nodes.
118		124
119	=item seed nodes	125	=item seed nodes
120		126
121	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
122	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
123	network. These other nodes are called "seed nodes".	129	network. These other nodes are called "seed nodes".
124		130
125	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
126	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
127	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.
128		134
129	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
130	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
131	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
132	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
133	nodes for all nodes ensures that eventually the subnets get merged again.	139	for all nodes ensures that eventually the subnets get merged again.
134		140
135	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
136	should always be available. They should also be relatively responsive - a	142	should always be available. They should also be relatively responsive - a
137	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.
138		144
…		…
162		168
163	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
164	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
165	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
166	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
167	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
168	reduces overhead).	174	reduces overhead).
169		175
170	=back	176	=back
171		177
172	=head1 VARIABLES/FUNCTIONS	178	=head1 VARIABLES/FUNCTIONS
…		…
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(
		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	);
181		199
182	use common::sense;	200	use common::sense;
183		201
184	use Carp ();	202	use Carp ();
185		203
186	use AE ();	204	use AnyEvent ();
		205	use Guard ();
187		206
188	use base "Exporter";	207	use base "Exporter";
189		208
190	our $VERSION = '1.30';	209	our $VERSION = '2.02'; # also in MP/Config.pm
191		210
192	our @EXPORT = qw(	211	our @EXPORT = qw(
193	NODE $NODE *SELF node_of after
194	configure	212	configure
		213
		214	NODE $NODE
		215	*SELF
		216
		217	node_of port_is_local
		218
		219	snd kil
195	snd rcv mon mon_guard kil psub peval spawn cal	220	port rcv mon mon_guard psub peval spawn cal
196	port	221	db_set db_del db_reg
		222	db_mon db_family db_keys db_values
		223
		224	after
197	);	225	);
198		226
199	our $SELF;	227	our $SELF;
200		228
201	sub _self_die() {	229	sub _self_die() {
…		…
212		240
213	=item $nodeid = node_of $port	241	=item $nodeid = node_of $port
214		242
215	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.
216		244
		245	=item $is_local = port_is_local $port
		246
		247	Returns true iff the port is a local port.
		248
217	=item configure $profile, key => value...	249	=item configure $profile, key => value...
218		250
219	=item configure key => value...	251	=item configure key => value...
220		252
221	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
222	"distributed mode") it has to configure itself - the minimum a node needs	254	"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	255	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.	256	some other nodes in the network to discover other nodes.
225		257
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	258	This function configures a node - it must be called exactly once (or
230	never) before calling other AnyEvent::MP functions.	259	never) before calling other AnyEvent::MP functions.
		260
		261	The key/value pairs are basically the same ones as documented for the
		262	F<aemp> command line utility (sans the set/del prefix), with these additions:
		263
		264	=over 4
		265
		266	=item norc => $boolean (default false)
		267
		268	If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not>
		269	be consulted - all configuration options must be specified in the
		270	C<configure> call.
		271
		272	=item force => $boolean (default false)
		273
		274	IF true, then the values specified in the C<configure> will take
		275	precedence over any values configured via the rc file. The default is for
		276	the rc file to override any options specified in the program.
		277
		278	=back
231		279
232	=over 4	280	=over 4
233		281
234	=item step 1, gathering configuration from profiles	282	=item step 1, gathering configuration from profiles
235		283
…		…
249	That means that the values specified in the profile have highest priority	297	That means that the values specified in the profile have highest priority
250	and the values specified directly via C<configure> have lowest priority,	298	and the values specified directly via C<configure> have lowest priority,
251	and can only be used to specify defaults.	299	and can only be used to specify defaults.
252		300
253	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
254	this process. If not, then the profile name will be used as node ID. The	302	this process. If not, then the profile name will be used as node ID, with
255	special node ID of C<anon/> will be replaced by a random node ID.	303	a unique randoms tring (C</%u>) appended.
		304
		305	The node ID can contain some C<%> sequences that are expanded: C<%n>
		306	is expanded to the local nodename, C<%u> is replaced by a random
		307	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>.
256		310
257	=item step 2, bind listener sockets	311	=item step 2, bind listener sockets
258		312
259	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
260	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
261	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
262	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
263	binds, but it can still talk to all "normal" nodes).	317	binds, but it can still talk to all "normal" nodes).
264		318
265	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
266	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
…		…
277	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.
278	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.
279		333
280	configure	334	configure
281		335
282	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
283	clients.	337	commandline clients.
284		338
285	configure nodeid => "anon/";	339	configure nodeid => "myscript/%n/%u";
286		340
287	Example: configure a node using a profile called seed, which si suitable	341	Example: configure a node using a profile called seed, which is suitable
288	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,
289	customary for aemp).	343	customary for aemp).
290		344
291	# use the aemp commandline utility	345	# use the aemp commandline utility
292	# aemp profile seed nodeid anon/ binds '*:4040'	346	# aemp profile seed binds '*:4040'
293		347
294	# then use it	348	# then use it
295	configure profile => "seed";	349	configure profile => "seed";
296		350
297	# or simply use aemp from the shell again:	351	# or simply use aemp from the shell again:
…		…
362		416
363	=cut	417	=cut
364		418
365	sub rcv($@);	419	sub rcv($@);
366		420
367	sub _kilme {	421	my $KILME = sub {
368	die "received message on port without callback";	422	(my $tag = substr $_[0], 0, 30) =~ s/([^\x20-\x7e])/./g;
369	}	423	kil $SELF, unhandled_message => "no callback found for message '$tag'";
		424	};
370		425
371	sub port(;&) {	426	sub port(;&) {
372	my $id = "$UNIQ." . $ID++;	427	my $id = $UNIQ . ++$ID;
373	my $port = "$NODE#$id";	428	my $port = "$NODE#$id";
374		429
375	rcv $port, shift \|\| \&_kilme;	430	rcv $port, shift \|\| $KILME;
376		431
377	$port	432	$port
378	}	433	}
379		434
380	=item rcv $local_port, $callback->(@msg)	435	=item rcv $local_port, $callback->(@msg)
…		…
385		440
386	The global C<$SELF> (exported by this module) contains C<$port> while	441	The global C<$SELF> (exported by this module) contains C<$port> while
387	executing the callback. Runtime errors during callback execution will	442	executing the callback. Runtime errors during callback execution will
388	result in the port being C<kil>ed.	443	result in the port being C<kil>ed.
389		444
390	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
391	C<tag> match.	446	C<tag> match.
392		447
393	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...	448	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
394		449
395	Register (or replace) callbacks to be called on messages starting with the	450	Register (or replace) callbacks to be called on messages starting with the
…		…
430		485
431	sub rcv($@) {	486	sub rcv($@) {
432	my $port = shift;	487	my $port = shift;
433	my ($nodeid, $portid) = split /#/, $port, 2;	488	my ($nodeid, $portid) = split /#/, $port, 2;
434		489
435	$NODE{$nodeid} == $NODE{""}	490	$nodeid eq $NODE
436	or Carp::croak "$port: rcv can only be called on local ports, caught";	491	or Carp::croak "$port: rcv can only be called on local ports, caught";
437		492
438	while (@_) {	493	while (@_) {
439	if (ref $_[0]) {	494	if (ref $_[0]) {
440	if (my $self = $PORT_DATA{$portid}) {	495	if (my $self = $PORT_DATA{$portid}) {
…		…
483	$port	538	$port
484	}	539	}
485		540
486	=item peval $port, $coderef[, @args]	541	=item peval $port, $coderef[, @args]
487		542
488	Evaluates the given C<$codref> within the contetx of C<$port>, that is,	543	Evaluates the given C<$codref> within the context of C<$port>, that is,
489	when the code throews an exception the C<$port> will be killed.	544	when the code throws an exception the C<$port> will be killed.
490		545
491	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
492	be returned to the caller.	547	be returned to the caller.
493		548
494	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
…		…
559	$res	614	$res
560	}	615	}
561	}	616	}
562	}	617	}
563		618
		619	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		620
		621	=item $guard = mon $port # kill $SELF when $port dies
		622
564	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies	623	=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		624
570	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies	625	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
571		626
572	Monitor the given port and do something when the port is killed or	627	Monitor the given port and do something when the port is killed or
573	messages to it were lost, and optionally return a guard that can be used	628	messages to it were lost, and optionally return a guard that can be used
574	to stop monitoring again.	629	to stop monitoring again.
575		630
		631	The first two forms distinguish between "normal" and "abnormal" kil's:
		632
		633	In the first form (another port given), if the C<$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<$SELF>.
		640
		641	The remaining forms don't distinguish between "normal" and "abnormal" kil's
		642	- it's up to the callback or receiver to check whether the C<@reason> is
		643	empty and act accordingly.
		644
576	In the first form (callback), the callback is simply called with any	645	In the third form (callback), the callback is simply called with any
577	number of C<@reason> elements (no @reason means that the port was deleted	646	number of C<@reason> elements (empty @reason means that the port was deleted
578	"normally"). Note also that I<< the callback B<must> never die >>, so use	647	"normally"). Note also that I<< the callback B<must> never die >>, so use
579	C<eval> if unsure.	648	C<eval> if unsure.
580		649
581	In the second form (another port given), the other port (C<$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	650	In the last form (message), a message of the form C<$rcvport, @msg,
590	C<snd>.	651	@reason> will be C<snd>.
591		652
592	Monitoring-actions are one-shot: once messages are lost (and a monitoring	653	Monitoring-actions are one-shot: once messages are lost (and a monitoring
593	alert was raised), they are removed and will not trigger again.	654	alert was raised), they are removed and will not trigger again, even if it
		655	turns out that the port is still alive.
594		656
595	As a rule of thumb, monitoring requests should always monitor a port from	657	As a rule of thumb, monitoring requests should always monitor a remote
596	a local port (or callback). The reason is that kill messages might get	658	port locally (using a local C<$rcvport> or a callback). The reason is that
597	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
598	even monitoring requests can get lost (for example, when the connection	660	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	661	when the connection to the other node goes down permanently). When
600	these problems do not exist.	662	monitoring a port locally these problems do not exist.
601		663
602	C<mon> effectively guarantees that, in the absence of hardware failures,	664	C<mon> effectively guarantees that, in the absence of hardware failures,
603	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
604	arrive, or the monitoring action will be invoked after possible message	666	arrive, or the monitoring action will be invoked after possible message
605	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
…		…
650	}	712	}
651		713
652	$node->monitor ($port, $cb);	714	$node->monitor ($port, $cb);
653		715
654	defined wantarray	716	defined wantarray
655	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })	717	and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) })
656	}	718	}
657		719
658	=item $guard = mon_guard $port, $ref, $ref...	720	=item $guard = mon_guard $port, $ref, $ref...
659		721
660	Monitors the given C<$port> and keeps the passed references. When the port	722	Monitors the given C<$port> and keeps the passed references. When the port
…		…
696	will be reported as reason C<< die => $@ >>.	758	will be reported as reason C<< die => $@ >>.
697		759
698	Transport/communication errors are reported as C<< transport_error =>	760	Transport/communication errors are reported as C<< transport_error =>
699	$message >>.	761	$message >>.
700		762
701	=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: $!";
702		774
703	=item $port = spawn $node, $initfunc[, @initdata]	775	=item $port = spawn $node, $initfunc[, @initdata]
704		776
705	Creates a port on the node C<$node> (which can also be a port ID, in which	777	Creates a port on the node C<$node> (which can also be a port ID, in which
706	case it's the node where that port resides).	778	case it's the node where that port resides).
…		…
764	}	836	}
765		837
766	sub spawn(@) {	838	sub spawn(@) {
767	my ($nodeid, undef) = split /#/, shift, 2;	839	my ($nodeid, undef) = split /#/, shift, 2;
768		840
769	my $id = "$RUNIQ." . $ID++;	841	my $id = $RUNIQ . ++$ID;
770		842
771	$_[0] =~ /::/	843	$_[0] =~ /::/
772	or Carp::croak "spawn init function must be a fully-qualified name, caught";	844	or Carp::croak "spawn init function must be a fully-qualified name, caught";
773		845
774	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;	846	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
775		847
776	"$nodeid#$id"	848	"$nodeid#$id"
777	}	849	}
		850
778		851
779	=item after $timeout, @msg	852	=item after $timeout, @msg
780		853
781	=item after $timeout, $callback	854	=item after $timeout, $callback
782		855
…		…
797	ref $action[0]	870	ref $action[0]
798	? $action[0]()	871	? $action[0]()
799	: snd @action;	872	: snd @action;
800	};	873	};
801	}	874	}
		875
		876	#=item $cb2 = timeout $seconds, $cb[, @args]
802		877
803	=item cal $port, @msg, $callback[, $timeout]	878	=item cal $port, @msg, $callback[, $timeout]
804		879
805	A simple form of RPC - sends a message to the given C<$port> with the	880	A simple form of RPC - sends a message to the given C<$port> with the
806	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.
…		…
852	$port	927	$port
853	}	928	}
854		929
855	=back	930	=back
856		931
		932	=head1 DISTRIBUTED DATABASE
		933
		934	AnyEvent::MP comes with a simple distributed database. The database will
		935	be mirrored asynchronously on all global nodes. Other nodes bind to one
		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.
		939
		940	The database structure is that of a two-level hash - the database hash
		941	contains hashes which contain values, similarly to a perl hash of hashes,
		942	i.e.:
		943
		944	$DATABASE{$family}{$subkey} = $value
		945
		946	The top level hash key is called "family", and the second-level hash key
		947	is called "subkey" or simply "key".
		948
		949	The family must be alphanumeric, i.e. start with a letter and consist
		950	of letters, digits, underscores and colons (C<[A-Za-z][A-Za-z0-9_:]*>,
		951	pretty much like Perl module names.
		952
		953	As the family namespace is global, it is recommended to prefix family names
		954	with the name of the application or module using it.
		955
		956	The subkeys must be non-empty strings, with no further restrictions.
		957
		958	The values should preferably be strings, but other perl scalars should
		959	work as well (such as C<undef>, arrays and hashes).
		960
		961	Every database entry is owned by one node - adding the same family/subkey
		962	combination on multiple nodes will not cause discomfort for AnyEvent::MP,
		963	but the result might be nondeterministic, i.e. the key might have
		964	different values on different nodes.
		965
		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:
		969
		970	db_set my_image_scalers => $port;
		971
		972	And clients looking for an image scaler will want to get the
		973	C<my_image_scalers> keys from time to time:
		974
		975	db_keys my_image_scalers => sub {
		976	@ports = @{ $_[0] };
		977	};
		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
		994	=item $guard = db_set $family => $subkey [=> $value]
		995
		996	Sets (or replaces) a key to the database - if C<$value> is omitted,
		997	C<undef> is used instead.
		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	};
		1109
		1110	=cut
		1111
		1112	=back
		1113
857	=head1 AnyEvent::MP vs. Distributed Erlang	1114	=head1 AnyEvent::MP vs. Distributed Erlang
858		1115
859	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	1116	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	1117	== 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	1118	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
…		…
901	filter messages without dequeuing them.	1158	filter messages without dequeuing them.
902		1159
903	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
904	being event-based, while Erlang is process-based.	1161	being event-based, while Erlang is process-based.
905		1162
906	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
907	top of AEMP and Coro threads.	1164	top of AEMP and Coro threads.
908		1165
909	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	1166	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
910		1167
911	Sending messages in Erlang is synchronous and blocks the process until	1168	Sending messages in Erlang is synchronous and blocks the process until
912	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
913	need a queue that can overflow). AEMP sends return immediately, connection	1170	need a queue that can overflow). AEMP sends return immediately, connection
914	establishment is handled in the background.	1171	establishment is handled in the background.
915		1172
916	=item * Erlang suffers from silent message loss, AEMP does not.	1173	=item * Erlang suffers from silent message loss, AEMP does not.
917		1174
…		…
1015	Keeping your messages simple, concentrating on data structures rather than	1272	Keeping your messages simple, concentrating on data structures rather than
1016	objects, will keep your messages clean, tidy and efficient.	1273	objects, will keep your messages clean, tidy and efficient.
1017		1274
1018	=back	1275	=back
1019		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
1020	=head1 SEE ALSO	1385	=head1 SEE ALSO
1021		1386
1022	L<AnyEvent::MP::Intro> - a gentle introduction.	1387	L<AnyEvent::MP::Intro> - a gentle introduction.
1023		1388
1024	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1389	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.

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Comparing cvsroot/AnyEvent-MP/MP.pm (file contents): Revision 1.119 by root, Sun Feb 26 10:29:59 2012 UTC vs. Revision 1.153 by root, Sat Nov 2 01:30:49 2019 UTC

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Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.119 by root, Sun Feb 26 10:29:59 2012 UTC vs.
Revision 1.153 by root, Sat Nov 2 01:30:49 2019 UTC