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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.123 by root, Thu Mar 1 19:37:59 2012 UTC vs.
Revision 1.154 by root, Fri Nov 15 09:47:38 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 ();
		205	use Guard ();
190		206
191	use base "Exporter";	207	use base "Exporter";
192		208
193	our $VERSION = $AnyEvent::MP::Config::VERSION;	209	our $VERSION = '2.02'; # also in MP/Config.pm
194		210
195	our @EXPORT = qw(	211	our @EXPORT = qw(
196	NODE $NODE *SELF node_of after
197	configure	212	configure
		213
		214	NODE $NODE
		215	*SELF
		216
		217	node_of port_is_local
		218
		219	snd kil
198	snd rcv mon mon_guard kil psub peval spawn cal	220	port rcv mon mon_guard psub peval spawn cal
199	port	221	db_set db_del db_reg
		222	db_mon db_family db_keys db_values
		223
		224	after
200	);	225	);
201		226
202	our $SELF;	227	our $SELF;
203		228
204	sub _self_die() {	229	sub _self_die() {
…		…
215		240
216	=item $nodeid = node_of $port	241	=item $nodeid = node_of $port
217		242
218	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.
219		244
		245	=item $is_local = port_is_local $port
		246
		247	Returns true iff the port is a local port.
		248
220	=item configure $profile, key => value...	249	=item configure $profile, key => value...
221		250
222	=item configure key => value...	251	=item configure key => value...
223		252
224	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
…		…
228		257
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.
231		260
232	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
233	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:
234		263
235	=over 4	264	=over 4
236		265
237	=item norc => $boolean (default false)	266	=item norc => $boolean (default false)
238		267
239	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>
240	be consulted - all configuraiton options must be specified in the	269	be consulted - all configuration options must be specified in the
241	C<configure> call.	270	C<configure> call.
242		271
243	=item force => $boolean (default false)	272	=item force => $boolean (default false)
244		273
245	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
…		…
269	and the values specified directly via C<configure> have lowest priority,	298	and the values specified directly via C<configure> have lowest priority,
270	and can only be used to specify defaults.	299	and can only be used to specify defaults.
271		300
272	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
273	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
274	a slash (C</>) attached.	303	a unique randoms tring (C</%u>) appended.
275		304
276	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>
277	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>.
278		310
279	=item step 2, bind listener sockets	311	=item step 2, bind listener sockets
280		312
281	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
282	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
283	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
284	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
285	binds, but it can still talk to all "normal" nodes).	317	binds, but it can still talk to all "normal" nodes).
286		318
287	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
288	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
…		…
299	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.
300	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.
301		333
302	configure	334	configure
303		335
304	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
305	clients.	337	commandline clients.
306		338
307	configure nodeid => "anon/";	339	configure nodeid => "myscript/%n/%u";
308		340
309	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
310	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,
311	customary for aemp).	343	customary for aemp).
312		344
…		…
384		416
385	=cut	417	=cut
386		418
387	sub rcv($@);	419	sub rcv($@);
388		420
389	sub _kilme {	421	my $KILME = sub {
390	die "received message on port without callback";	422	(my $tag = substr $_[0], 0, 30) =~ s/([^\x20-\x7e])/./g;
391	}	423	kil $SELF, unhandled_message => "no callback found for message '$tag'";
		424	};
392		425
393	sub port(;&) {	426	sub port(;&) {
394	my $id = $UNIQ . ++$ID;	427	my $id = $UNIQ . ++$ID;
395	my $port = "$NODE#$id";	428	my $port = "$NODE#$id";
396		429
397	rcv $port, shift \|\| \&_kilme;	430	rcv $port, shift \|\| $KILME;
398		431
399	$port	432	$port
400	}	433	}
401		434
402	=item rcv $local_port, $callback->(@msg)	435	=item rcv $local_port, $callback->(@msg)
…		…
407		440
408	The global C<$SELF> (exported by this module) contains C<$port> while	441	The global C<$SELF> (exported by this module) contains C<$port> while
409	executing the callback. Runtime errors during callback execution will	442	executing the callback. Runtime errors during callback execution will
410	result in the port being C<kil>ed.	443	result in the port being C<kil>ed.
411		444
412	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
413	C<tag> match.	446	C<tag> match.
414		447
415	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...	448	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
416		449
417	Register (or replace) callbacks to be called on messages starting with the	450	Register (or replace) callbacks to be called on messages starting with the
…		…
452		485
453	sub rcv($@) {	486	sub rcv($@) {
454	my $port = shift;	487	my $port = shift;
455	my ($nodeid, $portid) = split /#/, $port, 2;	488	my ($nodeid, $portid) = split /#/, $port, 2;
456		489
457	$NODE{$nodeid} == $NODE{""}	490	$nodeid eq $NODE
458	or Carp::croak "$port: rcv can only be called on local ports, caught";	491	or Carp::croak "$port: rcv can only be called on local ports, caught";
459		492
460	while (@_) {	493	while (@_) {
461	if (ref $_[0]) {	494	if (ref $_[0]) {
462	if (my $self = $PORT_DATA{$portid}) {	495	if (my $self = $PORT_DATA{$portid}) {
…		…
505	$port	538	$port
506	}	539	}
507		540
508	=item peval $port, $coderef[, @args]	541	=item peval $port, $coderef[, @args]
509		542
510	Evaluates the given C<$codref> within the contetx of C<$port>, that is,	543	Evaluates the given C<$codref> within the context of C<$port>, that is,
511	when the code throews an exception the C<$port> will be killed.	544	when the code throws an exception the C<$port> will be killed.
512		545
513	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
514	be returned to the caller.	547	be returned to the caller.
515		548
516	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
…		…
581	$res	614	$res
582	}	615	}
583	}	616	}
584	}	617	}
585		618
		619	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		620
		621	=item $guard = mon $port # kill $SELF when $port dies
		622
586	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies	623	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
587
588	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
589
590	=item $guard = mon $port # kill $SELF when $port dies
591		624
592	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies	625	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
593		626
594	Monitor the given port and do something when the port is killed or	627	Monitor the given port and do something when the port is killed or
595	messages to it were lost, and optionally return a guard that can be used	628	messages to it were lost, and optionally return a guard that can be used
596	to stop monitoring again.	629	to stop monitoring again.
597		630
		631	The first two forms distinguish between "normal" and "abnormal" kil's:
		632
		633	In the first form (another port given), if the C<$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<$SELF>.
		640
		641	The remaining forms don't distinguish between "normal" and "abnormal" kil's
		642	- it's up to the callback or receiver to check whether the C<@reason> is
		643	empty and act accordingly.
		644
598	In the first form (callback), the callback is simply called with any	645	In the third form (callback), the callback is simply called with any
599	number of C<@reason> elements (no @reason means that the port was deleted	646	number of C<@reason> elements (empty @reason means that the port was deleted
600	"normally"). Note also that I<< the callback B<must> never die >>, so use	647	"normally"). Note also that I<< the callback B<must> never die >>, so use
601	C<eval> if unsure.	648	C<eval> if unsure.
602		649
603	In the second form (another port given), the other port (C<$rcvport>)
604	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
605	"normal" kils nothing happens, while under all other conditions, the other
606	port is killed with the same reason.
607
608	The third form (kill self) is the same as the second form, except that
609	C<$rvport> defaults to C<$SELF>.
610
611	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<$rcvport, @msg,
612	C<snd>.	651	@reason> will be C<snd>.
613		652
614	Monitoring-actions are one-shot: once messages are lost (and a monitoring	653	Monitoring-actions are one-shot: once messages are lost (and a monitoring
615	alert was raised), they are removed and will not trigger again.	654	alert was raised), they are removed and will not trigger again, even if it
		655	turns out that the port is still alive (but monitoring actions added after
		656	that will again trigger).
616		657
617	As a rule of thumb, monitoring requests should always monitor a port from	658	As a rule of thumb, monitoring requests should always monitor a remote
618	a local port (or callback). The reason is that kill messages might get	659	port locally (using a local C<$rcvport> or a callback). The reason is that
619	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
620	even monitoring requests can get lost (for example, when the connection	661	obvious reason is that even monitoring requests can get lost (for example,
621	to the other node goes down permanently). When monitoring a port locally	662	when the connection to the other node goes down permanently). When
622	these problems do not exist.	663	monitoring a port locally these problems do not exist.
623		664
624	C<mon> effectively guarantees that, in the absence of hardware failures,	665	C<mon> effectively guarantees that, in the absence of hardware failures,
625	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
626	arrive, or the monitoring action will be invoked after possible message	667	arrive, or the monitoring action will be invoked after possible message
627	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
…		…
672	}	713	}
673		714
674	$node->monitor ($port, $cb);	715	$node->monitor ($port, $cb);
675		716
676	defined wantarray	717	defined wantarray
677	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })	718	and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) })
678	}	719	}
679		720
680	=item $guard = mon_guard $port, $ref, $ref...	721	=item $guard = mon_guard $port, $ref, $ref...
681		722
682	Monitors the given C<$port> and keeps the passed references. When the port	723	Monitors the given C<$port> and keeps the passed references. When the port
…		…
718	will be reported as reason C<< die => $@ >>.	759	will be reported as reason C<< die => $@ >>.
719		760
720	Transport/communication errors are reported as C<< transport_error =>	761	Transport/communication errors are reported as C<< transport_error =>
721	$message >>.	762	$message >>.
722		763
723	=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: $!";
724		775
725	=item $port = spawn $node, $initfunc[, @initdata]	776	=item $port = spawn $node, $initfunc[, @initdata]
726		777
727	Creates a port on the node C<$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
728	case it's the node where that port resides).	779	case it's the node where that port resides).
…		…
821	? $action[0]()	872	? $action[0]()
822	: snd @action;	873	: snd @action;
823	};	874	};
824	}	875	}
825		876
		877	#=item $cb2 = timeout $seconds, $cb[, @args]
		878
826	=item cal $port, @msg, $callback[, $timeout]	879	=item cal $port, @msg, $callback[, $timeout]
827		880
828	A simple form of RPC - sends a message to the given C<$port> with the	881	A simple form of RPC - sends a message to the given C<$port> with the
829	given contents (C<@msg>), but adds a reply port to the message.	882	given contents (C<@msg>), but appends a reply port to the message.
830		883
831	The reply port is created temporarily just for the purpose of receiving	884	The reply port is created temporarily just for the purpose of receiving
832	the reply, and will be C<kil>ed when no longer needed.	885	the reply, and will be C<kil>ed when no longer needed.
833		886
834	A reply message sent to the port is passed to the C<$callback> as-is.	887	A reply message sent to the port is passed to the C<$callback> as-is.
…		…
875	$port	928	$port
876	}	929	}
877		930
878	=back	931	=back
879		932
		933	=head1 DISTRIBUTED DATABASE
		934
		935	AnyEvent::MP comes with a simple distributed database. The database will
		936	be mirrored asynchronously on all global nodes. Other nodes bind to one
		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.
		940
		941	The database structure is that of a two-level hash - the database hash
		942	contains hashes which contain values, similarly to a perl hash of hashes,
		943	i.e.:
		944
		945	$DATABASE{$family}{$subkey} = $value
		946
		947	The top level hash key is called "family", and the second-level hash key
		948	is called "subkey" or simply "key".
		949
		950	The family must be alphanumeric, i.e. start with a letter and consist
		951	of letters, digits, underscores and colons (C<[A-Za-z][A-Za-z0-9_:]*>,
		952	pretty much like Perl module names.
		953
		954	As the family namespace is global, it is recommended to prefix family names
		955	with the name of the application or module using it.
		956
		957	The subkeys must be non-empty strings, with no further restrictions.
		958
		959	The values should preferably be strings, but other perl scalars should
		960	work as well (such as C<undef>, arrays and hashes).
		961
		962	Every database entry is owned by one node - adding the same family/subkey
		963	combination on multiple nodes will not cause discomfort for AnyEvent::MP,
		964	but the result might be nondeterministic, i.e. the key might have
		965	different values on different nodes.
		966
		967	Different subkeys in the same family can be owned by different nodes
		968	without problems, and in fact, this is the common method to create worker
		969	pools. For example, a worker port for image scaling might do this:
		970
		971	db_set my_image_scalers => $port;
		972
		973	And clients looking for an image scaler will want to get the
		974	C<my_image_scalers> keys from time to time:
		975
		976	db_keys my_image_scalers => sub {
		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.
		992
		993	=over
		994
		995	=item $guard = db_set $family => $subkey [=> $value]
		996
		997	Sets (or replaces) a key to the database - if C<$value> is omitted,
		998	C<undef> is used instead.
		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
		1003	=item db_del $family => $subkey...
		1004
		1005	Deletes one or more subkeys from the database family.
		1006
		1007	=item $guard = db_reg $family => $port => $value
		1008
		1009	=item $guard = db_reg $family => $port
		1010
		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	};
		1110
		1111	=cut
		1112
		1113	=back
		1114
880	=head1 AnyEvent::MP vs. Distributed Erlang	1115	=head1 AnyEvent::MP vs. Distributed Erlang
881		1116
882	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	1117	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
883	== aemp node, Erlang process == aemp port), so many of the documents and	1118	== aemp node, Erlang process == aemp port), so many of the documents and
884	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	1119	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
…		…
924	filter messages without dequeuing them.	1159	filter messages without dequeuing them.
925		1160
926	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
927	being event-based, while Erlang is process-based.	1162	being event-based, while Erlang is process-based.
928		1163
929	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
930	top of AEMP and Coro threads.	1165	top of AEMP and Coro threads.
931		1166
932	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	1167	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
933		1168
934	Sending messages in Erlang is synchronous and blocks the process until	1169	Sending messages in Erlang is synchronous and blocks the process until
935	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
936	need a queue that can overflow). AEMP sends return immediately, connection	1171	need a queue that can overflow). AEMP sends return immediately, connection
937	establishment is handled in the background.	1172	establishment is handled in the background.
938		1173
939	=item * Erlang suffers from silent message loss, AEMP does not.	1174	=item * Erlang suffers from silent message loss, AEMP does not.
940		1175
…		…
1038	Keeping your messages simple, concentrating on data structures rather than	1273	Keeping your messages simple, concentrating on data structures rather than
1039	objects, will keep your messages clean, tidy and efficient.	1274	objects, will keep your messages clean, tidy and efficient.
1040		1275
1041	=back	1276	=back
1042		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
1043	=head1 SEE ALSO	1386	=head1 SEE ALSO
1044		1387
1045	L<AnyEvent::MP::Intro> - a gentle introduction.	1388	L<AnyEvent::MP::Intro> - a gentle introduction.
1046		1389
1047	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 1.123 by root, Thu Mar 1 19:37:59 2012 UTC vs. Revision 1.154 by root, Fri Nov 15 09:47:38 2019 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.123 by root, Thu Mar 1 19:37:59 2012 UTC vs.
Revision 1.154 by root, Fri Nov 15 09:47:38 2019 UTC