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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.127 by root, Sat Mar 3 20:35:10 2012 UTC vs.
Revision 1.153 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
…		…
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
248	precedence over any values configured via the rc file. The default is for	275	precedence over any values configured via the rc file. The default is for
249	the rc file to override any options specified in the program.	276	the rc file to override any options specified in the program.
250
251	=item secure => $pass->($nodeid)
252
253	In addition to specifying a boolean, you can specify a code reference that
254	is called for every remote execution attempt - the execution request is
255	granted iff the callback returns a true value.
256
257	See F<semp setsecure> for more info.
258		277
259	=back	278	=back
260		279
261	=over 4	280	=over 4
262		281
…		…
291		310
292	=item step 2, bind listener sockets	311	=item step 2, bind listener sockets
293		312
294	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
295	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
296	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
297	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
298	binds, but it can still talk to all "normal" nodes).	317	binds, but it can still talk to all "normal" nodes).
299		318
300	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
301	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
…		…
397		416
398	=cut	417	=cut
399		418
400	sub rcv($@);	419	sub rcv($@);
401		420
402	sub _kilme {	421	my $KILME = sub {
403	die "received message on port without callback";	422	(my $tag = substr $_[0], 0, 30) =~ s/([^\x20-\x7e])/./g;
404	}	423	kil $SELF, unhandled_message => "no callback found for message '$tag'";
		424	};
405		425
406	sub port(;&) {	426	sub port(;&) {
407	my $id = $UNIQ . ++$ID;	427	my $id = $UNIQ . ++$ID;
408	my $port = "$NODE#$id";	428	my $port = "$NODE#$id";
409		429
410	rcv $port, shift \|\| \&_kilme;	430	rcv $port, shift \|\| $KILME;
411		431
412	$port	432	$port
413	}	433	}
414		434
415	=item rcv $local_port, $callback->(@msg)	435	=item rcv $local_port, $callback->(@msg)
…		…
420		440
421	The global C<$SELF> (exported by this module) contains C<$port> while	441	The global C<$SELF> (exported by this module) contains C<$port> while
422	executing the callback. Runtime errors during callback execution will	442	executing the callback. Runtime errors during callback execution will
423	result in the port being C<kil>ed.	443	result in the port being C<kil>ed.
424		444
425	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
426	C<tag> match.	446	C<tag> match.
427		447
428	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...	448	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
429		449
430	Register (or replace) callbacks to be called on messages starting with the	450	Register (or replace) callbacks to be called on messages starting with the
…		…
465		485
466	sub rcv($@) {	486	sub rcv($@) {
467	my $port = shift;	487	my $port = shift;
468	my ($nodeid, $portid) = split /#/, $port, 2;	488	my ($nodeid, $portid) = split /#/, $port, 2;
469		489
470	$NODE{$nodeid} == $NODE{""}	490	$nodeid eq $NODE
471	or Carp::croak "$port: rcv can only be called on local ports, caught";	491	or Carp::croak "$port: rcv can only be called on local ports, caught";
472		492
473	while (@_) {	493	while (@_) {
474	if (ref $_[0]) {	494	if (ref $_[0]) {
475	if (my $self = $PORT_DATA{$portid}) {	495	if (my $self = $PORT_DATA{$portid}) {
…		…
518	$port	538	$port
519	}	539	}
520		540
521	=item peval $port, $coderef[, @args]	541	=item peval $port, $coderef[, @args]
522		542
523	Evaluates the given C<$codref> within the contetx of C<$port>, that is,	543	Evaluates the given C<$codref> within the context of C<$port>, that is,
524	when the code throews an exception the C<$port> will be killed.	544	when the code throws an exception the C<$port> will be killed.
525		545
526	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
527	be returned to the caller.	547	be returned to the caller.
528		548
529	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
…		…
594	$res	614	$res
595	}	615	}
596	}	616	}
597	}	617	}
598		618
		619	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		620
		621	=item $guard = mon $port # kill $SELF when $port dies
		622
599	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies	623	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
600
601	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
602
603	=item $guard = mon $port # kill $SELF when $port dies
604		624
605	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies	625	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
606		626
607	Monitor the given port and do something when the port is killed or	627	Monitor the given port and do something when the port is killed or
608	messages to it were lost, and optionally return a guard that can be used	628	messages to it were lost, and optionally return a guard that can be used
609	to stop monitoring again.	629	to stop monitoring again.
610		630
		631	The first two forms distinguish between "normal" and "abnormal" kil's:
		632
		633	In the first form (another port given), if the C<$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<$SELF>.
		640
		641	The remaining forms don't distinguish between "normal" and "abnormal" kil's
		642	- it's up to the callback or receiver to check whether the C<@reason> is
		643	empty and act accordingly.
		644
611	In the first form (callback), the callback is simply called with any	645	In the third form (callback), the callback is simply called with any
612	number of C<@reason> elements (no @reason means that the port was deleted	646	number of C<@reason> elements (empty @reason means that the port was deleted
613	"normally"). Note also that I<< the callback B<must> never die >>, so use	647	"normally"). Note also that I<< the callback B<must> never die >>, so use
614	C<eval> if unsure.	648	C<eval> if unsure.
615		649
616	In the second form (another port given), the other port (C<$rcvport>)
617	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
618	"normal" kils nothing happens, while under all other conditions, the other
619	port is killed with the same reason.
620
621	The third form (kill self) is the same as the second form, except that
622	C<$rvport> defaults to C<$SELF>.
623
624	In the last form (message), a message of the form C<@msg, @reason> will be	650	In the last form (message), a message of the form C<$rcvport, @msg,
625	C<snd>.	651	@reason> will be C<snd>.
626		652
627	Monitoring-actions are one-shot: once messages are lost (and a monitoring	653	Monitoring-actions are one-shot: once messages are lost (and a monitoring
628	alert was raised), they are removed and will not trigger again.	654	alert was raised), they are removed and will not trigger again, even if it
		655	turns out that the port is still alive.
629		656
630	As a rule of thumb, monitoring requests should always monitor a port from	657	As a rule of thumb, monitoring requests should always monitor a remote
631	a local port (or callback). The reason is that kill messages might get	658	port locally (using a local C<$rcvport> or a callback). The reason is that
632	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
633	even monitoring requests can get lost (for example, when the connection	660	obvious reason is that even monitoring requests can get lost (for example,
634	to the other node goes down permanently). When monitoring a port locally	661	when the connection to the other node goes down permanently). When
635	these problems do not exist.	662	monitoring a port locally these problems do not exist.
636		663
637	C<mon> effectively guarantees that, in the absence of hardware failures,	664	C<mon> effectively guarantees that, in the absence of hardware failures,
638	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
639	arrive, or the monitoring action will be invoked after possible message	666	arrive, or the monitoring action will be invoked after possible message
640	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
…		…
731	will be reported as reason C<< die => $@ >>.	758	will be reported as reason C<< die => $@ >>.
732		759
733	Transport/communication errors are reported as C<< transport_error =>	760	Transport/communication errors are reported as C<< transport_error =>
734	$message >>.	761	$message >>.
735		762
736	=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: $!";
737		774
738	=item $port = spawn $node, $initfunc[, @initdata]	775	=item $port = spawn $node, $initfunc[, @initdata]
739		776
740	Creates a port on the node C<$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
741	case it's the node where that port resides).	778	case it's the node where that port resides).
…		…
833	ref $action[0]	870	ref $action[0]
834	? $action[0]()	871	? $action[0]()
835	: snd @action;	872	: snd @action;
836	};	873	};
837	}	874	}
		875
		876	#=item $cb2 = timeout $seconds, $cb[, @args]
838		877
839	=item cal $port, @msg, $callback[, $timeout]	878	=item cal $port, @msg, $callback[, $timeout]
840		879
841	A simple form of RPC - sends a message to the given C<$port> with the	880	A simple form of RPC - sends a message to the given C<$port> with the
842	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.
…		…
891	=back	930	=back
892		931
893	=head1 DISTRIBUTED DATABASE	932	=head1 DISTRIBUTED DATABASE
894		933
895	AnyEvent::MP comes with a simple distributed database. The database will	934	AnyEvent::MP comes with a simple distributed database. The database will
896	be mirrored asynchronously at all global nodes. Other nodes bind to one of	935	be mirrored asynchronously on all global nodes. Other nodes bind to one
897	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.
898		939
899	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
900	contains values.	941	contains hashes which contain values, similarly to a perl hash of hashes,
		942	i.e.:
		943
		944	$DATABASE{$family}{$subkey} = $value
901		945
902	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
903	is called "subkey" or simply "key".	947	is called "subkey" or simply "key".
904		948
905	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
…		…
910	with the name of the application or module using it.	954	with the name of the application or module using it.
911		955
912	The subkeys must be non-empty strings, with no further restrictions.	956	The subkeys must be non-empty strings, with no further restrictions.
913		957
914	The values should preferably be strings, but other perl scalars should	958	The values should preferably be strings, but other perl scalars should
915	work as well (such as undef, arrays and hashes).	959	work as well (such as C<undef>, arrays and hashes).
916		960
917	Every database entry is owned by one node - adding the same family/subkey	961	Every database entry is owned by one node - adding the same family/subkey
918	combination on multiple nodes will not cause discomfort for AnyEvent::MP,	962	combination on multiple nodes will not cause discomfort for AnyEvent::MP,
919	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
920	different values on different nodes.	964	different values on different nodes.
…		…
924	pools. For example, a worker port for image scaling might do this:	968	pools. For example, a worker port for image scaling might do this:
925		969
926	db_set my_image_scalers => $port;	970	db_set my_image_scalers => $port;
927		971
928	And clients looking for an image scaler will want to get the	972	And clients looking for an image scaler will want to get the
929	C<my_image_scalers> keys:	973	C<my_image_scalers> keys from time to time:
930		974
931	db_keys "my_image_scalers" => 60 => sub {	975	db_keys my_image_scalers => sub {
932	#d##TODO#	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.
933		991
934	=over	992	=over
935		993
936	=item db_set $family => $subkey [=> $value]	994	=item $guard = db_set $family => $subkey [=> $value]
937		995
938	Sets (or replaces) a key to the database - if C<$value> is omitted,	996	Sets (or replaces) a key to the database - if C<$value> is omitted,
939	C<undef> is used instead.	997	C<undef> is used instead.
940		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
941	=item db_del $family => $subkey	1002	=item db_del $family => $subkey...
942		1003
943	Deletes a key from the database.	1004	Deletes one or more subkeys from the database family.
944		1005
945	=item $guard = db_reg $family => $subkey [=> $value]	1006	=item $guard = db_reg $family => $port => $value
946		1007
947	Sets the key on the database and returns a guard. When the guard is	1008	=item $guard = db_reg $family => $port
948	destroyed, the key is deleted from the database. If C<$value> is missing,	1009
949	then C<undef> is used.	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	};
950		1109
951	=cut	1110	=cut
952		1111
953	=back	1112	=back
954		1113
…		…
999	filter messages without dequeuing them.	1158	filter messages without dequeuing them.
1000		1159
1001	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
1002	being event-based, while Erlang is process-based.	1161	being event-based, while Erlang is process-based.
1003		1162
1004	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
1005	top of AEMP and Coro threads.	1164	top of AEMP and Coro threads.
1006		1165
1007	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	1166	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
1008		1167
1009	Sending messages in Erlang is synchronous and blocks the process until	1168	Sending messages in Erlang is synchronous and blocks the process until
1010	a conenction has been established and the message sent (and so does not	1169	a connection has been established and the message sent (and so does not
1011	need a queue that can overflow). AEMP sends return immediately, connection	1170	need a queue that can overflow). AEMP sends return immediately, connection
1012	establishment is handled in the background.	1171	establishment is handled in the background.
1013		1172
1014	=item * Erlang suffers from silent message loss, AEMP does not.	1173	=item * Erlang suffers from silent message loss, AEMP does not.
1015		1174
…		…
1113	Keeping your messages simple, concentrating on data structures rather than	1272	Keeping your messages simple, concentrating on data structures rather than
1114	objects, will keep your messages clean, tidy and efficient.	1273	objects, will keep your messages clean, tidy and efficient.
1115		1274
1116	=back	1275	=back
1117		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
1118	=head1 SEE ALSO	1385	=head1 SEE ALSO
1119		1386
1120	L<AnyEvent::MP::Intro> - a gentle introduction.	1387	L<AnyEvent::MP::Intro> - a gentle introduction.
1121		1388
1122	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1389	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.127 by root, Sat Mar 3 20:35:10 2012 UTC vs. Revision 1.153 by root, Sat Nov 2 01:30:49 2019 UTC

Diff Legend

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.127 by root, Sat Mar 3 20:35:10 2012 UTC vs.
Revision 1.153 by root, Sat Nov 2 01:30:49 2019 UTC