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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.117 by root, Wed Oct 27 06:32:39 2010 UTC vs.
Revision 1.149 by root, Wed Aug 17 19:44:07 2016 UTC

…		…
35	# destroy a port again	35	# destroy a port again
36	kil $port; # "normal" kill	36	kil $port; # "normal" kill
37	kil $port, my_error => "everything is broken"; # error kill	37	kil $port, my_error => "everything is broken"; # error kill
38		38
39	# monitoring	39	# monitoring
40	mon $localport, $cb->(@msg) # callback is invoked on death	40	mon $port, $cb->(@msg) # callback is invoked on death
41	mon $localport, $otherport # kill otherport on abnormal death	41	mon $port, $localport # kill localport on abnormal death
42	mon $localport, $otherport, @msg # send message on death	42	mon $port, $localport, @msg # send message on death
43		43
44	# temporarily execute code in port context	44	# temporarily execute code in port context
45	peval $port, sub { die "kill the port!" };	45	peval $port, sub { die "kill the port!" };
46		46
47	# execute callbacks in $SELF port context	47	# execute callbacks in $SELF port context
48	my $timer = AE::timer 1, 0, psub {	48	my $timer = AE::timer 1, 0, psub {
49	die "kill the port, delayed";	49	die "kill the port, delayed";
50	};	50	};
51		51
52	=head1 CURRENT STATUS	52	# distributed database - modification
		53	db_set $family => $subkey [=> $value] # add a subkey
		54	db_del $family => $subkey... # delete one or more subkeys
		55	db_reg $family => $port [=> $value] # register a port
53		56
54	bin/aemp - stable.	57	# distributed database - queries
55	AnyEvent::MP - stable API, should work.	58	db_family $family => $cb->(\%familyhash)
56	AnyEvent::MP::Intro - explains most concepts.	59	db_keys $family => $cb->(\@keys)
57	AnyEvent::MP::Kernel - mostly stable API.	60	db_values $family => $cb->(\@values)
58	AnyEvent::MP::Global - stable API.	61
		62	# distributed database - monitoring a family
		63	db_mon $family => $cb->(\%familyhash, \@added, \@changed, \@deleted)
59		64
60	=head1 DESCRIPTION	65	=head1 DESCRIPTION
61		66
62	This module (-family) implements a simple message passing framework.	67	This module (-family) implements a simple message passing framework.
63		68
…		…
78		83
79	Ports allow you to register C<rcv> handlers that can match all or just	84	Ports allow you to register C<rcv> handlers that can match all or just
80	some messages. Messages send to ports will not be queued, regardless of	85	some messages. Messages send to ports will not be queued, regardless of
81	anything was listening for them or not.	86	anything was listening for them or not.
82		87
		88	Ports are represented by (printable) strings called "port IDs".
		89
83	=item port ID - C<nodeid#portname>	90	=item port ID - C<nodeid#portname>
84		91
85	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<#>)
86	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).
87		95
88	=item node	96	=item node
89		97
90	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,
91	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
92	ports.	100	ports.
93		101
94	Nodes are either public (have one or more listening ports) or private	102	Nodes are either public (have one or more listening ports) or private
95	(no listening ports). Private nodes cannot talk to other private nodes	103	(no listening ports). Private nodes cannot talk to other private nodes
96	currently.	104	currently, but all nodes can talk to public nodes.
		105
		106	Nodes is represented by (printable) strings called "node IDs".
97		107
98	=item node ID - C<[A-Za-z0-9_\-.:]*>	108	=item node ID - C<[A-Za-z0-9_\-.:]*>
99		109
100	A node ID is a string that uniquely identifies the node within a	110	A node ID is a string that uniquely identifies the node within a
101	network. Depending on the configuration used, node IDs can look like a	111	network. Depending on the configuration used, node IDs can look like a
102	hostname, a hostname and a port, or a random string. AnyEvent::MP itself	112	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
103	doesn't interpret node IDs in any way.	113	doesn't interpret node IDs in any way except to uniquely identify a node.
104		114
105	=item binds - C<ip:port>	115	=item binds - C<ip:port>
106		116
107	Nodes can only talk to each other by creating some kind of connection to	117	Nodes can only talk to each other by creating some kind of connection to
108	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
		119	endpoints - binds.
		120
109	endpoints - binds. Currently, only standard C<ip:port> specifications can	121	Currently, only standard C<ip:port> specifications can be used, which
110	be used, which specify TCP ports to listen on.	122	specify TCP ports to listen on. So a bind is basically just a tcp socket
		123	in listening mode that accepts connections from other nodes.
111		124
112	=item seed nodes	125	=item seed nodes
113		126
114	When a node starts, it knows nothing about the network. To teach the node	127	When a node starts, it knows nothing about the network it is in - it
115	about the network it first has to contact some other node within the	128	needs to connect to at least one other node that is already in the
116	network. This node is called a seed.	129	network. These other nodes are called "seed nodes".
117		130
118	Apart from the fact that other nodes know them as seed nodes and they have	131	Seed nodes themselves are not special - they are seed nodes only because
119	to have fixed listening addresses, seed nodes are perfectly normal nodes -	132	some other node I<uses> them as such, but any node can be used as seed
120	any node can function as a seed node for others.	133	node for other nodes, and eahc node can use a different set of seed nodes.
121		134
122	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
123	maintain the network and to connect nodes that otherwise would have	136	maintain the network - all nodes using the same seed node are part of the
124	trouble connecting. They form the backbone of an AnyEvent::MP network.	137	same network. If a network is split into multiple subnets because e.g. the
		138	network link between the parts goes down, then using the same seed nodes
		139	for all nodes ensures that eventually the subnets get merged again.
125		140
126	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
127	should always be available. They should also be relatively responsive - a	142	should always be available. They should also be relatively responsive - a
128	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.
129		144
		145	For small networks, it's best if every node uses the same set of seed
		146	nodes. For large networks, it can be useful to specify "regional" seed
		147	nodes for most nodes in an area, and use all seed nodes as seed nodes for
		148	each other. What's important is that all seed nodes connections form a
		149	complete graph, so that the network cannot split into separate subnets
		150	forever.
		151
		152	Seed nodes are represented by seed IDs.
		153
130	=item seeds - C<host:port>	154	=item seed IDs - C<host:port>
131		155
132	Seeds are transport endpoint(s) (usually a hostname/IP address and a	156	Seed IDs are transport endpoint(s) (usually a hostname/IP address and a
133	TCP port) of nodes that should be used as seed nodes.	157	TCP port) of nodes that should be used as seed nodes.
134		158
135	The nodes listening on those endpoints are expected to be long-running,	159	=item global nodes
136	and at least one of those should always be available. When nodes run out	160
137	of connections (e.g. due to a network error), they try to re-establish	161	An AEMP network needs a discovery service - nodes need to know how to
138	connections to some seednodes again to join the network.	162	connect to other nodes they only know by name. In addition, AEMP offers a
		163	distributed "group database", which maps group names to a list of strings
		164	- for example, to register worker ports.
		165
		166	A network needs at least one global node to work, and allows every node to
		167	be a global node.
		168
		169	Any node that loads the L<AnyEvent::MP::Global> module becomes a global
		170	node and tries to keep connections to all other nodes. So while it can
		171	make sense to make every node "global" in small networks, it usually makes
		172	sense to only make seed nodes into global nodes in large networks (nodes
		173	keep connections to seed nodes and global nodes, so making them the same
		174	reduces overhead).
139		175
140	=back	176	=back
141		177
142	=head1 VARIABLES/FUNCTIONS	178	=head1 VARIABLES/FUNCTIONS
143		179
…		…
145		181
146	=cut	182	=cut
147		183
148	package AnyEvent::MP;	184	package AnyEvent::MP;
149		185
		186	use AnyEvent::MP::Config ();
150	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	);
151		199
152	use common::sense;	200	use common::sense;
153		201
154	use Carp ();	202	use Carp ();
155		203
156	use AE ();	204	use AnyEvent ();
		205	use Guard ();
157		206
158	use base "Exporter";	207	use base "Exporter";
159		208
160	our $VERSION = 1.29;	209	our $VERSION = $AnyEvent::MP::Config::VERSION;
161		210
162	our @EXPORT = qw(	211	our @EXPORT = qw(
163	NODE $NODE *SELF node_of after	212	NODE $NODE
164	configure	213	configure
		214	node_of port_is_local
		215	snd kil
		216	db_set db_del
		217	db_mon db_family db_keys db_values
		218
		219	*SELF
		220
165	snd rcv mon mon_guard kil psub peval spawn cal	221	port rcv mon mon_guard psub peval spawn cal
166	port	222	db_set db_del db_reg
		223	db_mon db_family db_keys db_values
		224
		225	after
167	);	226	);
168		227
169	our $SELF;	228	our $SELF;
170		229
171	sub _self_die() {	230	sub _self_die() {
…		…
182		241
183	=item $nodeid = node_of $port	242	=item $nodeid = node_of $port
184		243
185	Extracts and returns the node ID from a port ID or a node ID.	244	Extracts and returns the node ID from a port ID or a node ID.
186		245
		246	=item $is_local = port_is_local $port
		247
		248	Returns true iff the port is a local port.
		249
187	=item configure $profile, key => value...	250	=item configure $profile, key => value...
188		251
189	=item configure key => value...	252	=item configure key => value...
190		253
191	Before a node can talk to other nodes on the network (i.e. enter	254	Before a node can talk to other nodes on the network (i.e. enter
192	"distributed mode") it has to configure itself - the minimum a node needs	255	"distributed mode") it has to configure itself - the minimum a node needs
193	to know is its own name, and optionally it should know the addresses of	256	to know is its own name, and optionally it should know the addresses of
194	some other nodes in the network to discover other nodes.	257	some other nodes in the network to discover other nodes.
195		258
196	The key/value pairs are basically the same ones as documented for the
197	F<aemp> command line utility (sans the set/del prefix).
198
199	This function configures a node - it must be called exactly once (or	259	This function configures a node - it must be called exactly once (or
200	never) before calling other AnyEvent::MP functions.	260	never) before calling other AnyEvent::MP functions.
		261
		262	The key/value pairs are basically the same ones as documented for the
		263	F<aemp> command line utility (sans the set/del prefix), with these additions:
		264
		265	=over 4
		266
		267	=item norc => $boolean (default false)
		268
		269	If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not>
		270	be consulted - all configuration options must be specified in the
		271	C<configure> call.
		272
		273	=item force => $boolean (default false)
		274
		275	IF true, then the values specified in the C<configure> will take
		276	precedence over any values configured via the rc file. The default is for
		277	the rc file to override any options specified in the program.
		278
		279	=back
201		280
202	=over 4	281	=over 4
203		282
204	=item step 1, gathering configuration from profiles	283	=item step 1, gathering configuration from profiles
205		284
…		…
219	That means that the values specified in the profile have highest priority	298	That means that the values specified in the profile have highest priority
220	and the values specified directly via C<configure> have lowest priority,	299	and the values specified directly via C<configure> have lowest priority,
221	and can only be used to specify defaults.	300	and can only be used to specify defaults.
222		301
223	If the profile specifies a node ID, then this will become the node ID of	302	If the profile specifies a node ID, then this will become the node ID of
224	this process. If not, then the profile name will be used as node ID. The	303	this process. If not, then the profile name will be used as node ID, with
225	special node ID of C<anon/> will be replaced by a random node ID.	304	a unique randoms tring (C</%u>) appended.
		305
		306	The node ID can contain some C<%> sequences that are expanded: C<%n>
		307	is expanded to the local nodename, C<%u> is replaced by a random
		308	strign to make the node unique. For example, the F<aemp> commandline
		309	utility uses C<aemp/%n/%u> as nodename, which might expand to
		310	C<aemp/cerebro/ZQDGSIkRhEZQDGSIkRhE>.
226		311
227	=item step 2, bind listener sockets	312	=item step 2, bind listener sockets
228		313
229	The next step is to look up the binds in the profile, followed by binding	314	The next step is to look up the binds in the profile, followed by binding
230	aemp protocol listeners on all binds specified (it is possible and valid	315	aemp protocol listeners on all binds specified (it is possible and valid
231	to have no binds, meaning that the node cannot be contacted form the	316	to have no binds, meaning that the node cannot be contacted from the
232	outside. This means the node cannot talk to other nodes that also have no	317	outside. This means the node cannot talk to other nodes that also have no
233	binds, but it can still talk to all "normal" nodes).	318	binds, but it can still talk to all "normal" nodes).
234		319
235	If the profile does not specify a binds list, then a default of C<*> is	320	If the profile does not specify a binds list, then a default of C<*> is
236	used, meaning the node will bind on a dynamically-assigned port on every	321	used, meaning the node will bind on a dynamically-assigned port on every
237	local IP address it finds.	322	local IP address it finds.
238		323
239	=item step 3, connect to seed nodes	324	=item step 3, connect to seed nodes
240		325
241	As the last step, the seeds list from the profile is passed to the	326	As the last step, the seed ID list from the profile is passed to the
242	L<AnyEvent::MP::Global> module, which will then use it to keep	327	L<AnyEvent::MP::Global> module, which will then use it to keep
243	connectivity with at least one node at any point in time.	328	connectivity with at least one node at any point in time.
244		329
245	=back	330	=back
246		331
247	Example: become a distributed node using the local node name as profile.	332	Example: become a distributed node using the local node name as profile.
248	This should be the most common form of invocation for "daemon"-type nodes.	333	This should be the most common form of invocation for "daemon"-type nodes.
249		334
250	configure	335	configure
251		336
252	Example: become an anonymous node. This form is often used for commandline	337	Example: become a semi-anonymous node. This form is often used for
253	clients.	338	commandline clients.
254		339
255	configure nodeid => "anon/";	340	configure nodeid => "myscript/%n/%u";
256		341
257	Example: configure a node using a profile called seed, which si suitable	342	Example: configure a node using a profile called seed, which is suitable
258	for a seed node as it binds on all local addresses on a fixed port (4040,	343	for a seed node as it binds on all local addresses on a fixed port (4040,
259	customary for aemp).	344	customary for aemp).
260		345
261	# use the aemp commandline utility	346	# use the aemp commandline utility
262	# aemp profile seed nodeid anon/ binds '*:4040'	347	# aemp profile seed binds '*:4040'
263		348
264	# then use it	349	# then use it
265	configure profile => "seed";	350	configure profile => "seed";
266		351
267	# or simply use aemp from the shell again:	352	# or simply use aemp from the shell again:
…		…
332		417
333	=cut	418	=cut
334		419
335	sub rcv($@);	420	sub rcv($@);
336		421
337	sub _kilme {	422	my $KILME = sub {
338	die "received message on port without callback";	423	(my $tag = substr $_[0], 0, 30) =~ s/([\x20-\x7e])/./g;
339	}	424	kil $SELF, unhandled_message => "no callback found for message '$tag'";
		425	};
340		426
341	sub port(;&) {	427	sub port(;&) {
342	my $id = "$UNIQ." . $ID++;	428	my $id = $UNIQ . ++$ID;
343	my $port = "$NODE#$id";	429	my $port = "$NODE#$id";
344		430
345	rcv $port, shift \|\| \&_kilme;	431	rcv $port, shift \|\| $KILME;
346		432
347	$port	433	$port
348	}	434	}
349		435
350	=item rcv $local_port, $callback->(@msg)	436	=item rcv $local_port, $callback->(@msg)
…		…
355		441
356	The global C<$SELF> (exported by this module) contains C<$port> while	442	The global C<$SELF> (exported by this module) contains C<$port> while
357	executing the callback. Runtime errors during callback execution will	443	executing the callback. Runtime errors during callback execution will
358	result in the port being C<kil>ed.	444	result in the port being C<kil>ed.
359		445
360	The default callback received all messages not matched by a more specific	446	The default callback receives all messages not matched by a more specific
361	C<tag> match.	447	C<tag> match.
362		448
363	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...	449	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
364		450
365	Register (or replace) callbacks to be called on messages starting with the	451	Register (or replace) callbacks to be called on messages starting with the
…		…
400		486
401	sub rcv($@) {	487	sub rcv($@) {
402	my $port = shift;	488	my $port = shift;
403	my ($nodeid, $portid) = split /#/, $port, 2;	489	my ($nodeid, $portid) = split /#/, $port, 2;
404		490
405	$NODE{$nodeid} == $NODE{""}	491	$nodeid eq $NODE
406	or Carp::croak "$port: rcv can only be called on local ports, caught";	492	or Carp::croak "$port: rcv can only be called on local ports, caught";
407		493
408	while (@_) {	494	while (@_) {
409	if (ref $_[0]) {	495	if (ref $_[0]) {
410	if (my $self = $PORT_DATA{$portid}) {	496	if (my $self = $PORT_DATA{$portid}) {
…		…
454	}	540	}
455		541
456	=item peval $port, $coderef[, @args]	542	=item peval $port, $coderef[, @args]
457		543
458	Evaluates the given C<$codref> within the contetx of C<$port>, that is,	544	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
459	when the code throews an exception the C<$port> will be killed.	545	when the code throws an exception the C<$port> will be killed.
460		546
461	Any remaining args will be passed to the callback. Any return values will	547	Any remaining args will be passed to the callback. Any return values will
462	be returned to the caller.	548	be returned to the caller.
463		549
464	This is useful when you temporarily want to execute code in the context of	550	This is useful when you temporarily want to execute code in the context of
…		…
529	$res	615	$res
530	}	616	}
531	}	617	}
532	}	618	}
533		619
		620	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		621
		622	=item $guard = mon $port # kill $SELF when $port dies
		623
534	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies	624	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
535
536	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
537
538	=item $guard = mon $port # kill $SELF when $port dies
539		625
540	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies	626	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
541		627
542	Monitor the given port and do something when the port is killed or	628	Monitor the given port and do something when the port is killed or
543	messages to it were lost, and optionally return a guard that can be used	629	messages to it were lost, and optionally return a guard that can be used
544	to stop monitoring again.	630	to stop monitoring again.
545		631
		632	The first two forms distinguish between "normal" and "abnormal" kil's:
		633
		634	In the first form (another port given), if the C<$port> is C<kil>'ed with
		635	a non-empty reason, the other port (C<$rcvport>) will be kil'ed with the
		636	same reason. That is, on "normal" kil's nothing happens, while under all
		637	other conditions, the other port is killed with the same reason.
		638
		639	The second form (kill self) is the same as the first form, except that
		640	C<$rvport> defaults to C<$SELF>.
		641
		642	The remaining forms don't distinguish between "normal" and "abnormal" kil's
		643	- it's up to the callback or receiver to check whether the C<@reason> is
		644	empty and act accordingly.
		645
546	In the first form (callback), the callback is simply called with any	646	In the third form (callback), the callback is simply called with any
547	number of C<@reason> elements (no @reason means that the port was deleted	647	number of C<@reason> elements (empty @reason means that the port was deleted
548	"normally"). Note also that I<< the callback B<must> never die >>, so use	648	"normally"). Note also that I<< the callback B<must> never die >>, so use
549	C<eval> if unsure.	649	C<eval> if unsure.
550		650
551	In the second form (another port given), the other port (C<$rcvport>)
552	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
553	"normal" kils nothing happens, while under all other conditions, the other
554	port is killed with the same reason.
555
556	The third form (kill self) is the same as the second form, except that
557	C<$rvport> defaults to C<$SELF>.
558
559	In the last form (message), a message of the form C<@msg, @reason> will be	651	In the last form (message), a message of the form C<$rcvport, @msg,
560	C<snd>.	652	@reason> will be C<snd>.
561		653
562	Monitoring-actions are one-shot: once messages are lost (and a monitoring	654	Monitoring-actions are one-shot: once messages are lost (and a monitoring
563	alert was raised), they are removed and will not trigger again.	655	alert was raised), they are removed and will not trigger again, even if it
		656	turns out that the port is still alive.
564		657
565	As a rule of thumb, monitoring requests should always monitor a port from	658	As a rule of thumb, monitoring requests should always monitor a remote
566	a local port (or callback). The reason is that kill messages might get	659	port locally (using a local C<$rcvport> or a callback). The reason is that
567	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
568	even monitoring requests can get lost (for example, when the connection	661	obvious reason is that even monitoring requests can get lost (for example,
569	to the other node goes down permanently). When monitoring a port locally	662	when the connection to the other node goes down permanently). When
570	these problems do not exist.	663	monitoring a port locally these problems do not exist.
571		664
572	C<mon> effectively guarantees that, in the absence of hardware failures,	665	C<mon> effectively guarantees that, in the absence of hardware failures,
573	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
574	arrive, or the monitoring action will be invoked after possible message	667	arrive, or the monitoring action will be invoked after possible message
575	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
…		…
620	}	713	}
621		714
622	$node->monitor ($port, $cb);	715	$node->monitor ($port, $cb);
623		716
624	defined wantarray	717	defined wantarray
625	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })	718	and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) })
626	}	719	}
627		720
628	=item $guard = mon_guard $port, $ref, $ref...	721	=item $guard = mon_guard $port, $ref, $ref...
629		722
630	Monitors the given C<$port> and keeps the passed references. When the port	723	Monitors the given C<$port> and keeps the passed references. When the port
…		…
666	will be reported as reason C<< die => $@ >>.	759	will be reported as reason C<< die => $@ >>.
667		760
668	Transport/communication errors are reported as C<< transport_error =>	761	Transport/communication errors are reported as C<< transport_error =>
669	$message >>.	762	$message >>.
670		763
671	=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: $!";
672		775
673	=item $port = spawn $node, $initfunc[, @initdata]	776	=item $port = spawn $node, $initfunc[, @initdata]
674		777
675	Creates a port on the node C<$node> (which can also be a port ID, in which	778	Creates a port on the node C<$node> (which can also be a port ID, in which
676	case it's the node where that port resides).	779	case it's the node where that port resides).
…		…
734	}	837	}
735		838
736	sub spawn(@) {	839	sub spawn(@) {
737	my ($nodeid, undef) = split /#/, shift, 2;	840	my ($nodeid, undef) = split /#/, shift, 2;
738		841
739	my $id = "$RUNIQ." . $ID++;	842	my $id = $RUNIQ . ++$ID;
740		843
741	$_[0] =~ /::/	844	$_[0] =~ /::/
742	or Carp::croak "spawn init function must be a fully-qualified name, caught";	845	or Carp::croak "spawn init function must be a fully-qualified name, caught";
743		846
744	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;	847	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
745		848
746	"$nodeid#$id"	849	"$nodeid#$id"
747	}	850	}
		851
748		852
749	=item after $timeout, @msg	853	=item after $timeout, @msg
750		854
751	=item after $timeout, $callback	855	=item after $timeout, $callback
752		856
…		…
767	ref $action[0]	871	ref $action[0]
768	? $action[0]()	872	? $action[0]()
769	: snd @action;	873	: snd @action;
770	};	874	};
771	}	875	}
		876
		877	#=item $cb2 = timeout $seconds, $cb[, @args]
772		878
773	=item cal $port, @msg, $callback[, $timeout]	879	=item cal $port, @msg, $callback[, $timeout]
774		880
775	A simple form of RPC - sends a message to the given C<$port> with the	881	A simple form of RPC - sends a message to the given C<$port> with the
776	given contents (C<@msg>), but adds a reply port to the message.	882	given contents (C<@msg>), but adds a reply port to the message.
…		…
822	$port	928	$port
823	}	929	}
824		930
825	=back	931	=back
826		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
827	=head1 AnyEvent::MP vs. Distributed Erlang	1115	=head1 AnyEvent::MP vs. Distributed Erlang
828		1116
829	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
830	== 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
831	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
…		…
862	ports being the special case/exception, where transport errors cannot	1150	ports being the special case/exception, where transport errors cannot
863	occur.	1151	occur.
864		1152
865	=item * Erlang uses processes and a mailbox, AEMP does not queue.	1153	=item * Erlang uses processes and a mailbox, AEMP does not queue.
866		1154
867	Erlang uses processes that selectively receive messages, and therefore	1155	Erlang uses processes that selectively receive messages out of order, and
868	needs a queue. AEMP is event based, queuing messages would serve no	1156	therefore needs a queue. AEMP is event based, queuing messages would serve
869	useful purpose. For the same reason the pattern-matching abilities of	1157	no useful purpose. For the same reason the pattern-matching abilities
870	AnyEvent::MP are more limited, as there is little need to be able to	1158	of AnyEvent::MP are more limited, as there is little need to be able to
871	filter messages without dequeuing them.	1159	filter messages without dequeuing them.
872		1160
873	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	1161	This is not a philosophical difference, but simply stems from AnyEvent::MP
		1162	being event-based, while Erlang is process-based.
		1163
		1164	You can have a look at L<Coro::MP> for a more Erlang-like process model on
		1165	top of AEMP and Coro threads.
874		1166
875	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	1167	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
876		1168
877	Sending messages in Erlang is synchronous and blocks the process (and	1169	Sending messages in Erlang is synchronous and blocks the process until
		1170	a connection has been established and the message sent (and so does not
878	so does not need a queue that can overflow). AEMP sends are immediate,	1171	need a queue that can overflow). AEMP sends return immediately, connection
879	connection establishment is handled in the background.	1172	establishment is handled in the background.
880		1173
881	=item * Erlang suffers from silent message loss, AEMP does not.	1174	=item * Erlang suffers from silent message loss, AEMP does not.
882		1175
883	Erlang implements few guarantees on messages delivery - messages can get	1176	Erlang implements few guarantees on messages delivery - messages can get
884	lost without any of the processes realising it (i.e. you send messages a,	1177	lost without any of the processes realising it (i.e. you send messages a,
…		…
887	AEMP guarantees (modulo hardware errors) correct ordering, and the	1180	AEMP guarantees (modulo hardware errors) correct ordering, and the
888	guarantee that after one message is lost, all following ones sent to the	1181	guarantee that after one message is lost, all following ones sent to the
889	same port are lost as well, until monitoring raises an error, so there are	1182	same port are lost as well, until monitoring raises an error, so there are
890	no silent "holes" in the message sequence.	1183	no silent "holes" in the message sequence.
891		1184
		1185	If you want your software to be very reliable, you have to cope with
		1186	corrupted and even out-of-order messages in both Erlang and AEMP. AEMP
		1187	simply tries to work better in common error cases, such as when a network
		1188	link goes down.
		1189
892	=item * Erlang can send messages to the wrong port, AEMP does not.	1190	=item * Erlang can send messages to the wrong port, AEMP does not.
893		1191
894	In Erlang it is quite likely that a node that restarts reuses a process ID	1192	In Erlang it is quite likely that a node that restarts reuses an Erlang
895	known to other nodes for a completely different process, causing messages	1193	process ID known to other nodes for a completely different process,
896	destined for that process to end up in an unrelated process.	1194	causing messages destined for that process to end up in an unrelated
		1195	process.
897		1196
898	AEMP never reuses port IDs, so old messages or old port IDs floating	1197	AEMP does not reuse port IDs, so old messages or old port IDs floating
899	around in the network will not be sent to an unrelated port.	1198	around in the network will not be sent to an unrelated port.
900		1199
901	=item * Erlang uses unprotected connections, AEMP uses secure	1200	=item * Erlang uses unprotected connections, AEMP uses secure
902	authentication and can use TLS.	1201	authentication and can use TLS.
903		1202
…		…
906		1205
907	=item * The AEMP protocol is optimised for both text-based and binary	1206	=item * The AEMP protocol is optimised for both text-based and binary
908	communications.	1207	communications.
909		1208
910	The AEMP protocol, unlike the Erlang protocol, supports both programming	1209	The AEMP protocol, unlike the Erlang protocol, supports both programming
911	language independent text-only protocols (good for debugging) and binary,	1210	language independent text-only protocols (good for debugging), and binary,
912	language-specific serialisers (e.g. Storable). By default, unless TLS is	1211	language-specific serialisers (e.g. Storable). By default, unless TLS is
913	used, the protocol is actually completely text-based.	1212	used, the protocol is actually completely text-based.
914		1213
915	It has also been carefully designed to be implementable in other languages	1214	It has also been carefully designed to be implementable in other languages
916	with a minimum of work while gracefully degrading functionality to make the	1215	with a minimum of work while gracefully degrading functionality to make the
917	protocol simple.	1216	protocol simple.
918		1217
919	=item * AEMP has more flexible monitoring options than Erlang.	1218	=item * AEMP has more flexible monitoring options than Erlang.
920		1219
921	In Erlang, you can chose to receive I<all> exit signals as messages	1220	In Erlang, you can chose to receive I<all> exit signals as messages or
922	or I<none>, there is no in-between, so monitoring single processes is	1221	I<none>, there is no in-between, so monitoring single Erlang processes is
923	difficult to implement. Monitoring in AEMP is more flexible than in	1222	difficult to implement.
924	Erlang, as one can choose between automatic kill, exit message or callback	1223
925	on a per-process basis.	1224	Monitoring in AEMP is more flexible than in Erlang, as one can choose
		1225	between automatic kill, exit message or callback on a per-port basis.
926		1226
927	=item * Erlang tries to hide remote/local connections, AEMP does not.	1227	=item * Erlang tries to hide remote/local connections, AEMP does not.
928		1228
929	Monitoring in Erlang is not an indicator of process death/crashes, in the	1229	Monitoring in Erlang is not an indicator of process death/crashes, in the
930	same way as linking is (except linking is unreliable in Erlang).	1230	same way as linking is (except linking is unreliable in Erlang).
…		…
973	Keeping your messages simple, concentrating on data structures rather than	1273	Keeping your messages simple, concentrating on data structures rather than
974	objects, will keep your messages clean, tidy and efficient.	1274	objects, will keep your messages clean, tidy and efficient.
975		1275
976	=back	1276	=back
977		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 contetx hierarchy for AnyEvent::MP modules, it will receive
		1384	all log messages by submodules.
		1385
978	=head1 SEE ALSO	1386	=head1 SEE ALSO
979		1387
980	L<AnyEvent::MP::Intro> - a gentle introduction.	1388	L<AnyEvent::MP::Intro> - a gentle introduction.
981		1389
982	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 1.117 by root, Wed Oct 27 06:32:39 2010 UTC vs. Revision 1.149 by root, Wed Aug 17 19:44:07 2016 UTC

Diff Legend

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.117 by root, Wed Oct 27 06:32:39 2010 UTC vs.
Revision 1.149 by root, Wed Aug 17 19:44:07 2016 UTC